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Abstract The authors present the multi‐physical field performances comparative research for a 30 kW, 30,000 r/min high‐speed permanent magnet motor (HSPMM) when the motor is powered by the sinusoidal pulse width modulation (SPWM) voltage inverter and sinusoidal voltage source, respectively. Firstly, electromagnetic performances including torque, voltage and current of the HSPMM with different driving methods are compared and analysed by the finite element method (FEM). Considering the effects of high operation frequency, power losses of the HSPMM with different driving methods under full‐load conditions are calculated and compared with the skin effect and the proximity effect considered for HSPMM winding copper loss estimation. Based on the above analysis, a prototype driven by the SPWM voltage inverter is manufactured, with its electromagnetic and thermal performances tested and verified. In addition, several influencing factors of the HSPMM rotor eddy current loss are studied, with their effects on the HSPMM under different driving methods further analysed and compared as well. A novel equivalent power supply method is proposed to effectively save the calculation time with a negligible error. Finally, in order to further improve the heat dissipation capacity of the HSPMM, a novel cooling method is intensively studied with its influencing factors further analysed. The cooling effect of the novel cooling method and the temperature of the motor components are verified and calculated by the computational fluid dynamics (CFD) method.

Abstract Large‐scale design optimisation techniques enable the design of high‐performance electric machines. Electromagnetic 3D finite element analysis (FEA) is typically employed in optimisation studies for accurate analysis of axial flux permanent magnet (AFPM) machines, which require extensive computational resources. To reduce the computational burden, a FEA‐based mathematical method relying on the geometric and magnetic symmetry of coreless AFPM machines is proposed to estimate the machine performance indicators using the least number of FEA solutions, thereby significantly lowering the running time. This method is generally applicable to AFPM machines with low saturation effects and cogging torque as exemplified for a printed circuit board (PCB) stator coreless AFPM machine. To further reduce the computation time, a systematically simplified equivalent 3D FEA model for planar PCB coils integrated with this machine is also proposed. The practical implementation of the introduced method is elaborated based on an example optimisation study, and an analytical method for fast design scaling is also discussed. The results of the proposed approach are compared with detailed transient FEA results, and a prototype 26‐pole PCB stator coreless AFPM machine was also used to validate the results experimentally.

Abstract Machine acoustics is an important area of research impacting the quality and comfort of human life. With increased levels of electrification and the wider use of electric motors, the contribution of motor drives towards quieter acoustic systems becomes increasingly important. This paper presents a novel acoustic improvement method involving the use of acoustic waves generated from High Frequency Injection to perform Active Noise Control. Although High Frequency Injection has been used widely in the domain of sensorless motor control, its acoustic generation process has been so far perceived as a negative by‐product. This paper presents the analysis and experimental results from the application of the proposed method to the Helicopter Electro‐Mechanical Actuation System. Considering the extensive use of motor drives in a number of industries, the proposed practice of High Frequency Injection Active Noise Control can have a significant impact to future applications.

Abstract Accurate calculation of equivalent circuit parameters is a prerequisite for accurately calculating the large‐capacity synchronous condenser parameter model. Due to its special transient operating conditions, the high transient magnetic saturation effect during operation causes the non‐linearity and time‐varying of the equivalent circuit parameters. The field mutual leakage reactance is the critical factor affecting the field current, and the time‐varying of the equivalent circuit parameters is closely related to the field current. However, the existing equivalent circuit parameter calculation methods considering field leakage reactance cannot achieve time‐varying parameters. A calculation method of time‐varying equivalent circuit parameters based on a back propagation neural network algorithm is proposed, which solves the calculation problem of time‐varying equivalent circuit parameters considering field mutual leakage reactance. Then, a 300MVar condenser is taken as the research object, and the proposed method is used to simulate the different operating conditions of the condenser and verified by the finite element method and experiment. The results show that the method improves the calculation accuracy of the equivalent circuit parameter model, reduces the calculation time, and applies to different operating conditions.

Abstract The paper suggests a design and optimisation approach for a consequent‐pole line‐start permanent magnet motor (CPLSPM) with flexible pole arc coefficients and high utilisation of rare‐earth (RE) materials, without the need for a variable frequency drive. The presence of dual‐sided slots and adjustable pole arc coefficient sets CPLSPM apart from other types of motors, making the analysis of its cogging torque more complex. Taking into account the double‐sided slotted and flexible adjustable pole arc coefficient, a cogging torque and airgap flux density model was established, and the influence of the pole arc coefficient on the characteristics of the cogging torque and airgap flux density of CPLSPM was analysed. The authors conduct multidimensional optimisation considering the coupling of multiple parameters to obtain a CPLSPM with minimal RE material usage, low cogging torque and excellent start‐up and steady‐state performance. Finite element simulation data are presented to validate the factors affecting the cogging torque and the feasibility of the proposed less‐magnetic CPLSPM design. Finally, a prototype of a 750 rpm/2.2 kW CPLSPM is built, and performance testing is carried out for comparison, and applied to submersible mixers.

Abstract The use of rare earth elements (REE) in permanent magnets (PMs) raises problems in several domains. The supply chain of these is fragile, the prices have shown volatility and its manufacturing has a bigger impact on climate change when compared to the manufacturing of other PMs. Instead, ferrite PMs have been researched as an alternative. This alternative shows a relatively higher demagnetisation risk when compared to REE PMs. Thus, a detailed study on permanent demagnetisation during winding faults is crucial. The authors use the finite element method to evaluate different machine designs, developed under mechanical constraints, and explore several strategies to mitigate permanent demagnetisation. Also, the importance of avoiding permanent demagnetisation is changed gradually in the optimisation process. The results show that the protection of the PM and performance optimisation are irreconcilable goals. It also highlights the impact of the stator design in decreasing demagnetisation. Additionally, it is shown that the classic notion of avoiding demagnetisation is an ineffective strategy for designing high‐performance machines with ferrite magnets, and instead, it should be integrated into the optimisation process and weighted according to the application demands.

Abstract Despite being a well‐known problem, bearing faults are still one of the major challenges that the industry face. The growing use of voltage source inverters imposed the alertness of possible bearing damage due to their high‐frequency signals. The aim of this paper is to investigate the effect of capacitive discharges on a rolling element bearing to obtain a series of faulty bearings with different deterioration levels. An ageing test bench is built to generate bearing roughness using Electric Discharge Machining. The purpose is to study the effect of operation conditions, such as frequency of drive, amplitude of shaft voltage, radial load level as well as rotational speed, on the capacitive discharge occurrence within the bearing. Having the desire to further understand this phenomenon, the influence of each parameter on the discharge activity and the discharge waveform is analysed. A worst‐case scenario is conducted and applied to a series of bearings. Finally, the bearing damage is examined, and a quantitative fault detection method is presented based on a microscopic inspection of the bearing's surface.

Abstract In order to address the issues of complexity, high cost, large volume, and low reliability associated with traditional H‐bridge cascaded converters when operating under high voltage, high capacity, and dual electric motor loads, the authors propose the utilisation of a nine‐switch converter as an alternative to the conventional H‐bridge converter for implementing cascaded multilevel converters in dual electric motor drive systems. After conducting an analysis and research on the topology and operational control strategy of cascaded multilevel converters based on the nine‐switch converter, a design is presented using six individual nine‐switch converter units to develop a cascaded multilevel converter capable of driving two 3 MW asynchronous electric motors at a 6 kV voltage level. Simulation verification is performed, and a scaled‐down prototype is built for experimental validation. The results demonstrate that, in comparison to traditional H‐bridge cascaded converters, the proposed cascaded multilevel converter can effectively drive dual electric motors at the same or different frequencies while reducing the number of switches to 1/4, the total transformer windings to 1/2, and Direct Current‐side capacitors to 1/6. This improvement enhances system reliability, portability, and load adaptability, thus offering increased versatility in dual electric motor drive applications.

Abstract A mathematical model of co‐axial magnetic gears is given for the prediction of magnetic field distribution and the magnetic forces. The modelling approach is based on the separation of variables method (SVM), Sturm–Liouville problem, and spectral analysis. This method is computationally more efficient and has the ability to account for finite permeability of magnetic saliency. An finite element method (FEM) validation is performed for a case study, and the results are observed to be almost matched. The computational time of the analytical model has been almost in the same order of that of the FEM for a specified rotor position (both in a matter of a second or less); however, when 100 number of rotor positions were accounted in the simulation, the computational time of FEM was increased to 82 s, while the computational complexity of SVM was almost unaffected.

Abstract A systematic definition of an aircraft generator's “available power” (used to supply loads on its DC bus) is given, which is defined in the context of constraints on transient and steady‐state performance. Using a geometric, data‐driven approach, such a characterisation has been achieved, and a new method, called Power availablE Estimation Tool (PEET), has been developed to determine in real‐time whether a given load can be fulfilled at a given time while maintaining power quality. This is an important problem, especially for safety critical electrical systems such as more electric aircraft, for which it is imperative to know a priori whether an added load will result in voltage variations outside of allowed values. PEET is introduced and its conceptual framework is formalised. Lastly, it provides simulation results that illustrate its performance. The results show that the PEET method produces reliable a priori estimates of power availability, and that this can be achieved within time frames that make it applicable in a real‐time implementation.

In order to analyze the loss, temperature rise and the mechanical structural response under the combined magnetic tension and thermal stress of the stator core, the electromagnetic-temperature-stress coupling calculation for the stator core of a synchronous generator is carried out in this paper. Firstly, the core loss and the magnetic pull per unit area are theoretically deduced, followed by an analysis of the core's temperature rise characteristics. On this basis, the mechanical structure response of the core under the coupling excitation of magnetic pull and non-uniform thermal load is obtained. Then, a three-dimensional finite element model of the CS-5 synchronous generator is established. This model calculates the magnetic pull per unit area, loss curve and temperature distribution of the stator core. Furthermore, the deformation, strain and stress of the stator core under the simultaneous action of magnetic tension and thermal load are obtained. The results show that the stator slot temperature is highest when the generator runs stably. The deformation at the groove is largest and the stress at the bottom of the groove is higher. Finally, the temperature rises of the end face, inside slot and outside circle of the stator core are monitored in real-time by thermocouples and a temperature monitor. The measured temperature distribution of the stator core is in good agreement with the finite element simulation results, verifying the effectiveness of the electromagnetic-temperature-stress coupling method. In this paper, the temperature distribution of the stator core and the mechanical structural response distribution of the stator core under magnetic and thermal coupling excitation are obtained, providing a technical reference for the reverse optimization design of the generator structure and the prevention of stator core deformation.

Overhead transmission lines are the significant component of electric power system, where the over current can be coupled with the transient electromagnetic field or excitations (such as high-altitude electromagnetic pulse). As the coupling path of strong electro-magnetic interference, overhead transmission lines cause serious interference to the power system. Among the existing modelling methods, the classical transmission line theory may generate large error when dealing with the high-frequency coupling problem, where the cross dimension of the transmission line is not electrically small. Numerical full-wave method (such as moment of method) which relies on the grid subdivision with low efficiency when dealing with long transmission lines. Moreover, the number of cables is usually large in electric power system, and the ground are considered as the lossy ground. Therefore, to address the above mentioned problems, an asymptotic method is proposed to calculate the high-frequency coupling current along overhead transmission lines in electric power system. Based on the asymptotic theory with high calculation efficiency, the scattering and reflection process are introduced to quantify higher-order model components. In addition, the arbitrary number of wires, arbitrary parameters of the ground and different excitations are considered to derivate the current expression. Finally, the validity and reliability of the proposed method are tested using the full-wave simulation and antenna irradiation experiment. The proposed method can quickly calculate high-frequency coupling current, which can provide theoretical basis and data support for protection and electromagnetic effect study of overhead transmission lines.

Integrated energy systems enable the complementary utilization of various forms of energy. With the rapid increase in installed capacity of distributed generations, their intermittency and randomness have posed significant challenges to the operational efficiency and safety of the system. To address the impact of uncertainties in both energy supply and demand on the economic scheduling of building integrated energy systems, this study first models the operational characteristics of each subsystem, including the power grid, natural gas network, and various coupled equipments. Next, a thermal cell model of the building users is constructed based on the quantitative relationship among temperature, thermal radiation, and thermal load. Then, a day-ahead optimization scheduling model for the building integrated energy systems is established with the objective of minimizing the operating cost. A chance-constrained programming approach is employed to convert the non-linear scheduling model into a mixed-integer second-order cone programming problem easy to solve. Finally, simulation analysis is conducted in the Python environment using the CPLEX solver. The results demonstrate that the proposed model and solution method are capable of effectively characterizing and addressing uncertainty risks in the system, facilitating the consumption of renewable energy, and improving the economic efficiency of system operation.

The multi-uncertainty of source and load poses significant challenges to the optimal scheduling of 'source-load-storage' integrated microgrid. However, a limitation of the traditional optimization model is its one-sidedness and use of a single time scale, which can result in suboptimal scheduling outcomes. Striking a balance between reliability and economy presents a considerable obstacle, as does coordinating the relationship between uncertainty analysis methods and varying time scales. Based on the data-driven multi-discrete scene distribution robust method, a two-stage distributed robust day-ahead optimal scheduling model of microgrid is proposed, which is solved by column and constraint generation algorithm. By combining the improved distributed robust optimization uncertainty method with a multi-time scale scheduling strategy and model predictive control theory, the accuracy of the scheduling can be enhanced. This is achieved through the gradual refinement of the scheduling time scale and reduction of the prediction period length. The day-ahead-day multi-time scale rolling optimization scheduling model is established to minimize the generation cost and adjustment cost, while also exhibiting a high degree of resilience to system uncertainties. Combined with the simulation analysis of the example, the proposed model has demonstrated advantages in incorporating new energy sources, reducing operating costs, and balancing considerations of safety and economy.

If a subsequent commutation failure occurs in the line commutated converter-based high voltage direct current (LCC-HVDC) transmission system, it will have a seriously negative impact on the safe and stable operation of the AC-DC hybrid power grid. Aiming at the problem of commutation failure during the current deviation control stage in the fault recovery process of the LCC-HVDC system, the relationship between current deviation control parameter and commutation failure is analyzed theoretically. It is found that to avoid commutation failure at this stage, the DC voltage and AC commutation voltage at the inverter side of the LCC need to meet certain constraints. These constraints are directly affected by the current deviation control parameter. Based on the theoretical analysis results, a current deviation control parameter tuning method is proposed, which can improve the control requirements for DC voltage recovery speed and degree during the fault recovery process of the system. The method makes it easier for the system to meet the stable operation constraints between DC voltage and AC commutation voltage, thereby reducing the probability of subsequent commutation failure. Finally, the CIGRE standard test model in the PSCAD/EMTDC simulation platform is used to verify the correctness of the theoretical analysis and the effectiveness of the parameter tuning method.

When applying the fault enumeration method to evaluate the reliability of the whole transmission and distribution network composed of transmission network and flexible interconnected distribution network, apart from analyzing the influence of internal faults of the transmission network and distribution network on their respective power supply reliability, the interaction between the transmission network and distribution network should also be considered under the fault scenario. Based on existing independent reliability evaluation algorithms for the transmission network and distribution network, the reliability evaluation method for the whole transmission and distribution network is proposed in this paper. The proposed method in this paper can account for the interrelation between the operation states of the transmission network and the distribution network under the fault condition. The node load reduction after the failure of the transmission network is refined into the optimized load cutting scheme of the distribution network. While improving the accuracy of the reliability evaluation results of the transmission network, the load loss of the distribution network caused by the failure of the transmission network is included in the reliability evaluation of the distribution network. In addition, the load loss caused by internal faults of the distribution network and its influence on the reliability of the transmission network are included in the reliability evaluation of the transmission network. For the whole transmission and distribution network, the reliability index of the transmission and distribution network is calculated by the analytical method based on fault enumeration. The validity of the reliability evaluation model is verified by the results of the numerical analysis.

In order to improve the flicker suppression performance of static var compensator (SVC) in response to impact loads such as DC electric arc furnace, a SVC rolling predictive control method based on the improved Takagi-Sugeno (TS) fuzzy algorithm is proposed. Firstly, the electrical model of DC electric arc furnace is established and its reactive power characteristics are simulated and analyzed. Then, an improved method of range adaptive correction is proposed to address the issue of abnormal output set to 0 when the classical TS fuzzy prediction algorithm is applied to fluctuating loads. This method can eliminate the outliers caused by the application mechanism of a class of algorithms, so as to improve the reliability and accuracy of TS fuzzy algorithm for reactive power prediction of fluctuating loads. Finally, based on the model training time constraint, a reactive power half-cycle rolling predictive control model is established to predict the reactive power 10 ms in advance. It is competent to improve the lag characteristics of the traditional SVC control system response. The simulation results show that the average flicker improvement rate of the proposed method increases by 54.17% compared with the traditional SVC control method, and the suppression effect of flicker phenomenon is significantly improved.

In order to solve the problems of system peaking and consumption caused by the integration of large-scale new energy sources into the grid, this paper analyzes the source-load-storage peaking capacity and its complementarities, so as to tap the system's peaking capacity and promote new energy consumption. Firstly, taking into account the peaking pricing and compensation for ancillary services for thermal power, energy storage and electric vehicles, the peaking cost sharing and compensation mechanism is analyzed and a deep peaking model is established. Secondly, considering the uncertainty and correlation of wind power, a typical wind power sequence based on kernel density estimation and Frank Copula function is generated and a step-type demand response model is established to realize the graded compensation of the response amount. Then, it is possible to improve the response enthusiasm of demand-side users. Finally, with the objective of minimizing the total operating cost, a joint source-load-storage peak-peaking optimization model considering uncertainty and pricing compensation is constructed, and the improved IEEE 30-node system is used as an example for analysis. The results show that the proposed model can increase the system's peak-shaving capability and renewable energy consumption level by utilizing the flexible peak-shaving potential of resources on the three sides of source, load, and storage.

Under the background of the new power system, it is important to make full use of the distributed generation in the distribution network to achieve carbon peaking and carbon neutrality goals. With the wide access of distributed power sources, there is bi-directional power flow between the transmission and distribution networks. If the transmission and distribution networks still follow the traditional equivalence method for optimal power calculation, accurate results will not be obtained. Therefore, a transmission-distribution-network-coordinated optimal power flow model is established. The node tearing method is used to decouple the coupling variables of the transmission network and distribution networks. On this basis, the iterative form of the model with immobile points is obtained by mathematical derivation. The traditional heterogeneous decomposition algorithm only uses the latest calculation results for iterative computation. Hence, combining with the Anderson acceleration idea in mathematics, the heterogeneous decomposition algorithm based on Anderson acceleration is proposed by using the historical iteration values to optimize the iterations of immobile points. It is demonstrated by numerical experiments that, the established model can fully utilize the initiative of the distribution networks and reduce carbon emissions. The proposed algorithm has high accuracy. In addition, compared with the heterogeneous decomposition algorithm, its convergence performance is significantly improved.

The rational utilization of the complementarity between new energy sources can smooth out the fluctuation of their power output, and the consideration of complementarity in new energy planning can make the new energy planning layout more rational. Based on this, the paper considers the complementarity of new energy outputs and investigates the optimal planning method of new energy system taking into account the source-load matching. The positive correlation between new energy output and load is utilized to maintain the dynamic balance between new energy output and load. Firstly, based on the idea of source-load matching, an equalization index describing the degree of closeness between the new energy output and the load, and a consistency index describing the degree of positive correlation between the new energy output and the baseline load output are proposed. Then, a multi-region new energy optimization planning model considering the source-load matching is established, and a constraint on the equilibrium degree of the new energy output and the load matching is introduced to ensure the consistency of the change characteristics of the two. Finally, a case study is conducted to analyze the power grids of four regions in the northern part of China. The results show that the new energy optimization planning considering the source-load matching can consider the new energy consumption rate and penetration rate comprehensively, and provide a solution for the new energy planning layout considering the complementarity of new energy output.

In order to explore the economic and carbon reduction benefits of photovoltaic-storage-charging integrated stations and achieve reasonable configuration of internal components, a multi-objective optimization configuration method for stations that takes into account economic and low-carbon aspects is proposed. Firstly, based on the functions and requirements of each module in the charging station, the sources of carbon emissions generated by station is explored, and a mathematical model for the cost and carbon emissions of each module in the station is established. Then, with the goal of minimizing the annual investment and operating cost of the system and carbon emissions, a multi-objective particle swarm optimization algorithm based on three-black-hole capturing strategy is used to optimize the configuration of various modules of stations in different load scenarios, and the optimal configuration plan for each component module of the station under three scenarios is obtained. The comparative results show that the method proposed in this article can effectively reduce the cost and carbon emissions during planning and operation, and improve the economic and environmental benefits of stations. Finally, the technique for order preference by similarity to ideal solution is used to provide a compromise optimization plan for the optimal scenario, which can provide reference for the current investment and construction of photovoltaic-storage-charging integrated stations.

Strong corrosive active sulfur in the mineral insulating oil has been considered to be the main culprit to induce the insulation failures of oil-immersed power equipment. In order to protect the oil-paper insulation from sulfur corrosion, active sulfur is cleared in the refining process of crude oil. Some inactive sulfur with high antioxidant is still retained in the mineral oil to improve the oxidation stability of oil. However, the activation of inactive sulfur under the operating condition of oil-immersed power equipment is not gained attention. This paper focuses on the reaction mechanism of winding corrosion induced by non-active thiophene sulfide in mineral insulating oil. The thermal pyrolysis products of thiophene sulfide are investigated by the material phase analysis method, and the activation energy changes of thiophene sulfide at different heating rates are analyzed in combination with the pyrolysis kinetics analysis method, and the experimental study of inactive thiophene sulfide under the action of oil paper insulation thermal field is carried out. The results of gas chromatography, mass spectrometry and Fourier transform infrared spectroscopy show that the main activation product of thiophene sulfide (thiophene, benzothiophene, dibenzothiophene) during pyrolysis is H2S, which is highly corrosive and volatile. The thermogravimetric and differential thermogravimetric curves of thiophene sulfides are basically the same at different pyrolysis rates, and thiophene is the most prone to pyrolysis, followed by benzothiophene and dibenzothiophene. Under the condition of low temperature superheating of oil paper insulation, due to the continuous accumulation of system energy, the inactive thiophene sulfide will be activated and then generate low molecular highly corrosive sulfide, which intensifies the corrosivity of oil products and leads to sulfur corrosion of oil paper insulation.

Aiming to address the problems of high cost, large size and complex structure of the traditional back-to-back three-level converter, this paper proposes a new dual-port three-level converter topology. This new topology reduces the number of switching devices and optimizes the system size through device multiplexing. Firstly, the operating principle of the proposed converter topology is analyzed in detail, outlining the six effective switching states, current flow paths, and corresponding dual-port output levels of the single leg, while also discussing and the voltage stresses of each switching device. Secondly, a level-shifting pulse width modulation for the proposed converter topology is investigated and designed, and the effect of modulating wave overlap is avoided by adding DC offsets. Thirdly, the key problems of the modulation scheme under both the common frequency and different frequency operation modes, such as the modulation regime range and phase angle difference constraints are analyzed. The principles for selecting DC offsets and constraint range of two-port modulation system in each operating mode are introduced. Finally, the different operating modes are verified using the DSP-FPGA-Typhoon HIL 402 experimental platform. The experimental results show that level-shifting pulse width modulation with DC offsets makes the output power quality of the converter better and the harmonic content lower on the premise of achieving stable output of voltage and current for the proposed converter topology.

When the earth faults occur in different phases of two feeders connected to the same bus in the resonant grounding system, the conventional fault line selection devices are inaccurate. To address the difficulties of fault line selection in the earth faults that occurred in different phases of two feeders connected to the same busbar for resonant grounding system, the line zero-sequence admittance is calculated by the zero-sequence current at the first end of the line and the zero-sequence voltage of the bus. The analysis of the fault characteristics indicates that, the zero-sequence admittance amplitude in faulty lines is larger than that in the non-faulty line, and this characteristic also appears in the high-impedance grounding faults. Based on the ratio of zero-sequence admittance amplitude, a fault line selection method for earth faults occurring in different phases of two feeders connected to the same bus in a resonant grounding system is proposed. The difference in zero-sequence admittance amplitude between fault and non-fault lines is used to establish a line selection criterion, which allows all fault lines to be selected. The results simulated by PSCAD confirmed that the proposed method works effectively, with high accurary. This method is not affected by the fault location and the compensation degree of the arc suppression coil, and it can also withstand high fault resistances.

The zero-value piece of insulator string can be detected by measuring its electric field strength. The traditional way is always by measuring the electric field distribution curve of the whole string to judge out the zero-value piece position, which is inefficient and difficult to operate in field. In this paper, an improved method of identifying zero-value insulator by just measuring the partial electric field of insulator unit is proposed. Firstly, the simulation model of insulator string zero-value unit detection is established, and the partial electric field distortion characteristic caused by zero-value piece is analysed. Then the partial electric field variation criterion for zero-value identifying is obtained basing on the simulation result. Finally, the identification method is verified by designing the detection device and carrying out the point to point zero-value piece evaluating experiments. The results show that the point to point zero-value insulator detection can be realized using the three-array-probe electric field measuring method. The length of the array should be larger than the length of the electric field distortion interval, which can be taken as 130 mm for the research object in this paper. The identification criteria is that the deviation between probe 1 and 3 is less than 10%, and the deviation between probe 2 and the average is less than 50% at the same time. When detecting zero-value piece at the high-voltage and medium-voltage end, the best position for the sensor device identification is directly facing the steel foot, while for the low-voltage end, the best position is facing the shed edge. The results of the study can provide theoretical support for the intelligent operation and maintenance of external insulation in power transmission and distribution.

Micro-energy networks integrate distributed energy systems, multiple loads and control devices in parks or communities. Micro-energy networks are capable of realizing multi-energy cogeneration and co-supply functions, which are conducive to enhancing the operational flexibility and economy of multi-energy networks. To effectively cope with the uncertainty of load and new energy output within the micro-energy networks, a polyhedral uncertainty set is established to portray the fluctuation of load and photovoltaic output. An energy hub (EH) coupling matrix describing the topology of micro-energy networks and the coupling relationship between the energy flows is constructed. Then, a two-stage robust optimization economic dispatch model is established for micro-energy networks in both grid-connected and islanded operation modes to minimize the system operation cost. Linear decision rule (LDR) and duality theory are used to develop model-solving strategy. Finally, a case is carried out using micro-energy networks based on improved IEEE 33-node distribution network. The results show that LDR can effectively approximate the relationship between decision variables and uncertain variables through linear affine function within a certain accuracy range, which reduces the difficulty of solving the two-stage robust optimization economic dispatch model.

The transmission tower and tower line coupling system is an important carrier of the power system transmission process. Strong winds in coastal areas have a significant impact on the transmission tower and tower line system. To study the dynamic response characteristics of tower line system under the action of random fluctuating wind fields, the 1W2C9 drum-type self-supporting transmission tower in Guangdong is taken as the research object. Finite element models for the single tower and one tower two-line tower line coupling system are established. By combining the Davenport wind speed spectrum with the fourth order autoregressive method, the fluctuating wind fieldswith spatial correlation are simulated for a single tower with 9 nodes and tower line system with 49 nodes. The dynamic response of a single tower and tower line system under this fluctuating wind field is studied, and the influence of different wind direction angles on theirdynamic response is explored. The results indicate that the maximum dynamic response of both the single tower and tower line system is greater than their pseudo-static response. The existence of transmission lines enhances the stability of the transmission tower line system, reducing its dynamic response. A wind direction angle of 90° proves to be the most unfavorable for the dynamic response of the single tower and tower line system.

At present, new energy is introduced into the power system in large quantities. In order to make it replace the traditional hydropower and gas units as the black start power supply, segmentation restoration strategy of power grid based on the combined optical storage system is studied. Firstly, according to the structure and control mode of the optical storage system, the energy storage system establishes a stable grid-connected bus voltage is proposed, and the photovoltaic system is connected to the grid step by step. Secondly, in order to enhance the damping inertial support of photovoltaic power generation system, virtual synchronous control is proposed to be added to the inverter side of photovoltaic system. Finally, in the process of grid connection between the units to be started and the system load, the energy storage system is configured with additional damping controller to suppress the sub-synchronous oscillation generated by the grid black start, so as to ensure the stable recovery of the grid. In PSCAD/EMTDC, the electromagnetic transient simulation model of black start of the combined optical storage system is built and the simulation analysis is carried out. The results show that the busbar voltage deviation and system frequency deviation in the recovery process of the system are less than 0.65% and less than 1%, which meets the requirements of black start and verifies the feasibility of the start-up strategy proposed in the paper.

Currently, there are issues such as insufficient research on the physical characteristics of windings in grounding transformers under outlet short circuit conditions and a high number of damage accidents. Given this issues, a dry-type grounding transformer is chosen as the research subject. A three-dimensional multi-physics field coupling model is constructed using finite element simulation software. The aim is to analyze changes and distribution patterns of multiple physical parameters such as winding electromagnetic fields, winding temperature rise, and winding stress deformation under the outlet short circuit condition of the low voltage side of the grounding transformer. The key factors influencing grounding transformer's ability to resist outlet short circuit are also explored. Results indicate that after an outlet short circuit occurs in the grounding transformer, the magnetic flux and equivalent stress on its winding side, influenced by its yoke core and adjacent pillar cores, are greater than those on the front side, resulting in extremely uneven overall deformation. Due to the grounding transformer's special winding structure and operating mode, the transient temperature of its low voltage winding during outlet short circuit faults can reach 140.9 ℃, which is much higher than that of the high voltage winding. Finally, measures are proposed to improve the grounding transformer's ability to resist outlet short-circuit based on the dual constraints of dynamic and thermal stability, and structural optimization is carried out for the weak areas of grounding transformer to resist outlet short-circuit.

AC submarine cable is an important component in AC transmission system of offshore wind farms. However, the issue of charging current limits its application in offshore wind power with long-distance and large-capacity. Taking HYJQF41-F290/500 kV single-core AC submarine cable as an example, the overvoltage distribution along the cable in different working conditions is analyzed, considering the long-distance and high-voltage transmission. The simulation model of the cable is established and its parameters are corrected firstly. According to the different compensation degrees of the shunt reactor, the capacity of the shunt reactor under the configuration scheme of single-end compensation and two-end compensation calculated out. Finally, based on the single-phase grounding fault, the closing and opening conditions in the high-voltage and long-distance wind farm models, and the distribution law of overvoltage along the submarine cable under different reactive power compensation schemes is tested by simulation. The results show that the maximum overvoltage of submarine cables appears in different positions with different compensation schemes. Based on this, the selection methods for high-voltage submarine cable and overvoltage in insulation level design of substation equipment are given out under different compensation schemes, which have certain guiding significance for engineering practice.

Temperature plays a crucial role in influencing the mechanical properties of materials. Accurately measuring the temperature of devices is essential for understanding the evolution of their mechanical properties under stress and evaluating their health and lifespan. However, traditional methods encounter challenges in measuring transient temperatures and lack sufficient time-resolution capability, particularly when it comes to the rapid temperature changes at the solder interface during the switching process of power devices. In this paper, based on the close correlation between the intensities of the characteristic spectral lines of the laser-induced elements and the temperatures, a method of measuring the surface temperatures with the time-resolved capability of the order of microsecond is proposed, and a quantitative relationship between the surface temperatures of the sample and the spectral characteristics is established. The findings demonstrate that an increase in the surface temperature of the material results in enhanced intensity and signal-to-noise ratio of laser-induced plasma spectra. This enhancement is influenced by the spectral acquisition delay and gate width. To establish a quantitative relationship between surface temperature and spectral properties, back propagation-artificial neural network (BP-ANN) and partial least squares (PLS) are employed for fitting and calibration. The fitted models can achieve linear correlation coefficient indexes exceeding 0.99. Notably, the BP-ANN fitted model exhibites a small fitting bias, with a root mean squared error (RMSE) of 2.582 and a correctness rate of 98.3%. The method provides an effective means for transient temperature measurement of objects and gives a strong support for the assessment of the health status of the soldering interface of power devices.

Pulse injection to simulate partial discharge (PD) is the main method for functional verification of gas insulated switchgear (GIS) ultra high frequency (UHF) PD monitoring device. Due to the different coupling modes of pulse injection in field verification, the equivalence law between simulated PD and actual PD is not clear, and the effectiveness of functional verification of monitoring device cannot be guaranteed. In this paper, a typical PD defect (tip, suspension, insulator bubble) and internal/external pulse injection UHF PD detection platform for 126 kV GIS are established, and the effective pulses of UHF signals are normalized and extracted. Then a signal processing method of weighted intrinsic mode functions (IMF) based on empirical mode decomposition is proposed. The signal equivalence is characterized by calculating the average and maximum values of the Euclidean distance of the signal, and finally compared with the conventional signal deviation method. The research shows that compared with the conventional signal equivalence analysis method, the weighted IMF method can effectively solve the problem of large local difference of UHF signal waveform. The internal sensor pulse injection analog PD and suspended PD have the highest equivalence. The average value Me and the maximum value Ma of Euclidean distance are 3.82% and 10.28%, respectively. Therefore, the function verification of UHF monitoring device can use constant parameter pulse injection instead of suspension defect, and the internal UHF sensor injection can be preferred for analog PD. The research in this paper can provide reference for the pulse injection method for the function verification of UHF PD monitoring device.

Partial discharge at the oil-paper interface is one of the main reasons for the failure of oil-paper insulation in oil-immersed transformers. In this article, based on the numerical model of multi-branching streamer discharge, a multi-branching streamer discharge model in oil-paper insulation system is constructed by further considering the charge transport characteristics of oil-paper interface. The surface discharge characteristics under the influence of the dielectric constant ratio between natural ester insulating oil and insulating paper, and the spacing between needle electrode and paperboard are studied by finite element method, respectively. The results show that the distance between the needle electrode and the paperboard, and the dielectric constant ratio of insulating oil and insulating paper both significantly affect the streamer branching. The smaller the clearance between the needle electrode and paper-board is, the more serious the inhibition of streamer branches at the oil-paper interface is, which resulting in the streamers near the oil-paper interface are more significant effect on the propagation of the z-axis streamer. When the dielectric constant of the insulating oil is larger than that of the paperboard, the development and branching of the streamer in the oil will be more significant. On the contrary, the streamer is more likely to develop along the surface of the paperboard and accumulate charge at the oil-paper interface.

In order to coordinate the interests between electric vehicle owners and the active distribution network, a multi-objective hierarchical optimization method for the optimal scheduling of the active distribution network with electric vehicles is proposed. This method takes into account both the comprehensive satisfaction of electric vehicle charging and the operational benefits of the active distribution network. The upper layer model focuses on maximizing the charging benefits of electric vehicle owners, and the normalized normal constraint method is used to solve the optimal charging and discharging plan of electric vehicle, which is input to the lower layer optimization model. The lower layer model aims to maximize the operational efficiency of the active distribution network by adjusting the output power of the controllable distributed generation according to the charging and discharging plan of electric vehicle. The second-order cone program and weighted minimal modular ideal point method are used to solve the nonlinear multi-objective problem. Simulation results show that the proposed multi-objective hierarchical optimization method can promote the comprehensive satisfaction of electric vehicle charging exceeding 0.9 while reducing active power loss by 94.12% and operating costs by 30.90%, which achieves a win-win situation for both electric vehicle owners and the active distribution network.

Permanent magnet synchronous motors (PMSMs) are widely utilized in the field of manufacturing and production due to their notable advantages such as simple structure, stable operation, high efficiency, and diverse configurations. Operating under conditions with variable speeds and load fluctuations, PMSMs inevitably experience various faults, including bearing faults, eccentricity faults, demagnetization faults, and interturn short-circuit faults. An overview of common fault types in PMSMs is provided in this paper and the existing researches on signal-based condition monitoring methods in the field of automation for the detection and diagnosis of electrical and mechanical faults are summarized. Subsequently, diagnostic methods are summarized, and their strengths and limitations are analyzed, discussing the pros and cons of different signal processing approaches in application. Finally, considering the current state of research, the challenges and future directions in the monitoring and diagnosis of PMSM faults are discussed.

Time-frequency domain reflection (TFDR) method has the advantages of maturity, convenience and high resolution, so it is widely applied to locate defects in various cables. To ensure the fracture defect of the instrumentation and control (I&C) cable can be effectively discriminated and precisely located in nuclear power plant (NPP), an improved TFDR method is proposed by intervening thermal stress in this paper. Subsequently, different degrees of fracture defects are simulated in a 50-meter multi-core I&C cable, and traditional TFDR and improved TFDR methods are used for detection and verification. Comparing the detection results of both, the peak localization of improved TFDR method for weak defect fracture is improved to 0.2, which is 2.5 times of the traditional TFDR method, and the localization error rate is less than 2.5%. Compared to the traditional TFDR method, improved TFDR method utilizes the thermal stress fluctuation variance curve as the basis for defect identification, the identification power of weak fracture defects can be substantially improved. The original localization distance can be corrected to improves the accuracy of weak fracture damage in improved TFDR method. So the effective identification and localization of weak defects can be further achieved in improved TFDR method.

The capacity of distributed photovoltaic impacts the safe and reliable operation of the distribution network. Energy storage in distribution feeders has emerged as a pivotal solution for consuming distributed photovoltaic. However, it is challenged to balance the economic viability of energy storage investing and grid reliability. In response, a method of optimizing the configuration of energy storage in distribution feeders based on the new model of counter configuration of the renewables from energy storage is proposed, which takes into account both the economy and reliability aspects. Firstly, an economic model for optimizing energy storage in distribution feeders is established. Secondly, a grid reliability simulation is performed based on the results of the economic optimization of energy storage in distribution feeders. Finally, considering the comprehensive indexes of economy and reliability, the different nodes are evaluated for site selection using technique for order preference by similarity to ideal solution (TOPSIS), and the energy storage configuration scheme is determined by the cumulative distribution curve. The simulation results show that the consuming capacity of distributed photovoltaic in the distribution feeders is effectively improved, and better balance the economic viability of energy storage investing with grid reliability, which can be used as a reference for the reasonable determination of ratios of the energy storage for renewables.

Abstract The authors investigate a semi‐flooded cooling technology for modular permanent magnet machines using flux gaps (FGs) in alternate stator teeth for extra cooling channels. The investigated machine is separated into stationary and rotational components by a polyether ether ketone sleeve. Liquid is directed into the stationary component to achieve a significant temperature reduction, at the same time, avoiding the liquid leakage into the rotating component that will cause an increase in friction losses. The FGs in the modular machine increase the contact area between coolant and machine components, resulting in better cooling efficiency. Furthermore, the FGs contribute to reduced pressure loss by minimising system flow resistance. The influence of the FG width on improving machine cooling efficiency, lowering machine temperature, and reducing pressure losses is delved. Additionally, the investigation considers the impact of inlet and outlet areas to reveal the influences stemming from fluid expansions and contractions in these regions. Computational fluid dynamics (CFD) modelling is employed to simulate the cooling performances of the investigated machines. In addition, the flow network analysis has also been employed to help understand the fluid behaviour within machines. A series of tests have been carried out to validate the CFD modelling.

Abstract Rare‐earth permanent magnet synchronous machines face challenges in manipulating their magnetic fields, which hinders the ability to extend the operation speed range. Moreover, this inflexibility leads to reduced efficiency in high‐speed scenarios when the machine is under flux‐weakening control and increases the risk of the magnets becoming demagnetised. The authors propose an alterable‐magnetic‐circuit variable‐flux memory machine (AMC‐VFMM) and a multi‐objective hierarchical optimisation method is conducted to optimise the machine. Firstly, the topology and alterable‐magnetic‐circuit principle of the proposed AMC‐VFMM are introduced. Then, optimisation objectives including torque production capability, flux regulation capability, and resisting unintentional demagnetisation capability are defined, and the hierarchical optimisation approach is established by stratifying the optimisation objectives and variables through the sensitivity analysis. Finite element analysis indicates that electromagnetic performances of the optimised design scheme are significantly enhanced. The bench test of the prototype demonstrates the superiority of the proposed AMC‐VFMM and validates the effectiveness of the optimisation design method.

Abstract Precisely interpreting frequency response analysis (FRA) curves is crucial when investigating mechanical malfunctions in power transformer windings (TWs). However, many conventional explanations of FRA features cannot be validated by an equivalent circuit (EC) that represents winding structures using resistance, inductance, and capacitance components in a ladder network. Incorrect interpretation can lead to misdiagnosis and confusion in asset management. Previous ECs are often proposed by analysing winding structures without rigorous verification compared to the corresponding FRA data. The specific EC is acquired using the transfer function (TF) derived from the measured FRA data. This allows for the establishment of the relationship between TW FRA curves, TF equations, and EC topologies. The precise interpretation of FRA curves can be achieved by closely observing the FRA curves created from TFs and ECs. The remarkable similarity between the measured and modelled FRA curves verifies the authenticity of the derived ECs. This significant achievement clarifies many misunderstandings regarding FRA and represents a substantial advancement in FRA technology.

Abstract Current transformers (CTs) are widely used for energy metering, relay protection, condition monitoring and control circuits. However, CT saturation may lead to non‐negligible measurement errors and relay malfunctions, posing a threat to the stability and security of the power grid. In order to address the problem of CT saturation, a novel measurement‐protection‐integrated current transformer (MPICT) is proposed. First, the working states of the MPICT are summarised and the approximate expressions for the steady‐state measuring characteristics, the transient response characteristics, and the measurement errors are derived from the equivalent circuit model. Then, the feasibility of the MPICT and the theoretical analyses are verified by the 3D FEM simulation imitating the presented MPICT excited by diverse currents. Finally, a down‐scale prototype is fabricated and a series of tests are conducted in the laboratory to validate the effectiveness of the equipment. The simulation and experimental results suggest that the output of the MPICT can accurately reconstruct the primary current waveform, even if the primary current contains decaying or constant DC component.

Abstract There is not only thrust but also normal force between the primary and secondary components for the single‐side flat plate permanent magnet linear synchronous motor (PMLSM). The normal force will fluctuate periodically, which will cause friction perturbation and finally affect the positioning accuracy of linear feed system. For the single‐side flat plate PMLSM, the variation law of normal force ripple under the coupling effect of multiple effects is studied, and the method of primary component segmental design to suppress it is proposed. Firstly, the influence of the cogging effect, the end effect and the armature reaction on the normal force ripple is analysed. Meanwhile the mathematical model of normal force ripple is established. Secondly, the PMLSM with segmental primary component is introduced and its suppression mechanism to the normal force ripple is expounded. On this basis, a scheme combining the non‐integer pole slot matching with the primary component segmental design is proposed to further suppress the normal force ripple. Finally, an 18‐slot 96/5‐pole prototype is taken as an example to carry out the finite element simulation and experimental test, of which the results verify the research theory in this paper.

Abstract Vector control of induction motors has provided us with both good performance and acceptable efficiency at rated loads. Using this method at light loads reduces the efficiency due to the adjustment of motor flux at the rated value. Electric motors are normally used even at lower loads than the rated ones and often selected oversized. Enhancing the efficiency of induction motors at light loads will significantly reduce electric energy consumption. A novel method called Flux Angle Control (FAC) of the induction motor is presented to improve efficiency in the steady state at light loads. To increase the accuracy of the induction motor model we consider iron losses. This method controls the angle between the stator flux (stator current) and the d‐axis (rotor flux direction). The primary aim of the flux angle control method is to reduce the flux level and increase the flux angle at light loads. The optimal flux angle is sensitive to some induction motor parameters. The proposed method offers several advantages compared to similar methods, including high efficiency, minimal sensitivity of the optimal flux angle to changes in motor parameters, a reduced number of calculations, and easy implementation. The validity of this method is examined through experiments.

Abstract During geomagnetic storms, geomagnetically induced currents (GICs) occur in the power grid. GIC is a quasi‐direct current, which is represented by using a fixed DC current, the authors propose an approach that combines field‐circuit‐coupled and weakly coupled magneto‐mechanical models to investigate the magnetostriction characteristics of single‐phase, four‐column autotransformer cores excited by GICs. A non‐linear magnetostrictive constitutive model that considers the impact of stress and magnetisation intensity on ferromagnetic materials is introduced. The model reveals that the strain in the core initially increases as the magnetisation intensity increases; however, when the core begins to saturate, the magnetostrictive strain weakens as the magnetisation intensity increases. Moreover, the results of multiphysics finite‐element modelling are experimentally verified using a direct current bias platform. The results show that when excited by GICs, there is an enhancement in the vibration of the iron core, and the harmonic content of the vibration acceleration increases considerably, with the odd harmonics most significantly increasing in amplitude. The conclusion drawn is that GICs can exacerbate transformer vibration and significantly increase the content of harmonics, especially odd harmonics.

Abstract This paper introduces a novel application of the inverse modelling method, which is designed to estimate core losses in both the stator and rotor regions of an electrical machine. The technique focuses on the use of short‐term transient temperature measurements obtained from the stator core of a slotless induction machine, with a focus on validating the measured temperature rise through a forward model. The measurement setup involves two primary approaches: (i) the use of thermal sensors embedded in a printed circuit board inside the stator core and (ii) surface sensors embedded on the stator yoke. Through the use of this innovative approach, the results indicate that the inverse modelling technique is highly effective in predicting core losses based on short‐time transient temperature rise measurements.

Abstract Magnet cracking is a common issue in external rotor motors. To investigate the causes of magnet cracking and propose solutions, the authors consider the effects of magnet shape, magnet and yoke material fit on the motor rotor magnets, perform a static analysis of the motor rotor. The simulation and test results show that the stress distribution of tile‐shaped magnets is better than that of rectangular magnets. The highest safety margin of 56.41% is achieved for the magnet and yoke material fit of DT4/N35(EH). The maximum force of the permanent magnet (PM) exceeds 22.38% of the stress limit when the material fit is DT4/SmCo28, which can lead to cracks in the PM. The results of this paper have important reference significance for the structural design of the external rotor motor and their safe and reliable operation.

Nowadays, electric trains are experiencing a transition from diesel fuel to renewable energy. Hybrid electric trains can prove progress from renewable energy, even though they require more than one energy source such as fuel cells and batteries, because renewable energy cannot stand alone. This results in an increase in voltage on the Fuel Cell (FC) which can have an impact on current density and a decrease in voltage, thus requiring a protected DC-DC Converter type circuit to obtain ideal and dynamic condition characteristics. To overcome this problem, the IFBC (Interleaved Full Bridge Circuit) DC-DC Converter is highly recommended as a voltage regulator. There are several methods used to regulate MOSFET’s which in this case affect the IFBC DC DC Converter settings, one of which is the SMC (Sliding Mode Control) method. SMC is a type of non-linear control that functions functionally to control variable structures. However, the application of SMC requires a considerable switching frequency, which has the potential to cause component loss, therefore the switching frequency needs to be limited to that range. To overcome this problem, a method is needed to identify the IFBC output voltage control process using the SMC method in Fuel Cell applications and the software which is considered the most efficient in carrying out this, namely SIMULINK MATLAB software.

Abstract The permanent magnet eddy‐current coupler (PMEC) is a kind of non‐contact, stepless speed regulation device and has been widely used in transmissions. However, the current PMECs are coaxial and cannot achieve transmission and speed regulation in intersecting axes. An intersecting‐axis permanent magnet (PM) eddy current coupler (IPMEC), which consists of a disk‐type PM rotor and a barrel‐type conductive sheet (CS) rotor arranged with intersecting axes, is proposed. It generates eddy currents through the speed difference between the two rotors and uses the non‐contact electromagnetic force between the eddy currents and permanent magnets to transmit torque. During operation, the speed can be adjusted by altering the coupling area or air gap. A theoretical model of the IPMEC based on the equivalent magnetic circuit method is presented and verified by finite element simulation using ANSYS. Then, the effects of the pole number of the PMs, the radius of the CS rotor and the PM rotor on the performance were analysed, and the design method of the IPMEC was proposed. This study can be used to expand the application range of PMECs.

Abstract In order to cope with the grid fluctuation caused by large‐scale wind power connected to the grid, the wind thermal power generation system has been proposed and extensively studied. The wind thermal power generation system uses a wind turbine to drive a heat generation device to heat the heat storage medium, which is further exchanged to drive a turbine to generate electricity. A superconducting magnetic eddy current heater (SMH) is proposed for the characteristics of wind thermal power generation system, which uses non‐resistive, large current‐carrying superconducting coils for excitation, and has high output efficiency and power density. The working principle of magnetic eddy current heating is analysed, and the structure of SMH with no ferromagnetic material and two heating screens inside and outside is proposed according to the characteristics of SMH. An analytical model of the SMH is established, and the influence of the structure and materials of the SMH on the magnetic field distribution is analysed. Based on this, a 22‐pole SMH was designed and analysed for output power at 10–20 rpm. A three‐dimensional magnetism‐stress combined analysis model of SMH is established, and the strain and stress characteristics of SMH are simulated under the condition of maximum output power, which verifies the feasibility of the mechanical properties of existing superconducting materials for application in SMH.

Abstract A hybrid ferrite‐Al‐Ni‐Co permanent magnet assisted synchronous reluctance motor (PMa‐SyRM) for an air‐conditioner compressor is proposed. Al‐Ni‐Co PMs have high residual flux density similar to rare‐earth PMs such as Nd‐Fe‐B and Sm‐Co. Therefore, the performance parameters of the PMa‐SyRM such as power factor, efficiency etc., with Al‐Ni‐Co PMs can be improved without significantly increasing the cost of the motor. However, Al‐Ni‐Co PMs have a steep IInd‐quadrant B‐H curve, and the challenge lies in addressing their demagnetisation issues. In the proposed hybrid PMa‐SyRM, the rotor geometry is suitably optimised for placing the Al‐Ni‐Co PMs in the centre flux barriers to address the demagnetisation issues. Further, an analytical magnetic circuit is presented to design the proposed PMa‐SyRM. Later, 2‐D finite element analysis of the proposed motor including the demagnetisation analysis of PMs and stress analysis of the rotor is carried out and presented. A prototype is fabricated, experimental validation is carried out, and the results of the performance and cost are compared with that of ferrite and hybrid ferrite‐Nd‐Fe‐B PMa‐SyRM.