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Metal object detection (MOD) is crucial for the safe operation of ground-assembled wireless electric vehicle charging (WEVC) systems. Electromagnetic sensing by passive coils is a reliable MOD method for high-power applications, such as WEVC. Previous designs of sensing coils are mainly targeted at the systems with unpolarized coils (e.g., circular coils). However, they are not suitable for those with DD-coil-coupling engaged due to the fundamentally different field pattern. To fix this problem, in this article, a field-oriented design of sensing coils is proposed, which mainly aims at blind-zone elimination while maintaining high sensitivity and cost-effectiveness. The blind zone arising from axial symmetry of the field is removed by size-modulated C-shape coil units. And removing the central blind spot relies on an extra patch coil by utilizing the characteristic of parallel magnetic flux generated by DD coils. Tested by 13 positions (central blind spot excluded) where MOs might exist using a 3-kW WEVC prototype, the optimized sensing coils completely remove the axial blind zones when 50 mV is set as the threshold voltage. Moreover, for the central blind spot, the proposed patch coil can stably identify MO intrusion no matter if the prototype operates in light-load or heavy-load conditions. [ABSTRACT FROM AUTHOR]

How to effectively withstand the dc magnetic bias is one of the key aspects of transformer design. General approaches either require additional active power electronics devices or apply complicated control strategies, causing the increased cost or reduced reliability. In this article, a passive negative magnetic reluctance structure (NMRS) is proposed and installed in the air gap of the open-core transformer, which could achieve improved dc magnetic bias withstanding capability without extra active devices. The key criterion of the proposed design is to employ the NMRS with a frequency-variation magnetic reluctance property as a magnetic bandpass filter, which shows a negative equivalent magnetic reluctance for the fundamental component of flux. Nevertheless, it presents a high magnetic reluctance for the dc component. With the proposed design, the transformer provides a strong withstanding dc bias capability and a low magnetizing current as well as high efficiency. Accordingly, both the advantages of open-core and closed-core transformers could be obtained with the proposed design. For verification, a 500-W EE55-based core prototype is constructed and verified with sinusoidal and square wave excitation. Electromagnetic analysis and experimental results are provided to demonstrate the effectiveness of the proposed design. [ABSTRACT FROM AUTHOR]

Multiphase dc-excited Vernier reluctance machine (DC-VRM) exhibits the merits of robust structure, small torque ripple, and good fault-tolerant ability. Developing advanced sensorless drive methods can further promote its application in the safety-critical system. In this article, pulse injection sensorless drive methods are optimized in a six-phase DC-VRM parallel H-bridge drive system to strengthen their acceleration performance and fault-tolerant ability. The acceleration performance studied in this article corresponds to the acceleration speed during the startup stage. By the full-phase alternative pulse injection method (APIM), each phase can be excited independently to avoid mutual-inductance influence on position estimation, but this method suffers from a long communication delay and relatively poor acceleration performance. A reduced-phase APIM can reduce detection time, but the lack of detected phase may influence position estimation accuracy and fault-tolerant ability. To solve these problems, a novel vertical-axis synchronous pulse injection method is proposed and compared with previous methods in this article. The key is to inject detection pulses into vertical-axis phases simultaneously, thus reducing the detection time and improving the torque generation. It is proved that the influence of mutual inductance on position estimation can be ignored, and the detection accuracy and acceleration performance can be improved without deterioration of fault-tolerant ability. [ABSTRACT FROM AUTHOR]

This article presents a novel doubly salient permanent magnet (DSPM) machine with enhanced torque performance. The key is that an assistive magnetic flux is produced by using two sets of slot PMs inserted into the slot openings, which can effectively improve the torque production. Besides, a complementary magnetic path is built by dual rotors with 180° angle shift to reduce leakage flux, which can effectively suppress the torque ripple. In this article, the proposed machine design is presented, including working principle, winding configuration, magnetic path analysis. Then, the Genetic Algorithm is used to find the optimal designs for the proposed machine. Further, to verify the effectiveness of the proposed machine, three doubly salient machines are compared, including the proposed machine, a DSPM machine without assistive slot PM design, and a dual-rotor DSPM machine without complementary rotor structure. Finally, a prototype of the proposed machine is built and tested to verify the validity of the proposed machine design. [ABSTRACT FROM AUTHOR]

In this work, a novel general pattern of assisted flux barriers in an asymmetric V-shape interior permanent magnet (AVIPM) machine is presented. The AVIPM machine has a symmetric permanent magnet (PM) structure and an asymmetric rotor core structure to realize the magnetic-field-shifting (MFS) effect. The general pattern can represent four possible types of assisted flux barriers at different positions on the rotor core and the final structure can be automatically determined by using optimization method. The advantage of the proposed optimization pattern is that the optimal design of assisted flux barriers in V-shape interior permanent magnet (VIPM) machines with high torque and low torque ripple can be generated within a short computing time. The proposed optimization method is applied to improve the structure of a conventional 8-pole 48-slot VIPM machine, which is commonly used for driving electric vehicles (EVs). A non-dominated sorting genetic algorithm II (NSGA-II) is used for the global optimization of both a VIPM machine and an AVIPM machine. The electromagnetic performance is computed using a finite element analysis (FEA). Moreover, a frozen permeability (FP) method is applied to perform an accurate separation of PM torque and reluctance torque. The results exhibit that the peak output torque of the AVIPM machine is increased by 8.7% compared to a conventional VIPM machine with the same PM volume due to the notable MFS effect. In the meantime, the AVIPM machine has a better overload capability due to the larger contribution of reluctance torque. Moreover, the proposed machine has high efficiency of over 97%. [ABSTRACT FROM AUTHOR]

DC-Excited vernier reluctance machine (DC-VRM) using a 12-slot/10-pole-pair design, exhibits the advantages of small torque ripple and low cogging torque due to the inherent commentary characteristic. However, the inherent saliency is canceled out by a 12/10 pole combination of machine design driven by a traditional three-phase inverter. As a result, the sensorless operation in zero/low-speed regions becomes difficult because the position estimation methods using self-inductance detection cannot be applied. To tackle this problem, we first analyzed the saliency annihilation phenomenon through Fourier analysis that the odd-order harmonics in self-inductance are canceled. Moreover, reconstructing saliency method is proposed by splitting a phase winding into two sub-phase coils and using parallel H-bridge converters to supply sub-phase coils and achieve sensorless drive. Through this method, the saliency effect is recovered in self-inductance, thereby pulse injection sensorless drive can be applied. The constructed 12/10 DC-VRM sensorless drive shows good fault-tolerant ability and can be applied in safety-critical industry applications such as aerospace propulsion. Analysis and experiments are performed in the initial position detection, start-up and free-running stages to verify the feasibility of the proposed solution. A sector estimation accurate to 6° can be achieved. [ABSTRACT FROM AUTHOR]

Numerous research efforts are devoted to attain high performance and strong fault tolerance for the machine drives in safety critical applications, though the two aspects are conflicted in most cases. In this paper, a novel triple 3-phase PMA-SynRM with star-delta connected windings is proposed. The star-delta winding could produce a higher fundamental magneto-motive force and lower spatial harmonics than the conventional star winding. Therefore, it exhibits higher torque, lower torque ripple and lower iron loss, enhancing the healthy performance. In addition, the coils whose turn fault current is the highest are arranged in the inner delta part which provides circulating current path. It is demonstrated that the proposed winding solution reduces the fault current by 55% and the fault turn copper loss by 65%. Hence, the machine's fault tolerance is significantly improved. The machines with the star winding and star-delta winding are studied by detailed finite element calculation and experimental tests under various operation modes. Both the simulation and test results confirm that the proposed star-delta winding machine owns higher performance and stronger fault tolerance than the conventional star winding machine. Thus, it becomes a more competitive candidate for the high reliability drives. [ABSTRACT FROM AUTHOR]

In this article, slot-PM-assisted consequent-pole-PM machine (SPMA-CPMM) is proposed. The key is that the consequent-pole ferrite PMs are employed in the stator yoke to reduce the PM material cost largely, while a small amount of tangential magnetized rare-earth PMs is placed in the slot opening to improve the torque production. This proposed hybrid magnet design can greatly enhance the PM utilization ratio and reduce the PM cost while maintaining a relatively large torque density. In this article, the configurations of ferrite-PM machine (FPMM), consequent-pole ferrite-PM machine (CFPMM), and SPMA-CPMM are illustrated, while equivalent magnetic circuits (EMCs) of them are compared. Then, the electromagnetic performances of three machines are investigated and compared, which verifies the validity of the proposed machine. [ABSTRACT FROM AUTHOR]

This article presents a novel slot permanent-magnet-assisted hybrid-magnet memory machine (SPMA-HMMM) with hybrid permanent magnets (PMs) in both stator yoke and slot opening. The key is each pair of yoke PMs is composed of one pole of high coercive force (HCF) PM and one pole of low coercive force (LCF) PM with flexible flux regulation. LCF PMs can be freely magnetized and demagnetized through dc current pulses, which are supplied by dc excitation coils wound on LCF PMs. This design leads to high efficiency of machine due to negligible field excitation loss. In this article, the machine configuration and operation principle are illustrated in detail. An equivalent magnetic circuit is modeled to unveil flux regulation and parallel excitation effect. Then, the electromagnetic performances of SPMA-HMMM under different magnetization states (MSs) are investigated, which verify flux regulation ability of the proposed machine with changeable MSs of LCF yoke PMs. [ABSTRACT FROM AUTHOR]

The transverse flux tubular linear machine (TF-TLM) has merits of high power density and efficiency. However, excited by constant permanent magnet (PM), it is hard for TF-TLM to regulate its flux effectively, which restricts its further application in wave energy conversion (WEC). In contrast, the inherent higher order harmonics existing in the induced voltage may cause the additional loss and produce overvoltage, which should be eliminated to prompt power quality. Therefore, to strengthen the flux regulation capability of TF-TLM and improve the generated power quality, a novel hybrid-excited TF-TLM (HE-TFTLM) with complementary structure is proposed in this article. The key is that a parallel and complementary structure is constructed for hybrid excitations of both dc windings and PMs installed on the stator to enhance the flux regulation capability and eliminate the even-order harmonics in the induced voltage. In addition, the stator consequent-pole design boosts the output thrust density. According to the 3-D finite element analysis (FEA) results, output thrust force reaches 279.14 N, and the power density of the proposed machine can be effectively improved to 154 kW/m3 at rated excitation. [ABSTRACT FROM AUTHOR]

A line-start permanent magnet (LSPM) machine can be regarded as the integration of an induction motor and a permanent magnet synchronous motor (PMSM), so it has both self-starting capability as the induction motor and high efficiency as PMSM. As the cage winding on the rotor of LSPM only works at the starting process, it competes with permanent magnets for the space of a rotor. To solve this paradox, a steel-bar starting cage-based LSPM machine is proposed and analyzed in this article. Steel has larger resistivity than aluminum and copper, which can increase the starting torque and reduce the impact current of cage winding at the starting stage. Due to high permeability of steel, magnetic flux can also flow through steel-bar cage winding at synchronous speed. A steel-bar starting cage and a traditional aluminum starting cage winding are compared based on a four-pole LSPM machine using finite-element analysis (FEA) in this article. It is verified that although the self-starting capability of steel-bar cage winding is reduced due to the leakage flux, the performance at synchronous speed such as torque density and torque ripple is improved. [ABSTRACT FROM AUTHOR]

Vernier reluctance machine (VRM) with dc field coils in stator is a competitive rare-earth-free design for variable-speed industrial applications due to its robust structure and controllable excitation, while its torque density is relatively disadvantageous. To address this issue, this article proposes a new armature winding design method for VRM with dc field coils across two stator teeth. The key is to break the traditional winding design principle based on the flux modulation effect of fundamental dc field harmonic, and instead, reconstruct a novel harmonic winding to enhance the utilization factor of the modulated high-order dc field harmonics arising from the unique magnetomotive force distribution of dc field coils across two stator teeth. By this means, the torque density can be improved by 75.6% against the existing poor counterpart. In this article, the machine structure and operation principle are introduced, with emphasis on the high-order dc field harmonics distribution rule and its influence on the armature winding design. By finite element design and optimization, a comparative study is performed to evaluate the electromagnetic performance of VRMs using two different winding configurations with variable slot pole combinations. A prototype is fabricated and tested, and the results agree well with finite element analysis, which verifies the feasibility and advantages of the proposed winding design method. [ABSTRACT FROM AUTHOR]

In this article, a novel winding switching control strategy is proposed to extend the speed range of a consequent-pole ferrite-permanent magnet hybrid-excited machine (CPFPM-HEM) for electric vehicle application. The key is that in low-speed range, the ac armature winding and dc field winding are connected in series to achieve large starting torque, while in high-speed range, dc field winding is injected with adjustable dc currents to realize variable speed constant voltage of ac armature winding. Furthermore, consequent-pole rotor is used to reduce the usage of the permanent magnet (PM). In the meantime, ferrite PMs are used to replace rare-earth PMs to reduce the cost with the shortage of rare-earth resources. In this article, the machine configuration, operation principle with dual excitation sources, flux modulation principle, and winding switching strategy are illustrated in detail. Then, the electromagnetic performance of the CPFPM-HEM in different speed ranges is investigated. Finally, the speed range extension with winding switching strategy is verified by the Maxwell/Simplorer co-simulation. [ABSTRACT FROM AUTHOR]

Reluctance machines with dc excitation coils have become a promising solution for electric vehicle propulsion system because of its robust rotor structure and good field-weakening ability. However, these machines usually suffer from relatively low torque density and efficiency. To solve this problem, this article proposes a novel hybrid reluctance machine with improved torque density and efficiency. The key novelty is to introduce skewed permanent magnets (PMs) in slot openings. The tangential component of skewed PMs can be used to relieve the dc saturation in the stator iron core, so that the $B-H$ working range can be extended and relatively high dc excitation can be applied in the proposed machine. Besides, the radial component of skewed PM provides extra torque component under flux modulation effect. Therefore, the proposed skewed PMs can achieve torque boost and core utilization improvement simultaneously. In this article, the dc-saturation-relieving effect of the proposed design is thoroughly investigated and verified by finite element analysis. [ABSTRACT FROM AUTHOR]

In this article, two novel dual-stator machines with different biased permanent magnet (PM) configurations are developed and comparatively studied. For the proposed machines, the PMs are only located in the inner stator, but with different configurations, that is, surface-mounted PM (SPM) and interior PM (IPM), respectively. The machine topologies and operating principle are introduced first. Then, the electromagnetic characteristics, including open-circuit performance, torque characteristics, field-weakening capability, loss, and efficiency, are comprehensively analyzed and compared by finite-element method (FEM). The experimental validation is conducted to verify the FEM analyses. [ABSTRACT FROM AUTHOR]

In this article, the balanced bidirectional-magnetization effect of a newly developed hybrid-magnet-circuit variable-flux memory machine (HMC-VFMM) is revealed and investigated. First, the machine topology and variable-flux principle of the HMC-VFMM are described. In addition, the balanced bidirectional-magnetization effect is analytically unveiled by using a Fourier-series-based hysteresis model of low coercive force (LCF) magnet. The PM magnetization characteristics are then investigated by a coupled solution, which is employed to identify the mismatch between the LCF magnet movement trajectories subject to either continuous one-way or bidirectional alternate current pulses. Finally, a prototype is manufactured and tested to verify the theoretical analyses. [ABSTRACT FROM AUTHOR]

This article proposed a new slot-permanent-magnet (PM)-assisted hybrid reluctance generator (SPMa-HRG) with self-excited dc source for stand-alone wind power generation system. By introducing PM excitation in stator slot openings, enhanced torque density due to flux modulation effect can be achieved compared with the original reluctance topology. Moreover, the introduced PMs make it feasible to build a self-excited dc source to fed dc field winding without using extra power supply. In particular, a simple design of ac supply winding is proposed, by splitting a small portion of ac armature winding to provide electrical power to dc field winding through a diode rectifier and small-capacity H-bridge converter. Compared with using separate dc source, the device cost is reduced, and the system reliability is improved. In this article, the generator structure and operation principle are introduced. PM usage is optimized to obtain the optimal torque. The feasibility of the optimal design with self-excited dc source is verified by field-circuit coupled finite element analysis. [ABSTRACT FROM AUTHOR]

This article investigates rotor losses in permanent magnet Vernier machines. By analyzing air-gap field, the harmonic distribution and frequency of modulated open-circuit flux density and armature reaction flux density are obtained. Then, rotor losses production principle is revealed and the influence of each harmonic on the loss is analyzed. Meanwhile, the influence of each harmonic on torque is also studied. It is found that some harmonics have no contribution to torque but produce additional losses. On this basis, a new rotor structure is proposed to suppress the rotor losses. Comparison results indicate that by suppressing nonworking harmonics, the rotor losses can be reduced effectively without affecting the effective torque. Finally, the theoretical and finite-element analysis results are verified by prototype tests. [ABSTRACT FROM AUTHOR]

This article proposes a novel asymmetric-magnetic-pole interior permanent magnet (AMP-IPM) machine, which is geometrically characterized by a combination of dual-layer reluctance and flat-type PM rotor structures. The design concept of “asymmetric-magnetic-pole” is introduced to achieve a magnet-axis-shifting effect, namely, the magnet d-axis is shifted to make PM and reluctance torque components approximately maximize at similar current angles. Consequently, the resultant torque can be further improved without increasing magnet usage. The machine topology is first introduced. The electromagnetic characteristics of the proposed AMP-IPM machine are then investigated and compared with those of the benchmark conventional IPM machine with symmetrical magnetic poles, with similar sizing and PM usage. Finally, an AMP-IPM machine prototype is manufactured and tested, which confirms the feasibility of the proposed AMP design for the torque performance improvement. [ABSTRACT FROM AUTHOR]

In this article, a novel pre-processing method is proposed for magnetic field approximation based on neural networks. The process of calculating magnetic fields based on neural networks is presented first. In order to save the training time and reduce the estimation error, an excitation distance function, which is inspired by an analytical formula of magnetic potential, is proposed to integrate the input data, such as the geometry, excitations, and boundaries. This pre-processing or roughly reduces the dimension of the input layer by three quarters, while the training process is accelerated by a more integrated input layer. Preliminary experiments show that the predicted results by the proposed pre-processing method are close to the ground truth, with a significant reduction of computation time compared with the traditional finite element method (FEM). [ABSTRACT FROM AUTHOR]

The reluctance machine with dc field coils in stator is an emerging brushless candidate for the in-wheel direct drive for its wide speed range and robust mechanical structure, while it suffers from relatively low torque density and efficiency, due to the poor excitation ability of dc field coils and worse extra dc saturation effect in the stator core. To address this issue, a new hybrid reluctance machine is proposed in this article, in which an integrated dual-layer PM source is introduced into stator slots, aiming to relieve dc saturation and, meanwhile, evoke flux modulation effect. In this way, the stator core utilization factor can be boosted due to dc saturation elimination by inner-layer slot permanent magnets (PM). On the other side, extra PM torque is generated by the flux modulation effect of outer-layer slot PMs. Hence, with synthetic assistance from dual-layer slot PMs, the torque density is improved distinctly especially under relatively high current density. Besides, slot PMs share a parallel magnetic circuit with dc field coils, which enables a bidirectional dc magnetization control for speed range extension. In this article, the proposed new topology is fully evaluated by both finite element (FE) analysis and prototype experiments. [ABSTRACT FROM AUTHOR]

This article proposes a novel compact dual-permanent magnet (PM) dual-stator generator for hybrid ac/dc generation system. Two sets of windings are installed in the inner and outer stator separately. It has two electric ports, in which one is used to generate ac voltage and the other electric port that also generates ac voltage is rectified to obtain the dc voltage. The key of the generator is that two stators share one rotor with consequent PM structure, and the output power of the machine is much higher than that of the machine with only one stator. Besides, with two separated stator core and armature windings, the reliability of the proposed generator is improved. The advantage of the proposed dual-stator dual-PM generator is illustrated theoretically, and its slot/pole selection guideline is given. Comprehensive sensitivity analysis of the proposed generator is performed and multilevel design optimization method is adopted. The efficiency, torque ripple, and total harmonic distortion of the inner and outer armature windings of the generator after optimization are calculated to verify the effectiveness of the proposed machine design. [ABSTRACT FROM AUTHOR]

In this article, a novel winding switching strategy is proposed to improve the flux-weakening capability of a hybrid-excited reluctance machine (HERM). The key is that in low-speed operation, the primary and the secondary windings are connected in series and serve as armature winding to maximize output voltage while in high-speed operation, the secondary winding is switched to dc excitation winding to realize variable speed constant voltage output. The machine configuration, operation principle with dual excitation sources, winding switching concept, and manipulation circuit are illustrated in detail. Then the electromagnetic characteristics of HERM in different operation status are investigated. Finally, the variable speed constant voltage output of wind power generation system resorting to winding switching as well as dc excitation regulation is verified with Maxwell/Simplorer cosimulation. [ABSTRACT FROM AUTHOR]

Due to the flux leakage and large detent force, the thrust force ripple of transverse-flux linear motor is relatively large, which restricts its further application. Also, the field of most existing transverse-flux machines is hard to be altered and regulated considering the permanent magnet (PM) excitation. Therefore, to suppress the force ripple and strengthen the flux regulation capability of transverse-flux machines, a novel hybrid excitation transverse-flux tubular motor with complementary structure is proposed in this article. The key is that a complementary and parallel structure is constructed in this motor, and hybrid excitation of both dc windings and small auxiliary PMs installed at opening of the slot is adopted in this motor as well. In addition, unequal teeth design of dc winding and ac winding is also employed to increase the thrust force density. Finite element calculation results verify the effectiveness of the proposed machine. [ABSTRACT FROM AUTHOR]

This article proposes a novel model predictive control for a three-phase permanent-magnet synchronous motor (PMSM) with enhanced robustness against parameter variation and higher current control precision. First, the extended set of voltage vectors are adopted to increase the current control precision. Then, the parameter sensitivity problem is avoided in the first stage using an indirect reference vector strategy for the sake of computation time reduction. Subsequently, the inductance disturbance observer is adopted in the current prediction process to enhance the robustness against machine parameter mismatch. The intrinsic connection between the discrete control sets precision and disturbance observer is analyzed. The proposed method improves the robustness against parameter mismatch and current control precision simultaneously. Experimentations are conducted to verify the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This paper proposes a novel direct-drive dual-PM motor for electric automatic guided vehicles (AGV). The proposed motor has split teeth on stator and dual PMs in stator and rotor sides, which contributes to reduced torque ripple, and enhanced torque. The airgap field of the proposed motor is analyzed theoretically, and the slot/pole selection guide line is concluded. The simulation results of the airgap flux density are shown and Fourier Transformation (FFT) analysis results agree well with the theoretically analyses results. Besides, the effects of design parameters of the proposed motor to the performances of the proposed motor are investigated. And it is found that reduced slot open could produce improved efficiency and decreased torque ripple. The efficiency of the proposed motor is relatively high within the operation range. A corresponding prototype is fabricated and the experiment validates the design. [ABSTRACT FROM AUTHOR]

This article tackles the design problem for a permanent magnet Vernier machine with hybrid stator to achieve a high structure robustness, enhanced torque and improved power factor simultaneously. The key of the solution is divided into two parts. One is to solve the conflict between torque and power factor by deterministic optimization. The other is to optimize its robustness with the help of robust optimization. Firstly, sensitivity analysis is adopted to stratify design parameters. Afterwards, a multi-objective deterministic optimization is applied to achieve an optimal balancing design between the two competing objectives, torque and power factor. However, the deterministic optimization ignores the size deviation in actual production, which most likely results in the poor structure robustness. Therefore, robustness analysis is employed to check its robustness. Then, through the robustness optimization, the robustness of this machine is further improved on the basis of the deterministic optimization. Finally, a prototype machine is built and the experiments on the prototype machine are carried out to verify the validity of the robust optimization. [ABSTRACT FROM AUTHOR]

This article aims to propose a new hybrid reluctance machine equipped with relieving-dc-saturation (RDCS) ability for electric vehicle in-wheel drive. The proposed machine uses integrated ac and dc current excitation to eliminate extra dc field coils for the efficient torque generation. Besides, considering the inherent dc saturation in stator core caused by dc current excitation, slot PMs are artificially introduced to provide RDCS effect and thus boost torque density. Moreover, with a modular magnetic field configuration, the proposed topology exhibits excellent fault-tolerant potential at both open-circuit and short-circuit condition, making it suitable for safety-critical in-wheel vehicle propulsion. In this article, the machine configuration and operation principle are introduced, with emphasis on its RDCS effect and corresponding design consideration. Further, performance of this new topology is evaluated by both finite element analysis and prototype experiments. It is revealed that, with this RDCS ability, torque density of the proposed machine can be enhanced by about 25% under relatively high current density. [ABSTRACT FROM AUTHOR]

Benefiting from flexible flux control and short-circuit withstand ability, the hybrid excitation machine is an emerging starter generator solution for hybrid electric vehicle propulsion. However, to realize a brushless hybrid design in conventional permanent magnet machines, a three-dimensional magnetic circuit is usually adopted, leading to complicated mechanical structure and torque density sacrifice. To address this issue, a new relieving-dc-saturation hybrid excitation Vernier machine is proposed in this article, which integrates good torque density and bidirectional flux control within a simple and brushless structure. The key is to artificially construct reluctance effect in a consequent-pole Vernier permanent magnet machine (CP-VPMM) by introducing extra dc field excitation equipped with the relieving-dc-saturation ability. In this way, the advantages of bidirectional flux control in stator-dc-excited reluctance machine and good torque density in CP-VPMM are well combined in this topology, making it especially suitable for multimode starter generator application. In this article, the machine structure and its design mechanism are introduced, with its electromagnetic performance evaluated by the finite-element simulation. A prototype is manufactured and tested. Experiment results verify the feasibility of this new topology. [ABSTRACT FROM AUTHOR]

Owing to bidirectional field modulation effect, dual-permanent-magnet-excited (DPME) machine could offer improved torque capability, which has attracted increasing attention in recent years. However, conventional DPME machine only utilizes a small amount of abundant field harmonics to yield torque, which leads to limited torque enhancement. To solve this issue, a novel DPME machine with enriched working harmonics is proposed in this paper. The key of the proposed DPME machine is to design some non-uniformly distributed permanent-magnets and flux modulation poles on the stator. Thus, increased field harmonics are produced to produce effective torque, offering the potential to enhance torque. Firstly, the topology and feature of the machine are introduced. Moreover, operating principle is analyzed by using air gap field modulation theory. Then, the operating principle and torque enhancement are verified and evaluated by using finite-element method. At last, a corresponding principle machine is fabricated, and some experiments are performed for validation. [ABSTRACT FROM AUTHOR]

This paper aims to propose a new Vernier reluctance machine (VRM), which integrates the advantages of a robust rotor structure, good torque density, and flexible flux control ability. The key is to establish the excitation field with both stator slot permanent magnets (PMs) and zero-sequence current. Two excitation sources have different pole pair numbers but share a parallel magnetic circuit and contribute to superimposed torque in this machine. Meanwhile, a flexible flux control can be achieved by regulating zero-sequence current, and little demagnetization risk exists for slot PMs during flux control. In this paper, the machine configuration and operation principle are introduced, along with its integrated ac and dc drive method. Electromagnetic performance of this new machine is evaluated by finite-element analysis. Leading design parameters are determined and optimized considering optimal injection ratio of zero-sequence current. A prototype is fabricated, and relevant experiment results demonstrate the feasibility of the proposed solution. [ABSTRACT FROM AUTHOR]