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To address the issues of magnetic parameter dependence and insufficient dynamic performance in high-speed sensorless control of switched reluctance motors (SRMs), this article proposes a sensorless control scheme based on the delayed signal cancellation flux observer (DSCFO) for high-speed SRM drives. This scheme improves the dynamic performance while achieving sensorless control, without the need for magnetic characteristics. Due to the superior filtering efficiency of the DSCFO, the proposed observer eliminates the non-linear terms in the calculated single-phase flux linkage and extracts a pair of orthogonal signals with positional information. Following this, the rotor position and speed information are estimated through the phase locked loop, enabling sensorless control. Finally, experiments are conducted on a three-phase 5.5 kW 12/8 SRM experimental setup to verify the effectiveness of the proposed scheme. Experimental results indicate that compared to other methods, the proposed approach can achieve sensorless control with only single-phase while possessing desirable accuracy and stronger robustness.

To make full use of the advantages of dual three-phase permanent magnet synchronous motor (DTP-PMSM) and three-phase open-winding permanent magnet synchronous motor (OW-PMSM), this article proposed a novel typology of the motor drive which can switch between dual three-phase (DTP) structure and three-phase open-winding (OW) structure online. On this basis, the basic control and fault-tolerant control are studied to explore the superiority of the proposed typology. Under healthy conditions, no adjustment is required for the modulation method of the proposed control scheme when switching between DTP and OW mode. By using two bidirectional thyristors, smooth switching between the two modes can be guaranteed. Besides, the power weight of two inverters can be adjusted by changing the current ratio in DTP mode and changing the voltage ratio in OW mode. For the fault-tolerant control, when an open-phase fault occurs, DTP mode will be used to provide sufficient dimensions of current control and the fault-tolerant scheme can be realized through current compensation without changing the control framework. When an open-switch fault or short-switch fault occurs, OW mode will be adopted to guarantee symmetrical phase currents, and the remaining healthy switches in the faulty inverter are fully used to share the loss of the healthy inverter. The experiment has been conducted to prove the feasibility and superiority of the proposed typology and control scheme.

Parameter estimation of permanent magnet synchronous motors (PMSMs) is broadly researched, while the parameter observability has not been well-discussed. This article employs the local weak observability theory to obtain unified observable conditions and give a definite reference for parameter estimation. Based on the results, a novel machine parameter estimation algorithm based on convex optimization is proposed to verify these conditions. This scheme establishes an integrated cost function and solves it by the numerical method to estimate parameters. Then, with the proposed approach, several parameters are obtained together by one estimator, which avoids multiple observer designs and reduces the system's complexity. Moreover, convergency analyses of the cost function demonstrate that the states of PMSMs are locally weakly observable at the unified conditions. Finally, the stability of the observable conditions and the feasibility of the proposed method are verified on a 4-kW PMSM experimental setup. © 1986-2012 IEEE.

To fully suppress the current harmonics of torque plane and zero-sequence dimension in open-end winding (OW) permanent-magnet synchronous motor (PMSM), a novel 3-D space vector pulsewidth modulation (SVPWM) strategy is proposed in this article. First, the distribution of 3-D space vectors is analyzed. Then, a subspace-based vector selection method is developed to utilize the adjacent vectors in space to synthesize the reference vector. On this basis, a repetitive controller is equipped for zero-sequence current to guarantee precise current tracking. By using the proposed 3D-SVPWM strategy, the current controls in 3D can be well balanced. Besides, the fault-tolerant control of open-phase fault in OW PMSM drive is realized with the proposed 3D-SVPWM strategy by simply changing zero-sequence current reference. The experiments are carried out to prove the effectiveness of the proposed strategy.

Although the torque and radial force ripples are two important causes of unwelcomed vibration in switched reluctance machines, the suppression of these ripples is usually contradictory. To address this issue, we propose a model predictive torque and force control (MPT&FC) method. First, the torque and force sharing functions are constructed based on the flux-linkage curve, following which the sharing functions are optimized online by tuning the turn-ON angle to minimize the torque and force ripple. Finally, the MPT&FC method is applied to complete the sharing function tracking control. For balanced control of the torque and radial force, we optimize the candidate-voltage-vector table. Experiments were done on a three-phase 12/8 switched reluctance machine to verify that the proposed method suppresses vibrations.

This article proposed a universal model predictive control (MPC) strategy for dual inverters fed open-winding permanent magnet synchronous motor drives where two isolated buses have arbitrary dc voltages. Diverse and unordered space vector distribution caused by different voltage ratios of dc buses that greatly increase the calculation burden for the conventional MPC algorithm is analyzed in detail. Based on this, a novel MPC strategy that is universally applicable to any voltage ratio is put forward, which could decrease the number of candidate vectors from 49 to less than 15 in every cycle. Although the computational burden is reduced, the output power quality is unaffected owing to the effective simplification of the vectors. Besides, an optimized switching algorithm is designed to adapt to the situation when the voltage ratio changes during the operation state. The experimental results are presented to verify the effectiveness of the proposed method.

A novel two-mode inverter-based open-winding permanent magnet synchronousmotor drive is proposed in this article. The proposed drive operates in hybrid-inverter mode at low and medium speed to achieve high power quality. The common dc-bus mode is adopted at high speed to fulfill a wider speed range than hybrid-inverter mode. Based on the proposed drive, a modulation strategy for any voltage ratio is proposed, which integrates the instantaneous floating capacitor (FC) voltage into modulation to synthesize the reference voltage vector. The proposed modulation strategy can not only guarantee the FC voltage regulation but also start the drive when the FC voltage is zero and switch the mode of the drive smoothly. Besides, the excellent fault-tolerant capability of the proposed drive is studied under open-phase and switch faults. In the proposed fault-tolerant control, a sinusoidal zero-sequence current is injected to tolerate the open-phase fault in the common dc-bus mode and redundant switching combinations are used to tolerate switch faults in the hybrid-inverter mode. All the claimed advantages have been validated by experimental results.

The increasing power density of permanent magnet synchronous motors has led to a severe motor heating problem that demands precise rotor temperature information to avoid demagnetization. Traditional temperature estimation techniques rely on thermal models that require specialized knowledge in motor design, thermodynamics, and material science. However, thermal parameters are often hard to obtain in real applications and contain significant mismatches when the working environment of motors varies. To overcome this challenge, this letter proposes an ensemble data-driven approach using the gradient boosting decision tree (GBDT) to estimate the temperature of the permanent magnet. The proposed scheme uses the temperature data at the stator tooth, winding, and yoke to predict the rotor temperature. The GBDT technique offers advantages in terms of accuracy and versatility due to its strong capability in handling complex data in various motor operating conditions, making it well-suited for industrial applications. The experimental results of a high-power machine validate the greatly improved accuracy in rotor temperature estimation over other approaches.

A unified unsaturated-reluctance-based wide speed range sensorless control method for switched reluctance machines (SRMs) is proposed in this paper. Firstly, the sensitivity analysis of the estimated position to the possible reluctance calculation error is analyzed. This analysis reveals the feasible regions with low sensitivity and low risk of entering saturation. Then, the unsaturated reluctance in these feasible regions is obtained and modeled. A simple second-order rational expression is proposed to fit the highly nonlinear unsaturated reluctance curve. With this simple model, the rotor position can be analytically calculated only by solving a simple quadratic problem. Based on the above-presented analysis, a wide-speed range sensorless control is developed. The rotor position is universally estimated from the real-time reluctance value and the proposed analytical model. The high-frequency voltage injection and normal conduction phase are combined to calculate the phase reluctance over the wide-speed range. The concerns of calculating reluctance at the low-speed range are also discussed. A 5.1 kW four-phase 8/6 SRM is used to verify the proposed method. Various steady state and transient state experimental results prove the effectiveness of the proposed sensorless control method.

The maximum efficiency per ampere (MEPA) control strategy stands out as a highly effective means of improving the efficiency of a synchronous reluctance motor (SynRM) drive. This paper introduces an improved approach to optimizing efficiency that treats the motor and inverter as a unified system, ensuring maximum efficiency throughout operation. Diverging from conventional id=iq or maximum torque per ampere control methods, this approach accounts for both iron losses and inverter losses, while also addressing cross-coupling effects. This is achieved through real-time virtual signal injection, which extracts optimal operation points, and an accurate analytical approach to assess iron losses. Experimental results convincingly validate the effectiveness of this novel methodology. © 2023 IEEE.

Electric vehicles require high-power machines, so reducing power loss becomes crucial. Compared to space vector modulation, synchronous optimal pulse width modulation (SOP) has several advantages in high-speed applications, like the capability to operate at a very low switching frequency with lower total harmonic distortion, and reduced losses. This article presents a comprehensive review after performing a systematic investigation on different inverter topologies, including two-level voltage source inverters and multilevel inverter topologies with SOP as the modulation scheme. Several optimal pulsewidth methods will be studied along with SOP design methods, including steady state and dynamic switching. More emphasis is given to the various challenges faced in implementing SOP, followed by future trends. IEEE

This paper presents a simple and practical method to estimate the lumped radial force characteristics for the switched reluctance machines (SRMs). Firstly, the relationship between the square root of the lumped radial force and the flux-linkage is discussed and analyzed. With the geometry data of the studied SRM, the above relationship under nominal airgap length and nominal material magnetic property conditions can be obtained through the finite element analysis (FEA) software. Since the radial flux density dominates the magnitude of the radial force and it concentrates on the overlapping area, the above relationship is analyzed to be roughly held when the airgap length and/or material magnetic property vary. Based on this relationship obtained from FEA and the actual measured flux-linkage characteristics, the lumped radial force can be easily reconstructed for the actual SRMs regardless of the possible airgap length variation and material magnetic property deviation during the manufacturing process. Simulation results on the 8/6 SRM and 12/8 SRM verify that the proposed method provides good radial force estimation results when the airgap length is reduced or increased up to 50%. Superior estimation results are also observed on the condition that the magnetic BH curve is linearly varied by ±25%. The accurate and simple radial force estimation method proposed in this paper provides a solid basis for the radial-force-shaping-based advanced control methods to suppress the acoustic noise.

In recent years, permanent magnet synchronous motors (PMSMs) are widely used in electric vehicles due to the high-power density. The increasing power density of PMSMs can result in the rapid temperature rise, which leads to a negative impact on the machine. The high temperature may lead to weakened winding insulation in the stator slots and the irreversible demagnetization of permanent magnet. In order to avoid overheating running, massive methods aiming to estimate the temperature inside PMSMs are investigated. However, traditional methods like Lumped Parameter Thermal Networks (LPTNs) require massive domain knowledge and accurate parameters. Therefore, a model-free data driven approach based on support vector regression is proposed to estimate the temperature inside the PMSM in this paper. © 2022 IEEE.

The vibration/noise and torque ripple are two inherent issues for switched reluctance motors (SRMs), one of the effective methods to address these two issues is flattening both the total radial force and total torque. In this paper, an optimized quadratic-sharing-function-based radial force and torque simultaneous flattening method is proposed for SRMs. Firstly, the features of the radial force and torque characteristics are analyzed without considering saturation. Then, with these unique and specific features, four regions are defined to develop the simultaneous radial force and torque control method based on the linear sharing functions. To incorporate the saturation effects in the proposed method, the quadratic sharing functions are adopted. The proper parameters of the quadratic sharing functions and the region definition at different operating conditions are obtained through the genetic algorithm (GA) optimization. The switching angles and reference current of the conventional current chopping control (CCC) method are also optimized by GA for fair comparison purpose. Extensive simulation results are presented in this paper, and these results prove the effectiveness and superiority of the proposed method regarding the simultaneous radial force and torque control. © 2022 IEEE.

Synchronous optimal pulse-width modulation (SOPWM) is an effective solution to reduce switching frequency without increasing the current distortion. This method is widely used along with stator flux tracking in traction applications of induction motors. However, stator flux tacking is not an ideal control technique for permanent magnet synchronous motors (PMSMs). This paper studies SOPWM with stator current tracking for PMSM traction applications. Stator current tracking with SOPWM suffers poor steady-state performance when the PMSM operates around discontinuity of the switching angles due to the voltage disturbance generated from current harmonics. This problem is usually solved by using continuous switching angles. However, this approach brings more overall current distortion due to sub-optimal switching angles. To address this issue, a novel hysteresis control-based SOPWM scheme with continuous switching angles is proposed. Preliminary simulation results indicate that the proposed method can offer low current distortion compared to conventional and continuous SOPWMs. © 2022 IEEE.

Open-phase fault (OPF) and open-switch fault (OSF) are two common electrical faults in the permanent magnet synchronous machine (PMSM) drives. To locate the faults rapidly and relieve the fault damage, a current prediction based diagnosis scheme is proposed for OPF and OSF in three-phase PMSM drives. The proposed diagnosis scheme consists of three steps, namely determining fault occurrence, locating the faulty phase, and identifying the specific fault. The general current deviations between dq-axis predicted currents from the normal model and dq-axis feedback currents are used to determine the fault occurrence. The general current deviations between dq-axis feedback currents and dq-axis predicted currents from different faulty models are used to locate the faulty phase. Then, an intervention-based diagnosis is developed to identify the specific fault. In this way, the specific fault can be quickly located within several switching periods. Finally, the effectiveness of the proposed diagnosis scheme is verified by the experimental results. IEEE

In this article, a general-purpose low-speed position estimation scheme using pulse injection is proposed for sensorless switched reluctance motor (SRM) drives. For the conventional low-speed sensorless control methods, magnetic characteristics are often used for position estimation, but it requires offline measurement and reduces the generality of sensorless control algorithms. To solve the issue, a new position estimator based on a regional phase-locked loop (RPLL) is designed. The approach utilizes a self-commissioning process to capture the unsaturated inductance adaptively at the initial stage. The RPLL is then adopted to estimate the full-cycle rotor position from the idle-phase inductance during sensorless operation. The speed-reversible sensorless control capability is also realized by a simple heterodyne design. Furthermore, stability analyses and parameter design are given to prove the robust local stability and convergence. Finally, comparative experimental validation is conducted on a 5.5-kW 12/8 SRM setup to verify the proposed method's effectiveness under both no-load and load conditions.

High-speed position-sensorless control of switched reluctance motor (SRM) drives is often realized by searching a priori flux linkage lookup table. However, obtaining the nonlinear flux linkage characteristic requires time-consuming offline measurement and occupies large memory storage. To deal with this problem, this article proposes a new position estimation scheme for SRM drives without using any magnetic characteristics. This feature is achieved by using a quadrature flux estimator (QFE) that can extract the fundamental flux and its quadrature signal from the real-time calculated flux linkage. The flux bias and flux harmonics can also be suppressed by the QFE’s adaptive bandpass capability. Therefore, the proposed method can reduce the nonlinearity in SRM flux linkage and derive simple sine–cos position signals. Afterward, the rotor position and speed can be estimated from the orthogonal flux signals using a three-phase phase-locked loop. To baseline the advantages, comparative experimental validation with the conventional method is conducted on a three-phase 12/8 SRM test bench. The results show that the proposed scheme can achieve the same estimation accuracy as the conventional method even though no magnetic characteristics are used.

In this article, a low-ripple continuous control set (CCS) model predictive torque control (MPTC) method for switched reluctance machines (SRMs) is proposed. The inherent high nonlinearity of the SRMs makes it difficult to solve the optimization problem in the CCS MPTC algorithm analytically. To address this issue, an equivalent linear SRM model is adopted, and the cost function is also properly modified. Then, with the torque boundary values provided by executing the voltage vectors of an improved switching table, the optimization problem in the CCS MPTC method becomes simple and analytically solvable. The Lagrange multiplier method is employed to solve this optimization problem analytically and generate the optimum torque reference values for the active phases. Based on the estimated torque variation rates, the duty cycles for each phase are calculated. Extensive simulation and experimental tests are carried out in a four-phase 8/6 SRM setup. These testing results reveal that the proposed CCS MPTC method shows much lower torque ripples and current ripples in a wide speed range with a low computational burden than the existing finite control set MPTC methods.