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Electric Machines & Control Application (CN 31-1959/TM, ISSN 1673-6540) was founded in 1959 in title of Technical Information of Small and Medium-sized Electric Machines. The title was changed to Small and Medium-sized Electric Machines in 1977, and then changed to its current title in 2005. The journal is sponsored by Shanghai Electrical Apparatus Research Institute (Group) Co., Ltd., aims to publish cutting-edge achievements in various research fields related to the electrical science. The journal is a source journal of the Comprehensive Evaluation Database of Chinese Academic Journals, and the full text articles are included in Chinese Academic Journals (CD). It has been included in Chinese Core Journals and Key Magazine of China Technology for years. Recently, it has also been included in Scopus, EBSCO, DOAJ, EuroPub, Research4Life, ICI world of Jourmals, ICI Journal Master Lister, Japan Science and Technology Agency database (JST, Japan) and Abstract Journals (AJ, Russia). The impact factor is steadily increasing year by year. Electric Machines and Control Application is published on the 10th of each month and is publicly distributed domestically and internationally. The post issuing code is 4-199.
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2026(3):212-225, DOI: 10.12177/emca.2026.136
Abstract:
[Objective] Aiming at the technical challenge of balancing the accuracy and efficiency of online wideband impedance measurement of wind turbines, this paper proposes a hybrid measurement method that integrates key frequency targeted high-precision injection and wideband impedance transfer reconstruction. [Methods] Firstly, the standard simulation model was constructed based on the target wind turbines to obtain its all-operating-conditions wideband impedance data model. Secondly, the key frequency point set was screened, and the impedance data of the target wind turbines at the key frequency points were obtained online via targeted injection of single-sine signals. Finally, the discrete key frequency point impedance was extended to the target frequency band by employing transfer reconstruction technology, and fast online measurement of wideband impedance characteristics of the wind turbines was realized. [Results] The effectiveness of the proposed hybrid measurement method was verified by simulation and controller hardware-in-the-loop experiments. The experimental results showed that under the influence of 30 dB noise, the measurement accuracy of the proposed hybrid measurement method was comparable to that of the traditional single-sine frequency sweep method, while the measurement time was reduced by more than 85%. [Conclusion] The proposed hybrid measurement method significantly reduces the online measurement frequency points while retaining the high-precision advantages of single-sine signal injection, thus effectively improving the measurement efficiency.
[Objective] Aiming at the technical challenge of balancing the accuracy and efficiency of online wideband impedance measurement of wind turbines, this paper proposes a hybrid measurement method that integrates key frequency targeted high-precision injection and wideband impedance transfer reconstruction. [Methods] Firstly, the standard simulation model was constructed based on the target wind turbines to obtain its all-operating-conditions wideband impedance data model. Secondly, the key frequency point set was screened, and the impedance data of the target wind turbines at the key frequency points were obtained online via targeted injection of single-sine signals. Finally, the discrete key frequency point impedance was extended to the target frequency band by employing transfer reconstruction technology, and fast online measurement of wideband impedance characteristics of the wind turbines was realized. [Results] The effectiveness of the proposed hybrid measurement method was verified by simulation and controller hardware-in-the-loop experiments. The experimental results showed that under the influence of 30 dB noise, the measurement accuracy of the proposed hybrid measurement method was comparable to that of the traditional single-sine frequency sweep method, while the measurement time was reduced by more than 85%. [Conclusion] The proposed hybrid measurement method significantly reduces the online measurement frequency points while retaining the high-precision advantages of single-sine signal injection, thus effectively improving the measurement efficiency.
2026(3):226-235, DOI: 10.12177/emca.2026.135
Abstract:
[Objective] In the sensorless control system of permanent magnet synchronous motors, the traditional full-order sliding mode observer (FOSMO) adopts a fixed sliding mode gain, which fails to simultaneously balance the dynamic response speed and steady state performance of the system over a wide speed range. This leads to severe system chattering during the low speed operation of the motor, thereby reducing the observation accuracy of the rotor position and speed. [Methods] To address the aforementioned contradictions, this paper proposed an adaptive FOSMO based on current error and estimated speed. The sliding mode gain was dynamically adjusted according to the real-time operating state of the system, achieving smooth regulation under different operating conditions, thereby enhancing the dynamic performance and steady state accuracy of the system. Furthermore, to further suppress the chattering caused by high-frequency switching, a continuous and smooth hyperbolic tanh function was introduced to replace the traditional sign function. Meanwhile, the Lyapunov stability theory was employed to conduct mathematical derivation of the improved observer, which verified the convergence of the observer. [Results] The observation performance of the proposed adaptive FOSMO was verified through simulations and experiments. The results showed that, compared with the traditional FOSMO, the proposed adaptive FOSMO significantly suppressed the chattering of the extended back electromotive force waveforms and speed waveforms in the low speed region, remarkably reduced the rotor position estimation error, and achieved higher observation accuracy. [Conclusion] Under the proposed adaptive FOSMO, the system chattering is significantly suppressed, the overall stability of the system is improved, and the adaptive FOSMO has a wider applicable speed range.
[Objective] In the sensorless control system of permanent magnet synchronous motors, the traditional full-order sliding mode observer (FOSMO) adopts a fixed sliding mode gain, which fails to simultaneously balance the dynamic response speed and steady state performance of the system over a wide speed range. This leads to severe system chattering during the low speed operation of the motor, thereby reducing the observation accuracy of the rotor position and speed. [Methods] To address the aforementioned contradictions, this paper proposed an adaptive FOSMO based on current error and estimated speed. The sliding mode gain was dynamically adjusted according to the real-time operating state of the system, achieving smooth regulation under different operating conditions, thereby enhancing the dynamic performance and steady state accuracy of the system. Furthermore, to further suppress the chattering caused by high-frequency switching, a continuous and smooth hyperbolic tanh function was introduced to replace the traditional sign function. Meanwhile, the Lyapunov stability theory was employed to conduct mathematical derivation of the improved observer, which verified the convergence of the observer. [Results] The observation performance of the proposed adaptive FOSMO was verified through simulations and experiments. The results showed that, compared with the traditional FOSMO, the proposed adaptive FOSMO significantly suppressed the chattering of the extended back electromotive force waveforms and speed waveforms in the low speed region, remarkably reduced the rotor position estimation error, and achieved higher observation accuracy. [Conclusion] Under the proposed adaptive FOSMO, the system chattering is significantly suppressed, the overall stability of the system is improved, and the adaptive FOSMO has a wider applicable speed range.
2026(3):236-248, DOI: 10.12177/emca.2026.140
Abstract:
[Objective] Aiming at the difficulty of directly detecting the current in permanent magnet synchronous motor (PMSM) equipped with inductor-capacitor-transformer (LCT) high-order filter, this paper proposes a current cascaded observation method based on an extended state observer (ESO) and a Luenberger state observer (LSO). [Methods] The novel ESO cascaded method proposed in this paper required only the inverter-side current signal. The intermediate system state was obtained through the LSO, and disturbances were estimated and compensated in real-time by the ESO, achieving high-precision observation of the motor current. [Results] The experimental results showed that, under rated conditions, the motor current observation error was reduced by 3.2% with the novel ESO cascaded method proposed in this paper compared to the traditional LSO. [Conclusion] The proposed method achieves high-precision observation of high-order filtered PMSM current without requiring additional sensors or hardware modifications, effectively reducing system complexity and cost.
[Objective] Aiming at the difficulty of directly detecting the current in permanent magnet synchronous motor (PMSM) equipped with inductor-capacitor-transformer (LCT) high-order filter, this paper proposes a current cascaded observation method based on an extended state observer (ESO) and a Luenberger state observer (LSO). [Methods] The novel ESO cascaded method proposed in this paper required only the inverter-side current signal. The intermediate system state was obtained through the LSO, and disturbances were estimated and compensated in real-time by the ESO, achieving high-precision observation of the motor current. [Results] The experimental results showed that, under rated conditions, the motor current observation error was reduced by 3.2% with the novel ESO cascaded method proposed in this paper compared to the traditional LSO. [Conclusion] The proposed method achieves high-precision observation of high-order filtered PMSM current without requiring additional sensors or hardware modifications, effectively reducing system complexity and cost.
2026(3):249-258, DOI: 10.12177/emca.2026.137
Abstract:
[Objective] To reduce the harmonic content and operating losses of high-power AC/DC converter, and realize the bidirectional energy flow, this paper proposes a rectification scheme consisting of a phase-shifting transformer (3→3N) combined with multi-pulse uncontrolled rectification. [Methods] The proposed scheme employed phase-shifting technology to expand three-phase into 3N phase, resulting in a denser phase distribution on the AC side, which effectively increased the rectification pulse frequency and reduced low-order harmonics. Meanwhile, multi-path current splitting reduced the current amplitude of each branch and achieved current sharing. The uncontrolled rectifier eliminated the switching losses caused by switching devices, with only conduction losses presented, thereby further reducing the overall system losses. The proposed scheme was compared and analyzed with two other schemes: three-phase transformer+six-pulse uncontrolled rectification and three-phase transformer + insulated gate bipolar transistor (IGBT) fully controlled rectification. The total harmonic distortion (THD) was evaluated using the root mean square calculation method based on fast Fourier transform, and the conversion efficiency was calculated as the ratio of output power to input power under steady-state conditions. [Results] The simulation results showed that under identical filter parameters and load conditions, the THD of the proposed multi-pulse uncontrolled rectification scheme was the lowest, at 7.57%, which was significantly superior to 12.87% for the IGBT rectification scheme and 17.96% for the three-phase uncontrolled rectification scheme. At full load, the efficiencies of the three schemes were 91.2%, 88.2%, and 87.8%, respectively. In the upgraded phase-shifting multi-pulse uncontrolled rectification low harmonic bidirectional extended topology, the battery current could smoothly cross zero and achieved commutation. [Conclusion] The proposed multi-pulse topology achieves low harmonic distortion and low-loss operation with minimal control complexity. The hybrid scheme combined with the fully controlled structure further expands the bidirectional energy flow capability.
[Objective] To reduce the harmonic content and operating losses of high-power AC/DC converter, and realize the bidirectional energy flow, this paper proposes a rectification scheme consisting of a phase-shifting transformer (3→3N) combined with multi-pulse uncontrolled rectification. [Methods] The proposed scheme employed phase-shifting technology to expand three-phase into 3N phase, resulting in a denser phase distribution on the AC side, which effectively increased the rectification pulse frequency and reduced low-order harmonics. Meanwhile, multi-path current splitting reduced the current amplitude of each branch and achieved current sharing. The uncontrolled rectifier eliminated the switching losses caused by switching devices, with only conduction losses presented, thereby further reducing the overall system losses. The proposed scheme was compared and analyzed with two other schemes: three-phase transformer+six-pulse uncontrolled rectification and three-phase transformer + insulated gate bipolar transistor (IGBT) fully controlled rectification. The total harmonic distortion (THD) was evaluated using the root mean square calculation method based on fast Fourier transform, and the conversion efficiency was calculated as the ratio of output power to input power under steady-state conditions. [Results] The simulation results showed that under identical filter parameters and load conditions, the THD of the proposed multi-pulse uncontrolled rectification scheme was the lowest, at 7.57%, which was significantly superior to 12.87% for the IGBT rectification scheme and 17.96% for the three-phase uncontrolled rectification scheme. At full load, the efficiencies of the three schemes were 91.2%, 88.2%, and 87.8%, respectively. In the upgraded phase-shifting multi-pulse uncontrolled rectification low harmonic bidirectional extended topology, the battery current could smoothly cross zero and achieved commutation. [Conclusion] The proposed multi-pulse topology achieves low harmonic distortion and low-loss operation with minimal control complexity. The hybrid scheme combined with the fully controlled structure further expands the bidirectional energy flow capability.
2026(3):259-268, DOI: 10.12177/emca.2026.128
Abstract:
[Objective] To address the issues of low trajectory tracking accuracy, slow dynamic response, and difficult parameter tuning inherent in traditional position-speed-current triple-loop control system for high-speed, high-precision galvanometer motors, this paper proposes a position-current dual-loop servo control strategy based on lead correction under time-delay conditions. [Methods] Firstly, the limitations of the traditional triple-loop architecture and the operating mechanism of the dual-loop scheme were analyzed, and the stabilizing effect of the proportional-integral-lead (PI-Lead) controller on the dual-loop system was demonstrated. Secondly, the impact of phase loss caused by time-delay on trajectory tracking accuracy and transient response speed was investigated. A time-delay-compensated PI-Lead (PI-Lead-TDC) controller was proposed to compensate for the phase loss induced by delay. Finally, a closed-loop frequency-domain parameter tuning strategy was proposed, wherein frequency-domain parameters were designed based on theoretical paradigms to enhance parameter tuning speed. [Results] Experimental results showed that, compared to the traditional triple-loop control system, the proposed dual-loop control system exhibited a significantly reduced root mean square error in sinusoidal trajectory tracking. Furthermore, for a 1% stroke step command, the response speed was improved by 20%. [Conclusion] Compared to traditional triple-loop control system, the proposed dual-loop control system based on PI-Lead-TDC achieves higher trajectory tracking accuracy, faster dynamic response speed, and a more efficient and simplified parameter tuning process.
[Objective] To address the issues of low trajectory tracking accuracy, slow dynamic response, and difficult parameter tuning inherent in traditional position-speed-current triple-loop control system for high-speed, high-precision galvanometer motors, this paper proposes a position-current dual-loop servo control strategy based on lead correction under time-delay conditions. [Methods] Firstly, the limitations of the traditional triple-loop architecture and the operating mechanism of the dual-loop scheme were analyzed, and the stabilizing effect of the proportional-integral-lead (PI-Lead) controller on the dual-loop system was demonstrated. Secondly, the impact of phase loss caused by time-delay on trajectory tracking accuracy and transient response speed was investigated. A time-delay-compensated PI-Lead (PI-Lead-TDC) controller was proposed to compensate for the phase loss induced by delay. Finally, a closed-loop frequency-domain parameter tuning strategy was proposed, wherein frequency-domain parameters were designed based on theoretical paradigms to enhance parameter tuning speed. [Results] Experimental results showed that, compared to the traditional triple-loop control system, the proposed dual-loop control system exhibited a significantly reduced root mean square error in sinusoidal trajectory tracking. Furthermore, for a 1% stroke step command, the response speed was improved by 20%. [Conclusion] Compared to traditional triple-loop control system, the proposed dual-loop control system based on PI-Lead-TDC achieves higher trajectory tracking accuracy, faster dynamic response speed, and a more efficient and simplified parameter tuning process.
2026(3):269-278, DOI: 10.12177/emca.2026.139
Abstract:
[Objective] As an emerging intelligent control technology, deep reinforcement learning (DRL) has demonstrated remarkable potential in the field of motor drive system control. In this regard, this paper researches and designs an advanced DRL-based drive control architecture for permanent magnet synchronous motor (PMSM), aiming to achieve high-precision, model-free robust control without relying on the accurate identification of motor physical parameters. [Methods] This paper combined the deep Q-network with finite control set torque control, directly outputting the switching states of the inverter through online learning, thus enabling the agent to determine the optimal switching states of the inverter directly via continuous online learning and interaction with the motor environment. Firstly, a comprehensive multi-level reward function was designed to reflect the complex characteristics of the PMSM, simultaneously accommodating multiple optimization objectives including high-fidelity torque tracking, stator current amplitude minimization, and overall energy efficiency maximization. Secondly, to bridge the gap between theoretical exploration and practical safety requirements, a novel safety protection and evaluation mechanism based on current constraints was established. This mechanism ensured that the inherent random exploration process of DRL did not lead to system overcurrent or hardware damage. Finally, the convergence and control performance of the algorithm were effectively improved by introducing the Q-learning structure and an automated hyperparameter optimization method. [Results] The simulation results showed that the average reward value stabilized at approximately 1 after 400 training episodes, which verified the excellent convergence of the proposed algorithm. The algorithm accurately tracked the torque commands and maintained fast response speeds with minimal steady-state errors under various speed and load step conditions. With the valid weight coefficients, the system successfully balanced torque precision and operational efficiency. Furthermore, the safety protection mechanism effectively truncated the expected future returns of high-risk states via the done signal, ensuring that the stator current was strictly confined within the safety threshold, which validated the robustness of the model even in small-sample scenarios. [Conclusion] The proposed scheme achieves high-performance model-free torque control, and its integrated safety assessment mechanism provides a scientific foundation and novel insights for preventive operation and maintenance alongside the application of reinforcement learning in the power electronics field, as well as a new research direction for intelligent motor control.
[Objective] As an emerging intelligent control technology, deep reinforcement learning (DRL) has demonstrated remarkable potential in the field of motor drive system control. In this regard, this paper researches and designs an advanced DRL-based drive control architecture for permanent magnet synchronous motor (PMSM), aiming to achieve high-precision, model-free robust control without relying on the accurate identification of motor physical parameters. [Methods] This paper combined the deep Q-network with finite control set torque control, directly outputting the switching states of the inverter through online learning, thus enabling the agent to determine the optimal switching states of the inverter directly via continuous online learning and interaction with the motor environment. Firstly, a comprehensive multi-level reward function was designed to reflect the complex characteristics of the PMSM, simultaneously accommodating multiple optimization objectives including high-fidelity torque tracking, stator current amplitude minimization, and overall energy efficiency maximization. Secondly, to bridge the gap between theoretical exploration and practical safety requirements, a novel safety protection and evaluation mechanism based on current constraints was established. This mechanism ensured that the inherent random exploration process of DRL did not lead to system overcurrent or hardware damage. Finally, the convergence and control performance of the algorithm were effectively improved by introducing the Q-learning structure and an automated hyperparameter optimization method. [Results] The simulation results showed that the average reward value stabilized at approximately 1 after 400 training episodes, which verified the excellent convergence of the proposed algorithm. The algorithm accurately tracked the torque commands and maintained fast response speeds with minimal steady-state errors under various speed and load step conditions. With the valid weight coefficients, the system successfully balanced torque precision and operational efficiency. Furthermore, the safety protection mechanism effectively truncated the expected future returns of high-risk states via the done signal, ensuring that the stator current was strictly confined within the safety threshold, which validated the robustness of the model even in small-sample scenarios. [Conclusion] The proposed scheme achieves high-performance model-free torque control, and its integrated safety assessment mechanism provides a scientific foundation and novel insights for preventive operation and maintenance alongside the application of reinforcement learning in the power electronics field, as well as a new research direction for intelligent motor control.
2026(3):279-287, DOI: 10.12177/emca.2026.131
Abstract:
[Objective] To address the cogging torque suppression issue in axial flux permanent magnet synchronous motor (AFPMSM), this paper proposes an optimal design method based on an asymmetric slot depth structure, aiming to significantly suppress cogging torque and thus improve the operational stability and reliability of the motor. [Methods] Firstly, an analytical calculation model of cogging torque was established based on the energy method, and the general method for cogging torque suppression was theoretically derived. Then, taking a 20-pole 18-slot AFPMSM as the research object, a finite element simulation model was constructed, and a regulation method for the height dislocation difference of stator slot depth was proposed. By adjusting the height difference of adjacent stator teeth Δh, the variation laws of Δh on the harmonic distribution of air-gap magnetic flux density and cogging torque were systematically analyzed. Finally, the effectiveness and engineering feasibility of the proposed optimal design method were verified through simulation. [Results] The simulation results showed that on the premise that the slot fill factor met the working condition requirements, compared with the conventional AFPMSM, the asymmetric slot depth structure achieved the optimal cogging torque suppression effect when Δh=0.6 mm, with a suppression rate of 79.18%. [Conclusion] This paper verifies the effectiveness and feasibility of the asymmetric slot depth structure for cogging torque suppression, reduces the torque ripple by means of this structure, and thus provides a technical approach and reference for the electromagnetic optimal design of AFPMSM.
[Objective] To address the cogging torque suppression issue in axial flux permanent magnet synchronous motor (AFPMSM), this paper proposes an optimal design method based on an asymmetric slot depth structure, aiming to significantly suppress cogging torque and thus improve the operational stability and reliability of the motor. [Methods] Firstly, an analytical calculation model of cogging torque was established based on the energy method, and the general method for cogging torque suppression was theoretically derived. Then, taking a 20-pole 18-slot AFPMSM as the research object, a finite element simulation model was constructed, and a regulation method for the height dislocation difference of stator slot depth was proposed. By adjusting the height difference of adjacent stator teeth Δh, the variation laws of Δh on the harmonic distribution of air-gap magnetic flux density and cogging torque were systematically analyzed. Finally, the effectiveness and engineering feasibility of the proposed optimal design method were verified through simulation. [Results] The simulation results showed that on the premise that the slot fill factor met the working condition requirements, compared with the conventional AFPMSM, the asymmetric slot depth structure achieved the optimal cogging torque suppression effect when Δh=0.6 mm, with a suppression rate of 79.18%. [Conclusion] This paper verifies the effectiveness and feasibility of the asymmetric slot depth structure for cogging torque suppression, reduces the torque ripple by means of this structure, and thus provides a technical approach and reference for the electromagnetic optimal design of AFPMSM.
2026(3):288-299, DOI: 10.12177/emca.2026.133
Abstract:
[Objective] To address the challenges faced by drive motors for nuclear reactor control rods, including magnetic performance attenuation caused by the large air-gap structure, temperature rise limitation in high-temperature environments, and the complexity of multi-objective optimization, this paper proposes an optimization design method that balance efficiency and accuracy. This approach aims to enhance the output torque, operational stability, and thermal reliability of the motor. [Methods] Firstly, an electromagnetic design scheme was developed for the motor, determining the initial scheme of 24 slots and 4 poles pole-slot combination, radial "I" type rotor magnetic circuit and Recoma28 samarium-cobalt permanent magnet material. Secondly, seven key structural parameters were selected as optimization variables. Sample data were obtained based on maximum-minimum Latin hypercube sampling. Parameter sensitivity was analyzed using Pearson correlation coefficient, and a high-precision Kriging surrogate model was constructed to replace finite element simulation. Thirdly, the non-dominated sorting genetic algorithm II (NSGA-II) was employed to conduct multi-objective optimization targeting maximization of average torque and minimization of torque ripple. Finally, temperature field simulations were performed using Fluent software to validate the effectiveness of the designed cooling structure. [Results] After optimization, the average torque of the motor reached 17.074 N·m, which was 15.03% higher than the initial scheme, the torque ripple was reduced to 0.29%, with a decrease of 87.97%. The maximum temperature under rated working conditions was 117.8 ℃, and the temperature rise was 58 K, meeting the requirements of class F insulation and class B temperature rise limit. [Conclusion] The combination of Kriging surrogate model and NSGA-II effectively solves the problem of high computational complexity of multi-parameter optimization. On the premise of meeting structural and environmental constraints, the designed motor has significantly improved electromagnetic performance and thermal stability, which can provide reliable power support for the nuclear reactor control rod drive system.
[Objective] To address the challenges faced by drive motors for nuclear reactor control rods, including magnetic performance attenuation caused by the large air-gap structure, temperature rise limitation in high-temperature environments, and the complexity of multi-objective optimization, this paper proposes an optimization design method that balance efficiency and accuracy. This approach aims to enhance the output torque, operational stability, and thermal reliability of the motor. [Methods] Firstly, an electromagnetic design scheme was developed for the motor, determining the initial scheme of 24 slots and 4 poles pole-slot combination, radial "I" type rotor magnetic circuit and Recoma28 samarium-cobalt permanent magnet material. Secondly, seven key structural parameters were selected as optimization variables. Sample data were obtained based on maximum-minimum Latin hypercube sampling. Parameter sensitivity was analyzed using Pearson correlation coefficient, and a high-precision Kriging surrogate model was constructed to replace finite element simulation. Thirdly, the non-dominated sorting genetic algorithm II (NSGA-II) was employed to conduct multi-objective optimization targeting maximization of average torque and minimization of torque ripple. Finally, temperature field simulations were performed using Fluent software to validate the effectiveness of the designed cooling structure. [Results] After optimization, the average torque of the motor reached 17.074 N·m, which was 15.03% higher than the initial scheme, the torque ripple was reduced to 0.29%, with a decrease of 87.97%. The maximum temperature under rated working conditions was 117.8 ℃, and the temperature rise was 58 K, meeting the requirements of class F insulation and class B temperature rise limit. [Conclusion] The combination of Kriging surrogate model and NSGA-II effectively solves the problem of high computational complexity of multi-parameter optimization. On the premise of meeting structural and environmental constraints, the designed motor has significantly improved electromagnetic performance and thermal stability, which can provide reliable power support for the nuclear reactor control rod drive system.
2026(3):300-309, DOI: 10.12177/emca.2026.132
Abstract:
[Objective] To meet the requirements of the IE5 international maximum energy efficiency class and address the issues of high cost in permanent magnet motors, excessive material consumption in asynchronous motors for achieving IE5 efficiency class, and low power factor in pure reluctance motors, this study developed a series of permanent magnet assisted synchronous reluctance motor (PMASRM) featuring high efficiency, high power factor, and low cost. [Methods] Firstly, the influences of key parameters, including the number of motor poles, air gap length, the number of flux barrier layers, flux barrier ratio, and rotor rib width, on electromagnetic performance such as torque, efficiency, and power factor were systematically investigated. Then, the finite element method was employed for parameter optimization design and torque-angle characteristic simulation, through which the optimal current control angle was determined. Moreover, an electromagnetic-structural coupled strength analysis was conducted on the rotor flux barrier bridge to guarantee mechanical reliability. Finally, the trial production and testing of nine prototypes across six specifications were completed. [Results] All prototypes achieved the IE5 energy efficiency class, and their power factors generally exceeded the requirements of industrial standards. Cost analysis results demonstrated that, at the same output power, the total cost of active materials for this series of motors was lower than that of IE4 efficiency class induction motors and permanent magnet motors, showing a particularly significant cost advantage. [Conclusion] The series of PMASRM developed in this study have successfully achieved the IE5 energy efficiency target. They demonstrate outstanding cost-performance ratio across most commonly used speed points, integrating both energy-saving and material-saving characteristics. With substantial market potential, the proposed motor series provides robust technical support for enhancing the international competitiveness of China’s motor industry.
[Objective] To meet the requirements of the IE5 international maximum energy efficiency class and address the issues of high cost in permanent magnet motors, excessive material consumption in asynchronous motors for achieving IE5 efficiency class, and low power factor in pure reluctance motors, this study developed a series of permanent magnet assisted synchronous reluctance motor (PMASRM) featuring high efficiency, high power factor, and low cost. [Methods] Firstly, the influences of key parameters, including the number of motor poles, air gap length, the number of flux barrier layers, flux barrier ratio, and rotor rib width, on electromagnetic performance such as torque, efficiency, and power factor were systematically investigated. Then, the finite element method was employed for parameter optimization design and torque-angle characteristic simulation, through which the optimal current control angle was determined. Moreover, an electromagnetic-structural coupled strength analysis was conducted on the rotor flux barrier bridge to guarantee mechanical reliability. Finally, the trial production and testing of nine prototypes across six specifications were completed. [Results] All prototypes achieved the IE5 energy efficiency class, and their power factors generally exceeded the requirements of industrial standards. Cost analysis results demonstrated that, at the same output power, the total cost of active materials for this series of motors was lower than that of IE4 efficiency class induction motors and permanent magnet motors, showing a particularly significant cost advantage. [Conclusion] The series of PMASRM developed in this study have successfully achieved the IE5 energy efficiency target. They demonstrate outstanding cost-performance ratio across most commonly used speed points, integrating both energy-saving and material-saving characteristics. With substantial market potential, the proposed motor series provides robust technical support for enhancing the international competitiveness of China’s motor industry.
2026(3):310-317, DOI: 10.12177/emca.2026.130
Abstract:
[Objective] The existence of dead-time in the operation of a three-phase inverter results in the generation of high-order harmonics in both the output voltage and output current. Specifically, when switching devices with a relatively high switching frequency are employed, severe switching oscillation will be induced. To address the problem of complex calculation associated with traditional dead-time compensation methods, this paper proposes an improved dead-time compensation method of inverters based on direct voltage calculation, which significantly simplifies the calculation process of the traditional approaches. [Methods] Firstly, the influence mechanism of dead-time in voltage space vector modulation on the phase voltage and phase current of the motor was analyzed. Then, a dead-time compensation method based on the polarity determination of the phase current at the voltage neutral point was proposed. This method compensated the voltage by calculating the voltage vector conduction time in segments according to the different polarities of the phase current at the voltage midpoint, which reduced the computational complexity of the traditional dead-time compensation methods. Finally, the effectiveness of the proposed method was verified through simulations and experiments. [Results] The simulation results showed that before and after the implementation of the compensation method, the total harmonic distortion (THD) of the phase A output current was reduced from 7.29% to 3.45%. Experimental results demonstrated that with the proposed dead-time compensation strategy applied, the phase current THD was below 4%, whereas the THD exceeded 6% without dead-time compensation. [Conclusion] The strategy proposed in this paper can effectively mitigate the impacts caused by the dead-time effect and improve the waveform quality of the output voltage and output current.
[Objective] The existence of dead-time in the operation of a three-phase inverter results in the generation of high-order harmonics in both the output voltage and output current. Specifically, when switching devices with a relatively high switching frequency are employed, severe switching oscillation will be induced. To address the problem of complex calculation associated with traditional dead-time compensation methods, this paper proposes an improved dead-time compensation method of inverters based on direct voltage calculation, which significantly simplifies the calculation process of the traditional approaches. [Methods] Firstly, the influence mechanism of dead-time in voltage space vector modulation on the phase voltage and phase current of the motor was analyzed. Then, a dead-time compensation method based on the polarity determination of the phase current at the voltage neutral point was proposed. This method compensated the voltage by calculating the voltage vector conduction time in segments according to the different polarities of the phase current at the voltage midpoint, which reduced the computational complexity of the traditional dead-time compensation methods. Finally, the effectiveness of the proposed method was verified through simulations and experiments. [Results] The simulation results showed that before and after the implementation of the compensation method, the total harmonic distortion (THD) of the phase A output current was reduced from 7.29% to 3.45%. Experimental results demonstrated that with the proposed dead-time compensation strategy applied, the phase current THD was below 4%, whereas the THD exceeded 6% without dead-time compensation. [Conclusion] The strategy proposed in this paper can effectively mitigate the impacts caused by the dead-time effect and improve the waveform quality of the output voltage and output current.
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The impact of largescale access of wind farms on the transient stability of power grids could not be ignored. Taking the extended twomachine system with doublyfed wind turbines as an example, the equivalent model of doublyfed induction generator was established, and the twomachine system could be equivalent to a singlemachine infinity system. Based on the law of equal area, the analytic formula of critical clearing angle of the system was deduced in detail after wind power accessed. The analytic formula was used to quantitatively analyze the variation trends of the critical clearing angle with wind power ratio, wind turbine grid connection position, fault location and load access position. The influence laws of the above four factors on the stability of transient power angle were summarized. The simulation models of the extended twomachine system with doublyfed induction generator was established in BPA and FASTEST, and the accuracy of the theoretical analysis was verified.
The impact of largescale access of wind farms on the transient stability of power grids could not be ignored. Taking the extended twomachine system with doublyfed wind turbines as an example, the equivalent model of doublyfed induction generator was established, and the twomachine system could be equivalent to a singlemachine infinity system. Based on the law of equal area, the analytic formula of critical clearing angle of the system was deduced in detail after wind power accessed. The analytic formula was used to quantitatively analyze the variation trends of the critical clearing angle with wind power ratio, wind turbine grid connection position, fault location and load access position. The influence laws of the above four factors on the stability of transient power angle were summarized. The simulation models of the extended twomachine system with doublyfed induction generator was established in BPA and FASTEST, and the accuracy of the theoretical analysis was verified.
Abstract:
Multimotor synchronous and coordinate system was widely used in the field of motor control. The control strategy played a important role in the performance of multimotor synchronization system. Domestic and foreign scholars had conducted deep research, who aimed at the problem of multimotor synchronization.They put forward a variety of synchronization control strategies. The control strategies proposed at home and abroad were reviewed. The accuracy of tracking, robustness and capacity of antiload of the control object were analyzed. The new prospect of multimotor synchronization control was proposed.
Multimotor synchronous and coordinate system was widely used in the field of motor control. The control strategy played a important role in the performance of multimotor synchronization system. Domestic and foreign scholars had conducted deep research, who aimed at the problem of multimotor synchronization.They put forward a variety of synchronization control strategies. The control strategies proposed at home and abroad were reviewed. The accuracy of tracking, robustness and capacity of antiload of the control object were analyzed. The new prospect of multimotor synchronization control was proposed.
Abstract:
Inwheel motor drive technology represents an essential development direction in new energy vehicle drive system. The technical requirements and drive form were introduced. The technical requirements and drive form of inwheel motor drive were summarized. Current research situation of inwheel motor drive technology was compared and analyzed briefly. The key technique problems of inwheel motor technology were proposed. The essential technologies in descreasing unsprung mass, restraining vertical vibration effect and reducing torque ripple of inwheel motor were discussed, which were supposed to be solved urgently. The development trend of inwheel motor drive technology was predicted.
Inwheel motor drive technology represents an essential development direction in new energy vehicle drive system. The technical requirements and drive form were introduced. The technical requirements and drive form of inwheel motor drive were summarized. Current research situation of inwheel motor drive technology was compared and analyzed briefly. The key technique problems of inwheel motor technology were proposed. The essential technologies in descreasing unsprung mass, restraining vertical vibration effect and reducing torque ripple of inwheel motor were discussed, which were supposed to be solved urgently. The development trend of inwheel motor drive technology was predicted.
2024,51(9):70-79, DOI: 10.12177/emca.2024.090
Abstract:
To address the issue of high torque ripple in permanent magnet assisted synchronous reluctance motor (PMA-SynRM), a multi-objective optimization design method based on the non-dominated sorting genetic algorithm II (NSGA-II) was proposed. First, the basic structure and working principle of the PMA-SynRM were introduced. Next, the rotor structure of the PMA-SynRM was improved by constructing air barriers and designing asymmetric auxiliary slots. Then, sensitivity analysis was conducted to identify the parameters that had the most significant impact on the optimization objectives of the PMA-SynRM, and multi-objective optimization was performed using NSGA-II. The optimal topology was selected from the generated Pareto front. Finally, the torque performance of the optimized motor was compared with that of the initial motor using finite element analysis software. Simulation results showed that the performance of the PMA-SynRM optimized through NSGA-II was significantly improved.
To address the issue of high torque ripple in permanent magnet assisted synchronous reluctance motor (PMA-SynRM), a multi-objective optimization design method based on the non-dominated sorting genetic algorithm II (NSGA-II) was proposed. First, the basic structure and working principle of the PMA-SynRM were introduced. Next, the rotor structure of the PMA-SynRM was improved by constructing air barriers and designing asymmetric auxiliary slots. Then, sensitivity analysis was conducted to identify the parameters that had the most significant impact on the optimization objectives of the PMA-SynRM, and multi-objective optimization was performed using NSGA-II. The optimal topology was selected from the generated Pareto front. Finally, the torque performance of the optimized motor was compared with that of the initial motor using finite element analysis software. Simulation results showed that the performance of the PMA-SynRM optimized through NSGA-II was significantly improved.
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Electric Machines & Control Application ® 2026
Supported by:Beijing E-Tiller Technology Development Co., Ltd.
沪ICP备16038578号-3
Electric Machines & Control Application ® 2026
Supported by:Beijing E-Tiller Technology Development Co., Ltd.
