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When dealing with safety‐critical applications that involve multiphase permanent magnet synchronous motors (PMSMs), the current source inverter (CSI) is a superior choice compared with the voltage source inverter. The conventional technique of pulse width modulation (PWM) presents a challenge for CSI, particularly during faults. The fault‐tolerant control of multiphase PMSMs fed by CSIs has not been well investigated, particularly in situations involving double‐phase open‐circuit faults. Furthermore, fault‐tolerant control becomes more complex when the multiphase PMSM includes harmonic back electromotive forces (EMFs). To deal with these issues, an ampere‐second (AS) vector PWM technique is developed for a five‐phase PMSM powered by CSI11. The modulation ratio of the proposed PWM is identical to that of space vector PWM. The proposed method, however, is easier to implement. A fault‐tolerant control method using AS‐vector is proposed for single‐phase, adjacent double‐phase, and non‐adjacent double‐phase open‐circuit faults. Additionally, a method is developed to suppress the torque ripple that results from harmonic back‐EMFs during fault conditions. Compared without the torque ripple suppression method, during the speed rising, the proposed method can reduce torque ripple to 16.7%, 54.5%, and 37.5%, respectively. The experiments have confirmed the effectiveness of the proposed PWM technique and fault‐tolerant control method. [ABSTRACT FROM AUTHOR]

In interior permanent magnet synchronous motor (IPMSM) position‐sensorless drives, the high‐frequency (HF) square‐wave voltage injection method is often used to estimate the rotor position and speed in low‐speed range by tracking the salient polarity of the motor. In order to reduce the torque ripple caused by HF signal injection, a strategy to update the magnitude of the injected signal online by back propagation neural network is proposed in this paper. With the proposed method, the neural network can update the magnitude of the injected signal online according to the d‐axis current and the position error information. It can not only ensure the accuracy of position extraction but also effectively reduce the current harmonics caused by the injected signal, and then the torque ripple can be reduced. In addition, the proposed method is easy to implement, resulting in low computation burden. Finally, the experiments are implemented on a 1‐kW IPMSM drive. The experimental results show that compared with the conventional fixed magnitude injection, the peak‐to‐peak value of the torque ripple is reduced by nearly half along with the decrease of the injected magnitude. [ABSTRACT FROM AUTHOR]

Among the existing harmonic current suppression methods, it is difficult and complicated to suppress any nth harmonic current accurately for multi-phase permanent magnet synchronous motors (PMSMs). To solve this problem, this paper takes a five-phase dual-rotor PMSM fed with a current source inverter (CSI) as an example, and proposes an nth harmonic current suppression method based on the impulse current PWM algorithm. Firstly, the analysis is conducted and presented for the nth harmonic current in the mth harmonic space. Then, based on the Sliding Discrete Fourier Transformation (SDFT), a low-pass filter (LPF) named SDFT-LPF is designed. Additionally, the impulse current PWM technique for the five-phase CSI is realized. In this paper, the experiments have confirmed that the SDFT-LPF has good filter performance. Compared with the SVPWM, the impulse current PWM technique has the same DC-link current utilization rate, but it is easier to implement. Moreover, the proposed harmonic current control method can accurately control any nth harmonic current without changing the PWM technique, which has significantly reduced the complexity of the harmonic current control. Additionally, the proposed scheme is easy to implement and can be directly extended to the multiple harmonic current's control. [ABSTRACT FROM AUTHOR]