An ampere-second-vector pulse width modulation technique and fault-tolerant control for CSI11 fed five-phase permanent magnet synchronous motor with multiple harmonic electromotive forces

Abstract

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.