Seven-Phase PMSM Drives Operation Post Two Types of Faults

Abstract

This research presents a seven-phase PMSM drive with a high degree of reliability. This enhancement in reliability is achieved by applying two new Fault Tolerant Control techniques (FTC) at the same time. The first FTC will maintain the operation of the seven-phase PMSM drive after the failure in one based on the minimum inverter current optimization technique. The implementation of this FTC technique is achieved through developing a novel Space Vector Pulse Width Modulation (SVPWM) to assure proper distribution of the currents in the remaining phases post failure. The second FTC technique keeps the operation of the faulty seven-phase PMSM drive post the failure in the speed sensor. This is created by developing a new algorithm to obtain the rotor position and speed of the faulty seven-phase PMSM drive based on the voltage excitation method. Simulation results are presented to demonstrate the enhancement in the reliability achieved by the FTCs developed in this paper for the seven-phase motor drive running post the failures in phase ‘A’ and the speed sensor at the same time.

Control of 7-phase permanent magnet synchronous motor drive post three failures

“…Under healthy operating conditions, the SVPWM technique presented in [36] was utilized. In case of failure of phase 'a', the SVPWM presented in [41] was utilized. If the failure occurred in phases 'a' and 'c', the new SVPWM proposed in the previous In addition, the encoder was used to obtain the speed and position of the motor to achieve vector control.…”

“…When the 7-phase motor is operating without faults, the stator currents will be equal in magnitudes and phase shifted by 51.42. This distribution of stator currents is illustrated in Figure 2 and (3) [39]- [41].…”

“…If phases 'a' and 'c' were exposed to a fault, the remaining healthy current has to be redistributed as given in (5) as shown in Figure 4. This distribution will keep the MMF while achieving the minimum the inverter current optimization [39]- [41]. Figures 4(a (5)…”

“…In addition, the FTC can also perform other optimizations, such as equal currents, minimum losses, and maximum torque [39]- [42]. If a fault occurs in phase 'a', the remaining healthy currents have to be redistributed as given in (4) and Figure 3 to keep the MMF while minimizing the inverter current [39]- [41]. Figures 3(a) and 3(b) illustrate the phasor and the sinusoidal distribution of the stator currents respectively after the failure in phase 'a'.…”

“…After that when 𝑡 = 2 𝑠, a fault occurred in phase 'a', and the space vector pulse width modulation (SVPWM) proposed in [41] was utilized simultaneously. The measured speed of the motor obtained using the encoder proves that the 7-phase motor speed was not changed but the ripple in speed was slightly increased.…”