Implementation of Postfault Decoupling Vector Control and Mitigation of Current Ripple for Five-Phase Fault-Tolerant PM Machine Under Single-Phase Open-Circuit Fault

Multiphase machines have been attracting more and more attentions in high-reliability-required applications due to their inherent fault-tolerant capability. Postfault control strategies withstanding opencircuit faults (OCFs) for several multiphase machine types, like five-phase, symmetrical six-phase (S6) and asymmetrical six-phase (A6) machines, have been widely investigated in recent literatures. However, faulttolerant control for symmetrical dual three-phase (D3) machines have rarely been studied so far. To fill the gap, this paper addresses key issues in postfault decoupling modeling and field orient control (FOC) for the dual three-phase surface-mounted permanent magnet synchronous machine (SPMSM) with isolated neutrals under single-phase OCF. To do so, a postfault decoupling model with reduced-order transformation is established for D3 machines. Postfault current references are reconfigured with two mainstream criteria: minimum-loss (ML) and maximum-torque (MT). Furthermore, third harmonic flux linkage/back-EMF are taken into account in modeling and control, since it causes third harmonic currents and hence torque ripples under single-phase OCF. Proportional-resonant controllers are employed to decrease the third harmonic currents and torque pulsations. The validity of the postfault control strategies is proved by experiments. INDEX TERMS Dual three-phase, fault-tolerant control, open-circuit fault, permanent-magnet synchronous machine (PMSM).

Section: Introductionmentioning

confidence: 99%

Postfault Control and Harmonic Current Suppression for a Symmetrical Dual Three-Phase SPMSM Drive Under Single-Phase Open-Circuit Fault

Liang

Kou

et al. 2020

“…However, when the faults occur, the different subspaces are no longer independent. In order to realize the VC operation of five-phase motor under fault condition, some transformation matrices were mainly investigated, such as the reduced-order transformation matrices [17] [18] and the reduced-order orthogonal transformation matrices [19]- [21]. By using these matrices, the motor with VC strategy achieves disturbance-free operation under the fault condition.…”

Section: Introductionmentioning

confidence: 99%

Unified Decoupling Vector Control of Five-Phase Permanent-Magnet Motor With Double-Phase Faults

Cheng

Zhou

Wang³

2020

Multi-phase permanent-magnet (PM) motor is a competitive candidate for application where uninterrupted operation is demanded under fault condition. However, double-phase open-circuit or short-circuit faults result in serious problems, such as high fluctuating-torque, deteriorated dynamic performance, even breakdown. This paper proposes a novel unified decoupling vector control strategy to restrain torque fluctuations and improve dynamic performance for a five-phase PM motor with arbitrary double-phase failures. The novelty of the proposed strategy is the development of reduced-order orthogonal transformation matrices and remedies voltages, and then the smooth operation with vector control strategy can be achieved under double-phase open-circuit or short-circuit fault condition. The decoupled motor model in the synchronous rotating frame is achieved by the combination of the reduced-order orthogonal transformation matrices deduced from the optimal fault-tolerant currents and the remedy voltages. The torque fluctuations cancellation is achieved by the remedy voltages. This control strategy exhibits the improved dynamic performance with smooth torque of the faulty PM motor. The experimental results are presented to verify the feasibility of the proposed strategy. INDEX TERMS Five-phase permanent-magnet motor, fault-tolerant control, reduced-order orthogonal transformation matrix, remedy voltage, double-phase faults, vector control.

“…Various opencircuit and short-circuit faults in the machine drive system can be converted into the open-phase fault through the fault isolation. Therefore, the research of fault-tolerant control strategies for multiphase machines are mainly focused on the open-phase fault [6]- [20]. When an open-phase fault occurs, to suppress the torque ripple, the postfault phase current references need to be modified to maintain the same rotating magnetomotive force as in prefault situation [6].…”

Section: Introductionmentioning

confidence: 99%

“…The full-range minimum losses (FRML) strategy which minimizes the losses in the whole torque operation range is proposed in [11]- [13]. To realize the field-oriented control operation in the open-phase fault situation, the vector space decomposition (VSD) can be implemented by using the normal decoupling transformation matrices [14]- [17] or the reduced-order transformation matrices [18]- [20]. The inner current control loops can been realized using dual PI [15] and model predictive controllers [9].…”

Section: Introductionmentioning

confidence: 99%

Control Strategy for a Five-Leg Inverter Supplying Dual Three-Phase PMSM

Jing

Zhou

2020

This study presents a novel control strategy for a five-leg inverter-fed dual three-phase permanent-magnet synchronous motor (DT-PMSM)system. Three different five-leg inverter topologies (operating modes) can be reconfigured by choosing a pair of phases for sharing the common leg. The fiveleg inverter operation mode with 150° phase difference can achieve full torque output, but the utilization of DC bus voltage is low. The operation mode with 30° phase difference has higher DC bus voltage utilization but lower output torque. The modified double zero-sequence injection (DZI) PWM strategy based on carrier-based PWM (CBPWM) for five-leg inverter operating modes is proposed. This strategy can achieve the maximum DC bus voltage utilization. The five-leg inverter operating modes can be used as a faulttolerant solution for the occurrence of a fault in one leg of the six-leg inverter. Compared with the commonly used open phases fault-tolerant control (FTC) strategies, this strategy has the advantages of without increasing the stator copper, reducing the torque ripples, and implementing easily. Experimental results verify the effectiveness and feasibility of the proposed strategy. INDEX TERMS Five-leg inverter, dual three-phase permanent magnetic synchronous motor, double zerosequence injection pulse width modulation strategy, DC bus voltage utilization.