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

Abstract

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.

A Comprehensive Survey on Fault Tolerance in Multiphase AC Drives, Part 1: General Overview Considering Multiple Fault Types

“…The tolerance to phase OCs of an induction generator composed of two five-phase stars, with one star excited by an HB PWM inverter and another one feeding an HB diode rectifier, is addressed in [405]. On the other hand, other VSC topologies [101,171,239,274,275,316,343,346,372,408,411,413,465] rely to a great extent on postfault reconfiguration and they will hence be discussed later.…”

“…These reconfiguration strategies are explained in the following. As mentioned in Section 2, in the literature it is commonly assumed that switch SC faults are transformed into phase OC ones [102,119,171,277,373,377,385,448,464,465], which are easier to handle and are discussed in Part 2. Considering for the sake of illustration a single leg of a conventional two-level VSC based on IGBTs as in Figure 15a, this conversion into phase OC can be easily completed by opening a bidirectional switch between the corresponding converter leg and stator terminal as depicted in Figure 15b [102,119,385,464,465,506].…”

“…On the one hand, the switch drivers are commonly able to detect switch SCs [119,168]. On the other hand, regarding tolerance, the main reason for the lack of specific publications about switch SCs is arguably that these faults may be easily converted into phase OCs by simply opening the corresponding current path, and then the tolerance methods for the latter can be directly applied [102,119,130,171,277,373,377,385,448,464,465]. However, in practice this implies reducing the achievable torque compared with healthy conditions [24,312,344], assuming that the VSC rating is not set higher than needed for normal operation.…”

“…Since the machine back-EMF tends to increase with speed, if v dc decreases then the maximum speed and power are reduced as well [141,171]; • If the modulation index increases beyond the linear modulation range, overmodulation occurs. This means that low-order voltage harmonics are introduced, the VSD subspaces become coupled in terms of voltage, and the conventional PWM and control methods are no longer able to work properly [8,9,134,135,[137][138][139]142,143,145,[147][148][149][150][151][152][154][155][156]158,159,167]; • If the VSC ac voltage is reduced, the difference between its magnitude and that of the machine back-EMF may become substantially greater.…”

New independent control of a Bi Machine system powered by a multi-leg inverter applied to four in-wheel motor drive electric vehicle

“…Numerous researches have been done to lower the number of inverters [7]- [10]. Developing new control techniques or revising the inverter's topology are two ways to improve the performance of multimachine drives [11]- [14]. Recently, with the development of power electronic devices and the powerful microprocessors, greater attention is paid to systems comprising several electrical machines powered by a single inverter [15].…”