Minimum torque ripple current control strategy in a dual fault tolerant PM AC motor drive

In this paper a dual fault tolerant motor drive utilizing brushless permanent magnet AC motors is investigated for safety critical applications. The motor modules are designed to provide both magnetic and electrical isolation between the phases, and the use of two modules also offers redundancy. This paper addresses an important issue, torque ripple and torque compensation due to the loss of a phase or phases in a practical dual motor drive. The mathematical models for reference current calculation in both healthy and various faulty operation modes are established under the zero torque ripple factor and minimum copper loss constraint conditions. These models are suitable for both sinusoidal and trapezoidal fault tolerant motor drives. The experimental results under various fault conditions are provided to verify the proposed fault remedial strategy.