Jingwei Zhu

Detection and Remediation of Switch Faults on a Fault Tolerant Permanent Magnet Motor Drive with Redundancy

Fault-tolerant motor drives are becoming more important in safety critical applications. Using a special motor design and an appropriate inverter topology, brushless permanent magnet AC motor drives can have a fault-tolerant capability. This paper considers a dual motor drive system on a common shaft to introduce redundancy. The paper provides a systematic classification for the potential electrical faults which may occur in a real motor drive. In the paper, the switch and winding short circuit fault detection and identification methods are studied and experimental results are presented. In addition, the effects of switch faults on the phase currents and output torque are discussed, and remedial strategies for these faults are proposed. Furthermore, it was also demonstrated using simulation results that the proposed remedial strategies can compensate for the loss of torque due to the switch faults and can keep the peak-to-peak torque ripple factor comparable to healthy operation of the drive.

Fault Analysis and Remedial Strategies on a Fault-Tolerant Motor Drive with Redundancy

Fault-tolerant motor drives are required in a range of safety-critical applications. Using a special motor design and an appropriate inverter topology, brushless permanent magnet AC motor drives can have an effective fault-tolerant capability. Although a single motor fault-tolerant drive system may be sufficient in many critical applications, a higher degree of fault tolerance requires redundancy in the motor system as considered in this paper. This is achieved by using a dual motor module on a common shaft. The simulation model of the entire drive system and the analysis of the various faults are presented in this paper. The effects of fault(s) on the phase current and output torque are provided. Three remedial operating modes are proposed and their features are compared. In addition, an experimental setup was introduced, which is based on dual electrically and magnetically isolated brushless AC motor modules, h-bridge inverters for individual phases and dsPICDEM MCU motor controller.

Fault remedial strategies in a fault-tolerant brushless permanent magnet AC motor drive with redundancy

In this paper the fault-tolerant brushless permanent magnet AC motor drive with redundancy is investigated. The motor modules are designed to provide both magnetic and electrical isolation between phases and the redundancy is achieved by using two motor modules connected on a common shaft. The effect of potential faults on the output torque and torque ripple factor are examined and the fault analysis shows that the output torque will be reduced and the torque ripple will be increased after fault(s). Three fault remedial strategies are proposed to compensate the torque loss due to the fault(s) and their features are discussed as well. Zero torque ripple with minimum copper loss fault remedial strategy is the most suitable method which can result in minimum torque ripple factor with only a modest increase in copper loss comparing with the minimum possible value. The experimental setup of the motor drive is developed and the experimental test results are provided to verify the analysis results and the validity of the proposed fault remedial strategies.

Performance Investigation of a Fault-Tolerant Brushless Permanent Magnet AC Motor Drive

Fault-tolerant motor drives are required in various safety critical applications. Using special motor design and inverter topology, brushless permanent magnet AC motor drives can have a fault-tolerant capability. In this paper, a dual motor drive configuration has been proposed which offer high robustness and reliability. This paper studies various critical performance characteristics of the dual motor drive including drive loss and system efficiency. The paper aims to address some of important performance issues in the motor drive, which has not been addressed previously. The paper presents the details of the experimental setup and explains the measurement methods for the motor parameters and for the open-circuit torque loss. The efficiency prediction method and corresponding results are also presented and verified by the computer simulation study both under healthy and various faulty conditions

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.

Design and optimization of a six-phase fault-tolerant permanent magnet motor

This paper presents a six-phase fault tolerant permanent magnet (FTPM) motor with high performance and reliability for use in safety critical motor drive systems. Fault tolerance is achieved by design and optimization of motor parameters. The influence of the number of phases on motor operation performance is discussed. The method of optimization of main motor parameters, namely armature core length and armature core diameter, is proposed. The winding configuration and the slot and pole number combination are considered. Finally, the proposed six-phase 12-slot 10-pole FTPM motor is verified by Finite Element Analysis (FEA), and the simulation results shows good output performance with low cogging torque and high power density.

An indirect rotor position estimation technique for a fault-tolerant brushless PM motor drive

This paper proposes an indirect rotor position estimation method for a fault-tolerant brushless PM motor drive that has a dual motor module on a common shaft. The technique is based on flux linkage increments of phase windings and performing multiple rotor position estimations using pairs of phases in the motor drive. The paper provides the theory of the method and presents extensive test results to demonstrate its effectiveness using off line real data obtained under various practical operating conditions including faulty states and parameter variations.

Modeling and simulation of six-phase fault-tolerant permanent magnet motor vector control system

In order to improve the control performance of the six-phase fault tolerant permanent magnet (FTPM) motor drive in healthy and faulty conditions, the vector control technique for this motor drive is studied in this paper. Based on the analysis of the structure and operating principle, the mathematical models in the rotational coordinate system and the simulation model of vector control system using SVPWM technique for this motor drive are established. The simulation results shows that the designed vector control system for six-phase FTPM motor drive can quickly track the required speed and output torque. After one-phase open-circuit fault, through properly increasing the current in healthy windings, the motor drive can still provide the same output torque as in healthy operation and the torque ripple is not increased obviously.