Search

The fault-tolerant control method of dual three-phase permanent-magnet synchronous motor (PMSM) drives has gained more and more attention in some applications, such as aircraft system and offshore wind energy system. In this letter, the reason for the torque ripple caused by the standard control method has been investigated in view of the frequency domain after the occurrence of a single open-phase fault. Based on the theoretical analysis, a universal control scheme has been proposed for the dual three-phase PMSM drives with two isolated neutral points, which can be implemented under either healthy condition or fault condition. The key is to modify with a closed-loop controller on harmonic subspace with the notch filter. The proposed method not only realizes the seamless transition between two operation conditions without fault diagnosis but also avoids the reconfiguration of the control structure. Moreover, the system optimization of the minimum copper loss under postfault condition has been integrated into the proposed method. The experimental results are presented to illustrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

A standard three-phase motor drive means a typical two-level voltage source inverter fed three-phase motor drive without any auxiliary circuits. Without fault-tolerant control, common open-circuit faults will cause the breakdown of the standard three-phase motor drives. Although the torque pulsation is theoretically inevitable under the open-circuit faults of standard three-phase motor drives, it's still meaningful to improve the fault-tolerant capability of standard three-phase drives to prolong the reliable operation. In this article, a current optimization based fault-tolerant control is proposed to minimize the proportion of torque loss for standard three-phase permanent-magnet synchronous motor (PMSM) drives under open-phase fault and open-switch fault conditions. Firstly, a two-mode current control is designed to minimize the proportion of torque loss without changing the mathematical model of the faulty motor. Secondly, a three-mode current control is proposed and combined with adjustment of pulse width to tolerate the open-switch faults. Instead of removing the faulty inverter leg directly, the remaining healthy switch in the faulty inverter leg is still utilized. In this way, the damage from torque pulsation can be relieved in the aspect of both frequency and intensity. Finally, the validity of the proposed fault-tolerant control is verified by experiments. [ABSTRACT FROM AUTHOR]

In this article, a coupled fault-tolerant control (C-FTC) is proposed for primary permanent-magnet linear motor traction system in subway applications. By coupling the faulty mover with a healthy mover, the proposed C-FTC can achieve continuous operation of the faulty mover, in which one or more current sensors fail. A healthy mover is determined as the reference mover. The switch-states of the reference mover are also applied to its mathematical model. As a result, synchronous currents of the reference mover are also estimated from its mathematical model, and they are treated as the reference currents of the mathematical model of the faulty mover. Hence, the switch-states of the faulty mover can be determined. Therefore, the faulty mover can be controlled without any current sensors. The key of C-FTC is to compensate the parameter variations and the nonlinear effects of the faulty mover drive system with those of a healthy mover drive system, which is the main contribution of this article. Comparing with the conventional current-sensorless control, C-FTC has stronger robustness to the parameter variations and the nonlinear effects. The effectiveness and robustness of the proposed C-FTC are verified by simulation and experimental results. [ABSTRACT FROM AUTHOR]

Aiming at tolerating common electric faults of multiphase motor drives comprehensively and minimizing the adverse impacts from the remedial scheme itself, a diagnosis-free self-healing scheme is put forward for the open-circuit faults of dual three-phase permanent-magnet synchronous motor (PMSM) drives. First, the self-healing mechanisms of dual three-phase PMSM drives are analyzed in detail. On the basis of theoretical analysis, the repressed self-healing capability of the dual three-phase PMSM drives is fully released by optimizing the current references on harmonic subspace. Since the diagnosis process is not required in the proposed self-healing scheme, the misdiagnosis problem and the prolonged damage caused by the additional time cost of diagnosis can be fundamentally avoided. The proposed self-healing scheme can be generally applied to open-switch faults, single open-phase faults, and multiple open-phase faults in the multiphase motor drives. No change is required for the machine model, modulation strategy, or control framework under different open-circuit faults. Thus, the complex transition strategies among different fault-tolerant control methods for different faults can be avoided, and the adverse impacts from the remedial scheme itself can be minimized. Experimental verification is presented to prove the validity of the proposed self-healing scheme. [ABSTRACT FROM AUTHOR]

In this paper, fault diagnosis and fault-tolerant control strategies have been studied comprehensively for dual three-phase permanent-magnet synchronous motor (PMSM) drives to improve the reliability. Based on direct torque control (DTC) with space vector modulation, a series of diagnostic and tolerant control methods have been proposed for five types of faults, namely, speed-sensor fault, dc-link voltage-sensor fault, current-sensor fault, open-phase fault, and open-switch fault. First, diagnosis and tolerant schemes are proposed for speed-sensor fault by estimating the rotor angle speed with the rotating speed of stator flux. Second, diagnosis and tolerant schemes are proposed for dc-link voltage-sensor fault by combining the current model based stator flux observer with the voltage model based stator flux observer. Third, a three-step method is designed to diagnose three types of faults related to current signals, namely, current-sensor fault, open-phase fault, and open-switch fault simultaneously. A vector space decomposition based current estimation method is proposed to achieve fault-tolerant control for the current-sensor fault, and the voltage compensation based fault-tolerant control is presented for both open-phase and open-switch faults. The experiments have been taken on a laboratory prototype to verify the effectiveness of the proposed fault diagnosis and fault-tolerant schemes. [ABSTRACT FROM AUTHOR]