A maximum torque per ampere (MTPA) control based on virtual signal injection for interior permanent magnet synchronous motor (IPMSM) with fast dynamic response is proposed in this paper. A small square wave signal is mathematically injected into current angle for accurately tracking MTPA points. The extracted derivative of elctromagnetic torque is utilized to compensate the initially set current angle to the real MTPA operation current angle. Due to the absence of bandpass and lowpass filters which are essential in the sinusoidal injected signal scheme, this method shows good dynamic response. By incorporating a modified equation for the torque after signal injection, the steady-state accuracy is also enhanced. The d- and q-axes current references are obtained through the current vector magnitude and optimal current angle instead of using the torque equation with nominal motor parameters, which guarantees the accuracy of the output torque. The proposed scheme is parameter independent and no real signal is injected to the current or voltage command. Thus, the problems of high-frequency signal injection method are avoided. A prototype is set up and experiments are carried out to verify effectiveness and robustness of the proposed control scheme.

This paper proposes a simple and practical duty cycle modulated direct torque control (DDTC) for permanent magnet synchronous motors. The duty cycle of active vector is obtained using a duty cycle generator according to the torque error and motor speed, which can avoid the complex calculation process associated with conventional DDTC. The design details about the duty cycle generator are illustrated, and the stability of the proposed DDTC is analyzed, which ensures the reliable operation of the motor system. Experimental results are presented to validate the effectiveness of the proposed DDTC. Furthermore, the comparative evaluation of the proposed DDTC and conventional DDTC is conducted to verify the superiority of the proposed DDTC.

A flux-weakening control algorithm with an improved stator flux linkage command's adjustment part of interior permanent magnet synchronous motors is proposed in this paper. The current commands are derived from lookup tables, which consider variation of motor parameters. The merits of this algorithm are the maximization of torque and high torque stability. Experimental results are demonstrated to verify the effectiveness of the proposed algorithm.

Fault-tolerant capability is one of the dominant advantage of multiphase drives. In case of open-phase fault occurrence, the control strategy needs to be modified in order to maintain smooth operation, resulting in larger amplitude of the phase current. Consequently, the winding losses are increased in comparison with healthy operation. Also, the torque operation range (TOR) is reduced inevitably. This article proposed a unified fault-tolerant strategy that can ensure the widest TOR while minimizing losses. Compared with state-of-the-art literature, the execution of the fault-tolerant algorithm does not require any online or offline global optimization process. Instead, simple closed-form expressions are adopted, which could be considered a feasible simplification. Furthermore, the proposed strategy can be adopted for symmetrical or asymmetrical multiphase machines with any number of phases. Experimental results validate the effectiveness of the proposed fault-tolerant method.

Reliable inter-turn short-circuit (ITSC) fault detection is essential for permanent magnet synchronous generators (PMSGs). The harmonics in machine currents and voltages are affected by the bandwidths of dual-loop controllers, which may lead to the failure of ITSC fault detection based on the current or voltage signature analysis. In this article, a robust method for ITSC fault detection is proposed to deal with this problem. First, the mathematical model of PMSG with ITSC fault is established. Then, the behaviors of the second-order harmonics in dq -axis currents, dq -axis voltages, and dc-link voltage with respect to the bandwidths of current and voltage controllers are investigated. After that, a reliable detection method based on two fault detection indicators and adaptive to the bandwidth changes of dual-loop controllers is proposed. The first indicator is simple and easy when only the bandwidth of the current controller changes, and the other one weights and sums the second harmonics in q -axis current, q -axis voltage, and dc-link voltage to ensure the robustness and improve the accuracy of ITSC detection when both the bandwidths of current and voltage controllers change. Finally, the effectiveness of the proposed method is validated by experiments.