Optimized Discrete-Time Current Control for IPMSM Drives

Abstract

Designing the current controller directly in the discrete-time domain is essential to high-speed applications, mainly due to the delay inherent to the digital control system. Active-damping (AD) is usually included to improve the disturbance rejection. However, the continuous-time form of the AD element is normally followed simply in the discrete-time domain design, which causes the dynamic performance and the anti-disturbance performance cannot be taken into account well. To easy the confliction, a novel AD loop, dedicated to the discrete-time plant, is proposed. In this design, the AD element is no longer limited to be a single real gain, as commonly seen in the continuous-time domain representing the active resistance. Alternatively, it is designed with the feedback control theory, allowing both the tracking response and disturbance response to be designed as required respectively. As a result, the dynamic response and disturbance rejection can be determined independently, and the parameter robustness can also be designed intentionally to a great extent. Besides, to reduce computation load in practice, a discrete-time IPMSM’s model with low computation intensity and high accuracy is presented in this paper. Some experimental results are reported to demonstrate the performance of the discrete-time control designed in this paper.