Optimized Discrete-Time Current Control for IPMSM Drives

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 antidisturbance performance cannot to be taken into account well. To ease 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 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. In addition, to reduce computation load in practice, a discrete-time interior permanent magnet synchronous motor (IPMSM)’s model with low computation intensity and high accuracy is presented in this article. Some experimental results are reported to demonstrate the performance of the discrete-time control designed in this article.