Variable Switching Frequency Strategy for Enhanced Settling Performance of Position Control within Inverter Loss Limit

This paper proposes variable switching frequency strategy for improving settling performance of position control. The proposed algorithm increases the switching frequency by using the amount of conduction loss reduction in the settling region. By increasing sampling frequency due to enhanced switching frequency, control performance limited by distortion from digital implementation is improved. The influence of increased sampling frequency is analyzed through the closed loop system pole analysis in z domain. The settling performance enhancement is verified through two experiments with 1kW SPMSM. In the experiment using the same PID gain set, overshoot was suppressed, and in the small step reference test (0.2rad) with same overshoot limit, 17% settling time reduction was achieved.