Model-Free Predictive Voltage Control of the Floating Capacitor in Hybrid-Inverter Open- Winding Permanent Magnet Synchronous Motor
Chong Zhang, Chun Gan, Kai Ni, Shuanghong Wang, Jianbo Sun, Zhiyue Yu, Ronghai Qu
Abstract
In a hybrid-inverter open-winding permanent magnet synchronous motor (OW-PMSM) drive, the motor and the floating capacitor are controlled simultaneously. Besides, since the compensatory inverter barely provides active power under steady-state operation, the unity power factor control (UPFC) of the main inverter (MI) is also required. However, the conventional model-based predictive control of the hybrid-inverter OW-PMSM is highly sensitive to the accuracy of parameters, including the floating capacitance and stator inductance. Serious current distortions and system oscillations appear when the model parameters are mismatched with the actual ones. In addition, unmodeled parts such as power switch voltage drops and disturbances also degrade the system performance. Hence, a linear disturbance observer (LDO) based model-free predictive control (MFPC) is put forward. By using ultralocal models to substitute the mathematical models of the floating capacitor and OW-PMSM, the proposed scheme maintains satisfactory performance when system parameters are mismatched. Moreover, because system disturbances are obtained by LDO, the tracking errors can be eliminated even when parameters of ultralocal model are less appropriate. Thus, high precision of UPFC for the MI is guaranteed. Finally, experiments are carried out on a 500 W hybrid-inverter OW-PMSM drive, proving the superiority and effectiveness of the proposed MFPC strategy.