Nonlinear position controller design for SynRM drive systems with reduced switching frequency

This paper proposes a novel PWM switching method and control algorithm for synchronous reluctance drive systems. In this paper, first, in different switching modes, the current slope of the stator current can be systematically derived. The current slope is related to the DC-bus voltage, operating conditions, and parameters of the motor. Then, by computing the derivation of the current slope command and the real current slope, an optimum switching state can be determined and used to trigger the inverter. After that, the nonlinear controller for a position control system is proposed. By using the proposed method, the synchronous reluctance drive system performs very well. It has smaller current harmonics, lower switching frequency, and less switching loss when compared to the hysteretic current control. In addition, a fast transient response, good load disturbance rejection ability, and good tracking performance of position control can be achieved. No extra hardware is required. Several experimental results validate the theoretical analysis.