A Model based Voltage Phase Controller in Six-step Mode for IPMSM with an Extending Operation Region

As a key method to realize a high-performance control of IPMSM in six-step mode, which is of benefit to reduce the switching frequency and increase the output voltage, the conventional voltage phase controller can adjust the output torque by amending the voltage phase through an integrator. However, the assumption that the relationship between the torque and voltage phase is monotonically increasing, is not always correct. In fact, motor parameters may change the relationship, which results in the failure of driving the motor for the conventional voltage phase controller. In this paper, we analyze the effect of motor parameters on the monotonicity. Then, point out that the assumption in the conventional way is a critical limit for the voltage phase control of some motors. It limits the operation region seriously. After achieving the condition that can judge which case the relationship between the torque and voltage phase is in, a model based voltage phase controller in six-step mode for IPMSM is proposed. The operation region, which is not suitable for some conventional ways, can be approached well for the proposed method. Finally, some simulation results are also given to prove the correctness and feasibility of the proposed method.