Hybrid Pulse Width Modulation with Current Derivative Measurement for PMSM Sensorless Control

This paper proposes a position sensorless control method of permanent magnet synchronous motor (PMSM) using the current derivative measurement with the hybrid pulse width modulation (PWM). Ensuring a sufficient duration of the voltage vector for the current derivative measurement is a main issue in fundamental PWM excitation-based (FPE) sensorless control method. The proposed method overcomes this issue by extracting the position error from the phase voltage and current in only one voltage vector. Then, the hybrid PWM method is introduced to enhance the accuracy of the position estimation regardless of the modulation index (MI). In addition, the current derivative is accurately measured using the multi-point current sampling (MPCS) and the least square curve fitting (LSCF). To improve the performance of the sensorless control, the time delay compensation and average current calculation methods are presented. As a result, the proposed method enables a full-region sensorless control of PMSM without any voltage injection or phase shifting, which deteriorates the field-oriented control (FOC). The effectiveness of the proposed method is verified by a 1kW PMSM drive system in various driving conditions.