High-Frequency Injection Method for Position Sensorless Drive of IPMSM With a Single DC-Link Current Sensor

This paper proposes a new high-frequency injection method for saliency-based position sensorless drives of interior permanent magnet synchronous machines, utilizing a single dc-link current sensor. Due to the minimum duration time required for accurate current measurement, there exists an immeasurable region during which current cannot be measured. In addition, the simultaneous reconstruction of three-phase currents is not possible, and unaligned sampling points introduce reconstruction errors that degrade rotor position estimation accuracy. To address these limitations, a new pulse-width modulation (PWM) technique is proposed to enhance rotor position estimation accuracy, and an alternatingdq-axis injection method is adopted to avoid current immeasurable regions. The proposed approach requires no additional compensation based on motor parameters and enables high-frequency injection close to the inverter switching frequency. The effectiveness of the proposed HF injection sensorless drive is validated through experimental results under both acceleration and load conditions, demonstrating that a single current sensor achieves performance similar to that obtained with three-phase current sensors.