High Frequency Voltage Injection Method for Sensorless Control Using Single DC-Link Current Sensor in IPMSM Drives

Saliency-based sensorless control based on current derivative measurements offers improved position estimation accuracy in single current sensor systems, but it typically requires a modified pulsewidth modulation (PWM) to secure a minimum time of active vector (T<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">min</inf>). This article proposes a high-frequency voltage injection (HFI) method without modifying the PWM scheme, where both magnitude and direction of the injected voltage are determined to ensure the T<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">min</inf>. First, the proposed method ensures the T<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">min</inf> of six active vectors, thereby eliminating parameter dependency in position estimation. In addition, a zero vector distribution strategy is introduced to reduce the current ripple induced by the additional HFI. Experimental results verify that the proposed method achieves a position estimation error below 0.05 rad and reduces current ripple by 35% without any PWM modification.