Switching Frequency Voltage Injection for Sensorless IPMSM Control Using Current Derivative Measurements

Position sensorless control using switching frequency voltage injection often suffers from increased position estimation error due to the voltage injection error caused by pulse width modulation (PWM). To mitigate the position estimation error, current derivatives are measured within a single active voltage vector for position estimation. This method requires an active vector with minimum time for precise current derivative measurement. This article presents a voltage injection scheme that ensures the measurement voltage vector without modifying PWM. By calculating the magnitude of the d-axis pulsating voltage based on the relationship between the fundamental voltage vector and the d-axis of the rotor, the measurement voltage vector is accurately secured regardless of the operating region. The effectiveness of the proposed method is verified through experimental results under various operating conditions.