Influence of d-Axis Current on Torque and Transformer Secondary-Side Power in Power Superposition System for Position Sensor of Surface-Mounted PMSM

This paper investigates a method of supplying power to a position sensor using a transformer connected to the power lines of a permanent magnet synchronous motor and compares the transformer secondary-side power and torque characteristics for ac injection as a square wave versus as a sine wave. Simulations and experiments evaluate the power and torque. When a square wave is injected rather than a sine wave, power exceeding the required power is obtained in all operating regions. However, the torque ripple increases regardless of the type of ac power injection.