Quiet Position Sensorless Drive of IPMSM Using Ultrasonic Three-Phase Triangular-Wave Carrier

This paper proposes a method for the removal of acoustic noise in position sensorless control using high-frequency three-phase triangular-wave carriers. In general, high-frequency voltage injection is used for sensorless control of permanent magnet synchronous motors in low-speed range. As control using three-phase triangular-wave carriers automatically generates the voltage of the carrier frequency component and induces the current of the same frequency, it is possible to realize sensorless vector control in the low-speed range without applying high-frequency voltage and to estimate the magnetic pole position from the current. This control method corresponds to not only the low-speed range but also the full-speed range. However, injection of a high-frequency voltage signal causes acoustic noise of the same frequency. To remove acoustic noise, the injecting voltage frequency is increased above the audible range. Moreover, as the current used for estimating the magnetic pole position is a high-frequency current and its values are small, it is considerably affected by the dead time and delay of switching devices. Therefore, by considering these two parameters and measuring the high-frequency current at the ideal point, the position estimation error was reduced. Experiments confirm the validity of the proposed method.