Torque Ripple and Acoustic Noise Suppression for Sensorless PMSM Drive Based on Biaxial Random Signal Injection

The signal injection method shows good performance in estimating the rotor position of permanent magnet synchronous motor (PMSM) at low speed, while the traditional uniaxial fixed-phase signal injection (UFPSI) method will produce extra torque ripple and noise. This article proposes a novel sensorless PMSM drive method based on biaxial random phase signal injection (BRPSI), which can simultaneously suppress both torque ripple and noise. To achieve this, an additional injected q-axis voltage, with its amplitude calculated in real time to satisfy different operating conditions, is used to counteract the torque ripple induced by the injected d-axis voltage. Meanwhile, the phase of the injected voltages is randomly switched to achieve a smooth current power spectral density (PSD) and attenuated noise level. The effectiveness of the proposed method is verified on a rapid control prototyping (RCP) platform, which demonstrates that the proposed method exhibits good speed and position tracking performance while simultaneously suppressing the torque ripples and noise caused by the injected signals.