New low-noise sensorless control strategy for permanent magnet synchronous motor drives based on variable-frequency voltage signal injection

This paper proposes a new low-noise sensorless control strategy for the permanent magnet synchronous motor (PMSM) drives to tackle audible noise caused by high-frequency injection method. The traditional noise reduction methods face limitation in improving estimated accuracy of rotor position due to the signal delay with fixed frequency signal. To overcome this issue, a low-noise sensorless control strategy is developed, which consists of two parts. First, with the injection of the proposed variable-frequency voltage signal, significant noise reduction can be achieved due to its characteristics of multi-frequency switching and multi-modal amplitude tuning. Secondly, a delayed effects-aware demodulated signal is designed to reduce the impact of system delay, which can further improve the estimation accuracy of rotor position. As a result, the proposed low-noise sensorless control scheme can suppress audible noise and further improve position estimation accuracy. Also, the steady-state and dynamic performances of the motor drive system can be enhanced. Finally, comparative experiments under steady-state and dynamic conditions demonstrate the superiority of the proposed method in PMSM.