Critical Aspects and Strategies for Sensorless Control of IPMSM based on Low-Frequency Voltage Injection

High-Frequency signal injection is widely adopted for zero and low-speed operating conditions in sensorless control of Interior Permanent Magnet Synchronous Motors (IPMSM) drives. However, the audible noise emissions caused by induced HF current has restricted in some cases its practical application. Low-frequency signal injection solve the noise problem, but it introduces new issues. In particular, the filtering for signal separation is not trivial and affects negatively the current control loop and the dynamic performance of the angle tracking estimator. To overcome these limitations, some new strategies and modifications respect to the traditonal sensorless control are proposed in this paper, using the esteem of specific signal components estimated from known information of the drive. The simulations were carried out considering a discrete-time controller and quantiziers on measured currents and pulsed voltages. The results demonstrated the feasibility of the proposed method.