Low-Speed Sensorless Control With Single-Current Sensor Based on Current Reconstruction of Multiple-Branch Sampling

This article proposes a sensorless control method based on high-frequency (HF) voltage signal injection for permanent magnet synchronous motors (PMSMs) using multiple-branch sampling with a single current sensor. The conventional direct current (dc) bus sampling methods suffer from reconstruction dead zones and require phase shift operations, which generate current harmonics and further deteriorate position estimation performance. The proposed method based on multiple-branch sampling eliminates the effect of reconstruction dead zones. Sampling at the midpoint of zero vector periods is to avoid sector division, thus reducing algorithm complexity. A cascaded second-order generalized integrator (SOGI) is introduced to compensate for dc bias errors caused by the current sensor, further improving the estimation accuracy. The experimental results verify the effectiveness of the proposed method. The position estimation errors at 60, 120, and 180 r/min are reduced by 12.2%, 22.6%, and 21.2% compared to traditional dc bus sampling methods.