Rotating High Frequency Signal Injection Based on Interior Permanent Magnet Synchronous Motor Rotor Position Estimation with the Demodulation Implemented on the Synchronous Reference Frame

Rotating high-frequency (HF) injection technique is a typical scheme for position estimation of interior permanent magnet synchronous motor (IPMSM) in standstill and low speeds. It has good stability, but its estimation accuracy is affected by the digital control delay and the demodulation filtering delay, resulting in a limited accuracy of the estimated position. To compensate the estimation error, a synchronous reference frame (SRF) based demodulation scheme is proposed in this paper. Both the extraction of the HF carrier currents and the demodulation of the rotor position are implemented in the estimated SRF. By the phase relationship of the positive- and negative-sequence HF currents, the delay error is compensated inherently, and the estimation accuracy is enhanced. In the proposed estimation scheme, the HF rotating voltage is still injected in the stationary reference frame, but the extraction and demodulation processes are based on the estimated SRF. In this SRF, the positive- and the negative-sequence components has the same frequency, therefore, the delaying effects cause the same phase delay to both sequence components, which is the basis to compensate the phase delay of the negative-sequence current with the positive-sequence current. With the compensation, the position accuracy is consequently improved. Effectiveness of this scheme is verified through the experimental results on an 18kW IPMSM test rig. © 2020, Electrical Technology Press Co. Ltd. All right reserved.