Stator flux oriented sensorless DTFC for IPMSMs using pseudo-random HF signal injection

In this article, a stator flux oriented sensorless control method is proposed for interior permanent magnet synchronous motor (IPMSM) drives based on the direct torque and flux control (DTFC) and pseudo-random high-frequency signal injection (PR-HFSI) in the zero-low speed range. The DTFC for IPMSMs is introduced briefly and the conventional high-frequency signal injection (HFSI) method, which requires an additional transformation, is also introduced. Then the stator flux oriented PR-HFSI is proposed comprising injection mode and rotor observation, with the aim of noise reduction and easy implementation. Furthermore, the high-frequency noise in HFSI and the mechanisms of noise suppression in PR-HFSI are analyzed based on current spectrums. Meanwhile, the optimal noise reduction frequency combination of n kinds frequency injections is also analyzed. Finally, the performance of the proposed stator flux oriented PR-HFSI method is confirmed with experiments on a 60 kW IPMSM test bench.