Sensorless Direct Torque and Flux Control of IPMSMs Using Pseudo-Random HF Square-Wave Voltage Injection into a Stator Flux Reference Frame

This paper proposes a high-frequency square-wave voltage injection with random frequency and random phase (HFSVI-RFRP) scheme to solve serious noise problem caused by the traditional fixed frequency high-frequency square-wave voltage injection (HFSVI) scheme for interior permanent magnet synchronous motor (IPMSM). The current power spectra density (PSD) analysis is performed to evaluate the noise suppression performance of the HFSVI-RFRP. Besides, a comparison among HFSVI, HFSVI-RFRP and high-frequency square-wave voltage injection with fixed frequency and random phase (HFSVI-FFRP) is introduced. The results show that the continuous component of HFSVI-RFRP is smoothest among three schemes and discrete component is not existing even the probability p is not strictly equal to 0.5. In addition, for DTC control frame, an extra frame transformation is needed to transform the injected signal from dq-axis to αβ-axis. Therefore, the signal of HFSVI-RFRP is directly injected into stator flux reference frame. Finally, the performances of the proposed HFSVI-RFRP based sensorless control method are verified.