Sensorless Control Method for Dual Permanent Magnet Synchronous Motors Driven by Five-Leg Voltage Source Inverter

The five-leg voltage source inverter (FL-VSI) is a fault-tolerant control scheme, which has the advantages of small size and low cost. Sensorless control has the advantages of increasing the reliability of permanent magnet synchronous motor (PMSM), reducing system cost and saving system space. Combining characteristics of the traditional modulation strategy of FL-VSI, a sensorless control method for the dual-PMSM system is proposed. The contributions of the proposed method are as follows. First, based on the traditional modulation strategy of the FL-VSI, the high-frequency (HF) square-wave voltages are injected in the half period of zero vectors action, which realizes the separation of the vector control period and the HF signals' injection period and eliminates the filters for position information demodulation. Besides, a novel duty cycle modification strategy of FL-VSI is adopted to meet the switching constraints of the common leg. The proposed method can independently control two motors and is easy to implement in engineering with no additional external circuit. The experimental results show that the proposed method can accurately estimate the positions of the two motors and has good dynamic and steady-state performance.