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

The five-leg voltage source inverter (FL-VSI) has been widely studied as a better fault-tolerant scheme. In this article, combined with the duty cycle correction method, a low-speed sensorless control method for dual permanent magnet synchronous motors driven by FL-VSI with single current sensor is proposed. A high-frequency (HF) voltage injection method is used to solve the dead zone of current reconstruction as well as achieve position estimation of two motors by only one HF signal. The HF voltages are injected into the stationary beta-axis of two motors to extend the voltage vector to the measurable region of specific sectors, which solves the dead zone of the current reconstruction without changing the symmetry of pulsewidth modulation wave. Then, the reconstruction method and HF voltage injection period are changed to reduce the reconstruction error caused by HF voltage injection and different sampling points, and extract rotor position information more accurately. Finally, several experimental results are provided to verify the feasibility and effectiveness of the proposed method.