A Novel Intermittent High-Frequency Square-Wave Injection of IPMSM Sensorless Drive for Eliminating Inverter Dead time Nonlinear Effect

High-frequency (HF) square-wave signal injection has been widely applied in the sensorless control system of interior permanent magnet synchronous machine, increasing the bandwidth of speed and position control loop. However, the injected high-frequency square-wave voltage may be distorted by the inverter nonlinearity effects, especially by the nonlinear effects of the dead time. This paper analyzes the effects of inverter nonlinearity on injection voltage, induced current ripple, and position estimation performance. A novel intermittent high- frequency square-wave injection method is proposed to minimize the effect of the dead time, which also improves the efficiency of injection voltage. Experimental results conform the advantages of proposed method. The mechanical position estimation errors are lower than 0.0314rad (1.8°).