Three-phase current reconstruction method for permanent magnet synchronous motor based on current transformer sensors

The position sensorless permanent magnet synchronous motor (PMSM), with its simple structure, is applied in the aerospace field with high reliability requirements. To drive PMSM safely, the three-phase current measured from the driver needs to be isolated for the closed-loop control. And then, the accuracy current measurement is crucial for achieving optimal motor performance. In the paper, current transformer (CT) with centre taps is employed to isolate and measure the high-frequency current of the inverter switch. Additionally, an algorithm is proposed to reconstruct the switch current into the low-frequency phase current. Subsequently, the measuring method and the algorithm are applied to an inverter platform, which drives a 100W PMSM. Finally, the reconstructed phase current waveform is compared with the measured phase current waveform, and the experimental results show that the above method is effective and feasible.