High-Frequency Voltage Injection Sensorless Control Technique for IPMSMs Fed by a Three-Phase Four-Switch Inverter With a Single Current Sensor

This paper proposes a sensorless control strategy using sine-wave high-frequency (HF) voltage injection for interior permanent magnet synchronous motors (IPMSMs) fed by a three-phase four-switch (TPFS) inverter, with a single current sensor. Three-phase currents are reconstructed by a single current sensor with modification of the inverter topology. The principle of the phase current reconstruction strategy in TPFS inverter is analyzed and the topology of the proposed drive system is illustrated. Then, the normal areas and the dead zones for current reconstruction are investigated in detail, and the vector synthesis method is also explained. Furthermore, the zero vector synthesis strategy and the pulse width modulation (PWM) generation method are also presented, where two current sampling points are applied in each PWM cycle for phase current reconstruction. Finally, an HF voltage injection based sensorless control strategy in the proposed drive system is realized by voltage projection on the proposed k-l axis coordinate system. The reconstructed phase currents track the actual ones accurately, and the estimation error of the rotor position by using the reconstructed phase currents is within ±0.1 rad. The effectiveness of the proposed scheme is verified by simulation and experimental results on a 5-kW IPMSM prototype.