A New Speed-Varying Ellipse Voltage Injection Method for Sensorless Drive of Permanent-Magnet Synchronous Motors with Pole Saliency: -- New PLL Method Using High Frequency Current Auto-Correlated Signal --

This paper proposes a new sensorless vector control method for salient-pole permanent-magnet synchronous motors. With regard to phase estimation, the sensorless vector control method is featured by a new high frequency voltage injection method distinguished from the conventional ones by a unique ellipse shape of the spatially rotating high frequency voltage, and by a new PLL method whose input is a high frequency current auto-correlated signal. The new vector control method established by two innovative technologies can have the following high-performance and attractive characteristics: 1) it can allow 250% rated torque at standstill; 2) it can operate from zero to the rated speed under the rated motoring or regenerating load; 3) it accepts instant injection of the rated load even for zero-speed control; 4) it accommodates a load with huge moment of inertia; 5) phase estimation is robust against inverter dead time; 6) computational load for estimating rotor phase is very small. Usefulness of the proposed new vector control method is verified through extensive experiments.