A Restart Method for PMSM Driving a High-Inertia Load with a Single DC-link Shunt Resistor

Abstract

In the application of inverter with a single DC-link shunt resistor, in order to realize the speed sensor-less control of the motor the DC-link current is used to reconstruct the motor phase current. Since there is no speed sensor, the actual position and speed of the motor at the time of re-starting remain unknown. This paper presents a method for re-starting a permanent magnet synchronous motor (PMSM) driving a high-inertia load with a single DC-link shunt resistor. When the line back-EMF amplitude is lower than the DC-link voltage, the half bridge of the inverter adopts a specific impulse conduction mode to instantaneous short-circuit two of the three phases of the motor. And, the negative peak envelope of the DC-link current response has the same frequency with the motor line back EMF, also the amplitude is proportional to the motor line back EMF. The actual rotor position and speed is determined by analyzing the phase relationship and detecting the characteristic points of the DC-link current peak. The experimental results show that the proposed method can re-start the PMSM with high-inertia load using a single DC-link current sample, and has the advantages of low parameter sensitivity, easy engineering realization, and strong versatility.