3-PHASE PWM INVERTER SYSTEM USING SINGLE DC-LINK CURRENT SENSOR

摘要

A 3-phase PWM(Pulse Width Modulation) inverter system using a single current sensor is provided to improve a pulsation phenomenon of a load current by changing a voltage modulation process which is applied to recover a 3-phase current. A 3-phase PWM inverter system using a single current sensor includes a single current sensor(4), and a controller(7). The single current sensor detects a DC link current of the inverter. The controller outputs a reference voltage vector which is a reference of a load control. An output reference voltage vector determines an initial sector included in a voltage vector plane. The controller determines a sector where the reference voltage vector is included by applying a hysteresis according to a moving direction of the reference voltage vector after determining the initial sector. The controller determines an amended voltage vector which is injected to recover a phase-current in a dead zone where a maintaining time of a PWM switching is smaller than a specific time in the voltage vector plane based on the sector determined by the hysteresis. The controller amends the reference voltage vector by modulating the reference voltage vector based on the determined amended voltage vector. The controller outputs the amended reference voltage vector to the inverter, and controls an operation for recovering a 3-phase current based on a DC link current which is detected through the single current sensor.