A simple sensorless method for sinusoidal PWM converters

This paper describes a simple sensorless method of PWM converters which can remove the line voltage sensors. It has the following characteristics. The voltage sensorless method is realized only by adding two operational amplifiers to the conventional PWM control circuit. Therefore, it has low cost and small size. The line current waveform can be improved by compensating voltage drops of the input filter reactor and dead-time of IGBTs. Quick response is also obtained on the high speed fluctuation of voltage and frequency or transient states. It can get characteristics other than the conventional complexity sensorless control methods. As a result, the input power factor and the total input current distortion of more than 99.5% and less than 2.3% are achieved, respectively on a 3 kW system. It not only obtains excellent performance but also realizes the small size, simple control construction and low cost converter.