Method and apparatus for controlling a DC to AC inverter system by a plurality of pulse-width modulated pulse trains

摘要

A pulse train pulse-width modulated by PWM control using a sine-wave signal and a carrier signal is inverted alternately in positive- negative polarity. With a high-frequency AC signal obtained by the inversion, a primary side of a transformer for insulating input and output from each other is excited. This arrangement makes it possible to employ a high- frequency transformer which has a capacity ratio of about 1/30 and a weight ratio of about 1/20 relative to a commercial-frequency transformer, instead of using it. Thus, an inverter apparatus can be reduced in size and weight as compared with the system using the power- frequency transformer. A sine-wave AC waveform with substantially less distortion similar to the waveform output by the conventional PWM control can be obtained with a simple construction.