Output Waveform Improvement of High Switching Frequency PWM Inverters Introducing Digital Signal Processing

A method to improve output current waveform of high switching frequency PWM inverters introducing digital signal processing is presented. For a given clock frequency of the digital PWM controller, the control resolution is inversely proportional to the switching frequency. Consequently, a higher switching frequency results in poorer control resolution. In the proposed method, poor resolution of a high switching frequency digital PWM controller is improved by a noise shaper which is widely used in class D digital audio amplifiers. The effectiveness of the noise shaper used in the three phase voltage source inverters is demonstrated by some experimental results employing a prototype implemented by a FPGA.