A PC-based pulse-width modulator for static converters

Developments in power control techniques for pulse-width-modulated inverters are often ignored because of lack of time for adequate testing and evaluation. A programmable PC-based pulse-width modulator that is designed to alleviate this problem is described. The modulator is capable of generating, in ready-to-use form, gating signals for most types of carrier or programmable pulse-width modulation (PWM) scheme under open-loop operating conditions and for most types of converter. It can also generate and display associated converter-output voltage and current waveforms and their respective frequency spectra for further evaluation of selected PWM schemes. Therefore, tasks such as the selection of PWM strategy, switching frequencies, and voltage/frequency curves (for variable-speed AC drives under open-loop control) are easier to perform. Moreover, the proposed research and development tool differs from similar devices in that it is user friendly, multipurpose, and versatile. Selected performance features of the developed prototype are demonstrated by presenting the associated experimental waveforms