Experimental investigations into the dual-randomization PWM scheme for power converters

Randomized pulse width modulation schemes in power converters have shown potential for relaxing filtering requirements and reducing electromagnetic interference. Majority of existing schemes randomize one modulation parameter to disperse the harmonic contents of the output of the power converter. This paper concerns the investigation of a new dual-randomization scheme by means of extensive experimentation, which includes comparison with existing randomised PWM schemes. The effects of randomizing the two independent modulation parameters, carrier frequency and pulse position, on the harmonic content for a given output of the converter are examined. These experimental results, achieved by a simple microprocessor, underline the superior spectral power spread of the new scheme, and will lead to lower electromagnetic interference and associated adverse effects.