Patent ID: 7649756
Filing Date: 2010-01-19
Classification: H02M

Abstract:
1. A method for reducing common mode noise in a three phase pulse width modulated (PWM) system that includes a three phase waveform generator that generates first, second and third modulating waveforms, a carrier signal generator and a PWM generator that compares modulating waveforms and the carrier signal to generate switch control signals for controlling at least one of converter and inverter switches, the method comprising the steps of: receiving the first, second and third modulating waveforms; identifying one of the modulating waveforms that is at least one of instantaneously the maximum and instantaneously the minimum of the modulating waveforms as a first identified waveform, wherein comparison of the first identified waveform to the carrier signal would generate a first on-off pulse sequence associated with a phase corresponding to the first identified waveform; generating switch control signals associated with the phase corresponding to the first identified waveform that cause a modified on-off pulse sequence that is phase shifted from the first pulse sequence; using the second and third modulating waveforms to generate second and third on-off pulse sequences corresponding to second and third phases; and providing the modified pulse sequence and the second and third pulse sequences to the one of the inverter and the converter.