Sliding notch pulse width modulation (PWM)

Claim 1

Apparatus for regulating the RMS voltage value of an output sine wave signal from an inverter by pulse width modulation of the rectangular output signal of the inverter bridge in response to a control signal at a magnitude representative of a selected RMS value, the bridge providing the output signal at a waveform and frequency in dependence on rectangular waveform gate signals presented from a gate signal source to a gate input of the bridge, the apparatus comprising: look-up table means for storing a plurality of information sets and responsive to the control signal presented thereto, each information set being associated with a particular control signal magnitude and each information set defining the pulse width and location of a single pulse width modulation notch with respect to each half cycle of the rectangular waveform gate signals, said look-up table means providing the associated one of said plurality of information sets at an output thereof in response to the presence of the particular control signal magnitude at an input thereof; and pulse width modulation means, interconnected between the inverter gate signal source and the inverter bridge and responsive to the rectangular gate signals and to said information sets from said look-up table means, for providing pulse width modulation of the gate signals with a single pulse width modulation notch at a pulse width and location in each half cycle in dependence on that defined by a present information set, said modulation means presenting said modulated gate signal to the inverter bridge to provide pulse width modulation of the output signal in dependence thereof.