Power frequency changer with controllable input displacement factor

Claim 1

In a frequency changer system for converting AC input supply voltage of a first frequency into AC output voltage of a second frequency for application to an electrical load, the combination comprising, a converter means including a plurality of conduction controlled bilateral switching means operatively connected between a source of said AC input supply voltage and said electrical load, each of said conduction controlled switching means being capable of supporting electrical conduction in both a forward and reverse direction, firing control circuit means operatively connected to said converter means to establish a first and second set of firing instants and to generate a first and second set of firing pulses to operate said bilateral switching means to develop a first and second plurality of voltage segments each exhibiting substantially the same fundamental component, means for generating gating signals controllably displaced with respect to said fundamental components, means for alternately gating said first and second set of firing pulses in response to said gating signals to develop said AC output voltage comprised of alternate portions of said first and second plurality of voltage segments, the controlled displacement of said gating signals with respect to said fundamental component functioning to provide control of the input displacement factor of said converter means.

Claim 6

A method for controlling the input displacement factor of a frequency changer system including a plurality of conduction controlled bilateral switching means arranged to form a converter circuit which is operatively connected between an AC input voltage source and an electrical load comprising the steps of, developing firing instants and corresponding firing pulses for said bilateral switching means such that said converter circuit means is capable of generating a first and second intermediate output waveform each having approximately the same fundamental component, generating gating signals controllably displaced with respect to said fundamental component, alternately gating portions of said firing pulses corresponding to said intermediate output waveforms to fabricate an AC output voltage, and controllably shifting said gating signals with respect to said fundamental component to vary the input displacement factor of said frequency changer system.

Claim 7

A method for controlling the input displacement factor of a frequency changer system including a plurality of conduction controlled bilateral switching means arranged to form a converter circuit which is operatively connected between an AC input voltage source and an electrical load comprising the steps of, developing firing instants and corresponding firing pulses for said bilateral switching means such that said converter circuit means is capable of generating a first and second intermediate output waveform each having approximately the same fundamental component, generating gating signals controllably displaced with respect to said fundamental component, alternately gating portions of said firing pulses corresponding to said intermediate output waveforms to fabricate an AC output voltage, and controllably shifting said gating signals with respect to said fundamental component to vary the input displacement factor of said frequency changer system.