Reversible inverter system having improved control scheme

摘要

An inverter system for supplying variable frequency alternating current power to a load such as an a.c. motor includes an inverter bridge of controlled rectifiers which are selectively rendered conductive by the application thereto of gating pulses. The gating signals result from a control circuit which includes a voltage controlled oscillator responsive to a command signal having a d.c. magnitude and polarity which in turn outputs a signal having a substantially saw-tooth wave shape. Comparator circuits responsive to the saw-tooth wave shape signal provide timing pulses and direction signals which are applied to a shift register to effect movement of the register contents the extant status of which initiates the production of the gating signals for rendering the semiconductors conductive.