MULTILEVEL STATIC FREQUENCY CONVERTER FOR FEEDING INDUCTION AND SYNCHRONOUS MOTORS

摘要

FIELD: electrical engineering; power supply to induction and synchronous motors from three- or single-phase mains.;SUBSTANCE: proposed multilevel static frequency converter designed for feeding induction and synchronous motors with sine-wave current of power factor close to unity from over 3-kV, 0.5- to 15-MW three- or single-phase mains and for power regeneration during their generator braking has power transformer, output filter, main control unit, and inverter-regeneration modules incorporating power transistors with built-in backward diodes forming two single-phase bridges connected in parallel over DC circuit through current sensor. Connected to first-bridge DC circuit are capacitor bank and voltage sensor. First-bridge AC circuit is connected to one of power-transformer secondary windings through current sensor and switch; the latter has two transistors connected in parallel opposition. Second-bridge AC circuit that functions as module output is connected in parallel with outputs of other modules to form three star-connected groups. Each module has local control unit for shaping power transistor control pulses in compliance with current operating mode of module and with control signals arriving from main control unit over optical channel.;EFFECT: enlarged range of frequency converters.;1 cl, 4 dwg