CONTROL UNIT OF INDUCTION MACHINE

摘要

PURPOSE:To reduce the current capacity of a power inverter and a transformer connected to the power inverter, by providing a secondary current limiter circuit to a secondary chopper control circuit to regulate the secondary current of an induction machine. CONSTITUTION:A power rectifier 2 is connected to the secondary side of an induction machine 1, on the output side of which a secondary chopper 3 is connected. A series circuit of a diode 4 and a capacitor 5 is connected in parallel to the secondary chopper 3. A power inverter 8 is provided to regenerate the secondary power or the induction machine 1 to an AC power source. A regenerating chopper 6 is provided to regulate the current from the capacitor 5 to the power inverter 8 between the capacitor 5 and the power inverter 8 so as to keep the capacitor voltage in a predetermined value. The current limit value of a regenerating circuit from a command machine 15 is divided by a sliding operational value of a computing element 26 and the current limit value of the secondary chopper 3 is operated. In an optional machine 24 the original limit value is compared with the current limit value from a divider 25 and a smaller value is selected.