Electric power conversion system

摘要

A power conversion system according to the present invention includes: an inverter circuit unit that converts a direct current power supplied from a direct current source into an alternating current power, the direct current power being supplied to the inverter circuit through a contactor that conducts and interrupts the direct current; a capacitor that smoothes the direct current power; a discharge circuit unit that is connected to the capacitor in parallel, and that includes a discharge resistor for discharging a charge stored in the capacitor and a switching element for the discharge resistor, being connected in series to the discharge resistor; a voltage detection circuit unit that detects voltage between both terminals of the capacitor; a first discharge control circuit that includes a first microcomputer, and that outputs a control signal to control switching of the switching element for discharging; and a second discharge control circuit that outputs an interruption signal to interrupt the switching element for the discharge resistor.

主权项

1. A power conversion system comprising:
an inverter circuit unit that converts a direct current power supplied from a direct current source into an alternating current power, the direct current power being supplied to the inverter circuit through a contactor that conducts and interrupts the direct current; a capacitor that smoothes the direct current power; a voltage detection circuit unit that detects voltage between both terminals of the capacitor; a discharge circuit unit that is connected to the capacitor in parallel, and that includes a discharge resistor for discharging a charge stored in the capacitor and a switching element for discharging the voltage detection circuit unit which detects voltage between both terminals of the switching element, being connected in series to the discharge resistor; a first discharge control circuit that includes a microcomputer that outputs a control signal to control switching of the switching element for discharging, based on a voltage value of the voltage detected by the voltage detecting circuit unit and a discharge signal output from another control unit to start discharging; and a second discharge control circuit that includes a signal output circuit that outputs a conduction command signal to achieve conduction of the switching element for discharging for a predetermined period and an interruption command signal to interrupt the conduction of the switching element for discharging after the conduction for the predetermined period, based on the control signal received from the first discharge control circuit via an insulated transmission element, wherein: after the first discharge control circuit is determined to be in an abnormal state,
the second discharge control circuit receives the detected voltage from the voltage detection circuit unit, the detected voltage from the switching element for discharging the voltage detection circuit unit, and an active discharge signal outputted from the other control unit via the insulated transmission element, andthe signal output circuit outputs the conduction command signal and the interruption command signal based on the detected voltage from the voltage detection circuit unit, the detected voltage from the switching element for discharging the voltage detection circuit unit, and the active discharge signal.