ON-VEHICLE ELECTRIC SYSTEM

摘要

PROBLEM TO BE SOLVED: To cause a smoothing capacitor 20 to discharge electrical charges when an abnormal condition occurs.SOLUTION: An on-vehicle electric system 1 includes: an inverter circuit 10 driving a three-phase AC motor 2; a smoothing capacitor 20 stabilizing an output voltage provided to the inverter circuit 10 from a high-voltage power-supply 3; a discharge resistor 30 connected between a positive electrode and a negative electrode of the smoothing capacitor 20; and a discharge switching element 40 connected between the positive electrode and the negative electrode of the smoothing capacitor 20 in series to the discharge resistor 30. A control device 80 outputs an off-signal for opening between the positive electrode and the negative electrode of the smoothing capacitor 20 to the discharge switching element 40. The discharge switching element 40 is a normally-on type switching element that connects between the positive electrode and the negative electrode of the smoothing capacitor 20 through the discharge resistor 30 in a period other than the period in which the off-signal is provided from the control device 80.