A voltage converting circuit for electric vehicles that is capable of
stably performing precharge control from a high voltage battery to an
inverter. The voltage converting circuit includes a high voltage battery
for supplying electric power to a vehicle drive motor; and an inverter,
which is interposed between the high voltage battery and the vehicle
drive motor and has a capacitor, for converting a direct current,
supplied from the high voltage battery, to an alternating current and
supplying to the vehicle drive motor. The voltage converting circuit
further includes a voltage converter, connected to the high voltage
battery in parallel with the inverter, for converting a voltage of the
high voltage battery to a low voltage and outputting the low voltage; a
contactor circuit, interposed between the high voltage battery and the
inverter, for performing a process of suppressing rush current relative
to the inverter when supplying electric power of the high voltage battery
to the vehicle drive motor; and voltage a converter start-up enabling
units and for enabling start-up of the voltage converter when a
conclusion of the suppression process performed by the contactor circuit
is sensed.