A leakage detection circuit for an electric vehicle includes a battery
pack, first and second leakage detection switches, a controller, a
leakage detection resistor, a voltage detector, and a calculator. The
first and second leakage detection switches are connected to the high and
low voltage sides of the battery pack, respectively. The battery pack
includes a plurality of batteries that are connected in series. The
midpoint of the leakage detection resistor is connected to the ground via
the first and second leakage detection switches. The controller
alternately turns the first and second leakage detection switches ON.
Thus, the voltage detector detects leakage voltage values that are
generated in the leakage detection resistor. The controller turns the
first and second leakage detection switches ON and OFF, respectively, to
detect a first leakage voltage value of the leakage voltage values. On
the other hand, the controller turning the first and second leakage
detection switches OFF and ON, respectively, to detect a second leakage
voltage value of the leakage voltage values. Consequently, the calculator
detects leakage based on the first and second leakage voltage values.