The present provides a leakage detection circuit for an electric vehicle, and
so on, capable of calculating a leakage resistance. The leakage detection circuit
for an electric vehicle detects a current Ig11(t1) that flows
in leakage resistances Ra and Rb when one leakage detection
switch SW1 is closed at t1 and the other leakage detection
switch SW2 is opened, and detects a current Ig12(t2)
when the switch SW1 is opened at t2 and the switch SW2
is closed. In addition, the circuit detects voltages Vl11(t1,
t2) and Vl12(t1, t2) of portions where
these leakage detection resistances Ra are connected. A combined value
Rl of the leakage resistances is calculated by a leakage calculator
based on the following equation 34
##EQU1##
