POWER SUPPLY SYSTEM OF ELECTRIC VEHICLE AND CONTROL METHOD THEREOF

Relays (SMR 1, SMR2) are inserted and connected between a battery (BA) and a boosting converter (12A), and relays (SR1, SR2) are inserted and connected between a battery (BB) and a boosting converter (12B) connected are relays (SMR 1, SMR2). A controller (30) controls control signals (CONT1 - CONT4) controlling open/close of the relays (SMR 1, SMR2, SR1, SR2). When short-circuit of a switching element occurs in the boosting converter (12A, 12B), controller 30 controls turning-off of the relays (SMR 1, SMR2, SR 1, SR2) such that at least one of order and timing of turning off the relays is changed depending on which of the switching elements is short-circuited.