The auxiliary power supply is comprised of the auxiliary inverter (SIV) and charger (BC) , The cabinet is integrated with filter reactor, transformer, pre charging unit, cooling fan and auxiliary control unit (ACU), which can invert the DC voltage (DC1500V) into three-phase AC voltage (AC380V), providing stable three-phase four wire AC voltage to air conditioner, air compressor, lighting etc., and it can convert AC380V voltage into DC110V voltage to be supplied to the storage battery charging and vehicleDC load.