Abstract: A DC-DC converter includes a synchronous rectification converter that converts electric power, a voltage detection circuit that detects a voltage proportional to an output voltage of the converter, a converter controller that compares a detection voltage detected by the voltage detection circuit with a reference voltage and controls an operation of the converter to provide a constant or substantially constant voltage of the detection voltage, and a command processor that sets, in a case where a target voltage command value input from an ECU is lower than a voltage value of the output voltage of the converter, a voltage value of the reference voltage to be equal or substantially equal to a voltage value of the detection voltage.

Abstract: An abnormality determiner turns OFF a third switch and controls a converter controller to stop operating in a case where a voltage value detected by a voltage detector during a normal mode exceeds a first threshold value. The abnormality determiner determines that a first switch has an abnormality in a case where the voltage value exceeds a second threshold value in a state where the converter controller is stopped. The abnormality determiner controls the converter controller to operate in a case where the voltage value is equal to or smaller than the second threshold value in a state where the converter controller is stopped. The abnormality determiner determines that the converter controller has an abnormality in a case where the voltage value exceeds a third threshold value in a state where the converter controller is operated.

Abstract: A DC-DC converter includes a synchronous rectification converter that converts electric power, a voltage detection circuit that detects a voltage proportional to an output voltage of the converter, a converter controller that compares a detection voltage detected by the voltage detection circuit with a reference voltage and controls an operation of the converter to provide a constant or substantially constant voltage of the detection voltage, and a command processor that sets, in a case where a target voltage command value input from an ECU is lower than a voltage value of the output voltage of the converter, a voltage value of the reference voltage to be equal or substantially equal to a voltage value of the detection voltage.

Abstract: An abnormality determiner turns OFF a third switch and controls a converter controller to stop operating in a case where a voltage value detected by a voltage detector during a normal mode exceeds a first threshold value. The abnormality determiner determines that a first switch has an abnormality in a case where the voltage value exceeds a second threshold value in a state where the converter controller is stopped. The abnormality determiner controls the converter controller to operate in a case where the voltage value is equal to or smaller than the second threshold value in a state where the converter controller is stopped. The abnormality determiner determines that the converter controller has an abnormality in a case where the voltage value exceeds a third threshold value in a state where the converter controller is operated.