Abstract: An upper switching device and a lower switching device in an electric-power conversion unit are separately driven to close by an upper closing command signal and a lower closing command signal, respectively, generated by a calculation control unit; in response to occurrence of an excessive current abnormality or an excessive voltage abnormality, upper and lower selection circuits and a penetration prevention circuit provided in a signal path select an upper three-phase short-circuiting command signal or a lower three-phase short-circuiting command signal, or an upper-and-lower six-phase cutoff command signal, and a penetration prevention time prohibits upper and lower switching devices from being concurrently closed; when an excessive voltage abnormality occurs, the three-phase short-circuiting command signal is immediately generated, without an advanced cutoff operation being performed. As a result, excessive-voltage breakage of the circuit components is prevented.

Abstract: An upper switching device and a lower switching device in an electric-power conversion unit are separately driven to close by an upper closing command signal and a lower closing command signal, respectively, generated by a calculation control unit; in response to occurrence of an excessive current abnormality or an excessive voltage abnormality, upper and lower selection circuits and a penetration prevention circuit provided in a signal path select an upper three-phase short-circuiting command signal or a lower three-phase short-circuiting command signal, or an upper-and-lower six-phase cutoff command signal, and a penetration prevention time prohibits upper and lower switching devices from being concurrently closed; when an excessive voltage abnormality occurs, the three-phase short-circuiting command signal is immediately generated, without an advanced cutoff operation being performed. As a result, excessive-voltage breakage of the circuit components is prevented.

Abstract: On-vehicle electrical loads (121,122) are connected to an on-vehicle battery (101) via a series circuit including a load switching element (221,222) and a reverse current interrupting element (200a) for a load circuit, and a feeding switching element (120A) that is closed in response to closure of a power supply switch (110). The element (FET) (200a) is closed when the switch (110) is closed and a power supply voltage is applied to a load power supply terminal (Vba) connected to the element (120A), to thereby be energized in an energization direction of an internal parasitic diode thereof. The element (200a) is de-energized when the switch (110) is opened. Thus, malfunction is prevented, which occurs when the element (120A) is opened, a short-to-power flows backward via the element (200a) into the terminal (Vba) so as to feed power to another device connected to the element (200a).

Abstract: Disclosed is a power supply control apparatus of an electric load that includes an upstream side switching element and a downstream side switching element and detects various abnormality states of a load wiring by a small number of detection signals. The power supply control apparatus includes a control circuit unit that gives a power supply command signal to the upstream switching element connected in series with the electric load and gives a conduction command signal to the downstream switching element, open-circuits the upstream and downstream switching elements by a synthetic overcurrent determination storage circuit that is operated in response to an overcurrent detecting circuit, monitors a value of one variable divided voltage generated by the voltage monitoring circuit for the electric load, and identifies and stores a wiring abnormality such as a negative line supply fault, a positive line ground fault, and a load short circuit abnormality.

Abstract: Disclosed is a power supply control apparatus of an electric load that includes an upstream side switching element and a downstream side switching element and detects various abnormality states of a load wiring by a small number of detection signals. The power supply control apparatus includes a control circuit unit that gives a power supply command signal to the upstream switching element connected in series with the electric load and gives a conduction command signal to the downstream switching element, open-circuits the upstream and downstream switching elements by a synthetic overcurrent determination storage circuit that is operated in response to an overcurrent detecting circuit, monitors a value of one variable divided voltage generated by the voltage monitoring circuit for the electric load, and identifies and stores a wiring abnormality such as a negative line supply fault, a positive line ground fault, and a load short circuit abnormality.

Abstract: On-vehicle electrical loads (121,122) are connected to an on-vehicle battery (101) via a series circuit including a load switching element (221,222) and a reverse current interrupting element (200a) for a load circuit, and a feeding switching element (120A) that is closed in response to closure of a power supply switch (110). The element (FET) (200a) is closed when the switch (110) is closed and a power supply voltage is applied to a load power supply terminal (Vba) connected to the element (120A), to thereby be energized in an energization direction of an internal parasitic diode thereof. The element (200a) is de-energized when the switch (110) is opened. Thus, malfunction is prevented, which occurs when the element (120A) is opened, a short-to-power flows backward via the element (200a) into the terminal (Vba) so as to feed power to another device connected to the element (200a).