| 摘要 |
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. |
| 主权项 |
1. A power supply control apparatus of an electric load comprising:
an upstream side switching element that is serially connected to the electric load on an upstream side of the electric load supplied with a load current by power supply from an external power source; a downstream side switching element that is serially connected to the electric load on a downstream side of the electric load; and a control circuit unit that uses a microprocessor as a main component and controls a conduction state of the upstream side switching element and the downstream side switching element, wherein when one switching element of the upstream side switching element and the downstream side switching element is abnormally short-circuited, the power supply is stopped by the other switching element, the power supply control apparatus includes an upstream overcurrent determination storage circuit that detects an upstream overcurrent as the load current flowing in the upstream side switching element exceeds a predetermined value to generate an upstream overcurrent detection signal and a downstream overcurrent determination storage circuit that detects a downstream overcurrent as the load current flowing in the downstream side switching element exceeds a predetermined value to generate a downstream overcurrent detection signal, or a synthetic overcurrent determination storage circuit that generates a synthetic overcurrent detection signal when any one of the upstream overcurrent flowing in the upstream side switching element and the downstream overcurrent flowing in the downstream side switching element, and a voltage monitoring circuit that generates a variable divided voltage in response to a switching state of the upstream side switching element and a switching state of the downstream side switching element, the voltage monitoring circuit includes a third resistance and a fourth resistance that divide a power source voltage of the external power source, at least one of a first resistance and a fifth resistance that is connected to a connecting portion of the third resistance and the fourth resistance at one end thereof, and a second resistance that connects the other end of the at least one of the first resistance and the fifth resistance to a positive wiring or a negative wiring of the power source voltage through the electric load, the other end of the first resistance is connected on one of the upstream side and the downstream side of the electric load, the other end of the fifth resistance is connected on the other of the upstream side and the downstream side of the electric load, the variable divided voltage is generated at both ends of the fourth resistance, the control circuit unit monitors a value of a power source voltage detection signal that is a voltage being in proportion to the power source voltage and a value of a load voltage detection signal that is a voltage being in proportion to the variable divided voltage, calculates a voltage ratio of the value of the power source voltage detection signal and the value of the load voltage detection signal, and monitors the upstream overcurrent detection signal and the downstream overcurrent detection signal, or the synthetic overcurrent detection signal, the control circuit unit further includes abnormality determination means for generating a power supply command signal for one of the upstream side switching element and the downstream side switching element and a conduction command signal for the other one thereof, and for determining an abnormality state of a load wiring for the electric load while the electric load is operated, and abnormality processing means for stopping the generation of the power supply command signal and the conduction command signal when the abnormality determination means determines the abnormality state, and for identifying and storing a plurality of types of abnormality occurrence information, the abnormality determination means determines the abnormality state of the load wiring based on a combination of a value of the voltage ratio corresponding to a generation state of the power supply command signal and the conduction command signal, and a generation state of the upstream overcurrent detection signal and the downstream overcurrent detection signal or the synthetic overcurrent detection signal, and the abnormality state of the load wiring includes at least one of a state where there is a doubt about a positive supply fault abnormality in which an upstream positive wiring of the electric load is connected to a positive electrode wiring of the external power source, or a positive line ground fault abnormality in which the upstream positive wiring of the electric load is connected to a negative electrode wiring of the external power source, a state where there is a doubt about a negative supply fault abnormality in which a downstream negative wiring of the electric load is connected to the positive electrode wiring of the external power source, or a negative line ground fault abnormality in which the downstream negative wiring of the electric load is connected to the negative electrode wiring of the external power source, and a state where there is a doubt about a load short circuit abnormality or a load disconnection abnormality in which the electric load is short-circuited or disconnected. |
