Electric power source for motor vehicle

Abstract

An electric power source for a motor vehicle is equipped with a welded state discriminator, and while a positive-side contactor and negative-side contactor are controlled to be switched off, the welded state discriminator detects a voltage of a positive-side contactor or negative-side contactor on its loading side with respect to a connecting point of a battery unit on a positive side and a battery unit on a negative side, so that when in a plus voltage where the detected voltage thus obtained is larger than a predetermined voltage, the positive-side contactor is judged to be in a welded state, and when in a minus voltage where the detected voltage is larger than the predetermined voltage, the negative-side contactor is judged to be in a welded state.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit diagram showing a conventional electric power source;

FIG. 2 is a block diagram illustrating an electric power source for driving a motor vehicle in accordance with an embodiment of the invention;

FIG. 3 is a block diagram illustrating an electric power source for driving a motor vehicle in accordance with an alternative embodiment of the invention;

FIG. 4 is a flow chart employed for the welded state discriminator to judge a welded state of positive-side and negative-side contactors;

FIG. 5 is a flow chart employed for the welded state discriminator to detect a voltage of a battery unit on the positive side and a voltage of a battery unit on the negative side;

FIG. 6 is a block diagram illustrating an example of the current detection circuit;

FIG. 7 is a graph depicting a circuit failure judgment with regard to the current detection circuit shown in FIG. 6;

FIG. 8 is a graph depicting a circuit offset drift detection with regard to the current detection circuit shown in FIG. 6;

FIG. 9 is a block diagram illustrating an example of a remaining life estimation and detection circuit; and

FIG. 10 is a graph depicting a relation between a discharge duration and a voltage regarding an electrolytic capacitor.

Claims

1. An electric power source for a motor vehicle comprising: a driving battery for driving a motor vehicle, the driving battery connecting a battery unit on a positive side and a battery unit on a negative side in series at a connecting point;a positive-side contactor and a negative-side contactor, the contactors being connected in series to the driving battery on the positive side and the negative side respectively;a control circuit controlling the positive-side contactor and negative-side contactor to be switched on or off; anda welded state discriminator detecting a welded state of the contactor at contact points thereof,wherein the welded state discriminator comprises: a voltage detector detecting a voltage of at least one of the positive-side contactor and negative-side contactor on a loading side thereof with respect to the connecting point for the driving battery; and a judgment circuit discriminating the welded state of the positive-side contactor and negative-side contactor, based on an amount of and a positive or negative property of the detected voltage which is obtained by the voltage detector, andwherein the electric power source is so constructed and arranged that while the control circuit controls the positive-side contactor and negative-side contactor to be switched off, the voltage detector in the welded state discriminator detects a voltage of at least one of the positive-side contactor and negative-side contactor on the loading side thereof and then the judgment circuit compares such detected voltage with a predetermined voltage, so that when in a state of a plus voltage where the detected voltage is larger than the predetermined voltage, the positive-side contactor is judged to be in a welded state, and when in a state of a minus voltage where the detected voltage is larger than the predetermined voltage, the negative-side contactor is judged to be in a welded state.

2. The electric power source for a motor vehicle as recited in claim 1, wherein the predetermined voltage is set to be 20% to 80% of the voltage of the battery unit.

3. The electric power source for a motor vehicle as recited in claim 1, wherein the electric power source is so constructed and arranged that while the control circuit switches on the positive-side contactor and switches off the negative-side contactor, the voltage detector in the welded state discriminator detects a voltage of the positive-side contactor on the loading side thereof, so that a voltage of the battery unit on the positive side is detected.

4. The electric power source for a motor vehicle as recited in claim 1, wherein the electric power source is so constructed and arranged that while the control circuit switches on the positive-side contactor and switches off the negative-side contactor, the voltage detector in the welded state discriminator detects a voltage of the negative-side contactor on the loading side thereof, so that a voltage of the battery unit on the positive side is detected.

5. The electric power source for a motor vehicle as recited in claim 1, wherein the electric power source is so constructed and arranged that while the control circuit switches off the positive-side contactor and switches on the negative-side contactor, the voltage detector in the welded state discriminator detects a voltage of the positive-side contactor on the loading side thereof, so that a voltage of the battery unit on the negative side is detected.

6. The electric power source for a motor vehicle as recited in claim 1, wherein the electric power source is so constructed and arranged that while the control circuit switches off the positive-side contactor and switches on the negative-side contactor, the voltage detector in the welded state discriminator detects a voltage of the negative-side contactor on the loading side thereof, so that a voltage of the battery unit on the negative side is detected.

7. The electric power source for a motor vehicle as recited in claim 1, wherein the electric power source further comprises a remaining life estimation and detection circuit, and the remaining life estimation and detection circuit is provided with an electrolytic capacitor for a life judgment, so that a capacitance of the electrolytic capacitor is detected to judge a life.