Power circuit abnormality detection method
First Claim
1. A power circuit abnormality detection method for being applicable to a power circuit and for detecting whether or not an abnormality in a power source relay exists, the power circuit which comprises:
- the power source relay which opens and closes a connection between a direct current power source which drives an electric motor and a motor drive circuit which includes a plurality of switching elements and which supplies a drive current to the electric motor;
a smoothing condenser which is connected between a power source wire between the power source relay and the motor drive circuit and a ground wire to absorb ripples in current;
a pre-charge circuit which opens and closes a connection between the direct current power source and the smoothing condenser by bypassing the power source relay to pre-charge the smoothing condenser; and
a discharge circuit, including a discharge switch and a discharge resistance, which is connected between the power source wire and the ground wire in parallel to the smoothing condenser and which discharges electric charges stored in the smoothing condenser via the discharge resistance when the discharge switch is closed,the power circuit abnormality detection method comprising;
detecting whether or not an open-contacts abnormality in the power source relay exists based on whether or not a charge voltage of the smoothing condenser is reduced when a predetermined period of time has elapsed since the pre-charge circuit is actively opened after both the discharge circuit and the power source relay are closed.
1 Assignment
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Accused Products
Abstract
A power circuit abnormality detection method for a power circuit detects whether an abnormality in a power source relay exists. The power circuit includes a pre-charge circuit opening and closing a connection between a direct current power source and a smoothing condenser by bypassing the power source relay to pre-charge the smoothing condenser, and a discharge circuit connected in parallel to the smoothing condenser to discharge electric charges stored in the smoothing condenser via a discharge resistance when a discharge switch is closed. The power circuit abnormality detection method includes a step of detecting whether the open contact abnormality in the power source relay exists based on whether a charge voltage of the smoothing condenser is reduced when a predetermined period of time has elapsed since both the discharge circuit and the power source relay are closed after the pre-charge circuit is opened.
15 Citations
12 Claims
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1. A power circuit abnormality detection method for being applicable to a power circuit and for detecting whether or not an abnormality in a power source relay exists, the power circuit which comprises:
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the power source relay which opens and closes a connection between a direct current power source which drives an electric motor and a motor drive circuit which includes a plurality of switching elements and which supplies a drive current to the electric motor; a smoothing condenser which is connected between a power source wire between the power source relay and the motor drive circuit and a ground wire to absorb ripples in current; a pre-charge circuit which opens and closes a connection between the direct current power source and the smoothing condenser by bypassing the power source relay to pre-charge the smoothing condenser; and a discharge circuit, including a discharge switch and a discharge resistance, which is connected between the power source wire and the ground wire in parallel to the smoothing condenser and which discharges electric charges stored in the smoothing condenser via the discharge resistance when the discharge switch is closed, the power circuit abnormality detection method comprising; detecting whether or not an open-contacts abnormality in the power source relay exists based on whether or not a charge voltage of the smoothing condenser is reduced when a predetermined period of time has elapsed since the pre-charge circuit is actively opened after both the discharge circuit and the power source relay are closed. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A power circuit abnormality detection method for being applicable to a power circuit and for detecting whether or not an abnormality in a power source relay exists, the power circuit which comprises:
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the power source relay which opens and closes a connection between a direct current power source which drives an electric motor and a motor drive circuit which includes a plurality of switching elements and which supplies a drive current to the electric motor; a smoothing condenser which is connected between a power source wire between the power source relay and the motor drive circuit and a ground wire to absorb ripples in current; a pre-charge circuit which opens and closes a connection between the direct current power source and the smoothing condenser by bypassing the power source relay to pre-charge the smoothing condenser; and a discharge circuit, including a discharge switch and a discharge resistance, which is connected between the power source wire and the ground wire in parallel to the smoothing condenser and which discharges electric charges stored in the smoothing condenser via the discharge resistance when the discharge switch is closed, the power circuit abnormality detection method comprising; detecting whether or not an open-contacts abnormality in the power source relay exists based on an increase in a charge voltage of the smoothing condenser after a predetermined period of time has elapsed since the power source relay is closed after the discharge circuit is in an on-state and since the pre-charge circuit is actively opened. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification