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(11) | EP 1 738 990 A8 |
| (12) | CORRECTED EUROPEAN PATENT APPLICATION |
| Note: Bibliography reflects the latest situation |
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| (54) | Voltage boosting circuit and electrically-driven power steering device |
| (57) A switching device of a chopper circuit is interrupted from a switching circuit when
the switching device has a breakdown, whereby power source input is directly output
without being boosted by chopper operation. A motor controller provided to ECU of
an electrically-driven power steering device is equipped with a chopper circuit for
carrying out a voltage boosting operation, a detection circuit for detecting a failure
of a first switching device TR1 in the chopper circuit, and an interrupting relay
switch. A controller carries out ON/OFF control on the first switching device, and
when the detection circuit detects the failure of the switching device, the controller
turns off the interrupting relay switch, and separates the first switching device
from the chopper circuit. At this time, the battery voltage Vin is output as an output
voltage Vout without being boosted by the chopper circuit.
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