| CPC H02M 1/44 (2013.01) [B60R 16/02 (2013.01); G01R 31/282 (2013.01); H02M 3/155 (2013.01)] | 13 Claims |
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1. A noise reduction device comprising:
a detection circuit that, in operation, detects a noise component generated in a load;
a noise reduction circuit that, in operation, generates an offset signal with reverse polarity of the noise component generated in the load based on the noise component detected by the detection circuit; and
a failure diagnosis circuit that, in operation,
detects a level of the offset signal generated by the noise reduction circuit based on the noise component detected by the detection circuit,
determines whether or not the level of the offset signal deviates from an appropriate range,
diagnoses, based on a determination result, whether or not a failure has occurred in the noise reduction circuit,
diagnoses that a failure has occurred in the noise reduction circuit in response to determining that the level of the offset signal deviates from the appropriate range, and
diagnoses that no failure has occurred in the noise reduction circuit in response to determining that the level of the offset signal is within the appropriate range,
wherein the noise reduction circuit includes an isolation transformer including a primary winding and a secondary winding,
wherein a ratio of a number of windings of the primary winding to a number of windings of the secondary winding is 1:1,
wherein a switching circuit connected to the load is controlled with power lower than normal power in a case where the failure diagnosis circuit diagnoses that the failure has occurred in the noise reduction circuit, and
wherein the level of the offset signal is substantially equal to a level of the noise component.
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