Patent ID: 9680388
Date: 2017-06-13
CPC Classifications: H02H,H02M

Claim:
1. A variable frequency drive system, comprising: a main contactor; a variable frequency drive including: a charging module structured to generate a magnetizing AC voltage, wherein the charging module is structured to selectively provide the magnetizing AC voltage to the transformer, wherein the charging module is structured to be selectively coupled to the AC source and generate the magnetizing AC voltage in response to receiving the main AC voltage; and a sensing and control circuit having a number of sensors operably associated with at least one of the transformer, the converter, and the DC link, the sensing and control circuit being structured to detect a short circuit condition in the variable frequency drive when the magnetizing AC voltage is provided to the transformer based on an output of at least one of the number of sensors, and responsive thereto prevent the main contactor from being closed and thereby prevent the main AC voltage from being provided to the transformer.