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Variable frequency drive self-check

  • US 9,654,048 B2
  • Filed: 07/06/2015
  • Issued: 05/16/2017
  • Est. Priority Date: 01/23/2013
  • Status: Active Grant
First Claim
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1. A method, comprising:

  • providing a variable frequency drive including a DC bus configured to provide a positive DC voltage and a negative DC voltage to an inverter, wherein the inverter includes one or more pairs of transistors, wherein an upper transistor of the one or more pairs of transistors is configured to receive the positive DC voltage and a lower transistor of the one or more pairs of transistors is configured to receive the negative DC voltage; and

    before operating the variable frequency drive to drive a motor, operating a controller operatively coupled with the variable frequency drive to complete a set of pre-operation tests, the set of pre-operation tests performed by the controller comprising;

    testing for a short circuit condition of one or more of the transistors including switching the transistors off, measuring a voltage at a node in electrical communication with an output of one or more of the transistors, and evaluating the voltage relative to a first expected value,testing for an open circuit condition of one or more of the transistors including switching the transistors off, switching on one of the transistors, measuring a voltage at a node in electrical communication with an output of the transistor switched on, and evaluating the voltage relative to a second expected value, andtesting for a sensor error condition of one or more current sensors including switching on an upper transistor coupled to a first node and switching on a lower transistor coupled to a second node, measuring a first current at the first node and a second current at the second node, and evaluating the first current and the second current relative to one another.

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