Importance

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Abstract

A method and apparatus for distributing alternating electrical current to motors via a direct current bus is provided. The method and apparatus is directed towards a system wherein a plurality of motors may be controlled by individual motor drives. AC power is supplied to a single active rectifier circuit (as opposed to one per motor) which maintains unity power factor in the AC power and which develops DC power for a DC distribution system. The DC distribution system, which comprises a set of controllable contactors, is in turn coupled to a plurality of motor drive units which convert the DC power into properly conditioned AC power for operating associated motors. The system operates in response to commands issued by a programmable controller. In the event of a fault in one of the drive units, fault isolation may be accomplished by individually turning off each motor drive in sequence via the associated contactor to determine the faulty drive unit. Alternatively, all of the motor drive units may be turned off and then individually turned back on until the fault reappears. Once the fault reappears, the faulty unit is identified and disabled and the remaining units are turned back on.

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First Claim