Patent ID: 8513911

Claim:
A power converter that can be used to interface a motor that requires variable voltage at variable frequency to a supply network providing a nominally fixed voltage and nominally fixed frequency, the power converter comprising: a first active rectifier/inverter electrically connected to a stator of the motor and including a plurality of semiconductor power switching devices; a second active rectifier/inverter electrically connected to the supply network and including a plurality of semiconductor power switching devices; a dc link connected between the first active rectifier/inverter and the second active rectifier/inverter; a first controller for the first active rectifier/inverter; and a second controller for the second active rectifier/inverter; wherein the first controller uses a dc link voltage demand signal indicative of a desired dc link voltage to control the semiconductor power switching devices of the first active rectifier/inverter to achieve the desired level of dc link voltage that corresponds to the dc link voltage demand signal; and wherein the second controller uses a first demand signal to control the semiconductor power switches of the second active rectifier/inverter to control the level of real power to be transferred into and out of the dc link through the second active rectifier/inverter, and a second demand signal to control the semiconductor power switching devices of the second active rectifier/inverter to control the level of reactive power and/or ac voltage at the supply network.