Patent ID: 8008885
Filing Date: 2011-08-30
Classification: B63H,Y02T

Abstract:
1. 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 the stator of the motor and including a plurality of semiconductor power switching devices; a second active rectifier/inverter 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 filter connected between the second active rectifier/inverter and the supply network, the filter including network terminals; 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; wherein the second controller uses a power demand signal indicative of the level of power to be transferred to the dc link from the supply network through the second active rectifier/inverter, and a voltage demand signal indicative of the voltage to be achieved at the network terminals of the filter to control the semiconductor power switching devices of the second active rectifier/inverter to achieve the desired levels of power and voltage that correspond to the power and voltage demand signals, and wherein the first controller supplies a control signal that varies in accordance with the prevailing motor conditions to the second controller and the second controller uses the control signal to limit the level of power that is transferred to the dc link from the supply network through the second active rectifier/inverter.