Power converters

摘要

The present invention is directed to a power converter that can be used to interface a motor (4) that requires variable voltage at variable frequency to a supply network (i.e. a bus) providing a nominally fixed voltage and nominally fixed frequency. The power converter includes a first active rectifier/inverter (10) electrically connected to the stator of the motor (4) and a second active rectifier/inverter (14). Both the first and second active rectifier/inverters include a plurality of semiconductor power switching devices. A dc link (12) is connected between the first active rectifier/inverter and the second active rectifier/inverter. A filter (16) is connected between the second active rectifier/inverter and the supply network and includes network terminals. The power converter includes a first controller (18) for the first active rectifier/inverter and a second controller (20) for the second active rectifier/inverter. The first controller (18) uses a dc link voltage demand signal (VDC_MOT*) indicative of a desired dc link voltage to control the semiconductor power switching devices of the first active rectifier/inverter (10) to achieve the desired level of dc link voltage that corresponds to the dc link voltage demand signal. The second controller (20) uses a power demand signal (P*) indicative of the level of power to be transferred to the dc link (12) from the supply network through the second active rectifier/inverter (14), and a voltage demand signal (VBUS*) indicative of the voltage to be achieved at the network terminals of the filter (16) to control the semiconductor power switching devices of the second active rectifier/inverter (14) to achieve the desired levels of power and voltage that correspond to the power and voltage demand signals. The power converter can be employed in a marine propulsion system where the rotor of the motor (4) is used to drive a propeller assembly (2).