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 (
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 (
bus) 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.