Patent ID: 6690593
Filing Date: 2004-02-10
Classification: H02M,Y02B

Abstract:
A power inverter outputting power to a polyphase load comprising:an inverter main circuit working to apply phase voltages to the polyphase load through switching elements; a voltage command outputting circuit outputting first voltage commands for respective phases, each of the first voltage commands varying between a maximum and a minimum level; a voltage command converter converting the first voltage commands outputted by said voltage command outputting circuit into second voltage commands in a first and a second conversion cycle which are provided alternately, said voltage command converter converting two of the first voltage commands into the second voltage commands that are equal to one of the maximum and minimum levels in the first conversion cycle and also converting one of the two of the first voltage commands into the second voltage command that is equal to one of the maximum and minimum levels in the second conversion cycle, if the one of the first voltage commands as being converted into the second voltage command that is equal to the one of the maximum and minimum levels both in the first and second conversion cycles is defined as an A-phase voltage command, the A-phase voltage command being selected as one of two of the first voltage commands showing the maximum and minimum levels within the first and second conversion cycles which is greater in absolute value of a corresponding current outputted to the polyphase load, if the other of the two of the first voltage commands as being converted into the second voltage commands that is equal to the one of the maximum and minimum level only in the first conversion cycle is defined as a B-phase voltage command, the B-phase voltage command being selected as one of the first voltage commands which is greater in absolute value of a corresponding current outputted to the polyphase load next to the A-phase voltage command; and a switching control signal outputting circuit working to pulse-width modulate a carrier wave as functions of the respective second voltage commands to output switching control signals for the respective phases to control switching operations of the switching elements of said inverter main circuit.