| 摘要 |
PURPOSE:To provide an equipment and a method for controlling a PWM inverter which allows a noise generated from a motor to be easily heard even when the condition of a load of the motor or the installation environment of the motor changes. CONSTITUTION:A carrier wave variation width controlling circuit 13 sets a width of a carrier wave frequency according to the central frequency of a carrier wave from a command circuit 12 which commands the central frequency of the carrier wave. A carrier wave controlling circuit 14 changes the carrier wave frequency by the variation width in point of time. A signal having the central frequency commanded by the command circuit 12 of the central frequency of the carrier wave and a pattern signal from the carrier wave controlling circuit 14 are added by an adder 11 and then a PWM frequency command signal which changes cyclically around the central frequency is generated. A carrier wave generating circuit 4, receiving the PWM frequency command signal, makes a carrier wave which changes in point of time by the variation width set just around the central frequency. |
