| 摘要 |
PROBLEM TO BE SOLVED: To prevent shortage of torque and over-excitation in the motor of an air conditioner, by controlling the waveform of input alternating current into a sine wave and controlling its compressor in an appropriate V/f pattern. SOLUTION: Alternating-current power supply 1 is converted into a direct- current voltage through a power-factor improvement power circuit 2. The converted direct-current voltage is converted into an alternating-current voltage through an inverter circuit 3, and is supplied to the induction motor 4 of a compressor. Thus the compressor is inverter-controlled. At this time a microcomputer 10 outputs to a power-factor improvement control section 2i a control signal Sc to start or end control on a switching element 2d according to the output frequency of inverter control. In addition to the control on the switching element, the microcomputer switches the V/f pattern to either of the first and second V/f patterns in an internal storage section 10a. The power-factor improvement control section 2i starts or ends control on the switching element 2d according to an input control signal Sc. The microcomputer 10 outputs a signal to control the compressor in the switched V/f pattern to the inverter circuit 3 through a drive circuit 6, and the revolution of an induction motor 4 is thereby controlled. |
