Abstract: When an outdoor machine 2 includes a signal line connector 21 for receiving ON/OFF signals for a compressor, an outdoor machine drive control unit 30 of an air conditioner includes an inverter device 32 for supplying power variable in frequency to the compressor 22, and a control device 33 for controlling the inverter device 32 to gradually increase the number of revolutions of the compressor 22 when the ON/OFF signal for the compressor received through the signal line connector 21 changes from the OFF condition to the ON condition. The air conditioner outdoor machine drive control unit 30 enables to construct an inverter-type air conditioner by using a general heat-pump-type indoor machine and merely mounting it in an outdoor machine.

Abstract: This invention relates to a brushless motor driving system for driving an outdoor fan of an air conditioner. The driving system comprises a Hall probe for detecting a position of a rotor of a brushless motor, an inverter circuit consisting of a plurality of switching elements connected in bridge-connection, the inverter circuit supplying ON-OFF electric current to stator coils of the brushless motor, and a control means for switching the switching elements of the inverter circuit based on the output signal of the Hall probe. Before starting the motor, the control means controlls the switching elements to supply DC PWM-controlled current to the stator coils of the motor in synchronization with the output signal of the Hall probe, so that the rotor is braked, stopped and set to home position.

Abstract: A filter apparatus has a current-detecting coil. The coil detects a high-frequency leak current flowing from the phase-windings of a motor to the earth terminal through the closed case of a compressor. A current-canceling circuit generates a current similar in waveform to the high-frequency leak current detected by the coil. The current thus generated cancels out the high-frequency leak current.