AirStage AO54FJ, Service Manual

Page: 44 / 169

03-05
3-2-9 DC Motor (DC Inverter)
The rotor of DC compressor motor is made of permanent magnet, and it creates the
revolving magnetic field by applying the voltage that is obtained by PAM control to
the stator winding. And the pull and repulsion between the rotating magnetic field
and the permanent magnet creates the force toward the same direction of the rotating
magnetic field, and the rotor rotates.
The rotor and the permanent magnet need to be controlled to match up the revolving
magnetic field to the polarity. In order to control the positioning detection, there are
several types. One is the sensor type that built in the rectifier or Hall Effect Device,
and the other type is the one that the positioning detection is done by the reverse
power force which is excited at the stator winding by the rotation (Fleming
’ s Right
Hand Rule).
The speed of the compressor can be changed by drifting the voltage (PAM control /
PWM control).
The rotor is made of permanent magnet.
No slipping is occurred and the efficiency is good.
When measuring the motor frequency by using a clamp meter,
the indication is 2 time of actual rotation speed since it used
4 pole permanent magnet.