| 摘要 |
PROBLEM TO BE SOLVED: To obtain a control method in which a compressor is protected properly irrespective of a load state when a brushless motor is used as a compressor motor or the like and irrespective of the change state (load change) of a discharge temperature at the compressor. SOLUTION: A DC power supply Vdc is switched by an inverter part 3 so as to be applied to a brushless motor 4 as a compressor motor, an applied voltage is made variable at the duty ratio of a chopping operation, and the rotation of the brushless motor 4 is controlled. At this time, the position of a rotor (a) is detected by a position detection signal from a position detection circuit 5, a discharge temperature at a compressor is detected by a temperature detection signal from a discharge-temperature detection part 9, and the applied voltage is lowered by every prescribed value when the discharge temperature reaches a prescribed value (a protective temperature value). Here, the applied voltage is decided so as to be lowered to the prescribed value according to the difference between a temperature when the discharge temperature reaches the prescribed value and a temperature just before it. Then, the applied voltage is lowered by every prescribed value at every prescribed time until the speed of rotation of the brushless motor 4 is lowered by a prescribed speed of rotation. |
