| 摘要 |
PROBLEM TO BE SOLVED: To eliminate the appearance of noise at the time of switching a chopping of an upper and a lower arm. SOLUTION: The power of an AC power supply 1 is rectified by a voltage doubler rectifier circuit 2 to DC of double voltage. When the DC of double voltage is supplied to armature windings of a brushless motor 4 through a transistor module section 3, a control circuit 10 detects the position of a rotor 4a based on a position signal from a position detecting section 5 and turns transistors U, V, W of an upper arm and transistors X, Y, Z of a lower arm of the transistor module section ON and OFF based on the detected position. At that time, either of the upper and the lower arm is chopped and the chopping of the upper and the lower arm is switched at a specified timing. When the specified timing is the same as an excitation switching timing due to the ON/ OFF driving of the transistors, an edge of the chopping is detected after that timing and then the chopping of the upper and the lower arm is switched. When the specified timing is the time before the position detection, an edge of the chopping is detected after the time before the position detection and then the chopping of the upper and the lower arm is switched. |
