| 摘要 |
PURPOSE:To make the current peak value low throughout the low and high speed total range by a method wherein when the revolution speed is large, then, the switching frequency is made small and the condition time length is made long; and when the revolution speed is small, then, the switching frequency is made large and the conduction time length is made short. CONSTITUTION:The frequency convertor 12 is established in order that in receiving the detection signal of the motor revolution speed, the frequency can be low as the revolution speed becomes large; and the frequency can be high as the revolution speed becomes small. And the switching frequency of the output is decided depending upon the motor revolution speed. The conduction time length of the switching elements 4-9 which turn the stator windings 1-3 of the motor ON/OFF, is decided by the setting of time length of the control signal of the dial unit 13 through the speed setting unit 14. Therefore, it is decided based on the revolution per minute, in which the generation torque decided by means of the setting of the continuity time length through the speed setting unit 14 and the switching frequency are in harmony with the load. And further, the revolution speed permits to be adjusted by adjusting the conduction time length. |
