| 摘要 |
PROBLEM TO BE SOLVED: To increase the torque at high speed of a servo motor by varying the value of the clamp level of the three-phase voltage command to carrier between positive side and negative side, by means of a controller which makes voltage commands. SOLUTION: For negative side time ta required for current detection must be secured in view of restriction on current detection similar to a prior art embodiment, but for upper arm, side, there is no restriction time, so the positive overclamp value Vda is made zero, and for the negative overclamp value Vdd is made the same as a prior art embodiment. Hereby, the maximum amplitude of the voltage command can be made large by Vda/2 than the prior art positive overclamp value Vda, and the on time of the transistor can be made longer, and the output voltage to the servo motor can be taken large. As a result, it follows that the voltage that the controller of a servo motor can output increases, and that the voltage saturation at high-speed revolution of the motor gets to hardly occur, and this can make it hard to cause torque shortage. |
