| 摘要 |
PURPOSE: To suppress the speed variation and DC voltage fluctuation a motor caused by a rapid change of a load, by making the upper limit value of a torque reference of a motor zero immediately after the detection of a rapid decrease of the load, and making the lower limit value zero immediately after the detection of a rapid increase of the load. CONSTITUTION: When a load 6 has decreased rapidly, a speed feedback SP-F increases first. The speed increase at this time is generated as the load, torque before the rapid decrease of the load changes into accelerating torque of the motor due to the rapid decrease of the real load. Accordingly, it is necessary not to output positive-side torque immediately after a rapid decrease of the load is detected. So, it becomes possible to prevent a motor from overspeeding by setting the upper limit value of a torque limit to zero by the use of a rapid load change processing circuit 28 immediately after the detection of a rapid decrease of the load by a rapid load change detecting circuit 27, and preventing acceleration torque from being generated. This is also identical in the case where the load increases rapidly, and it becomes possible to suppress speed variation at the time of a rapid load change. |
