| 摘要 |
PURPOSE:To control current stably and smoothly by providing an observation means for observing the DC current at the AC input terminal side of an inverter and a control means for turning on a transistor for regeneration when an observation voltage nearly exceeds the value which should be observed while a servo motor is being loaded. CONSTITUTION:Two input terminals of an A/D converter 14 are connected to two conductors P and N which allow main circuit DC current to flow and the main circuit DC voltage of an inverter 6 is observed. Then, when a CPU 15 allows the main circuit DC voltage to be input from the A/D converter 14 and the main circuit DC voltage is higher than a value which should be observed mostly when a servo motor 13 is not loaded, a transistor 5 for regeneration is turned on for discharging voltage which is charged to a capacitor 3 and at the same time all thyristors of a thyristor bridge 2 are turned off, thus reducing the main circuit DC voltage. On the other hand, when the main circuit DC voltage is low, the CPU 15 turns on each thyristor of the thyristor bridge 2. |
