| 摘要 |
A charging contactor and charging resistor of a capacitor battery in a prior art intermediate circuit of a frequency converter are replaced with three semiconductor switches connected between a three-phase voltage supply and a capacitor battery. When the frequency converter is connected to a supply network, the three semiconductor switches are arranged to operate at first in a current regulating mode in order to charge the capacitor battery using a regulated charging current until the voltage of the capacitor battery reaches a predetermined level. After this, the three semiconductor switches are directed to operate in a diode bridge mode in parallel with an actual network inverter, thus providing a second rectification branch. In a preferred embodiment of the invention, each semiconductor switch comprises a diode and a series connection of a gate-triggered component, preferably a thyristor. |
