| 摘要 |
An auxiliary commutation circuit for an inverter comprises a pair of oppositely charged capacitors (56, 58) controlled by separate switches (60, 62), each operable at a particular time during the conduction cycle of the main thyristors (14, 16) to provide additional stored energy for commutation during overcurrent conditions. A current detector (78) senses the load current and provides a signal to an auxiliary gate (68) whenever the rate of change in the load current or its absolute magnitude exceeds a preselected value. In response to the overcurrent signal and a timing signal, the auxiliary gate (68) renders the appropriate switch operative coupling the charged auxiliary capacitor in parallel with the primary commutation capacitor (52) so that the combined electrical energy stored on both capacitors is available for commutation. After the commutation period the auxiliary gate (68) maintains the switch in its open state for a sufficient period of time to allow the auxiliary capacitor to be recharged. |
