| 摘要 |
PURPOSE:To improve time limit characteristic and to simplify a protective circuit by selecting and setting a control signal from actually measured characteristics of semiconductor control elements corresponding to the load. CONSTITUTION:Semiconductor control elements, i.e. IGBT(Insulated Gate Bipolar Transistor) 1a-1f convert power fed from a DC power source into AC power and drives a motor 13. Relation between collector-emitter voltage VCE of the IGBT1a-1f and the collector current IC is previously measured with the gate voltage VGE being employed as a parameter, and the load current IC(max) for the maximum load is obtained previously. Then a current larger by IC than the load current IC(max) is obtained and a gate voltage VGE where the voltage VCE increases abruptly is obtained and employed for control of the IGBT1a-1f. By such arrangement, load current can be limited. |
