| 摘要 |
PURPOSE:To save the waste of electric power by reducing the base current of a power transistor as the temperature of the transistor becomes high. CONSTITUTION:The bases of power transistors PT1, PT2 of a transistor chopper circuit 4 are connected to the emitters of a transistor TR1 controlled ON or OFF by a current flowing rate control circuit 6. A voltage regulator 10 controls the ON and OFF times of a transistor TR2 in response to the deviation between the instruction voltage V2 and the voltage V1 of a capacitor C1. An operational amplifier OP3 outputs a current reference signal proportional to the base and emitter voltages of a transistor TR3 responsive to the temperatures of power trnsistors PT1, PT2. An operational amplifier OP3 controls the instruction voltage V2 responsive to the deviation between the current reference signal and the current detection signal. |
