| 摘要 |
PURPOSE:To simplify the structure of an armature current detector by supplying variable DC power controlled in phase for AC power to a DC electric machine through a rectifier. CONSTITUTION:A rectifier D is connected between voltage phase control means 3 and a DC motor 2. Induction electromotive force detecting means 11 receives a voltage signal a generated at the cathode side of a rectifier D and a voltage signal b generated at the anode side, and outputs as the induction electromotive force signal d of a DC motor 2 the voltage signal a under the condition that there is a potential difference between the voltage signals a and b and the voltage signal b is zero. Arithmetic means 15 outputs a signal proportional to the armature current by reducing the signal a and the signal d therefrom. The output of the means 15 is applied to the phase control circuit 10 of the means 3 through a current control amplifier 16. In this manner, the armature current can be detected without providing a shunt or a DC current transformer in a main circuit. |
