| 摘要 |
PURPOSE:To prevent a drive power factor of a field chopper from decreasing by weakening a branch coil current during the receiving of a cam shaft advancing signal in case that a drive command is received when a signal which represents higher than set speed is received from a speed detector. CONSTITUTION:A field chopper 11 of an electric motor vehicle is controlled upon reception of a cam shaft advancing signal from a resistance cam shaft advancing detector 13, a signal from a normally open contact 15a of a speed detecting relay 15 and a drive command signal. The relay 15 is operated by the output from a speed detector 16. When the speed of th vehicle is higher than the set value, the detector 16 operates the relay 15, and a signal which represents higher than the set speed value is applied to a chopper 11. When a drive command is outputted in this state, a cam shaft starts rotating, but the chopper 11 operates to weaken the branch field current under the condition of a logic product of the above three signal. Thus, the cam shaft is advanced when an armature electromotive force is low and an armature current is large. A danger that the armature current during the can advancing period becomes minus is less, and the OFF of a main circuit becomes less. |
