| 摘要 |
PURPOSE:To detect the position of the changeover of excitation precisely by chopping supply currents to a armature winding for the whole conduction period while the terminal voltage of the armature winding generated as the result of the chopping is inputted to a position detecting circuit through a sampling hold circuit. CONSTITUTION:Transistors T1-T6 in an inverter 1 are controlled by a speed control circuit 5. The speed control circuit 5 is constituted of a chopper-signal generating circuit 51 and an AND circuit, and the transistors T1-T6 are controlled so that supply currents to an armature winding are chopped for the whole conduction period. The terminal voltage of the armature winding is sampling-held by a sampling hold circuit 6, and inputted to a position detecting circuit 3, thus detecting the position of the changeover of excitation. |
