| 摘要 |
<p>When a supply current of an excitation coil is cut off at the end of a position detection signal, the high magnetic energy stored in the excitation coil is prevented from flowing back to the power source side by reverse blocking diodes (43a, 43b) and consequently caused to flow forcedly into an excitation coil to which the power is to be next supplied. Accordingly, the extinguishing time of the magnetic energy in the excitation coil of the preceding stage is shortened, and accumulation of the magnetic energy in the excitation coil of the succeeding stage can be accelerated. Therefore, a high speed (up to about 100,000 rpm) rotation can be obtained while keeping the feature of high torque. If a plurality of teeth that are used customarily for magnetic poles are disposed, the output torque can be multiplied at an ordinary rotational speed. Since a chopper circuit operates when the operation mode is changed to the reverse rotation mode from the forward revolution, the voltage applied to the excitation coil becomes the sum of the D.C. power source voltage and the counter electromotive force. Accordingly, the rise of the excitation current becomes sharp. When the excitation current reaches a current of a set value, the supply of power is cut off. The reduction of the magnetic energy stored in the excitation coil becomes slow. In this period, the power flows into the power source by transistors connected in parallel with the reverse blocking diodes (43a, 43b) respectively to regenerate power. Accordingly, regenerative braking can be made.</p> |
