| 摘要 |
PURPOSE:To secure a torque at low speed by setting characteristics of a speed feedback circuit to broken line-shaped characteristics. CONSTITUTION:A speed signal 1 is converted into a voltage by an F/V converter 2 to obtain a revolution signal Va. An offset circuit 3 outputs a signal when the revolution signal Va reaches a given voltage. An inverting amplifier circuit 4 inverts the output of the offset circuit 3 into Vb on the basis of the revolution signal Va and amplifies Vd to output a voltage Vc. A differential amplifier circuit 5 outputs a deviation signal Vd between the output Vc of inverting amplifier circuit 4 and a speed control voltage Vref determined by a speed regulating variable resistor 6. Further, a comparison PWM circuit 8 compares a reference triangular wave outputted from a reference triangular wave generator circuit 7 with the deviation signal Vd to output PWM pulse to a control circuit 9. In this manner, it is possible to secure a torque at low speed. |
