| 摘要 |
PURPOSE:To eliminate the unnecessary torque loss and abnormal vibration of a brushless motor by controlling via a switching mode power source the collector vs. emitter voltage of an output transistor to become the prescribed current amplification factor capable of being predetermined by a resistor. CONSTITUTION:Assume that the only transistors Q3, Q4 of output transistors Q1-Q3 are conducted by the positional relation between a rotor 1 and an armature winding 3. Since the hFE of the Q4 varies in response to the collector vs. emitter voltage, the collector vs. emitter operation voltage of the Q4 when the loop gain of a negative feedback loop via a differential amplifier 20, a low pass filter 21, a position signal converter 5, Q3, windings L1, L3, Q4, and resistor 13 are sufficiently high are automatically determined, the hFE becomes constant, and the current amplification factor is maintained constantly. On the other hand, the Q3 is similarly operated to automatically determine the collector vs. emitter operation voltage of the Q3 when the loop gain of the negative feedback loop via a differential amplifier 24, a low pass filter 25, a switching mode power source 26, Q3, windings L1, L3, Q4, and resistor 13 is sufficiently high, and the hFE of the Q3 and the current amplification factor become constant. |
