| 摘要 |
PURPOSE:To minimize the switching loss of a chopper transistor at the low speed rotating time of a motor by controlling a triangular or sawtooth wave oscillator for generating a switching pulse with a frequency signal proportional to the rotating speed of the motor. CONSTITUTION:The AC voltage output of an AC tachometer ganerator (TG) 2 is full-wave rectified, is then wave-form shaped, and the oscillation frequency of an oscillator 5 is controlled with the frequency of the shaped output to produce a triangular or sawtooth wave synchronized with the feedback frequency of the TG 2. A comparator 6 compares the triangular or sawtooth wave outputted from the oscillator 5 with a speed deviation signal outputted from a deviation amplifier 4, and the switching pulse having a duty factor responsive to the rotating speed is applied to a chopper power transistor drive circuit 7. |
