| 摘要 |
PURPOSE:To eliminate a tachometer generator and a pulse oscillator by obtaining a pulse signal from a rotor groove harmonic voltage contained in induced power and obtaining a speed signal by the magnitude of the induced electromotive force. CONSTITUTION:A mode discriminator 24 outputs a mode 1 signal in the induced electromotive force output range, and a mode 2 signal in the motor operation range. An induced electromotive force sampling-hold circuit 25 samples the induced electromotive force by the mode 1 signal and outputs a speed signal. A comparison discriminator 27 compares the output signal of the circuit 25 with a signal having a rotor groove harmonic number from a low order pulsation removing filter 26 and outputs a pulse signal. A frequency sampling hold circuit 28 produces a pulse proportional to the speed N of the motor from the rotor groove harmonic frequency in the period that the mode 2 signal is outputted, and applies it to a digital control circuit 30. |
