PURPOSE: To positively give attenuation to a system to be controlled by providing a phase shift means connected in series with a compensation means, whose synthesized frequency characteristic has a phase lead characteristic at a predetermined frequency band and having a predetermined amplification factor to the controller.
CONSTITUTION: A phase shift circuit 9 is provided between a converter 4 and a compensation circuit 5, the compensation circuit 5 receiving an output of the circuit 9 implements PID or phase lead/lag arithmetic operation, and a power amplifier 7 controls a supply current to an electromagnet 3 based on signal divided positively and negatively by a positive/negative signal selector 6. For example, the phase shift circuit 9 adds a signal passing through a band pass filter 10 and an amplifier 11 to an input signal. Through the constitution of the phase shift circuit 9 above, a full band pass filter is obtained, in which a phase characteristic is steeply changed in the vicinity of a center frequency of the band pass filter. Thus, A phase lead or a phase lag is easily provided at a frequency in the vicinity of the vibration mode by setting a center frequency of the band pass filter in the vicinity of a harmonic vibration mode frequency in a state quantity to provide a large dumping torque.
FUKUSHIMA YASUO
HIROSHIMA MINORU
