| 摘要 |
PURPOSE:To eliminate uncontrolled state under low displacement detection signal by operating the proper gap on the basis of a rotary angle detection signal obtained from the detection signal of a gap detector and a swing amplituide detection signal passed through lowest amplitude compensator. CONSTITUTION:PLL unit 3 is comprised of multipliers 36, 37, adders 38, 39, an amplifier 32, rotor rotation command frequency transmitter 35 and two-phase oscillator 34. While an amplitude operating unit 5 is comprised of two multipliers 51, 52, an adder 53, a sign inversion amplifier and a lowpss filter 55. The input signal DELTAdeltasintheta for the amplifier 32 in PLL unit 3 is brough to 0 through PLL 3 while the input signal DELTAdeltacostheta for the lowpass filter 55 is also brought to 0, thereby DELTAdeltacostheta will be DELTAdelta, to produce only the swing amplitude. In the invention, a lowest amplitude compensator 13 is provided before PLL unit 3. |
