| 摘要 |
PURPOSE:To improve the high-speed follow-up performance of a current controller by converting a coil current into a digital signal and giving such processes to the digital signal as addition/subtraction, smoothing of exponent, amplification, delay, etc. CONSTITUTION:The current (i) of a coil 1 is turned into a digital signal by an A/D converter 6 with a cycle decided as a reciprocal of the product of the frequency of an AC power supply and the effective phase number. Then said current digital value is subtracted from the current set value (r) supplied in the form of a digital signal. This deviation is integrated by an integrator 8, and at the same time the exponent smoothing is applied to the deviation through an exponent smoother 9. These sum value is amplified and converted into an analog signal by a D/A converter 11. This analog signal is used as a firing angle. The parameters for exponent smoothing and amplification are selected properly from the coil constant, said cycle, the upper limit of the time needed for those digital operations, etc. Thus the current control is possible in the shortest time or in the time little longer than the shortest time. |
