| 摘要 |
PURPOSE:To reduce the 2nd higher harmonic wave ripple produced to the output of a multiplier by subtracting a current equivalent to the semi-steady component of the reactive power out of the current signal of the multiplier that produces the instantaneous value of the reactive power. CONSTITUTION:The 90 deg. phase-delayed waveform of voltage is multiplied by a load current through a multiplier X4 for generation of the reactive power. The 2nd higher harmonic wave contained in the reactive power is deleted by an LPF2 and smoothed. In this case, a long time constant of about one - several sec is selected for the characteristics of the LPF2 and the therefore the fluctuation component of the reactive power is averaged and not shown. Thus the semi-steady reactive power is obtained. A waveform which has a 90 deg. phase delay compared with the voltage waveform and is proportional to the semi- steady reactive power value means a current component corresponding to the semi-steady component of the reactive power. Thus the amplitude of the current supplied to a multiplier X1 can be reduced by subtracting said current component out of the current signal of the multiplier X1 which produces the instantaneous value of the reactive power. Then the 2nd higher harmonic wave ripple contained in the output of the multiplier X1 can be reduced.
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