| 摘要 |
PURPOSE:To achieve a highly accurate power converting operation, by converting an analog voltage sampled and held with a sample hold amplifier to a digital signal directly to be computed with an arithmetic unit. CONSTITUTION:Two output voltages of e+Ki and e-Ki are obtained across resistances 3a and 3b from a voltage (e) obtained at a voltage transformer 1 and two currents (i) from a current transformer 2A. These voltages of e+Ki and e-Ki are sampled with a sampling and hold amplifier 4 at a proper timing and held. Then, the two voltage e+Ki and e-Ki are converted into a digital value with a digital conversion means 5A, the output of which is applied to a micro-arithmetic unit 6A, the instantaneous value thereof is memorized and stored during one cycle. The value data obtained here is used to perform a section quadrature by a specified integration formula, employing sampled value when the e+Ki and e-Ki give the same code values to obtain a desired totalized power value. In this manner, the use of universal circuit parts enables a highly accurate power converting operation.
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