JPH0624775Y2 - Phase angle / power factor signal converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention provides a voltage or current signal proportional to a phase angle (φ) to a signal corresponding to a power factor (cosφ) (not a signal proportional to the power factor. The present invention relates to a phase angle / power factor signal converter that converts a power factor into a signal that can be easily known based on the signal; hereinafter referred to as a power factor signal).

(Prior Art) In order to know the operating state of a load, it is also useful to know the voltage V applied to the load and the current I and power P flowing through the load, as well as the phase angle φ between the voltage V and the current I, the power factor cosφ, and the like. .

The phase angle φ is 0 when the voltage V and the current I are in phase, but the polarity changes depending on whether the current I leads or lags the voltage V. On the other hand, the power factor cosφ is irrelevant to the polarity of the phase angle φ. For this reason, it is impossible to determine whether it is the leading power factor lead or the lagging power factor lag with respect to the same power factor amount, simply from the signal indicating the power factor cosφ. Therefore, Japanese Patent Publication No. 49-23222 discloses a device for obtaining a power factor amount having a polarity indicating a lead power factor or a lag power factor.

The device described here is composed of a series (parallel) circuit of a Zener diode and a resistance element to obtain a DC signal corresponding to the amount of power factor, and the phase of the AC current advances with respect to the phase of the AC voltage. Or a delay, and a circuit for converting a DC signal corresponding to the power factor amount into a DC signal having a polarity corresponding to the advanced power factor or the delayed power factor by a detection signal from the detection circuit. ing.

(Problems to be solved by the invention) The conventional device having such a configuration has a circuit for detecting whether the phase is advanced or delayed, and the polarity of the power factor amount according to the detection signal from the detection circuit. However, there is a problem that a circuit is required to change the configuration, the configuration is complicated, and the total price is high. Further, the output becomes discontinuous at the phase angle φ = 0 ° as shown in FIG. 4, and the data of the discontinuous portion is discontinuous in the data processing in the device such as the data logger connected to the latter stage of this device. There was a problem because it was stable.

The present invention has been made in view of these problems,
The purpose is to realize a conversion device that has a simple configuration and is capable of converting a phase angle signal into a continuous power signal that is also a power factor signal with a polarity indicating whether it is a leading power factor or a lagging power factor. To do.

(Means for Solving Problems) The present invention for solving the above problems is an absolute value circuit that inputs a signal proportional to a phase angle φ and outputs an absolute value signal, and an absolute value circuit from this absolute value circuit. A multiplier for multiplying the value signal and the signal proportional to the phase angle φ to obtain a signal corresponding to the power factor cosφ.

Embodiment An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a conceptual diagram of the configuration of the device of the present invention. In the figure, reference numeral 1 is a signal V _Y proportional to the phase angle φ (see FIG. 3 (a)), and a signal V proportional to its absolute value.
An absolute value circuit 2 for outputting _X is an analog multiplier, which multiplies the absolute value signal V _X from the absolute value circuit 1 by a voltage signal V _Y proportional to the phase angle φ, and outputs a power factor cos φ at the output end. To obtain a signal E ₀ corresponding to.

Here, φ (DEG) is 1 every 2 ° in the range of 0 to + 60 °.
Table 1 shows the values obtained by calculating the error of φ ² with respect to −COSφ. In this case, when φ = 60 °, y = 1-COS
The value of a is determined by the following equation (1) so that φ is equal to y = a · φ ² .

a = [(1-COSφ) / φ ² ] = 1.38889 × 10 ⁻⁴ [DEG] …… (1) As is clear from Table 1, the maximum error is when φ = 42 °
It becomes 0.011855. Therefore, the maximum error can be regarded as about 0.01. Although Table 1 is for the range of 0 to + 60 °, the same is true for the range of -60 ° to 0.

In the device of the present invention, 1-cos φ and φ ² are −60 ° to +6.
Focusing on the point that there is only about 0.01 difference in the range of 0 °, the analog multiplier 2 multiplies the voltage signal V _Y proportional to the phase angle φ and its absolute value signal V _X, and is proportional to φ ² . The power factor signal (1-cosφ)
It is what

With the configuration shown in FIG. 1, when the phase angle signal V _{Y has a} positive (+) polarity, the absolute value signal V _X also has a positive polarity, so that the multiplier 2 outputs a positive polarity φ ² (+ Φ ² ),
Therefore, the output signal E ₀ approximated to the power factor 1-cosφ is obtained, and this becomes the (positive) power factor signal in the lead region.
When the phase angle signal V _Y has a negative (−) polarity, the absolute value signal V _X has a positive polarity, and therefore the multiplier 2 has a negative polarity and φ.
² (−φ ² ), and thus an output signal E ₀ approximated to the power factor cos φ−1 is obtained, which is the (negative polarity) power factor signal in the lag region. Therefore, the power factor signal as shown in FIG. 3B can be obtained with a simple configuration. Also, the conversion accuracy is 1-
As described above, between cos φ and φ ² is −60 ° to +60.
In the range of °, there is only a difference of about 0.01, so it can be increased. Further, conversion can be performed within an allowable limit even outside the range described above.

FIG. 2 is a concrete circuit diagram showing an example of the device of the present invention. In this embodiment, the absolute value circuit 1 uses a known one composed of an operational amplifier OP ₁ having a diode D ₁ in a feedback circuit and an amplifier OP ₂ having the output of the operational amplifier OP ₁ as an input. There is. The multiplier 2 uses a commercially available IC (NJM4200 manufactured by New Japan Radio). The output signal from the multiplier 2 is output as a power factor signal through a circuit including an operational amplifier OP ₃ for adjusting the zero point and the span value.

In the above description, the case where the voltage signal V _Y proportional to the phase angle φ is input is described as an example, but the current signal proportional to the phase angle φ may be input.

(Effect of the Invention) As described in detail above, the device of the present invention can be configured by the absolute value circuit and the multiplier, and thus has a simple configuration. Moreover, a continuous power factor signal can be obtained, and it is possible to know whether the power factor is advanced or delayed. Also, since the signal corresponding to the power factor (cosφ) is approximately obtained by squaring the phase angle (φ), it is possible to accurately convert the phase angle signal into the power factor signal in a specific phase angle range. You can

[Brief description of drawings]

FIG. 1 is a conceptual diagram of the device of the present invention, FIG. 2 is a concrete circuit diagram showing an embodiment of the device of the present invention, and FIG. 3 is a diagram showing an input V _Y and an output E ₀ in the device of the present invention, FIG. 4 is a diagram showing the relationship between the phase angle signal and the power factor signal in the conventional device. 1 ... Absolute value circuit, 2 ... Analog multiplier

Claims (1)

[Scope of utility model registration request] 1. An absolute value circuit for inputting a signal proportional to a phase angle φ and outputting an absolute value signal thereof, and an absolute value signal from the absolute value circuit multiplied by a signal proportional to the phase angle φ. A phase angle / power factor signal conversion apparatus including a multiplier that obtains a signal that approximates to the power factor cosφ and that includes information for determining whether the power factor is the advanced power factor or the delayed power factor.