JPH0291576A - Ac current detector - Google Patents

Abstract

PURPOSE:To reduce a detecting error due to the change of ambient temperature by providing a diode for temperature compensation in an A/D conversion reference electric-potential circuit of a microcomputer. CONSTITUTION:An AC current flowing in an electric-wire 3 is converted into an DC voltage corresponding to an AC current value by CT 2, a load resistance 9, a diode 10 for rectifying and a smoothing capacitor 11. And, the DC voltage is divided to a partial voltage below an A/D reference electric potential of a micro-computer 8 by partial voltage resistances 21, 22 and a semi-fixed resistor 23 for adjustment, and inputted into an analog input terminal 81 of the microcomputer 8. On the other hand, for the reference electric potential terminal 83 for A/D conversion of the microcomputer 8, the voltage of a DC power source 15 is divided to the partial voltage by resistances 24, 25 and a diode 26 for temperature compensation and is allotted. Here, as the diode 26 for temperature compensation is constituted of a diode 10 for rectifying and a double diode, a temperature characteristic which is an order characteristic of the diode 26 for temperature compensation pursues the temperature characteristic which is the order characteristic of the diode 10 for rectifying. By this method, the detecting error due to the change of the ambient temperature of a CT detector is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an alternating current detection device using an alternator.

[Conventional technology]

Figure 2 shows, for example, a flow detection system (I
C (hereinafter referred to as OT detection device) in Figure 9 (3)
is 'a111il' where an alternating current is flowing! .

(2) is the current transformer (hereinafter referred to as OT) attached to the electric wire (3), (9) t'i the UT 12++7) load resistance, auh rectifier diode, Qljt'! Smooth capacitor, Q41 is a resistor. (8) It is a microcomputer, and αS is Rin! It is a power source.

Next, the operation will be explained.

'[# +3) father mn0T(2+,
Load g resistor (9), rectifier diode Q (1, ten beak capacitor α11 converts into DC voltage according to the AC current value. Then, the DC voltage is divided by voltage dividing resistor qυca, a
Microcontroller (81 A/
The voltage is divided below the D reference potential and input to the analog input terminal (81) of the microcomputer (8).

On the other hand, the A/D conversion reference potential terminal (83) of the microcomputer (8)
) is provided with the voltage of the DC power supply u5 divided by the resistors (2) (2) and the temperature compensation diode (to).

Here, the temperature sleeve customary diode Ca is! 1. Rukawa diode (consisting of IG and double diode, &&
Since the temperature characteristic of the ML characteristic of the seismic intensity compensation diode (2) follows the temperature characteristic of the forward characteristic of the rectifying diode a, detection errors due to changes in the ambient temperature of the OT detection device can be significantly reduced.

[Problem to be solved by the invention]

Since the conventional OT detection device is constructed as described above, a problem frequently arises in that detection errors caused by individual temperature characteristics of each component are not taken into consideration. In particular, the ++* characteristics of rectifier diodes are greatly affected by ambient temperature and are a major factor in detection errors.

This invention was made to solve the above-mentioned problems, and is a device that can reduce errors caused by rectifying diodes, which have the best warm-summer characteristics among all the components! The purpose is to obtain c.

[Means to solve the problem]

AC 1 according to this invention! The current detection device converts the alternating current into a direct current voltage according to the alternating current value, inputs the direct current voltage to the microcomputer, and uses the A/D conversion function of the microcomputer to convert the current value to the above 9. In the identified device, a temperature compensation diode is provided in the A/D conversion reference potential circuit of the microcomputer.

[For production]

AC 1 in this invention! The current detection device reduces detection errors by causing the forward characteristic of the temperature compensation diode to completely follow the change in the j-circular characteristic of the 1i diverting diode due to a change in ambient temperature.

〔Example〕

The entire drawings of an embodiment of the present invention will be described below.

In Figure 1, (3) is one line through which alternating current flows;
(2) is aq' installed on this 'RL line (3).

(9) is the load resistance of 0'r (21, QIHV current diode, α11 is the smoothing capacitor, &DΩ is the voltage dividing resistor, Ω is the semi-fixed resistor for adjustment connected in series with the voltage dividing resistor @) The vessel is ruru.

(8) is a microcomputer, (81) is an analog input terminal of the microcomputer (8), (82) is an analog ground terminal, and (83) is an A/D conversion reference potential terminal. Also, O5 is DC 1! It is the source.

Set f, '41C5 is resistance, Ci! e is a temperature-axis conventional diode, and these are connected in series to create a direct current image a
5 and the analog ground terminal (82), and the A/D conversion reference potential terminal (83) is inserted between the connection point of the resistor @ (to).
)It is connected to the. Here, the rectifying diode Ql) and the m-degree compensating diode (to) are integrally constituted by a diode (27).

Incidentally, in the above embodiment, a case has been described in which the microcomputer (8) has an A/D conversion function.

The same effect as in the above embodiment can be achieved by using a comparator and an operation unit.

Next, the operation will be explained.

The alternating current flowing through t Iwao (31 is (,!T(2+, load resistance (9)K) converts the alternating current '! into an alternating current direct voltage according to the flow, and the cough alternating current voltage is applied to the next stage!!l! The diode Ql and the smoothing capacitor (IIIK convert it into direct current.

This DC voltage is then input to the analog input terminal of the microcomputer (81). In this way, the microcomputer (81) inputs the DC voltage corresponding to the magnitude of the alternating current flowing through the electric wire (3) from all analog input terminals, and (8) A/D in
The conversion function identifies the AC flow value.

〔Effect of the invention〕

According to this invention, the AC'fL flow is adjusted to the recommended value of the AC'ton, ! In the device that converts the AC voltage #L value into voltage, inputs it to the microcomputer, and uses the A/D conversion function of the microcomputer to identify the AC voltage #L value, temperature is stored in the A/D conversion reference potential circuit of the microcomputer. 1 in configuration with compensation diode
9. It is possible to obtain a detection error with less error due to changes in ambient temperature.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of a 7417 example of current transformer according to the present invention, and Figure 2 is a circuit diagram of a conventional current transformer.
This is a flow detection circuit diagram. In the figure, (8) is a microcomputer, and (to) is a temperature-axis conventional diode. In addition. In the figure. The same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] In an alternating current detection device that converts an alternating current into a direct current voltage according to the alternating current value, inputs the direct current voltage to a microcomputer, and identifies the alternating current value by the A/D conversion function of the microcomputer, the microcomputer's A An alternating current detection device comprising a temperature compensation diode in a /D conversion reference potential circuit.