KR102371225B1 - Isolation DC Voltage Measurement Device By Using Photocoupler - Google Patents

Abstract

The present invention relates to an insulated DC voltage measuring device using a photocoupler, and more particularly, to an input power source, an optical signal transmitter connected to the input power source to receive a first current supplied by the input power source, and emit an optical signal; A photocoupler including an optical signal receiver for receiving a signal and generating a second current, and a photocoupler connected in parallel with an output terminal of the photocoupler to receive the second current generated by the photocoupler and convert it into a voltage to be measured resistance may be included.
Therefore, according to the present invention, the insulated voltage can be accurately measured without a differential amplifier by setting the ratio of the voltage to be measured using the characteristic that the current transfer ratio is proportional to the photocoupler in a certain range according to the specifications of the photocoupler, 1 By calculating the range of current applied to the resistance of the secondary side, the current can be induced in the secondary side, so that the voltage can be continuously measured without the need for an auxiliary sequence circuit. device can be implemented.

Description

Isolation DC Voltage Measurement Device By Using Photocoupler

The present invention relates to an insulated DC voltage measuring device using a photocoupler, and more particularly, to an input power source, an optical signal transmitter connected to the input power source to receive a first current supplied by the input power source, and emit an optical signal; A photocoupler including an optical signal receiving unit for receiving a signal and generating a second current, and a photocoupler connected in parallel with an output terminal of the photocoupler to receive the second current generated by the photocoupler and convert it into a voltage to be measured resistance may be included.

Insulated DC voltage measurement refers to the method of measuring the voltage of one circuit in another circuit that is insulated from each other.

When measuring the existing insulated DC voltage, the measurement method using Isolation Op-Amp is used, or when there is a primary circuit and a secondary circuit insulated from each other as shown in FIG. 1, in order to measure the voltage on the primary side, The insulated primary voltage was derived by placing a capacitor on the car side and measuring the voltage charged in the capacitor by charging or discharging the capacitor using an insulated photoswitch.

However, when measuring the insulated voltage using the existing Isolation Op-Amp, the voltage must be amplified using a differential circuit and then measured. There is a problem that there is no choice but to limit to 2V.

In addition, in the case of measuring the insulated voltage using the photoswitch as shown in FIG. 1 , a capacitor capable of temporarily storing the voltage in the photoswitch is required. In addition, a sequence control to turn on/off the photoswitch is required separately, and an Op-Amp that controls the voltage charged in the capacitor is additionally required because the correct primary voltage can be measured only when the correct voltage is read the moment the capacitor is charged. Therefore, there is a problem in that the circuit configuration is complicated, the manufacturing process is complicated, and miniaturization is difficult.

The present invention was invented based on this technical background, and it was invented to satisfy the technical needs salpinned above, as well as provide additional technical elements that a person of ordinary skill in the art cannot easily invent.

The present invention has been devised to solve the above-mentioned problems, and by using the characteristic that the current transfer ratio is proportional to the photocoupler in a certain range, the ratio of the voltage to be measured is set according to the specifications of the photocoupler, so that the insulated voltage without a differential amplifier The purpose is to accurately measure

In addition, the present invention can induce a current in the secondary side by calculating the range of current applied to the resistance of the primary side, so that an auxiliary sequence circuit is not required and the voltage can be continuously measured, simplifying the circuit and accurate It aims to implement a device capable of measuring insulation voltage.

In addition, an object of the present invention is to enable measurement in an electrically isolated state during voltage measurement to safely measure voltage even where a large voltage flows.

In addition, the present invention is electrically insulated by a photocoupler and the signal is transmitted by an optical signal, so the effect of noise is small. aim to

In order to achieve the above object, an insulated DC voltage measuring apparatus using a photocoupler of the present invention is an input power source, and an optical signal transmitter connected to the input power source to receive a first current supplied by the input power source and emit an optical signal. , a photocoupler including an optical signal receiving unit generating a second current by receiving the optical signal and connected in parallel with an output terminal of the photocoupler to receive and measure the second current generated by the photocoupler It may include a conversion resistor that converts it to a voltage.

In this case, the optical signal receiver may generate a second current having a current transfer ratio proportional to the first current. In addition, it may be characterized in that the input power and the voltage applied to the conversion resistor are proportional.

In addition, the present invention may further include a voltage divider connected in parallel with the input power source and the photocoupler, dividing the voltage of the input power supply to the photocoupler, and the voltage dividing unit is a first resistor connected in series to the input power source. and a second resistor and a first capacitor connected in parallel to the first resistor, wherein the photocoupler is connected in parallel to the first capacitor.

In addition, the present invention is a first amplifier including a (+) input terminal connected to the output terminal of the photo coupler, an output terminal for converting the second current to a voltage to be measured and output, and a (-) input terminal connected to the first node and a voltage converter comprising It may be characterized in that it is connected to a third noise removing unit connected to, wherein the first noise removing unit and the second noise removing unit have a resistor and a capacitor connected in series or in parallel, and the third noise removing unit includes a resistor and It may be characterized in that the capacitors are connected in parallel.

In addition, the present invention further comprises an amplifier comprising a second amplifier connected in parallel to the output terminal of the voltage converter to amplify the voltage converted by the voltage converter, wherein the second amplifier is a non-inverting amplifier or an inverting amplifier In addition, it may be characterized in that the input power and the voltage applied to the output terminal of the amplifying unit are proportional.

In the present invention, the insulated voltage can be accurately measured without a differential amplifier by setting the ratio of the voltage to be measured according to the specifications of the photocoupler by using the characteristic that the current transfer ratio is proportional to the photocoupler in a certain range.

In addition, the present invention can induce a current in the secondary side by calculating the range of current applied to the resistance of the primary side, so that an auxiliary sequence circuit is not required and the voltage can be continuously measured, simplifying the circuit and accurate A device capable of measuring insulation voltage can be implemented.

In addition, the present invention can measure the voltage safely even in a place where a large voltage flows because it is possible to measure the voltage in an electrically isolated state.

In addition, the present invention is electrically isolated by a photocoupler and transmits a signal by an optical signal, so the effect of noise is small. can

1 is a circuit diagram showing a circuit configuration for measuring an insulated DC voltage using a photoswitch according to the prior art.
2 is a block diagram illustrating a functional block of an insulated DC voltage measuring apparatus using a photocoupler according to an embodiment of the present invention.
3 is a circuit diagram using a non-inverting amplifier in an insulated DC voltage measuring apparatus using a photocoupler according to an embodiment of the present invention.
4 is a circuit diagram using an inverting amplifier in an insulated DC voltage measuring apparatus using a photocoupler according to an embodiment of the present invention.
5 is a reference diagram for explaining the configuration of a noise removing unit of an insulated DC voltage measuring apparatus using a photocoupler according to an embodiment of the present invention.
6 is a reference diagram for explaining the characteristics of a section in which a transfer current ratio of a photocoupler is proportional to an input current.
7 is a reference diagram for measuring voltages output from each section of a circuit of an insulated DC voltage measuring apparatus using a photocoupler according to an embodiment of the present invention.

The purpose and technical configuration of the present invention, and details regarding the operational effects thereof will be more clearly understood by the following detailed description based on the accompanying drawings in the specification of the present invention. An embodiment according to the present invention will be described in detail with reference to the accompanying drawings.

The embodiments disclosed herein should not be construed or used as limiting the scope of the present invention. It is natural for those skilled in the art that the description including the embodiments of the present specification will have various applications. Accordingly, any embodiments described in the detailed description of the present invention are illustrative for better describing the present invention and are not intended to limit the scope of the present invention to the embodiments.

The functional blocks shown in the drawings and described below are merely examples of possible implementations. Other functional blocks may be used in other implementations without departing from the spirit and scope of the detailed description. Also, although one or more functional blocks of the present invention are represented as separate blocks, one or more of the functional blocks of the present invention may be combinations of various hardware and software configurations that perform the same function.

In addition, the expression that includes certain components is an open expression and merely refers to the existence of the corresponding components, and should not be construed as excluding additional components.

Furthermore, when a component is referred to as being connected or connected to another component, it may be directly connected or connected to the other component, but it should be understood that another component may exist in the middle.

In addition, expressions such as 'first, second', etc. are used only for distinguishing a plurality of components, and do not limit the order or other characteristics between the components.

1 is a circuit diagram showing a circuit configuration for measuring an insulated DC voltage using a photoswitch according to the prior art.

Referring to FIG. 1 , in the method of measuring an insulated DC voltage using a photoswitch, a capacitor is placed on the secondary side to measure the voltage on the primary side when there is a primary circuit and a secondary circuit insulated from each other. Measure the insulated primary voltage using the charged or charged capacitor in the capacitor by using a photoswitch.

However, in the case of measuring an insulated voltage using a photoswitch, a capacitor capable of temporarily storing the voltage in the photoswitch is required. In addition, a sequence control to turn on/off the photoswitch is required separately, and an Op-Amp that controls the voltage charged in the capacitor is additionally required because the correct primary voltage can be measured only when the correct voltage is read the moment the capacitor is charged. Therefore, there is a problem in that the circuit configuration is complicated, the manufacturing process is complicated, and miniaturization is difficult.

2 is a view showing a functional block of an insulated DC voltage measuring apparatus 100 using a photocoupler according to an embodiment of the present invention, and FIGS. 3 and 4 are diagrams using a photocoupler according to an embodiment of the present invention. It is a diagram showing the circuit configuration of the insulated DC voltage measuring device 100 .

2 to 4 , an insulated DC voltage measuring apparatus 100 using a photocoupler according to an embodiment of the present invention includes an input power supply 10 , a photocoupler 110 and a conversion resistor 120 . do. In more detail, the input power supply 10, the input power supply 10 is connected to the first current supplied by the input power supply 10 as input and receives the optical signal transmitter 111 and the optical signal to emit an optical signal to receive The photocoupler 110 including an optical signal receiver 112 for generating a second current and the photocoupler 110 are connected in parallel with the output terminal of the photocoupler 110 to receive and measure the second current generated by the photocoupler 110 It may include a conversion resistor 120 that converts the desired voltage. In this case, the first current is a current received by the photocoupler 110 , and the second current is a current output from the photocoupler 110 .

The input power 10 is a power supply for supplying a voltage to be measured, and is preferably a DC power supply for the photocoupler 110 to operate in one direction.

The photocoupler 110 is connected to the input power 10 and receives the first current supplied by the input power 10 and receives the optical signal transmitter 111 for emitting an optical signal, and receives the optical signal to generate a second current It may include an optical signal receiving unit 112 to generate.

In this case, the optical signal transmitter 111 may use an infrared LED as a light emitting diode, and the optical signal receiver 112 may use a photo diode or a photo transistor. The optical signal transmitter 111 and the optical signal receiver 112 are optically coupled via a transparent resin, and the periphery may be thickly covered with black resin to block external light and add mechanical strength. In addition, if gallium arsenide aluminum is used for the optical signal transmitter 111 and a pin diode high-speed device is used for the optical signal receiver 112, it can be used up to 100 MHz, and a flat frequency response can be obtained from direct current to high frequency.

Since the photocoupler 110 uses light, it is strong against noise, can insulate current between devices constituting the system, and can be grounded for each device. In addition, since the coupling capacitance between devices is small, there is an advantage in that the signal on the output side does not return to the input side. For this reason, if an electric circuit is coupled via the photocoupler 110 to measure the voltage, there is no need to worry about the difference in power supply voltage or noise generated from the mechanical part, so that the circuit design can be simplified. In addition, since it is possible to measure voltage in an electrically isolated state, it has the advantage of being able to safely measure voltage even where a large voltage flows.

On the other hand, the optical signal receiver 112 generates a second current having a current transfer ratio proportional to the first current (ratio of the output current of the optical signal receiver to the input current of the optical signal transmitter, Current Transfer Ratio, CTR). can be characterized as This is because the photocoupler 110 has a characteristic in which a current transfer ratio is proportional to an input current within a constant current range as shown in FIG. 6 . The EL817, which is the photocoupler 110 used in the experiment of FIG. 6 , had a linear current transfer ratio at an input current of 0 mA to 10 mA, and this range may be slightly different for each manufacturer of the photo coupler 110 . The present invention uses a voltage divider 130 to be described later so that the transfer current ratio of the photocoupler 110 can be used within a linear region, so the ratio of the voltage to be measured is divided according to the specifications of the photocoupler 110 . The insulated voltage can be measured.

In addition, as shown in FIG. 7 , it may be characterized in that the input power (point (a) of FIG. 3) and the voltage applied to the conversion resistor (point (b) of FIG. 3) are proportional to each other. This is because the optical signal receiver 112 of the photocoupler 110 generates a second current having a current transfer ratio proportional to the first current. Therefore, it is possible to measure the insulation voltage proportional to the input voltage at the node of the conversion resistor, which has the advantage of safely measuring the voltage even where a large voltage flows.

The conversion resistor 120 is connected in parallel with the output terminal of the photocoupler 110 to convert the second current generated by the photocoupler 110 into a voltage to be measured. Accordingly, the present invention enables the conversion resistor 120 to derive an insulation voltage from the voltage value converted from the second current. However, in order to facilitate the measurement of the insulation voltage, the magnitude of the voltage converted by the conversion resistor 120 must be sufficiently large. In order to efficiently amplify the voltage, the configuration of the voltage conversion unit 140 or the amplification unit, which will be described later, may be further added.

Meanwhile, in another embodiment of the present invention, the insulated DC voltage measuring device 100 using a photocoupler is connected in parallel with the input power supply 10 and the photocoupler 110, and divides the voltage of the input power supply 10 to The photocoupler 110 may further include a pressure dividing unit 130 to transmit it.

Since the purpose of the present invention is to use the photocoupler 110 in a region where the transfer current ratio is linear, the input current can be varied by adjusting the resistance value so that the transfer current ratio has an input current having a linear characteristic. When the voltage of the power supply 10 is very large, the voltage may be divided to be measured.

At this time, the voltage divider 130 includes a first resistor R1 and a second resistor R2 connected in series to the input power 10, and a first capacitor C1 connected in parallel to the first resistor R1, and , the photocoupler 110 may be characterized in that it is connected in parallel to the first capacitor C1.

Therefore, by adjusting the values of the first resistor R1 and the second resistor R2, the first current value to be input to the photocoupler 110 is adjusted so that the transfer current ratio of the photocoupler 110 can be used within a linear region. When the voltage of the input power supply 10 is very large, only the voltage applied to the first resistor R1 is measured by dividing the voltage across the first resistor R1 and the second resistor R2 to measure the total input power supply 10 ) can be measured. Meanwhile, the first resistor R1 and the first capacitor C1 are connected in parallel to remove a noise component included in the input power supply 10 side.

In addition, in another embodiment of the present invention, the insulated DC voltage measuring apparatus 100 using a photocoupler includes a (+) input terminal connected to the output terminal of the photocoupler, an output terminal that converts the second current into a voltage to be measured and outputs; Further comprising a voltage converter 140 including a first amplifier 144 including a (-) input terminal connected to the first node 145, the first node 145 is connected to the output terminal of the photocoupler The first node 145 is connected to the first noise removing unit 141 , and the first node 145 is connected to the second noise removing unit 142 connected to the ground, and the first node 145 is connected to the first amplifier 144 . It may be characterized in that it is connected to the third noise removing unit 143 connected to the output terminal. On the other hand, it is obvious that the first amplifier 144 is connected to an input impedance component, a positive power supply voltage, and a negative power supply voltage.

Accordingly, the voltage converter 140 can amplify the voltage converted by the conversion resistor 120 and remove noise at the same time. may be removed, the second noise removing unit 142 may filter the high-frequency signal of the input-side signal source, and the third noise removing unit 143 may function to remove noise of the output signal source.

In this case, the first noise removing unit 141 and the second noise removing unit 142 may be characterized in that a resistor and a capacitor are connected in series or in parallel as shown in FIG. 5 . In addition, the third noise removing unit 143 may be characterized in that a resistor and a capacitor are connected in parallel.

However, in the present invention, when this combination was tested, the resistance and the capacitor of the first noise removing unit 141 are in series, and the resistance of the second noise removing unit 142 and the third noise removing unit 143 and the It was confirmed that noise removal is most effective when capacitors are connected in parallel. Therefore, it is most preferable that the first noise removing unit 141 connects the resistor and the capacitor in series, and the second noise removing unit 142 and the third noise removing unit 143 connect the resistor and the capacitor in parallel.

In addition, in another embodiment of the present invention, when the voltage converter 140 is present, it is connected in parallel to the output terminal of the voltage converter 140 and includes a second amplifier for amplifying the voltage converted by the voltage converter 140 . It may further include an amplifying unit 150 .

The amplification unit 150 can measure a more accurate result to amplify the signal from which the noise has been removed by the above-described voltage converter 140 , and amplification can be increased with a small voltage, which is effective.

For example, if you want to amplify the voltage of 1V 100 times and use only one amplifier without a noise canceling part, the noise is also amplified 100 times, making it difficult to accurately measure the insulation voltage. Therefore, the above-described voltage converter 140 removes the noise of the input signal and then amplifies it, and then amplifies the signal once more in the amplifier to more efficiently amplify the voltage without noise, thereby helping to accurately measure the insulation voltage.

Also, if only one amplifier is used to amplify the voltage 100 times when the input voltage is 1V, 100V power must be supplied to the amplifier. However, in the case of using the voltage converter 140 and the first amplifier 144 and the second amplifier of the amplifier, even if only 10V is supplied to each amplifier, 10x10 = 100 times can be amplified. It can be amplified to be more efficient.

In this case, the second amplifier may be a non-inverting amplifier 151 or an inverting amplifier 152 . Therefore, when the second amplifier is the non-inverting amplifier 151, the circuit can be configured as shown in FIG. 3, and the signal output by the voltage converter 140 after removing the noise can be amplified in order to be more amplified. In addition, when the second amplifier is the inverting amplifier 152, the circuit can be configured as shown in FIG. 4, and the signal output by the voltage converter 140 after removing the noise can be more amplified or reduced. Therefore, there is an advantage in that the measurement result can be accurately measured by adjusting it when the voltage is too large or too small. In this case, the input signal of the second amplifier may be further stabilized by adding a pull-down resistor connected to the ground to the (+) input terminal or the (-) input terminal of the second amplifier.

In addition, as shown in FIG. 7 , the input power (point (a) of FIG. 3) and the voltage applied to the output terminal of the amplifier (point (c) of FIG. 3) may be proportional to each other. In this case, the optical signal receiver 112 of the photocoupler 110 generates a second current having a current transfer ratio proportional to the first current, and the voltage converter 140 and the amplifier 150 first convert the input voltage to the first current. This is because it increases proportionally in the form of a function. Therefore, an insulation voltage having a magnitude proportional to the input voltage can be measured at the output terminal of the amplifier 150, so that a relatively large voltage compared to the voltage applied to the conversion resistor is applied to the output terminal of the amplifier 150, and in addition to the voltage conversion unit ( 140) has the advantage of being easy to measure and accurate because noise is removed.

As in the circuit of FIG. 3 , it includes all of the above-described input power supply 10 , voltage divider 130 , photo coupler 110 , conversion resistor 120 , voltage converter 140 , and amplifier 150 . When the voltage is measured at points a), b), and c) of FIG. 3, the results are as shown in FIG. As such, as the input voltage increases, the voltage measured at the output terminal of the amplifying unit also increases in proportion. Therefore, if the value of each element constituting the circuit is set, the insulation voltage can be measured based on this.

As such, those skilled in the art to which the present invention pertains will understand that the present invention may be embodied in other specific forms without changing the technical spirit or essential characteristics thereof. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the following claims rather than the above detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention. do.

10: input power
100: Insulated DC voltage measuring device using photo coupler
110: photo coupler
111: optical signal transmitter
112: optical signal receiver
120: conversion resistance
130: pressure dividing unit
R1: first resistor
R2: second resistor
C1: first capacitor
140: voltage converter
141: first noise removing unit
142: second noise removing unit
143: third noise removing unit
144: first amplifier
145: first node
150: amplification unit
151: non-inverting amplifier
152: inverting amplifier

Claims (11)

input power;
a photocoupler comprising: an optical signal transmitter connected to the input power supply to receive a first current supplied by the input power supply and emit an optical signal; and an optical signal receiver configured to receive the optical signal and generate a second current;
a conversion resistor connected in parallel with the output terminal of the photocoupler to receive the second current generated by the photocoupler and convert it into a voltage to be measured;
Voltage comprising a first amplifier including a (+) input terminal connected to the output terminal of the photocoupler, an output terminal for converting the second current into a voltage to be measured, and a (-) input terminal connected to the first node conversion unit; and
an amplifying unit connected in parallel to an output terminal of the voltage converting unit and including a second amplifier for amplifying the voltage converted by the voltage converting unit;
includes,
A voltage applied to the input power and the conversion resistor is proportional, and a voltage applied to the input power and an output terminal of the amplifying unit is also proportional,
The optical signal receiving unit,
generating a second current having a current transfer ratio proportional to the first current,
The first node is
It is connected to the first noise removing unit connected to the output terminal of the photo coupler,
It is connected to the second noise removing unit connected to the ground,
An insulated DC voltage measuring device using a photocoupler, characterized in that it is connected to a third noise removing unit connected to the output terminal of the first amplifier.
delete delete According to claim 1,
a voltage dividing unit connected in parallel to the input power and the photocoupler, dividing the voltage of the input power and transferring the voltage to the photocoupler;
Insulated DC voltage measuring device using a photocoupler further comprising a.
5. The method of claim 4,
The pressure dividing unit,
a first resistor and a second resistor connected in series to the input power;
a first capacitor connected in parallel to the first resistor;
including,
The photocoupler is an insulated DC voltage measuring device using a photocoupler, characterized in that it is connected in parallel to the first capacitor.
delete The method of claim 1,
The first noise removing unit and the second noise removing unit,
An insulated DC voltage measuring device using a photocoupler, characterized in that a resistor and a capacitor are connected in series or in parallel.
The method of claim 1,
The third noise removing unit,
An insulated DC voltage measuring device using a photocoupler, characterized in that a resistor and a capacitor are connected in parallel.
delete delete delete

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