Low power consumption current mode strong current input circuit

Abstract

A low-power current type strong current circuit, comprising a strong current circuit, an input isolation circuit and a power supply, the strong current circuit is composed of a first voltage dividing resistor R1, a third voltage dividing resistor R3 and a threshold voltage detection circuit, the strong current input positive electrode is connected to the strong current input negative electrode through the first voltage dividing resistor R1 and the third voltage dividing resistor R3 in series, and the threshold voltage detection circuit is connected in parallel across the third voltage dividing resistor R3; the voltage difference between the strong current input positive electrode and the strong current input negative electrode is a strong current input signal, and the threshold voltage detection circuit is used for outputting a strong current circuit threshold voltage when the strong current input signal exceeds a set value; the input end of the input isolation circuit is connected with the output end of the strong current circuit, and the input isolation circuit comprises an optical coupler U1; when the input isolation circuit receives the strong current circuit threshold voltage, the optical coupler U1 is turned on, and the low level of the input signal output by the optical coupler U1 becomes high level. The utility model effectively reduces the loop power consumption, reduces the cost and the heat quantity.

Description

Technical Field

[0001] This utility model belongs to the technical field of relay protection equipment, and more specifically, relates to a low-power current-type high-voltage input circuit. Background Technology

[0002] Currently, high-voltage input circuits are widely used in relay protection equipment. In power system secondary equipment, high-voltage input refers to DC 220V / DC 110V input voltage, while low-voltage input often refers to DC 24V. The current solution uses a large-value resistor in series with an optocoupler in the input circuit. Because of the need for DC 220V or 110V input signals in the field, and considering the threshold requirements for high-voltage input, the series optocoupler must operate in the linear region, resulting in a relatively small current of 2mA to 5mA. Since the primary voltage drop of the optocoupler is small (1.2V), most of the input DC 220V or 110V signal voltage is obtained by voltage division by the large-value resistor in the circuit. Under prolonged and multi-channel use, this can cause the circuit to overheat, threatening equipment safety and even causing damage to resistors, adjacent components, and the PCB board.

[0003] In existing technical documents, the design of high-voltage input circuits mainly includes:

[0004] CN115102387A discloses an input circuit for AC / DC input, including a circuit that uses a rectifier bridge structure and a resistor in series with an optocoupler to realize AC / DC input function. Its main body uses a resistor in series with an optocoupler to achieve basic input function, but it cannot solve the problem of excessive circuit power. A similar technical document is CN 204008881U.

[0005] CN202330541U discloses an AC 220V input signal acquisition circuit, including a high-voltage input circuit. It more directly uses a resistor and series optocoupler to complete the high-voltage input function. A diode is connected in series in the circuit to realize half-wave rectification and reverse connection protection of the cable. However, its main body is a resistor and optocoupler to realize the basic input function, which cannot solve the problem of excessive circuit power.

[0006] CN101630829B discloses a high-voltage switch input module with power requirements, including a voltage-type input circuit with power requirements. During the gradual increase of the input voltage, a parallel power circuit consisting of a resistor and a transistor is provided to dissipate power. When the main circuit operates, Q1 in the parallel power circuit is disconnected, and the power circuit is cut off. Although the high-voltage switch input module described in the document adopts a removable power circuit design, it increases the complexity of the high-voltage switch input design. The voltage-type Q2 activation principle results in weak anti-interference capabilities and the possibility of power circuit disconnection failure due to component failure. Utility Model Content

[0007] To address the shortcomings of existing technologies, this invention provides a low-power current-type high-voltage input circuit.

[0008] The present invention adopts the following technical solution.

[0009] The first aspect of this utility model provides a low-power current-mode high-voltage input circuit, comprising a high-voltage input front-end circuit, an input isolation circuit, and a power supply, characterized in that:

[0010] The high-voltage input front-end circuit consists of a first voltage divider resistor R1, a third voltage divider resistor R3, and a threshold voltage detection circuit. The positive terminal of the high-voltage input is connected to the negative terminal of the high-voltage input through the first voltage divider resistor R1 and the third voltage divider resistor R3 connected in series. The threshold voltage detection circuit is connected in parallel across the third voltage divider resistor R3. The voltage difference between the positive and negative terminals of the high-voltage input is the high-voltage input signal. The threshold voltage detection circuit is used to output the threshold voltage of the high-voltage input circuit when the high-voltage input signal exceeds the set allowable value.

[0011] The input terminal of the input isolation circuit is connected to the output terminal of the high-voltage input front-end circuit. The input isolation circuit includes an optocoupler U1. When the input isolation circuit receives the threshold voltage of the high-voltage input circuit, the optocoupler U1 is turned on, and the low level of the input signal output by the optocoupler U1 changes to a high level.

[0012] The power supply is used to power the primary positive terminal of optocoupler U1.

[0013] Preferably, the threshold voltage detection circuit includes a Zener diode Z1, a second resistor R2, and a second diode D2;

[0014] The cathode of Zener diode Z1 is connected to the junction of the first voltage divider resistor R1 and the third voltage divider resistor R3; the anode of Zener diode Z1 is connected to one end of the second resistor R2, the other end of the second resistor R2 is connected to the cathode of the second diode D2, and the anode of the second diode D2 is connected to the negative terminal of the high-voltage input circuit; the cathode and anode of the second diode D2 serve as the two output terminals of the threshold voltage detection circuit, and the voltage difference between the cathode and anode of the second diode D2 is the threshold voltage of the high-voltage input circuit.

[0015] Preferably, the input isolation circuit further includes a first diode D1, an NPN transistor T2, a fourth resistor R4, a fifth resistor R5, and a sixth resistor R6;

[0016] The base of NPN transistor T2 is connected to the cathode of the second diode D2. The emitter of NPN transistor T2 is connected to the negative terminal of the high-voltage switch through the fifth resistor R5. The collector of NPN transistor T2 is connected to the negative terminal of the primary side of optocoupler U1 through the fourth resistor R4. The positive terminal of the primary side of optocoupler U1 is connected to the cathode of the first diode D1, and the anode of the first diode D1 is connected to the negative terminal of the high-voltage switch. The positive terminal of the secondary side of optocoupler U1 is connected to a 3.3V voltage, and the negative terminal of the secondary side of optocoupler U1 is connected to one end of the sixth resistor R6. The connection point serves as the input signal output. The other end of the sixth resistor R6 is grounded.

[0017] Preferably, the first diode D1 and the second diode D2 are diodes of the same type.

[0018] Preferably, the positive terminal of the power supply is connected to the junction point of the primary positive terminal of the optocoupler U1 and the cathode of the first diode D1, and the negative terminal of the power supply is connected to the negative terminal of the high voltage input.

[0019] Preferably, the breakdown voltage U of the Zener diode Z satisfy:

[0020]

[0021] Where U0 is the rated voltage of the power grid, and R1 and R3 are the resistance values ​​of the first voltage divider resistor and the third voltage divider resistor, respectively.

[0022] Preferably, the resistance values ​​of the first voltage divider resistor R1 and the third voltage divider resistor R3 are both greater than or equal to 100kΩ and less than 1MΩ.

[0023] Preferably, the resistance values ​​of the first voltage divider resistor R1 and the third voltage divider resistor R3 are 450kΩ and 140kΩ, respectively.

[0024] Preferably, the power supply is an isolated power supply with a positive output of 5V and a negative output of -5V.

[0025] The beneficial effects of this utility model are as follows, compared with the prior art:

[0026] 1. This circuit uses high-value voltage divider resistors to effectively reduce the current value in the high-voltage input circuit, thereby effectively reducing circuit power consumption and reducing component aging caused by heat during long-term circuit operation.

[0027] 2. This circuit has a simple circuit structure, a small number of components, which can effectively reduce costs, generate low heat, and require little wiring space, making it suitable for practical layouts in small spaces and with multiple dense circuits.

[0028] 3. The circuit is easy to expand and highly practical. By changing the component parameters of the Zener diode and diode, the threshold voltage of the high-voltage input circuit can be set, making the operation convenient, accurate, and easy to produce.

[0029] 4. An isolated power supply is used to supply power to the primary side of the isolation optocoupler in the input isolation circuit. After the threshold voltage of the high-voltage input circuit is confirmed, the conduction current of the primary side of the isolation optocoupler does not depend on the high-voltage input current. Attached Figure Description

[0030] Figure 1 This is a block diagram of the circuit of this utility model. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. The embodiments described in this application are merely some embodiments of this utility model, and not all embodiments. Based on the spirit of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0032] like Figure 1 As shown, Embodiment 1 of this utility model proposes a low-power current-mode high-voltage input circuit, including a high-voltage input front-end circuit, an input isolation circuit, and a power supply, characterized in that:

[0033] The high-voltage input front-end circuit consists of a first voltage divider resistor R1, a third voltage divider resistor R3, and a threshold voltage detection circuit. The positive terminal of the high-voltage input is connected to the negative terminal of the high-voltage input through the first voltage divider resistor R1 and the third voltage divider resistor R3 connected in series. The threshold voltage detection circuit is connected in parallel across the third voltage divider resistor R3. The voltage difference between the positive and negative terminals of the high-voltage input is the high-voltage input signal. The threshold voltage detection circuit is used to output the threshold voltage of the high-voltage input circuit when the high-voltage input signal exceeds the set allowable value.

[0034] The input terminal of the input isolation circuit is connected to the output terminal of the high-voltage input front-end circuit. The input isolation circuit includes an optocoupler U1. When the input isolation circuit receives the threshold voltage of the high-voltage input circuit, the optocoupler U1 is turned on, and the low level of the input signal output by the optocoupler U1 changes to a high level.

[0035] The power supply is used to power the primary positive terminal of optocoupler U1.

[0036] The threshold voltage detection circuit includes a Zener diode Z1, a second resistor R2, and a second diode D2;

[0037] The cathode of Zener diode Z1 is connected to the junction of the first voltage divider resistor R1 and the third voltage divider resistor R3; the anode of Zener diode Z1 is connected to one end of the second resistor R2, the other end of the second resistor R2 is connected to the cathode of the second diode D2, and the anode of the second diode D2 is connected to the negative terminal of the high-voltage input circuit; the cathode and anode of the second diode D2 serve as the two output terminals of the threshold voltage detection circuit, and the voltage difference between the cathode and anode of the second diode D2 is the threshold voltage of the high-voltage input circuit.

[0038] The input isolation circuit also includes a first diode D1, an NPN transistor T2, a fourth resistor R4, a fifth resistor R5, and a sixth resistor R6;

[0039] The base of NPN transistor T2 is connected to the cathode of the second diode D2. The emitter of NPN transistor T2 is connected to the negative terminal of the high-voltage switch through the fifth resistor R5. The collector of NPN transistor T2 is connected to the negative terminal of the primary side of optocoupler U1 through the fourth resistor R4. The positive terminal of the primary side of optocoupler U1 is connected to the cathode of the first diode D1, and the anode of the first diode D1 is connected to the negative terminal of the high-voltage switch. The positive terminal of the secondary side of optocoupler U1 is connected to a 3.3V voltage, and the negative terminal of the secondary side of optocoupler U1 is connected to one end of the sixth resistor R6. The connection point serves as the input signal output. The other end of the sixth resistor R6 is grounded.

[0040] Specifically, in this embodiment, the optocoupler U1 is model TLP185 and the NPN transistor T2 is model NPN-MMBT2222LT1;

[0041] The first diode D1 and the second diode D2 are diodes of the same type. Specifically, in this embodiment, the first diode D1 and the second diode are of type D2IN4148 and have a reverse withstand voltage of 1000V.

[0042] The positive terminal of the power supply is connected to the junction point of the primary positive terminal of the optocoupler U1 and the cathode of the first diode D1, and the negative terminal of the power supply is connected to the negative terminal of the high voltage input.

[0043] The breakdown voltage U of the Zener diode Z satisfy:

[0044]

[0045] Where U0 is the rated voltage of the power grid, and R1 and R3 are the resistance values ​​of the first voltage divider resistor and the third voltage divider resistor, respectively.

[0046] The resistance values ​​of the first voltage divider resistor R1 and the third voltage divider resistor R3 are both greater than or equal to 100kΩ and less than 1MΩ.

[0047] It should be noted that resistors of 100kΩ or higher are more suitable and readily available, and perform better in voltage division and reducing current in high-voltage input circuits. If megaohm-level resistors are used for distribution, their failure rate will be higher due to manufacturing issues.

[0048] Specifically, the resistance values ​​of the first voltage divider resistor R1 and the third voltage divider resistor R3 are 450kΩ and 140kΩ, respectively. The second resistor R2 is 22Ω; the fourth resistor R4 is 1.2kΩ; the fifth resistor R5 is 4.7kΩ; and the sixth resistor R6 is 0Ω.

[0049] Specifically, in this embodiment, the rated mains voltage is 220V, and 55% of the rated mains voltage is 121V. When the high-voltage input signal is 121V, the voltage across R3 is 28.7V. Furthermore, 70% of the rated mains voltage is the voltage at which the mains must operate, i.e., 154V. When the high-voltage input signal is 154V, the voltage across R3 is 35.42V. The breakdown voltage of the Zener diode should be between 28.7V and 35.42V. In this embodiment, a breakdown voltage U is selected. Z It is a 30V Zener diode with wide applicability.

[0050] The power supply is an isolated power supply with a positive output of 5V and a negative output of -5V. Specifically, the isolated power supply used in this embodiment has a length, width, and height of 20mm, 6mm, and 10mm, respectively, and its specific model is MORNSUN_F0505S-2WR3.

[0051] When a high-voltage input signal is input to the high-voltage input circuit, it is divided by the first voltage divider resistor R1 and the third voltage divider resistor R3. If the voltage of the third voltage divider resistor R3 is greater than the breakdown voltage of the Zener diode Z1, then the Zener diode Z1 and the second diode D2 will conduct. The conduction voltage of the second diode D2 is the threshold voltage of the high-voltage input circuit. At this time, the voltage difference between the base and emitter of the NPN transistor T2 is equal to the threshold voltage of the high-voltage input circuit, and the NPN transistor T2 conducts. The negative terminal of the primary side of the optocoupler U1 is connected to the negative terminal of the high-voltage input circuit, and the positive terminal of the primary side of the optocoupler U1 is connected to the positive terminal of the power supply. The optocoupler U1 conducts, and the negative terminal of the secondary side of the optocoupler U1 changes from a low level to a high level.

[0052] Specifically, when the high-voltage input signal is 121V, the voltage U of the third voltage divider resistor R3 is... R3 for:

[0053]

[0054] U1 is the high-voltage input signal;

[0055] At this time, the voltage U of the third voltage divider resistor R3 R3 Less than the breakdown voltage U of Zener diode Z1 ZAt this time, no current flows through the second resistor R2, and the second diode D2 and NPN transistor T2 are not conducting; the optocoupler U1 outputs a low level.

[0056] When the high-voltage input signal is 127V, the voltage U of the third voltage divider resistor R3 is... R3 for:

[0057]

[0058] U1 is the high-voltage input signal;

[0059] At this time, the voltage U of the third voltage divider resistor R3 R3 Greater than the breakdown voltage U of Zener diode Z1 Z At this time, current flows through the second resistor R2, and the second diode D2 and NPN transistor T2 are both turned on; the optocoupler U1 outputs a high level.

[0060] At this time, the long-term operating power P of the circuit is:

[0061]

[0062] This demonstrates that the low power consumption requirement has been met.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and not to limit it. Although the utility model has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of this utility model. Any modifications or equivalent substitutions that do not depart from the spirit and scope of this utility model should be covered within the protection scope of the claims of this utility model.

Claims

1. A low-power current-mode high-voltage input circuit, comprising a high-voltage input front-end circuit, an input isolation circuit, and a power supply, characterized in that: The high-voltage input front-end circuit consists of a first voltage divider resistor R1, a third voltage divider resistor R3, and a threshold voltage detection circuit. The positive terminal of the high-voltage input is connected to the negative terminal of the high-voltage input through the first voltage divider resistor R1 and the third voltage divider resistor R3 connected in series. The threshold voltage detection circuit is connected in parallel across the third voltage divider resistor R3. The voltage difference between the positive and negative terminals of the high-voltage input is the high-voltage input signal. The threshold voltage detection circuit is used to output the threshold voltage of the high-voltage input circuit when the high-voltage input signal exceeds the set allowable value. The input terminal of the input isolation circuit is connected to the output terminal of the high-voltage input front-end circuit. The input isolation circuit includes an optocoupler U1. When the input isolation circuit receives the threshold voltage of the high-voltage input circuit, the optocoupler U1 is turned on, and the low level of the input signal output by the optocoupler U1 changes to a high level. The power supply is used to power the primary positive terminal of optocoupler U1.

2. The low-power current-mode high-voltage input circuit according to claim 1, characterized in that: The threshold voltage detection circuit includes a Zener diode Z1, a second resistor R2, and a second diode D2; The cathode of Zener diode Z1 is connected to the junction of the first voltage divider resistor R1 and the third voltage divider resistor R3; the anode of Zener diode Z1 is connected to one end of the second resistor R2, the other end of the second resistor R2 is connected to the cathode of the second diode D2, and the anode of the second diode D2 is connected to the negative terminal of the high-voltage input circuit; the cathode and anode of the second diode D2 serve as the two output terminals of the threshold voltage detection circuit, and the voltage difference between the cathode and anode of the second diode D2 is the threshold voltage of the high-voltage input circuit.

3. The low-power current-mode high-voltage input circuit according to claim 2, characterized in that: The input isolation circuit also includes a first diode D1, an NPN transistor T2, a fourth resistor R4, a fifth resistor R5, and a sixth resistor R6; The base of NPN transistor T2 is connected to the cathode of the second diode D2. The emitter of NPN transistor T2 is connected to the negative terminal of the high-voltage switch through the fifth resistor R5. The collector of NPN transistor T2 is connected to the negative terminal of the primary side of optocoupler U1 through the fourth resistor R4. The positive terminal of the primary side of optocoupler U1 is connected to the cathode of the first diode D1, and the anode of the first diode D1 is connected to the negative terminal of the high-voltage switch. The positive terminal of the secondary side of optocoupler U1 is connected to a 3.3V voltage, and the negative terminal of the secondary side of optocoupler U1 is connected to one end of the sixth resistor R6. The connection point serves as the input signal output. The other end of the sixth resistor R6 is grounded.

4. The low-power current-mode high-voltage input circuit according to claim 3, characterized in that: The first diode D1 and the second diode D2 are diodes of the same type.

5. A low-power current-mode high-voltage input circuit according to claim 3, characterized in that: The positive terminal of the power supply is connected to the junction point of the primary positive terminal of the optocoupler U1 and the cathode of the first diode D1, and the negative terminal of the power supply is connected to the negative terminal of the high voltage input.

6. The low-power current-mode high-voltage input circuit according to claim 2, characterized in that: The breakdown voltage U of the Zener diode Z satisfy: Where U0 is the rated voltage of the power grid, and R1 and R3 are the resistance values ​​of the first voltage divider resistor and the third voltage divider resistor, respectively.

7. A low-power current-mode high-voltage input circuit according to claim 6, characterized in that: The resistance values ​​of the first voltage divider resistor R1 and the third voltage divider resistor R3 are both greater than or equal to 100kΩ and less than 1MΩ.

8. A low-power current-mode high-voltage input circuit according to claim 7, characterized in that: The resistance values ​​of the first voltage divider resistor R1 and the third voltage divider resistor R3 are 450kΩ and 140kΩ, respectively.

9. A low-power current-mode high-voltage input circuit according to claim 5, characterized in that: The power supply is an isolated power supply, with a positive output of 5V and a negative output of -5V.

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