Low-power-consumption current type strong current input circuit and method

Abstract

The invention discloses a low-power-consumption current type strong current input circuit and method, and the circuit comprises a strong current input front-end circuit, an input isolation circuit, and a power supply, and the strong current input front-end circuit is composed of a first divider resistor R1, a third divider 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 divider resistor R1 and the third divider resistor R3 which are connected in series, and the threshold voltage detection circuit is connected to the two ends of the third divider resistor R3 in parallel; 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 input 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 input front-end circuit, the input isolation circuit comprises an optocoupler U1, when the input isolation circuit receives the threshold voltage of the strong current input circuit, the optocoupler U1 is conducted, and the low level of an input signal output by the optocoupler U1 is changed into the high level. Loop power consumption is effectively reduced, and cost and calorific value are reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of relay protection equipment, and more specifically, relates to a low-power current-type high-voltage input circuit and method. Background Art

[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 DC voltage inputs, as opposed to low-voltage inputs, which often refer to DC 24V. The current solution uses a large-value resistor in series with an optocoupler in the input circuit. Because the on-site DC 220V or 110V input signal, while also meeting the threshold requirements for high-voltage input, requires the series optocoupler to operate in the linear region, resulting in a relatively low current flow of 2 to 5 mA. Because the optocoupler's primary voltage drop is a small 1.2V, the majority of the DC 220V or 110V input signal voltage is derived from voltage dividers made by large-value resistors in the circuit. Prolonged, multi-circuit use can cause the circuit to heat up, threatening equipment safety and potentially damaging the resistor, adjacent components, and even the printed circuit board.

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

[0004] CN115102387A discloses a binary input circuit for AC and DC binary inputs. This circuit utilizes a rectifier bridge structure and a resistor in series with an optocoupler to achieve the AC / DC binary input function. While the circuit's core is a resistor in series with an optocoupler to achieve the basic binary input function, it fails to address the issue of excessive circuit power. Similar technical documents include CN 204008881U.

[0005] CN202330541U discloses an AC 220V input signal acquisition circuit, including a high-voltage switching circuit, which more directly uses resistors and series optocouplers to complete the high-voltage switching function. A diode is connected in series in the loop to achieve half-wave rectification and anti-reverse function of cable reverse connection. However, its main body is a resistor in series with an optocoupler to achieve the basic switching 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 open-in circuit with power requirements. As the open-in voltage gradually increases, a parallel power circuit consisting of a resistor and a transistor is provided to consume power. When the main circuit is activated, 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 power circuit removable design, it increases the complexity of the high-voltage switch input design. The voltage-type Q2 opening principle has weak anti-interference performance and the power circuit cut-off failure caused by component failure. Summary of the Invention

[0007] In order to solve the deficiencies in the prior art, the present invention provides a low-power current-type high-voltage input circuit design and method.

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

[0009] The first aspect of the present invention provides a low-power current-type high-voltage input circuit, comprising a high-voltage input front-end circuit, a high-voltage input isolation circuit, and a power supply, characterized in that:

[0010] The front-end circuit of the strong power input is composed of a first voltage-dividing resistor R1, a third voltage-dividing resistor R3 and a threshold voltage detection circuit. The positive electrode of the strong power input is connected to the negative electrode of the strong power input through the first voltage-dividing resistor R1 and the third voltage-dividing resistor R3 connected in series, and the threshold voltage detection circuit is connected in parallel at both ends of the third voltage-dividing resistor R3; the voltage difference between the positive and negative electrodes of the strong power input is the strong power input signal, and the threshold voltage detection circuit is used to output the threshold voltage of the strong power input circuit when the strong power input signal exceeds the set allowable value;

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

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

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

[0014] The cathode of the voltage-stabilizing tube Z1 is connected to the connection point of the first voltage-dividing resistor R1 and the third voltage-dividing resistor R3; the anode of the voltage-stabilizing tube Z1 is connected to one end of the second resistor, 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 electrode of the high-voltage input; the cathode and anode of the second diode D2 serve as the two output ends 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 open-in 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 the NPN transistor T2 is connected to the cathode of the second diode D2, the emitter of the NPN transistor T2 is connected to the negative electrode of the high-voltage input through the fifth resistor R5, and the collector of the NPN transistor T2 is connected to the negative electrode of the primary side of the optocoupler U1 through the fourth resistor R4; the positive electrode of the primary side of the 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 electrode of the high-voltage input; the positive electrode of the secondary side of the optocoupler U1 is connected to the 3.3V voltage, and the negative electrode of the secondary side of the optocoupler U1 is connected to one end of the sixth resistor R6, and the connection point is used 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 electrode of the power supply is connected to the connection point of the primary positive electrode of the optocoupler U1 and the cathode of the first diode D1, and the negative electrode of the power supply is connected to the negative electrode of the high-voltage input.

[0019] Preferably, the breakdown voltage of the voltage regulator tube is U Z satisfy:

[0020]

[0021] Wherein, U0 is the rated voltage of the grid, R1 and R3 are the resistance values ​​of the first and third voltage-dividing resistors respectively.

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

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

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

[0025] The second aspect of the present invention provides a method for accessing the low-power current-type high-voltage input circuit based on the first aspect of the present invention, characterized by comprising:

[0026] The strong current input signal is input into the strong current input circuit, and the voltage is divided by the first voltage-dividing resistor R1 and the third voltage-dividing resistor R3. If the voltage of the third voltage-dividing resistor R3 is greater than the breakdown voltage of the voltage-regulating tube Z1, the voltage-regulating tube Z1 and the second diode D2 are turned on, and the turn-on voltage of the second diode D2 is the threshold voltage of the strong current input circuit. At this time, the voltage difference between the base and the emitter of the NPN transistor T2 is equal to the threshold voltage of the strong current input circuit, the NPN transistor T2 is turned on, the primary negative electrode of the optocoupler U1 is connected to the negative electrode of the strong current input, the primary positive electrode of the optocoupler U1 is connected to the positive electrode of the power supply, the optocoupler U1 is turned on, and the secondary negative electrode of the optocoupler U1 changes from a low level to a high level.

[0027] The beneficial effects of the present invention are as follows:

[0028] 1. This circuit uses a relatively high-resistance voltage divider resistor to effectively reduce the current value in the high-voltage input circuit, thereby effectively reducing the circuit power consumption and thus reducing the aging of components caused by heat during long-term operation of the circuit.

[0029] 2. This circuit has a simple loop structure and a small number of components, which can effectively reduce costs, generate low heat, and requires small wiring space, which is conducive to small space and multi-channel intensive practical layout.

[0030] 3. The circuit is easy to expand and has strong practicality. By changing the component parameters of the voltage regulator tube and the diode, it is possible to set whether to output the strong power input circuit threshold voltage and the strong power input circuit threshold voltage itself. The operation is convenient, accurate and easy to produce.

[0031] 4. Use an isolated power supply to meet the power supply requirements of the primary side of the isolated optocoupler in the input isolation circuit. After the threshold voltage of the strong power input circuit is confirmed, the primary side conduction current of the isolated optocoupler does not depend on the strong power input current. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A block diagram of the circuit of the present invention. DETAILED DESCRIPTION

[0033] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. The embodiments described in this application are only part of the embodiments of the present invention, not all of them. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0034] like Figure 1 As shown, embodiment 1 of the present invention proposes a low-power current-type high-voltage input circuit, including a high-voltage input front-end circuit, a high-voltage input isolation circuit and a power supply, characterized in that:

[0035] The front-end circuit of the strong power input is composed of a first voltage-dividing resistor R1, a third voltage-dividing resistor R3 and a threshold voltage detection circuit. The positive electrode of the strong power input is connected to the negative electrode of the strong power input through the first voltage-dividing resistor R1 and the third voltage-dividing resistor R3 connected in series, and the threshold voltage detection circuit is connected in parallel at both ends of the third voltage-dividing resistor R3; the voltage difference between the positive and negative electrodes of the strong power input is the strong power input signal, and the threshold voltage detection circuit is used to output the threshold voltage of the strong power input circuit when the strong power input signal exceeds the set allowable value;

[0036] The input end of the binary input isolation circuit is connected to the output end of the strong power binary input front-end circuit. The binary input isolation circuit includes an optocoupler U1. When the binary input isolation circuit receives the threshold voltage of the strong power binary input circuit, the optocoupler U1 is turned on, and the binary input signal output by the optocoupler U1 changes from a low level to a high level.

[0037] The power supply is used to power the primary positive terminal of the optocoupler U1.

[0038] The threshold voltage detection circuit includes a voltage regulator Z1, a second resistor R2 and a second diode D2;

[0039] The cathode of the voltage-stabilizing tube Z1 is connected to the connection point of the first voltage-dividing resistor R1 and the third voltage-dividing resistor R3; the anode of the voltage-stabilizing tube Z1 is connected to one end of the second resistor, 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 electrode of the high-voltage input; the cathode and anode of the second diode D2 serve as the two output ends 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.

[0040] The open-in 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;

[0041] The base of the NPN transistor T2 is connected to the cathode of the second diode D2, the emitter of the NPN transistor T2 is connected to the negative electrode of the high-voltage input through the fifth resistor R5, and the collector of the NPN transistor T2 is connected to the negative electrode of the primary side of the optocoupler U1 through the fourth resistor R4; the positive electrode of the primary side of the 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 electrode of the high-voltage input; the positive electrode of the secondary side of the optocoupler U1 is connected to the 3.3V voltage, and the negative electrode of the secondary side of the optocoupler U1 is connected to one end of the sixth resistor R6, and the connection point is used as the input signal output; the other end of the sixth resistor R6 is grounded.

[0042] Specifically, the model of the optocoupler U1 used in this embodiment is TLP185, and the model of the NPN transistor T2 is NPN-MMBT2222LT1;

[0043] The first diode D1 and the second diode D2 are diodes of the same model. Specifically, the first diode D1 and the second diode used in this embodiment are of model D2IN4148, and have a reverse withstand voltage of 1000V.

[0044] The positive electrode of the power supply is connected to the connection point of the primary positive electrode of the optocoupler U1 and the cathode of the first diode D1, and the negative electrode of the power supply is connected to the negative electrode of the high-voltage input.

[0045] Breakdown voltage U of the Zener diode Z satisfy:

[0046]

[0047] Wherein, U0 is the rated voltage of the grid, R1 and R3 are the resistance values ​​of the first and third voltage-dividing resistors respectively.

[0048] The resistance of the first voltage-dividing resistor R1 and the third voltage-dividing resistor R3 are both greater than or equal to 100 kΩ and less than 1 MΩ.

[0049] It should be noted that resistors greater than or equal to 100kΩ are readily available and are excellent at dividing the voltage and reducing the current in the high-voltage input circuit. Using megohm-level resistors for this purpose can result in a higher failure rate due to manufacturing issues.

[0050] Specifically, the resistance values ​​of the first voltage-dividing resistor R1 and the third voltage-dividing resistor R3 are 450 kΩ and 140 kΩ respectively. The second resistor R2 is 22 Ω; the fourth resistor R4 is 1.2 kΩ; the fifth resistor R5 is 4.7 kΩ; and the sixth resistor R6 is 0 Ω.

[0051] Specifically, the grid rated voltage of this embodiment is 220V, 55% of the grid rated voltage is 121V, when the strong power input signal is 121V, the voltage across R3 is 28.7V; in addition, 70% of the grid rated voltage is the voltage at which the grid must operate, that is, 154V is the voltage at which the grid must operate, when the strong power input signal is 154V, the voltage across R3 is 35.42V. The breakdown voltage of the voltage regulator should be between 28.7V and 35.42V. In this embodiment, the breakdown voltage U Z It is a 30V voltage regulator tube with strong applicability.

[0052] The power supply is an isolated power supply, whose positive output is 5V and negative output is -5V. Specifically, the length, width and height of the isolated power supply used in this embodiment are 20mm, 6mm and 10mm respectively, and the specific model is MORNSUN_F0505S-2WR3.

[0053] Embodiment 2 of the present invention proposes a method for accessing a low-power current-type high-voltage input circuit based on Embodiment 1 of the present invention, characterized by comprising:

[0054] The strong current input signal is input into the strong current input circuit, and the voltage is divided by the first voltage-dividing resistor R1 and the third voltage-dividing resistor R3. If the voltage of the third voltage-dividing resistor R3 is greater than the breakdown voltage of the voltage-regulating tube Z1, the voltage-regulating tube Z1 and the second diode D2 are turned on, and the turn-on voltage of the second diode D2 is the threshold voltage of the strong current input circuit. At this time, the voltage difference between the base and the emitter of the NPN transistor T2 is equal to the threshold voltage of the strong current input circuit, the NPN transistor T2 is turned on, the primary negative electrode of the optocoupler U1 is connected to the negative electrode of the strong current input, the primary positive electrode of the optocoupler U1 is connected to the positive electrode of the power supply, the optocoupler U1 is turned on, and the secondary negative electrode of the optocoupler U1 changes from a low level to a high level.

[0055] Specifically, when the strong power input signal is 121V, the voltage U of the third voltage divider resistor R3 is R3 for:

[0056]

[0057] Among them, U1 is the strong power input signal;

[0058] At this time, the voltage U of the third voltage divider resistor R3 R3 Less than the breakdown voltage U of the Zener diode Z1 Z At this time, no current flows through the second resistor R2, the second diode D2 and the NPN transistor T2 are both off; the optocoupler U1 outputs a low level;

[0059] When the strong power input signal is 127V, the voltage U R3 for:

[0060]

[0061] Among them, U1 is the strong power input signal;

[0062] At this time, the voltage U of the third voltage divider resistor R3 R3 Greater than the breakdown voltage U of the Zener diode Z1 Z At this time, current flows through the second resistor R2, the second diode D2 and the NPN transistor T2 are both turned on; the optocoupler U1 outputs a high level;

[0063] At this time, the long-term working power P of the circuit is:

[0064]

[0065] This shows that low power consumption requirements are achieved.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A low-power current-type high-voltage input circuit, comprising a high-voltage input front-end circuit, a high-voltage input isolation circuit, and a power supply, characterized in that: The front-end circuit of the strong power input is composed of a first voltage-dividing resistor R1, a third voltage-dividing resistor R3 and a threshold voltage detection circuit. The positive electrode of the strong power input is connected to the negative electrode of the strong power input through the first voltage-dividing resistor R1 and the third voltage-dividing resistor R3 connected in series, and the threshold voltage detection circuit is connected in parallel at both ends of the third voltage-dividing resistor R3; the voltage difference between the positive and negative electrodes of the strong power input is the strong power input signal, and the threshold voltage detection circuit is used to output the threshold voltage of the strong power input circuit when the strong power input signal exceeds the set allowable value; The input end of the binary input isolation circuit is connected to the output end of the strong power binary input front-end circuit. The binary input isolation circuit includes an optocoupler U1. When the binary input isolation circuit receives the threshold voltage of the strong power binary input circuit, the optocoupler U1 is turned on, and the binary input signal output by the optocoupler U1 changes from a low level to a high level. The power supply is used to power the primary positive terminal of the optocoupler U1.

2. A low-power current-type high-voltage input circuit according to claim 1, characterized in that: The threshold voltage detection circuit includes a voltage regulator Z1, a second resistor R2 and a second diode D2; The cathode of the voltage-stabilizing tube Z1 is connected to the connection point of the first voltage-dividing resistor R1 and the third voltage-dividing resistor R3; the anode of the voltage-stabilizing tube Z1 is connected to one end of the second resistor, 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 electrode of the high-voltage input; the cathode and anode of the second diode D2 serve as the two output ends 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. A low-power current-type high-voltage input circuit according to claim 2, characterized in that: The open-in 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; The base of the NPN transistor T2 is connected to the cathode of the second diode D2, the emitter of the NPN transistor T2 is connected to the negative electrode of the high-voltage input through the fifth resistor R5, and the collector of the NPN transistor T2 is connected to the negative electrode of the primary side of the optocoupler U1 through the fourth resistor R4; the positive electrode of the primary side of the 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 electrode of the high-voltage input; the positive electrode of the secondary side of the optocoupler U1 is connected to the 3.3V voltage, and the negative electrode of the secondary side of the optocoupler U1 is connected to one end of the sixth resistor R6, and the connection point is used as the input signal output; the other end of the sixth resistor R6 is grounded.

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

6. A low-power current-type high-voltage input circuit according to claim 2, characterized in that: Breakdown voltage U of the Zener diode Z satisfy: Wherein, U0 is the rated voltage of the grid, R1 and R3 are the resistance values ​​of the first and third voltage-dividing resistors respectively.

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

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

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

10. A method for accessing a low-power current-type high-voltage input circuit according to any one of claims 3 to 9, characterized in that: include: The strong current input signal is input into the strong current input circuit, and the voltage is divided by the first voltage-dividing resistor R1 and the third voltage-dividing resistor R3. If the voltage of the third voltage-dividing resistor R3 is greater than the breakdown voltage of the voltage-regulating tube Z1, the voltage-regulating tube Z1 and the second diode D2 are turned on, and the turn-on voltage of the second diode D2 is the threshold voltage of the strong current input circuit. At this time, the voltage difference between the base and the emitter of the NPN transistor T2 is equal to the threshold voltage of the strong current input circuit, the NPN transistor T2 is turned on, the primary negative electrode of the optocoupler U1 is connected to the negative electrode of the strong current input, the primary positive electrode of the optocoupler U1 is connected to the positive electrode of the power supply, the optocoupler U1 is turned on, and the secondary negative electrode of the optocoupler U1 changes from a low level to a high level.

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