Protection measurement and control device with high anti-interference capability
By using a combination of optocoupler isolators and clamped diodes in the digital input circuit, along with a power supply circuit incorporating ferrite beads and varistors, the problems of large size and insufficient accuracy of varistors are solved, achieving miniaturized, high-precision anti-interference protection.
Patent Information
- Application Number
- CN202520130866.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-20
- Publication Date
- 2026-01-13
- Estimated Expiration
- 2035-01-20
AI Technical Summary
In existing digital input circuits, varistors are bulky, making it difficult to meet the miniaturization requirements of electrical equipment. Furthermore, their clamping accuracy is greatly affected by the performance of the components, failing to meet high-precision requirements.
The switching input circuit uses an optocoupler and a clamped diode, combined with a power supply circuit using a ferrite bead and a varistor. It protects subsequent components through current limiting and clamping structures, and uses miniaturized clamped diodes to replace varistors to enhance anti-interference capability.
It achieves miniaturization, low cost, and high anti-interference capability, improves the clamping accuracy and clamping range of the circuit, protects the safety of subsequent components, and simplifies the circuit structure.
Smart Images
Figure CN223797905U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of measurement and control protection technology, and in particular to a protection and measurement device with high anti-interference capability. Background Technology
[0002] In the field of power control, switches such as those in closed and open positions, isolating switches, grounding switches, and circuit breakers require signals to be input into an MCU to achieve automatic opening and closing, power on / off, and other measurement and control functions for the entire system. This process necessitates the use of dedicated digital input circuits to input various signals into the MCU. Existing digital input circuits typically use varistors placed at the signal input front end for clamping, preventing high voltage and surges from affecting subsequent components and ensuring circuit stability and reliability. However, this circuit structure requires significant space due to the large size of the varistor. Furthermore, the clamping effect of the varistor is highly dependent on its own performance, necessitating the selection of more expensive varistors to meet higher precision clamping requirements, which does not meet the demands of miniaturization in electrical equipment. Therefore, a redesign of the digital input circuit is necessary to address these issues. Utility Model Content
[0003] The technical problem to be solved by this utility model is to overcome the shortcomings of the prior art and provide a protection and control device with high anti-interference ability that is simple in structure, small in size, and has good effect.
[0004] The technical solution adopted in this utility model is a protection and control device with high anti-interference capability, including a switch input circuit and a power supply circuit for supplying power to the switch input circuit. The switch input circuit includes a positive input terminal, a negative input terminal, a signal output terminal, and an optocoupler isolator disposed between the positive input terminal, the negative input terminal, and the signal output terminal. The signal output terminal outputs a signal to an external MCU. A first resistor, a second resistor, and a third resistor are connected in series at the positive input terminal. The third resistor is connected to the transmitter of the optocoupler and then to the negative input terminal to form a loop. A first capacitor and a fourth resistor are connected in parallel between the third resistor and the transmitter of the optocoupler. The first capacitor and the fourth resistor are connected in series. The series connection point of the first capacitor and the fourth resistor is connected to the negative input terminal to form a loop. A first clamping diode is connected between the output terminal of the third resistor and the negative input terminal.
[0005] In the above scheme, the forward voltage of the first clamping diode is 75V. Under normal input conditions, the first clamping diode does not conduct; under abnormal input conditions, when the input voltage exceeds the clamping voltage of 75V, the first clamping diode conducts, forming a circuit through the first clamping diode, thereby preventing damage to subsequent components of the switch input circuit. A first resistor, a second resistor, and a third resistor are connected in series at the positive terminal of the input, and the current limiting effect can be achieved through the three resistors. The first resistor, the second resistor, the third resistor, and the first clamping diode together form the voltage and current limiting structure of the switch input circuit, thereby effectively ensuring the safety of subsequent components of the switch input circuit and improving the circuit's anti-interference capability. Moreover, compared with existing varistors, the first clamping diode can set a wider clamping range, thereby improving the application range of clamping, and has high clamping accuracy and good effect. In addition, the first clamping diode is small in size, the overall circuit structure is simple, and the manufacturing cost is low.
[0006] The signal output terminal and the receiving terminal of the optocoupler are connected to the system power supply via a fifth resistor. Therefore, the fifth resistor is used for voltage division and current limiting.
[0007] The power supply circuit includes a DC / DC module. The positive and negative electrodes of the DC / DC module are connected to a 48V voltage. A first varistor is connected between the positive and negative electrodes of the power supply. A first ferrite bead, a unidirectional diode, and a third ferrite bead are connected sequentially from the positive electrode to the positive electrode. A second ferrite bead and the third ferrite bead are connected sequentially from the negative electrode to the negative electrode. A fourth varistor is connected between the output terminals of the first and second ferrite beads. A second capacitor, a third capacitor, a fourth capacitor, and a fifth capacitor are connected in parallel between the positive and negative electrodes. A second varistor and a third varistor are respectively provided at the front ends of the first and second ferrite beads. The other ends of the second and third varistors are connected to the G pin of the DC / DC module and grounded.
[0008] As can be seen from the above scheme, in the power supply circuit, when extreme situations such as surges occur, the first varistor connected between the positive and negative terminals of the power supply clamps the high voltage of the surge within a set range. Rapid clamping is achieved through the first varistor. After passing through the first ferrite bead, and then through the fourth varistor and the second ferrite bead, it is connected to the negative terminal of the power supply. The fourth varistor performs secondary clamping to enhance the anti-interference protection for subsequent power supply circuits. In addition, the second and third varistors eliminate ground interference in the circuit; the first, second, and third ferrite beads eliminate pulse signals in the circuit; the second capacitor performs filtering; and the third, fourth, and fifth capacitors store energy.
[0009] The DC / DC module provides +24V, -24V, +5V, and -5V voltage outputs. Therefore, the DC / DC module can provide different voltage values to meet various power supply voltage requirements.
[0010] A second clamping diode is connected between the +5V and -5V output pins, and a sixth resistor is connected in parallel with the second clamping diode. Here, the second clamping diode clamps the voltage to 6V to prevent sudden voltage output from damaging external devices; the sixth resistor achieves the effect of voltage division and current division. Attached Figure Description
[0011] Figure 1 This is the circuit schematic of the aforementioned switch input circuit;
[0012] Figure 2 This is the circuit diagram of the power supply circuit. Detailed Implementation
[0013] like Figure 1 As shown, a protection and control device with high anti-interference capability includes a digital input circuit and a power supply circuit for supplying power to the digital input circuit. The digital input circuit includes a positive input terminal IN+, a negative input terminal IN-, a signal output terminal YX1, and an optocoupler U1 disposed between the positive input terminal IN+, the negative input terminal IN-, and the signal output terminal YX1. The signal output terminal YX1 outputs a signal to an external MCU. A first resistor R1, a second resistor R2, and a third resistor R3 are connected in series at the positive input terminal IN+. The third resistor R3 is connected to the transmitter of the optocoupler U1 and then to the negative input terminal IN- to form a loop. A first capacitor C1 and a fourth resistor R4 are connected in parallel between the third resistor R3 and the transmitter of the optocoupler U1. The first capacitor C1 and the fourth resistor R4 are connected in series. The series connection point of the first capacitor C1 and the fourth resistor R4 is connected to the negative input terminal IN- to form a loop. A first clamping diode TVS1 is connected between the output terminal of the third resistor R3 and the negative input terminal IN-. The signal output terminal YX1 and the receiving terminal of the optocoupler U1 are connected to the system power supply VCC through the fifth resistor R5.
[0014] When the circuit is subjected to sudden changes such as lightning strikes, the first resistor R1, the second resistor R2, and the third resistor R3 limit the current of the abnormal input, while the first clamping diode TVS1 clamps the input voltage. When the input is higher than 75V, the first clamping diode TVS1 conducts, forming a loop with the negative terminal IN- of the input to release the high voltage. The current flowing through the components in the later stages of the circuit will be minimal, thus avoiding damage from high voltage surges. The first capacitor can absorb fluctuations and achieve filtering, and the fourth resistor R4 can also achieve filtering and voltage division.
[0015] like Figure 2 As shown, the power supply circuit includes a DC / DC module P1, which accepts an input of 18-75V. The positive electrode L and negative electrode N of the DC / DC module P1 are connected to a 48V voltage. A first varistor RT1 is connected between the positive and negative terminals of the power supply. A first ferrite bead FB1, a unidirectional diode D1, and a third ferrite bead LL1 are connected sequentially from the positive terminal to the positive electrode L. A second ferrite bead FB2 and the third ferrite bead LL1 are connected sequentially from the negative terminal to the negative electrode N. A fourth varistor RT4 is connected between the output terminals of the first ferrite bead FB1 and the second ferrite bead FB2. A second capacitor C2, a third capacitor C3, a fourth capacitor C4, and a fifth capacitor C5 are connected in parallel between the positive electrode L and the negative electrode N. A second varistor RT2 and a third varistor RT3 are respectively installed at the front ends of the first ferrite bead FB1 and the second ferrite bead FB2. The combination of the second varistor RT2 and the third varistor RT3 can clamp the voltage to approximately 1000V. The other ends of the second varistor RT2 and the third varistor RT3 are both connected to pin G of the DC / DC module P1 and grounded to PE. The DC / DC module P1 provides +24V, -24V, +5V, and -5V voltage outputs. A second clamping diode TVS2 is connected between the +5V and -5V output pins, and a sixth resistor R6 is connected in parallel with the second clamping diode TVS2.
[0016] Compared with the prior art, the present invention has a simple and reasonable result, small size, wide clamping voltage range, high clamping accuracy, and good clamping effect.
[0017] Finally, it should be emphasized that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. For those skilled in the art, the present utility model can have various changes and modifications. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.
Claims
1. A protection and control device with high anti-interference capability, comprising a switching quantity input circuit and a power supply circuit for supplying power to the switching quantity input circuit, the switching quantity input circuit comprising an input positive terminal (IN+), an input negative terminal (IN-), a signal output terminal (YX1) and an optocoupler isolator (U1) arranged between the input positive terminal (IN+) and the input negative terminal (IN-) and the signal output terminal (YX1), the signal output terminal (YX1) outputting a signal to an external MCU, characterized in that: The input positive terminal (IN+) is connected in series with a first resistor (R1), a second resistor (R2) and a third resistor (R3), the third resistor (R3) is connected to the emitting terminal of the optocoupler isolator (U1) and then to the input negative terminal (IN-) to form a loop, a first capacitor (C1) and a fourth resistor (R4) are also connected in parallel between the third resistor (R3) and the emitting terminal of the optocoupler isolator (U1), the first capacitor (C1) and the fourth resistor (R4) are connected in series, the series connection point of the first capacitor (C1) and the fourth resistor (R4) is connected to the input negative terminal (IN-) to form a loop, and a first clamping diode (TVS1) is connected between the output terminal of the third resistor (R3) and the input negative terminal (IN-).
2. The protection TT&C device with high anti-interference capability according to claim 1, characterized in that, The signal output terminal (YX1) is connected to the receiving terminal of the optocoupler isolator (U1) through a fifth resistor (R5) and a system power supply (VCC).
3. The protection TT&C device with high anti-interference capability according to claim 1, characterized in that, The power supply circuit includes a DC / DC module (P1), the positive electrode (L) and the negative electrode (N) of the DC / DC module (P1) are connected to a 48V voltage, a first varistor (RT1) is connected between the positive and negative electrodes of the power supply, a first magnetic bead (FB1), a unidirectional diode (D1) and a third magnetic bead (LL1) are connected in sequence between the positive electrode (L) of the power supply and the positive electrode (L), a second magnetic bead (FB2) and the third magnetic bead (LL1) are connected in sequence between the negative electrode (N) of the power supply and the negative electrode (N), a fourth varistor (RT4) is connected between the output terminal of the first magnetic bead (FB1) and the output terminal of the second magnetic bead (FB2), a second capacitor (C2), a third capacitor (C3), a fourth capacitor (C4) and a fifth capacitor (C5) are connected in parallel between the positive electrode (L) and the negative electrode (N), a second varistor (RT2) and a third varistor (RT3) are arranged at the front ends of the first magnetic bead (FB1) and the second magnetic bead (FB2) respectively, and the other end of the second varistor (RT2) and the other end of the third varistor (RT3) are connected to the G pin of the DC / DC module (P1) and grounded (PE).
4. The protection TT&C device with high anti-interference capability according to claim 3, characterized in that, The DC / DC module (P1) provides +24V, -24V, +5V and -5V voltage outputs.
5. The protection TT&C device with high anti-interference capability according to claim 4, characterized in that, A second clamping diode (TVS2) is connected between the +5V and -5V output pins, and a sixth resistor (R6) is also connected in parallel with the second clamping diode (TVS2).