Overcurrent protection circuit

Abstract

The utility model discloses an over-current protection circuit, which comprises a reference voltage, a forward over-current protection unit, a reverse over-current protection unit and an over-current filtering unit, the forward overcurrent protection unit comprises a forward filtering module and a forward overcurrent triggering module; the reverse overcurrent protection unit comprises a reverse filtering module and a reverse overcurrent triggering module; the reference voltage provides a forward reference voltage V21 or a reverse reference voltage V31 for the reverse overcurrent trigger module, and the current sampling circuit provides a forward sampling voltage V22 or a reverse sampling voltage V32 for the reverse overcurrent trigger module; and if V22 is greater than V21 or V32 is greater than V31, the overcurrent filtering unit filters the overload current. By arranging the forward and reverse over-current protection unit, over-current protection is immediately carried out on the over-current flowing through the circuit in the forward and reverse directions, and the over-current filtering unit responds in time when over-current exists, so that the damage to electrical components or a circuit board is reduced, and the use safety of the circuit board is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of circuit design, and in particular relates to an overcurrent protection circuit. Background Art

[0002] IGBT (Insulated Gate Bipolar Transistor), insulated gate bipolar transistor, is a composite fully controlled voltage-driven power semiconductor device composed of BJT (bipolar transistor) and MOS (insulated gate field effect transistor). It has the advantages of both MOSFET's high input impedance and GTR's low on-state voltage drop. GTR has low saturation voltage drop and high current density, but high driving current; MOSFET has low driving power and fast switching speed, but high on-state voltage drop and low current density. IGBT combines the advantages of the above two devices, with low driving power and low saturation voltage drop, and is widely used in circuit boards.

[0003] One of the important phenomena of circuit board damage is overcurrent causing device burnout, and some even cause fire and smoke accidents, which can easily lead to subsequent circuit damage. Therefore, power protection is very necessary. However, the traditional use of simple electrical components such as fuses or thermistors for protection is relatively rough. If targeted current detection protection is required, the corresponding circuit structure needs to be designed.

[0004] The prior art generally adopts the current structure disclosed in the prior art, patent CN218850747U, IGBT current protection current. This technology determines whether there is overcurrent by detecting the on-state voltage drop of the IGBT, and turns off the IGBT when there is overcurrent. Since this operation mode requires repeated control of the on and off of the IGBT, the IGBT is prone to damage during use, thereby increasing the cost of maintenance and replacement. In addition, in actual applications, the IGBT is not used independently, and it needs to be connected to multiple electrical components later, including but not limited to single-chip microcomputers. After the IGBT is turned off, it will affect the normal use of subsequent electrical components.

[0005] In order to solve the above problems, designing an overcurrent protection circuit is an important technical problem that those skilled in the art need to solve. Utility Model Content

[0006] The purpose of the utility model is to solve the above problems existing in the prior art and to provide an overcurrent protection circuit.

[0007] The purpose of the utility model is achieved through the following technical solutions:

[0008] An overcurrent protection circuit is electrically connected to the output end of a current sampling circuit; it includes a reference voltage, a forward overcurrent protection unit, a reverse overcurrent protection unit, and an overcurrent filtering unit; the forward overcurrent protection unit includes a forward filtering module and a forward overcurrent triggering module connected to the current sampling circuit and the reference voltage output end; the reference voltage provides a forward reference voltage V21 for the forward overcurrent triggering module, and the current sampling circuit provides a forward sampling voltage V22 for the forward overcurrent triggering module; V22>V21, and the overcurrent filtering unit performs filtering processing on the overload current; the reverse overcurrent protection unit includes a reverse filtering module and a reverse overcurrent triggering module connected to the current sampling circuit and the reference voltage output end; the reference voltage provides a reverse reference voltage V31 for the reverse overcurrent triggering module, and the current sampling circuit provides a reverse sampling voltage V32 for the reverse overcurrent triggering module; V32>V31, and the overcurrent filtering unit performs filtering processing on the overload current.

[0009] Preferably, the current sampling circuit at least includes a sampling terminal IV, the output end of the sampling terminal IV is connected to the anode of the diode D1 and the cathode of the diode A; the cathode of the diode D1 is connected to the forward filtering module, and the anode of the diode A is connected to the reverse filtering module; the output end of the reference voltage is connected in parallel with a resistor R3 and the reverse filtering module.

[0010] Preferably, the forward filtering module includes a resistor R1, a resistor R2, a capacitor C1 and a capacitor C2; wherein the resistor R1 and the capacitor C1 are arranged in parallel at the output end of the diode D1; the resistor R2, the capacitor C2 and the input end of the resistor R5 are arranged in parallel at the output end of the resistor R3; the output ends of the resistor R1, the resistor R2, the capacitor C1 and the capacitor C2 are all grounded; the output end of the resistor R5 is connected in series with the sixth pin of the forward overcurrent trigger module, and the voltage of the sixth pin is the forward reference voltage V21.

[0011] Preferably, the forward overcurrent trigger module includes a first comparator and a diode D2 connected in series therewith; the first comparator includes a fifth pin, a sixth pin and a seventh pin; the voltage at the fifth pin is a sampling voltage V22, and its input end is connected in series with a resistor R4, and the input end of the resistor R4 is connected in parallel with the resistor R1 and the capacitor C1 at the output end of the diode D1; the seventh pin is an output pin and is connected in series with the positive electrode of the diode D2; the negative electrode of the diode D2 is connected to the overcurrent filtering unit.

[0012] Preferably, the reverse filtering module includes capacitor C6, capacitor C5, capacitor C4 and capacitor C3, as well as resistor R6 and resistor R7; wherein, the capacitor C6 and the resistor R3 are arranged in parallel at the output end of the reference voltage, and the output end of the capacitor C6 is arranged in parallel with the capacitor C5, capacitor C4, capacitor C3, resistor R6 and resistor R7; the output end of the capacitor C5 is connected to the negative reference voltage; the resistor R7 and the output end of the capacitor C4 are arranged in parallel with resistor R8 and resistor R10; the output end of the resistor R8 is connected to the negative reference voltage; the diode A and resistor R9 are arranged in parallel with the output end of the resistor R6 and the capacitor C3.

[0013] Preferably, the reverse overcurrent trigger module includes a second comparator and a diode D3 arranged in series therewith; the second comparator includes a third pin connected to the resistor R10, a second pin connected to the resistor R9, a fourth pin connected to the negative reference voltage and a first pin for outputting current voltage; the diode D3 is arranged at the output end of the first pin; the second pin is a reverse sampling voltage V32; the third pin is a reverse reference voltage V31; the diode D3 is arranged in parallel with the diode D2, and the output ends of both are connected to the overcurrent filtering unit.

[0014] Preferably, the overcurrent filtering unit includes a resistor R11 connected in series with the output ends of the diode D3 and the diode D2, a resistor R12 and a photoelectric coupler arranged in parallel at the output end of the resistor R11, and a filtering module arranged at the output end of the photoelectric coupler and an OC terminal for connecting to a single-chip microcomputer.

[0015] Preferably, the photoelectric coupler includes a light emitting diode and an amplifier; the light emitting diode is arranged in parallel with the resistor R12, and the output ends of both are grounded; the light emitting diode lights up and transmits the optical signal to the base of the amplifier, the collector of the amplifier is connected to a 5V voltage, and its emitter is provided with the filter module and the OC terminal.

[0016] Preferably, the filtering module includes a resistor R13 and a capacitor C7 connected in parallel, and the OC terminal; the output ends of the resistor R13 and the capacitor C7 are grounded.

[0017] The advantages of the technical solution of the utility model are mainly reflected in:

[0018] By arranging a forward overcurrent protection unit and a reverse overcurrent protection unit at the output end of the sampling circuit, overcurrent protection is immediately performed on the overload current flowing through the circuit in the forward and reverse directions, and the overcurrent filter unit reacts in time when overcurrent exists, effectively preventing the forward and reverse current from overflowing, causing damage to the electrical components connected to the sampling circuit, or damaging the circuit board, thereby improving the safety of the circuit board and the electrical components thereon;

[0019] The forward or reverse overload current flowing into the circuit is filtered through the forward filter module and the reverse filter module, and the overload current is reduced while ensuring the stability of the current input into the forward overcurrent trigger module or the reverse overcurrent trigger module, thereby improving the circuit's anti-interference ability;

[0020] A photocoupler is set in the overcurrent filtering unit, in which the light-emitting diode can be triggered when there is an overload current to prompt the outside world that there is an overcurrent phenomenon in the current circuit. At the same time, the overload current will turn on the transistor, and the output of the transistor will be filtered. Finally, the filtered current will be input into the microcontroller to ensure the stable input of the current signal and further enhance the anti-interference performance of the current. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 : Circuit structure diagram of the preferred embodiment of the utility model. DETAILED DESCRIPTION

[0022] The purpose, advantages and features of the present invention will be illustrated and explained through the non-limiting description of the following preferred embodiments. These embodiments are only typical examples of the application of the technical solution of the present invention, and any technical solution formed by equivalent replacement or equivalent transformation falls within the scope of protection claimed by the present invention.

[0023] In the description of the scheme, it should be noted that the terms "center", "up", "down", "left", "right", "front", "back", "vertical", "horizontal", "inside", "outside" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of description and simplified description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance. Moreover, in the description of the scheme, with the operator as a reference, the direction close to the operator is the proximal end, and the direction away from the operator is the distal end.

[0024] The utility model discloses an overcurrent protection circuit, which is electrically connected to the output end of a current sampling circuit; the current sampling circuit at least includes a sampling terminal IV, the output end of the sampling terminal IV is connected to the positive pole of a diode D1 and the negative pole of a diode A; the negative pole of the diode D1 is connected to a forward filtering module 21 of a forward overcurrent protection unit 2, and the positive pole of the diode A is connected to a reverse filtering module 31 of a reverse overcurrent protection unit 3. When the sampling circuit outputs a forward current, the forward overcurrent protection unit works, determines whether the current is overloaded, and performs subsequent processing; when the sampling circuit outputs a reverse current, the reverse overcurrent protection unit works, determines whether the current is overloaded, and performs subsequent processing, effectively preventing the forward and reverse currents from overflowing, causing damage to the electrical components connected to the sampling circuit, or damaging the circuit board, and improving the safety of the circuit board and the electrical components thereon.

[0025] The overcurrent protection circuit specifically includes a reference voltage 1, a forward overcurrent protection unit 2, a reverse overcurrent protection unit 3, and an overcurrent filter unit 4. Among them, in the present application, the reference voltage 1 is preferably designed to be a voltage of 15V. In other embodiments, its voltage value can be adjusted according to the use requirements, which is not limited here. The output end of the reference voltage is connected in parallel with a resistor R3 and the reverse filter module 31. The forward overcurrent protection unit 2 and the reverse current protection unit 3 are connected in parallel to the output end of the reference voltage 1, and one of them works at a certain time point, that is, the forward overcurrent protection unit 2 and the reverse overcurrent protection unit 3 monitor in real time whether the forward or reverse current output from the sampling terminal IV is overloaded, thereby improving the safety of use.

[0026] The forward overcurrent protection unit 2 includes a forward filter module 21 and a forward overcurrent trigger module 22 connected to the cathode of the diode D1 at the output end of the current sampling circuit and the output end of the reference voltage 1. The reference voltage 1 provides a forward reference voltage V21 for the forward overcurrent trigger module 22, and the current sampling circuit provides a forward sampling voltage V22 for the forward overcurrent trigger module 22. When V22>V21, it indicates that the current output by the current sampling circuit is overloaded, and then the overcurrent filter unit 4 performs filtering on the overload current.

[0027] Specifically, the forward filtering module 21 includes a resistor R1, a resistor R2, a capacitor C1 and a capacitor C2. The resistor R1 and the capacitor C1 are arranged in parallel at the output end of the diode D1; and the output ends of the two are connected in series with the resistor R4. The input end of the resistor R2, the capacitor C2 and the resistor R5 are arranged in parallel at the output end of the resistor R3; the output ends of the resistor R1, the resistor R2, the capacitor C1 and the capacitor C2 are all grounded. The output end of the resistor R5 is connected in series with the sixth pin of the forward overcurrent trigger module 22, and the voltage of the sixth pin is the forward reference voltage V21.

[0028] Further, the forward overcurrent trigger module 22 includes a first comparator 221 and a diode D2 connected in series therewith. The first comparator 221 includes a fifth pin, a sixth pin and a seventh pin. The voltage at the fifth pin is a sampling voltage V22, and its input end is connected in series with the resistor R4, and the input end of the resistor R4 is connected in parallel with the resistor R1 and the capacitor C1 at the output end of the diode D1. The seventh pin is an output pin and is connected in series with the positive electrode of the diode D2. The negative electrode of the diode D2 is connected to the overcurrent filter unit 4. The input current signal is filtered by the forward filter module 21, which effectively improves the anti-interference ability of the circuit.

[0029] The reverse overcurrent protection unit 3 includes a reverse filtering module 31 and a reverse overcurrent triggering module 32 connected to the current sampling circuit and the output end of the reference voltage 1. The reference voltage provides a reverse reference voltage V31 for the reverse overcurrent triggering module 32, and the current sampling circuit provides a reverse sampling voltage V32 for the reverse overcurrent triggering module 32. When V32>V31, it indicates that the current output by the current sampling circuit is overloaded, and then the overcurrent filtering unit 4 performs filtering on the overload current.

[0030] Specifically, the reverse filtering module 31 includes capacitor C6, capacitor C5, capacitor C4 and capacitor C3, as well as resistor R6 and resistor R7. The capacitor C6 and the resistor R3 are arranged in parallel at the output end of the reference voltage, and the output end of the capacitor C6 is provided with the capacitor C5, capacitor C4, capacitor C3, resistor R6 and resistor R7 in parallel. The output end of the capacitor C5 is connected to the negative reference voltage, and the negative reference voltage is preferably -15V. In other embodiments, the voltage value of the negative reference voltage can be adjusted according to demand, which is not limited here. The output end of the resistor R7 and the capacitor C4 is provided with resistor R8 and resistor R10 in parallel; wherein the output end of the resistor R8 is connected to the negative reference voltage. The output end of the resistor R10 is connected to the third pin of the reverse overcurrent trigger module 32. The output end of the resistor R6 and the capacitor C3 is provided with the diode A and resistor R9 in parallel.

[0031] Furthermore, the reverse overcurrent trigger module 32 includes a second comparator 321 and a diode D3 connected in series therewith. The second comparator 321 includes a third pin connected to the resistor R10, a second pin connected to the resistor R9, a fourth pin connected to the negative reference voltage, and a first pin for outputting current and voltage. The diode D3 is provided at the output end of the first pin. The second pin is a reverse sampling voltage V32. The third pin is a reverse reference voltage V31. The diode D3 is provided in parallel with the diode D2, and the output ends of both are connected to the overcurrent filter unit 4. The input current signal is filtered by the reverse filter module 31, thereby effectively improving the anti-interference ability of the circuit.

[0032] The overcurrent filter unit 4 includes a resistor R11 connected in series with the output ends of the diode D3 and the diode D2, a resistor R12 and a photoelectric coupler 41 arranged in parallel at the output end of the resistor R11, and a filter module 42 arranged at the output end of the photoelectric coupler 41 and an OC terminal for connecting a single-chip microcomputer. Specifically, the photoelectric coupler 41 includes a light-emitting diode and an amplifier. The light-emitting diode is arranged in parallel with the resistor R12, and the output ends of both are grounded. The light-emitting diode lights up, and converts the optical signal into an electrical signal and transmits it to the base of the amplifier. The collector of the amplifier is connected to a 5V voltage, and its emitter is provided with the filter module 42 and the OC terminal.

[0033] Furthermore, the filtering module 42 includes a resistor R13 and a capacitor C7 connected in parallel, and the OC terminal; the output ends of the resistor R13 and the capacitor C7 are grounded.

[0034] When the overloaded current passes through the resistor R11 in the overcurrent filter unit 4, the current will be reduced, and then the current will be shunted through the resistor R12 and the photoelectric coupler 41 to further reduce the current; finally, the current output from the photoelectric coupler 41 is filtered by the filter module 42 to further improve the anti-interference ability of the circuit. The overall circuit adopts conventional electrical components for series-parallel design, with a simple structure and low design and production cost.

[0035] When V22>V21, or V32>V31, the forward overcurrent protection unit 2 or the reverse overcurrent protection unit 3 will output a high-level signal (sampling current voltage) to the overcurrent filter unit 4. At this time, it indicates that the current current has an overcurrent phenomenon, and the light-emitting diode in the photoelectric coupler 41 is turned on and emits light, and at the same time, the light signal is transmitted to the transistor, and the output of the transistor is filtered and processed. Finally, the current after filtering will be input to the single-chip microcomputer connected to the OC terminal to ensure the stable input of the current signal and further enhance the anti-interference performance of the current. Otherwise, the forward overcurrent protection unit 2 or the reverse overcurrent protection unit 3 will output a low-level signal (reference current voltage) to the overcurrent filter unit 4, indicating that the current current does not have an overcurrent phenomenon, the light-emitting diode in the photoelectric coupler 41 is not turned on, and the single-chip microcomputer connected to the OC terminal will be driven to work by other circuit structures, which will not be repeated here.

[0036] There are many implementation methods of the utility model, and all technical solutions formed by equivalent transformation or equivalent transformation fall within the protection scope of the utility model.

Claims

1. An overcurrent protection circuit, electrically connected to the output end of the current sampling circuit; characterized in that: The invention comprises a reference voltage (1), a forward overcurrent protection unit (2), a reverse overcurrent protection unit (3), and an overcurrent filtering unit (4); the forward overcurrent protection unit (2) comprises a forward filtering module (21) and a forward overcurrent triggering module (22) connected to the current sampling circuit and the output end of the reference voltage (1); the reference voltage (1) provides a forward reference voltage V21 for the forward overcurrent triggering module (22), and the current sampling circuit provides a forward sampling voltage V22 for the forward overcurrent triggering module (22); V22>V2 1, the overcurrent filtering unit (4) performs filtering processing on the overload current; the reverse overcurrent protection unit (3) comprises a reverse filtering module (31) and a reverse overcurrent triggering module (32) connected to the current sampling circuit and the output end of the reference voltage (1); the reference voltage provides a reverse reference voltage V31 for the reverse overcurrent triggering module (32), and the current sampling circuit provides a reverse sampling voltage V32 for the reverse overcurrent triggering module (32); V32>V31, and the overcurrent filtering unit (4) performs filtering processing on the overload current.

2. The overcurrent protection circuit according to claim 1, characterized in that: The current sampling circuit comprises at least a sampling terminal IV, the output end of the sampling terminal IV being connected to the anode of a diode D1 and the cathode of a diode A; the cathode of the diode D1 being connected to the forward filtering module (21), the anode of the diode A being connected to the reverse filtering module (31); and the output end of the reference voltage (1) being provided with a resistor R3 and the reverse filtering module (31) in parallel.

3. The overcurrent protection circuit according to claim 2, characterized in that: The forward filtering module (21) comprises a resistor R1, a resistor R2, a capacitor C1 and a capacitor C2; wherein the resistor R1 and the capacitor C1 are arranged in parallel at the output end of the diode D1; the resistor R2, the capacitor C2 and the input end of the resistor R5 are arranged in parallel at the output end of the resistor R3; the output ends of the resistor R1, the resistor R2, the capacitor C1 and the capacitor C2 are all grounded; the output end of the resistor R5 is connected in series with the sixth pin of the forward overcurrent trigger module (22), and the voltage of the sixth pin is the forward reference voltage V21.

4. The overcurrent protection circuit according to claim 3, characterized in that: The forward overcurrent trigger module (22) comprises a first comparator (221) and a diode D2 connected in series therewith; the first comparator (221) comprises a fifth pin, a sixth pin and a seventh pin; the voltage at the fifth pin is a sampling voltage V22, the input end of which is connected in series with a resistor R4, the input end of the resistor R4 is connected in parallel with the resistor R1 and the capacitor C1 to the output end of the diode D1; the seventh pin is an output pin and is connected in series with the positive electrode of the diode D2; the negative electrode of the diode D2 is connected to the overcurrent filtering unit (4).

5. The overcurrent protection circuit according to claim 4, characterized in that: The reverse filtering module (31) comprises a capacitor C6, a capacitor C5, a capacitor C4 and a capacitor C3, and a resistor R6 and a resistor R7; wherein the capacitor C6 and the resistor R3 are arranged in parallel at the output end of the reference voltage, and the output end of the capacitor C6 is provided with the capacitor C5, the capacitor C4, the capacitor C3, the resistor R6 and the resistor R7 in parallel; the output end of the capacitor C5 is connected to the negative reference voltage; the resistor R7 and the output end of the capacitor C4 are provided with resistors R8 and R10 in parallel; the output end of the resistor R8 is connected to the negative reference voltage; the diode A and the resistor R9 are provided in parallel with the output end of the resistor R6 and the capacitor C3.

6. The overcurrent protection circuit according to claim 5, characterized in that: The reverse overcurrent trigger module (32) comprises a second comparator (321) and a diode D3 connected in series therewith; the second comparator (321) comprises a third pin connected to the resistor R10, a second pin connected to the resistor R9, a fourth pin connected to the negative reference voltage, and a first pin for outputting current and voltage; the diode D3 is provided at the output end of the first pin; the second pin is a reverse sampling voltage V32; the third pin is a reverse reference voltage V31; the diode D3 is provided in parallel with the diode D2, and the output ends of both are connected to the overcurrent filtering unit (4).

7. The overcurrent protection circuit according to claim 6, characterized in that: The overcurrent filtering unit (4) comprises a resistor R11 connected in series with the diode D3 and the output end of the diode D2, a resistor R12 and a photoelectric coupler (41) arranged in parallel at the output end of the resistor R11, and a filtering module (42) arranged at the output end of the photoelectric coupler (41) and an OC terminal for connecting to a single-chip microcomputer.

8. The overcurrent protection circuit according to claim 7, characterized in that: The photoelectric coupler (41) comprises a light emitting diode and an amplifier; the light emitting diode is arranged in parallel with the resistor R12, and the output ends of both are grounded; the light emitting diode lights up and transmits the optical signal to the base of the amplifier; the collector of the amplifier is connected to a 5V voltage, and the emitter is provided with the filter module (42) and an OC terminal.

9. The overcurrent protection circuit according to claim 8, characterized in that: The filtering module (42) comprises a resistor R13 and a capacitor C7, which are arranged in parallel, and the OC terminal; the output ends of the resistor R13 and the capacitor C7 are grounded.

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