Overcurrent protection circuit and system

Abstract

The utility model discloses an overcurrent protection circuit and system, and relates to the technical field of power electronics, a current detection device can collect current of a circuit to be detected and convert the current into linearly dependent voltage, an operational amplifier circuit can amplify the voltage, and the operational amplifier circuit is connected with the current detection device. When the amplified voltage value is larger than a first reference voltage value provided by the first reference module, the positive comparison circuit outputs a preset level signal of a first preset time, and when the amplified voltage value is smaller than a second reference voltage value provided by the second reference module, the negative comparison circuit outputs a preset level signal of a second preset time. Therefore, the controller has enough time to receive the preset level signal and carries out blocking driving after receiving the preset level signal, so that the current value of the circuit side to be detected is reduced, and over-current protection is accurately realized.

Description

Technical Field

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

[0002] For the bidirectional current sampling circuits currently on the market, the controller is directly connected to the bidirectional current sampling circuit and obtains the current value and current overcurrent condition collected by the bidirectional current sampling circuit. However, this traditional method is easily interfered with and falsely triggered, or triggered and then quickly restored, which results in the controller not having enough time to sense the current overcurrent condition and failing to block the drive in time, resulting in excessive stress on the switching device and damage to the machine. Utility Model Content

[0003] The purpose of the utility model is to provide an overcurrent protection circuit and system. In this solution, the controller has enough time to receive a preset level signal, and performs a blocking drive after receiving the preset level signal to reduce the current value on the circuit side to be tested and accurately implement overcurrent protection.

[0004] In order to solve the above technical problems, the utility model provides an overcurrent protection circuit, comprising:

[0005] A current detection device, the input end of which is connected to the circuit to be tested, and is used to collect the current on the circuit to be tested and convert the current into a voltage, wherein the voltage is linearly related to the current;

[0006] An operational amplifier circuit, wherein the positive input terminal and the negative input terminal of the operational amplifier circuit are both connected to the current detection circuit, and are used to linearly amplify the voltage, wherein the minimum value of the amplified voltage value corresponding to the positive current is greater than the maximum value of the amplified voltage value corresponding to the negative current, and the amplified voltage values ​​are all positive values;

[0007] A positive comparison circuit, wherein the negative phase input terminal of the positive comparison circuit is connected to the output terminal of the operational amplifier circuit, the positive phase input terminal of the positive comparison circuit is connected to the first reference module, and the output terminal of the positive comparison circuit is connected to the controller, and is used to output a preset level signal of a first preset time to the controller when the amplified voltage value is greater than the first reference voltage value provided by the first reference module, so that the controller performs blocking driving after receiving the preset level signal;

[0008] A negative comparison circuit, wherein the positive input terminal of the negative comparison circuit is connected to the output terminal of the operational amplifier circuit, the negative input terminal of the negative comparison circuit is connected to the second reference module, and the output terminal of the negative comparison circuit is connected to the controller, and is used to output the preset level signal of the second preset time to the controller when the amplified voltage value is less than the second reference voltage value provided by the second reference module, so that the controller performs blocking driving after receiving the preset level signal; the first reference voltage value is greater than the second reference voltage value.

[0009] Optionally, the current detection device includes:

[0010] A current transformer, wherein the primary winding of the current transformer is connected in series in the circuit to be tested, and is used to sense the current in the circuit to be tested;

[0011] A first resistor, wherein a first end of the first resistor is connected to a first end of a secondary winding of the current transformer and a positive phase input end of the operational amplifier circuit, and a second end of the first resistor is respectively connected to a second end of the secondary winding, a ground wire, and a negative phase input end of the operational amplifier circuit, for collecting the current and converting the current into the voltage.

[0012] Optionally, the operational amplifier circuit includes:

[0013] a second resistor, wherein a first end of the second resistor is connected to a first end of the first resistor, and a second end of the second resistor is connected to a non-inverting input end of the operational amplifier;

[0014] a third resistor, wherein a first end of the third resistor is connected to a second end of the first resistor, and a second end of the third resistor is connected to a negative phase input end of the operational amplifier;

[0015] The operational amplifier, the output end of the operational amplifier is respectively connected to the first end of the fourth resistor, the negative phase input end of the positive comparison circuit and the positive phase input end of the negative comparison circuit, for linearly amplifying the voltage;

[0016] The fourth resistor, a second end of the fourth resistor is connected to the first end of the first capacitor;

[0017] a fifth resistor, wherein a first end of the fifth resistor is connected to the second end of the first capacitor, and a second end of the fifth resistor is connected to the first reference power supply;

[0018] The first capacitor, a second end of the first capacitor is connected to the second end of the second resistor;

[0019] a second capacitor, the second capacitor being connected in parallel with the fourth resistor;

[0020] A third capacitor is connected in parallel with the fifth resistor.

[0021] Optionally, the forward comparison circuit comprises:

[0022] a sixth resistor, wherein a first end of the sixth resistor is connected to the output end of the operational amplifier circuit, and a second end of the sixth resistor is connected to the negative phase input end of the first comparator;

[0023] The first comparator, the non-inverting input terminal of the first comparator is connected to the first reference module, and the output terminal of the first comparator is connected to the first reference module and the controller respectively, and is used to output the preset level signal of the first preset time to the controller when the amplified voltage value is greater than the first reference voltage value, so that the controller performs blocking driving after receiving the preset level signal;

[0024] A fourth capacitor, wherein a first end of the fourth capacitor is connected to the negative phase input end of the first comparator, and a second end of the fourth capacitor is grounded.

[0025] Optionally, the method further includes: the first reference module; wherein the first reference module includes:

[0026] a seventh resistor, wherein a first end of the seventh resistor is connected to a second reference power supply, and a second end of the seventh resistor is respectively connected to a non-inverting input end of the first comparator, a first end of an eighth resistor, and a first end of a ninth resistor, and is used for converting a voltage at the second end of the seventh resistor from a first threshold voltage to a second threshold voltage after the first comparator outputs the preset level signal, wherein the first threshold voltage is greater than the second threshold voltage, and when the first comparator outputs the preset level signal, the first threshold voltage is less than the amplified voltage value;

[0027] The eighth resistor, a second end of the eighth resistor is grounded;

[0028] The ninth resistor, a second end of the ninth resistor is connected to the output end of the first comparator;

[0029] A fifth capacitor is connected in parallel with the eighth resistor.

[0030] Optionally, the negative comparison circuit includes:

[0031] A second comparator, wherein the positive input terminal of the second comparator is connected to the second end of the sixth resistor, the negative input terminal of the second comparator is connected to the second reference module, and the output terminal is connected to the controller, and is used for outputting the preset level signal of the second preset time to the controller when the amplified voltage value is less than the second reference voltage value provided by the second reference module, so that the controller performs blocking driving after receiving the preset level signal.

[0032] Optionally, the method further includes: a second reference module; wherein the second reference module includes:

[0033] a tenth resistor, wherein a first end of the tenth resistor is connected to the negative phase input end of the second comparator, and a second end of the tenth resistor is connected to the third reference power supply;

[0034] A PNP transistor, the emitter of which is connected to the second end of the tenth resistor;

[0035] an eleventh resistor, a first end of the eleventh resistor being connected to the negative phase input end of the second comparator, and a second end of the eleventh resistor being connected to the collector of the PNP transistor;

[0036] a diode, wherein the anode of the diode is connected to the base of the PNP transistor, and the cathode of the diode is connected to the fourth reference power supply;

[0037] a twelfth resistor, wherein a first end of the twelfth resistor is respectively connected to a first end of the tenth resistor, a first end of the eleventh resistor and a negative phase input end of the second comparator, and a second end of the twelfth resistor is grounded, and is used for converting a voltage at the first end of the twelfth resistor from a third threshold voltage to a fourth threshold voltage when the output end of the second comparator outputs the preset level signal, the third threshold voltage is less than the fourth threshold voltage, and when the second comparator outputs the preset level signal, the third threshold voltage is greater than the amplified voltage value;

[0038] A sixth capacitor is connected in parallel with the twelfth resistor.

[0039] Optionally, the second reference module further includes:

[0040] a thirteenth resistor, a first end of the thirteenth resistor being connected to the base of the PNP transistor, and a second end of the thirteenth resistor being connected to the anode of the diode;

[0041] A fourteenth resistor, wherein a first end of the fourteenth resistor is connected to the cathode of the diode, and a second end of the fourteenth resistor is connected to the fourth reference power supply.

[0042] Optionally, also include:

[0043] a fifteenth resistor, wherein a first end of the fifteenth resistor is respectively connected to the output end of the positive comparison circuit and the output end of the negative comparison circuit, and a second end of the fifteenth resistor is respectively connected to the first end of the seventh capacitor and the controller;

[0044] The seventh capacitor, a second end of the seventh capacitor is grounded.

[0045] In order to solve the above technical problems, the utility model also provides an overcurrent protection system, comprising: the overcurrent protection circuit and the controller as described above, wherein the overcurrent protection circuit is connected to the controller.

[0046] The purpose of the utility model is to provide an overcurrent protection circuit and system, wherein a current detection device can collect the current of a circuit to be tested and convert the current into a linearly related voltage, an operational amplifier circuit can amplify this part of the voltage, when the amplified voltage value is greater than a first reference voltage value provided by a first reference module, a positive comparison circuit will output a preset level signal for a first preset time, and when the amplified voltage value is less than a second reference voltage value provided by a second reference module, a negative comparison circuit will output a preset level signal for a second preset time, so that a controller has enough time to receive the preset level signal, and performs a blocking drive after receiving the preset level signal, so as to reduce the current value on the side of the circuit to be tested and accurately realize overcurrent protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0048] Figure 1 A schematic diagram of the structure of an overcurrent protection circuit provided by the utility model;

[0049] Figure 2 This is a structural schematic diagram of another overcurrent protection circuit provided by the utility model. DETAILED DESCRIPTION

[0050] The core of the utility model is to provide an overcurrent protection circuit and system. In this solution, the controller has enough time to receive a preset level signal, and performs a blocking drive after receiving the preset level signal to reduce the current value on the circuit side to be tested and accurately implement overcurrent protection.

[0051] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0052] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of an overcurrent protection circuit provided by the utility model. The circuit includes:

[0053] A current detection device 1, the input end of which is connected to the circuit to be tested, for collecting the current on the circuit to be tested and converting the current into a voltage, wherein the voltage is linearly related to the current;

[0054] Operational amplifier circuit 2, the positive phase input terminal and the negative phase input terminal of the operational amplifier circuit 2 are connected to the current detection circuit, and are used to linearly amplify the voltage, the minimum value of the amplified voltage value corresponding to the positive current is greater than the maximum value of the amplified voltage value corresponding to the negative current, and the amplified voltage values ​​are all positive values;

[0055] A positive comparison circuit 3, wherein the negative phase input terminal of the positive comparison circuit 3 is connected to the output terminal of the operational amplifier circuit 2, the positive phase input terminal of the positive comparison circuit 3 is connected to the first reference module, and the output terminal of the positive comparison circuit 3 is connected to the controller, and is used to output a preset level signal of a first preset time to the controller when the amplified voltage value is greater than the first reference voltage value provided by the first reference module, so that the controller performs blocking driving after receiving the preset level signal;

[0056] A negative comparison circuit 4, wherein the positive input terminal of the negative comparison circuit 4 is connected to the output terminal of the operational amplifier circuit 2, the negative input terminal of the negative comparison circuit 4 is connected to the second reference module, and the output terminal of the negative comparison circuit 4 is connected to the controller, and is used to output a preset level signal of a second preset time to the controller when the amplified voltage value is less than the second reference voltage value provided by the second reference module, so that the controller performs a blocking drive after receiving the preset level signal; the first reference voltage value is greater than the second reference voltage value.

[0057] In the utility model, the current detection device 1 can collect the current on the circuit to be tested and convert it into a voltage. Because the current includes a positive current and a negative current, the voltage corresponding to the current also includes a positive voltage and a negative voltage. In order to realize protection when an overcurrent condition (positive overcurrent and negative overcurrent) occurs in the circuit to be tested, the operational amplifier circuit 2 is required to amplify the voltage so that the amplified voltage values ​​output by the operational amplifier circuit 2 can all be positive values. At this time, the forward comparison circuit 3 can compare the amplified voltage value and the first reference voltage value provided by the first reference module to determine whether the circuit to be tested is in a forward overcurrent state. When the first reference voltage value is less than the amplified voltage value, the circuit to be tested is in a forward overcurrent state. In the overcurrent state, the positive comparison circuit 3 outputs a preset level signal, and the preset level signal will last for a first preset time; similarly, the negative comparison circuit 4 can compare the amplified voltage value and the second reference voltage value provided by the second reference module to determine whether the circuit to be tested is in a negative overcurrent state. When the second reference voltage value is greater than the amplified voltage value, the circuit to be tested is in a negative overcurrent state, and the negative comparison circuit 4 outputs a preset level signal, and the preset level signal will last for a second preset time. Therefore, when the circuit to be tested is in an overcurrent state, the controller has enough time to receive the preset level signal, and performs a blocking drive after receiving the preset level signal to reduce the current value on the circuit to be tested side and accurately implement overcurrent protection.

[0058] It should be noted that this overcurrent protection circuit collects the high-voltage side current through a current transformer, and then transmits the overcurrent signal to the controller through circuits such as an op amp and a comparator, and adds a hysteresis interval to the overcurrent protection threshold, so that the controller has enough time to recognize the conversion of high and low levels, thereby effectively blocking and releasing the drive, and has strong anti-interference ability. In addition, this overcurrent protection circuit blocks the drive through the controller, and the signal transmission delay is small, which reduces the maximum current after the overcurrent, thereby reducing the stress of the switch tube and playing a certain protective role on the device itself.

[0059] The present embodiment provides an overcurrent protection circuit, wherein a current detection device 1 can collect the current of a circuit to be tested and convert the current into a linearly related voltage, an operational amplifier circuit 2 can amplify this voltage, when the amplified voltage value is greater than a first reference voltage value provided by a first reference module, a positive comparison circuit 3 will output a preset level signal for a first preset time, and when the amplified voltage value is less than a second reference voltage value provided by a second reference module, a negative comparison circuit 4 will output a preset level signal for a second preset time, so that the controller has enough time to receive the preset level signal, and performs a blocking drive after receiving the preset level signal, so as to reduce the current value on the circuit to be tested side and accurately implement overcurrent protection.

[0060] Based on the above embodiments:

[0061] As an optional embodiment, the current detection device 1 includes:

[0062] A current transformer, the primary winding of which is connected in series in the circuit to be tested, and is used to sense the current in the circuit to be tested;

[0063] A first resistor R1, a first end of the first resistor R1 is connected to a first end of a secondary winding of a current transformer and a positive phase input end of an operational amplifier circuit 2, and a second end of the first resistor R1 is respectively connected to a second end of the secondary winding, a ground wire and a negative phase input end of the operational amplifier circuit 2, for collecting current and converting the current into voltage.

[0064] In the utility model, the current detection device 1 includes: a current transformer and a first resistor R1, wherein the current transformer is connected in series in the circuit to be measured, and senses the current of the circuit to be measured through the primary winding and the secondary winding. Since the first resistor R1 is arranged at both ends of the secondary winding of the current transformer, the voltage across the first resistor R1 is the voltage corresponding to the current collected by itself, and the current on the circuit to be measured is accurately collected and converted into voltage.

[0065] It should be noted that the overcurrent protection circuit is Figure 2 As shown: the primary side of the current transformer reduces the high-voltage side current of the circuit to be tested (high-voltage side power circuit) by N times and transmits it to the secondary side of the current transformer, then flows through the first resistor R1 to become a differential voltage, is amplified or reduced by the operational amplifier circuit 2, and then sent to the first comparator and the second comparator. Because the high-voltage side current has positive and negative directions, it is necessary to protect both positive and negative overcurrents in a timely manner, so two comparator modules are required. When there is a positive overcurrent, the voltage at the negative input terminal of the first comparator will exceed the voltage at the positive input terminal, and the voltage sent to the controller (MCU, Microcontroller Unit) will drop from a high level to a low level. At this time, the controller will block the drive inside the chip, so that the high-voltage side current gradually decreases, and the sampling voltage of the current conversion will also decrease accordingly. At this time, the voltage at the positive input terminal of the first comparator will also decrease. When the current drops to a very small level, the output voltage of the first comparator will flip back from a low level to a high level again. This is a typical hysteresis circuit design. When negative overcurrent occurs, the voltage at the negative input terminal of the second comparator will exceed the voltage at the positive input terminal, and the voltage sent to the controller will drop from a high level to a low level. At this time, the controller will block the drive inside the chip, causing the current on the high-voltage side to gradually decrease. The sampling voltage of the current conversion will increase accordingly, and the voltage at the positive input terminal of the second comparator will increase. When the current drops to a very small level, the output voltage of the second comparator will flip back from a low level to a high level again.

[0066] It should also be noted that a PNP transistor and a diode are used in the negative overcurrent protection circuit. The purpose is that when the output voltage of the second comparator is high, the transistor and the diode will not work, and the voltage potential of the positive input terminal of the comparator is fixed; when the output voltage of the second comparator is low, the transistor and the diode will work, and the voltage of the positive input terminal of the comparator will increase (the voltage across the first capacitor C1), so that the overcurrent threshold will produce a hysteresis interval. That is to say, when a negative overcurrent occurs, the controller blocks the drive after receiving a low level. Only when the current sampling voltage rises to a level higher than the voltage across the first capacitor C1, the signal received by the controller will flip back to a high level, and the drive can be unblocked. The key point of this circuit is that the hysteresis circuit is added to both the positive overcurrent and the negative overcurrent, so that the controller has enough time to receive the overcurrent signal (low level) to prevent the overcurrent signal from flipping to a low level and then quickly flipping back to a high level, which will cause the controller to fail to block the drive in time, causing the switch device to be damaged by excessive stress.

[0067] As an optional embodiment, the operational amplifier circuit 2 includes:

[0068] a second resistor R2, wherein a first end of the second resistor R2 is connected to a first end of the first resistor R1, and a second end of the second resistor R2 is connected to a non-inverting input end of the operational amplifier;

[0069] a third resistor R3, wherein a first end of the third resistor R3 is connected to a second end of the first resistor R1, and a second end of the third resistor R3 is connected to a negative phase input end of the operational amplifier;

[0070] An operational amplifier, wherein the output end of the operational amplifier is respectively connected to the first end of the fourth resistor R4, the negative phase input end of the positive comparison circuit 3 and the positive phase input end of the negative comparison circuit 4, for linearly amplifying the voltage;

[0071] a fourth resistor R4, wherein a second end of the fourth resistor R4 is connected to a first end of the first capacitor C1;

[0072] a fifth resistor R5, wherein a first end of the fifth resistor R5 is connected to the second end of the first capacitor C1, and a second end of the fifth resistor R5 is connected to the first reference power supply;

[0073] A first capacitor C1, a second end of the first capacitor C1 is connected to a second end of the second resistor R2;

[0074] A second capacitor C2, the second capacitor C2 is connected in parallel with a fourth resistor R4;

[0075] The third capacitor C3 is connected in parallel with the fifth capacitor C5.

[0076] In the utility model, the operational amplifier circuit 2 includes: a second resistor R2, a third resistor R3, an operational amplifier, a fourth resistor R4, a fifth resistor R5, a first capacitor C1, a second capacitor C2 and a third capacitor C3, wherein the present application changes the feedback resistance of the operational amplifier by changing the parameters of the second resistor R2, the third resistor R3, the fourth resistor R4, the fifth resistor R5, the first capacitor C1, the second capacitor C2 and the third capacitor C3, and the voltage values ​​output by the operational amplifier are all positive values ​​by changing the feedback resistance.

[0077] It should be noted that, because there are positive currents and negative currents, the voltage corresponding to the current has positive voltages and negative voltages. For example, if the voltage range of the negative voltage after amplification is -1.5V-0V, and the voltage range of the positive voltage after amplification is 0-1.5V, in order to ensure that the voltage output by the operational amplifier is positive, the second resistor R2, the third resistor R3, the fourth resistor R4 and the fifth resistor R5 are introduced as feedback resistors of the operational amplifier, so that the voltage range of the negative voltage after amplification is 0-1.5V, and the voltage range of the positive voltage after amplification is 0-1.5V. The voltage range is 1.5-3V. When the resistance value of the second resistor R2 is equal to (=) the resistance value of the third resistor R3, and the resistance value of the fourth resistor R4 is equal to (=) the resistance value of the fifth resistor R5, the output voltage Vo of the operational amplifier is Vo=(R5 / R2)*(Iin*R1 / N)+V1, where N is the current transformer ratio, Iin is the current collected by the first resistor R1, Vo is known, and V1 is a known first reference voltage, so that the resistance values ​​of the first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R4, and the fifth resistor R5 can be inferred.

[0078] As an optional embodiment, the forward comparison circuit 3 includes:

[0079] a sixth resistor R6, wherein a first end of the sixth resistor R6 is connected to the output end of the operational amplifier circuit 2, and a second end of the sixth resistor R6 is connected to the negative phase input end of the first comparator;

[0080] A first comparator, wherein the non-inverting input terminal of the first comparator is connected to the first reference module, and the output terminal of the first comparator is connected to the first reference module and the controller respectively, and is used to output a preset level signal of a first preset time to the controller when the amplified voltage value is greater than the first reference voltage value, so that the controller performs blocking driving after receiving the preset level signal;

[0081] A fourth capacitor C4, a first terminal of the fourth capacitor C4 is connected to the negative phase input terminal of the first comparator, and a second terminal of the fourth capacitor C4 is grounded.

[0082] In the present utility model, the forward comparison circuit 3 includes: a sixth resistor R6, a first comparator and a fourth capacitor C4, wherein the sixth resistor R6 and the fourth capacitor C4 constitute an RC filter module, which performs corresponding filtering on the amplified electric energy output by the operational amplifier circuit 2, so that the first comparator compares the filtered voltage value with the first reference voltage value of the first reference module, and when the amplified voltage value is greater than the first reference voltage value, the first comparator will output a preset level signal of a first preset time to the controller, so that the controller performs accurate blocking drive after receiving the preset level signal.

[0083] As an optional embodiment, it further includes: a first reference module; wherein the first reference module includes:

[0084] a seventh resistor R7, wherein a first end of the seventh resistor R7 is connected to a second reference power supply, and a second end of the seventh resistor R7 is respectively connected to a non-inverting input end of the first comparator, a first end of an eighth resistor R8, and a first end of a ninth resistor R9, and is used for converting a voltage at the second end of the seventh resistor R7 from a first threshold voltage to a second threshold voltage after the first comparator outputs a preset level signal, wherein the first threshold voltage is greater than the second threshold voltage, and when the first comparator outputs a preset level signal, the first threshold voltage is less than the amplified voltage value;

[0085] An eighth resistor R8, a second end of the eighth resistor R8 is grounded;

[0086] a ninth resistor R9, wherein a second end of the ninth resistor R9 is connected to the output end of the first comparator;

[0087] The fifth capacitor C5 is connected in parallel with the eighth resistor R8.

[0088] In the utility model, the first reference module includes: a seventh resistor R7, an eighth resistor R8, a ninth resistor R9 and a fifth capacitor C5. The three resistors are used for voltage division, and the voltage value after voltage division is the first threshold voltage when the first comparator outputs a preset level signal. When the first comparator outputs a preset level signal, the voltage value after voltage division becomes the second threshold voltage. Because the first threshold voltage is greater than the second threshold voltage, when the negative input terminal of the first comparator just switches from a high voltage to a low voltage, the first comparator will not immediately output the preset level signal. At this time, the first comparator, as a hysteresis comparator, will output a preset level signal of the first preset time according to its own hysteresis comparison interval to ensure that the controller has enough time to receive the preset level signal.

[0089] As an optional embodiment, the negative comparison circuit 4 includes:

[0090] A second comparator, the positive input terminal of the second comparator is connected to the second end of the sixth resistor R6, the negative input terminal of the second comparator is connected to the second reference module, and the output terminal is connected to the controller, and is used to output a preset level signal of a second preset time to the controller when the amplified voltage value is less than the second reference voltage value provided by the second reference module, so that the controller performs blocking driving after receiving the preset level signal.

[0091] In the present utility model, the negative comparison circuit 4 includes: a second comparator, wherein the non-phase input terminal of the second comparator is connected to an RC filter module composed of a sixth resistor R6 and a fourth capacitor C4, and the RC filter module can perform corresponding filtering on the amplified electric energy output by the operational amplifier circuit 2, so that the second comparator compares the filtered voltage value with the second reference voltage value of the second reference module, and when the amplified voltage value is less than the first reference voltage value, the second comparator will output a preset level signal of a second preset time to the controller, so that the controller can perform accurate blocking drive after receiving the preset level signal.

[0092] As an optional embodiment, it further includes: a second reference module; wherein the second reference module includes:

[0093] a tenth resistor R10, wherein a first end of the tenth resistor R10 is connected to the negative phase input end of the second comparator, and a second end of the tenth resistor R10 is connected to the third reference power supply;

[0094] A PNP transistor, the emitter of the PNP transistor is connected to the second end of the tenth resistor R10;

[0095] an eleventh resistor R11, wherein a first end of the eleventh resistor R11 is connected to the negative phase input end of the second comparator, and a second end of the eleventh resistor R11 is connected to the collector of the PNP transistor;

[0096] A diode, wherein the anode of the diode is connected to the base of the PNP transistor, and the cathode of the diode is connected to the fourth reference power supply;

[0097] a twelfth resistor R12, wherein a first end of the twelfth resistor R12 is respectively connected to a first end of the tenth resistor R10, a first end of the eleventh resistor R11 and a negative phase input end of the second comparator, and a second end of the twelfth resistor R12 is grounded, and is used for converting a voltage at the first end of the twelfth resistor R12 from a third threshold voltage to a fourth threshold voltage when the output end of the second comparator outputs a preset level signal, the third threshold voltage is less than the fourth threshold voltage, and the third threshold voltage is greater than the amplified voltage value when the second comparator outputs a preset level signal;

[0098] The sixth capacitor C6 is connected in parallel with the twelfth resistor R12.

[0099] In the utility model, the second reference module includes: a tenth resistor R10, a PNP transistor, an eleventh resistor R11, a twelfth resistor R12, a diode and a sixth capacitor C6, wherein when the output end of the second comparator does not output a preset level signal, the PNP transistor and the diode are not turned on, and at this time, the voltage at the negative phase input end of the second comparator is the voltage divided by the third reference power supply after passing through the tenth resistor R10 and the twelfth resistor R12, when the output end of the second comparator outputs a preset level signal, the PNP transistor and the diode are turned on, and at this time, the voltage at the negative phase input end of the second comparator is the voltage divided by the third reference power supply after passing through the tenth resistor R10 and the eleventh resistor R11 in parallel and then in series with the twelfth resistor R12, and at this time, the voltage at the negative phase input end of the second comparator changes from the third threshold voltage to the fourth threshold voltage, and at this time, the second comparator, as a hysteresis comparator, will output a preset level signal of a second preset time according to its own hysteresis comparison interval, to ensure that the controller has enough time to receive the preset level signal.

[0100] As an optional embodiment, the second reference module further includes:

[0101] a thirteenth resistor R13, wherein a first end of the thirteenth resistor R13 is connected to the base of the PNP transistor, and a second end of the thirteenth resistor R13 is connected to the anode of the diode;

[0102] A fourteenth resistor R14 , a first end of the fourteenth resistor R14 is connected to the cathode of the diode, and a second end of the fourteenth resistor R14 is connected to the fourth reference power supply.

[0103] In the utility model, the second reference module also includes a thirteenth resistor R13 and a fourteenth resistor R14, and the thirteenth resistor R13 is arranged between the base of the PNP transistor and the anode of the diode, which can play a role in current limiting. Similarly, the fourteenth resistor is arranged between the cathode of the diode and the fourth reference power supply, which can also play a role in current limiting, thereby improving the safety performance of the solution.

[0104] It should be noted that the first reference power supply is Figure 2 V1 and the second reference power supply are Figure 2 V2 and the third reference power supply are Figure 2 V3 and the fourth reference power supply are Figure 2 In V4, the specific voltage value of each reference power supply depends on the actual situation and is not particularly limited in this application.

[0105] As an optional embodiment, it also includes:

[0106] A fifteenth resistor R15, wherein a first end of the fifteenth resistor R15 is respectively connected to the output end of the positive comparison circuit 3 and the output end of the negative comparison circuit 4, and a second end of the fifteenth resistor R15 is respectively connected to the first end of the seventh capacitor C7 and the controller;

[0107] A seventh capacitor C7: a second end of the seventh capacitor C7 is grounded.

[0108] In the utility model, the overcurrent protection circuit also includes: a fifteenth resistor R15 and a seventh capacitor C7. The fifteenth resistor R15 and the seventh capacitor C7 are arranged at the output end of the positive comparison circuit 3 and the output end of the negative comparison circuit 4 to play a filtering role, so that the level signals sent by the positive comparison circuit 3 and the negative comparison circuit 4 can be transmitted to the controller more stably after filtering, thereby improving the efficiency of the solution.

[0109] The utility model also provides an embodiment corresponding to an overcurrent protection system, comprising: the overcurrent protection circuit and the controller as described above, the overcurrent protection circuit and the controller are connected.

[0110] The overcurrent protection system provided in this embodiment corresponds to the overcurrent protection circuit mentioned above, and therefore has the same beneficial effects as the overcurrent protection circuit mentioned above. Therefore, for the embodiments of the overcurrent protection system part, please refer to the description of the embodiments of the overcurrent protection circuit part, which will not be repeated here.

[0111] It should be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0112] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An overcurrent protection circuit, characterized in that: include: A current detection device, the input end of which is connected to the circuit to be tested, and is used to collect the current on the circuit to be tested and convert the current into a voltage, wherein the voltage is linearly related to the current; An operational amplifier circuit, wherein the positive input terminal and the negative input terminal of the operational amplifier circuit are both connected to the current detection circuit, and are used to linearly amplify the voltage, wherein the minimum value of the amplified voltage value corresponding to the positive current is greater than the maximum value of the amplified voltage value corresponding to the negative current, and the amplified voltage values ​​are all positive values; A positive comparison circuit, wherein the negative phase input terminal of the positive comparison circuit is connected to the output terminal of the operational amplifier circuit, the positive phase input terminal of the positive comparison circuit is connected to the first reference module, and the output terminal of the positive comparison circuit is connected to the controller, and is used to output a preset level signal of a first preset time to the controller when the amplified voltage value is greater than the first reference voltage value provided by the first reference module, so that the controller performs blocking driving after receiving the preset level signal; A negative comparison circuit, wherein the positive phase input terminal of the negative comparison circuit is connected to the output terminal of the operational amplifier circuit, the negative phase input terminal of the negative comparison circuit is connected to the second reference module, and the output terminal of the negative comparison circuit is connected to the controller, and is used to output the preset level signal of the second preset time to the controller when the amplified voltage value is less than the second reference voltage value provided by the second reference module, so that the controller performs blocking driving after receiving the preset level signal; The first reference voltage value is greater than the second reference voltage value.

2. The overcurrent protection circuit according to claim 1, characterized in that: The current detection device comprises: A current transformer, wherein the primary winding of the current transformer is connected in series in the circuit to be tested, and is used to sense the current in the circuit to be tested; A first resistor, wherein a first end of the first resistor is connected to a first end of a secondary winding of the current transformer and a positive phase input end of the operational amplifier circuit, and a second end of the first resistor is respectively connected to a second end of the secondary winding, a ground wire, and a negative phase input end of the operational amplifier circuit, for collecting the current and converting the current into the voltage.

3. The overcurrent protection circuit according to claim 2, characterized in that: The operational amplifier circuit comprises: a second resistor, wherein a first end of the second resistor is connected to a first end of the first resistor, and a second end of the second resistor is connected to a non-inverting input end of the operational amplifier; a third resistor, wherein a first end of the third resistor is connected to a second end of the first resistor, and a second end of the third resistor is connected to a negative phase input end of the operational amplifier; The operational amplifier, the output end of the operational amplifier is respectively connected to the first end of the fourth resistor, the negative phase input end of the positive comparison circuit and the positive phase input end of the negative comparison circuit, for linearly amplifying the voltage; The fourth resistor, a second end of the fourth resistor is connected to the first end of the first capacitor; a fifth resistor, wherein a first end of the fifth resistor is connected to the second end of the first capacitor, and a second end of the fifth resistor is connected to the first reference power supply; The first capacitor, a second end of the first capacitor is connected to the second end of the second resistor; a second capacitor, the second capacitor being connected in parallel with the fourth resistor; A third capacitor is connected in parallel with the fifth resistor.

4. The overcurrent protection circuit according to claim 1, characterized in that: The forward comparison circuit comprises: a sixth resistor, wherein a first end of the sixth resistor is connected to the output end of the operational amplifier circuit, and a second end of the sixth resistor is connected to the negative phase input end of the first comparator; The first comparator, the non-inverting input terminal of the first comparator is connected to the first reference module, and the output terminal of the first comparator is connected to the first reference module and the controller respectively, and is used to output the preset level signal of the first preset time to the controller when the amplified voltage value is greater than the first reference voltage value, so that the controller performs blocking driving after receiving the preset level signal; A fourth capacitor, wherein a first end of the fourth capacitor is connected to the negative phase input end of the first comparator, and a second end of the fourth capacitor is grounded.

5. The overcurrent protection circuit according to claim 4, characterized in that: Also includes: The first reference module; wherein the first reference module comprises: a seventh resistor, wherein a first end of the seventh resistor is connected to a second reference power supply, and a second end of the seventh resistor is respectively connected to a non-inverting input end of the first comparator, a first end of an eighth resistor, and a first end of a ninth resistor, and is used for converting a voltage at the second end of the seventh resistor from a first threshold voltage to a second threshold voltage after the first comparator outputs the preset level signal, wherein the first threshold voltage is greater than the second threshold voltage, and when the first comparator outputs the preset level signal, the first threshold voltage is less than the amplified voltage value; The eighth resistor, a second end of the eighth resistor is grounded; The ninth resistor, a second end of the ninth resistor is connected to the output end of the first comparator; A fifth capacitor is connected in parallel with the eighth resistor.

6. The overcurrent protection circuit according to claim 4, characterized in that: The negative comparison circuit comprises: A second comparator, wherein the positive input terminal of the second comparator is connected to the second end of the sixth resistor, the negative input terminal of the second comparator is connected to the second reference module, and the output terminal is connected to the controller, and is used for outputting the preset level signal of the second preset time to the controller when the amplified voltage value is less than the second reference voltage value provided by the second reference module, so that the controller performs blocking driving after receiving the preset level signal.

7. The overcurrent protection circuit according to claim 6, characterized in that: Also includes: The second reference module; wherein the second reference module comprises: a tenth resistor, wherein a first end of the tenth resistor is connected to the negative phase input end of the second comparator, and a second end of the tenth resistor is connected to the third reference power supply; A PNP transistor, the emitter of which is connected to the second end of the tenth resistor; an eleventh resistor, a first end of the eleventh resistor being connected to the negative phase input end of the second comparator, and a second end of the eleventh resistor being connected to the collector of the PNP transistor; A diode, wherein an anode of the diode is connected to a base of the PNP transistor, and a cathode of the diode is connected to a fourth reference power supply; a twelfth resistor, wherein a first end of the twelfth resistor is respectively connected to a first end of the tenth resistor, a first end of the eleventh resistor and a negative phase input end of the second comparator, and a second end of the twelfth resistor is grounded, and is used for converting a voltage of the first end of the twelfth resistor from a third threshold voltage to a fourth threshold voltage when the output end of the second comparator outputs the preset level signal, the third threshold voltage is less than the fourth threshold voltage, and when the second comparator outputs the preset level signal, the third threshold voltage is greater than the amplified voltage value; A sixth capacitor is connected in parallel with the twelfth resistor.

8. The overcurrent protection circuit according to claim 7, characterized in that: The second reference module further includes: a thirteenth resistor, a first end of the thirteenth resistor being connected to the base of the PNP transistor, and a second end of the thirteenth resistor being connected to the anode of the diode; A fourteenth resistor, wherein a first end of the fourteenth resistor is connected to the cathode of the diode, and a second end of the fourteenth resistor is connected to the fourth reference power supply.

9. The overcurrent protection circuit according to any one of claims 1 to 8, characterized in that: Also includes: a fifteenth resistor, wherein a first end of the fifteenth resistor is respectively connected to the output end of the positive comparison circuit and the output end of the negative comparison circuit, and a second end of the fifteenth resistor is respectively connected to the first end of the seventh capacitor and the controller; The seventh capacitor, a second end of the seventh capacitor is grounded.

10. An overcurrent protection system, characterized in that: include: The overcurrent protection circuit and controller according to any one of claims 1 to 9, wherein the overcurrent protection circuit is connected to the controller.

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