High-stability self-recovery over-current protection circuit

Abstract

The invention provides a high-stability self-recovery over-current protection circuit. The high-stability self-recovery over-current protection circuit comprises a current sensor, a voltage comparator, a time delay circuit and a switching circuit, the current sensor converts a current signal into a voltage signal and outputs the voltage signal to the first input end of the voltage comparator. And the voltage comparator compares the voltage signal with a preset standard voltage value to judge whether the circuit is in an overcurrent state or not. The time delay circuit is used for setting the overcurrent duration time, and false triggering under the normal short-time large-current condition is avoided. And the switching circuit cuts off the circuit connection after the overcurrent signal lasts for more than a set time. According to the circuit, through cooperation of the time delay circuit and the switching circuit, a high-stability over-current protection function is realized. The overcurrent protection circuit can realize high stability and self-recovery function of overcurrent protection, and has the advantages of simple technical principle, low cost and high applicability.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit protection, and more particularly to a high-stability self-recovery overcurrent protection circuit. Background Art

[0002] Among existing circuit overcurrent protection technologies, traditional fuses are the mainstream solution. When an overcurrent condition occurs in a circuit, the fuse blows, disconnecting the circuit and protecting it from damage. However, this protection method has significant drawbacks: once a fuse blows, it must be replaced to restore normal circuit operation, increasing repair costs and extending equipment downtime. Furthermore, while resettable fuses can partially address the fuse replacement issue, they operate by melting a polymer resin to create a high-resistance state through the heat generated by the current. This design is prone to false triggering or non-triggering of the overcurrent protection in high or low temperature environments, resulting in insufficient stability and reliability.

[0003] In the process of implementing the embodiments of the present invention, the inventors discovered that the prior art has at least the following problems or defects: the traditional fuse-type protection method has high maintenance costs and long recovery time; and the self-resettable fuse has unstable performance under extreme temperature conditions and cannot meet the requirements of high-reliability circuit protection. Summary of the Invention

[0004] The present invention provides a high-stability self-recovery overcurrent protection circuit, comprising:

[0005] Current sensor, voltage comparator, delay circuit and switching circuit;

[0006] The output end of the current sensor is connected to the first input end of the voltage comparator, the output end of the voltage comparator is connected to the input end of the delay circuit, and the output end of the delay circuit is connected to the control end of the switching circuit; the current sensor is used to convert the current signal into a voltage signal; the voltage comparator is used to compare the voltage signal with a preset standard voltage value to determine whether the circuit is in an overcurrent state; the delay circuit is used to set the overcurrent duration to avoid false triggering of normal short-term high current conditions; the switching circuit is used to cut off the circuit connection after the overcurrent signal continues for more than a set time.

[0007] Furthermore, the current sensor is a Hall-effect induction current sensor, the current measurement range of the Hall-effect induction current sensor is -30A to +30A, and the output end of the Hall-effect induction current sensor is connected to the first input end of the voltage comparator.

[0008] Furthermore, the voltage comparator is an LM2903B dual comparator, the first input end of the LM2903B dual comparator is connected to the output end of the current sensor, the second input end of the LM2903B dual comparator is connected to a preset standard voltage value, and the output end of the LM2903B dual comparator is connected to the input end of the delay circuit.

[0009] Furthermore, the delay circuit is composed of a capacitor C3, a resistor R5 and a resistor R6, one end of the capacitor C3 is connected to the output end of the voltage comparator, the other end of the capacitor C3 is connected to the ground, one end of the resistor R5 is connected to the output end of the voltage comparator, the other end of the resistor R5 is connected to one end of the resistor R6, and the other end of the resistor R6 is connected to the ground; the delay time calculation formula of the delay circuit is:

[0010]

[0011] Among them, V t is the capacitor voltage value at any time t, V U is the charging voltage value, R5 is the charging resistance value, and C3 is the charging capacitance value.

[0012] Furthermore, the delay time of the delay circuit is set by adjusting the values of the resistor R5 and the capacitor C3, and the output end of the delay circuit is connected to the control end of the switch circuit.

[0013] Furthermore, the switching circuit includes a transistor Q1, a push switch S1 and a thyristor Q2; the collector of the transistor Q1 is connected to the anode of the thyristor Q2, the emitter of the transistor Q1 is connected to the cathode of the thyristor Q2, and the base of the transistor Q1 is connected to the output end of the delay circuit; one end of the push switch S1 is connected to the gate of the thyristor Q2, and the other end of the push switch S1 is connected to the power supply.

[0014] Furthermore, when the output end of the delay circuit is at a high level, the transistor Q1 is turned on, the anode voltage of the thyristor Q2 drops to the conduction voltage drop of the transistor Q1, and the thyristor Q2 is turned off, cutting off the power supply of subsequent electrical equipment.

[0015] Furthermore, when the output terminal of the delay circuit drops to a low level, the transistor Q1 is turned off, and the key switch S1 is pressed, the thyristor Q2 obtains sufficient gate voltage, and the thyristor Q2 is turned on to continue to supply power to the subsequent circuit.

[0016] Furthermore, the output voltage value V of the current sensor out The voltage value V corresponding to the preset maximum current REF1 The relationship is:

[0017] V out =2.5+S·I P

[0018] Among them, V out is the output voltage value, I P is the measured current, S is the sensor sensitivity, and the sensor sensitivity is 66mV.

[0019] Furthermore, the preset standard voltage value V REF1 The calculation formula is:

[0020] V REF1 =2.5+S·I PMAX

[0021] Among them, I PMAX is the maximum operating current of the system, S is the sensor sensitivity, and the sensor sensitivity is 66mV.

[0022] The above-described embodiments of the present invention have at least the following beneficial effects: The high-stability, resettable overcurrent protection circuit of the present invention effectively solves the inconvenience of traditional fuse replacement after a blown fuse, avoiding the increased maintenance costs and equipment downtime associated with fuse replacement. Furthermore, the circuit overcomes the potential for false triggering or non-triggering of resettable fuses in high or low temperature environments, ensuring the stability and reliability of circuit protection. Furthermore, the technical principles of the present invention are relatively simple, cost-effective, and widely applicable to a variety of circuit structures, providing an efficient and reliable solution for circuit overcurrent protection.

[0023] The present invention can also set the overcurrent duration through a delay circuit to avoid false triggering under normal short-term high current conditions, further improving the accuracy and adaptability of circuit protection. At the same time, the switching circuit implements a rapid recovery function after overcurrent protection, allowing users to achieve self-recovery through simple operations or using devices such as single-chip microcomputers, greatly improving the operating efficiency of the circuit system and user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and other objects, features and advantages of the exemplary embodiments of the present invention will become readily apparent by reading the following detailed description with reference to the accompanying drawings, in which several embodiments of the present invention are shown by way of example and not limitation, in which:

[0025] Figure 1 A logic block diagram of a high-stability self-recovery overcurrent protection circuit provided by an embodiment of the present invention;

[0026] Figure 2 A schematic structural diagram of a high-stability self-recovery overcurrent protection circuit provided by one embodiment of the present invention;

[0027] Figure 3 A current-voltage correspondence diagram provided by an embodiment of the present invention;

[0028] Figure 4 This is a temperature characteristic diagram provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The principles and spirit of the present invention will be described below with reference to several exemplary embodiments. It should be understood that these embodiments are provided solely to enable those skilled in the art to better understand and implement the present invention, and are not intended to limit the scope of the present invention in any way. Rather, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0030] Those skilled in the art will appreciate that the embodiments of the present invention may be implemented as a system, apparatus, device, method, or computer program product. Therefore, the present invention may be implemented in the following forms: entirely in hardware, entirely in software (including firmware, resident software, microcode, etc.), or in a combination of hardware and software.

[0031] It should be noted that any number of elements in the drawings is for illustration only and not for limitation, and any naming is only for distinction and does not have any limiting meaning.

[0032] Reference below Figure 1 , Figure 1 This is a schematic diagram of the structure of a high stability self-recovery overcurrent protection circuit provided by an embodiment of the present invention. Figure 1 As shown, a high stability self-recovery overcurrent protection circuit 100 includes:

[0033] Current sensor 101 , voltage comparator 102 , delay circuit 103 and switch circuit 104 .

[0034] like Figure 2 As shown. The output end of the current sensor is connected to the first input end of the voltage comparator, the output end of the voltage comparator is connected to the input end of the delay circuit, and the output end of the delay circuit is connected to the control end of the switch circuit; the current sensor is used to convert the current signal into a voltage signal; the voltage comparator is used to compare the voltage signal with a preset standard voltage value to determine whether the circuit is in an overcurrent state; the delay circuit is used to set the overcurrent duration to avoid false triggering in normal short-term high current conditions; the switch circuit is used to disconnect the circuit after the overcurrent signal persists for more than a set time.

[0035] It should be noted that the high-stability self-recovery overcurrent protection circuit of the present invention includes a current sensor, a voltage comparator, a delay circuit, and a switch circuit. The current sensor is used to convert a current signal into a voltage signal, and its output end is connected to the first input end of the voltage comparator. The voltage comparator is used to compare the voltage signal with a preset standard voltage value to determine whether the circuit is in an overcurrent state. Its output end is connected to the input end of the delay circuit. The delay circuit is used to set the overcurrent duration to avoid false triggering in normal short-term high current conditions. Its output end is connected to the control end of the switch circuit. The switch circuit is used to disconnect the circuit connection after the overcurrent signal continues for more than a set time. Among them, the current sensor is a device that can convert a current signal into a voltage signal, the voltage comparator is a circuit that can compare two voltage signals and output corresponding logic levels, the delay circuit is a circuit that can delay the output of a signal, and the switch circuit is a device that can disconnect or connect the circuit according to a control signal.

[0036] Specifically, the current sensor adopts a Hall-effect inductive design, and its measurement range is -30A to +30A, which can cover the current detection needs of most common circuits. The Hall-effect inductive current sensor converts the current signal into a voltage signal through the Hall effect, and has the characteristics of high precision, low power consumption and fast response. The voltage comparator uses the LM2903B dual comparator, whose first input is connected to the output of the current sensor, and the second input is connected to the preset standard voltage value. LM2903B is a dual-channel voltage comparator with the characteristics of low power consumption, high gain and a wide operating voltage range. The delay circuit is composed of capacitor C3, resistor R5 and resistor R6, and the delay time can be set by adjusting the values of the resistors and capacitors. The calculation formula for the delay time is: The formula for the change of capacitor voltage over time is:

[0037]

[0038] Among them, V c (t) represents the capacitor voltage value at any time t, V charge represents the charging voltage, R5 represents the charging resistance, and C3 represents the charging capacitance. The switching circuit includes transistor Q1, pushbutton switch S1, and thyristor Q2. The collector of transistor Q1 is connected to the anode of thyristor Q2, the emitter is connected to the cathode of thyristor Q2, and the base is connected to the output of the delay circuit. One end of pushbutton switch S1 is connected to the gate of thyristor Q2, and the other end is connected to the power supply. When the output of the delay circuit is high, transistor Q1 turns on, the anode voltage of thyristor Q2 drops to the conduction voltage drop of transistor Q1, and thyristor Q2 turns off, cutting off power to subsequent electrical devices.

[0039] like Figure 3 As shown, the relationship between the output voltage value of the current sensor and the voltage value corresponding to the preset maximum current is Vout =2.5+S×I measured , where V out is the output voltage value, I measured is the measured current, and S is the sensor sensitivity, which is 66mV in this case.

[0040] like Figure 4 As shown. The preset standard voltage value V ref The calculation formula is V ref =2.5+S×I max , where I max is the maximum operating current of the system. In practical applications, current sensors with different sensitivities can be selected based on different circuit requirements, such as the ACS712ELCTR-30A-T, which has a sensitivity of 66mV. For voltage comparators, in addition to the LM2903B dual comparator, other high-performance voltage comparators, such as the LM393, can also be used. The delay time of the delay circuit can be adjusted by selecting resistors of different values and capacitors of different capacities to suit different application scenarios. For example, smaller resistor and capacitor values can be selected for shorter delay times, while larger resistor and capacitor values can be selected for longer delay times. The pushbutton switch S1 in the switching circuit can also be replaced by a device such as a microcontroller to implement an automatic recovery function, improving the circuit's intelligence.

[0041] In some embodiments, the current sensor is a Hall-effect inductive current sensor, the current measurement range of the Hall-effect inductive current sensor is -30A to +30A, and the output end of the Hall-effect inductive current sensor is connected to the first input end of the voltage comparator.

[0042] It should be noted that the current sensor is a key component in the overcurrent protection circuit of the present invention, and its function is to convert the current signal in the circuit into a voltage signal for subsequent processing. The current sensor adopts a Hall-effect design. This sensor can convert the change of current into the change of voltage through the Hall effect principle, thereby realizing non-contact measurement of current. The Hall-effect current sensor has the characteristics of high precision, high response speed and good linearity, and is suitable for a variety of current measurement scenarios. In the present invention, the current measurement range of the current sensor is -30A to +30A, which means that it can detect the current change from -30A to +30A, which can meet the current detection requirements of most common circuits. The output end of the current sensor is connected to the first input end of the voltage comparator to ensure that the voltage signal after the current signal is converted can be accurately transmitted to the voltage comparator for further processing.

[0043] Specifically, the working principle of the Hall effect current sensor is based on the Hall effect. When current flows through a conductor, a voltage proportional to the current is generated in a magnetic field perpendicular to the current direction. In this invention, the current sensor model selected is ACS712ELCTR-30A-T, which has a sensitivity of 66mV / A. That is, for every 1A of current flowing through it, the voltage output by the sensor changes by 66mV. The relationship between the output voltage of the current sensor and the measured current can be expressed by the formula V out =2.5+S·I measured Indicates that V out is the voltage value output by the sensor, I measured is the measured current value, and S is the sensitivity of the sensor. In the present invention, the output voltage range of the sensor is 0V to 5V, and the corresponding current measurement range is -30A to +30A. This design enables the current sensor to provide accurate voltage output within a wider current range, thereby providing a reliable data basis for subsequent voltage comparison. In addition, the temperature characteristics of the current sensor are also very important. Its sensitivity offset range is ±1mV within the temperature range of -40℃ to 150℃, which means that the influence of temperature on the output accuracy of the sensor can be ignored, thereby ensuring the accuracy of current measurement under different ambient temperatures.

[0044] To further improve the performance and applicability of the current sensor, other Hall-effect current sensors, such as the ACS712-20A or ACS712-5A, can be selected. These models offer different current measurement ranges and sensitivities, allowing selection based on specific application requirements. For example, for circuits requiring low current measurement, the ACS712-5A can be selected, with its ±5A current measurement range and higher sensitivity, providing more accurate measurement results. Furthermore, to enhance the current sensor's interference resistance, filtering circuits can be added to the sensor's input and output to reduce the impact of electromagnetic interference on the measurement results. For example, a low-pass filter can be added to the sensor's input to filter out high-frequency noise, thereby improving the stability and reliability of the current measurement.

[0045] In some embodiments, the voltage comparator is a LM2903B dual comparator, the first input end of the LM2903B dual comparator is connected to the output end of the current sensor, the second input end of the LM2903B dual comparator is connected to a preset standard voltage value, and the output end of the LM2903B dual comparator is connected to the input end of the delay circuit.

[0046] It should be noted that the voltage comparator is one of the core components of the overcurrent protection circuit of the present invention. Its function is to compare the voltage signal output by the current sensor with the preset standard voltage value, thereby determining whether the circuit is in an overcurrent state. The voltage comparator outputs a corresponding logic level signal by comparing the voltage signals at the two input terminals to indicate whether the circuit is overcurrent. In the present invention, the voltage comparator selected is the LM2903B dual-channel comparator, which has the characteristics of low power consumption, high gain and a wide operating voltage range, and can meet the usage requirements in different circuit environments. The first input terminal of the LM2903B dual-channel comparator is connected to the output terminal of the current sensor to receive the voltage signal converted by the current sensor; the second input terminal is connected to the preset standard voltage value to set the threshold value of the overcurrent protection; its output terminal is connected to the input terminal of the delay circuit, and the comparison result is passed to the delay circuit for subsequent processing.

[0047] Specifically, the LM2903B dual comparator is a commonly used voltage comparator that can compare the voltage signals of the two input terminals and output a high level or a low level according to the comparison result. In the present invention, the voltage signal output by the current sensor is connected to the first input terminal of the LM2903B, and the preset standard voltage value is connected to the second input terminal. When the voltage output by the current sensor exceeds the preset standard voltage value, the LM2903B comparator outputs a high level signal, indicating that the circuit is in an overcurrent state; conversely, when the voltage output by the current sensor is lower than the preset standard voltage value, the comparator outputs a low level signal, indicating that the circuit is normal. The preset standard voltage value is calculated based on the maximum operating current of the system, and its calculation formula is V ref =2.5+S·I max , where I max is the maximum operating current of the system, and S is the sensitivity of the current sensor. For example, if the maximum operating current of the system is 20A and the sensitivity of the current sensor is 66mV / A, the preset standard voltage value is:

[0048] V ref =2.5+0.066×20

[0049] =2.5+1.32

[0050] =3.82(V)

[0051] This setting ensures that the voltage comparator can accurately output an overcurrent signal when the current exceeds the set threshold.

[0052] Preferably, to further improve the performance and applicability of the voltage comparator, other types of voltage comparators, such as the LM393 or LM339, can be selected. These comparators have different characteristics, such as higher input impedance, faster response speed, or lower power consumption, and can be selected based on specific application requirements. For example, the LM393 has higher input impedance and faster response speed, making it suitable for applications with high response time requirements. In addition, to improve the anti-interference ability of the voltage comparator, a filtering circuit can be added to the input of the comparator to reduce the impact of noise on the comparison results. For example, a low-pass filter can be added to the input of the comparator to filter out high-frequency noise, thereby improving the stability and reliability of the comparator.

[0053] In some embodiments, the delay circuit is composed of a capacitor C3, a resistor R5, and a resistor R6, one end of the capacitor C3 is connected to the output end of the voltage comparator, the other end of the capacitor C3 is connected to the ground, one end of the resistor R5 is connected to the output end of the voltage comparator, the other end of the resistor R5 is connected to one end of the resistor R6, and the other end of the resistor R6 is connected to the ground; the delay time calculation formula of the delay circuit is:

[0054]

[0055] Among them, V t is the capacitor voltage value at any time t, V U is the charging voltage value, R5 is the charging resistance value, and C3 is the charging capacitance value.

[0056] It should be noted that the delay circuit is an important component of the overcurrent protection circuit of the present invention. Its function is to avoid false triggering caused by short-term large current by setting a certain delay time after the voltage comparator outputs the overcurrent signal. The delay circuit is composed of capacitor C3, resistor R5 and resistor R6. Through the synergistic effect of these components, the delay time can be accurately controlled. Specifically, one end of capacitor C3 is connected to the output end of the voltage comparator, and the other end is grounded; one end of resistor R5 is connected to the output end of the voltage comparator, and the other end is connected to one end of resistor R6, and the other end of resistor R6 is grounded. The calculation formula for the delay time is:

[0057]

[0058] Among them, V c (t) = the capacitor voltage value at any time t, V charge is the charging voltage, R5 is the charging resistance, and C3 is the charging capacitance. This design allows the delay circuit to flexibly adjust the delay time according to actual needs, thereby improving the accuracy and reliability of overcurrent protection.

[0059] Specifically, the core of the delay circuit utilizes the charge-discharge characteristics of a capacitor to achieve a delay function. In the present invention, capacitor C3 and resistors R5 and R6 together form an RC charge-discharge circuit. When the voltage comparator outputs a high level, capacitor C3 begins charging, and its voltage rises exponentially over time. The length of the delay time depends on the values of resistor R5 and capacitor C3. By adjusting these parameters, the delay time can be precisely controlled. For example, if the delay time needs to be set to 1 second, appropriate values for R5 and C3 can be selected so that the product of R5·C3 is close to the desired delay time. In addition, the output end of the delay circuit is connected to the control end of the switching circuit. When the capacitor voltage reaches a set threshold, the delay circuit outputs a high-level signal, triggering the switching circuit to cut off the power supply, thereby implementing the overcurrent protection function. This design not only effectively avoids false triggering caused by short-term high currents, but also promptly cuts off the circuit when an overcurrent actually occurs, protecting the equipment safety.

[0060] Preferably, in order to further optimize the performance of the time-delay circuit, different types of capacitors and resistors can be selected. For example, using high-precision metal film resistors and low-leakage ceramic capacitors can improve the stability and accuracy of the time-delay circuit. In addition, in order to improve the flexibility of the time-delay circuit, an adjustable resistor (such as a potentiometer) can be used to replace the fixed resistor R5, and the delay time can be dynamically adjusted by adjusting the resistance of the potentiometer. For example, an adjustable resistor can be installed on a circuit board and adjusted by an external knob, thereby achieving flexible control of the delay time. In addition, the time-delay circuit can also reduce the influence of ambient temperature on the delay time by adding a temperature compensation element, further improving the reliability of the circuit.

[0061] In some embodiments, the delay time of the delay circuit is set by adjusting the values of the resistor R5 and the capacitor C3, and the output end of the delay circuit is connected to the control end of the switch circuit.

[0062] It should be noted that the delay time of the delay circuit can be set by adjusting the values of resistor R5 and capacitor C3. This design gives the delay circuit a high degree of flexibility, allowing it to cleverly adjust the delay time according to different application scenarios, thereby better meeting the operating requirements of various circuits. The output of the delay circuit is connected to the control end of the switch circuit. This ensures that if the overcurrent signal persists for more than the set time, the switch circuit is promptly triggered to disconnect the circuit, effectively protecting the electrical equipment from damage. The delay time adjustment function greatly expands the possibilities of circuit design, allowing the circuit to cleverly avoid false triggering under normal short-term high current conditions, while also responding quickly when an overcurrent actually occurs.

[0063] Specifically, the core principle of the delay circuit is to cleverly utilize the charge and discharge characteristics of capacitor C3 to achieve the delay function. In the present invention, one end of capacitor C3 is connected to the output of the voltage comparator, and the other end is grounded. Resistors R5 and R6 are connected in series and then in parallel with capacitor C3, together constructing a typical RC charge and discharge circuit. The delay time is calculated as follows:

[0064]

[0065] Among them, V c (t) represents the capacitor voltage value at any time t, V charge represents the charging voltage, R5 is the charging resistor, and C3 is the charging capacitor. By carefully adjusting the values of R5 and C3, the delay time can be precisely controlled. For example, if the desired delay time is 2 seconds, appropriate values for R5 and C3 can be selected so that the product of R5·C3 approaches 2 seconds. The output of the delay circuit is connected to the control terminal of the switching circuit. When the capacitor voltage reaches the set threshold, the delay circuit outputs a high-level signal, which triggers the switching circuit to cut off the power supply, successfully implementing the overcurrent protection function. This design not only effectively avoids false triggering caused by short-term high currents, but also promptly cuts off the circuit when an overcurrent condition actually occurs, fully ensuring equipment safety.

[0066] Preferably, in order to further improve the performance of the delay circuit, high-precision resistors and low-leakage capacitors can be used. For example, the use of metal film resistors and ceramic capacitors can significantly enhance the stability and accuracy of the delay circuit. In addition, in order to enhance the flexibility of the delay circuit, an adjustable resistor (such as a potentiometer) can be used to replace the fixed resistor R5, and the delay time can be dynamically regulated by adjusting the resistance of the potentiometer. For example, by installing an adjustable resistor on the circuit board and adjusting it with the help of an external knob, flexible control of the delay time can be easily achieved. In addition, the delay circuit can also reduce the influence of the ambient temperature on the delay time by adding a temperature compensation element, thereby further enhancing the reliability of the circuit. For example, a temperature compensation capacitor is connected to the circuit, and its temperature coefficient is opposite to that of the main capacitor C3. In this way, when the temperature changes, some errors can be offset, and the stability of the delay time can be effectively guaranteed.

[0067] In some embodiments, the switching circuit includes a transistor Q1, a push switch S1, and a thyristor Q2; the collector of the transistor Q1 is connected to the anode of the thyristor Q2, the emitter of the transistor Q1 is connected to the cathode of the thyristor Q2, and the base of the transistor Q1 is connected to the output end of the delay circuit; one end of the push switch S1 is connected to the gate of the thyristor Q2, and the other end of the push switch S1 is connected to a power supply.

[0068] It should be noted that the switch circuit is the executive component in the overcurrent protection circuit of the present invention, and its function is to cut off the circuit connection after the delay circuit outputs the overcurrent signal, thereby protecting subsequent electrical equipment from overcurrent damage. The switch circuit is composed of a transistor Q1, a key switch S1 and a thyristor Q2. The collector of the transistor Q1 is connected to the anode of the thyristor Q2, the emitter is connected to the cathode of the thyristor Q2, and the base is connected to the output end of the delay circuit. One end of the key switch S1 is connected to the gate of the thyristor Q2, and the other end is connected to the power supply. This design enables the switch circuit to cut off the circuit connection through the synergistic action of the transistor Q1 and the thyristor Q2 after the overcurrent signal continues for more than a set time, and at the same time, the manual power supply restoration function is realized through the key switch S1, thereby improving the reliability and operational convenience of the circuit.

[0069] Specifically, transistor Q1 and thyristor Q2 are the core components of the switching circuit. The function of transistor Q1 is to control the conduction state of thyristor Q2 according to the overcurrent signal output by the delay circuit. When the delay circuit outputs a high level, transistor Q1 is turned on, and the voltage drop between its collector and emitter decreases, causing the anode voltage of thyristor Q2 to drop to a level insufficient to maintain its conduction, thereby turning off thyristor Q2 and cutting off the power supply of the subsequent circuit. Thyristor Q2 is a unidirectional conductive semiconductor device. Once it is turned on, it needs to be turned off by lowering its anode voltage or cutting off the gate signal. In the present invention, the gate of thyristor Q2 is connected to the power supply through the push button switch S1. When the push button switch S1 is pressed, the thyristor Q2 obtains sufficient gate voltage and turns on, restoring the power supply to the circuit. For example, if the maximum operating current of the system is I max =20A, you can choose a suitable thyristor model, such as BT136, whose rated current is I rated =4A, which can meet the needs of most application scenarios. In addition, the key switch S1 can be replaced by a mechanical key or an electronic switch (such as a relay controlled by a single-chip microcomputer) to achieve more flexible control.

[0070] Preferably, to further improve the performance and reliability of the switching circuit, some optimizations can be made to the circuit design. For example, a current-limiting resistor can be added between the base of transistor Q1 and the output of the delay circuit to protect the transistor from overcurrent damage. Furthermore, to improve the anti-interference capability of thyristor Q2, a resistor-capacitor snubber circuit can be added between its gate and cathode to suppress gate voltage spikes. In practical applications, push-button switch S1 can be replaced by a relay or MOSFET controlled by a single-chip microcomputer to implement an automatic recovery function. For example, when the delay circuit outputs a low level, the single-chip microcomputer can control the relay or MOSFET to turn on, providing sufficient voltage to the gate of thyristor Q2, turning it on and restoring circuit power. This design not only improves the circuit's intelligence but also reduces the inconvenience of manual operation.

[0071] In some embodiments, when the output end of the delay circuit is at a high level, the transistor Q1 is turned on, the anode voltage of the thyristor Q2 drops to the conduction voltage drop of the transistor Q1, and the thyristor Q2 is turned off, cutting off the power supply of subsequent electrical devices.

[0072] It's important to note that when the output of the delay circuit is high, transistor Q1 conducts, the anode voltage of thyristor Q2 drops to the conduction voltage drop of transistor Q1, and thyristor Q2 turns off, cutting off power to subsequent devices. This process is the core operating mechanism of the switching circuit, used to promptly shut off the circuit to protect equipment if an overcurrent signal persists for a set time. Transistor Q1 serves as the control element, its conduction state determined by the output signal of the delay circuit; thyristor Q2, on the other hand, serves as the main switching element, responsible for disconnecting or connecting the circuit. This design ensures a fast response and reliable protection in overcurrent conditions.

[0073] Specifically, the conduction condition of transistor Q1 is that its base voltage is higher than a certain threshold. When the delay circuit outputs a high level, the base of transistor Q1 obtains sufficient voltage and turns on. At this time, the voltage drop between the collector and emitter of transistor Q1 (conduction voltage drop) is usually between 0.2V and 0.7V, and the specific value depends on the model of the transistor. The anode voltage of thyristor Q2 will therefore drop below the conduction voltage drop of transistor Q1, which is lower than the forward voltage threshold required for thyristor Q2 to maintain conduction, causing thyristor Q2 to turn off. The forward voltage threshold of thyristor Q2 is usually between 1V and 2V, and the specific value depends on the model of the thyristor. For example, if the selected thyristor model is BT136, its forward conduction voltage is approximately U F ≈1.2V. When transistor Q1 is turned on, the anode voltage of thyristor Q2 drops to U AK ≈0.3V (assuming the conduction voltage drop of transistor Q1 is U CE =0.3V, which is lower than the sustaining conduction voltage of thyristor Q2, causing it to turn off and cut off the power supply to the subsequent circuit. This process ensures that if the overcurrent signal lasts for more than the set time, the circuit can quickly cut off the power supply and protect the electrical equipment from damage.

[0074] Preferably, in order to further improve the reliability and flexibility of the switching circuit, some optimizations can be made to the circuit. For example, a current limiting resistor can be added between the base of the transistor Q1 and the output of the delay circuit to prevent excessive current from damaging the transistor. The resistance R of the current limiting resistor can be adjusted based on the base current I B And the output voltage U of the delay circuit out To choose. According to Ohm's law (where U BE is the voltage between the base and emitter of the transistor). For example, if the output voltage Uout =5V, the base current of transistor Q1 is I B =10mA, assuming U BE =0.7V, then A current-limiting resistor of 470Ω can be selected. Furthermore, to implement automatic recovery, push switch S1 can be replaced with a relay or MOSFET controlled by the microcontroller. For example, when the delay circuit outputs a low level, the microcontroller can control the relay or MOSFET to provide sufficient voltage to the gate of thyristor Q2, turning it on and restoring power to the circuit. This design not only improves the circuit's intelligence but also reduces the inconvenience of manual operation.

[0075] In some embodiments, when the output end of the delay circuit drops to a low level, the transistor Q1 is turned off, the key switch S1 is pressed, the thyristor Q2 obtains sufficient gate voltage, the thyristor Q2 is turned on, and continues to supply power to the subsequent circuit.

[0076] It's important to note that when the output of the delay circuit drops to a low level, transistor Q1 turns off. Pressing pushbutton switch S1 then provides sufficient gate voltage for thyristor Q2 to turn on, resuming power to the subsequent circuits. This process enables the circuit's self-recovery function, meaning that after the overcurrent signal disappears, normal power supply can be restored with a simple operation. Pushbutton switch S1 provides a trigger signal to the gate of thyristor Q2, causing it to transition from the off state to the on state, thereby restoring power to the circuit. This design not only improves the circuit's flexibility and reliability but also reduces the duration of power interruptions due to overcurrent protection.

[0077] Specifically, the cut-off state of transistor Q1 means that its base voltage is insufficient to turn it on. At this time, the collector and emitter of transistor Q1 are in a high-impedance state, which is equivalent to a disconnected switch. The conduction condition of thyristor Q2 is that its gate needs a sufficiently high voltage signal to trigger. When the output of the delay circuit drops to a low level, the base voltage of transistor Q1 also decreases, causing transistor Q1 to be cut off. At this time, press the push button switch S1, and the power supply voltage U s The key switch S1 is directly connected to the gate of the thyristor Q2 to provide it with sufficient trigger voltage. s =5V, the gate trigger voltage U of thyristor Q2 g ≈1.5V. After pressing pushbutton switch S1, the gate voltage of thyristor Q2 reaches the power supply voltage, which is much higher than its trigger voltage, causing it to conduct and restore power to the circuit. This process ensures that the circuit can quickly restore power after the overcurrent signal disappears, improving circuit availability.

[0078] Preferably, to further optimize the circuit's self-recovery function, the push-button switch S1 can be improved. For example, an electronic switch (such as a MOSFET controlled by a single-chip microcomputer) can be used in place of the mechanical push-button switch S1 to implement the automatic recovery function. When the output of the delay circuit drops to a low level, the single-chip microcomputer can control the conduction of the MOSFET, providing a trigger signal to the gate of thyristor Q2, turning it on and restoring power to the circuit. This design not only improves the circuit's intelligence but also reduces the inconvenience of manual operation. Furthermore, to improve circuit reliability, a RC snubber circuit can be added between the gate and cathode of thyristor Q2 to suppress gate voltage spikes and prevent false triggering. For example, a resistor R = 100Ω and a capacitor C = 0.1μF can be connected in parallel to form a RC snubber circuit, effectively reducing gate voltage spikes and improving the anti-interference capability of thyristor Q2.

[0079] In some embodiments, the output voltage value V of the current sensor out The voltage value V corresponding to the preset maximum current REF1 The relationship is:

[0080] V out =2.5+S·I P

[0081] Among them, V out is the output voltage value, I P is the measured current, S is the sensor sensitivity, and the sensor sensitivity is 66mV.

[0082] It should be noted that the relationship between the output voltage value of the current sensor and the voltage value corresponding to the preset maximum current is V out =2.5+S·I measured , where V out is the output voltage value, I measured Where is the measured current, and S is the sensor sensitivity. This formula reflects the linear relationship between the current sensor's conversion of current signals into voltage signals and is the basis for implementing overcurrent protection. By setting a preset voltage value corresponding to the system's maximum operating current, it is possible to accurately determine whether the circuit is experiencing an overcurrent condition. This design utilizes the linear output characteristics of Hall-effect current sensors, ensuring accurate and reliable current measurement.

[0083] Specifically, the output voltage of the current sensor V out is generated by the Hall effect and is related to the measured current I measuredThe sensor sensitivity S refers to the output voltage change caused by a unit current change, usually expressed in millivolts per ampere (mV / A). In this invention, the current sensor ACS712ELCTR-30A-T has a sensitivity of 66mV / A, which means that for every 1A of current flowing through it, the voltage output by the sensor changes by 66mV. For example, when the measured current I measured =10A, the output voltage V out for:

[0084] V out =2.5+0.066×10

[0085] =2.5+0.66

[0086] =3.16(V)

[0087] The voltage value V corresponding to the preset maximum current ref It is based on the system's maximum operating current I max The calculated value is used to set the overcurrent protection threshold. For example, if the system maximum operating current I max =20A, then the preset voltage value is V ref for:

[0088] V ref =2.5+0.066×20

[0089] =2.5+1.32

[0090] =3.82(V)

[0091] When the current sensor outputs a voltage V out Exceeds the preset voltage value V ref When , it indicates that the circuit is in overcurrent state, triggering subsequent protection actions.

[0092] Preferably, to further improve the accuracy and reliability of current measurement, a more sensitive current sensor can be selected, such as the ACS712-20A, which has a sensitivity of 100mV / A and is suitable for scenarios requiring higher-precision measurements. Furthermore, to reduce the impact of temperature on the current sensor output, a temperature compensation mechanism can be incorporated into the circuit design. For example, based on the sensor's temperature characteristic curve, the output voltage can be temperature-compensated using a software algorithm to ensure the accuracy of measurement results under different ambient temperatures. Furthermore, to improve the system's anti-interference capability, a low-pass filter can be added to the output of the current sensor to filter out high-frequency noise and further improve signal quality.

[0093] In some embodiments, the preset standard voltage value V REF1 The calculation formula is:

[0094] VREF1 =2.5+S·I PMAX

[0095] Among them, I PMAX is the maximum operating current of the system, S is the sensor sensitivity, and the sensor sensitivity is 66mV.

[0096] It should be noted that the preset standard voltage value V ref The calculation formula is V ref =2.5+S·I max , where I max is the system's maximum operating current, and S is the sensitivity of the current sensor. This formula determines the overcurrent protection threshold: when the voltage output by the current sensor exceeds this preset value, the circuit is deemed to be in an overcurrent state. This method allows precise setting of the protection circuit's triggering conditions, ensuring that the circuit does not falsely trigger under normal operating currents while still providing a timely response in overcurrent conditions. This design leverages the linear output characteristics of the current sensor and, combined with system design parameters, achieves precise control of overcurrent protection.

[0097] Specifically, the preset standard voltage value V ref It is calculated based on the output characteristics of the current sensor. The sensitivity S of the current sensor refers to the change in output voltage caused by a unit current change, usually expressed in millivolts per ampere (mV / A). In this invention, the current sensor ACS712ELCTR-30A-T is selected with a sensitivity of 66mV / A. The maximum operating current of the system is I max Is the maximum current value allowed in the circuit design. Exceeding this value will be considered an overcurrent condition. For example, if the maximum operating current I max =20A, then the preset standard voltage value V ref for:

[0098] V ref =2.5+0.066×20

[0099] =2.5+1.32

[0100] =3.82(V)

[0101] This value serves as the reference voltage for the voltage comparator. When the voltage output by the current sensor exceeds this value, the voltage comparator outputs a high-level signal, triggering subsequent overcurrent protection. In this way, the circuit can promptly cut off power when the current exceeds the designed threshold, protecting the circuit and equipment from damage.

[0102] Preferably, in order to further improve the accuracy and reliability of overcurrent protection, more factors can be considered when calculating the preset standard voltage value. For example, a temperature compensation coefficient can be introduced because the sensitivity of the current sensor may be affected by temperature. According to the temperature characteristic curve of the sensor, the sensitivity correction value ΔS(T) at different temperatures can be calculated. In this case, the calculation formula of the preset standard voltage value can be corrected to V ref =2.5+(S+ΔS(T))·I max In addition, in order to improve the anti-interference ability of the system, a filtering circuit can be added to the input of the voltage comparator to reduce the impact of noise on the comparison result. For example, a low-pass filter can be added to the input of the voltage comparator to filter out high-frequency noise, thereby improving the stability and reliability of the comparator. At the same time, in order to adapt to different application scenarios, the system maximum operating current I max The value of the preset standard voltage V ref , so that the circuit can flexibly respond to different working conditions.

[0103] The above-mentioned embodiments of the present invention have the following beneficial effects: the high-stability self-recovery overcurrent protection circuit of the present invention converts the current signal into a voltage signal through a current sensor, and uses a voltage comparator to compare it with a preset standard voltage value, so as to accurately determine whether the circuit is in an overcurrent state. This design avoids the trouble of replacing a traditional fuse after it blows, and at the same time solves the problem of false triggering or non-triggering of the self-recovery fuse at extreme temperatures, thereby improving the stability and reliability of the circuit protection. In addition, the setting of the delay circuit can effectively avoid false triggering under normal short-term high current conditions, and the delay time can be flexibly set by adjusting the values of the resistor and capacitor, further enhancing the adaptability and accuracy of the circuit. The design of the switch circuit can cut off the circuit connection after the overcurrent signal continues for more than the set time, thereby ensuring the safety of electrical equipment.

[0104] The current sensor utilizes a Hall-effect sensing design with a measurement range of -30A to +30A, meeting the current detection needs of a variety of circuits. The voltage comparator uses the LM2903B dual comparator, which offers stable performance and accurately outputs comparison results. The delay circuit's calculation formula is clear and precise, facilitating parameter adjustment based on actual needs. The switching circuit, comprised of a transistor, pushbutton switch, and thyristor, enables rapid recovery after overcurrent protection. Users can implement self-recovery through simple operations or using devices such as microcontrollers, significantly improving the circuit system's operational efficiency and user experience. Furthermore, the relationship between the current sensor's output voltage and the voltage corresponding to the preset maximum current is clear, and the calculation formula for the preset standard voltage value is simple and easy to use, further enhancing the flexibility and practicality of the circuit design.

[0105] Furthermore, the storage medium of the embodiment of the present application stores program instructions that can implement all the above methods, wherein the program instructions can be stored in the above storage medium in the form of a software product, including a number of instructions for causing a computer device (which can be a personal computer, server, or network device, etc.) or a processor to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, or a terminal device such as a computer, a server, a mobile phone, or a tablet.

[0106] The above descriptions are merely some preferred embodiments of the present invention and an illustration of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in the embodiments of the present invention is not limited to the technical solutions formed by a specific combination of the above-mentioned technical features, but should also encompass other technical solutions formed by any combination of the above-mentioned technical features or their equivalents without departing from the above-mentioned inventive concept. For example, a technical solution formed by mutually replacing the above-mentioned features with (but not limited to) technical features having similar functions disclosed in the embodiments of the present invention.

Claims

1. A high stability self-recovery overcurrent protection circuit, characterized in that: It includes a current sensor, a voltage comparator, a delay circuit and a switching circuit; the output end of the current sensor is connected to the first input end of the voltage comparator, the output end of the voltage comparator is connected to the input end of the delay circuit, and the output end of the delay circuit is connected to the control end of the switching circuit; the current sensor is used to convert the current signal into a voltage signal; the voltage comparator is used to compare the voltage signal with a preset standard voltage value to determine whether the circuit is in an overcurrent state; the delay circuit is used to set the overcurrent duration to avoid false triggering in normal short-term high current situations; the switching circuit is used to cut off the circuit connection after the overcurrent signal continues for more than a set time.

2. The high stability self-recovery overcurrent protection circuit according to claim 1, characterized in that: The current sensor is a Hall-effect inductive current sensor, the current measurement range of the Hall-effect inductive current sensor is from -30A to +30A, and the output end of the Hall-effect inductive current sensor is connected to the first input end of the voltage comparator.

3. The high stability self-recovery overcurrent protection circuit according to claim 1, characterized in that: The voltage comparator is an LM2903B dual comparator, a first input end of the LM2903B dual comparator is connected to the output end of the current sensor, a second input end of the LM2903B dual comparator is connected to a preset standard voltage value, and an output end of the LM2903B dual comparator is connected to the input end of the delay circuit.

4. The high stability self-recovery overcurrent protection circuit according to claim 1, characterized in that: The delay circuit is composed of a capacitor C3, a resistor R5, and a resistor R6. One end of the capacitor C3 is connected to the output end of the voltage comparator, and the other end of the capacitor C3 is connected to the ground. One end of the resistor R5 is connected to the output end of the voltage comparator, and the other end of the resistor R5 is connected to one end of the resistor R6, and the other end of the resistor R6 is connected to the ground. The delay time calculation formula of the delay circuit is: Among them, V t is the capacitor voltage value at any time t, V U is the charging voltage value, R5 is the charging resistance value, and C3 is the charging capacitance value.

5. The high stability self-recovery overcurrent protection circuit according to claim 4, characterized in that: The delay time of the delay circuit is set by adjusting the values of the resistor R5 and the capacitor C3, and the output end of the delay circuit is connected to the control end of the switch circuit.

6. The high stability self-recovery overcurrent protection circuit according to claim 1, characterized in that: The switching circuit includes a transistor Q1, a push switch S1 and a thyristor Q2; the collector of the transistor Q1 is connected to the anode of the thyristor Q2, the emitter of the transistor Q1 is connected to the cathode of the thyristor Q2, and the base of the transistor Q1 is connected to the output end of the delay circuit; one end of the push switch S1 is connected to the gate of the thyristor Q2, and the other end of the push switch S1 is connected to the power supply.

7. The high stability self-recovery overcurrent protection circuit according to claim 6, characterized in that: When the output end of the delay circuit is at a high level, the transistor Q1 is turned on, the anode voltage of the thyristor Q2 drops to the conduction voltage drop of the transistor Q1, and the thyristor Q2 is turned off, cutting off the power supply of subsequent electrical devices.

8. The high stability self-recovery overcurrent protection circuit according to claim 6, characterized in that: When the output end of the delay circuit drops to a low level, the transistor Q1 is turned off, and the key switch S1 is pressed, so that the thyristor Q2 obtains sufficient gate voltage and is turned on to continue to supply power to the subsequent circuit.

9. The high stability self-recovery overcurrent protection circuit according to claim 1, characterized in that: The output voltage value V of the current sensor out The voltage value V corresponding to the preset maximum current REF1 The relationship is: V out =2.5+S·I P Among them, V out is the output voltage value, I P is the measured current, S is the sensor sensitivity, and the sensor sensitivity is 66mV.

10. The high stability self-recovery overcurrent protection circuit according to claim 1, characterized in that: The preset standard voltage value V REF1 The calculation formula is: V REF1 =2.5+S·I PMAX Among them, I PMAX is the maximum operating current of the system, S is the sensor sensitivity, and the sensor sensitivity is 66mV.

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