An overload and short circuit protection circuit and electronic circuit breaker

Abstract

The embodiment of the application discloses an overload and short-circuit protection circuit and an electronic circuit breaker, and the overload and short-circuit protection circuit comprises an overload detection circuit, a short-circuit detection circuit and a driving circuit; an input end of the overload detection circuit is connected with a current sampling circuit; an input end of the short-circuit detection circuit is connected with the current sampling circuit; a first input end of the driving circuit is connected with an output end of the overload detection circuit, and a second input end of the driving circuit is connected with an output end of the short-circuit detection circuit. The application does not need a single-chip microcomputer, realizes the overload and short-circuit protection function, has fast response speed, is stable and reliable, and has low cost.

Description

Technical Field

[0001] This invention relates to the field of circuit breaker technology, and more particularly to an overload and short-circuit protection circuit and an electronic circuit breaker. Background Technology

[0002] Electronic circuit breakers are widely used protective electrical appliances that provide overload and short-circuit protection for power distribution system facilities and electrical equipment. Existing electronic circuit breakers, especially DC circuit breakers, are based on microcontrollers, using signal acquisition and data processing to achieve their protection functions, with the microcontroller executing overload or short-circuit protection. However, in high-interference environments, hardware or software malfunctions in microcontrollers can directly lead to the failure of the electronic circuit breaker's protection function, affecting its stability and the safety of subsequent systems. Furthermore, electronic circuit breakers require signal acquisition and data processing before fault diagnosis and protection action, resulting in slow response times and poor protection effectiveness. The high cost of microcontrollers directly contributes to the high cost and selling price of electronic circuit breakers, leading to higher operating costs for users.

[0003] The above problems urgently need to be solved. Summary of the Invention

[0004] To address the related technical problems, this invention provides an overload and short-circuit protection circuit and an electronic circuit breaker to solve the problems mentioned in the background section above.

[0005] To achieve the above objectives, the embodiments of the present invention adopt the following technical solutions:

[0006] In a first aspect, embodiments of the present invention provide an overload and short circuit protection circuit, including an overload detection circuit, a short circuit detection circuit, and a driving circuit;

[0007] The input terminal of the overload detection circuit is connected to the current sampling circuit, which converts the current signal in the circuit loop collected by the current sampling circuit into a voltage signal, and after filtering and amplifying the voltage signal, determines whether it is greater than the reference voltage. If it is greater, it determines that an overload has occurred in the circuit loop and outputs an overload control signal to the drive circuit. The filtering time is T1, and the amplification factor is N1.

[0008] The input terminal of the short-circuit detection circuit is connected to the current sampling circuit. It is used to convert the current signal in the circuit loop collected by the current sampling circuit into a voltage signal, and after filtering and amplifying the voltage signal, it determines whether the voltage signal is greater than a reference voltage. If it is greater, it determines that a short circuit has occurred in the circuit loop and outputs a short-circuit control signal to the drive circuit. When the short-circuit detection circuit filters and amplifies the voltage signal, the filtering time is T2, the amplification factor is N2, T2 is less than T1, and N2 is less than N1.

[0009] The first input terminal of the driving circuit is connected to the output terminal of the overload detection circuit, and the second input terminal of the driving circuit is connected to the output terminal of the short circuit detection circuit. The driving circuit is used to output a driving voltage to the protection switch in the circuit loop after receiving an overload control signal or a short circuit control signal. The protection switch turns off the power supply of the circuit loop after receiving the driving voltage.

[0010] By setting different filtering times and amplification factors for the overload detection circuit and the short-circuit detection circuit, a time difference exists in the signal processing of the two circuits. Therefore, the overload detection circuit and the short-circuit detection circuit can perform both overload and short-circuit detection for the same signal collected by the current sampling circuit. That is, when the circuit is overloaded, the overload detection circuit will detect the overload and output an overload control signal to the drive circuit, while the short-circuit detection circuit will not respond; when the circuit is short-circuited, the short-circuit detection circuit will detect the short circuit and output a short-circuit control signal to the drive circuit, while the overload detection circuit will not respond. The entire overload and short-circuit protection circuit does not require a microcontroller; it achieves overload and short-circuit protection functions solely through a pure hardware circuit composed of the overload detection circuit, the short-circuit detection circuit, and the drive circuit. The protection switch will directly cut off the power supply to the circuit loop after receiving the drive voltage output from the drive circuit. This not only results in fast response speed but also stability, reliability, and low cost.

[0011] As an optional implementation, the overload detection circuit includes a first filter circuit, a first operational amplifier, and a first comparator;

[0012] The first terminal of the first filter circuit is connected to the current sampling circuit, and the second terminal of the first filter circuit is connected to the non-inverting input terminal of the first operational amplifier.

[0013] The output of the first operational amplifier is connected to the non-inverting input of the first comparator, and the inverting input of the first comparator is connected to the reference voltage.

[0014] The first operational amplifier is used to convert the current signal in the circuit loop acquired by the current sampling circuit into a voltage signal, and then amplify the voltage signal after filtering by the first filtering circuit. The amplified voltage signal is then output to the first comparator. The first comparator is used to determine whether the voltage signal input to the first operational amplifier is greater than the reference voltage. If it is greater, it determines that an overload has occurred in the circuit loop and outputs an overload control signal to the drive circuit.

[0015] An overload detection circuit is constructed using a first filter circuit, a first operational amplifier, and a first comparator. The first filter circuit filters the voltage signal according to a set filtering time. The first operational amplifier amplifies the filtered voltage signal according to a set amplification factor. The first comparator compares the voltage signal input to the first operational amplifier with a reference voltage. If the input voltage is greater than the reference voltage, an overload is determined to have occurred in the circuit loop. The first filter circuit, the first operational amplifier, and the first comparator are all general-purpose, mature, and stable circuit components, or are composed of general-purpose circuit components, which improves the stability and reliability of the overload detection circuit, reduces costs, and the entire overload detection process is a direct judgment of the electrical signal without data analysis, resulting in a fast response speed and rapid detection of circuit overload.

[0016] As an optional implementation, the short-circuit detection circuit includes a second filter circuit, a second operational amplifier, and a second comparator;

[0017] The first terminal of the second filter circuit is connected to the current sampling circuit, and the second terminal of the second filter circuit is connected to the non-inverting input terminal of the second operational amplifier.

[0018] The output of the second operational amplifier is connected to the non-inverting input of the second comparator, and the inverting input of the second comparator is connected to the reference voltage.

[0019] The second operational amplifier is used to convert the current signal in the circuit loop acquired by the current sampling circuit into a voltage signal, and then amplify the voltage signal after filtering by the second filtering circuit. The amplified voltage signal is then output to the second comparator. The second comparator is used to determine whether the voltage signal input to the second operational amplifier is greater than the reference voltage. If it is greater, it determines that a short circuit has occurred in the circuit loop and outputs a short circuit control signal to the driving circuit.

[0020] A short-circuit detection circuit is constructed using a second filter circuit, a second operational amplifier, and a second comparator. The second filter circuit filters the voltage signal according to a set filtering time. The second operational amplifier amplifies the filtered voltage signal according to a set amplification factor. The second comparator compares the voltage signal input to the second operational amplifier with a reference voltage. If the input voltage is greater than the reference voltage, a short circuit is determined to have occurred in the circuit loop. The second filter circuit, the second operational amplifier, and the second comparator are all general-purpose, mature, and stable circuit components, or are composed of general-purpose circuit components, which improves the stability and reliability of the short-circuit detection circuit, reduces costs, and the entire short-circuit detection process is a direct judgment of the electrical signal, without data analysis, resulting in a fast response speed and rapid detection of short circuits.

[0021] As an optional implementation, the driving circuit includes a first OR gate; the input A terminal of the first OR gate is connected to the output terminal of a first comparator, and the input B terminal is connected to the output terminal of a second comparator, for outputting a high level after receiving an overload control signal input from the first comparator or a short-circuit control signal input from the second comparator.

[0022] The first OR gate connects to the outputs of the first comparator and the second comparator via input A and input B, respectively. Using general, mature and stable circuit components, the OR gate directly outputs a drive signal after receiving either an overload control signal or a short-circuit control signal. It has a fast response speed, is stable and reliable, and has a low cost.

[0023] As an optional implementation, the driving circuit further includes a thyristor; the control electrode of the thyristor is connected to the output terminal of the first OR gate, the cathode of the thyristor is connected to the negative terminal of the power supply in the circuit loop, and the anode of the thyristor is connected to the protection switch, for conducting after receiving a high level output from the first OR gate, thereby turning off the protection switch at a low level.

[0024] When the overload detection circuit detects an overload or the short-circuit detection circuit detects a short circuit, the thyristor will remain in the ON state after receiving a high-level output from the first OR gate. The protection switch will remain in the OFF state with a low level, thus keeping the power supply in the circuit off. This provides reliable protection against overload and short circuits. The thyristor is a general-purpose, mature, and stable circuit component, offering stability, reliability, and low cost.

[0025] In a second aspect, embodiments of the present invention provide an electronic circuit breaker, the electronic circuit breaker including a current sampling circuit, a protective switch and the overload and short circuit protection circuit described in any of the first aspects above;

[0026] The current sampling circuit is connected to the overload and short circuit protection circuit and is used to collect the current signal in the circuit loop.

[0027] The protection switch is connected in series with the current sampling circuit and the load in the circuit loop. When an overload or short circuit occurs in the circuit loop, it receives the driving voltage output by the overload and short circuit protection circuit and shuts off the power supply of the circuit loop.

[0028] Electronic circuit breakers do not require a microcontroller. They achieve overload and short-circuit protection functions solely through a pure hardware circuit consisting of a current sampling circuit, a protective switch, and an overload and short-circuit protection circuit. Upon receiving the drive voltage output from the overload and short-circuit protection circuit, the protective switch will directly cut off the power supply to the circuit loop. This not only provides a fast response but also ensures stability, reliability, and low cost.

[0029] As an optional implementation, the electronic circuit breaker further includes an overcurrent protection circuit; the overcurrent protection circuit is used to control the current in the circuit to gradually increase when the circuit is energized.

[0030] The overcurrent protection circuit enables the current in the circuit to gradually increase when the circuit is powered on, realizing the overcurrent protection function of the electronic circuit breaker and effectively solving the problem of peak surge when the circuit is first powered on.

[0031] As an optional implementation, the overcurrent protection circuit includes a first resistor, a first transistor, a first capacitor, a second resistor, a third resistor, and a second transistor;

[0032] The first terminal of the first resistor is connected to the drain of the first transistor, and the first terminal of the first resistor is also connected to the first terminal of the protection switch.

[0033] The source of the first transistor is connected to the second terminal of the first resistor, and the source of the first transistor is also connected to the first terminal of the first capacitor and the positive terminal of the power supply in the circuit loop.

[0034] The second terminal of the first capacitor is connected to the gate of the first transistor. The second terminal of the first capacitor is also connected to the first terminal of the second resistor. The first terminal of the second resistor is connected to the first terminal of the third resistor. The second terminal of the third resistor is connected to the positive terminal of the power supply in the circuit loop.

[0035] The second end of the second resistor is connected to the drain of the second transistor, the gate of the second transistor is connected to the second end of the protection switch, and the source of the second transistor is connected to the negative terminal of the power supply in the circuit loop.

[0036] When the circuit is powered on, the first resistor is connected to the circuit. Current flows through the first resistor before entering the load. The first capacitor controls the time it takes for the first transistor to fully conduct, allowing the transistor to gradually turn on and thus gradually increasing the current, achieving overcurrent protection. Furthermore, once the first transistor is fully conducting, the first resistor is no longer connected to the circuit, effectively solving the problem of the first resistor constantly overheating. The first resistor, first transistor, first capacitor, second resistor, third resistor, and second transistor that make up the overcurrent protection circuit are all general-purpose, mature, and stable circuit components, ensuring stability, reliability, and low cost.

[0037] As an optional implementation, the electronic circuit breaker further includes a second short-circuit protection circuit; the second short-circuit protection circuit includes a third transistor;

[0038] The third transistor is connected to the protection switch and the current sampling circuit, and is used to control the protection switch to turn off when the loop current value collected by the current sampling circuit reaches the preset short-circuit current value.

[0039] When the loop current value collected by the current sampling circuit through the third transistor reaches the preset short-circuit current value, the protection switch is controlled to turn off, so that even if there is an overload or a functional failure of the short-circuit protection circuit, the electronic circuit breaker can still achieve the short-circuit protection function. Moreover, the third transistor is a general-purpose, mature and stable circuit component with fast response speed, stability and reliability, and low cost.

[0040] As an optional implementation, the electronic circuit breaker further includes a self-test circuit; the self-test circuit is connected to the protection switch and is used to detect whether the status of the protection switch is normal when the circuit is powered on.

[0041] The self-testing circuit enables the detection of the status of the protection switch, making it easier for staff to understand whether the protection switch is working properly. If an abnormality is found in the protection switch, it can be replaced or repaired in a timely manner to ensure the normal operation of the electronic circuit breaker. Attached Figure Description

[0042] To more clearly illustrate and understand the technical solutions in the embodiments of the present invention, the accompanying drawings used in the background technology and embodiment descriptions of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the content of the embodiments of the present invention and these drawings without creative effort.

[0043] Figure 1 This is a schematic diagram of the overload and short circuit protection circuit provided in Embodiment 1 of the present invention;

[0044] Figure 2This is a schematic diagram of the overload and short circuit protection circuit provided in Embodiment 1 of the present invention;

[0045] Figure 3 The structural diagram of the electronic circuit breaker provided in Embodiment 2 of the present invention is as follows;

[0046] Figure 4 This is a schematic diagram of the circuit structure of the electronic circuit breaker provided in Embodiment 2 of the present invention. Detailed Implementation

[0047] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] Example 1

[0049] Please refer to Figure 1 The above, Figure 1 This is a schematic diagram of the overload and short circuit protection circuit provided in Embodiment 1 of the present invention. As shown in the figure, the overload and short circuit protection circuit 100 in this embodiment includes an overload detection circuit 101, a short circuit detection circuit 102, and a drive circuit 103;

[0050] The input terminal of the overload detection circuit 101 is connected to the current sampling circuit 104. It is used to convert the current signal in the circuit loop collected by the current sampling circuit 104 into a voltage signal, and to filter and amplify the voltage signal to determine whether it is greater than a reference voltage. If it is greater, it is determined that an overload has occurred in the circuit loop, and an overload control signal is output to the drive circuit 103. The filtering time is T1, and the amplification factor is N1.

[0051] The input terminal of the short-circuit detection circuit 102 is connected to the current sampling circuit 104. It is used to convert the current signal in the circuit loop collected by the current sampling circuit 104 into a voltage signal, and after filtering and amplifying the voltage signal, determine whether it is greater than a reference voltage. If it is greater, it is determined that a short circuit has occurred in the circuit loop, and a short-circuit control signal is output to the drive circuit 103. When the short-circuit detection circuit 102 filters and amplifies the voltage signal, the filtering time is T2, the amplification factor is N2, T2 is less than T1, and N2 is less than N1.

[0052] The first input terminal of the drive circuit 103 is connected to the output terminal of the overload detection circuit 101, and the second input terminal of the drive circuit 103 is connected to the output terminal of the short circuit detection circuit 102. The drive circuit 103 is used to output a drive voltage to the protection switch 105 in the circuit loop after receiving an overload control signal or a short circuit control signal. The protection switch 105 turns off the power supply of the circuit loop after receiving the drive voltage.

[0053] In this embodiment, different filtering times and amplification factors are set for the overload detection circuit 101 and the short-circuit detection circuit 102, resulting in a time difference in the signal processing of the overload detection circuit 101 and the short-circuit detection circuit 102. Therefore, the overload detection circuit 101 and the short-circuit detection circuit 102 can perform both overload detection and short-circuit detection for the same signal collected by the current sampling circuit 104. That is, when the circuit is overloaded, the overload detection circuit 101 will detect the overload and output an overload control signal to the drive circuit 103, while the short-circuit detection circuit 102 will not respond; when the circuit is short-circuited, the short-circuit detection circuit 102 will detect the short circuit and output a short-circuit control signal to the drive circuit 103, while the overload detection circuit 101 will not respond. The entire overload and short circuit protection circuit 100 does not require a microcontroller. It achieves overload and short circuit protection functions through a pure hardware circuit consisting of an overload detection circuit 101, a short circuit detection circuit 102, and a drive circuit 103. After receiving the drive voltage output by the drive circuit 103, the protection switch 105 will directly cut off the power supply of the circuit loop. It is not only fast in response, but also stable, reliable, and low in cost.

[0054] It should be noted that the filtering time and amplification factor of the overload detection circuit 101 and the short circuit detection circuit 102 need to be adjusted according to the specific circumstances of the application scenario, such as the load size, to ensure that the overload detection circuit 101 and the short circuit detection circuit 102 do not falsely trigger when they are working, and to achieve the overload and protection functions according to the above design timing.

[0055] For example, such as Figure 2 The overload detection circuit 101 includes a first filter circuit, a first operational amplifier U3A, and a first comparator U4A;

[0056] The first terminal of the first filter circuit is connected to the current sampling circuit 104, and the second terminal of the first filter circuit is connected to the non-inverting input terminal of the first operational amplifier U3A.

[0057] The output terminal of the first operational amplifier U3A is connected to the non-inverting input terminal of the first comparator U4A, and the inverting input terminal of the first comparator U4A is connected to the reference voltage.

[0058] The first operational amplifier U3A is used to convert the current signal in the circuit loop collected by the current sampling circuit 104 into a voltage signal, and then amplify the voltage signal after filtering by the first filtering circuit. The amplified voltage signal is then output to the first comparator U4A. The first comparator U4A is used to determine whether the voltage signal input to the first operational amplifier U3A is greater than the reference voltage. If it is greater, it is determined that an overload has occurred in the circuit loop, and an overload control signal is output to the drive circuit 103.

[0059] In this embodiment, an overload detection circuit 101 is constructed using a first filter circuit, a first operational amplifier U3A, and a first comparator U4A. The first filter circuit filters the voltage signal according to a set filtering time. The first operational amplifier U3A amplifies the filtered voltage signal according to a set amplification factor. The first comparator U4A compares the voltage signal input to the first operational amplifier U3A with a reference voltage. If the input voltage is greater than the reference voltage, an overload is determined to have occurred in the circuit loop. The first filter circuit, the first operational amplifier U3A, and the first comparator U4A are all general-purpose, mature, and stable circuit components or are composed of general-purpose circuit components, which improves the stability and reliability of the overload detection circuit 101, reduces costs, and the entire overload detection process is a direct judgment of the electrical signal without data analysis, resulting in a fast response speed and rapid detection of circuit overload.

[0060] For example, such as Figure 2 As shown in the figure, the protective switch Q4 is the same as... Figure 1 In embodiment 105, the protection switch Q4 uses, but is not limited to, an N-MOS transistor. The current sampling circuit 104 includes a sampling resistor R4. The first filter circuit includes a resistor R5 and a capacitor C2. The first terminal of the sampling resistor R4 is connected to the negative terminal of the power supply, the second terminal of the sampling resistor R4 is connected to the first terminal of the resistor R5, and the sampling resistor R4 is also connected to the source of the protection switch Q4. The second terminal of the resistor R5 is connected to the first terminal of the capacitor C2, and the second terminal of the resistor R5 is also connected to the non-inverting input terminal of the first operational amplifier U3A. The second terminal of the capacitor C2 is connected to the negative terminal of the power supply. In this embodiment, the N-MOS transistor Q3, sampling resistor R4, resistor R5, and capacitor C2 are all general-purpose, mature, and stable circuit components, which are stable, reliable, and low in cost.

[0061] For example, such as Figure 2 As shown, the short-circuit detection circuit 102 includes a second filter circuit, a second operational amplifier U3B, and a second comparator U4B;

[0062] The first terminal of the second filter circuit is connected to the current sampling circuit 104, and the second terminal of the second filter circuit is connected to the non-inverting input terminal of the second operational amplifier U3B.

[0063] The output terminal of the second operational amplifier U3B is connected to the non-inverting input terminal of the second comparator U4B, and the inverting input terminal of the second comparator U4B is connected to the reference voltage.

[0064] The second operational amplifier U3B is used to convert the current signal in the circuit loop collected by the current sampling circuit 104 into a voltage signal, and then amplifies the voltage signal after filtering by the second filtering circuit. The amplified voltage signal is then output to the second comparator U4B. The second comparator U4B is used to determine whether the voltage signal input to the second operational amplifier U3B is greater than the reference voltage. If it is greater, it is determined that a short circuit has occurred in the circuit loop, and a short circuit control signal is output to the driving circuit 103.

[0065] In this embodiment, a short-circuit detection circuit 102 is constructed using a second filter circuit, a second operational amplifier U3B, and a second comparator U4B. The second filter circuit filters the voltage signal according to a set filtering time. The second operational amplifier U3B amplifies the filtered voltage signal according to a set amplification factor. The second comparator U4B compares the voltage signal input to the second operational amplifier U3B with a reference voltage. If the input voltage is greater than the reference voltage, a short circuit is determined to have occurred in the circuit loop. The second filter circuit, the second operational amplifier U3B, and the second comparator U4B are all general-purpose, mature, and stable circuit components or are composed of general-purpose circuit components, which improves the stability and reliability of the short-circuit detection circuit 102, reduces costs, and the entire short-circuit detection process is a direct judgment of the electrical signal without data analysis, resulting in a fast response speed and rapid detection of short circuits.

[0066] For example, such as Figure 2 As shown, the second filter circuit includes a resistor R6 and a capacitor C3. The first terminal of resistor R6 is connected to the first terminal of sampling resistor R4 and the source of protection switch Q4. The second terminal of resistor R6 is connected to the first terminal of capacitor C3. The second terminal of resistor R6 is also connected to the non-inverting input terminal of the second operational amplifier U3B. The second terminal of capacitor C3 is connected to the negative terminal of the power supply. In this embodiment, resistor R6 and capacitor C3 are both general-purpose, mature, and stable circuit components, ensuring stability, reliability, and low cost.

[0067] For example, such as Figure 2 As shown, the driving circuit 103 includes a first OR gate U1; the input A terminal of the first OR gate U1 is connected to the output terminal of the first comparator U4A, and the input B terminal is connected to the output terminal of the second comparator U4B, and is used to output a high level after receiving an overload control signal input from the first comparator U4A or a short-circuit control signal input from the second comparator U4B.

[0068] In this embodiment, the first OR gate U1 is connected to the output of the first comparator U4A and the output of the second comparator U4B through input A and input B respectively. Using general, mature and stable circuit components, the OR gate directly outputs a drive signal after receiving either the overload control signal or the short circuit control signal. It has a fast response speed, is stable and reliable, and has a low cost.

[0069] For example, such as Figure 2 As shown, the driving circuit 103 also includes a thyristor Q5; the control electrode of the thyristor Q5 is connected to the output terminal of the first OR gate U1, the cathode of the thyristor Q5 is connected to the negative terminal of the power supply in the circuit loop, and the anode of the thyristor Q5 is connected to the protection switch Q4, which is used to turn on after receiving a high level output from the first OR gate U1, so that the protection switch Q4 is turned off at a low level.

[0070] In this embodiment, when the overload detection circuit 101 detects an overload in the circuit loop or the short circuit detection circuit 102 detects a short circuit in the circuit loop, the thyristor Q5 will remain in the on state after receiving a high level output from the first OR gate U1, and the protection switch Q4 will remain in the off state at a low level. Therefore, the power supply in the circuit loop will also remain off, achieving reliable protection in the event of overload and short circuit. The thyristor Q5 is a general-purpose, mature, and stable circuit component, offering stability, reliability, and low cost.

[0071] Example 2

[0072] Please refer to Figure 3 As shown, Figure 3 This is a structural diagram illustrating the principle of an electronic circuit breaker provided in Embodiment 2 of the present invention. In this embodiment, the electronic circuit breaker 200 includes a current sampling circuit 201, a protective switch 202, and the overload and short-circuit protection circuit 100 described in Embodiment 1 above.

[0073] The current sampling circuit 201 is connected to the overload and short circuit protection circuit 100 and is used to collect the current signal in the circuit loop.

[0074] The protection switch 202 is connected in series with the current sampling circuit 201 and the load in the circuit loop. When an overload or short circuit occurs in the circuit loop, it receives the driving voltage output by the overload and short circuit protection circuit 100 and shuts off the power supply of the circuit loop.

[0075] In this embodiment, the electronic circuit breaker 200 does not require a microcontroller. It achieves overload and short-circuit protection functions through a pure hardware circuit consisting of a current sampling circuit 201, a protection switch 202, and an overload and short-circuit protection circuit 100. After receiving the drive voltage output by the overload and short-circuit protection circuit 100, the protection switch 202 will directly cut off the power supply of the circuit loop. This not only has a fast response speed, but is also stable, reliable, and low in cost.

[0076] For example, the electronic circuit breaker 200 further includes an overcurrent protection circuit; the overcurrent protection circuit is used to control the current in the circuit to gradually increase when the circuit loop is energized.

[0077] In this embodiment, the overcurrent protection circuit enables the gradual increase of current in the circuit when the circuit is powered on, thereby realizing the overcurrent protection function of the electronic circuit breaker 200 and effectively solving the problem of peak surge when the circuit is first powered on.

[0078] For example, such as Figure 4 As shown in the figure, the protective switch Q4 is the same as... Figure 3 202, the overcurrent protection circuit includes a first resistor R1, a first transistor Q1, a first capacitor C1, a second resistor R2, a third resistor R3, and a second transistor Q2;

[0079] The first terminal of the first resistor R1 is connected to the drain of the first transistor Q1, and the first terminal of the first resistor R1 is also connected to the first terminal of the protection switch Q4.

[0080] The source of the first transistor Q1 is connected to the second terminal of the first resistor R1. The source of the first transistor Q1 is also connected to the first terminal of the first capacitor C1 and the positive terminal of the power supply in the circuit loop.

[0081] The second terminal of the first capacitor C1 is connected to the gate of the first transistor Q1. The second terminal of the first capacitor C1 is also connected to the first terminal of the second resistor R2. The first terminal of the second resistor R2 is connected to the first terminal of the third resistor R3. The second terminal of the third resistor R3 is connected to the positive terminal of the power supply in the circuit loop.

[0082] The second end of the second resistor R2 is connected to the drain of the second transistor Q2, the gate of the second transistor Q2 is connected to the second end of the protection switch Q4, and the source of the second transistor Q2 is connected to the negative terminal of the power supply in the circuit loop.

[0083] For example, such as Figure 4 As shown, the first transistor Q1 is, but is not limited to, a P-MOS transistor. The second transistor Q2 is, but is not limited to, an N-MOS transistor. The first resistor R1 is a cement resistor or an NTC resistor.

[0084] In this embodiment, when the circuit is powered on, the first resistor R1 is connected to the circuit. Current flows through the first resistor R1 before entering the load. The first capacitor C1 controls the time it takes for the first transistor Q1 to fully conduct, allowing Q1 to gradually turn on and thus gradually increase the current during power-on, achieving overcurrent protection. Furthermore, once Q1 is fully turned on, the first resistor R1 is no longer connected to the circuit, effectively solving the problem of R1 constantly overheating when continuously connected. The first resistor R1, first transistor Q1, first capacitor C1, second resistor R2, third resistor R3, and second transistor Q2 that make up the overcurrent protection circuit are all general-purpose, mature, and stable circuit components, ensuring stability, reliability, and low cost.

[0085] For example, the electronic circuit breaker 200 further includes a second short-circuit protection circuit; the second short-circuit protection circuit includes a third transistor Q3;

[0086] The third transistor Q3 is connected to the protection switch Q4 and the current sampling circuit 201, and is used to control the protection switch Q4 to turn off when the loop current value collected by the current sampling circuit 201 reaches the preset short-circuit current value.

[0087] For example, such as Figure 4 As shown, the third transistor Q3 is, but is not limited to, a bipolar transistor.

[0088] In this embodiment, when the loop current value collected by the current sampling circuit 201 reaches the preset short-circuit current value through the third transistor Q3, the protection switch Q4 is controlled to turn off, so that even if the electronic circuit breaker 200 is overloaded or the short-circuit protection circuit 100 fails, the electronic circuit breaker 200 can still achieve the short-circuit protection function. Moreover, the third transistor Q3 is a general-purpose, mature and stable circuit component with fast response speed, stability and reliability, and low cost.

[0089] For example, the electronic circuit breaker 200 further includes a self-test circuit; the self-test circuit is connected to the protection switch Q4 and is used to detect whether the state of the protection switch Q4 is normal when the circuit is powered on.

[0090] In this embodiment, the status detection of the protection switch Q4 is realized through the self-test circuit, which makes it easier for the staff to understand whether the protection switch Q4 is normal. If the protection switch Q4 is found to be abnormal, it can be replaced or repaired in time to ensure the normal operation of the electronic circuit breaker 200.

[0091] For example, such as Figure 4As shown, the self-test circuit includes a second OR gate U2, a self-test indicator LED1, resistors R16 and R17, a transistor Q6, and a resistor R18. The collector of transistor Q6 is connected to the first pin of the PLC; the second pin of the PLC is connected to the drain of the second transistor Q2. The electronic circuit breaker 200 also includes a button power-on circuit, which includes a self-locking button switch SW1, a capacitor C6, an N-MOS transistor Q6, resistors R19 and R20, and an indicator LED2.

[0092] like Figure 4 As shown, the working principle of the electronic circuit breaker 200 in this embodiment is as follows: When the self-locking button switch SW1 is pressed, the button is closed, the Ugs of the N-MOS transistor Q7 is 0, the N-MOS transistor Q7 is not conducting, the gate of the protection switch Q4 is divided by the resistors R19 and R20, the gate of the protection switch Q4 is in a high potential state, thus the protection switch Q4 is conducting, and the current path is established; the current flows through the fuse F1, through the resistor R1 into the load, and then through the protection switch Q4 and the sampling resistor R4 to ground. At the same time, the negative terminal of the LED indicator LED2 is in a high potential state. Due to the presence of the thyristor Q5 and the resistor R20, the negative terminal of the LED indicator LED2 is not 12V. Therefore, the LED indicator LED2 will be in a dim state. When the loop current value collected by the sampling resistor R4 reaches the preset short-circuit current value, the protection switch Q4 can be quickly controlled to turn off through the resistor R20 and the third transistor Q3. At this time, the Ugs voltage of the second transistor Q2 in the overcurrent protection circuit is raised to a high potential, and the second transistor Q2 conducts. The second resistor R2 and the third resistor R3 divide the Ugs voltage of the first transistor Q1. Due to the presence of the first capacitor C1, the Cgs capacitance is increased, which prolongs the time for the first transistor Q1 to fully conduct. This allows resistor R1 to be gradually short-circuited, achieving a gradual increase in current when the circuit is powered on, thus achieving the purpose of overcurrent protection. Moreover, after the first transistor Q1 is fully turned on, the first resistor R1 will no longer be connected to the circuit, effectively avoiding the situation where the first resistor R1, which is used as a ground resistor or NTC resistor, is constantly connected to the circuit and gets hot, causing the resistance value to decrease. When the current level drops, the protection capability against inrush current decreases. At this time, the PLC pin connected to the overcurrent protection circuit outputs a low level, and the PLC receives the status information of the electronic circuit breaker 200. After the first transistor Q1 is turned on, the current flows into the load and the indicator LED3. The indicator LED3 is lit, indicating the operating status of the load. At D1 and G1 of the protection switch Q4, the level flows into the second OR gate U2 of the self-test circuit. The second OR gate U2 outputs a high level, the self-test indicator LED1 is turned off, and at the same time, the self-test pin of the self-test circuit outputs a low level. The PLC receives the self-test status information of the electronic circuit breaker 200 to realize the status check of the protection switch Q4.

[0093] Current flows through sampling resistor R4, generating a voltage drop. The base-emitter voltage of the third transistor Q3 is raised. If the current exceeds the preset short-circuit current value, the third transistor Q3 will conduct at a speed of nanoseconds, forcing the protection switch Q4 to turn on. This ensures that even if there is an overload or a functional failure of the short-circuit protection circuit 100, the electronic circuit breaker 200 can still achieve the short-circuit protection function.

[0094] The voltage drop across sampling resistor R4 enters the first operational amplifier U3A and the second operational amplifier U3B. The amplification factors of operational amplifiers U3A and U3B are different and can be flexibly adjusted according to the actual load and wire diameter. The filtering times at the non-inverting inputs of operational amplifiers U3A and U3B are also different, giving the circuit a time difference, providing both overload and short-circuit protection for the same input voltage. The voltage signals output from operational amplifiers U3A and U3B are maintained by diodes D1 and D2 before entering the inputs of comparators U4A and U4B. Comparators U4A and U4B compare the input voltage with a reference voltage, and the result is input to the first OR gate U1. When a short circuit occurs in the circuit, the voltage across the sampling resistor R4 quickly passes through the second operational amplifier U3B, enters the second comparator U4B, and then enters the first OR gate U1. The first OR gate U1 outputs a high level to activate the thyristor Q5, causing the protection switch Q4 to close. At the same time, because the thyristor Q5 is turned on, the second transistor Q2 of the overcurrent protection circuit is turned off, the PLC pin outputs a high level, and the PLC receives the signal from the electronic circuit breaker 200, enabling the host computer to understand the status of the electronic circuit breaker 200. Therefore, when the circuit is short-circuited, the output state changes first in the second operational amplifier U3B. Then, after passing through the second comparator U4B, the state of the first OR gate U1 changes, cutting off the current loop. The thyristor Q5 turns on, the indicator LED2 lights up red, the indicator LE3 turns off green, and the PLC pin outputs a high level, indicating that the circuit breaker state has changed. At this time, because the filtering at the input end of the second operational amplifier U3A is more severe and the filtering time is longer, the output level will take some time to change. By this time, the circuit has been disconnected. At the same time, the first transistor Q1 of the overcurrent protection circuit slowly turns off, and the first resistor R1 is gradually connected in parallel to the circuit, further enhancing circuit safety.

[0095] When the circuit is overloaded, if the load is capacitive or inductive, such as a motor, the circuit will experience a sudden surge of current several times or even tens of times the rated current at the moment of power-on. At this time, a short-lived voltage spike will appear across the sampling resistor R4, exceeding the set current value. The voltage will then flow through the second operational amplifier U3B. However, since the amplification factor of the second operational amplifier U3B is less than that of the first operational amplifier U3A, the output voltage will not trigger the second operational amplifier U3B. This prevents false triggering of the short-circuit protection and forces the output state of the first OR gate U1 to be determined solely by the output level of the first operational amplifier U3B. When an overload occurs, the voltage will be filtered by resistor R5 and capacitor C2 before entering the first operational amplifier U3A. If the voltage continues to rise, the first OR gate U1 will output a high level, and indicator LED2 will light up red. If, after filtering, the voltage drops but does not reach the set reference voltage, it is considered to be due to a capacitive or inductive load. The first OR gate U1 will continue to maintain a low level, and the circuit will operate normally. Indicator LED2 will light up red, and indicator LED3 will light up green. At the same time, the first transistor Q1 of the overcurrent protection circuit will slowly turn off, and the first resistor R1 will gradually be connected in parallel with the circuit to further enhance circuit safety.

[0096] When the button on the self-locking push-button switch SW1 is released, the N-MOS transistor Q7 turns on, pulling the Ugs of the protection switch Q4 low, causing the protection switch Q4 to open. After the circuit is disconnected, the first transistor of the overcurrent protection circuit slowly turns off, and the first resistor R1 is gradually connected in parallel to the circuit to enhance circuit safety. Current flows away from the first resistor R1, the green light of indicator LED3 goes out, and the red light of indicator LED2 dimly illuminates. It is worth mentioning that the response speed of the overload protection of the electronic circuit breaker 200 in this embodiment can be adjusted by capacitor C2. For example, if the load is several motors, the overload capacitor C2 and the amplification factor of the short-circuit detection circuit can be adjusted for adaptation.

[0097] The electronic circuit breaker 200 proposed in this embodiment of the invention provides multiple protections for electrical equipment through a fuse, an overcurrent protection circuit, and an overload and short-circuit protection circuit 100. It does not require a microcontroller and the entire circuit is implemented purely in hardware. It not only has a fast response speed and the protection switch does not arc, but it is also stable, reliable, and highly safe. Moreover, it is low in cost, which reduces the user's operating costs.

[0098] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. An overload and short-circuit protection circuit, characterized in that, Includes overload detection circuit, short circuit detection circuit, and drive circuit; The input terminal of the overload detection circuit is connected to the current sampling circuit, which converts the current signal in the circuit loop collected by the current sampling circuit into a voltage signal, and after filtering and amplifying the voltage signal, determines whether it is greater than the reference voltage. If it is greater, it determines that an overload has occurred in the circuit loop and outputs an overload control signal to the drive circuit. The filtering time is T1, and the amplification factor is N1. The input terminal of the short-circuit detection circuit is connected to the current sampling circuit. It converts the current signal collected by the current sampling circuit into a voltage signal, filters and amplifies the voltage signal, and then determines whether the voltage signal is greater than a reference voltage. If it is greater, a short circuit is determined to have occurred in the circuit, and a short-circuit control signal is output to the drive circuit. When the short-circuit detection circuit filters and amplifies the voltage signal, the filtering time is T2, the amplification factor is N2, T2 is less than T1, and N2 is less than N1. The first input terminal of the driving circuit is connected to the output terminal of the overload detection circuit, and the second input terminal of the driving circuit is connected to the output terminal of the short circuit detection circuit. The driving circuit is used to output a driving voltage to the protection switch in the circuit loop after receiving an overload control signal or a short circuit control signal. The protection switch turns off the power supply of the circuit loop after receiving the driving voltage.

2. The overload and short-circuit protection circuit according to claim 1, characterized in that, The overload detection circuit includes a first filter circuit, a first operational amplifier, and a first comparator; The first terminal of the first filter circuit is connected to the current sampling circuit, and the second terminal of the first filter circuit is connected to the non-inverting input terminal of the first operational amplifier. The output of the first operational amplifier is connected to the non-inverting input of the first comparator, and the inverting input of the first comparator is connected to the reference voltage. The first operational amplifier is used to convert the current signal in the circuit loop acquired by the current sampling circuit into a voltage signal, and then amplify the voltage signal after filtering by the first filtering circuit. The amplified voltage signal is output to the first comparator. The first comparator is used to determine whether the voltage signal input to the first operational amplifier is greater than the reference voltage. If it is greater, it is determined that an overload has occurred in the circuit loop, and an overload control signal is output to the driving circuit.

3. The overload and short-circuit protection circuit according to claim 2, characterized in that, The short-circuit detection circuit includes a second filter circuit, a second operational amplifier, and a second comparator; The first terminal of the second filter circuit is connected to the current sampling circuit, and the second terminal of the second filter circuit is connected to the non-inverting input terminal of the second operational amplifier. The output of the second operational amplifier is connected to the non-inverting input of the second comparator, and the inverting input of the second comparator is connected to the reference voltage. The second operational amplifier is used to convert the current signal in the circuit loop acquired by the current sampling circuit into a voltage signal, and then amplify the voltage signal after filtering by the second filtering circuit. The amplified voltage signal is output to the second comparator. The second comparator is used to determine whether the voltage signal input to the second operational amplifier is greater than the reference voltage. If it is greater, it is determined that a short circuit has occurred in the circuit loop, and a short circuit control signal is output to the driving circuit.

4. The overload and short-circuit protection circuit according to claim 3, characterized in that, The driving circuit includes a first OR gate; the input A terminal of the first OR gate is connected to the output terminal of a first comparator, and the input B terminal is connected to the output terminal of a second comparator, for outputting a high level after receiving an overload control signal input from the first comparator or a short-circuit control signal input from the second comparator.

5. The overload and short-circuit protection circuit according to claim 4, characterized in that, The driving circuit also includes a thyristor; the control electrode of the thyristor is connected to the output terminal of the first OR gate, the cathode of the thyristor is connected to the negative terminal of the power supply in the circuit loop, and the anode of the thyristor is connected to the protection switch, which is used to turn on after receiving a high level output from the first OR gate, so that the protection switch turns off at a low level.

6. An electronic circuit breaker, characterized in that, The electronic circuit breaker includes a current sampling circuit, a protection switch, and the overload and short circuit protection circuit as described in claim 1. The current sampling circuit is connected to the overload and short circuit protection circuit and is used to collect the current signal in the circuit loop. The protection switch is connected in series with the current sampling circuit and the load in the circuit loop. When an overload or short circuit occurs in the circuit loop, it receives the driving voltage output by the overload and short circuit protection circuit and shuts off the power supply of the circuit loop.

7. The electronic circuit breaker according to claim 6, characterized in that, The electronic circuit breaker also includes an overcurrent protection circuit; the overcurrent protection circuit is used to control the current in the circuit to gradually increase when the circuit is energized.

8. The electronic circuit breaker according to claim 7, characterized in that, The overcurrent protection circuit includes a first resistor, a first transistor, a first capacitor, a second resistor, a third resistor, and a second transistor. The first terminal of the first resistor is connected to the drain of the first transistor, and the first terminal of the first resistor is also connected to the first terminal of the protection switch. The source of the first transistor is connected to the second terminal of the first resistor, and the source of the first transistor is also connected to the first terminal of the first capacitor and the positive terminal of the power supply in the circuit loop. The second terminal of the first capacitor is connected to the gate of the first transistor. The second terminal of the first capacitor is also connected to the first terminal of the second resistor. The first terminal of the second resistor is connected to the first terminal of the third resistor. The second terminal of the third resistor is connected to the positive terminal of the power supply in the circuit loop. The second end of the second resistor is connected to the drain of the second transistor, the gate of the second transistor is connected to the second end of the protection switch, and the source of the second transistor is connected to the negative terminal of the power supply in the circuit loop.

9. The electronic circuit breaker according to claim 6, characterized in that, The electronic circuit breaker also includes a second short-circuit protection circuit; the second short-circuit protection circuit includes a third transistor. The third transistor is connected to the protection switch and the current sampling circuit, and is used to control the protection switch to turn off when the loop current value collected by the current sampling circuit reaches the preset short-circuit current value.

10. The electronic circuit breaker according to claim 6, characterized in that, The electronic circuit breaker also includes a self-test circuit; the self-test circuit is connected to the protection switch and is used to detect whether the status of the protection switch is normal when the circuit is powered on.

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