Intelligent circuit breaker capable of preventing over-current, over-voltage and over-heat faults

Abstract

The invention belongs to the technical field of protective circuit breakers, particularly relates to an intelligent circuit breaker capable of preventing over-current, over-voltage and over-heat faults, and aims to solve the problems that a traditional circuit breaker cannot perform system protection on various fault types and lacks intelligent management in a power supply recovery process after a fault occurs. The system comprises a sampling module, a detection module, a conditioning module and an execution module, the sampling module collects a system current, and generates an overcurrent signal to the conditioning module when the system current exceeds a limit; the detection module monitors voltage and temperature, and sends an overvoltage signal to the conditioning module and an over-temperature signal to the execution switch module respectively when the voltage and the temperature exceed threshold values. A first-stage conditioning unit of the conditioning module converts overcurrent into an adjustable pulse width turn-off signal, a second-stage conditioning unit processes an overvoltage signal and cooperatively regulates and controls the energy storage discharge speed, and an execution switch module cuts off a power supply after receiving a turn-off or over-temperature signal. The intelligent circuit breaker can monitor and respond to three fault conditions of overcurrent, overvoltage and overheating at the same time, and an integrated solution is provided.

Description

Technical Field

[0001] The invention belongs to the technical field of protective circuit breakers, and in particular relates to an intelligent circuit breaker for preventing overcurrent, overvoltage and overheating faults. Background Art

[0002] In modern power systems, the widespread use of electronic equipment and electrical devices has put forward higher requirements for the safety and reliability of power supplies. With the development of science and technology, the complexity of various household appliances, industrial equipment and automation systems has continued to increase. These devices may encounter faults such as overcurrent, overvoltage and overheating during operation. These abnormal conditions may not only cause equipment performance degradation or damage, but also cause serious safety accidents such as fires. Therefore, effective protection mechanisms are needed to ensure the safety of equipment and personnel.

[0003] Traditional circuit breakers usually only provide one type of protection function, such as protection against overcurrent or overvoltage, and most of them are based on mechanical circuit breakers or fuse designs, which have slow response speeds and lack intelligent judgment capabilities. For some precision instruments or high-value equipment, this protection method obviously cannot meet their needs for fast response and precise protection. In addition, traditional circuit breaker protection measures are often unable to handle multiple types of faults at the same time, and lack intelligent management in the process of restoring power after a fault occurs.

[0004] Based on this, the present invention proposes an intelligent circuit breaker that prevents overcurrent, overvoltage and overheating faults. Summary of the invention

[0005] In order to solve the above problems in the prior art, that is, traditional protection measures are often unable to handle multiple fault types at the same time, and lack intelligent management in the process of restoring power supply after a fault occurs, the present invention proposes an intelligent circuit breaker for preventing overcurrent, overvoltage and overheating faults, and the intelligent circuit breaker includes a sampling module, a detection module, a conditioning module and an execution switch module; The sampling module is connected to the power input to collect the real-time current of the protected system. If the real-time current exceeds the set current threshold, the corresponding real-time current is defined as an overcurrent signal and sent to the conditioning module; The detection module detects the real-time voltage and real-time temperature of the protected system. If the real-time voltage exceeds a set voltage threshold, the corresponding real-time voltage is defined as an overvoltage signal and sent to the conditioning module. If the real-time temperature exceeds a set temperature threshold, the corresponding real-time temperature is defined as an overtemperature signal and sent to the execution switch module. The conditioning module includes a primary conditioning unit and a secondary conditioning unit: the primary conditioning unit converts the overcurrent signal into a high-level protection signal, and adjusts the pulse width of the high-level protection signal, generates a shutdown signal and sends it to the execution switch module; the secondary conditioning unit receives the overvoltage signal, and adjusts the pulse width of the overvoltage signal, and controls the discharge speed of the energy storage subunit of the secondary conditioning unit according to the pulse width of the high-level protection signal and the pulse width of the overvoltage signal; The execution switch module, after receiving the shutdown signal or the over-temperature signal, executes the switch disconnection operation of the intelligent circuit breaker to cut off the power input of the protected system.

[0006] Furthermore, the sampling module is connected to a current signal amplification and comparison module, and the current signal amplification and comparison module is used to perform signal amplification processing on the real-time current, and compare the amplified current with the set current threshold to determine whether an overcurrent signal needs to be triggered.

[0007] Furthermore, the setting current threshold is obtained by: The current signal amplification and comparison module is connected to a current protection threshold signal adjustment module, and the current protection threshold signal adjustment module is used to output the set current threshold.

[0008] Furthermore, if the real-time temperature exceeds the set temperature threshold, the power input is cut off by the temperature monitoring module connected to the execution switch module, and the specific method is as follows: The maximum dissipated power is calculated based on the real-time temperature. When the maximum dissipated power is greater than the heating power of the execution switch module, the power input is cut off through the temperature monitoring module connected to the execution switch module.

[0009] Further, the current protection threshold signal adjustment module includes a resistor R30, a resistor R29 and a capacitor C16; One end of the resistor R30 is connected to the voltage network stabilized by the voltage stabilization module, the other end of the resistor R30 is connected to the resistor R29, and the other end of the resistor R29 is connected to the current signal amplification and comparison module; The two ends of the capacitor C16 are connected to the two ends of the resistor R29; According to the required threshold signal, the ratio of the resistance value of the resistor R30 and the resistor R29 is adjusted so that the threshold signal is output after the current passes through the resistor R30 and the resistor R29.

[0010] Further, the first-stage conditioning unit includes a capacitor C9, a resistor R20 and a diode D4; Both ends of the capacitor C9 are connected to the output of the current signal amplification and comparison module, one end of the capacitor C9 is connected to one end of the resistor R20, the other end of the resistor R20 is connected to the negative terminal of the diode D4, the first positive terminal of the diode D4 is connected between one end of the capacitor C9 and one end of the resistor R20, and the second positive terminal of the diode D4 is grounded.

[0011] Furthermore, the first-level conditioning unit converts the overcurrent signal into a high-level protection signal and adjusts the pulse width of the high-level protection signal. The pulse width t w , which is calculated as: t w =R X C X ; Among them, R X is the resistance value of resistor R20, C X is the capacity of capacitor C9.

[0012] Further, the secondary conditioning unit includes a diode D3, a resistor R18 and a capacitor C8; The positive terminal of the diode D3 is connected to the output of the current signal amplification and comparison module, the negative terminal of the diode D3 is connected to one end of the resistor R18 and the first node P1, the first node P1 is respectively connected to one end of the capacitor C8 and the gate of the load switch in the execution switch module, the other end of the resistor R18 is connected to the other end of the capacitor C8, and the other end of the capacitor C8 is connected to the power ground of the first set threshold.

[0013] Furthermore, the detection module includes an overvoltage protection detection module, and the overvoltage protection detection module is used to detect the real-time voltage of the protected system; The overvoltage protection detection module includes a transistor Q2, a voltage regulator Z2, a resistor R16 and a resistor R17; The first pin of the transistor Q2 is connected to the negative terminal of the diode D3, the second pin of the transistor Q2 is connected to the power ground of the second set threshold, the third pin of the transistor Q2 is connected to one end of the resistor R16, and the other end of the resistor R16 is connected to the power ground of the second set threshold; One end of the voltage regulator tube Z2 is connected between the third pin of the transistor Q2 and one end of the resistor R16, the other end of the voltage regulator tube Z2 is connected to one end of the resistor R17, and the other end of the resistor R17 is grounded.

[0014] Furthermore, the charging time t of the capacitor C8 is c , which is calculated as: t c =RC×ln[(V 1 -V0 ) / (V 1 -V t )]; Among them, R is the internal resistance of diode D3 after it is turned on, C is the capacity of capacitor C8, V 1 is the voltage value that capacitor C8 can finally be dropped to, V 0 is the initial voltage value of capacitor C8, V t It is the voltage value when the load switch enters the on state.

[0015] Beneficial effects of the present invention: Synchronous monitoring and protection of multiple fault types: The integrated sampling module and detection module respectively collect current, voltage and temperature parameters in real time, and can simultaneously monitor three types of faults: overcurrent, overvoltage and overheating, avoiding the limitations of a single protection function and significantly improving system safety.

[0016] Fast response and precise triggering: The overcurrent signal directly generates a high-level shutdown signal through the first-level conditioning unit, triggering the execution switch module to quickly disconnect the circuit.

[0017] The overvoltage signal and the overcurrent signal are coordinated through the pulse width modulation (PWM) of the secondary conditioning unit to control the discharge speed of the energy storage subunit, thereby dynamically adjusting the protection threshold and taking into account both sensitivity and stability.

[0018] Intelligent power restoration management: After the fault is eliminated, the system can automatically restore power supply through preset logic (such as delayed reclosing or manual intervention mode), reducing power outage time. It is suitable for scenarios with high continuity requirements such as industrial automation.

[0019] Adaptive protection parameter adjustment: The discharge speed of the energy storage subunit is dynamically adjusted according to the real-time fault signal to support different load types and protection requirements, extend the equipment life and reduce the misjudgment rate.

[0020] Modular design and high reliability: Each functional module operates independently and does not interfere with each other. The signal is processed in stages through the conditioning module to reduce the impact of electromagnetic interference on detection accuracy and ensure long-term stable operation of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings: Figure 1 It is a schematic diagram of the connection relationship between various modules in an intelligent circuit breaker for preventing overcurrent, overvoltage and overheating faults of the present invention; Figure 2 It is a schematic diagram of the overall structure of an intelligent circuit breaker for preventing overcurrent, overvoltage and overheating faults of the present invention; Figure 3It is a structural schematic diagram of a current voltage stabilizing module of an intelligent circuit breaker for preventing overcurrent, overvoltage and overheating faults of the present invention; Figure 4 It is a structural schematic diagram of a current real-time signal sampling module and an execution switch module in an intelligent circuit breaker for preventing overcurrent, overvoltage and overheating faults of the present invention; Figure 5 It is a structural schematic diagram of a current protection threshold signal adjustment module and a current signal amplification comparison module in an intelligent circuit breaker for preventing overcurrent, overvoltage and overheating faults of the present invention; Figure 6 It is a structural schematic diagram of a primary conditioning unit in an intelligent circuit breaker for preventing overcurrent, overvoltage and overheating faults of the present invention; Figure 7 It is a schematic diagram of an overvoltage protection detection module and a secondary conditioning unit in an intelligent circuit breaker for preventing overcurrent, overvoltage and overheating faults according to the present invention.

[0022] Figure 8 It is a schematic diagram of the connection relationship between the primary conditioning unit and the secondary conditioning unit in an intelligent circuit breaker for preventing overcurrent, overvoltage and overheating faults of the present invention. DETAILED DESCRIPTION

[0023] The present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It is also necessary to explain that, for ease of description, only the parts related to the relevant invention are shown in the accompanying drawings.

[0024] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0025] like Figure 1-8 For details, see Figure 1 , the present invention provides an intelligent circuit breaker for preventing overcurrent, overvoltage and overheating faults, the intelligent circuit breaker comprises a sampling module, a detection module, a conditioning module and an execution switch module; The sampling module is connected to the power input to collect the real-time current of the protected system. If the real-time current exceeds the set current threshold, the corresponding real-time current is defined as an overcurrent signal and sent to the conditioning module; The detection module detects the real-time voltage and real-time temperature of the protected system. If the real-time voltage exceeds a set voltage threshold, the corresponding real-time voltage is defined as an overvoltage signal and sent to the conditioning module. If the real-time temperature exceeds a set temperature threshold, the corresponding real-time temperature is defined as an overtemperature signal and sent to the execution switch module. The conditioning module includes a primary conditioning unit and a secondary conditioning unit: the primary conditioning unit converts the overcurrent signal into a high-level protection signal, and adjusts the pulse width of the high-level protection signal, generates a shutdown signal and sends it to the execution switch module; the secondary conditioning unit receives the overvoltage signal, and adjusts the pulse width of the overvoltage signal, and controls the discharge speed of the energy storage subunit of the secondary conditioning unit according to the pulse width of the high-level protection signal and the pulse width of the overvoltage signal; The execution switch module, after receiving the shutdown signal or the over-temperature signal, executes the switch disconnection operation of the intelligent circuit breaker to cut off the power input of the protected system.

[0026] like Figure 2 As shown, the sampling module in the present invention uses the voltage difference signal between the two ends generated by the current flowing through the resistor to amplify and compare. If the set current threshold is exceeded, the level value of the output signal is changed (from high to low, or from low to high), the load switch is turned off, and the fault current is cut off. Specifically: The sampling module in the present invention is two parallel sampling resistors, which are connected in series to the input port of the circuit after being connected in parallel. The sampling resistors in this embodiment are resistors R31 and R32; The sampling resistors in the design are selected to have high power (to ensure that normal load current passes through without heating), high precision (to make the sampled current more accurate and the action threshold more accurate), and low temperature drift (to minimize the influence of temperature on the current sampling of the circuit in various temperature ranges); Resistance value: According to the overcurrent design target of 1.35A maximum operating current value and the maximum voltage drop of 0.12V caused by the sampling resistor on the output voltage, the resistance value is calculated and selected, that is: Sampling resistor size: R=U / I Substitute the current and voltage parameters to calculate: R=0.12 / 1.35 The calculated sampling resistance cannot exceed 0.8889 ohms. Considering the parameters that affect the accuracy of the current signal, such as the accuracy of the current amplifier circuit of the entire system and the input actual adjustment voltage (Vos) of the signal comparator, the sampling resistor value is finally 0.075 ohms, and the accuracy is not less than 1%, which can achieve a voltage difference of input and output loss within 0.1%. When the design selects a 0.075 ohm resistor, the sampling signal of the protection action current is: Vsample = 1.35 × 0.075 = 0.1013 (V) Resistance power: After determining the resistance value to be 0.75 ohms, when the maximum rated working current is 1.35 A, the power consumed by the resistor is: W = I²×R. Calculation: W = 1.35×1.35×0.075 = 0.137 W.

[0027] That is, the resistance power cannot be less than 0.137 W. Considering factors such as the working environment temperature and thermal resistance, two 0.15-ohm resistors with a power of 1 W are used in parallel in the design and selection of the sampling resistor to obtain a resistance value of 0.075 ohms. The main advantage of this design is that the power of the sampling resistor is increased through parallel connection, heat dissipation is improved, the accuracy drift caused by temperature rise is reduced, and the circuit stability is improved.

[0028] Resistance accuracy: The design uses a sampling resistor with an accuracy not lower than 1%, ensuring the sampling accuracy of the current signal.

[0029] Resistance temperature drift: An alloy sampling resistor with a low temperature drift of 50 ppm / °C is used in the design. The maximum change in the resistance value within the working temperature range does not exceed 0.3%; In this embodiment, the sampling module is connected to the current signal amplification and comparison module. The current signal amplification and comparison module is used to perform signal amplification processing on the real-time current, and after amplification, it is compared with the set current threshold to determine whether an overcurrent signal needs to be triggered.

[0030] The method for obtaining the set current threshold is as follows: The current signal amplification and comparison module is connected to the current protection threshold signal adjustment module, and the current protection threshold signal adjustment module is used to output the set current threshold.

[0031] Specifically, as Figure 5 shown, the current protection threshold signal adjustment module includes resistor R30, resistor R29, and capacitor C16; One end of resistor R30 is connected to the voltage network after voltage stabilization by the voltage stabilization module. The other end of resistor R30 is connected to resistor R29, and the other end of resistor R29 is connected to the current signal amplification and comparison module; Both ends of capacitor C16 are connected to both ends of resistor R29; According to the required threshold signal, adjust the ratio of the resistance values of resistor R30 and resistor R29 so that after the current passes through resistor R30 and resistor R29, a threshold signal is output.

[0032] The present invention utilizes the principle of resistor voltage division. The voltage signal REF2 on R29 in the series circuit of R29 and R30 grounded is used as the comparison threshold for the current overcurrent signal, so that the magnitude of the fault current protection value can be adjusted: The overcurrent signal size calculated above is 2.03V. It can be known that by adjusting the resistance value in the proportional integral circuit composed of R29 and R30 (capacitor C16 increases the delay, stabilizes the output signal, and reduces the disturbance caused by input fluctuations), the required comparator reference voltage input signal value can be obtained on the REF2 signal network. The calculation formula is as follows: Vvref2=((Vin-Vgnd) / (R29+R30))×R29; Where, Vin=12(V), Vgnd=7(V); Vvref2 cannot be greater than the overcurrent signal value of 2.03V; When R30 is selected as a 1% resistor of 20k, R29=13.7k is calculated by the above formula.

[0033] That is, during overcurrent protection, the comparator can only operate reliably when the reference voltage is less than 2.03V, and the maximum value of the voltage-dividing sampling resistor R29 cannot exceed 13.7K.

[0034] The current protection threshold signal adjustment module further includes a capacitor C17, and both ends of the capacitor C17 are arranged between IN2+ and IN2-, specifically, connected between the IN+ pin and the IN- pin of U2.

[0035] In this embodiment, Figure 3 As shown, the voltage stabilizing module includes a voltage stabilizer U6, a capacitor C18, a voltage regulator tube Z9 and a voltage regulator tube Z10; The first terminal of the voltage stabilizer U6 is grounded, the second terminal of the voltage stabilizer U6 is connected to the 12V input voltage, and the third terminal of the voltage stabilizer U6 is provided with a fourth node P4 and a fifth node P5; The fourth node P4 is connected to one end of the capacitor C18 and the fifth node P5, the fifth node P5 is connected to one end of the Zener diode Z9 and one end of the Zener diode Z10, the other end of the Zener diode Z9 is connected to the other end of the Zener diode Z10, and then connected to the other end of the capacitor C18, and the other end of the capacitor C18 is connected to the 12V input voltage.

[0036] The capacitor C18, the voltage regulator tube Z9 and the voltage regulator tube Z10 are connected in parallel with each other and then connected in series to the third terminal of the voltage regulator U6.

[0037] like Figure 7 and Figure 8 As shown, in this embodiment, the secondary conditioning unit is also connected to the overvoltage protection detection module. When the overvoltage protection detection module detects an overvoltage signal, the discharge speed of the energy storage subunit is controlled by adjusting the pulse width of the overvoltage signal.

[0038] The overvoltage protection detection module includes a transistor Q2, a voltage regulator Z2, a resistor R16 and a resistor R17; The first pin of the transistor Q2 is connected to the negative terminal of the diode D3, the second pin of the transistor Q2 is connected to the power ground of the second set threshold, the third pin of the transistor Q2 is connected to one end of the resistor R16, and the other end of the resistor R16 is connected to the power ground of the second set threshold; One end of the voltage regulator tube Z2 is connected between the third pin of the transistor Q2 and one end of the resistor R16, the other end of the voltage regulator tube Z2 is connected to one end of the resistor R17, and the other end of the resistor R17 is grounded.

[0039] Wherein, the second set threshold is 12V.

[0040] Among them, the overvoltage protection detection module in the present invention can cut off the output when the input voltage exceeds the allowed or set threshold value. In the present invention, the overvoltage protection detection module does not adopt a solution of direct comparison of voltage signals, but adopts a simpler and lower-cost solution. It uses the principle and characteristics of avalanche voltage regulation of the voltage regulator diode to monitor the power supply voltage through the Z2 voltage regulator tube with a voltage regulation value of 12V. When the power supply voltage is greater than the Z2 voltage regulation value, Z2 clamps the voltage on its cathode to stabilize at about 12V (R16 and R17 are current limiting resistors to ensure that the working current of Z2 is within the rated range). Using the switching characteristics of the PNP transistor Q2, the transistor is turned on when its emitter voltage (power supply voltage) is greater than the base voltage (Z2 voltage regulation), that is, high and low level signals are output from the collector (equivalent to turning on the power supply voltage to the collector).

[0041] like Figure 5 and Figure 6 As shown, in this embodiment, the current signal amplification and comparison module uses a device U2 with a built-in operational amplifier and voltage comparator to complete the amplification and comparison functions of the load current signal (actually the voltage difference signal across the resistor is collected), and completes the signal comparison in about 400ns, outputs a control signal U5_2B, and is triggered by a trigger U5: This module uses the INA381A1 high-speed current sensing amplifier with an amplification factor of 20 times, so the signal during overcurrent protection is: Vcompare = 0.101 × 20 = 2.02 (V); Highlights: The signal amplification is relatively fast, but there are interference signals during the operation of the circuit. The RC filter circuit composed of R14 and C19 can filter out the high-frequency interference glitches to ensure that there will be no malfunction.

[0042] Among them, Figure 5As shown, the ALERT pin of the device U2 of the voltage comparator is connected to the sixth node P6, the sixth node P6 is connected to one end of the resistor R2 and one end of the resistor R14, the other end of the resistor R2 is connected to the 12V input voltage, the other end of the resistor R14 is connected to one end of the capacitor C19 and U5, and the other end of the capacitor C19 is connected to the voltage stabilizing module.

[0043] In this embodiment, the execution switch module includes a voltage regulator tube Z4, a load switch Q4 and a feedback resistor FB2; One end of the voltage regulator Z4 is connected to the gate of the load switch Q4, and the other end of the voltage regulator Z4 is connected to the second node P2, and the second node P2 is connected to the resistor R31 and the resistor R32 respectively; The drain of the load switch Q4 is connected to one end of the feedback resistor FB2 and the output voltage of 12V, the source of the load switch Q4 is connected to the third node P3, and the third node P3 is connected to the other end of the feedback resistor FB2 and the second node P2.

[0044] like Figure 6-Figure 8 As shown, in this embodiment, the first-stage conditioning unit includes a capacitor C9, a resistor R20 and a diode D4; Both ends of the capacitor C9 are connected to the output of the current signal amplification and comparison module, one end of the capacitor C9 is connected to one end of the resistor R20, the other end of the resistor R20 is connected to the negative terminal of the diode D4, the first positive terminal of the diode D4 is connected between one end of the capacitor C9 and one end of the resistor R20, and the second positive terminal of the diode D4 is grounded.

[0045] The secondary conditioning unit includes a diode D3, a resistor R18 and a capacitor C8; The positive terminal of the diode D3 is connected to the output of the current signal amplification and comparison module, the negative terminal of the diode D3 is connected to one end of the resistor R18 and the first node P1, the first node P1 is respectively connected to one end of the capacitor C8 and the gate of the load switch, the other end of the resistor R18 is connected to the other end of the capacitor C8, and the other end of the capacitor C8 is connected to the power supply ground of the first set threshold.

[0046] The diode D3 and the diode D4 are formed by connecting the cathodes of the two diodes in parallel.

[0047] Among them, the first set threshold is 7V. This 7V is a "power ground" after the input power supply is stepped down and stabilized, but it is not 0V. 7V is used as the ground. Compared with the input 12V, it is equivalent to stepping down and stabilizing it to 5V, realizing the change of the input power supply voltage, but the threshold voltage of the threshold circuit (using the principle of resistor voltage division) does not change.

[0048] Specifically, the primary conditioning unit and the secondary conditioning unit in the present invention constitute a hiccup protection circuit. When an overcurrent or overvoltage fault occurs, the corresponding monitoring circuit will output a high-level protection signal to control the gate (G) of the field effect switch tube to turn off the output.

[0049] For current protection, as described above, the current sampling resistor continuously monitors the current, and when the fault current occurs, the signal level signal is changed from high to low through the signal amplification comparator U2, thereby generating a high-level pulse signal in the trigger device U5 (trigger), which enters the charge and discharge circuit composed of C8 and R18 after passing through the diode D3, fully charging C8, and this high-level pulse will give the gate of the load switch Q4 a signal to shut down the output, ultimately achieving the design goal of protection.

[0050] As for voltage protection, as mentioned above, when overvoltage occurs, transistor Q2 is turned on. The protection signal also enters the charge and discharge circuit composed of C8 and R18, making Q4_G high level, and then the load switch Q4 is turned off until the voltage returns to normal. And because of the reverse cutoff of diode D3, this signal will not enter the current protection signal circuit, which improves the circuit reliability and stability. The duration of hiccup protection is adjusted by the charging and discharging time of the capacitor. For overcurrent protection, there are two levels of adjustment. The first level is to control the width of the protection pulse by controlling the charging time of capacitor C9 by R20 through trigger U5 after the trigger signal arrives. It not only charges C8, but also directly affects the duration of the protection signal Q4_G, making the protection last longer.

[0051] The secondary conditioning unit is a charge and discharge circuit composed of C8 and R18. The energy storage size can be adjusted by adjusting the size of capacitor C8. The larger the capacitor, the more energy storage and the longer the discharge time. The discharge speed (time) can be adjusted by adjusting the size of R18. The smaller the resistance, the faster the discharge. Based on the previous design ideas, the high-level pulse signal output by U5 charges a larger capacitor. A larger discharge resistance can increase the load switch cut-off duration, and vice versa. The advantage of this adjustment is that it allows the protected equipment to have sufficient time to dissipate heat and will not expand the fault.

[0052] Because U5 will only be triggered when the trigger signal jumps (from high to low, or from low to high), in the event of a fault, the load switch will not be closed again from the off state until the protection signal level energy generated by the protection is released.

[0053] Therefore, if the fault disappears at this moment, the closed loop of the switch will not cause the signal of the signal amplifier comparator U2 to jump (because the signal of the sampling resistor is within the normal range), thereby realizing the automatic recovery function after protection.

[0054] If the fault persists, then after the switch is closed, the fault still exists and the current signal collected by the sampling resistor is still abnormal. In this case, the output signal of the signal amplifier comparator U2 jumps again, and the trigger U5 is triggered again and outputs a current fault protection pulse signal. The load switch is closed again for a period of time (the duration is determined by the circuit parameters of the two-level protection signal setting), and finally repeated hiccup protection is achieved.

[0055] Under normal working conditions, the load current is less than the designed 1.35A. At this time, among the two input signals of the comparator (real-time sampling signal and reference voltage signal), the comparator reference voltage signal (comparison threshold) is higher than the current real-time sampling signal, and the comparator outputs a high-level protection signal.

[0056] When a short circuit fault occurs in the protected system, the real-time sampling signal is higher than the comparator reference voltage signal, and the comparator jumps from a high-level protection signal to a low-level signal, generating a falling edge trigger signal.

[0057] The falling edge signal generated by the comparator due to overcurrent triggers the Schmitt trigger U5 (U5 is configured as falling edge trigger). The signal output by U5 is triggered to charge C9 through R20. The charging time is the high-level pulse width that needs to be controlled. The first level of control of the duration of the protection signal is achieved through the high-level width (duration). The calculation is as follows: t w =R X C X ; where t w The width of the first level protection pulse determines the amount of energy stored in the second level protection pulse. Rx and Cx are R20 (100k) and C9 (10uF) in this circuit respectively; Calculation shows that the first level pulse width is approximately 1000ms.

[0058] The first-level high-level protection pulse adjusted by the trigger charges C8 after passing through the reverse diode D3. The charging time constant of C8 (i.e., the time required for the terminal voltage of capacitor C8 to reach the level value required by the output control circuit to turn off Q4) can be calculated according to the following formula: t c =RC×ln[(V 1 -V 0 ) / (V 1 -V t )]; Where R is the internal resistance of diode D3 after it is turned on, which is usually tens to hundreds of ohms. Here, we take 100Ω. V 1 is the voltage value that capacitor C8 can finally be dropped to, V 0is the initial voltage value of capacitor C8, V t It is the voltage value when the load switch enters the on state.

[0059] C is the capacity of capacitor C8, which is 4.7uF in this embodiment; V1=4.7V; (the voltage value that the capacitor can reach when charged, which is also the signal level of the trigger output) V0=0V; (initial voltage value of capacitor C8) Vt=2.5V; (You can check the chip data to know the voltage value of field effect tube Q4 when it is turned off) Calculation can be obtained: t c =356us (this time is also the main component of the overcurrent protection response time, other influencing factors can be ignored) Discharge time constant: (i.e. the time required for capacitor C8 to discharge through R18 until the voltage is lower than the level required for field effect transistor Q4 to close, that is, to discharge to the 1.6V voltage value for Q4 to open) It can be calculated as follows: tc=RC×Ln[(V1-V0) / (V1-Vt)]; Where: R is the 51k resistor R18; C is 4.7uF; V1=0V; (the voltage value that the capacitor can finally be placed at) V0=4.7V; (initial voltage value of capacitor C8) Vt=1.6V; (From the data, we can know the voltage value when the field effect tube Q4 enters the on state) Calculation shows: tc = 258ms (this time is also the duration of the FET output being turned off during overcurrent / overvoltage protection.) The VCC pin of U5 is connected to one end of the capacitor C10 and the 12V current input, and the other end of the capacitor C10 is connected to the voltage stabilizing module.

[0060] In this embodiment, a temperature sensor is installed on the surface of the execution switch module. The temperature sensor is used to obtain the real-time temperature and calculate the maximum dissipation power based on the real-time temperature. When the maximum dissipation power is greater than the heating power of the execution switch module, the power input is cut off through the temperature monitoring module connected to the execution switch module.

[0061] Specifically: Constructing the maximum junction temperature function P DMAX , the maximum junction temperature function is the maximum allowable power dissipation of the semiconductor device at any ambient temperature: P DMAX =(T JMAX −T A ) / θJA .

[0062] Where: T JMAX =125°C to 150°C.

[0063] Junction-to-ambient thermal resistanceθ JA It is directly related to the device packaging. Devices with different packages have different junction-to-ambient thermal resistances at the same power. This circuit design uses reasonable thermal design to reduce the junction-to-ambient thermal resistance. Ambient temperature (T A ) is the device’s operating ambient temperature.

[0064] If this maximum dissipation power is exceeded, the junction temperature of the device will exceed the maximum allowable range, and the device will not work properly or may even be damaged.

[0065] The power load switch device in this design is AOD4185, packaged in TO252 (DPARK package). Check its working parameters: T JMAX =150°C; T A =25°C; θ JA =50°C / W (maximum 50); Substitute into the above formula P DMAX =(150-25) / 50=2.5(W); It can be obtained that when the device operates at the highest junction temperature, the maximum power dissipation of the device is 2.5W when the ambient temperature is 25°C.

[0066] When the protection circuit is at the maximum operating current, the heating power of the power load switch is: w=I 2 ×R; Where I = 1.35A; R = 0.02Ω; Calculation shows that: W=0.036 (W), indicating that under normal working conditions, the heat generation power is much smaller than the maximum dissipation power. Taking into account the fault conditions and ambient temperature factors, an NTC temperature sensor is placed on the surface of the load switch in the actual design, and the temperature value is converted into a voltage signal for comparison. When the set operating temperature is exceeded, the output is cut off to achieve overheating protection.

[0067] In the description of the present invention, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0068] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0069] The term "comprise" or any other similar term is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus / device that includes a list of elements includes not only those elements but also other elements not expressly listed, or also includes elements inherent to such process, method, article, or apparatus / device.

[0070] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. An intelligent circuit breaker for preventing overcurrent, overvoltage and overheating faults, characterized in that: The intelligent circuit breaker includes a sampling module, a detection module, a conditioning module and an execution switch module; The sampling module is connected to the power input to collect the real-time current of the protected system. If the real-time current exceeds the set current threshold, the corresponding real-time current is defined as an overcurrent signal and sent to the conditioning module; The detection module detects the real-time voltage and real-time temperature of the protected system. If the real-time voltage exceeds a set voltage threshold, the corresponding real-time voltage is defined as an overvoltage signal and sent to the conditioning module. If the real-time temperature exceeds a set temperature threshold, the corresponding real-time temperature is defined as an overtemperature signal and sent to the execution switch module. The conditioning module includes a primary conditioning unit and a secondary conditioning unit: the primary conditioning unit converts the overcurrent signal into a high-level protection signal, and adjusts the pulse width of the high-level protection signal, generates a shutdown signal and sends it to the execution switch module; the secondary conditioning unit receives the overvoltage signal, and adjusts the pulse width of the overvoltage signal, and controls the discharge speed of the energy storage subunit of the secondary conditioning unit according to the pulse width of the high-level protection signal and the pulse width of the overvoltage signal; The execution switch module, after receiving the shutdown signal or the over-temperature signal, executes the switch disconnection operation of the intelligent circuit breaker to cut off the power input of the protected system.

2. The intelligent circuit breaker for preventing overcurrent, overvoltage and overheating faults according to claim 1, characterized in that: The sampling module is connected to the current signal amplification and comparison module, and the current signal amplification and comparison module is used to perform signal amplification processing on the real-time current, compare the amplified current with the set current threshold, and determine whether an overcurrent signal needs to be triggered.

3. The intelligent circuit breaker for preventing overcurrent, overvoltage and overheating faults according to claim 2, characterized in that: The setting current threshold value is obtained by: The current signal amplification and comparison module is connected to a current protection threshold signal adjustment module, and the current protection threshold signal adjustment module is used to output the set current threshold.

4. The intelligent circuit breaker for preventing overcurrent, overvoltage and overheating faults according to claim 1, characterized in that: If the real-time temperature exceeds the set temperature threshold, the power input is cut off through the temperature monitoring module connected to the execution switch module, and the specific method is as follows: The maximum dissipated power is calculated based on the real-time temperature. When the maximum dissipated power is greater than the heating power of the execution switch module, the power input is cut off through the temperature monitoring module connected to the execution switch module.

5. The intelligent circuit breaker for preventing overcurrent, overvoltage and overheating faults according to claim 3, characterized in that: The current protection threshold signal adjustment module includes a resistor R30, a resistor R29 and a capacitor C16; One end of the resistor R30 is connected to the voltage network stabilized by the voltage stabilization module, the other end of the resistor R30 is connected to the resistor R29, and the other end of the resistor R29 is connected to the current signal amplification and comparison module; The two ends of the capacitor C16 are connected to the two ends of the resistor R29; According to the required threshold signal, the ratio of the resistance value of the resistor R30 and the resistor R29 is adjusted so that the threshold signal is output after the current passes through the resistor R30 and the resistor R29.

6. The intelligent circuit breaker for preventing overcurrent, overvoltage and overheating faults according to claim 1, characterized in that: The first-stage conditioning unit includes a capacitor C9, a resistor R20 and a diode D4; Both ends of the capacitor C9 are connected to the output of the current signal amplification and comparison module, one end of the capacitor C9 is connected to one end of the resistor R20, the other end of the resistor R20 is connected to the negative terminal of the diode D4, the first positive terminal of the diode D4 is connected between one end of the capacitor C9 and one end of the resistor R20, and the second positive terminal of the diode D4 is grounded.

7. The intelligent circuit breaker for preventing overcurrent, overvoltage and overheating faults according to claim 6, characterized in that: The first-level conditioning unit converts the overcurrent signal into a high-level protection signal and adjusts the pulse width of the high-level protection signal. w , which is calculated as: t w =R X C X ; Among them, R X is the resistance value of resistor R20, C X is the capacity of capacitor C9.

8. The intelligent circuit breaker for preventing overcurrent, overvoltage and overheating faults according to claim 2, characterized in that: The secondary conditioning unit includes a diode D3, a resistor R18 and a capacitor C8; The positive terminal of the diode D3 is connected to the output of the current signal amplification and comparison module, the negative terminal of the diode D3 is connected to one end of the resistor R18 and the first node P1, the first node P1 is respectively connected to one end of the capacitor C8 and the gate of the load switch in the execution switch module, the other end of the resistor R18 is connected to the other end of the capacitor C8, and the other end of the capacitor C8 is connected to the power ground of the first set threshold.

9. The intelligent circuit breaker for preventing overcurrent, overvoltage and overheating faults according to claim 8, characterized in that: The detection module includes an overvoltage protection detection module, which is used to detect the real-time voltage of the protected system; The overvoltage protection detection module includes a transistor Q2, a voltage regulator Z2, a resistor R16 and a resistor R17; The first pin of the transistor Q2 is connected to the negative terminal of the diode D3, the second pin of the transistor Q2 is connected to the power ground of the second set threshold, the third pin of the transistor Q2 is connected to one end of the resistor R16, and the other end of the resistor R16 is connected to the power ground of the second set threshold; One end of the voltage regulator tube Z2 is connected between the third pin of the transistor Q2 and one end of the resistor R16, the other end of the voltage regulator tube Z2 is connected to one end of the resistor R17, and the other end of the resistor R17 is grounded.

10. The intelligent circuit breaker for preventing overcurrent, overvoltage and overheating faults according to claim 8, characterized in that: The charging time of the capacitor C8 is t c , which is calculated as: t c =RC×ln[(V1-V0) / (V1-V t )]; Among them, R is the internal resistance of diode D3 after it is turned on, C is the capacity of capacitor C8, V1 is the voltage value that capacitor C8 can finally be put on, V0 is the initial voltage value of capacitor C8, V t It is the voltage value when the load switch enters the on state.

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