Positive and negative current overcurrent protection self-locking circuit

Abstract

The positive and negative current overcurrent protection self-locking circuit comprises a power supply circuit, a positive and negative current detection circuit, a positive current comparison circuit, a negative current comparison circuit, a level self-locking circuit, an overcurrent reset circuit and a control output circuit, one end of the positive current comparison circuit and one end of the negative current comparison circuit are respectively connected with the positive and negative current detection circuit, the other end of the positive current comparison circuit and the other end of the negative current comparison circuit are respectively connected with the level self-locking circuit and the overcurrent reset circuit, and the overcurrent reset circuit is further connected with the level self-locking circuit. The level self-locking circuit is connected with the control output circuit; the power supply circuit is connected with the positive and negative current detection circuit, the positive current comparison circuit, the negative current comparison circuit, the level self-locking circuit, the overcurrent reset circuit and the control output circuit. By adopting the over-current protection circuit, accurate and reliable over-current protection can be provided for a direct-current circuit.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of circuit, in particular to a positive and negative current overcurrent protection self-locking circuit. BACKGROUND

[0002] In today's era of rapid development of power electronics technology, the application of high-power DC circuit is increasingly widespread, covering many key fields such as new energy power generation, electric vehicle charging, data center power supply, etc. These high-power DC systems play a crucial role in ensuring efficient conversion and utilization of energy, and promoting the intelligent and green development of various industries.

[0003] In the operation process of high-power DC circuit, overcurrent protection is the core link to ensure the safe and stable operation of the system. If overcurrent occurs in the circuit and cannot be protected in time and effectively, it will cause equipment overheating, insulation damage, and even serious accidents such as fire, thereby causing huge economic losses and safety hazards.

[0004] At present, DC air circuit breaker is a commonly used device in high-power overcurrent protection. It occupies a certain market share in the field of DC circuit protection due to its simple structure, low cost, and certain breaking capacity. However, with the increasing requirements of high-power DC systems for safety and reliability, the limitations of DC air circuit breaker in protection performance have gradually become apparent. Its reaction speed is relatively slow, and it cannot quickly cut off the circuit when facing sudden overcurrent faults, resulting in the continuous action of fault current in a short time, which aggravates the risk of equipment damage, and may cause misprotection or insufficient protection in actual application, which cannot provide precise and reliable overcurrent protection for DC circuits. SUMMARY

[0005] In order to solve the above problems, the purpose of the present application is to provide a positive and negative current overcurrent protection self-locking circuit, which can provide precise and reliable overcurrent protection for DC circuits.

[0006] Based on this, the present application provides a positive and negative current overcurrent protection self-locking circuit, which comprises: a power supply circuit, a positive and negative current detection circuit, a positive current comparison circuit, a negative current comparison circuit, a level self-locking circuit, an overcurrent reset circuit, and a control output circuit; One end of the positive current comparison circuit and the negative current comparison circuit is connected to the positive and negative current detection circuit respectively, and the other end is connected to the level self-locking circuit and the overcurrent reset circuit respectively, the overcurrent reset circuit is also connected to the level self-locking circuit, and the level self-locking circuit is connected to the control output circuit; The power supply circuit is connected with the positive and negative current detection circuit, the positive current comparison circuit, the negative current comparison circuit, the level self-locking circuit, the overcurrent reset circuit and the control output circuit respectively.

[0007] The power supply circuit comprises a direct current power input port, a first output end of the direct current power input port is grounded, a second output end of the direct current power input port is connected with one end of a twelfth capacitor and an input end of a voltage stabilizing chip respectively, the other end of the twelfth capacitor and the ground end of the voltage stabilizing chip are grounded, an output end of the voltage stabilizing chip is connected with one end of a tenth capacitor and one end of an eleventh capacitor respectively, the other end of the tenth capacitor and the other end of the eleventh capacitor are grounded, the second output end of the direct current power input port serves as a first voltage output end, and the output end of the voltage stabilizing chip serves as a second voltage output end.

[0008] The positive and negative current detection circuit comprises a current sensor chip, a first input end and a second input end of the current sensor chip are connected with external circuits, a first output end of the current sensor chip is connected with the second voltage output end of the power supply circuit, one end of a first capacitor and one end of a second capacitor respectively, the other end of the first capacitor, the other end of the second capacitor and a second output end of the current sensor chip are grounded, a third output end of the current sensor chip is connected with one end of a sixth resistor, the other end of the sixth resistor is connected with one end of a third capacitor and one end of a fifth resistor respectively, the other end of the third capacitor is grounded, and the other end of the fifth resistor is connected with the positive current comparison circuit and the negative current comparison circuit respectively.

[0009] The positive current comparison circuit comprises a first operational amplifier, a third end of the first operational amplifier is connected with one end of a ninth resistor and an output end of the positive and negative current detection circuit respectively, a second end of the first operational amplifier is connected with one end of a fourth capacitor, one end of a fourth resistor and one end of a first resistor respectively, the other end of the fourth capacitor, the other end of the fourth resistor and the other end of the ninth resistor are grounded, the other end of the first resistor is connected with the second voltage output end of the power supply circuit, a first end of the first operational amplifier is connected with one end of a second resistor, the other end of the second resistor is connected with the anode of a first diode, and the cathode of the first diode is connected with the level self-locking circuit.

[0010] The negative current comparison circuit comprises a third operational amplifier, a tenth end of the third operational amplifier is connected with one end of a ninth capacitor, one end of a fourteenth resistor, one end of a twelfth resistor and a positive electrode of a fourth diode respectively, the other end of the ninth capacitor and the other end of the fourteenth resistor are grounded, the other end of the twelfth resistor and a negative electrode of the fourth diode are connected with a second voltage output end of the power supply circuit, an eleventh end of the third operational amplifier is connected with a first voltage output end of the power supply circuit, one end of a fifth capacitor and one end of a sixth capacitor respectively, the other end of the fifth capacitor and the other end of the sixth capacitor are grounded, a ninth end of the third operational amplifier is connected with an output end of the positive and negative current detection circuit, an eighth end of the third operational amplifier is connected with one end of a thirteenth resistor, the other end of the thirteenth resistor is connected with a positive electrode of a fifth diode, and a negative electrode of the fifth diode is connected with the level self-locking circuit.

[0011] The level self-locking circuit comprises a second operational amplifier, a fifth end of the second operational amplifier is connected with an output end of the positive current comparison circuit, an output end of the negative current comparison circuit, a negative electrode of a second diode, one end of an eleventh resistor and one end of a seventh capacitor respectively, the other end of the eleventh resistor and the other end of the seventh capacitor are grounded, a positive electrode of the second diode is connected with one end of a third resistor, the other end of the third resistor is connected with a seventh end of the second operational amplifier and an input end of the control output circuit respectively, a sixth end of the second operational amplifier is connected with the overcurrent reset circuit, one end of an eighth capacitor, one end of a seventh resistor and one end of a tenth resistor respectively, the other end of the eighth capacitor and the other end of the tenth resistor are grounded, and the other end of the seventh resistor is connected with a second voltage output end of the power supply circuit.

[0012] The control output circuit comprises a first triode, a base of the first triode is connected with one end of an eighth resistor, the other end of the eighth resistor is connected with the level self-locking circuit, an emitter of the first triode is grounded, a collector of the first triode is connected with a positive electrode of a third diode and one end of a relay coil respectively, a negative electrode of the third diode and the other end of the relay coil are connected with a first voltage output end of the power supply circuit respectively.

[0013] The overcurrent reset circuit comprises a fourth operational amplifier, the fourteenth end of the fourth operational amplifier is connected with the negative electrode of a sixth diode, the positive electrode of the sixth diode is connected with one end of a sixteenth resistor, the other end of the sixteenth resistor is connected with the level self-locking circuit, the positive current comparison circuit and the negative current comparison circuit respectively, the twelfth end of the fourth operational amplifier is also connected with the level self-locking circuit, the thirteenth end of the fourth operational amplifier is connected with one end of a fifteenth resistor and one end of a seventeenth resistor respectively, the other end of the seventeenth resistor is grounded, the other end of the fifteenth resistor is connected with one end of an overcurrent reset switch, the other end of the overcurrent reset switch is connected with the second voltage output end of the power supply circuit.

[0014] The first operational amplifier is LM324AD.

[0015] The current sensor chip is ACS772ECB-200B-FFF-T.

[0016] In the application, one end of the positive current comparison circuit and the negative current comparison circuit is connected with the positive and negative current detection circuit respectively, the other end is connected with the level self-locking circuit and the overcurrent reset circuit respectively, the overcurrent reset circuit is also connected with the level self-locking circuit, the level self-locking circuit is connected with the control output circuit, the power supply circuit supplies power for the rest of the circuits, and the positive and negative current detection circuit is used for detecting whether the current is positive current or negative current.

[0017] If the current is positive current and the output voltage is greater than the preset value, the positive current is compared by the positive current comparison circuit and high voltage is output, at this time, the level self-locking circuit forms positive feedback to complete self-locking, the relay of the control output circuit is attracted and the normally closed contact of the relay is disconnected, when the overcurrent fault is eliminated, the overcurrent reset switch is closed, the relay coil of the control output circuit loses power, and the relay is released to the original initial state. At this time, the circuit returns to the initial state and waits for the next overcurrent signal trigger.

[0018] If the current is negative current and the output voltage is greater than the preset value, the negative current is compared by the negative current comparison circuit and high voltage is output, at this time, the level self-locking circuit forms positive feedback to complete self-locking, the relay of the control output circuit is attracted and the normally closed contact of the relay is disconnected, when the overcurrent fault is eliminated, the overcurrent reset switch is closed, the relay coil of the control output circuit loses power, and the relay is released to the original initial state. At this time, the circuit returns to the initial state and waits for the next overcurrent signal trigger.

[0019] The application processes overcurrent signals through a high-speed operational amplifier, and performs power-off protection through a self-locking circuit and a driving relay, so that the device can be prevented from being damaged by positive and negative current overcurrent, and the positive and negative DC electrical equipment can be protected. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0021] Figure 1 is a schematic diagram of the positive and negative current overcurrent protection self-locking circuit provided by the embodiment of the present application; Figure 2 is a circuit diagram of the positive and negative current overcurrent protection self-locking circuit provided by the embodiment of the present application. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort belong to the scope of protection of the present application.

[0023] Figure 1 is a schematic diagram of the positive and negative current overcurrent protection self-locking circuit provided by the embodiment of the present application, which comprises: a power supply circuit 107, a positive and negative current detection circuit 104, a positive current comparison circuit 103, a negative current comparison circuit 106, a level self-locking circuit 102, an overcurrent reset circuit 105, and a control output circuit 101; One end of the positive current comparison circuit 103 and the negative current comparison circuit 106 is connected to the positive and negative current detection circuit 104 respectively, and the other end is connected to the level self-locking circuit 102 and the overcurrent reset circuit 105 respectively, the overcurrent reset circuit 105 is also connected to the level self-locking circuit 102, and the level self-locking circuit 102 is connected to the control output circuit 101; The power supply circuit 107 is connected to the positive and negative current detection circuit 104, the positive current comparison circuit 103, the negative current comparison circuit 106, the level self-locking circuit 102, the overcurrent reset circuit 105, and the control output circuit 101 respectively.

[0024] Figure 2The application provides a positive and negative current overcurrent protection self-locking circuit, and a circuit diagram of the positive and negative current overcurrent protection self-locking circuit is provided.

[0025] The positive and negative current detection circuit comprises a current sensor chip, the first input end and the second input end of the current sensor chip are connected with external circuits, the first output end of the current sensor chip is connected with the second voltage output end of the power supply circuit, one end of a first capacitor C1 and one end of a second capacitor C2, respectively, the other end of the first capacitor C1, the other end of the second capacitor C2 and the second output end of the current sensor chip are all grounded, the third output end of the current sensor chip is connected with one end of a sixth resistor R6, the other end of the sixth resistor R6 is connected with one end of a third capacitor C3 and one end of a fifth resistor R5, respectively, the other end of the third capacitor C3 is grounded, and the other end of the fifth resistor R5 is connected with the positive current comparison circuit and the negative current comparison circuit.

[0026] The first input end and the second input end of the current sensor chip are connected with external circuits, the first input end is J3, the second input end is J4, and the first input end and the second input end are connected in series in a load circuit and used for detecting the current value state of the circuit.

[0027] The positive current comparison circuit comprises a first operational amplifier, the third end of the first operational amplifier is connected with one end of a ninth resistor R9 and the output end of the positive and negative current detection circuit, respectively, the second end of the first operational amplifier is connected with one end of a fourth capacitor C4, one end of a fourth resistor R4 and one end of a first resistor R1, respectively, the other end of the fourth capacitor C4, the other end of the fourth resistor R4 and the other end of the ninth resistor R9 are all grounded, the other end of the first resistor R1 is connected with the second voltage output end of the power supply circuit, the first end of the first operational amplifier is connected with one end of a second resistor R2, the other end of the second resistor R2 is connected with the anode of a first diode D1, and the cathode of the first diode D1 is connected with the level self-locking circuit. The negative current comparison circuit comprises a third operational amplifier, a tenth end of the third operational amplifier is connected with one end of a ninth capacitor C9, one end of a fourteenth resistor R14, one end of a twelfth resistor R12 and a positive electrode of a fourth diode D4, the other end of the ninth capacitor C9 and the other end of the fourteenth resistor R14 are grounded, the other end of the twelfth resistor R12 and the negative electrode of the fourth diode D4 are connected with a second voltage output end of the power supply circuit, an eleventh end of the third operational amplifier is connected with a first voltage output end of the power supply circuit, one end of a fifth capacitor C5 and one end of a sixth capacitor C6, the other end of the fifth capacitor C5 and the other end of the sixth capacitor C6 are grounded, a ninth end of the third operational amplifier is connected with an output end of the positive and negative current detection circuit, an eighth end of the third operational amplifier is connected with one end of a thirteenth resistor R13, the other end of the thirteenth resistor R13 is connected with a positive electrode of a fifth diode D5, and the negative electrode of the fifth diode D5 is connected with the level self-locking circuit.

[0028] The level self-locking circuit comprises a second operational amplifier, a fifth end of the second operational amplifier is connected with an output end of the positive current comparison circuit, an output end of the negative current comparison circuit, a negative electrode of a second diode D2, one end of an eleventh resistor R11 and one end of a seventh capacitor C7, the other end of the eleventh resistor R11 and the other end of the seventh capacitor C7 are grounded, a positive electrode of the second diode D2 is connected with one end of a third resistor R3, the other end of the third resistor R3 is connected with a seventh end of the second operational amplifier and an input end of the control output circuit, a sixth end of the second operational amplifier is connected with the overcurrent reset circuit, one end of an eighth capacitor C8, one end of a seventh resistor R7 and one end of a tenth resistor R10, the other end of the eighth capacitor C8 and the other end of the tenth resistor R10 are grounded, and the other end of the seventh resistor R7 is connected with a second voltage output end of the power supply circuit.

[0029] The control output circuit comprises a first triode Q1, a base of the first triode Q1 is connected with one end of an eighth resistor R8, the other end of the eighth resistor R8 is connected with the level self-locking circuit, an emitter of the first triode Q1 is grounded, a collector of the first triode Q1 is connected with a positive electrode of a third diode D3 and one end of a relay coil, respectively, and a negative electrode of the third diode D3 and the other end of the relay coil are connected with a first voltage output end of the power supply circuit.

[0030] J1 is a relay input port, J2 is a relay output port, in the off or closed state, for transmitting signals to the host computer or single-chip microcomputer or directly driving a high-power contactor or relay to cut off the load power supply and protect the equipment.

[0031] The overcurrent reset circuit comprises a fourth operational amplifier, a fourteenth terminal of the fourth operational amplifier is connected with a negative electrode of a sixth diode D6, a positive electrode of the sixth diode D6 is connected with one end of a sixteenth resistor R16, the other end of the sixteenth resistor R16 is connected with the level self-locking circuit, the positive current comparison circuit and the negative current comparison circuit respectively, a twelfth terminal of the fourth operational amplifier is also connected with the level self-locking circuit, a thirteenth terminal of the fourth operational amplifier is connected with one end of a fifteenth resistor R15 and one end of a seventeenth resistor R17 respectively, the other end of the seventeenth resistor R17 is grounded, the other end of the fifteenth resistor R15 is connected with one end of an overcurrent reset switch, the other end of the overcurrent reset switch is connected with a second voltage output terminal of the power supply circuit.

[0032] The circuit principle is as follows: The DC 12V power supply is input to the twelfth capacitor C12 through the port JP1, filtered and then output as a +12V power supply, and another power supply is supplied to the three-terminal voltage stabilizing chip IC2 (model 78M05) to be reduced to a +5V power supply, and the tenth capacitor C10 and the eleventh capacitor C11 are both filter capacitors.

[0033] That is, the power supply circuit can serve as a first voltage output terminal, that is, a +12V voltage output terminal, and also can serve as a second voltage output terminal, that is, a +5V voltage output terminal, and the power supply circuit supplies power to the rest of the circuits.

[0034] The first input terminal and the second input terminal of the current sensor chip IC1 are connected with external circuits, the first capacitor C1 and the second capacitor C2 are both filter capacitors, the current sensor chip IC1 outputs a 2.5V direct current signal when the current is 0, outputs a voltage greater than 2.5V when the current is positive, and outputs a voltage less than 2.5V when the current is negative.

[0035] The following describes the case when the current is positive: When the positive current, that is, the positive phase output current, reaches 120A, the voltage output by the third output terminal, that is, the 3-pin output, of the current sensor chip IC1 is about 3.7V, at this time, the 3.7V signal output by the third output terminal of the current sensor chip IC1 is output as a stable 3.7V signal through the RC high-frequency filter circuit composed of the sixth resistor R6 and the third capacitor C3, and the fifth resistor R5 is a current limiting resistor.

[0036] The third end of the first operational amplifier, i.e. the 3rd pin, and the second end, i.e. the 2nd pin, are compared by the fifth resistor R5 and the ninth resistor R9, i.e. a pull-down resistor. The voltage at the 2nd pin is obtained by dividing the voltage of +5V by the first resistor R1 and the fourth resistor R4 to obtain a voltage of 3.7V and filtering by the fourth capacitor C4. If the voltage at the 3rd pin of the first operational amplifier is greater than the voltage of 3.7V at the 2nd pin, the first end of the first operational amplifier, i.e. the 1st pin, outputs a high level voltage of 5V, which is sent to the seventh capacitor through the second resistor and the first diode. The second resistor is a current-limiting resistor, the first diode is a single-phase conducting diode, and the seventh capacitor is a voltage holding capacitor.

[0037] The voltage at the fifth end of the second operational amplifier, i.e. the 5th pin, and the voltage at the sixth end, i.e. the 6th pin, are compared. The voltage at the 6th pin is obtained by dividing the voltage of +5V by the seventh resistor R7 and the tenth resistor R10 and filtering by the eighth capacitor C8 to obtain a voltage of 2.5V. At this time, the voltage at the 5th pin is 5V, which is greater than the voltage at the 6th pin, i.e. 2.5V. Therefore, the seventh end of the second operational amplifier, i.e. the 7th pin, outputs a high level voltage of 5V. One way is to charge the seventh capacitor C7 through the third resistor R3, i.e. a current-limiting resistor, and the second diode D2, forming positive feedback to complete self-locking. At this time, if the current signal disappears, the circuit is also in a self-locking protection state. The voltage at the seventh end of the second operational amplifier, i.e. the 7th pin, is another way to flow to the first transistor Q1 through the eighth resistor R8, i.e. a current-limiting resistor, so that the first transistor Q1 is positively biased and turned on. After the first transistor Q1 is turned on, +12V forms a loop through the first transistor Q1 to the ground through the relay coil, so that the relay K1 is attracted and disconnected, and the normally closed contact of the relay is powered off.

[0038] At this time, the circuit overcurrent fault is eliminated. The overcurrent reset switch S1 is closed, and the voltage of +5V is divided by the fifteenth resistor R15 and the seventeenth resistor R17 to obtain a voltage of about 4.5V, which is sent to the thirteenth end of the fourth operational amplifier, i.e. the 13th pin, and the voltage of 2.5V at the twelfth end, i.e. the 12th pin. Since the voltage at the thirteenth end is greater than the voltage at the twelfth end, the fourteenth end of the fourth operational amplifier, i.e. the 14th pin, outputs a low level voltage of 0V, which is sent to the fifth end of the second operational amplifier, i.e. the 5th pin, through the sixth diode D6 and the sixteenth resistor R16, i.e. a current-limiting resistor, to lower the voltage at the 5th pin to about 0.1V. At this time, the voltage at the sixth end of the second operational amplifier, i.e. the 6th pin, is 2.5V, which is greater than the voltage at the 5th pin, i.e. 0.1V. The voltage at the seventh end of the second operational amplifier, i.e. the 7th pin, is a low level voltage of 0V, which is sent to the base of the first transistor Q1, i.e. the base, through the eighth resistor R8, i.e. a voltage of 0V. The first transistor Q1 is cut off and closed. The relay K1 is also released to the original initial state due to the loss of power of the relay coil. At this time, the circuit returns to the initial state and waits for the next overcurrent signal trigger.

[0039] The following describes the case when the negative current signal is: When the negative current, i.e. the reverse phase output current, reaches 120A, the voltage at the third output terminal of the current sensor chip IC1, i.e. the 3-pin output, is about 1.3V. At this time, the 3-pin output of the current sensor chip IC1 outputs a stable 1.3V signal through the RC high-frequency filter circuit composed of the sixth resistor R6 and the third capacitor C3. The fifth resistor R5 is a current-limiting resistor.

[0040] The voltage at the ninth terminal of the third operational amplifier, i.e. the 9-pin, and the tenth terminal, i.e. the 10-pin, is compared through the fifth resistor R5 and the ninth resistor R9, i.e. the pull-down resistor. The voltage at the tenth terminal is obtained by dividing the +5V through the fourth resistor R4 and the twelfth resistor R12 to obtain a 1.3V voltage and filtering by the ninth capacitor C9. The fourth diode D4 is a fast reset discharge diode during shutdown.

[0041] If the voltage at the 9-pin of the third operational amplifier is less than the 1.3V voltage at the 10-pin, the eighth terminal of the third operational amplifier, i.e. the 8-pin, outputs a high-level 5V voltage, which is sent to the seventh capacitor through the thirteenth resistor and the fifth diode. The thirteenth resistor is a current-limiting resistor, the fifth diode is a single-phase conduction diode, and the seventh capacitor is a voltage holding capacitor.

[0042] The voltage at the fifth terminal of the second operational amplifier, i.e. the 5-pin, and the sixth terminal, i.e. the 6-pin, is compared (the voltage at the 6-pin is obtained by dividing +5V through the seventh resistor R7 and the tenth resistor R10 and filtering by the eighth capacitor C8 to obtain 2.5V). At this time, the voltage at the 5-pin is 5V, which is greater than the voltage at the 6-pin, i.e. 2.5V, so the seventh terminal of the second operational amplifier, i.e. the 7-pin, outputs a high-level 5V. One way is to charge the seventh capacitor C7 through the third resistor R3, i.e. the current-limiting resistor, and the second diode D2, forming a positive feedback to complete self-locking. At this time, if the current signal disappears, the circuit is also in a self-locking protection state. The voltage at the seventh terminal of the second operational amplifier, i.e. the 7-pin, is another way to flow to the first transistor Q1 through the eighth resistor R8, i.e. the current-limiting resistor, so that the first transistor Q1 is positively biased and turned on. After the first transistor Q1 is turned on, +12V forms a loop through the first transistor Q1 to the ground through the relay coil, so that the relay K1 is attracted and disconnected, and the normally closed contact of the relay is powered off.

[0043] If the overcurrent fault is cleared, press the overcurrent reset switch S1 to close it. The +5V voltage is divided by the voltage divider resistors R15 (15th resistor) and R17 (17th resistor) to obtain approximately 4.5V, which is then sent to the 13th pin (pin 13) of the fourth operational amplifier for comparison with the 2.5V at the 12th pin (pin 12). Since the voltage at the 13th pin is greater than that at the 12th pin, the 14th pin (pin 14) of the fourth operational amplifier outputs a low level of 0V. This low level is then passed through the 6th diode D6 and the 16th resistor R16 (current limiting resistor), pulling the voltage at the 5th pin of the second operational amplifier down to approximately 0.1V. At this point, the 2.5V at the 6th pin of the second operational amplifier is greater than the 0.1V at the 5th pin, and the 7th pin of the second operational amplifier outputs a low level of 0V. This low level is then passed through the 8th resistor R8 to the base of the first transistor Q1, where the base voltage is 0V. The first transistor Q1 is then cut off, and the relay K1 is released to its initial state due to the de-energization of its coil. At this point, the circuit returns to its initial state and waits for the next overcurrent signal to trigger.

[0044] The first operational amplifier is model LM324AD.

[0045] The current sensor chip is model ACS772ECB-200B-FFF-T.

[0046] In this invention, one end of the positive current comparison circuit and the negative current comparison circuit are respectively connected to the positive and negative current detection circuit, and the other end is respectively connected to the level self-locking circuit and the overcurrent reset circuit. The overcurrent reset circuit is also connected to the level self-locking circuit. The level self-locking circuit is connected to the control output circuit. The power supply circuit supplies power to the other circuits. The positive and negative current detection circuit is used to detect whether the current is positive or negative.

[0047] If the current is positive and the output voltage is greater than the preset value, the positive current is compared by the positive current comparison circuit and a high-level voltage is output. At this time, the level self-locking circuit forms positive feedback to complete self-locking. The relay of the control output circuit is energized and disconnected, and the normally closed contact of the relay is de-energized. When the overcurrent fault in the circuit is cleared, the overcurrent reset switch is closed. The relay coil of the control output circuit is de-energized, causing the relay to release to its initial state. At this point, the circuit returns to its initial state, waiting for the next overcurrent signal to trigger.

[0048] If the negative current and the output voltage is greater than the preset value, the negative current is compared by the negative current comparison circuit and outputs a high voltage, at this time, the level self-locking circuit forms positive feedback to complete self-locking, the relay coil of the control output circuit loses power, and the relay releases to the original initial state. At this time, the circuit returns to the initial state, and waits for the next overcurrent signal trigger.

[0049] The application processes the overcurrent signal by a high-speed operational amplifier, and performs power-off protection by self-locking circuit and driving relay, which can prevent the damage of equipment caused by positive and negative current overcurrent, and plays a role in protecting the positive and negative DC electrical equipment.

[0050] The above is only the preferred embodiment of the present application, and it should be pointed out that for those skilled in the art, without departing from the technical principles of the present application, a number of improvements and substitutions can be made, which should also be considered as the protection scope of the present application.

Claims

1. A positive and negative overcurrent protection self-locking circuit, characterized in that, include: Power supply circuit, positive and negative current detection circuit, positive current comparison circuit, negative current comparison circuit, level self-locking circuit, overcurrent reset circuit, and control output circuit; One end of the positive current comparison circuit and the negative current comparison circuit are respectively connected to the positive and negative current detection circuits, and the other end is respectively connected to the level self-locking circuit and the overcurrent reset circuit. The overcurrent reset circuit is also connected to the level self-locking circuit, and the level self-locking circuit is connected to the control output circuit. The power supply circuit is connected to the positive and negative current detection circuit, the positive current comparison circuit, the negative current comparison circuit, the level self-locking circuit, the overcurrent reset circuit, and the control output circuit.

2. The positive and negative current overcurrent protection self-locking circuit as described in claim 1, characterized in that, The power supply circuit includes: a DC power input port, a first output terminal of the DC power input port grounded, a second output terminal of the DC power input port connected to one end of a twelfth capacitor and the input terminal of a voltage regulator chip, the other end of the twelfth capacitor and the ground terminal of the voltage regulator chip both grounded, the output terminal of the voltage regulator chip connected to one end of a tenth capacitor and one end of an eleventh capacitor, the other ends of the tenth capacitor and the eleventh capacitor both grounded, the second output terminal of the DC power input port serving as a first voltage output terminal, and the output terminal of the voltage regulator chip serving as a second voltage output terminal.

3. The positive and negative current overcurrent protection self-locking circuit as described in claim 1, characterized in that, The positive and negative current detection circuit includes: a current sensor chip, the first input terminal and the second input terminal of the current sensor chip are connected to an external circuit, the first output terminal of the current sensor chip is connected to the second voltage output terminal of the power supply circuit, one end of the first capacitor and one end of the second capacitor respectively, the other end of the first capacitor, the other end of the second capacitor and the second output terminal of the current sensor chip are all grounded, the third output terminal of the current sensor chip is connected to one end of the sixth resistor, the other end of the sixth resistor is connected to one end of the third capacitor and one end of the fifth resistor respectively, the other end of the third capacitor is grounded, and the other end of the fifth resistor is connected to the positive current comparison circuit and the negative current comparison circuit respectively.

4. The positive and negative current overcurrent protection self-locking circuit as described in claim 1, characterized in that, The positive current comparison circuit includes: a first operational amplifier, the third terminal of which is connected to one end of the ninth resistor and the output terminal of the positive and negative current detection circuit, the second terminal of which is connected to one end of the fourth capacitor, one end of the fourth resistor and one end of the first resistor, the other end of the fourth capacitor, the other end of the fourth resistor and the other end of the ninth resistor are all grounded, the other end of the first resistor is connected to the second voltage output terminal of the power supply circuit, the first terminal of the first operational amplifier is connected to one end of the second resistor, the other end of the second resistor is connected to the positive terminal of the first diode, and the negative terminal of the first diode is connected to the level lockout circuit.

5. The positive and negative current overcurrent protection self-locking circuit as described in claim 1, characterized in that, The negative current comparison circuit includes: a third operational amplifier, the tenth terminal of which is connected to one end of the ninth capacitor, one end of the fourteenth resistor, one end of the twelfth resistor, and the positive terminal of the fourth diode; the other ends of the ninth capacitor and the fourteenth resistor are grounded; the other end of the twelfth resistor and the negative terminal of the fourth diode are connected to the second voltage output terminal of the power supply circuit; the eleventh terminal of the third operational amplifier is connected to the first voltage output terminal of the power supply circuit, one end of the fifth capacitor, and one end of the sixth capacitor; the other ends of the fifth capacitor and the sixth capacitor are grounded; the ninth terminal of the third operational amplifier is connected to the output terminal of the positive and negative current detection circuit; the eighth terminal of the third operational amplifier is connected to one end of the thirteenth resistor; the other end of the thirteenth resistor is connected to the positive terminal of the fifth diode; and the negative terminal of the fifth diode is connected to the level-locking circuit.

6. The positive and negative current overcurrent protection self-locking circuit as described in claim 1, characterized in that, The level-locked circuit includes: a second operational amplifier, the fifth terminal of which is connected to the output terminal of the positive current comparator circuit, the output terminal of the negative current comparator circuit, the negative terminal of the second diode, one end of the eleventh resistor, and one end of the seventh capacitor, respectively; the other end of the eleventh resistor and the other end of the seventh capacitor are both grounded; the positive terminal of the second diode is connected to one end of the third resistor, the other end of the third resistor is connected to the seventh terminal of the second operational amplifier and the input terminal of the control output circuit, the sixth terminal of the second operational amplifier is connected to the overcurrent reset circuit, one end of the eighth capacitor, one end of the seventh resistor, and one end of the tenth resistor, respectively; the other end of the eighth capacitor and the other end of the tenth resistor are both grounded; and the other end of the seventh resistor is connected to the second voltage output terminal of the power supply circuit.

7. The positive and negative current overcurrent protection self-locking circuit as described in claim 1, characterized in that, The control output circuit includes: a first transistor, the base of which is connected to one end of an eighth resistor, the other end of which is connected to the level-locking circuit, the emitter of which is grounded, the collector of which is connected to the anode of a third diode and one end of a relay coil, and the cathode of the third diode and the other end of the relay coil are connected to the first voltage output terminal of the power supply circuit.

8. The positive and negative current overcurrent protection self-locking circuit as described in claim 1, characterized in that, The overcurrent reset circuit includes: a fourth operational amplifier, the fourteenth terminal of which is connected to the negative terminal of a sixth diode, the positive terminal of the sixth diode being connected to one end of a sixteenth resistor, the other end of the sixteenth resistor being connected to the level latching circuit, the positive current comparator circuit, and the negative current comparator circuit, the twelfth terminal of the fourth operational amplifier being connected to the level latching circuit, the thirteenth terminal of the fourth operational amplifier being connected to one end of a fifteenth resistor and one end of a seventeenth resistor, the other end of the seventeenth resistor being grounded, the other end of the fifteenth resistor being connected to one end of an overcurrent reset switch, and the other end of the overcurrent reset switch being connected to the second voltage output terminal of the power supply circuit.

9. The positive and negative current overcurrent protection self-locking circuit as described in claim 4, characterized in that, The first operational amplifier is model LM324AD.

10. The positive and negative current overcurrent protection self-locking circuit as described in claim 3, characterized in that, The current sensor chip is model ACS772ECB-200B-FFF-T.

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