An overcurrent protection device control circuit and design method thereof

Abstract

The present invention relates to a control circuit for an overcurrent protection device and a design method thereof. The control circuit includes a power module, a sampling module, a threshold analysis module, and an execution protection module. The power module is used to connect to an electrical connector socket and convert an input voltage into an operating voltage for the sampling module and the threshold analysis module. The sampling module is used to connect to the electrical connector socket and collect the output signal of the electrical connector socket. The threshold analysis module is connected to the sampling module and controls the operating state based on the input voltage difference. The execution protection module is connected to the threshold analysis module and connected to a trip unit to control the operating state of the trip unit based on the output signal of the execution analysis module. The present invention can energize the trip unit coil according to the actual operating current of the circuit to be protected. The product contact system and the control system drive the switch to operate, delay disconnection or instantaneous disconnection of the circuit to protect the subsequent circuit.

Description

Technical Field

[0001] The present invention relates to the technical field of overcurrent protection in circuit structures, and in particular to an overcurrent protection device control circuit and a design method thereof. Background Art

[0002] Common overcurrent protection devices on the market can only realize the single function of automatically disconnecting the switch when the operating current exceeds a certain limit. They are unable to simultaneously realize the two control functions of delayed disconnection and instantaneous disconnection of the switch based on the actual current flowing through the product and the product operating conditions. Summary of the Invention

[0003] In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is to provide an overcurrent protection device control circuit and a design method thereof.

[0004] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: an overcurrent protection device control circuit, including a power supply module, a sampling module, a threshold analysis module and an execution protection module;

[0005] The power supply module is used to connect to the electrical connector socket and is used to convert the input voltage into the operating voltage of the sampling module and the threshold analysis module;

[0006] The sampling module is used to connect to the electrical connector socket and collect the output signal of the electrical connector socket;

[0007] The threshold analysis module is connected to the sampling module and is used to control the working state according to the input voltage difference;

[0008] The execution protection module is connected to the threshold analysis module, and is used to connect to the trip unit, and is used to control the working state of the trip unit according to the output signal of the execution protection module.

[0009] The power supply module includes a transient suppression diode, a first filtering circuit, a voltage regulator, and a second filtering circuit. The transient suppression diode and the first filtering circuit are both connected between the input voltage and the ground line. The voltage regulator is connected between the input voltage and the output working voltage. The second filtering circuit is connected between the output working voltage and the ground line.

[0010] The sampling module includes a sampling resistor and an amplifier circuit, and performs on-off node control by controlling the current range flowing through the sampling resistor.

[0011] The threshold analysis module includes a first comparator circuit, a second comparator circuit, a delay circuit and a third comparator circuit;

[0012] The non-inverting input terminals of the first comparator circuit and the second comparator circuit are connected to the output terminal of the sampling module, and the inverting input terminals are connected to the output terminal of the power supply module after voltage division;

[0013] The non-inverting input terminal of the third comparator circuit is connected to the output terminal of the second comparator circuit, the inverting input terminal is connected to the output terminal of the power supply module after voltage division, and a delay circuit is connected between the non-inverting input terminal and the inverting input terminal of the third comparator circuit.

[0014] The execution protection module includes a first diode, a second diode and a transistor;

[0015] The anode of the first diode is connected to the output end of the first comparator circuit, and the cathode is connected to the base of the transistor; the anode of the second diode is connected to the output end of the third comparator circuit, and the cathode is connected to the base of the transistor; the emitter of the transistor is connected to the ground wire, and the collector is connected to the release.

[0016] A method for designing a control circuit of an overcurrent protection device, comprising:

[0017] A sampling module, a threshold analysis module and an execution protection module are sequentially arranged between the electrical connector socket and the trip unit;

[0018] The sampling module is used to collect the output signal of the input electrical connector socket; the threshold analysis module is used to control the working state through the input voltage difference; and the execution protection module is used to control the working state of the trip unit according to the output signal of the execution protection module.

[0019] It also includes: a power supply module for providing a working voltage arranged between the electrical connector socket and the sampling module and the threshold analysis module.

[0020] The threshold analysis module includes a first comparator circuit, a second comparator circuit, a delay circuit and a third comparator circuit;

[0021] The non-inverting input terminals of the first comparator circuit and the second comparator circuit are connected to the output terminal of the sampling module, and the inverting input terminals are connected to the output terminal of the power supply module after voltage division; the non-inverting input terminal of the third comparator circuit is connected to the output terminal of the second comparator circuit, and the inverting input terminal is connected to the output terminal of the power supply module after voltage division, and a delay circuit is connected between the non-inverting input terminal and the inverting input terminal of the third comparator circuit.

[0022] The sampling module includes a sampling resistor and an amplifier circuit, and performs on-off node control by controlling the current range flowing through the sampling resistor, specifically:

[0023] When the input current of the electrical connector socket is less than 6.6A, the voltage U output by the amplifier circuit is less than the voltage of the inverting input terminal of the second comparator circuit and the first comparator circuit, the comparators both output a low level, the release does not trip, and the switch is turned on;

[0024] When the input current of the electrical connector socket is greater than 6.9A and less than 9.5A, the voltage U output by the amplifier circuit is greater than the voltage at the inverting input terminal of the second comparator circuit and less than the voltage at the inverting input terminal of the first comparator circuit, causing the first comparator circuit to output a low level and the second comparator circuit to output a high level. The delay circuit operates, the capacitor starts charging, and the third comparator outputs a high level to drive the release to disconnect the switch.

[0025] When the input current of the electrical connector socket is greater than 10.5A, the voltage U output by the amplifier circuit is greater than the voltage of the inverting input terminal of the first comparator circuit, and the first comparator circuit outputs a high level, driving the release to disconnect the switch.

[0026] The present invention has the following advantages and beneficial effects:

[0027] 1. The present invention can energize the trip coil according to the actual working current of the circuit to be protected. The product contact system and control system drive the switch to operate, delay disconnection or instantaneous disconnection of the circuit to protect the subsequent circuit.

[0028] 2. The present invention can be widely used in aerospace, aviation, industry, vehicles, power systems, metallurgical systems, ships and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural block diagram of the control circuit of the present invention;

[0030] Figure 2 This is the circuit schematic diagram of the power module of the control circuit;

[0031] Figure 3 It is the schematic diagram of the sampling circuit module of the control circuit;

[0032] Figure 4 This is the schematic diagram of the threshold analysis module of the control circuit;

[0033] Figure 5 It is the schematic diagram of the execution protection circuit module of the control circuit. DETAILED DESCRIPTION

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0035] like Figure 1-5As shown, the control circuit mainly consists of four parts: the power supply module, the sampling circuit module, the threshold analysis module, and the execution protection module. The power supply module consists of a three-terminal fixed voltage regulator JW78L05, a transient suppression diode SY6053A, capacitors, and resistors. It prevents voltage fluctuations from burning out the downstream chip and converts the input voltage into the 5V operating voltage required by the digital chip. The sampling circuit module mainly consists of a sampling resistor RXG12-0.01Ω / 5W and a dual-channel operational amplifier F353 for collecting input signals. The threshold analysis module consists of a four-channel comparator JF139 and controls the product's operating state by the input voltage difference between the two ends of the comparator. The execution protection module consists of a transistor 3DK104C and its main function is to prevent product damage due to improper operation.

[0036] like Figure 2 As shown in the figure, the power module is constructed as follows: After the 22V-32V test voltage is input through the electrical connector socket, it passes through transient suppression diode D4 to prevent voltage spikes in the circuit. After filtering the input voltage through capacitors C5 and C6, the three-terminal voltage regulator IC1 stabilizes the input voltage to 5V. It is then filtered by capacitors C3 and C4 to provide the power supply voltage for operational amplifier U1 and comparator U2.

[0037] like Figure 3 As shown, the sampling circuit module is composed as follows: During normal operation, the sampling resistor RQ is converted into a voltage by the current in the sampling circuit. According to the characteristics of the virtual short and virtual open of the operational amplifier, the voltage across R2 is equal to the voltage across RQ, that is, U RQ =U R2 , and I R2 =I R6 , then U R2 / R2= U R6+R并 / (R6+R in parallel), where R in parallel is the parallel resistance value of R6-1, R6-2 and R6-3. The on / off node of the overcurrent protection device can be controlled by controlling the current range flowing through the precision resistor RQ. Figure 4 As shown, the threshold analysis module is composed as follows: the voltage output by the sampling circuit module is used as the non-inverting input terminal of the comparator U2A and U2B, and the voltage at the inverting input terminal of U2A is controlled by the resistors R7 and R7. ， , R8, R8 ， The 5V voltage output by the voltage regulator is divided and the resistance value is adjusted according to actual needs to control the current value of the instantaneous disconnection of the switch; the voltage at the inverting input of U2A is determined by resistors R9 and R9 ， R14 and R24 divide the 5V output voltage of the voltage regulator. Adjust the resistor values according to actual needs to control the current value of the switch delay disconnection. Comparator U2D is floating.

[0038] like Figure 5 As shown in the figure, the execution protection module is composed of the following: This part mainly consists of transistor Q2, diodes D1 and D2. Its main function is to transfer the voltage at the output end of the comparator of the threshold analysis circuit to transistor Q2 through the unidirectional diodes D1 and D2. Through the current amplification effect of the transistor, the working state of the trip device is controlled to prevent the subsequent circuit from being damaged due to improper operation of the product.

[0039] When the product is working normally, the sampling resistor RQ is converted into a voltage by the current in the sampling circuit. According to the characteristics of the operational amplifier's virtual short, the voltage across RQ is equal to the voltage of R2, R3 and R4 in series. According to the characteristics of the operational amplifier's virtual open, the input current at the operational amplifier's input is almost zero, so no current flows through R2 and R3, and the current flows to Q1 through R2 and R5. At this time, the voltage across R2 is equal to the voltage across RQ, that is, U RQ =U R2 , and I R2 =I R6 , then U R2 / R2= U R6+R并 / (R6 + R in parallel), where R is the parallel resistance value of R6-1, R6-2 and R6-3. In order to achieve different operating characteristics of products with different current ranges, two current nodes are set up - 6.7A and 10A, which correspond to the amplifier output voltage respectively. The corresponding comparator U2A and U2B's non-inverting input voltages are 2.01V and 3V respectively. The inverting input voltage is the voltage value obtained by dividing the two resistors as the reference voltage. The reference voltage of U2A is (R8 + R8 ， ) / ( R8+R8 ， +R24+R7 , ) 5V=3V; the reference voltage of U2B is (R9+R9 ， ) / (R9+R9 ， +R24） ×5V=2.06V; the working conditions are as follows:

[0040] a) When the current is less than 6.6A, the voltage U output by the amplifier circuit is less than the reference voltage of the comparators U2B and U2A, and the comparators both output a low level, and the circuit acts as a switch;

[0041] b) When the current is greater than 6.9A and less than 9.5A, the voltage U output by the amplifier circuit is greater than the reference voltage of comparator U2B and less than the reference voltage of U2A, causing comparator U2A to output a low level and U2B to output a high level. Capacitor C1 begins to charge. After 4 to 5 seconds, when the voltage across C1 is equal to 0.01, comparator U2C outputs a high level to drive the release to disconnect the switch.

[0042] c) When the current is greater than 10.5A, the voltage U output by the amplifier circuit is greater than the reference voltage of the comparator U2A. The comparator U2A outputs a high level, driving the release to immediately disconnect the switch in less than 1s.

[0043] Through the above calculations, the overcurrent protection device designed using this control circuit principle can achieve the following functions:

[0044] a) When the current is less than 6.6A, the powered equipment operates normally;

[0045] b) Cut off the surge of 6.9A-9.5A with a delay time of 4 to 5 seconds;

[0046] c) Cut off surges greater than 10.5A in less than 1 second.

[0047] At present, the applicant has completed the production of three overcurrent protection devices using this circuit principle, and all of them have passed the performance test. The test results are as follows (all current point tests have been completed at any voltage point):

[0048] Voltage test points are 22V, 24V, 25.5V, 30V, 32V;

[0049] The current test points are 3.2A, 6.6A, 6.9A, 8A, 9.5A, 10.5A, and 11A.

[0050] a) The product switch does not disconnect after being closed and powered on under the conditions of 3.2A and 6.6A (test time is 1 minute);

[0051] b) Under the conditions of 6.9A, 8A, and 9.5A, the product switch is closed and energized for 4 to 5 seconds before disconnecting;

[0052] c) Under the conditions of 10.5A and 11A, the product switch is disconnected within 1 second after closing.

Claims

1. An overcurrent protection device control circuit, characterized in that: It includes power supply module, sampling module, threshold analysis module and execution protection module; The power supply module is used to connect to the electrical connector socket and is used to convert the input voltage into the operating voltage of the sampling module and the threshold analysis module; The sampling module is used to connect to the electrical connector socket and collect the output signal of the electrical connector socket; The threshold analysis module is connected to the sampling module and is used to control the working state according to the input voltage difference; The execution protection module is connected to the threshold analysis module, which is used to connect to the trip unit and control the working state of the trip unit according to the output signal of the execution protection module; The threshold analysis module includes a first comparator circuit, a second comparator circuit, a delay circuit and a third comparator circuit; The non-inverting input terminals of the first comparator circuit and the second comparator circuit are connected to the output terminal of the sampling module, and the inverting input terminals are connected to the output terminal of the power supply module after voltage division; The non-inverting input terminal of the third comparator circuit is connected to the output terminal of the second comparator circuit, the inverting input terminal is connected to the output terminal of the power supply module after voltage division, and a delay circuit is connected between the non-inverting input terminal and the inverting input terminal of the third comparator circuit; The execution protection module includes a first diode, a second diode and a transistor; The anode of the first diode is connected to the output end of the first comparator circuit, and the cathode is connected to the base of the transistor; the anode of the second diode is connected to the output end of the third comparator circuit, and the cathode is connected to the base of the transistor; the emitter of the transistor is connected to the ground wire, and the collector is connected to the release; The power module includes a transient suppression diode, a first filtering circuit, a voltage stabilizer, and a second filtering circuit, wherein the transient suppression diode and the first filtering circuit are both connected between the input voltage and the ground line, the voltage stabilizer is connected between the input voltage and the output working voltage, and the second filtering circuit is connected between the output working voltage and the ground line; Diodes are provided on the input paths of the execution protection modules.

2. The overcurrent protection device control circuit according to claim 1, characterized in that: The sampling module includes a sampling resistor and an amplifier circuit, and performs on-off node control by controlling the current range flowing through the sampling resistor.

3. A method for designing an overcurrent protection device control circuit, applied to the overcurrent protection device control circuit described in claim 1, characterized in that: include: A power supply module, a sampling module, a threshold analysis module and an execution protection module are sequentially arranged between the electrical connector socket and the trip unit; The sampling module is used to collect the output signal of the input electrical connector socket; the threshold analysis module is used to control the working state through the input voltage difference; and the execution protection module is used to control the working state of the trip unit according to the output signal of the execution protection module.

4. The method for designing a control circuit of an overcurrent protection device according to claim 3, wherein: Also includes: A power supply module for providing a working voltage is provided between the electrical connector socket and the sampling module and the threshold analysis module.

5. The method for designing a control circuit of an overcurrent protection device according to claim 3, wherein: The threshold analysis module includes a first comparator circuit, a second comparator circuit, a delay circuit and a third comparator circuit; The non-inverting input terminals of the first comparator circuit and the second comparator circuit are connected to the output terminal of the sampling module, and the inverting input terminals are connected to the output terminal of the power supply module after voltage division; the non-inverting input terminal of the third comparator circuit is connected to the output terminal of the second comparator circuit, and the inverting input terminal is connected to the output terminal of the power supply module after voltage division, and a delay circuit is connected between the non-inverting input terminal and the inverting input terminal of the third comparator circuit; The sampling module includes a sampling resistor and an amplifier circuit, and performs on-off node control by controlling the current range flowing through the sampling resistor, specifically: When the input current of the electrical connector socket is less than 6.6A, the voltage U output by the amplifier circuit is less than the voltage of the inverting input terminal of the second comparator circuit and the first comparator circuit, the comparators both output a low level, the release does not trip, and the switch is turned on; When the input current of the electrical connector socket is greater than 6.9A and less than 9.5A, the voltage U output by the amplifier circuit is greater than the voltage at the inverting input terminal of the second comparator circuit and less than the voltage at the inverting input terminal of the first comparator circuit, causing the first comparator circuit to output a low level and the second comparator circuit to output a high level. The delay circuit operates, the capacitor starts charging, and the third comparator outputs a high level to drive the release to disconnect the switch. When the input current of the electrical connector socket is greater than 10.5A, the voltage U output by the amplifier circuit is greater than the voltage of the inverting input terminal of the first comparator circuit, and the first comparator circuit outputs a high level, driving the release to disconnect the switch.

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