Protection circuit of direct current conversion circuit

Abstract

The utility model relates to the technical field of power electronics, and discloses a protection circuit of a direct-current conversion circuit, the protection circuit is connected with the direct-current conversion circuit, the direct-current conversion circuit comprises a control module and a power module, a sampling end of an input protection circuit is connected with a direct-current voltage input end of the direct-current conversion circuit, and an output end of the input protection circuit is connected with the control module; the sampling end of the output protection circuit is connected with the DC voltage output end of the DC conversion circuit, and the output end of the output protection circuit is connected with the control module. The over-temperature protection circuit comprises a temperature sampling unit and an over-temperature detection circuit, and the output end of the over-temperature detection circuit is connected with the control module; the overcurrent protection circuit comprises a voltage conversion unit and a voltage detection circuit, the output end of the voltage detection circuit is connected with the control module, a signal for stopping work can be sent to the control module in time under the conditions of undervoltage, overvoltage, overcurrent and overhigh temperature, the direct current conversion work is stopped, and the work safety is comprehensively improved.

Description

Technical Field

[0001] The invention relates to the technical field of power electronics, and in particular to a protection circuit for a direct current conversion circuit. Background Art

[0002] Direct Current / Direct Current (DC / DC) converters are widely used in remote and data communications, military, computer, aerospace and other fields. DC / DC converters convert fixed DC voltage into variable DC voltage through DC / DC conversion circuits. With the development of science and technology, more and more types of integrated circuits are used in electronic equipment products in the above fields. The power supply voltage required by integrated circuits is different, and DC / DC conversion circuits are needed to provide DC power to electronic equipment according to demand. For DC power supply, several issues need to be considered:

[0003] The input and output of the power supply should have a relatively fixed operating voltage range. If the input voltage is too low, some circuits in the power supply will not work properly. If the output voltage is too low, the load (such as electronic chips) will not work properly. If the output voltage is too high, the electronic products will be burned. Abnormal input voltage and output voltage will damage the power supply and electronic products or reduce their service life.

[0004] The power supply should have a stable input current. Excessive input current will also cause damage to the secondary power supply. Therefore, the working voltage and current of the secondary power supply must be managed in a standardized manner to form a comprehensive protection circuit. A power supply with perfect protection function can extend the life of the power supply and improve the reliability of the system. When a fault occurs in the external circuit of the power supply, it will automatically enter the protection state without permanent failure. When some external faults disappear, it will automatically return to normal to ensure the safety of the system. Summary of the invention

[0005] The purpose of the present invention is to provide a protection circuit for a DC conversion circuit to solve the following technical problems:

[0006] How to provide a protection circuit that can fully protect the DC conversion circuit.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] A protection circuit for a DC conversion circuit, connected to the DC conversion circuit, wherein the DC conversion circuit includes a control module and a power module, including an input protection circuit, an output protection circuit, an over-temperature protection circuit and an over-current protection circuit;

[0009] The sampling end of the input protection circuit is connected to the DC voltage input end of the DC conversion circuit, and the output end of the input protection circuit is connected to the control module;

[0010] The sampling end of the output protection circuit is connected to the DC voltage output end of the DC conversion circuit, and the output end of the output protection circuit is connected to the control module;

[0011] The over-temperature protection circuit comprises a temperature sampling unit and an over-temperature detection circuit, wherein the temperature sampling unit collects temperature data of the DC conversion circuit, and the output end of the over-temperature detection circuit is connected to the control module;

[0012] The overcurrent protection circuit includes a voltage conversion unit and a voltage detection circuit. The voltage conversion unit converts the current at a specified sampling point into a voltage signal and sends it to the voltage detection circuit. The output end of the voltage detection circuit is connected to the control module.

[0013] As a further solution of the present invention: the input protection circuit includes:

[0014] Resistor R1, resistor R2, resistor R3, resistor R22, resistor R24, resistor R27, resistor R28, resistor R29, resistor R42, resistor R32, capacitor C8, capacitor C12, capacitor C13, capacitor C34, capacitor C35, capacitor C36, transistor Q18, transistor Q26, transistor Q38, operational amplifier A4B, operational amplifier A4D, CMOS chip 15C, CMOS chip 15D, diode D10, diode D25, photoelectric coupling device O11.

[0015] As a further solution of the present invention: the output protection circuit includes:

[0016] Resistor R5, resistor R6, resistor R7, resistor R23, resistor R30, resistor R31, resistor R33, resistor R43, resistor R32, capacitor C14, capacitor C16, capacitor C17, capacitor C37, capacitor C39, capacitor C40, transistor Q21, transistor Q41, op amp A9B, op amp A9D, CMOS chip 20C, CMOS chip 20D, diode D19.

[0017] As a further solution of the present invention: the over-temperature protection circuit includes:

[0018] Thermistor NTC1, resistor R104, resistor R105, resistor R112, resistor R113, resistor R114, resistor R115, resistor R116, resistor R119, resistor R120, capacitor C107, capacitor C108, capacitor C109, capacitor C117, capacitor C121, transistor Q112, transistor Q119, operational amplifier A106B, operational amplifier A106D, CMOS chip 111C, CMOS chip 111D, diode D110.

[0019] As a further solution of the present invention: the overcurrent protection circuit includes:

[0020] Resistor R58, resistor R60, resistor R61, resistor R63, resistor R71, resistor R76, resistor R79, resistor R84, capacitor C1, capacitor C44, capacitor C67, capacitor C81, operational amplifier A70, diode D3, diode D4, diode D59, photoelectric coupling device O1, and MOS tube N2.

[0021] As a further solution of the present invention: the control module includes a main control circuit, and the main control circuit includes a control chip U10, a capacitor C20, a capacitor C21, a capacitor C23, a capacitor C25, a capacitor C26, a capacitor C29, a resistor R21, a resistor R29, a resistor R31, a resistor R32, a resistor R33, a resistor R37 and a resistor R40.

[0022] Beneficial effects of the present invention: The present invention detects input overvoltage or undervoltage at the input and output ends of the DC conversion circuit respectively through an input protection circuit and an output protection circuit, and can also detect whether the DC conversion circuit has an over-high operating temperature or a short circuit through an over-temperature protection circuit and an over-current protection circuit, and promptly sends a stop signal to the control module of the DC conversion circuit to control the power module to stop working, thereby comprehensively improving work safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be further described below in conjunction with the accompanying drawings.

[0024] Figure 1 It is a modular schematic diagram of the protection circuit in the present invention;

[0025] Figure 2 Schematic diagram of the circuit structure of the input protection circuit in the present invention;

[0026] Figure 3 It is a circuit structure schematic diagram of the output protection circuit in the present invention;

[0027] Figure 4 Schematic diagram of the circuit structure of the over-temperature protection circuit in the present invention;

[0028] Figure 5 Schematic diagram of the circuit structure of the overcurrent protection circuit in the present invention;

[0029] Figure 6 It is a schematic diagram of the main control circuit structure of the control module in the present invention. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] See also Figure 1 As shown, the present invention is a protection circuit of a DC conversion circuit, which is connected to the DC conversion circuit, wherein the DC conversion circuit includes a control module and a power module, including an input protection circuit, an output protection circuit, an over-temperature protection circuit and an over-current protection circuit;

[0032] The sampling end of the input protection circuit is connected to the DC voltage input end of the DC conversion circuit, and the output end of the input protection circuit is connected to the control module;

[0033] The sampling end of the output protection circuit is connected to the DC voltage output end of the DC conversion circuit, and the output end of the output protection circuit is connected to the control module;

[0034] The over-temperature protection circuit comprises a temperature sampling unit and an over-temperature detection circuit, wherein the temperature sampling unit collects temperature data of the DC conversion circuit, and the output end of the over-temperature detection circuit is connected to the control module;

[0035] The overcurrent protection circuit includes a voltage conversion unit and a voltage detection circuit. The voltage conversion unit converts the current at a specified sampling point into a voltage signal and sends it to the voltage detection circuit. The output end of the voltage detection circuit is connected to the control module.

[0036] The input protection circuit and the output protection circuit can be used to detect the input overvoltage or undervoltage at the input and output ends of the DC conversion circuit respectively. The over-temperature protection circuit and the over-current protection circuit can also be used to detect whether the DC conversion circuit has an over-temperature or short-circuit condition. A stop signal can be promptly sent to the control module of the DC conversion circuit to control the power module to stop working, thereby comprehensively improving work safety.

[0037] like Figure 6 As shown, the control module includes a main control circuit, which includes a control chip U10, a capacitor C20, a capacitor C21, a capacitor C23, a capacitor C25, a capacitor C26, a capacitor C29, a resistor R21, a resistor R29, a resistor R31, a resistor R32, a resistor R33, a resistor R37 and a resistor R40.

[0038] In this embodiment of the present invention, the control chip U10 adopts the chip JUCC1895L, the main control circuit mainly receives voltage signals and current signals, etc., and sends control instructions to the drive control circuit and other circuits according to the received signals. The voltage feedback circuit collects the output voltage and monitors the output voltage. In order to ensure the high reliability and stability of the collection, the reference voltage 2.5V of the controllable precision voltage regulator TL431 is used for comparison, and the differential circuit is used for proportional amplification to ensure that the voltage collection is accurate and reliable. TP521 is used as the signal isolator U11 for signal isolation, and the result is sent to the control chip U10; the current collection circuit is responsible for converting the current into a voltage signal, and using the operational amplifier to send its voltage value to the control chip U10 to realize the current sampling function.

[0039] like Figure 2 As shown, the input protection circuit includes:

[0040] Resistor R1, resistor R2, resistor R3, resistor R22, resistor R24, resistor R27, resistor R28, resistor R29, resistor R42, resistor R32, capacitor C8, capacitor C12, capacitor C13, capacitor C34, capacitor C35, capacitor C36, transistor Q18, transistor Q26, transistor Q38, operational amplifier A4B, operational amplifier A4D, CMOS chip 15C, CMOS chip 15D, diode D10, diode D25, photoelectric coupling device O11.

[0041] Among them, 28V is the voltage sampling point, which is amplified by the difference with the TL431 reference voltage 5V, and after being judged by the voltage comparator LM139, the logic result (whether it is overvoltage) is sent to the back-end CD4011 (CMOS chip 15C and CMOS chip 15D). When it is judged as overvoltage, the transistor Q26, that is, the FMMT222 transistor is turned on, the DCDCOFF instruction takes effect and is sent to the control chip U10, and the control chip U10 issues a shutdown instruction.

[0042] like Figure 3 As shown, the output protection circuit includes:

[0043] Resistor R5, resistor R6, resistor R7, resistor R23, resistor R30, resistor R31, resistor R33, resistor R43, resistor R32, capacitor C14, capacitor C16, capacitor C17, capacitor C37, capacitor C39, capacitor C40, transistor Q21, transistor Q41, op amp A9B, op amp A9D, CMOS chip 20C, CMOS chip 20D, diode D19.

[0044] Among them, 270VFB is the voltage sampling point, which is amplified by the difference with the TL431 reference voltage 5V, and after being judged by the voltage comparator LM139, the logic result (whether it is overvoltage or undervoltage) is sent to the back-end CD4011 (CMOS chip 20C and CMOS chip 20D). When it is judged as overvoltage or undervoltage, the DCDCOFF instruction takes effect and is sent to the control chip U10, and the control chip U10 issues a shutdown instruction.

[0045] like Figure 4 As shown, the over-temperature protection circuit includes:

[0046] Thermistor NTC1, resistor R104, resistor R105, resistor R112, resistor R113, resistor R114, resistor R115, resistor R116, resistor R119, resistor R120, capacitor C107, capacitor C108, capacitor C109, capacitor C117, capacitor C121, transistor Q112, transistor Q119, operational amplifier A106B, operational amplifier A106D, CMOS chip 111C, CMOS chip 111D, diode D110;

[0047] Among them, thermistor NTC1 is used for temperature determination. When the temperature of thermistor NTC1 changes, the resistance value changes accordingly, and is amplified by the difference with the TL431 reference voltage 5V. After determination by voltage comparator LM139 (op amp A106B and op amp A106D), the logic result (whether it is over-temperature) is sent to the back-end CD4011. When it is determined to be over-temperature, the DCDCOFF instruction takes effect and is sent to the control chip U10, and the control chip U10 issues a shutdown instruction.

[0048] like Figure 5 As shown, the overcurrent protection circuit includes:

[0049] Resistor R58, resistor R60, resistor R61, resistor R63, resistor R71, resistor R76, resistor R79, resistor R84, capacitor C1, capacitor C44, capacitor C67, capacitor C81, operational amplifier A70, diode D3, diode D4, diode D59, photoelectric coupling device O1, MOS tube N2;

[0050] Among them, the current is converted into voltage through resistor R79, and it is judged by LM111 operational amplifier and standard voltage value VREF. When it is judged as overcurrent, DCDCOFF instruction takes effect and is sent to control chip U10, and control chip U10 issues a shutdown instruction.

[0051] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A protection circuit for a DC conversion circuit, connected to the DC conversion circuit, wherein the DC conversion circuit comprises a control module and a power module, It is characterized in that Including input protection circuit, output protection circuit, over-temperature protection circuit and over-current protection circuit; The sampling end of the input protection circuit is connected to the DC voltage input end of the DC conversion circuit, and the output end of the input protection circuit is connected to the control module; The sampling end of the output protection circuit is connected to the DC voltage output end of the DC conversion circuit, and the output end of the output protection circuit is connected to the control module; The over-temperature protection circuit comprises a temperature sampling unit and an over-temperature detection circuit, wherein the temperature sampling unit collects temperature data of the DC conversion circuit, and the output end of the over-temperature detection circuit is connected to the control module; The overcurrent protection circuit includes a voltage conversion unit and a voltage detection circuit, wherein the voltage conversion unit converts the current at a specified sampling point into a voltage signal and sends it to the voltage detection circuit, and the output end of the voltage detection circuit is connected to the control module; The input protection circuit comprises: Resistor R1, resistor R2, resistor R3, resistor R22, resistor R24, resistor R27, resistor R28, resistor R29, resistor R42, resistor R32, controllable precision voltage regulator TL431MGJ18, controllable precision voltage regulator TL431MGJ38, capacitor C8, capacitor C12, capacitor C13, capacitor C34, capacitor C35, capacitor C36, transistor Q26, operational amplifier A4B, operational amplifier A4D, CMOS chip 15C, CMOS chip 15D, diode D10, diode D25, photoelectric coupling device O11; Among them, one end of the resistor R1 is connected to a 28V voltage, and the other end is connected to one end of the capacitor C13 and the resistor R22 and the reference electrode of the controllable precision voltage regulator TL431MGJ18, the other end of the capacitor C13 is connected to one end of the resistor R2, the cathode of the controllable precision voltage regulator TL431MGJ18 and the in-phase input terminal of the operational amplifier A4B, the other end of the resistor R2 is connected to a 15V voltage, the inverting input terminal of the operational amplifier A4B is connected to a 7.5V voltage, one end of the resistor R3 is connected to a 15V voltage, and the other end is connected to one end of the capacitor C12 and the output terminal of the operational amplifier A4B, and the other end of the capacitor C12 is grounded; One end of the resistor R28 is connected to a 28V voltage, and the other end is connected to the capacitor C34, one end of the resistor R42, and the reference electrode of the controllable precision voltage regulator TL431MGJ38. The other end of the capacitor C34 is connected to one end of the resistor R29, the cathode of the controllable precision voltage regulator TL431MGJ38, and the inverting input end of the operational amplifier A4D. One end of the resistor R29 is connected to a 15V voltage, and the non-inverting input end of the operational amplifier A4D is connected to a 7.5V voltage. The other end of the resistor R32 is connected to a 15V voltage, and the other end is connected to one end of the capacitor C35 and the output end of the operational amplifier A4D. The other end of the capacitor C35 is grounded. The output end of the operational amplifier A4B and the output end of the operational amplifier A4D are coupled to the input side pins of the CMOS chip 15D and the CMOS chip 15C respectively, the output end of the CMOS chip 15C is coupled to the input side of the CMOS chip 15D, the output end of the CMOS chip 15D is coupled to the input side of the CMOS chip 15C and the anode of the diode D10, the cathode of the diode D10 is connected to one end of the resistor R27, the other end of the resistor R27 is connected to the base of the transistor Q26, the emitter of the transistor Q26 is grounded, the collector of the transistor Q26 is connected to one end of the resistor R24, the other end of the resistor R24 ​​is connected to the photoelectric coupling device O11, and the photoelectric coupling device O11 is coupled to the overcurrent protection circuit through the diode D25; The output protection circuit comprises: Resistor R5, resistor R6, resistor R7, resistor R23, resistor R30, resistor R31, resistor R33, resistor R43, resistor R32, capacitor C14, capacitor C16, capacitor C17, capacitor C37, capacitor C39, capacitor C40, controllable precision voltage regulator TL431MGJ21, controllable precision voltage regulator TL431MGJ41, operational amplifier A9B, operational amplifier A9D, CMOS chip 20C, CMOS chip 20D, diode D19; Among them, one end of the resistor R5 is connected to a 28V voltage, and the other end is connected to the capacitor C17 and one end of the resistor R23 and the reference electrode of the controllable precision voltage regulator TL431MGJ21, the other end of the capacitor C17 is connected to one end of the resistor R6 and the cathode of the controllable precision voltage regulator TL431MGJ21 and the in-phase input terminal of the operational amplifier A9B, the other end of the resistor R6 is connected to a 15V voltage, the inverting input terminal of the operational amplifier A9B is connected to a 7.5V voltage, one end of the resistor R7 is connected to a 15V voltage, and the other end is connected to one end of the capacitor C14 and the output terminal of the operational amplifier A9B, and the other end of the capacitor C14 is grounded; One end of the resistor R30 is connected to a 28V voltage, and the other end is connected to the capacitor C37, one end of the resistor R43, and the reference electrode of the controllable precision voltage regulator TL431MGJ41, the other end of the capacitor C37 is connected to one end of the resistor R31, the cathode of the controllable precision voltage regulator TL431MGJ41, and the inverting input terminal of the operational amplifier A9D, the other end of the resistor R31 is connected to a 15V voltage, the non-inverting input terminal of the operational amplifier A9D is connected to a 7.5V voltage, one end of the resistor R33 is connected to a 15V voltage, and the other end is connected to one end of the capacitor C39 and the output terminal of the operational amplifier A9D, and the other end of the capacitor C39 is grounded; The output end of the operational amplifier A9B and the output end of the operational amplifier A9D are coupled to the input side pins of the CMOS chip 20D and the CMOS chip 20C respectively, the output end of the CMOS chip 20C is coupled to the input side of the CMOS chip 20D, the output end of the CMOS chip 20D is coupled to the input side of the CMOS chip 20C and the anode of the diode D19, and the cathode of the diode D19 is coupled to the overcurrent protection circuit.

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