CN113036723A - DC-DC converter and overcurrent protection circuit thereof - Google Patents
DC-DC converter and overcurrent protection circuit thereof Download PDFInfo
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- CN113036723A CN113036723A CN202110341022.4A CN202110341022A CN113036723A CN 113036723 A CN113036723 A CN 113036723A CN 202110341022 A CN202110341022 A CN 202110341022A CN 113036723 A CN113036723 A CN 113036723A
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- triode
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- 238000005070 sampling Methods 0.000 claims description 24
- 239000003990 capacitor Substances 0.000 claims description 13
- 230000003321 amplification Effects 0.000 claims description 8
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 8
- 230000000087 stabilizing effect Effects 0.000 claims description 3
- 238000010586 diagram Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000002159 abnormal effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
- H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
- H02H7/1213—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for DC-DC converters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/14—Arrangements for reducing ripples from dc input or output
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
- Emergency Protection Circuit Devices (AREA)
Abstract
The invention relates to a DC-DC converter and an overcurrent protection circuit thereof, belonging to the technical field of low-voltage power distribution networks and power electronics. The overcurrent protection circuit can accurately detect the change condition of the load current, controls the conduction of the first triode under the condition of overcurrent of the load current, leads the second triode to be conducted after the collector of the first triode is conducted and VCC is loaded to the base of the first triode through the collector of the second triode to form self-locking, thereby ensuring that the power supply of the DC-DC converter can be safely and stably cut off during overcurrent. The invention realizes overcurrent protection through the driving and self-locking circuit formed by the two triodes, and has low cost and strong anti-interference capability.
Description
Technical Field
The invention relates to a DC-DC converter and an overcurrent protection circuit thereof, belonging to the technical field of low-voltage power distribution networks and power electronics.
Background
In recent years, with rapid development of power electronics and electronic technology, DC-DC converters are widely used in the fields of computers, communications, industrial automation, electronics, electrical instruments, and the like. In a DC-DC converter, a high-power MOSFET has a new breakthrough in technology and application, has lower voltage drop and higher switching speed, and is widely applied by virtue of excellent high-frequency switching characteristics, but the MOSFET has weaker capacity of bearing short-time overload, and the generated power can be increased sharply under the abnormal conditions of power supply short circuit, internal short circuit and the like, so that the normal operation of the MOSFET is influenced, and permanent damage can be caused to the MOSFET. An overcurrent protection circuit is therefore usually required within the DC-DC converter in order to protect the MOSFET switching tubes. At present, some reported overcurrent protection circuits suitable for the DC-DC converter cannot give good consideration to aspects of circuit structure cost, current limiting precision, power consumption and interference resistance. How to design a reliable and reasonable overcurrent protection circuit plays a crucial role in giving full play to the advantages of the MOSFET switch tube and avoiding the weakness thereof, and is also the premise and the key for effectively utilizing the MOSFET switch tube.
Disclosure of Invention
The invention aims to provide a DC-DC converter and an overcurrent protection circuit thereof, and aims to solve the problem that the cost and the anti-interference capability of the overcurrent protection circuit of the existing DC-DC converter cannot be considered at the same time.
The present invention provides an overcurrent protection circuit for a DC-DC converter, which includes:
the sampling protection circuit comprises a sampling resistor which is connected in series on a loop of the DC-DC converter for supplying power to a load so as to detect the current change on the load;
the signal amplification circuit comprises an operational amplifier, wherein the input end of the operational amplifier is connected with the output end of the sampling protection circuit and is used for amplifying the sampling signal;
the voltage comparison circuit comprises a comparator, one input end of the comparator is connected with the output end of the operational amplifier, the other input end of the comparator is connected with reference voltage, and the output end of the comparator is connected with a pull-up resistor;
the driving and self-locking circuit comprises a first triode and a second triode, wherein the base of the first triode is connected with the output end of the comparator, the emitting electrode of the first triode is grounded, the collecting electrode of the first triode is connected with the base of the second triode, the emitting electrode of the second triode is connected with the power supply, the collecting electrode of the second triode is connected to the base electrode of the first triode through a resistor, the collecting electrode of the second triode is grounded through a relay coil, and the contact of the relay is used for being arranged between the DC-DC converter and the load.
The overcurrent protection circuit can accurately detect the change condition of the load current, controls the conduction of the first triode under the condition of overcurrent of the load current, leads the second triode to be conducted after the collector of the first triode is conducted and VCC is loaded to the base of the first triode through the collector of the second triode to form self-locking, thereby ensuring that the power supply of the DC-DC converter can be safely and stably cut off during overcurrent. The invention realizes overcurrent protection through the driving and self-locking circuit formed by the two triodes, and has low cost and strong anti-interference capability.
Furthermore, in order to prevent the operational amplifier from being damaged by the overhigh voltage, the sampling protection circuit further comprises a voltage stabilizing diode which is used for stabilizing the voltage of the voltage sampling signal.
Furthermore, the operational amplifier comprises a non-inverting input end and an inverting input end, the non-inverting input end is connected with the output end of the sampling protection circuit, and the inverting input section is connected to the output end of the operational amplifier through the adjustable resistance module.
Furthermore, two ends of the relay coil are connected in parallel with an anti-reverse diode.
The invention also provides a DC-DC converter, which comprises a DC power supply, an input filter circuit, a bridge converter, an output filter circuit and an overcurrent protection circuit, wherein the DC power supply, the input filter circuit, the bridge converter and the output filter circuit are sequentially connected.
Further, in order to realize current-limiting protection of the DC-DC converter, the DC-DC converter further comprises a current-limiting unit, and the current-limiting unit comprises a contactor and a current-limiting resistor.
Further, the input filter circuit is an input filter capacitor.
Furthermore, the output filter circuit is an LC filter circuit, which includes a filter inductor and an output filter capacitor, and is disposed between the bridge converter and the load.
Further, the bridge converter is a half-bridge converter.
Drawings
FIG. 1 is a schematic diagram of the DC-DC converter of the present invention;
FIG. 2 is a circuit diagram of the over-current protection of the DC-DC converter of the present invention;
1 is a direct current power supply; 2 is a current limiting unit; 3 is a contactor; 4 is a current limiting resistor; 5 is an input filter capacitor; 6 is a half-bridge converter; 7 is a first IGBT; 8 is a second IGBT; 9 is a filter inductor; 10 is an output filter capacitor; 11 is a resistance load; 12 is a load RL; 13 is a first resistor; 14 is a sampling resistor; 15 is a voltage regulator diode; 16 is a first capacitor; 17 is a sampling protection circuit; 18 is an operational amplifier; 19 is a second resistor; 20 is a sliding resistor; 21 is a signal amplifying circuit; 22 is a third resistor; 23 is a pull-up resistor; 24 is a fourth resistor; 25 is a comparator; 26 is a voltage comparison circuit; 27 is a fifth resistor; 28 is a sixth resistor; 29 is a seventh resistor; 30 a second triode; 31 is a first triode; 32 is a diode; 33 is a driving and self-locking circuit.
Detailed Description
The following further describes embodiments of the present invention with reference to the drawings.
Embodiments of the DC-DC converter
The DC-DC converter of the invention is shown in figure 1, and comprises a direct current power supply 1, a current limiting unit 2, an input filter capacitor 5, a half-bridge converter 6, a filter inductor 9 and an output filter capacitor 10, wherein the current limiting unit 2 comprises a contactor 3 and a current limiting resistor 4 which are connected in parallel, the power supply is connected to the half-bridge converter 6 through the current limiting unit 2, and the input filter capacitor 5 is arranged between the current limiting unit 2 and the half-bridge converter 6 and used for filtering the power supply; the half-bridge converter comprises a first IGBT 7 and a second IGBT 8, the first IGBT 7 and the second IGBT 8 form a half-bridge structure to convert the voltage of a power supply, and the output end of the half-bridge converter is connected with a resistive load 11 through a filter inductor 9 and an output filter capacitor 10 to supply power for the resistive load 11.
The DC-DC converter can realize voltage conversion of a power supply through the circuit structure, and is also provided with an overcurrent protection circuit in order to realize overcurrent protection of the DC-DC converter. As shown in fig. 2, the overcurrent protection circuit includes a sampling protection circuit 17, a signal amplification circuit 21, a voltage comparison circuit 26, and a driving and self-locking circuit.
As shown in fig. 2, the sampling protection circuit 17 includes a sampling resistor 14 (resistor R10) connected in series to a power supply loop of a load RL 12, the load RL is a load supplied by the DC-DC converter and is located at a position equivalent to the resistive load 11, a serial connection point of the load RL and the load R10 is connected to the signal amplification circuit through a first resistor 13 (resistor R9), in order to prevent the signal amplification circuit from being damaged by overvoltage, a zener diode 15 (diode D2) is further provided, and a first capacitor 16 (capacitor C1) is further connected in parallel to two ends of the zener diode 15; diode D2 can play the guard action, and the input of protection operational amplifier prevents that too high voltage from coming into and damaging the operational amplifier, and electric capacity C1 plays anti-jamming effect. The load RL and the load R10 are connected in series, and according to the principle that the series currents are equal, the current flowing through the sampling resistor R10 and the current of the load RL are equal, that is, the change of the voltage on the R10 reflects the change of the load current, so that the voltage on the sampling resistor R10 is used for representing the change of the load RL current.
The signal amplifying circuit 21 comprises an operational amplifier 18 (operational amplifier U1A), wherein the non-inverting input end of the operational amplifier 18 is connected with the output end of the sampling protection circuit and is used for amplifying the voltage signal on the resistor R10; the inverting input terminal of the operational amplifier 18 is grounded through the second resistor 19 (resistor R7), and the connection point of the inverting input terminal of the operational amplifier and the resistor R7 is connected to the output terminal of the operational amplifier through the sliding resistor 20 (resistor R2), and the operational amplifier and the resistors R2 and R7 constitute a typical in-phase amplifying circuit, and the amplification factor is determined by R2 and R7.
The voltage comparison circuit 26 includes a comparator 25(U1B), a non-inverting input terminal of the comparator 25 is connected to an output terminal of the operational amplifier, an inverting input terminal of the comparator is connected to a reference voltage, and an output terminal of the comparator is connected to a pull-up resistor 23 (resistor R5); the reference voltage is provided by a voltage dividing circuit including a third resistor 22 (resistor R3) and a fourth resistor 24 (resistor R6) connected in series between the power supply and ground, and the connection point of the resistor R3 and the resistor R6 is connected to the inverting input terminal of the comparator. When the voltage at the non-inverting terminal is greater than the voltage at the inverting terminal, the comparator U1B outputs a high indicating that the circuit has over-current.
The driving and self-locking circuit 33 comprises a first triode 31 (triode Q2) and a second triode 30 (triode Q1), wherein the triode Q2 is NPN type, the triode Q1 is PNP type, the base of the triode Q2 is connected with the output end of the comparator through a seventh resistor 29 (resistor R8), the emitter of the triode Q2 is grounded, the collector of the triode Q2 is connected with the base of the triode Q1 through a fifth resistor 27 (resistor R1), the emitter of the triode Q1 is connected with the power supply Vcc, the collector of the triode Q1 is connected with the base of the triode Q2 through a sixth resistor 28 (resistor R4), the collector of the triode Q1 is also grounded through a relay coil, the normally closed contact of the relay is used for connecting in the power supply loop of the DC-DC converter, wherein the ports AC + and AC-are connected in series between the filter inductor 9 and the load 11, as shown in fig. 1, K1 is a normally closed contact, when the DC-DC converter is in overcurrent, the normally closed contact is opened, and an open circuit is formed between 9 and 11. In addition, a diode 32 (diode D1) is connected in parallel to two ends of the relay coil for preventing reverse connection. When the comparator outputs high level, the triode Q2 is conducted, after the Q2 is conducted, the collector of the Q2 becomes low level to conduct the triode Q1, after the Q1 is conducted, VCC is loaded to the base of the triode Q2 through the triode Q1 and the resistor R4 to form a self-locking function, so that the Q1 and the Q2 are conducted even if the output of the comparator becomes low level; when the Q1 is switched on, the current flows through the coil of the relay, the relay is closed, and the power supply input is cut off when the relay is closed.
The operation process of the DC-DC converter is as follows: the sampling protection circuit acquires a voltage signal representing load current in the DC-DC converter, the voltage signal reaches the driving and self-locking circuit through the signal amplification circuit and the voltage comparison circuit, when the DC-DC converter is in overcurrent, the voltage comparison circuit outputs high level to enable the triode Q2 to be conducted, after the Q2 is conducted, the collector of the Q2 is changed into low level to enable the triode Q1 to be conducted, after the Q1 is conducted, VCC is loaded to the base of the triode Q2 through the triode Q1 and the resistor R4 to form self-locking, and after the output of the comparator is changed into low level, the Q1 and the Q2 are still conducted; after the Q1 is conducted, current flows through a coil of the relay, the relay is closed, the power supply input is cut off when the relay is closed, and overcurrent protection of the DC-DC converter is achieved.
Embodiments of the overcurrent protection Circuit
The invention relates to an overcurrent protection circuit. As shown in fig. 2, the circuit includes a sampling protection circuit, a signal amplification circuit 21, a voltage comparison circuit, and a driving and self-locking circuit, and the specific results and operation principle of the circuit have been explained in detail in the embodiment of the DC-DC converter, and are not described herein again.
Claims (9)
1. An overcurrent protection circuit of a DC-DC converter, the overcurrent protection circuit comprising:
the sampling protection circuit comprises a sampling resistor which is connected in series on a loop of the DC-DC converter for supplying power to a load so as to detect the current change on the load;
the signal amplification circuit comprises an operational amplifier, wherein the input end of the operational amplifier is connected with the output end of the sampling protection circuit and is used for amplifying the sampling signal;
the voltage comparison circuit comprises a comparator, one input end of the comparator is connected with the output end of the operational amplifier, the other input end of the comparator is connected with reference voltage, and the output end of the comparator is connected with a pull-up resistor;
the driving and self-locking circuit comprises a first triode and a second triode, wherein the base of the first triode is connected with the output end of the comparator, the emitting electrode of the first triode is grounded, the collecting electrode of the first triode is connected with the base of the second triode, the emitting electrode of the second triode is connected with the power supply, the collecting electrode of the second triode is connected to the base electrode of the first triode through a resistor, the collecting electrode of the second triode is grounded through a relay coil, and the contact of the relay is used for being arranged between the DC-DC converter and the load.
2. The overcurrent protection circuit of claim 1, wherein the sampling protection circuit further comprises a zener diode for stabilizing the voltage sampling signal.
3. The overcurrent protection circuit of claim 1, wherein the operational amplifier comprises a non-inverting input and an inverting input, the non-inverting input is connected to the output of the sampling protection circuit, and the inverting input is connected to the output of the operational amplifier via the adjustable resistor module.
4. The overcurrent protection circuit of a DC-DC converter according to claim 1, wherein an anti-reverse diode is connected in parallel to both ends of the relay coil.
5. A DC-DC converter comprises a DC power supply, an input filter circuit, a bridge converter and an output filter circuit which are connected in sequence, and is characterized by further comprising an overcurrent protection circuit, wherein the overcurrent protection circuit is the overcurrent protection circuit in any one of claims 1 to 4.
6. The DC-DC converter according to claim 5, further comprising a current limiting unit including a contactor and a current limiting resistor.
7. The DC-DC converter according to claim 5, wherein the input filter circuit is an input filter capacitor.
8. The DC-DC converter of claim 5, wherein the output filter circuit is an LC filter circuit including a filter inductor and an output filter capacitor disposed between the bridge converter and the load.
9. The DC-DC converter of claim 5, wherein the bridge converter is a half-bridge converter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110341022.4A CN113036723A (en) | 2021-03-30 | 2021-03-30 | DC-DC converter and overcurrent protection circuit thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110341022.4A CN113036723A (en) | 2021-03-30 | 2021-03-30 | DC-DC converter and overcurrent protection circuit thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN113036723A true CN113036723A (en) | 2021-06-25 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110341022.4A Pending CN113036723A (en) | 2021-03-30 | 2021-03-30 | DC-DC converter and overcurrent protection circuit thereof |
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| Country | Link |
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| CN (1) | CN113036723A (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101697458A (en) * | 2009-10-26 | 2010-04-21 | 株洲南车时代电气股份有限公司 | Three-phase auxiliary inverter |
| CN105337328A (en) * | 2014-08-08 | 2016-02-17 | 国家电网公司 | Charging circuit and system for rechargeable battery |
| CN108512423A (en) * | 2018-05-23 | 2018-09-07 | 威腾电气集团股份有限公司 | A kind of vehicle-mounted DCDC power supplys of high-efficiency high-power |
| CN108808620A (en) * | 2018-06-29 | 2018-11-13 | 徐州凯思特机电科技有限公司 | A kind of current foldback circuit with self-locking function |
-
2021
- 2021-03-30 CN CN202110341022.4A patent/CN113036723A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101697458A (en) * | 2009-10-26 | 2010-04-21 | 株洲南车时代电气股份有限公司 | Three-phase auxiliary inverter |
| CN105337328A (en) * | 2014-08-08 | 2016-02-17 | 国家电网公司 | Charging circuit and system for rechargeable battery |
| CN108512423A (en) * | 2018-05-23 | 2018-09-07 | 威腾电气集团股份有限公司 | A kind of vehicle-mounted DCDC power supplys of high-efficiency high-power |
| CN108808620A (en) * | 2018-06-29 | 2018-11-13 | 徐州凯思特机电科技有限公司 | A kind of current foldback circuit with self-locking function |
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Application publication date: 20210625 |