CN203826929U - A switch power supply protection circuit - Google Patents
A switch power supply protection circuit Download PDFInfo
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- CN203826929U CN203826929U CN201420221255.6U CN201420221255U CN203826929U CN 203826929 U CN203826929 U CN 203826929U CN 201420221255 U CN201420221255 U CN 201420221255U CN 203826929 U CN203826929 U CN 203826929U
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Abstract
A switch power supply protection circuit described by the utility model comprises an input filter circuit, a power converting circuit, a high-frequency transformer, an output rectification circuit, an output filter circuit, a driving control circuit, an output feedback control circuit and an over-current protection circuit. The output filter circuit comprises an output filter inductor. The over-current protection circuit comprises a current conditioning circuit and an output current sampling circuit. According to the switch power supply protection circuit described by the utility model, the output current sampling circuit and the current conditioning circuit are added to the circuit; the sampling circuit is almost free from power consumption, so that a certain condition is created for raising efficiency of a power supply ; output efficiency of the switch power supply is raised; line losses of the circuit are reduced; and anti-interference capability is improved.
Description
Technical field
The utility model relates to switching power circuit field, is specifically related to a kind of protective circuit of switch power source.
Background technology
Protective circuit of switch power source is the important component part in switch power supply system.Its effect is when Switching Power Supply is in system debug or use procedure, and the power component in can protection switch power supply and other circuit working of system are in safety zone.Switching Power Supply current foldback circuit is one of core cell of protective circuit of switch power source.When the output institute bringing onto load of power supply surpasses nominal load, can cause damage to power supply, the power component that current foldback circuit can effective guarantee switch power supply system and system power supply circuit working are in safety zone.
The form of overcurrent protection has a variety of, mainly can be divided into two large classes: a class is cut-off type overcurrent protection, and a class is automatically to recover type overcurrent protection.In certain applications and design, adopt cut-off type overcurrent protection mode, the reliability of power supply has improved like this, but occurs to need manually to reset after overcurrent at every turn, and this uses for user can be not too convenient.So, generally adopt automatic recovery type more.At present; automatically the overcurrent protection of recovery type mainly adopts the sagging type current foldback circuit of rated current; this current foldback circuit is mainly in output current loop, to access sample resistance; and then this current sampling signal is processed with over-current signal; the shortcoming of this current protecting circuit is mainly the existence of sample resistance; reduced the efficiency of power supply, especially, the in the situation that of High-current output, ohmically power consumption can obviously increase.Therefore, consider power consumption, should avoid the access of sample resistance as far as possible.
Utility model content
The technical problems to be solved in the utility model is to provide a kind of protective circuit of switch power source, has changed the structure of original current foldback circuit, and this circuit has not only improved Switching Power Supply delivery efficiency, reduced the line loss of circuit, and antijamming capability is strong.
For solving the problems of the technologies described above, the utility model by the following technical solutions:
A kind of protective circuit of switch power source, comprise input filter circuit, circuit for power conversion, high frequency transformer, output rectification circuit, output filter circuit, Drive and Control Circuit, output feedback control circuit, current foldback circuit, described output filter circuit comprises output inductor, and described current foldback circuit comprises current regulating circuit and output current sample circuit; Described input filter circuit is connected with the output of described Drive and Control Circuit, the input of described high frequency transformer respectively via described circuit for power conversion; The input of described Drive and Control Circuit is connected with the output of the output of described input filter circuit, described output feedback control circuit; The output of described high frequency transformer is connected with power source loads via described output rectification circuit, output filter circuit; The output of described output filter circuit is connected with the input of output current sample circuit, the input of described output feedback control circuit is connected with the output of current regulating circuit, the output of output filter circuit, and the input of described current regulating circuit is connected with the output of described output current sample circuit.
Described output current sample circuit is comprised of sample coil and resistance, described sample coil and output inductor and be wound on same magnetic core, the Same Name of Ends of sample coil is connected with the Same Name of Ends of output inductor, and the different name end of sample coil is connected with output inductor different name end by resistance.
Described current regulating circuit comprises the amplifying circuit consisting of amplifier, the comparison circuit consisting of comparator; The in-phase input end of described amplifier is connected with the different name end of sample coil, and the output of described comparator is connected with output feedback control circuit.
The beneficial effects of the utility model are: 1, in circuit, increased output current sample circuit and current regulating circuit, this sample circuit almost can be accomplished no power waste, this has created certain condition for power-efficient improves, not only improved Switching Power Supply delivery efficiency, reduced the line loss of circuit, and antijamming capability is strong.2, sample coil is on output inductor, and both are wound on same magnetic core, and sample circuit device is less, implements more convenient.3, in-55 ℃～+ 125 ℃ temperature ranges, work, can reach when power source loads surpasses 1.4 times of nominal load, effectively carry out overcurrent protection; Product integrated level is high, good reliability.
Accompanying drawing explanation
Fig. 1 is circuit block diagram of the present utility model;
Fig. 2 is output current sample circuit of the present utility model;
Fig. 3 is current regulating circuit of the present utility model.
Embodiment
Below in conjunction with accompanying drawing, the utility model will be further described.
As shown in Figure 1, a kind of protective circuit of switch power source is comprised of input filter circuit 1, circuit for power conversion 2, high frequency transformer 3, output rectification circuit 4, output filter circuit 5, output feedback control circuit 8, Drive and Control Circuit 7, current foldback circuit.Current foldback circuit comprises current regulating circuit 9 and output current sample circuit 10; Input filter circuit 1 is connected with the output of Drive and Control Circuit 7, the input of high frequency transformer 3 respectively via circuit for power conversion 2; The input of Drive and Control Circuit 7 is connected with the output of input filter circuit 1, the output of output feedback control circuit 8; The output of high frequency transformer is connected with power source loads 6 via output rectification circuit 4, output filter circuit 5; The output of output filter circuit 5 is connected with the input of output current sample circuit 10, the output of the output input of feedback control circuit 8 and the output of current regulating circuit 9, output filter circuit 5 is connected, and the input of current regulating circuit 9 is connected with the output of output current sample circuit 10.
The direct voltage of input is through input filter circuit 1, the operating voltage of Drive and Control Circuit 7 is provided by accessory power supply, Drive and Control Circuit 7 produces the driving signal of power switch pipe in circuit for power conversion 2, through high frequency transformer 3 isolation, coupling, output obtains needed direct voltage through output rectification circuit 4 and output filter circuit 5.In order to realize the stable of output voltage, output feedback control circuit 8 adopts output voltage direct sample, after the comparison with reference voltage, amplification and isolation feedback, go to control the duty ratio of pulse width modulator in Drive and Control Circuit 7, thereby realize the closed-loop control of output voltage.The output current of power supply arrives output feedback control circuit 8 through output current sample circuit 10 and through current regulating circuit 9 output voltage signals, finally controls the voltage at power source loads 6 two ends.
As shown in Figure 2, output current sample circuit is comprised of sample coil L2 and resistance R; Sample coil L2 and output inductor L1 and be wound on same magnetic core, the Same Name of Ends of sample coil L2 is connected with the Same Name of Ends of output inductor L1, and the different name end of sample coil L2 is connected with output inductor L1 by resistance R.In dotted line frame, be output current sample circuit 10, L1 is the output inductor in output filter circuit 5.A point voltage is the reference ground of output voltage, and B point voltage is the equivalent resistance and the product that flows through the electric current of output inductor of output inductor L1.B point voltage signal is exactly the output signal of output current sample circuit 10, and current regulating circuit 9 receives the output current sampled signal of output current sample circuit 10.
As shown in Figure 3, current regulating circuit comprises the amplifying circuit 11 consisting of amplifier U1, the comparison circuit 12 consisting of comparator U2; The in-phase input end of amplifier U1 is connected with the different name end of sample coil L2, and the output of comparator U2 is connected with output feedback control circuit.The output voltage signal of output current sample circuit 10 need to carry out signal amplification through the amplifying circuit 11 in current regulating circuit 9, and the output signal of amplifying circuit 11 is sent into the comparator forward end of comparison circuit 12 and compared with the reference signal of the comparator backward end of comparison circuit 12.When the output signal voltage of amplifying circuit 11 is greater than the reference signal voltage of comparator backward end of comparison circuit 12, comparison circuit 12 output high level, i.e. current regulating circuit 9 output high level; Otherwise, current regulating circuit 9 output low levels.Here, the conductor material of output inductor L1 is soft copper, and the temperature coefficient of copper is larger, and therefore, in the constant situation of power source loads 6, the output signal voltage signal variation with temperature of amplifying circuit 11 and changing, is totally positive temperature characterisitic.So the signal voltage of the comparator backward end of comparison circuit 12 is variation with temperature and changing also, variation characteristic is consistent with the output signal voltage signal variation with temperature characteristic of amplifying circuit 11.
Current regulating circuit 9 receives the output signal of output current sample circuit 10, and this signal is exported to feedback control circuit 8 through sending into after conditioning, and then controls the driving signal output of Drive and Control Circuit 7.When there is not overload in power source loads 6, current regulating circuit 9 output low levels.The output signal of current regulating circuit 9 is inoperative to output feedback control circuit 8, and Drive and Control Circuit 7 is normally worked, the output voltage stabilization at power source loads 6 two ends.When there is larger overload in power source loads 6, reach the mistake flow point that Switching Power Supply arranges, current regulating circuit 9 output high level, make the driving signal of Drive and Control Circuit 7 stop output by output feedback control circuit 8, finally make the voltage drop at power source loads 6 two ends.
The utility model is mainly to utilize the equivalent resistance of the output inductor L1 in output filter circuit 5 and the specific rule between output current to carry out sample of signal, its advantage is that sample circuit almost can be accomplished no power waste, this has created certain condition for power-efficient improves, improved Switching Power Supply delivery efficiency, the line loss that has reduced circuit, antijamming capability is strong.Sample coil L2 is upper around output inductor L1, and both are wound on same magnetic core, and sample circuit device is less, and it is convenient to implement.In addition, 9, current regulating circuit need to solve temperature characterisitic and the matching problem thereof of reference signal voltage of the comparator backward end of comparison circuit 12, just can obtain good over-flow protecting effect.In-55 ℃～+ 125 ℃ temperature ranges, work, can reach when power source loads 6 surpasses 1.4 times of nominal load, effectively carry out overcurrent protection, and product integrated level is high, good reliability.
Claims (3)
1. a protective circuit of switch power source, comprise input filter circuit, circuit for power conversion, high frequency transformer, output rectification circuit, output filter circuit, Drive and Control Circuit, output feedback control circuit, current foldback circuit, described output filter circuit comprises output inductor (L1), it is characterized in that: described current foldback circuit comprises current regulating circuit and output current sample circuit; Described input filter circuit is connected with the output of described Drive and Control Circuit, the input of described high frequency transformer respectively via described circuit for power conversion; The input of described Drive and Control Circuit is connected with the output of the output of described input filter circuit, described output feedback control circuit; The output of described high frequency transformer is connected with power source loads via described output rectification circuit, output filter circuit; The output of described output filter circuit is connected with the input of output current sample circuit, the input of described output feedback control circuit is connected with the output of current regulating circuit, the output of output filter circuit, and the input of described current regulating circuit is connected with the output of described output current sample circuit.
2. a kind of protective circuit of switch power source according to claim 1, is characterized in that: described output current sample circuit is comprised of sample coil (L2) and resistance (R); Described sample coil (L2) and output inductor (L1) and be wound on same magnetic core, the Same Name of Ends of sample coil (L2) is connected with the Same Name of Ends of output inductor (L1), and the different name end of sample coil (L2) is connected with the different name end of output inductor (L1) by resistance (R).
3. a kind of protective circuit of switch power source according to claim 1, is characterized in that: described current regulating circuit comprises the amplifying circuit (11) consisting of amplifier (U1), the comparison circuit (12) consisting of comparator (U2); The in-phase input end of described amplifier (U1) is connected with the different name end of sample coil (L2), and the output of described comparator (U2) is connected with output feedback control circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420221255.6U CN203826929U (en) | 2014-05-04 | 2014-05-04 | A switch power supply protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420221255.6U CN203826929U (en) | 2014-05-04 | 2014-05-04 | A switch power supply protection circuit |
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| Publication Number | Publication Date |
|---|---|
| CN203826929U true CN203826929U (en) | 2014-09-10 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201420221255.6U Expired - Fee Related CN203826929U (en) | 2014-05-04 | 2014-05-04 | A switch power supply protection circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103944147A (en) * | 2014-05-04 | 2014-07-23 | 中国电子科技集团公司第四十三研究所 | Switching power protection circuit and control method thereof |
-
2014
- 2014-05-04 CN CN201420221255.6U patent/CN203826929U/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103944147A (en) * | 2014-05-04 | 2014-07-23 | 中国电子科技集团公司第四十三研究所 | Switching power protection circuit and control method thereof |
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| Date | Code | Title | Description |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20140910 Termination date: 20170504 |
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| CF01 | Termination of patent right due to non-payment of annual fee |