CN202888808U - A push-pull converter overcurrent protection circuit - Google Patents
A push-pull converter overcurrent protection circuit Download PDFInfo
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- CN202888808U CN202888808U CN 201220522386 CN201220522386U CN202888808U CN 202888808 U CN202888808 U CN 202888808U CN 201220522386 CN201220522386 CN 201220522386 CN 201220522386 U CN201220522386 U CN 201220522386U CN 202888808 U CN202888808 U CN 202888808U
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Abstract
The utility model relates to a push-pull converter technical field especially indicates a push-pull converter overcurrent protection circuit. The structure of the circuit comprises a push-pull circuit, a first driving circuit and a second driving circuit which are used for generating driving signals of a switching tube of the push-pull circuit, and an overcurrent detection circuit, wherein the overcurrent detection circuit blocks the corresponding driving circuit when detecting that voltage signals at two ends of the output of the switching tube of the push-pull circuit are overvoltage. Compared with the prior art: the utility model discloses need not to sample input current, need not to adopt current transformer promptly, simplified the circuit of converter, reduced the use of component, reduced the asymmetric possibility of two winding circuit of push-pull converter input side, make the difficult magnetic biasing of transformer.
Description
Technical field
The utility model relates to the push-pull converter technical field, refers to especially a kind of push-pull converter current foldback circuit.
Background technology
At present, in the following power section of uninterrupted power supply 3KVA, usually adopt push-pull converter to come battery is carried out DC converting to dc bus.And push-pull converter is very high to the symmetry requirement of two bridges about the input side, if the transformer input side winding difference of this push-pull converter is too large, or bridge cabling length in the circuit board has big difference up and down, and perhaps the driving pulsewidth of bridge switch pipe exists certain deviation all can cause this transformer to produce bias phenomenon up and down.And when magnetic bias accumulated gradually, the winding input current of magnetic bias can be increasing, the electric current that super normal operation far away can produce and cause transformer saturated, and the great input current of generation can damage other elements in the converter at this moment.
Thereby when push-pull converter primary side input current much larger than the normal operation can produce electric current the time, take certain safeguard measure be quite necessity.Deliver to comparison circuit generation guard signal to controller and adopt in some uninterrupted power supply product at present at input side adding current transformer sampling input side electric current, the way of being closed the push-pull converter driving by controller realizes this protection; This method has increased than multi-line and element, has not only increased cost, and has increased the asymmetric possibility of push-pull converter input side two winding lines, the easier transformer bias that causes.
Summary of the invention
The purpose of this utility model is to avoid above-mentioned weak point of the prior art and a kind of over-current detection circuit that can effectively protect variator when the push-pull converter overcurrent and not increase the winding asymmetry is provided.
The purpose of this utility model is achieved through the following technical solutions:
A kind of push-pull converter current foldback circuit is provided; comprise push-pull circuit; the first drive circuit and the second drive circuit for generation of the driving signal of the switching tube of push-pull circuit; also comprise over-current detection circuit, block corresponding drive circuit during the voltage signal overvoltage at switching tube output two ends that described over-current detection circuit records push-pull circuit.
Wherein, described over-current detection circuit comprises the clamped circuit that is formed by capacitor C 1 and the diode D1 that is connected in series with capacitor C 1, and described clamped circuit is consistent the voltage of the switching tube of conducting in capacitor C 1 both end voltage and the push-pull circuit; Described over-current detection circuit also comprises the switching tube Q8 by voltage control conducting or the disconnection of capacitor C 1, described switching tube output overcurrent guard signal SD.
Wherein, described capacitor C 1 is parallel with switching tube Q7, and the control end of described switching tube Q7 is connected with overcurrent protection signal SD with the control signal PWM_A of the first drive circuit, the control signal PWM_B of the second drive circuit simultaneously.
Wherein, described switching tube Q8 is triode Q8, the collector electrode output overcurrent guard signal SD of described triode Q8, and the emitter of described triode Q8 connects low level; the base stage of described triode Q8 is connected with an end of capacitor C 1, another termination low level of described capacitor C 1.
Wherein, described overcurrent protection signal SD is low level signal, described the first drive circuit comprises the switching tube Q1 by the control signal PWM_A control conduction and cut-off of the first drive circuit of outside input, comprise that also output is series at switching tube Q2 and the switching tube Q3 between high level and the low level, the output termination low level of described switching tube Q1, the control end of another output termination switching tube Q2, the anode of the control end of switching tube Q3 and diode D1, the negative electrode of described diode D1 connects overcurrent protection signal SD, and the link of described switching tube Q2 and switching tube Q3 is defeated to be the driving signal OUT_A that push-pull circuit;
Described the second drive circuit comprises the switching tube Q4 by the control signal PWM_B control conduction and cut-off of the second drive circuit of outside input; comprise that also output is series at switching tube Q5 and switching tube Q6 between high level and the low level; the output termination low level of described switching tube Q1; control end, the control end of switching tube Q6 and the anode of diode D3 of another output termination switching tube Q5; the negative electrode of described diode D3 connects overcurrent protection signal SD, the driving signal OUT_B of the link output push-pull circuit of described switching tube Q5 and switching tube Q6.
The beneficial effects of the utility model: the utility model provides a kind of push-pull converter current foldback circuit, obtain the voltage signal at switching tube two ends in the push-pull converter by over-current detection circuit, and produce the overcurrent protection signal SD of invalidating according to this voltage signal; And overcurrent protection signal SD blocks the first drive circuit effectively the time and the second drive circuit makes its switching tube that can't produce effective drive push-pull circuit, thereby the protection converter is not damaged.Compared with prior art: the utility model need not input current is sampled, namely need not to adopt current transformer, simplified the circuit of converter, reduced the use of element, reduced the asymmetric possibility of push-pull converter input side two winding lines, made transformer be difficult for magnetic bias.Greatly reduce simultaneously cost, be convenient to implement.
Description of drawings
Fig. 1 is the circuit block diagram of the embodiment of a kind of push-pull converter current foldback circuit of the utility model.
Fig. 2 is the circuit diagram of over-current detection circuit of the embodiment of a kind of push-pull converter current foldback circuit of the utility model.
Fig. 3 is first drive circuit of embodiment of a kind of push-pull converter current foldback circuit of the utility model and the circuit diagram of the second drive circuit.
Fig. 4 is the circuit diagram of push-pull circuit of the embodiment of a kind of push-pull converter current foldback circuit of the utility model.
Embodiment
With the following Examples the utility model is further described.
The embodiment of a kind of push-pull converter current foldback circuit of the utility model; as shown in Figures 1 to 4; comprise: push-pull circuit 4; the first drive circuit 2 and the second drive circuit 3 for generation of the driving signal of the switching tube of push-pull circuit 4; also comprise over-current detection circuit 1, block corresponding drive circuit during the voltage signal overvoltage at switching tube output two ends that described over-current detection circuit 1 records push-pull circuit 4.
In the circuit working process, obtain the voltage signal at switching tube two ends in the push-pull converter by over-current detection circuit 1, and produce the overcurrent protection signal SD of invalidating according to this voltage signal; And overcurrent protection signal SD blocks the first drive circuit 2 effectively the time and the second drive circuit 3 makes its switching tube that can't produce effective drive push-pull circuit 4, thereby the protection converter is not damaged.Compared with prior art: the utility model need not input current is sampled, namely need not to adopt current transformer, simplified the circuit of converter, reduced the use of element, reduced the asymmetric possibility of push-pull converter input side two winding lines, made transformer be difficult for magnetic bias.Greatly reduce simultaneously cost, be convenient to implement.
In the present embodiment, described over-current detection circuit 1 comprises the clamped circuit that is formed by capacitor C 1 and the diode D1 that is connected in series with capacitor C 1, one end of capacitor C 1 is connected with low level, the anodic bonding of the other end and diode D1, the negative electrode of described diode D1 obtains voltage signal VDS_A and the VDS_B of two switching tubes of push-pull circuit 4 simultaneously, thereby the voltage of the switching tube of conducting in capacitor C 1 both end voltage and the push-pull circuit 4 is consistent; Described over-current detection circuit 1 also comprises the switching tube Q8 by voltage control conducting or the disconnection of capacitor C 1, described switching tube output overcurrent guard signal SD.Wherein, switching tube Q8 is triode Q8, the collector electrode output overcurrent guard signal SD of described triode Q8, and the emitter of described triode Q8 connects low level; the base stage of described triode Q8 is connected with an end of capacitor C 1 through Transient Suppression Diode ZD1, another termination low level of described capacitor C 1.Further, the capacitance of described capacitor C 1 is 100PF.
In the present embodiment, described capacitor C 1 is parallel with switching tube Q7, and the control end of described switching tube Q7 is connected with overcurrent protection signal SD with the control signal PWM_A of the first drive circuit 2, the control signal PWM_B of the second drive circuit 3 simultaneously.Described switching tube Q7 is 2N7002L type switching tube.
In the present embodiment, push-pull circuit 4 comprises switching tube Q41 and switching tube Q42, described switching tube Q41 and switching tube Q42 control conducting/disconnection by driving signal OUT_A, the OUT_B of the first drive circuit 2 and 3 outputs of the second drive circuit respectively, the output termination low level of switching tube Q41, another output is output voltage signal VDS_A behind diode D41, D42 and ecological diode ZD41, the output termination low level of switching tube Q42, another output is output voltage signal VDS_B behind diode D41, D43 and ecological diode ZD42.
When push-pull converter is worked, the switching tube Q41 of push-pull circuit 4 and switching tube Q42 alternate conduction, such as Fig. 2 and shown in Figure 4, voltage on the capacitor C 1 is clamped by voltage signal VDS_A and VDS_B voltage signal, when push-pull circuit 4 primary side currents rise, the upper voltage that produces of the switching tube Q41 that it is corresponding or Q42 increases, and causes the corresponding rising of VDS_A or VDS_B, and the voltage that then obtains on the capacitor C 1 also increases; When this voltage is high enough to when making triode Q8 conducting; then drag down the SD signal; produce an effective overcurrent protection signal SD, thereby block the first drive circuit 2 and the second drive circuit 3 makes its switching tube that can't produce effective drive push-pull circuit 4 play the purpose of overcurrent protection.For example, when Q41 is open-minded, and Q42 is when turn-offing, the voltage diode D1 on the capacitor C 1, and diode D41, diode D42, transient diode ZD41, and switching tube Q41 is by clamped.Raise and surpass limit value if flow through conduction voltage drop that excessive electric current causes Q41 this moment among the Q41, then the voltage on the capacitor C 1 raises and surpasses limit value and trigger triode Q8 produces effective overcurrent protection signal SD.
In addition, during owing to push-pull circuit 4 normal operation, can there be certain Dead Time in the control signal PWM_B of the control signal PWM_A of the first drive circuit 2 and the second drive circuit 3.In being in Dead Time, the control signal PWM_A of P the first drive circuit 2 and the control signal PWM_B of the second drive circuit 3 are high level simultaneously, and when this moment over-current detection circuit 1 do not move overcurrent protection signal SD and be in high level yet.In this case, switching tube Q7 is conducting, thereby with the voltage zero clearing on the capacitor C 1.And after over-current detection circuit 1 action, overcurrent protection signal SD is dragged down, and the driving meeting of switching tube Q7 is dragged down always, thereby makes the voltage on the capacitor C 1 keep high-tension state to block drive circuit.
Described the first drive circuit 2 comprises the switching tube Q1 by the control signal PWM_A control conduction and cut-off of the first drive circuit 2 of outside input, comprise that also output is series at switching tube Q2 and the switching tube Q3 between high level and the low level, the output termination low level of described switching tube Q1, control end, the control end of switching tube Q3 and the anode of diode D1 of another output termination switching tube Q2, the negative electrode of described diode D1 connects overcurrent protection signal SD, the driving signal OUT_A of the link output push-pull circuit 4 of described switching tube Q2 and switching tube Q3;
As shown in Figure 3; described the second drive circuit 3 comprises the switching tube Q4 by the control signal PWM_B control conduction and cut-off of the second drive circuit 3 of outside input; comprise that also output is series at switching tube Q5 and switching tube Q6 between high level and the low level; the output termination low level of described switching tube Q1; the control end of another output termination switching tube Q5; the anode of the control end of switching tube Q6 and diode D3; the negative electrode of described diode D3 connects overcurrent protection signal SD, the driving signal OUT_B of the link output push-pull circuit 4 of described switching tube Q5 and switching tube Q6.
The overcurrent protection signal SD that works as input for the first drive circuit 2 is high, be that overcurrent protection signal SD is when invalid, when control signal PWM_A when low, switching tube Q1 cut-off, the control end of switching tube Q2 and switching tube Q3 obtains high level, switching tube Q2 conducting, switching tube Q3 cut-off, the driving signal of the first drive circuit 2 output high level (namely effective); When control signal PWM_B when low, switching tube Q1 conducting, the control end of switching tube Q2 and switching tube Q3 obtains low level, switching tube Q2 cut-off, switching tube Q3 conducting, the driving signal of the first drive circuit 2 output low levels (namely invalid); When overcurrent guard signal SD is high, be that overcurrent protection signal SD is when effective, no matter control signal PWM_A is high level or low level, and the control end of switching tube Q2 and switching tube Q3 all obtains low level, the driving signal of the first drive circuit 2 output low levels (namely invalid); Therefore the truth table of the first drive circuit 2 is as follows:
In like manner, can to obtain truth table as follows for the second drive circuit 3:
To sum up, over-current detection circuit 1 detect draw push away circuit and produce overcurrent and produce effective overcurrent protection signal SD after, the first drive circuit 2 and the second drive circuit 3 can effectively be blocked, the switching tube of uncertain push-pull circuit 4, protection push-pull converter.
Should be noted that at last; above embodiment is only in order to illustrate the technical solution of the utility model; but not to the restriction of the utility model protection range; although with reference to preferred embodiment the utility model has been done to explain; those of ordinary skill in the art is to be understood that; can make amendment or be equal to replacement the technical solution of the utility model, and not break away from essence and the scope of technical solutions of the utility model.
Claims (5)
1. push-pull converter current foldback circuit; comprise push-pull circuit (4); the first drive circuit (2) and the second drive circuit (3) for generation of the driving signal of the switching tube of push-pull circuit (4); it is characterized in that: also comprise over-current detection circuit (1), block corresponding drive circuit during the voltage signal overvoltage at switching tube output two ends that described over-current detection circuit (1) records push-pull circuit (4).
2. a kind of push-pull converter current foldback circuit as claimed in claim 1, it is characterized in that: described over-current detection circuit (1) comprises the clamped circuit that is formed by capacitor C 1 and the diode D1 that is connected in series with capacitor C 1, and described clamped circuit is consistent the voltage of the switching tube of conducting in capacitor C 1 both end voltage and the push-pull circuit (4); Described over-current detection circuit (1) also comprises the switching tube Q8 by voltage control conducting or the disconnection of capacitor C 1, described switching tube output overcurrent guard signal SD.
3. a kind of push-pull converter current foldback circuit as claimed in claim 2; it is characterized in that: described capacitor C 1 is parallel with switching tube Q7, and the control end of described switching tube Q7 is connected with overcurrent protection signal SD with the control signal PWM_A of the first drive circuit (2), the control signal PWM_B of the second drive circuit (3) simultaneously.
4. a kind of push-pull converter current foldback circuit as claimed in claim 2; it is characterized in that: described switching tube Q8 is triode Q8; the collector electrode output overcurrent guard signal SD of described triode Q8; the emitter of described triode Q8 connects low level; the base stage of described triode Q8 is connected with an end of capacitor C 1, another termination low level of described capacitor C 1.
5. a kind of push-pull converter current foldback circuit as claimed in claim 2, it is characterized in that: described overcurrent protection signal SD is low level signal, described the first drive circuit (2) comprises the switching tube Q1 by the control signal PWM_A control conduction and cut-off of first drive circuit (2) of outside input, comprise that also output is series at switching tube Q2 and the switching tube Q3 between high level and the low level, the output termination low level of described switching tube Q1, the control end of another output termination switching tube Q2, the anode of the control end of switching tube Q3 and diode D1, the negative electrode of described diode D1 connects overcurrent protection signal SD, the driving signal OUT_A of the link output push-pull circuit (4) of described switching tube Q2 and switching tube Q3;
Described the second drive circuit (3) comprises the switching tube Q4 by the control signal PWM_B control conduction and cut-off of second drive circuit (3) of outside input; comprise that also output is series at switching tube Q5 and switching tube Q6 between high level and the low level; the output termination low level of described switching tube Q1; the control end of another output termination switching tube Q5; the anode of the control end of switching tube Q6 and diode D3; the negative electrode of described diode D3 connects overcurrent protection signal SD, the driving signal OUT_B of the link output push-pull circuit (4) of described switching tube Q5 and switching tube Q6.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220522386 CN202888808U (en) | 2012-10-12 | 2012-10-12 | A push-pull converter overcurrent protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220522386 CN202888808U (en) | 2012-10-12 | 2012-10-12 | A push-pull converter overcurrent protection circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN202888808U true CN202888808U (en) | 2013-04-17 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201220522386 Expired - Lifetime CN202888808U (en) | 2012-10-12 | 2012-10-12 | A push-pull converter overcurrent protection circuit |
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| Country | Link |
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| CN (1) | CN202888808U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102868143A (en) * | 2012-10-12 | 2013-01-09 | 广东易事特电源股份有限公司 | Overcurrent protection circuit of push-pull converter |
| CN107658853A (en) * | 2017-09-12 | 2018-02-02 | 嘉善中正新能源科技有限公司 | BOOST coordinates the current foldback circuit of PUSH PULL cascade circuits |
-
2012
- 2012-10-12 CN CN 201220522386 patent/CN202888808U/en not_active Expired - Lifetime
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102868143A (en) * | 2012-10-12 | 2013-01-09 | 广东易事特电源股份有限公司 | Overcurrent protection circuit of push-pull converter |
| CN102868143B (en) * | 2012-10-12 | 2015-10-21 | 广东易事特电源股份有限公司 | A kind of overcurrent protection circuit of push-pull converter |
| CN107658853A (en) * | 2017-09-12 | 2018-02-02 | 嘉善中正新能源科技有限公司 | BOOST coordinates the current foldback circuit of PUSH PULL cascade circuits |
| CN107658853B (en) * | 2017-09-12 | 2019-03-15 | 嘉善中正新能源科技有限公司 | The current foldback circuit of BOOST cooperation PUSH-PULL cascade circuit |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| AV01 | Patent right actively abandoned |
Granted publication date: 20130417 Effective date of abandoning: 20151021 |
|
| AV01 | Patent right actively abandoned |
Granted publication date: 20130417 Effective date of abandoning: 20151021 |
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| C25 | Abandonment of patent right or utility model to avoid double patenting |