CN204651910U

CN204651910U - A kind of short-circuit protection circuit

Info

Publication number: CN204651910U
Application number: CN201520411900.5U
Authority: CN
Inventors: 林森
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-06-15
Filing date: 2015-06-15
Publication date: 2015-09-16
Anticipated expiration: 2025-06-15

Abstract

The utility model discloses a kind of short-circuit protection circuit; comprise transformer T, rectifier bridge Q, diode D3, diode D4, potentiometer RP1, comparator U1 and comparator U2; transformer T coil L1 is serially connected in the collector circuit of IGBT; transformer T coil L2 two ends connect rectifier bridge Q pin 1 respectively and rectifier bridge Q pin 3, rectifier bridge Q pin 2 connects diode D3 positive pole, electric capacity C1, resistance R2 and resistance R3 respectively.The utility model short-circuit protection circuit can realize soft switching when short circuit to IGBT pipe, and fail safe is high, and circuit structure is simple, is applicable to very much promoting the use of.

Description

A kind of short-circuit protection circuit

Technical field

The utility model relates to a kind of protective circuit, specifically a kind of short-circuit protection circuit.

Background technology

Because power-converting device is all operated in high-power environment, overcurrent and short circuit are inevitable, work safely and reliably in order to ensure power-converting device, effective current protection design is necessary, modern electric converting means all adopts high-power semiconductor switch device, the current overload ability that it can bear is much lower relative to rotation convertor assembly, the overload current of tens even several μ s of μ s can only be born as IGBT, once short circuit occur just require protective circuit can within the time short as far as possible shutdown switch device, cutting-off of short-circuit electric current, switching device is unlikely damage because of overcurrent.But, rapid shutdown switch device in a short-circuit situation, produces excessive di/dt by causing load current to decline too fast, due to the existence of lead-in inductance and leakage inductance, excessive di/dt will produce very high overvoltage, and makes switching device face the danger of over-voltage breakdown.For IGBT, too high voltage may cause again device inside generation latching effect out of control and damage device.Therefore, must consider and design power-converting device short-circuit protection, to guarantee the validity of current protection.

Utility model content

The purpose of this utility model is the short-circuit protection circuit providing a kind of soft switching, to solve the problem proposed in above-mentioned background technology.

For achieving the above object, the utility model provides following technical scheme:

A kind of short-circuit protection circuit, comprises transformer T, rectifier bridge Q, diode D3, diode D4, potentiometer RP1, comparator U1 and comparator U2, described transformer T coil L1 is serially connected in the collector circuit of IGBT, and transformer T coil L2 two ends connect rectifier bridge Q pin 1 respectively and rectifier bridge Q pin 3, rectifier bridge Q pin 2 connects diode D3 positive pole respectively, electric capacity C1, resistance R2 and resistance R3, diode D3 negative pole connects ground connection diode D4 negative pole, and described rectifier bridge Q pin 4 connects the electric capacity C1 other end respectively, the resistance R2 other end, electric capacity C2, potentiometer RP1, potentiometer RP1 slide plate, diode D2 positive pole, comparator U1 earth terminal, electric capacity C3 and comparator U2 earth terminal ground connection, the electric capacity C2 other end is the contact resistance R3 other end respectively, the potentiometer RP1 other end and comparator U1 in-phase end, comparator U1 end of oppisite phase connects diode D2 negative pole respectively, resistance R4, resistance R5 and comparator U2 end of oppisite phase, the resistance R4 other end is contact resistance R6 respectively, comparator U2 power end, comparator U1 power end and power supply VCC, the resistance R6 other end connects comparator U1 output and resistance R1 respectively, and the resistance R1 other end connects diode D1 negative pole respectively, the electric capacity C3 other end, comparator U2 in-phase end and resistance R7, the diode D1 positive pole contact resistance R5 other end, the described resistance R7 other end connects comparator U2 output and resistance R8 respectively, and the resistance R8 other end connects IGBT drive module.

As further program of the utility model: described comparator U1 and comparator U2 all adopts LM339.

As further program of the utility model: described diode D2 and diode D4 is voltage stabilizing didoe.

As the utility model further scheme: described IGBT drive module adopts chip EXB841.

Compared with prior art, the beneficial effects of the utility model are: the utility model short-circuit protection circuit can realize soft switching when short circuit to IGBT pipe, and fail safe is high, and circuit structure is simple, is applicable to very much promoting the use of.

Accompanying drawing explanation

Fig. 1 is the circuit diagram of short-circuit protection circuit.

Embodiment

Below in conjunction with the accompanying drawing in the utility model embodiment, be clearly and completely described the technical scheme in the utility model embodiment, obviously, described embodiment is only the utility model part embodiment, instead of whole embodiments.Based on the embodiment in the utility model, those of ordinary skill in the art are not making the every other embodiment obtained under creative work prerequisite, all belong to the scope of the utility model protection.

Refer to Fig. 1, in the utility model embodiment, a kind of short-circuit protection circuit, comprises transformer T, rectifier bridge Q, diode D3, diode D4, potentiometer RP1, comparator U1 and comparator U2, transformer T coil L1 is serially connected in the collector circuit of IGBT, and transformer T coil L2 two ends connect rectifier bridge Q pin 1 respectively and rectifier bridge Q pin 3, rectifier bridge Q pin 2 connects diode D3 positive pole respectively, electric capacity C1, resistance R2 and resistance R3, diode D3 negative pole connects ground connection diode D4 negative pole, and rectifier bridge Q pin 4 connects the electric capacity C1 other end respectively, the resistance R2 other end, electric capacity C2, potentiometer RP1, potentiometer RP1 slide plate, diode D2 positive pole, comparator U1 earth terminal, electric capacity C3 and comparator U2 earth terminal ground connection, the electric capacity C2 other end is the contact resistance R3 other end respectively, the potentiometer RP1 other end and comparator U1 in-phase end, comparator U1 end of oppisite phase connects diode D2 negative pole respectively, resistance R4, resistance R5 and comparator U2 end of oppisite phase, the resistance R4 other end is contact resistance R6 respectively, comparator U2 power end, comparator U1 power end and power supply VCC, the resistance R6 other end connects comparator U1 output and resistance R1 respectively, and the resistance R1 other end connects diode D1 negative pole respectively, the electric capacity C3 other end, comparator U2 in-phase end and resistance R7, the diode D1 positive pole contact resistance R5 other end, the resistance R7 other end connects comparator U2 output and resistance R8 respectively, and the resistance R8 other end connects IGBT drive module.

Comparator U1 and comparator U2 all adopts LM339.

Diode D2 and diode D4 is voltage stabilizing didoe.

IGBT drive module adopts chip EXB841.

Operation principle of the present utility model is: refer to Fig. 1, transformer T coil L1 is serially connected in the collector circuit of IGBT, the over-current signal that transformer T coil L2 responds to delivers to comparator U1 in-phase end after rectification, compare with the reference voltage V ref of end of oppisite phase, comparator U1 exports V1 to the comparator U2 in-phase end with positive feedback, exported through resistance R8 by the output of comparator U2, not during overcurrent, comparator U1 in-phase input end voltage is less than Vref, comparator U1 output output low level, comparator U2 in-phase end coating-forming voltage V2 is delivered to through resistance R1, because now voltage V2 is less than Vref, comparator U2 exports as low level, IGBT drive module is normally worked.When there is overcurrent, the commutating voltage that transformer T detects will raise, and V1 is greater than Vref, and V1 is high level; charged to electric capacity C3 by resistance R1, after certain time delay, V2 will be greater than Vref; comparator U2 exports high level, and chip EXB841 protective circuit works, and makes IGBT fall grid voltage soft switching.After IGBT closes, transformer T coil L1 no current flows through, and make V1 be less than Vref again, electric capacity C3 discharges through resistance R1, when V2 is less than Vref, and comparator U2 output low level, circuit rearming.If overcurrent exists, protective circuit returns to again original current-limiting protection operating state, and iterative cycles makes the output drive waveforms of EXB841 be in interval output state, and IGBT pipe output current effective value is reduced, and reaches the object of protection IGBT pipe.

To those skilled in the art, obvious the utility model is not limited to the details of above-mentioned one exemplary embodiment, and when not deviating from spirit of the present utility model or essential characteristic, can realize the utility model in other specific forms.Therefore, no matter from which point, all should embodiment be regarded as exemplary, and be nonrestrictive, scope of the present utility model is limited by claims instead of above-mentioned explanation, and all changes be therefore intended in the implication of the equivalency by dropping on claim and scope are included in the utility model.Any Reference numeral in claim should be considered as the claim involved by limiting.

In addition, be to be understood that, although this specification is described according to execution mode, but not each execution mode only comprises an independently technical scheme, this narrating mode of specification is only for clarity sake, those skilled in the art should by specification integrally, and the technical scheme in each embodiment also through appropriately combined, can form other execution modes that it will be appreciated by those skilled in the art that.

Claims

1. a short-circuit protection circuit, comprises transformer T, rectifier bridge Q, diode D3, diode D4, potentiometer RP1, comparator U1 and comparator U2, is characterized in that, described transformer T coil L1 is serially connected in the collector circuit of IGBT, and transformer T coil L2 two ends connect rectifier bridge Q pin 1 respectively and rectifier bridge Q pin 3, rectifier bridge Q pin 2 connects diode D3 positive pole respectively, electric capacity C1, resistance R2 and resistance R3, diode D3 negative pole connects ground connection diode D4 negative pole, and described rectifier bridge Q pin 4 connects the electric capacity C1 other end respectively, the resistance R2 other end, electric capacity C2, potentiometer RP1, potentiometer RP1 slide plate, diode D2 positive pole, comparator U1 earth terminal, electric capacity C3 and comparator U2 earth terminal ground connection, the electric capacity C2 other end is the contact resistance R3 other end respectively, the potentiometer RP1 other end and comparator U1 in-phase end, comparator U1 end of oppisite phase connects diode D2 negative pole respectively, resistance R4, resistance R5 and comparator U2 end of oppisite phase, the resistance R4 other end is contact resistance R6 respectively, comparator U2 power end, comparator U1 power end and power supply VCC, the resistance R6 other end connects comparator U1 output and resistance R1 respectively, and the resistance R1 other end connects diode D1 negative pole respectively, the electric capacity C3 other end, comparator U2 in-phase end and resistance R7, the diode D1 positive pole contact resistance R5 other end, the described resistance R7 other end connects comparator U2 output respectively and is connected IGBT drive module with the resistance R8 resistance R8 other end.

2. short-circuit protection circuit according to claim 1, is characterized in that, described comparator U1 and comparator U2 all adopts LM339.

3. short-circuit protection circuit according to claim 1, is characterized in that, described diode D2 and diode D4 is voltage stabilizing didoe.

4. short-circuit protection circuit according to claim 1, is characterized in that, described IGBT drive module adopts chip EXB841.