CN203026904U - Over-current protection circuit and PFC (power factor correction) control circuit with same - Google Patents

Over-current protection circuit and PFC (power factor correction) control circuit with same Download PDF

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Publication number
CN203026904U
CN203026904U CN2012206946297U CN201220694629U CN203026904U CN 203026904 U CN203026904 U CN 203026904U CN 2012206946297 U CN2012206946297 U CN 2012206946297U CN 201220694629 U CN201220694629 U CN 201220694629U CN 203026904 U CN203026904 U CN 203026904U
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CN
China
Prior art keywords
circuit
voltage
output
signal
input
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Application number
CN2012206946297U
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Chinese (zh)
Inventor
李巨林
贺煜华
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Tcl空调器(中山)有限公司
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Priority to CN2012206946297U priority Critical patent/CN203026904U/en
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Publication of CN203026904U publication Critical patent/CN203026904U/en

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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02BCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

The utility model discloses an over-current protection circuit and a PFC (power factor correction) control circuit with the same. The over-current protection circuit is connected between a sampling resistor of an active PFC circuit and a grid electrode of an IGBT (insulated gate bipolar translator) drive circuit; the over-current protection circuit comprises a signal input end, a signal output end and a comparison circuit which is connected between the signal input end and the signal output end; the signal input end is connected with the sampling resistor; the signal output end is connected with an input end of the IGBT drive circuit; an output end of the IGBT drive circuit is connected to the grid electrode of the IGBT; a system current signal is input through the signal input end after being converted into a sampling voltage signal through the sampling resistor; a high/low level signal is output by the comparison circuit; the IGBT drive circuit is controlled to output a control signal to control on or off of an IGBT; and a comparator can change an output state according to a detection result. Therefore, the over-current protection circuit has a timely and reliable effect on over-current protection, and is convenient to debug, and simple and rapid.

Description

Current foldback circuit and there is the PFC control circuit of this current foldback circuit
Technical field
The utility model relates to a kind of current foldback circuit, relates in particular to a kind of current foldback circuit and has the PFC(Power Factor Correction of this current foldback circuit, power factor correction) control circuit.
Background technology
Along with improving constantly of people's living standard, some high-end household electrical appliance have also entered ordinary family, as: LCD TV, electromagnetic oven, convertible frequency air-conditioner etc., and some Switching Power Supplies and powerful inductive load are due to the characteristic of itself, its exciting power can return to electrical network, household electrical appliance are reduced the utilance of electrical network, and the EMC(Electro Magnetic Compatibility that the harmonic current that inductive load produces brings) with the THD(total harmonic distortion) problem, had a strong impact on the normal use of household electrical appliance.
For this reason, passive PFC control method and active PFC control method have been proposed at present, to improve the electrical network utilance of household electrical appliance.Although the passive PFC reliability be comprised of passive device is high, power factor is low, still lower to the utilance of electrical network, active PFC is comprised of some active devices usually, such as: IGBT(Insulated Gate Bipolar Transistor, insulated gate bipolar transistor), its power factor is higher, usually can reach 0.99, so present BOOST(boost chopper as shown in Figure 1 that generally adopts) the PFC control circuit of structure, but, there is following defect in this BOOST structure: when the improper use of electrical equipment own or the protection not in time, be easy to due to the former of overcurrent thereby cause IGBT(G1 as shown in Figure 1) damage, electrical equipment or equipment can't normally be used, thereby bring a lot of adverse effects to user's production and life, and, after IGBT damages, whole circuit just is equivalent to passive PFC, but as previously mentioned, passive PFC power factor is low, so still low to the utilance of electrical network.
And the common current value that detects PFC with the A/D mouth of single-chip microcomputer in prior art, once if overcurrent, single-chip microcomputer will be processed detected electric current by a series of computing, often due to protection, cause not in time the damage of PFC, and can not automatically recover after a lot of electrical equipment or device current are normal, need to re-power and could start shooting or use, in addition, prior art also has by current transformer and detects electric current, but the precision of current transformer is not very high, general error is in the 0.5A left and right, if use high-precision current transformer, its design cost is very high again, in some household appliance technical field, be not too suitable.
The utility model content
Main purpose of the present utility model is to provide a kind of PFC control circuit that can protect in time the current foldback circuit that pfc circuit and simple and fast, reliability are high and have this current foldback circuit.
In order to achieve the above object, the utility model proposes a kind of current foldback circuit, be connected between the sampling resistor and IGBT drive circuit of active PFC circuit, current foldback circuit comprises signal input part, signal output part and is connected to the comparison circuit between described signal input part and signal output part; Described signal input part is connected in active PFC circuit between sampling resistor and rectifier bridge, and described signal output part connects the input of described IGBT drive circuit, and the output of IGBT drive circuit is connected on the grid of IGBT; After the system power signal changes the sampled voltage signal into by sampling resistor, by described signal input part input, by described comparison circuit, export high/low level signal, control cut-off or conducting that IGBT drive circuit output control signal is controlled IGBT.
Preferably, described comparison circuit comprises a comparator and is used to described comparator that the reference voltage circuit of reference voltage is provided; Described reference voltage circuit comprises the first DC power supply and the first pull-up resistor; Described the first DC power supply connects the output of comparator by the first pull-up resistor; The inverting input of described comparator connects described signal input part, and the in-phase input end of described comparator is through pull down resistor ground connection; Also be connected with feedback resistance between the in-phase input end of described comparator and output, described the first DC power supply forms reference voltage through described the first pull-up resistor between described feedback resistance and pull down resistor; The high/low level signal of described comparison circuit output determines the size of described reference voltage, upset along with the output output state of described comparator, reference voltage can produce lower limit reference voltage and upper limit reference voltage, the corresponding high level signal output of lower limit reference voltage, the corresponding low level signal output of upper limit reference voltage.
Preferably, this current foldback circuit also comprises divider resistance, and described divider resistance is connected between the inverting input and described signal input part of described comparator.
Preferably, this current foldback circuit also comprises biasing circuit, and described biasing circuit comprises the second DC power supply and the second pull-up resistor, and described the second DC power supply connects the inverting input of comparator through described the second pull-up resistor; Described the second DC power supply is by the second pull-up resistor output offset voltage, and described bias voltage and the described sampled voltage signal voltage after described divider resistance dividing potential drop superposes, and is input to the inverting input of described comparator.
Preferably, this current foldback circuit also comprises a filter capacitor, and described filter capacitor is connected in parallel on the two ends of described feedback resistance.
The utility model also proposes a kind of PFC control circuit, comprises current foldback circuit as above.
A kind of current foldback circuit the utility model proposes and the PFC control circuit with this current foldback circuit; after changing current signal into voltage signal by sampling resistor; detect the size of this voltage signal by hysteresis comparator; due to the in-phase input end of comparator during higher or lower than the voltage of inverting input; its output state will overturn at once, therefore can carry out in time, reliably overcurrent protection.In addition, the threshold value of protective current can be adjusted by the resistance that changes circuit, and debugging is convenient, simple and fast.
The accompanying drawing explanation
Fig. 1 is the PFC control circuit structural representation of existing BOOST structure;
Fig. 2 is the PFC control circuit structural representation with current foldback circuit of the utility model preferred embodiment;
Fig. 3 is the electrical block diagram of current foldback circuit in Fig. 2;
Fig. 4 is the transmission characteristic figure of the output voltage V 0 of sampled voltage Vi and comparator in the current foldback circuit shown in Fig. 3.
In order to make the technical solution of the utility model clearer, clear, below in conjunction with accompanying drawing, be described in further detail.
Embodiment
With reference to Fig. 2 and Fig. 3, Fig. 2 is the PFC control circuit structural representation with current foldback circuit of the utility model preferred embodiment, and Fig. 3 is the electrical block diagram of current foldback circuit in Fig. 2.
The present embodiment is in order to overcome in prior art, when the electrical equipment improper use or the protection not in time, be easy to because overcurrent etc. is former thereby cause IGBT to damage, electrical equipment or equipment can't normally be used, as shown in Figure 3, the utility model proposes a kind of current foldback circuit, be connected between the sampling resistor R1 and IGBT drive circuit of the active PFC circuit shown in Fig. 2, specifically as shown in Figure 2, this current foldback circuit 10 and IGBT drive circuit are connected in turn between the A point and G point in Fig. 2, described A point is the node between sampling resistor R1 and rectifier bridge in active PFC circuit, described G point connects the grid of IGBT G1.
Particularly, this current foldback circuit 10 comprises: connect signal input part, the signal output part that A orders and be connected to the comparison circuit 1 between described signal input part and signal output part, described signal output part connects the input of IGBT drive circuit 2; The output of described IGBT drive circuit 2 connects the G point, thereby is connected on the grid of IGBT G1; Sampling resistor R1 connects described signal input part system power signal change the sampled voltage signal into by sampling resistor R1 after, by described signal input part input, by the high/low level signal of described comparison circuit 1 output, control cut-off or conducting that IGBT drive circuit 2 output control signals are controlled IGBT G1.
Described comparison circuit 1 comprises a comparator IC and is used to described comparator IC that the reference voltage circuit of reference voltage is provided; Described reference voltage circuit comprises a drop-down resistance R 3; The output of described comparator IC connects one first DC power supply by the first pull-up resistor R5; The inverting input of described comparator IC connects described signal input part A by divider resistance R2, and the in-phase input end of described comparator IC is through pull down resistor R3 ground connection; Also be connected with feedback resistance R6 between the in-phase input end of described comparator IC and output, the two ends of described feedback resistance R6 also are parallel with filter capacitor C1, and described the first DC power supply forms reference voltage U between described feedback resistance R6 and pull down resistor R3 through described the first pull-up resistor R5.
Further, when signal input part is fainter from the sampled voltage signal of A point acquisition, in order to strengthen this sampled voltage signal, can also increase by a biasing circuit 3, described biasing circuit 3 comprises one second pull-up resistor R4, and the reverse input end of described comparator IC connects one second DC power supply by described the second pull-up resistor R4; Described the second DC power supply is by the second pull-up resistor R4 output offset voltage, and described bias voltage and the described sampled voltage signal voltage after described divider resistance R2 dividing potential drop superposes, and is input to the inverting input of described comparator IC.
Thus, by the stack of sampled voltage and bias voltage, the variation of sampled voltage weak output signal can make the inverting input of comparator IC receive the input voltage that variation is larger, thus the precision that can improve protection and detect.
In the present embodiment, be preferably+5V of the first DC power supply DC power supply, be preferably+5V of the second DC power supply DC power supply, comparator IC is preferably the LM293 voltage comparator, below elaborates the operation principle of the present embodiment:
As shown in Figure 3, the voltage of comparator IC in-phase input end is reference voltage U, reference voltage U is that the first DC power supply produces by above-mentioned reference voltage circuit, the high/low level signal of the output output of comparator IC determines the size of reference voltage U, therefore along with the upset of the output output state of comparator IC, reference voltage U can produce lower limit reference voltage UL and upper limit reference voltage UH, wherein, the corresponding high level signal output of lower limit reference voltage UL, the corresponding low level signal output of upper limit reference voltage UH.System power I is after sampling resistor R1 changes sampled voltage Vi into, and by signal output part, A is input in current foldback circuit.
The sense of current that system power I in Fig. 2 and Fig. 3 shown in arrow and the second DC power supply produce is known, changing by sampling resistor R1 the sampled voltage Vi come by system power I is a negative voltage signal, and system power I is larger, the numerical value of sampled voltage Vi is less, the voltage that is input to comparator IC inverting input after sampled voltage Vi and bias voltage stack is U, increase along with system power I, the numerical value of sampled voltage Vi will reduce gradually, U also will reduce gradually simultaneously, when system power I is greater than certain value, the inverting input voltage U is less than the lower limit reference voltage UL of in-phase input end, the output of comparator IC is exported high level signal, the IGBT drive circuit 2 that makes to be connected on the output of comparator IC drives IBGT G1 cut-off, thereby reach the purpose of protection IGBT G1 when electric current is excessive, simultaneously, when IGBT G1 ends, because being converted into electric energy, the magnetic energy of storing in inductance L 1 continues powering load, and the output voltage of inductance L 1 equals the inverse electromotive force of line voltage coilloading L1, be equivalent to raise the voltage of diode D1 anode, the time of current following input voltage is lengthened, therefore improved power factor, along with reducing of system power I, sampled voltage Vi will increase gradually, U_ also will increase gradually simultaneously, when system power I returns to the setting normal value, inverting input voltage U _ be greater than the upper limit reference voltage UH of in-phase input end, the output output low level signal of comparator IC, the IGBT drive circuit 2 that makes to be connected on the output of comparator IC drives IBGT G1 gate turn-on, make the pfc circuit normal operation, now electrical network is to inductance L 1 energy storage.
Concrete, as shown in Figure 2, in the present embodiment, comparator IC model is preferably LM293, in the present embodiment, if set divider resistance R2=20K, pull down resistor R3=1K, the second pull-up resistor R4=125K, the first pull-up resistor R5=5.1K, feedback resistance R6=100K, filter capacitor C1=10PF, the sampled voltage of being ordered by A is Vi, according to circuit diagram in Fig. 2, the inverting input voltage U of known LM293 _ be , when system power I is greater than certain value, inverting input voltage U _ be less than the now lower limit reference voltage UL of in-phase input end, and lower limit reference voltage UL=0, so by can extrapolate Vi<-0.8V, if detecting the resistance of resistance R 1 is 20m Ω, Vi=-0.02I<-0.8, can extrapolate I>40A, be that system power I is while being greater than 40A, LM293 output output high level signal, the IGBT drive circuit 2 that makes to be connected on the output of LM293 drives IGBT G1 cut-off, thereby reach the purpose of protection IGBT G1 when electric current is excessive, simultaneously, when IGBT G1 ends, because being converted into electric energy, the magnetic energy of storing in inductance L 1 continues powering load, and the output voltage of inductance L 1 equals the inverse electromotive force of line voltage coilloading L1, be equivalent to raise the voltage of diode D1 anode, the time of current following input voltage is lengthened, therefore improved power factor.
Along with reducing of system power I, sampled voltage Vi will increase gradually, and simultaneously U_ also will increase gradually, when system power I returns to, set normal value when following, inverting input voltage U _ be greater than the now upper limit reference voltage UH of in-phase input end, and upper limit reference voltage , so by can extrapolate Vi>-0.74V, if detecting the resistance of resistance R 1 is 20m Ω, Vi=-0.02I>-0.74, can extrapolate I<37A, be to set normal value 37A when following when system power I returns to, the output output low level signal of LM293, the IGBT drive circuit 2 that makes to be connected on the output of comparator IC drives IBGT G1 conductings, and electrical network is to inductance L 1 energy storage.
That is to say, be 20m Ω if detect the resistance of resistance R 1, and when the electric current that flows through detection resistance R 1 is greater than 40A, IGBT drive circuit 2 drives IGBT G1 cut-off, thereby reach the purpose of protection IGBT when electric current is excessive; When electric current is less than 37A, IGBT drive circuit 2 drives IBGT G1 conducting, and system is recovered normal operation.
In system power I change procedure, as shown in Figure 4, Fig. 4 is the transmission characteristic figure of the output voltage V 0 of sampled voltage Vi and LM293 in the current foldback circuit of the utility model preferred embodiment.When Vi<-0.8V, i.e. I during 40A, the output voltage V 0=5V of LM293, the IGBT drive circuit 2 that makes to be connected on the output of LM293 drives the cut-off of IBGT G1 grids, thereby protection IGBT G1; Work as Vi >-0.74V, during I<37A, the output voltage V 0=0V of LM293, the IGBT drive circuit 2 that makes to be connected on the output of comparator IC drives IBGT G1 normal operation, now IBGT G1 conducting.
Compared to existing technology; existing active PFC circuit is worked as the improper use of electrical equipment own or is protected not in time; be easy to, because overcurrent etc. is former thereby cause IGBT to damage, electrical equipment or equipment can't normally be used, thereby bring a lot of adverse effects to user's production and life.
The current foldback circuit of the present embodiment; its peripheral circuit is simple; carry out the detection system electric current I by the hysteresis comparator formed by comparator LM293; when system power I reaches the protection threshold value of circuit; the output of hysteresis comparator will be overturn at once, thereby control conducting and the cut-off of IGBT G1, and the time of this upset is in nanosecond; detect the fast order of magnitude of overcurrent than the A/D mouth with single-chip microcomputer, and then protect in time IGBT G1 not to be damaged.When IGBT G1 conducting, electrical network is to inductance L 1 energy storage, when IGBT G1 ends, because being converted into electric energy, the magnetic energy of storing in inductance L 1 continues powering load, and the output voltage of inductance L 1 equals the inverse electromotive force of line voltage coilloading L1, be equivalent to raise the voltage of diode D1 anode, the time of current following input voltage is lengthened, compare passive PFC, improved power factor.
In addition, in the current foldback circuit of the utility model preferred embodiment, the threshold value of protective current can be adjusted by the resistance of circuit, depend on+5V of the size of described reference voltage U DC power supply is at the first pull-up resistor R5, distribution on feedback resistance R6 and pull down resistor R3, therefore in use can be by adjusting the first pull-up resistor R5, the size of feedback resistance R6 and pull down resistor R3 is changed the size of reference voltage U, also can adjust by adjusting sampling resistor R1 size the size of sampled voltage Vi, thereby set the parameter of protective current, simple and fast, reliability is high, and debugging is convenient.
The foregoing is only preferred embodiment of the present utility model; not thereby limit the scope of the claims of the present utility model; every equivalent structure or flow process conversion that utilizes the utility model specification and accompanying drawing content to do; or directly or indirectly be used in other relevant technical field, all in like manner be included in scope of patent protection of the present utility model.

Claims (6)

1. a current foldback circuit, be connected between the sampling resistor and IGBT drive circuit of active PFC circuit, it is characterized in that, comprises signal input part, signal output part and be connected to the comparison circuit between described signal input part and signal output part; Described signal input part is connected in active PFC circuit between sampling resistor and rectifier bridge, and described signal output part connects the input of IGBT drive circuit, and the output of IGBT drive circuit is connected on the grid of IGBT; After the system power signal changes the sampled voltage signal into by sampling resistor, by described signal input part input, by described comparison circuit, export high/low level signal, control cut-off or conducting that IGBT drive circuit output control signal is controlled IGBT.
2. current foldback circuit according to claim 1, is characterized in that, described comparison circuit comprises a comparator and is used to described comparator that the reference voltage circuit of reference voltage is provided; The drop-down resistance of described reference voltage circuit one; The output of described comparator connects one first DC power supply by the first pull-up resistor; The inverting input of described comparator connects described signal input part, and the in-phase input end of described comparator is through described pull down resistor ground connection; Also be connected with feedback resistance between the in-phase input end of described comparator and output, described the first DC power supply forms reference voltage through described the first pull-up resistor between described feedback resistance and pull down resistor; The high/low level signal of described comparison circuit output determines the size of described reference voltage, upset along with the output output state of described comparator, reference voltage can produce lower limit reference voltage and upper limit reference voltage, the corresponding high level signal output of lower limit reference voltage, the corresponding low level signal output of upper limit reference voltage.
3. current foldback circuit according to claim 2, is characterized in that, also comprises divider resistance, and described divider resistance is connected between the inverting input and described signal input part of described comparator.
4. current foldback circuit according to claim 3, is characterized in that, also comprises biasing circuit, and described biasing circuit comprises one second pull-up resistor, and the reverse input end of described comparator connects one second DC power supply by described the second pull-up resistor; Described the second DC power supply is by the second pull-up resistor output offset voltage, and described bias voltage and the described sampled voltage signal voltage after described divider resistance dividing potential drop superposes, and is input to the inverting input of described comparator.
5. current foldback circuit according to claim 4, is characterized in that, also comprises a filter capacitor, and described filter capacitor is connected in parallel on the two ends of described feedback resistance.
6. a PFC control circuit, is characterized in that, comprises the described current foldback circuit of any one in claim 1-5.
CN2012206946297U 2012-12-14 2012-12-14 Over-current protection circuit and PFC (power factor correction) control circuit with same CN203026904U (en)

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104779577A (en) * 2014-01-10 2015-07-15 海洋王(东莞)照明科技有限公司 Over-current protection circuit
CN106329483A (en) * 2015-06-29 2017-01-11 欧姆龙株式会社 Switch power supply
CN106532627A (en) * 2016-12-13 2017-03-22 珠海格力电器股份有限公司 Current projection circuit and system
CN108206517A (en) * 2018-03-08 2018-06-26 广州金升阳科技有限公司 A kind of low cost inputs anti-overvoltage crowbar
CN109149520A (en) * 2018-08-21 2019-01-04 珠海格力电器股份有限公司 A kind of overheat overcurrent protective device, motor and its overheat over-current protection method
CN110707668A (en) * 2019-10-12 2020-01-17 法泰电器(江苏)股份有限公司 Overcurrent detection and on-off control method of solid-state circuit breaker

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104779577A (en) * 2014-01-10 2015-07-15 海洋王(东莞)照明科技有限公司 Over-current protection circuit
CN104779577B (en) * 2014-01-10 2018-11-06 海洋王(东莞)照明科技有限公司 A kind of current foldback circuit
CN106329483A (en) * 2015-06-29 2017-01-11 欧姆龙株式会社 Switch power supply
CN106329483B (en) * 2015-06-29 2018-11-09 欧姆龙株式会社 Switching Power Supply
CN106532627A (en) * 2016-12-13 2017-03-22 珠海格力电器股份有限公司 Current projection circuit and system
CN108206517A (en) * 2018-03-08 2018-06-26 广州金升阳科技有限公司 A kind of low cost inputs anti-overvoltage crowbar
WO2019169904A1 (en) * 2018-03-08 2019-09-12 广州金升阳科技有限公司 Low-cost input anti-overvoltage protection circuit
CN108206517B (en) * 2018-03-08 2020-05-19 广州金升阳科技有限公司 Low-cost input overvoltage-resistant protection circuit
CN109149520A (en) * 2018-08-21 2019-01-04 珠海格力电器股份有限公司 A kind of overheat overcurrent protective device, motor and its overheat over-current protection method
CN110707668A (en) * 2019-10-12 2020-01-17 法泰电器(江苏)股份有限公司 Overcurrent detection and on-off control method of solid-state circuit breaker

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