CN203840606U - Novel alternating current LED drive power supply device - Google Patents

Abstract

The utility model relates to the field of LED lighting, and especially relates to a drive circuit of a lighting lamp which is used in daily life. A novel alternating current LED drive power supply device comprises a lightning protection circuit, a PFC circuit, a high voltage rectification circuit, an AC-LED drive circuit, an LED lamp bead module and a temperature sensor. According to the alternating current LED drive power supply device provided by the utility model, a transformer with large volume is no longer used, which can save a considerable space; a large capacity electrolytic capacitor which cannot be used for a long time is no longer used, thus the product reliability is greatly improved; the longest product service life, which is allowed by an LED lamp, of LED lighting is realized; the limit of the short service life cycle of the electrolytic capacitor is broken; and LED lighting is environment-friendly, green and long-term.

Description

Novel AC LED drive electric power unit

Technical field

the present invention relates to LED lighting field, be especially applied in the drive circuit of the illuminating lamp of daily life.

Background technology

LED light source as green, energy-conservation, power saving, long-life the 4th generation lighting and be a dark horse, extensively concerned, develop rapidly in high gear.Current LED light source is the semiconductor device of low-voltage, large current work, must provide the suitable direct current stream could be normally luminous.At present no matter domestic or the drive circuit of external LED generally all adopts DC power supply to power, the luminous technology of DC driven LED light source is more and more ripe, the power supply using due to our normal lighting is to exchange (AC 100～220V), so must obtain by the technology of step-down lower voltage, conventional method is to adopt transformer or Switching Power Supply step-down, then exchange conversion is become to direct current, then be transformed into DC constant current power supply, just can impel LED light source luminous.Therefore the system applies scheme main flow of DC driven LED light source is: transformer+rectification+constant-current source or transformer+Switching Power Supply+constant-current source.But there is following problem in DC driven supply power mode:

1, LED light fixture (mainly referring to bulb lamp here), comprise LED combination module, driving power module and light fixture lamp holder, light fixture lamp holder must have will have certain space to settle LED combination module, driving power module, but very limited for space the light fixture of the daily bayonet type to the GU such as the standard screw sockets such as E14. E27. E12. E26 and GU10 beginning, be difficult to settle.

2, no matter be via transformer+rectification or Switching Power Supply step-down, system all can have a certain amount of loss, when DC driven power supply LED light fixture is changed between alternating-current/direct-current, approximately 15%～30% electric power is depleted, and system effectiveness is difficult to accomplish that more than 90% energy resource consumption is larger.

If can be with exchanging direct driving LED light source luminescent, system applies scheme will be simplified greatly, and system effectiveness will reach more than 90% very like a cork, compare with traditional LED DC driven, and in the application scenario of mains-supplied, exchanging to drive has greater advantage.Therefore it can not need transformation rectification and unsteady flow homenergic transform part, has reduced electric energy loss, has the advantages such as easy to use, cost is low, volume is little, circuit is simple and efficiency is high.

Summary of the invention

technical problem to be solved by this invention is to overcome above-mentioned the deficiencies in the prior art, and a kind of novel AC LED drive electric power unit is provided.

in order to solve the problems of the technologies described above, novel AC LED drive electric power unit of the present invention, is characterized in that: it comprises that lightning protection circuit 1, pfc circuit 2, high-voltage rectifier 3, AC-LED drive circuit 4, LED lamp pearl module 5, temperature sensor 6 form.Described AC power is sent into lightning protection circuit 1, PFC circuit of power factor correction 2 is sent in the output of lightning protection circuit 1, calibrated AC power is sent into high-voltage rectifier 3, direct voltage through rectification circuit 3 outputs is sent into LED drive circuit 4, LED lamp pearl module 5 is connected with the output of LED drive circuit 4, on LED lamp pearl module 5, temperature sensor 6 is installed, the temperature signal that LED drive circuit 4 receives from temperature sensor 6, regulation output is to the drive current of LED lamp pearl module 5 automatically.

further, described lightning protection circuit 1 by resettable fuse,the composition differential mode lightning protection circuits such as metal-oxide varistor with alloy-type temperature fuse;

further, described pfc circuit 2the passive PFC circuit adopting is comprised of three diodes and two electric capacity;

further, described high-voltage rectifier 3 forms filter circuit by rectifier bridge and electric capacity and is formed;

further, described LED drive circuit 4directly use the illumination LED Driver IC of alternating current

form,the relatively huge transformer of volume needn't be re-used, sizable space can be saved.Certainly also just needn't use again the big capacity electrolyte capacitor of not resistance to long-time use, significantly improve the reliability of product, allow LED illumination become really can to reach LED lamp grain allows long products life-span, not limited by the of short duration life cycle of electrochemical capacitor, this environmental protection that LED illumination has just, green energy, long-acting.

further, described LED lamp pearl module 5 is formed in parallel after being contacted by many pieces of LED again;

further, described temperature sensor 6 adopts thermistor NTC, it is positioned near the LED pipe in light fixture, for detection of the temperature of the LED pipe in light fixture.

above feature will be introduced in detail in embodiment.

Accompanying drawing explanation

Fig. 1: overall system block diagram

Fig. 2: lightning protection unit circuit

Fig. 3: rectification unit circuit

Fig. 4: PFC power factor correction unit circuit

Fig. 5: LED driver element

Fig. 6: temperature sensing circuit schematic diagram

Fig. 7: oscillogram

embodiment

below in conjunction with accompanying drawing, the present invention is further illustrated.

fig. 2 islightning protection unit circuit

In Fig. 2, alternating current input power supplying live wire (L) is connected with one end of restorability protective tube (a); the other end of restorability protective tube (a) is connected with zero line (N) with the Zinc-oxide piezoresistor (b) with temperature protection; form differential mode protective circuit; metal-oxide varistor; referred to as varistor; it is widely used as overvoltage protection and the surge absorbing element of circuit, equipment and components and parts with its superior non-linear voltage-current characteristic.Though metal-oxide varistor has remarkable function and efficacy, but it is under the effect of various stress, always can lose efficacy, and its failure mode mostly is short circuit failure mode.Losing efficacy finally all to make metal-oxide varistor be short-circuited.If effective safeguard measure rapidly not departs from the metal-oxide varistor having lost efficacy timely from circuit, can cause the short circuit accident of whole supply line, and cause and catch fire or explode.What the present invention adopted is the piezo-resistance with alloy-type temperature fuse, in Fig. 2, (b) is exactly the piezo-resistance with alloy-type temperature fuse, it is alloy-type temperature fuse (c) and is that metal-oxide varistor (d) is combined, and can avoid because metal-oxide varistor is deteriorated, losing efficacy produces the overheated disaster hidden-trouble producing.Protection philosophy is such: alloy-type temperature fuse and metal-oxide varistor are cascaded, the pulse current that alloy-type temperature fuse need to bear (should with the maximum of metal-oxide varistor bear current value suitable), when metal-oxide varistor reaches a certain temperature, alloy-type temperature fuse is with regard to quick-break, so just cut off the current path of metal-oxide varistor, avoided the continuation heating of metal-oxide varistor, this just can play protective action to catching fire of metal-oxide varistor.After the temperature of metal-oxide varistor drops to a certain numerical value, alloy-type temperature fuse resets.

Fig. 3 is high-voltage rectifier schematic diagram

220V alternating voltage is sent into the bridge rectifier being comprised of D1/D2/D3/D4 and is carried out full-wave rectification, by AC voltage conversion, is direct voltage output.

Fig. 4 is PFC power factor correction unit circuit

Schematic diagram, for improving line power factor, suppresses current waveform distortion, must adopt PFC measure.Passive PFC circuit is not used the active devices such as transistor, but by diode, resistance, the passive component such as electric capacity and inductance forms, passive PFC circuit has a lot of types, the passive PFC circuit that the present invention adopts is comprised of three diodes and two electric capacity, the operation principle of this passive PFC circuit is: when the AC of 50Hz line voltage distribution by sinusoidal rule by 0 1/4 cycle changing to peak value Vm in (in the 0<t< 5ms phase, asking), diode D2 and D3 conducting in bridge rectifier (D1 and D4 cut-off), electric current charges (as the A in Fig. 3 schemes) to C4 to capacitor C 3 and through diode D6.When Vac instantaneous value reaches Vm, because of C3=C4, therefore C3 is identical with the voltage on C4, be 1/2Vm, when AC line voltage distribution starts to decline from peak value, capacitor C 3 is discharged rapidly (as the B in Fig. 3 schemes) by load and diode D7, and fall off rate declines faster than AC voltage by sinusoidal rule, therefore until AC instantaneous voltage reaches 1/2 V-, before, D2 and D3 conducting always.When instantaneous AC voltage magnitude is less than 1/2 V-, time, capacitor C 2 is by D7 and load discharge.When ac input voltage instantaneous value is during lower than the DC bus voltage of passive PFC circuit, D1 and D4 cut-off, AC electric current can not pass through rectifier diode, so dead band appears in IAC.In asking during after the negative half period of AC voltage starts one section, D2 and D3 be conducting at once.Only at AC instantaneous voltage during higher than the DC voltage of bridge rectifier output, D2 and D3 could be because of forward bias conductings.Once D2 and D3 conducting, C3 and C4 are recharged again, so occur and the positive similar situation of half cycle, result obviously increases the rectifier diode angle of flow, AC input current waveform can become smoothly, adopts this compensation method to make to exchange phase difference between the fundamental current of input and voltage and reduces to reach the object that improves power factor.

Fig. 5 is LED driver element circuit, and circuit has adopted a slice special chip IC 1 , chip supports 12V to the power supply input of 600V, is a driving chip that is specifically designed to the LED illumination of civil power input (220 V ac/110 V ac).In order to extend the useful life of LED lamp,iC1 adopt the type of drive of current mode.iC1 there is good user interface, support multiple light-modulating mode, both can be for PWM light modulation, again can be for the light modulation of analog linearity voltage.

in order to solve chip heating problem,iC1 there is no built-in power switching tube, user can select suitable power MOS pipe according to the size of output current, so has both been conducive to solve heat dissipation problem, also can need to optimize flexibly whole conceptual design according to practical application.

IC1 the pin function of chip is as follows:

PIN1:vin power input, supports that 12V inputs to 600 direct voltages, while being used in electric main, only needs through rectifier bridge.While considering practical application, vin need to provide certain drive current, if input voltage is higher, chip is by the larger power consumption of consumption rate, cause chip temperature to rise, when application, the resistance of several parallel connections of connecting is to share a part of power consumption, and the value of these resistance is not less than 50V with vim voltage and is as the criterion.

PIN2: current detecting end Isense, isense voltage obtain corresponding electric current divided by sampling resistor (Rsense).In Current rise process, when the voltage of changing the time is during lower than 250mv or adim, driver output HIGH voltage, otherwise output LOW voltage turn-offs MOS power tube through toff time, the conducting again of MOS power tube.As isense voltage, driver will export the square wave of low duty ratio during always higher than 250mv or adim, and exporting low logical time is toffo.

PIN3:gnd, chip power ground;

PIN4:driver, outside MOS power tube drives pin, and its output HIGH voltage is 7.5 v, and low-voltage is 0v;

PIN5:ddim, i.e. PWM control pin, when ddim is high logic, chip operation, during for low logic, driver output LOW voltage, turn-offs the MOS power tube of outside, and whole system is in low power consumpting state, and now overall power consumption is in 0.2W left and right.The pull down resistor of the built-in 100k of Ddim, even also used time, this pin can not be unsettled, otherwise chip is not worked.

PIN6:vcc, the working power of chip, is produced by built-in high tension voltage adjuster.

PIN7:adim, analog linearity light modulation input pin, corresponding with ddim.When adim is greater than 250mv, driving LED electric current and the adim of output are irrelevant, and when adim is less than 250mv, the LED drive current peak value of setting is directly proportional to adim;

PIN8:toff, the external MOS turn-off time arranges pin, and during use, R1 resistance is connected between toff and driver, and the pass of turn-off time and this resistance is

Toff=R1(kΩ)+22/25μs

Adjust R1 resistance, can obtain the different turn-off times.

In Fig. 5, the direct voltage of PFC unit output is sent into LED driver element circuit after filter capacitor C5 filtering, divider resistance R6a with after R6b parallel connection, be connected with the Vin pin of chip IC 1, R6a and R6b have two effects, one is in order to reduce the temperature of IC1, one is in order to reduce the voltage of Vin pin, and the impulse voltage misfortune that prevents electrical network is incorporated into Vin pin and punctures chip.Two resistance parallel connections of R6a and R6b are to share a part of power consumption.Overcharged voltage in order to prevent from powering on, R6a and R6b preferably select resistance more than 1/4W, adjust the resistance of R6a and R6b, and the vin point voltage of take is not less than 50V as normative reference.

In figure, R4, R5, C6 have formed chip soft starting circuit.Soft-start time T=(R4+R5) * C7, this soft-start time can prevention system power up in the violent rising of LED electric current, the safety of protection LED lamp.

The effect of R3 in figure, in order to protect MOS power tube MOS power tube Q1 and LED load, when IC1 lost efficacy, R3 has been communicated with source electrode and the grid of MOS power tube Q1, automatically closes MOS power tube Q1 switch, has protected LED lamp load.

Protective circuit has overvoltage protection and overcurrent protection, overvoltage protection: D9 and G1 play overvoltage protection, when voltage surpasses 1.2v, and D9 conducting, electric current flows through R14.When R14 pressure drop is during higher than 1.2V, G1 conducting, drop-down ddim voltage turn-offs chip.

Overcurrent protection: G1 and resistance R 15, R16, R17 play overvoltage protection, and when LED electric current is excessive, the pressure drop on R 15, R 16, R 17 also will make G1 conducting, thereby turn-off chip.

RCD clamp circuit is comprised of R13, C3 and D7, due to the existence of transformer leakage inductance and the impact of other distributed constant, converter can produce very large peak voltage at switching tube shutdown moment, the normal work of switching tube in this peak voltage serious threat, must take measures it to suppress.RCD clamp method is simple in structure with it, feature with low cost and being used widely.The operation principle of RCD clamp circuit is: while powering on, power supply charges to L1, Current rise, and when isense voltage rises to 250mV, chip 4 pin output low levels are turn-offed MOS power tube Ql.Through the toff time, chip 4 pin output high level, repeat process above.From this analysis, can find out, during MOS power tube Q1 conducting, L1 charging, power supply passes through L1, Q1, R2 to gnd; When MOS power tube Q1 turn-offs, the energy of storing in L1, will transfer to secondary L2 output, L2 electric discharge, and the energy flow of L2 storage is crossed D8 and the load of LED lamp module.When MOS power tube Q1 conducting, stored energy is in L1, when MOS power tube Q1 ends, the energy of storing in L1, to transfer to secondary L2 output, but the energy in leakage inductance will can not transferred to secondary, if there is no RCD clamp circuit, energy in leakage inductance will be transferred in the drain-source interelectrode capacitance and other stray capacitance in circuit of switching tube at MOS power tube shutdown moment, and the now drain electrode of MOS power tube will be born higher switch stress.If add RCD clamp circuit, most of energy in energy in leakage inductance will be transferred at MOS power tube shutdown moment on the clamping capacitance C3 of clamp circuit, and then this part energy is consumed and just greatly reduced like this voltge surge power to MOS power tube Q1 by case position resistance R 13.

R1 determines the time of turn-offing;

C3 plays energy storage and afterflow;

The key of the whole circuit of R2, has determined the size of inductance peak current;

Q1: external MOS power tube;

T1: high frequency transformer, is comprised of armature winding L1 and secondary winding L2.

The direct voltage of circuit working process PFC unit output is sent into LED driver element circuit after filter capacitor C5 filtering, after soft-start time, chip 4 pin output signal to MOS power tube Q1 and make its conducting, power supply passes through L1, Q1, R2 charges to L1 to ground, when isense voltage rises to 250mV, chip 4 pin output low levels are turn-offed MOS power tube Ql, the energy of storing in L1, to transfer to secondary L2 output L2 electric discharge, the energy flow of L2 storage is crossed D8 and the load of LED lamp module, through the toff time, chip output high level, repeat process above, working waveform figure is shown in 8.

Fig. 6 is temperature sensing circuit schematic diagram

in AC LED drive system in LED lighting, LED pipe in light fixture (claims again, LED lamp pearl) at work can the evolution of heat, heating causes temperature to raise, the standard the highest of giving according to the star of american energy is 85 ° of normal work of guarantee LED pipe, once temperature surpasses 85 °, the light decay of LED pipe will be very fast, and the life-span also can sharply decline along with the rising of temperature.The thermistor that the present invention has negative temperature coefficient is positioned near the LED pipe in light fixture, for detection of the temperature of the LED pipe in light fixture; The thermistor that NTC is negative temperature coefficient in Fig. 6, temperature rising resistance value declines, the voltage of sending into transistor T 1 base stage can change thereupon, exports to the end of oppisite phase of operational amplifier A 1 after amplifying, and delivers to the A1-1 port controlling output of Fig. 5 by amplifier A1 output port A1-2lED drive current , when temperature is raise, drive current reduces, and reduces the consumption heating amount of LED pipe, ensures the normal work of LED pipe.

fig. 8 is relevant key point oscillogram.

the content that this specification is not described in detail belongs to and well known to a person skilled in the art prior art; although oneself is illustrated the present invention and is described by relevant case study on implementation; but; those skilled in the art should be understood; in the scope of claims; can do the various variation in form and details, so protection scope of the present invention is when being as the criterion with claims.

Claims (4)

1. a novel AC LED drive electric power unit, is characterized in that: it comprises that lightning protection circuit (1), pfc circuit (2), high-voltage rectifier (3), AC-LED drive circuit (4), LED lamp pearl module (5), temperature sensor (6) form, described AC power is sent into lightning protection circuit (1), PFC circuit of power factor correction (2) is sent in the output of lightning protection circuit (1), calibrated AC power is sent into high-voltage rectifier (3), direct voltage through rectification circuit (3) output is sent into LED drive circuit (4), LED lamp pearl module (5) is connected with the output of LED drive circuit (4), temperature sensor (6) is installed on LED lamp pearl module (5), LED drive circuit (4) receives the temperature signal from temperature sensor (6), automatically regulation output is to the drive current of LED lamp pearl module (5).

2. a kind of novel AC LED drive electric power unit according to claim 1, is characterized in that: lightning protection circuit (1) is by resettable fuse, form differential mode lightning protection circuit with metal-oxide varistor of alloy-type temperature fuse etc.

3. a kind of novel AC LED drive electric power unit according to claim 1, is characterized in that: the passive PFC circuit that pfc circuit (2) adopts is comprised of three diodes and two electric capacity.

4. a kind of novel AC LED drive electric power unit according to claim 1, is characterized in that: temperature sensor (6) adopts thermistor NTC, it is positioned near the LED pipe in light fixture, and for detection of the temperature of the LED pipe in light fixture,

The LED drive current of delivering to the A1-1 port controlling output of Fig. 5 by amplifier A1 output port A1-2, when temperature is raise, drive current reduces, and reduces the consumption heating amount of LED pipe, ensures the normal work of LED pipe.