Summary of the invention
The present invention provides a kind of LED lamp driving power source protective circuit, can solve the problem of the overheat protector and the short-circuit protection of LED lamp driving power source.
The present invention provides a kind of LED lamp driving power source protective circuit, comprising:
Temperature detecting unit; Temperature detecting unit comprises negative temperature coefficient resister RT, divider resistance R32, voltage-stabiliser tube Z4 and diode D6; Wherein, negative temperature coefficient resister RT connects with divider resistance R32, and the other end of negative temperature coefficient resister RT is connected to the voltage output end with burning voltage output; The other end of divider resistance R32 is connected to equipment ground; The negative electrode of voltage-stabiliser tube Z4 is connected in the series connection point of negative temperature coefficient resister RT and divider resistance R32, and the anode of voltage-stabiliser tube Z4 connects the anode of diode D6, and the negative electrode of diode D6 connects feedback control unit;
Feedback control unit is connected between the output and PWM module of LED lamp driving power source, is used for feedback signal is transmitted back the PWM module of LED lamp driving power source.
Preferably, said protective circuit also comprises a positive temperature coefficient resistor PTC, and positive temperature coefficient resistor PTC is serially connected in the output of LED lamp driving power source.
Preferably; Said voltage output end with burning voltage output is realized by resistance R 26, capacitor C 13, voltage-stabiliser tube Z3 jointly; Wherein, capacitor C 13 is parallelly connected with voltage-stabiliser tube Z3, and resistance R 26 is connected the parallelly connected point of LED lamp driving power source output and capacitor C 13 and voltage-stabiliser tube Z3; Resistance R 26 is connected the equal connection device of the other end ground of LED lamp driving power source output and capacitor C 13 and voltage-stabiliser tube Z3, and the negative electrode of voltage-stabiliser tube Z3 is as voltage output end.
Preferably; Said FEEDBACK CONTROL power supply comprises control chip U2, voltage sample resistance, current sampling resistor and optocoupler; Control chip U2 obtains the magnitude of voltage and the current value of current output through voltage sample resistance and current sampling resistor from the output of LED lamp driving power source respectively, and control chip transmits back feedback signal the PWM module of LED lamp driving power source through optocoupler.
Technique scheme can be found out, because temperature detecting unit only adopts negative temperature coefficient resister that temperature is carried out sensing in the embodiment of the invention, change in voltage is transferred to feedback control unit through voltage-stabiliser tube; Circuit structure is simple, and cost is low, and can in time transmit back the PWM module of LED lamp driving power source through feedback control unit through the change in voltage that variations in temperature causes; Has real-time control more accurately; Can effectively prevent the continuous heating of circuit and LED light fixture, and in the protective circuit of the present invention, the output of LED lamp driving power source serial connection positive temperature coefficient resistor; Avoided output current excessive further; Especially electric current excessive impact to the LED light fixture of moment during short circuit can guarantee effectively that the LED light fixture is not in time burnt yet when short circuit, have higher fail safe.
The present invention also provides a kind of LED lamp driving power source, and this power supply comprises above-mentioned LED lamp driving power source protective circuit.
Use the LED lamp driving power source of above-mentioned protective circuit in Power Operating Process, to have safer, stable performance.
Embodiment
To combine the accompanying drawing in the embodiment of the invention below, the technical scheme in the embodiment of the invention is carried out clear, intactly description, obviously, described embodiment only is the present invention's part embodiment, rather than whole embodiment.Based on the embodiment among the present invention, those of ordinary skills are not making all other embodiment that obtained under the creative work prerequisite, all belong to the scope of the present invention's protection.
Embodiment 1:
As shown in Figure 1, the embodiment of the invention provides a kind of LED lamp driving power source protective circuit, comprising:
Temperature detecting unit; Temperature detecting unit comprises negative temperature coefficient resister RT, divider resistance R32, voltage-stabiliser tube Z4 and diode D6; Wherein, negative temperature coefficient resister RT connects with divider resistance R32, and the other end of negative temperature coefficient resister RT (Port end) is connected to the voltage output end with burning voltage output; The other end of divider resistance R32 is connected to equipment ground GND; The negative electrode of voltage-stabiliser tube Z4 is connected in the series connection point of negative temperature coefficient resister RT and divider resistance R32, and the anode of voltage-stabiliser tube Z4 connects the anode of diode D6, and the negative electrode of diode D6 connects feedback control unit;
Feedback control unit is connected between the output and PWM module of LED lamp driving power source, is used for feedback signal is transmitted back the PWM module of LED lamp driving power source.
Particularly; As shown in Figure 2, said voltage output end with burning voltage output realized by resistance R 26, capacitor C 13, voltage-stabiliser tube Z3 jointly, wherein; Capacitor C 13 is parallelly connected with voltage-stabiliser tube Z3; Resistance R 26 is connected the parallelly connected point of LED lamp driving power source output and capacitor C 13 and voltage-stabiliser tube Z3, and resistance R 26 is connected the equal connection device of the other end ground of LED lamp driving power source output and capacitor C 13 and voltage-stabiliser tube Z3, and the negative electrode of voltage-stabiliser tube Z3 is as voltage output end (being that Port holds).
Below in conjunction with Fig. 1, Fig. 2 the operation principle of the LED lamp driving power source protective circuit in the embodiment of the invention is made concrete introduction.
At first; Negative temperature coefficient resister RT is as the temperature monitoring point of this protective circuit; Negative temperature coefficient resister RT is arranged on the heat dissipation equipment place of LED light fixture or heat radiation place of driving power, and negative temperature coefficient resister RT just can be in time detects the temperature of LED light fixture or driving power like this; It is understandable that; When the electric current exported in the driving power increased, driving power itself and all can be caused heating owing to the lifting of electric current by the LED light fixture of driving power power supply was monitored when guaranteeing the temperature to driving power and LED light fixture; Two negative temperature coefficient resisters are set in the temperature detecting unit; The series connection of two negative temperature coefficient resisters is connected between divider resistance R32 holds with Port among Fig. 1 then, and the negative temperature coefficient resister that promptly is equivalent to the negative temperature coefficient resister RT among Fig. 1 is split into two series connection is connected in the circuit; One of them negative temperature coefficient resister is arranged on heat radiation place of driving power; As the point of the monitoring temperature in the driving power, another negative temperature coefficient resister is arranged on the heat abstractor place of LED light fixture, as the monitoring temperature point of LED light fixture.
Since the output (LED+ end) of LED lamp driving power source pass through resistance R 26 with voltage distribution to voltage-stabiliser tube Z3; The interference signal of capacitor C 13 in can the filtering circuit; Prevent the interference of interference signal, can obtain stable voltage output, and export burning voltage to negative temperature coefficient resister RT through the Port end at the negative electrode of voltage-stabiliser tube Z3 to negative temperature coefficient resister RT; Therefore; When negative temperature coefficient resister RT sensed the temperature rising of driving power or LED light fixture, the resistance of negative temperature coefficient resister RT can reduce, thereby the dividing potential drop on the negative temperature coefficient resister RT also reduces thereupon; Dividing potential drop on the divider resistance R32 of series connection then increases thereupon with it; After the puncture voltage of the voltage on the divider resistance R32 greater than voltage-stabiliser tube Z4, voltage-stabiliser tube Z4 is breakdown, and the dividing potential drop on the divider resistance R32 just transfers to feedback control unit through voltage-stabiliser tube Z4 and diode D6; Choosing of the reverse breakdown voltage value of voltage-stabiliser tube Z4 is corresponding with the protection value of temperature detection; If choosing then high more of the reverse breakdown voltage value of promptly high more for the temperature protection value of driving power then voltage-stabiliser tube Z4, diode D6 can prevent the voltage or anti-degree of the rising again detecting unit of irritating of electric current of connected feedback control unit, and All other routes are impacted; It is understandable that; Feedback control unit is connected with the PWM module of LED lamp driving power source; After feedback control unit receives the change in voltage on the temperature detecting unit; Change in voltage on the feedback control unit temperature detecting unit is converted into the PWM module that the corresponding feedback signal transfers to the LED lamp driving power source, and the PWM module is adjusted the output voltage of LED lamp driving power source through relatively inner.
The protective circuit of LED lamp driving power source has only adopted negative temperature coefficient resister RT as temperature detecting point in the embodiment of the invention; And with the height of voltage-stabiliser tube Z4 limit temperature detected value, with respect to existing driving power protective circuit, the device of use significantly reduces; Simple in structure being easy to realized; And variations in temperature is converted into the PWM module that change in voltage is transmitted back driving power through feedback control unit, and further utilized feedback control unit, improved the utilance of device.
Embodiment 2:
As shown in Figure 3, in the embodiment of the invention, LED lamp driving power source protective circuit also comprises a positive temperature coefficient resistor PTC, and positive temperature coefficient resistor PTC is serially connected in the output (LED+ end) of LED lamp driving power source.When the output of LED lamp driving power source is short-circuited, can produce bigger electric current at the LED+ end and change, electric current can draw high rapidly; And existing LED lamp driving power source adopts feedback control unit that output is detected more, and promptly feedback control unit carries out current sample through current sampling resistor to the output of LED lamp driving power source, when output end current is excessive; Feedback control unit obtains current changing signal from current sampling resistor, and feeds back to the PWM module of LED lamp driving power source, by the PWM module to the output of power supply make adjustment (closing working power); But; This control mode has certain hysteresis quality, is that output has produced big electric current and just carries out FEEDBACK CONTROL, is unfavorable for very first time protection LED light fixture; Therefore; The embodiment of the invention is at output (LED+ end) the serial connection positive temperature coefficient resistor PTC of LED lamp driving power source, when the LED+ end produces than big electric current, during like short circuit current; Electric current increases at ordinary times just 2~3 times of constant; The electric current that this moment, positive temperature coefficient resistor PTC flow through is 2~3 times of load current value, make positive temperature coefficient resistor PTC persistent fever cause himself resistance rising, and then short circuit current decline also keeps high-impedance state always.After the unshorting phenomenon; But the LED lamp driving power source is operate as normal again; Even the PWM module of the signal back LED lamp driving power source that the LED lamp driving power source so in the embodiment of the invention in time increases electric current at feedback control unit, positive temperature coefficient resistor PTC also can guarantee that the electric current of LED+ end drops to safe range in the very first time.
The FEEDBACK CONTROL power supply comprises control chip U2, voltage sample resistance, current sampling resistor and optocoupler in the embodiment of the invention; Control chip U2 obtains the magnitude of voltage and the current value of current output through voltage sample resistance and current sampling resistor from the output of LED lamp driving power source respectively, and control chip transmits back feedback signal the control end of the PWM module of LED lamp driving power source through optocoupler.Particularly, as shown in Figure 3, R30, C16; R27, R23, R29 forms the constant current testing circuit; Voltage sample resistance comprises R24, R25, and the dividing potential drop on the resistance R 24 is transferred to control chip U2, R30 as sampled voltage; C16, R27, R23; R29 forms the constant current testing circuit, and current sampling resistor R23, R27, R29 convert sample rate current into voltage transmission and give control chip U2, and control chip U2 does comparison to the voltage reference voltage inner with it that sampled voltage and/or sample rate current are changed; And then the size of the voltage at the two ends, the former limit of optocoupler OP1 that link to each other with control chip U2 of control, thereby realize control, the final PWM module that realizes feedback signal is transmitted back the LED lamp driving power source to optocoupler OP1 secondary voltage.
LED lamp driving power source protective circuit is under the cooperation of feedback control unit and positive temperature coefficient resistor PTC of control chip the LED lamp driving power source to be protected at temperature detecting unit 301, with U2 in the embodiment of the invention; Can realize overheat protector and short-circuit protection, make LED lamp driving power source safety and stability more.
Embodiment 3:
As shown in Figure 4, the LED lamp driving power source in the embodiment of the invention comprises voltage input circuit 401, rectification circuit 402, pwm control circuit 403, output rectification circuit 404, output constant-current and constant-voltage control circuit, short-circuit protection and thermal-shutdown circuit composition.And having comprised the foregoing description 1 or embodiment 2 described LED lamp driving power source protective circuits, output crossing current constant-voltage control circuit is realized with feedback control circuit in the foregoing description, and is significant to the safe and stable operation of whole power supply.
In the input circuit assembly, increase piezo-resistance VR1 in case surge (Surge) surging in the system electrical network damages the switch MOS pipe.Piezo-resistance VR1 can clamper arrive certain voltage levvl when running into the interference of surge surging, avoid switch MOS pipe and IC element etc. to bear too high voltages and damage.
In rectification circuit, CBB (polypropylene) electric capacity that behind rectifier bridge, need add a low capacity leaches clutter and anti-interference, needs according to power supply designed output power decision filter capacitor capacity, and reasonably the electric capacity value can effectively improve PF and antijamming capability.
Pwm chip adopts traditional CRM non-continuous mode boost control chip; Through feed back to elementary PWM chip U1 internal comparator end with the secondary voltage current sampling; PWM chip U1 compares the sampling of input voltage waveform simultaneously, controls output Gate voltage width and frequency to follow the tracks of input voltage waveform, and control switch metal-oxide-semiconductor break-make; Make transformer by certain frequency and pulsewidth work; And then voltage coupling outputed to secondary transformer, and just can the driving LED load after rectification, form promptly have PF proofread and correct again can voltage of transformation circuit.
Can know that by Fig. 4 the LED lamp driving power source in the embodiment of the invention adopts implements 2 described LED lamp driving power source protective circuits, and the overheat protector and the short-circuit protection of power supply are given security.
Single-stage PFC (Power Factor Correction power factor circuit) power supply structure design that the embodiment of the invention is released and the LED driving power of producing adopt single transformer to accomplish active power factor calibration APFC (Active Power Factor Correction) and voltage transformation.Promptly adopt a transformer just to realize power factor correction and voltage transformation, element is few, and it is little to take sky PCB space, and power supply complete machine cost is low, and can handle requirements such as safety safety well.
U.S.'s " Energy Star " is to Valuation Standard (the ENERGY STAR Program Requirements for Integral LED Lamps ENERGY STAR Eligibility Criteria of LED driving power; 3; 2009) regulation; Power factor under the civilian and commercial condition is not less than 0.7 and 0.9 respectively, and this is to get into the unalterable quota that American market must reach.The LED driving power power factor of APFC power supply structure of the present invention reaches 0.996 (promptly 99.6%), is superior to U.S.'s " Energy Star " standard.
More than LED lamp driving power source protective circuit and LED lamp driving power source that the embodiment of the invention provided have been carried out detailed introduction; Used concrete example among this paper principle of the present invention and execution mode are set forth, the explanation of above embodiment just is used for helping to understand method of the present invention and core concept thereof; Simultaneously, for one of ordinary skill in the art, according to thought of the present invention, the part that on embodiment and range of application, all can change, in sum, this description should not be construed as limitation of the present invention.