CN201742601U

CN201742601U - Stabilized power supply of light-emitting diode lamp

Info

Publication number: CN201742601U
Application number: CN2010202096862U
Authority: CN
Inventors: 莫绍祥
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-05-31
Filing date: 2010-05-31
Publication date: 2011-02-09
Anticipated expiration: 2020-05-31

Abstract

Disclosed is a stabilized power supply of a light-emitting diode lamp, which comprises a rectifying circuit, a filter capacitor and a step-down constant-current circuit, wherein the rectifying circuit comprises diodes D1-D4, a capacitor C4 is bridge-jointed between one power input point and anodes of the diodes D1, D2, and a capacitor C5 is bridge-jointed between the power input point and cathodes of the diodes D3, D4.

Description

The stabilized power supply of led lamp

Technical field

The utility model relates to the stabilized power supply of a kind of light-emitting diode (LED) light fixture.

Background technology

The LED light fixture is made up of a rectification circuit and filtering capacitor and step-down constant current circuit usually.Common rectification circuit makes light fixture can be used for exchanging and DC power supply.The step-down constant current circuit provides stabling current for light-emitting diode.

Electronic transformer is that a simple 20KHz-50KHz oscillating circuit cooperates a coil type transformer more much smaller than traditional wire wound-type transformer High Level AC Voltage to be transferred to the alternating current that is equivalent to 12V.This circuit cost is low, and a lot of 12V Halogen lamp LEDs all adopt this electronic transformer.The output of this electronic transformer is not formal sine wave, but amplitude of vibration is followed the 20KHz-50KHz concussion of instantaneous input voltage modulation.Again all can stop when too low and load current is too low at input voltage because of oscillating circuit, so actual output is a high-frequency alternating current discontinuous and wave amplitude is stable.These change the existing LED light fixture of order and reach that to cause constant current output very difficult.

When using the alternating electromotive force input, constant-current circuit is the power supply that stored by filtering capacitor for some time.Existing power source design, the crest voltage of filtering capacitor are only slightly high than the minimum normal operating voltage that constant-current circuit needs.Therefore after filtering capacitor power supply very short time, voltage just is low to moderate and is not enough to keep constant current output.LED to be because of the electric current deepening that descends, and just brightens again to filtering capacitor again until rectification circuit after a while.So periodic deepening gently then makes the light output of LED reduce, and is heavy then visible flashing occur.

In addition, discontinuous big electric current can appear in rectification circuit.To having relatively high expectations of part, and shorten life of product.

A common example, input electric power are that 12V exchanges or direct current, and every string LED is 3.The voltage of LED string is about 10V. when the 12V direct current import, and through being about 11.2V behind the bridge rectifier circuit, and the minimum normal operating voltage of constant-current circuit needs is about the LED crosstalk and presses and add 0.5V, i.e. 10.5V again.The rectification metapedes is to make the constant-current circuit normal running.But when exchanging input, crest voltage is 12Vx1.414=17V, and the crest voltage of filter capacitor is about 15V in the actual track.After alternating voltage reduced a period of time, the voltage of filter capacitor was brought down below 10.5V very soon, and LED begins deepening.When voltage was low to moderate about 9V, constant-current circuit output had been low to moderate insignificant, and the accumulate of filter capacitor remainder can not use.

Summary of the invention

The purpose of this utility model provides the stabilized power supply of a kind of light-emitting diode (LED) light fixture, be added on the conventional bridge rectifier by two capacitors, make rectification circuit that voltage multiplying rectifier is made in the interchange input of electronic transformer, the defective that prior art exists can be overcome effectively, also current peak and electromagnetic interference can be reduced by the mode that adds resistance, inductance, electric capacity.

The realization the technical solution of the utility model is: the stabilized power supply of this light-emitting diode (LED) light fixture comprises rectification circuit, filter capacitor, step-down constant-current circuit, wherein said rectification circuit comprises diode D1-D4, cross-over connection has capacitor C 4 between electric power input point and diode D1, the D2 positive pole therein, and cross-over connection has capacitor C 5 between this electric power input point and diode D3, D4 negative pole.

This technical scheme also comprises:

Be connected via resistance R 2 between described capacitor C 4 and capacitor C 5 and the described electric power input point.

Be connected via inductance L 1 between described capacitor C 4 and capacitor C 5 and the described electric power input point.

Described diode D1-D4 is a Schottky diode.

Cross-over connection input capacitance C6 between described electric power input point and the rectification circuit.

Described rectification circuit is cross-over connection resistance R 3 between end output and the described filter capacitor wherein.

Described rectification circuit is cross-over connection inductance L 3 between end output and the described filter capacitor wherein.

The beneficial effect that the utlity model has: to drive three series LEDs is example, if constant current value is 350mA, the filter capacitor that the utility model only needs 100uF (100 microfarad) just can, and existing bridge rectifier uses 220uF electric capacity not to be enough to yet keep constant current in the whole AC power cycle.

When powering with electronic transformer, the utility model reaches to a half voltage of a little higher than filter capacitor in AC-input voltage and just can make electronic transformer starting and begin the filter capacitor charging, thereby makes electronic transformer at normal output power of the long period of power-up period.Compare existing bridge rectifier, the stored electric power of filter capacitor only need be kept the short time.Therefore the filter capacitor that need not too big numerical value also can be kept always and be higher than the required voltage of constant current, and LED also keeps stable high brightness always.

The electric capacity of mentioning in this programme, resistance, and inductance can reduce current peak, also lowered electromagnetic interference and production cost simultaneously.

Description of drawings

Fig. 1 is a circuit block diagram of the present utility model.

Fig. 2 is Fig. 1 schematic diagram, wherein comprises rectification and imports voltage doubling rectifing circuit to exchanging.

Fig. 3-Fig. 4 is other rectification circuit figure of Fig. 2.

Fig. 5 is the amplitude envelope line schematic diagram of electronic transformer with High Level AC Voltage.

Fig. 6 is a LED lamp serial connection mode schematic diagram.

Among the figure: 1 rectification circuit, 2 step-down constant-current circuits, 3LED light fixture.

Embodiment

The utility model is described in further detail below in conjunction with accompanying drawing:

As shown in the figure, the utility model is made up of rectification circuit 1, step-down constant-current circuit 2, LED light fixture 3.

Operation principle

The utility model is respectively to be connected a capacitor between one of them electric power input point of bridge rectifier and bridge rectifier both positive and negative polarity, or the input point of an electric power respectively is connected a capacitor through between a resistance or inductance and bridge rectifier both positive and negative polarity therein.It then is a voltage doubling rectifing circuit for exchanging input that this circuit remains a bridge rectifier for direct current input.12V can make filter capacitor charge to about 30V when exchanging input.Constant as capacitance, when the electric power of storage is available circuit 15V 4 times.Acceptable filter capacitor voltage drop is improved to 30V-10.5V=19.5V from 15V-10.5V=4.5V.The electric power that filter capacitor stores can more mostly be used.

Be parallel to two capacitors on the diode and form series circuit at the output of rectification circuit simultaneously, therefore be equivalent to strengthen the numerical value of filter capacitor.Get big numerical value as these two electric capacity, the numerical value of filter capacitor can even not used in corresponding minimizing.As electric capacity parallel diode, promptly be equivalent to have the filter capacitor of a 110uF with two 220uF.As electric capacity parallel diode with two 10uF, add the filter capacitor of a 100uF again, promptly be equivalent to the filter capacitor of a 105uF.

Application of the present utility model

Add the capacitor of a fractional value at the input of rectification circuit, can make concussion voltage up-down speed lower and alleviate impact to commutation diode and capacitor, also can reduce electromagnetic interference.

LED lamp string is a LED or an above LED series connection basically, also can be many group LED connection in series-parallel, also can be the series and parallel combination. When many groups are in parallel, but resistance balance of every group of series connection is gone here and there required electric current.

Claims

1. the stabilized power supply of a led lamp, comprise rectification circuit, filter capacitor, step-down constant-current circuit, it is characterized in that described rectification circuit comprises diode D1-D4, cross-over connection has capacitor C 4 between electric power input point and diode D1, the D2 positive pole therein, and cross-over connection has capacitor C 5 between this electric power input point and diode D3, D4 negative pole.

2. the stabilized power supply of led lamp as claimed in claim 1 is characterized in that being connected via resistance R 2 between described capacitor C 4 and capacitor C 5 and the described electric power input point.

3. the stabilized power supply of led lamp as claimed in claim 1 is characterized in that being connected via inductance L 1 between described capacitor C 4 and capacitor C 5 and the described electric power input point.

4. the stabilized power supply of led lamp as claimed in claim 1 is characterized in that described diode D1-D4 is a Schottky diode.

5. the stabilized power supply of led lamp as claimed in claim 1 is characterized in that cross-over connection input capacitance C6 between described electric power input point and the rectification circuit.

6. the stabilized power supply of led lamp as claimed in claim 1 is characterized in that wherein cross-over connection resistance R 3 between end output and the described filter capacitor of described rectification circuit.

7. the stabilized power supply of led lamp as claimed in claim 1 is characterized in that wherein cross-over connection inductance L 3 between end output and the described filter capacitor of described rectification circuit.