CN102202440A - Constant current controller which is powered by alternative current used in LED illuminating lamps - Google Patents

Abstract

The invention relates to a constant current controller which is powered by the alternative current used in LED illuminating lamps. The constant current controller comprises a power factor correction circuit and a constant current drive circuit which connect a rectifier bridge circuit and LED illuminating lamps string, wherein the power factor correction circuit has two power factor control circuits whose input terminus connect with the output terminus of the rectifier bridge circuit, the output control terminus of the two power factor control circuits respectively connects a 1/3 tandem position and a 2/3 tandem position of the LED illuminating lamps string, and the constant current drive circuit connects the LED illuminating lamps string and the rectifier bridge circuit in series connection. Through changing the quantity of LED illuminating lamps in series, the constant current controller raises the power factor in runtime. The power supply conversion efficiency of the constant current controller is greater than 95%, the power factor of the constant current controller is greater than 0.95 and the cost of the control system is reduced by 80%, thus the life of the power matches the life of the LED lamps to realize the long time use of LED illuminating lamps.

Description

The constant-current controller that the LED illuminating lamp is directly powered with AC power

Technical field

The invention belongs to the semi-conductor lighting lamp applied technical field, relate to a kind of constant-current controller that the semiconductor lamp driving power is directly powered with AC power to the LED illuminating lamp of aspects such as luminaire efficiency, life-span and cost influence that is used for solving.

Background technology

The LED lighting because have the luminous efficiency height, remarkable advantages such as power savings is obvious, the life-span is long, pollution-free, anti-vibration, be subjected to the attention of countries in the world day by day, be expected in the near future the traditional various lightings of replacement comprehensively.But also there is following some shortcomings part in actual applications in present this light fixture:

1, power supply conversion efficiency is not high: must install in the LED lighting alternating current is become galvanic constant-current driving power supply, but the efficient of this power supply is generally not high, constant-current source efficient all is lower than 85% preferably at present;

2, power source life and light source life do not match: owing to generally all be lower than 10000 hours the useful life of the electrolytic capacitor of using always in the Switching Power Supply, though the life-span of led light source can reach more than 50,000 hours, after but power supply damages, light fixture promptly can not throw light on, so the DC driven power supply also is one of restraining factors that directly influence LED light fixture useful life;

3, the power supply cost is difficult to reduce: in recent years, along with applying of LED technology, the price of led light source is also reducing significantly, but it is because higher to reliability and life requirements, so the cost of driving power is difficult to lower, the cost of driving power restricts the main bottleneck that the LED light fixture is applied near the cost of led light source so the cost of driving power has also become in the high-power illumination light fixture at present.Obviously, if the LED light fixture also as incandescent lamp, can be lighted illumination as long as add electric main, can reduce the cost of LED light fixture undoubtedly greatly, and prolong life-span of LED light fixture greatly, and also can significantly improve the operating efficiency of LED light fixture, save more electric energy.

Summary of the invention

The objective of the invention is to overcome the deficiency that prior art exists, provide that a kind of novel structure, cost are low, high efficiency, long service life, be convenient to large-scale promotion application the LED illuminating lamp with the direct constant-current controller of power supply of AC power.

Technical solution of the present invention comes from following theoretical foundation: because LED has the existence of on state threshold voltage, therefore when exchanging input, its power factor is lower, when practical application, just need to improve its power factor, spy of the present invention has for this reason increased circuit of power factor correction and constant-current drive circuit on the basis that exchanges directly driving, make it the applications that is applicable to that AC-input voltage is more stable.The LED illuminating lamp that provides according to such scheme comprises a circuit of power factor correction and constant-current drive circuit that is connected between rectifier circuit and the LED illuminating lamp string with the direct constant-current controller of powering of AC power, wherein, circuit of power factor correction has two power factor control circuits, its input connects with the output of rectifier circuit, the output control terminal of two power factor control circuits is received the 1/3 tandem position and the 2/3 tandem position of LED illuminating lamp string respectively, and constant-current drive circuit is serially connected between LED illuminating lamp string and the rectifier circuit.

Work principle of Power Factor Correction Circuit of the present invention is: when input ac voltage zero to 1/3 crest voltage when interval, the series LED illuminating lamp of conducting 1/3 only; When input ac voltage when 1/3 to 2/3 crest voltage is interval, the series LED illuminating lamp of conducting 2/3 only; When input ac voltage is higher than 2/3 crest voltage, the LED illuminating lamp that conducting is all.So can improve power factor by the quantity that changes the series LED illuminating lamp.

Constant-current drive circuit effect of the present invention is when the input voltage overrate, and the current effective value of guaranteeing to flow through the LED illuminating lamp is constant.

Compared with prior art, the present invention is directed to the technical bottleneck problem of present semiconductor lighting control power supply, proposed to optimize feasible drive controlling solution and made the constant-current driving controller, obtained technological break-through---100Hz steamed bun ripple is carried out voltage adaptive control.Through actual detected, the power supply conversion efficiency of this constant-current controller is greater than 95%, and power factor is greater than 0.95, and the control system cost reduces by 80%, makes the life-span of power source life and led light source be complementary, and has realized that the long-life of LED illuminating lamp uses.

Description of drawings

Fig. 1: the schematic diagram of work structuring principle of the present invention.

Fig. 2: the circuit structure diagram of circuit of power factor correction embodiment among the present invention.

Fig. 3: the circuit structure diagram of constant-current drive circuit embodiment among the present invention.

Embodiment

Below with reference to accompanying drawing content of the present invention is described further, but actual fabrication structure of the present invention is not limited in following embodiment.

Referring to accompanying drawing, the constant-current controller that LED illuminating lamp of the present invention is directly powered with AC power is made up of the circuit of power factor correction 3 and the constant-current drive circuit 2 that are connected between rectifier circuit 1 and the LED illuminating lamp string.

A typical circuit of circuit of power factor correction 3 as shown in Figure 2, it has comprised two power factor control circuit K1 and K2 that structure is identical, parameter is identical or close that are made of two-stage metal-oxide-semiconductor circuit, and these two power factor control circuit K1, K2 receive the 1/3 tandem position and the 2/3 tandem position of LED illuminating lamp string respectively.

Below be example with left side control circuit among Fig. 2, introduce the operation principle of this partial circuit.

In the circuit of the left side of Fig. 2, resistance R 7, R8, R24 detect the voltage (the VIN voltage waveform is the steamed bun ripple) of VIN, after the voltage on the R24 surpasses the on state threshold voltage of metal-oxide-semiconductor V7, and the V7 conducting, AC-input voltage is returned after flowing through 1/3 LED, V7, R26.U2, R26 constitute constant-current circuit to be limited the electric current that flows through this LED of 1/3.Computing formula is:

$I_{R26}=\frac{V_{\mathrm{ref}}}{R26}=\frac{2.5V}{R26}---\left(1\right)$

Vref is the reference voltage of TL431 in the formula, and the reference voltage of the TL431 that selects in this circuit is 2.5V.The resistance of regulating R26 just can change current value, and setting current value usually is 1/3 of peak current.Resistance R 5 in this circuit, R6, R17 detect the voltage of VIN, and when VIN voltage surpassed 1/3 crest voltage, the voltage on the R17 surpassed the on state threshold voltage of metal-oxide-semiconductor V1, and the V1 conducting drags down the grid voltage of V7, and V7 turn-offs.This circuit also can change the 18V voltage-stabiliser tube in resistance R 24, mainly is the grid voltage of restriction metal-oxide-semiconductor V7, prevents that grid voltage is too high and punctures.

The structure of the right control circuit and operation principle and left side circuit are identical among Fig. 2, its objective is ON time and the conducting electric current of the LED of control 2/3, and the electric current computing formula that flows through this part is identical with aforesaid formula (1).

The structure of constant-current drive circuit 2 as shown in Figure 3, it is serially connected between LED illuminating lamp string and the rectifier circuit 1.When the input voltage overrate, the current effective value that constant-current drive circuit 2 can guarantee to flow through LED is constant.

In Fig. 3 circuit structure, R13, Z1, V9 constitute accessory power supply 21, to constant-current drive circuit provide stable operating voltage about 9V (this partial circuit in fact when input voltage is comparatively stablized can, directly R14 is received LED-and gets final product).Because if 265V designs according to maximum input voltage, the change in voltage scope of V10 grid is excessive, the constant-current circuit effect that U1, V10 and R29 form is undesirable, therefore accessory power supply is set, and reaches the purpose of stablizing constant current by adding burning voltage at the V10 grid.

Form constant-current circuit 22 by U1, V10 and R29 among Fig. 3, its electric current computing formula is identical with aforesaid formula (1).Because the current waveform that flows through LED is for sinusoidal wave, so the constant current point of this constant-current circuit is the peak electricity flow point, after the peak current that flows through LED was higher than constant current point, constant-current circuit was started working, from current waveform, though peak current is limited, but the area of current waveform increases, and is reflected to be the current effective value increase on the digital watch, therefore also needs the shunt circuit of assisting, when input voltage surpasses rated voltage, reduce the electric current that flows through LED.

Form two identical shunt circuits 23,24 of function by R16, R18, R19, R22, V3, V4, Z3 and R15, R20, R21, R23, V5, V6, Z2 among Fig. 3, the voltage to the constant-current circuit two ends detects and the electric current that flows through LED is controlled respectively.Wherein, in rightmost shunt circuit 24, when AC-input voltage is less than or equal to specified input voltage, R20 provides bias voltage to V5, V5 conducting, R15 and R29 parallel connection, flow through the parallel connection value decision of the electric current of V10 by R15 and R29, when input voltage was higher than rated voltage, R21, R23 detected the voltage at constant-current circuit two ends, when this voltage is higher than set point, the V6 conducting drags down the grid voltage of V5, and V5 turn-offs, R15 is equivalent to open circuit, and the electric current that flows through V10 reduces.The grid voltage that act as protection V6 of Z2 is in safety value.The function of another shunt circuit 23 of being made up of R16, R18, R19, R22, V3, V4, Z3 and above-mentioned shunt circuit 23 are identical.

Claims (3)

1. constant-current controller that the LED illuminating lamp is directly powered with AC power, it is characterized in that comprising the circuit of power factor correction (3) and the constant-current drive circuit (2) that are connected between rectifier circuit (1) and the LED illuminating lamp string, wherein, circuit of power factor correction (3) has two power factor control circuits (K1, K2), its input connects with the output of rectifier circuit (1), and the output control terminal of two power factor control circuits (K1, K2) is received the 1/3 tandem position and the 2/3 tandem position of LED illuminating lamp string respectively; Constant-current drive circuit (2) is serially connected between LED illuminating lamp string and the rectifier circuit (1).

2. the constant-current controller that LED illuminating lamp according to claim 1 is directly powered with AC power, it is characterized in that circuit of power factor correction (3) comprises two power factor control circuit K1 and K2 that are made of two-stage metal-oxide-semiconductor circuit, their output is received the 1/3 tandem position and the 2/3 tandem position of LED illuminating lamp string respectively.

3. the constant-current controller that LED illuminating lamp according to claim 1 is directly powered with AC power is characterized in that constant-current drive circuit (2) is made up of accessory power supply (21), constant-current circuit (22) and two shunt circuits (23,24).

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