CN201585165U - LED alternating-current direct power supply circuit - Google Patents

Abstract

The utility model discloses an LED alternating-current direct power supply circuit which is characterized in that an input 50Hz sine wave alternating-current is rectified into a 100Hz full wave which is added at two ends of a circuit formed by connecting an LED lamp string with a current-limiting circuit in series; the LED lamp string is equally divided into n plus 1 sections; and the voltage peak of the full wave is equally divided into n plus 1 parts by a voltage division circuit, the base electrode or gate electrode of an electronic switch is connected with the output end of the voltage division circuit, the collector electrode or drain electrode of the electronic switch is connected with all the sections of the LED lamp string, and the emitting electrode or source electrode of the electronic switch is connected with the intersection point between the LED lamp string and the current-limiting circuit. The flash-on and flash-off of each section of the LED lamp string are controlled by connecting and disconnecting the electronic switch. The service life of the LED alternating-current direct power supply circuit is far longer than that of the conventional LED driving power supply, the conversion efficiency of a power supply reaches 97%, the power factor reaches up to 0.95, the volume and the weight are far less than those of the conventional LED driving power supply.

Description

The LED alternating current (AC) directly-powered circuit

Technical field

The utility model relates to circuit design field, particularly relates to a kind of power supply circuits of led light source.

Background technology

Light-emitting diode (LED) solid light source has advantages such as luminous efficiency height, environmental protection, long-life, be described as the 5th generation lighting source.The luminous efficiency of LED can reach 186lm/W at present.

Because LED has can only forward conduction, therefore existing LED lamp all need convert alternating current to direct current by the AC/DC supply convertor and powers, and this just need use energy-storage travelling wave tubes such as electric capacity, and the life-span of electric capacity is limited.In addition, owing to need to adopt large volume o components such as electric capacity, transformer, the volume of the required power supply of LED lamp also is difficult for dwindling, and the power factor of power supply and power supply conversion efficiency are also lower.

Summary of the invention

The prior art power source life is limited, electrical source power factor is low, power supply conversion efficiency is low in order to overcome, bulky deficiency, the utility model provides a kind of LED alternating current (AC) directly-powered circuit, can reach and prolong power supply useful life, improve power-efficient, dwindle effects such as power volume.

The technical scheme that its technical problem that solves the utility model adopts is: comprise rectifier bridge, current-limiting circuit, electronic switching circuit and LED lamp string.Rectifier bridge is the 100Hz all-wave with the 50Hz sine wave AC electric rectification of input, is added in the circuit two ends that LED lamp string and current-limiting circuit are in series; The maximum operating currenbt of current-limiting circuit makes the electric current that flows through LED not exceed the limiting current that LED can bear smaller or equal to the maximum operating currenbt of LED; Electronic switch Ki (i=1 ... n, n 〉=1) employing double pole triode or field effect transistor; LED lamp string is divided into the n+1 section; Adopt bleeder circuit that the voltage peak Umax of all-wave is divided into n+1 part, the base stage of electronic switch Ki or grid connect the output of bleeder circuit

Umax, the collector electrode of electronic switch Ki or drain electrode connect the intersection point of Ki section LED lamp string and Ki+1 section LED lamp string, and the emitter of electronic switch Ki or source electrode connect the intersection point of LED lamp string and current-limiting circuit, K1, K2 ... Kn forms the turn-on and turn-off circuit.By the turn-on and turn-off of control electronic switch, control every section LED light on and off; Along with the rising of voltage U, electronic switch Ki is turn-on and turn-off successively, up to voltage peak Umax; When voltage is in

Umax extremely

In the time of between the Umax, electronic switch Ki conducting, other electronic switches turn-off; When voltage reaches

In the time of between the Umax to Umax, all electronic switches all turn-off.Along with the reduction of voltage U, electronic switch Ki conducting successively is 0 up to voltage then; When voltage is in

In the time of between the Umax to Umax, all electronic switches all turn-off, when voltage is in Umax extremely

In the time of between the Umax, electronic switch Ki conducting.When making change in voltage like this, every section voltage can both be fully utilized, and makes the voltage at every LEDs two ends not exceed its limit value all the time again simultaneously, thereby reaches the purpose that improves power utilization efficient and power factor.

Described bleeder circuit is made of 2i resistance, and per two resistance R i1 and Ri2 series connection are one group, connects the all-wave of rectifier bridge output after the parallel connection of n group series resistance by current-limiting circuit; Two resistance R i1 of i group and the resistance value ratio of Ri2 are

The base stage of electronic switch Ki or grid connect the intersection point of resistance R i1 and Ri2.

The beneficial effects of the utility model are:

1, since circuit described in the utility model all constitute by semiconductor device and resistance, without any the electric capacity of kind, thus its useful life and LED life-span be complementary, can reach more than 50,000 hours, far above the LED driving power of routine.

2, power supply conversion efficiency of the present utility model reaches 97%, is higher than the power supply conversion efficiency of existing led driver about 85%; Its power factor is better than 0.9 ± 0.05 GB draft requirement up to 0.95.

3, because circuit described in the utility model need not used transformer, inductance, electrochemical capacitor equal-volume and the bigger device of weight, therefore volume and weight of the present utility model is much smaller than conventional LED driving power, only is about 1/10 of custom circuit with the alternating current (AC) directly-powered circuit volume of power.

Below in conjunction with drawings and Examples the utility model is further specified.

Description of drawings

Fig. 1 is the utility model schematic block circuit diagram, and H is a current-limiting circuit among the figure.

Embodiment

Device embodiment: with reference to Fig. 1, whole piece LED lamp string is divided into three sections, the voltage waveform of 50Hz sine wave alternating current after the rectifier bridge rectification of input is the all-wave of 100Hz, be added in the circuit two ends that LED lamp string and current-limiting circuit are in series, the maximum operating currenbt of current-limiting circuit is smaller or equal to the maximum operating currenbt of LED.1/3 place and 2/3 place of voltage detecting point for input rated voltage established in bleeder circuit and the connection in series-parallel of LED lamp respectively, and promptly described bleeder circuit is made of 4 resistance, and resistance R 1 and R2 series connection are one group, and the resistance value ratio of resistance R 1 and R2 is 1: 3; Resistance R 3 and R4 series connection are one group, and the resistance value ratio of resistance R 3 and R4 is 2: 3; Constitute bleeder circuit after two groups of series resistance parallel connections.The base stage of triode K1 connects the intersection point of resistance R 1 and R2; The base stage of triode K2 connects the intersection point of resistance R 3 and R4.The collector electrode of triode K1 and K2 is connected 1/3 place and 2/3 place of LED lamp string respectively, and the emitter of triode K1 and K2 is connected current-limiting circuit.When input voltage rises between 0～1/3 input rated voltage scope, K1 conducting, the 1/3LED lamp string conducting that only inserts work; When input voltage rose between 1/3～2/3 input rated voltage scope, K1 turn-offed, and the K2 conducting inserts 2/3 LED conducting work this moment; After input voltage was higher than 2/3 input rated voltage, K2 turn-offed, all LED conducting work; When input voltage drops to 2/3～1/3 specified input voltage, K2 conducting, the LED conducting work of residue 2/3; When input voltage was lower than 1/3 input rated voltage scope, the K1 conducting only had 1/3 LED conducting work.By that analogy, can increase and decrease hop count.

Described triode can adopt field effect transistor to replace.

Therefore the power supply circuits of use present embodiment are along with the rising of voltage, the LED segmentation is lighted, because frequency is more than 100Hz, human eye perceives is less than flicker, circuit just can make full use of alternating current in the mode of piecewise differential like this, and after tested, power factor can reach more than 95%.

Claims (2)

1.LED alternating current (AC) directly-powered circuit, comprise rectifier bridge, current-limiting circuit, electronic switching circuit and LED lamp string, it is characterized in that: rectifier bridge is the 100Hz all-wave with the 50Hz sine wave AC electric rectification of input, is added in the circuit two ends that LED lamp string and current-limiting circuit are in series; The maximum operating currenbt of current-limiting circuit is smaller or equal to the maximum operating currenbt of LED; Electronic switch Ki adopts double pole triode or field effect transistor, i=1 ... n, n 〉=1; LED lamp string is divided into the n+1 section; Adopt bleeder circuit that the voltage peak Umax of all-wave is divided into n+1 part, the base stage of electronic switch Ki or grid connect the output of bleeder circuit

The collector electrode of electronic switch Ki or drain electrode connect the intersection point of Ki section LED lamp string and Ki+1 section LED lamp string, and the emitter of electronic switch Ki or source electrode connect the intersection point of LED lamp string and current-limiting circuit.

2. LED alternating current (AC) directly-powered circuit according to claim 1, it is characterized in that: described bleeder circuit is made of 2i resistance, per two resistance R i1 and Ri2 series connection are one group, connect the all-wave of rectifier bridge output after the parallel connection of n group series resistance by current-limiting circuit; Two resistance R i1 of i group and the resistance value ratio of Ri2 are

The base stage of electronic switch Ki or grid connect the intersection point of resistance R i1 and Ri2.

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