CN101511136A - Current balance power supply circuit of multiple groups of light emitting diodes - Google Patents

Abstract

The invention relates to a current balance power supply circuit of a plurality of groups of light-emitting diodes, which is used for driving the plurality of groups of light-emitting diodes so as to ensure that the brightness of each group of light-emitting diodes is the same. The current balance power supply circuit at least comprises: the current supply circuit is used for receiving a power supply and converting the power supply into a current with a specific current magnitude so as to provide the current for the plurality of groups of light-emitting diodes; the current equalizing circuit is connected with the output of the current supply circuit and the plurality of groups of light-emitting diodes in series and comprises at least one coupling inductor for balancing the current of the plurality of groups of light-emitting diodes; and the current control unit is connected with the current supply circuit and at least one group of light-emitting diodes in the plurality of groups of light-emitting diodes and is used for detecting the current of the plurality of groups of light-emitting diodes and controlling the output current of the current supply circuit. The invention can balance the current of each group of light-emitting diodes and has the same brightness, the circuit has small power loss and high operating efficiency, relatively few elements and low circuit complexity, and greatly saves the cost.

Description

Current balanced power supply circuit for multiple groups of light-emitting diodes

technical field

The invention relates to a power supply circuit, in particular to a current balanced power supply circuit for multiple groups of light emitting diodes.

Background technique

In recent years, due to breakthroughs in light-emitting diode (Light Emitting Diode, LED) manufacturing technology, the luminous brightness and luminous efficiency of light-emitting diodes have been greatly improved, so light-emitting diodes have gradually replaced traditional lamps and become new lighting components, and are widely used in household lighting such as Devices, automotive lighting devices, hand-held lighting devices, LCD panel backlight, traffic signal lights, sign boards and other lighting applications.

In the application of multiple light-emitting diodes, since the characteristics of each light-emitting diode are different from each other, the magnitude of the current flowing through each light-emitting diode is not the same, which not only leads to the electronic devices using light-emitting diodes, such as liquid crystal display panels, Inhomogeneity will also greatly reduce the service life of individual light emitting diodes, thereby causing damage to the entire electronic device.

In order to improve the problem of uneven LED current, many LED current balancing techniques have been used to improve this defect. U.S. Patent No. US6,621,235 discloses a current balanced power supply circuit for multiple groups of LEDs. As shown in FIG. 1, the traditional current balanced power supply circuit includes a linear regulator 11 (linear regulator), a low-pass filter 12 and A plurality of current mirrors M ₁ -M _n . Wherein, the reference current I _ref connected to the first input terminal of the linear voltage regulator 11 is a constant current, which is used to control the linear voltage regulator 11 to generate a corresponding output voltage to the low-pass filter 12 for filtering by the low-pass filter 12 Then output to the gate terminals of the current mirrors M ₁ ~ M _n , so that each current mirror M ₁ ~ M _n outputs the same current, therefore, each group of light-emitting diodes connected to the current mirrors M ₁ ~ M _n has the same current and luminance.

However, the conventional current balance power supply circuit of multiple groups of LEDs uses a linear voltage regulator and a current mirror, resulting in large power loss and low operating efficiency of the circuit, relatively more components are used and the circuit is more complicated. Therefore, how to develop a current balance power supply circuit for multiple groups of light emitting diodes that can improve the above-mentioned defects of the prior art is an urgent problem for those in the relevant technical field to solve.

Contents of the invention

The main purpose of the present invention is to provide a current balanced power supply circuit for multiple groups of LEDs, which uses a circuit structure different from the traditional power supply circuit for multiple groups of LEDs, so that the current of each group of LEDs is balanced and the luminous brightness is the same, and the circuit The power loss is small and the operating efficiency of the circuit is high, relatively few components are used and the circuit complexity is low, and the cost can be greatly saved.

To achieve the above purpose, a broad embodiment of the present invention provides a current balance power supply circuit for multiple groups of LEDs, which is used to drive multiple groups of LEDs so that the luminance of each group of LEDs is substantially the same. The current balance power supply circuit of the multiple sets of light emitting diodes at least includes: a current supply circuit, which is used to receive power and convert it into a current with a specific current magnitude, so as to provide the multiple sets of light emitting diodes; a current equalizing circuit, and the output of the current supply circuit terminal and the plurality of groups of light emitting diodes are connected in series, and the current sharing circuit includes at least one coupled inductor to balance the current of the plurality of groups of light emitting diodes; and a current control unit is connected to the current supply circuit and the plurality of groups of light emitting diodes At least one group of light emitting diodes is used to detect the magnitude of the current of the plurality of groups of light emitting diodes and control the output current of the current supply circuit.

The above-mentioned current balance power supply circuit may further include: a plurality of rectifiers, respectively connected in series with the output end of the current power supply circuit, the current equalizing circuit and the plurality of groups of light emitting diodes.

In the above current balance power supply circuit, the plurality of rectifiers can be connected in series between the output end of the current supply circuit and the current equalizing circuit, or between the current equalizing circuit and the plurality of groups of light emitting diodes.

The above-mentioned current balance power supply circuit may further include: a power rectification circuit connected to the input end of the current power supply circuit for receiving AC power and converting the power to the current power supply circuit.

The above-mentioned current balance power supply circuit may further include: a filter circuit connected to the input end of the current power supply circuit.

The above current balanced power supply circuit may further include: a plurality of capacitors respectively connected to the plurality of groups of light emitting diodes.

In the above-mentioned current balance power supply circuit, the current power supply circuit may at least include: a switch circuit, including at least one switch element, connected to the current control unit and the input end of the current power supply circuit; and a transformer, including a primary winding and multiple sets of secondary winding, the primary winding is connected to the switch circuit and the input end of the current supply circuit.

In the above current balance power supply circuit, the switch circuit may be composed of a first switch element, the current control unit controls the first switch element to be turned on or off, so as to transmit the power to the multiple sets of secondary windings of the transformer, and wherein Each of the multiple sets of secondary windings of the transformer has the same turns ratio as the primary winding.

In the above current balance power supply circuit, the switch circuit may include a second switch element, a third switch element, a resonant inductor, and a resonant capacitor, wherein the second switch element and the third switch element are respectively connected to the current control unit and the current power supply The input end of the circuit is connected and connected in series at a series point, and the resonant inductance and the resonant capacitor are connected in series between the series point and the primary winding of the transformer.

In the above current balance power supply circuit, the current control unit can control the second switch element and the third switch element to be turned on or off alternately, so as to transmit the power to the multiple sets of secondary windings of the transformer, and wherein the Each of the multiple sets of secondary windings of the transformer has a center tap and is connected to a common node.

In the above-mentioned current balance power supply circuit, the current sharing circuit may have a coupling inductor, and the coupling inductor has a plurality of inductors, and the plurality of inductors in the coupling inductor are respectively connected in series with the multiple groups of light emitting diodes correspondingly.

In the above-mentioned current balance power supply circuit, the current sharing circuit may include multiple sets of inductors, and each set of inductors includes multiple inductors.

In the above-mentioned current balance power supply circuit, the plurality of inductance groups may at least include a first group of inductance groups and a second group of inductance groups, wherein the number of multiple inductors in the first group of inductance groups is the same as the number of groups of the plurality of groups of light emitting diodes The same, and the plurality of inductors in the first group of inductors are respectively connected in series with the plurality of groups of light emitting diodes.

In the above current balance power supply circuit, the first group of inductors may include one or more coupled inductors.

In the above current balance power supply circuit, the number of inductors in the second group of inductors may be smaller than the number of inductors in the first group of inductors.

In the above current balance power supply circuit, the second group of inductors may include one or more coupled inductors.

In the above-mentioned current balance power supply circuit, each inductor in the plurality of inductors of the first group of inductors can respectively form a current loop corresponding to each group of LEDs in the plurality of groups of LEDs.

In the above current balance power supply circuit, each inductor in the second group of inductors can be connected in series with some inductors in the first group of inductors.

In the above current balance power supply circuit, the multiple sets of inductor groups may further include a third set of inductor groups, the third set of inductor groups includes a coupled inductor, and the coupled inductor has two inductors.

In the above current balance power supply circuit, the two inductors in the third group of inductors can be connected in series with the first inductor and the last inductor in the first group of inductors respectively.

In the above-mentioned current balance power supply circuit, each group of LEDs in the multiple groups of LEDs may have a plurality of LEDs respectively.

In the above-mentioned current balance power supply circuit, the output current of the current power supply circuit may be a pulsed current.

The invention can make the current balance of each group of light emitting diodes and the same luminance, the circuit power consumption is small, the operating efficiency is high, the components are relatively few, the circuit complexity is low, and the cost is greatly saved.

Description of drawings

Figure 1 is a traditional light-emitting diode current balance power supply circuit.

FIG. 2A is a schematic circuit block diagram of a current balancing power supply circuit for multiple sets of LEDs according to a preferred embodiment of the present invention.

FIG. 2B is a schematic circuit block diagram of a current balance power supply circuit for multiple sets of LEDs according to another preferred embodiment of the present invention.

FIG. 3 is a schematic diagram of the detailed circuit structure of the current balance power supply circuit for multiple sets of LEDs shown in FIG. 2A .

FIG. 4 is a schematic circuit diagram of a current balance power supply circuit for multiple sets of LEDs in another preferred embodiment of the present invention.

FIG. 5 is a schematic circuit diagram of an exemplary current sharing circuit of a current balancing power supply circuit for multiple groups of LEDs according to a preferred embodiment of the present invention.

FIG. 6 is a schematic circuit diagram of an exemplary current sharing circuit of a current balancing power supply circuit for multiple sets of LEDs according to another preferred embodiment of the present invention.

FIG. 7 is a schematic circuit diagram of another exemplary current sharing circuit of the embodiment shown in FIG. 6 .

FIG. 8 is a schematic circuit diagram of an exemplary current sharing circuit of a current balancing power supply circuit for multiple groups of LEDs according to another preferred embodiment of the present invention.

FIG. 9 is a schematic circuit diagram of another variation of the embodiment shown in FIG. 8 .

Wherein, the reference signs are explained as follows:

11: Linear voltage regulator 12: Low-pass filter

2: Current balance power supply circuit for multiple groups of light-emitting diodes

21: Current supply circuit 211: Switching circuit

22: Current sharing circuit 23: Current control unit

24: Power rectifier circuit 25: Filter circuit

V ₁ : Power supply V _in : AC power supply

D ₁ ～D _n : Rectifier G _1a ～G _nb : Light emitting diode

C ₁ ～C _n : capacitance C _in : input capacitance

T ₁ : First Transformer T ₂ : Second Transformer

N ₁₁ , N ₂₁ : primary winding N ₁₂ , N ₂₂ : first secondary winding

N ₁₃ , N ₂₃ : second secondary winding M ₁ ~M _n : current mirror

Q ₁ : First switching element Q ₂ : Second switching element

Q ₃ : Third switching element L _r : Resonant inductance

C _r : Resonant capacitance k: Series point

L _ca , L _cb , L _cc : coupled inductance L _ca1 , L _cb1 : first inductance

L _ca2 , L _cb2 : the second inductance L _ca3 : the third inductance

L _ca4 : Fourth inductance

Detailed ways

Some typical embodiments embodying the features and advantages of the present invention will be described in detail in the description in the following paragraphs. It should be understood that the present invention is capable of various changes in different aspects without departing from the scope of the present invention, and that the description and drawings therein are illustrative in nature and not intended to limit the present invention.

The current balanced power supply circuit for multiple groups of LEDs of the present invention is used for multiple groups of LEDs, and each group of LEDs can have multiple LEDs. The following will illustrate by taking each group of LEDs with two LEDs as an example. . Please refer to FIG. 2A , which is a circuit block diagram of a current balancing power supply circuit for multiple sets of LEDs in a preferred embodiment of the present invention. As shown in FIG. 2A , the current balance power supply circuit 2 of multiple groups of LEDs at least includes a current power supply circuit 21, a current equalizing circuit 22 and a current control unit 23, wherein the current power supply circuit 21 is used to receive a power supply V ₁ , such as a DC power supply, and The electric current converted into a specific current magnitude is provided to multiple groups of LEDs G _1a -G _nb , wherein n represents the number of groups, and a and b respectively represent the first LED and the second LED in the group. The current equalizing circuit 22 includes at least one coupled inductor, which is connected in series with the output end of the current supply circuit 21 and the LEDs G _1a -G _nb for balancing the current of the LEDs G _1a -G _nb . The current control unit 23 is connected to the current supply circuit 21 and at least one group of light-emitting diodes among the multiple groups of light-emitting diodes _G1a - _Gnb , and is used to detect the magnitude of the current of the multiple groups of light-emitting diodes _G1a - _Gnb and control the current supply circuit 21. output current, in this embodiment, the current control unit 23 is connected in series with, for example, the first group of light-emitting diodes G _1a -G _1b among multiple groups of light-emitting diodes G _1a -G _nb , so as to detect the current magnitude of one group of light-emitting diodes, and then Control the magnitude of the current flowing through multiple groups of light emitting diodes G _1a -G _nb . In some embodiments, the current supply circuit 21 may be, for example, an isolated or non-isolated current supply circuit, but not limited thereto.

In some embodiments, the current balanced power supply circuit 2 for multiple groups of LEDs of the present invention further includes a plurality of rectifiers D ₁ -D _n , a power rectification circuit 24 , a filter circuit 25 and a plurality of capacitors C ₁ -C _n , among which a plurality of The rectifiers D ₁ -D _n can be, for example, diodes, which are respectively connected in series with the output end of the current supply circuit 21, the current equalizing circuit 22 and multiple groups of light emitting diodes G _1a -G _nb , so that the output current direction of the current supply circuit 21 is a single direction , for example, from the current supply circuit 21 to multiple groups of light emitting diodes G _1a ~ G _nb , in addition, in some variations, the connection polarity of one or more rectifiers among the multiple rectifiers D ₁ ~ D _n can be changed, and the phase The corresponding single or multiple groups of light emitting diodes G _1a -G _nb also change their connection polarities at the same time, so as to adjust the current direction of each group of light emitting diodes separately or simultaneously.

The power rectification circuit 24 is connected to the input terminal of the current supply circuit 21, and is used to receive the AC power supply V _in and convert it into a power supply V ₁ acceptable to the current supply circuit 21, such as a DC voltage, to provide the current supply circuit 21. In some embodiments, the power rectification circuit 24 also has a power factor correction function. The filter circuit 25 is connected to the output end of the power rectification circuit 24 for filtering unnecessary high-frequency noise. A plurality of capacitors C ₁ -C _n are respectively connected to each corresponding group of light emitting diodes G _1a -G _nb . In this embodiment, as shown in FIG. 2A , a plurality of rectifiers D ₁ -D _n are respectively connected in series between the output terminal of the current supply circuit 21 and the current equalizing circuit 22 . Of course, in other embodiments, as shown in FIG. 2B As shown, a plurality of rectifiers D ₁ -D _n can also be connected in series between the current equalizing circuit 22 and the corresponding sets of light emitting diodes G _1a -G _nb respectively.

Please refer to FIG. 3 , which is a schematic diagram of a detailed circuit structure of the current balance power supply circuit for multiple sets of LEDs shown in FIG. 2A . As shown in FIG. 3 , the current supply circuit 21 can be, for example, an isolated current supply circuit and at least includes an input capacitor C _in , a switch circuit 211 and a first transformer T ₁ , wherein the input capacitor C _in is connected to the input terminal of the current supply circuit 21 . The switch circuit 211 is connected to the input capacitor C _in , the current control unit 23 , the input terminal of the current supply circuit 21 and the primary winding N ₁₁ of the first transformer T ₁ , wherein the switch circuit 211 is composed of at least one switch element, and is controlled by the current Unit 23 controls its operation. In this embodiment, the switching circuit 211 is composed of the first switching element _Q1 , and the current control unit 23 controls the first switching element _Q1 to be turned on or off, so as to transmit the electric energy of the power supply _V1 to the second The first secondary winding N ₁₂ and the second secondary winding N ₁₃ of a transformer T ₁ , therefore, the first secondary winding N ₁₂ and the second secondary winding N ₁₃ of the first transformer T ₁ will sense and output pulses such as Since the turn ratio of the first secondary winding N ₁₂ to the primary winding N ₁₁ is the same as the turn ratio of the second secondary winding N ₁₃ to the primary winding N ₁₁ , the first turn ratio of the current supply circuit 21 The first output terminal and the second output terminal, that is, the first secondary winding N ₁₂ and the second secondary winding N ₁₃ induce and output currents in the form of pulses with similar magnitudes.

In this embodiment, the current sharing circuit 22 is composed of at least one first coupling inductance L _ca , and the first coupling inductance L _ca has a plurality of inductances, such as a first inductance L _ca1 and a second inductance L _ca2 , wherein the first inductance L _ca1 is connected in series with the first output terminal among the multiple output terminals of the current supply circuit 21 , the first rectifier D ₁ and the first group of LEDs G _1a -G _1b to form a first current loop. The second inductor L _ca2 is connected in series with the second output terminal of the current supply circuit 21 , the second rectifier D ₂ and the second group of light emitting diodes G _2a -G _2b to form a second current loop. Utilizing the current equalizing circuit 22 makes the current flowing through the first group of LEDs G _1a -G _1b and the second group of LEDs G _2a -G _2b substantially the same. In some embodiments, the current balancing power supply circuit 2 for multiple groups of LEDs of the present invention further includes multiple capacitors, for example, capacitors connected to the first group of LEDs G _1a -G _1b and the second group of LEDs G _2a -G _2b respectively The first capacitor C ₁ and the second capacitor C ₂ .

Please refer to FIG. 4 , which is a schematic circuit diagram of a current balance power supply circuit for multiple groups of LEDs according to another preferred embodiment of the present invention. As shown in FIG. 4, in this embodiment, the current equalizing circuit 22, the current control unit 23, the multiple rectifiers D ₁ -D ₄ and the multiple capacitors C ₁ -C ₂ of the current balance power supply circuit 2 of multiple LEDs The architecture, functions and principles are similar to those of the embodiment shown in FIG. 3 , so details are not repeated here. However, the current supply circuit 21 adopts a different circuit architecture and includes a switch circuit 211, the switch circuit 211 is composed of a second switch element _Q2 , a third switch element _Q3 , a resonant inductor _Lr and a resonant capacitor _Cr , wherein the second The switch element _Q2 and the third switch element _Q3 are connected in series with the input terminal of the current supply circuit 21 and the input capacitor C _in through the series connection point k, and the connection between the connection point k and the primary winding _N21 of the second transformer _T2 Then, the resonant inductor L _r and the resonant capacitor C _r are connected in series to reset the unbalanced energy generated when the second switch element _Q2 and the third switch element _Q3 are turned on and off. The switching circuit 211 of this embodiment similarly controls the operation of the current supply circuit 21 through the current control unit 23. In this embodiment, the current control unit 23 controls the second switching element _Q2 and the third switching element _Q3 to alternately conduct is turned on or off, so as to transmit the electric energy of the power supply V ₁ to the first secondary winding N ₂₂ and the second secondary winding N ₂₃ of the second transformer T ₂ in the form of pulses, for example. Although, the turns ratio of the first secondary winding N ₂₂ to the primary winding N ₂₁ of the second transformer T ₂ is the same as the turns ratio of the second secondary winding N ₂₃ to the primary winding N ₂₁ , and the second transformer T ₂ The first secondary winding N ₂₂ and the second secondary winding N ₂₃ will also induce and output currents in the form of pulses with similar magnitudes, however, the first secondary winding N ₂₂ of the second transformer T ₂ and the second secondary winding N ₂₃ has a center tap (center tap) and is connected to a common contact, therefore, the first secondary winding N ₂₂ and the second secondary winding N ₂₃ of the second transformer T ₂ will induce and output output currents of different polarities at different times . In this embodiment, the two ends of the first secondary winding N ₂₂ of the second transformer T ₂ are respectively connected in series with the first rectifier D ₁ and the second rectifier D ₂ , and the two ends of the second secondary winding N ₂₃ are respectively connected in series with The third rectifier D ₃ and the fourth rectifier D ₄ make the current direction of the current supply circuit 21 output to the first group of light emitting diodes G _1a ~ G _1b and the second group of light emitting diodes G _2a ~ G _2b fixed, that is, for the second The output current of the first secondary winding N ₂₂ and the second secondary winding N ₂₃ of the transformer T ₂ is rectified. Wherein, the first inductance L _ca1 of the current equalizing circuit 22 forms a first current loop with the first group of light emitting diodes G _1a -G _1b , and the second inductance L _ca2 forms a second current loop with the second group of light emitting diodes G _2a -G _2b circuit. The current equalizing circuit 22 is also respectively connected to the first group of light emitting diodes G _1a -G _1b of the first current loop and the second group of light emitting diodes G _2a -G _2b of the second current loop, and the first capacitor C ₁ and the second capacitor C ₂ is also connected to the first group of light emitting diodes G _1a -G _1b and the second group of light emitting diodes G _2a -G _2b respectively.

Please refer to FIG. 5 , which is a schematic circuit diagram of an exemplary current sharing circuit of a current balancing power supply circuit for multiple sets of LEDs according to a preferred embodiment of the present invention. Taking the current balanced power supply circuit 2 of multiple groups of light-emitting diodes of the present invention applied to drive, for example, four groups of light-emitting diodes _G1a - _G4b as an example, as shown in _FIG . G _4b , the current sharing circuit 22 is composed of a first group of inductance groups and a second group of inductance groups, wherein the first group of inductance groups is composed of a first coupling inductance L _ca with four inductances (in the first coupling inductance L _ca The number of inductances is the same as the total number of groups of light-emitting diodes), and the number of inductances in the second group of inductance groups is two, which is relatively less than the number of inductances in the first group of inductance groups (in the second group of inductance groups The number of inductors = the number of inductors in the first group of inductors - 2). In this embodiment, the second group of inductors consists of a second coupled inductor L _cb with two inductors. Each inductance in the first group of inductance groups will respectively form a current loop corresponding to each group of light-emitting diodes. Each group of LEDs and each rectifier. In this embodiment, the first inductance L _ca1 , the second inductance L _ca2 , the third inductance L _ca3 and the fourth inductance L _ca4 in the first group of inductances form the first current loop, the second current loop, and the third inductance respectively. The current loop and the fourth current loop, and each current loop is connected in series with the corresponding first group of light emitting diodes G _1a ~ G _1b , the second group of light emitting diodes G _2a ~ G _2b , and the third group of light emitting diodes G _3a ~ G _3b , the fourth group of light emitting diodes G _4a -G _4b , the first rectifier D ₁ , the second rectifier D ₂ , the third rectifier D ₃ and the fourth rectifier D ₄ . Each inductance in the second group of inductance groups is connected in series with the partial inductances of the first group of inductance groups respectively. In this embodiment, the first inductance L _cb1 in the second group of inductance groups is connected with The second inductance L _ca2 in the first inductance group is connected in series, and the second inductance L _cb2 in the second inductance group is connected in series with the third inductance L _ca3 in the first inductance group on the third current loop.

Please refer to FIG. 6 , which is a schematic circuit diagram of a current sharing circuit according to another preferred embodiment of the present invention. As shown in FIG. 6, the current equalizing circuit 22 is respectively connected to n groups of light-emitting diodes G _1a -G _nb . The current equalizing circuit 22 is composed of multiple groups of inductance groups, for example, x groups of inductance groups (wherein x is a positive value greater than 2. Integer), wherein the first group of inductance groups includes a first coupled inductance L _ca with n inductances (the number of inductances in the first coupled inductance L _ca is the same as the total number of groups of light-emitting diodes), and the second group The number of inductances in the inductance group is less than the number of inductances in the first group of inductance groups (the number of inductances in the second group of inductance groups=the number of inductances in the first group of inductance groups-2), and can be formed by a coupling inductor (as shown in the figure 6) or multiple coupled inductors (as shown in Figure 7). By analogy, the number of inductors in the x-th group of inductors is less than the number of inductors in the previous (x-1) group of inductors, and similarly can also be composed of one or more coupled inductors. In the embodiment shown in FIG. 6, each inductor group is composed of a coupled inductor. Wherein, each inductance of the first group of inductance groups will form a current loop with each corresponding group of light-emitting diodes, and the number of current loops is n which is the same as the total number of multiple groups of light-emitting diodes, and each current loop is respectively Each group of corresponding LEDs and each rectifier are connected in series. Except for the first group of inductance groups, each inductance of each group of inductance groups will be connected in series with part of the corresponding inductance group in the previous group of inductance groups. The manner is similar to the embodiment shown in FIG. 5 , and will not be repeated here.

Please refer to FIG. 8 , which is a schematic circuit diagram of an exemplary current sharing circuit of a current balancing power supply circuit for multiple groups of LEDs according to another preferred embodiment of the present invention. As shown in FIG. 8 , the current equalizing circuit 22 is respectively connected to n groups of light-emitting diodes G _1a -G _nb , and the current equalizing circuit 22 is composed of two groups of inductance groups, wherein the first group of inductance groups includes (n/2) coupled inductors L _ca , the total number of inductances in the (n/2) coupled inductance L _ca is n (the total number of inductances in the first group of inductance groups is the same as the total number of groups of light-emitting diodes), and the second group of inductance groups The number of inductances in is less than the number of inductances in the first group of inductance groups (the number of inductances in the second group of inductance groups=the number of inductances in the first group of inductance groups-2), and can be obtained by [(n-2)/2 ] A coupled inductor L _cb composition. In this embodiment, the total number of coupled inductors is (n/2)+[(n−2)/2]=n−1, in other words, the current sharing circuit 22 can use n−1 coupled inductors. Similarly, each inductor in the first group of inductance groups will form a current loop with each corresponding group of light-emitting diodes, and the number of current loops is n which is the same as the total number of groups of light-emitting diodes, and each current loop Each corresponding group of light emitting diodes and each rectifier are respectively connected in series. Each inductor of the second group of inductors is respectively connected in series with a part of the corresponding inductors of the first group of inductors. The series connection method is similar to the embodiment shown in FIG. 5 , which will not be repeated here.

Please refer to FIG. 9 , which is a schematic circuit diagram of another variation of the embodiment shown in FIG. 8 . As shown in FIG. 9 , the current equalizing circuit 22 is respectively connected to n groups of light-emitting diodes G _1a -G _nb , and the current equalizing circuit 22 is composed of three groups of inductance groups, wherein the first group of inductance groups includes (n/2) coupled inductors L _ca , the total number of inductors in the (n/2) coupled inductor L _ca is n (the total number of inductors in the first group of inductors is the same as the total number of groups of light-emitting diodes), and the second group of inductors The number of inductances in the group is less than the number of inductances in the first group of inductance groups (the number of inductances in the second group of inductance groups=the number of inductances in the first group of inductance groups-2), and can be obtained by [(n-2)/ 2] Composed of a coupled inductor L _cb . The number of inductors in the third group of inductors is less than the number of inductors in the second group of inductors, and can be composed of a single coupled inductor L _cc . In this embodiment, the total number of coupled inductors is (n/2)+[(n−2)/2]+1=n, in other words, the current sharing circuit 22 can use n coupled inductors. Similarly, each inductor in the first group of inductance groups will form a current loop with each corresponding group of light-emitting diodes, and the number of current loops is n which is the same as the total number of groups of light-emitting diodes, and each current loop Each corresponding group of light emitting diodes and each rectifier are respectively connected in series. Each inductor in the second group of inductors is connected in series with the corresponding part of the inductors in the first group of inductors. The series connection method is similar to the embodiment shown in FIG. 8 , and will not be repeated here. The third group of inductors has two inductors, which are respectively connected in series with the first inductor and the last inductor in the first group of inductors. Utilizing the current equalizing circuit 22 can not only make the currents flowing through the n groups of LEDs G _1a -G _nb substantially the same, but also avoid safety problems caused by short circuit and increase the protection function.

To sum up, the current balanced power supply circuit of multiple groups of light-emitting diodes in the present invention is different from the traditional power supply circuit of multiple groups of light-emitting diodes, so that the current of each group of light-emitting diodes is balanced and the luminous brightness is the same, and the power loss of the circuit is small and the circuit The operating efficiency is high, relatively few components are used and the circuit complexity is low, and the cost can be greatly reduced.

The present invention is susceptible to various modifications by those skilled in the art, all without departing from the scope of protection of the appended claims.

Claims (22)

1. A current balanced power supply circuit for multiple groups of light-emitting diodes, used to drive multiple groups of light-emitting diodes, the current balanced power supply circuit for multiple groups of light-emitting diodes at least includes: The current supply circuit is used to receive power and convert it into a current with a specific current magnitude, so as to provide the plurality of groups of light-emitting diodes; A current equalizing circuit is connected in series with the output end of the current supply circuit and the plurality of sets of light emitting diodes, and the current equalizing circuit includes at least one coupled inductor to balance the current of the plurality of sets of light emitting diodes; and The current control unit is connected to the current supply circuit and at least one set of LEDs among the plurality of groups of LEDs, and is used for detecting the magnitude of the current of the plurality of groups of LEDs and controlling the output current of the current supply circuit. 2. The current balanced power supply circuit for multiple groups of LEDs as claimed in claim 1, further comprising: a plurality of rectifiers connected in series with the output end of the current power supply circuit, the current equalizing circuit and the multiple groups of LEDs respectively. 3. The current balanced power supply circuit for multiple groups of light-emitting diodes as claimed in claim 2, wherein the plurality of rectifiers are respectively connected in series between the output end of the current power supply circuit and the current equalizing circuit, or respectively connected in series with the current equalizing circuit and between the groups of light-emitting diodes. 4. The current balanced power supply circuit of multiple groups of light-emitting diodes as claimed in claim 1, further comprising: a power rectification circuit, connected to the input end of the current power supply circuit, for receiving AC power and converting the power to the current power supply circuit. 5. The current balanced power supply circuit for multiple groups of LEDs according to claim 1, further comprising: a filter circuit connected to the input end of the current power supply circuit. 6. The current balanced power supply circuit for multiple groups of light emitting diodes according to claim 1, further comprising: a plurality of capacitors connected to the multiple groups of light emitting diodes respectively. 7. The current balance power supply circuit of multiple groups of light-emitting diodes as claimed in claim 1, wherein the current power supply circuit at least comprises: a switch circuit, including at least one switch element, connected to the current control unit and the input end of the current supply circuit; and The transformer includes a primary winding and multiple sets of secondary windings, the primary winding is connected to the switch circuit and the input end of the current supply circuit. 8. The current balanced power supply circuit of multiple groups of light-emitting diodes as claimed in claim 7, wherein the switch circuit is composed of a first switch element, and the current control unit controls the first switch element to be turned on or off, so as to transmit the power to the plurality of sets of secondary windings of the transformer, and wherein each set of secondary windings of the plurality of sets of secondary windings of the transformer has the same turns ratio as the primary winding. 9. The current balanced power supply circuit for multiple groups of LEDs as claimed in claim 7, wherein the switch circuit comprises a second switch element, a third switch element, a resonant inductor and a resonant capacitor, wherein the second switch element and the third The switching elements are respectively connected to the current control unit and the input end of the current supply circuit and connected in series at a series point, and the resonant inductance and the resonant capacitor are connected in series between the series point and the primary winding of the transformer. 10. The current balanced power supply circuit for multiple sets of LEDs as claimed in claim 9, wherein the current control unit controls the second switch element and the third switch element to be turned on or off alternately, so as to transmit the power to the The multiple sets of secondary windings of the transformer, and each of the multiple sets of secondary windings of the transformer respectively has a center tap and is connected to a common node. 11. The current balance power supply circuit of multiple groups of light-emitting diodes as claimed in claim 1, wherein the current sharing circuit has a coupled inductor, and the coupled inductor has multiple inductors, and the multiple inductors in the coupled inductor are respectively connected to the multiple groups The light emitting diodes are correspondingly connected in series. 12. The current balanced power supply circuit for multiple sets of LEDs as claimed in claim 1, wherein the current sharing circuit comprises multiple sets of inductors, and each set of inductors includes a plurality of inductors. 13. The current balance power supply circuit of multiple groups of light-emitting diodes as claimed in claim 12, wherein the multiple groups of inductance groups at least include a first group of inductance groups and a second group of inductance groups, wherein a plurality of inductance groups in the first group The number of inductors is the same as that of the multiple groups of light emitting diodes, and the multiple inductors in the first group of inductors are respectively connected in series with the multiple groups of light emitting diodes. 14. The current balanced power supply circuit for multiple sets of LEDs as claimed in claim 13, wherein the first set of inductors comprises one or more coupled inductors. 15. The current balanced power supply circuit for multiple sets of LEDs as claimed in claim 14, wherein the number of inductors in the second set of inductors is smaller than the number of inductors in the first set of inductors. 16. The current balanced power supply circuit for multiple sets of LEDs as claimed in claim 15, wherein the second set of inductors comprises one or more coupled inductors. 17. The current balanced power supply circuit for multiple sets of light emitting diodes as claimed in claim 16, wherein each of the multiple inductors of the first set of inductance groups corresponds to each set of light emitting diodes in the multiple sets of light emitting diodes respectively ground forms a current loop. 18. The current balanced power supply circuit for multiple sets of LEDs as claimed in claim 16, wherein each inductor in the second set of inductors is connected in series with some inductors in the first set of inductors. 19. The current balance power supply circuit of multiple groups of light-emitting diodes as claimed in claim 18, wherein the multiple groups of inductance groups further comprise a third group of inductance groups, the third group of inductance groups includes a coupled inductor, and the coupled inductor has two an inductor. 20. The current balanced power supply circuit for multiple groups of LEDs as claimed in claim 19, wherein two inductors in the third group of inductors are respectively connected in series with the first inductor and the last inductor in the first group of inductors. 21. The current balance power supply circuit for multiple groups of LEDs as claimed in claim 1, wherein each group of LEDs in the multiple groups of LEDs has a plurality of LEDs respectively. 22. The current balance power supply circuit for multiple groups of LEDs as claimed in claim 1, wherein the output current of the current power supply circuit is a pulsed current.

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