CN114679808A - Wide-input-voltage soft-switching n-way current-sharing LED output circuit - Google Patents

Abstract

The invention discloses a soft-switching n-path current-sharing LED output circuit with wide input voltage, which comprises a direct-current input power supply and an input inductor L_BBAn output inductor L, a power supply capacitor C_BBFour power switches, energy storage capacitor C_iFreewheel diode D_jOutput load LED_jFilter capacitor C_oj. The soft-switching n-path current-sharing LED output circuit with wide input voltage has a current-sharing effect, the circuit has the capacity of adjusting the wide input voltage by changing the working state of the power switch tube, and meanwhile, the power switch tube can realize zero-voltage switching-on and has higher efficiency. The LED current sharing circuit is suitable for occasions with large input voltage variation range and multi-path LED current sharing output.

Description

Wide-input-voltage soft-switching n-way current-sharing LED output circuit

Technical Field

The invention belongs to the technical field of power electronics, and particularly relates to a soft-switching n-way current-sharing LED output circuit with wide input voltage, which is suitable for the fields of power electronics and the like.

Background

With the development of semiconductor technology, LEDs have become more and more prominent in lighting systems due to their advantages of high light emitting efficiency, environmental protection, long life, various colors, easy dimming, and the like. Because of these advantages, LEDs have penetrated into lighting applications, such as home, traffic lights, street, automotive lighting, and the like.

The current through the LED is exponential to the voltage across it, so a slight voltage change results in a large change in the current through the LED, and consequently in a large change in the light output. To meet the requirements of a wide range of input voltage applications, such as commercial, battery, or solar power, an LED driver should have the capability of boosting or stepping down. However, the conventional dc LED driving circuit basically has only a step-up capability or a step-down capability, and cannot adjust a wide range of input voltages.

The LLC resonant converter is widely used in LED driving due to its advantages of soft switching and high power density, but it is difficult to achieve multiple LED outputs due to the secondary side rectification structure of the LLC resonant converter. Meanwhile, the dimming mode of the LLC resonator when the LLC resonator is used as an LED drive circuit is mostly PFM control, and when the LLC resonant converter works in an over-resonant mode, the power switch tube loses the zero-voltage switching-on capacity, so that high switching-on loss is caused.

Disclosure of Invention

The invention aims to solve the problems in the prior art and provide a soft-switching n-way current-sharing LED output circuit with wide input voltage.

The above object of the present invention is achieved by the following technical means:

a soft-switching n-way current-sharing LED output circuit with wide input voltage comprises an integrated Buck-Boost full-bridge switch network, wherein the output of the integrated Buck-Boost full-bridge switch network comprises a first power interface, a second power interface and n-way LED output loads, wherein n is more than or equal to 2,

when n is an even number, defining p =1, 3, 5, ·, n-1, p being an odd number; q =2, 4, 6,.. and n-2, q is an even number, the first power interface is connected with one end of an output inductor L, and the other end of the output inductor L is respectively connected with an energy storage capacitor C_pIs connected with the positive electrode of the energy storage capacitor C_pNegative pole of (D) is connected with a freewheeling diode (D)_pAnode and freewheeling diode D_p+1Cathode of (D), freewheeling diode D_pCathode and output load LED_pIs connected to the anode of a freewheeling diode D_qAnode and output load LED_qIs connected to the cathode of the energy storage capacitor C_qAnode of the LED is connected with an output load LED_qAnd output load LED_q+1Cathode of (2), energy storage capacitor C_qThe negative electrode of the LED is connected with a second power interface to output a load LED_nAnode and output load LED₁The cathodes of the LED are connected with a second power interface, and each output load LED_jAre all connected in parallel with a filter capacitor C_oj，

When n is odd, p1=1, 3, 5, ·, n-2 is defined, p1 is odd; q1=2, 4, 6,. and n-1, q1 is an even number, the first power interface is connected with one end of an output inductor L, and the other end of the output inductor L is respectively connected with an energy storage capacitor C_p1Anode and freewheel diode D_nIs connected with the anode of the energy storage capacitor C_p1Negative pole of (D) is connected with a freewheeling diode (D)_p1Anode and freewheeling diode D_p1+1Cathode of (D), freewheeling diode D_p1Cathode and output load LED_p1Is connected to the anode of a freewheeling diode D_q1Anode and output load LED_q1Is connected to the cathode of the energy storage capacitor C_q1Anode of the LED is connected with an output load LED_q1Anode and output load LED_q1+1Cathode of (2), energy storage capacitor C_q1Negative electrode, output load LED₁And output load LED_nIs connected with the second power interface, a freewheeling diode D_nCathode and output load LED_nAnode connection of, each output load LED_jAre all connected in parallel with a filter capacitor C_oj。

The integrated Buck-Boost full-bridge switch network comprises a direct-current input power supply V_inInput inductance L_BBPower supply capacitor C_BBPower switch tube S₁Power switch tube S₂Power switch tube S₃And power switch tube S₄，

DC input power supply V_inThe positive electrode is connected with an input inductor L simultaneously_BBOne terminal and a power supply capacitor C_BBOne terminal of (1), input inductance L_BBAnother end of (S), a power switch tube (S)₁Source electrode of (1), power switch tube S₂Is connected with the second power interface, and a power switch tube S₁Drain electrode of (1) and power switch tube S₃Drain electrode of the capacitor is connected with a power supply capacitor C_BBAnother terminal of (1), a power switch tube S₂Source electrode of (2) and power switch tube S₄Source electrode of the transistor is connected with a direct current input power supply V_inNegative pole, power switch tube S₃Source electrode of (1), power switch tube S₄Is connected to the first power interface.

The operation modes of the integrated Buck-Boost full-bridge switch network comprise: an integrated Buck-Boost full-bridge mode, an integrated Buck-Boost half-bridge mode, and a half-bridge mode,

in an integrated Buck-Boost full-bridge mode, a power switch tube S₁And a power switch tube S₂Complementary conducting power switch tube S₃And a power switch tube S₄Complementary conducting power switch tube S₂And a power switch tube S₃Conducting synchronously;

in an integrated Buck-Boost half-bridge mode, a power switch tube S₁And a power switch tube S₂Complementary conducting power switch tube S₃Keep off, power switch tube S₄Keeping conduction;

in half-bridge mode, the power switch tube S₃And a power switch tube S₄Complementary conducting power switch tube S₁Keep on, the power switch tube S₂Remain off.

Compared with the prior art, the invention has the following beneficial effects:

the invention realizes multi-path LED current-sharing output on the occasion of wider input voltage by controlling the power switch tube, and the power switch tube has the capability of zero-voltage switching on.

Drawings

FIG. 1(a) is a schematic diagram of an integrated Buck-Boost full-bridge mode even-numbered LED output circuit structure,

FIG. 1(b) is a schematic diagram of an integrated Buck-Boost full-bridge mode odd-numbered LED output circuit structure;

FIG. 2 is a schematic diagram of a structure of an integrated Buck-Boost full-bridge mode four-way LED output circuit;

fig. 3(a) is a schematic diagram of an integrated Buck-Boost full-bridge mode four-way LED outputting a main working mode 1, fig. 3(b) is a schematic diagram of an integrated Buck-Boost full-bridge mode four-way LED outputting a main working mode 2, fig. 3(c) is a schematic diagram of an integrated Buck-Boost full-bridge mode four-way LED outputting a main working mode 3, fig. 3(d) is a schematic diagram of an integrated Buck-Boost full-bridge mode four-way LED outputting a main working mode 4, fig. 3(e) is a schematic diagram of an integrated Buck-Boost full-bridge mode four-way LED outputting a main working mode 5, and fig. 3(f) is a schematic diagram of an integrated Buck-Boost full-bridge mode four-way LED outputting a main working mode 6;

FIG. 4 is a schematic diagram of a structure of an integrated Buck-Boost half-bridge mode four-way LED output circuit;

FIG. 5 is a schematic diagram of a half-bridge four-way LED output circuit;

FIG. 6(a) is a waveform diagram of 20 times of amplification of the voltage and the amplitude of the driving signal of the power switch tube of the integrated Buck-Boost full-bridge mode four-way LED output circuit under the rated load,

FIG. 6(b) is a waveform diagram of the power switch tube voltage and the amplitude of the driving signal of the integrated Buck-Boost half-bridge mode four-way LED output circuit under the rated load amplified by 20 times,

FIG. 6(c) is a waveform diagram of the power switch tube voltage and the amplitude of the driving signal of the half-bridge mode four-way LED output circuit under the rated load amplified by 20 times,

fig. 6(d) is an output current waveform diagram of the integrated Buck-Boost full-bridge mode four-way LED output circuit under unbalanced load.

Detailed Description

The present invention will be described in further detail with reference to examples for the purpose of facilitating understanding and practice of the invention by those of ordinary skill in the art, and it is to be understood that the present invention has been described in the illustrative embodiments and is not to be construed as limited thereto.

For convenience of description and analysis, the parameters of voltage, current, etc. representing the circuit elements are defined as follows:

soft-switched n-way current sharing L for wide input voltageED output circuit, n is greater than or equal to 2, and D is defined as a power switch tube S₂Power switch tube S₃Duty cycle of the on-time; t is defined as the time of one switching cycle; DT is defined as power switch tube S₂Power switch tube S₃The product of the duty cycle D of the on-time and the time of one switching cycle time T; f. of_SDefined as the switching frequency; v_S1、V_S2、V_S3、V_S4Are respectively defined as a power switch tube S₁Power switch tube S₂Power switch tube S₃Power switch tube S₄The voltage at the two ends is from the drain electrode to the source electrode of the power switch tube; i.e. i_S1、i_S2、i_S3、i_S4Are respectively defined as flowing through the power switch tube S₁Power switch tube S₂Power switch tube S₃Power switch tube S₄The current of (2) is from the drain electrode to the source electrode of the power switch tube in the direction; q_S1、Q_S2、Q_S3、Q_S4Are respectively a power switch tube S₁Power switch tube S₂Power switch tube S₃Power switch tube S₄The amplitude of the driving signal of (1); v_LBBIs defined as the input inductance L_BBVoltage across, V_CBBDefined as the power supply capacitance C_BBVoltage across, V_LDefined as the voltage across the output inductor L, in the direction shown in fig. 1(a) and 1 (b); v_HDefined as the average value of the input voltage of the n-way output load in one switching period, the direction is shown in figure 1(a) and figure 1(b), V_H1Defined as the maximum value of the input voltage, V, of the n-way output load in one switching cycle_H2Defining the minimum value of input voltage of n output loads in a switching period; v_Ci(i =1, 2, · n-1) is defined as the energy storage capacitance C_i(i =1, 2,. 1, n-1), the direction being as in fig. 1(a) and fig. 1(b), i =1, 2_Ci(i =1, 2,. n-1) is defined as flowing through the storage capacitor C_i(i =1, 2,. n-1) current, direction and V_CiIn the same direction; v_Dj(j =1, 2,. and n) is defined as a freewheeling diode D_j（j=1、2、...、n）Voltage across, direction from freewheeling diode D_j(j =1, 2,. n-1) from positive to negative; v_LEDj(j =1, 2, · n) is defined as the output load LED_j(j =1, 2,. logarithms, n), the direction being as analogized in fig. 1(a) and 1 (b); I.C. A_LEDj(j =1, 2, · n) is defined as the output load LED_jAverage output current over (j =1, 2, · n), i_LEDj(j =1, 2, · n) is defined as the output load LED_j(j =1, 2,. n) instantaneous output current, direction and V_LEDj(j =1, 2, · n) in the same direction; delta Q_ich(i =1, 2,. and n-1) is defined as the energy storage capacitor C in one switching cycle_i(i =1, 2, …, n-1) the amount of charge charged; delta Q_idis(i =1, 2,. and n-1) is defined as the energy storage capacitor C in one switching cycle_i(i =1, 2,. n-1) an amount of charge discharged; the input voltage is defined as V_inThe direction is shown in fig. 1(a) and 1 (b); i all right angle_LBBIs defined as flowing through the input inductor L_BBThe direction of the current is shown in FIG. 1(a) and FIG. 1 (b); i.e. i_LDefined as the current flowing through the output inductor L, in the direction shown in fig. 1(a) and 1 (b).

The structural schematic diagrams of the integrated Buck-Boost full-bridge mode multi-path LED output circuit are shown in fig. 1(a) and fig. 1(b), and the integrated Buck-Boost full-bridge mode multi-path LED output circuit comprises an integrated Buck-Boost full-bridge switch network and n paths of LED output loads, wherein n is greater than or equal to 2.

The integrated Buck-Boost full-bridge switch network comprises a direct-current input power supply V_inInput inductance L_BBPower supply capacitor C_BBPower switch tube S₁Power switch tube S₂Power switch tube S₃And power switch tube S₄. The output of the integrated Buck-Boost full-bridge switch network comprises a first power interface, a second power interface and a direct-current input power supply V_inThe positive electrode is connected with an input inductor L simultaneously_BBOne terminal, and a power supply capacitor C_BBOne terminal of (1), input inductance L_BBAnother end of (S), a power switch tube (S)₁Source electrode of (1), power switch tube S₂Is connected with the second power interface, and a power switch tube S₁Drain electrode of (1) and power switch tube S₃Drain electrode of the capacitor is connected with a power supply capacitor C_BBAnother terminal of (1), a power switch tube S₂Source electrode of and power switch tube S₄Source electrode of the transistor is connected with a direct current input power supply V_inNegative pole, power switch tube S₃Source electrode of (1), power switch tube S₄Is connected to the first power interface.

According to the working state of the power switch tube, the following three modes can be divided: power switch tube S₁And a power switch tube S₂Complementary conducting power switch tube S₃And a power switch tube S₄Complementary conducting power switch tube S₂And a power switch tube S₃When synchronous conduction is carried out, the integrated Buck-Boost full-bridge switch network works in an integrated Buck-Boost full-bridge mode; power switch tube S₁And a power switch tube S₂Complementary conducting power switch tube S₃Keep off, power switch tube S₄When the integrated Buck-Boost full-bridge switch network is kept on, the integrated Buck-Boost full-bridge switch network works in an integrated Buck-Boost half-bridge mode; power switch tube S₃And a power switch tube S₄Complementary conducting power switch tube S₁Keep on, the power switch tube S₂And when the integrated Buck-Boost full-bridge switch network is kept to be switched off, the integrated Buck-Boost full-bridge switch network works in a half-bridge mode.

When n is an even number, defining p =1, 3, 5, ·, n-1, p being an odd number; q =2, 4, 6,. and n-2, q is even number, and the even number LED load circuit is shown in figure 1 (a). The first power interface is connected with one end of an output inductor L, and the other end of the output inductor L is respectively connected with an energy storage capacitor C_pIs connected with the positive electrode of the energy storage capacitor C_pNegative pole of (D) is connected with a freewheeling diode (D)_pAnode (positive electrode) of (2) and a free-wheeling diode D_p+1Cathode (negative electrode) of (2), flywheel diode D_pCathode (cathode) of (2) and output load LED_pIs connected to the anode (positive electrode) of a freewheeling diode D_qAnode (anode) of and output load LED_qIs connected with the cathode (negative electrode), and an energy storage capacitor C_qAnode of the LED is connected with an output load LED_qAnode (anode) of and output load LED_q+1Cathode (negative electrode) of (2), energy storage capacitor C_qOf the negative electrodeConnected with the second power interface and outputting a load LED_nAnode (anode) of and output load LED₁The cathodes (negative poles) of the LED are connected with a second power interface, and each output load LED_jAre all connected in parallel with a filter capacitor C_oj。

When n is odd, p1=1, 3, 5, ·, n-2 is defined, p1 is odd; q1=2, 4, 6,. and n-1, q1 is even, and the odd-numbered LED load circuit is shown in fig. 1 (b). The first power interface is connected with one end of an output inductor L, and the other end of the output inductor L is respectively connected with an energy storage capacitor C_p1Anode and freewheel diode D_nIs connected with the anode (anode), and an energy storage capacitor C_p1Negative pole of (D) is connected with a freewheeling diode (D)_p1Anode (positive electrode) of (D) and a freewheeling diode (D)_p1+1Cathode (negative electrode) of (1), freewheel diode D_p1Cathode (cathode) and output load LED_p1Is connected to the anode (positive electrode) of a freewheeling diode D_q1Anode (anode) of and output load LED_q1Is connected with the cathode (negative electrode), and an energy storage capacitor C_q1Anode of the LED is connected with an output load LED_q1Anode (anode) of and output load LED_q1+1Cathode (negative electrode) of (2), energy storage capacitor C_q1Negative electrode, output load LED₁And output load LED_nIs connected with the second power interface, and a freewheeling diode D_nCathode (cathode) and output load LED_nIs connected to the anode (anode), each output load is LED_jAre all connected in parallel with a filter capacitor C_oj. In order to explain the working principle of the circuit provided by the invention, the integrated Buck-Boost full-bridge mode multi-path LED output circuit is similar to the integrated Buck-Boost half-bridge mode multi-path LED output circuit and the half-bridge mode multi-path LED output circuit in operation. Therefore, only the working principle and mode of the integrated Buck-Boost full-bridge mode multi-path LED output circuit are discussed below. For example, an integrated Buck-Boost full-bridge mode four-way LED output circuit is shown in fig. 2. Power switch tube S₂Power switch tube S₃Is conducted with a duty ratio D and a power switch tube S₁Power switch tube S₄And a power switch tube S₂Power switchPipe S₃And conducting complementarily. As shown in fig. 2, n is an even number 4.

To simplify the analysis, assume

(1) All the switch tubes, diodes, capacitors and inductors are ideal devices.

(2) Energy storage capacitor C₁、C₂、C₃Are equal.

(3) Filter capacitance value C_o1、C_o2、C_o3、C_o4Much larger than the energy storage capacitance C₁、C₂、C₃Therefore, the voltage across the filter capacitor can be considered as a constant value in the switching period, and the output load LED is connected in parallel with the constant value₁、LED₂、LED₃、LED₄The voltage across the terminals being constant, i.e. V_LED1、V_LED2、V_LED3、V_LED4Is a constant value.

The circuit has 6 modes in one switching period, as shown in fig. 3(a) to 3 (f):

mode 1[ t ]₀~t₁]: as shown in FIG. 3(a), in the power switch tube S₂Power switch tube S₃Before the power is switched on, the power switch tubes are all switched off to output L current i of the inductor_LThrough a power switch tube S₃The parasitic diode of (1) freewheeling, the input current flowing through the power switch tube S₂So that the power switch tube S₂Power switch tube S₃The drain-source voltage of the power switch tube S is zero₂Power switch tube S₃ZVS turn-on conditions are provided. Input inductance L_BBVoltage V across_LBBEqual to the power supply input voltage V_inThus the input inductance L_BBCurrent of (i)_LBBAnd (4) increasing linearly. Power switch tube S₂Power switch tube S₃When conducting, the inductor L current i is output_LRising linearly as a result of being subjected to a forward voltage. Freewheeling diode D₂、D₄Conducting, freewheeling diode D₁、D₃Turn-off, filter capacitor C_o1LED for output load₁Discharge, filter capacitance C_o3LED for output load₃And (4) discharging. Current i due to output inductance L_LThrough a freewheeling diode D₂Energy supply and storage capacitor C₁、C₂Discharge through a freewheeling diode D₄Energy supply and storage capacitor C₃Discharging, thereby the voltage V across the energy storage capacitor_C1、V_C2、V_C3Both decrease. When the L current i of the output inductor is_LWhen rising to 0, this mode ends.

Mode 2[ t ]₁~t₂]: as shown in fig. 3(b), a freewheeling diode D₃Conducting, freewheeling diode D₁、D₂、D₄Turn-off, filter capacitor C_o1、C_o2、C_o4Respectively provide output load LED₁、LED₂、LED₄And (4) discharging. Energy storage capacitor C₁Is clamped. Current i due to output inductance L_LThrough a freewheeling diode D₃Energy supply and storage capacitor C₂、C₃Charging and energy-storing capacitor C₂、C₃Voltage V across_C2、V_C3And (4) rising. As energy storage capacitor C₂、C₃And output load LED₃The sum of the voltages at the two ends rises to the energy storage capacitor C₁And output load LED₁When the sum of the voltages at both ends is equal, the freewheeling diode D₁Conduction ends this mode.

Mode 3[ t ]₂~t₃]: as shown in fig. 3(c), a free-wheeling diode D₁、D₃Conducting, freewheeling diode D₂、D₄Turn-off, filter capacitor C_o2For output load LED₂Discharging, filtering capacitor C_o4LED for output load₄Discharging and outputting inductor L current i_LRising to a peak. Due to output inductor L current i_LThrough a freewheeling diode D₁Energy supply and storage capacitor C₁Charging through a freewheeling diode D₃Energy supply and storage capacitor C₂、C₃Voltage V across the charging and energy-storage capacitor_C1、V_C2、V_C3Both rise. When power switch tube S₁Power switch tube S₄When on, this mode ends.

Mode 4[ t ]₃~t₄]: as shown in fig. 3(d), the power switch tube S₁Power switch tube S₄Before conduction, the power supply capacitor C_BBPower supply switch tube S₁Discharging the parasitic capacitance of the output inductor L to output the L current i_LThrough a power switch tube S₄The parasitic diode of (1) freewheeling, thus the power switch tube S₁Power switch tube S₄ZVS turn-on conditions are provided. Input inductance L_BBThrough a power switch tube S₁Parasitic diode of to power supply capacitor C_BBAnd (6) charging. Freewheeling diode D₁、D₃Still conducting, freewheeling diode D₂、D₄Is still turned off, the filter capacitor C_o2For output load LED₂Discharging, filtering capacitor C_o4LED for output load₄Discharging and outputting inductor L current i_LAnd drops by being subjected to a reverse voltage. Due to output inductor L current i_LThrough a freewheeling diode D₁Energy supply and storage capacitor C₁Charging through a freewheeling diode D₃Energy supply and storage capacitor C₂、C₃Voltage V across charging and energy-storage capacitor_C1、V_C2、V_C3Both rise. When the L current i of the output inductor is_LWhen it falls to 0, this mode ends.

Mode 5[ t ]₄~t₅]: as shown in fig. 3(e), a free-wheeling diode D₂Conducting, freewheeling diode D₁、D₃、D₄Turn off, filter capacitor C_o1、C_o3、C_o4Respectively provide output load LED₁、LED₃、LED₄And (4) discharging. Energy storage capacitor C₃Is clamped. Current i due to output inductance L_LThrough a freewheeling diode D₂Energy supply and storage capacitor C₁、C₂Discharging, energy-storing capacitor C₁、C₂Voltage V across_C1、V_C2And (4) descending. As energy storage capacitor C₁、C₂And output load LED₄The sum of the voltages at the two ends is reduced to be equal to the energy storage capacitor C₃And output load LED₂When the sum of the voltages at both ends is equal, the freewheeling diode D₄Conduction, this mode ends.

Mode 6[ t ]₅~t₆]: as shown in fig. 3(f), a free-wheeling diode D₂、D₄Conducting, freewheeling diode D₁、D₃Turn-off, filter capacitor C_o1LED for output load₁Discharge, filter capacitance C_o3LED for output load₃And (4) discharging. Current i due to output inductance L_LThrough a freewheeling diode D₂Energy supply and storage capacitor C₁、C₂Discharge through a freewheeling diode D₄Energy supply and storage capacitor C₃Voltage V across the discharge, storage capacitor_C1、V_C2、V_C3Both decrease. This mode ends when the next switching cycle begins.

In modes 1, 5, and 6, the storage capacitor C is due to the unidirectional conductivity of the diode₁By output load LED₂And a freewheeling diode D₂Discharge, Δ Q_1disAnd the LED flows through the output load in one switching period₂Are equal in charge amount; in modes 3, 4, the storage capacitor C is due to the unidirectional conductivity of the diode₁By output load LED₁And a freewheeling diode D₁Charge, Δ Q_1chAnd the LED flows through the output load in one switching period₁The output current can be regarded as a constant value because the filter capacitance is large enough, and the following relationship exists:

（1）

in modes 1, 5, and 6, the storage capacitor C is due to the unidirectional conductivity of the diode₂By output load LED₂And a freewheeling diode D₂Discharge, Δ Q_2disAnd the LED flows through the output load in one switching period₂Are equal in charge amount; in modes 2, 3, 4, the storage capacitor C is due to the unidirectional conductivity of the diode₂By output load LED₃And a freewheeling diode D₃Charge, Δ Q_2chAnd the LED flows through the output load in one switching period₃Is equal, because the filter capacitance is large enough, the output isThe current can be regarded as a constant value, and the following relationship is given:

（2）

in modes 1 and 6, the storage capacitor C is due to the unidirectional conductivity of the diode₃By output load LED₄And a freewheeling diode D₄Discharge, Δ Q_3disAnd the LED flows through the output load in one switching period₄Are equal in charge amount; in modes 2, 3, 4, the storage capacitor C is due to the unidirectional conductivity of the diode₃By output load LED₃And a freewheeling diode D₃Charge, Δ Q_3chAnd the LED flows through the output load in one switching period₃The output current can be regarded as a constant value because the filter capacitance is large enough, and the following relationship exists:

（3）

the relationship between the charge quantity flowing through the energy storage capacitor in each mode in a switching period and the charge-discharge balance of the energy storage capacitor can be deduced:

（4）

（5）

（6）

the following equations (1) and (4) can be derived:

（7）

the following equations (2) and (5) can be derived:

（8）

the following equations (3) and (6) can be derived:

（9）

the following can be derived from equations (7), (8), (9):

（10）

therefore, the circuit realizes the current balance on the four output branches by using the charge balance principle of the three energy storage capacitors.

The integrated Buck-Boost full-bridge mode four-way LED output circuit is in modes 1, 2 and 3, namely a power switch tube S₂When conducting, the input inductance L_BBVoltage V across_LBBEqual to the power supply input voltage V_inThus the input inductance L_BBCurrent i of_LBBAnd is increasing. In modes 4, 5, 6, i.e. power switch S₁When conducting, the input inductance L_BBThrough a power switch tube S₁Parasitic diode of to power supply capacitor C_BBCharging, derivable:

（11）

（12）

by switching the power transistor S₄Keep on, the power switch tube S₃Keeping off to obtain an integrated Buck-Boost half-bridge mode four-way LED output circuit, a power switch tube S₁And a power switch tube S₃Complementary conduction, as shown in fig. 4. The following can be derived from the working principle:

（13）

by switching the power transistor S₁Keep on, the power switch tube S₂Keeping off to obtain a half-bridge mode four-way LED output circuit, a power switch tube S₃And power switch tube S₄Complementary conduction, as shown in fig. 5. The working principle can be deduced:

（14）

under the integrated Buck-Boost full-bridge mode, the method can be obtained by the working modes:

（15）

due to the current i in the output inductor L_LIn the power switch tube S₂Power switch tube S₃Before conducting, it is negative and is at power switch tube S₁Power switch tube S₄Before conduction, all are positive values, input inductance L_BBCurrent i of_LBBAre all positive values, and in the power switch tube S₂Before conducting, the power switch tube S₂The parasitic diode is conducted, and the power switch tube in the mode can realize zero voltage switching-on.

In the integrated Buck-Boost half-bridge mode, the working mode can obtain:

（16）

due to the current i in the output inductor L_LIn the power switch tube S₂Power switch tube S₃Before conducting, it is negative and is at power switch tube S₁Power switch tube S₄Before conduction, all are positive values, input inductance L_BBCurrent i of_LBBAre all positive values, and in the power switch tube S₂Before conducting, the power switch tube S₂The parasitic diode is conducted, and the power switch tube in the mode can realize zero voltage switching-on.

In half-bridge mode, it is possible to obtain from the operating mode:

（17）

due to the current i in the output inductor L_LIn the power switch tube S₃Before conducting, it is negative and is at power switch tube S₄Before the switch-on, the power switch tube is positive, and the power switch tube in the mode can realize zero voltage switch-on.

Simulations are built according to the integrated Buck-Boost full-bridge mode four-way LED output circuits shown in FIGS. 3(a) to 3(f), and main waveforms are simulated for the integrated Buck-Boost full-bridge mode four-way LED output circuits shown in FIGS. 6(a) to 6 (d). The main simulation parameters are set as follows_BB=15uF, input inductance L_BB=260uH, output inductance L =30uH, switching frequency f_S=100kHz, rated output load equivalent impedance R₁、R₂、R₃、R₄Rated output current i of 40 Ω_LED1、i_LED2、i_LED3、i_LED4500mA, and 80V rated output voltage. Energy storage capacitor C₁、C₂、C₃、C₄Is 1uF, a filter capacitor C_o1、C_o2、C_o3、C_o4Was 10 uF.

TABLE 1 shows the input voltage V at rated output for three modes_inAnd a power switch tube S₂、S₃Relation of on duty ratio. Table 1 shows that under rated output, Buck-Boost is integrated at a certain duty ratioFull bridge mode input voltage V_inFor integrating Buck-Boost half-bridge mode input voltage V_inDouble of that of the integrated Buck-Boost half-bridge mode input voltage V_inFor a half-bridge mode input voltage V_inMultiple of (1-D), input voltage V_inThe variation range of (2) is 14.4-288V.

TABLE 1 input voltage V in three modes_inAnd a power switch tube S₂Power switch tube S₃Relationship of on duty ratio

When the load of the four-way LED output load is unbalanced, namely the equivalent impedance R of the output load₁=30Ω、R₂=40Ω、R₃=60Ω、R₄=80 Ω, the current sharing effect of the four LED output loads can still be achieved, and the output current waveform is shown in fig. 6 (d).

According to the analysis, the soft-switching n-way current-sharing LED output circuit with wide input voltage has a current-sharing effect, and zero-voltage switching-on of the power switching tube can be realized within a wide range of input voltage by changing three working modes of the circuit.

The above disclosure is only for the preferred embodiments of the present invention, but the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are intended to be covered by the protection scope of the present invention. Therefore, the scope of the invention should be determined by the appended claims and all changes that can be made without departing from the principles of the invention.

Claims (3)

1. A soft-switching n-way current-sharing LED output circuit with wide input voltage comprises an integrated Buck-Boost full-bridge switch network, the output of the integrated Buck-Boost full-bridge switch network comprises a first power interface and a second power interface, and is characterized by further comprising n-way LED output loads, wherein n is more than or equal to 2,

when n is an even number, p =1, 3, 5,. eta., n-1 is defined, p being an odd number; q =2, 4, 6,.. and n-2, q is an even number, the first power interface is connected with one end of an output inductor L, and the other end of the output inductor L is respectively connected with an energy storage capacitor C_pIs connected with the positive electrode of the energy storage capacitor C_pNegative pole of (D) is connected with a freewheeling diode (D)_pAnode and freewheeling diode D_p+1Cathode of (D), freewheeling diode D_pCathode and output load LED_pIs connected to the anode of a freewheeling diode D_qAnode and output load LED_qIs connected to the cathode of the energy storage capacitor C_qAnode of the LED is connected with an output load LED_qAnode and output load LED_q+1Cathode of (2), energy storage capacitor C_qThe negative electrode of the LED is connected with a second power interface to output a load LED_nAnd output load LED₁The cathodes of the LED are connected with a second power interface, and each output load LED_jAre all connected in parallel with a filter capacitor C_oj，

When n is odd, p1=1, 3, 5, ·, n-2 is defined, p1 is odd; q1=2, 4, 6, n., n-1, q1 is an even number, the first power source interface is connected with one end of an output inductor L, and the other end of the output inductor L is respectively connected with an energy storage capacitor C_p1Anode and freewheel diode D_nIs connected with the anode of the energy storage capacitor C_p1Negative pole of (D) is connected with a freewheeling diode (D)_p1Anode and freewheeling diode D_p1+1Cathode of (D), freewheeling diode D_p1Cathode and output load LED_p1Is connected to the anode of a freewheeling diode D_q1Anode and output load LED_q1Is connected to the cathode of the energy storage capacitor C_q1Anode of the LED is connected with an output load LED_q1Anode and output load LED_q1+1Cathode of (2), energy storage capacitor C_q1Negative electrode, output load LED₁And output load LED_nIs connected with the second power interface, a freewheeling diode D_nCathode and output load LED_nIs connected to the anode of each output load LED_jAre all connected in parallel with a filter capacitor C_oj。

2. According to claim 1The soft-switching n-way current-sharing LED output circuit with wide input voltage is characterized in that an integrated Buck-Boost full-bridge switching network comprises a direct-current input power supply V_inInput inductance L_BBPower supply capacitor C_BBPower switch tube S₁Power switch tube S₂Power switch tube S₃And power switch tube S₄，

DC input power supply V_inThe positive electrode is connected with an input inductor L simultaneously_BBOne terminal and a power supply capacitor C_BBOne terminal of (1), input inductance L_BBAnother end of (S), a power switch tube (S)₁Source electrode of (1), power switch tube S₂Is connected with the second power interface, and a power switch tube S₁Drain electrode of (1) and power switch tube S₃Drain electrode of the capacitor is connected with a power supply capacitor C_BBAnother terminal of (1), a power switch tube S₂Source electrode of and power switch tube S₄Source electrode of the transistor is connected with a direct current input power supply V_inNegative pole, power switch tube S₃Source electrode of (1), power switch tube S₄Is connected to the first power interface.

3. The wide-input-voltage soft-switched n-way current-sharing LED output circuit as claimed in claim 1, wherein the operation mode of the integrated Buck-Boost full-bridge switching network comprises: an integrated Buck-Boost full bridge mode, an integrated Buck-Boost half bridge mode, and a half bridge mode,

in an integrated Buck-Boost full-bridge mode, a power switch tube S₁And a power switch tube S₂Complementary conducting power switch tube S₃And a power switch tube S₄Complementary conducting power switch tube S₂And a power switch tube S₃Conducting synchronously;

in an integrated Buck-Boost half-bridge mode, a power switch tube S₁And a power switch tube S₂Complementary conducting power switch tube S₃Keep off, power switch tube S₄Keeping conduction;

in half-bridge mode, the power switch tube S₃And a power switch tube S₄Complementary conducting power switch tube S₁Keep on, power switchPipe S₂Remain off.

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