I 2 Control the SIDO Buck LED driver power supply

Abstract

This invention relates to the field of LED driver power supply technology, and in particular to I 2 The SIDO Buck LED driver power supply is controlled by the main circuit SIDO Buck LED driver power supply and I... 2 The control circuit consists of two parts, I 2 The control circuit includes I 2 Control circuits I and I 2 Control circuit II. The I proposed in this invention 2 Compared to voltage-controlled SIDO Buck LED driver power supplies, controlled SIDO Buck LED driver power supplies effectively reduce crosstalk between output branches.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of LED driving power supply, and particularly relates to an I 2 Control SIDO Buck LED driving power supply. BACKGROUND

[0002] LED has the advantages of long service life, low energy consumption and green pollution-free, and has been widely used in residential lighting, traffic lighting and landscape lighting fields. According to the volt-ampere characteristic of LED, the LED can be equivalent to a series circuit of an on-voltage source v d , an ideal diode D d and an equivalent resistance R d .

[0003] The driving of multiple LEDs usually has two ways of single-channel LED driving power supply and multi-channel LED driving power supply. The single-channel LED driving power supply is usually used to drive multiple LEDs connected in series, if one of the LEDs is broken, the LEDs of the channel will not light up, and the series LED needs a higher driving voltage. The multi-channel LED driving power supply is usually used to drive multiple series LEDs, and the multi-channel LED driving power supply has problems of high cost and large size.

[0004] The single-inductor multiple-output (SIMO) LED driving power supply uses one inductor to provide output for multiple LED branches, reduces the number of components, thereby reducing the size of the driving power supply and reducing the cost. The current research on the SIMO LED driving power supply mainly focuses on the precise regulation of current and the improvement of the corresponding control scheme.

[0005] The prior art 1 proposes an AC / DC SIMO LED driving power supply, which realizes accurate independent current control of each LED.

[0006] The prior art 2 proposes a boost type and a buck type SIMO LED driving power supply, which makes the system work in a wide load range through a feedback current control method.

[0007] The prior art 3 proposes a dual-output LED driving power supply based on a quasi-lag finite state machine and a digital dimming control, which eliminates the loop compensation of the controller and reduces the complexity of the control circuit.

[0008] The current sampling resistor control strategy proposed in the prior art 4 provides an effective solution to improve the reliability of the multi-channel LED driving power supply.

[0009] The prior art 5 proposes a large range continuously adjustable light SIMO Buck LED driving power supply suitable for high-power lighting, which uses pulse width modulation technology to flexibly and accurately control the brightness of the LED, and significantly improves the light frequency.

[0010] The SIMO LED driving power supply proposed by the prior art 6 realizes soft switching, including zero-current switching and zero-voltage switching, eliminates large switching loss, and improves power supply efficiency. In fact, the output currents of the SIMO DC-DC LED driving power supply are interrelated. The current change of one output branch will affect the current of other output branches, and there is cross-influence between the output currents. However, there are few reports on the cross-influence problem of the SIMO DC-DC LED driving power supply.

[0011] The prior art 7 uses a time-multiplexing control scheme to manage the switching period, which can generate system differences between LED currents, so that only one switch is in the on state in each period, thereby solving the cross-influence problem.

[0012] The prior art 8 introduces a continuous conduction mode (CCM) SIMO Boost driving power supply based on time-multiplexing control and replacement conduction sequence, which can drive multiple channels of LEDs at the same time, so that each channel of LED has the same current and brightness, not only reducing circuit loss, but also reducing cross-influence between output branches. At present, there is still a lack of in-depth theoretical analysis and better solutions for the cross-influence of the SIMO DC-DC LED driving power supply.

[0013] In order to reduce the cross-influence between the output branches of the single-inductor dual-output (SIDO) CCM Buck LED driving power supply, the present application proposes an I 2 The working principle of the SIDO Buck LED driving power supply is analyzed in detail, and based on the state space averaging method and the current ripple waveform, an I 2 The small signal model of the SIDO Buck LED driving power supply is established, and the cross-influence transfer functions of the voltage-controlled and current-controlled SIDO Buck LED driving power supplies are obtained. 2 The cross-influence between the output branches is compared and analyzed by comparing the cross-influence transfer functions of the voltage-controlled and current-controlled SIDO Buck LED driving power supplies. Finally, the correctness of the theoretical analysis is verified by experimental results. SUMMARY

[0014] In view of the deficiencies in the above prior art, the purpose of the present application is to provide an I 2To control the SIDO BuckLED driver power supply and reduce the crosstalk between the output branches of the SIDO CCM BuckLED driver power supply.

[0015] To address the above problems, this invention discloses I 2 The SIDO Buck LED driver power supply is controlled by the main circuit SIDO Buck LED driver power supply and I 2 The control circuit consists of two parts, I 2 The control circuit includes I 2 Control circuits I and I 2 Control circuit II; in I 2 In control circuit I, the sampling resistor R s1 The sampled output current i1 is then passed through error amplifier AM1 and compared with the reference signal i. ref1 The signal v is obtained after subtraction. o1 ;v o1 The amplified error signal v is obtained through compensator PI1. c1 v c1 Then, with the ramp signal v ramp1 The sum is the signal v e1 Sampling output current R s1 i1 and v e1 The comparison is performed by comparator CM1, and the comparison result and clock signal clk are input to the S and R terminals of flip-flop RS1, respectively; the Q terminal of flip-flop RS1 outputs the control signal V. g1 To control the on and off of the switching transistor S1;

[0016] Similarly, in I 2 In control circuit II, the sampling resistor R s2 The sampled output current i2 is then passed through error amplifier AM2 and compared with the reference signal i. ref2 The signal v is obtained after subtraction. o2 ;v o2 The amplified error signal v is obtained through compensator PI2. c2 v c2 Then, with the ramp signal v ramp2 The sum is the signal v e2 Sampling output current R s2 i2 and v e2 The comparison is performed by comparator CM2, and the comparison result and clock signal clk are input to the S and R terminals of flip-flop RS2, respectively; the Q terminal of flip-flop RS2 outputs the control signal V. g2 This is to control the switching transistor S2 to turn on and off.

[0017] Preferably, the SIDO Buck LED driver power supply includes an input voltage V i, inductor L, output capacitors C1, C2, diodes D1, D2, switch tubes S1, S2, LED1 output branch and LED2 output branch;v i The energy is transferred to the LED1, LED2 output branch through the inductor L, and i1, i2 and v1, v2 are the output current and output voltage of the LED1, LED2 output branch respectively, wherein v1>v2; the control signal and on-duty of S1, S2 are V g1 , V g2 and d1, d2.

[0018] As preferred, the on-duty d1 and d2 have three size relations: d1

[0019] 1) Switching state I: switch tubes S1, S2 are on, and diodes D1, D2 are off; the input voltage v i charges the inductor L and capacitor C2, and supplies power to LED2; capacitor C1 supplies power to LED1;

[0020] 2) Switching state II: diodes D1, D2 are on, and switch tubes S1, S2 are off; the inductor L charges capacitor C1, and supplies power to LED1; capacitor C2 supplies power to LED2;

[0021] 3) Switching state III: switch tube S2 and diode D1 are on, and switch tube S1 and diode D2 are off; the inductor L charges capacitor C2, and supplies power to LED2; capacitor C1 supplies power to LED1.

[0022] As preferred, let state variable x = [i L v1 v2] T , input vector u = [v i v d1 v d2 ] T , wherein v d1 and v d2 are the turn-on voltage of LED1 and LED2 respectively, R d1 and R d2 are the equivalent resistance of LED1 and LED2 respectively; the corresponding state equations of the SIDO Buck LED driving power when working in switching state I, switching state II and switching state III are respectively:

[0023]

[0024] In the formula, matrices A1-A3 and B1-B3 are respectively:

[0025]

[0026]

[0027] The state space average model of the SIDO Buck LED driving power supply can be obtained by using the state space average method:

[0028]

[0029] wherein is the average value of the state variable, is the average value of the input vector; A = d2A1 + (1-d2)A2, B = d1B3 + (1-d1)B1, then the coefficient matrix A and B are respectively:

[0030]

[0031] The small signal perturbation of the variable in equation (2) can be obtained as

[0032] The small signal model of the SIDO Buck LED driving power supply is:

[0033]

[0034] wherein the capital letter variable is the direct current steady state quantity, and the variable with the “^” letter is the small signal perturbation quantity.

[0035] Preferably, I 2 The control timing of the SIDO Buck LED driving power supply is controlled, at the moment of nT, the sampling output current R s1 i1 is less than the signal v e1 , the comparator CM1 outputs high level, the flip-flop RS1 is set, and the switch tube S1 is turned on; at the same time, the sampling output current R s2 i2 is less than the signal v e2 , the comparator CM2 outputs high level, the flip-flop RS2 is set, and the switch tube S2 is turned on; the inductor current i L rises with the slope k L3 , R s1 i1 falls with the slope -k2, and the sampling R s2 i2 rises with the slope k4.

[0036] When the clock signal clk comes, the flip-flops RS1 and RS2 are reset, the switch tubes S1 and S2 are turned off, i L falls with the slope -k L1 , R s1 i1 rises with the slope k1, and R s2 i2 falls with the slope -k3. When R s2 i2 falls to the signal ve2 When the comparator CM2 outputs high level, the flip-flop RS2 is set, the switch S2 is turned on, and the switch S1 remains off, i L R L2 Continuing to drop, R s2 R s1 i1 drops with the slope -k2; until R s1 i1 drops to v e1 , the circuit enters the next switching cycle;

[0037] The inductance current slope k L1 , k L2 , k L3 are respectively:

[0038]

[0039] The sampling output current slope k1~k4 are respectively:

[0040]

[0041] As preferred, the amplified error signal v c1 and v c2 are respectively:

[0042]

[0043]

[0044] In the formula, k p1 , k p2 are the proportional coefficients of the compensators PI1, PI2, k i1 , k i2 are the integral coefficients of the compensators PI1, PI2;

[0045] From the ripple waveform of i L , we can get

[0046] k L1 (1-d2)+k L2 (d2-d1)=k L3 d1 (8)

[0047]

[0048] In the formula, d1 is the average value of the inductance current ripple waveform;

[0049] From the ripple waveform of R s1 i1, R s2 i2, we can get

[0050]

[0051]

[0052] Small signal perturbation is applied to the variable in formula (10) and (11),

[0053] The small signal expression of d1 and d2 is obtained respectively as follows:

[0054]

[0055]

[0056] In the formula:

[0057]

[0058]

[0059]

[0060]

[0061]

[0062]

[0063]

[0064] According to formula (3), (12) and (13), I 2 The cross-influence transfer function Z1(s) of the LED1 output branch of the SIDO Buck LED driving power supply and the cross-influence transfer function Z2(s) of the LED2 output branch are respectively:

[0065]

[0066]

[0067] By adopting the above technical scheme, the application has the following beneficial effects: the application describes the working principle of the SIDO Buck LED driving power supply, adopts the state space average method, and establishes the state space average model thereof. 2 The application controls the SIDO Buck LED driving power supply, analyzes the circuit structure and working principle thereof in detail, and deduces the cross-influence transfer function. Based on the bode diagram of the cross-influence transfer function, the I 2The cross-influence between output branches of the control and voltage control SIDO Buck LED driving power supply is controlled. The theoretical and experimental results show that, compared with the voltage control SIDO Buck LED driving power supply, the I 2 The cross-influence between output branches of the control SIDO Buck LED driving power supply is effectively reduced. BRIEF DESCRIPTION OF DRAWINGS

[0068] Figure 1 The schematic diagram of the SIDO Buck LED driving power supply is shown in the figure.

[0069] Figure 2 The circuit topology diagram of the switch state I of the SIDO Buck LED driving power supply is shown in the figure.

[0070] Figure 3 The circuit topology diagram of the switch state II of the SIDO Buck LED driving power supply is shown in the figure.

[0071] Figure 4 The circuit topology diagram of the switch state III of the SIDO Buck LED driving power supply is shown in the figure.

[0072] Figure 5 The schematic diagram of the I 2 The schematic diagram of the control SIDO Buck LED driving power supply is shown in the figure.

[0073] Figure 6 The control timing diagram of the I 2 The control timing diagram of the control SIDO Buck LED driving power supply is shown in the figure.

[0074] Figure 7 The bode diagram of the cross-influence transfer function is shown in the figure.

[0075] Figure 8 The experimental waveform diagram of the output current of iref1 mutation (i2=0.8A, iref1=1.6→0.8) is shown in the figure.

[0076] Figure 9 The experimental waveform diagram of the output current of iref2 mutation (i1=0.2A, iref2=3.2→1.6) is shown in the figure. DETAILED DESCRIPTION

[0077] The embodiments of the present application are described in detail below with reference to the accompanying drawings, but the present application can be implemented in various different ways limited and covered by the claims.

[0078] 1. The SIDO Buck LED driving power supply

[0079] 1.1 Working principle

[0080] Figure 1The SIDO Buck LED driving power supply is shown in the attached figure, which includes input voltage v i , inductor L, output capacitors C1 and C2, diodes D1 and D2, switches S1 and S2, LED1 output branch and LED2 output branch.v i The energy is transferred to LED1 and LED2 output branches through inductor L, and i1, i2 and v1, v2 (v1>v2) are output current and output voltage of LED1 and LED2 output branches respectively. The control signal and on-duty of S1 and S2 are V g1 , V g2 and d1, d2 respectively.

[0081] The on-duty d1 and d2 have three relationships: d1 Figures 2-4 .

[0082] 1) Switching state I: switches S1 and S2 are on, and diodes D1 and D2 are off; input voltage v i charges inductor L and capacitor C2, and supplies power to LED2; capacitor C1 supplies power to LED1.

[0083] 2) Switching state II: diodes D1 and D2 are on, and switches S1 and S2 are off; inductor L charges capacitor C1, and supplies power to LED1; capacitor C2 supplies power to LED2.

[0084] 3) Switching state III: switch S2 and diode D1 are on, and switches S1 and diode D2 are off; inductor L charges capacitor C2, and supplies power to LED2; capacitor C1 supplies power to LED1.

[0085] 1.2 Small signal model

[0086] Let state variable x = [i L v1 v2] T , and input vector u = [v i v d1 v d2 ] T , where v d1 and v d2 are turn-on voltage of LED1 and LED2 respectively, and R d1 and R d2 are equivalent resistance of LED1 and LED2 respectively. The corresponding state equations of SIDO Buck LED driving power supply working in switching state I, switching state II and switching state III are as follows:

[0087]

[0088] In the formula, matrices A1~A3 and B1~B3 are respectively:

[0089]

[0090]

[0091] Using the state-space averaging method, the state-space average model of the SIDO Buck LED driver power supply can be obtained as follows:

[0092]

[0093] In the formula The average value of the state variables. Let A = d2A1 + (1 - d2)A2, B = d1B3 + (1 - d1)B1, then the coefficient matrices A and B are respectively:

[0094]

[0095] Applying a small-signal perturbation to the variables in equation (2) yields the following:

[0096] The small-signal model of the SIDO Buck LED driver power supply is:

[0097]

[0098] In the formula, the uppercase letter variables are DC steady-state quantities, and the variables with "^" are small-signal disturbance quantities.

[0099] 2 I 2 Control the SIDO Buck LED driver power supply

[0100] 2.1 Working Principle

[0101] Figure 5 For I 2 The schematic diagram of the SIDO Buck LED driver power supply is as follows: Figure 1 The main circuit and I shown 2 The control circuit consists of two parts, including I. 2 Control circuits I and I 2 Control circuit II. In I 2 In control circuit I, the sampling resistor R s1 The sampled output current i1 is then passed through error amplifier AM1 and compared with the reference signal i. ref1 The signal v is obtained after subtraction. o1 ;v o1 The amplified error signal v is obtained through compensator PI1. c1 vc1 v ramp1 is added to get signal v e1 ; sampling output current R s1 i1 and v e1 is compared by comparator CM1, and the comparison result and clock signal clk are input to the S terminal and R terminal of flip-flop RS1 respectively; the control signal V g1 is output from the Q terminal of flip-flop RS1 to control the on and off of switch S1.

[0102] Similarly, in I 2 control circuit II, sampling resistor R s2 sampling output current i2 is compared with reference signal i ref2 by error amplifier AM2 to get signal v o2 ; v o2 is obtained by compensator PI2 to get amplified error signal v c2 , v c2 is added to get signal v ramp2 ; v e2 is obtained by compensator PI2 to get amplified error signal v s2 ; sampling output current R e2 i2 and v g2 is compared by comparator CM2, and the comparison result and clock signal clk are input to the S terminal and R terminal of flip-flop RS2 respectively; the control signal V 2 is output from the Q terminal of flip-flop RS2 to control the on and off of switch S2.

[0103] Figure 6 The control timing of I 2 control SIDO Buck LED driving power supply is shown, at nT moment, sampling output current R s1 i1 is less than signal v e1 , comparator CM1 outputs high level, flip-flop RS1 is set, and switch S1 is turned on; at the same time, sampling output current R s2 i2 is less than signal v e2 , comparator CM2 outputs high level, flip-flop RS2 is set, and switch S2 is turned on; inductor current i L rises with slope k L3 , R s1 i1 falls with slope -k2, and sampling R s2 i2 rises with slope k4.

[0104] When clock signal clk comes, flip-flop RS1 and RS2 are reset, switches S1 and S2 are turned off, i L falls with slope -k L1 , R s1 i1 rises with slope k1, and R s2 i2 falls with slope -k3. When Rs2 i2 drops to signal v e2 When comparator CM2 outputs a high level, flip-flop RS2 is set, switch S2 is turned on, and switch S1 remains off. L With slope -k L2 R continues to decline s2 i2 rises with a slope of k4, R s1 i1 decreases with a slope of -k2; until R... s1 i1 drops to v e1 The circuit then enters the next switching cycle.

[0105] Inductor current slope k L1 k L2 k L3 They are respectively:

[0106]

[0107] The slopes k1 to k4 of the sampled output current are as follows:

[0108]

[0109] 2.2 Cross-influence transfer function

[0110] Depend on Figure 5 The amplified error signal v can be obtained c1 and v c2 They are respectively:

[0111]

[0112]

[0113] In the formula, k p1 k p2 These are the proportional coefficients of compensators PI1 and PI2, respectively, k i1 k i2 These are the integral coefficients of compensators PI1 and PI2, respectively.

[0114] Depend on Figure 6 in i L The ripple waveform can be obtained.

[0115] k L1 (1-d2)+k L2 (d2-d1)=k L3 d1 (8)

[0116]

[0117] In the formula, This represents the average value of the inductor current ripple waveform. (From...) Figure 6 Chinese Rs1 i1, R s2 i2, the ripple waveform, can be obtained

[0118]

[0119]

[0120] The small signal perturbation quantity is applied to the variable in formula (10), (11), and the small signal expression of d1, d2 is obtained respectively:

[0121]

[0122]

[0123] In the formula:

[0124]

[0125]

[0126]

[0127]

[0128]

[0129]

[0130]

[0131] According to formula (3), (12) and (13), I 2 The cross-influence transfer function Z1(s) of the LED1 output branch of the SIDO Buck LED driving power supply and the cross-influence transfer function Z2(s) of the LED2 output branch are respectively:

[0132]

[0133]

[0134] According to the existing literature "Chen L, Xu L M and Zhang L Y, et al. Cross regulation analysis of voltage-mode controlled SIDO buck LED driver [C]. 2021 IEEE 16th Conference on Industrial Electronics and Applications, 2021: 1868-1871", the cross-influence transfer function Z'1(s) of the LED1 output branch and the cross-influence transfer function Z'2(s) of the LED2 output branch of the voltage-controlled SIDO Buck LED driver power supply are as follows:

[0135]

[0136]

[0137] 3 Cross-influence analysis

[0138] According to the circuit parameters in Table 1 and according to the formula (14)-(17), the I Figure 7 2 The Bode diagram of the cross-influence transfer functions Z1(s), Z2(s), Z'1(s) and Z'2(s) of the current-controlled and voltage-controlled SIDO Buck LED driver power supply, wherein the solid line represents the amplitude-frequency curve and the phase-frequency curve of Z1(s) and Z2(s), and the dashed line represents the amplitude-frequency curve and the phase-frequency curve of Z'1(s) and Z'2(s). The low-frequency gain amplitude size reflects the cross-influence size, the smaller the low-frequency gain amplitude, the smaller the cross-influence; the larger the low-frequency gain amplitude, the larger the cross-influence.

[0139] Table 1 I 2 Circuit parameters of the current-controlled SIDO Buck LED driver power supply

[0140]

[0141] From Figure 7 It can be seen from (a) and (b) that the low-frequency gain of the amplitude-frequency curve of Z1(s) and Z2(s) is smaller than that of Z'1(s) and Z'2(s). It shows that 2 The cross-influence of the LED2 output branch on the LED1 output branch or the cross-influence of the LED1 output branch on the LED2 output branch of the current-controlled SIDO Buck LED driver power supply is smaller.

[0142] The above frequency domain analysis shows that, compared with the voltage-controlled SIDO Buck LED driver power supply, the I 2 ​Controlling the SIDO Buck LED driver power supply reduces the crossover effect between the two output branches.

[0143] 4. Experimental Verification

[0144] To verify the correctness of the theoretical analysis, I was designed. 2 The experimental circuit parameters for controlling the SIDO Buck LED driver are shown in Table 1, and the experimental waveforms are shown in Table 1. Figure 8 and Figure 9 As shown.

[0145] Figure 8 The output current is i2 = 0.8A, i ref1 Experimental results of the cross-influence of the LED1 output branch on the LED2 output branch when i = 1.6 → 0.8 (i1 = 0.4A → 0.2A). From Figure 8 (a) It can be seen that the cross-effect of the voltage-controlled SIDO Buck LED driver power supply LED1 output branch on the LED2 output branch is 0.25A; from Figure 8 (b) It can be seen that I 2 The cross-effect of the output branch of the SIDO Buck LED driver power supply LED1 on the output branch of LED2 is 0.09A. This indicates that the reference signal i ref1 When mutated, I 2 Compared to voltage-controlled SIDO Buck LED driver power supplies, controlling the SIDO Buck LED driver power supply reduces the cross-influence of the LED1 output branch on the LED2 output branch.

[0146] Figure 9 Given an output current i1 = 0.2A, i ref2 Experimental results of the cross-influence of the LED2 output branch on the LED1 output branch when i = 3.2 → 1.6 (i2 = 0.8A → 0.4A). From Figure 9 (a) It can be seen that the cross-effect of the voltage-controlled SIDO Buck LED driver power supply LED2 output branch on the LED1 output branch is 0.06A; from Figure 9 (b) It can be seen that I 2 The cross-current effect of the output branch of the SIDO Buck LED driver power supply LED2 on the output branch of LED1 is 0.03A. This indicates that the reference signal i ref2 When mutated, I 2 Compared to voltage-controlled SIDO Buck LED driver power supplies, controlling the SIDO Buck LED driver power supply reduces the cross-influence of the LED2 output branch on the LED1 output branch.

[0147] In summary, I 2Compared with the voltage-controlled SIDO Buck LED driver, the cross effect between two output branches is improved in the proposed current-controlled SIDO Buck LED driver. The experimental results verify the correctness of the theoretical analysis.

Claims

1. I 2 A control SIDO Buck LED driving power supply, characterized in that, The main circuit SIDO Buck LED driving power supply and I 2 The control circuit consists of two parts, I 2 The control circuit further comprises I 2 The control circuit I and I 2 The control circuit II; in I 2 In the control circuit I, the sampling resistor R s1 The sampling output current i1, through the error amplifier AM1 with the reference signal i ref1 The difference between the two signals is v o1 ; v o1 Through the compensator PI1 to get the amplified error signal v c1 , v c1 And the ramp signal v ramp1 Addition of signal v e1 ; sampling output current R s1 i1 and v e1 Through the comparator CM1 comparison, the comparison result and clock signal clk are input to the S end and R end of the flip-flop RS1 respectively; the Q end of the flip-flop RS l Output control signal V g1 , to control the on and off of the switch tube S1; Similarly, in I 2 In the control circuit II, the sampling resistor R s2 The sampling output current i2, through the error amplifier AM2 and the reference signal i ref2 After the difference, the signal v o2 ;v o2 Through the compensator PI2, the amplified error signal v c2 , v c2 And the slope signal v ramp2 Add to get the signal v e2 ; sampling output current R s2 i2 and v e2 Through the comparator CM2 comparison, the comparison result and the clock signal clk are input to the S end and the R end of the flip-flop RS2 respectively; the Q end of the flip-flop RS2 outputs the control signal V g2 , to control the conduction and turn-off of the switch tube S2; The SIDO Buck LED driving power supply comprises an input voltage v i , an inductor L, output capacitors C1, C2, diodes D1, D2, switch tubes S1, S2, an LED1 output branch and an LED2 output branch;v i Energy is transferred to the LED1, LED2 output branch through the inductor L, and i1, i2 and v1, v2 are output currents and output voltages of the LED1, LED2 output branch respectively, wherein v1>v2; control signals and conduction duty cycles of S1, S2 are V g1 , V g2 and d1, d2 respectively; There are three size relationships of the conduction duty cycles d1 and d2: d1 < d2, d1 = d2, d1 > d2; when d1 < d2, the SIDO Buck LED driving power source has three switching states: 1) Switching state I: switch S1, S2 are on, diode D1, D2 are off; input voltage v i Inductor L and capacitor C2 are charged, and power is supplied to LED2; capacitor C1 supplies power to LED1; 2) Switching state II: diodes D1 and D2 are turned on, switch tubes S1 and S2 are turned off, the inductor L charges the capacitor C1 and supplies power to LED1; the capacitor C2 supplies power to LED2; 3) Switching state III: switch tube S2 and diode D1 are turned on, switch tube S1 and diode D2 are turned off; the inductor L charges the capacitor C2 and supplies power to LED2; the capacitor C1 supplies power to LED1; Let the state variable x = [i L v1v2] T , the input vector u = [v i v d1 v d2 ] T , where v d1 and v d2 are the turn-on voltages of LED1 and LED2 respectively, and Rd1 and Rd2 are the equivalent resistances of LED1 and LED2 respectively; the corresponding state equations when the SIDO Buck LED driving power supply works in the switching state I, the switching state II and the switching state III are respectively: In the formula, matrices A1-A3 and B1-B3 are respectively: By using the state space averaging method, the state space average model of the SIDO Buck LED driving power source can be obtained as: wherein is the average value of the state variable, is the average value of the input vector; A = d2A1 + (1 - d2)A2, B = d1B3 + (1 - d1)B1, then the coefficient matrices A, B are respectively: Applying a small signal perturbation to the variables in equation (2) gives The small signal model of the SIDO Buck LED driving power source is: In the formula, the capital letter variable is a direct current steady state quantity, the variable with "^" is a small signal disturbance quantity; s is a complex variable; I 2 The control timing of the SIDO Buck LED driving power supply is controlled, and at the moment of nT, the sampling output current R s1 i1 is less than the signal v e1 , the comparator CM1 outputs a high level, the flip-flop RS1 is set, and the switch tube S1 is turned on; at the same time, the sampling output current R s2 i2 is less than the signal v e2 , the comparator CM2 outputs a high level, the flip-flop RS2 is set, and the switch tube S2 is turned on; the inductor current i L rises with a slope k L3 , R s1 i1 falls with a slope -k2, and R s2 i2 rises with a slope k4; When the clock signal clk arrives, flip-flops RS1 and RS2 are reset, and switches S1 and S2 are turned off. L With slope -k L1 Decrease, R s1 i1 rises with a slope of k1, R s2 i2 decreases with a slope of -k3; when R s2 i2 drops to signal v e2 When comparator CM2 outputs a high level, flip-flop RS2 is set, switch S2 is turned on, and switch S1 remains off. L With slope -k L2 R continues to decline s2 i2 rises with a slope of k4, R s1 i1 decreases with a slope of -k2; until R... s1 i1 drops to v e1 The circuit then enters the next switching cycle T; Inductor current slope k L1 , k L2 , k L3 are respectively: The sampling output current slopes k1-k4 are respectively: where i L denotes the inductor current, k L1 , k L2 , k L3 is the inductor current slope instantaneous value.

2. The I 2 A control SIDO Buck LED driving power supply characterized by amplifying the error signal v c1 and v c2 are respectively: where k p1 , k p2 are the proportional coefficients of compensators PI1, PI2, respectively, k i1 , k i2 are the integral coefficients of compensators PI1, PI2, respectively, and s is a complex variable. The inductance current i L of the ripple waveform, can be obtained k L1 (1 - d2) + k L2 (d2 - d1) = k L3 d1(8) In the formula, is the average value of the inductance current ripple waveform; R s1 i1, R s2 i2, a ripple waveform, can be obtained Small signal disturbance quantities are applied to the variables in formula (10), (11), The small signal expressions of the duty cycles d1 and d2 of switch tubes S1 and S2 are respectively: In the formula: wherein K L1 , K L2 , K L3 are the inductance current slope steady-state values, T represents the switching period, K c1 , K c2 respectively represent the slope of the amplified error signal after slope compensation; where the capital letters of the relevant quantities are expressed as DC steady-state quantities, which can be obtained from equations (3), (12) and (13) as I 2 The cross-over influence transfer function Z1(s) of the LED1 output branch and the cross-over influence transfer function Z2(s) of the LED2 output branch of the SIDO Buck LED driving power supply are respectively:

Images