An LED lighting circuit suitable for light-storage, direct-flexible buildings

Abstract

The present invention discloses an LED lighting circuit suitable for a photovoltaic-storage-direct-flexible building. The present invention comprises a photovoltaic power supply, an energy storage battery, a DC-DC converter, an LCC resonant converter, and a building LED load; the output end of the photovoltaic power supply is connected to the first low-voltage circuit of the DC-DC converter; the first low-voltage circuit and the second low-voltage circuit of the DC-DC converter are connected in series, and the on-off selection control of the circuit is performed by turning on and off switches Q1 and Q2, together forming the high-voltage circuit of the DC-DC converter; the diode D at the output end of the high-voltage circuit is connected to the first low-voltage circuit of the DC-DC converter; the first low-voltage circuit and the second low-voltage circuit of the DC-DC converter are connected in series, and the on-off selection control of the circuit is performed by turning on and off switches Q1 and Q2, together forming the high-voltage circuit of the DC-DC converter; the diode D at the output end of the high-voltage circuit is connected to the first low-voltage circuit of the DC-DC converter; the first low-voltage circuit and the second low-voltage circuit of the DC-DC converter are connected in series, and the first low-voltage circuit and the second low-voltage circuit ... H In series with the low voltage inductor L I and switch Q2 as the input of the LCC resonant converter; the LCC resonant converter includes a capacitor C in series S 、Inductor L S and capacitor C P , capacitor C P With the diode D L1 、D L2 、D L3 、D L4 The H-bridge circuits formed by the power supply are connected in parallel; the building LED load is connected in parallel with the H-bridge circuit. Compared with traditional photovoltaic LED power supply circuits, the present invention has higher voltage conversion and lower voltage stress on power semiconductor devices, meeting the application requirements of photovoltaic storage and direct-flexible buildings.

Description

Technical Field

[0001] The present invention relates to the technical field of converters, and in particular to an LED lighting circuit suitable for light-storage, direct-flexible buildings. Background Art

[0002] Driving architectural LED lighting is a typical application scenario for solar-storage, direct-flexible buildings. The power supply for high-performance LED lighting systems requires accurate and stable voltage and current output control. Considering the intermittent and uncertain nature of photovoltaic output, traditional DC-DC converters have low output voltage gain and cannot meet the requirements of high-performance LED lighting. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the defects of the above-mentioned prior art and provide an LED lighting circuit suitable for solar-storage, direct-flexible buildings, so that the LED lighting circuit has higher voltage transfer and lower voltage stress of power semiconductor devices to meet the application of solar-storage, direct-flexible buildings.

[0004] To this end, the present invention adopts the following technical solution: an LED lighting circuit suitable for a photovoltaic storage direct-flexible building, which includes a photovoltaic power source, an energy storage battery, a DC-DC converter, an LCC resonant converter and a building LED load;

[0005] The DC-DC converter includes a first low-voltage circuit and a second low-voltage circuit;

[0006] The output end of the photovoltaic power supply is connected to the first low-voltage circuit of the DC-DC converter and performs a maximum power tracking strategy;

[0007] The first low-voltage circuit includes a capacitor C connected in parallel with the photovoltaic power source. F 、With N L Turns of low-voltage inductance L L , switch Q1 with anti-parallel diode D1, capacitor C L , diode D R2 and diode D L The low voltage inductor L L With capacitor C L After parallel connection, they are connected with diode D L The positive and negative electrodes are connected; the capacitor C F With low voltage inductor L L After being connected in series, they are connected in parallel with the positive and negative electrodes of the switch Q1;

[0008] The second low voltage circuit includes a I Turns of low-voltage inductance L I , switch Q2 with anti-parallel diode D2 and diode D R1 , the low voltage inductor L IIn series with switch Q2, low voltage inductor L I With capacitor C I After connecting in series with diode D I in parallel;

[0009] After the first low-voltage circuit and the second low-voltage circuit are connected in series, the on-off selection control of the circuit is performed by turning on and off the switches Q1 and Q2, and together they constitute the high-voltage circuit of the DC-DC converter to control the magnitude of the output voltage;

[0010] The diode D at the output end of the high voltage circuit H In series with the low voltage inductor L I and switch Q2, serving as the input of the LCC resonant converter; the diode D H The negative electrode of is connected in parallel with the switch Q2 and then connected to the positive electrode of the energy storage battery, and the negative electrode of the energy storage battery is connected to the negative electrode of the LED lighting circuit;

[0011] The diode D R1 The cathode of the switch Q2 is connected in series with the diode D R1 The positive electrode is connected to the negative electrode of the energy storage battery;

[0012] The LCC resonant converter includes a series capacitor C S 、Inductor L S and capacitor C P , capacitor C P With the diode D L1 、D L2 、D L3 、D L4 The H-bridge circuit is connected in parallel; the diode D R2 The negative pole and the low voltage inductor L L Series, diode D R2 The positive electrode is connected in series with the capacitor Cs; the building LED load is connected in parallel with the H-bridge circuit and the capacitor C0 respectively.

[0013] Furthermore, the LED lighting circuit applicable to the light-storage direct-flexible building adopts an operating mode including a first operating mode, a second operating mode and a third operating mode;

[0014] In the first working mode, the photovoltaic power source supplies energy to the energy storage and the LED load simultaneously;

[0015] In the second working mode, the photovoltaic power source is disconnected and the LED load is powered by the energy storage;

[0016] In the third working mode, the LED load is disconnected and the photovoltaic power supply outputs electrical energy to charge the energy storage.

[0017] Furthermore, the first operating mode has seven stages, when the gate signal voltage is applied to the switch Q1, the switch Q2 is turned off, and vice versa;

[0018] The gate signal voltages of diodes D1 and D2 are expressed as V G1 、V G2 , the input current of the LED lighting circuit is expressed as i PV , flows through the low voltage inductor L L The current in the branch is represented by i L , flows through capacitor C L The resonant current of the branch is i CL , flows through the low voltage inductor L I The current in the branch is represented by i I , diode D H The current is represented by i DH , diode D L The current is represented by i DL , diode D I The current is represented by i DI , the output current of the LCC resonant converter is expressed as i R , the input voltage of the LCC resonant converter is expressed as V AB ; The output voltage of the photovoltaic power supply is expressed as V PV ;

[0019] The descriptions of the various stages are as follows:

[0020] 1) The first stage, t0<t≤t1

[0021] At t=t0, the moment the switch Q1 is turned on, the photovoltaic power supply circuit is turned on by closing the switch Q1. L The upper excitation generates a current i L , starts to increase from 0, thus obtaining the zero current transition of the switch Q1; the first stage occurs at t0<t<t1, the switch Q2 is closed, and the low-voltage inductor L I Through the diode D I To capacitor C I Charging, at this time, the diode D L and D R2 Close, D H and D R1 Conductive; energized inductor L S Through the capacitor C P , diode D L1 , building LED load, capacitor C0, diode D L2 , diode D R1 and capacitor C S Continuous discharge;

[0022] If the resonant current iCL When it approaches 0 at t=t1, the first stage ends;

[0023] 2) The second stage, t1 <t≤t2

[0024] In the second stage, the switch Q1 is still in the on state; the low-voltage inductor L L The current i L Linearly excited, current i I Continue to add capacitor C I Charging; diode D H At this time, it is in the off state;

[0025] The capacitor C S Through the switch Q1, diode D R2 , diode D L3 , capacitor C0, diode D L4 and inductor L S Powering the building's LED load, the second phase ends at t = t2 with Q1 in the off state;

[0026] 3) The third stage, t2 <t≤t3

[0027] Switch Q2 is turned on; the input current i provided by the photovoltaic power supply PV Becomes zero; low voltage inductance L L Through the capacitor C L and diode D L Discharge; diode D I The current i DI Starts to decrease, diode D I The voltage V DI Starts to increase; diode D H and D R2 Continue to be in the off state;

[0028] The current i I Through the capacitor C I and diode D I Reversing its polarity, capacitor C S Continue through diode D2, diode D L3 , capacitor C0, diode D L4 and inductor L S Provide power to building LED loads;

[0029] At t=t3, the current i DI =0, the third stage ends;

[0030] 4) The fourth stage, t3 <t≤t4

[0031] Switch Q2 is continuously turned on, and diode D H It is forward biased during this phase;

[0032] Photovoltaic power supply through capacitor C L , capacitor C I 、Inductor L I and diode D H Power is supplied to the energy storage battery and capacitor C0, and the inductor L L Continue through diode D L and capacitor C L Discharge, capacitor C S Still continue through diode D2, diode D R2 , diode D L3 , capacitor C0, diode D L4 and inductor L S Provide power to building LED loads;

[0033] At t=t4, the current i L =0, the fourth stage ends;

[0034] 5) Stage 5, T4 <t≤t5

[0035] Switch Q2 is still on and diode D R1 、D R2 Closed, diode D H Continue to forward bias; the photovoltaic power continues to pass through capacitor C L , capacitor C I 、Inductor L I and diode D H Power supply to energy storage battery; capacitor C S Still continue through diode D2, diode D L3 , capacitor C0, diode D L4 and inductor L S Provide power to building LED loads;

[0036] At t=t5, the current i L =0, the fifth stage ends;

[0037] 6) Stage 6, T5 <t≤t6

[0038] Switch Q2 is still in the on state, and diode D R1 、D R2 Closed, diode D H Still in forward bias state; photovoltaic power continues to pass through capacitor C L , capacitor C I 、Inductor L I and diode D H Power is supplied to the energy storage battery and capacitor C0; the energy storage battery supplies power to switch Q2 and capacitor C S , resonant converter circuit diode D L1 、DL2 and building LED load injection power;

[0039] At t=t6, the current i L becomes zero, and the sixth stage ends;

[0040] 7) Stage 7, T6 <t≤t7

[0041] Diode D H Reverse bias, diode D R1 、D R2 When the photovoltaic power source stops supplying power to the energy storage battery and the building LED load, the energy storage battery is connected to the power supply through the switch Q2 and the capacitor C S , diode D L1 and diode D L3 Continue to supply power to the building's LED loads;

[0042] At t=t7, the switch Q1 is in the on state, and the seventh stage ends.

[0043] Furthermore, the circuit equation for the first stage is expressed as:

[0044]

[0045] i CL (t) = i DL (t) = i DH (t)=0 (2)

[0046]

[0047] The circuit equation for the second stage is expressed as:

[0048]

[0049] i CL (t) = i DL (t) = i DH (t)=0 (6)

[0050]

[0051] Where V CI Represents capacitance C I The voltage across both ends.

[0052] Furthermore, the circuit equation for the third stage is expressed as:

[0053] i PV (t)=0 (9)

[0054]

[0055] Where VCL Represents capacitance C L The voltage across the terminals, V CI Represents capacitance C I The voltage across both ends.

[0056] Furthermore, the circuit equation for the fourth stage is expressed as:

[0057]

[0058] i DI (t)=0 (17)

[0059] Where V CI Represents capacitance C I The voltage across the terminals, V CL Represents capacitance C L The voltage across the terminals, V C0 Represents the voltage across capacitor C0.

[0060] Furthermore, the circuit equation for the fifth stage is expressed as:

[0061]

[0062] i L (t) = i DL (t)=0 (19)

[0063] Where V CI Represents capacitance C I The voltage across the terminals, V CL Represents capacitance C L The voltage across the terminals, V C0 Represents the voltage across capacitor C0.

[0064] Furthermore, the circuit equation for the sixth stage is expressed as:

[0065]

[0066] i L (t) = i DL (t)=0 (21)

[0067] Where V CI Represents capacitance C I The voltage across the terminals, V CL Represents capacitance C L The voltage across the terminals, V C0 Represents the voltage across capacitor C0.

[0068] Furthermore, the circuit equation for the seventh stage is expressed as:

[0069] i PV (t) = iCL (t) = i I (t) = i DH (t) = i L (t) = i DL (t)=0 (22)

[0070] At this time, the voltage V AB Expressed as the energy storage battery voltage V using the fundamental frequency approximation method B :

[0071]

[0072] Furthermore, the equivalent mathematical model of the LED lighting circuit includes:

[0073] Use the load circuit quality factor Q L LED light power P LED Expressed as:

[0074]

[0075] Where R L Indicates the LED equivalent resistance, V B Represents the voltage of the energy storage battery; ω s 、ω r They represent the switching angular frequency and equivalent resonant angular frequency of the LCC resonant converter respectively;

[0076] The LED equivalent resistance R L The calculation formula is as follows:

[0077]

[0078] Where R LED The DC equivalent resistance of the LED is obtained from its rated value and is calculated as follows:

[0079]

[0080] Where V LED Indicates the rated DC voltage of LED; I LED Indicates the rated DC current of LED;

[0081] Load circuit quality factor Q L The calculation formula is:

[0082]

[0083] The equivalent resonant angular frequency ω of the LCC resonant converter r The calculation formula is:

[0084]

[0085] Among them, C eq Represents the equivalent capacitance of the LCC resonant converter equivalent circuit; L eq represents the equivalent inductance of the LCC resonant converter equivalent circuit; Z0 represents the equivalent capacitive reactance of the LCC resonant converter equivalent circuit.

[0086] The beneficial effects of the present invention are as follows: The present invention adopts a single-stage, low-cost, simple-structure, high-gain DC-DC converter, and on this basis provides an LED lighting circuit suitable for solar-storage, direct-flexible buildings. The LED lighting circuit has higher voltage conversion and lower voltage stress of power semiconductor devices, meeting the application of solar-storage, direct-flexible buildings. BRIEF DESCRIPTION OF THE DRAWINGS

[0087] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0088] Figure 1 Schematic diagram of the first operating mode of the LED lighting circuit of the present invention;

[0089] Figure 2 Schematic diagram of the second operating mode of the LED lighting circuit of the present invention;

[0090] Figure 3 Schematic diagram of the third operating mode of the LED lighting circuit of the present invention;

[0091] Figure 4 This is a circuit diagram of the first operating mode of the LED lighting circuit of the present invention;

[0092] Figure 5 A circuit diagram of the second operating mode of the LED lighting circuit of the present invention;

[0093] Figure 6 This is a circuit diagram of the third operating mode of the LED lighting circuit of the present invention;

[0094] Figure 7 This is a diagrammatic diagram of the LED lighting circuit theory of the present invention;

[0095] Figure 8 4 is an equivalent circuit diagram of the first stage of the first working mode of the LED lighting circuit of the present invention;

[0096] Figure 9 1 is an equivalent circuit diagram of the second stage of the first working mode of the LED lighting circuit of the present invention;

[0097] Figure 10 4 is an equivalent circuit diagram of the third stage of the first working mode of the LED lighting circuit of the present invention;

[0098] Figure 11 4 is an equivalent circuit diagram of the fourth stage of the first working mode of the LED lighting circuit of the present invention;

[0099] Figure 12 4 is an equivalent circuit diagram of the fifth stage of the first working mode of the LED lighting circuit of the present invention;

[0100] Figure 13 4 is an equivalent circuit diagram of the sixth stage of the first working mode of the LED lighting circuit of the present invention;

[0101] Figure 14 The first working mode of the LED lighting circuit of the present invention is high frequency i L (t) waveform diagram;

[0102] Figure 15 This is the equivalent circuit diagram of the LED lighting resonant converter of the present invention. DETAILED DESCRIPTION

[0103] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0104] The present invention is an LED lighting circuit suitable for a photovoltaic, energy storage, direct-flexible building, which includes a photovoltaic power supply, an energy storage battery, a DC-DC converter, an LCC resonant converter and a building LED load.

[0105] The DC-DC converter includes a first low-voltage circuit and a second low-voltage circuit.

[0106] The output end of the photovoltaic power supply is connected to the first low-voltage circuit of the DC-DC converter and implements a maximum power tracking strategy.

[0107] The first low-voltage circuit includes a capacitor C connected in parallel with the photovoltaic power source. F 、With N L Turns of low-voltage inductance L L , switch Q1 with anti-parallel diode D1, capacitor C L , diode D R2 and diode D L The low voltage inductor L L With capacitor C L After parallel connection, they are connected with diode DL The positive and negative electrodes are connected; the capacitor C F With low voltage inductor L L After being connected in series, they are connected in parallel with the positive and negative electrodes of the switch Q1.

[0108] The second low voltage circuit includes a I Turns of low-voltage inductance L I , switch Q2 with anti-parallel diode D2 and diode D R1 , the low voltage inductor L I In series with switch Q2, low voltage inductor L I With capacitor C I After connecting in series with diode D I in parallel.

[0109] After the first low-voltage circuit and the second low-voltage circuit are connected in series, the on-off selection control of the circuit is performed by opening and closing the switches Q1 and Q2, and together they constitute the high-voltage circuit of the DC-DC converter to control the output voltage.

[0110] The diode D at the output end of the high voltage circuit H In series with the low voltage inductor L I and switch Q2, serving as the input of the LCC resonant converter; the diode D H The negative electrode of the switch Q2 is connected in parallel to the positive electrode of the energy storage battery, and the negative electrode of the energy storage battery is connected to the negative electrode of the LED lighting circuit.

[0111] The diode D R1 The cathode of the switch Q2 is connected in series with the diode D R1 The positive electrode is connected to the negative electrode of the energy storage battery; the LCC resonant converter includes a capacitor C in series S 、Inductor L S and capacitor C P , capacitor C P With the diode D L1 、D L2 、D L3 、D L4 The H-bridge circuit is connected in parallel; the diode D R2 The negative electrode and the inductor L L In series, the diode D R2 The positive electrode is connected in series with the capacitor Cs; the building LED load is connected in parallel with the H-bridge circuit and the capacitor C0 respectively.

[0112] The LED lighting circuit suitable for light-storage direct-flexible buildings adopts a first working mode, a second working mode and a third working mode; the first working mode, such as Figure 1 As shown, the photovoltaic power supply supplies energy to the energy storage and LED load at the same time. The circuit diagram of the first working mode is as follows Figure 4 As shown; the second working mode, as Figure 2 As shown, the photovoltaic power supply is disconnected and the LED load is powered by the energy storage. The circuit diagram of the second working mode is as follows Figure 5 As shown; the third working mode, as Figure 3 As shown, the LED load is disconnected, and the photovoltaic power supply outputs electrical energy to charge the energy storage. The circuit diagram of the third working mode is as follows Figure 6 shown.

[0113] The first operation mode has seven stages. When the gate signal voltage is applied to the switch Q1, the switch Q2 is turned off, and vice versa.

[0114] The gate signal voltages of diodes D1 and D2 are expressed as V G1 、V G2 , the input current of the LED lighting circuit is expressed as i PV , flows through the inductor L L The current in the branch is represented by i L , flows through capacitor C L The harmonic current of the branch is i CL , flows through the inductor L I The current in the branch is represented by i I , diode D H The current is represented by i DH , diode D L The current is represented by i DL , diode D I The current is represented by i DI , the output current of the LCC resonant converter is expressed as i R , the input voltage of the LCC resonant converter is expressed as V AB ; The output voltage of the photovoltaic power supply is expressed as V PV .

[0115] The theoretical waveform of the LED lighting circuit is as follows Figure 7 As shown, the description of each stage is as follows:

[0116] 1) The first stage, t0<t≤t1

[0117] At t=t0, the switch Q1 is turned on; the photovoltaic power supply circuit is turned on by closing the switch Q1, and the inductor L L The upper excitation generates a current i L , starts to increase from 0, thus obtaining the zero current transition of the switch Q1; Figure 8 As shown, the first stage occurs t0<t<t1, the switch Q2 is closed, and the inductor L I Through the diode D I To capacitor C I Charging, at this time, the diode DL and D R2 Close, D H and D R1 Conductive; energized inductor L S Through the capacitor C P , diode D L1 , building LED load, capacitor C0, diode D L2 , diode D R1 and capacitor C S Continuous discharge;

[0118] If the resonant current i CL When it approaches 0 at t=t1, the first stage ends;

[0119] The circuit equation for the first stage is expressed as:

[0120]

[0121] i CL (t) = i DL (t) = i DH (t)=0 (2)

[0122]

[0123] Where V CI Represents capacitance C I The voltage across both ends.

[0124] 2) The second stage, t1 <t≤t2

[0125] like Figure 9 As shown, in the second stage, the switch Q1 is still in the on state; the inductor L L The current i L Linearly excited, current i I Continue to add capacitor C I Charging; diode D H At this time, it is in the off state;

[0126] The capacitor C S Through the switch Q1, diode D R2 , diode D L3 , capacitor C0, diode D L4 and inductor L S Powering the building's LED load, the second phase ends at t = t2 with Q1 in the off state;

[0127] The circuit equation for the second stage is expressed as:

[0128]

[0129] iCL (t) = i DL (t) = i DH (t)=0 (6)

[0130]

[0131] 3) The third stage, t2 <t≤t3

[0132] like Figure 10 As shown, the switch Q2 is turned on; the input current i provided by the photovoltaic power supply PV Becomes zero; inductance L L Through the capacitor C L and diode D L Discharge; diode D I The current i DI Starts to decrease, diode D I The voltage V DI Starts to increase; diode D H and D R2 Continue to be in the off state;

[0133] The current i I Through the capacitor C I and diode D I Reversing its polarity, capacitor C S Continue through diode D2, diode D L3 , capacitor C0, diode D L4 and inductor L S Provide power to building LED loads;

[0134] At t=t3, the current i DI =0, the third stage ends;

[0135] The circuit equation for the third stage is expressed as:

[0136] i PV (t)=0 (9)

[0137]

[0138] Where V CL Represents capacitance C L The voltage across both ends.

[0139] 4) The fourth stage, t3 <t≤t4

[0140] like Figure 11 As shown, switch Q2 is continuously turned on and diode D H It is forward biased during this phase;

[0141] Photovoltaic power supply through capacitor C L , capacitor CI 、Inductor L I and diode D H Power is supplied to the energy storage battery and capacitor C0, and the inductor L L Continue through diode D L and capacitor C L Discharge, capacitor C S Still continue through diode D2, diode D R2 , diode D L3 , capacitor C0, diode D L4 and inductor L S Provide power to building LED loads;

[0142] At t=t4, the current i L =0, the fourth stage ends;

[0143] The circuit equation for the fourth stage is expressed as:

[0144]

[0145] i DI (t)=0 (17)

[0146] Where V C0 Represents the voltage across capacitor C0.

[0147] 5) Stage 5, T4 <t≤t5

[0148] like Figure 12 As shown, switch Q2 is still in the on state and diode D R1 、D R2 Closed, diode D H Continue to forward bias; the photovoltaic power continues to pass through capacitor C L , capacitor C I 、Inductor L I and diode D H Power supply to energy storage battery; capacitor C S Still continue through diode D2, diode D L3 , capacitor C0, diode D L4 and inductor L S Provide power to building LED loads;

[0149] At t=t5, the current i L =0, the fifth stage ends;

[0150] The circuit equation of the fifth stage is expressed as:

[0151]

[0152] i L (t) = i DL(t)=0 (19).

[0153] 6) Stage 6, T5 <t≤t6

[0154] like Figure 13 As shown, the switch Q2 is still in the on state, and the diode D R1 、D R2 Closed, diode D H Still in forward bias state; photovoltaic power continues to pass through capacitor C L , capacitor C I 、Inductor L I and diode D H Power is supplied to the energy storage battery and capacitor C0; the energy storage battery supplies power to switch Q2 and capacitor C S , resonant converter circuit diode D L1 、D L2 and building LED load injection power;

[0155] At t=t6, the current i L becomes zero, and the sixth stage ends;

[0156] The circuit equation for the sixth stage is expressed as:

[0157]

[0158] i L (t) = i DL (t)=0 (21).

[0159] 7) Stage 7, T6 <t≤t7

[0160] Diode D H Reverse bias, diode D R1 、D R2 When the photovoltaic power source stops supplying power to the energy storage battery and the building LED load, the energy storage battery is connected to the power supply through the switch Q2 and the capacitor C S , diode D L1 and diode D L3 Continue to supply power to the building's LED loads;

[0161] At t=t7, Q1 is in the on state and the seventh stage ends.

[0162] The circuit equation of the seventh stage is expressed as:

[0163] i PV (t) = i CL (t) = i I (t) = i DH (t) = i L (t) = i DL (t)=0 (22)

[0164] At this time, the voltage V AB Expressed as the energy storage battery voltage V using the fundamental frequency approximation method B :

[0165]

[0166] The equivalent mathematical model of the above LED lighting circuit is as follows:

[0167] Using R L Represents the equivalent resistance of the LED. When the switch Q1 is turned on, the initial value of the current suddenly increases due to the change in the current path. Assuming that the time for the sudden increase in the initial value of the current can be ignored, the low-voltage inductor L L The current i L (t) increases linearly from 0 and can be expressed as:

[0168]

[0169] At this moment, the low-voltage inductor L L The current continues to increase and can be expressed as:

[0170]

[0171] t1=DT s , T s is the switching frequency, D is the duty cycle of switch Q1, and at the end of the first working mode, i L (t) reaches the maximum value I at t3 Lm :

[0172]

[0173] When the switch Q1 is in the off state, at t1 < t < t3, the inductor current is 0. When the switch Q1 is turned off, the low-voltage inductor L L To capacitor C L Therefore, the low voltage inductor L L The current is zero and the discharge time is Figure 14 shown.

[0174] The input power P of the low voltage inductor L It can be expressed as:

[0175]

[0176] Corresponding LED lamp power P lamp It can be expressed as:

[0177]

[0178] Where η is the conversion efficiency of the total circuit, the inductor L I Voltage V I The transformer turns ratio n and inductance L can be used L Voltage V L express:

[0179] V I =nV L =V B (29)

[0180] During normal operation of the circuit, the inductor L L The voltage V L With input voltage V PV consistent, so the voltage V B It can be expressed as:

[0181] V B =nV PV (30)

[0182] Using the second voltage balance equation, the inductor voltage on the low-voltage side is V L becomes zero, which can be expressed as:

[0183]

[0184] D and f s are the duty cycle of the switch and the resonant converter frequency respectively. After simplification, the above equation becomes:

[0185]

[0186] Capacitor C L The voltage V CL and the inductor voltage V L The polarity is opposite, V CL It can be expressed as:

[0187]

[0188] According to Kirchhoff's voltage law, the resonant converter output voltage V out Expressed as:

[0189] V out =V CL +V CI +V PV -V I (34)

[0190] According to the voltage quadratic balance equation, the inductor voltage V in the secondary winding coil I is zero, which can be expressed as:

[0191]

[0192] The voltage gain G of the resonant converter V It can be expressed as:

[0193]

[0194] The photovoltaic power supply voltage V PV The energy storage battery voltage V B Indicates that the power P of the LED lamp lamp It can be expressed as:

[0195]

[0196] Voltage V AB Through the resonant element inductance L S and capacitor C P Applied to the LED tube, that is, the building LED load. Load circuit quality factor Q L Expressed as:

[0197]

[0198] Where, ω r Represents the equivalent resonant angular frequency of the resonant converter; C eq Represents the equivalent capacitance of the LCC resonant converter equivalent circuit; L eq represents the equivalent inductance of the LCC resonant converter equivalent circuit; Z0 represents the equivalent capacitive reactance of the LCC resonant converter equivalent circuit.

[0199] The DC equivalent resistance R of the LED lamp LED It can be obtained from its rated value, which can be expressed as:

[0200]

[0201] Where V LED Indicates the rated DC voltage of LED; I LED Indicates the rated DC current of the LED.

[0202] The basic component of the resonant input voltage is the switching angular frequency of the resonant converter is ω s The sinusoidal voltage is assumed to be zero phase angle. In the case of AC, the bridge rectifier with capacitor filter follows the LED equivalent resistance R L It is assumed that the power transfer from input to output is achieved through the fundamental component and all harmonic contributions are eliminated. The LED equivalent resistance R L It can be expressed as:

[0203]

[0204] According to the resonant converter equivalent circuit, Figure 15As shown, the circuit equivalent impedance Z AB It can be expressed as:

[0205]

[0206] According to the equivalent circuit of the resonant converter, the voltage transfer function is:

[0207]

[0208] Using the quality factor Q L LED light power P LED It can be expressed as:

[0209]

[0210] Based on the LED lighting circuit of the photovoltaic storage direct flexible building, there is no need to additionally consider related characteristics such as distributed power supply characteristics, light intensity, energy storage battery temperature, etc. A photovoltaic power supply with simple control logic can efficiently and stably drive the LED lighting circuit.

[0211] Application Examples

[0212] A test circuit was built on the MATLAB platform, and a 60W LED streetlight was selected for design. The photovoltaic input voltage was 12V, the energy storage battery voltage was 72V, and the capacity was 50Ah. The switching frequency was 50kHz. The duty cycle D was selected as 0.5. Therefore, the turns ratio of the coupled inductor is 3 according to formula (36). The efficiency is close to 95%. Using formula (28), L L Calculated to be 5.4μH. The maximum input current is 27.7A. L I Using the turns ratio calculated as 48.6μH. To minimize the switch Q1 and diode D L 、D I The current ripple and voltage in L L C L and L I C I The filter cutoff frequency is 10 times lower than the switching frequency. Therefore, the calculated capacitance C L The value is 3.3μF, the capacitor C I The value is 0.2μF. Using the capacitor charge change, the capacitor C H The calculated value is 47.6μF. The calculated lamp resistance is 17.5Ω, the oscillation switching frequency is 1.1, and Q L 、C P and L S The values ​​are 2.1, 3.3μF and 3.6mH. S The value is 33μF.

[0213] Table 1 lists the conversion efficiency of the test circuit under different photovoltaic power supply output voltages. The test results show that the conversion efficiency of the circuit is above 91%, with the highest conversion efficiency reaching 93.25%, which can meet the high-efficiency LED lighting power demand of solar-storage direct-flexible buildings under different photovoltaic outputs.

[0214] Table 1 Test circuit conversion efficiency under different photovoltaic power outputs

[0215] <![CDATA[V PV / V]]> <![CDATA[I PV / mA]]> <![CDATA[P PV / W]]> <![CDATA[I LED / A]]> <![CDATA[V LED / V]]> <![CDATA[P LED / W]]> η / % 1 6 10.56 63.36 1.62 35.6 57.67 91.01 2 7 9.06 63.42 1.63 35.5 57.86 91.23 3 8 7.98 63.89 1.64 35.7 58.54 91.63 4 9 7.04 63.36 1.64 35.6 58.38 92.14 5 10 6.36 63.61 1.65 35.8 59.07 92.86 6 11 5.81 63.96 1.66 35.9 59.59 93.17 7 12 5.34 64.08 1.66 36 59.76 93.25

[0216] It is obvious that those skilled in the art can easily make various modifications to the above embodiments and apply the general principles described herein to other embodiments without requiring creative effort. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention should fall within the scope of protection of the present invention.

Claims

1. An LED lighting circuit suitable for a light-storage, direct-flexible building, characterized in that: Includes photovoltaic power source, energy storage battery, DC-DC converter, LCC resonant converter and building LED load; The DC-DC converter includes a first low-voltage circuit and a second low-voltage circuit; The output end of the photovoltaic power supply is connected to the first low-voltage circuit of the DC-DC converter and performs a maximum power tracking strategy; the first low-voltage circuit includes a capacitor C connected in parallel with the photovoltaic power supply. F 、With N L Turns of low-voltage inductance L L , switch Q1 with anti-parallel diode D1, capacitor C L , diode D R2 and diode D L The low voltage inductor L L With capacitor C L After parallel connection, they are connected with diode D L The positive and negative electrodes are connected; the capacitor C F With low voltage inductor L L After being connected in series, they are connected in parallel with the positive and negative electrodes of the switch Q1; the second low voltage circuit includes a I Turns of low-voltage inductance L I , switch Q2 with anti-parallel diode D2 and diode D R1 , the low voltage inductor L I In series with switch Q2, low voltage inductor L I With capacitor C I After connecting in series with diode D I in parallel; After the first low-voltage circuit and the second low-voltage circuit are connected in series, the on-off selection control of the circuit is performed by turning on and off the switches Q1 and Q2, and together they constitute the high-voltage circuit of the DC-DC converter to control the magnitude of the output voltage; The diode D at the output end of the high voltage circuit H In series with the low voltage inductor L I Between the switch Q2, the diode D H Directly connected to the LCC resonant converter as the input of the LCC resonant converter; the diode D H The negative electrode of is connected in parallel with the switch Q2 and then connected to the positive electrode of the energy storage battery, and the negative electrode of the energy storage battery is connected to the negative electrode of the LED lighting circuit; The diode D R1 The cathode of the switch Q2 is connected in series with the diode D R1 The positive electrode is connected to the negative electrode of the energy storage battery; The LCC resonant converter includes a series capacitor C S 、Inductor L S and capacitor C P , capacitor C P With the diode D L1 、D L2 、D L3 、D L4 The H-bridge circuit is connected in parallel; the diode D R2 The negative pole and the low voltage inductor L L Series, diode D R2 The positive electrode is connected in series with the capacitor Cs; the building LED load is connected in parallel with the H-bridge circuit and the capacitor C0 respectively.

2. The LED lighting circuit suitable for a light-storage, direct-flexible building according to claim 1, characterized in that: The adopted working modes include the first working mode, the second working mode and the third working mode; In the first working mode, the photovoltaic power source supplies energy to the energy storage and the LED load simultaneously; In the second working mode, the photovoltaic power source is disconnected and the LED load is powered by the energy storage; In the third working mode, the LED load is disconnected and the photovoltaic power supply outputs electrical energy to charge the energy storage.

3. The LED lighting circuit suitable for light-storage, direct-flexible buildings according to claim 2, characterized in that: The first operating mode has seven stages. When the gate signal voltage is applied to the switch Q1, the switch Q2 is turned off, and vice versa. The gate signal voltages of diodes D1 and D2 are expressed as V G1 、V G2 , the input current of the LED lighting circuit is expressed as i PV , flows through the low voltage inductor L L The current in the branch is represented by i L , flows through capacitor C L The resonant current of the branch is i CL , flows through the low voltage inductor L I The current in the branch is represented by i I , diode D H The current is represented by i DH , diode D L The current is represented by i DL , diode D I The current is represented by i DI , the output current of the LCC resonant converter is expressed as i R , the input voltage of the LCC resonant converter is expressed as V AB ; The output voltage of the photovoltaic power supply is expressed as V PV ; The descriptions of the various stages are as follows: 1) The first stage, t0<t≤t1 At t=t0, the moment the switch Q1 is turned on, the photovoltaic power supply circuit is turned on by closing the switch Q1. L The upper excitation generates a current i L , starts to increase from 0, thus obtaining the zero current transition of the switch Q1; The first stage occurs at t0<t<t1, the switch Q2 is closed, and the low-voltage inductor L I Through the diode D I To capacitor C I Charging, at this time, the diode D L and D R2 Close, D H and D R1 Conductive; energized inductor L S Through the capacitor C P , diode D L1 , building LED load, capacitor C0, diode D L2 , diode D R1 and capacitor C S Continuous discharge; If the resonant current i CL When it approaches 0 at t=t1, the first stage ends; 2) The second stage, t1 <t≤t2 In the second stage, the switch Q1 is still in the on state; the low-voltage inductor L L The current i L Linearly excited, current i I Continue to add capacitor C I Charging; diode D H At this time, it is in the off state; The capacitor C S Through the switch Q1, diode D R2 , diode D L3 , capacitor C0, diode D L4 and inductor L S Powering the building's LED load, the second phase ends at t = t2 with Q1 in the off state; 3) The third stage, t2 <t≤t3 Switch Q2 is turned on; the input current i provided by the photovoltaic power supply PV Becomes zero; low voltage inductance L L Through the capacitor C L and diode D L Discharge; diode D I The current i DI Starts to decrease, diode D I The voltage V DI Starts to increase; diode D H and D R2 Continue to be in the off state; The current i I Through the capacitor C I and diode D I Reversing its polarity, capacitor C S Continue through diode D2, diode D L3 , capacitor C0, diode D L4 and inductor L S Provide power to building LED loads; At t=t3, the current i DI =0, the third stage ends; 4) The fourth stage, t3 <t≤t4 Switch Q2 is continuously turned on, and diode D H It is forward biased during this phase; Photovoltaic power supply through capacitor C L , capacitor C I 、Inductor L I and diode D H Power is supplied to the energy storage battery and capacitor C0, and the inductor L L Continue through diode D L and capacitor C L Discharge, capacitor C S Still continue through diode D2, diode D R2 , diode D L3 , capacitor C0, diode D L4 and inductor L S Provide power to building LED loads; At t=t4, the current i L =0, the fourth stage ends; 5) Stage 5, T4 <t≤t5 Switch Q2 is still on and diode D R1 、D R2 Closed, diode D H Continue to forward bias; the photovoltaic power continues to pass through capacitor C L , capacitor C I 、Inductor L I and diode D H Power supply to energy storage battery; capacitor C S Still continue through diode D2, diode D L3 , capacitor C0, diode D L4 and inductor L S Provide power to building LED loads; At t=t5, the current i L =0, the fifth stage ends; 6) Stage 6, T5 <t≤t6 Switch Q2 is still in the on state, and diode D R1 、D R2 Closed, diode D H Still in forward bias state; photovoltaic power continues to pass through capacitor C L , capacitor C I 、Inductor L I and diode D H Power is supplied to the energy storage battery and capacitor C0; the energy storage battery supplies power to switch Q2 and capacitor C S , resonant converter circuit diode D L1 、D L2 and building LED load injection power; At t=t6, the current i L becomes zero, and the sixth stage ends; 7) Stage 7, T6 <t≤t7 Diode D H Reverse bias, diode D R1 、D R2 When the photovoltaic power source stops supplying power to the energy storage battery and the building LED load, the energy storage battery is connected to the power supply through the switch Q2 and the capacitor C S , diode D L1 and diode D L3 Continue to supply power to the building's LED loads; At t=t7, the switch Q1 is in the on state, and the seventh stage ends.

4. The LED lighting circuit suitable for a light-storage, direct-flexible building according to claim 3, characterized in that: The circuit equation for the first stage is expressed as: i CL (t)=i DL (t)=i DH (t)=0 (2) The circuit equation for the second stage is expressed as: i CL (t)=i DL (t)=i DH (t)=0 (6) Where V CI Represents capacitance C I The voltage across both ends.

5. The LED lighting circuit suitable for a light-storage, direct-flexible building according to claim 3, characterized in that: The circuit equation for the third stage is expressed as: i PV (t)=0 (9) Where V CL Represents capacitance C L The voltage across the terminals, V CI Represents capacitance C I The voltage across both ends.

6. The LED lighting circuit suitable for a light-storage, direct-flexible building according to claim 3, characterized in that: The circuit equation for the fourth stage is expressed as: i DI (t)=0 (17) Where V CI Represents capacitance C I The voltage across the terminals, V CL Represents capacitance C L The voltage across the terminals, V C0 Represents the voltage across capacitor C0.

7. The LED lighting circuit suitable for a light-storage, direct-flexible building according to claim 3, characterized in that: The circuit equation of the fifth stage is expressed as: i L (t)=i DL (t)=0 (19) Where V CI Represents capacitance C I The voltage across the terminals, V CL Represents capacitance C L The voltage across the terminals, V C0 Represents the voltage across capacitor C0.

8. The LED lighting circuit suitable for a light-storage, direct-flexible building according to claim 3, characterized in that: The circuit equation for the sixth stage is expressed as: i L (t)=i DL (t)=0 (21) Where V CI Represents capacitance C I The voltage across the terminals, V CL Represents capacitance C L The voltage across the terminals, V C0 Represents the voltage across capacitor C0.

9. The LED lighting circuit suitable for a light-storage, direct-flexible building according to claim 3, characterized in that: The circuit equation of the seventh stage is expressed as: i PV (t)=i CL (t)=i I (t)=i DH (t)=i L (t)=i DL (t)=0 (22) At this time, the voltage V AB Expressed as the energy storage battery voltage V using the fundamental frequency approximation method B :

10. The LED lighting circuit applicable to a light-storage, direct-flexible building according to any one of claims 1 to 3, characterized in that: The equivalent mathematical model of the LED lighting circuit includes: Use the load circuit quality factor Q L LED light power P LED Expressed as: Where R L Indicates the LED equivalent resistance, V B Represents the voltage of the energy storage battery; ω s 、ω r They represent the switching angular frequency and equivalent resonant angular frequency of the LCC resonant converter respectively; The LED equivalent resistance R L The calculation formula is as follows: Where R LED The DC equivalent resistance of the LED is obtained from its rated value and is calculated as follows: Where V LED Indicates the rated DC voltage of LED; I LED Indicates the rated DC current of LED; Load circuit quality factor Q L The calculation formula is: The equivalent resonant angular frequency ω of the LCC resonant converter r The calculation formula is: Among them, C eq Represents the equivalent capacitance of the LCC resonant converter equivalent circuit; L eq represents the equivalent inductance of the LCC resonant converter equivalent circuit; Z0 represents the equivalent capacitive reactance of the LCC resonant converter equivalent circuit.

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