Driving circuit of high-power LED without electrolytic capacitor

Abstract

The invention discloses a high-power LED drive circuit without an electrolytic capacitor, and the drive circuit comprises a drive circuit which comprises a pre-stage protection circuit, an EMI filter circuit, a bridge type rectification conversion circuit, an RCD clamping circuit, a PFC + DC / DC main circuit topology, an output filter, a voltmeter, a voltage collector, an ammeter, a current collector, a control circuit, and an LED load. One end of the pre-stage protection circuit is connected with one end of the EMI filter circuit, the other end of the EMI filter circuit is connected with one end of the bridge type rectification conversion circuit, when the input alternating current voltage of the improved flyback-Zeta electrolytic-capacitor-free driving circuit ranges from 90 V to 220 V, the driving circuit achieves the effect of restraining ripples, and the output voltage of the flyback-Zeta electrolytic-capacitor-free driving circuit is improved. Meanwhile, under the condition of insufficient input power, the problem that ripple suppression voltage is out of control is effectively solved, the requirement for driving an LED load in a constant-current driving mode is met, the proposed driving circuit effectively solves the sudden change of load voltage and current when the circuit is just started, and the possibility of damage to a load LED is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of LED drive circuits, and in particular to a high-power electrolytic capacitor-free LED drive circuit. Background Art

[0002] "Work at sunrise and rest at sunset", lighting plays a vital role in people's life and work. Without the promotion and development of lighting technology, the historical process of mankind would stagnate. The discovery and use of fire allowed people to no longer rely solely on natural light sources for lighting. In the absence of natural light sources, there were also artificial alternative light sources, which achieved the first breakthrough and development of lighting technology. After that, with the discovery and use of electricity in the 18th century, Edison invented the incandescent lamp. Human beings gradually entered the era of electric lighting from the single lighting of fire, realizing the second revolution of lighting technology. However, due to the low photoelectric conversion efficiency and short life of incandescent lamps, people continued to explore and study lighting technology in many aspects, and then invented fluorescent lamps and other gas discharge lamps. However, due to the inherent characteristics of the working principle of such lighting fixtures, the energy loss is large. In order to improve the photoelectric conversion efficiency, people finally discovered LED lighting technology at the end of the 20th century. LED lighting technology combines the working principle of traditional light sources with microelectronic chip technology, and replaces traditional lighting devices with semiconductor light-emitting diode light sources, entering a new era of lighting.

[0003] In order to meet the strategic requirements of energy conservation and emission reduction and the market demand of the lighting industry, various countries are formulating corresponding plans to vigorously develop and promote the engineering application of LED light source lighting. Among the products produced in the numerous LED industry chains, LED driver is one of the important factors affecting the development of LED light sources.

[0004] LED light sources cannot be directly connected to alternating current for lighting, so the function of LED driving circuit in LED lighting is very important and indispensable. Therefore, when designing LED driving circuit, it is necessary to meet the requirements of LED light source energy conversion and flexible regulation. The driving circuit not only affects the various performances of the light emitted by the LED light source, but also affects the reliability, service life, efficiency and electromagnetic compatibility performance of the entire system.

[0005] However, the traditional LED driving circuit has the following disadvantages:

[0006] The service life of traditional LED driving circuits cannot match that of LED light sources. It also causes an imbalance between input energy and load power, ripple in output voltage, and flicker. Summary of the invention

[0007] The purpose of the present invention is to provide a high-power electrolytic capacitor-free LED driving circuit to solve the problem that the service life of the traditional LED driving circuit mentioned in the above background technology cannot match the LED light source, and it also causes an imbalance between the input energy and the load power, and the output voltage has ripples, causing flicker.

[0008] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a high-power electrolytic capacitor-free LED driving circuit, comprising a driving circuit, wherein the driving circuit comprises a pre-stage protection circuit, an EMI filter circuit, a bridge rectifier conversion circuit, an RCD clamping circuit, a PFC+DC / DC main circuit topology, an output filter, a voltmeter, a voltage collection, an ammeter, a current collection, a control circuit and an LED load, wherein one end of the pre-stage protection circuit is connected to one end of the EMI filter circuit, the other end of the EMI filter circuit is connected to one end of the bridge rectifier conversion circuit, the other end of the bridge rectifier conversion circuit is connected to the RCD clamping circuit, and the other end of the bridge rectifier conversion circuit is connected to the RCD clamping circuit. One end of the RCD clamp circuit is connected to one end of the PFC+DC / DC main circuit topology, the other end of the PFC+DC / DC main circuit topology is connected to one end of the output filter, the other end of the output filter is respectively connected to one end of a voltmeter, one end of an ammeter and one end of an LED load, the other end of the voltmeter is connected to one end of the voltage collection, the other end of the ammeter is connected to one end of the current collection, the other end of the voltage collection and the other end of the current collection are both connected to one end of the control circuit, and the other end of the control circuit is connected to a side directly opposite to the PFC+DC / DC main circuit topology.

[0009] As a preferred technical solution of the present invention, the front-stage protection circuit includes a fuse FU, a varistor Rv, a filter EMI and an AC power supply AC, one side of the filter EMI is connected in parallel with the varistor Rv, one end of the varistor Rv is connected to one end of the fuse FU, the other end of the fuse FU is connected to one end of the AC power supply AC, and the other end of the AC power supply AC is connected to the other end of the varistor Rv;

[0010] At the input end of the AC voltage, a pre-stage protection circuit consisting of a fuse FU and a varistor Rv should be added. The fuse is also called a fuse tube. It is the first protection for the LED drive circuit to connect to the AC input mains. In order to protect the LED drive circuit from greater economic losses due to current overload or short circuit failure, a fuse needs to be connected. When selecting a fuse, first select it according to the maximum allowable working voltage. In the case of AC 220V input, we need to select a fuse with a specification of 250V. At the same time, when calculating the fuse's breaking current, in order for the fuse to provide better protection services, it is necessary to substitute the minimum input voltage into the formula to calculate its rated current, and the fuse's breaking current needs to be calculated by multiplying its rated current during normal operation by the fusing factor as follows:

[0011]

[0012] When selecting a varistor, voltage is an important parameter. If the selected voltage is too high, the varistor cannot be closed, and it cannot protect the circuit. If the varistor voltage is too low, the varistor will malfunction, reducing the reliability of the circuit operation. Therefore, when selecting a varistor, select 2-3 times the voltage. The calculation formula is as follows:

[0013] U Rv =(2-3)U in =(2-3)x220=-220V.

[0014] As a preferred technical solution of the present invention, the EMI filter circuit includes a differential mode capacitor C1, a differential mode capacitor C2, a common mode capacitor C3, a common mode capacitor C4, a common mode inductor L1 and a common mode inductor L2, the two ends of one side between the common mode inductor L1 and the common mode inductor L2 are respectively connected to the two ends of the differential mode capacitor C1, the two ends of the other side between the common mode inductor L1 and the common mode inductor L2 are respectively connected to one end of the common mode capacitor C3, one end of the common mode capacitor C4 and the two ends of the differential mode capacitor C2, the other end of the common mode capacitor C3 is connected to the other end of the common mode capacitor C4,

[0015] Differential mode interference refers to the disturbance generated between two power lines. Differential mode capacitors are mainly used to suppress low-frequency differential mode interference. In the event of their failure, personal safety must also be guaranteed. Therefore, when selecting the capacitance value of differential mode capacitors, the worst case scenario should be considered. In different applications, there are three levels of differential mode capacitors for selection, ranging from 0.1-1μF. The current calculation formula for the inductor in the EMI filter is as follows:

[0016]

[0017] The differential mode capacitors C1 and C2 are 0.3μF film capacitors, the common mode capacitors C3 and C4 are debugged based on experience and are selected to be 2.2nF, and the common mode inductors L1 and L2 are selected from the empirical value of 6mH.

[0018] As a preferred technical solution of the present invention, the RCD clamping circuit includes a clamping resistor R clamp , Clamping capacitor C clamp , leakage inductance L k , transformer primary inductor L1, transformer primary inductor L2, transformer secondary diode VD2, clamping diode VD clamp and switch tube Q1, the transformer primary inductor L1 is connected in parallel with the transformer primary inductor L2, one end of the transformer primary inductor L2 is connected to one end of the transformer secondary diode VD2, and one end of the transformer primary inductor L1 is connected to the leakage inductor L k One end of the leakage inductance L k The other end of the clamp capacitor C clamp One end and the clamp resistor R clamp One end of the clamp capacitor C clamp The other end and the clamp resistor R clamp The other end of the clamping diode VD clamp One end of the clamping diode VD is connected clamp The other end is connected to one end of the switch tube Q1.

[0019] When the switch tube Q1 is turned on, the transformer primary inductance L1 and leakage inductance L K At the same time, the inductor currents generated by the two inductors are equal until the switch tube Q1 is turned off, and the currents on the two inductors reach IT. At the moment when the switch tube Q1 is turned off, the secondary diode VD2 of the transformer is still in the cut-off state. At this time, the clamping circuit capacitor C clamp The stored energy passes through the resistor R clamp After the transformer secondary diode VD2 is turned on, the secondary output voltage is a constant value. At this stage, the clamping circuit capacitor C clamp The stored energy is still through the resistor R clamp To release, the clamp capacitor C clamp The stored energy comes entirely from the leakage energy of the leakage inductance. The calculation formula is as follows:

[0020]

[0021] Leakage inductance L K The energy loss is:

[0022]

[0023] Clamping capacitor C clampThe energy stored is:

[0024]

[0025] The combined formulas yield:

[0026]

[0027] In the experimental simulation, a ceramic capacitor with a capacitance of 2.6nF is selected to meet the requirements and settings of non-electrolytic capacitors. The relationship between the clamping capacitor and the clamping resistor is as follows:

[0028]

[0029] Among them, V ripple Take V clamp 5% to 10% of the value. According to the result calculated by the formula, in order to leave a part of the domain for the clamping resistor, a resistor with a resistance value of 2.6k is selected.

[0030] As a preferred technical solution of the present invention, the bridge rectifier conversion circuit is provided with four diodes, and the maximum reverse voltage U RM for:

[0031]

[0032] The effective value of the input current of the full-bridge rectifier is I RMS for:

[0033]

[0034] Among them, P0 is the output power of the LED driving circuit, η is the power efficiency, U IN(MAX) is the minimum value of the AC input voltage, cosφ is the power factor of the circuit, and the rated effective current I of the rectifier bridge at work BR for:

[0035] I BR >2I RMS =3.5A.

[0036] As a preferred technical solution of the present invention, the output filter is provided with output capacitors C2 and C3. The output capacitor C2 represents the energy difference between the input and the output, and the formula is:

[0037]

[0038] Among them, V C2-max is the maximum voltage on capacitor C2, V C2-min is the minimum voltage on capacitor C2, V C2-avg is the average voltage value on capacitor C2, VC 2-ripis the peak value of the ripple on capacitor C2. At the same time, the energy difference between the input and output ends is calculated by the integration method, and the formula is:

[0039]

[0040] The output capacitor C3 is mainly used as the energy source for the auxiliary stage bidirectional flow. This energy flow is not large, and the capacitance value of the output capacitor C3 should not be too large. The calculation formula is as follows:

[0041]

[0042] Where ΔV C3 This is the high-frequency voltage fluctuation output by capacitor C3, which is set to 0.5V based on experience.

[0043] As a preferred technical solution of the present invention, the formula of the current acquisition internal excitation inductance and input current is:

[0044]

[0045] Assuming there is no energy loss from input to output, the average input power should be equal to the power consumed by the load, calculated as:

[0046] P in =P LED

[0047] P LED =V LED xI LED .

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] 1. Use the flyback circuit as the prototype as the main circuit of the drive circuit, and the improved Zeta circuit as the auxiliary stage to establish the simulation experimental circuit diagram of the LED drive system circuit, design the corresponding control strategy method, and select components and calculate parameters for the improved flyback-Zeta electrolytic capacitor-free drive circuit;

[0050] 2. According to the circuit modular design method, the overall drive circuit system is divided into input protection circuit module, rectifier circuit module, RCD clamping circuit module and main circuit DC-DC module, and the components are selected and parameter designs are carried out according to the purposes of different modules;

[0051] 3. When the input AC voltage of the improved flyback-Zeta electrolytic capacitor-free drive circuit is in the range of 90-220V, the drive circuit can suppress the generation of ripples. At the same time, when the input power is insufficient, the problem of ripple suppression voltage out of control is effectively solved, and the constant current drive mode is satisfied to drive the LED load. At the same time, the proposed drive circuit effectively solves the sudden change of load voltage and current when the circuit is just started, reducing the possibility of damage to the load LED;

[0052] 4. Under the condition of wide input voltage, the power factor of the overall drive circuit system reaches more than 98%, and the overall conversion efficiency is higher than 83%, achieving the performance requirements of high power factor and high efficiency of the circuit. The odd-order harmonic content of the tested input current shows that the proposed drive circuit system can basically meet the IEC-61000-3-2C class harmonic standard. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 A circuit diagram of the present invention;

[0054] Figure 2 is a circuit diagram of a front-stage protection circuit of the present invention;

[0055] Figure 3 is a circuit diagram of the EMI filter circuit of the present invention;

[0056] Figure 4 A circuit diagram of an RCD clamping circuit of the present invention;

[0057] Figure 5 is a diagram showing the relationship between input energy and load energy of the present invention;

[0058] Figure 6 It is a simulation model diagram of the driving circuit of the present invention;

[0059] Figure 7 is the input voltage V of the present invention in and input current I in The simulation waveform diagram of

[0060] Figure 8 It is the Fourier analysis diagram of the AC input current of the present invention;

[0061] Fig. 9 It is the output voltage diagram of the rectifier bridge of the present invention;

[0062] Fig.10 The output voltage uC2 of the capacitor C2 and the output voltage uC3 of the ripple suppression capacitor of the present invention are shown;

[0063] Fig.11 The circuit efficiency and power factor curves of the present invention under different input voltage vin conditions are shown in FIG. DETAILED DESCRIPTION

[0064] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions 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 creative work are within the scope of protection of the present invention.

[0065] See also Figure 1-11 The present invention provides a driving circuit for a high-power electrolytic capacitor-free LED, comprising a driving circuit, wherein the driving circuit comprises a pre-stage protection circuit, an EMI filter circuit, a bridge rectifier conversion circuit, an RCD clamping circuit, a PFC+DC / DC main circuit topology, an output filter, a voltmeter, a voltage collection, an ammeter, a current collection, a control circuit and an LED load, wherein one end of the pre-stage protection circuit is connected to one end of the EMI filter circuit, the other end of the EMI filter circuit is connected to one end of the bridge rectifier conversion circuit, the other end of the bridge rectifier conversion circuit is connected to one end of the RCD clamping circuit, the other end of the RCD clamping circuit is connected to one end of the PFC+DC / DC main circuit topology, the other end of the PFC+DC / DC main circuit topology is connected to one end of the output filter, the other end of the output filter is respectively connected to one end of the voltmeter, one end of the ammeter and one end of the LED load, the other end of the voltmeter is connected to one end of the voltage collection, the other end of the ammeter is connected to one end of the current collection, the other end of the voltage collection and the other end of the current collection are both connected to one end of the control circuit, and the other end of the control circuit is connected to a side directly opposite to the PFC+DC / DC main circuit topology.

[0066] The front-stage protection circuit includes a fuse FU, a varistor Rv, a filter EMI and an AC power supply AC, one side of the filter EMI is connected in parallel with the varistor Rv, one end of the varistor Rv is connected to one end of the fuse FU, the other end of the fuse FU is connected to one end of the AC power supply AC, and the other end of the AC power supply AC is connected to the other end of the varistor Rv;

[0067] At the input end of the AC voltage, a pre-stage protection circuit consisting of a fuse FU and a varistor Rv should be added. The fuse is also called a fuse tube. It is the first protection for the LED drive circuit to connect to the AC input mains. In order to protect the LED drive circuit from greater economic losses due to current overload or short circuit failure, a fuse needs to be connected. When selecting a fuse, first select it according to the maximum allowable working voltage. In the case of AC 220V input, we need to select a fuse with a specification of 250V. At the same time, when calculating the fuse's breaking current, in order for the fuse to provide better protection services, it is necessary to substitute the minimum input voltage into the formula to calculate its rated current, and the fuse's breaking current needs to be calculated by multiplying its rated current during normal operation by the fusing factor as follows:

[0068]

[0069] When selecting a varistor, voltage is an important parameter. If the selected voltage is too high, the varistor cannot be closed, and it cannot protect the circuit. If the varistor voltage is too low, the varistor will malfunction, reducing the reliability of the circuit operation. Therefore, when selecting a varistor, select 2-3 times the voltage. The calculation formula is as follows:

[0070] U Rv =(2-3)U in =(2-3)x220=-220V.

[0071] The EMI filter circuit includes a differential mode capacitor C1, a differential mode capacitor C2, a common mode capacitor C3, a common mode capacitor C4, a common mode inductor L1 and a common mode inductor L2. The two ends of one side between the common mode inductor L1 and the common mode inductor L2 are respectively connected to the two ends of the differential mode capacitor C1, and the two ends of the other side between the common mode inductor L1 and the common mode inductor L2 are respectively connected to one end of the common mode capacitor C3, one end of the common mode capacitor C4 and the two ends of the differential mode capacitor C2. The other end of the common mode capacitor C3 is connected to the other end of the common mode capacitor C4.

[0072] Differential mode interference refers to the disturbance generated between two power lines. Differential mode capacitors are mainly used to suppress low-frequency differential mode interference. In the event of their failure, personal safety must also be guaranteed. Therefore, when selecting the capacitance value of differential mode capacitors, the worst case scenario should be considered. In different applications, there are three levels of differential mode capacitors for selection, ranging from 0.1-1μF. The current calculation formula for the inductor in the EMI filter is as follows:

[0073]

[0074] The differential mode capacitors C1 and C2 are 0.3μF film capacitors, the common mode capacitors C3 and C4 are debugged based on experience and are selected to be 2.2nF, and the common mode inductors L1 and L2 are selected from the empirical value of 6mH.

[0075] The RCD clamping circuit includes a clamping resistor R clamp , Clamping capacitor C clamp , leakage inductance L k , transformer primary inductor L1, transformer primary inductor L2, transformer secondary diode VD2, clamping diode VD clamp and switch tube Q1, the transformer primary inductor L1 is connected in parallel with the transformer primary inductor L2, one end of the transformer primary inductor L2 is connected to one end of the transformer secondary diode VD2, and one end of the transformer primary inductor L1 is connected to the leakage inductor L k One end of the connection, leakage inductance L k The other end of the clamp capacitor C clamp One end and the clamp resistor R clamp One end of the clamp capacitor C clamp The other end and the clamp resistor R clamp The other end of the clamping diode VD clamp One end of the clamping diode VD is connected clamp The other end is connected to one end of the switch tube Q1.

[0076] When the switch tube Q1 is turned on, the transformer primary inductance L1 and leakage inductance L K At the same time, the inductor currents generated by the two inductors are equal until the switch tube Q1 is turned off, and the currents on the two inductors reach IT. At the moment when the switch tube Q1 is turned off, the secondary diode VD2 of the transformer is still in the cut-off state. At this time, the clamping circuit capacitor C clamp The stored energy passes through the resistor R clamp After the transformer secondary diode VD2 is turned on, the secondary output voltage is a constant value. At this stage, the clamping circuit capacitor C clamp The stored energy is still through the resistor R clamp To release, the clamp capacitor C clamp The stored energy comes entirely from the leakage energy of the leakage inductance. The calculation formula is as follows:

[0077]

[0078] Leakage inductance L K The energy loss is:

[0079]

[0080] Clamping capacitor C clamp The energy stored is:

[0081]

[0082] The combined formulas yield:

[0083]

[0084] In the experimental simulation, a ceramic capacitor with a capacitance of 2.6nF is selected to meet the requirements and settings of non-electrolytic capacitors. The relationship between the clamping capacitor and the clamping resistor is as follows:

[0085]

[0086] Among them, V ripple Take V clamp 5% to 10% of the value. According to the result calculated by the formula, in order to leave a part of the domain for the clamping resistor, a resistor with a resistance value of 2.6k is selected.

[0087] There are four diodes in the bridge rectifier conversion circuit. The maximum reverse voltage U RM for:

[0088]

[0089] The effective value of the input current of the full-bridge rectifier is I RMS for:

[0090]

[0091] Among them, P0 is the output power of the LED driving circuit, η is the power efficiency, U IN(MAX) is the minimum value of the AC input voltage, cosφ is the power factor of the circuit, and the rated effective current I of the rectifier bridge at work BR for:

[0092] I BR >2I RMS =3.5A.

[0093] The output filter is equipped with output capacitors C2 and C3. Output capacitor C2 represents the energy difference between input and output. The formula is:

[0094]

[0095] Among them, V C2-max is the maximum voltage on capacitor C2, V C2-min is the minimum voltage on capacitor C2, V C2-avg is the average voltage value on capacitor C2, VC 2-rip is the peak value of the ripple on capacitor C2. At the same time, the energy difference between the input and output ends is calculated by the integration method, and the formula is:

[0096]

[0097] The output capacitor C3 is mainly used as the energy source for the auxiliary stage bidirectional flow. This energy flow is not large, and the capacitance value of the output capacitor C3 should not be too large. The calculation formula is as follows:

[0098]

[0099] Where ΔV C3 This is the high-frequency voltage fluctuation output by capacitor C3, which is set to 0.5V based on experience.

[0100] The formula for the current acquisition internal excitation inductance and input current is:

[0101]

[0102] Assuming there is no energy loss from input to output, the average input power should be equal to the power consumed by the load, calculated as:

[0103] P in =P LED

[0104] P LED =V LED xI LED .

[0105] In the present invention, in conjunction with the specification Figure 5 There are two output capacitors on the output side of the driving circuit, namely output capacitor C2 and output capacitor C3. The two capacitors have different functions in the whole system. The main function of C2 is to power the load LED, balance the energy difference between the input energy and the energy required by the load, and buffer the unbalanced energy. In order to verify the correctness and feasibility of the designed circuit, the proposed circuit model is built based on the above calculated component parameters, and the designed control method is combined with the circuit to conduct simulation experimental analysis. Combined with the instructions attached Figure 6 According to the established driving circuit simulation model, we must first verify whether the power factor correction circuit in the circuit makes the power correction factor of the entire circuit reach above 0.95. The simulation results are shown in the attached manual. Figure 7 And the instruction manual Figure 8 As shown in the figure, when the input voltage is 220V, there is basically no phase difference between the input voltage and the input current in the figure. The Fourier analysis of the AC input current shows that the corresponding THD=17.34%. The power factor calculated according to the formula is 98.5%. At the same time, according to the Fourier analysis of the AC input current, it can be seen that the harmonic current content of each order in the AC input current meets the IEC610003-2C class limit, and the harmonic content is less than 11%. When the input voltage is 110V, the power factor is calculated to be 99.6%. Therefore, under different voltage inputs, this circuit achieves a power factor of more than 0.95, which meets the expected expected value. Combined with the attached manual Fig. 9, is the voltage waveform output by the rectifier bridge. When the input voltage is 220V, the voltage waveform output by the rectifier bridge is complete and has no waveform distortion, which lays the foundation for providing high-quality power supply voltage to the transformer in the future. Fig.10 When analyzing the working mode of the circuit, according to the operating characteristics of the working circuit, analyze whether the auxiliary stage circuit has achieved the effect of suppressing the secondary ripple. The voltage uC3 output by the auxiliary stage circuit fluctuates according to the amplitude of the output voltage uC2 of the main circuit, and generates a voltage with a phase opposite to it for ripple suppression. At the same time, the waveform frequency and amplitude of the auxiliary stage output voltage uC3 and the voltage uC2 output by the main circuit are consistent, achieving the effect of dynamic ripple suppression. The voltage uC2 output by the circuit floats around 300V, and the auxiliary stage circuit floats around 0V. When the voltage uC2 is higher than 300V, the auxiliary stage circuit will increase the amplitude of ripple elimination. When the voltage uC2 is lower than 300V, the auxiliary stage circuit will reduce the amplitude of ripple elimination, so that the load LED supply voltage meets 300V, making the entire circuit more stable. At the same time, the auxiliary stage output voltage uC3 is an AC power supply, which balances the problem of imbalance between input power and load power and achieves an energy balance state. Combined with the attached manual Fig.11 Under different voltage conditions, the overall transfer efficiency of the circuit system is above 83%, and the input voltage and efficiency are in a nonlinear relationship. When the voltage reaches 120V, the efficiency of the circuit system reaches a maximum value of 85.2%, which meets the high efficiency standard under the condition of wide input voltage input. Under different voltage conditions, the power factor of the overall circuit system is above 98%, and the input voltage and power factor are in an approximately linear relationship. When the input voltage is 90V, the power factor reaches 99.8%, and when the input voltage is 220V, the power factor reaches 98.5%, which meets the high power factor standard of the circuit.

[0106] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-power electrolytic capacitor-free LED driving circuit, comprising a driving circuit, characterized in that: The driving circuit includes a pre-stage protection circuit, an EMI filter circuit, a bridge rectifier conversion circuit, an RCD clamp circuit, a PFC+DC / DC main circuit topology, an output filter, a voltmeter, a voltage collection, an ammeter, a current collection, a control circuit and an LED load. One end of the pre-stage protection circuit is connected to one end of the EMI filter circuit, the other end of the EMI filter circuit is connected to one end of the bridge rectifier conversion circuit, the other end of the bridge rectifier conversion circuit is connected to one end of the RCD clamp circuit, the other end of the RCD clamp circuit is connected to one end of the PFC+DC / DC main circuit topology, the other end of the PFC+DC / DC main circuit topology is connected to one end of the output filter, the other end of the output filter is respectively connected to one end of the voltmeter, one end of the ammeter and one end of the LED load, the other end of the voltmeter is connected to one end of the voltage collection, the other end of the ammeter is connected to one end of the current collection, the other end of the voltage collection and the other end of the current collection are both connected to one end of the control circuit, and the other end of the control circuit is connected to a side directly opposite to the PFC+DC / DC main circuit topology.

2. A high-power electrolytic capacitor-free LED driving circuit according to claim 1, characterized in that: The front-stage protection circuit includes a fuse FU, a varistor Rv, a filter EMI and an AC power supply AC, one side of the filter EMI is connected in parallel with the varistor Rv, one end of the varistor Rv is connected to one end of the fuse FU, the other end of the fuse FU is connected to one end of the AC power supply AC, and the other end of the AC power supply AC is connected to the other end of the varistor Rv.

3. The high-power electrolytic capacitor-free LED driving circuit according to claim 1, characterized in that: The EMI filtering circuit includes a differential mode capacitor C1, a differential mode capacitor C2, a common mode capacitor C3, a common mode capacitor C4, a common mode inductor L1 and a common mode inductor L2, two ends of one side between the common mode inductor L1 and the common mode inductor L2 are respectively connected to two ends of the differential mode capacitor C1, two ends of the other side between the common mode inductor L1 and the common mode inductor L2 are respectively connected to one end of the common mode capacitor C3, one end of the common mode capacitor C4 and two ends of the differential mode capacitor C2, and the other end of the common mode capacitor C3 is connected to the other end of the common mode capacitor C4.

4. The high-power electrolytic capacitor-free LED driving circuit according to claim 1, characterized in that: The RCD clamp circuit includes a clamp resistor R clamp , Clamping capacitor C clamp , leakage inductance L k , transformer primary inductor L1, transformer primary inductor L2, transformer secondary diode VD2, clamping diode VD clamp and switch tube Q1, the transformer primary inductor L1 is connected in parallel with the transformer primary inductor L2, one end of the transformer primary inductor L2 is connected to one end of the transformer secondary diode VD2, and one end of the transformer primary inductor L1 is connected to the leakage inductor L k One end of the leakage inductance L k The other end of the clamp capacitor C clamp One end and the clamp resistor R clamp One end of the clamp capacitor C clamp The other end and the clamp resistor R clamp The other end of the clamping diode VD clamp One end of the clamping diode VD is connected clamp The other end is connected to one end of the switch tube Q1.

5. The high-power electrolytic capacitor-free LED driving circuit according to claim 1, characterized in that: The bridge rectifier conversion circuit is provided with four diodes, and the maximum reverse voltage U RM for: The effective value of the input current of the full-bridge rectifier is I RMS for: Among them, P0 is the output power of the LED driving circuit, η is the power efficiency, U IN(MAX) is the minimum value of the AC input voltage, cosφ is the power factor of the circuit, and the rated effective current I of the rectifier bridge at work BR for: <h2 style=";text-align:left;direction:ltr">I<h2 style=";text-align:left;direction:ltr"> BR <h2 style=";text-align:left;direction:ltr"> >2I<h2 style=";text-align:left;direction:ltr"> RMS <h2 style=";text-align:left;direction:ltr"> <3.5A.

6. The high-power electrolytic capacitor-free LED driving circuit according to claim 1, characterized in that: The output filter is provided with output capacitors C2 and C3. Output capacitor C2 represents the energy difference between input and output, and its formula is: Among them, V C2-max is the maximum voltage on capacitor C2, V C2-min is the minimum voltage on capacitor C2, V C2-avg is the average voltage value on capacitor C2, VC 2-rip is the peak value of the ripple on capacitor C2. At the same time, the energy difference between the input and output ends is calculated by the integration method, and the formula is: The output capacitor C3 is mainly used as the energy source for the auxiliary stage bidirectional flow. This energy flow is not large, and the capacitance value of the output capacitor C3 should not be too large. The calculation formula is as follows: Where, ΔV C3 This is the high-frequency voltage fluctuation output by capacitor C3, which is set to 0.5V based on experience.

7. The high-power electrolytic capacitor-free LED driving circuit according to claim 1, characterized in that: The formula of the current acquisition internal excitation inductance and input current is: Assuming there is no energy loss from input to output, the average input power should be equal to the power consumed by the load, calculated as: P in =P LED P LED =V LED xI LED 。

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