LED driving circuit

Abstract

The present application relates to an LED driving circuit, comprising: a rectifier and filter module, a flyback circuit module, a constant current buck module, and a dimming module; the input end of the flyback circuit module is connected to the output end of the rectifier and filter module, and the output end of the flyback circuit module is connected to the input end of the constant current buck module; the output end of the constant current buck module is connected to an LED load; the rectifier and filter module is used to rectify and filter an AC signal; the flyback circuit module is used to adjust the signal after rectification and filtering; the constant current buck module is used to perform constant current buck on the adjusted signal and then input it into the LED load to control the LED load; the input end of the dimming module is connected to the LED load, and the output end of the dimming module is connected to the flyback circuit module and the constant current buck module; the dimming module is used to generate a first control signal and a second control signal, so as to solve the problem in the related art that the type of LED lamp is changed, and the power factor and efficiency cannot be taken into account at the same time, thereby increasing the electricity cost.

Description

Technical Field

[0001] The present application relates to the field of electronic technology, and in particular to an LED driving circuit. Background Art

[0002] With the development of electronic technology, LED (Light Emitting Diode) has been widely used due to its advantages of energy saving, environmental protection, low power consumption, long life, etc. In the application process of LED, the performance of LED driving circuit will directly affect the performance of LED. With the continuous improvement of the quality requirements of LED light source, the design of LED driving circuit has become more and more complicated.

[0003] Generally, a suitable LED driving circuit can be configured according to the application of the LED lamp. For example, when used in a home or classroom, the power of the LED lamp is generally required to be within 100W. For the application of LED non-strobe lamps, the input voltage of the LED lamp needs to meet the wide voltage range of 90-264V. Therefore, in the prior art, one LED driving power supply can only adapt to one type of LED lamp. If the type of LED lamp in the current scene changes, the existing LED driving circuit continues to be used to power the new LED lamp, which will increase the electricity cost because it cannot achieve both power factor and efficiency.

[0004] With regard to the change in the type of LED lamps in the related art, the existing LED driving circuit continues to be used to power the new LED lamps. However, since it is impossible to achieve both power factor and efficiency at the same time, the problem of increased electricity costs has not yet been proposed an effective solution. Summary of the invention

[0005] Based on this, it is necessary to provide an LED driving circuit to address the above technical problems so as to solve the problem in the related technology that the type of LED lamp is changed and the new LED lamp is powered by the existing LED driving circuit, which increases the electricity cost because it is impossible to achieve both power factor and efficiency at the same time.

[0006] In this embodiment, an LED driving circuit is provided, the circuit comprising: a rectifier filter module, a flyback circuit module, a constant current buck module, and a dimming module; wherein:

[0007] The input end of the flyback circuit module is connected to the output end of the rectifier and filter module, and the output end of the flyback circuit module is connected to the input end of the constant current buck module; the output end of the constant current buck module is used to connect the LED load;

[0008] The rectifier and filter module is used to obtain an external AC signal, rectify and filter the AC signal to obtain a rectified and filtered signal, and send the rectified and filtered signal to the flyback circuit module; the flyback circuit module is used to adjust the received rectified and filtered signal to obtain an adjusted signal, and send the adjusted signal to the constant current buck module; the constant current buck module is used to perform constant current buck on the adjusted signal and then input it into the connected LED load to control the LED load;

[0009] The input end of the dimming module is used to connect the LED load, and the output end of the dimming module is respectively connected to the control end of the flyback circuit module and the control end of the constant current buck module;

[0010] The dimming module is used to collect the load voltage of the LED load and generate a first control signal and a second control signal based on the load voltage of the LED load; the first control signal is used to control the flyback circuit module to adjust the received rectified and filtered signal; the second control signal is used to control the constant current buck module to perform constant current buck on the adjusted signal.

[0011] In some embodiments, the circuit further comprises the LED load;

[0012] The LED load is connected to the output end of the constant current buck module and the input end of the dimming module.

[0013] In some embodiments, the flyback circuit module is used to adjust the rectified and filtered signal at the primary side of the flyback circuit module based on the first control signal, so that the ratio of the secondary side voltage of the flyback circuit module to the load voltage of the LED load meets a preset ratio condition.

[0014] In some of the embodiments, the dimming module includes a signal acquisition unit and a dimming unit;

[0015] The signal acquisition unit is connected to the input end of the dimming unit, and is used to acquire an external control signal and send the external control signal to the dimming unit;

[0016] The input end of the dimming unit is used to connect the LED load, and the output end of the dimming unit is respectively connected to the control end of the flyback circuit module and the control end of the constant current buck module; the dimming unit is used to collect the load voltage of the LED load, and generate the first control signal and the second control signal based on the load voltage of the LED load and the external control signal.

[0017] In some of the embodiments, the dimming unit includes a control subunit and an optical coupling subunit;

[0018] The input end of the control subunit is connected to the signal acquisition unit and the LED load respectively, and the output end of the control subunit is connected to the input end of the optocoupler subunit and the control end of the constant current buck module respectively; the control subunit is used to collect the load voltage of the LED load and receive the external control signal sent by the signal acquisition unit, and generate an optocoupler control signal and the second control signal based on the load voltage of the LED load and the external control signal, and send the optocoupler control signal to the optocoupler subunit;

[0019] The output end of the optocoupler subunit is connected to the flyback circuit module, and is used to generate the first control signal based on the optocoupler control signal.

[0020] In some embodiments, the optical coupler subunit includes: an optical coupler group and a first resistor group; the optical coupler group includes two or more optical couplers; the first resistor group includes three or more resistors;

[0021] The input end of the optocoupler group is connected to the control subunit; the output end of the optocoupler group is connected to one end of the first resistor group; the other end of the first resistor group is connected to the flyback circuit module;

[0022] The optocoupler group is used to control the on and off of each resistor in the first resistor group based on the optocoupler control signal; the first resistor group is used to generate the first control signal based on the on and off of each resistor in the first resistor group.

[0023] In some of the embodiments, the dimming module is further configured to send the second control signal to the constant current buck module in the form of a PWM signal or an analog signal based on the external control signal.

[0024] In some embodiments, the flyback circuit module includes: a first capacitor, a second capacitor, a third capacitor, a first resistor, a transformer, a first diode, a second diode and a first control chip;

[0025] The input end of the first primary coil of the transformer is connected to the first control chip, the output end of the first primary coil of the transformer is respectively connected to one end of the first capacitor and the rectifier and filter module, the input end of the secondary coil of the transformer is connected to the positive electrode of the second diode; the negative electrode of the second diode is respectively connected to the positive electrode of the third capacitor and the constant current step-down module; the other end of the first capacitor, the negative electrode of the third capacitor, and the output end of the secondary coil of the transformer are all grounded;

[0026] The first capacitor, the transformer, the second diode, the third capacitor and the first control chip constitute a flyback circuit of the flyback circuit module;

[0027] The first control chip is also connected to one end of the second capacitor, the cathode of the first diode, the dimming module and one end of the first resistor respectively; the anode of the first diode is connected to the dimming module and the input end of the second primary coil of the transformer respectively; the other end of the second capacitor, the other end of the first resistor and the output end of the second primary coil of the transformer are all grounded;

[0028] The second capacitor, the first diode and the transformer constitute a power supply circuit of the first control chip; the first resistor is a current limiting resistor; the first control chip is used to adjust the rectified and filtered signal at the primary side of the flyback circuit module.

[0029] In some embodiments, the first control chip includes at least one first MOSFET; wherein the material of the first MOSFET is gallium nitride.

[0030] In some embodiments, the constant current buck module includes: an inductor, a third diode, a second resistor, a third resistor, a voltage regulator and a second control chip;

[0031] One end of the inductor is connected to the flyback circuit module and the cathode of the third diode respectively, and the other end of the inductor is connected to the dimming module and the LED load respectively; the anode of the third diode is connected to the LED load and the second control chip respectively; the second control chip is also connected to the dimming module; the inductor, the third diode and the second control chip constitute a constant current buck circuit of the constant current buck module;

[0032] One end of the second resistor is connected to the second control chip, and the other end of the second resistor is grounded; the second resistor is used to control the input current of the LED load;

[0033] One end of the inductor is also connected to one end of the third resistor; the other end of the third resistor is respectively connected to the second control chip and the negative electrode of the voltage regulator; the positive electrode of the voltage regulator is grounded; the third resistor and the voltage regulator constitute the power supply circuit of the second control chip; the second control chip is used to perform constant current step-down control on the regulated signal.

[0034] In some embodiments, the second control chip includes at least one second MOSFET; wherein the material of the second MOSFET is gallium nitride.

[0035] In some embodiments, the dimming module includes: a third control chip and a second resistor group; the second resistor group includes two resistors;

[0036] The third control chip is used to obtain the load voltage of the LED load by sampling; the third control chip is also used to generate the first control signal and the second control signal based on the load voltage of the LED load;

[0037] The second resistor group is used to sample the load voltage of the LED load.

[0038] Compared with the related art, in the present embodiment, an LED driving circuit is provided, comprising: a rectifier and filter module, a flyback circuit module, a constant current buck module and a dimming module; wherein: the input end of the flyback circuit module is connected to the output end of the rectifier and filter module, the output end of the flyback circuit module is connected to the input end of the constant current buck module; the output end of the constant current buck module is used to connect to the LED load; the input end of the dimming module is used to connect to the LED load, and the output end of the dimming module is respectively connected to the control end of the flyback circuit module and the control end of the constant current buck module. The invention collects the load voltage of the LED load, generates a first control signal and a second control signal based on the load voltage of the LED load, controls the flyback circuit module to adjust the received rectified and filtered signal through the first control signal, controls the constant current buck module to perform constant current buck on the adjusted signal through the second control signal, controls the output voltage of the flyback circuit module through the load voltage of the LED load, controls the input of the LED load by using the constant current buck module to match the voltage after the LED type is changed, and achieves both power factor and efficiency. The invention solves the problem in the related technology that the type of LED lamp is changed, and the existing LED driving circuit is continued to be used to power the new LED lamp, but the power cost is increased because the power factor and efficiency cannot be achieved at the same time.

[0039] Details of one or more embodiments of the present application are set forth in the following drawings and description to make other features, objects, and advantages of the present application more readily apparent. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0041] Figure 1 is a schematic structural diagram of a first LED driving circuit of this embodiment;

[0042] Figure 2 is a structural schematic diagram of a second LED driving circuit of this embodiment;

[0043] Figure 3 is a schematic structural diagram of a third LED driving circuit of this embodiment;

[0044] Figure 4 Schematic diagram of the circuit structure of an LED driving circuit of this embodiment. DETAILED DESCRIPTION

[0045] In order to more clearly understand the purpose, technical solutions and advantages of the present application, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments.

[0046] Unless otherwise defined, the technical terms or scientific terms involved in this application shall have the general meaning understood by people with general skills in the technical field to which this application belongs. The words "one", "a", "the", "these" and the like in this application do not indicate a quantitative limitation, and they may be singular or plural. The terms "include", "comprise", "have" and any variants thereof involved in this application are intended to cover non-exclusive inclusions; for example, a process, method and system, product or device comprising a series of steps or modules (units) is not limited to the listed steps or modules (units), but may include unlisted steps or modules (units), or may include other steps or modules (units) inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "multiple" involved in this application refers to two or more. "And / or" describes the association relationship of associated objects, indicating that there may be three relationships, for example, "A and / or B" may mean: A exists alone, A and B exist at the same time, and B exists alone. Generally, the character " / " indicates that the objects associated with each other are in an "or" relationship. The terms "first", "second", "third", etc. in this application are only used to distinguish similar objects and do not represent a specific ordering of the objects.

[0047] See also Figure 1 , Figure 1 1 is a schematic diagram of the structure of the first LED driving circuit 100 of this embodiment. Figure 1As shown, the LED driving circuit 100 includes: a rectifier and filter module 110, a flyback circuit module 120, a constant current buck module 130, and a dimming module 140; wherein: the input end of the flyback circuit module 120 is connected to the output end of the rectifier and filter module 110, and the output end of the flyback circuit module 120 is connected to the input end of the constant current buck module 130; the output end of the constant current buck module 130 is used to connect the LED load 150; the rectifier and filter module 110 is used to obtain an external AC signal, rectify and filter the AC signal, obtain a rectified and filtered signal, and send the rectified and filtered signal to the flyback circuit module 120; the flyback circuit module 120 is used to adjust the received rectifier and filtered signal to obtain an adjusted signal, and send the adjusted signal To the constant current buck module 130; the constant current buck module 130 is used to input the connected LED load 150 after constant current bucking of the regulated signal to control the LED load 150; the input end of the dimming module 140 is used to connect the LED load 150, and the output end of the dimming module 140 is respectively connected to the control end of the flyback circuit module 120 and the control end of the constant current buck module 130; the dimming module 140 is used to collect the load voltage of the LED load 150, and generate a first control signal and a second control signal based on the load voltage of the LED load 150; the first control signal is used to control the flyback circuit module 120 to adjust the received rectified and filtered signal; the second control signal is used to control the constant current buck module 130 to perform constant current buck on the regulated signal.

[0048] The above-mentioned rectification and filtering module 110 may include a rectification unit and a filtering unit. The above-mentioned filtering unit may be an EMC (Electromagnetic Compatibility) filter, or a filter composed of common-mode inductors, common-mode capacitors and differential-mode capacitors, or other filters or filtering circuits. The specific filtering unit is not specifically limited in this embodiment, as long as it can be used to filter out the high-frequency noise of the external AC signal to obtain a filtered AC signal. The above-mentioned rectification unit may be a rectifier bridge, or other rectification circuits composed of one or more capacitors. The specific rectification unit is not specifically limited in this embodiment, as long as it can be used to convert the filtered AC signal into a DC signal.

[0049] Generally, the external AC signal is input in the form of AC power. When the external AC signal is input into the rectifier and filter module, the rectifier and filter module 110 rectifies and filters the received AC signal to obtain a rectified and filtered signal, and sends the rectified and filtered signal to the flyback circuit module 120. The flyback circuit module 120 adjusts the received rectified and filtered signal to obtain an adjusted signal, and sends the adjusted signal to the constant current buck module 130. The constant current buck module 130 performs constant current buck on the received adjusted signal to obtain a constant current bucked signal, and inputs the constant current bucked signal into the LED load 150, and uses the constant current bucked signal to control the LED load 150.

[0050] For example, for the driving circuit of the LED non-strobe light, its external AC signal can be 90-277Vac AC. When the 90-277Vac AC is input to the rectifier and filter module, the rectifier and filter module 110 rectifies and filters the received AC signal to obtain a rectified and filtered signal, and sends the rectified and filtered signal to the flyback circuit module 120. The flyback circuit module 120 adjusts the received rectified and filtered signal to obtain an adjusted signal with a voltage of 30-80Vdc, and sends the adjusted signal with a voltage of 30-80Vdc to the constant current buck module 130. The constant current buck module 130 performs constant current bucking on the received adjusted signal to obtain a constant current bucked signal, and inputs the constant current bucked signal into the LED load 150, and uses the constant current bucked signal to control the LED load 150. At this time, the constant current bucked signal is suitable for the LED load 150 with a voltage between 25-66Vdc.

[0051] Generally, for the application scenarios of LED non-strobe lights, it is necessary to dim the LED lights. For example, the LED lights in the classroom need to change their brightness appropriately according to the outdoor light, such as lowering the brightness during the day and raising the brightness at night. Directly adjusting the LED load 150 according to the brightness of the external environment will affect the power factor or efficiency of the LED power supply. In order to ensure that the power factor and efficiency are taken into account at the same time during dimming, it is necessary to consider the brightness of the external environment and the load voltage of the LED load 150 at the same time, and adjust the flyback circuit module 120 and the constant current buck module 130 to ensure the power conversion efficiency of the flyback circuit module 120 and the constant current buck module 130. Specifically, the constant current buck module 130 can be controlled according to an external control signal related to the brightness of the external environment, and the flyback circuit module 120 can be controlled according to the external control signal and the load voltage of the LED load 150. By controlling the constant current buck module 130 and the flyback circuit module 120, the power factor and efficiency can be taken into account at the same time.

[0052] In view of the above situation, in this embodiment, a dimming module 140 is connected to the LED driving circuit 100 to collect the load voltage of the LED load 150, and generate a first control signal and a second control signal based on the load voltage of the LED load 150, so as to control the flyback circuit module 120 to adjust the received rectified and filtered signal through the first control signal to ensure the power conversion efficiency of the flyback circuit module 120, and control the constant current buck module 130 to perform constant current buck on the adjusted signal through the second control signal to ensure the power conversion efficiency of the constant current buck module 130. By ensuring the power conversion efficiency of the flyback circuit module 120 and the power conversion efficiency of the constant current buck module 130, the power factor and efficiency of the LED driving circuit 100 are taken into consideration at the same time.

[0053] Based on this, when the type of LED changes, the load voltage of the LED load 150 changes, and a first control signal and a second control signal are generated based on the load voltage of the LED load 150. The first control signal is used to control the flyback circuit module 120 to adjust the received rectified and filtered signal, and the second control signal is used to control the constant current buck module 130 to perform constant current buck on the adjusted signal. The output voltage of the flyback circuit module 120 is controlled by the load voltage of the LED load 150, and the constant current buck module 130 is used to control the input of the LED load 150 to match the voltage after the type of LED changes, so as to achieve both power factor and efficiency. This solves the problem in the related art that when the type of LED lamp changes, the existing LED driving circuit continues to be used to power the new LED lamp, but the electricity cost increases because the power factor and efficiency cannot be achieved at the same time.

[0054] Specifically, as an implementable method, continue to refer to Figure 1 The LED driving circuit 100 also includes an LED load 150 ; the LED load 150 is connected to the output end of the constant current buck module 130 and the input end of the dimming module 140 .

[0055] The LED load 150 may be one or more LED lamps, and specifically may be different types of LED lamps.

[0056] As an implementable embodiment, the flyback circuit module 120 is used to adjust the rectified and filtered signal at the primary side of the flyback circuit module 120 based on the first control signal, so that the ratio of the secondary side voltage of the flyback circuit module 120 to the load voltage of the LED load 150 meets a preset ratio condition.

[0057] The flyback circuit module 120 includes at least one transformer, and the transformer includes a primary coil and a secondary coil. The primary coil of the transformer is connected to the output end of the rectifier and filter module 110, and the signal after rectification and filtering enters the primary coil of the transformer. Therefore, the secondary voltage of the flyback circuit module 120 can be adjusted by adjusting the signal after rectification and filtering at the primary side of the flyback circuit module 120. The primary side of the flyback circuit module 120 can be the primary coil of the transformer of the flyback circuit module 120. The secondary voltage of the flyback circuit module 120 can be the voltage between the input end and the output end of the secondary coil of the transformer of the flyback circuit.

[0058] Because the signal at the secondary side of the flyback circuit module 120 is an adjusted signal, the adjusted signal is the input voltage of the constant current buck module 130, that is, the secondary side voltage of the flyback circuit is the input voltage of the constant current buck module, and the voltage drop between the input voltage and the output voltage of the constant current buck module 130 cannot be too large. If the voltage drop between the input voltage and the output voltage of the constant current buck module 130 is too large, the power conversion efficiency of the constant current buck module 130 will be too low. However, if the voltage drop between the input voltage and the output voltage of the constant current buck module 130 is too small, the second control chip in the constant current buck module 130 will not be able to reach the highest duty cycle. Therefore, the ratio between the input voltage and the output voltage of the constant current buck module 130 must be within a certain range to ensure that the power factor and efficiency of the LED drive circuit are taken into account at the same time. Because the output voltage of the constant current buck module 130 is used to control the LED load 150, that is, there is a certain relationship between the load voltage of the LED load 150 and the output voltage of the constant current buck module 130. Based on this, the load voltage of the LED load 150 can be collected and the ratio of the secondary voltage of the flyback circuit module 120 to the load voltage of the LED load 150 can be controlled to meet the preset ratio condition to ensure that the power factor and efficiency of the LED driving circuit are taken into account at the same time. The above-mentioned preset ratio condition can be set according to the specific situation. Specifically, the above-mentioned preset ratio condition can be determined by historical experience data or experimental results. For example, it can be known from the experimental results that when the ratio of the secondary voltage of the flyback circuit module 120 to the load voltage of the LED load 150 is in the range of 0.6 to 0.8, the power conversion efficiency of the constant current buck module 130 can be guaranteed to reach the preset efficiency threshold. Then, it is necessary to adjust the signal after rectification and filtering at the primary side of the flyback circuit module 120 so that the ratio of the secondary voltage of the flyback circuit module 120 to the load voltage of the LED load 150 is within the range of 0.6 to 0.8. The above-mentioned preset efficiency threshold can be specifically set according to relevant energy efficiency standards or according to specific needs.

[0059] In addition, as an implementable embodiment, Figure 21 is a schematic diagram of the structure of the second LED driving circuit 100 of this embodiment. Figure 2 As shown, the dimming module 140 includes a signal acquisition unit 142 and a dimming unit 144; the signal acquisition unit 142 is connected to the input end of the dimming unit 144, and is used to obtain an external control signal and send the external control signal to the dimming unit 144; the input end of the dimming unit 144 is used to connect to the LED load 150, and the output end of the dimming unit 144 is respectively connected to the control end of the flyback circuit module 120 and the control end of the constant current buck module 130; the dimming unit 144 is used to collect the load voltage of the LED load 150, and generate a first control signal and a second control signal based on the load voltage of the LED load 150 and the external control signal.

[0060] The signal acquisition unit 142 may be a control circuit composed of a WIFI receiving module or an MCU (Microcontroller Unit), or a photosensitive component similar to a light-sensing device. The signal acquisition unit 142 acquires an external control signal, which may be sent to the signal acquisition unit 142 of the dimming module 140 through an external communication module using a communication command such as 485, and may be sent to the signal acquisition unit 142 of the dimming module 140 in the form of an electrical signal or an optical signal. Based on this, the external control signal may be a control signal for generating a first control signal and a second control signal, and the specific external control signal may be an electrical signal or an optical signal.

[0061] Further, as an implementable embodiment, Figure 3 is a schematic diagram of the structure of the third LED driving circuit of this embodiment. Figure 3 As shown, the dimming unit 144 includes a control subunit 1442 and an optocoupler subunit 1444; the input end of the control subunit 1442 is respectively connected to the signal acquisition unit 142 and the LED load 150, and the output end of the control subunit 1442 is respectively connected to the input end of the optocoupler subunit 1444 and the control end of the constant current buck module 130; the control subunit 1442 is used to collect the load voltage of the LED load 150 and the external control signal sent by the receiving signal acquisition unit 142, and based on the load voltage of the LED load 150 and the external control signal, generate an optocoupler control signal and a second control signal, and send the optocoupler control signal to the optocoupler subunit 1444; the output end of the optocoupler subunit 1444 is connected to the flyback circuit module 120, and is used to generate a first control signal based on the optocoupler control signal.

[0062] Among them, the above-mentioned optocoupler subunit 1444 can be a device of photoelectric transmission or magnetic coupling transmission, which is used to isolate the primary side and the secondary side, and can be specifically used to generate a first control signal based on an optocoupler control signal. In addition, the above-mentioned optocoupler subunit 1444 can be an optocoupler device with at least two optocouplers integrated inside. The above-mentioned optocoupler control signal can be used to control the signal of the optocoupler subunit 1444. The above-mentioned optocoupler control signal can be a high-level signal and a low-level signal.

[0063] Specifically, as an implementable embodiment, the optocoupler subunit 1444 includes: an optocoupler group and a first resistor group; the optocoupler group includes two or more optocouplers; the first resistor group includes three or more resistors; the input end of the optocoupler group is connected to the control subunit 1442; the output end of the optocoupler group is connected to one end of the first resistor group; the other end of the first resistor group is connected to the flyback circuit module 120; the optocoupler group is used to control the on and off of each resistor in the first resistor group based on the optocoupler control signal; the first resistor group is used to generate a first control signal based on the on and off of each resistor in the first resistor group.

[0064] Figure 4 FIG. 1 is a schematic diagram of a circuit structure of an LED driving circuit of this embodiment. Figure 4 As shown, the optocoupler subunit 1444 includes: an optocoupler group and a first resistor group; wherein the optocoupler group includes a first optocoupler OP1 and a second optocoupler OP2; and the first resistor group includes: a first control resistor RB1, a second control resistor RB2, and a third control resistor RB3. The optocoupler subunit 1444 controls the series-parallel connection and the on-off of the first control resistor RB1, the second control resistor RB2, and the third control resistor RB3 through the first optocoupler OP1 and the second optocoupler OP2, and generates a first control signal for controlling the flyback circuit module 120 to adjust the received rectified and filtered signal, thereby controlling the output voltage of the flyback circuit module 120. Among them, the series-parallel connection result of the first control resistor RB1, the second control resistor RB2, and the third control resistor RB3 can be used as a pull-down resistor of the flyback circuit module 120, and is used to control the output voltage of the flyback circuit module 120. It can be seen that the first control signal is to control the flyback circuit module 120 to adjust the received rectified and filtered signal by controlling the pull-down resistor of the flyback circuit module 120.

[0065] For example, when the optocoupler control signal received by the first optocoupler OP1 is at a high level, the first optocoupler OP1 works, the first control resistor RB1 and the second control resistor RB2 are connected in parallel, and the result of the first control resistor RB1 and the second control resistor RB2 being connected in parallel is the pull-down resistor of the flyback circuit module 120. When the optocoupler control signal received by the second optocoupler OP2 is at a high level, the second optocoupler OP2 works, the first control resistor RB1 and the third control resistor RB3 are connected in parallel, and the result of the first control resistor RB1 and the third control resistor RB3 being connected in parallel is the pull-down resistor of the flyback circuit module 120. When the optocoupler control signal received by the first optocoupler OP1 is at a high level, and the optocoupler control signal received by the second optocoupler OP2 is at a high level, the first optocoupler OP1 and the second optocoupler OP2 work simultaneously, the first control resistor RB1, the second control resistor RB2 and the third control resistor RB3 are connected in parallel, and the result of the three control resistors being connected in parallel is the pull-down resistor of the flyback circuit module 120. As the pull-down resistance decreases, the output voltage of the flyback circuit module 120 increases. Based on this, the output voltage of the flyback circuit module 120 is regulated by controlling the resistance of the pull-down resistor.

[0066] As an implementable embodiment, the dimming module 140 is further configured to send a second control signal to the constant current buck module 130 in the form of a PWM signal or an analog signal based on an external control signal.

[0067] Among them, the PWM (Pulse Width Modulation) signal is generally a square wave with a frequency of 100-20khz and a duty cycle of 0-100%, and the analog signal is generally a voltage signal of 0-3.3V. For example, if the second control signal is a PWM signal with a frequency of 10khz and a duty cycle of 30%, the output end of the constant current buck module 130 outputs 30% of the LED load current. If the second control signal is a voltage signal of 1.65V, the output end of the constant current buck module 130 outputs 0.5 times the LED load current.

[0068] The second control signal may be a dimming signal for dimming determined according to an external control signal sent by the signal acquisition unit 142 .

[0069] As an implementation method, continue to see Figure 4, the flyback circuit module 120 includes: a first capacitor C1, a second capacitor C2, a third capacitor C3, a first resistor R1, a transformer T, a first diode D1, a second diode D2 and a first control chip IC1; the input end of the first primary coil of the transformer T is connected to the first control chip IC1, the output end of the first primary coil of the transformer T is respectively connected to one end of the first capacitor C1 and the rectifier filter module 110, the input end of the secondary coil of the transformer T is connected to the positive electrode of the second diode D2; the negative electrode of the second diode D2 is respectively connected to the positive electrode of the third capacitor C3 and the constant current step-down module 130; the other end of the first capacitor C1, the negative electrode of the third capacitor C3, and the output end of the secondary coil of the transformer T are all grounded; the first capacitor C1, the transformer T, the second diode D2, the third capacitor C3 and the first control chip IC1 constitute the flyback circuit of the flyback circuit module 120; the first control chip IC1 is also respectively connected to one end of the second capacitor C2, the cathode of the first diode D1, the dimming module 140 and one end of the first resistor R1; the anode of the first diode D1 is respectively connected to the dimming module 140 and the input end of the second primary coil of the transformer T; the other end of the second capacitor C2, the other end of the first resistor R1, and the output end of the second primary coil of the transformer T are all grounded; the second capacitor C2, the first diode D1 and the transformer T constitute the power supply circuit of the first control chip IC1; the first resistor R1 is a current limiting resistor; the first control chip IC1 is used to adjust the rectified and filtered signal at the primary side of the flyback circuit module 120.

[0070] The flyback circuit module 120 may include a flyback circuit and a control terminal. The control terminal may be a first control chip for receiving a first control signal and controlling the flyback circuit module 120 to adjust the received rectified and filtered signal based on the received first control signal.

[0071] Among them, the output voltage calculation formula of the flyback circuit is:

[0072]

[0073] Among them, V O is the output voltage of the flyback circuit module 120, N S is the number of turns of the secondary coil of transformer T, is the feedback reference voltage of the flyback circuit module 120. Generally, the feedback reference voltage is 2.5V. is a pull-up resistor, is a pull-down resistor, and It constitutes a part of the feedback voltage divider network, which is used to reduce the output voltage of the flyback circuit module 120 in proportion and then compare it with the feedback reference voltage of the flyback circuit module 120. is the number of turns of the auxiliary winding, and the auxiliary winding is used to directly detect the change of the output voltage of the flyback circuit module 120 on the primary coil side, so as to achieve primary side regulation.

[0074] Based on the output voltage calculation formula of the flyback circuit, it can be known that the output voltage of the flyback circuit is related to the turns ratio of the primary coil and the secondary coil of the transformer T, the feedback reference voltage and the resistance value of the feedback voltage divider network. The output voltage of the flyback circuit can be controlled by adjusting the turns ratio of the primary coil and the secondary coil of the transformer T, the feedback reference voltage and the resistance value of the feedback voltage divider network. Because the pull-down resistor RB constitutes a part of the feedback voltage divider network, the output voltage of the flyback circuit can be adjusted by controlling the pull-down resistor RB.

[0075] In addition, the first control chip IC1 may be a control chip using PSR (Primary Side Regulation) technology. In addition, the first control chip IC1 may be an integrated chip with a power factor regulation function.

[0076] As an implementation method, the first control chip IC1 includes at least one first MOSFET (metal oxide semiconductor field effect transistor); wherein the material of the first MOSFET is gallium nitride.

[0077] Because gallium nitride, as a wide bandgap semiconductor material, has the characteristics of high electron mobility, high breakdown voltage, low on-resistance and good thermal stability, the first MOSFET has a withstand voltage of 600-850 V. In addition, the gate charge of the first MOSFET made of gallium nitride is very low, and less energy is consumed during the switching process, which is conducive to improving the efficiency of the flyback circuit module 120.

[0078] In the above embodiment, by designing the first control chip IC1 as a control chip of PSR technology, an integrated chip with a power factor regulation function, and including a first MOSFET made of gallium nitride, the first control chip IC1 has a power factor correction function, so that the harmonic distortion rate is less than 10%, thereby saving costs while ensuring the efficiency of the flyback circuit module 120.

[0079] As an implementation method, continue to see Figure 4The constant current buck module 130 includes: an inductor L, a third diode D3, a second resistor R2, a third resistor R3, a voltage regulator ZD and a second control chip IC2; one end of the inductor L is respectively connected to the flyback circuit module 120 and the cathode of the third diode D3, and the other end of the inductor L is respectively connected to the dimming module 140 and the LED load 150; the anode of the third diode D3 is respectively connected to the LED load 150 and the second control chip IC2; the second control chip IC2 is also connected to the dimming module 140; the inductor L, the third diode D3 and the second control chip IC2 constitute a constant current A constant current step-down circuit of the step-down module 130; one end of the second resistor R2 is connected to the second control chip IC2, and the other end of the second resistor R2 is grounded; the second resistor R2 is used to control the input current of the LED load 150; one end of the inductor L is also connected to one end of the third resistor R3; the other end of the third resistor R3 is respectively connected to the second control chip IC2 and the negative electrode of the voltage regulator ZD; the positive electrode of the voltage regulator ZD is grounded; the third resistor R3 and the voltage regulator ZD constitute the power supply circuit of the second control chip IC2; the second control chip IC2 is used to perform constant current step-down control on the regulated signal.

[0080] The constant current buck module 130 may include a constant current buck circuit and a control terminal. The control terminal may be a control integrated chip. The control terminal is used to receive a second control signal, and based on the received second control signal, control the constant current buck module 130 to perform constant current buck on the regulated signal.

[0081] The formula for controlling the input current of the LED load 150 through the second resistor R2 is as follows:

[0082]

[0083] Wherein, V1 is a reference voltage of the LED load 150 , and the reference voltage is a constant value. , is to set the input current of the LED load to 150.

[0084] Because the reference voltage of the LED load 150 is a fixed value, the input current of the LED load 150 can be set by the second resistor R2.

[0085] In addition, a fourth capacitor C4 can be connected in parallel at both ends of the voltage regulator ZD, and the fourth capacitor and the voltage regulator together form a decoupling circuit. In addition, the fourth capacitor C4 can be used as a decoupling capacitor at the output end of the second control chip IC2 to provide transient response and filtering for the second control chip IC2.

[0086] As an implementation method, the second control chip IC2 includes at least one second MOSFET; wherein the material of the second MOSFET is gallium nitride.

[0087] Since the gate charge of the second MOSFET made of gallium nitride is very low, less energy is consumed during the switching process. Therefore, the use of gallium nitride material is beneficial to improving the power conversion efficiency of the constant current buck module 130 .

[0088] As an implementation method, continue to see Figure 4 The dimming module 140 includes: a third control chip IC3 and a second resistor group; the second resistor group includes two resistors; the third control chip IC3 is used to obtain the load voltage of the LED load 150 by sampling; the third control chip IC3 is also used to generate a first control signal and a second control signal based on the load voltage of the LED load 150; the second resistor group is used to sample the load voltage of the LED load 150.

[0089] The second resistor group includes a fourth resistor R4 and a fifth resistor R5. The third control chip IC3 samples and obtains the load voltage of the LED load 150 through the fourth resistor R4 and the fifth resistor R5.

[0090] Continue to see Figure 4 , Figure 4 The filtering unit in the middle rectifying and filtering module 110 adopts an EMI (Electromagnetic Interference) circuit for filtering, and the rectifying unit adopts a single diode BD1 for rectification.

[0091] It should be noted that the specific examples in this embodiment can refer to the examples described in the above embodiments and optional implementation modes, and will not be repeated in this embodiment.

[0092] It should be understood that the specific embodiments described herein are only used to explain the application, rather than to limit it. Based on the embodiments provided in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of this application.

[0093] Obviously, the drawings are only some examples or embodiments of the present application. For ordinary technicians in the field, the present application can also be applied to other similar situations based on these drawings without creative work. In addition, it is understandable that although the work done in this development process may be complicated and lengthy, for ordinary technicians in the field, certain changes in design, manufacturing or production based on the technical content disclosed in this application are only conventional technical means and should not be regarded as insufficient content disclosed in this application.

[0094] The term "embodiment" in this application refers to a specific feature, structure or characteristic described in conjunction with the embodiment that can be included in at least one embodiment of the present application. The appearance of this phrase in various locations in the specification does not necessarily mean the same embodiment, nor does it mean that it is mutually exclusive with other embodiments and is independent or optional. It is clearly or implicitly understood by those of ordinary skill in the art that the embodiments described in this application can be combined with other embodiments without conflict.

[0095] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of patent protection. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the scope of protection of the present application. Therefore, the scope of protection of the present application shall be subject to the attached claims.

Claims

1. An LED driving circuit, characterized in that: The circuit includes: a rectifier filter module, a flyback circuit module, a constant current buck module, and a dimming module; wherein: The input end of the flyback circuit module is connected to the output end of the rectifier and filter module, and the output end of the flyback circuit module is connected to the input end of the constant current buck module; the output end of the constant current buck module is used to connect the LED load; The rectifier and filter module is used to obtain an external AC signal, rectify and filter the AC signal to obtain a rectified and filtered signal, and send the rectified and filtered signal to the flyback circuit module; the flyback circuit module is used to adjust the rectified and filtered signal at the primary side of the flyback circuit module based on a first control signal, so that the ratio of the secondary side voltage of the flyback circuit module to the load voltage of the LED load meets a preset ratio condition, obtain an adjusted signal, and send the adjusted signal to the constant current buck module; the constant current buck module is used to perform constant current buck on the adjusted signal based on a second control signal and then input the signal into the connected LED load to control the LED load; The input end of the dimming module is used to connect the LED load, and the output end of the dimming module is respectively connected to the control end of the flyback circuit module and the control end of the constant current buck module; The dimming module is used to collect the load voltage of the LED load, and generate an optocoupler control signal and the second control signal based on the load voltage of the LED load and an external control signal, and generate the first control signal based on the optocoupler control signal; the optocoupler control signal is used to generate different pull-down resistors of the flyback circuit module by controlling the on and off of the optocoupler; the different pull-down resistors of the flyback circuit module are used to adjust the output voltage of the flyback circuit module.

2. The LED driving circuit according to claim 1, characterized in that: The circuit also includes the LED load; The LED load is connected to the output end of the constant current buck module and the input end of the dimming module.

3. The LED driving circuit according to claim 1, characterized in that: The dimming module includes a signal acquisition unit and a dimming unit; The signal acquisition unit is connected to the input end of the dimming unit, and is used to acquire the external control signal and send the external control signal to the dimming unit; The input end of the dimming unit is used to connect the LED load, and the output end of the dimming unit is respectively connected to the control end of the flyback circuit module and the control end of the constant current buck module; the dimming unit is used to collect the load voltage of the LED load, and generate the first control signal and the second control signal based on the load voltage of the LED load and the external control signal.

4. The LED driving circuit according to claim 3, characterized in that: The dimming unit includes a control subunit and an optical coupling subunit; The input end of the control subunit is connected to the signal acquisition unit and the LED load respectively, and the output end of the control subunit is connected to the input end of the optocoupler subunit and the control end of the constant current buck module respectively; the control subunit is used to collect the load voltage of the LED load and receive the external control signal sent by the signal acquisition unit, and generate the optocoupler control signal and the second control signal based on the load voltage of the LED load and the external control signal, and send the optocoupler control signal to the optocoupler subunit; The output end of the optocoupler subunit is connected to the flyback circuit module, and is used to generate the first control signal based on the optocoupler control signal.

5. The LED driving circuit according to claim 4, characterized in that: The optical coupler subunit includes: an optical coupler group and a first resistor group; the optical coupler group includes two or more optical couplers; the first resistor group includes three or more resistors; The input end of the optocoupler group is connected to the control subunit; the output end of the optocoupler group is connected to one end of the first resistor group; the other end of the first resistor group is connected to the flyback circuit module; The optocoupler group is used to control the on and off of each resistor in the first resistor group based on the optocoupler control signal; the first resistor group is used to generate the first control signal based on the on and off of each resistor in the first resistor group.

6. The LED driving circuit according to claim 5, characterized in that: The dimming module is further configured to send the second control signal to the constant current buck module in the form of a PWM signal or an analog signal based on the external control signal.

7. The LED driving circuit according to claim 1, characterized in that: The flyback circuit module includes: a first capacitor, a second capacitor, a third capacitor, a first resistor, a transformer, a first diode, a second diode and a first control chip; The input end of the first primary coil of the transformer is connected to the first control chip, the output end of the first primary coil of the transformer is respectively connected to one end of the first capacitor and the rectifier and filter module, the input end of the secondary coil of the transformer is connected to the positive electrode of the second diode; the negative electrode of the second diode is respectively connected to the positive electrode of the third capacitor and the constant current step-down module; the other end of the first capacitor, the negative electrode of the third capacitor, and the output end of the secondary coil of the transformer are all grounded; The first capacitor, the transformer, the second diode, the third capacitor and the first control chip constitute a flyback circuit of the flyback circuit module; The first control chip is also connected to one end of the second capacitor, the cathode of the first diode, the dimming module and one end of the first resistor respectively; the anode of the first diode is connected to the dimming module and the input end of the second primary coil of the transformer respectively; the other end of the second capacitor, the other end of the first resistor and the output end of the second primary coil of the transformer are all grounded; The second capacitor, the first diode and the transformer constitute a power supply circuit of the first control chip; the first resistor is a current limiting resistor; the first control chip is used to adjust the rectified and filtered signal at the primary side of the flyback circuit module.

8. The LED driving circuit according to claim 7, characterized in that: The first control chip includes at least one first MOSFET; wherein the material of the first MOSFET is gallium nitride.

9. The LED driving circuit according to claim 1, characterized in that: The constant current step-down module includes: an inductor, a third diode, a second resistor, a third resistor, a voltage regulator tube and a second control chip; One end of the inductor is connected to the flyback circuit module and the cathode of the third diode respectively, and the other end of the inductor is connected to the dimming module and the LED load respectively; the anode of the third diode is connected to the LED load and the second control chip respectively; the second control chip is also connected to the dimming module; the inductor, the third diode and the second control chip constitute a constant current buck circuit of the constant current buck module; One end of the second resistor is connected to the second control chip, and the other end of the second resistor is grounded; the second resistor is used to control the input current of the LED load; One end of the inductor is also connected to one end of the third resistor; the other end of the third resistor is respectively connected to the second control chip and the negative electrode of the voltage regulator; the positive electrode of the voltage regulator is grounded; the third resistor and the voltage regulator constitute the power supply circuit of the second control chip; the second control chip is used to perform constant current step-down control on the regulated signal.

10. The LED driving circuit according to claim 9, characterized in that: The second control chip includes at least one second MOSFET; wherein the material of the second MOSFET is gallium nitride.

11. The LED driving circuit according to claim 1, characterized in that: The dimming module includes: a third control chip and a second resistor group; the second resistor group includes two resistors; The third control chip is used to obtain the load voltage of the LED load by sampling; the third control chip is also used to generate the first control signal and the second control signal based on the load voltage of the LED load and the external control signal; The second resistor group is used to sample the load voltage of the LED load.

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