LED power supply circuit and lighting system

Abstract

The present application provides an LED power supply circuit, including a rectifier conversion circuit, a first voltage stabilizing unit, a π-type filter, a second voltage stabilizing unit, a power supply management unit, a field effect tube unit, a filter compensation unit and an LED driving unit, which are electrically connected in sequence. The voltage output to the power supply management unit and the field effect tube unit is ensured to be stable through multi-stage voltage stabilization after rectification, and the ripple noise in the circuit is effectively suppressed through the π-type filter, so that the output waveform is more stable, and the flickering phenomenon of the ripple noise in the current when passing through the LED is avoided; the field effect tube unit is driven to output power through the power supply management unit, and the filter compensation unit is used to compensate so that its output continuously outputs a large and stable current, thereby ensuring that the LED can work stably, and the power supply current and voltage are monitored through voltage feedback and current feedback to ensure that the power supply circuit can work stably.

Description

Technical Field

[0001] The present application relates to the technical field of filter circuits, and in particular to an LED power supply circuit and a lighting system. Background Art

[0002] LED (Lighting Emitting Diode) lighting is light-emitting diode lighting, which is a semiconductor solid light-emitting device. It uses solid semiconductor chips as luminescent materials, and emits photons through the excess energy released by carrier recombination in the semiconductor, directly emitting red, yellow, blue, and green light. On this basis, using the principle of three primary colors and adding phosphors, it can emit light of any color.

[0003] Research data shows that since LED is a cold light source, semiconductor lighting itself does not pollute the environment. Compared with incandescent lamps and fluorescent lamps, the power saving efficiency can reach more than 90%. At the same brightness, the power consumption is only 1 / 10 of ordinary incandescent lamps and 1 / 2 of fluorescent lamps. If LED replaces 50% of our traditional lighting, the amount of electricity saved in my country each year is equivalent to the total power generation of a Three Gorges Power Station. Its energy-saving benefits are very considerable.

[0004] However, the current LED energy-saving lighting is affected by the power supply system and the circuit and power supply noise, and the LED lights will flicker. On the one hand, it affects the life of the LED, and on the other hand, the flickering phenomenon will affect vision health. Therefore, a stable power supply system and circuit are needed. Summary of the invention

[0005] In view of the above problems, the present application is proposed to provide an LED power supply circuit and a lighting system that overcome the above problems or at least partially solve the above problems.

[0006] The present application discloses an LED power supply circuit, comprising: a rectifier conversion circuit, a first voltage stabilizing unit, a π-type filter, a second voltage stabilizing unit, a power supply management unit, a field effect tube unit, a filter compensation unit and an LED driving unit, which are electrically connected in sequence;

[0007] The rectifying and converting circuit is used to connect to the mains, convert the mains into direct current, and output a first voltage to the first voltage stabilizing unit;

[0008] The first voltage stabilizing unit is used for stabilizing the first voltage and outputting a second voltage to the π-type filter;

[0009] The π-type filter filters the second voltage and outputs a third voltage to the second voltage stabilizing unit;

[0010] The second voltage stabilizing unit outputs the stabilized third voltage to the power supply management unit and the field effect tube unit;

[0011] The field effect tube unit is used to output a fourth voltage to the filtering and compensation unit, and to feed back current to the power supply management unit;

[0012] The filtering and compensating unit is used for processing the fourth voltage into an LED driving voltage, outputting the driving voltage to the LED driving unit, and outputting the driving voltage as a feedback voltage to the power supply management unit.

[0013] Furthermore, it also includes: the interface of the LED driving unit is electrically connected to the power supply management unit, which is used to detect whether the interface is connected to an LED lamp.

[0014] Furthermore, the rectification and conversion circuit comprises:

[0015] Transformer T1, whose primary winding is connected to the mains, and whose secondary winding is connected to a rectifier bridge VD1, is used to transform the mains and output the transformed voltage to the rectifier bridge VD1 for rectification;

[0016] The rectifier bridge VD1 is electrically connected to the input end of the first voltage stabilizing unit, and is used to output direct current to the first voltage stabilizing unit.

[0017] Furthermore, the rectification and conversion circuit further includes:

[0018] The fuse F1 is connected in series between the primary winding of the transformer T1 and the mains; the two ends of the primary winding are also electrically connected to a varistor RV and a filter capacitor C10.

[0019] Further, the first voltage stabilizing unit includes: at least one three-terminal voltage stabilizer;

[0020] The input end of the three-terminal regulator is electrically connected to the output end of the rectifier conversion circuit, and the output end of the three-terminal regulator is electrically connected to the π-type filter.

[0021] Furthermore, the first voltage stabilizing unit further includes: at least two transistors Q20 and Q21 and corresponding two pull-up resistors R21 and R22 and a current limiting resistor R20;

[0022] One end of the current limiting resistor R20 serves as the input end of the first voltage stabilizing unit and is connected to one end of the pull-up resistor R21 and one end of the pull-up resistor R22, and the other end of the current limiting resistor R20 is connected to the input end of the three-terminal voltage regulator and the b-pole of the transistors Q20 and Q21;

[0023] The other end of the pull-up resistor R21 and the other end of the pull-up resistor R22 are connected to the e-pole of the transistors Q20 and Q21 respectively; the c-pole of the transistors Q20 and Q21 is connected to the output end of the three-terminal regulator as the output end of the first voltage stabilizing unit;

[0024] Two ends of the current limiting resistor R20 are respectively connected to a filter capacitor C20 and C21 , and the output end of the three-terminal regulator is also connected to a filter capacitor C22 .

[0025] Furthermore, the π-type filter is an LC-type filter, specifically comprising: a first inductor L1 and electrolytic capacitors C1 and C2 connected at both ends of the first inductor L1. A filter capacitor C3 is further provided between the first inductor L1 and the electrolytic capacitor C2.

[0026] Furthermore, the second voltage stabilizing unit is a TL431 voltage regulating circuit, specifically comprising:

[0027] One end of the current limiting resistor R1 is the input end of the second voltage stabilizing unit; the other end of the current limiting resistor R1 is the output end of the second voltage stabilizing unit, and is connected to the e-pole of the transistor Q5, one end of the current limiting resistor R4 and one end of the voltage dividing resistor R2;

[0028] The b-pole of the transistor Q5 is connected to the other end of the current limiting resistor R4 and the cathode of TL431; the other end of the voltage dividing resistor R2 is connected to one end of the voltage dividing resistor R3 and the reference end of TL431;

[0029] The C-pole of the transistor Q5, the anode of the TL431 and the other end of the voltage-dividing resistor R3 are grounded.

[0030] Furthermore, the second voltage stabilizing unit further includes: a current control unit;

[0031] The current control unit includes a transistor Q6, a transistor Q7 and a resistor R5, wherein the c-pole of the transistor Q6 and the c-pole of the transistor Q7 are connected to one end of the current limiting resistor R1, the e-pole of the transistor Q6 is connected to the b-pole of the transistor Q7 and one end of the resistor R5, and the e-pole of the transistor Q7 and the other end of the resistor R5 are connected to one end of the voltage dividing resistor R2;

[0032] When the second voltage stabilizing unit includes the current control unit, one end of the current limiting resistor R4 in the TL431 voltage regulating circuit, the e-pole of the transistor Q5 and the other end of the current limiting resistor R1 are connected to the b-pole of the transistor Q6.

[0033] The present application also discloses an LED lighting system, comprising an LED lamp and the above-mentioned LED power supply circuit, wherein the LED lamp is connected to an LED driving unit.

[0034] This application has the following advantages:

[0035] In an embodiment of the present application, a rectifier conversion circuit, a first voltage stabilizing unit, a π-type filter, a second voltage stabilizing unit, a power supply management unit, a field effect tube unit, a filter compensation unit and an LED driving unit are electrically connected in sequence; the rectifier conversion circuit is used to connect to the AC power, convert the AC power into direct current, and output a first voltage to the first voltage stabilizing unit; the first voltage stabilizing unit is used to stabilize the first voltage and output a second voltage to the π-type filter; the π-type filter filters the second voltage and outputs a third voltage to the second voltage stabilizing unit; the second voltage stabilizing unit outputs the stabilized third voltage to the power supply management unit and the field effect tube unit; the field effect tube unit is used to output a fourth voltage to the filter compensation unit, and feedback current to the power supply management unit; the filter compensation unit is used to process the fourth voltage as an LED driving voltage, output the driving voltage to the LED driving unit, and output the driving voltage as a feedback voltage to the power supply management unit. The multi-stage voltage regulation after rectification ensures the stability of the voltage output to the power supply management unit and the field effect tube unit. The π-type filter effectively suppresses the ripple noise in the circuit, making the output waveform more stable and avoiding the flickering phenomenon when the ripple noise in the current passes through the LED. The power supply management unit drives the field effect tube unit to output power, and the filter compensation unit compensates it to continuously output a large and stable current, thereby ensuring the stable operation of the LED. The power supply current and voltage are monitored through voltage feedback and current feedback to ensure the stable operation of the power supply circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solution of the present application, the drawings required for use in the description of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0037] Figure 1 This is a structural block diagram of an LED power supply circuit provided by an embodiment of the present application;

[0038] Figure 2 This is a schematic diagram of a circuit structure in an LED power supply circuit provided in an embodiment of the present application;

[0039] Figure 3This is a schematic diagram of a circuit structure in an LED power supply circuit provided in an embodiment of the present application;

[0040] Figure 4 This is a schematic diagram of the circuit structure of a first voltage stabilizing unit in an LED power supply circuit provided in an embodiment of the present application;

[0041] Figure 5 This is a schematic diagram of the circuit structure of a second voltage stabilizing unit in an LED power supply circuit provided in an embodiment of the present application;

[0042] Figure 6 It is a circuit structure diagram of a power supply management unit, an effect tube unit and a filter compensation unit in an LED power supply circuit provided in one embodiment of the present application. DETAILED DESCRIPTION

[0043] In order to make the objects, features and advantages of the present application more obvious and understandable, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0044] It should be noted that in any embodiment of the present invention, the three electrodes of the above-mentioned transistor are respectively the base (b pole), the collector (c pole) and the emitter (e pole); the three electrodes of the above-mentioned field effect transistor are the gate (G pole), the source (S pole) and the drain (D pole).

[0045] Reference Figure 1, shows a structural block diagram of an LED power supply circuit provided by an embodiment of the present application, comprising: a rectifier conversion circuit 101, a first voltage stabilizing unit 102, a π-type filter 103, a second voltage stabilizing unit 104, a power supply management unit 105, a field effect tube unit 106, a filter compensation unit 107 and an LED driving unit 108 electrically connected in sequence; the rectifier conversion circuit 101 is used to connect to the mains, convert the mains into direct current, and output a first voltage to the first voltage stabilizing unit 102; the first voltage stabilizing unit 102 is used to stabilize the first voltage and output a second voltage to the π-type filter 103; the The π-type filter 103 filters the second voltage and outputs a third voltage to the second voltage stabilizing unit 104; the second voltage stabilizing unit 104 outputs the stabilized third voltage to the power supply management unit 105 and the field effect tube unit 106; the field effect tube unit 106 is used to output a fourth voltage to the filtering and compensating unit 107, and to feed back current to the power supply management unit 105; the filtering and compensating unit 107 is used to process the fourth voltage as an LED driving voltage, and output the driving voltage to the LED driving unit 108, and output the driving voltage as a feedback voltage to the power supply management unit 105.

[0046] In the above embodiment, the stability of the voltage output to the power supply management unit 105 and the field effect tube unit 106 is ensured by multi-stage voltage stabilization after rectification, and the ripple noise in the circuit is effectively suppressed by the π-type filter 103, so that the output waveform is more stable, and the flickering phenomenon caused by the ripple noise in the current passing through the LED is avoided; the field effect tube unit 106 is driven by the power supply management unit 105 to output power, and is compensated by the filtering compensation unit 107 so that its output continuously outputs a large and stable current, thereby ensuring that the LED can work stably, and the power supply current and voltage are monitored by voltage feedback and current feedback to ensure that the power supply circuit can work stably.

[0047] Next, an LED power supply circuit in this exemplary embodiment will be further described.

[0048] In one embodiment of the present application, Figure 1As shown, an LED power supply circuit is disclosed, comprising: a rectifier conversion circuit 101, a first voltage stabilizing unit 102, a π-type filter 103, a second voltage stabilizing unit 104, a power supply management unit 105, a field effect tube unit 106, a filter compensation unit 107 and an LED driving unit 108 which are electrically connected in sequence; the rectifier conversion circuit 101 is used to connect to the mains, convert the mains into direct current, and output a first voltage to the first voltage stabilizing unit 102; the first voltage stabilizing unit 102 is used to stabilize the first voltage and output a second voltage to the π-type filter 103; the π-type filter 104 is used to connect to the mains, convert the mains into direct current, and output a first voltage to the first voltage stabilizing unit 102; the first voltage stabilizing unit 102 is used to stabilize the first voltage and output a second voltage to the π-type filter 103; the π-type filter 105 ... 03 filters the second voltage and outputs a third voltage to the second voltage stabilizing unit 104; the second voltage stabilizing unit 104 outputs the stabilized third voltage to the power supply management unit 105 and the field effect tube unit 106; the field effect tube unit 106 is used to output a fourth voltage to the filtering and compensating unit 107, and to feed back current to the power supply management unit 105; the filtering and compensating unit 107 is used to process the fourth voltage as an LED driving voltage, and output the driving voltage to the LED driving unit 108, and output the driving voltage as a feedback voltage to the power supply management unit 105. It also includes that the interface of the LED driving unit 108 is electrically connected to the power supply management unit 105, and is used to detect whether the interface is connected to an LED lamp.

[0049] In the above embodiment, by setting the feedback connection of the interface, when the LED light is not connected to the interface or the interface is abnormal, the power supply management unit 105 controls the field effect tube unit 106 not to output power. On the one hand, the safety of the interface is guaranteed, for example, no power is output when the interface is short-circuited. On the other hand, a certain energy-saving effect can be achieved. For example, when the interface is unloaded and no power is supplied, the power supply management unit 105 controls its subsequent circuit to not work.

[0050] As an example, when the LED is unloaded or short-circuited, its interface resistance value and the LED diode value are different from when the LED is connected. The corresponding power supply management unit 105 detects that the interface voltage value or resistance value is abnormal, and shuts off the subsequent output to protect the circuit.

[0051] In one embodiment of the present application, Figure 2 As shown, the above-mentioned rectification conversion circuit 101 includes: a transformer T1, whose primary winding is connected to the AC power, and whose secondary winding is connected to the rectifier bridge VD1, which is used to transform the AC power and output the transformed voltage to the above-mentioned rectifier bridge VD1 for rectification; the above-mentioned rectifier bridge VD1 is electrically connected to the input end of the above-mentioned first voltage stabilizing unit 102, and is used to output direct current to the above-mentioned first voltage stabilizing unit 102.

[0052] In the above embodiment, the mains power is stepped down by the transformer T1 and then rectified to convert it into direct current to power subsequent circuits.

[0053] As an example, the above-mentioned rectifier bridge VD1 can be a half bridge composed of two diodes, or a full bridge composed of four diodes, or an integrated integrated rectifier bridge stack.

[0054] It should be noted that LED is also called light-emitting diode. Although it has the characteristics of a diode (unidirectional conduction) and can work and emit light when directly connected to an AC power supply, its reverse breakdown voltage is relatively low. When the reverse voltage is higher and exceeds its breakdown voltage, it is easy to be broken down and damaged. Similarly, if there is strong ripple interference, the LED is also at risk of being broken down and damaged. Therefore, the LED power supply circuit provided above can effectively protect the LED from reverse breakdown and damage.

[0055] In one embodiment of the present application, Figure 2 As shown, the above-mentioned rectifier conversion circuit 101 further includes: a fuse F1, which is connected in series between the primary winding of the above-mentioned transformer T1 and the mains; the two ends of the above-mentioned primary winding are also electrically connected to a varistor RV and a filter capacitor C10.

[0056] In the above embodiment, since the power supply of the mains power grid in many places is unstable or out of phase (220V lighting voltage becomes 380V power voltage), it is easy to cause an overvoltage burning accident of the electrical appliances. For this reason, the above-mentioned varistor RV is used to provide an overvoltage protection function. When the input voltage of the power grid is normal, the resistance of the varistor RV is very large and is in a disconnected state, which has no effect on the protector. Once the mains power grid is overvoltage (for example, exceeding 260V) or out of phase (380V) for some reason, the resistance of RV decreases sharply, forming a large current loop, reducing the current loop of the subsequent stage, so that the subsequent circuit is protected.

[0057] In one embodiment of the present application, Figure 2 and Figure 4 As shown, the first voltage stabilizing unit 102 includes: at least one three-terminal voltage regulator; the input end of the three-terminal voltage regulator is electrically connected to the output end of the rectification conversion circuit 101, and the output end of the three-terminal voltage regulator is electrically connected to the π-type filter 103.

[0058] In the above embodiment, a three-terminal voltage stabilizer is used for voltage stabilization output, thereby solving the problem that the unstable mains power makes the rectified voltage unstable as well, so that the rectified voltage can be output stably to the subsequent stage.

[0059] As an example, since the LED power supply is generally between 3-12V, the above-mentioned three-terminal regulator can select one or more of the 7812, 7824 and 7805 types. In order to increase the output power, the same type of three-terminal regulators can be used in parallel. Since the above-mentioned three-terminal regulator is a voltage-stabilizing element, its output voltage is fixed. According to the formula W=U*I, the voltage is fixed and the power is proportional to the current. Therefore, the output current can be doubled by parallel connection.

[0060] In a specific embodiment, if Figure 4 As shown, the first voltage stabilizing unit 102 can also expand the current by adding transistors, specifically including: at least two transistors Q20 and Q21 and corresponding two pull-up resistors R21 and R22 and a current limiting resistor R20; one end of the current limiting resistor R20 serves as the input end of the first voltage stabilizing unit 102 and is connected to one end of the pull-up resistor R21 and one end of the pull-up resistor R22, and the other end of the current limiting resistor R20 is connected to the input end of the three-terminal regulator and the b-pole of the transistors Q20 and Q21; the other end of the pull-up resistor R21 and the other end of the pull-up resistor R22 are respectively connected to the e-pole of the transistors Q20 and Q21; the c-pole of the transistors Q20 and Q21 is connected to the output end of the three-terminal regulator as the output end of the first voltage stabilizing unit 102; the two ends of the current limiting resistor R20 are respectively connected to a filter capacitor C20 and C21, and the output end of the three-terminal regulator is also connected to the filter capacitor C22. For example, the above transistor can preferably be a power transistor TIP2599, whose single current output is adjusted to maintain 5A. After two of them are connected in parallel, the output current can reach 10A; Figure 4 As shown, the output current can be increased to 20A by four transistors Q20 to Q23, specifically by setting resistors R21 to R24 to 0.1Ω, R20 to 100Ω, capacitors C20 and C21 to 470μF, and capacitor C22 to 10μF. Similarly, using 6 transistors can expand the output to 30A, thereby achieving high-power regulated output.

[0061] In one embodiment of the present application, Figure 2 As shown, the π-type filter 103 is an LC filter, specifically comprising: a first inductor L1 and electrolytic capacitors C1 and C2 connected at both ends of the first inductor L1. A filter capacitor C3 is also provided between the first inductor L1 and the electrolytic capacitor C2 of the π-type filter 103. The input and output of the π-type filter 103 are both low impedance, so its insertion loss characteristics are better than those of the RC type and LC type.

[0062] As an example, the π-type filter 103 can also use a magnetic bead L1 to replace the first inductor L1. Preferably, the inductance of the first inductor L1 or the magnetic bead L1 is 5μH; the electrolytic capacitors C1 and C3 have a capacity of 100μF; the capacity of the second capacitor C2 is 22μF; the magnetic bead L1 has the ability to suppress high-frequency noise and spike interference on the signal line and the power line, and also has the ability to absorb static pulses. Magnetic beads Magnetic beads L1 are used to absorb ultra-high frequency signals. Some RF circuits, PLL, oscillation circuits, and ultra-high frequency memory circuits (DDR SDRAM, RAMBUS, etc.) all require magnetic beads L1 to be added to the power input part. Inductors are energy storage elements, generally used in LC oscillation circuits, medium and low frequency filter circuits, etc., and their application frequency range rarely exceeds 50MHZ; magnetic beads have high resistivity and permeability, which is equivalent to resistors and inductors in series, but the resistance and inductance values ​​vary with frequency.

[0063] In the above embodiment, a relatively large electrolytic capacitor C1 is provided at the input end of the π-type filter 103 to firstly perform low-frequency filtering, and then perform high-frequency filtering through the first inductor L1 or the magnetic bead L1, and then perform low-frequency filtering through the third capacitor C3 at the output end, and then perform high-frequency filtering again through the electrolytic capacitor C2 of 22μF, thereby removing interference noise and ripple interference in the output current; achieving the effect of effectively suppressing the ripple noise of the linear power supply and improving the power supply quality.

[0064] It should be noted that, in order to improve the filtering quality, a plurality of the above-mentioned π-type filters 103 (not shown in the figure) may also be used, for example, Figure 2 An inductive PI filter 103 is used in the position of the PI filter 103 shown (according to the physical properties of the circuit, generally no high frequency is generated between the rectification and the power supply management unit 105); a magnetic bead-type π filter 103 is added between the filter compensation unit and the LED drive unit 108 to achieve multi-stage ripple filtering.

[0065] The above-mentioned π-type filter 103 has a simple structure and is only composed of electrolytic capacitors or filter capacitors and inductors, which greatly reduces the circuit connection difficulty and interference between components in the prior art; the electrolytic capacitors and inductors in the π-type filter 103 can filter out ripples multiple times and have strong robustness.

[0066] In one embodiment of the present application, Figure 3As shown, the second voltage stabilizing unit 104 is a TL431 voltage regulating circuit, specifically comprising: one end of the current limiting resistor R1 is the input end of the second voltage stabilizing unit 104; the other end of the current limiting resistor R1 is the output end of the second voltage stabilizing unit 104, and is connected to the e-pole of the transistor Q5, one end of the current limiting resistor R4 and one end of the voltage dividing resistor R2; the b-pole of the transistor Q5 is connected to the other end of the current limiting resistor R4 and the cathode of TL431; the other end of the voltage dividing resistor R2 is connected to one end of the voltage dividing resistor R3 and the reference end of TL431; the c-pole of the transistor Q5, the anode of the TL431 and the other end of the voltage dividing resistor R3 are grounded. Through the amplification function of the transistor Q5, the TL431 obtains a larger working current, thereby increasing the output current of its output end.

[0067] In the above embodiment, the TL431 voltage regulating circuit is composed of the main components of TL431. Through the controllable precision voltage stabilizing element TL431, it uses a voltage divider resistor to set the reference terminal voltage Vref, and its reference terminal voltage Vref (2.5V) is any value in the range of 36V. The typical dynamic impedance of the device is 0.2Ω. Due to its good precision and simple circuit composition, it improves the voltage stabilization accuracy compared to the voltage stabilizing diode, and the voltage stabilization value can be set according to the reference terminal voltage. Specific working principle: When the input voltage increases, the output voltage increases, resulting in an increase in output sampling. At this time, the internal circuit increases the current flowing through itself through adjustment, so that the current flowing through the current limiting resistor increases, so that the voltage drop of the current limiting resistor increases, and the output voltage is equal to the input voltage minus the voltage drop of the current limiting resistor. The increase in input voltage and the increase in the voltage drop of the current limiting resistor reduce the output voltage, thereby achieving voltage stabilization.

[0068] In one embodiment of the present application, Figure 5 As shown, the second voltage stabilizing unit 104 may further include: a current control unit; the current control unit includes a transistor Q6, a transistor Q7 and a resistor R5, wherein the c-pole of the transistor Q6 and the c-pole of the transistor Q7 are connected to one end of the current limiting resistor R1, the e-pole of the transistor Q6 is connected to the b-pole of the transistor Q7 and one end of the resistor R5, and the e-pole of the transistor Q7 and the other end of the resistor R5 are connected to one end of the voltage dividing resistor R2; when the second voltage stabilizing unit 104 includes the current control unit, one end of the current limiting resistor R4 in the TL431 voltage regulating circuit, the e-pole of the transistor Q5 and the other end of the current limiting resistor R1 are connected to the b-pole of the transistor Q6.

[0069] In the above embodiment, referring to Figure 5, by preferably using high-current NPN-type metal-shell silicon transistors Q6 and Q7, the output circuit of the second voltage stabilizing unit 104 can be increased to 10A (when the previous circuit can provide a current of more than 10A), wherein the current limiting resistor R2 can preferably use an adjustable resistor, and by adjusting the resistance value of the resistor, different currents can be output, so that the user can conveniently adjust the voltage as needed during use, and the adjustment range is any value within the range of 2.5V to 36V. And electrolytic capacitors can be set at the input and output ends of the second voltage stabilizing unit 104 for filtering, so that its output is more stable (not shown in the figure). Its adjustment principle is to adjust the cathode voltage of the above-mentioned TL41 through the voltage-dividing resistors R2 and R3, thereby adjusting the b-pole voltage of the transistor Q6, so that it forms the Ibe current corresponding to the transistor Q6, thereby further forming the driving voltage at the b-pole of the transistor Q7, and adjusting the Ibe current corresponding to the transistor Q7, thereby adjusting the on-off of the transistor Q7. In addition, the output current can be expanded and the output power can be increased by arranging a plurality of transistors corresponding to the transistor Q7 in parallel.

[0070] In one embodiment of the present application, Figure 3 As shown, the power supply management unit 105 is mainly composed of a power management chip, which is connected to the G pole of the field effect tube in the field effect tube unit 106 through the driving pin (Gate (H) and Gate (L)), and outputs a control pulse to control the conduction between the D pole and the S pole of the field effect tube, thereby adjusting the output voltage, wherein Gate (H) is used to control the upper tube, and Gate (L) is used to control the lower tube. A group of field effect tubes is formed by at least one upper tube and at least one lower tube, the S pole of the lower tube is grounded, the D pole of the upper tube is connected to the output end of the second voltage stabilizing unit 104, the S pole of the upper tube is connected to the D pole of the lower tube, and is connected to the inductor of the filtering and compensation unit 107. The filtering and compensation capacitor composed of the inductor and multiple capacitors filters the power output to the LED driving unit 108. The position where the upper tube and the lower tube are connected to the inductor is also connected to the current feedback pin of the power management chip, so as to monitor the current of the power supply in real time. By connecting the output end of the filtering and compensation unit 107 to the voltage feedback pin of the power management chip, the monitoring of the power supply voltage is realized. By monitoring the power supply current and voltage, when the voltage or current is abnormal, the power supply output is stopped, thereby protecting the subsequent circuits and ensuring the safety of power use of the equipment.

[0071] In a specific example, the power management unit 105 is preferably an ISL6262 chip or a GD3000 chip; the corresponding field effect tube unit 106 includes two groups of field effect tubes, such as Figure 3As shown, the output ends of the field effect tubes Q1 and Q2 are connected to the inductors L2 and L3 respectively with the output ends of the field effect tubes Q3 and Q4. The inductors L2 and L3 are combined with the capacitors C5 and C6 for energy storage and filtering. While ensuring the output power, the output current can be made more stable and the subsequent LED lamps will not flicker.

[0072] In one embodiment of the present application, Figure 6 As shown, the power supply management unit 105 can also be composed of two-level control chips. For example, the first-level chip is preferably RT9246, and the second-level chip is preferably / RT9603. The PWM signal is output to the diode chip through the PWM pin of the first-level chip. The diode chip is used to drive the conduction output voltage of the field effect tube, wherein the current feedback and voltage feedback are connected to the first-level chip to further improve the precise control of the output.

[0073] In an embodiment of the present application, an LED lighting system is further disclosed, including an LED lamp and the above-mentioned LED power supply circuit, wherein the above-mentioned LED lamp is connected to an LED driving unit 108 .

[0074] It should be noted that, since many current LED lamp designs are composed of multiple light-emitting diodes connected in series, they can adapt to higher voltage outputs. However, if one of the light-emitting diodes in the series lamp group fails, all the diodes in the series will not work properly. The above circuit of the present application can realize adjustable voltage, as well as low voltage, high current and high power supply. Therefore, it is also suitable for non-series LED lamp power supply, avoiding the failure of a single light-emitting diode affecting the lighting of the entire lamp. The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referred to each other.

[0075] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present application.

[0076] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or terminal device including the elements.

[0077] The above is a detailed introduction to an LED power supply circuit provided by the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for general technicians in this field, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. An LED power supply circuit, characterized in that: include: A rectifying and converting circuit, a first voltage stabilizing unit, a π-type filter, a second voltage stabilizing unit, a power supply management unit, a field effect tube unit, a filtering and compensation unit, and an LED driving unit electrically connected in sequence; The rectifying and converting circuit is used to connect to the mains, convert the mains into direct current, and output a first voltage to the first voltage stabilizing unit; The first voltage stabilizing unit is used for stabilizing the first voltage and outputting a second voltage to the π-type filter; The π-type filter filters the second voltage and outputs a third voltage to the second voltage stabilizing unit; The second voltage stabilizing unit outputs the stabilized third voltage to the power supply management unit and the field effect tube unit; The field effect tube unit is used to output a fourth voltage to the filtering and compensation unit, and to feed back current to the power supply management unit; The filtering and compensating unit is used to process the fourth voltage into an LED driving voltage, output the driving voltage to the LED driving unit, and output the driving voltage as a feedback voltage to the power supply management unit; The first voltage stabilizing unit comprises: at least one three-terminal voltage stabilizer; the input end of the three-terminal voltage stabilizer is electrically connected to the output end of the rectifier conversion circuit, and the output end of the three-terminal voltage stabilizer is electrically connected to the π-type filter; The first voltage stabilizing unit further includes: at least two transistors Q20 and Q21 and two corresponding pull-up resistors R21 and R22 and a current limiting resistor R20; one end of the current limiting resistor R20 serves as the input end of the first voltage stabilizing unit and is connected to one end of the pull-up resistor R21 and one end of the pull-up resistor R22, and the other end of the current limiting resistor R20 is connected to the input end of the three-terminal voltage regulator and the b-pole of the transistors Q20 and Q21; the other end of the pull-up resistor R21 and the other end of the pull-up resistor R22 are connected to the e-pole of the transistors Q20 and Q21, respectively; the c-pole of the transistors Q20 and Q21 is connected to the output end of the three-terminal voltage regulator as the output end of the first voltage stabilizing unit; the two ends of the current limiting resistor R20 are respectively connected to a filter capacitor C20 and C21, and the output end of the three-terminal voltage regulator is also connected to a filter capacitor C22; The π-type filter is an LC filter, specifically comprising: a first inductor L1 and electrolytic capacitors C1 and C2 connected at both ends of the first inductor L1; a filter capacitor C3 is further provided between the first inductor L1 and the electrolytic capacitor C2; The second voltage stabilizing unit is a TL431 voltage regulating circuit, specifically comprising: one end of the current limiting resistor R1 is the input end of the second voltage stabilizing unit; the other end of the current limiting resistor R1 is the output end of the second voltage stabilizing unit, and is connected to the e-pole of the transistor Q5, one end of the current limiting resistor R4 and one end of the voltage dividing resistor R2; the b-pole of the transistor Q5 is connected to the other end of the current limiting resistor R4 and the cathode of TL431; the other end of the voltage dividing resistor R2 is connected to one end of the voltage dividing resistor R3 and the reference end of the TL431; the c-pole of the transistor Q5, the anode of the TL431 and the other end of the voltage dividing resistor R3 are grounded; The second voltage stabilizing unit also includes: a current control unit; the current control unit includes a transistor Q6, a transistor Q7 and a resistor R5, wherein the c-pole of the transistor Q6 and the c-pole of the transistor Q7 are connected to one end of the current limiting resistor R1, the e-pole of the transistor Q6 is connected to the b-pole of the transistor Q7 and one end of the resistor R5, and the e-pole of the transistor Q7 and the other end of the resistor R5 are connected to one end of the voltage dividing resistor R2; when the second voltage stabilizing unit includes the current control unit, one end of the current limiting resistor R4 in the TL431 voltage regulating circuit, the e-pole of the transistor Q5 and the other end of the current limiting resistor R1 are connected to the b-pole of the transistor Q6.

2. The LED power supply circuit according to claim 1, characterized in that: Also includes: The interface of the LED driving unit is electrically connected to the power supply management unit, and is used to detect whether the interface is connected to an LED lamp.

3. The LED power supply circuit according to claim 1, characterized in that: The rectifier conversion circuit comprises: Transformer T1, whose primary winding is connected to the mains, and whose secondary winding is connected to a rectifier bridge VD1, is used to transform the mains and output the transformed voltage to the rectifier bridge VD1 for rectification; The rectifier bridge VD1 is electrically connected to the input end of the first voltage stabilizing unit, and is used to output direct current to the first voltage stabilizing unit.

4. The LED power supply circuit according to claim 3, characterized in that: The rectification and conversion circuit further includes: The fuse F1 is connected in series between the primary winding of the transformer T1 and the mains; the two ends of the primary winding are also electrically connected to a varistor RV and a filter capacitor C10.

5. An LED lighting system, characterized in that: The invention comprises an LED lamp and an LED power supply circuit as claimed in any one of claims 1 to 4, wherein the LED lamp is connected to an LED driving unit.

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