LED lighting circuit, LED lighting system and clothes airing machine

Abstract

The utility model provides an LED lighting circuit, an LED lighting system and a clothes airing machine, and relates to the technical field of circuit design. The LED lighting circuit comprises a filter circuit, a control circuit and a power loop which are connected in sequence, wherein the filter circuit receives a PWM (Pulse Width Modulation) signal; the filter circuit filters the PWM signal to obtain a direct current level signal, and outputs the direct current level signal to the control circuit; the control circuit processes the DC level signal to obtain a ripple current, and outputs the ripple current to the power loop; and the power loop outputs the ripple current to an LED lighting unit to supply power to the LED lighting unit. According to the utility model, the filter circuit is used for filtering clutter interference in PWM signals, and the first chip is used for dimming the direct current level, so that the problem of lamp flashing when the brightness of the LED lighting unit is relatively low is effectively solved.

Description

Technical Field

[0001] The utility model relates to the technical field of circuit design. Specifically, the utility model relates to an LED lighting circuit, a system and a clothes dryer. Background Art

[0002] At present, people's material living standards have gradually improved, and many people use intelligent electric clothes dryers to dry clothes at home. Among the common clothes dryers on the market, in addition to using a motor to control the automatic lifting of the clothes dryer, an LED lighting unit is usually added to illuminate the balcony.

[0003] In the related art, the external power supply of the clothes dryer is converted into a constant voltage of 24V through a transformer. The constant voltage of 24V outputs a ripple current to the LED lighting unit through the LED lighting circuit. At the same time, the constant voltage of 24V outputs to the micro-control unit through a constant voltage of 5V for controlling the lifting of the motor and adjusting the brightness intensity of the LED lighting unit.

[0004] However, the constant voltage of 24V has poor dynamic response and a large ripple current, resulting in a lamp flashing problem when the brightness intensity of the LED lighting unit is adjusted to the minimum. Summary of the Utility Model

[0005] Aiming at the shortcomings of the existing method, the utility model provides an LED lighting circuit, a system and a clothes dryer to solve the technical problem of lamp flashing existing in the related art at the minimum brightness of the LED lighting.

[0006] In a first aspect, the utility model provides an LED lighting circuit, including:

[0007] A filter circuit, a control circuit and a power loop connected in sequence;

[0008] Wherein, the filter circuit receives a PWM signal; the filter circuit filters the PWM signal to obtain a DC level signal and outputs the DC level signal to the control circuit;

[0009] The control circuit processes the DC level signal to obtain a ripple current and outputs the ripple current to the power loop;

[0010] The power loop outputs the ripple current to the LED lighting unit to supply power to the LED lighting unit.

[0011] In a possible implementation manner, the filter circuit includes a first resistor, a second resistor and a first capacitor;

[0012] Wherein, the first end of the first resistor is arranged at the input end of the filter circuit and is connected to the micro-control unit, and the micro-control unit is used to output a PWM signal to the filter circuit;

[0013] The second terminal of the first resistor, the first terminal of the second resistor, and the first terminal of the first capacitor are connected and set as the output terminal of the filter circuit to be connected to the control circuit;

[0014] The second terminal of the second resistor and the second terminal of the first capacitor are grounded.

[0015] In a possible implementation, the control circuit includes a first chip; the first chip includes a DIM pin and a DR pin;

[0016] Among them, the DIM pin is connected to the output terminal of the filter circuit for receiving the DC level signal output by the filter circuit;

[0017] The DR pin is connected to the power loop for outputting the ripple current to the power loop.

[0018] In a possible implementation, the power loop includes a switching module;

[0019] The switching module includes: a first MOS transistor, a third resistor, and a fourth resistor;

[0020] Among them, the first terminal of the third resistor is connected to the DR pin of the first chip; the second terminal of the third resistor, the drain of the first MOS transistor, and the first terminal of the fourth resistor are connected; the source of the first MOS transistor and the second terminal of the fourth resistor are grounded.

[0021] In a possible implementation, the power loop further includes: a current detection module, a first polarized capacitor, an EMC common mode inductor, a power inductor, and a first diode;

[0022] Among them, the current detection module includes a fifth resistor, a sixth resistor, and a seventh resistor connected in parallel; the first terminal of the fifth resistor, the first terminal of the sixth resistor, and the first terminal of the seventh resistor are connected and set as the first terminal of the current detection module; the second terminal of the fifth resistor, the second terminal of the sixth resistor, and the second terminal of the seventh resistor are connected and set as the second terminal of the current detection module;

[0023] The positive electrode of the first polarized capacitor is connected to the first terminal of the current detection module, and the negative electrode of the first polarized capacitor is grounded; the second terminal of the current detection module is connected to the first terminal of the EMC common mode inductor, the second terminal of the EMC common mode inductor is connected to the positive electrode of the LED lighting unit for supplying power to the LED lighting unit; the third terminal of the EMC common mode inductor is connected to the negative electrode of the LED lighting unit; the fourth terminal of the EMC common mode inductor is connected to the negative electrode of the power inductor, and the positive electrode of the power inductor is connected to the drain of the first MOS transistor;

[0024] The positive electrode of the first diode is connected to the positive electrode of the power inductor, and the negative electrode of the first diode is connected to the first terminal of the current detection module.

[0025] In a possible implementation, when the output voltage of the DR pin is greater than or equal to the first voltage, the first MOS transistor is turned on;

[0026] The ripple current flows from the positive electrode of the first polar capacitor through the first end of the current detection module, the second end of the current detection module, the first end and the second end of the EMC common mode inductor, the positive and negative electrodes of the LED lighting unit, the third end and the fourth end of the EMC common mode inductor, the negative electrode of the power inductor, the positive electrode of the power inductor, the drain of the first MOS transistor, and the source of the first MOS transistor back to ground;

[0027] When the output voltage of the DR pin is less than the first voltage, the first MOS transistor is turned off;

[0028] The power inductor releases the ripple current; the ripple current flows through the positive electrode of the power inductor, the positive electrode of the first diode, the negative electrode of the first diode, the first end of the current detection module, the second end of the current detection module, and the positive and negative electrodes of the LED lighting unit in sequence, and then returns to the negative electrode of the power inductor.

[0029] In a possible implementation, the power loop further includes: a second polar capacitor and an eighth resistor;

[0030] Wherein, the positive electrode of the second polar capacitor and the first end of the eighth resistor are connected to the second end of the current detection module, and the negative electrode of the second polar capacitor and the second end of the eighth resistor are connected to the negative electrode of the power inductor;

[0031] The second polar capacitor is used to filter the ripple current flowing through the LED lighting unit, and the eighth resistor is used to discharge the second polar capacitor.

[0032] In a possible implementation, the control circuit further includes a second capacitor and a third capacitor, and the first chip further includes an IN pin, an RS pin, a VCC pin, and a GND pin;

[0033] Wherein, the IN pin, the first end of the second capacitor, and the first end of the current detection module are connected; the RS pin is connected to the second end of the current detection module; the current flowing through the power loop is obtained through the IN pin and the RS pin;

[0034] The VCC pin is connected to the first end of the third capacitor; the second end of the second capacitor, the second end of the third capacitor, and the GND pin are respectively grounded.

[0035] In a second aspect, the present invention provides an LED lighting system, including: an LED lighting unit and the LED lighting circuit as in the first aspect;

[0036] The LED lighting unit is connected to the power loop of the LED lighting circuit.

[0037] In a third aspect, the present utility model provides a clothes dryer, comprising: the LED lighting system of the second aspect.

[0038] The beneficial technical effects brought by the technical solution provided by the present utility model include:

[0039] The LED lighting circuit of the present utility model includes a filtering circuit, a control circuit and a power loop. The filtering circuit receives a PWM signal and filters the PWM signal to obtain a DC level signal, and outputs the DC level signal to the control circuit. Since the filtering circuit can filter out the clutter interference in the PWM signal, and the first chip in the control circuit can also perform DC level dimming, the problem that when the motor starts, the dynamic response of the 24V constant voltage unit is poor and the ripple current is large, resulting in the LED lighting unit flashing, is solved.

[0040] The additional aspects and advantages of the present utility model will be partially given in the following description, and these will become obvious from the following description, or be understood through the practice of the present utility model. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The above-mentioned and / or additional aspects and advantages of the present utility model will become obvious and easy to understand from the following description of the embodiments in conjunction with the drawings, wherein:

[0042] Figure 1 is a schematic structural diagram of a clothes dryer in the related art provided by the present utility model;

[0043] Figure 2 is a schematic framework diagram of an LED lighting circuit provided by the present utility model;

[0044] Figure 3 is a schematic structural diagram of an LED lighting circuit provided by the present utility model; BRIEF DESCRIPTION OF THE DRAWINGS:

[0046] 10 - LED lighting circuit;

[0047] 20 - micro control unit;

[0048] 30 - 24V constant voltage unit;

[0049] 40 - LED lighting unit;

[0050] 110 - filtering circuit;

[0051] 120 - control circuit;

[0052] 130 - power loop;

[0053] U2 - first chip;

[0054] R39 - First resistor, R40 - Second resistor, C23 - First capacitor;

[0055] C19 - Second capacitor, C24 - Third capacitor;

[0056] Q4 - First MOS transistor, R41 - Third resistor, R42 - Fourth resistor;

[0057] R44 - Fifth resistor, R45 - Sixth resistor, R36 - Seventh resistor;

[0058] CE9 - First polarized capacitor, LF3 - EMC common - mode inductor, L5 - Power inductor, D7 - First diode;

[0059] CE12 - Second polarized capacitor, R46 - Eighth resistor, CN4 - LED lighting unit. Detailed implementation mode

[0060] The embodiments of the present invention will be described below with reference to the accompanying drawings in the present invention. It should be understood that the implementation modes described below with reference to the accompanying drawings are exemplary descriptions for explaining the technical solutions of the present invention and do not constitute limitations on the technical solutions of the present invention.

[0061] Those skilled in the art of the present technology can understand that unless specifically stated, the "a" and "the" used here can also include the plural form. It should be further understood that the term "comprising" used in the specification of the present invention means the presence of features, integers, steps, operations, elements, and / or components, but does not exclude the presence of other features, information, data, steps, operations, elements, components, and / or combinations thereof supported by the art of the present technology. It should be understood that when we say an element is "connected" or "coupled" to another element, this element can be directly connected or coupled to the other element, or it can mean that this element and the other element establish a connection relationship through an intermediate element. In addition, the "connection" or "coupling" used here can include wireless connection or wireless coupling. The term "and / or" used here means at least one of the items defined by this term. For example, "A and / or B" can be implemented as "A", or implemented as "B", or implemented as "A and B".

[0062] To make the purpose, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0063] It has been found through research that the traditional LED lighting circuit has obvious defects. The dynamic response of the constant - voltage 24V unit is poor. At the moment when the motor starts, the 24V output voltage will drop significantly, resulting in a large change in the ripple current output by the lighting circuit. When the brightness of the LED lighting circuit is low, there will be a problem of stroboscopic.

[0064] The LED lighting circuit, system and clothes dryer provided by the present utility model aim to solve the above technical problems in the related art.

[0065] The technical solutions of the present utility model and how the technical solutions of the present utility model solve the above technical problems will be described in detail below with specific embodiments. It should be noted that the following embodiments can be referred to, learned from or combined with each other. For the same terms, similar features and similar implementation steps in different embodiments, they will not be described repeatedly.

[0066] Figure 1 It is a schematic structural diagram of a clothes dryer in the related art provided by the present utility model. As shown in the figure, the structure of the clothes dryer consists of AC input and EMI filtering, single-stage PFC control circuit, transformer, constant voltage 24V unit, motor drive circuit, motor, BUCK constant voltage 5V output, MCU, BUCK constant current circuit, and LED lighting. The specific implementation principle is as follows: The clothes dryer is externally connected to an AC power supply AC. After the AC input is rectified through EMI filtering, it is converted into a constant voltage 24V unit by a single-stage PFC control circuit and a transformer to meet the requirements of harmonic current; the constant voltage 24V passes through the BUCK constant voltage 5V output, and the ripple voltage is very small to meet the requirements of the micro-control unit, enabling the micro-control unit to control the lifting of the motor and the on / off and dimming of the LED lighting. However, the dynamic response of the constant voltage 24V unit is poor, and the ripple current is large, resulting in a lamp flashing problem when the brightness of the LED lighting unit is the smallest.

[0067] The LED lighting circuit, system and clothes dryer provided by the present utility model aim to solve the above technical problems in the prior art.

[0068] Figure 2 It is a schematic framework diagram of an LED lighting circuit provided by the present utility model. The LED lighting circuit includes: an LED lighting circuit 10, a micro-control unit 20, a constant voltage 24V unit 30, and an LED lighting unit 40.

[0069] The micro-control unit 20 is connected to the filtering circuit 110 of the LED lighting circuit 10.

[0070] The constant voltage 24V unit 30 is connected to the control circuit 120 and the power loop 130 of the LED lighting circuit 10 for supplying power to the control circuit 120 and the power loop 130.

[0071] The LED lighting circuit 10 includes: a filtering circuit 110, a control circuit 120, and a power loop 130; the filtering circuit 110, the control circuit 120, and the power loop 130 are connected in sequence; the power loop 130 is also connected to the LED lighting unit 40 for supplying power to the LED lighting unit 40.

[0072] See Figure 2As shown in the figure, the filter circuit 110 receives the Pulse Width Modulation (PWM) signal output by the microcontroller unit 20; the filter circuit 110 filters the PWM signal to obtain a DC level signal, and outputs the DC level signal to the control circuit 120; the control circuit 120 processes the DC level signal to obtain a ripple current, and outputs the ripple current to the power loop 130; the power loop 130 outputs the ripple current to the LED lighting unit to supply power to the LED lighting unit.

[0073] It should be noted that the existing BUCK constant current circuit of the clothes dryer is used to supply power to the LED lighting unit. Therefore, the present invention improves the BUCK constant current circuit, that is: the LED lighting circuit provided by the present invention adds a filter circuit on the basis of the BUCK constant current circuit, which is used to filter out the clutter in the input PWM signal and convert the PWM signal into a DC level signal and output it to the control circuit.

[0074] The LED lighting circuit 10 of the present invention includes a filter circuit 110, a control circuit 120 and a power loop 130; wherein, the filter circuit receives the PWM signal and filters the PWM signal to obtain a DC level signal, and outputs the DC level signal to the control circuit; the control circuit processes the DC level signal to obtain a ripple current, and outputs the ripple current to the power loop; the power loop outputs the ripple current to the LED lighting unit to supply power to the LED lighting unit. Since the filter circuit can filter out the irregular high-order harmonics and random interference in the PWM signal, and the control circuit can adjust the light by the DC level, it greatly reduces the problem that when the motor starts, the dynamic response of the constant voltage 24V unit is poor and the ripple current is large, resulting in lamp flashing when the light intensity of the LED lighting unit is the smallest.

[0075] Figure 3 It is a schematic structural diagram of an LED lighting circuit provided by the present invention. As Figure 3 shown, the filter circuit 110 includes a first resistor R39, a second resistor R40 and a first capacitor C23;

[0076] Among them, the first end of the first resistor is arranged at the input end of the filter circuit and is connected to the microcontroller unit, and the microcontroller unit is used to output the PWM signal to the filter circuit;

[0077] The second end of the first resistor, the first end of the second resistor and the first end of the first capacitor are connected, and are set as the output end of the filter circuit and connected to the control circuit;

[0078] The second end of the second resistor and the second end of the first capacitor are grounded.

[0079] Specifically, the first resistor is connected to the microcontroller unit and is used to receive the PWM signal output by the microcontroller unit. The first resistor, the second resistor, and the first capacitor form a filtering circuit to filter the PWM signal output by the microcontroller unit, filtering out clutter interference. At the same time, the PWM signal is converted into a DC level signal and output to the control circuit, so that the control circuit outputs less ripple current after dimming the DC level signal, overcoming the stroboscopic problem of the LED lighting unit when the brightness is small.

[0080] See Figure 3 As shown, in some embodiments, the control circuit includes a first chip; the first chip includes a DIM pin and a DR pin;

[0081] Among them, the DIM pin is connected to the output end of the filtering circuit and is used to receive the DC level signal output by the filtering circuit;

[0082] The DR pin is connected to the power loop and is used to output the ripple current to the power loop.

[0083] Specifically, the first chip selected in the present invention has very good dynamic response and small output ripple current; compared with the prior art, the first chip is compatible with level dimming and PWM dimming at the DIM pin, so that a filtering circuit can be added to the DIM pin, and only with appropriate capacitor and resistor parameters can there be a good dimming effect. It can be understood that the combination of the first chip and the filtering circuit in the present invention solves the problem of lamp flashing.

[0084] The first chip can be a BUCK constant current chip. The BUCK constant current chip selected in the present invention has very good dynamic response and small output ripple current. When the input voltage of the constant voltage 24V changes, the output ripple current changes little, effectively avoiding the stroboscopic problem of the LED lighting unit when the brightness is small.

[0085] See Figure 3 As shown, in some embodiments, the power loop includes a switching module;

[0086] The switching module includes: a first MOS transistor Q4, a third resistor R41, and a fourth resistor R42;

[0087] Among them, the first end of the third resistor is connected to the DR pin of the first chip; the second end of the third resistor, the gate of the first MOS transistor, and the first end of the fourth resistor are connected; the source of the first MOS transistor is grounded with the second end of the fourth resistor.

[0088] Specifically, the first MOS transistor has two states: on and off. When the voltage between the gate and source of the first MOS transistor is greater than the conduction voltage, the first MOS transistor conducts; otherwise, the first MOS transistor is turned off. Therefore, the first MOS transistor can be regarded as a switch, and the first chip can be used to control the first MOS transistor to continuously conduct and turn off, thereby adjusting the duty cycle to obtain the appropriate output voltage and output current of the LED lighting unit.

[0089] See Figure 3 As shown, in some embodiments, the power loop further includes: a current detection module, a first polarized capacitor, an EMC common mode inductor, a power inductor, and a first diode;

[0090] Among them, the current detection module includes a fifth resistor, a sixth resistor, and a seventh resistor connected in parallel; the first ends of the fifth resistor, the sixth resistor, and the seventh resistor are connected and set as the first end of the current detection module; the second ends of the fifth resistor, the sixth resistor, and the seventh resistor are connected and set as the second end of the current detection module;

[0091] The positive electrode of the first polarized capacitor is connected to the first end of the current detection module, and the negative electrode of the first polarized capacitor is grounded; the second end of the current detection module is connected to the first end of the EMC common mode inductor, and the second end of the EMC common mode inductor is connected to the positive electrode of the LED lighting unit for supplying power to the LED lighting unit; the third end of the EMC common mode inductor is connected to the negative electrode of the LED lighting unit; the fourth end of the EMC common mode inductor is connected to the negative electrode of the power inductor, and the positive electrode of the power inductor is connected to the drain of the first MOS transistor;

[0092] The positive electrode of the first diode is connected to the positive electrode of the power inductor, and the negative electrode of the first diode is connected to the first end of the current detection module.

[0093] Specifically, the present invention can indirectly measure the current passing through the current detection module by measuring the voltage across the two ends of the current detection module; due to the parallel connection of resistors, the total resistance value is reduced, making the voltage generated under the same current smaller, which is beneficial to protecting the circuit and improving the measurement accuracy; at the same time, the parallel resistors can also reduce the measurement error caused by the failure of a single resistor and improve the reliability of the system. The second end of the current detection module is connected to the first end of the EMC common mode inductor to provide a stable current supply for the LED lighting unit.

[0094] Further, the positive electrode of the first polar capacitor is connected to the first end of the current detection module, and the negative electrode of the first polar capacitor is grounded; this connection method helps to filter out high-frequency noise and interference in the current and protect the subsequent circuit from electromagnetic interference. In addition, the EMC common-mode inductor further suppresses the common-mode noise to ensure the purity and stability of the current signal. The positive electrode of the first diode is connected to the positive electrode of the power inductor, and the negative electrode is connected to the first end of the current detection module. When the power inductor discharges, the first diode conducts, releasing the energy stored in the inductor back to the power supply or the current detection module to achieve energy recovery and reuse.

[0095] See Figure 3 As shown, in some embodiments, when the output voltage of the DR pin is greater than or equal to the first voltage, the first MOS transistor conducts;

[0096] The ripple current flows from the positive electrode of the first polar capacitor through the first end of the current detection module, the second end of the current detection module, the first and second ends of the EMC common-mode inductor, the positive and negative electrodes of the LED lighting unit, the third and fourth ends of the EMC common-mode inductor, the negative electrode of the power inductor, the positive electrode of the power inductor, the drain of the first MOS transistor, and the source of the first MOS transistor back to ground.

[0097] Specifically, in the present utility model, the first chip controls the output voltage of the DR pin to be greater than or equal to the first voltage. At this time, the voltage between the gate and the source of the first MOS transistor is greater than or equal to its own conduction voltage, and the first MOS transistor conducts. The ripple current output by the first chip flows from the positive electrode of the first polar capacitor through the fifth resistor, the sixth resistor, and the seventh resistor, flows through the positive and negative electrodes of the LED lighting unit to light the lamp, flows through the power inductor and stores energy, and flows through the first MOS transistor back to ground, that is, back to the negative electrode of the first polar capacitor, forming the first power loop.

[0098] See Figure 3 As shown, in some embodiments, when the output voltage of the DR pin is less than the first voltage, the first MOS transistor turns off;

[0099] The power inductor releases the ripple current; the ripple current flows through the positive electrode of the power inductor, the positive electrode of the first diode, the negative electrode of the first diode, the first end of the current detection module, the second end of the current detection module, and the positive and negative electrodes of the LED lighting unit in sequence, and then returns to the negative electrode of the power inductor.

[0100] Specifically, in the present utility model, the first chip controls the output voltage of the DR pin to be less than the first voltage. At this time, the voltage between the gate and the source of the first MOS transistor is less than its own conduction voltage, the first MOS transistor turns off, the power inductor releases energy, and the ripple current flows from the positive electrode of the power inductor through the first diode, through the fifth resistor, the sixth resistor, and the seventh resistor, flows through the positive and negative electrodes of the LED lighting unit, and then returns to the negative electrode of the power inductor, forming the second power loop.

[0101] See Figure 3 As shown, in some embodiments, the power circuit further includes: a second polarized capacitor and an eighth resistor;

[0102] Wherein, the positive electrode of the second polarized capacitor, the first end of the eighth resistor are connected to the second end of the current detection module, and the negative electrode of the second polarized capacitor, the second end of the eighth resistor are connected to the negative electrode of the power inductor;

[0103] The second polarized capacitor is used for filtering the ripple current flowing through the LED lighting unit, and the eighth resistor is used for discharging the second polarized capacitor.

[0104] Specifically, in the present utility model, the second polarized capacitor filters the voltage and current of the LED lighting unit, making the ripple of the voltage and current smaller, and the eighth resistor is used for discharging the second polarized capacitor.

[0105] See Figure 3 As shown, in some embodiments, the control circuit further includes a second capacitor and a third capacitor, and the first chip further includes an IN pin, an RS pin, a VCC pin and a GND pin;

[0106] Wherein, the IN pin, the first end of the second capacitor and the first end of the current detection module are connected; the RS pin is connected to the second end of the current detection module; the current flowing through the power circuit is obtained through the IN pin and the RS pin;

[0107] The VCC pin is connected to the first end of the third capacitor; the second end of the second capacitor, the second end of the third capacitor and the GND pin are respectively grounded.

[0108] Specifically, in the present utility model, the first end of the current detection module is connected to the IN pin of the first chip, and the second end of the current detection module is connected to the RS pin of the first chip. When there is a ripple current passing through the current detection module, the first chip can obtain the ripple current flowing through the current detection module, so as to detect whether the magnitude of the ripple current in the power circuit meets the requirements of the LED lighting unit.

[0109] Based on the same inventive concept, the present utility model provides an LED lighting system, including the LED lighting circuit of the present utility model.

[0110] Based on the same inventive concept, the present utility model provides a clothes dryer, including the LED lighting system of the present utility model.

[0111] Those skilled in the art can understand that the steps, measures, and solutions in the various operations, methods, and processes discussed in the present utility model can be alternated, changed, combined, or deleted. Further, the other steps, measures, and solutions in the various operations, methods, and processes discussed in the present utility model can also be alternated, changed, rearranged, decomposed, combined, or deleted. Further, the steps, measures, and solutions in the relevant technologies that are the same as those disclosed in the various operations, methods, and processes of the present utility model can also be alternated, changed, rearranged, decomposed, combined, or deleted.

[0112] In the description of the present utility model, the directions or positional relationships indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are the exemplary directions or positional relationships based on the drawings, and are for the convenience of describing or simplifying the embodiments of the present utility model, rather than indicating or implying that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present utility model.

[0113] The terms "first" and "second" are only used for descriptive purposes, and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present utility model, unless otherwise specified, the meaning of "plurality" is two or more.

[0114] In the description of the present utility model, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific situations.

[0115] In the description of this specification, the specific features, structures, materials, or characteristics can be combined in a suitable manner in any one or more embodiments or examples.

[0116] The above are only some embodiments of the present utility model. It should be noted that for those of ordinary skill in the art, without departing from the technical concept of the solution of the present utility model, adopting other similar implementation means based on the technical idea of the present utility model also belongs to the protection scope of the present utility model.

Claims

1. An LED lighting circuit, characterized in that, Comprising: A filter circuit, a control circuit, and a power loop connected in sequence; Wherein, the filter circuit receives a PWM signal; The filter circuit filters the PWM signal to obtain a DC level signal, and outputs the DC level signal to the control circuit; The control circuit processes the DC level signal to obtain a ripple current, and outputs the ripple current to the power loop; The power loop outputs the ripple current to the LED lighting unit to supply power to the LED lighting unit.

2. The LED lighting circuit according to claim 1, wherein, The filter circuit includes a first resistor, a second resistor, and a first capacitor; Wherein, the first end of the first resistor is disposed at the input end of the filter circuit and is connected to a micro control unit, and the micro control unit is used to output the PWM signal to the filter circuit; The second end of the first resistor, the first end of the second resistor, and the first end of the first capacitor are connected and set as the output end of the filter circuit to be connected to the control circuit; The second end of the second resistor and the second end of the first capacitor are grounded.

3. The LED lighting circuit according to claim 1, characterized in that, The control circuit includes a first chip; the first chip includes a DIM pin and a DR pin; Wherein, the DIM pin is connected to the output end of the filter circuit and is used to receive the DC level signal output by the filter circuit; The DR pin is connected to the power loop and is used to output the ripple current to the power loop.

4. The LED lighting circuit according to claim 3, characterized in that, The power loop includes a switch module; The switch module includes: a first MOS transistor, a third resistor, and a fourth resistor; Wherein, the first end of the third resistor is connected to the DR pin of the first chip; the second end of the third resistor, the gate of the first MOS transistor, and the first end of the fourth resistor are connected; the source of the first MOS transistor and the second end of the fourth resistor are grounded.

5. The LED lighting circuit according to claim 4, characterized in that, The power loop further includes: a current detection module, a first polarized capacitor, an EMC common mode inductor, a power inductor, and a first diode; Wherein, the current detection module includes a fifth resistor, a sixth resistor, and a seventh resistor connected in parallel; the first ends of the fifth resistor, the sixth resistor, and the seventh resistor are connected and set as the first end of the current detection module; the second ends of the fifth resistor, the sixth resistor, and the seventh resistor are connected and set as the second end of the current detection module; The positive electrode of the first polarized capacitor is connected to the first end of the current detection module, and the negative electrode of the first polarized capacitor is grounded; the second end of the current detection module is connected to the first end of the EMC common mode inductor, the second end of the EMC common mode inductor is connected to the positive electrode of the LED lighting unit for supplying power to the LED lighting unit; the third end of the EMC common mode inductor is connected to the negative electrode of the LED lighting unit; the fourth end of the EMC common mode inductor is connected to the negative electrode of the power inductor, and the positive electrode of the power inductor is connected to the drain of the first MOS transistor; The positive electrode of the first diode is connected to the positive electrode of the power inductor, and the negative electrode of the first diode is connected to the first end of the current detection module.

6. The LED lighting circuit according to claim 5, wherein, When the output voltage of the DR pin is greater than or equal to the first voltage, the first MOS transistor is turned on; The ripple current flows from the positive electrode of the first polar capacitor through the first end of the current detection module, the second end of the current detection module, the first end and the second end of the EMC common-mode inductor, the positive and negative electrodes of the LED lighting unit, the third end and the fourth end of the EMC common-mode inductor, the negative electrode of the power inductor, the positive electrode of the power inductor, the drain of the first MOS transistor, and the source of the first MOS transistor back to ground; When the output voltage of the DR pin is less than the first voltage, the first MOS transistor is turned off; The power inductor releases the ripple current; the ripple current sequentially flows through the positive electrode of the power inductor, the positive electrode of the first diode, the negative electrode of the first diode, the first end of the current detection module, the second end of the current detection module, and the positive and negative electrodes of the LED lighting unit, and then returns to the negative electrode of the power inductor.

7. The LED lighting circuit according to claim 5, characterized in that The power loop further includes: a second polar capacitor and an eighth resistor; Wherein, the positive electrode of the second polar capacitor and the first end of the eighth resistor are connected to the second end of the current detection module, and the negative electrode of the second polar capacitor and the second end of the eighth resistor are connected to the negative electrode of the power inductor; The second polar capacitor is used for filtering the ripple current flowing through the LED lighting unit, and the eighth resistor is used for discharging the second polar capacitor.

8. The LED lighting circuit according to claim 7, characterized in that, The control circuit further includes a second capacitor and a third capacitor, and the first chip further includes an IN pin, an RS pin, a VCC pin, and a GND pin; Wherein, the IN pin, the first end of the second capacitor, and the first end of the current detection module are connected; the RS pin is connected to the second end of the current detection module; the current flowing through the power loop is obtained through the IN pin and the RS pin; The VCC pin is connected to the first end of the third capacitor; the second end of the second capacitor, the second end of the third capacitor, and the GND pin are respectively grounded.

9. An LED lighting system, characterized in that, It includes an LED lighting unit and the LED lighting circuit according to any one of claims 1-8, and the LED lighting circuit is connected to the LED lighting unit.

10. A clothes dryer, characterized in that, It includes: The LED lighting system according to claim 9.

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