LED power supply to eliminate afterglow

Abstract

LED power supply for eliminating afterglow, characterized in that it comprises a DC / DC converter module, a controller, a switching module, a power consumption module and a drive module; wherein the DC / DC converter module is provided with an output capacitor Cout, wherein the switching module is coupled to the negative terminal of the input side of the output capacitor Cout, wherein the power consumption module is connected in parallel to the output side of the output capacitor Cout, wherein the controller is electrically connected to the power consumption module via the drive module, and wherein both the DC / DC converter module and the switching module are electrically connected to the controller.

Description

TECHNICAL AREA

[0001] The utility model relates to the technical field of driver power supply, in particular to an LED power supply that can eliminate afterglow. STATE OF THE ART

[0002] Afterglow is a common problem faced by LED power supplies; one principle of afterglow formation is in Fig. Figure 1 shows that when a DC / DC conversion module P2 is pulled down by a dimming signal PWM1 and enters a light-out state, an L input end passes through a rectifier P1, a DC / DC conversion module P2, a load P3 (LED), and a load parasitic capacitor P4 to a PE earth terminal, forming a path in which a voltage from the L input end to the PE earth terminal is negative (e.g., PE → CP1 → Cout → L). This voltage is applied across an output capacitor Cout of the DC / DC conversion module P2 and the load parasitic capacitor P4, generating a leakage current that causes afterglow in the load P3 along the path. If the load P3 has several parallel branches (with the corresponding plurality of parallel load parasitic capacitors P4), each branch has a parallel voltage (e.g. PE → CP2 → LED2 → LED3 → L, PE → CP3 → LED3 → L), which also causes the afterglow.

[0003] Therefore, due to the aforementioned principle of afterglow, an existing LED power supply is typically connected in series with diodes at one positive and one negative electrode between the DC / DC conversion module P2 and the load P3 to interrupt the current path and achieve the goal of eliminating afterglow. However, during normal operation of the LED power supply, the output current must also pass through the diodes to reach the load P3, resulting in current losses, reduced conversion efficiency, and potentially insufficient LED brightness.

[0004] Even if the diodes can prevent the leakage current from charging the output capacitor Cout, a residual voltage higher than the LED turn-on voltage remains on the output capacitor Cout; it is necessary to wait until the residual voltage on the output capacitor Cout slowly decreases below the LED turn-on voltage, which means that the LED afterglow continues for a period of time, resulting in a poor afterglow installation. CONTENT OF THE PRESENT INVENTION

[0005] In response to the aforementioned disadvantages, the purpose of the utility model is to propose an afterglow LED power supply that solves problems of extended afterglow time and the impact on the conversion efficiency of the LED power supply.

[0006] To achieve this purpose, the utility model proposes the following technical solution: a phosphorescent LED power supply comprising a DC / DC conversion module, a control module, a switching module, a power consumption module and a drive module; the DC / DC conversion module is provided with an output capacitor Cout, the switching module is coupled to a negative electrode of an input side of the output capacitor Cout, the power consumption module is connected in parallel to an output side of the output capacitor Cout, the control unit is electrically connected to the power consumption module via the drive module and both the DC / DC conversion module and the switching module are electrically connected to the control unit.

[0007] Furthermore, the energy consumption module comprises a switching tube and at least one resistor R1; a positive electrode of the switching tube is electrically connected to a positive electrode of the output side of the output capacitor Cout; a negative electrode of the switching tube is connected in series with the resistor(s) R1 and subsequently electrically connected to a negative electrode of the output side of the output capacitor Cout; and a control end of the switching tube is electrically connected to the drive module.

[0008] Furthermore, the switching tube is a triode Q1, an emitter of triode Q1 serves as the positive electrode of the switching tube, a collector of triode Q1 serves as the negative electrode of the switching tube, and a base of triode Q1 serves as the control end of the switching tube; and the drive module comprises a resistor R3, a resistor R4, a resistor R5, and a triode Q2; the base of triode Q1 is sequentially connected in series with resistor R3 and resistor R4 and then electrically connected to a collector of triode Q2; a base of triode Q2 is connected in series with resistor R5 and then electrically connected to the control; and an emitter of triode Q2 is electrically connected to the negative electrode of the output side of the output capacitor Cout.

[0009] Furthermore, the drive module is a constant current source.

[0010] Furthermore, the switching tube is a MOS tube Q4, an outlet of the MOS tube Q4 serves as the positive electrode of the switching tube, a source of the MOS tube Q4 serves as the negative electrode of the switching tube, and a gate of the MOS tube Q4 serves as the control end of the switching tube.

[0011] Furthermore, the drive module includes a resistor R9, a resistor R10, a resistor R11, a resistor R12, an operating amplifier U3B and a capacitor C2;One end of resistor R9 and one end of resistor R10 are both electrically connected to the gate of MOSFET Q4; another end of resistor R9 is electrically connected to an output terminal of operational amplifier U3B; another end of resistor R10 and an inverting input terminal of operational amplifier U3B are both electrically connected to the source of MOSFET Q4; a non-inverting input terminal of operational amplifier U3B is electrically connected to one end of resistor R11; another end of resistor R11 and one end of capacitor C2 are both electrically connected to one end of resistor R12; another end of capacitor C2 is electrically connected to the negative terminal of the output side of output capacitor Cout; and another end of resistor R12 is electrically connected to the regulator. Furthermore, the switching module includes a MOSFET Q3, a resistor R6, and a resistor R7.A source and a derivative of the MOS tube Q3 are connected in series with the negative electrode of the input side of the output capacitor Cout; a gate of the MOS tube Q3 is connected in series with the resistor R7 and then electrically connected to the control unit; and the resistor R6 is connected in parallel between the source and the gate of the MOS tube Q3.

[0012] Furthermore, the DC / DC conversion module is equipped with a diode D5 and a DC / DC conversion chip U1; the diode D5 is coupled to a positive electrode of the input side of the output capacitor Cout, an anode of the diode D5 is electrically connected to the DC / DC conversion chip U1, and a cathode of the diode D5 is electrically connected to the output capacitor Cout.

[0013] The technical solution provided by the utility model can have the following advantageous effects: the switching module remains conductive during normal operation of the LED power supply; when the controller sets the DC / DC conversion module to receive a PWM1 dimming signal and switch off a light, the controller (e.g., an MCU) first sends a PWM3 signal to keep the power consumption module activated via the drive module for a predetermined power consumption period (which can be specified according to the actual conditions); during this period, the power consumption module quickly dissipates any leakage current, and because it is connected in parallel, it does not cause any current loss or impair the conversion efficiency during normal operation of the LED power supply;After the power consumption module has eliminated the reverse leakage current, the controller then sends a PWM2 signal to disconnect the negative electrode of the input side of the output capacitor Cout via the switching module, thus creating a path break (otherwise, a residual voltage at the output capacitor Cout would continue to power an LED); thus, when the leakage current dissipates and the path is broken, the afterglow can be eliminated in an extremely short time, resulting in better performance without affecting the conversion efficiency of the LED power supply during normal operation. BRIEF DESCRIPTION OF THE DRAWING Fig. 1. A circuit diagram of an existing LED power supply. Fig. 2 a circuit diagram of a photoluminescent LED power supply according to embodiment 1 of the utility model. Fig. 3 a circuit diagram of a photoluminescent LED power supply according to embodiment 2 of the utility model.

[0014] These include: DC / DC conversion module 1, switching module 2, power consumption module 3, drive module 4, output capacitor Cout, resistor R1, triode Q1, resistor R3, resistor R4, resistor R5, triode Q2, MOS tube Q4, resistor R9, resistor R10, resistor R11, resistor R12, operating amplifier U3B, capacitor C2, MOS tube Q3, resistor R6, resistor R7, diode D5, DC / DC conversion chip U1. DETAILED DESCRIPTION

[0015] The embodiments of the utility model are described in more detail below. Examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements with the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and serve solely to illustrate the utility model and should not be interpreted as limiting the utility model.

[0016] In the description of the embodiments of the utility model, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying a relative meaning or as implicitly specifying a quantity of a stated technical feature. Thus, a feature defined by "first" and "second" may explicitly or implicitly comprise one or more such features. In the description of the embodiments of the utility model, the term "a plurality of" means two or more, unless expressly and specifically defined otherwise.

[0017] When describing the embodiments of the utility model, it should be noted that, unless expressly stated and defined otherwise, the terms "install," "connected," and "connect" are to be understood broadly. A connection may, for example, be a permanent connection, a detachable connection, or an integral connection. It may be a direct connection, an indirect connection via an intermediate medium, internal communication between two elements, or an interaction relationship between two elements. A person skilled in the art may understand specific meanings of the aforementioned terms in embodiments of the utility model based on specific contexts.

[0018] Regarding the Fig. 2 to Fig. 3 below describes an LED power supply which, according to the embodiments of the utility model, can eliminate afterglow.

[0019] The afterglow LED power supply comprises a DC / DC conversion module 1 and a controller, further comprising a switching module 2, a power consumption module 3 and a drive module 4; the switching module 2 is coupled to a negative electrode of an input side of an output capacitor Cout of the DC / DC conversion module 1, the power consumption module 3 is connected in parallel to an output side of the output capacitor Cout, the controller is electrically connected to the power consumption module 3 via the drive module 4 and both the DC / DC conversion module 1 and the switching module 2 are electrically connected to the controller.

[0020] In a preferred embodiment of the LED power supply that can eliminate afterglow, as in Fig. 2 or Fig. As shown in Figure 3, the switching module 2 remains conductive during normal operation of the LED power supply. When the controller sets the DC / DC conversion module 1 to receive a dimming signal PWM1 and switch off a light, the controller (e.g., an MCU) first sends a PWM3 signal to keep the power consumption module 3 activated via the drive module 4 for a predetermined power consumption period (which can be specified according to the actual state). During this period, the power consumption module 3 quickly dissipates any leakage current, and because it is connected in parallel, it does not cause any power loss or impair conversion efficiency during normal operation of the LED power supply.After the power consumption module 3 has eliminated the reverse leakage current, the controller then sends a PWM2 signal to disconnect the negative electrode of the input side of the output capacitor Cout via the switching module 2, thus creating a path break (otherwise, a residual voltage across the output capacitor Cout would continue to power an LED). Therefore, once the leakage current dissipates and the path is broken, the afterglow is eliminated extremely quickly, resulting in improved performance without affecting the conversion efficiency of the LED power supply during normal operation. Furthermore, the switching module 2 comprises a MOSFET Q3, a resistor R6, and a resistor R7. A source and a derivative of the MOSFET Q3 are connected in series with the negative electrode of the input side of the output capacitor Cout. A gate of the MOSFET Q3 is connected in series with resistor R7 and subsequently electrically connected to the control unit.and the resistor R6 is connected in parallel between the source and the gate of the MOS tube Q3.;

[0021] In this embodiment, the switching module 2 preferably consists of the MOS tube Q3 and its circumferential circuitry; when the MOS tube Q3 is switched off, an equivalent capacitor CQ3 of the MOS tube Q3 can be connected in series with the output capacitor Cout and a load-parasitic capacitor CP1 in a loop from an L input end to a PE earth terminal; due to a smaller capacitance and a larger equivalent impedance of the equivalent capacitor CQ3, the voltage across the output capacitor Cout and the load-parasitic capacitor CP1 can be significantly lower, and the correspondingly generated leakage current can also be low, which further reduces the predetermined energy dissipation time.

[0022] Furthermore, the DC / DC conversion module 1 is equipped with a diode D5 and a DC / DC conversion chip U1; the diode D5 is coupled to a positive electrode of the input side of the output capacitor Cout, an anode of the diode D5 is electrically connected to the DC / DC conversion chip U1, and a cathode of the diode D5 is electrically connected to the output capacitor Cout.

[0023] In this embodiment, if the DC / DC conversion module 1 is of a boost architecture, then the diode D5 functions as a rectifier; if the DC / DC conversion module 1 is of a buck architecture, the diode serves to prevent reverse switching (i.e., an input being connected to an output end), both of which are essential measures to ensure the safety of the DC / DC conversion module 1.

[0024] It should be noted that diode D5 is not the diode used to block leakage current in the background; the diode mentioned in the background must also be provided on the output side of the output capacitor Cout. Design 1

[0025] The energy consumption module 3 comprises a switching tube and at least one resistor R1; a positive electrode of the switching tube is electrically connected to a positive electrode of the output side of the output capacitor Cout; a negative electrode of the switching tube is connected in series with the resistor(s) R1 and subsequently electrically connected to a negative electrode of the output side of the output capacitor Cout; and a control end of the switching tube is electrically connected to the drive module 4.

[0026] In this embodiment, as in Fig. As shown in Figure 2, the consumption of the leakage current by the energy dissipation module 3 is achieved primarily by utilizing an equivalent resistance loss of one or more resistors R1 for discharge; that is, when the switching tube is turned on, the resistors R1 are connected in series and then in parallel across the output capacitor Cout. Due to the small resistance value and large capacitance of the resistors R1, the discharge rate is very fast, so that the output capacitor Cout releases energy within a short time.

[0027] Furthermore, the switching tube is a triode Q1, an emitter of triode Q1 serves as the positive electrode of the switching tube, a collector of triode Q1 serves as the negative electrode of the switching tube, and a base of triode Q1 serves as the control end of the switching tube; and the drive module 4 comprises a resistor R3, a resistor R4, a resistor R5, and a triode Q2; the base of triode Q1 is sequentially connected in series with resistor R3 and resistor R4 and then electrically connected to a collector of triode Q2; a base of triode Q2 is connected in series with resistor R5 and then electrically connected to the control; and an emitter of triode Q2 is electrically connected to the negative electrode of the output side of the output capacitor Cout.

[0028] In this embodiment, in order to increase the switching speed of the energy consumption module 3, both the switching tube and the drive module 4 preferably adopt the triode in coordination with the control system for the drive. Design 2

[0029] The drive module 4 is a constant current source.

[0030] Given that the energy dissipation module 3 mainly uses the resistors for discharge and energy consumption, even with low resistance the current consumed by the resistors decreases with decreasing voltage, i.e. during a discharge process the consumed current gradually decreases with decreasing voltage and also the dissipated power decreases, which can lead to incomplete elimination of the leakage current within the given energy dissipation time.

[0031] In this embodiment, to solve this problem, as in Fig.As shown in Figure 3, by modifying the drive module 4 in the constant current source circuit, the immediate discharge current consumption of the power consumption module 3 can be significantly increased, and the same level of current consumption can be maintained across different output voltage values. This further reduces the specified energy consumption time, allowing the output capacitor Cout voltage to be discharged almost instantly to a level far below the LED's turn-on voltage. This eliminates the possibility of afterglow and provides the user with a better experience. More importantly, for different types of LEDs, the constant current source output can be adjusted via the controller to accommodate leakage currents generated by various loads, thus improving product compatibility.

[0032] Furthermore, the switching tube is a MOS tube Q4, an outlet of the MOS tube Q4 serves as the positive electrode of the switching tube, a source of the MOS tube Q4 serves as the negative electrode of the switching tube, and a gate of the MOS tube Q4 serves as the control end of the switching tube.

[0033] In this embodiment, since the drive module 4 is the constant current source, it can withstand a higher discharge power; in this case, the switching tube is preferably the MOS tube Q4.

[0034] Furthermore, the drive module 4 includes a resistor R9, a resistor R10, a resistor R11, a resistor R12, an operating amplifier U3B and a capacitor C2;One end of resistor R9 and one end of resistor R10 are both electrically connected to the gate of the MOS tube Q4, another end of resistor R9 is electrically connected to an output end of operational amplifier U3B, another end of resistor R10 and an inverting input end of operational amplifier U3B are both electrically connected to the source of the MOS tube Q4, a non-inverting input end of operational amplifier U3B is electrically connected to one end of resistor R11, another end of resistor R11 and one end of capacitor C2 are both electrically connected to one end of resistor R12, another end of capacitor C2 is electrically connected to the negative electrode of the output side of the output capacitor Cout, and another end of resistor R12 is electrically connected to the regulator.

[0035] In this embodiment, based on a requirement to switch the MOS tube Q4 on or off, the constant current source circuit of the drive module 4 preferably consists of resistor R9, resistor R10, resistor R11, resistor R12, the operating amplifier U3B and capacitor C2; one principle of this is as follows: the PWM3 signal transitions from a low level to a signal with a certain duty cycle, this signal passes through an RCR filter network (resistor R11, resistor R12 and capacitor C2) to a fixed voltage reference value, and this voltage can be called Vref;Due to a virtual short sign of an operational amplifier, a voltage at the inverting input end of the operational amplifier U3B is also Vref, and a constant output current of the drive module 4 is I = Vref / R1 (based on the resistors R1 can be one or more, and R1 represents a total resistance value of resistor R1), which allows the MOS tube Q4 to operate in a saturation region.

[0036] Other components and operations of the LED power supply that can eliminate afterglow according to the embodiments of the utility model are known to those skilled in the art and are not described in detail here.

[0037] In the description of this specification, a description referring to terms such as "elaboration" or "example" means that specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, schematic representations of the aforementioned terms do not necessarily refer to the same embodiment or example. Furthermore, the described specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0038] Although the embodiments of the utility model have been shown and described, the person skilled in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the utility model; the scope of the utility model is defined by the claims and their equivalents.

Claims

[1] LED power supply to eliminate afterglow, characterized by , comprising a DC / DC converter module, a controller, a switching module, a power consumption module and a drive module; wherein the DC / DC converter module is provided with an output capacitor Cout, wherein the switching module is coupled to the negative terminal of the input side of the output capacitor Cout, wherein the power consumption module is connected in parallel to the output side of the output capacitor Cout, wherein the controller is electrically connected to the power consumption module via the drive module, and wherein both the DC / DC converter module and the switching module are electrically connected to the controller. [2] LED power supply for eliminating afterglow according to claim 1, characterized by, that the energy consumption module comprises a switching transistor and at least one resistor R1; wherein the positive terminal of the switching transistor is electrically connected to the positive terminal of the output side of the output capacitor Cout; wherein the negative terminal of the switching transistor is electrically connected to the negative terminal of the output side of the output capacitor Cout after it has been connected in series with one or more resistors R1; wherein a control terminal of the switching transistor is electrically connected to the control module. [3] LED power supply for eliminating afterglow according to claim 2, characterized by, that the switching transistor is transistor Q1, wherein the emitter of transistor Q1 serves as the positive terminal of the switching transistor, the collector of transistor Q1 serves as the negative terminal of the switching transistor, and the base of transistor Q1 serves as the control terminal of the switching transistor; wherein the control module comprises a resistor R3, a resistor R4, a resistor R5, and a transistor Q2; wherein the base of transistor Q1 is connected successively in series with resistor R3 and resistor R4 and then electrically connected to the collector of transistor Q2; wherein the base of transistor Q2 is connected in series with resistor R5 and electrically connected to the control; and wherein the emitter of transistor Q2 is electrically connected to the negative terminal of the output side of the output capacitor Cout. [4] LED power supply for eliminating afterglow according to claim 2, characterized bythat the control module is a constant current source. [5] LED power supply for eliminating afterglow according to claim 4, characterized by , that the switching transistor is a MOS transistor Q4, wherein the drain of the MOS transistor Q4 serves as the positive terminal of the switching transistor, wherein the source of the MOS transistor Q4 serves as the negative terminal of the switching transistor, and wherein the gate of the MOS transistor Q4 serves as the control terminal of the switching transistor. [6] LED power supply for eliminating afterglow according to claim 5, characterized by, that the control module includes a resistor R9, a resistor R10, a resistor R11, a resistor R12, an operational amplifier U3B and a capacitor C2;wherein one end of resistor R9 and one end of resistor R10 are each electrically connected to the gate of MOS transistor Q4, wherein the other end of resistor R9 is electrically connected to the output end of operational amplifier U3B, wherein the other end of resistor R10 and the negative input end of operational amplifier U3B are each electrically connected to the source of MOS transistor Q4, wherein the positive input end of operational amplifier U3B is electrically connected to one end of resistor R11, wherein the other end of resistor R11 and one end of capacitor C2 are each electrically connected to one end of resistor R12, wherein the other end of capacitor C2 is electrically connected to the negative terminal of the output side of output capacitor Cout, and wherein the other end of resistor R12 is electrically connected to the control. [7] LED power supply for eliminating afterglow according to claim 1, characterized by , that the switching module comprises a MOS transistor Q3, a resistor R6 and a resistor R7; wherein the source and drain of the MOS transistor Q3 are connected in series with the negative terminal of the input side of the output capacitor Cout; wherein the gate of the MOS transistor Q3 is connected in series with the resistor R7 and then electrically connected to the control; and wherein the resistor R6 is connected in parallel between the source and the gate of the MOS transistor Q3. [8] LED power supply for eliminating afterglow according to claim 1, characterized by, that the DC / DC converter module is further equipped with a diode D5 and a DC / DC converter chip U1; wherein the diode D5 is coupled to the negative terminal of the input side of the output capacitor Cout, wherein the anode of the diode D5 is electrically connected to the DC / DC converter chip U1, and wherein the cathode of the diode D5 is electrically connected to the output capacitor Cout.

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