LED dimming power supply

Abstract

The utility model discloses an LED dimming power supply, which comprises a power module, a control line, a silicon controlled rectifier follow current module, a silicon controlled rectifier sampling module and a dimming control module, the power module can convert alternating current into direct current to supply power to an LED load, one end of the control line is electrically connected with a silicon controlled rectifier dimmer, and the other end of the control line is electrically connected with the silicon controlled rectifier sampling module. The other end of the control line is electrically connected with the input end of the silicon controlled rectifier follow current module, the output end of the silicon controlled rectifier follow current module is electrically connected with the input end of the silicon controlled rectifier sampling module, and the output end of the silicon controlled rectifier sampling module is electrically connected with the input end of the dimming control module. The output end of the dimming control module is electrically connected with the output end of the power module so as to output a PWM signal to drive an LED load; a dimming signal of a silicon controlled rectifier dimmer is transmitted to the silicon controlled rectifier sampling module through the silicon controlled rectifier follow current module, and the silicon controlled rectifier sampling module can convert the dimming signal into a square signal to control the dimming control module to output a PWM signal.

Description

Technical Field

[0001] The utility model relates to the technical field of thyristor dimming, in particular to an LED dimming power supply. Background Art

[0002] Thyristor dimming technology is mainly used for traditional incandescent lamps and halogen lamps (resistance wire type). Because it is purely resistive, there is no instantaneous interference when the thyristor is turned on and off. The dimming circuit is simple and easy to use. Existing thyristor dimming solutions are designed for LEDs. They require a driver power supply to function properly. The thyristor dimmer is directly connected in series with the driver power supply's live input line, making it incompatible with the 100-277V input voltage range and limited to a fixed-voltage dimming range, resulting in poor compatibility. Furthermore, the power supply's input energy is determined by the thyristor dimmer's conduction angle. For example, if the thyristor dimmer's conduction angle is too small, the energy input to the power supply during the entire AC cycle is minimal, resulting in insufficient output voltage, which can cause insufficient brightness or flickering. Furthermore, the power supply's input sinusoidal waveform is incomplete at any thyristor conduction angle. Regardless of whether the thyristor is switched on first or last, a spike is generated at the moment of phase-cutting, generating noise that can interfere with the power grid. Furthermore, since the power supply's input sinusoidal waveform is incomplete at any thyristor conduction angle, the power supply's PF value and harmonics cannot meet standard ranges, with both harmonic and conduction voltage levels exceeding standards. The lower the dimming brightness, the more serious the problem. The input current is severely distorted, and the harmonics and PF values ​​cannot meet the EMC standards, causing interference to the power grid. Utility Model Content

[0003] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art and to provide an LED dimming power supply that reduces interference to the power grid.

[0004] According to an embodiment of the utility model, the LED dimming power supply includes a power module, a control line, a thyristor freewheeling module, a thyristor sampling module and a dimming control module. The power module can convert alternating current into direct current to power the LED load. One end of the control line is electrically connected to the thyristor dimmer, and the other end of the control line is electrically connected to the input end of the thyristor freewheeling module. The output end of the thyristor freewheeling module is electrically connected to the input end of the thyristor sampling module. The output end of the thyristor sampling module is electrically connected to one end of the isolation module, and the other end of the isolation module is electrically connected to the input end of the dimming control module. The output end of the dimming control module is electrically connected to the output end of the power module to output a PWM signal to drive the LED load; the dimming signal of the thyristor dimmer is transmitted to the thyristor sampling module via the thyristor freewheeling module, and the thyristor sampling module can convert the dimming signal into a square wave signal to control the dimming control module to output a PWM signal.

[0005] The LED dimming power supply according to the embodiment of the present invention has at least the following beneficial effects: 1. Electrically connected to a thyristor dimmer via a control line to sample the thyristor dimmer's dimming signal, the thyristor freewheeling module maintains the thyristor's conduction state, and the thyristor sampling module samples the dimming signal's conduction angle signal, which is then transmitted to the dimming control module to control the output PWM. Thus, changing the thyristor's conduction angle is equivalent to changing the LED's brightness. 2. Because the thyristor dimmer is not connected to the live wire, the power module of the power supply can input a complete AC signal through the neutral and live wires, regardless of whether the load is 100% or 10%, and is unaffected by the thyristor dimming portion. Its harmonics and PF value are well controlled, meeting the EMC standards for LED power supplies. Linear output power is achieved in any thyristor dimming state, unrestricted by the thyristor's conduction angle. 2. During dimming, the dimming signal comes from the thyristor freewheeling module and the sampling module and is not affected by the power size of the power module. Regardless of the conduction angle of the thyristor dimmer, the dimming signal is stable, avoiding the difficulty of flickering at low brightness of traditional thyristor dimming. In addition, the dimming response speed is fast and the dimming can also be linear because the power module is in normal working condition throughout the dimming range, and only the load changes. 3. In application, if the control line is not connected to the thyristor dimmer, the power supply is a conventional non-dimming power supply and does not affect normal use. When dimming is required, the control line is connected to the thyristor dimmer, and the neutral and live wires are connected to the power module normally. The overall wiring is convenient, and one dimmer can be connected to the control lines of multiple power supplies to achieve synchronous dimming.

[0006] Additional aspects and advantages of the present invention will be given in part in the following description and will become apparent from the following description or learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The following is a further description of the specific embodiments of the present invention in conjunction with the accompanying drawings;

[0008] Figure 1 This is the principle block diagram of LED dimming power supply;

[0009] Figure 2 This is a schematic diagram of synchronous dimming of multiple driving power supplies;

[0010] Figure 3 This is the circuit diagram of the LED dimming power supply. DETAILED DESCRIPTION

[0011] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present invention, but it cannot be understood as a limitation on the scope of protection of the present invention.

[0012] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0013] In the description of this utility model, "several" means one or more, "many" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and is not to be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0014] Reference Figures 1 to 3The utility model provides an LED dimming power supply, including a power module 10, a control line, a thyristor freewheeling module 11, a thyristor sampling module 12, an isolation module 13 and a dimming control module. The input end of the power module 10 is connected to the live wire and the neutral wire to convert alternating current into direct current to power the LED load. One end of the control line is electrically connected to the thyristor dimmer, and the other end of the control line is electrically connected to the input end of the thyristor freewheeling module 11. The output end of the thyristor freewheeling module 11 is electrically connected to the input end of the thyristor sampling module 12. The output end of the thyristor sampling module 12 is electrically connected to one end of the isolation module 13, and the other end of the isolation module 13 is electrically connected to the input end of the dimming control module. The output end of the dimming control module is electrically connected to the output end of the power module 10 to output a PWM signal to drive the LED load; the dimming signal of the thyristor dimmer is transmitted to the thyristor sampling module 12 via the thyristor freewheeling module 11, and the thyristor sampling module 12 can convert the dimming signal into a square wave signal to control the dimming control module to output a PWM signal. That is, the driver power supply is electrically connected to the thyristor dimmer via a control line to sample the dimming signal of the thyristor dimmer. The thyristor freewheeling module 11 maintains the thyristor in the conductive state, and the thyristor sampling module 12 samples the conduction angle signal of the dimming signal. After signal isolation processing by the isolation module 13, it is sent to the dimming control module to control the output PWM. In this way, changing the conduction angle of the thyristor is equivalent to changing the brightness of the LED. It has the following advantages: 1. Because the thyristor dimming part is not connected to the live wire, the power module 10 in the driver power supply can input a complete AC signal through the neutral wire and the live wire, regardless of whether it is 100% load or 10% load, and is not affected by the thyristor dimming part. Its harmonics and PF value are well controlled, both of which can meet the EMC standards of LED power supplies. Linear output power can be achieved in any state of the thyristor dimming, without being limited by the thyristor conduction angle. 2. During dimming, the dimming signal comes from the thyristor freewheeling module 11 and the sampling module, and is not affected by the power size of the power module 10. Regardless of the conduction angle of the thyristor dimmer, the dimming signal is stable, avoiding the difficulty of low-brightness flickering of traditional thyristor dimming. In addition, the dimming response speed is fast and the dimming can also be linear, because in the entire dimming range, the power module 10 is in normal working condition, only the weight of the load changes. 3. In application, if the control line is not connected to the thyristor dimmer, the driving power supply is a conventional non-dimming power supply, which does not affect normal use. When dimming is required, the control line is connected to the thyristor dimmer, and the neutral and live wires are normally connected to the power module 10, making the overall wiring convenient.

[0015] like Figure 2 In some embodiments, there are multiple dimming power supplies, and a thyristor dimmer is electrically connected to the control lines of the multiple dimming power supplies to achieve synchronous dimming.

[0016] like Figure 3In some embodiments, the thyristor freewheeling module 11 includes a diode D1, a constant current IC U2, a resistor R5, and a diode Q2. The anode of diode D1 is electrically connected to the thyristor dimmer, the cathode of diode D1 is electrically connected to one end of the constant current IC U2, and the other end of the constant current IC U2 is electrically connected to the drain of the MOS transistor Q2 via a series voltage divider resistor R5. The source of the MOS transistor Q2 is grounded, and the gate of the MOS transistor Q2 is electrically connected to the thyristor sampling module 12. The thyristor sampling module 12 includes a MOS transistor Q3, a resistor R1, and a resistor R3. One end of the resistor R1 is electrically connected to the gate of the MOS transistor Q3, the other end of the resistor R1 is electrically connected to the cathode of diode D1, the source of the MOS transistor Q3 is grounded, one end of the resistor R3 is connected to the VCC voltage, and the drain of the MOS transistor Q3 is electrically connected to the other end of the resistor R3 and the isolation module 13. The isolation module 13 uses an optocoupler U3. The dimming control module includes an integration circuit 14 and a main control chip U1. The integration circuit 14 includes a MOS transistor Q4, a resistor R2, a resistor R4, and a capacitor C1. One output end of the isolation module is electrically connected to the drain of the MOS transistor Q2 and one end of the resistor R2 via a series resistor R4. The other end of the resistor R2 is electrically connected to one end of the capacitor C1 and the input end of the main control chip U1. The other end of the capacitor C1 and the source of the MOS transistor Q4 are grounded. The other output end of the isolation module 13 is electrically connected to the gate of the MOS transistor Q4 via a series resistor. U2 is a linear constant current IC, whose constant current is slightly greater than the thyristor freewheeling value, generally greater than about 20mA. The current is controlled by the constant current IC U2 determines the voltage, ZD1 is the MOS driver for the voltage regulator protection, and a 12V zener is generally used. Resistor R1 provides a bias voltage for the MOS transistor to turn on. When the thyristor dimmer is turned on, MOS transistor Q2 is turned on, and MOS transistor Q3 is also turned on. At this time, the optocoupler U3 is turned off, and the emitter of the optocoupler U3 outputs a high level, which controls the MOS transistor Q4 to turn on through resistor R9, and outputs a low level through resistor R2. When the thyristor dimmer is not turned on, the VIN node connected to one end of the resistor R1 has no voltage, MOS transistor Q3 is turned off, and the optocoupler U3 is turned on. The emitter of the optocoupler U3 outputs a low level, which controls the MOS transistor Q4 to turn off through resistor R9. At this time, the 5V voltage passes through resistors R4 and R2 to charge capacitor C1 to form an integration circuit 14. By adjusting the parameters, a smooth voltage value can be obtained on capacitor C1, and this voltage value is controlled by the conduction angle of the thyristor. The main control chip U1 outputs a PWM signal from pin 3 to drive MOS transistor Q1 according to the voltage value on capacitor C1, thereby achieving LED brightness adjustment.

[0017] That is, the key to the thyristor dimming system is to add another control line, which is specifically used to sample the thyristor dimming signal, and the power module 10 in the driving power supply can be a variety of different power supply topologies. Their working principles are the same as those of a normal power supply (generally including a lightning surge module, a rectifier module, a PFC module, a power conversion module, a rectifier and filter module, and a PWM output module, which are used to convert the AC power into a voltage to power the LED). The input power is L / N. If the metal casing also includes a ground wire, the input voltage range can be 100-277V. During the dimming process, the input sinusoidal waveform of the power supply is complete and is not affected by the conduction angle of the thyristor dimmer. Therefore, its PF value / harmonic noise can easily meet the EMC standard range. The control line added to the system is specifically used to sample the thyristor dimming signal. Any conduction angle of the thyristor does not affect the input sinusoidal waveform of the power module 10, and the thyristor freewheeling circuit uses a simple linear constant current to obtain a stable thyristor freewheeling state. The freewheeling circuit can obtain a square wave waveform with the same input sinusoidal frequency according to the conduction angle of the thyristor. The pulse width of the square wave waveform is controlled by the conduction angle of the thyristor. The square wave waveform is then isolated to the secondary of the power module 10 through the optocoupler U3. The dimming control module converts the square wave waveform into a voltage signal through the integration circuit 14, and then converts the voltage signal into a dimming PWM signal to control the output circuit. In this way, changing the conduction angle of the thyristor is equivalent to changing the output LED brightness. Regardless of the conduction angle of the thyristor, the LED dimming can be done stably, avoiding the difficulty of low-brightness flickering of traditional thyristor dimming. Moreover, the dimming response speed is fast and the dimming can be linear because the power module 10 is in normal working condition throughout the entire dimming range, and the only difference is the weight of the load. However, when the thyristor conduction angle of the existing thyristor dimming is very small, the effective sine waveform is also very small, and the input energy is very small. At this time, the power supply is in undervoltage protection due to the low input voltage or energy, or it takes a long time to start. In this way, the dimming response is very slow, generally delayed by 2-3 seconds, which is also something that traditional hardware circuits cannot improve.

[0018] The thyristor freewheeling module 11 can have various forms, but they are all essentially thyristor freewheeling, maintaining a controllable conduction effect after the thyristor is turned on. The thyristor sampling module 12 is essentially converting the input waveform into a square wave, which can be obtained in a variety of existing ways. The isolation module 13 uses optocoupler isolation, and can also use a digital isolation chip. The dimming control module also uses the square wave signal as the control signal to output PWM to control the MOS tube Q1, thereby controlling the brightness change of the output load LED.

[0019] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above preferred embodiments can be freely combined and superimposed.

[0020] The above are only preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention specification and drawings under the utility model concept, or directly or indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. An LED dimming power supply, characterized in that: include: A power module (10), a control line, a thyristor freewheeling module (11), a thyristor sampling module (12), an isolation module (13) and a dimming control module, wherein the power module (10) is capable of converting alternating current into direct current to power an LED load, one end of the control line is electrically connected to a thyristor dimmer, the other end of the control line is electrically connected to an input end of the thyristor freewheeling module (11), the output end of the thyristor freewheeling module (11) is electrically connected to an input end of the thyristor sampling module (12), and the output end of the thyristor sampling module (12) is electrically connected to an input end of the thyristor sampling module (12). The output end is electrically connected to one end of the isolation module (13), the other end of the isolation module (13) is electrically connected to the input end of the dimming control module, and the output end of the dimming control module is electrically connected to the output end of the power module (10) to output a PWM signal to drive an LED load; the dimming signal of the thyristor dimmer is transmitted to the thyristor sampling module (12) via the thyristor freewheeling module (11), and the thyristor sampling module (12) is capable of converting the dimming signal into a square wave signal to control the dimming control module to output a PWM signal.

2. The LED dimming power supply according to claim 1, characterized in that: The thyristor freewheeling module (11) comprises a diode D1, a constant current IC U2, a resistor R5 and a diode Q2, wherein the anode of the diode D1 is electrically connected to the thyristor dimmer, the cathode of the diode D1 is electrically connected to one end of the constant current IC U2, the other end of the constant current IC U2 is electrically connected to the drain of the MOS tube Q2 via the series voltage divider resistor R5, the source of the MOS tube Q2 is grounded, and the gate of the MOS tube Q2 is electrically connected to the thyristor sampling module (12).

3. The LED dimming power supply according to claim 2, characterized in that: The thyristor sampling module (12) comprises a MOS tube Q3, a resistor R1, and a resistor R3, one end of the resistor R1 being electrically connected to the gate of the MOS tube Q3, the other end of the resistor R1 being electrically connected to the cathode of the diode D1, the source of the MOS tube Q3 being grounded, one end of the resistor R3 being connected to a VCC voltage, and the drain of the MOS tube Q3 being electrically connected to the other end of the resistor R3 and the isolation module (13).

4. The LED dimming power supply according to claim 1, characterized in that: The dimming control module comprises an integration circuit (14) and a main control chip U1. The input end of the integration circuit (14) is electrically connected to the isolation module. The integration circuit (14) can be charged to output a smooth voltage value when the thyristor dimmer is not turned on. The output end of the integration circuit (14) is electrically connected to the input end of the main control chip U1. The main control chip U1 outputs a corresponding PWM signal according to the voltage value.

5. The LED dimming power supply according to claim 4, characterized in that: The integration circuit (14) includes a MOS tube Q4, a resistor R2, a resistor R4 and a capacitor C1. One output end of the isolation module is electrically connected to the drain of the MOS tube Q2 and one end of the resistor R2 via the series resistor R4. The other end of the resistor R2 is electrically connected to one end of the capacitor C1 and the input end of the main control chip U1. The other end of the capacitor C1 and the source of the MOS tube Q4 are grounded respectively. The other output end of the isolation module (13) is electrically connected to the gate of the MOS tube Q4 via the series resistor.

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