LED silicon controlled rectifier dimming stroboflash-free power source

Abstract

The utility model relates to an LED silicon controlled rectifier dimming stroboscopic-free power source, which comprises an input EMI circuit, a rectification circuit, a first surge suppression circuit, a filter circuit, a second surge suppression circuit, a power conversion circuit, a PWM control circuit, a constant current control circuit, a phase detection circuit, an overvoltage and undervoltage protection circuit, an output stroboscopic-free circuit and an LED load. The output current is synchronously adjusted along with the dimming angle, so that the dimming range and the dimming compatibility of the lamp can be improved; and the stroboflash removing circuit is arranged, so that the voltage of the LED load can be kept stable, the stroboflash removing purpose is achieved, and particularly, the condition that the lamp flickers at low brightness can be improved.

Description

Technical Field

[0001] This utility model relates to the field of LED lighting technology, and in particular to a flicker-free LED SCR dimming power supply. Background Technology

[0002] For over half a century, SCR (Silicon Controlled Rectifier) ​​technology has been highly mature and stable. Following SCR dimming, the lighting industry has adopted 0 / 1-10V analog dimming, DMX512, and DALI digital dimming protocols. However, SCR dimming technology still holds certain advantages. One is its historical legacy, and the other is its simplicity—requiring no signal cables and no need to modify existing wiring. It is also low-cost and easy to install, making it popular with project owners. Therefore, SCR dimming power supplies still hold the largest market share in the dimming power supply market. SCR dimming power supplies offer advantages such as minimal component usage, low cost, high power density, and voltage protection, making them suitable for low-power downlights and bulbs under 20W. LED lighting typically uses low-power power supplies.

[0003] In recent years, major markets such as Europe and the United States have put forward requirements for LED lighting products in terms of high efficiency, long life, high power factor, flexible expansion and dimming, which has brought about a new transformation in the LED driver IC and power supply industry. The application of intelligent dimming power supplies, especially in commercial lighting, is expected to increase rapidly.

[0004] In addition to these issues, most SCR power supplies have many common problems such as poor dimming effect, narrow dimming range, and easy flickering. Therefore, research on SCR dimming LED lighting products is very meaningful. Utility Model Content

[0005] To address the aforementioned technical problems, this utility model provides an LED SCR dimming flicker-free power supply, which can improve the dimming range of lamps, especially the flickering of lamps at low brightness.

[0006] This utility model is achieved using the following technical solution: A flicker-free LED SCR dimming power supply includes an input EMI circuit, a rectifier circuit, a first surge suppression circuit, a filter circuit, a second surge suppression circuit, a power conversion circuit, a PWM control circuit, a constant current control circuit, a phase detection circuit, an over / under voltage protection circuit, an output flicker-free circuit, and an LED load. The input EMI circuit is connected to the rectifier circuit. The positive output of the rectifier circuit is connected to the input of the first surge suppression circuit. The output of the first surge suppression circuit is connected to the input of the filter circuit. The output of the filter circuit is connected to the input of the second surge suppression circuit. The output of the second surge suppression circuit is connected to the input of the power conversion circuit. The output of the power conversion circuit is connected to the input of the flicker-free circuit. The output of the flicker-free circuit is connected to the LED load. The constant current circuit, the phase detection circuit, and the over / under voltage protection circuit detect the operating state of the power conversion circuit and transmit it to the PWM control circuit. After receiving the state information, the PWM control circuit adjusts the operating state of the power conversion circuit, forming a feedback closed loop.

[0007] The input EMI circuit consists of capacitor CX1 and common-mode inductor LF1. The rectifier circuit is a rectifier bridge BD1. The first surge suppression circuit consists of diode D1, capacitor EC1, resistor R1, and resistor R2, used to suppress low-frequency high-value voltages. The filter circuit is a π-type filter composed of capacitor C1, capacitor C6, and inductor L1. The second surge suppression circuit consists of varistor VR2, capacitor C2, and resistor R4, used to absorb voltage spikes. The rectifier circuit, filter circuit, first surge suppression circuit, and second surge suppression circuit share a common ground.

[0008] The power conversion circuit is an inductor energy storage and release circuit, including the primary coil of the transformer T1A, MOSFET Q1, gate resistor R9, gate resistor R10, gate-source resistor R11, source-drain capacitor C3, leakage inductance spike voltage absorption resistor R14, capacitor C4, and diode D5.

[0009] The frequency reduction circuit includes a filter component capacitor EC3, a resistor R15, a MOSFET Q2, a MOSFET Q3, a rectifier diode D6, a resistor R16, a Zener diode ZD1, a Zener diode ZD2, an energy storage capacitor EC4, and a filter common-mode inductor L2.

[0010] The PWM control circuit chip is powered by the bus voltage through the HV pin.

[0011] The PWM control circuit uses the BP3288 chip.

[0012] Compared with the prior art, the beneficial effects of this utility model are as follows: setting up a phase detection circuit enables the output current to be adjusted synchronously with the dimming angle, which can improve the dimming range and dimming compatibility of the lamp; setting up a flicker-reducing circuit enables the voltage of the LED load to be kept stable, thereby achieving the purpose of flicker reduction, especially improving the flickering of the lamp at low brightness. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0014] Figure 2 This is a circuit diagram of a flicker-free LED SCR dimming power supply component; Detailed Implementation

[0015] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0016] Example:

[0017] Please combine Figure 1-2 This embodiment of an LED SCR dimming flicker-free power supply includes an input EMI circuit, a rectifier circuit, a first surge suppression circuit, a filter circuit, a second surge suppression circuit, a power conversion circuit, a PWM control circuit, a constant current control circuit, a phase detection circuit, an over / under voltage protection circuit, an output flash de-frequency circuit, and an LED load. The input EMI circuit is connected to the rectifier circuit. The positive output of the rectifier circuit is connected to the input of the first surge suppression circuit. The output of the first surge suppression circuit is connected to the input of the filter circuit. The output of the filter circuit is connected to the input of the second surge suppression circuit. The output of the second surge suppression circuit is connected to the input of the power conversion circuit. The output of the power conversion circuit is connected to the input of the flash de-frequency circuit. The output of the flash de-frequency circuit is connected to the LED load. The constant current circuit, the phase detection circuit, and the over / under voltage protection circuit detect the operating state of the power conversion circuit and transmit it to the PWM control circuit. After receiving the state information, the PWM control circuit adjusts the operating state of the power conversion circuit to form a feedback closed loop.

[0018] The input EMI circuit consists of capacitor CX1 and common-mode inductor LF1. The rectifier circuit is a rectifier bridge BD1. The first surge suppression circuit consists of diode D1, capacitor EC1, resistor R1, and resistor R2, used to suppress low-frequency high-value voltages. The filter circuit is a π-type filter composed of capacitor C1, capacitor C6, and inductor L1, used to filter out high-frequency noise. The second surge suppression circuit consists of varistor VR2, capacitor C2, and resistor R4, used to absorb voltage spikes. The rectifier circuit, filter circuit, first surge suppression circuit, and second surge suppression circuit share a common ground.

[0019] The power conversion circuit is an inductor energy storage and release circuit, including the primary coil of the transformer T1A, MOSFET Q1, gate resistor R9, gate resistor R10, gate-source resistor R11, source-drain capacitor C3, leakage inductance spike voltage absorption resistor R14, capacitor C4, and diode D5.

[0020] The flicker-eliminating circuit includes a filter component, capacitor EC3, resistor R15, MOSFETs Q2 and Q3, rectifier diode D6, resistor R16, Zener diodes ZD1 and ZD2, energy storage capacitor EC4, and common-mode filter inductor L2. Its basic principle is that the LED load and the drain-source terminals of the MOSFETs are connected in series to the output voltage. Zener diode ZD2 maintains the gate-source voltage of the MOSFET at a fixed value Vgs, which is greater than the turn-on voltage Vth, and the source-drain voltage Vds is less than Vgs minus Vth. At this time, MOSFETs Q2 and Q3 operate in the variable resistance region. When the output voltage fluctuates, the drain-source voltages of MOSFETs Q2 and Q3 also increase or decrease accordingly, thereby stabilizing the voltage of the LED load and achieving flicker elimination.

[0021] The PWM control circuit chip is powered by the bus voltage through the HV pin. When the internal voltage of the chip reaches the chip turn-on threshold, the PWM control circuit chip starts to work.

[0022] The constant current circuit described herein has its PWM control circuit chip's CS terminal connected to the internal inverting input of a reference operational amplifier. The operational amplifier's positive output is the CS reference voltage. The operational amplifier's output error signal is automatically adjusted through internal compensation to achieve constant output current. The phase detection circuit described herein uses the internal Tonmax limit of the PWM control circuit chip when an external dimmer is connected, causing the output current to adjust synchronously with the dimming angle, improving the dimming range and dimming compatibility. The over / under voltage protection circuit described herein uses the voltage output from the transformer's secondary coil T1B, which is divided by resistors and then fed to the chip's over / under voltage protection signal differential sampling positive terminal OVP. VS is the chip's over voltage protection signal differential sampling negative terminal. Both are fed to the chip based on the over / under voltage control signal output from the internal comparator.

[0023] The PWM control circuit uses the BP3288 chip.

[0024] The 120-240V AC power enters the rectifier and filter circuit after passing through the EMI circuit. After passing through the dual surge suppression circuit, a stable AC power is obtained, which then enters the PWM control circuit. Pins 1 and 8 of the PWM control chip are connected to the differential input of the overvoltage detection circuit, pin 5 is connected to the rectified output voltage, and pin 3 is connected to the current sensing resistor. The differential output of pins 1 and 8 is multiplied by the voltage at pin 5 inside the chip to obtain the current value, which is then compared with the current at pin 3 to obtain the drive signal at pin 4, controlling the switching of the MOSFET. Therefore, the chip has overvoltage protection and PFC correction functions. The Tonmax resistor at pin 2 is grounded and detects the phase of the external SCR controller, changing the output current magnitude accordingly.

[0025] The rectified DC power enters the power conversion circuit and connects to the primary coil of transformer T1. The primary coil is connected in parallel with the LED load. Through the switching of the MOS, energy is periodically stored and released to power the LED load in the next stage. Therefore, the secondary coil can detect the magnitude of the output voltage, which enters pin 8 of the chip after being divided by a resistor.

[0026] Pin 4 of the primary coil of transformer T1 is connected to the drain of MOSFETs Q2 and Q3 in parallel. The source of MOSFETs Q2 and Q3 is connected to the LED load. A Zener diode ZD2 is connected in parallel between the gate and source of MOSFETs Q2 and Q3. The voltage of ZD2 keeps MOSFETs Q2 and Q3 in a variable resistance state. When MOSFET Q1 is turned off and the primary coil releases energy, the voltage across it is the output voltage. When the output voltage fluctuates, because MOSFETs Q2 and Q3 are in a variable resistance state, the voltage across them fluctuates with the output voltage, while the voltage across the LED load remains stable, thus eliminating LED flicker.

[0027] The above embodiments are merely preferred embodiments of this utility model and should not be construed as limiting the scope of protection of this utility model. Any non-substantial changes and substitutions made by those skilled in the art based on this utility model shall fall within the scope of protection claimed by this utility model.

Claims

1. An LED triac dimmable flicker-free power supply, characterized by, The input EMI circuit, rectifier circuit, first surge suppression circuit, filter circuit, second surge suppression circuit, power conversion circuit, PWM control circuit, constant current circuit, phase detection circuit, over-voltage protection circuit, output anti-flicker circuit, LED load, the input EMI circuit is connected with the rectifier circuit, the output positive of the rectifier circuit is connected with the input end of the first surge suppression circuit, the output end of the first surge suppression circuit is connected with the input end of the filter circuit, the output end of the filter circuit is connected with the input end of the second surge suppression circuit, the output end of the second surge suppression circuit is connected with the input end of the power conversion circuit, the output end of the power conversion circuit is connected with the input end of the anti-flicker circuit, the output end of the anti-flicker circuit is connected with the LED load, the constant current circuit, phase detection circuit, over-voltage protection circuit detect the working state of the power conversion circuit and transmit to the PWM control circuit, the PWM control circuit adjusts the working state of the power conversion circuit after receiving the state information, and forms a feedback closed loop.

2. A triac dimmable flicker-free power supply for LEDs as claimed in claim 1, characterized in that, The input EMI circuit is composed of a capacitor CX1 and a common mode inductor LF1, the rectifier circuit is a rectifier bridge BD1, the first surge suppression circuit is composed of a diode D1, a capacitor EC1, a resistor R1 and a resistor R2, which is used to suppress low-frequency high-voltage, the filter circuit is a π-type filter composed of a capacitor C1, a capacitor C6 and an inductor L1, the second surge suppression circuit is composed of a voltage-dependent resistor VR2, a capacitor C2 and a resistor R4, which is used to absorb sharp peak voltage, and the rectifier circuit, filter circuit, first surge suppression circuit and second surge suppression circuit are grounded.

3. A triac dimmable flicker-free LED power supply as defined in claim 1, characterized in that, The power conversion circuit is an inductor energy storage release circuit, which includes a transformer primary coil T1A, a MOS tube Q1, a gate resistor R9, a gate resistor R10, a gate-source resistor R11, a source-drain capacitor C3, a drain inductance sharp peak voltage absorption resistor R14, a capacitor C4 and a diode D5.

4. A triac dimmable flicker-free LED power supply as defined in claim 1, characterized in that, The anti-flicker circuit includes a filter component capacitor EC3, a resistor R15, a MOS tube Q2, a MOS tube Q3, a rectifier diode D6, a resistor R16, a voltage stabilizing diode ZD1, a voltage stabilizing diode ZD2, an energy storage capacitor EC4 and a filter common mode inductor L2.

5. A triac dimmable flicker-free LED power supply as defined in claim 1, wherein, The chip of the PWM control circuit is powered by the bus voltage through the HV pin.

6. A triac dimmable flicker-free LED power supply as defined in claim 1, characterized in that, The chip of the PWM control circuit adopts BP3288 model.

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