High-efficiency LED street lamp driver

Abstract

The high-efficiency LED street lamp driver comprises an EMI filtering unit, a power factor correction unit, a DC-DC conversion unit and an auxiliary power supply unit, the EMI filtering unit is electrically connected with a rectification filtering unit, the power factor correction unit is electrically connected with the rectification filtering unit, and the power factor correction unit is provided with a first power switch tube. The DC-DC conversion unit is electrically connected with the power factor correction unit, the DC-DC conversion unit converts the DC voltage output by the power factor correction unit into DC voltage suitable for LED driving, and the DC-DC conversion unit is provided with a second power switch tube; the EMI filtering unit effectively suppresses electromagnetic interference introduced by a power grid and interference feedback of a driver. And meanwhile, overcurrent and overvoltage protection elements are integrated, so that core components are prevented from being damaged. The power factor correction unit is matched, so that the input current changes in sine wave along with the voltage, the power factor is stable, the total harmonic distortion is reduced, and the power transmission line loss is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of LED power supply, in particular to a high-efficiency LED street lamp driver. BACKGROUND

[0002] LED lighting has the advantages of high luminous efficiency, long service life, high reliability and no pollution. In recent years, with the progress of technology, higher requirements are put forward for LED lighting, requiring high PF (Power Factor), no flicker, high efficiency, thereby reducing the harm to the human eye and improving the utilization rate of energy.

[0003] In the field of LED lighting, the traditional LED driving power supply mostly adopts the design of rectification plus capacitor filtering, the input current is in a pulse waveform, and the power factor is low; the forward voltage of the LED changes sensitively with temperature and current, and if the driving power supply cannot provide constant current output, it will cause the LED brightness to flicker, affecting the lighting effect of the LED. The output voltage of the rectification plus capacitor filtering scheme is high, the ripple current is large, and the average current is low, resulting in low LED driving efficiency, and the output current is greatly affected by the output voltage. SUMMARY

[0004] The purpose of the present application is to provide a high-efficiency LED street lamp driver to solve the problems raised in the background.

[0005] To achieve the above purpose, the present application provides the following technical scheme: a high-efficiency LED street lamp driver, comprising an EMI filter unit, the EMI filter unit is electrically connected with a rectification filter unit, the EMI filter unit suppresses electromagnetic interference introduced from the power grid, while avoiding the interference of the driver itself feedback to the power grid, and the rectification filter unit converts the alternating current of the power grid into direct current;

[0006] A power factor correction unit, the power factor correction unit is electrically connected with the rectification filter unit, the power factor correction unit makes the input current follow the change of the input voltage, realizes power factor correction, significantly improves the power factor, reduces the harmonic pollution of the power grid, and reduces the power transmission loss;

[0007] The power factor correction unit is provided with a first power switch tube, and the first power switch tube adjusts energy transmission when switched on and off;

[0008] A DC-DC conversion unit, the DC-DC conversion unit is electrically connected with the power factor correction unit, the DC-DC conversion unit converts the direct current voltage output by the power factor correction unit into a direct current voltage suitable for LED driving, the DC-DC conversion unit is provided with a second power switch tube, the DC-DC conversion unit controls the switching frequency and duty cycle of the second power switch tube, accurately outputs the driving voltage suitable for the LED, and ensures the stability of LED light emission;

[0009] An auxiliary power supply unit is electrically connected to a rectifier and filter unit, a DC-DC converter unit, and a power factor correction unit. The auxiliary power supply unit supplies power to the LED load, thereby improving the overall efficiency and stability of the driver.

[0010] Furthermore, the EMI filter unit is equipped with overcurrent protection and overvoltage protection components to protect the driver. It can quickly cut off the circuit or clamp overvoltage when abnormal conditions such as overcurrent or sudden rise in mains voltage occur in the circuit, preventing the circuit from burning out.

[0011] Furthermore, the filtering section of the rectifier filter unit includes several inductors and capacitors to reduce voltage ripple in the circuit, making the voltage output to the power factor correction unit more stable. This not only reduces the impact of ripple on power correction accuracy but also reduces the switching losses of power devices in subsequent circuits, indirectly improving the efficiency of the entire driver.

[0012] Furthermore, an auxiliary winding is electrically connected between the power factor correction unit and the rectifier filter unit. The auxiliary winding provides the power factor correction unit with operating power and feedback signals, optimizes the power factor correction effect, and ensures that the power factor remains stable at a high level.

[0013] Furthermore, the power factor correction unit includes several inductors and diodes. The inductors store and release energy, realizing energy conversion and transfer during the turn-on and turn-off process of the first switch. The diodes enable unidirectional current flow. The two work together to ensure that the power factor correction process is efficient and stable.

[0014] Furthermore, the DC-DC conversion unit is equipped with a current sampling module, which detects the operating current of the LED and feeds it back to the DC-DC conversion unit to form a closed-loop control. The control chip dynamically adjusts the duty cycle of the second power switch according to the feedback signal to ensure that the LED current is constant, avoid brightness flicker or LED overheating damage caused by current fluctuations, and ensure the stability and consistency of LED light emission.

[0015] Furthermore, the control chips for the power factor correction unit and the DC-DC conversion unit are BP2628 and BP2879, respectively.

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] (1) The EMI filter unit acts as a front-end barrier, effectively suppressing electromagnetic interference introduced by the power grid and interference feedback from the driver itself; it also integrates overcurrent and overvoltage protection components, which can quickly respond to abnormalities such as sudden rise in power grid voltage and circuit overcurrent, and avoid damage to core components. In conjunction with the power factor correction unit, the input current follows the voltage in a sinusoidal wave, the power factor is stable, the total harmonic distortion is greatly reduced, the transmission line loss is reduced, and the driving efficiency of LEDs is high.

[0018] (2) The rectifier and filter unit efficiently filters out the voltage ripple after rectification through a combination of multiple inductors and capacitors, providing a stable DC input for subsequent circuits and reducing the impact of ripple on power correction accuracy; the power factor correction unit, with the help of inductor energy storage and release and in coordination with the first power switch, achieves efficient energy conversion and reduces intermediate losses; the DC-DC conversion unit uses high-frequency switching technology to control the frequency and duty cycle of the second power switch, combined with a low-loss topology design, resulting in high overall conversion efficiency. This improves the energy utilization efficiency of LED streetlights.

[0019] (3) The DC-DC conversion unit is equipped with a current sampling module to detect the LED working current in real time and form a closed-loop control to ensure the accuracy of the output current and avoid brightness flicker caused by current fluctuations. The constant current output can prevent the LED from decaying due to overcurrent and overheating. Combined with the over-temperature protection function of the BP2879 chip, it can effectively extend the life of the LED. Attached Figure Description

[0020] Figure 1 This is an overall diagram of the driving circuit of the present invention;

[0021] Figure 2 This is a circuit diagram of the rectifier and filter unit of the present invention;

[0022] Figure 3 This is a circuit diagram of the EMI filter unit of the present invention;

[0023] Figure 4 This is a circuit diagram of the power factor correction unit of the present invention;

[0024] Figure 5 This is a circuit diagram of the DC-DC conversion unit of the present invention;

[0025] Figure 6 This is a circuit diagram of the auxiliary power supply unit of the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example:

[0028] Please see Figures 1-6 This invention provides a technical solution: a high-efficiency LED street light driver, including an EMI filter unit, wherein the EMI filter unit is electrically connected to a rectifier filter unit. The EMI filter unit suppresses electromagnetic interference introduced from the power grid, and the rectifier filter unit converts the AC power from the power grid into DC power. Inductors L1 and L2, capacitors C3, C4, C5, etc. constitute a filter circuit to perform preliminary filtering on the rectified DC voltage, reduce voltage ripple, and provide a more stable DC input for subsequent circuits.

[0029] The L and N terminals of the EMI filter unit are connected to the AC power supply, such as... Figure 2 As shown, CX1, CY2, CY1, common mode inductor TX5, etc. constitute an EMI filtering unit to prevent interference generated by the driver itself from being fed back to the power grid, ensuring that the equipment complies with electromagnetic compatibility (EMC) standards.

[0030] The power factor correction unit is electrically connected to the rectifier and filter unit. The power factor correction unit makes the input current follow the input voltage change to achieve power factor correction. The power factor correction unit has a first power switch (Q1). When the first power switch switches on and off, it adjusts the energy transfer. The power factor correction unit improves the input power factor and makes the input current waveform as close as possible to a sine wave and in phase with the input voltage, thereby reducing harmonic pollution to the power grid and improving power utilization.

[0031] The DC-DC conversion unit is electrically connected to the power factor correction unit. The DC-DC conversion unit converts the DC voltage output by the power factor correction unit into a DC voltage suitable for LED driving. The DC-DC conversion unit has a second power switch (Q6) and controls the switching frequency and duty cycle of the second power switch.

[0032] When the second power switch is turned on, the power supply provides power to the LED load through the second power switch and the inductor, and stores the energy in the inductor; when the second power switch is turned off, the inductor releases energy through the diode (D9, model LL4148) and continues to supply power to the LED, thereby realizing constant current or constant voltage drive for the LED;

[0033] An auxiliary power supply unit is electrically connected to a rectifier and filter unit, a DC-DC converter unit, and a power factor correction unit. The auxiliary power supply unit supplies power to the LED load to ensure the normal operation of the control circuit.

[0034] In this embodiment, as Figure 2 As shown, the EMI filter unit has overcurrent protection and overvoltage protection components to protect the driver. The parameters of the overcurrent protection component (F1) are 6.3A / 250V, and the recommended overvoltage protection component (VR1) is 250V. When the mains voltage is too high, the varistor breaks down, clamping the overvoltage and protecting the subsequent circuits.

[0035] In this embodiment, as Figure 3 As shown, the filtering section of the rectifier-filter unit includes several inductors and capacitors to perform preliminary filtering on the rectified DC voltage, reduce voltage ripple in the circuit, and provide a more stable DC input for subsequent circuits.

[0036] In this embodiment, as Figure 4 As shown, the power factor correction unit and the rectifier filter unit are electrically connected by an auxiliary winding (T1A). The auxiliary winding provides the power factor correction unit with operating power and feedback signals. On the one hand, it can provide a stable operating power supply for the control chip (U1) of the power factor correction unit without the need to introduce an additional independent power supply circuit, thus simplifying the circuit structure. On the other hand, it can collect the voltage or current signal after rectification and filtering in real time as feedback, so that U1 can more accurately adjust the switching state of the first power switch. The auxiliary winding is electrically connected to the ZCD pin of U1.

[0037] In this embodiment, as Figure 4 As shown, the power factor correction unit includes several inductors and diodes. The inductors store and release energy, realizing energy conversion and transfer during the conduction and turn-off of the first switch. The diodes enable unidirectional current flow. The power factor correction unit also includes resistors (RS1-5) for sampling signals such as input current or output voltage. The network of capacitors and resistors is used for signal filtering and feedback, transmitting relevant signals to U1 to form closed-loop control.

[0038] In this embodiment, as Figure 5 As shown, the DC-DC conversion unit is equipped with a current sampling module (RS8 - RS12, etc.). The current sampling module detects the operating current of the LED and feeds it back to the DC-DC conversion unit. U2 performs feedback control based on the sampled current signal to ensure that the LED operates under a constant current, thus guaranteeing the LED's brightness and lifespan. Simultaneously, the protection circuit composed of resistors and capacitors in the circuit promptly cuts off or adjusts the output in case of abnormal conditions, protecting the LED and the driver.

[0039] In this embodiment, as Figure 1 As shown, the control chips for the power factor correction unit and the DC-DC conversion unit are BP2628 and BP2879, respectively. BP2628 features high-precision power factor correction, achieving high power factor and low total harmonic distortion under wide voltage input conditions. BP2879 supports high-precision constant current output, has comprehensive over-temperature and over-current protection functions, and exhibits low switching losses. Using both together fully leverages the integrated advantages of the chips, simplifies peripheral circuit design, and improves the overall efficiency and stability of the driver.

[0040] 1. Mains input and EMI filtering protection stage

[0041] The AC mains power (220V) is connected to the EMI filtering unit through the L and N terminals. It first passes through a 6.3A / 250V fuse F1 (overcurrent protection) and a 250V varistor VR1 (overvoltage protection), forming the first safety barrier. When the circuit experiences overcurrent, F1 blows; when the voltage surges, VR1 breaks down to clamp the circuit, preventing damage to subsequent circuits. Subsequently, capacitors CX1, CY1, and CY2, along with the common-mode inductor TX5, form a filtering network. This network suppresses electromagnetic interference (EMI) introduced from the mains and prevents interference generated by the driver itself from feeding back to the mains, ensuring the device complies with EMC standards and providing AC input for subsequent circuits.

[0042] 2. Rectification and Pre-filtering Stage

[0043] The AC power, after EMI treatment, enters the rectifier and filter unit, where it is converted into pulsating DC power by rectifier bridges (such as DB1 and DB2). Subsequently, the filter circuit composed of inductors L1 and L2 and capacitors C3, C4, and C5 performs preliminary smoothing of the pulsating DC power: the inductors impede sudden current changes, and the capacitors absorb voltage ripple, together reducing the AC component in the DC voltage and outputting a stable DC voltage, providing a stable input for the power factor correction unit.

[0044] 3. Power Factor Correction Stage

[0045] The rectified and filtered DC voltage is input to the power factor correction unit. The core control chip U1 obtains the operating power and feedback signal through the auxiliary winding T1A, forming a closed-loop control. Its operation is divided into two stages:

[0046] During the switching transistor conduction period: U1 drives the first power switch Q1 to conduct, and the input voltage charges the inductor in the unit to store energy. At this time, the inductor current rises linearly, and U1 samples the input current and voltage signals through resistors RS1-RS5.

[0047] Switch turn-off period: U1 turns off Q1 according to the feedback signal, the inductor releases the stored energy, and it is transferred to the subsequent circuit through the diode (such as D3, D4). The unidirectional conductivity of the diode ensures that the current flows only in the forward direction.

[0048] 4. DC-DC Conversion and LED Driving Stage

[0049] The high-voltage DC output from the power factor correction unit enters the DC-DC conversion unit, and the operating state of the second power switch Q6 is regulated by the control chip U2.

[0050] When Q6 is turned on: the power supply supplies power to the LED load through Q6 and the energy storage inductor, while the inductor stores energy;

[0051] When Q6 is off: the inductor releases energy through diode D9 to continuously power the LED and ensure continuous current.

[0052] The current sampling modules RS8-RS12 monitor the LED's operating current in real time and feed the signal back to U2. U2 then adjusts the duty cycle of Q6 to achieve a constant current output. Simultaneously, a protection circuit composed of resistors and capacitors triggers U2 to cut off the output in case of overcurrent, overtemperature, or other abnormalities, ensuring the safety of the LED and driver. Finally, a stable current drives the LED to emit light through the LED+ and LED- terminals.

[0053] 5. Auxiliary power supply collaborative operation stage

[0054] The auxiliary power supply unit draws power from the rectified and filtered DC bus or the DC-DC conversion unit, and converts it into low-voltage DC power through components such as a transformer (e.g., TX4) to provide stable operating voltages for U1 and U2. This design avoids functional failure of U1 and U2 due to unstable power supply, ensures continuous stability of power factor correction and DC-DC conversion, simplifies the circuit structure, and improves overall reliability.

[0055] In summary, the entire driver achieves efficient, stable, and reliable driving from mains power to LEDs through five levels of synergy: EMI filtering for interference suppression, rectification and filtering for input stabilization, PFC correction for efficiency improvement, DC-DC conversion for output control, and auxiliary power supply for stability.

[0056] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-efficiency LED street light driver, characterized in that, include: An EMI filter unit is electrically connected to a rectifier filter unit. The EMI filter unit suppresses electromagnetic interference introduced from the power grid, and the rectifier filter unit converts the AC power from the power grid into DC power. A power factor correction unit is electrically connected to a rectifier and filter unit. The power factor correction unit makes the input current follow the input voltage change to achieve power factor correction. The power factor correction unit has a first power switch, which adjusts energy transmission when it switches on and off. The DC-DC conversion unit is electrically connected to the power factor correction unit. The DC-DC conversion unit converts the DC voltage output by the power factor correction unit into a DC voltage suitable for LED driving. The DC-DC conversion unit has a second power switch, and the DC-DC conversion unit controls the switching frequency and duty cycle of the second power switch. An auxiliary power supply unit is electrically connected to a rectifier and filter unit, a DC-DC converter unit, and a power factor correction unit, and supplies power to the LED load.

2. The high-efficiency LED street light driver according to claim 1, characterized in that: The EMI filter unit is equipped with overcurrent protection and overvoltage protection components to protect the driver.

3. The high-efficiency LED street light driver according to claim 1, characterized in that: The filtering section of the rectifier filter unit includes several inductors and capacitors to reduce voltage ripple in the circuit.

4. The high-efficiency LED street light driver according to claim 1, characterized in that: An auxiliary winding is electrically connected between the power factor correction unit and the rectifier filter unit. The auxiliary winding provides the power factor correction unit with operating power and feedback signals.

5. A high-efficiency LED street light driver according to claim 1, characterized in that: The power factor correction unit includes several inductors and diodes. The inductors store and release energy, realizing energy conversion and transfer during the turn-on and turn-off process of the first switch, while the diodes enable unidirectional current flow.

6. A high-efficiency LED street light driver according to claim 1, characterized in that: The DC-DC conversion unit is equipped with a current sampling module, which detects the operating current of the LED and feeds it back to the DC-DC conversion unit.

7. A high-efficiency LED street light driver according to claim 1, characterized in that: The control chips for the power factor correction unit and the DC-DC conversion unit are BP2628 and BP2879, respectively.

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