Improve HB LED Lighting Efficiency Through Primary End Adjustment

High brightness light emitting diode (HBLED) is a kind of high-power and high brightness LED. It has longer service life, smaller size and flexible design. It has become an alternative to traditional incandescent lamps and halogen lamps.

High brightness LED Driver with primary end adjustment controller

As mentioned above, LED lighting has many advantages, but without appropriate voltage and accurate current, the life of these devices will not only shorten, but also increase their power consumption and heat consumption, resulting in irreparable damage to the LED. Therefore, the current of LED is very important for lighting. For this reason, PSR with excellent constant current technology is both important and beneficial to the life of HB-LED.

In the traditional LED control circuit, the off-line constant output current LED driver can be realized by using the isolated flyback converter and the secondary end circuit to adjust the output current, as shown in Fig. 1. This scheme can provide accurate current control, but the disadvantage is that the number of devices is large, which means that larger on-board space, higher cost and lower reliability are required. At the same time, the inductive resistance ro will also increase the power consumption and reduce the efficiency of constant current regulating power supply. Recently, the efficiency and energy saving requirements of LED drivers have become more and more important. At the same time, LED applications also need smaller size, so the traditional circuits no longer meet the relevant requirements. This paper will introduce a primary end control method which can reduce the number of devices and improve efficiency.

Primary end regulation (PSR) technology is the best solution to minimize the cost of offline LED driver. It can provide accurate current control without using optocouplers at the secondary end. The basic principle of PSR is to use an innovative method to detect the output information by replacing the optocoupler at the secondary end with an auxiliary coil, as shown in Figure 2. Fig. 2 shows the basic circuit diagram and main working waveforms of a flyback converter using a primary end controller.

When the PSR controller turns on the MOSFET, the transformer current IP will increase linearly from zero to ipk, as shown in equation (1). During conduction, energy is stored in the transformer. When the MOSFET is off (toff), the energy stored in the transformer is transmitted to the output of the power converter through the output rectifier. During this period, the output voltage Vo and the forward voltage VF of the diode are reflected to the auxiliary coil naux, and the voltage on the auxiliary coil naux can be represented by equation (2). At this time, a proprietary sampling technology can be used to sample the reflected voltage. Since the forward voltage of the output rectifier becomes constant, the relevant output voltage information can be obtained. Then, the sampled voltage is compared with the accurate reference voltage to form a voltage loop, so as to determine the on time of MOSFET and accurately adjust the constant output voltage.

In this formula, LP is the inductance of the primary coil of the transformer; Vin is the input voltage of the transformer; Ton is the on time of MOSFET; Naux / NS is the turn ratio of auxiliary coil to secondary output coil; VO is the output voltage; VF is the forward voltage of the output rectifier.

This sampling scheme also doubles the discharge time (TDIS) of the transformer. As shown in Fig. 2, the output current IO is related to the secondary terminal current of the transformer. IO can also be obtained by ipk and TDIS, as shown in equation (3). The PSR controller uses this result to determine the on time of the MOSFET and adjust the constant output current. Sense resistor RSENSE is used to adjust the value of output current.

Here, TS is the switching cycle of the PSR controller; NP / NS is the turn ratio of primary coil and secondary output coil; RSENSE is the sensing resistance, which converts the switching current of the transformer into voltage VCs.

Using PSR controller to realize HB LED driver

Here, an HB LED driver is used to drive three HB LEDs in series, and the output specification is 12V / 0.35A. If the PSR controller fsez1016a integrating a PSR controller and a 600V / 1A MOSFET is adopted, it will help to reduce the number of external components, reduce PCB area, reduce power consumption and signal noise on MOSFET Driver circuit, and reduce interference. The proprietary green mode function can provide non conduction time modulation under light load and no load conditions to linearly reduce PWM frequency and minimize standby power consumption, so as to easily meet the requirements of most green specifications. In addition, its built-in frequency buffeting function further improves EMI performance.

Experiments show that with this method, the regulation accuracy of constant current (CC) can reach 1.8%, and the fold back voltage is 4V (as shown in Figure 3), which is suitable for a large VDD range, and the CC capacity is related to the output voltage. The efficiency is 77.66% at 115VAC input, 77.40% at 230VAC input, and the maximum power at no-load is 0.115w. Thus, a lighting solution with the least external components and the lowest cost can be obtained by using fsez1016a.

epilogue

In order to improve the capability of HBLED, the control circuit must use constant current to realize LED driving. The patented technology of "primary end regulation" (PSR) introduced in this paper can accurately adjust the voltage and current of LED driver in the primary end of transformer only through PSR controller, without secondary end feedback circuit, so as to realize products with smaller size, longer service life and more environmental protection. Experiments show that PSR can provide 1.8% constant current (CC) regulation accuracy. The efficiency is 77.66% at 115VAC input, 77.40% at 230VAC input, and the maximum power at no-load is 0.115w. This PSR technology is the best solution to reduce the cost of offline LED driver.

get in touch with us
مقالات مقترحة
What Is the Principle of Solar LED Lighting System
Solar energy is the most direct, universal and clean energy on the earth. As a huge amount of renewable energy, the radiant energy reaching the earth's surface every day is about 250 million barrels of oil, which can be said to be inexhaustible. Almost all the spectra of LEDs are concentrated in the visible frequency band, so the luminous efficiency is high. Most people believe that energy-saving lamps can save 4 / 5 energy, which is a great innovation, but LEDs can save 1 / 4 energy than energy-saving lamps, which is a greater reform of solid-state light sources.Solar LED lighting integrates the advantages of solar energy and led.1. Brief introduction and working principle of solar LED lighting systemThe system is composed of solar cell module (including support), LED lamp cap, control box (with controller and battery) and lamp pole; The solar panel has a light efficiency of 127wp / m2, which is very beneficial to the wind resistance design of the system; In the lamp cap part, 1W white LED and 1W yellow LED are integrated on the printed circuit board and arranged into a dot matrix with a certain spacing as the plane light source.The control box is made of stainless steel, beautiful and durable; Maintenance free lead-acid battery and charge discharge controller are placed in the control box. The valve regulated sealed lead-acid battery is selected for the system. Because it has little maintenance, it is also called "maintenance free battery", which is conducive to the reduction of system maintenance cost; the design of charge discharge controller takes into account the complete functions (with optical control, time control, overcharge protection, over discharge protection and reverse connection protection) and cost control, so as to achieve high cost performance.The working principle of the system is simple. The solar cell made by using the principle of photovoltaic effect receives solar radiation energy and converts it into electric energy output during the day. It is stored in the battery through the charge discharge controller. At night, when the illuminance gradually decreases to about 101ux and the open circuit voltage of the solar panel is about 4.5V, the charge discharge controller acts after detecting this voltage value to store electricity The cell discharges the lamp cap. After the battery is discharged for 8.5 hours, the charge discharge controller acts and the battery discharge ends. The main function of the charge discharge controller is to protect the battery.2. Design idea of solar LED lighting system2.1 solar cell module selectionDesign requirements: in Guangzhou, the load input voltage is 24V, the power consumption is 34.5w, the working hours are 8.5H per day, and the continuous rainy days are guaranteed for 7 days.(1) the average annual radiation in Guangzhou in recent 20 years is 107.7kcal/cm2. After simple calculation, the peak sunshine hours in Guangzhou are about 3.424h;(2) daily load power consumption = 12.2ah⑶ total charging current of required solar modules = 1.05 × twelve point two × ÷(3.424 × 0.85)=5.9AHere, the design minimum number of days between two consecutive rainy days is 20 days, 1.05 is the comprehensive loss coefficient of solar cell module system, and 0.85 is the charging efficiency of battery.(4) minimum total power of solar modules = 17.2 × 5.c=102WStandard battery modules with peak output power of 110wp and single 55wp shall be selected to ensure the normal operation of street lamp system in most cases of a year.2.2 battery selectionThe calculation of battery design capacity is simpler than the peak wattage of solar modules.According to the above calculation, the daily power consumption of load is 12.2ah. When the battery is full, it can work continuously for 7 cloudy and rainy days, plus the work in the first night, the battery capacity is:twelve point two × (7 1) = 97.6 (ah), two 12V100AH batteries can meet the requirements.2.3 solar cell module support design2.3.1 inclination designIn order to make the solar cell module receive as much solar radiation as possible in a year, we should choose an optimal inclination angle for the solar cell module.As for the discussion on the optimal inclination of solar cell module, the street lamp is used in Guangzhou, and the inclination of solar cell module support is 16 degrees.2.3.2 wind resistance design of solar LED lighting systemIn the solar street lamp system, a structural problem that needs to be paid great attention to is the wind resistance design. The wind resistance design is mainly divided into two parts, one is the wind resistance design of the battery module support, and the other is the wind resistance design of the lamp pole. The following analysis is made according to the above two parts.(1) wind resistance design of solar cell module supportAccording to the technical parameter data of the battery module manufacturer, the upwind pressure that the solar cell module can withstand is 2700pa. If the wind resistance coefficient is selected as 27m / S (equivalent to level 10 typhoon) According to the non viscous hydrodynamics, the wind pressure borne by the battery module is only 365pa. Therefore, the module itself can withstand the wind speed of 27m / s without damage. Therefore, the key to be considered in the design is the connection between the battery module support and the lamp pole.In the design of this set of street lamp system, the connection between the battery module support and the lamp pole is designed to be fixed and connected with a bolt rod.⑵ wind resistance design of street lamp poleThe parameters of street lamps are as follows:Inclination angle of battery board a = 16 °, lamp pole height = 5mDesign and select the weld width at the bottom of the lamp post δ= 4mm pole bottom od = 168mmThe surface where the weld is located is the failure surface of the lamp pole. The distance between the calculation point P of the resistance moment w of the failure surface of the lamp pole and the action line of the battery plate action load f on the lamp pole is PQ = [5000 (168 6) / tan16 °] × Sin16 ° = 1545mm = 1.545m. Therefore, the action moment of wind load on the failure surface of lamp pole M = F × 1.545。According to the design maximum allowable wind speed of 27m / s, 2 × The basic load of 30W double head solar street lamp panel is 730n. Considering the safety factor of 1.3, f = 1.3 × 730=949N。So, M = F × 1.545=949 × 1.545=1466N.m。According to mathematical derivation, the resistance moment of circular failure surface w = π × (3r2 δ 3r δ 2 δ 3)。Where R is the inner diameter of the ring, δ Is the ring width.Resistance moment of failure surface w = π × (3r2 δ 3r δ 2 δ 3)=π × (3 × eight hundred and forty-two × 43 × eighty-four × 4243)=88768mm3=88.768 × 10-6m3Stress caused by action moment of wind load on failure surface = m / w = 1466 / (88.768 × 10-6)=16.5 × 106pA=16.5MpA《215MpA215mpa is the bending strength of Q235 steel.Therefore, the weld width selected in the design meets the requirements. As long as the welding quality can be guaranteed, the wind resistance of the lamp post is no problem.2.4 solar LED lighting system controllerThe main function of solar charge discharge controller is to protect the battery. The basic functions must include overcharge protection, over discharge protection, optical control, time control and anti reverse connection.The general parameters of battery anti overcharge and over discharge protection voltage are shown in Table 1. When the battery voltage reaches the set value, the state of the circuit will be changed.In the selection of devices, at present, there are single-chip microcomputer and comparator. There are many schemes, each with its own characteristics and advantages. The corresponding scheme should be selected according to the demand characteristics of the customer group, which will not be described in detail here.2.5 surface treatment of solar LED lighting systemThis series of products adopt new electrostatic coating technology, mainly FP professional building materials coating, which can meet the requirements of customers for the coordination of product surface color and environment. At the same time, the products have high self-cleaning, strong corrosion resistance and aging resistance, and are suitable for any climatic environment. The processing process design is coating on the basis of hot-dip galvanizing, which greatly improves the product performance and reaches the most stringent aama2605.2005 Other indicators have met or exceeded the relevant requirements of GB.3. ConclusionThe overall design basically considers all links; the peak wattage selection design and battery capacity selection design of photovoltaic modules adopt the most common design method at present, and the design idea is more scientific; the wind resistance design is analyzed from the two parts of battery module support and lamp pole, and the analysis ratio is more comprehensive; the surface treatment adopts the most advanced technology; the overall structure of street lamps is simple and beautiful; The actual operation shows that the matching between each link is good.At present, the initial investment of solar LED lighting is still a major problem perplexing us. However, the light efficiency of solar cells is gradually increasing, and the price will gradually decrease. Similarly, the light efficiency of LED in the market is rapidly increasing, but the price is decreasing. Compared with the renewable, clean and pollution-free of solar energy and the environmental protection and energy saving of LED, conventional fossil energy is becoming more and more tense, and Therefore, solar LED lighting, as an emerging outdoor lighting, will show us infinite vitality and broad prospects.
Analysis of Three Reasons Why LED Lights still Emit Weak Light After Power Failure
Domestic LED Lighting Lamp Patent Status and Top Ten Applications
Let's Talk About the Application of Thermal Conductive Silica Gel in LED Lighting Industry
7 Tips to Help You Sell Your Farm Fresh Eggs for More Money
Need Help Finding Kitchen Items and Sofa?
Can I Heat an Outside Chicken Coop with an Underground Heating System?
How Can I Get My Foundation Brush Clean?
My Boyfriend Wants to Get Married? We Known Each Other for a Year?
My Mom Won't Let Me Go to School Tomorrow?
related searches
What Is the Principle of Solar LED Lighting System
Analysis of Three Reasons Why LED Lights still Emit Weak Light After Power Failure
Domestic LED Lighting Lamp Patent Status and Top Ten Applications
Let's Talk About the Application of Thermal Conductive Silica Gel in LED Lighting Industry
7 Tips to Help You Sell Your Farm Fresh Eggs for More Money
Need Help Finding Kitchen Items and Sofa?
Can I Heat an Outside Chicken Coop with an Underground Heating System?
How Can I Get My Foundation Brush Clean?
My Boyfriend Wants to Get Married? We Known Each Other for a Year?