Archives for October 2015

Advanced buying guide for LED driver & power supply. Just as Laptops need AC adapter, fluorescent demand ballast, LED lights & displays require suitable power supply as well. What is an LED driver? LED driver is know as LED power supply, which is the power source for an LED system. This guide of LED drivers will cover constant voltage or constant current led driver, dimming technology for led power supply, quality, control of led driver, and etc. The article is focusing on the LED industry.

 

The definitive guide of LED driver will be covering below table of contents(Almost complete one)

• Chapter #1 Types of power supplies
  Go to Chapter #1
• Chapter #2 Constant current or constant voltage led driver? Which is better ?
  Go to Chapter #2
• Chapter #3 Which power supply wattage do I need for LED light?
  Go to Chapter #3
• Chapter #4 Input voltage & Output voltage
  Go to Chapter #4
• Chapter #5 Dimming function (Dimmable LED driver)
  Go to Chapter #5
• Chapter #6 Waterproof or non-waterproof ?
  Go to Chapter #6
• Chapter #7 What is power quality of led driver?
  Go to Chapter #7
• Chapter #8 The future market of led driver
  Go to Chapter #8

 

 

Chapter #1 Types of power supplies

Chapter #1 Types of power supplies

LED driver has two types: constant voltageled driver and constant current led driver, depending on whether they regulate output to provide a constant voltage or current to the LEDs. Constant voltage led driver can be called voltage converter or ac to dc transformer, due to it covert the AC high voltage to DC low voltage, which normally has 5v power supply,12v power supply, 24v power supply, 36v power supply and 48v power supply (variable dc power supply).

Ac to dc converter: LED driver is a type of ac dc power, LEDs require a device that can transform incoming AC power to the proper DC voltage, and regulate the current flowing through the LED during operation. The LED driver & power supply converts 230V (or other voltage 110V) AC power to low-voltage DC power required by the LEDs, and protects the LEDs from line-voltage fluctuations.

There has some types of power supplies can be used for both traditional lights and LED lights, such as the switching power supply ( also known as switching-mode power supply, switch mode power supply, SMPS, or switcher) is an electronics power supply that incorporates a switching regulator to convert electrical power efficiently, which normally used for led strip lights today.

LED driver is the most important part for any LED system. You probably faced the situation that led driver power supply was broken but the LED was still good. As the rapid growing of led light during these years, there has many led driver manufacturers appear in the market, the quality and price is vary, how to find the best power supply for your LED lights among the different led drivers? Do you know the difference of constant current and constant voltage led driver or the information of wattage, power factor(PF), power factor correction (PFC), power efficiency, IP rate, housing shell,RoHS materials,electronic components,full load burn-in test,approval protection(over current, over load,short circuit and over temperature protection) ?

 

Chapter #2 Constant current or constant voltage led driver? Which is better?

Constant current or constant voltage led driver? Which is better?

Typically, LEDs are operated (or “Driven”) such that their (average) current is constant (Constant Current), power electronics components (led driver ICs, transformers. etc), are used to create power supply circuits which convert AC voltage into regulated LED constant (average) current.
A constant current power supply varies the voltage across an electronic circuit allowing the device to maintain a constant electric current. This thus ensures that, no matter the variation in voltage, the current delivered to LEDs does not change. In contrast to constant current led power supplies, constant voltage drivers are designed to operate with LED modules requiring a fixed voltage (ac to dc power supply), typically 12 or 24V DC. Modules are connected in parallel across the driver’s output power.

Advantages of using the constant current power supply: More consistent brightness and less light decay due to more stable and reliable output current for driving LEDs, as a result, it is able to have longer lifespan than the constant voltage led driver.

Constant voltage power supply: It is easier to design and develop with engineers and technicians, the cost is lower and the selling price is cheaper.

The constant voltage power supply is usually considered as not so good. During the working with LED lights, there might have the excessive forward current, which will result in extra heat generation and a significant reduction in LED lifespan. Therefore, a constant current source is the preferred method to drive one LED. In fact, LEDs are considered constant current driven devices.

According to the above information, does it mean constant voltage led driver is useless?

The answer is no, at present, constant voltage led driver is used a lot for led strip lights. Such as 12 volt power supply and 24 volt power supply.
Constant voltage led drivers are best suited to applications where the LED load is not known and the designer needs flexibility regarding the number of modules to be connected to the power supply. As constant-voltage LED modules are added to the load, driver current will increase to the maximum level. Typical applications include sign and track lighting.

Constant current led drivers (350 mA, 700 mA or etc.) are matched with constant-current LED modules, which are they connected in series or parallel. They provide higher efficiency, relatively easy dimming, longer expected life and greater control of brightness consistency across different LEDs in the same application. As a result, constant-current drivers are used in the large majority of LED products manufactured for general lighting applications. Many configurations are available to satisfy various applications.

Full collection of constant current and constant voltage led drivers with quality and competitive prices for your reference, 12 volt, 24 volt, 300mA 350mA 450mA 600mA 700mA 900mA and etc. Please contact us.

Chapter #3 Which power supply wattage do I need for LED light?

Which power supply wattage do I need for LED light?

Let us me ask you one question firstly: If the total power of led strip light is 100w, which power supply wattage do I need to drive the led strip light?

The answer is: 100w + power consumption of led driver.

How to know the power consumption of led driver? You need know the power efficiency (Performance per watt) of led driver (We’ve mentioned the relative information of “ Total Power Consumption” in the post of 5 tips to buy led strip lights)

 

 

If the power efficiency of led driver is 90%, the maximum power of 100w led driver supply 90w for led light, thus, it is not enough for 100w led strip light.

Now, you know how to count the enough power for your led light. You might ask, is high-efficiency led driver better? Yes!
There are several benefits to use high-efficiency LED drivers. The first thing is saving more energy, low the cost, (according to above calculation method for the power of led driver). In some applications, the cost saving can be more significant if taken into account the losses in the utility line and the reduced energy consumption of the air conditioning system (if the lamp is used indoor Energy savings in high efficiency drivers can be quite significant over the life of the driver.

In addition, the lower temperatures associated with higher efficiency drivers can significantly improve product life and MTBF. The power dissipated in a 90% efficient driver is less than half that dissipated in an 80% efficient driver. Doubling the heat in the lower efficiency driver significantly increases component temperatures. The life of the electrolytic capacitors in the driver decrease by about 50% with each 10 degree C increase in temperature. Therefore, higher efficiency drivers can easily have a 2-4 times longer projected life. As LED service life continues to improve, driver failure (rather than lumen depreciation) may be seen in the field as a lighting product end-of-life failure. LED drivers are designed with service-life ratings ranging from 50,000 to 100,000 hours, on par with the life expectancy of a majority of LEDs. These ratings are highly dependent on ambient temperature; the luminaire design and application characteristics (such as the installation space for heat dissipation, the working time of each day) can significantly affect actual life. When selecting a product, the temperature range of the driver should be evaluated and appropriately matched to the application.

Reliability is also a function of temperature and lowering temperature increases the reliability of all components in the driver. We adopt high quality electronic components from brand suppliers to ensure the long run of LED drivers.

From above information, you’ve learnt the suitable power for your led light and led driver in higher efficiency the better in power performance and lifespan.

Chapter #4 Input voltage & Output voltage

Next, below main power supply specifications:

Input voltage & Output voltage

Input voltage: (AC high voltage 110V/230V is worldwide, and DC voltage DC 110V etc.)

Unlike the traditional lights, LEDs need to be driven by DC low voltage. LEDs are low-voltage light sources, requiring a constant DC voltage or current to operate optimally. Light-emitting diodes (LEDs) require a constant source of direct current (DC) during operation. Individual LEDs might require 2–4 volts (V) and several hundred mill amperes (mA) of current. The voltages are generally in the range 100–240 V (always expressed as root-mean-square voltage). The two commonly used frequencies are 50 and 60 Hz.

To ensure consistent light output, the light source must be protected from line-voltage fluctuations that can cause disproportional changes in current. Driving the LEDs at current higher than manufacturer design limits can result in a brighter LED, but its light output would degrade faster due to higher internal temperatures. For these reasons, the majority of general lighting products that use LEDs need an electronic device that can convert incoming alternating current (AC) to DC and protect the LED from line-voltage fluctuations.

In general, AC to DC power supply is a very common type of led driver, which is considered as a power source in everywhere. DC to DC power supply also has been adopted in boat, flight, or high speed train lighting place, there has DC to DC type led driver work with emergency power source as well.
Besides above led drivers, other types of led drivers can be used for LED light as well. Such as Switched-mode power supply (SMPS) and AC adapter are power source for led strip lights.

As for input voltage of led driver, there has two types: one is fixed voltage (such as 110V,220V,230V), the other is wide range (100-240V, 86-265V, etc.).

Most of Europe, Africa, Asia, Australia, New Zealand and most of South America use a supply that is within 6% of 230 V. In the UK and Australia, the nominal supply voltage is 230 +10%/−6% to accommodate the fact that most supplies are in fact still 240 V. Japan, Taiwan, North America and some parts of northern South America use a voltage between 100 and 127 V.

For example, China needs the led driver with the input voltage of 220V AC, but the USA requires the input voltage in 110V AC.

The led driver with wide range input voltage, such as 100-240V AC can be used for almost worldwide area, due to the input voltage from 100v to 240v is available.

Output voltage: (constant voltage DC 5V, 12V, 24V, 36V, 48V; or constant current type)

The output voltage of led driver can be vary, which is depending on the working voltage of LED light and LED display.

As for the output voltage of constant voltage led driver, it usually has DC 5V, 12V, 24V, 36V and 48V. Let’s take led strip light as the example, the working voltage of led strip light normally has 12v or 24v dc, if one want to power led strip light in the USA, the led driver (input voltage should be AC110V or wide voltage input voltage type), the output voltage must be 12v dc or 24v dc (led driver with output voltage in 12v dc for 12v dc led strip light, likewise, 24v dc led driver for 24v dc led strip light)

However, due to the constant current led driver has the fixed current, the output voltage is vary. For example, the 10w 500mA (constant current) led driver has the output voltage: from 12 to 20v dc (The range of output voltage-“lowest voltage side:12v” can be customized by engineer so that it will meet with different requirements)

Constant voltage LED driver from Gaojie Electronics-best power supplies:
12v led driver (12v dc power supply)
24v led driver (24vdc power supply)
36v led driver (36v dc power supply)
48v led driver (48 volt power supply)

Output current:

If you purchase the constant current led driver, you should consider the output current. The output current of power supply stay constant for driving led, and the output voltage varies. Nowadays, the output current can be customized by customers for different needs of led light products. Gaojie Electronics is a leading supplier of constant current LED drivers & power supplies for the most cost-effective power solutions.

The Constant Current LED Driver is designed for driving LEDs in AC/DC high voltage applications. Universal input voltage ranged from 100-240VAC. LED drivers convert your power sources to constant current with a varying voltage, suitable for LEDs.

With years of proving high quality constant current led drivers in 300mA 350mA 450mA 600mA 700mA 900mA in different sizes, and installed in many small spaces and work well with led light products, we gain famous among our customers.

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Chapter #5 Dimming function (Dimmable LED driver)

Dimming function (Dimmable LED driver)

LED dimming performance is determined by Driver capability and compatibility with the dimming equipment. Multiple compatibility issues are rooted in circuit level interactions between the LED Driver and dimmer. Good LED dimming solutions are available today. Dimming can reduce energy consumption and enhance a space’s function.
Drivers can enable dimming and color-changing or sequencing of LEDs. LEDs are easily integrated with circuits to control dimming and color-changing so that these functions can respond to preset commands or occupant presence or commands.

The two main dimming methods for dimming the LED lights:

1. Coincident AC power and control signal:
   Phase-cut AC sine wave
   a. Forward Phase Control Dimming (Triac dimming, Leading-edge or SCR dimming)
   b. Reverse Phase Control Dimming (Trailing edge dimming)
2. Separate AC power and control signal
   1) 0/1-10V
   2) PWM signal,
   3) Dali (Digital Addressable Lighting Interface)
   4) DMX512

Phase-cut dimming

Forward Phase Control Dimming

It is known as “Triac dimming, Leading Edge dimming”, and SCR Dimming.
It is the most popular form of phasing dimming in the market. It usually uses a silicon device such as SCR or a Triac, to turn the mains waveform on part way through its cycle. By varying the point at which the waveform turns on, we can alter the amount of power delivered to the load. Triac dimmable led driver from Gaojie Electronics is compatible with most of brand leading edge dimmers in the market.

Leading edge dimmers (also called “triac dimmers” or “incandescent dimmers”):

• The electrical current (sinusoidal signal) is turned off at the front of the AC input waveform immediately after the zero crossing
• Traditionally used for incandescent lamps or magnetic low voltage transformers
• Produces a quick inrush of voltage into the load every half cycle which leads to a high inrush current into the electronic components of the LED lamp
• Causes buzzing sound when dimmed (though buzzing is not always perceptible and is dependent on many different factors, such as lamp design and number of lamps on a circuit. Even the dimmer itself, such as whether it allows dimming level adjustments and its minimum load requirements).

Reverse Phase Control Dimming

It is a “Trailing edge dimming”, which is a more complex circuit than a forward phase control dimmer. It is far more expensive and less common than the leading edge dimming type.
Trailing edge dimmers (“electronic dimmers”):

• The electrical current (sinusoidal signal) is turned off at the end of the AC input waveform immediately before the zero crossing
• Traditionally used for electronic drivers or low voltage transformers (capacitive loads)
• Is not subject to a high inrush of voltage that leads to a high inrush of current
• Does not cause buzzing sound when dimmed
• Produce less EMI and mains distortion than a forward phase control dimmer.

Trailing edge dimmers are a better fit for LED lamps. However, most of existing dimmers which are used for incandescent or halogen lamps, many manufacturers design and test their LED lamps to be compatible with leading edge dimmers.

Phase Control Dimmers in the market:
ELV (Electronic Low voltage)- Developed for use on electronic transformers & switch mode power supplies. Highest cost – Reverse Phase Dimmer

MLV (Magnetic Low voltage)-Developed for use on magnetics transformers. Medium cost – Froward Phase Dimmer that prevents DC in the output.

Incandescent – Developed for use on Resistive loads & bulb filaments. Lowest cost – Forward Phase Dimmer.

DALI – Remote controlled phase dimmer capable of either leading or trailing edge phase cuts dimming of the AC line.

Dimmer loading rules:

What is 0-10V Dimming?

Used as an early fluorescent dimming system and still used today, 0-10V dimming has been adapted to become a reliable LED dimming control protocol. This dimming method is more accurate than AC phase dimming.

0-10 V is one of the earliest and simplest electronic lighting control signaling systems; simply put, the control signal is a DC voltage that varies between zero and ten volts. The controlled lighting should scale its output so that at 10 V, the controlled light should be at 100% of its potential output, and at 0 V it should at the lowest possible dimming level. Gaojie Electronics 0-10v dimmable led drivers use CCR (Constant Current Reduction) based on the input signal level to achieve dimming.

Gaojie’s 0-10v dimming led drivers are compatible with Clipsal/Lutron/Dynalite dimmer (0-10V, 1-10V, PWM, and 100K Potentiometer dimmer), They are also perfectly work with Lutron & Clipsal lighting control system.

PWM led driver: In pulse-width modulation (PWM), the current sent through an LED is switched on and off at a high frequency-several thousand times per second. The current flow through the LED is the time-averaged value of the current when the LED is on and when it is off. Reducing the amount of time that the LED is on decreases the time-averaged current, or the effective current, delivered to the device and, as a result, its brightness.

Application of use PWM dimmable led driver: 1) Fixtures that must be dimmed lower than 40% and still maintain consistent color; 2) Color mixing applications, because of their need for precise levels of each color

The dimmable led power supply from Gaojie Electronics are made with built-in 3 in 1 dimming function (0/1~10VDC, PWM signal or resistance), which are compatibility with the general of led dimmers and lighting controls in the world.

Dali LED driver
LEDs can also work with devices governed by the DMX and digital addressable lighting interface (DALI) protocols and, in the future, may include wireless (RF) as a control option. Gaojie Electronics provide high power efficiency Dali controllable LED driver,built-in DALI interface and push dimming function.

The Gaojie Electronics as an Industry leader for led drivers, supplying full range of high performance Dali Dimmable Led Driver (Constant Current & Constant Voltage type), with full universal input voltage of 100-265VAC, the power of 10-235W, and the output current (amp) from 250mA/ 350mA/ 400mA/ 450mA/ 500mA/ 550mA/ 600mA/ 700mA/ 900mA/ 1050mA/ 1400mA/ 1750mA/ 2100mA/ 2450Ma/2500mA/ 2800mA /3000mA/ 3500mA/ 4200mA/ 6500mA, etc.

Dimming an LED source can change the behavior of the power supply.

– Efficiency can degrade, but may be offset by improving LED efficacy; unlike conventional sources, dimming does not affect the efficacy or longevity of LEDs. Lamp life is not affected by dimming, as is sometimes the case with frequently dimmed fluorescent lighting. Rather, dimming LEDs may lengthen the useful life of LEDs, because dimming can reduce operating temperatures inside the light source.”
– Flicker can be induced or increased; this is depending on the quality of led drivers. At present, it is not a problem. Solved by Gorgeous Lighting Co.,Ltd.
– Power quality, as quantitatively evaluated by the Power Factor and Total Harmonic Distortion metrics, can be degraded

 

 

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Chapter #6 Waterproof or Non-waterproof LED power supply

Waterproof or non-waterproof ?

The IP rate of Waterproof led power supply is start at IP65, which is the basis requirement of outdoor power supply transformer, otherwise, you have to put the led driver inside of a waterproof box (this is not good for heat dissipation sometimes). The housing shell of Waterproof LED power supply can be high Quality Aluminum Alloy or durable plastic case. In general, it is common to see waterproof led driver made in aluminum alloy housing shell, due to it is better for heat dissipation and stronger in outdoor use. High performance thermal management require high quality aluminum alloy housing. If you need the led power supply in water, we recommend the IP rate should be 68.

The connector for waterproof power supply must be waterproof as well, in case of any electric leakage. Same as water-poof led power, there has non-waterproof and waterproof connectors (IP20, IP44, IP65, IP68 etc)

Non-waterproof led power supply mainly used for indoor LED lighting, but not for wet space, such as bathroom, kitchen,etc. And there must have free space in installation area for heat dissipation of led driver. Durable plastic case is the main housing shell type for non-waterproof led power supply.

Protections
To protect the LED drivers and the light, a protection device is then required. Surge Protection (Over-voltage protection & over-current protection), A LED driver is required to provide a regulated supply of current. In addition, Short circuit protection; Over temperature protection, we need to think about protection modes for open and short circuits, and overheating conditions. The LED driver is likely to enter self-protection reset loops, either due to this dissipation causing an overheat, or due to short-circuit protection.

 
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Chapter #7 What is power quality of led driver?

What is power quality of led driver?

• It should be in high power factor, the closer to 1, the better it is (For example, the PF value of most of Gaojie’s led drivers is 0.95+.)
  Power Factor relates Active Power (P) and Apparent Power (S) by PF = P/S.
  Low(er) power factor loads DO NOT consume more energy, BUT they DO draw more RMS currentPFC is the abbreviation for Power Factor Correction. PFC allows power distribution to operate at its maximum efficiency. In order to maintain a high power factor, switch mode power supplies (including LED drivers) must employ some form of power factor correction. There are two types of PFC, Active PFC and Passive PFC. All of our power supplies are either Active PFC Power Supplies or Passive PFC Power Supplies. It is better have the active PFC function.
  Active PFC uses a circuit to correct power factor so that the led driver could provide more efficient power frequency. Active PFC is able to generate a theoretical power factor of over 95%. It also markedly diminishes total harmonics, automatically corrects for AC input voltage, and is capable of a full range of input voltage. Since Active PFC is the more complex method of Power Factor Correction, it is more expensive to produce an Active PFC power supply
• High power efficiency: The higher power efficiency of the led driver is, the better it is. High power efficiency led driver & power supply will definitely save more energy, and make the most use of the power, it can also save the cost, as a result, the led driver will be much more competitive in the market. Normally, if the power efficiency less than 80%, which is not a good power source, higher than 85% + is the good one, 90%+ is the best one in the market. We believe the power efficiency would probably higher than 95% in near future.One more thing about the power efficiency is: the smaller power of led driver is, the lower power efficiency is. For example: for the same series of led driver: the power efficiency of 20w led driver is about 80%, however, it will be 85% if it is a 60w led driver, and 88% if it is a 100w led driver. But one can’t say the 20w led driver is not good. If you want to know more about the power efficiency and led driver, please contact us.
• Perfect dimming performance: As for led driver with dimming function, the light should have no flicker, and high compatibility with installed dimmers.
• Lifespan: 50,000hrs +, the LED has more than 50,000hrs lifespan, as the power source for LED, the lifespan should be more than 50,000hrs. Which require the LED driver must have high quality electronic components inside, scientific design and perfect heat dissipation.

Chapter #8 The future market of led driver

The future market of led driver

In 2014, the gross output value of led drivers & power supplies was about US $4.4 billion, which was about 34% higher than the last year. And it will expand to more than $9 billion by 2019. According to the industrial report, there has more than 400pcs companies (enterprise above designated size) in China, among 90% percent are producing indoor led drivers.

This rapid growth is being driven by the fast developing of LED lighting and displays in the market. Also, the technologies for led drivers and power supply have been improved a lot: efficiency, stability and different functions, which will be mentioned in below articles. Last but not least, the demands of the replacement of defective power supply, some old led drivers probably broken after years of working or under bad situation, which need to be replaced with good led power.

The development of LED drivers & power supplies won’t stop just the same as the continuing innovations in LED technology.

The new control technologies require the updated led power supply:
Power line carrier
– Digital modulation of AC power
– Coincident AC power and control signal

Wireless
– Digital open spectrum communication
– Separate AC power and control signal

Centralized power supply or LED driver
– Low-voltage (CV or CC) wiring to LED source
– Coincident or separate AC power and control signal

ZigBee Light Link: Requires new control and LED driver

In conclusion, it is necessary & important to consider which type of led driver should be used as the power source for your LED lights. Constant current led driver is better than constant voltage led driver in relatively. You also need to think about what kind of dimming function do you need? The suitable dimming technology, and the existing dimmers, which installed in your place, does it compatible for your dimmable led driver? As the supplier of led driver and led lights, it should consider control technologies which separate AC power and the control signal. To consider using dimming controls designed for LED sources and/or new dimming technologies.

The buyer of led power also needs know the terminal connection type and length required for your led lights. The terminal connector can be waterproof or non-waterproof; it should be matched with your led lights.

Gorgeous Lighting Co.,Ltd.,- Gaojie Electronics have developed dimmable led drivers for 0-10v, PWM signal, DALI, Leading-edge and trailing-edge and ZigBee. It has perfect dimming performance and reliability, compatible with most of led dimmers in the market. Contact us now for more information.

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