What role does the isolated driving power supply play in the development of LED power supply?

Generally speaking, since many LED lighting applications are enclosed in a small space, it is difficult to use ventilation to dissipate heat. Without careful thermal design, LED and power driver circuits can easily degrade or permanently fail due to high temperatures.

The design of LED lighting power supply can be divided into non-isolated design and isolated design. An LED drive power supply with an isolation transformer or electrical isolation means that the LED can be touched directly by hand without getting an electric shock. Although the LED driving power supply without an isolation transformer can still achieve partial mechanical insulation with the help of a protective shell, the LEDs at this time cannot be in direct contact during operation.

The physical design determines whether the drive is isolated or non-isolated. Security rules often require the use of two separate layers of isolation. Designers can choose between two physical isolation layers, plastic diffusers and glass shields, and use non-isolated power supplies. If physical isolation is too costly, presents mechanical difficulties, or absorbs too much light, electrical isolation must be addressed in the power supply. Isolated power supplies are usually larger than non-isolated power supplies of the same power level. Lighting designers must perform extensive cost and design optimization work in every product they design.

Because it is suitable for different applications, whether to use an isolated insulating transformer or an isolated protective lampshade casing, designers will always have different opinions from different perspectives. Usually, they will analyze from many aspects, such as cost and manufacturing process, efficiency and volume, insulation reliability and safety specification requirements, etc.

The cost of driving with a transformer is higher, but it also makes LED lamps more practical and can meet the needs of end users who accidentally come into contact with LEDs. When the incandescent lamp glass envelope is easily damaged, an ordinary E27 model bulb can be replaced with an LED lamp. In addition, lamps used in industrial areas or office equipment do not need to come into contact with end users, such as street lamps and shopping mall lighting. At this time, LED lamps do require isolation transformers.

As a product that can be used safely by end users, the reliability of insulation and isolation must be considered. As a complete product, the parts of the product surface that are accessible to users must be isolated to prevent people from getting an electric shock. From the perspective of the entire product system, isolation is inevitable. The only difference is the location where isolation is set. Some designers use an isolated transformer design so they can simplify heat dissipation and lampshade design. If a non-isolated drive design is used, reliable insulation requirements must be considered on structures such as lamp housings. Therefore, as a power driver, isolation and non-isolation solutions have always existed at the same time.

The main challenge that Chinese LED drive power supply manufacturers may face is to find low-cost AC/DC drivers to meet the more stringent power factor and efficiency performance in low-cost power systems.

In the future, the use of high-quality, high-reliability power supplies in systems with limited space and difficult heat dissipation (such as LED lighting fixtures) will no longer be free. However, it will be difficult to demonstrate high quality until the end user has used many bulbs with a lifespan of around 10,000 hours.

Transformer-based isolated LED driving power supply will become mainstream

Isolated and non-isolated LED driving power solutions each have their own advantages and disadvantages. ClassII will likely become mainstream because it simplifies LED heat dissipation issues. Class I or II systems rely on a grounding system, which in most cases depends on the installation location. Class II is more common and requires double-level or reinforced isolation, which requires transformer magnetic windings, insulating tape and physical isolation. Class I systems require a grounded enclosure and/or mechanical barriers, which are not required for Class II systems.

There are several trends currently driving the development of the LED lighting market. The first is the continuous improvement of high-brightness LED efficiency and the continuous emergence of very efficient and high-reliability constant-current LED driving power supplies, followed by the global legislation banning incandescent lighting (due to its low efficiency) and the gradual fading out of CFL energy-saving lamps (if broken If it does, it will release mercury that is harmful to the environment). The combination of these factors is making LED lighting a long-term development trend. Of course, low system costs (including LEDs, thermal management systems and LED drivers) will always be the driving force behind widespread consumer adoption of LED general lighting.

In fact, in many LED lighting products, failure is a common phenomenon, most of which are due to the failure of the power supply rather than the failure of the LED.

At a design level, this means OEMs must become experts in system thermal design. LEDs offer high efficiency, but they also generate more conductive heat than incandescent or CFL lamps.