Miniaturization and Its Consequences

LpS 2018 - Human Centric Lighting
27 Sep 2018

Miniaturization and Its Consequences

„Light is not visible, light makes visible”, this also means that the room should be lit and the luminaires step into the background. In modern lighting solutions the luminaires are often no longer visible as they are integrated into the architecture, e.g. combined with acoustic absorbers or cooling ceilings. LED technology makes it possible to use very small optics, but at the same time, all other components of the luminaires must also be smaller to exploit this miniaturization potential.

More efficient LEDs mean less heat and consequently smaller heatsinks. But reducing the size of the LED-driver leads in general to a deterioration in the quality of the light, i.e. flicker. The size of the luminaire is meanwhile bound to the size and quality of the driver (electronics circuit), thus the driver becomes a key component of the luminaire. Smaller lights are also often associated with human centric lighting (HCL). This increases the demand on the requirements for the driver, which is difficult to solve with miniaturization.

A LED driver is normally composed of three parts, an ACDC converter ensuring good mains performance (PF and THD), a bulk capacitor storing the 50/100 Hz energy from the mains and a DCDC converter which controls the constant current output to the LEDs.The quest for miniaturized drivers generally leads to one of three solutions. The smallest change is to reduce the size/value of the bulk capacitor, which leads to increased voltage ripple on the bulk and increased current ripple on the output. The second option is to remove the DCDC converter and design for a decent trade-off between mains performance and ripple on the output. The third option is to use so called AC LEDs, which also have challenges with flicker performance.

In order to ensure high quality of light and low flicker in a given installation, it is important to know how to specify and test for flicker. This lecture will introduce some of the standards and specifications that can be used when specifying the driver. Bartenbach has the opportunity to explore the effect of flicker on users to define future standards. Furthermore, some of the possible test will be described and results from measurements carried out at Bartenbach and Nordic Power Converters laboratories will be presented.

In order to enable miniaturization while keeping high quality of light, Nordic Power Converters have developed a new technology enabling LED drivers to operate at highly elevated frequencies. This leads to a significant reduction in size of the components used in the LED driver while keeping both good mains performance and high quality of light.