Modelling of fluorescent lamps for circuit simulation

Globally, lighting is responsible for approximately 19% of all electricity consumption producing roughly 1889 MtCO2, equivalent to roughly 70% of the carbon dioxide emitted by passenger vehicles worldwide. The majority of energy consumed by lighting is consumed by incandescent lighting despite it only producing around 45% of the worlds artificial light. Switching from incandescent lamps to more efficient alternatives such as linear fluorescent and compact fluorescent lamps (CFL) has the potential to significantly reduce energy use due to lighting without any major impacts on society´s quality of life.

Although there is currently a good understanding of the physical behaviour of fluorescent lamps it has proved troublesome to provide a good model that is suitable for circuit simulation. Ballast designers have generally resorted to treating the fluorescent lamp as a resistor whose value is found from experimental results. This approach ignores the fluorescent lamp´s non-linear behaviour and requires time consuming experiments to be undertaken for each new operating condition or lamp type.

The purpose of this work is to produce a hybrid model that relies on physical laws where possible resorting to approximations, found from observing the results of a self consistent collisional radiative model, where the physical solution proves too computationally complex. This approach allows for the construction of a model that can be implemented in circuit simulation software, such as SPICE, Simulink and Saber, yet retains enough physical meaning of the lamp´s behaviour to be valid over a wide range of operating conditions. The model negates the requirement for experimental data to be collected to tune the model by using common lamp parameters such as the lamp length, diameter, buffer gas pressure and wall temperature.

Experimental and simulated voltage-current characteristics at 50Hz and 30kHz (black – simulated, grey – experimental)