Electrical System Load Management for High Power Work Lights Using Light Type Detection through Signature Recognition Technique 2015-01-2867

Work lights with high power rating consume high current. Since the battery voltage is fixed, high currents are needed to generate the necessary power (wattage). This makes it difficult to manage the load on the Electronic Control Unit (ECU) responsible for controlling the work lights and also on the entire electrical system of the vehicle. It is possible to prevent the system from getting over loaded by employing effective means of work light control techniques. These techniques differ based on the type of work lights connected on the vehicle.

There are three types of work lights available in the market. Halogen work lights, High Intensity Discharge (HID) work lights and Light Emitting Diode (LED) work lights. HIDs are not preferred by most customers due to their high warm up times & cost/unit. The other two types of lights, i.e. LED & Halogen, are comparatively less expensive. They also need negligible warm up times which are not objectionable to the vehicle operators. Due to these aspects, LEDs or Halogen work lights are provided as the default option on most of the off-road vehicles, regardless of the fact that their current consumption is relatively higher when compared to HID work lights. Sometimes, a combination of LED and Halogen work lights is provided on the vehicle. The type and rating of the work lights governs the design of the electrical system controlling the lights. For example, the gauge of the wire driving the work lights depends on the current rating of the light, the maximum duration the lights will remain on & the distance of the light from the ECU responsible for controlling these work lights. Also, the ECUs controlling high power work lights need to have components with higher current/ wattage rating. This adds to product cost as ECUs with higher ratings are expensive due to higher component costs. This cost further increases due to the complex design of the heat sink required to satisfy the heat dissipation needs of the ECU.

To interface high power work lights with a relatively low power & cost effective controller, current limiting means can be employed. But sometimes, the vehicle operators replace the factory fitted lights once the default lights are worn out. In any case, control methods programmed in ECUs for controlling lights shall be compatible with the type of light installed on the vehicle, i.e. halogen or LED; else they may either damage the ECU/work lights or substantially reduce their life.

This paper provides methods for controlling high power work lights with a relatively low power ECU without damaging the work lights/ECUs and at the same time ensuring that sufficient intensity of light will be available at the most critical places around the vehicle. This in turn helps to manage the load on the ECU and on the entire electrical system of the vehicle. Employing these techniques enable system architects to use low cost low power controllers for controlling high power work lights. One of the essential components in these techniques is light type detection. This paper also provides an innovative technique for automatic detection of the type of light connected on the vehicle to ensure employment of compatible control methods. Since, LED and Halogen lights are most preferred as work lights; the scope of this paper is restricted to these two types of lights.