Monday, 10 October 2016

Power Distribution to Greenhouse LED Lighting


I'm working on designing a custom LED lighting control system for an agricultural research project. This involves supplying significant amperage to high power LEDs distributed over a wide area (e.g. hundreds of feet). I have some influence over all aspects of the design. Each lighting fixture could demand, say, 1 Amp; and lets say there could be 100 fixtures. I'm thinking of using a (PWM dim-able) constant current buck driver to run a number of fixtures, and supplying a high enough DC voltage to each driver that it can run a number of fixtures wired in series.



Power efficiency is of paramount importance to the project, and I recognize that the LED selection has a lot to do with that (i.e. luminous efficacy), but from a strictly electrical standpoint I'm seeking advice on how best to optimize power efficiency in such a system.


I need typical (i.e. 5V or 3.3V) control / logic voltages at the light fixtures, but I can also envision benefits in carrying higher voltage (e.g. 36V) throughout the system, and DC/DC switching it down locally, so that I can have a number of LEDs in series supplied by each driver so as to overcome the forward voltage burden of the LEDs.


Does anyone here have experience designing LED lighting systems like these, and can share insights on how to distribute power efficiently to them? I am wondering if I have the right idea, e.g., putting in Meanwell AC/DC power supplies at regularly spaced intervals to independently supply power to regions of the system, and if so whether there are special considerations with regard to the type of power supply used in this application. I've read that power factor can be an issue in systems like these, but I don't understand why, or what is to be done about it. What kinds of power efficiency can I reasonably expect to attain?


Should I instead by thinking about running 110VAC (or 240VAC) to each fixture and doing the AC/DC conversions on the driver boards instead?




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