{"id":1834,"date":"2012-01-13T22:24:38","date_gmt":"2012-01-14T03:24:38","guid":{"rendered":"http:\/\/www.summet.com\/blog\/?p=1834"},"modified":"2012-01-12T22:26:15","modified_gmt":"2012-01-13T03:26:15","slug":"adventures-with-a-boost-converter","status":"publish","type":"post","link":"https:\/\/www.summet.com\/blog\/2012\/01\/13\/adventures-with-a-boost-converter\/","title":{"rendered":"Adventures with a boost converter"},"content":{"rendered":"

\"Breadboard<\/a>
\nA boost converter is a dynamic electronic circuit that can “boost” a lower voltage up to a higher voltage. Current is of course reduced in the process, but if you design it right you only lose 5-25% of the overall power. I am in the process of building one that will convert the approximately 70 volt nominal output provided by my solar panels<\/a> into 125-140 volts that will charge my trucks batteries<\/a>. I also plan on adding a bit of maximum power point tracking and battery charge regulation to the control logic, making it a MPPT solar boost converting charge controller. Why do I have all of these wires and parts scattered across the dining room table? Because the market does not sell what I need. (Believe me, I’ve looked.) So I have decided to build what I need. <\/p>\n

Not being an electrical engineer, I probably won’t be able to get 95% efficiency out of my system, but so far I’ve measured 85-90% efficiency when doubling voltage. [Test 1: 23 volts in at 0.28A for 6.44 watts, 46 volts out at 0.12A for 5.52 watts means 0.92 watts loss = 0.92\/6.44 = 0.142 or 14.2% losses. Test 2: 34.8 volts in at 0.35A for 12.18 watts, 72.3 volts out at 0.15A for 10.84 watts, or -1.335 watts loss, which is 10.9% losses.] <\/p>\n

I’m still running things off of a (relatively) low voltage and current supply (two\/three 12V 5AH batteries) while getting everything working, and only boosting up to 50-72 volts when testing. <\/p>\n

I had the circuit up to 95 volts (max of 16 watts) on the output side, but I really want to optimize it for a voltage doubling, and you lose a good amount of efficiency when going higher than a 50% duty cycle.<\/p>\n

I have also not been able to find a commercially available boost regulating control IC that works with 100 volt inputs and produces up to 200 volt outputs. One probably exists, but digikey doesn’t appear to have it. I’m solving this problem by programming my own using a PIC micro-controller. At least the programmable nature of my controller should also allow me to add the battery charging maximum voltage\/current and solar panel MPPT logic into the system. I am currently working on a single phase boost converter, but the plan is for the final system to be two phase (which basically means that I use two of them in parallel). This means that I need my single phase system to be able to support 100-175 watts maximum. Soon I’ll be moving from my 25 watt resistive load (25 watt lightbulb) to a 100 watt resistive load. Eventually, I may even borrow a 75 volt power supply and test it up to 140 volts.<\/p>\n

While working on my boost controller, I’ve found the following reference links very useful:<\/p>\n