# High Voltage Boost Converter



## Inframan (Jan 30, 2011)

I was wondering if anyone knew where I could pick up an off the shelf step up dc to dc for a solar truck project because a customer of mine wants solar panels on his electric truck I have tried to tell him the drawback but he really doesn't care. Anyway I've thought instead of ordering relatively high voltage panels 36 volts and wiring them in series I could have a boost converter step up from 18 to 135 volts or more since he is starting out with only a 120 volt pack of floodies and it he wants to up grade later to higher voltage he wouldn't have to change his entire set up so the system is more flexible that way. Has this been discussed before?

EDIT:Also he want to put 4 250 watt panels on for a total of 1000 watts just to have an idea of power needed.


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## PStechPaul (May 1, 2012)

If you can work with 12V or 24V you can use an automotive inverter to get 135VDC or 270VDC, and a 1200W unit is less than $50:
http://www.ebay.com/itm/181102816053 (24V to 220VAC or 270 VDC)

I'm not sure exactly what you need, however. I think you need a special solar power unit that automatically determines the best power transfer level and then makes 120 or 240 VAC for grid tie. For off-grid installations you just need to install a two-way charger/inverter to dump excess into the batteries and then draw power back out as needed. But if you fully charge the batteries you may need to disconnect the solar panels.


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## Inframan (Jan 30, 2011)

Would I have to used a bridge rectifier and a diode on the AC ouptur for whatever inverter I choose? Would a 120 volt inverter work for his 120 volt lead pack now? What if he later wanted to upgrade to lithium how would I control the charging then? What about pack voltages that are in between 120 and 220? I have search all over and can't really find an off the shelf solution


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## major (Apr 4, 2008)

Inframan said:


> Would I have to used a bridge rectifier and a diode on the AC ouptur for whatever inverter I choose? Would a 120 volt inverter work for his 120 volt lead pack now? What if he later wanted to upgrade to lithium how would I control the charging then? What about pack voltages that are in between 120 and 220? I have search all over and can't really find an off the shelf solution


I had to do a system needing a couple hundred volts from a 12 V truck alternator/battery system. I ended up using 2 Vicor ( http://cdn.vicorpower.com/documents/datasheets/ds_vi-200.pdf ) 12in/95out converters with inputs in parallel and outputs in series. 190V was just enough for what I needed. It was only 150W total. I think it cost about $4 or 5/watt. That probably is about the closest thing to an off the shelf solution out there.


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## TEV (Nov 25, 2011)

Inframan said:


> Would I have to used a bridge rectifier and a diode on the AC ouptur for whatever inverter I choose? Would a 120 volt inverter work for his 120 volt lead pack now? What if he later wanted to upgrade to lithium how would I control the charging then? What about pack voltages that are in between 120 and 220? I have search all over and can't really find an off the shelf solution


All the Manzanita chargers can work with a DC input if you let them know before you buy it.

I know that they require a minimum 80V for AC input.

http://www.manzanitamicro.com/products?page=shop.browse&category_id=14&vmcchk=1


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## PStechPaul (May 1, 2012)

You probably won't find an off-the-shelf solution for a project that differs from the norm, as this seems to be. If you intend to build a fully solar powered vehicle, remember that the 1000W panels will probably only produce about half that most of the time, and even at maximum output will only provide a little over 1 HP to an EV motor. There is a guy who made a totally solar powered tractor, but it has $10K of panels and it only runs for short periods of time. A practical solar powered highway vehicle might never be achieved. The maximum insolation at the earth's surface is about 1000W/m^2, so a truck with an area of 2m x 4m would get only about 8kW at best. The best solar panels are about 25% efficient so you might get 2kW under ideal conditions.

You can use a bridge rectifier on an AC inverter to get the peak DC which is 135 or 270 VDC nominal, but it's better to get the DC from the first part of the inverter. The output is not isolated so you need to deal with that. The internal DC shares a common ground with the battery, but if you rectify the output it does not. The AC output can be connected to some large capacitors and diodes in a voltage doubler configuration, so you can get about 250 VDC from a 120 VAC inverter.

You need a charger specifically designed for the batteries you have or plan to use. Lead-acid batteries can use common chargers that run on 100-130VAC for 12V batteries, but for 10 floodies you'd need 10 chargers. Much better to get one designed for 120-144 volts. 

In any case, photovoltaics are not really practical for a DIY electric vehicle, and thus are somewhat off-topic. You may need to ask people who have home solar panels for advice on batteries and controllers.


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