I have a solarpanel array that generates 600V, 5A (3kW). I want to create a small electronic unit to measure the DC current and voltage and transmit this wireless. For this I have an electronic board with ADC's and transmitter. This board uses a maximum of 3.3V and 100mA. I want to use part of the power generated by the panels for this board.
I found some components like the LR8 from Supertex, but this is not supplying enough current and has a max of 400V. It seems like whatever I do to convert this voltage down to 3.3V, I loose a lot by heating of powertransistors or mosfets. As the board might be floating I wonder if there are more smart methods to power this board?
Any ideas would be very much appriciated!
Answer
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Related
Design Considerations for High Step-Down ratio Buck Regulators
You will have some voltage drop between the panel low voltage end and the battery or load. An energy harvesting IC or a custom boost converter running from a fraction of a volt would be able to provide the energy you need.
To produce 3v3 @ 100 mW = 330 mW assume you need 500 mW in.
At 5A, to produce 500 mW you need a potential of 0.5 W/5A = 0.1 V. That would be with all the drop being used by the converter. If you had 0.5V drop available you need 1A. The first essentially requires interrupting the feed cable and the second is still a substantial proportion of the 5A load current.
If you introduced a point voltage drop across eg a MOSFET it would be more controllable.
Say 0.5V at up to 5A available = 2.5W.
Series MOSFET, regulate to 0.5V drop.
Efficiency loss = 0.5V/600V = 0.08%
BUT
You say
... I want to use part of the power generated by the panels for this board.
... but I do not have the option to use a single panel for this.
... As the board might be floating
but you do not say why these conditions apply.
Giving a fuller definition of your problem would help.
You say that your target load is 3V3 x 100 mA = 330 mW.
Adding a small PV panel to power your system would be trivial.
Presumably there is a converter supplying mains and or battery.
Presumably using these is not acceptable. Saying why may help.
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