Electronic – Get -50V to 50V range from battery output

batteriesboostnegativevoltage

I have the following problem: on the system which is battery-powered(4S1P Li-ion battery, 14.8V) I need to create outputs from -50V to 50V. The system has microcontroller on-board.

I am baffled on how to do it. Initially, I planned on using bipolar DAC which would give output of +/- 5V or so and then amplify it with gain of 10 to get total +/- 50V.

The problem is, how to get power supply with range from -50V to +50V from the 4S Li-ion battery? I am familiar with concept of having two 50V sources, then connecting the + of one source to the – of another and using that point as common ground. Total current needed at +/-50V is 300mA. Loads are resistive.

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Am I allowed to connect in this topology using two boost converters(switchers)? Would it work?

Thanks;
D. Petric

Best Answer

If you want to do this with a single SMPS circuit, you need some kind of transformer or capacitive coupling. You can do this with SEPIC topology http://www.linear.com/solutions/7345 Linear SEPIC solution

TI has app note with transformer and capacitive coupling options for boost topology http://www.ti.com.cn/cn/lit/an/slua288/slua288.pdf

Texas capacitive coupled solution

Buck can also be used for this but obviously it does not apply here.

If you want a straightforward solution, use boost for +50V and buck-boost for -50V. You can often use buck converter as buck-boost, texas has app notes for a few different solutions. As a bonus this way both outputs are well regulated, dual output can have problems with cross-regulation.TI appnote shows you the efficiency and regulation suffers when you start draining more than 100mA.

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