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Old 05-27-2009, 12:19 AM   #1 (permalink)
NiHaoMike
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DIY EV DC/DC converter?

Switching power supply
Perhaps the design could be modified for use as an EV DC/DC converter? At 40A continuous, an auxiliary battery might not even be necessary. Just a large car audio cap or two to assist the supply with load transients.

Modifications needed:
* If an auxiliary battery is used, the supply must not draw any significant current when off. Putting the controller on its own rectifier is an easy way to solve it. Then the only draw when off will be the feedback voltage divider and (insignificant) leakage current of the components.
* The supply (generally) needs to operate from a lower voltage. Use transistors with lower voltage ratings but higher current ratings and scale transformer turn ratios and component values as appropriate.
* Since devices like digital meters and the MOSFET drive circuit of some EV controllers need isolated supplies, add auxiliary outputs to supply those voltages.
* Replace the current-based fan controller with a temperature-based fan controller. Or leave the fan running whenever the supply is on since the power usage is insignificant.

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