7kW Electric Vehicle Charger/Discharger?

[treez]

Hello,
Do you think the attached is the best way to do a 7.5kW Charger/Discharger for an Electric Vehicle?

All six LLC converters would use the same transformer spec.
All 12 Boost converters would use the same Inductor spec.

The three discharge Boost converters are in parallel, and have a regulated output voltage, so therefore they need the single external error amplifier between the three of them. (so that they share current equally and don’t oscillate).

An alternative way would be to have three 2.5kW Grid-Tied-Inverters (instead of the one 7.5kW Grid-Tied-Inverter). This would then “modularise” the design nicely, as it would then contain three identical 2.5kW ‘Charge modules’, and three identical 2.5kW ‘Discharge modules’....(and the inconvenience of having the current share circuitry for the three discharge Boost converters then disappears)

(sorry the title should say "7.5kW")

- - - Updated - - -

The "Modular" version is also attached, and uses three identical 2.5kW "Charge" modules, and three identical 2.5kW "Discharge" modules.
2.5kW is a good size for a single module because the LLC transformer can be done with a low profile off-the-shelf PQ3535 core, which means the overall module height can be low, meaning that a 'stack' of them isn't too high.
The "module" idea is also good because in both "charge" and "discharge" directions, the module is "output current regulated", which means that the modules can be paralleled without needing any extra current sharing circuitry or inter-connectivity.

 

[Easy peasy]

Interesting concepts, certainly using a bi-directional topology requires a lot more control engineering design input, and there is an element of redundancy with the two lots of three approach.

keeping the modules fully self contained has a lot going for it...

 

[FvM]

Do you think the attached is the best way to do a 7.5kW Charger/Discharger for an Electric Vehicle?

I think it's a huge waste of resources.

 

[treez]

..However, its the simplest and most sure way of doing it..its the one way that means any basic Power Supply engineer can understand it and maintain or modify the design.
There are methods such as the " Single stage, Bridgeless PFC'd Isolated Cuk Converter"...however, few people in the world can understand this.
I wouldnt mind betting that the use of multiple smaller modules means that the thermal situation is less severe than in a "single stage" type design, -this would mean it will last longer.
Also, the redundancy Easy Peasy spoke of means that if one module fails, the others can still work.

Also, the size of the modules, limited to 2.5kw, means that off-the-shelf components and cores can be used, instead of custom stuff.

I also bet that this "multiple module" method means its more efficient than any of the "single stage" methods. -And with millions of electric vehicle chargers, efficiency is surely king.

The method of the top post looks poor, -until you look at the alternatives.