Open Standards/Multipurpose AC-Battery/Questions and answers

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This page answers most upcoming questions (FAQs).

Isn't it crazy to use hundreds of MOS-FETs instead of six in an B6-bridge?

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Well, if only the number is regarded - yes. But there are significant differences. First, the MOS-FETs have to switch maximum 10 V instead of 600 V, 1200 V or more. And they can do this slowly within 100–300 ns. This reduces the switching losses to a minimum, and distributes it over many devices. So standard parts from user electronics can be used instead of state-of-the-art large and high-speed chips.

Second, there is no need for separate charger and motor inverter anymore, because the same power electronic is used for many purposes.

In a conventional battery charger I need a transformer, the AC battery also needs a coil for buffering ripple currents - so what?

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The point is the SIZE of the coil. Example: A solar inverter for 20 KVA is switching about 600 V and needs a storage coil with a weight of roughly 10 kg. An AC battery pack can only switch about 7 V up or down, means for the same ripple current and power rating the coil reduces to roughly 0.12 kg. Even more, there is no need for buffer capacitors, and EMC problems are reduced to a minimum.

Why don't we have these battery packs today?

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AC battery packs are a simple and logical solution. Well, I was told that "producers want to differentiate from others with their own battery technology", meaning that a standardized product is not desired. May be it is possible to earn more money with a lot of additional products (chargers, battery management, inverters, express chargers,...) than with a simple solution.

On the other hand, the standard product can be sold (or rented) in really large volumes, without the need of high development costs necessary for different products. Earning money with AC battery packs is possible, too. But in another way of business as we have today.