How does CCS generate high voltages up to 920V?

[Glebiys]

Hello,

I am studying the design of DC fast chargers.

I learned some information about their varieties and the approximate principle of operation (Vienna Rect. - LLC DC/DC - Output).

Usually, after Vienna Rectifier, you can get a maximum voltage of about 840VDC, and then lower it to the desired level using a DC/DC converter.

Most electric vehicle models have battery voltages in the range of 345 - 480VDC.

The exception is the Porsche Taycan, which has an 800V battery.

It is charged by CCS, which can reach 920VDC.

As I understand it, usually the charging modules that make up the fast chargers give out 250-750VDC.
Further, they are already connected in parallel, for a set of high power.

I wondered how the CCS outputs such a high voltage (Up to 920VDC), if usually the modules produce up to 750VDC (which is enough for CHAdeMO).

Are they using other DC/DC designs (Buck-Boost) or simply combining serial and parallel connection of charging modules to increase the voltage?

Or is this voltage the sum of DC (up to 750V) and AC on the CCS plug?


Thank you!

 

[SilverString]

Perhaps they are using an additional step-up transformer on the AC side before rectification? Lots of ways to do this in addition to what you mention.

 

[Brando]

side note: I think I got this idea from Sandy Munro (?)

400 volts safer than higher voltages. Safer as in chances of getting electrocuted/hurt.
IF you consider this - let us know your opinion.

Ground Fault Detection - does it work at these higher voltages? any limits per voltage?
pyro fuses?

pyro fuse is a type of fuse for high voltage that use explosive rather than melting metal bar. Under high voltage, an arc might form inside a normal metal fuse defeating the purpose of fuses. Pyrotechnic fuse prevent the arcing by disconnecting contacts quicker.

 

[Frank99]

In the middle stage of the circuit you posted, there are four FETs driving a transformer. The output of the transformer Is then rectified by four diodes to give the 250-750VDC output.

To get 1000VDC out of the circuit would require nothing more than a different transformer with a higher output voltage (and possibly higher rated FETs). No need for anything more exotic than that.