In my case, I have a 384-536V unregulated, 12kW DC source available (i.e. solar).
What are you using to regulate? Can it take DC in if it is sufficiently above
the "ask" voltage. I can do 12kW at 384V but the power tapers down above that
so maybe I can only get to 80% without having the overhead of a high power
Solar panel DC is a bit elusive to use dependably, for example if a cloud happens
to float by (you know, the sky covering in monsoon season).
Since the Chademo vehicle expects the input current (thus power) to follow
its requested current, and there "appears" to be no provision for providing
substantially less (or more) than requested by the car, or abort the charging
True, there is a negotiation (kind of a mating ritual) at the beginning of the session,
before any charging actually starts, and part of that is the QC machine saying how
much voltage and current it can supply, and then the car wanting a demonstration
of the voltage "dance" from the QC machine. If the ritual is satisfactory (to both
sides), charging begins with a relatively fast, but controlled (by the car) ramp up
of the charging current, done at the present battery voltage, of course.
The car seems to allow for some lag in the current ramp, as the QC device
struggles to keep up. The current ramp is typically about 20 amps per second
(really plus 2 amps per 0.1 second).
Although this type of control is not difficult to do at low power, voltage, and
currents, where some wasted power is easy to handle, it most be done
quite efficiently when passing 50 kW, because even a 90% efficiency would
require 5,000 watts of cooling (think of the heat produced by 50 conventional
100 watt light bulbs).
Regulating a relatively dependable higher-voltage power source down to
a lower voltage, with a variable current (up to some maximum current or
temperature) is the job of a typical regulator. Another design allows a
relatively constant lower voltage source to be raised to a higher voltage.
Designing a regulator to do both jobs, at higher power, efficiently is more
what would be required to handle the Solar Power, even if it could provide
a dependable source of power.
The typical Solar Inverter has a slightly easier job, since it can produce
any amount of power at any time, and just "stuff" that power into
the grid. Producing more power requires drawing more current from the solar
panels, but the increased current flow causes a reduction in the DC output
voltage. The inverter typically "hunts" from the maximum power point,
since it is determining the amount of current to draw from the panels.
So, amateurs in power supply design rarely produce a single-stage, well
controlled, efficient design that will both decrease the voltage and increase
Isolation and voltage raising usually require a transformer. Low frequency,
high power transformers are very heavy, and usually get quite hot, often
requiring a cooling system. Using a higher frequency, modern-material
torroidal transformer might work, but the losses in the transformer might
require too much cooling to be nicely portable.
So, we are doing some experiments.
However, someone really experienced and skilled in this design area might
be able to provide a good solution, but patents and proprietary information
might obscure the state of the art.