Quote:
Originally Posted by e*clipse
Excellent news - thanks for the update. 
I think this is a great way to supply a charger. I made a small demo boost converter charger that relied heavily on the batteries to smooth the output. It was based on an Infineon boost controller. When the cells (measured individually with the BMS) reached the constant voltage stage of charging, the BMS would ultimately control the charging. It did this by measuring the cells' voltage and calculating the voltage drop slope curve over time. The BMS would turn off the charger when the cells reached a pre-determined voltage, then turn on again when the voltage drop curve reached a pre-determined slope. Charging was complete when the voltage drop curve slope was low enough to consider the charge complete.
Do you have any #'s regarding boosting for 50kW or 60kW?
Or were you thinking of doing this differently than 'Yota (boosting to 650V, then creating 3ph)
For example were you planning *somehow* to boost to 3 ph directly?? 
Sorry if you've covered this already, I guess I'm a few steps back.
Thanks a bunch,
E*clipse |
That's pretty much what I do as well. The charger output is variable and reaches a peak at 444VDC. Once one cell reaches 3.45V the charge is stopped, otherwise they are allowed to 'float charge'. I don't do balance charging.
The output is pulsating DC so it needs some good capacitance to smooth before going to the battery.
At the moment I'm not particularly targeting the inverter boost converter, (I think Paul is working on that) but of course the work done may be used with little modifications. My personal idea is to boost on demand as more/less torque is required, rather than having a fixed voltage. This allows the converter to operate only while under heavy load (current mode) where the inductor current remains continuous. Discontinuous mode would possible generate far too many losses on the switches
I received my inductors yesterday and I'm waiting for some samples from on-semi and some fast MOSFET/diodes I got from the USA... I might eventually consider moving there to speed up the process