Hi, Everyone
Recently we designed a system which includes 3* Quattro 48V 10kW & 2 * 250/100 MPPT tr and 40kWh BYD 2.56kWh batteries and some DC distributorsand DC power in. Just wonder how to pre-charge the DC bus when first time connect to battery.
I'm about to handle this for a much smaller system. Its "just" a parallel path to the main contactor that consist of a switch and a high power resistor.
Design wise there was a need to balance time to charge, pulse power rating of the switch, heatsinking arrangements and the DC break rating of the switch.
If you plan to disconnect the DC bus for testing and/or maintenance its worth doing the precharge path properly rather than jury rigging it.
I use a big 25 ohm resistor (because I have those available) with a momentary switch to bridge the battery breakers to do manual precharge. I'd recommend a 5 to 10 Ohm resistor for such a big system to charge fast enough (about 100W will do)
Another trick is to power up one of the multi's until it puts voltage on the dc-bus and then switch on the battery breaker.
If your setup includes available grid input on the Quattros' ACin1, you don't need to pre-charge from the DC side. (In some installations, you may be able to determine that a restart will always be in the presence of grid power.)
Precharge doesn't need to be anything complex .... momentary switch, only needs 10 seconds or so
