Replace the inrush current limiting (ICL) circuit
Less power. Current circuit wastes power to keep the NTCs hot.
If the main pack is disconnected from DC-DC, the HV caps will discharge, but the NTCs will still be hot for a while. When the main pack is reconnected, the ICL will not work because it’s already hot.
The NTCs probably won’t share the load evenly, which risks damaging them.
Switch to a 24V low voltage system?
I think a lot of the 12 V components we use (relays, etc) usually have 24 V variants that draw less current. This would reduce the losses from parasitic resistance.
Dynamic trim?
Replace the large capacitors with capacitor multipliers?
Some unfinished research on input filtering that may or may not be correct
https://docs.google.com/document/d/16yPDBctcahSyoY-HaPGO9dtGbWUdar-TTmWSBeYhLfg/edit?usp=sharing
ICL
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The current inrush due to bulk capacitance at the input is limited by MOSFETM1. It has a capacitor C2 between gate and source, dramatically increasing the tun on time of the MOSFET. Thus it will operate for longer in its ohmic region, limiting the amount of current passing to the capacitors while they charge. Current is limited to <4A for an input voltage of 154V and bulk capacitance of 2000uF. The circuit takes up to 3 seconds to ‘reset’ as C2 discharges through R2 and turns the fet back off. Inrush current won’t be limited during this period.
Discharge
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Since the input is at high voltage, a capacitor discharge circuit is required to make the board safer to handle after power is disconnected. When power is disconnected, M3 stops pulling the gate to M2 low, allowing current to flow through R3 and bringing the voltage of the caps down from 154V to 60V in about 2 seconds.