Bring the DC bus up to pack voltage through a resistor before the main contactors close.
Without precharge, closing the main contactor onto the inverter's DC bus capacitance draws an inrush current large enough to weld the contactor. The precharge circuit closes a resistive path first, waits for the bus to reach a threshold, then closes the main contactor and opens the precharge path.
No part-specific design process is documented. The Accumulator LV subsystem design process applies: 1. List every low voltage function inside the container and what it must interface with. 2. Decide grounding architecture (star chosen) and lay out the returns. 3. Design the boards, with conformal coating selected against the requirement (acrylic is easier to rework, silicone is more vibration resistant and more temperature tolerant but costs more and is harder to remove). 4. Design HV monitoring: optocoupler (smaller, cheaper, digital, needs conformal coating) against voltage transducer (no conformal coating needed, larger, more expensive, analog). 5. Build the sub-harnesses, test in simulated conditions before the pack is live.
Board manufactured externally, populated and bench tested in house before it goes on the car.
Custom PCB with a machined or 3D printed enclosure.
None recorded. This part has no entry in Knowledge_Transfer/Issue Logging/Fault Vault.xlsx, in either Issue Log.xlsx, in CR22/Issue Tracking/Shakedown 7-15-23.xlsx, or in any design review issue list found in CrimsonStorage or Box.
Nothing in CrimsonStorage covers these yet.