12S Pre-Charge Controller Module
Description
12S pre-charge controller module for controlled start-up / shut-down behavior of entire system power distribution network.
Engineer: @Robert Tang
Supervisor: @Kevin Li
Requirements
12S rated
Pre-charge/discharge circuit for controlled on/off behavior of entire power distribution network
Battery voltage / current sense ?
12S
100A pulse current / 60A continuous current
Dedicated MCU
CAN interface
System Background/Research
Pre-charge circuits
Why it is needed?
Without the pre-charge circuit, when connecting a high voltage source to the load, which can be modelled as a capacitor, there will be a large potential difference, and this will cause inrush currents that can damage the components. When the pre-charge circuit is used, the load capacitance can be safely charged up, and then the switch can be closed.
Reference documents
Why Pre-Charge Circuits Are Necessary in High Voltage Systems
High-Voltage Solid-State Relay Active Precharge Reference Design Reference design for this TPSI3050-Q1
Managing Inrush Current Not the exact same as pre-charge, but gives an general idea of managing in-rush current, and some of the methods in the doc are relevant to the pre-charge circuit (integrated load switches)
Designing a BCM® Pre-Charge Circuit
https://www.youtube.com/watch?v=dlGTonFXSrI&t=681s
https://github.com/michaelruppe/FSAE/tree/master/Precharge/Precharge Pre-charge circuit for tractive system
Pre-charge Component Selection
Search on DigiKey for: high-side FET driver, not looking for driver with internal FET (can reflect by no R_ds_on in the spec)
IC & Link | Type | Â |
---|---|---|
High Side NMOS Driver | The similar IC (4810) that was used in 12V->5V @ 5A Buck (without pre-charge, 48111 is with pre-charge) 3.5V to 80V input | |
Isolated Switch Driver | Might be overkill for our application | |
Current Controller | Is a bit different, does not mention pre-charge directly, but have in-rush current protection and have helped decrease dv/dt | |
https://www.digikey.ca/en/products/detail/texas-instruments/BQ76200PWR/5801509 | High side NMOS Driver | *With PMOS pre-charge FET driver function |
 |  |  |
CAN (and MCU)
Resources:
CAN - Controller Area Network (EFS team)
Current sense
Some pre-charge FET driver IC, such as the TPS48111 chip, has integrated current sensing feature, however I need to do calculations to validate the feasibility of the feature.
If the internal current sensor does not work, an external current sensing circuit is needed
System Design
System Block Diagram:
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