Formula Student Electric - Accumulator Management System

Building a competitive race-car needs a powerful tractive system. We at Campus Tirol Motorsport decided to supply our racecar with a 600V-Accumulator to reach a maximum power of 72kW.

One of the most complex tasks was the design of an own accumulator management system.
It is splitted into 3 parts. The first part is the cell supervision circuit which is a PCB directly mounted onto the cell segments. It balances the battery cells and checks the cell-temperatures. Both temperature and cell voltages are sent to the AMS-PCB in the front compartment of the accumulator using ISO-SPI.

The AMS is an STM32-based PCB with a CAN interface and the ability to switch the relays of the Accumulator that cut off high-voltage from the rest of the car.

To prevent damaging of the relays due to high current-peaks when closing the relays and charging the DC-link capacitors of the inverter, another PCB is mounted onto the AMS-PCB which precharges the capacitors 95% of the Tractive System voltage through a resistor.

AMS and precharge are stacked together with an Insulation Monitoring Device which results in a compact and space-efficient PCB-stack. Precharge and AMS are connected through a pin-header, saving a lot of wiring.

When the AMS opens the relays due to overcurrent, low-voltage or other software-controlled reasons, the dc-link capacitors are discharged through a PTC-Resistor mounted on an external PCB.

This project was part of the bachelor-thesis of one of our team-members at the university of Innsbruck.

Over 50 PCBs, including different versions of most of them as well as multilayer-PCBs have been developed over the last two years by the CTM-Team using KiCad and were manufactured by Aisler. We absolutly love the easy-to-use website and the abillity to upload KiCad board-files directly.

Shoutout to Felix and the Team from Aisler, you guys really make hardware less hard!

AMS-stack mounted inside the accumulator

AMS-Stack with Precharge and IMD

Overall front compartment with high current relays and fuse

One of the low voltage PCBs

Testing session at the Nordkette in Innsbruck