AMS Master for a Formula Student car

We are e-Tech Racing, a Formula Student team from Barcelona. We have been competing since 2013. We have assisted to FS Germany, Italy and other well-known events.

This year we are trying to implement a new BMS concept. We are moving from having a microcontroller in every slave with CAN communication to only one IC with ISO SPI communication with the master. This new way to implement our car’s BMS is very demanding in terms of design. We need to fit all needed hardware in a perfectly designed and high reliability PCB. This PCB is electrically attached to a microcontroller and CAN communication board, which manages all ISO SPI and CAN communications.

In this competition, finding the balance between performance, reliability and feasibility is key. This design tries to meet all 3, by reducing the used space, while reducing the weight and facilitating the maintenance. For context, our team competes with an electric vehicle and this board is placed right outside of the accumulator, managing its isolation and safety.

The board has 3 defined parts, the power one where we mounted our accumulator isolation relays to the board and connected to the power cables by copper traces and a high-power PCB mounted connector, reducing the space occupied by cables and allowing us to mount a resistor on the board.

The second part is also high voltage but it’s just a safety/monitoring system, first the voltage is measured by two circuits, a programable one and a non-programable one. After that, also for safety, an LED outside the accumulator container is turned on if there’s voltage after the isolation relays.

Finally, after the proper isolation, we find the low voltage system, where there’s a microcontroller, connected from an external board, and digital logic to complement all the measurements made in the high voltage part.

You can follow our experiece in YouTube: https://www.youtube.com/c/eTechRacing