Overview
As you may know, I'm a part of Terrier Motorsports. We build an electric race car and compete with other schools at the Formula Hybrid + Electric competition in New Hampshire each year, and hopefully at FSAE in Michigan, too, in the future. We're a pretty new team, which means having to figure out a lot of stuff on my own. This makes designing boards challenging, but super fun.
As a club, we've never actually gotten a car to drive at competition yet, so we're hoping to get this years car, TM-01, fully operational at New Hampshire.
I'm part of the Grounded Low Voltage team, which means I design parts of the electrical safety hierarchy we call the "Shutdown Loop." It ensures that the vehicle only turns on if everything is working correctly or shuts down if anything starts behaving abnormally. Last year, I worked mainly on board assembly, testing, and wiring harness routing, but this year I've leaped into a more design-focused role.
Design decisions
Previously, we used a 555 timer which is no longer permitted, and the board exclusively used through-hole components. In the new design, we not only transitioned to discrete voltage measurement using the LM393 comparator chip, but we also started using mostly surface-mount components. Although sizing down isn't a priority right now, it's good preparation for our next car, TM-02.
Since we are measuring directly from the HV sides now, there are strict rules for HV and LV isolation that we need to consider. The slot in the board is for meeting PCB on-surface creepage distance requirements. The components that go over the slot are the optocouplers and a galvanically isolated DC-DC converter.
