Fault behaviour

Notes from meeting on July 29 (and 5 minutes into July 30).

Relay behaviour

The solar relay should mirror the battery relay. Receive relay CAN messages from centre console and set the solar relay to mirror the battery relay. (If the solar board loses power, the relay is opened automatically.)

Faults

On battery faults: open the relay. (Goes along with mirroring the battery relay.)

Overcurrent: if the whole-array current is greater than 9A, open the relay. Note: the current will become signed (switching an IC for a bidirectional sensor). Any negative current, open the relay.

Overvoltage: if the sum of the MPPT output currents (from op-amp/I2C) is greater than 160V, open the relay.

Overtemperature: have an overtemperature threshold, but just log the fault.

MPPT status faults: just log the faults.

Other notes

None of the drive train startup should be dependent on solar working. We want to be able to drive without solar.

If the 5 and 6 MPPT boards disagree, the 5 MPPT board is correct.

On infotainment, we want to display the sum of the MPPT output voltages beside the battery voltage and warn the driver if the sum of MPPT output voltages is less than the battery voltage (which means we aren’t charging from solar).

It would be nice to have an “Engineering” tab on infotainment (or possibly the laptop) with a sweet GUI for all the faults and debugging info. Could include a chart of the MPPTs and their data/fault status.

When testing the MPPTs in November, a fault condition was found where when the MPPTs were connected to the power supply, an undervoltage cutoff would be triggered, all status bits bad, etc. This was because the MPPTs expect an ideal DC source like the battery or the panels which the power supply isn’t.