Over the past few days, initial schematics for the BMS circuitry have been designed and redesigned. To monitor each battery voltage, we have decided to settle on a difference amplifier topology which will then feed into an Analog to digital converter on a TI MSP430 chip (Fig. 1). The MSP430 will then run an algorithm to sort out the minimum battery voltage within the module and start bleeding the other batteries until they are balanced. The bleeding circuit may be created using an optically coupled p-channel device which turns on an n-channel transistor (Fig. 2). Eventually, individual temperature monitoring for the slave boards will be added and a master module will be designed to include inter-module balancing as well. Please keep in mind that this circuitry is still preliminary and not everything has been simulated to ensure that everything works as expected.
- This circuitry was designed by Bin Lu and Eric Winokur