Solid-state battery management system for high current applications
A Battery Management System (BMS) integrating solid-state relay and current shunt sensor on a single printed circuit board assembly (PCBA), in lieu of traditional electro-mechanical contactors and fuses and external current sensor, is disclosed. The associated monitoring, driving, protection and energy clamping circuitries, and thermal management design to enable high-current and safety-critical applications are also disclosed.
1 . A battery management system (BMS) printed circuit board assembly (PCBA) for managing a battery comprising:
a plurality of solid-state power transistors in back-to-back serial configuration configured to connect and disconnect the battery, and to function as resettable fuse,
a plurality of energy clamping circuits connected in parallel to the plurality of solid-state power transistors, the plurality of energy clamping circuits configured to provide an alternative current path when the plurality of solid-state power transistors are turned off,
a gate clamping circuit across a drain and gate of the plurality of solid-state power transistors, the gate clamping circuit configured to inject gate current to partially keep the plurality of solid-state power transistors in an active region and slow down the turn-off of the plurality of solid-state power transistors when a voltage across the plurality of solid-state power transistors and the plurality of energy clamping circuits exceeds a breakdown voltage of the gate clamping circuit,
gate drive circuitries configured to turn on and off the solid-state power transistors,
one or more shunt resistors configured for current sensing,
a battery monitoring application-specific integrated circuit (ASIC), and
a microprocessor,
wherein the battery monitoring ASIC and the microprocessor are configured to provide redundant overcurrent detection.
2 . The BMS PCBA of claim 1 , wherein the plurality of solid-state power transistors are arranged in a common source configuration.
3 . The BMS PCBA of claim 1 , wherein the plurality of solid-state power transistors comprise drain pins connected to large copper pads with vias to cool the solid-state power transistors through surrounding air convection.
4 . The BMS PCBA of claim 1 further comprising a metal clad or metal core printed circuit board (PCB).
5 . The BMS PCBA of claim 1 , wherein the gate drive circuitries comprise of a fast gate turn-off circuit configured to turn off the transistors when responding to an over-current fault.
6 . The BMS PCBA of claim 1 , wherein the gate drive circuitries comprise of a charge pump circuit configured to turn on and off the solid-state power transistors.
7 . The BMS PCBA of claim 1 further comprising a precharge circuit using MOSFET and resistors connected in parallel to one or more of the solid-state power transistors.
8 . The BMS PCBA of claim 1 further comprising an energy freewheeling circuit implemented across output positive and negative terminals of the BMS PCBA, the energy freewheeling circuit configured to dissipate inductive energy when the plurality of solid-state power transistors are turned off.
9 . The BMS PCBA of claim 1 further comprising a temperature monitor configure to detect an overheating of the plurality of solid-state power transistors and the one or more shunt resistors.
10 . The BMS PCBA of claim 9 further comprising one or more copper planes underneath the plurality of solid-state power transistors.
11 . The BMS PCBA of claim 9 wherein the temperature monitor comprises a surface mount thermistor that is thermally coupled to the plurality of solid-state power transistors and the one or more shunt resistors via a low impedance path through a printed circuit board (PCB) trace.
12 . The BMS PCBA of claim 11 , wherein the surface mount thermistor is connected via a standard comparator to the microprocessor.