Battery Management System

Abstract

This report details the design and implementation of a custom battery management system, tailored to the needs of the Delft Hyperloop dream team. The goal of the custom battery management system is development time reduction for future Delft Hyperloop teams, modularity which allows prototyping with various battery sizes and compliance with the rules and regulations of the hyperloop competition. The core functionalities of the battery management system include safety cell monitoring, cell group balancing and communication. Cell group balancing entails the determination of the amount of charge present in a cell group and consequently, taking action which leads to all cell groups having an equal amount of charge, this ensures performance, longevity and safety of the battery pack.

The battery management system discussed in this report, consists of a prototype printed circuit board which can manage up to 18 battery cell groups. The prototype is centred around a battery stack monitor integrated circuit, which allows high voltage measurement, balancing control and isolated communication. The integrated circuit supports 18 cell inputs with as many cell balancing outputs. The cell balancing outputs drive PMOS transistors which allow excess energy in cell groups to be dissipated in special resistors. Furthermore, a multiplexer is present on the prototype, which allows sixteen cell temperature measurement inputs to the battery stack monitor integrated circuit. Finally, a shunt resistor is present on the prototype, allowing for an accurate current measurement. The prototype has been developed with modularity in mind, the circuit allows to be chained up with multiple circuits of the same type, allowing the management of potentially up to hundreds of battery cell groups.