Design of a Universal Compact Low Voltage Vehicle Control Unit for Formula Electric Vehicles

Abstract

As the electric vehicle (EV) portion of annual car production continues to increase, EV designs are increasingly able to dictate industry standards and supply chains. At the same time, EVs have become increasingly prevalent in formula-style racing. EV high voltage (HV) powertrains have been critical in advancing EVs in both the commercial and high-performance spheres, but this has often come at the cost of underdeveloped low-voltage (LV) systems, which continue to be largely based on traditional internal combustion engine (ICE) vehicle designs. In anticipation of the rapidly growing popularity of EVs, this project seeks to propose an EV LV vehicle control unit (VCU) design that is compact and universally applicable to US-based formula student competitions, specifically FSAE and FH+E. The presented VCU is composed of a power distribution network (PDN), shutdown circuit (SDC), embedded computing (ECP), electrical interface (INT), and packaging (PAC) subsystem. These subsystems take advantage of the unique characteristics of EVs to implement ideas like using both of the EV’s HV and LV batteries to power the LV system, using higher base LV voltages, incorporating a comprehensive safety system, integrating a powerful central vehicle computer, and provisioning for an abundance of vehicle sensor data, guided by the goals of maximizing efficiency, centralization, density, and data-richness, without sacrificing rules-compliance, compactness, and user-friendliness. The design fills a unique niche in the formula student space, achieving a high degree of feature-density and multi-system integration even as compared to designs from industry and academia. A practical design prototype is then described, manufactured, and evaluated on its merits. Despite some errors in the prototyping process, the design is found to be viable, performing well with regards to voltage ripple, power efficiency, thermal performance, and EMI, while still abiding by the FSAE and FH+E rulesets and providing ample computing capabilities. At the same time, the complete device’s volume, mass, and cost is found to be reasonable, even by austere formula student standards. Widespread adoption of the presented EV LV VCU architecture may further accelerate EV growth with increased performance, reduced weight, and decreased costs, especially in the formula student domain, but perhaps even in the consumer sphere with additional modifications, advancing the objective of a more performant and cleaner future.