A Modular Battery System for Integrated AC, DC, and Auxiliary Outputs in Electric Vehicles

Conventional electric-vehicle battery systems are designed primarily to feed traction inverters and typically require separate converters for auxiliary loads, increasing hardware complexity, cost, and volume. This paper introduces a modular series–parallel reconfigurable battery that simultaneously delivers a main high-voltage AC or DC port as well as isolated low-voltage DC auxiliaries using the same hardware stack. Each auxiliary output requires only a single transformer and diode, while a phase-shifted carrier modulation scheme time-decouples the power paths, enabling independent regulation of the main and auxiliary ports without relays or extra conversion stages. The main port operates bidirectionally, supporting both traction and single-phase grid charging through a minimal LC filter and phase-shifted PWM. A small-signal model of the auxiliary loop provides analytical PI tuning rules to ensure stability and fast transient response. Experimental validation with a three-module prototype confirms 95% efficiency, <5% ripple in voltage and current, and ~10 ms settling time for the auxiliary port. Compared with representative onboard charger architectures, the proposed design achieves reduced part count, sensing, and control complexity while maintaining full modularity, scalability, and native multiport capability.

Duke Scholars

Author Stefan M Goetz Psychiatry & Behavioral Sciences, Behavioral Medicine & Neur ...