Loop-Shaping Control Design for a New Modular Integrated On-Board EV Charger with RHP Zero Compensation

Abstract

This paper presents the control design of a new modular integrated on-board charger (MIOBC) for electric vehicle (EV) applications. Unlike traditional EV systems with a single high-voltage (HV) battery, charger, and motor controller, the proposed MIOBC modularises both the battery and power converters, enhancing safety, controllability, and fault-ride-through (FRT) capability. Integrating the traction inverter with the on-board charger (OBC) reduces system size and weight while enabling seamless operation in three modes: charging, acceleration, and deceleration. The MIOBC employs single-stage Cuk-based converter topologies as submodules (SMs), which provide continuous input and output currents, handle a wide range of input voltages, and produce low electromagnetic interference (EMI). To address control challenges posed by right-half-plane (RHP) zeros in Cuk converters, loop-shaping techniques are applied using proportional-integral (PI), proportional-resonant (PR), and lead-lag compensators. These methods ensure sufficient phase margin (PM) and gain margin (GM) for robust, stable performance within the desired bandwidth (BW). This paper details the operating principles, controller design, and efficiency analysis. A 3 kW prototype was tested using Lancaster University's Formula Student (FS) racing car, demonstrating not only the robustness of the control strategy under partial faults in battery segments but also confirming the MIOBC system's ability to achieve a tested peak efficiency of 94.8% across a range of output powers.