State-Feedback Design Framework for Current-Mode-Controlled Multiphase Boost Converters with Fast Transient Response and Adaptive On-Time

A synchronous multiphase boost converter remains a preferred choice in electric vehicles for a bidirectional interface between 12 V and 48 V battery packs. The converter is required to support high-performance computing loads with high slew-rate step loads and large input fluctuations during cold cranks. Current mode control is an effective solution for achieving fast transient response, active current balance, and high efficiency over a wide input voltage and load current range. However, the challenges remain in identifying suitable design techniques because of the right half plane zero and coupling among phases. This paper proposes a unified state-feedback design framework for the current mode control of a multiphase boost converter to achieve high bandwidth with adequate phase margin. The proposed technique scales with phase count and overcomes design trade-offs between bandwidth and phase margin that limit conventional output feedback-based design. The proposed design ensures robust supply disturbance rejection. Large-signal design achieves ultra-fast transient response using load feedforward. Peak-current-based adaptive on-time control is used to enhance light-load efficiency.