Design of integrated inductors in multi-phase buck/boost converters including operation with deactivated phases

Inhalt:
Integration of coupled filter inductors on a common core reduces the phase-ripple currents in buck/boost multi-phase converters and improves their efficiency. Operation of these converters with deactivated phases leads to large dc fluxes and partial core saturation at high output power levels. However, converters for the automotive 48V/14V energy net must be fault-tolerant and additional MOSFET are often implemented to turn-off faulty half-bridges. This paper presents a design procedure for the integrated filter inductor of an automotive four-phase 48V/14V converter, including operation with deactivated phases. The design procedure is obtained from a detailed flux analysis. Simulations and measurements prove theoretical predictions and show the performance of the design.