Wide Range Digital Control for Three-Level Buck Converters with Sensorless Flying-Cap Voltage Balancing

This paper proposes a wide-range multi-sampling peak digital predictive current mode controller (DPCMC) for a 3-level flying capacitor (3LFC) Buck DC-DC converter. The main advantage of this controller is the ability to cover the entire voltage conversion ratio range without encountering any flying capacitor (FC) voltage instability issues. The proposed control strategy maintains the FC voltage balanced without the need for measurement, estimation, and no dedicated actions of the control systems are required. The proposed modification of the multi-sampling fast-update DPCMC performs effectively also at the operating point where the output voltage is half of the input voltage. This condition is generally avoided by existing control strategies. The performance of the algorithm is demonstrated through simulations and experimental tests on a 3LFC Buck converter prototype.