MIMO Control of a High-Step-Up Isolated Bidirectional DC-DC Converter

This paper proposes a multi-input multioutput (MIMO) digital control strategy for a bidirectional interleaved boost converter with coupled inductors, designed to operate as an interface between an ultra-capacitor and a high-voltage dc bus in a hybrid nano-grid. The control strategy keeps the high-voltage side dc-bus of the nano-grid stable when the voltage at the low-voltage side, connected to the ultra-capacitor, changes in a wide range. Bidirectional energy flow control with current protection is allowed too. The high-voltage regulation loop is closed around an inner, low voltage side current control loop. In parallel to these, a third, clamp voltage regulator is set to keep tight control over switch voltage stress. The paper discusses the controller organization, the design criteria, and shows the subsequent implementation on a general purpose digital control platform. The achievable performance is experimentally verified on a 1.5-kW converter prototype.