Control of a dc-dc Z-source driver used as a Synchronous Machine excitation system

This article presents a high-performance control strategy for a dc-dc Z-source converter used as the excitation-driver of a Flywheel Energy Storage System (FESS). One possible electromechanical interface for these systems is the Synchronous Machine. Its field winding permits direct management of the magnetization during speed variations. The common dc-link scheme for the dc-ac armature converter and dc-dc field converter is used to drive the FESS. A more efficient excitation system could be obtained using a converter with boosting capabilities. The Z-source converter in combination with the proposed multi-loop control law can achieve the desired voltage swing and high-performance tracking of the reference. This control algorithm makes use of the standard duty cycle and the shoot-through duty cycle of the Z-source converter as independent manipulated inputs. Preliminary experimental results are presented, which show the potential of the controller for tracking typical waveforms.