Enhancement of DC-bus voltage regulation in cascaded converter system by a new sensorless load current feedforward control scheme

Abstract

It is generally known that, with conventional PI control, the stability and dynamic response performances of a power converter cannot be optimized simultaneously. To overcome this limitation, an uncertainty and disturbance estimator assisted sensorless load current feedforward control for dc-bus voltage regulation is presented to achieve fast dynamic response to load variations while stability is guaranteed by tuning PI controller. The proposed control scheme is verified on a cascaded converters system comprising a front end dc-dc DAB converter followed by a single-phase inverter as an illustrative case. Load-current feedforward is used to enhance the transient response of the front end DAB converter while an uncertainty and disturbance estimator is used to compensate for any non-idealities arising from model uncertainties and error in load current estimation. To validate the proposed control scheme, experimental results obtained from a 250-W cascaded converter system are presented and compared rigorously to the performance of conventional PI control.