Modeling of Dc-dc Boost Converter in Discontinuous Conduction Mode Hafez Sarkawi (D1) 2016/06/20

Presentation Outline Introduction DCM Operation General Dc-dc Converter Averaged State-space DCM Model Dc-dc Boost Converter DCM Model Conclusion and Future Works

Presentation Outline Introduction DCM Operation General Dc-dc Converter Averaged State-space DCM Model Dc-dc Boost Converter DCM Model Conclusion and Future Works

1) Introduction The purpose of the dc-dc boost converter circuit is to draw power from the dc voltage source, and supply power to the load at a higher dc voltage value. This task is accomplished by first closing the switch to store energy in the inductor, and then opening the switch to transfer that energy to the capacitor, where it is available to the load. The discontinuous conduction mode (DCM) occurs when the converter is at light load (low current). Fig. 1 Dc-dc boost converter circuit

Presentation Outline Introduction DCM Operation General Dc-dc Converter Averaged State-space DCM Model Dc-dc Boost Converter DCM Model Conclusion and Future Works

2) DCM Operation DCM operation : the inductor current rises in the first interval when the switch is turned on, reaches a peak right before the switch is to be turned off, and resets to zero at the end of the second interval and remain zero until next switching occur. Fig. 2 Inductor current waveform in DCM Fig. 3 Three different modes for the DCM boost converter

Presentation Outline Introduction DCM Operation General Dc-dc Converter Averaged State-space DCM Model Dc-dc Boost Converter DCM Model Conclusion and Future Works

3) General Dc-dc Converter Averaged State-space DCM Model Piecewise-linear state-space model for the three different modes: Averaged model using SSA for above modes

Presentation Outline Introduction DCM Operation General Dc-dc Converter Averaged State-space DCM Model Dc-dc Boost Converter DCM Model Conclusion and Future Works

4) Dc-dc Boost Converter DCM Model State vector chosen for the dc-dc boost converter: State and input matrices: Averaged SSA DCM model: (1) Needs to be eliminated. Solution: Reflect using current and voltage

4) Dc-dc Boost Converter DCM Model (Cont.) Average inductor current Peak inductor current Subs. d2 into (1) New averaged SSA DCM model: (2)

4) Dc-dc Boost Converter DCM Model (Cont.) DC analysis Small signal analysis Subs. Using standard linearization techniques to (2), small signal model is given by: into (2) and solved for and

Presentation Outline Introduction DCM Operation General Dc-dc Converter Averaged State-space DCM Model Dc-dc Boost Converter DCM Model Conclusion and Future Works

4) Conclusion and Future Works Modeling of dc-dc boost converter operating in DCM has been presented. Future works will deal with the application of these modeling for dc-dc zeta converter and apply robust control technique to stabilize the converter.

Thank you! Hafez Sarkawi (D1) 2016/06/20