Date of Award

Spring 1994

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)


Electrical and Computer Engineering

First Advisor

Arkadan, Abdul-Rahman

Second Advisor

Brown, Ronald H.

Third Advisor

Heinen, James A.


The motivation for this work result from a need to develop a practical DC-DC converter that operates at the boundary between continuous and discontinuous inductor current. Such a converter is a critical-conduction mode converter. The critical-conduction converter has advantages over fixed-frequency converters that operate strictly in the discontinuous mode in that the peak currents are lower. This advantage motivated the development of a critical-conduction converter. In order to develop the critical-conduction converter, a need for continuous time behavioral models resulted. State Space Averaging is a well known approach to the development of a continuous time behavioral model but has not been previously applied to the critical-conduction converter. Next, the problem of output voltage "run-away" when the load is removed from the output of a critical-conduction converter needed to be addressed. This motivated the development of a new operation mode called bi-directional constant-off-time. In the thesis, the bidirectional constant-off-time converter is introduced. The bi-directional constant-off-time converter operates in a well behaved manner with the load removed. The bi-directional constant-off-time operation is easily combined with the critical-conduction converter to form a dual mode converter. The dual mode operation can then be applied to achieve a practical implementation of a DC-DC converter. This thesis discusses such an implementation.



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