Digital Type II Compensation with Forced-Output Control of an Interleaved Two-Phase Coupled-Inductor Boost Converter

Coupled-inductor boost converters are under development for high-current, high-power applications ranging from automotive fuel cells to photovoltaics. In order to operate over the full load range of a dc-dc converter, the implemented controller must be capable of maintaining stability in both Continuous-Conduction Mode (CCM), and Discontinuous-Conduction Mode (DCM). This paper presents the development of a digital Type II compensator, implemented in the inner loop of an average-current-mode-control scheme. Two different Type II compensators are designed; one for CCM operation, and the other for DCM operation. Finally, a novel method called Forced-Output Control is implemented in order to greatly reduce the transient which would normally occur when switching compensators mid-operation. The Type II compensators and Forced-Output Control scheme are verified experimentally from a 1 kW coupled-inductor boost converter prototype.