Numerous Patterns of Inductor Currents in DCM of Coupled SIDO Boost Converter

The coupled inductor single input dual output (CI-SIDO) converters have applications in portable electronic devices, electric vehicles, hybrid energy systems, renewable energy systems, etc. The coupled inductors present in the converter helps to reduce the physical size of the converter and also helps to reduce the ripples in input and inductor currents. The CI-SIDO converters are generally operated in continuous conduction mode (CCM) because of the load-independent input-output voltage relations and control. However, once the converter is designed and used, loads of the converter may reduce, leading to the discontinuous conduction mode (DCM). Therefore, the DCM analysis is essential when the converter is used in practical applications. This paper presents the DCM operation of the CI-SIDO boost converter. The DCM operations depend on the inductor current waveforms. As illustrated in the literature, the CI-SIDO boost converter has numerous inductor current waveforms depending on the voltages and coupled inductor parameters. As the analysis of each waveform in DCM is very tedious, this paper presents the DCM operation when the two inductor current slopes are opposite to each other. With these slope conditions, it is found the CI-SIDO boost converter has eight different DCM waveform possibilities. Each waveform is analyzed separately, and the output-input voltage relations are found for each case. The analysis is verified by simulations in Matlab/Simu link.