Bidirectional Buck-Boost Integrated Converter for Plug-in Hybrid Electric Vehicles

Background and Objectives: Power electronics infrastructures play an important role in charging different types of electric vehicles (EVs) especially Plug-in Hybrid EVs (PHEVs). Designing appropriate power converters is the topic of various studies. Method: In this paper, a novel bidirectional buck-boost multifunctional integrated converter is presented which is capable of handling battery and fuel cell stack in plug-in hybrid electric vehicles.  The proposed converter has the ability to work in five different operating modes (Charging/Propulsion (only battery)/ Propulsion (battery and FC)/ Regenerative braking/ V2G). The introduced multifunctional two-stage converter has the ability to work in all the above-mentioned modes in buck- boost condition, the feature that does not exist in the previous works. It is possible to control active and reactive power by using the effective dual-loop PI control method which is introduced in this paper. Working as an on-board charger and DC-DC converter (which interfaced between power sources and motor drive system) causes a decrease in the counts of the total components and an increase in system efficiency. Results: Operation principle and steady-state analysis of each stage of the proposed converter in all operating modes are provided in detail and in order to design an appropriate applicable converter, the design considerations and procedure are also explained for capacitive and inductive components. The proposed converter is simulated in MATLAB/SIMULAIN environment and results are provided. Voltage and current waveforms in all operating conditions are provided with their transient. FFT analysis of the input current (in the operating modes in which the converter absorb or deliver power from/to the grid) is also mentioned. A reduced-scale setup of the presented converter is built and tested and experimental results confirm simulation ones. Conclusion: A bidirectional buck-boost integrated converter in PHEVs applications is introduced in this paper. The design procedure of the presented converter is provided and also an effective control method to control active and reactive power during charging and V2G modes is introduced. A comparison study of the proposed converter with other similar converters introduced in recent years in terms of the number of high-frequency switches in each mode is also done. Simulation and experimental results are also provided.