Efficiency Improvement of a Cascaded Buck and Boost Converter for Fuel Cell Hybrid Vehicles with Overlapping Input and Output Voltages
Fuel cell hybrid vehicles represent an alternative to battery electric vehicles and will gain importance in the future as they do not need large battery capacities and thus require less critical raw materials. Depending on the electric architecture, the voltage of the fuel cell stack and traction ba...
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-08-01
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| Series: | Inventions |
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| Online Access: | https://www.mdpi.com/2411-5134/7/3/74 |
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| author | Noass Kunstbergs Hartmut Hinz Nigel Schofield Dennis Roll |
| author_facet | Noass Kunstbergs Hartmut Hinz Nigel Schofield Dennis Roll |
| author_sort | Noass Kunstbergs |
| collection | DOAJ |
| description | Fuel cell hybrid vehicles represent an alternative to battery electric vehicles and will gain importance in the future as they do not need large battery capacities and thus require less critical raw materials. Depending on the electric architecture, the voltage of the fuel cell stack and traction battery may overlap. Accordingly, it is necessary to use a bidirectional DC–DC converter that connects the battery to the DC bus, which supports overlapping input and output voltages. Furthermore, these converters should be non-isolating in terms of compact design. Concerning complexity and controllability, the bidirectional cascaded buck and boost converter is preferable and is the subject of this study. Published literature presents the bidirectional cascaded buck and boost converter with high losses for overlapping input and output voltages, introducing two methods for this operation mode. The method selected for this study, namely buck + boost, uses two switches, whereby one switch has a fixed duty cycle. However, there is no appropriate investigation to determine the impact of this fixed duty cycle on converter efficiency to date. Furthermore, efficiency improvement is possible by switching frequency modulation, but current literature does not address this modulation method for overlapping input and output voltages. Therefore, this paper investigates a non-isolated hard-switched bidirectional cascaded buck and boost converter for fuel cell hybrid vehicles operating with up to 19.8 kW. The study focuses on determining the optimum fixed duty cycle and efficiency optimisation through a novel critical conduction mode with adapted switching frequency by utilising the load-dependent inductance of the inductor with powder cores. Measurements with an experimental setup validate the proposed modulation method with Si-IGBT half-bridge modules. The results demonstrate that a loss reduction of 39% is possible with switching frequency modulation and the optimum duty cycle compared to fixed switching frequency. As a result, the converter achieves high efficiencies of up to 99% and low device junction temperatures. |
| first_indexed | 2024-03-09T23:37:43Z |
| format | Article |
| id | doaj.art-272cdd12ff824432a700840cde38588a |
| institution | Directory Open Access Journal |
| issn | 2411-5134 |
| language | English |
| last_indexed | 2024-03-09T23:37:43Z |
| publishDate | 2022-08-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Inventions |
| spelling | doaj.art-272cdd12ff824432a700840cde38588a2023-11-23T16:56:43ZengMDPI AGInventions2411-51342022-08-01737410.3390/inventions7030074Efficiency Improvement of a Cascaded Buck and Boost Converter for Fuel Cell Hybrid Vehicles with Overlapping Input and Output VoltagesNoass Kunstbergs0Hartmut Hinz1Nigel Schofield2Dennis Roll3Faculty of Computer Science and Engineering, Frankfurt University of Applied Sciences, 60318 Frankfurt am Main, GermanyFaculty of Computer Science and Engineering, Frankfurt University of Applied Sciences, 60318 Frankfurt am Main, GermanyDepartment of Engineering and Technology, University of Huddersfield, Huddersfield HD1 3DH, UKFaculty of Computer Science and Engineering, Frankfurt University of Applied Sciences, 60318 Frankfurt am Main, GermanyFuel cell hybrid vehicles represent an alternative to battery electric vehicles and will gain importance in the future as they do not need large battery capacities and thus require less critical raw materials. Depending on the electric architecture, the voltage of the fuel cell stack and traction battery may overlap. Accordingly, it is necessary to use a bidirectional DC–DC converter that connects the battery to the DC bus, which supports overlapping input and output voltages. Furthermore, these converters should be non-isolating in terms of compact design. Concerning complexity and controllability, the bidirectional cascaded buck and boost converter is preferable and is the subject of this study. Published literature presents the bidirectional cascaded buck and boost converter with high losses for overlapping input and output voltages, introducing two methods for this operation mode. The method selected for this study, namely buck + boost, uses two switches, whereby one switch has a fixed duty cycle. However, there is no appropriate investigation to determine the impact of this fixed duty cycle on converter efficiency to date. Furthermore, efficiency improvement is possible by switching frequency modulation, but current literature does not address this modulation method for overlapping input and output voltages. Therefore, this paper investigates a non-isolated hard-switched bidirectional cascaded buck and boost converter for fuel cell hybrid vehicles operating with up to 19.8 kW. The study focuses on determining the optimum fixed duty cycle and efficiency optimisation through a novel critical conduction mode with adapted switching frequency by utilising the load-dependent inductance of the inductor with powder cores. Measurements with an experimental setup validate the proposed modulation method with Si-IGBT half-bridge modules. The results demonstrate that a loss reduction of 39% is possible with switching frequency modulation and the optimum duty cycle compared to fixed switching frequency. As a result, the converter achieves high efficiencies of up to 99% and low device junction temperatures.https://www.mdpi.com/2411-5134/7/3/74buck + boostDC–DC converterfuel cell hybrid vehiclesswitching frequency modulation |
| spellingShingle | Noass Kunstbergs Hartmut Hinz Nigel Schofield Dennis Roll Efficiency Improvement of a Cascaded Buck and Boost Converter for Fuel Cell Hybrid Vehicles with Overlapping Input and Output Voltages Inventions buck + boost DC–DC converter fuel cell hybrid vehicles switching frequency modulation |
| title | Efficiency Improvement of a Cascaded Buck and Boost Converter for Fuel Cell Hybrid Vehicles with Overlapping Input and Output Voltages |
| title_full | Efficiency Improvement of a Cascaded Buck and Boost Converter for Fuel Cell Hybrid Vehicles with Overlapping Input and Output Voltages |
| title_fullStr | Efficiency Improvement of a Cascaded Buck and Boost Converter for Fuel Cell Hybrid Vehicles with Overlapping Input and Output Voltages |
| title_full_unstemmed | Efficiency Improvement of a Cascaded Buck and Boost Converter for Fuel Cell Hybrid Vehicles with Overlapping Input and Output Voltages |
| title_short | Efficiency Improvement of a Cascaded Buck and Boost Converter for Fuel Cell Hybrid Vehicles with Overlapping Input and Output Voltages |
| title_sort | efficiency improvement of a cascaded buck and boost converter for fuel cell hybrid vehicles with overlapping input and output voltages |
| topic | buck + boost DC–DC converter fuel cell hybrid vehicles switching frequency modulation |
| url | https://www.mdpi.com/2411-5134/7/3/74 |
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