Advanced Power Electronics Interface and Optimization for Fuel Cell Hybrid Electric Vehicles Applications

Student thesis: Doctoral Thesis


Due to rising concerns about environmental issues, such as global warming and
greenhouse gas emissions, as well as energy issues, automobile manufacturers are being
forced to shift their attention towards green energy power and clean vehicles. Electric
Vehicles (EVs), Hybrid Electric Vehicles (HEVs), Plug-in Hybrid Electric Vehicles
(PHEVs) and Fuel Cell Hybrid Electric Vehicles (FCHEVs) are more energy efficient and
cleaner than conventional vehicles.
FCHEVs and their plug-in configurations (called "PFCHEVs') can be considered
interesting alternatives to conventional vehicles. The FCHEVs and PFCHEVs comprise
a fuel cell (FC), energy storage systems (ESS), such as batteries and supercapacitors,
power electronics interfaces (such as DC/DC converters, DC/AC inverter and on-board
battery charger) and an electric motor. The major challenges for the development of the
FCHEVs and PFCHEVs are the power electronics interfaces, the sizing of the
powertrain components and the power flow control of the multiple energy sources. In
particular, the power electronics interfaces play an important role in the development of
FCHEVs and PFCHEVs. Consequently, the proper selection of the power electronics
interfaces (such as DC/DC converters, DC/AC inverter, and on-board battery charger)
and an appropriated energy/power control strategy can significantly optimize the
performance of FCHEVs and PFCHEVs. Therefore, a lot of research work has been
conducted to provide solutions for these challenges.
In this dissertation, a Novel Multi-Device Interleaved Boost Converter (MDIBC) has
been proposed for FCHEVs in order to optimize the drive system. The proposed
converter improves efficiency, reduces current and voltage ripples, and reduces the size
of the passive components, leading to a high reliability compared to other DC/DC
converter topologies. Furthermore, a generalized small-signal model has been
developed for PWM DC/DC converters, which has not been previously discussed. The
proposed DC/DC converter is compared to other converter topologies to verify its
dynamic performance. In addition, the proposed converter (MDIBC) is experimentally
validated with results obtained from a 30-kW prototype.
In the framework of this dissertation, new Multiple-Input Converter (MIC) concepts
have been proposed in order to integrate multiple-input DC sources (such as fuel cell,
battery and supercapacitor) together with a common DC-Link that are used in FCHEVs.
These concepts are an Interleaved Multiple-Input Power Converter (IMIPC) and a
Multi-Device Interleaved Multiple-Input Converter (MDI-MIC). The proposed
converters, IMPEC and MDI-MIC, can provide good solutions with high performance
for high-power applications for the combination of multiple-input DC sources, whose
voltage levels, current levels and power capacities are different. The proposed
converters and their control strategies have been successfully verified under different
operating conditions by extensive simulation results. As a result, the proposed
concepts are promising from the viewpoints of low cost, compact packaging, reliability
and centralized control requirements.
During this PhD work, a novel eight-switch inverter (ESI) has been designed and
experimentally implemented in a 30 kW prototype in order to integrate the DC/AC
inverter and on-board battery charger in one power electronics interface. The proposed
converter can function as a bidirectional single-phase AC/DC battery charger, and can
transfer electrical energy between the DC-link (i.e. connected with high-voltage battery)
and the electric traction system as three-phase DC/AC inverter. Consequently, the
proposed converter is compact and shows high performance in on-board battery
chargers and inverters in PFCHEV powertrains.
Integrating the DC/DC converters and DC/AC converter is an attractive solution to
interface a low-voltage DC source in the drivetrain of FCHEVs and PFCHEVs. In this
PhD work, new integrated power electronics interfaces (IPEIs) are proposed and tested
in order to realize the integration of the DC/DC converter, on-board battery charger
and DC/AC inverter together in the PFCHEV powertrain. The proposed IPEIs
incorporate the features of the interleaved DC/DC converter (IC), multi-device
interleaved DC/DC converter (MDIC) and ESI. These concepts can improve the
efficiency and reliability, can reduce the current and voltage ripples, and can reduce the
size of the passive and active components in the PFCHEV drivetrains compared with
other topologies. By means of simulation case-studies and experiments, the proposed
concepts of the IPEIs have been successfully verified and they promise significant
savings in component count, while providing high performance for PFCHEVs
compared to other topologies.
Finally, from the point of view of the control strategy, a methodology based on
particle swarm optimization (PSO) is proposed for FCHEVs in order to achieve the
optimal powertrain sizing as well as the optimal power sharing between multiple
energy sources. The proposed approach is used to minimize the hydrogen
consumption, and to minimize the cost, mass, and volume of the fuel cell and energy
storage system components in FCHEVs for different driving cycles. Furthermore, the
proposed methodology is compared to others methods under different driving cycles
and powertrains by extensive simulation results. By analyzing and comparing the
results, it is shown that the control strategy based on PSO can improve the performance
of the FCHEVs. These observations show that the proposed methodology can be
applied for a wide range of vehicular system applications.
The advanced power electronics interfaces and control strategies, which have been
proposed in this dissertation, can be considered as a step forward towards launching
new generations of vehicles.
Date of Award2 Jul 2012
Original languageEnglish
SupervisorJoeri Van Mierlo (Promotor), Maarten Kuijk (Jury), Rik Pintelon (Jury), Peter Van Den Bossche (Jury), Philippe Lataire (Jury), Alex Van Den Bossche (Jury) & Johan Gyselinck (Jury)


  • power electronics
  • electric vehicles
  • power converter

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