LLC Resonant Converter Topologies For Plug-In Electric Vehicle Battery Charging
Recent improvements in battery technology and reduction in price have intensified interests in electrical vehicles (EVs) as these provide best means for pollution free and efficient transportation necessary for the sustainable development of the whole world. In near future, plug-in electrical veh...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2017
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| Subjects: | |
| Online Access: | http://eprints.usm.my/46155/1/LLC%20Resonant%20Converter%20Topologies%20For%20Plug-In%20Electric%20Vehicle%20Battery%20Charging.pdf |
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| Summary: | Recent improvements in battery technology and reduction in price have
intensified interests in electrical vehicles (EVs) as these provide best means for
pollution free and efficient transportation necessary for the sustainable development
of the whole world. In near future, plug-in electrical vehicles (PEVs), which are
equipped with on-board chargers, are expected to dominate the automobile market.
Most commonly used on-board chargers consist of two stages with AC/DC converter
as first stage and DC/DC converter as second stage. This thesis focuses on second
stage whose function is to regulate charging voltage and current in accordance with
battery’s charging requirements. The terminal voltage of EV battery varies over wide
range during usage and it may discharge up to normally depleted or deeply depleted
states. Therefore, the main challenge for DC/DC converter designer is to realize wide
range of output voltage and current while maintaining good efficiency so that the
converter is able to revive deeply depleted battery. To this end, this thesis contributes
five novel topologies of LLC resonant converter for the DC/DC stage of on-board PEV
battery charger which are: double LLC tank resonant converter, double LLC tank
resonant converter with hybrid-rectifier, hybrid-bridge LLC resonant converter,
hybrid-bridge LLC resonant converter with hybrid-rectifier, and interleaved LLC
resonant converter with series connected voltage doublers. The first topology uses
frequency control to achieve only depleted battery charging voltage range. Whereas,
the other four topologies use mode changing with switching frequency control to
extend the output voltage range for reviving deeply depleted battery, compared with
conventional counterparts which use complex control techniques. Moreover, all the
proposed topologies operate below resonance frequency for most extensively used
normal battery charging range, therefore, power switches operate with ZVS and
rectifier diodes with ZCS. The proposed topologies are designed for charging lithiumion
PEV battery pack with terminal voltage as 420V when fully charged, 250V when
depleted, and 100V or less when deeply depleted. The circuit configuration, analysis
of operation, gain characteristics and design procedure of all the topologies are
presented in details. Finally, all the proposed topologies are implemented and tested in
laboratory and also simulated using MATLAB Simulink environment with 400V DC
input and 1.5 kW maximum output power. The captured experimental and simulation
results are presented in this thesis for validation of operation and performance of
proposed converter topologies. The presented results showed that the four proposed
topologies can effectively charge both normally depleted as well as deeply depleted
battery, while the first topology can achieve only normally depleted battery voltage
range. On the other hand, last two topologies have shown widest output voltage range
of 50V–420V. Therefore, last two topologies have the ability to charge even very
deeply depleted batteries. All the proposed topologies have peak efficiency higher than
95% at peak output power. However, the last topology which is interleaved LLC
resonant converter with voltage doubler rectifier has highest efficiency of 95.65%.
Moreover, this topology also has widest output voltage range of 50V–420V, so it can
be considered as the best one among all the proposed topologies. |
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