Design and Implementation of a DC–DC Resonant LLC Converter for Electric Vehicle Fast Chargers
Abstract
:1. Introduction
2. Design of the DC–DC LLC Resonant Converter
2.1. Design of the Isolated DC–DC LLC Resonant Converter
2.2. Advantages and Disadvantages of the Isolated DC–DC Resonant LLC Converter
2.3. Soft Switching vs. Hard Switching
2.4. High-Frequency Transformer Design
- Select the core with the “product of area” method using the following equation, where is the input power, is the maximum magnetic flux density, k is the packing factor, and J is the current density:
- 2.
- Determine the number of turns on the primary and secondary sides of the HFT (N1 and N2, respectively) using the following equations, where S represents the cross-sectional area of the magnetic core:
- 3.
- Calculate the cross-sectional area of the wire for and through the following equations, where I1 and I2 represent the current in the primary and secondary windings of the transformer, respectively. ID1 and ID2 represent the current in the diodes, and ILrms represents the rms value of the current in the resonant tank:
- 4.
- Calculate the winding losses (Pp) and the losses in the HFT core (Ps) through several steps to determine the HFT’s global efficiency.
- 4.1.
- Winding losses:
- 4.2.
- Find the HFT core losses using the datasheet for operating conditions.
- 4.3.
- Total sum of losses and calculation of HFT efficiency ():
3. Computational Validation
3.1. Operating Principle Validation
3.2. ZVS and ZCS Control Simulations
3.3. Influence of Power and Frequency on Converter Operation
4. HFT Development and Prototype Assembly
4.1. Implementation of a Real HFT
- Design 1: Wrap 12 turns of the primary and 12 turns of the secondary on top on both sides.
- Design 2: Wrap 6 turns plus 6 primary turns, and then, on top, 6 turns plus 6 secondary turns, repeating on both sides.
- Design 3: Wind 12 primary turns and another 12 secondary turns.
- Design 4: Wind 12 turns plus 12 turns of the primary on one side and 12 turns plus 12 turns on the other side of the secondary.
- Design 5: Wind 12 turns of the primary plus 12 turns of the secondary on each side, using the larger side.
- Design 6: Wind 12 turns plus 12 turns in parallel of the primary plus 12 turns of the secondary on both sides.
- Design 7: Wind 12 turns of the primary on one side plus 12 turns of the secondary on the other side, and then, on the larger side, wind 12 turns of the primary plus 12 turns of the secondary in parallel.
- Design 8: Wind 12 turns of the primary plus 12 turns of the secondary in parallel on one side, and then, 12 turns of the primary plus 12 turns of the secondary on the other.
- Design 9: Wrap 12 turns of the secondary, 12 turns of the primary, 12 turns of the secondary, and 12 turns of the primary divided among the 4 sides.
- Design 10: Wind 12 turns of the primary, 12 turns of the primary, 12 turns of the secondary, and 12 turns of the secondary, changing the order of Design 9.
4.2. Prototype Assembly
5. Experimental Results
5.1. Test with First HFT Design
5.2. Test with Second HFT Design
5.3. Efficiency Results
6. Conclusions
Author Contributions
Funding
Data Availability Statement
Conflicts of Interest
References
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Advantages | Disadvantages | |
---|---|---|
Interleaved Three-Phase LLC Resonant |
|
|
DAB |
|
|
Multilevel |
|
|
LLC Resonant |
|
|
Parameters | Value |
---|---|
Input voltage | 900 V |
Output voltage | 900 V |
Operating power | 5 kW to 25 kW |
Switching frequency, fsw | 100 kHz |
HFT transformation ratio | 1:1 |
MOSFET model | G3R30MT12J |
Diode model | GD30NPS12J |
Output capacitor | 10 µF |
Design 1 | 144 µH | 154 µH | 1.47 µH |
Design 2 | 179 µH | 180 µH | 12.86 µH |
Design 3 | 176 µH | 177 µH | 19.2 µH |
Design 4 | 196 µH | 199 µH | 70 µH |
Design 5 | 163 µH | 175 µH | 1.7 µH |
Design 6 | 156 µH | 157 µH | 1.32 µH |
Design 7 | 163 µH | 163 µH | 3 µH |
Design 8 | 157 µH | 158 µH | 2.5 µH |
Design 9 | 158 µH | 196 µH | 18 µH |
Design 10 | 168 µH | 170 µH | 32 µH |
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Rocha, J.; Amin, S.; Coelho, S.; Rego, G.; Afonso, J.L.; Monteiro, V. Design and Implementation of a DC–DC Resonant LLC Converter for Electric Vehicle Fast Chargers. Energies 2025, 18, 1099. https://doi.org/10.3390/en18051099
Rocha J, Amin S, Coelho S, Rego G, Afonso JL, Monteiro V. Design and Implementation of a DC–DC Resonant LLC Converter for Electric Vehicle Fast Chargers. Energies. 2025; 18(5):1099. https://doi.org/10.3390/en18051099
Chicago/Turabian StyleRocha, Joao, Saghir Amin, Sergio Coelho, Gonçalo Rego, Joao L. Afonso, and Vitor Monteiro. 2025. "Design and Implementation of a DC–DC Resonant LLC Converter for Electric Vehicle Fast Chargers" Energies 18, no. 5: 1099. https://doi.org/10.3390/en18051099
APA StyleRocha, J., Amin, S., Coelho, S., Rego, G., Afonso, J. L., & Monteiro, V. (2025). Design and Implementation of a DC–DC Resonant LLC Converter for Electric Vehicle Fast Chargers. Energies, 18(5), 1099. https://doi.org/10.3390/en18051099