Author Contributions
Conceptualization, Y.E.B. and D.S.; data curation, Y.E.B.; formal analysis, Y.E.B. and D.S.; funding acquisition, J.A.C. and J.C.; investigation, Y.E.B. and P.A.; methodology, Y.E.B., J.A.O. and P.A.; project administration, M.V., J.A.O., P.A. and J.C.; resources, G.M. and J.C.; software, Y.E.B.; supervision, M.V., J.A.O. and P.A.; validation, Y.E.B., U.B. and G.M.; visualization, Y.E.B.; writing—original draft, Y.E.B.; writing—review & editing, Y.E.B., D.S. and P.A.
Figure 1.
Aircraft active isolated rectifier architecture.
Figure 1.
Aircraft active isolated rectifier architecture.
Figure 2.
Isolated LLC full-bridge with full-bridge diode rectifier.
Figure 2.
Isolated LLC full-bridge with full-bridge diode rectifier.
Figure 3.
(a) LLC equivalent circuit (simplified first harmonic approximation (FHA)), (b) LLC voltage gain () at different inductance ratios () and quality factors ().
Figure 3.
(a) LLC equivalent circuit (simplified first harmonic approximation (FHA)), (b) LLC voltage gain () at different inductance ratios () and quality factors ().
Figure 4.
LLC converter modes: (a) below resonance; (b) at resonant; (c) above resonance.
Figure 4.
LLC converter modes: (a) below resonance; (b) at resonant; (c) above resonance.
Figure 5.
LLC converter total normalized power losses () at 10 kW output power. Including primary and secondary transistors and transformer. (a) for (b) for .
Figure 5.
LLC converter total normalized power losses () at 10 kW output power. Including primary and secondary transistors and transformer. (a) for (b) for .
Figure 6.
LLC converter total normalized power losses () at 500 W output power, including primary and secondary transistors and a transformer; (a) for ; (b) for .
Figure 6.
LLC converter total normalized power losses () at 500 W output power, including primary and secondary transistors and a transformer; (a) for ; (b) for .
Figure 7.
(a) Modified FHA LLC equivalent circuit with series resistance; (b) time-based (TB) LLC circuit with series resistance.
Figure 7.
(a) Modified FHA LLC equivalent circuit with series resistance; (b) time-based (TB) LLC circuit with series resistance.
Figure 8.
Comparison of the gain () for the modified FHA and TB models (with simulation) with series resistance at different output powers (a) for (b) for .
Figure 8.
Comparison of the gain () for the modified FHA and TB models (with simulation) with series resistance at different output powers (a) for (b) for .
Figure 9.
Equivalent circuit for transformer and external parasitics.
Figure 9.
Equivalent circuit for transformer and external parasitics.
Figure 10.
Modified FHA LLC equivalent circuit with distributed inductances and resistances.
Figure 10.
Modified FHA LLC equivalent circuit with distributed inductances and resistances.
Figure 11.
TB LLC circuit with distributed inductances and resistances.
Figure 11.
TB LLC circuit with distributed inductances and resistances.
Figure 12.
Comparison of the gain (
) for the series resistance model (
Figure 5a) and distributed model (
Figure 5b) with the FHA model and time-based simulations: (
a) series resistance model gain at different powers and inductance ratios (
Figure 6); (
b) distributed model gain at different powers and inductance ratios.
Figure 12.
Comparison of the gain (
) for the series resistance model (
Figure 5a) and distributed model (
Figure 5b) with the FHA model and time-based simulations: (
a) series resistance model gain at different powers and inductance ratios (
Figure 6); (
b) distributed model gain at different powers and inductance ratios.
Figure 13.
Zero voltage switching (ZVS) regions of the LLC converter.
Figure 13.
Zero voltage switching (ZVS) regions of the LLC converter.
Figure 14.
Time-based (TB) simulated currents of each mode and close-up of the dead-time transition for different LLC converter operation modes.
Figure 14.
Time-based (TB) simulated currents of each mode and close-up of the dead-time transition for different LLC converter operation modes.
Figure 15.
Time-based model simulations: inductive charge () and transistor output capacitor charge ( ), where iZVS stands for incomplete ZVS. (a) for ; (b) for .
Figure 15.
Time-based model simulations: inductive charge () and transistor output capacitor charge ( ), where iZVS stands for incomplete ZVS. (a) for ; (b) for .
Figure 16.
Proposed auxiliary circuit.
Figure 16.
Proposed auxiliary circuit.
Figure 17.
FHA equivalent circuit with auxiliary circuit.
Figure 17.
FHA equivalent circuit with auxiliary circuit.
Figure 18.
Auxiliary circuit current and voltage and auxiliary capacitor voltage ripple.
Figure 18.
Auxiliary circuit current and voltage and auxiliary capacitor voltage ripple.
Figure 19.
Auxiliary circuit maximum inductance ratio () design criteria.
Figure 19.
Auxiliary circuit maximum inductance ratio () design criteria.
Figure 20.
Design II: gapped transformer for , with a custom core and the same winding configuration and scale.
Figure 20.
Design II: gapped transformer for , with a custom core and the same winding configuration and scale.
Figure 21.
Design I: forward-type transformer for : planar E-core and 200 μm copper foil.
Figure 21.
Design I: forward-type transformer for : planar E-core and 200 μm copper foil.
Figure 22.
LLC full-bridge with a series parallel transformer configuration and two output-synchronous full-bridges.
Figure 22.
LLC full-bridge with a series parallel transformer configuration and two output-synchronous full-bridges.
Figure 23.
10 kW prototype.
Figure 23.
10 kW prototype.
Figure 24.
Experimental results: secondary transformer current (magenta and black), input resonant current (cyan), input voltage bridge (blue); (a) at 5 kW of output power; (b) at 10 kW of output power.
Figure 24.
Experimental results: secondary transformer current (magenta and black), input resonant current (cyan), input voltage bridge (blue); (a) at 5 kW of output power; (b) at 10 kW of output power.
Figure 25.
(a) Measurement setup including auxiliary circuit; (b) ZVS experimental results at 500 W.
Figure 25.
(a) Measurement setup including auxiliary circuit; (b) ZVS experimental results at 500 W.
Figure 26.
ZVS experimental results: (a) at 5 kW (b) at 10 kW.
Figure 26.
ZVS experimental results: (a) at 5 kW (b) at 10 kW.
Figure 27.
Experimental results without auxiliary circuit at 5 kW.
Figure 27.
Experimental results without auxiliary circuit at 5 kW.
Figure 28.
Experimental results: (a) efficiency at different output powers with (blue and yellow) and without (green and red) the auxiliary circuit, (b) close-up of the efficiency with the auxiliary circuit.
Figure 28.
Experimental results: (a) efficiency at different output powers with (blue and yellow) and without (green and red) the auxiliary circuit, (b) close-up of the efficiency with the auxiliary circuit.
Table 1.
Isolated DC/DC converter specification.
Table 1.
Isolated DC/DC converter specification.
Input Voltage | Output Voltage | Output Power | Output Current |
---|
400 V | 28 V | 10 kW | 360 A |
Table 2.
LLC converter normalized parameters.
Table 2.
LLC converter normalized parameters.
Normalized frequency | Inductance ratio |
| |
Load quality factor | Normalized voltage gain |
| |
Table 3.
Breakdown of losses, volume, and temperature of the two magnetic component designs.
Table 3.
Breakdown of losses, volume, and temperature of the two magnetic component designs.
| Transformers 1 | Auxiliary Inductor | Total Losses 1 | Total Volume 1 |
---|
Power Loss | Δθ | Volume | Power Loss | Δθ | Volume |
---|
PCu | PFe | PCu | PFe |
---|
Design I | 9.8 W | 13 W | 61 °C | 0.18 dm3 | 2.0 W | 2.2 W | 55 °C | 0.13 dm3 | 49.8 W | 0.49 dm3 |
Design II | 25.5 W | 18 W | 101 °C | 0.37 dm3 | - | - | - | - | 87 W | 0.74 dm3 |
Table 4.
Normalized parameters of the prototype.
Table 4.
Normalized parameters of the prototype.
Q (500 W) | Q (5 kW) | Q (10 kW) | QS | m | mx | fn | fxn |
---|
0.02 | 0.18 | 0.36 | 7.5 | 215 | 12.5 | 0.99 | 0.023 |
Table 5.
Parameters of the prototype.
Table 5.
Parameters of the prototype.
Lr | Cr | Lm | Lx | Cx | Rs | fr | fs |
---|
7.11 μH | 349 nF | 2 × 750 μH | 74 μH | 60 μF | 602 mΩ | 102 kHz | 101 kHz |
Table 6.
Prototype components.
Table 6.
Prototype components.
Component | Reference | Type | Quantity |
---|
Input capacitor | B32778G8606K | Film | 5 |
Primary transistors | IPW65R037C6 | Coolmos | 8 |
Resonant capacitor | C4532C0G2E473J320KA | Multilayer Ceramic | 6 |
C3225C0G2E103J160KA | 3 |
Transformer core | Planar E-core | Ferrite | 2 |
Transformer winding | Copper foil | 200 μm | - |
Secondary transistors | IPP10004S2L-03 | Optimos | 32 |
Output capacitors | B32774D4226J000 | Film | 12 |
Auxiliary inductor core | E65/32/27 | Ferrite | 1 |