An Optimization Design of the Diode Clamped Multi-Level Converter for Coaxial Inductive Power Transfer on the Low Voltage DC Micro-grid

Abstract

This proposed paper aims for the high efficiency contactless power transfer in household dc power distribution. A 300 W five-level diode clamped multi-level converter with 300 Vdc input dc link bus is employed for the power transferring task and the output voltage range is controlled at 48 Vdc. The inner and outer solenoid coils are used for inductive power transfer (IPT) transformer with the 200 kHz switching frequency for designed power density. Therefore, to achieve the converter efficiency above 95%, the LLC series resonant with fundamental harmonic analysis (FHA) and the calculated switching angles are used as an optimized tool for designing the system resonant tank. The validations of this approached topology are illustrated in both MATLAB/Simulink simulation and implementation.

Fig. 1. Coaxial contactless transformer ideal concept design

Fig. 2. The structure of DCML with IPT schematic

Fig. 3. (a) Simplified system circuit (b) Linear sinusoidcircuit

Fig. 4. Voltage gain vs nomalized frequency

Fig. 5. Operation boundary design

Fig. 6. The five-level diode clamped mutilevel converterscheme

Fig. 7. Upper portion switching toplogy

Fig. 8. Switching angles vs modulation index

Fig. 9. Operation mode of DCML and resonant circuit

Fig. 10. Operation mode 1(Negative current)

Fig. 11. Operation mode 1(Positive current)

Fig. 12. Operation mode 2

Fig. 13. Operation mode 3

Fig. 14. Operation mode 4

Fig. 15. Operation mode 5 (Positive current)

Fig. 16. Operation mode 5 (Negative current)

Fig. 17. Operation mode 6

Fig. 18. Operation mode 7

Fig. 19. Operation mode 8

Fig. 20. The SHE %THD vs modulation index

Fig. 21. 3rd harmonic elimination vs modulation index

Fig. 22. 5th harmonic elimination vs modulation index

Fig. 23. VDS1 vs S1 current

Fig. 24. VDS2 vs S2 current

Fig. 25. VDS3 vs S3 current

Fig. 26. VDS4 vs S4 current

Fig. 27.Switching gain boundary

Fig. 28. VDS1 and current at 100 W and 300W

Fig. 29. The DCML output voltage and voltage harmonicspectrum (CH I 200 V/DIV, FFT 50.0V/DIV, 312.5kHz/DIV, Sa 12.5 NSa)

Fig. 30. VDS1 and current of S1 (ID1 2A/DIV, VDS1 50V/DIV)

Fig. 31. VDS2 and current of S2 (ID2 2A/DIV, VDS2 50V/DIV)

Fig. 32. VDS3 and current of S3 (ID3 2A/DIV, VDS3 50V/DIV)

Fig. 33. VDS4 and current of S4 (ID4 2A/DIV, VDS4 50V/DIV)

Fig. 34. Prototype experimental setup

Fig. 35. Switching losses in DCML swtiching devices

Fig. 36. The DCML ZVS under load variation (Ir 10A/DIV,Vprimary 100V/DIV, T 2 μS/DIV)

Table 1. LLC Series resonant system gain design

Table 2. Diode clamped multi-level switching state

Table 3. Specification of the prototype converter

Table 4. Diode clamped multi-level converter components

Table 5. Contactless transformer specification