Auto-resonant Control of the H-Bridge Resonant Converter for Inductive Power Transfer Applications

Francesca Grazian, Peter van Duijsen, Bart Roodenburg, Thiago Batista Soeiro, Pavol Bauer

Research output: Chapter in Book/Conference proceedings/Edited volumeConference contributionScientificpeer-review

1 Citation (Scopus)
76 Downloads (Pure)


In inductive power transfer applications that use resonant compensation networks, the commonly employed H-bridge inverter should be kept operating in soft-switching to ensure high power efficiency and low irradiated electromagnetic noise. To achieve so, the zero-crossing detection circuit for the resonant current or voltage must be fast and accurate in any operating condition. This paper researches the concept of an auto-resonant control for the typical H-bridge resonant converter used in wireless charging systems. In the method proposed here, the reference levels for the zero-crossing detection of the inverter's current are automatically adapted depending on the slope of the current itself at the zero-crossing. In this way, it is possible to compensate for the circuit delay even in the presence of parameters' variation and to ensure that the soft-switching is always maintained. The functionality of this control method is proven first mathematically, and then with circuit simulations. The core steps for the implementation are described with the support of functional blocks. Finally, the system start-up strategy is explained, which uses an auxiliary timed oscillator to modulate the inverter with a fixed 50% duty cycle at a higher frequency than the nominal. This guarantees that the start-up is in the inductive region and, thus, the zero-voltage switching turn-on. Once the detection circuits sense the current flow, the oscillator is automatically disabled, and the nominal power transfer starts.

Original languageEnglish
Title of host publication2020 IEEE 29th International Symposium on Industrial Electronics, ISIE 2020 - Proceedings
Subtitle of host publicationProceedings
Place of PublicationPiscataway
Number of pages6
ISBN (Electronic)978-1-7281-5635-4
ISBN (Print)978-1-7281-5636-1
Publication statusPublished - 2020
Event29th IEEE International Symposium on Industrial Electronics - Delft, Netherlands
Duration: 17 Jun 202019 Jun 2020

Publication series

NameIEEE International Symposium on Industrial Electronics


Conference29th IEEE International Symposium on Industrial Electronics
Abbreviated titleISIE 2020
OtherVirtual/online event due to COVID-19
Internet address

Bibliographical note

Virtual/online event due to COVID-19


  • Control
  • inductive power transfer
  • inverter
  • soft-switching
  • wireless charging
  • zero voltage switching


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