Wireless Resonant Inductive Power Transfer for an Ebike Charging Battery

In this page presents the prototype and experimental tests of an E-bike 300W battery charger for a cyclo-station based on wireless power technology made for research.

For this project, several scientific papers were written with a mathematical model developed and conducted with performance analysis to determine the voltage transfer function, maximum power transfer capacity, efficiency for different air gaps (1 -3 cm) and misalignments (0.5-1.5 cm).

The resonance frequency of this circuit for wireless charging batteries is 40kHz.
To achieve maximum efficiency and maximum power transfer, work at the resonance frequency.
To evaluate the correctness of the circuit a LabView panel was realized where it was possible to characterize the circuit by varying the frequency between 30-50 kHz on the prototype.

This is a second prototype of the Ebike Charging battery. It is a primary part of the charger. it works at a higher frequency and for the magnetic part has been used a coil of Wurth Elektronik.

The circuit during the tests connected to the electronic instrumentation.

Scientific papers:

1- Resonant inductive power transfer for an E-bike charging station (Journal ELSEVIER)

2- Controller design and experimental validation of a power charging station for e-bike clever mobility (Conference IEEE)

3- Detailed continuous and discrete–time models and experimental validation to design a power charging station for e-bike clever mobility (Journal ELSEVIER)

LLC resonant converter

On this page presents several photos of a prototype and experimental tests of a 3kVA bidirectional resonant DC-DC converter, made for research activities.


The work was commissioned by AIRBUS, a major European company operating in the aerospace and defense sector, and was part of the doctoral thesis of Luigi Rubino, a member of RubinoLAB. The converter is an evolution compared to the classic hard-switching converters in which we participated in 2008-2009 for a European project called “Moet” More Open Electrical Technologies.

The LLC converter, required many hours of work to develop all the mathematical models before the realization taking into account also the parasitic effects of the components. Furthermore, all the parts that are difficult to find, such as transformers, resonant capacities, high thickness copper PCBs, MOS drivers for frequencies up to 300kHz, measurement and control boards have been realized in our laboratories and compared with mathematical models. The result, the measurements are identical to the simulations.

Particular design accuracy was given to the resonant transformer and to the resonant capacities not found by the component distributors.

Only the magnetic parts were purchased for the transformer, while the coils are suitably machined copper plates isolated from each other.


The resonant capacities at the primary and secondary are the most critical components in the system, since they must keep the value stable even when the working temperature changes. A minimal variation in the capacity value varies the resonance frequency of the circuit and therefore we will no longer have the maximum power transfer. The number of SMD capacity to be parallelized was chosen keeping in mind the capacity value and the working current.


To evaluate the correctness of the parameters of the entire circuit, a LabView interface was created where it was possible to characterize the resonant circuit by varying the circuit frequency.

Figure shows the prototype during the test phases.

In the video we can see the typical measurements with varying working frequency.

Scientific articles:

  1. Complementarity Model for Steady-State Analysis of Resonant LLC Power Converters
  2. LLC resonant converters in PV applications comparison of topologies considering the transformer design