The paper presents practical considerations and guidelines for designing an improved-efficiency contactless inductive power transfer link, delivering DC power in step-down mode to an electromagnetic levitation melting system residing in a sealed compartment. The proposed arrangement employs none-series compensated inductive power transfer link operating at the so-called “load-independent-voltage-output” frequency, allowing feedback-less and sensor-less design. However, the output voltage of a system operating at such frequency remains influenced by the load to some extent, residing within a certain range with boundary values (minimum and maximum) corresponding to maximum (rated) and minimum load, respectively. Consequently, the proposed contactless power delivery system is first analyzed using both first harmonic approximation (frequency-domain) based approach and differential equations (time-domain) based method to obtain corresponding output voltage bounds. Then, coil-to-coil efficiency and optimal load matching factor are determined. Comparison with both typically utilized symmetrical series-series and recently proposed series-none compensation topologies reveals the superiority of none-series compensation topology in terms of coil-to-coil efficiency for the whole range of coupling coefficients. Simulations and experiments of 400 V, 1 kW none-to-series compensated inductive wireless power transfer link, delivering contactless energy to a 250 V electromagnetic levitation melting system, demonstrate excellent matching and accurately validate the presented analysis.
- Inductive wireless power transfer
- Load independent voltage output
- None-series compensation
- Output voltage range