Development of a Digitally Controlled Inductive Power Transfer System with Post-Regulation for Variable Load Demand

Kateryna Stoyka,Mario Pucciarelli,Paolo Visconti,Massimo Costarella,Alfonso Avella,Antonio Vitale

doi:10.3390/electronics11010058

Kateryna Stoyka, Mario Pucciarelli + Show 4 more

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https://doi.org/10.3390/electronics11010058

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Abstract

Inductive Power Transfer (IPT) is an emerging technology enabling a contactless charging process in manifold applications such as electric vehicles, wearable and portable devices, or biomedical applications. Such technology can be profitably used to develop enhanced electronic solutions in the framework of smart cities, homes and smart workplaces. This paper presents the development and realization of a series–series compensated IPT System (IPTS) followed by a post-regulator implemented by means of a DC–DC converter. Such a system is modeled through a first harmonic approximation method, and a sensitivity analysis of the IPTS performance is carried out with respect to the variations of the primary inverter switching frequency and phase-shift angle. As an element of novelty of this work, the bias points are determined which allow the efficiency maximization while ensuring system controllability. An enhanced dynamic modeling of the system is then performed by means of a coupled mode theory, including the inverter phase-shift modulation and extending its validity to whatever operating frequency. A digital control of the post-regulator is implemented by means of a commercial low-cost microcontroller enabling the output voltage regulation under both fixed and variable load conditions through a voltage mode control technique. An IPTS prototype is eventually realized, which is able to correctly perform the output voltage regulation at the desired nominal value of 12 V for static resistive loads in the range [5, 24] Ω, yielding the output power in the range [6, 28.8] W and the experimental efficiencies going from 72.1% (for 24 Ω) to 91.7% (for 5 Ω). The developed system can also be effectively used to deliver up to 35 W output power to variable loads, as demonstrated during the battery charging test. Finally, an excellent output voltage regulation is ascertained for load transients between 5 Ω and 24 Ω, with limited over- and undershoot amplitudes (less than 3% of the nominal output voltage), thus enabling the use of the proposed system for both fixed and variable loads in the framework of smart homes and workplaces applications.

Highlights

As a second element of novelty, we have investigated the controllability issues of the buck post-regulator cascaded to the IPT System (IPTS) using the developed First Harmonic Approximation (FHA) static model
The developed Post-Regulated Inductive Power Transfer System (PR-IPTS) prototype has been tested under different load conditions to assess its power and efficiency performances and output voltage regulating capabilities for variable load demands
A Post-Regulated Inductive Power Transfer System (PR-IPTS) has been developed, which is based on a series–series capacitive compensation scheme and a DC/DC

Summary

Introduction

The wireless charging of electric and electronic devices and systems has become increasingly popular in everyday life since it allows for a contactless power transfer between a stationary primary source and one or more stationary or movable secondary loads. In this framework, Inductive Power Transfer (IPT) allows for a safe, reliable and cost-effective charging process over relatively large air-gaps via magnetic coupling between the primary transmitting and the secondary receiving coil, by exploiting the same operation principle as that of transformers and coupled inductors but with weaker coupling. Such technology can be profitably used to develop enhanced electronic solutions in the framework of smart cities [6], homes [7] and smart workplaces [8]

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Conclusion