Wireless charging using a separate third winding for reactive power supply

Predmet istraživanja ovog diplomskog rada, kako teorijski tako i eksperimentalno, bila su tri različita modela bežičnog napajanja. Prvi model koji je bio ispitivan je bio osnovni model bežičnog napajanja s dva namota u kojem su kondenzatori povezani u seriju sa zavojnicama. Treći namot, čija je uloga osiguravanje reaktivne snage, je postavljen na primarni namot te su ispitivane dvije različite topologije modela bežičnog napajanja s tri namota i uspoređene su s osnovnim modelom. Prvi model bežičnog napajanja s tri namota imao je kondenzator spojen u seriju sa sekundarnom i tercijarnom zavojnicom, dok je drugi model imao kondenzator spojen u seriju sa svakom od tri zavojnice. Kako bi se predvidjelo ponašanje svakog od triju modela bežičnog napajanja, napravljeni su simulacijski modeli u programskom paketu Matlab/Simulink, kao Bodeovi dijagrami prijenosnih funkcija svakog sustava. Nakon laboratorijskih ispitivanja, utvrđeno je da najvišu korisnost ima osnovni model bežičnog napajanja s dva namota koja je iznosila 64%. Model bežičnog napajanja s tri zavojnice i dva kondenzatora imao je korisnost od 57%, dok je model s tri kondenzatora imao korisnost od 61%. Navedene vrijednosti korisnosti su niže u odnosu na uobičajene vrijednosti modela bežičnog napajanja za male snage, a glavni razlog tome je što su prisutni visoki gubici u bakru.In this thesis, three different models of wireless charging systems were investigated theoretically and experimentally. The first model that was evaluated was a basic model of a two winding wireless charging system with a capacitor connected in series with each of the coils. An auxiliary winding was added on top of the transmitter coil in order to provide the reactive power and two different topologies of three winding wireless transfer systems were compared to a basic model. The first three winding model had a capacitor connected in series in the receiver loop and in the auxiliary loop, while the last model of a wireless charging system had a capacitor in every loop. In order to predict the behaviour of each wireless charging system, a simulation in Matlab/Simulink was made, as well as the Bode plot for the transfer function of each system. After some practical measurements, it was found that the best overall efficiency was for a basic two winding model, which was 64%. The three winding model with two capacitors had 57% efficiency, while the model with three capacitors had 61% efficiency. These values are rather low compared to the usual values of the efficiency for a wireless charging system for low power, and the main reason is that there were high copper losses, because Litz wires were not used in the experiment