# Design of a Ressonant Inductive Charger for static EV's

#### Pedro_Lopes_951

Joined Mar 24, 2020
9
Hi people, I'm new here just registered.
So I am writing about a problem I am having regarding some simulations(Simulink) a have been doing for my master thesis.
My goal is to design an inductive wireless charger that uses a resonant tank to maximize the efficiency of the process. I am going to add some pictures of the circuit so I can illustrate better the issue I am having.

You can see in the first picture that this is still a simple simulation where I have a Full bridge inverter connected to a DC source to supply power to another circuit that has a series-series topology for maximizing the power transfer. Then on the exit, there is another full-bridge rectifier to convert the signal to DC to charge a supposed batterie.
This simulation is based in many other that I have researched but I have used the data of another simulation published in an article: https://bit.ly/2WFg7bh (Page 37-44)
And so now mentioning the problem I am having, while in the article the waveforms of the primary voltage and current are in phase and also the voltage and current from the secondary wing of the resonant tank my waveforms (voltage and current on both sides) are shifted 90 º something that I don't understand why since all the parameter of the circuit are the same of the article. The capacitors are calculated using the formula 1/(wress^2*L) so that the tank is working in resonant frequency. I will add another picture of the waveforms.

Sorry for the long text but I will end here the explanation of my problem and give more details if someone knows what I should do. Due to the current state of the world, it has been hard to get help from my university professors because of the quarantine everyone is obliged to do in my country .

I hope I was clear enough with my English.
Thanks in advance and stay safe.

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#### ci139

Joined Jul 11, 2016
1,696
? reduce the inductance or frequency (see if the problem presists)
? reduce the inductance and increase the frequency (see the response)

basically you are not out of sync - try sine wave input

#### Pedro_Lopes_951

Joined Mar 24, 2020
9
? reduce the inductance or frequency (see if the problem presists)
? reduce the inductance and increase the frequency (see the response)

basically you are not out of sync - try sine wave input
Hey,
I tried to reduce the frequency to see how it influences the waveforms and it looks like the currents on both sides are starting to become more in phase with the voltage but now they are less sinusoidal the same happens when I increase the frequency and reduce the inductance. Do you have any idea why is this happening?
Thanks for the help.

#### ci139

Joined Jul 11, 2016
1,696
you have the L.s(er) @ the secondary side that takes time to pass the current
if you study the plotted wave-forms - you see the expected behaviour of ↑such↑

the question is - do you need things to be in phase-sync.

right now you have the series resonant circuits @ both sides ← it just means that the path for certain frequency meets the least resistance . . . in ideal case you need to have the load resistance + parasitic resistance = the total XL and total XC . . . pretty much like terminating the transmission line

. . . or then i don't get it quite correct ( a random guess follows . . . )

an interesting thing here is risen voltage on the secondary load ??? a simulation bug ??? ( ↓ with a bit modified circuit ↓ )

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