Wireless Power Transfer (is this correct)

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Discussion Overview

The discussion revolves around the workings of a wireless power transfer circuit, specifically focusing on the role of a transistor in generating oscillations and the behavior of currents within the circuit. Participants explore theoretical aspects, circuit design, and practical implementations.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant describes a cycle involving a transistor being initially OFF, then turning ON, allowing current to flow through the transformer, and questions the source of base current when emitter current is zero.
  • Another participant challenges the correctness of the figures referenced in the provided link, suggesting that they are missing elements necessary for oscillation.
  • A participant claims to have successfully simulated the circuit in MATLAB Simulink, achieving oscillations with a specific source voltage.
  • One participant provides an alternative explanation of the circuit operation, detailing how the transistor generates high-frequency AC current and creates a magnetic field, but this explanation is met with skepticism.
  • Another participant critiques the explanation of "discharging an inductor" and discusses the dynamics of feedback and amplification in producing oscillations.

Areas of Agreement / Disagreement

Participants express differing views on the accuracy of circuit explanations and the role of various components. There is no consensus on the correctness of the circuit operation or the explanations provided.

Contextual Notes

Participants reference specific figures and circuit designs, but there are uncertainties regarding the details and implications of these references. The discussion includes various interpretations of circuit behavior and the underlying principles.

jaus tail
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TL;DR
Circuit Operation:
Ref: https://www.semanticscholar.org/paper/Design-and-Simulation-of-Different-Wireless-Power-Baroi-Isla m/dc19ecfde904964704777ab5adef96d5d6846f1f
1572628388867.png


I couldn't find the working of this circuit so I guess it would be like:
Initially transistor is OFF, so the current flows through Base, and then when transistor is ON, the current flows through transistor Collector to Emitter, so now it flows down the transformer. Base current is reducing and then transistor turns off, so then flux falls. And then again current flows through Base, so cycle continues?

Is this correct? But if current flows through base initially, and if Emitter current is zero, so where does the base current come out from? Emitter current is Beta times collector current. Collector current is zero, so emitter current would also be zero, right?

 
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Which figure is that from at the link? It looks wrong, and is missing some way to make the left hand side oscillate, IMO. Is it from Figure 5?

1572633818698.png
 
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Oh, maybe you posted Figure 6. Still looks wrong to me, though...
 
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But I drew the original circuit that I have posted in MATLAB simulink and was able to get oscillations. I had kept source voltage around 0.4V
 
How
berkeman said:
Which figure is that from at the link? It looks wrong, and is missing some way to make the left hand side oscillate, IMO. Is it from Figure 5?

View attachment 252164
Could you explain the working of this circuit?
I found a slightly difference circuit:
1572842917182.png

It says:
In transmitter section, the Transistor is generating high-frequency AC current across the coil and the coil is generating a magnetic field around it. As the coil is center tapped, the two sides of the coil start to charge up. One side of the coil is connected to the resistor and another side is connected to the collector terminal of NPN transistor. During the charging condition, the base resistor starts to conduct which eventually turns on the transistor. The transistor then discharges the inductor as the emitter is connected with the ground. This charging and discharging of the inductor produces a very high frequency oscillation signal which is further transmitted as a magnetic field.

Ref: https://circuitdigest.com/electronic-circuits/simple-wireless-power-transmission-circuit-diagram
 
In transmitter section, the Transistor is generating high-frequency AC current across the coil and the coil is generating a magnetic field around it. As the coil is center tapped, the two sides of the coil start to charge up. One side of the coil is connected to the resistor and another side is connected to the collector terminal of NPN transistor. During the charging condition, the base resistor starts to conduct which eventually turns on the transistor. The transistor then discharges the inductor as the emitter is connected with the ground. This charging and discharging of the inductor produces a very high frequency oscillation signal which is further transmitted as a magnetic field.

That explanation really makes no sense. "discharging an inductor" ?
What happens both of the 17-turns inductors are wound into a transformer. Once the transistor starts to conduct, the much large collector current will turn off the base current. Negative feedback + time delay + enough amplification will produce oscillation.
 
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