IoT high-frequency electronic transformer with dimmable output voltage using PWM signals

This work presents the design, simulation, and implementation of a low-power electronic transformer, which output effective voltage can be controlled wirelessly through WIFI, via a user interface on a mobile phone. The methodology used in this project consists of 4 stages, a rectifier, an inverter, the inverter’s control system, and a ferrite reducer. The inverter has a full-bridge design and was implemented using MOSFET. The control system can vary the frequency and duty cycle of the output signals, by phase shifting the control signals, thus achieving the functionality of reducing the effective output voltage. Circuit design simulations were performed using PsPice Orcad. The implementation and the mathematical model of the built electronic transformer are carried out. The designed transformer operates with a maximum input voltage of 120 Vrms at 60 Hz at frequencies between 20 kHz and 30 kHz, which are controlled through the user interface; can reduce a 120 Vrms 60 Hz input signal to an effective voltage between 10 Vrms and 20 Vrms at a maximum power of 50 W. This project presents the feasibility of developing electronic transformers with variable output voltage, remotely controlled using IoT technology.This work presents the design, simulation, and implementation of a low-power electronic transformer, which output effective voltage can be controlled wirelessly through WIFI, via a user interface on a mobile phone. The methodology used in this project consists of 4 stages, a rectifier, an inverter, the inverter’s control system, and a ferrite reducer. The inverter has a full-bridge design and was implemented using MOSFET. The control system can vary the frequency and duty cycle of the output signals, by phase shifting the control signals, thus achieving the functionality of reducing the effective output voltage. Circuit design simulations were performed using PsPice Orcad. The implementation and the mathematical model of the built electronic transformer are carried out. The designed transformer operates with a maximum input voltage of 120 Vrms at 60 Hz at frequencies between 20 kHz and 30 kHz, which are controlled through the user interface; can reduce a 120 Vrms 60 Hz input signal to an effective voltage between 10 Vrms and 20 Vrms at a maximum power of 50 W. This project presents the feasibility of developing electronic transformers with variable output voltage, remotely controlled using IoT technology

MODELING AND TESTING OF ETHERNET TRANSFORMERS

Twisted-pair Ethernet is now the standard home and office last-mile network technology. For decades, the IEEE standard that defines Ethernet has required electrical isolation between the twisted pair cable and the Ethernet device. So, for decades, every Ethernet interface has used magnetic core Ethernet transformers to isolate Ethernet devices and keep users safe in the event of a potentially dangerous fault on the network media. The current state-of-the-art Ethernet transformers are miniature (<5mm diameter) ferrite-core toroids wrapped with approximately 10 to 30 turns of wire. As small as current Ethernet transformers are, they still limit further Ethernet device miniaturization and require a separate bulky package or jack housing. New coupler designs must be explored which are capable of exceptional miniaturization or on-chip fabrication. This dissertation thoroughly explores the performance of the current commercial Ethernet transformers to both increase understanding of the device's behavior and outline performance parameters for replacement devices. Lumped element and distributed circuit models are derived; testing schemes are developed and used to extract model parameters from commercial Ethernet devices. Transfer relation measurements of the commercial Ethernet transformers are compared against the model's behavior and it is found that the tuned, distributed models produce the best transfer relation match to the measured data. Process descriptions and testing results on fabricated thin-film dielectric-core toroid transformers are presented. The best results were found for a 32-turn transformer loaded with 100&#937;, the impedance of twisted pair cable. This transformer gave a flat response from about 10MHz to 40MHz with a height of approximately 0.45. For the fabricated transformer structures, theoretical methods to determine resistance, capacitance and inductance are presented. A special analytical and numerical analysis of the fabricated transformer inductance is presented. Planar cuts of magnetic slope fields around the dielectric-core toroid are shown that describe the effect of core height and winding density on flux uniformity without a magnetic core