Design of a Solid State Transformer

Project Title

Design of a Solid State Transformer

Project Area of Specialization Electrical/Electronic EngineeringProject Summary

Our project is to design and develop a solid-state transformer to replace the conventional transformer used in electrical systems.

The conventional transformer has many electrical power losses such as eddy current and copper losses. Conventional transformers are costly and covers a very large area due to their size requirement. Furthermore, conventional transformers are also not environment friendly due to heat and magnetic radiations in surroundings. We also require special oil or coolant system to control the temperature of conventional transformer.

On the other hand, solid state transformer will not have those issues of heat, large area requirement, power losses due to magnetic field losses and any coolant oil etc.

 A solid-state transformer will be based on three steps. First step will be AC-DC conversion, where high voltage Alternating Current will be converted to a DC, that will be feed to the next step. Depending upon requirements, here voltage can be increased or decreased. In our case, we will be stepping down the voltage from 240V to 12V. This 12-V DC can be directly used in many DC applications like Electric Weichel charging. After that, 12-volt DC will be converted back to AC using a cyclone converter and a very small size ferret core transformer.

This project will not only help in overcoming the issues in electrical system due to conventional transformers, such as power losses, large area requirement and cost, but will also be beneficial in modern applications like EV charging and smart grid station having high frequency requirements.

Project Objectives

The main objective of the project is design and development of a solid-state transformer, which can replace the conventional transformer in an electric system. The designed solid-state transformer will have:

1. Small size and area compared to equivalent conventional transformer
2. Much low power loss compared to equivalent conventional transformer
3. Environment friendly compared to conventional transformer in terms of heat and magnetic flux
4. No coolant system or oil requirement as needed in conventional transformer
5. Fault isolation in case of any fault in system unlike conventional transformer

Project Implementation Method

We divided the project implementation process into 4 parts. These parts are research, Model selection and simulation, development and testing. In the research phase, familiarization will be gained with issues with conventional transformer and their possible solution using solid state transformer. Different topologies will be analyzed and we will be also targeting the use of solid-state transformer in the smart grids and renewable energy sources.

In model selection and simulation phase, based on research model will be proposed. Circuit will be designed in proteus and detailed simulations will be carried out before hardware implementation.

In development phase, proper hardware of solid-state transformer will be developed by using selected components such as IGBTs, transistors, diodes and ferret core transformer etc.

Lastly, developed solid state transformer will be tested and its performance will be compared with equivalent solid-state transformer.

Benefits of the Project

Solid state transformer has many benefits in power system compared to conventional transformer. Some of these benefits are:

1. Much smaller volume and weight compared to conventional transformer
2. Unlike conventional transformers, solid state transformer can provide output with different frequencies and phases, which are useful in smart grids and renewable energy sources.
3. Complete isolation between input and output stage to protect the load from any damage in case of fault at any stage
4. Voltage regulation on demand
5. Improved voltage sag and swell
6. A direct DC voltage option for Electric Weichel charging
7. Environment friendly and clean power solution with no heat and magnetic leakage in environment and no coolant and oil requirements

Technical Details of Final Deliverable

Designed solid-state transformer in this project will be basically a prototype that will show how a larger scale transformer will work. Designed hardware will have 4 major parts.

1. AC to DC Converter: Which is based on a rectification stage followed by filtration for smooth DC level
2. DC to DC Converter: To step down DC voltage from 220 V to 12 Volts. This stage is based on a cyclo-converter to create a very high frequency AC signal from DC input, which is then passed through a small size ferret core transformer to get desired voltage level.
3. DC to AC Converter: Lastly, again cyclo-converter can be used to get AC output voltage at any desired frequency level.

Final Deliverable of the Project Hardware SystemCore Industry Energy Other Industries Others Core Technology Clean TechOther Technologies OthersSustainable Development Goals Affordable and Clean Energy, Responsible Consumption and Production, Climate ActionRequired Resources

Item Name	Type	No. of Units	Per Unit Cost (in Rs)	Total (in Rs)
			Total in (Rs)	71200
ferrite core transformer	Equipment	4	1500	6000
TL494 PWM IC	Equipment	20	80	1600
MOSFETs	Equipment	20	450	9000
FYP thesis printing and stationary	Miscellaneous	1	10000	10000
High frequency diodes	Equipment	20	150	3000
Transistors, Resistors, capacitors, diodes	Equipment	20	2000	40000
Conventional 220V transformer	Equipment	2	800	1600