Transformer-less isolation in DC power converters

2019 ELE Engineering Design Project (BV06)

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Faculty Lab Coordinator

Balasubramanian Venkatesh

Topic Category

Power

Preamble

DC power supplies (including DC/DC converters) come in two main categories; isolated and non-isolated. Isolation is normally achieved with the inclusion of a transformer. Isolation can be important for many power supplies (for safety, etc…), but the inclusion of a transformer in the design can add weight, cost, and can increase electromagnetic interference (EMI). On top of these challenges, transformers also need to be specified and customized for most commercial applications.

Objective

The objective of this project is to conceptualize, simulate, prototype, and test a transformer-less DC power isolation solution. This DC “transformer-less isolator” is meant to be used at the input of a non-isolated DC/DC converter (i.e. a buck converter), to add isolation, without the use of a transformer or any other additional magnetics.

Partial Specifications

The outcome of this project is to prove that a non-isolated DC/DC converter topology (i.e. buck converter) can achieve electrical isolation, between its input and its output, through the addition of a transformer-less isolation device.
The converter should be able to handle inputs of 0-50V and accurately control its output from 0-50V.

Suggested Approach

It is suggested to use a standard buck-converter topology, using an implementation of a standard buck controller IC (i.e. TPS 54560). It is also suggested to implement the transformer-less isolation using the “switched capacitor power buffer” created by Argentum Electronics (to be provided by Argentum).
An Arduino (or similar microcontroller) can be used to control the system logic.
A standard DC power supply can be used as an input to the system, and any resistive load can be used at the output.

Group Responsibilities

To create an operational prototype of an isolated buck-converter using the standard non-isolated buck topology, by adding a transformer-less isolator at its input.

Student A Responsibilities

Design, simulate, prototype, and test, a DC-DC buck converter (i.e. based on the TPS54560 buck controller). Calculate the values of the required capacitor and inductor, as well as operating frequency, loop compensation, and feedback resistor settings.

Student B Responsibilities

Design, simulate, prototype, and test a transformer-less DC power isolator (i.e. based on Argentum Electronics’ “switched capacitor power buffer”). If using the “switched capacitor power buffer”, calculate the required capacitor values, switching frequency, transistor specs, energy transfer, and efficiency. This student will also implement a simple frequency controller for the isolator (i.e. using on an Arduino microcontroller).

Student C Responsibilities

Provide support to students A and B in their design. Understand the implementation of the buck converter, and the transformer-less isolation in detail. Combine the two components, run several tests to confirm working condition of the system. Design tests to confirm electrical isolation, calculate efficiency, and no-load and load conditions.

Student D Responsibilities

Coordination and management

Course Co-requisites