Photo of Tomas Uno Jonsson

Tomas Uno Jonsson

Adjunct Assistant Lecturer

My work is around power electronics dealing with the integration of semiconductors, power system, batteries or pv-cells. The focus is on components and converter control. Power conversion for integration of renewable power is especially interesting.

Power Electronics

Power electronics is the field of electronic circuits related to power conversion. This could be conversion from direct current and voltage (DC) to alternating current and voltage (AC) or vice versa. Alternatively, conversion between different DC or AC levels, which often is referred to as power electronic transformation.

The working horse in a power converter is the power semiconductors, which typically would be transistors, diodes, thyristor or variant thereof.

Integration of power semiconductors is a multi-disciplinary exercise. Due to high speed switching of the power semiconductors the design of the control circuitry (gate electronics) is a crucial area. Detailed properties of the semiconductors, interfacing components and parasitics of the circuit must be understood.

Thermal management is another important area for semiconductor integration related to the cooling of devices. Furthermore, failure modes and protection strategies must be considered to arrive at a reliable and safe converter system.

The next large activity is the control system design, serving the functionalities demanded by the application. The control system includes interface to operators, measurement equipment and sensors, cooperated control systems in order to define the output signals for control of power semiconductors and other control devices (e.g. mechanical switches and breakers).

The control system can be ranging from complex industrial computer platforms down to embedded micro controllers. Of paramount importance for a converter application is the knowledge of connected energy sources (e.g. solar panels, wind turbines, batteries) and the receiving power consumer or power grid. The converter design and performance shall fulfil international standards and grid codes for power quality, electrical safety and environmental impact.

The engineering process includes detailed modelling of the properties of converter equipment and interconnected systems to be able to perform computer simulation for prediction of circuit design and system performance prior to the implementation.