Carel Minnaar (GRADUATED)

M.Eng Computer and electronic Engineering


Comparative study of power converters for coupling a renewable source to an electrolyser


Renewable energy sources are receiving much attention due to their clean and sustainable properties. The problem with these renewable energy sources is that they do not provide stable and constant power. Instead, they are only able to provide intermittent power when certain conditions are met. Therefore, to maximise the energy utilization from these renewable energy sources, the energy must be stored in such a way that no harmful by-products or gasses are formed. Hydrogen gas, produced from water using electrolysis, can be used to store solar and wind energy. Photovoltaic panels are conventionally used to power an electrolyser using a power converter. This configuration is both simple to implement and very environmentally friendly. Transitioning to hydrogen as an energy source will also ensure a more secure source of energy as there is less risk of depletion and price volatility that can result in economic pressures. An LLC resonant converter is a kind of DC/DC power converter that is able to achieve zero voltage switching across a wide load range by utilizing the transformer leakage and magnetizing inductances in series with a capacitor, hence the term LLC. Therefore, these power converters are associated with very high efficiencies up to 97%. Presented here is the design, simulation, test and evaluation of an LLC resonant converter for coupling a photovoltaic array to a polymer electrolyte membrane water electrolyser (PEMWE). The resonant converter will be compared to a hard switched converter. A microprocessor is used to control the power converter to ensure that the solar panels are operating at their maximum power point which will result in optimal hydrogen production and maximum overall system efficiency.
Supervisors: Dr Andre Grobler, Dr Dmitri Bessarabov and Dr Gerhard Human