QehnA internal seminars in the spring of 2021 on the theme "Control of Power Converters: From Theory to Practice" revolve around the concepts and methodology of rapid prototyping. After the seminar of 9 March 2021 on the PIL approach, this seminar of 6 April presents the implementation of the RCP approach with the OPAL-RT environment and its application to the case of the 4 quadrant chopper., with a brief reminder of the different approaches to begin with