This bachelor thesis is written as part of the curriculum for the bachelor Electrical Engineering at the Delft University of Technology. The thesis is part of the course EE3L11 - Bachelor Afstudeer Project and took place from April 2017 until July 2017. This document describes the development of a system that is able to drive electric drum brakes, the brake control unit (BCU). The BCU is a subsystem of a larger project; a braking system that minimizes the force between a trailer and a car when braking. The ultimate goal is to let the trailer completely brake for itself. To achieve this, two other subgroups have designed a control algorithm and a force sensor readout circuit that measures the force. The BCU receives a desired braking force from the control algorithm that should be exerted in order to eliminate the force between car and trailer. This input force covers a certain range, so the BCU should be designed such that the braking force of the brakes can be regulated. For this purpose a power supply, current controller and lookup table are designed. The developed power supply is able to provide a constant voltage to the solenoids inside the electric brakes. The power supply consists of a DC/DC converter, which is powered from a car battery. As a consequence, the input voltage of the DC/DC converter is dependent on the state of charge of the battery. Nevertheless, the output of the designed converter is able to provide a constant DC voltage with a maximum current of 8 A. The designed current controller makes use of a PWM driven current source, which controls the output current of the DC/DC converter. Besides this source, an algorithm that estimates the duty cycle of the PWM signal is derived, based on the desired current through the solenoid. Last, a lookup table is implemented that determines which current is needed for specific input forces. The table makes use of inter- and extrapolation between measured test results to calculate the right current for every input force.

In the past years electric cars have been rapidly taking market share in the automotive industry. Stimulated by their sustainable image and due to large investments in the charging infrastructure, the electric automobile has gained popularity in the field of research. Many papers are written on a variety of power converters inside the cars to interface between batteries, chargers and motors. Usually, these converters are made as universal as possible, in order to suit the needs of many different vehicles. As a result, they are capable of operating at wide voltage and power ranges, often at the cost of weight or efficiency. The Dutch electric car startup Lightyear aims at a completely different strategy. Their car with integrated solar panels is designed with one goal: increasing efficiency. For that reason, all components have been reconsidered and, if sufficient gains in efficiency can be achieved, completely redesigned. One of these components is an isolated bidirectional DC-DC converter that ensures power transfer from the solar panels to the main battery. In this thesis that DC-DC converter is developed. Special focus is put on maximizing the efficiency to ensure as much energy from the solar panels can be used to power the car. First, all possible topologies that meet the requirements are investigated and the best option is selected. Then, a script is developed that configures the power stage of the converter using a provided list of components. The implementation with the highest average efficiency over the operating range is automatically selected. After that, alternative modulation strategies are investigated, aimed at reducing the conduction losses of the converter. Finally, a controller is created and validated for the designed converter. The result of the presented work is an isolated bidirectional DC-DC converter, achieving an average power stage efficiency of 98.1 % over a wide range of input voltages and output voltages at a constant power output.