This Master thesis aims at studying the technology of In-Motion Charging (IMC) trolleybuses. These trolleybuses are equipped with an on-board battery large enough to provide energy for certain parts of the route. Thanks to that, the parts of the line do not have to be covered with overhead lines. As the vehicles charge their batteries en route, the IMC trolleybuses do not have to stop for depot charging which gives them advantage over regular e-buses.

Main task of this thesis is to develop and study a new charging scheme for IMC trolleybuses called the Valley-Charging. While conventional methods can only use two predefined charging powers, Valley-Charging allows changing the charging power over time based on the conditions on the trolley-grid. To evaluate the suitability to charge, methods of evaluating the state of the trolley-grid, such as traffic or power capacity of substations were developed into an estimator suggesting the appropriate charging power. The estimator is a set of conditions and constraints which use data that are available on-board of the trolleybus en route without any way of communication with other vehicles or infrastructure, such as bus voltage, bus current or bus position.

Multiple version of the estimator were developed and analysed for problematic circumstances. New conditions were added after that to make the estimator more complex. The Valley-Charging method supported by the estimator was implemented to 9 new IMC trolleybuses added to the Arnhem trolleygrid. Simulations with the latest version of the estimator showed that the new vehicles manage to service the line as it can collect enough energy under the overhead lines to successfully make the round trips. The results of the Valley-Charging scheme were compared with conventional charging schemes currently used. The Valley-Charging was found superior to the conventional methods in terms of energy collected or severity of technical limit violations.

Trolleybus systems can be a sustainable replacement for regular diesel powered busses. The sustainability of these systems can be further improved by storage systems that recuperate the braking energy of the buses and feed it at a later point. By strategically placing the storage system, the transmission losses in the grid can also be reduced. Based on measurements from the Arnhem grid, a case-study on the implementation of such systems is simulated. Results show that for this grid, implementing storage only for the reduction of transmission losses is not beneficial. However, when the recuperation of braking energy is considered, a significant energy reduction can be achieved (up to 17% for some specific sections in the grid). A recommendation on location, sizing and charge scheme is given based on the simulation results. Furthermore, a study has been performed on using stationery storage for reducing feeding substation peak demands, creating headroom for other ancillary services (e.g. EV charging).

Trolley bus systems provide modern low-emission public transport for urban areas. The trolley bus demands a peak power at acceleration that is at least 4 times the regular operational power demand of the bus. To provide the acceleration power for a fleet of buses, the substations are inherently oversized. With the excess capacity in the trolley grid, EV charging can be integrated into the DC trolley grid, making the trolley grid more multi-functional. This EV charger should be able to charge from a DC grid with fluctuating line
voltage, has high power, low volume, high efficiency, and conform to different charging protocols. In this thesis, a 25kW DC/DC converter for EV charging from the trolley grid is modeled, designed, and compared. The isolated full-bridge PWM ZVS topology is chosen and simulated on MATLAB Simulink. The working principle of the full-bridge converter is analyzed and modeled, obtaining the operating modes and circuit behavior. Then the influence of the circuit parameters can be investigated on the model, and the optimal design choices are made. The converter uses SiC MOSFET switches, and its modular two secondary phase design provides 2 connection modes, ensuring a wide output voltage and current range. The zero-voltage switching can be achieved over a wide load range, and the efficiency at rated load 25kW is 96.4%. Finally, another widely used high power DC/DC converter topology dual active bridge (DAB) is investigated and modeled in Simulink, and the waveforms and efficiency of DAB are presented in both power transfer directions. The performance of DAB is compared with that of the full-bridge converter.