HiEFFICIENT is driven by use cases (UCs), which investigate WBG technologies with different integration levels and include validation of the concepts up to the lab or relevant environments.
When developing electrified vehicles, there is a need for cost efficient but high-fidelity testing that replicates later customer usage as closely as possible. Additionally, as the market evolves, testing requirements are getting broader and more complex. Hence, there is a strong need for flexible testing equipment, which can fulfil the needs of both component and vehicle manufactures.
Hence, UC1 partners will work closely together to develop the next generation of power electronics for these testing devices, being more compact, flexible and having new power levels. Further, reliability is key operating these systems. Consequently, Prognostic Health Management for power electronics in electrification testbeds will be investigated and according methodologies will be developed.
Hybrid and electric vehicles have been developed rapidly in the last years. The increment of the number of electric vehicles in the market results in tight technical requirements for key powertrain components such as the traction inverter(s). The main requirements that must be fulfilled involve power density, efficiency, heat dissipation, and ease-of-integration. The development objectives are generally focused on the improvement of the efficiency, the reduction of the dimensions, and the optimization of the thermal behavior to reach the largest power density as possible. A second big challenge is related to powertrain reliability.
Use case is devided to two parts:
The scope of this use case is the development of a highly compact DC/AC inverter satisfying automotive traction applications requirements with a 48 V battery voltage. The commutation cell will be designed to support modular reuse in DC/DC applications, like an industrial battery cell tester. The converter will use GaN power switches and embed these into the PCB. This will enable a high package density and improved reliability. To drive the GaN power stage in an automotive safety relevant application, like a traction inverter, the development of a driver stage is necessary. The gate driver will also be designed to enable high switching frequencies, above 100 kHz, and tuning the switching waveform for higher lifetime.
Based on the overall objectives of HiEFFICIENT, an efficient, reliable, reconfigurable, and highly integrated power electronic converter system based on the application of SiC power devices will be realized and demonstrated in this use case. By dynamic reconfiguring of multiple grid-isolated units, the overall charging system can produce multiple output voltages and multiple output powers to cater for the growing demand of e-mobility equipment, especially fast DC charging. The proposed converter system aims to accommodate different charging needs for different e-mobility devices, unlike the existing charging infrastructure where it has been designed for a specific type and can only charge one piece of equipment. Also, the flexibility of the charging infrastructure will be extended by developing and testing new charging functionalities, which are enabled by the higher switching frequency of WGB devices. Where feasible, according to the power and voltage levels, a hybrid solution of SiC and GaN technologies will be applied and integrated. The integration at system level of grid-isolated WBG technology-based converter modules will be the basis for demonstrating a reliable and flexible charging station. The isolated DC output units can be arranged in series or parallel by a charging router circuitry, providing by this way the required power needs of different EVs connected at the same time. WBG, SiC MOSFETs power devices, suited for higher switching frequencies, will be used in the power processing converters to generate high frequency voltage signals that allow isolation transformer volume reduction. Furthermore, switching nodes in the semiconductor stacks will have actively controlled dv/dt through auxiliary circuits, aiming at reduction in overall power loss, inductor volume (especially the required EMI filters), and weight. For the UC4 demonstrator, a limited fleet of electric vehicles for professional transport, such as E-buses or E-trucks, will be addressed. The flexibility of the vehicle charging equipment will be explored by studying new charger functionalities enabled by WBG power devices. To do so, research is going to be carried out describing possible strategies which are enabled by the chosen switching frequency of the WBG power modules. The research is going to describe, among others, charger requirements, such as frequencies, power levels, harmonics, communication requirements, vehicle requirements, and expected impacts. Then, algorithms are going to be implemented on the charger side for controlling the WBG power modules and on the vehicle side for evaluating the benefit of the added functionality. The algorithms implementation will be focused on ensuring compatibility with rapid prototyping tools, real-time execution and compatibility with the WBG power modules developed by the partners. Algorithms functionality is going to be demonstrated with a WBG power module converter, in a proof-of-concept lab setting.
This Use Case is divided into three sub use cases.
UC5a: Smart GaN on board charger 400 V
This use case focuses on designing, optimizing and prototyping of a bidirectional OBC, by using 650V SoC GaN devices. The OBC will support extra features / functions such as, intelligent energy & thermal management and predictive health monitoring of electronic components. This will help in reducing the running costs and increasing the lifetime of the whole system. Additionally, the PHM improves serviceability and provides easy maintenance of the OBC.
UC5b: Bidirectional LV off board DC charging at 48 and 120V
In UC5b, the partners develop an innovative, modular, bidirectional low voltage off board DC charger solution (48 V and 120 V; maximum power 7 kW) and an on-board DC/DC 12-48/120 V converter for a low voltage car, equipped with solar panels.
UC5c: Bidirectional OBC (+DC/DC) 400-800 V
UC5c is dedicated to the developing of an integrated EV On-Board Charger (OBC). Two different versions will be developed:
UC6 is dedicated to the application of a GaN-based DC/DC solar converter for solar electric vehicles. Solar power in vehicles has long been a dream, but advances in solar technology (affordable mono-crystalline solar cells of > 25% efficiency) and a shift towards electric vehicles make for an interesting case. To maximize the number of kilometers a solar EV can drive per year, three factors are important: the available area on the car, the energy consumption of the car per km and the efficiency of the solar panel and its electronics. This use case aims to develop the next generation of power converters for automotive solar panels which maximize the total yield in kilometers per year of the solar panel. To achieve that, standby power needs to be minimized, the size should be decreased (since the converters are packaged in the roof of the car, aerodynamics can improve with smaller devices), and the conversion efficiency should increase. The first goal would be realized by having a better and more efficient integration of SoC devices by integrating switch, driver & sensors, the second and third goal would be realized by using GaN based switches at much higher switching frequencies to decrease the size of the filter components and increase conversion efficiency.