Powertrain modularity

This document provides a comprehensive report on the activities related to the experimental validation of lab-scale power converter prototypes. It includes an analysis of the current standards for power converter testing, drawing on publicly available sources and the expertise of RHODaS partners.

The document also proposes a detailed test plan for High Power Converters (HPC), which are based on Low Power Converter modules. This plan encompasses electrical tests for both Low Voltage (LV) and High Voltage (HV) parts, as well as environmental, mechanical, and safety tests. Additionally, the document reports on laboratory tests to verify basic parameters of Low Power Converters (LPC), such as efficiency, distortion, and Common Mode Voltage (CMV).

The analysis highlights the absence of comprehensive standards for inverter testing, necessitating the search for relevant documents from various testing fields. Due to the high voltage levels considered in the DC/AC converter, of at least 1000 VDC Bus, it is necessary the adaptation of research methodologies in cases where direct references are lacking. This process requires substantial knowledge and experience in test systems and application of standards.

The conclusions drawn from these activities are expected to support future design, optimization and recommendations, focusing on further improvements in power converters and the use of standards specifically adapted for them in automotive applications.

The Dual Active Bridge Converter topology is widely recognized for its high power density in high-power applications, enabling soft switching and achieving high efficiencies in both buck and boost operation modes. However, under conventional phase-shift modulation, operation at light or no load results in hard-switching and high effective currents, leading to increased overall losses, one of its main drawbacks. These issues have been primarily addressed by implementing complex modulation strategies, leveraging from the multiple degrees of freedom in the control of the converter power, particularly the inner and outer shift angles of its bridges. Contrary to the traditional approach, this work proposes the modulation of the series inductance of the DAB converter by implementing a switched inductor, aiming for a simplified modulation strategy. The proposed method effectively achieves zero current under no-load conditions and significantly reduces effective currents at light loads compared to the traditional phase-shift modulation approach. Although an in-depth comparison with other modulation schemes is required, this work represents a stepping stone in the analysis of the topology and the comprehension of its trade-offs.

This deliverable reports the selection of the optimum power devices for implementing the SCAPE high-voltage switching cells, after a literature review and commercial availability check. In addition to suitable electrical characteristics, the selection of candidates considered the suitability and availability of bare-die components for their subsequent chip embedding process. Two SiC MOSFET references have been selected and samples have been obtained for an initial test campaign (GeneSiC G4R12MT07. 750V – 12 mΩ and Wolfspeed CPM3-0650-0015A. 650V – 15 mΩ). For the development of the low-voltage switching cells of the auxiliary SCAPE converters, GaN HEMTs from EPC will be selected. The deliverable also includes a prospective and literature review about power device emerging technologies.