The project HOPE addressed power electronics. It was based on previous EU research projects such as FW5 HIMRATE (high-temperature power modules), FW5 PROCURE (high-temperature passive components), and MEDEA+ HOTCAR (high-temperature control electronics) and other EU and national research projects.
The general objectives of HOPE were:
- cost reduction;
- meet reliability requirements;
- reduction of volume and weight.
This was a necessity to bring the FC- and ICE-hybrid vehicles to success.
- Definition of specifications common to OEM for FC- and ICE-hybrid vehicle drive systems; Identification of common key parameters (power, voltage, size) that allows consequent standardisation; developing a scalability matrix for power electronic building blocks PEBBs. The power ranges were much higher than those of e.g. HIMRATE and went beyond 100 kW electric power.
- Preparation of works out one reference mission profile to be taken as the basis for the very extensive reliability tests planned.
- Investigation of key technologies for PEBBs in every respect: materials, components (active Si- and SiC switches, passive devices, sensors), new solders and alternative joinings, cooling, and EMI shielding.
- Development of three PEBBs: HDPM (high density power module) based on double side liquid cooling of the power semiconductor devices; IML (power mechatronics module) based on a lead-frame technology; and SiC-PEBB inverter (silicon carbide semiconductor JFET devices instead of Si devices).
- Development of a control unit for high-temperature control electronics for the SiC-PEBBs. Finally WP6 works on integrating the new technologies invented in HOPE into powertrain systems and carries out a benchmark tests.
The results of HOPE are relevant from a business perspective because they improve the competitiveness of European products. On the other hand they help in meeting the environmental targets and therefore HOPE is relevant for the whole European society.
The project has the following deliverables :
- common specifications from OEMs including key parameter ranges for FC-hybrid and ICE-hybrid vehicles drive system;
- scalability matrix;
- reference mission profile for FC- and ICE-hybrid electric vehicles;
- applicable test procedures for power electronic systems;
- results of APCT, AMPCT and subsystem tests;
- sensor evaluation;
- HT-joining technologies;
- cooling concepts and verifications;
- results of environmental and reliability tests;
- design of the first mechatronic test vehicles;
- SiC - control board;
- HT - SiC control board;
- impacts of implemented technologies on inverter integration;
- benchmark study.
In summary it can be said that HOPE has achieved good progress:
Performance: There are many examples where the performance has been increased, like:
- Thinner die attach to lower the thermal resistance
- Measures to reduce the CTE mismatch
- Specific packaging to reduce on-state and switching losses in SiC inverters
- Low Rth heatpipe coupling to the SiC inverter
- High temperature driver circuit
- Local heating by thermosyphon
- Integrated SiC commutation cell with very high power density
Lower cost: Three examples demonstrate that lower costs can be achieved:
- IML technology has the potential of 30% cost reduction by replacing the ceramic DCB by a plastic insulator
- The high temperature control board has a potential of 50% costs saving in contrast
to the ceramic substrate
- Integration itself has a potential of 20 to 30% because chip area and other
materials can be saved.
Reliability: Improvements were made in the following areas:
- Partially implementation of the new “Robustness Validation “ process
- Methodology like the mission profile test
- Translation of drive cycle to stress profile at the weakest parts of a system
- Robust high temperature test equipment