Condition Monitoring and Wide Bandgap Power Electronics - Leading Innovations for the European Energy Sector

Project Information

MoWiLife

Grant agreement ID: 101172657

DOI

10.3030/101172657

EC signature date 2 August 2024

Start date 1 October 2024

End date 30 September 2027

Funded under

• Climate, Energy and Mobility

Total cost

€ 3 955 691,25

EU contribution

€ 3 955 691,25

Coordinated by

UNIVERSITAT ROSTOCK
Germany

Periodic Reporting for period 1 - MoWiLife (Condition Monitoring and Wide Bandgap Power Electronics - Leading Innovations for the European Energy Sector)

Reporting period: 2024-10-01 to 2026-03-31

Summary of the context and overall objectives of the project

MoWiLife (Condition Monitoring and Wide Bandgap Power Electronics - Leading Innovations for the European Energy Sector) is an EU Horizon project within the CL5 call D3-01-14.

The MoWiLife consortium addresses Condition and Health Monitoring and Wide Bandgap und Ultra Wide Bandgap power electronics for the energy sector with four pilots and one technology carrier.

Basis for the four MoWiLife pilots is a 2.3 kV SiC MOSFET in an XHP2 module housing, which will be developed by project partner Infineon. It includes a source-gate PiN diode, whose on-state voltage has a strong temperature dependence.
The University Rostock is developing a gate drive unit, which can read out the on-state voltage of this diode during the off-state of the SiC-module and the on-state voltage of the SiC-chips during the on-state of the SiC-module. These information will be transmitted to the converter control unit. Here, the measured temperature is compared with the calculated temperature and the measured on-state voltage is compared with the expected temperature- and current-dependent on-state voltage. With these information, the state-of-health of the module can be detected.

In addition, self-protection features will be integrated into the SiC module for improved robustness and direct water cooling will be realized for higher output power.

Two wind energy converter pilots are being realized in MoWiLife by two industrial partners. As one of the technology leaders in wind energy, Vestas – supported by University of Aalborg – will realize a TRL 6 SiC converter with +20% power density and digital-twin Condition and Health Monitoring. The start-up RKL together with Rostock University will develop a TRL 5 wind energy power stack with Condition and Health Monitoring based on online chip temperature and on-state voltage measurement.

Solar medium voltage DC collection grids and meshed high voltage transmission grids will play an important role in the future. As third and fourth pilots, a TRL 5 DC-DC converter and a TRL 5 DC circuit breaker including condition monitoring are being developed by the MoWiLife university partners KTH Stockholm and University of Aberdeen.
The low-to-medium voltage DC-DC converter is based on dual active bridges. They are put in parallel on the low voltage side and in series on the medium voltage side. The topology allows zero voltage switching, which leads to a significant reduction of switching losses, thus allowing much higher switching frequency and thereby smaller transformers.
For the high voltage dc circuit breaker, a cascaded hybrid approach is used. It contains SiC MOSFET as commutation switches in series with the mechanical main switch. Due to the low on-state voltage of the SiC-MOSFET, efficiency especially at partial load is increased.

While SiC is today’s Wide Bandgap material for high power applications, ultra-high voltage Ultra-Wide Bandgap semiconductors may allow further efficiency improvements for future HVDC converters. The MoWiLife industrial partner DiamFab together with two IUNET universities will work on diamond as the ultimate semiconductor material. The TRL is still low but the potential for energy saving is high.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The MoWiLife project has six main objectives. The main achievements are described in relation to these objectives.

Objective O1: 2.3 kV SiC MOSFET module with access to TSEP, self-protection features and high power density

The MoWiLife-SiC-MOSFET module will have advanced self-protection features. This includes protection against high short-circuit currents by a sense-FET, protection against drain-source overvoltage by an module-integrated active clamping circuit and protection against high negative gate-source voltage by an chip-integrated source-gate diode. These features require new SiC-MOSFET chips, which have been developed and fabricated in the first phase of this project. Improved power density is going to be achieved by an improved thermal performance of the module base plate und by use of direct water cooling. Different materials for the base plate have been evaluated. To improve the thermal conductivity between the base plate and the coolant water, ribbon bonds on the base plate backside are going to be used.

Objective O2: Pilot 1 - SiC wind power converter

MoWiLife will demonstrate a 20% power density improvement of a wind power converter by using 2.5 kV SiC-MOSFET modules. A feasibility study has shown that three parallel MOSFET modules are necessary to reach the output power of 2.5 MW. Different possibilities for the stack-layout have been investigated and a preferred solution has been found.
Double pulse tests to evaluate the switching behavior of the SiC-MOSFET, to determine the gate resistances for smooth switching with low switching losses and to measure the switching losses have been performed.

Objective O3: Pilot 2 – SiC converter with condition monitoring

The main idea for condition monitoring in this project is to use the temperature dependence of the MOSFET source-gate diode as temperature sensitive parameter. To read out the temperature, the gate driver feeds a continuous current in the mA range into this diode while the MOSFET is in the off-state. By measuring the on-state voltage of the diode, it’s temperature can be determined. The gate driver with this feature has been designed and fabricated. Besides measuring the diode voltage, this gate driver can also measure the MOSFET on-state voltage during conduction. The information about the on-state voltage is sent back to the converter control. Together with the information about the current, the temperature can be determined. There are two requirements regarding condition monitoring. On the one hand, wear-out has to be detected before the device fails. This is going to be tested in a power cycling test bench. On the other hand, the condition monitoring circuit must be immune against false triggering in an inverter environment with high EMI levels. This is going to be tested in a converter in continuous operation. The power stack of such a converter including condition monitoring has been developed, switching performance of the SiC-MOSFET in this inverter has been tested.

Objective O4: Pilot 3 – SiC-MOSFET medium voltage DC-DC converter

The DC-DC converter should be able to connect a 1.5 kV PV system to a medium voltage collection grid with e.g. 10 kV DC. In the first project phase, a concept study has been performed. A dual active bridge (DAB) converter with parallel connection on the low voltage and series connection on the medium voltage level turned out to be the most favorable solution.
The DAB converter should operate at zero voltage switching. To evaluate the zero voltage switching behavior, a special test setup was realized. A ZVS gate driver has been developed in two versions, as well as a low inductive snubber capacitor board. Switching measurements have been performed, showing the potential of zero voltage switching with unipolar power semiconductors.

Objective O5: Pilot 4 – High Voltage DC Circuit Breaker

The basic 4.8 kV, 5-10 kA hybrid DC CB based on 4 series connected SiC MOSFETs has been designed and simulation model developed on PSCAD. Additionally, 2 other topologies are designed: 9 kV, 5-10 kV to test scaling to higher voltages, and 4.8 kV, 10-15 kV topology to test scaling to higher currents. In the first phase of the project, also more detailed SPICE model has been developed for SiC MOSFET to enable studies of detailed transients and series connection. In addition, the test bench for high voltage, high current tests has been upgraded.

Objective O6: Pilot 4 – Feasibility of Ultra-Wide Bandgap 20 kV FET

The high critical electric field of diamond opens the potential of unipolar devices with a much higher blocking voltage than SiC ones. In comparison to SiC devices, the drift layer thickness will be much lower. But compared to today’s diamond semiconductor samples with a blocking voltage around 1 kV, the drift layer has to be more than factor 10 higher. Therefore, growing of thick diamond layers and diamond deep etching are crucial technologies for ultra-high voltage devices. Remarkable progress was made in both areas during the first phase of the project. For example, growing of 10 µm-thick diamond layers with a very uniform thickness and low surface roughness was achieved. Diamond deep etching was increased from 5 µm to 20 µm.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

In this first project phase, the main results beyond the state of the art are related to the power semiconductors and new materials.

Integration of source-gate protection diodes for SiC-MOSFET has never been reported before and is a significant scientific progress. First samples have been fabricated and successfully tested within this project.

Significant progress far beyond the state of the art has been made regarding growth of thick doped diamond layer, which are the basis of ultra-high voltage power semiconductors.