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Power Electronics High Voltage Technologies

Periodic Reporting for period 2 - PHiVe (Power Electronics High Voltage Technologies)

Reporting period: 2019-11-01 to 2021-06-30

Problem/Issues being addressed

With the overall objective to reduce CO2 emissions for aviation and the reduction of the overall costs of building, operating, and maintaining aircraft, one of the key enablers towards this objective, is the adoption of higher levels of electrification on aircraft. This higher level of electrification, more commonly known as More Electric Aircraft (MEA), looks at replacing traditional non-electrical systems with lighter and more efficient electrical alternatives.

As a consequence of this progression towards MEA, there is an increasing requirement for power conversion methods in the power distribution network, which provide high density, and higher levels of efficiency. In addition, the push towards standardization of components, avoiding bespoke designs for each new application, means that any solutions which are module based will be preferred. Traditionally, the only viable solution for power conversion requirements was to use passive solutions with transformers and controlled rectifiers, such as TRU and ATRU units, which results in a heavy and inefficient power conversion system. By replacing the passive system with active power conversion, the weight and power density of each power conversion stage can be significantly reduced, thus leading to the overall goal to reduce system weight and costs.

Benefits

The introduction of high voltage bidirectional power converter system in generation and actuation applications, will yield a number of benefits for airframe manufacturers, around lower-cost solutions, improved reliability and lower weight. The reduction in weight will have a direct impact on fuel consumption providing direct financial benefits to the airliner as well as additional resulting environmental benefits. The cost reductions from reduced maintenance and overall system costs will assist in reducing the overall costs of air travel with the subsequent societal benefits.

Objectives

The objectives of the PHiVe project is to demonstrate operation of a scalable converter that addresses the most critical aspects in a high voltage aviation converter design, which are the converter topology, the components, the interconnections and the packaging. The demonstrator will provide further validation to the use of high voltage SiC devices in aerospace applications with their associated efficiency and reliability benefits.
Over the course of reporting period project, the following work has been completed by each of the consortium members.
UNOTT: Various converter topologies were modelled and a preferred topology was identified. Numerous evaluation tests were performed by the University of Nottingham. These were outlined in deliverable 2.1. Technical support was given to all consortium members on the development of the other sub-components. The assembled modules were tested and a screening test was developed to detect defective power modules. For final testing in a half-bridge configuration achieved operation up to 2.3kV and 80Arms at 40kHz and 50kHz was achieved. Drive circuitry, an inrush and fast discharge board and PWM generation were developed. Device cooling was implemented and a mock-up demonstrator was developed. 2 technical papers were presented at PEMD.

DEEP: A power module design was developed by DEEP concept. The design utilized a double-sided, water-cooled module package with stacked power substrates. The use of power bump technology was proposed for the chip interconnects. The modules were built and tested. The details of the design were outlined in deliverable 4.1 which was submitted in October 2019. Thermal modelling of the power module and an associated report was completed.

KNOW: Knowles has developed the MLCC capacitor that will be used inside the power modules. They have completed characterization testing of the device and have delivered all the required units for evaluation and final build. They have also designed, built and tested DC link capacitor modules and integrated them on custom bus bars. The capacitor test results were reported as part of deliverable 2.1.

TECN: They have designed, built and tested a controller board, a sensor board, a current sensor board, a fibre optic board and 2 power supply boards. They have advanced the development of the control algorithm but this was not implemented.

The University of Manchester has completed a report on interconnect technologies and have also developed an Excel based clearance and insulation thickness calculator which they have used to determine safe clearances and insulation thickness for the PHiVe converter. They have designed, built and tested a feedthrough connector and they have specified all the interconnects. 2 papers were presented at the Electrical Insulation Conference 2021.

Microchip has submitted four project management deliverables to the Clean Sky system (D1.1 D1.2 D1.3 and D1.4) and completed all associate work relating to these. A project plan was created to track the progress on all tasks, deliverables and milestones. A fortnightly consortium Webex meeting and all major review meetings have been organised by Microchip. Microchip facilitated correspondence between Clean Sky, the topic manager and the consortium. Microchip provided all SiC and FPGA piece parts for the converter build.
The 3.3kV Silicon Carbide die that has been delivered is beyond state of the art for this type of technology. The power bumps that will be used as interconnects in the power module package can be considered beyond state of the art as they provide many benefits over the traditional wire bond interconnect method. The impact of both these technologies will reduce weight and cost, and increase efficiency for aircraft electrical systems. This will result in associated environmental benefits of reduced emissions and lower maintenance cost and effort.
Controller, power supply 1 and fibre boards
Sensor and fibre boards
Partial demonstrator
DC Link design
Interconnects test setup
Trace of half-bridge operation
Power supply 2 board
Power Module 3D models