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HYPERMAC Report Summary

Project ID: 632565
Funded under: FP7-JTI
Country: Italy

Final Report Summary - HYPERMAC (Hyper Performance Motor, Air-Cooled)

Executive Summary:
The goal of the project was the development, manufacturing and test of a E-motor and related power converter for aircraft electric propulsion mainly characterized by high reliability, safety and high power-to-weight/power-to-volume ratio. A direct-drive full motor-drive air cooled with enhanced reliability and adequate power density has been designed, prototyped and qualified up to TRL4. The system is compatible to be adopted for the tail rotor propulsion of Rotary Wing aircrafts. The purpose of the project has been almost achieved.

Project Context and Objectives:
The development of a more electrical aircraft is a technological transition applied or envisioned for almost all the systems in the aircrafts and helicopters. Together with the electrification of aircraft actuation systems, also the implementation of an electric propulsion can lead to many advantages in terms of reduced specific consumption, noise reduction, weight and volume saving. Anyway this transition is mainly limited by the reliability, lifespan and some safety aspects of electric system.
In this extent the purpose of the project covers the design, development and validation of a motor-drive for aircraft electric powertrain mainly characterized by high reliability, safety and high power-to-weight/power-to-volume ratio. In particular, the design refers to the development of an Electrical Tail Rotor Drive and includes realistic requirements of a produced Rotary Wing aircrafts. The envisioned solution aims to design a direct-drive motor-drive air-cooled with enhanced reliability and adequate power density.

Project Results:
The project has been split in the work packages described below.
WP2 was dedicated to the analysis of the state of the art and to the elaboration of the technology concept. Starting from requirements released by the Topic Manager, a broad and in-depth survey of the literature studies and other project activities on electrical machines for the electric powertrain was performed in the first phase of the project. About electrical machines, different architectures were investigated, evaluated and compared on the basis of structure, related power electronics and control methods. In particular, the state of the art analysis was focalized on:
- BLDC motor
- PMSM motor
- Induction machine (IM)
- Switch Reluctance Motor (SRM)
About power electronic converter, among analyzed H-bridge converters, the ZVSHBI, the SPMLI and the MSHBI configurations stand out because they only need one supply source as opposed to SP7LI and SP7LI. Hence, they are best suited to the application. Moreover, the SPMLI and the MSHBI configurations present a very small THD and a simpler control strategy than the ZVSHBI configuration. Indeed, in case of conventional H-bridge type multi-level inverter, 8 controllable switches are used to obtain a 5 level output voltage, but the SPMLI configuration requires only 6 controllable switches while the basic H-bridge only uses 4 switches to obtain a 3 level output voltage. The circuit configuration of the latest is indeed simple, reliable and cost-effective implementation is possible. The efficiency can also be improved, granting the reduction of the switching loss. The basic H-bridge with 4 switches possesses numerous advantages as:
- Each motor phase will be independent with another, which makes the control easy and flexible;
- Power loss is smaller in fault tolerant mode because the fault phase will not affect the other phases’ operation;
The final inverter selection was due also on other considerations as ease of integration to the e-motor.
At the end of the WP2, three design concepts were proposed for the E-motor and tradeoff studies leads to the final choice of the motor architecture.
Different solutions for the power converter were discussed, focusing on the modular structures which are capable to assure the requested fault tolerance. Three architectures were proposed, based on the H-bridge structure, and evaluated by the fault three analyses which demonstrates that only one configuration is capable to satisfy the system safety requirements.
Therefore, the global architecture of the motor-drive was fixed during the preliminary design review.

WP3 was dedicated to the final design of prototypes. Starting from the results of the previous analysis the motor drive design will be carried out by an accurate and efficient design methodology that combines Finite Element (FE) programs, detailed models and automatic optimization procedures. At the end of the WP3 the design of the motor, power electronics and related control strategy was defined and fixed during the Critical Design Review. Beyond the detailed drawings of the motor and related inverter, further modeling activities were performed in order to verify the requirements compliance. The thermal analysis of the air-cooled motor was carried out in order to verify the steady-state temperature of the active materials (winding, PMs), in the healthy mode operations, by imposing the severe duty cycle defined in requirements. The thermal analysis was performed using two different approaches (and related software): using a lumped parameter thermal network and FE model. Results of both analysis confirm that the temperature of the stator winding and PMs are satisfactory and do not reach critical values. About the control strategies, the most promising architecture was deepened. By the adoption of this phase architecture, the system can guarantee the required modularity for fault tolerance while classical high dynamic Field-Oriented control strategies can be adopted. About the software, the low level functions based on the link between MATLAB and code composer studio development tools are initialized. The initialization process of SPI, CAN, ADC, DI, DO, EQEP, PWM modules helped the control board to interact with the control circuits and power devices. In addition, it simplifies software debugging and performance optimization with the advanced analysis and visualization capabilities of MATLAB. Furthermore, it helped to test and verify algorithms running on the C2000 family of DSP, exchange real-time data with development hardware and simulators.
Interface control document, 3D drawings and behavioural/electrical model were collected in D3.1. EM and thermal FEM are collected in D3.2. During the CDR, all documentation was approved and collected in D3.3 “CDR” in which updates of D2.1, D2.2, D3.1, D3.2 were included.
All foreseen deliverables were submitted to the commission.

In the scope of WP4, Umbra proceeds, according to final designs, to 3 motors and related power converter manufacturing: 1 for the delivery, 1 for the characterization and functional tests and 1 for spare.
An article inspection was performed as reported in D4.1. All design characteristic of manufactured/purchased mechanical components were in tolerance as specified by drawings or requirements or, when the dimension was out of range of tolerance, it was evaluated as acceptable.
After first functional test, the validation of TRL3 was performed (D4.2). The development process of the HyPerMAC project followed the usual aeronautics procedure. Therefore, the achievement of the CDR objective can be considered as TRL3 validation. In fact, the documentation to be provided for CDR acceptance responds to most of verifications needed for this TRL validation.
Main verification for TRL3 validation are reported in the following together with report in which the verification is addressed:
• Definition of function allocation and Interfaces available (D3.1 includes interface control document, 3D drawings and behavioural/electrical model);
• Technical modelling done (D3.1 includes interface control document, 3D drawings and behavioural/electrical model);
• Sizing done including assessment of critical performance (D3.2 includes EM and thermal FEM)
• Main features of new software function simulated and tested (D3.3 includes software development);
• Software technical impacts analyzed and assessed in architecture model (D3.3 includes software development);
• Critical performances assessed by engineering tests (D5.2 includes control board functionality test)
• Assessment of new technology and demonstration of critical performances and characteristics (D4.2 TRL3 validation);
• Technology characterized w.r.t intended usage (D4.2 TRL3 validation);
• Technical impact analysis done on functions and architecture (D4.2 TRL3 validation);
• Assessment of cross technology issues (D4.2 TRL3 validation);
• Initial assessment of compatibility/interoperability (D3.1 includes interface control document)
• Exhaustive assessment of benefits and drawbacks/ value (wrt dimensions), adequacy to needs (D3.3 CDR document)
• Risks / hard points identified (D3.3 CDR document)
• Preliminary assessment of safety / security / confidentiality/certification (D6.3 RAMS Analysis)
Moreover, as requested by the TM, the SWOT analysis was performed by Umbra. This analysis shows Strengths, Weaknesses, Opportunities and threats of the developed technologies.

WP5 was focused on characterization and functional tests on the prototypes. In the first phase of this WP, a Validation Test Plan, which includes an Acceptance Test Procedure, has been prepared and performed using existing capabilities. After the prototype manufacturing, HW SW integration and debug steps have been performed along with first characterisation/functional tests in order to validate the design and the performance of the prototype.
Several tests were performed on individual component in controlled environment. Suitable instrumentation were used to simulate the operating condition. Tests on the control board demonstrates that it works correctly, in particular:
• Power test
• JTAG test
• PWM test
• DAC test
• CANBUS A and B test
Also the power stage was tested in controlled environment in order to evaluate the innovative technology adopted (SiC) obtaining expected enhanced performance. The control board was tested together with the power stage with and without the snubber. PWM commands of the control board are correctly received by the driver without noise in the case of snubber presence or not.
In the scope of WP5, the TRL4 validation was performed (D5.4). Main verification for TRL3 validation are reported in the following together with report in which the verification is addressed.
About Architecture:
• Lab test of new architecture prototype: skeleton (integration of key components) with test S/W content
• Verification of critical properties (e.g latency, installation constraints...).
• Update of technical model
Evidence of these activities are reported in D3.1, D3.2, D3.3 and annex of D5.4
About Software:
• New function more comprehensive specification done & implemented in simulation / rapid prototyping.
• Technical impacts on architecture model updated.
• OS/MdW : detailed specification done.
Evidence of these activities are reported in D3.3, D5.2 and annex of D5.4
About Technology:
• Techno component prototype realization and lab testing against critical performances, environment and usage domain specification.
• Technical impacts on architecture and function models updated
Evidence of these activities are reported in the annex of D5.4
About Benefits/Value:
• Updated assessment of benefits / value / risk based on test results (& delta between test environment & real world), explicit answering of hard points (Annex of D5.4)
• Component level failure modes identified and Preliminary RAM assessment / identify certification issues (D6.3 RAMS Analysis)

WP6 addressed several activities for the evaluation of the development process.
Design documents (D2.1, D2.2, D3.1, D3.2) has no relevant updates from the CDR versions. Therefore, the deliverable D6.1, which is foreseen as a collection of D2.1, D2.2, D3.1, D3.2 updates, was submitted.
A final TRL assessment (D6.3) was performed confirming the TRL4 of the developed technology. Some important activities for TRL5 validation are on-going and this target will be probably achieved after the final closure. In the scope of this WP, the RAMS (Reliability, Availability, Maintainability and Safety) analysis was approached. The aim of this further important activity was the demonstration that the system is compliant with reliability requirements of the TM.

Potential Impact:
The primary objective for the aerospace industry is to offer products that not only meet the operating criteria in terms of loads and range but also significantly reduce the direct operating costs of the airlines. The switch over to more electric aircrafts offers a fundamental change in the technology compared to state-of-the-art systems and will significantly increase the performance in terms of improved system efficiency, reduced weight on airframe level. Main challenge of this transition is to achieve compliance with the stringent requirements in terms of operational reliability and safety.
During and after the HYPERMAC project, main achieved results have been disseminated to a broader scientific audience. Essential knowledge on electric motor, acquired during the project should strongly contribute to the European industries capability of supplying competitive products with high reliability. Although the European aerospace systems companies’ market share is globally significant, US systems companies have a dominant position in almost all product groups, with the US industry being strongly supported by its government. The project RTD works will support the system’s industry strive for highly competitive products and thus prepare the ground for a balanced market access. The promising results of the project can be confirmed by further tests.

List of Websites:
The public website is not foreseen.

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