Saturday, March 2, 2024

Speed record for an Australian electric motor

The professor Rukmi Dutta and her team of the University of New South Wales, in Australia, have developed a new electric motor that works at high speed and uses less energy, which definitively means less pollution.

Rukmi has innovated and improved the existing IPMSM, which have different characteristics that make them highly performing electric motors, decreasing their environmental impact.

The integration of magnets inside the rotor generates more torque: the cylinder turns not only owing to the interaction between magnet and alternate current, but also because of the additional rotation caused by the rotor material’s resistance to the magnetic field, a property called “magnetic reluctance”. These machines can also operate at high speed without needing much power, which means that the smallest IPMSM can perform the same quantity of work as other bigger motor types. Besides, compactness is a key factor for the use in cars and aircrafts, where space and weight capacity are limited. The developed motor, not longer than a pen and with the diameter not bigger than a coffee cup, can reach 100,000 rpm and the nominal power is 5 kilowatts.

Saietta: axial flux electric motor to electrify the world mobility

It is headquartered in the United Kingdom and it develops in pioneering way solutions for the automotive electrification and it is particularly in turmoil precisely for the great boom that the segment of electric vehicles is living, also due to the legislator’s contribution. We are speaking of Saietta, in search of new 250 collaborators and that has recently released its latest project: axial flux electric motor design, which combines both distributed windings with a yokeless stator.
Besides, the moment is particularly favourable: it has won a research contract through the Advanced Propulsion Center (APC) of the United Kingdom, but the witness by the chief executive officer of Saietta Group, Wicher Kist, a bit slows down enthusiasms: «We are ready for the future of transportation by stepping in with modern, lightweight electric motors as traditional internal combustion engines fuelled by petrol and diesel reach the end of the road. If the 2030 target is to be met, key decisions on future investment will need to be made quickly so companies like ours realize our full potential. That means more funding from UK government and quickly».
The company aims at a modular approach to its motors that are at the service of a broad range of vehicles, from scooters to trucks. Its first offer of commercial motors, for instance, AFT140, is optimized for the use of medium-size bikes and vehicles for last-mile deliveries, currently much more important solutions in terms of volumes in Asian markets rather than in Western ones. Precisely in this scenario, Saietta has recently announced a remarkable partnership agreement with Padmini VNA, one of the main automotive players in India.
The commercial agreement provides for Padmini collaboration with Saietta to develop new opportunities in the Indian market and renowned Indian two-wheel OEM players stand out among its customers, such as Hero MotorCorp, TVS, Bajaj Auto and Royal Enfield.

Mazda enhances R&D for its rotary engine

Mazda has announced they will speed up their research and development activity on the rotary engine (RE), already used in the MX-30 R-EV and presented as the powertrain of the concept Iconic SP shown to use on future electrified models.

The new “RE Development Group” will take care of going on making its rotary engine evolve, equipping it with ideal sizes to be used as a generator in electrified models, carrying out research and development activities in areas such as conformity with regulations in primary markets and the use of zero-emission fuels.

Speaking of the new team, Ichiro Hirose – Director, Senior Managing Executive Officer, and Chief Technology Officer (CTO) – declared: «In the electrification era and a society featuring zero carbon emissions, together with our challenging spirit, we promise we will continue to offer appealing cars that thrill customers».

Recently, for the first time Mazda restarted the production of cars with rotary engines, eleven years after the exit from the scene in 2012 of the Mazda RX-8, equipping the MX-30 with a motor-generator unit that is the core of its first mass-produced PHEV system. Released in Japan and Europe, the Mazda MX-30 e-Skyactiv R-EV is the twelfth Mazda model with a rotary engine.

Sustainable mobility: the excellence Italian National Pole was born

Last July 16th was presented the project of the National Pole of Sustainable Mobility and Manufacturing, also called SMTC, Sustainable Mobility Technology Center, which will be established in TNE spaces of Corso Settembrini 178 in Turin.
We, too, from Electric Motor Engineering were present, to be able to tell you at best this new Italian pride that exceeds a further border and involves more players of different nature: Turin Polytechnics, University, CIM 4.0, API, Turin Trade Chamber, Industrial Union, Piedmont Region and city of Turin.
The target is accompanying enterprises, especially small and medium-size ones, towards a course of innovation and training, giving them the possibility of using sophisticated tools, at disposal just with investments worth million Euros.
The keyword is technological transfer, a possibility that can be implemented through the creation of a sound network and the contamination between technologies and competences, also due to the establishment of territorial companies, but not only, at the Pole’s.
Within 2023 this new excellence should become concrete, with Turin at the core of the capability of doing system, to full benefit of research, innovation and technological transfer to offer training services and activities.
All this is completed by a project of sustainable reorganization of an area still unused, feather in the cap of the automotive manufacturing, where the smartest companies will be attracted.
During the launch event, it was possible to visit the pilot lines that will be the technological core of the Pole: the Additive Manufacturing Pilot Line, the Laser Powder Bed fusion and Direct Energy Deposition.

The new innovative battery by Stellantis that combines an inverter and a charger

After four years of intense projects and severe simulations, a team of 25 specialists who include engineers and researchers of Cnrs, the French National Centre of Scientific Research, has revealed a battery system known as Ibis (Integrated System of Intelligent Batteries). Ibis is supported by the Future Investment Plan, managed by Ademe (the French agency for the environment and the energy management) and coordinated by Stellantis. The primary participants in the project include Saft (TotalEnergies Group), E2CAD and Sherpa Engineering, together with the research laboratories of Cnrs and Institut Lafayette.
The specificity of this innovation resides in its design: the battery combines an inverter and a charger, notably increasing the efficiency and the longevity of batteries for electric vehicles. Moreover, this new configuration decreases costs and at the same time frees inner space in the vehicle.
Ibis is not only a product, but a real project that started in summer 2022, a system that changes the way according to which conversion boards are positioned as close as possible to the elements of the lithium-ion battery: a strategic position that allows the battery to produce directly alternate current for the electric motor.
Ibis has the potential to reduce the weight and the manufacturing costs of electric vehicles and to widen the range of available functions. From the point of view of the stationary energy, Saft provides for offering turnkey plants that enable a more efficient energy use, decreasing the environmental impact. Ibis battery by Stellantis also offers a simplified maintenance and an enhancement of plants.

Renewal of CSA accreditation for MGM Motori Elettrici

MGM Motori Elettrici laboratory in Serravalle Pistoiese factory has recently obtained the renewal of the accreditation by CSA for both safety-related tests and concerning inverter duty motors and energy efficiency (CSA C390). Although the range of already certified motors, in over 25 years of collaboration with CSA, is very broad, it is often necessary to certify new products according to the customization demanded by customers, or to update certifications after upgrades introduced on existing products.
The approval of MGM Motori Elettrici laboratory allows certifying new motors in shorter times, helping our customers, with a competent technical support, to release on the market reliable products in conformity with the regulations in force.
In addition to the safety aspect, in USA and Canada some regulations regarding motors’ energy efficiency are in force. For the conformity with such regulations, our motors are labelled on the plate with the marking cCSAus “Energy Efficiency” and “Certification Compliance number” released by the US Department of Energy (the CC number released to MGM Motori Elettrici is CC 051A).

University of Perugia: the study on the efficiency of electric cars is starting

One of the hottest issues concerning the electric mobility is the motor efficiency. Concerning this, a study involves the University of Perugia, in the context of a graduation course in industrial engineering. The research programme involves also professors of triennial and master graduation courses in Industrial Engineering in Terni, as well as Genesi Energia company, operating in the sector of the electric mobility engineering and of manufacturing, stocking and use of electric energy from renewable sources.
The study provides for activities of modelling and experimental analysis in electric mobility applications and the creation of predictive models for the assessment of the charge efficiency and of autonomy depending on the mileage. Such predictive models, combined with experimental checks, will be applied on Renault Zoe electric car, made available by Genesi Energia.
«The analysis of efficiency and energy dispersion of the new electric mobility – explained prof. Ermanno Cardelli, director of the Engineering department of University of Perugia – is a still unexplored field that will be fundamental to work at the implementation of the distribution networks of electric energy on roads. Moreover, the research provides for the design and the implementation of a prototype of electric quadricycle with pedal assistance with photovoltaic panels on board: the design of the super light frame, combined with renewable energy sources on board, will allow achieving theoretically unlimited autonomy in day travels».

In Berlin the new engineering centre for Bugatti Rimac

In the German capital, a new design and engineering hub will be established and it will operate under a new German subsidiary called Bugatti Rimac GmbH. Berlin is a young and sparkling city, able to fuel technological start-ups, an epicentre for artists and designers.
However, the automotive company’s headquarters will always remain in Zagreb, with the vast majority of employees and a future expansion in Croatia.
It seems that some job positions are already open: Concept Chief Engineer, Head of High-Voltage Systems and Components, Head of Fine Mechanics and design roles with specific focus on interiors, exteriors and VR.
Adriano Mudri, previously design director of Rimac Automobili, will be appointed design director of a future sister company of Rimac focused on mobility, which will take care of developing state-of-the-art vehicles, which will be successively revealed.
«Bugatti Rimac GmbH – stated its CEO Mate Rimac – represents a new exciting business expansion. This new branch will be deeply involved in many new exciting hypercar designs we are looking forward to sharing with the world. Our team is expanding day by day and Bugatti Rimac GmbH represents an opportunity for the best in the sector to join us, to prove their skills and to be part of a company that is redefining the hypercar».

Loccioni opens the doors to future engineers

One of the key components that in the future will allow the large-scale transition to the electric mobility is the electric axle. Loccioni has embraced this new adventure by developing Axenon, a test bench for e-axle technologies that perform the functional product test at line end, simulating the wheels’ behaviour in different scenarios and collecting data about quality, reliability and performances of each single e-axle. A preliminary assumption to frame a small part of the activity of Loccioni, which has recently hosted the students of the advanced course in Human Centric Engineering SITUM Alumni, who have been guided in a tour through the various work ambits and the current and future opportunities connected with the electrification process.
Important was the contribution by the University of L’ Aquila, which has joined the Polytechnic University of Marche and the University of Perugia in the development of SITUM, because it catches the attention on electrification and its future developments.
The visit in Loccioni laboratories has shown the concreteness of this transition to students. Besides injectors, common rails, pumps and endothermic motors, now inverters, batteries and electric motors must be tested. Even power modules, with SIC semiconductors, core of the electric motor, are the new components of electric vehicles. In addition to e-mobility, in Loccioni there is a lot on show in the front of smart buildings: all 6 laboratories are connected in a micro-grid, 100% electric, whose energy flows coming from renewables are managed by a smart system.

Synchronous Reluctance motor: a rare-earth free solution for electric vehicles

The Research Group at Department of Industrial & Information Engineering & Economics of the University of L’Aquila has been working for many years in the field of designing, prototyping and testing of innovative motors for automotive applications. It is recently involved in a H2020-GV European project focused on contributing to avoid the use of rare-earth magnets through the development of a next generation of electric drivetrains, ensuring the industrial feasibility for mass production while focusing on the low cost of the manufacturing technologies. 

The impact of internal combustion engine on the environment has led to efforts to replace it by alternative propulsion systems, among which the electric motor has become the primary candidate. The electric car market is booming and in the next twenty years a surge electric vehicles (EV) sales is expected which should exceed that of traditional ICE cars, as shown in Fig.1.
The new technologies for energy storage and powertrains play a critical role in the development of the electric vehicle market. At motor level, key components and innovative materials must be integrated in the current motor designs. Recent advances in materials, power electronics, control systems have contribuited to new energy efficient and performant powertrains adopting innovative motor technologies.

Trend of electric car sales (Bloomberg New Energy Finance)
1. Trend of electric car sales (Bloomberg New Energy Finance)

The basic characteristics of an electric motor

The requirements of the electric motors for EVs are different from the conventional ones used in the industrial applications. The most challenging specifications are a reduced size and high efficiency in an extended speed range. For good overloading and wide speed range capability, the machine is usually water cooled with a water jacket around the stator core.
The basic characteristics of an electric motor are the following:
1. high specific power and specific torque;
2. very wide speed range;
3. high efficiency over wide torque and speed ranges;
4. wide constant-power operating capability;
5. high reliability and robustness for vehicular environment;
6. reasonable cost.
Since the EV operates over a wide torque-speed range in various driving conditions, the motor design should be aimed to achieve overall energy saving over a driving-cycle of the vehicle (e.g. WLTP, NEDC, UDDS). There are many demands for developing propulsion systems with high power density, high efficiency and low cost.
The research in this field has been intense in the past few years and different types of electric machines have been studied and proposed. The vast majority of motor solutions rely on Permanent Magnet technology using rare-earth magnets. Table 1 summarizes the existing electric vehicles in the European & US markets, specifying the technological solution for the traction motors.

Traction Motors for Electric Vehicles
Table 1: Traction Motors for Electric Vehicles

From the Permanent Magnet Synchronous Motor

The Permanent Magnet (PM) Synchronous motors are more attractive and the main advantages are their inherently high efficiency, high power density, and high reliability.
The PM motors are relatively easy to control and exhibit excellent performance, in terms of maximum torque per ampere control and optimal extended speed operation. Different types of PM machines are proposed according to the position of PMs in the rotor and can be classified as surface or interior mounted magnets.
The high and volatile cost of raw materials for magnets makes uncertain their long-term availability, especially since the electric vehicle technology is going to be manufactured in mass production. Also, PM motors present several technical drawbacks that limit the performances of the motor, in particular the demagnetization effect if the temperature of the motor exceeds its operating conditions. Therefore, there is a growing attention in alternative solutions that include rare-earth (RE) free machines or reduced RE-PM machines.

The Synchronous Reluctance Motor

The Synchronous Reluctance Motor (SynRM) is becoming of great interest in the recent years and represents a valid alternative for electric and hybrid vehicles due to its simple and rugged construction. The main advantage of the SynRM relies on the absence of the rotor cage losses or PM losses, allowing a continuous torque higher than the torque of an Induction Motor (IM) of the same size. Other important features are:
1. the rotor is potentially less expensive than PM motors and IM ones;
2. the specific torque is acceptable and it is not affected by the rotor temperature;
3. the field-oriented control algorithm is simpler with respect to the one of IM drives.

Cross section of the 200 kW SynRM
2. Cross section of the 200 kW SynRM

The conventional SynRMs are known for their lower specific (peak) power and specific (peak) torque (compared to the PM motors), higher noise and lower power factor.
Despite these drawbacks, it is possible to obtain high torque density and high efficiency motors through an optimized rotor design.
Specific power in SynRM is enhanced by increasing the rotor operating speed and the flux-weakening region. Nevertheless, the optimal geometry for motor performances needs to be refined to guarantee the mechanical integrity of the rotor at high speed.

New solutions for the power traction systems of electrical vehicles

The Research Group at Department of Industrial & Information Engineering & Economics of the University of L’Aquila has been working for many years in the field of designing, prototyping and testing of innovative motors for automotive applications. The Group is recently involved in a H2020-GV European project labelled “RefreeDrive” – Rare Earth Free e-Drives for low cost manufacturing.

Table 2: SynRM requirements for the target application
Table 2: SynRM requirements for the target application

This project is focused on contributing to avoid the use of rare-earth magnets through the development of a next generation of electric drivetrains, ensuring the industrial feasibility for mass production while focusing on the low cost of the manufacturing technologies.
The aim is to study and develop new solutions for the power traction systems of electrical vehicles, based on Brushless AC electrical machines rare-earth magnet free.
Through the development in the electric motor topologies within the project, advanced performance has been achieved in terms of specific power, power density and efficiency, compared to a current electric vehicle taken as a reference (Tesla Model S 60). The ReFreeDrive Consortium is composed of 13 partners in six European countries and the team of University of L’Aquila took in charge the design of high speed Synchronous Reluctance motor (200 kW peak power) for a full-electric premium vehicle. The goal was to design a liquid cooled SynRM than could satisfy the imposed requirements shown in the Table 2.

Performances while respecting the target components cost

The avenues indicated above have required a complex optimization process for matching the desired motor performances while respecting the target components cost. Specific sizing procedures and optimization algorithms have been used for the design refinement and the proposed solution presents an innovative rotor structure with “fluid shaped” barriers and radial ribs.
Fig.2 shows the cross section of the 6-pole SynRM.The rotor with asymmetric shape has multiple “ribs” that connect the segments to each other axially and transversally: these connections maintain enough mechanical integrity in the rotor structure when rotational forces are applied at high speed.

Table 3: Performance of the SynRM
Table 3: Performance of the SynRM

The optimal positioning and the optimal thickness of the rotor ribs have been refined by the “topology optimizer” coupled to a mechanical Finite Element software; this algorithm has allowed to optimize the quantity and the positioning of the mass needed by a mechanical part to sustain the stress.
The main motor performance at peak power and continuous power are listed in Table 3 while Fig.3 presents the efficiency map in motoring mode: the peak efficiency is about 96% and the maximum torque is 383 Nm with a peak power of about 250 kW at 6200 rpm. At maximum speed (18000 rpm), the maximum power is 56 kW: these performances fully satisfy the requirements given in the Table 2.

Efficiency map of the SynRM
3. Efficiency map of the SynRM

 

Rotor of the SynRM (1 pole): mechanical stress @ 18000 rpm
4. Rotor of the SynRM (1 pole): mechanical stress @ 18000 rpm

The mechanical equivalent stress map at max speed (18000 rpm) is reported in Fig.4: the results are satisfactory and confirm that the rotor structure is able to withstand mechanical stress at high speeds and it satisfies the mechanical limits of the chosen electrical steel.
A lower power machine (75 kW peak power) has been scaled from the 200 kW design by only changing the stator winding and stack length in order to contain the manufacturing costs.
Two protoypes have been realized and Fig. 5 shows the stator and rotor cores of the 75 and 200 kW sizes.

Stator and rotor cores of the SynRM prototypes
5. Stator and rotor cores of the SynRM prototypes

The power electronic has been designed by R13 Technology (a University of L’Aquila spin-off) for a direct integration with the SynRM housing sharing the motor cooling system.
The powertrains (75 and 200 kW) will be tested in real driving conditions on a test bench and vehicle demonstrators.

by Marco Villani, University of L’Aquila, Dept. of Industrial and Information Engineering and Economics

ABOUT THE AUTHOR

Marco Villani, University of L’Aquila, Dept. of Industrial and Information Engineering and Economics
Marco Villani, University of L’Aquila, Dept. of Industrial and Information Engineering and Economics

Marco Villani received the M.S. degree in electrical engineering from the University of L’Aquila, Italy, in 1985. He became an Assistant Professor of power converters, electrical machines, and drives in 1993. In 1990, he was Research Fellow at the University of Dresden, German, and in 1995 at the Nagasaki University, Nagasaki, Japan. In 1998 he cooperated in two SAVE projects concerning the “Energy efficiency improvements in threephase Induction Motors” and the “Barriers against energy efficient motor repair”. He has been involved in National Research Projects and took the responsibility of several research contracts between the University of L’Aquila and industrial partners. He is currently associate professor of Electrical Machines Design for the Master-level degree courses of Electrical Engineering at the University of L’Aquila. His research interests are focused on modeling and design of electrical machines, high efficiency induction motors, optimization techniques for the electrical machines design, Finite Element analysis of electric motors, design of PM synchronous motors and Reluctance motors for industrial, automotive and aerospace applications. He is author of more than 160 technical papers in scientific journals and conference proceedings.