In Europe, the 640/2009 Regulation on electric asynchronous motors, which has been transposed in more phases, has been in force for some years now. Currently, the regulation concerns 50 Hz or 50Hz/60Hz three-phase asynchronous motors, for constant operation, with nominal powers between 0.75 kW and 375 kW, with 2, 4 and 6 poles; the energy efficiency class for use in net must be minimum IE3 for them.
The new DRN motors constitute integral part of our modular system of motors. A new interface with mechanical reducer, able to assure higher flexibility and system combination. With optimized weight, sizes and efficiency, these asynchronous motors can be easily integrated into machines and plants for high energy-efficiency operation. The new IE3 motors are naturally compliant with all main global specifications and design regulations like IEC 60034, NEMA MG1, UL 1004-1, CSA C22.2-100, ABNT 17094-1 and GB 12350 (CCC). Moreover, they already conform to the next regulations in the energy efficiency field for Europe, India, Brazil, USA, Canada, China and other Countries.
All this makes Sew-Eurodrive an outstanding manufacturer of low energy consumption gearmotors of the IE3 efficiency class, with nominal powers included between 90 and 200 watts, with all customary quality and a complete line of services connected with the product that operators know and appreciate.
What are the structural choices that make a motor innovative and super-performing? What are the most suitable materials for obtaining the best of each component in the design layout? We have asked it to a great expert: Luca Ianni, Engineer and Electric Motor Specialist of AVL, among the leader forefront companies, which at its sites, including the Italian hub at Cavriago (RE), is intercepting and outlining the present and the future of the electric motor of excellence.
Before going into the impressive theme that highlights the innovation of electric motors, with the target of exceeding the limit of the performances reached today from the point of view of technology and electromagnetic operation, especially in automotive ambit, it is necessary to do a macro-subdivision of electric motors; first between those with axial flux and radial flux. «In the automotive sector, we still find both motor typologies, even if there is growing interest in axial flux motors due to the achievable torque and power density performances. Today the axial flux motor can reach levels that were unconceivable last years, especially in terms of cost, because this motor typology features higher manufacturing difficulties that made the manufacturing cost rise and then induced to discard it a priori, owing to budgets, compared with radial flux motors».
Other macro-divisions among motors see on one hand permanent magnets synchronous motors, then brushless motors that in their turn can be split into surface mounted permanent magnet motors and internal permanent magnet motors, the latter called also IPM, widely used in the automotive industry because they allow exploiting the reluctance torque component, increasing efficiency and extending the speed range versus other structural typologies. On the other hand, there are wound rotor synchronous motors without magnets in their interior but with windings in the rotor, too. Asynchronous motors with squirrel cage rotor, appreciated for their low costs, high operation temperatures and the user-friendliness of the drive control. Finally, reluctance motors, which exploit only the reluctance contribution to produce torque, characterized by a simple rotor, without windings, bars or magnets, and then easily manufactured, not expensive and mechanically sturdy.
Beyond the simulation and design aspect that allows attaining more performing motors than in the past, what makes an electric motor become innovative, in comparison with past decades, is undoubtedly the choice of materials. In this context, a fundamental role is played by the lamination composing the rotor and the stator.
«Today we more and more often use laminations of iron –cobalt material, characterized by better performances in the electromagnetic behaviour, broader use range before saturation and low loss figures, with unchanged induction and frequencies, compared to other materials like iron-silicon. On the other hand, iron-cobalt features lower yield stress values than iron-silicon and therefore, for high-speed applications with notable mechanical stresses, the design optimization (i.e. flux barriers for IPM motors) and manufacturing techniques, like for instance backlack, become crucial. Iron losses are also reduced by the strong rolling of stator and rotor stacks: the more we decrease the thickness of these laminations, the more we reduce eddy-effect losses The trend that is prevailing today is having laminations around 0.2mm, even if with current cutting techniques we can obtain laminations of just 55µm. Obviously, 0.2mm laminations can be easily processed with punching and laser cutting techniques and then suitable for mass-production, on the contrary, from 55µm laminations we can achieve the wished geometries only through “Wire EDM” cutting techniques, suiting small volumes».
Throughout the years, the performances of the magnets offered by suppliers constantly improve. On the market, in fact, are available products with higher values of remanence and intrinsic coercitivity than in the past, this results in higher performance with the same magnet volumes and minor demagnetization problems, with the advantage of motors that can operate at higher temperatures and with higher inner magnetic fluxes, then improved torque and power density performances.
«Speaking of the materials that compose magnets, typically in the industrial sector but also in the automotive, Neodymium-Iron -Boron (NdFeB) is broadly used.
Other magnet typology is Samarium-Cobalt (SmCo) one that, even if more expensive, has higher BHmax values than NdFeB ones for temperatures exceeding about 150/180°C, but lower values compared to the best grades of NdFeB for lower temperatures.
The SmCo magnet features then higher remanence values at high temperatures and is less affected by demagnetization problems, featuring higher intrinsic coercitivity values than other typologies. In the choice of one instead of the other, we must understand what performance target we want to reach and then the thermal class of the motor. If we decide designing a motor that operates at 200°C and over (C thermal class), SmCo magnets certainly assure better performances. Moreover, the high admissible thermal delta, with regard to the environmental temperature, allows increasing torque and power densities of the motor at unreachable values with NdFeB magnets used at lower temperatures (F or H thermal classes)».
Another variant that is increasingly present in current motors is given by a growing use of hairpins instead of wire windings that constitute the wound stator. «We are witnessing a growing use, especially in the automotive industry, of hairpins, then enameled copper bars used to form windings inside stator slots. Benefits are immediate thanks to the bigger quantity of conductive material that can be inserted into the slots, leaving fewer empty spaces among conductors and then improving also the heat dissipation capacity».
The fill factor, then the ratio between copper area and slot area, generally reaches values ranging from 0.3 to 0.6 by using copper wires; with the use of hairpins and with an optimized slot geometry for the specific conductor, it is possible to go beyond this limit. Increasing the fill factor, then having more copper at disposal inside the slot itself, with unchanged current allows reducing joule losses, and therefore improving efficiency and reducing over-temperatures; reasoning instead with the same admissible thermal delta, it means the possibility of improving motor performances and then the torque density, with the same mass and volume.
Moreover, hairpins can be rolled in such a way as to avoid skin effect phenomena in the conductor.
The heat generation is connected with losses that occur inside the motor, they can be either joule losses in stator windings, or in rotor bars for induction motors, eddy effect and hysteresis losses in the laminations of rotor and stator, eddy effect losses in magnets, friction losses in bearings and windage losses in the magnetic gap in air between stator and rotor.
«All these losses result in heat generation; improving the cooling system and then the capability of extracting this heat from the motor and of dissipating it allows making the motor more performing: the better we dissipate heat, the higher performances will be».
There are different modalities to dissipate heat and each way has different efficaciousness. In industrial ambit, we generally opt for cooling through natural convection, broadly used for brushless motors or for air-forced systems often used in asynchronous with winged enclosures; we make the air flow (moved by a fan connected with the shaft or driven by a secondary motor) on the outer enclosure of the motor, increasing the thermal exchange that would occur with the standard convection. However, the performances we can obtain from these systems are distant from the ones wished for high power density motors. To grant better performances it is necessary to choose other methods, especially for the automotive sector of sport cars, where the research of performances is fundamental.
A more performing system provides for the use of a water jacket that forms the motor enclosure, containing ducts where the coolant flows, generally a water and glycol mixture. This broadly used typology allows attaining 3-time higher heat extraction than in a motor cooled by natural convection only.
A result resembling this cooling solution is achievable through the oil spray system, i.e. the injection of refrigerated oil on the heads of stator windings, therefore directly permitting to extract heat from the copper section protruding from the stator stack.
«There is another method, more performing than all others but less used, which allows a 4.5 time higher heat dissipation than natural convection: the complete immersion of the stator inside the oil that implies an excellent heat extraction from the stator and relative windings. Currently, despite the positive results, it is not largely used because this method requires particular manufacturing devices and this means that also costs increase hand in hand with performances, rise that cannot be justified for some applications».
The integration of the perfect mix
The perfect mix of components for the best possible motor? «A motor able to encompass the best of all materials and optimal electromagnetic, thermal and mechanical design, combined with all aspects of NVH and component noise optimization. Therefore, today the identikit of the innovative motor might be a brushless internal permanent magnet motor made of samarium-cobalt, which admit a use at steady-state temperatures exceeding 180°C, possibly in C class, with direct cooling in oil; iron-cobalt laminations in backlack, researching speeds certainly surpassing 20.000rpm with reduced losses. We should not underestimate the importance of having insulating material, resins and pottings, able to withstand temperatures exceeding 200°C, for the consequent freedom of a less constrained design, able to provide higher and higher performances. The potting compounds, for instance, used to encapsulate windings, which give benefits not only in terms of electric insulation but also in the heat exchange between windings and laminations, are today limited to temperatures inferior to the C class; besides, for all those applications that provide also for a particular motor certification for the sale in some States, like UL for the United States and CSA for Canada, the thermal limit of the insulating material is fixed at much lower values than the real limit of the component, then making the pursuit of the absolute performance, and at the same time the certification of the motor for a certain market, almost impossible».
Simulation and est
The motor performance is strictly linked with design and simulations carried out before the prototyping and production phases are fundamental. In a first step, it is possible to use 1D concentrated parameter calculation software for both the preliminary sizing and thermal simulations. In a second phase of more accurate optimization, FEM and CFD finite element simulation software, both 2D and 3D, are used, thus covering all the aspects that characterize an electric motor, from the electromagnetic circuit to mechanical, thermal and NVH performance, up to the study of the behaviour that occurs when the motor operates inside the application system, such as for instance an electric axle or an entire powertrain. «A study of this kind, then more in-depth, with more accurate simulations, addresses for instance the automotive ambit because torque and power densities of the motors intended for the most performing cars, are at the limit of technical possibilities, especially for high-speed applications or wherever we try to optimize efficiency at best or to exploit as much as possible the admissible thermal jump from used materials.
Besides the simulations, there is a key step: the test on the manufactured motor. It is not sufficient, in fact, to design and to simulate it, it is necessary to be able to test it accurately once manufactured, especially concerning the first prototypes, in order to validate the simulations executed; collecting precise data on prototypes allows carrying out the due optimizations in the second phase of simulations; besides, it is possible to acquire the necessary inputs for other simulation typologies, hardly executable without a first test phase, like for instance the airborne simulations for the definition and the reduction of noises».
The excellence of AVL deserves to be highlighted not only due to the capability of designing highly performing motors but also for the ability of integrating them at best inside use systems, to the ends of real innovation that provides for the integration of the electric motor with power electronics and mechanical transmission.
«What we are developing as AVL is an integrated design package, where the whole motor enclosure is devised for its connection with the inverter and the gearbox. All that allows achieving a noteworthy reduction of sizes and weights and then making the real difference in some applications, such as the automotive ambit».
Released on the market by WEG, the device enables electric motors to play a protagonist role in the Industry 4.0 ambit. A technological solution that allows minimizing, or even eliminating, machine downtimes and remarkably improving the manufacturing process efficiency.
Motors are always subjected to strong stresses and long operation hours and it is unavoidable they are affected by a certain wear level. However, they unfrequently break down without warning. Usually, the signs of an imminent failure are anticipated by an increase of vibrations and by the high temperature. Parameters that, if not controlled and supervised carefully, can lead to unexpected stops, plant downtimes and therefore undesired financial losses. Consequently, the constant monitoring of vibrations, of temperature and of operation time becomes decisive as well as necessary to the ends of higher competitive edge. The timely warning of potential problems allows in fact executing the due maintenance and repair interventions, thus avoiding unscheduled interruptions. Definitively, a constant monitoring can increase productivity, improve quality and rise profits. Precisely in this context, WEG, one of the major world manufacturers of cutting-edge motors and drives, presented Motor Scan.
«We are referring to a user-friendly and effective device – explains Fabrizio Arosio, automation business manager of WEG Italia – that allows the remote monitoring of WEG motors, in order to maximise the use time and to permit both preventive and predictive maintenance activities». This technology allows in fact maintenance technicians to take informed decisions about the «health state» of installed motors and to react consequently, according to the acquired data.
From the motor to the IIoT, from Big Data to higher competitive edge
Available for frame sizes from 100 to 450, the device by WEG grants immediate usability. It exploits the Industry 4.0 digital technology, which includes Industrial Internet of Things (IIoT) and Big Data Analytics to offer its customers a competitive edge in this dynamic and complex activity sector. Due to its devising and development, the device aims at avoiding the boring manual collection and monitoring of data, at removing the conjectures about preventive maintenance and at eliminating the inefficiency of the reactive maintenance.
The company in short
WEG is one of the major world manufacturers of electric equipment, with five main Business Units: Motors, Energy, Transmission and Distribution, Automation and Coatings. The company employs around 30,000 people and over 3,000 engineers worldwide, with a global sale turnover amounting to 9.5 billion R$ in 2017. Its solutions in the field of the energy generation, transmission and distribution allow companies working in several sectors (in particular in the field of oil & gas, water & wastewater, energy distribution and in the chemical and petrochemical sectors), to operate more efficiently and to decrease the energy consumption, the emissions of carbon dioxide and the environmental impact. Besides, WEG offers complete solutions for projects in the renewable energy ambit, through complete systems of wind turbines and photovoltaic systems.
«Motor Scan – adds Arosio – can predict and highlight a problem before it occurs. In a certain sense, it is as if we had a sort of crystal ball that allows knowing what will happen in the future. We believe that, preventing a problem before it occurs is the attainment of the best efficiency in terms of cost and maintenance. The device exploits the IIoT and the analysis to connect sensors and other devices aimed at collecting and analysing data in real time and besides it offers transparency in the adoption of immediate preventive actions. Moreover, our new solution helps customers in increasing the safety of their plants, remaining anyway competitive in this demanding constantly evolving sector». The sensor can be easily installed (even in a time following the motor installation) through a clamp and today it can detect vibrations, surface temperature, operation hours, speed and start/stop through a Bluetooth connection. For practical reasons, the collected data are stored in the cloud and users can exploit an available app for both iOS and Android, on their smartphones or tablets, to gain access to it. Besides, the access to data on laptop and desktop is enabled by a dedicated Web portal. A powerful analysis system allows processing data and anticipating possible hidden anomalies or problems according to the analysis of the frequency spectrum. Various warning levels, according to acceptable reference values of temperature/vibration, are pre-set, with the possibility of tracing performance curves on the basis of the collected data.
The added-value of a correct sizing
«Actually – adds Arosio – simultaneously with the installation, through the input of the univocal identification code of the single motor, the device automatically recognizes dozens and dozens of further product information, from the number of coils to their type of winding. Data that, through apposite algorithms, in the future will also enable, besides other things, to control the frequency, the efficiency and the real absorption in real time of the motor».
Moreover, these data will permit to check the correct motor sizing depending on the specific application. With noteworthy saving benefits.
«In fact, it quite often happens – further highlights Arosio – that starting from the designer’s initial sizing, to comply with the regulatory tolerances and so on, you achieve a motor used not by 100% but with much lower efficiencies. In other words, motors might be oversized or also undersized with respect to the load they are intended for. Discrepancy that unavoidably leads to some inefficiencies».
An oversized motor consumes more electric energy owing to a low power factor that increases costs. On the other hand, an undersized motor causes overheating. Therefore, it is important to monitor the motor load and to match the motor with its effective requirements, in order to improve the system performances and generate cost saving. For a certain number of years, in fact, the achievement of the energy efficiency has been the key target of industry. However, there is a concrete problem concerning the motor-load correspondence. Some energy savings must be obtained through the «right sizing». For this reason, the future evolution of Motor Scan will include the motor measuring.
Stop to vibrations, high temperatures and possible degradations of components
As already mentioned, the rise of vibrations, the high temperature and prolonged operation time of the motor can generate some risks, with undesired effects on the process where it is used. More in detail, anomalous vibrations come from electric or mechanical unbalances inside the motor. The electric causes include the variation of the flow around the stator that produces a variation of forces between the stator and the rotor, a broken rotor bar or a short circuit that involves a part of the winding. Mechanical causes include instead an unsuitable motor base and defective bearings.
«The complications caused by vibrations – points out Arosio – can for instance accelerate the bearing yielding, resulting in recesses on the tracks at the distance between balls or rollers».
Concerning temperature, some components, especially mobile parts, tend to release unusual heat quantities when they degrade. The presence of excessive heat can indicate an excess of friction, i.e. the presence of misalignments of components that rub one against the other (and they should not).
«According to some studies carried out – underlines Arosio – they estimate that each 10° rise of the operation temperature of motor windings, compared to the setup temperature, corresponds to the 50% reduction of the insulation duration of motor windings, even if the overheating is only temporary».
The effects of a protracted operation time can finally affect the fast degradation of some motor components. This occurs owing to the accumulation of overheating and stresses.
«To prolong the motor service life – notices Arosio – it is decisive, as well as important, monitoring the operation time and ascertaining that an excessive use is avoided. Moreover, the monitoring can offer the opportunity of an energy saving, permitting to switch motors off when they are not in use».
Reducing the motor operation time by just 10%, you achieve an energy saving that exceeds the one achievable by replacing a standard efficiency one with a high-efficiency execution. In short, the effective Motor Scan device not only allows eliminating the monotonous manual collection and monitoring of data but also makes preventive maintenance suppositions superfluous and actually annuls the inefficiency of the reactive maintenance. Besides, training maintenance technicians according to the particular requisites of predictive maintenance, it offers companies the opportunity of developing the staff’s skills, widening their capabilities and competences.
Axalta, a global supplier of liquid and powder coatings, launches Voltacast 3310/Voltacast H134, a new epoxy-based casting resin system that expands the Voltacast product portfolio of casting resins from Axalta’s Energy Solutions business.
Voltacast 3310 is specifically designed to offer high thermal stability in combination with high thermal conductivity for winding head encapsulation or total stator encapsulation of electric motors, like servo drives or large machine tools.
“We are always looking to expand our product portfolios and to meet the ever-evolving needs of our customers,” explains Christoph Lomoschitz, Global Product Manager for Axalta’s Energy Solutions business. “Voltacast 3310 ensures outstanding resistance to a variety of automatic transmission fluid oils used in electric vehicles, and its high thermal conductivity in combination with oil cooling of electric motors allows maximum heat dissipation.”
Voltacast 3310/Voltacast H134’s anhydride-free system can be cured at room temperature or preferably at temperatures up to 70ºC. The cured material is flame retardant, fulfilling the requirements of Underwriters Laboratories (UL) standard 94, class V0, and will shortly receive official UL recognition. The new Voltacast 3300 range is comprised of two-component systems – an epoxy resin and a hardener. The products of the Voltacast 3300 range offer superior thermal conductivity, from 1.2 W/mK up to 1.6 W/mK, without compromising an easy and safe application, as the processing viscosities are only 2200 mPa*s to 2400mPa*s at room temperature. The new Voltacast materials are very versatile, with glass transition temperatures of 24ºC, 60ºC and 95ºC, depending on the final application requirements.
50 years of experience have led the Vignati Group to develop strict processing methods with quality meeting the highest standards, with technical skills enabling it to assist customers even in conceiving and creating complex subassemblies.The Vignati Group is specialized in the production of complex technical components, including the production of moulds and dies. Its main areas of business are: appliances, automotive, electronics and electromechanics; medical; telecommunications.
The Vignati Group provides prototyping services through its prototype manager: analysis of details prior to industrial launch; launch of mould and die design; validation of designs; production of moulds and dies; testing and compilation of specific technical dossier; product qualification; assembly as customer requirements; correct management of the industrial engineering process is the key to reducing technical risk, thus reducing costs and meeting programming deadlines and quality standards; partnership with high-level laboratories to offer services marked by active participation in the development of the component and its function right through to the creation of the subassembly, featuring quality and performance without the high costs.
Next to liquid sealants, thermal interface materials, adhesives and impregnation resins for new-generation battery packs, Henkel is leveraging existing and new products and technologies for the emerging trend towards e-drive modules combining electric motor, power electronics and gearbox in one integrated e-axle unit. In addition, customers are also supported with appropriate design guidelines and recommendations for process requirements including equipment enabling automated high-volume production.Henkel’s portfolio for the entire value chain of e-drives manufacturing is focused on six key application areas: liquid gasketing, potting, pcb technologies, magnet bonding, impregnation service and parts cleaners and lubricants.
A polyacrylate technology – Loctite AA 5831 – is used for protection and fixation of parts in the e-motor or in the conversion electronic control unit. The compound has an ideal fit in large-series potting operations and cures within seconds under UV light and moisture. For e-drive stator coil potting applications, Henkel offers the two-component epoxy technology of Loctite PE 8082 which has a thermal conductivity of 1 W/mK, resulting in a significantly reduced working temperature. In addition, it shows outstanding oil resistance. Loctite EA 9497 is used for the bonding of magnets inside the e-motor. The two-component epoxy adhesive has proven its long-term reliability in this application segment, combining a wide operating temperature range of -55°C to +200°C with high mechanical strength as well as good chemical and oil resistance. With its added thermal conductivity, it also supports a more efficient thermal management.Parts cleaners and lubricants: Henkel’s range of machining products along with parts cleaners help to maintain a cleaner part through the entire process to ensure tight tolerances and reduce residues on parts, especially when used on sensitive e-drive modules.
Hypercars push the exclusivity concept to extremes: they are vehicles that are part of very limited series, with sports aesthetics and exasperate performances, by far exceeding conventional sports cars. Often, hypercars propose innovations in advance compared to the other cars and they are used as test bench to diffuse determinate technologies on more “reachable” vehicles.
We are speaking of a parallel world, of an extra-luxury market that exists thanks to an elitist niche of people looking for adrenaline, fond of motors and performances, willing to pay very high amounts to own and to drive vehicles that represent the utmost expression of the automotive technology. Hypercars satisfy on four wheels man’s natural bent for overcoming limits and it is unavoidable that such extreme cars make us dream, engaging in the design smart minds of skilful and enthusiastic engineers like Francesco Mastrandrea from AVL, the interviewee of these pages.
What a hypercar is
The engineer Francesco Mastrandrea has helped us to define “hypercars”: vehicles that belong to very limited series, with sports aesthetics and exasperate performances, by far exceeding the traditional sports cars. «These cars – the engineer Mastrandrea explains us – must be framed in the context of their historical period and borders are anyway undefined. A car considered hypercar in the Eighties, like for instance the F40, today would be deemed “just” a sports car, neither with particular qualities; let us think that a current Alfa Romeo Giulia Quadrifoglio Verde, apparently a common sedan, has 510 horsepower and overall performances that exceed a hypercar dating back to 25 years ago».
How were they born and what is their origin? The motivation should be sought in the precise essence of man and his will of overcoming the imposed limits. There have always been people who are not satisfied with standard vehicles and the hypercar concept was devised precisely with the advent of cars; we remember that in the Sixties there were already several brands that modified “standard” cars to create unique models intended for exclusive users. «Often, hypercars propose innovations in advance compared to the other cars and they are often used as test bench to diffuse determinate technologies on more “reachable” vehicles. “LaFerrari”, for instance, with its hybrid powertrain has anticipated some years earlier the use of this technology on the rest of Ferrari range».
Hypercar VS Supercar
If performances, very high cost and sports aesthetics might almost be shared by hypercar and supercar, there is a neatly different factor: the production modality.
ZOOM ON A HYPERCAR
Among all hypercar models, the engineer Mastrandrea highlighted the excellence of C_Two by Rimac (the pronounce is Rimaz), small Croatian automotive company specialized in electric cars owned by 10% by Porsche. The vehicle has been created in the name of lightness and aerodynamics: monocoque body and roof are completely made of carbon fibre, the rest of the bodywork is a mix formed by reinforced carbon fibre and aluminium. The battery pack can develop an energy peak of 1.4 megawatt, then it is equivalent to 1,914 CV, for a maximum torque of 2,300 Nm. These values allow Rimac C_Two to accelerate from 0 to 100 km/h in 1.85 seconds (a bit optimistic) and from 0 to 300 in 11.8 seconds. All that with zero emissions and a drive autonomy of 650 km (in ideal conditions).
«I had the lucky opportunity – told us the engineer of AVL – of living some phases of the creation of these vehicles. Hypercars further heightens the exclusivity concept: very few are produced upon customers’ specific demands and a direct relationship between buyer and manufacturer often emerges, with production logics that are more similar to the ones of an expert artisan.
Another differentiating factor concerns the availability on the market. Sport cars, even if with long wait times and for few people, are accessible because they are anyway catalogue cars. The price as well shares in creating a gap between the supercar and the hypercar: if the cost of a sports car range from 300 to 500,000 euros, a hypercar generally starts from one million of Euro, with some small exceptions. «Not many people in the world can afford it but more than we can imagine. They have manufactured 500 Ferrari hypercars whose cost is 1.7 million Euros and they were fully booked before the production started. In this market slice everything is relative: if you have already a yacht moored at the port and other three Ferrari in the garage, spending almost 2 million Euros for a car is quite coherent, obviously in that context».
Another aspect that characterizes this segment is the second-hand market that has opposite logics to the “traditional” one”. «Recently, a Ferrari 250 GTO of 1962 was auctioned for the record figure of 48,405,000 dollars. Then, they are vehicles not affected by devaluation but, contrary to normal supercars, they gain higher value as soon as the leave the dealer».
THE FLOOR TO THE EXPERT | The electric hypercar
How much does the motor influence the acceleration of a hypercar? The acceleration is mainly linked with the torque that the traction system can deliver in the time unit, besides the characteristics of tire/asphalt and other less relevant factors like the weight distribution, asset, aerodynamics, control system and frame stiffness. To obtain the highest possible torque, referring to the only motor is reductive but it is necessary to include the battery and the inverter, too. These elements, if not correctly sized, would represent a bottleneck for the performances that can be actually delivered: it would be as if we imagined of scoring the high jump record with half of our legs’ muscles and our hands behind the back. What are the main pluses for an electrified hypercar?
Primarily, the maximum torque at zero revolutions granted by the electric propulsion that allows immediacy in the response to the impulses of the accelerator and not losing time in gear changes. I add that the centre of gravity is positioned lower than in an endothermic vehicle for the favourable positioning of the battery, with remarkable advantages linked with load transfers; this improves the longitudinal performances, then acceleration and braking. Electric hypercars are often provided with four independent motors, therefore it is possible to deliver adequate torque to each wheel and to exploit the adhesion limit of the tire, optimizing its traction qualities. The use of electronic differentials in a vehicle with endothermic motor does not allow a so efficacious control. What are instead, still today, the most critical aspects?
Mainly the weight that is strictly connected with the energy density of the battery. Today it reaches about 250 wh/kg, still not sufficient to be competitive in terms of revolution performances with an endothermic vehicle. Having two independent motors on the same axle means to have to emulate a traditional differential but with licit perplexities concerning safety: a wrong signal to one of the two motors while the vehicle is engaged in a curve can have disastrous consequences. Therefore, huge efforts are necessary in this ambit, to optimize performances and safety. If a great quality of an electric motor is the easy development of a high instantaneous power, the delivery continuity represents a critical element. Rimac hypercar, for instance, declares powers approaching 1500 kW, probably it succeeds in maintaining them just for few seconds and only under certain conditions of external temperature and battery charge. The endothermic motor, on the contrary, grants the same performance for a prolonged time, with the exception of modest variations depending on environmental conditions like temperature, pressure and relative humidity. The challenge consists in managing the cooling so that temperatures remain as slow as possible; one of the main dangers is precisely the heat released by electric components and this limit compels to declass significantly the torque delivered to wheels when you pursue the highest performances. Creating a high-performance electric vehicle is a committing, but at the same time exciting, challenge because it deals with consolidated technologies, refined in dozens of years. Certainly, the endothermic vehicle starts in advantage but we are quickly recovering». What is the next frontier?
Operation voltages exceeding 1000V and batteries at the solid state. We will see incredible things… What is your favourite hypercar?
It is the fully electric hypercar that we would like to develop here, in our technical centre, and we hope we will soon have the opportunity. We work at research and development for most of our time and it is part of our job to recognize as passable those barriers that others deem unsurmountable.
*AVL is an Austrian multinational and in Italy it has a futuristic technological hub at Cavriago, in Reggio Emilia province. The company’s activity consists in research and development on advanced powertrain systems, from traditional internal combustion engines up to purely electric motors and encompassing the revolutionary fuel cells. The ITS division of AVL works at the design and manufacturing of test benches for the test and the validation of traction systems.
Torque control: the torque vectoring
Sports cars are equipped with an electronic differential that splits the torque on the two wheels of the same axle by means of small clutches assisted by hydraulic brakes, optimizing the drive dynamics. In electric cars, it is possible to manage the torque repartition more accurately and quickly thanks to the architecture with independent motors for each wheel. The advantages of this system are partially unexplored; several companies (AVL included) are working to exploit its potentialities at best.
Axalta’s bespoke automotive products provide electrical insulation solutions and are designed to improve the performance levels of modern electric motors. They include Voltron wire enamel, Voltatex 4200 for impregnation, and adhesive electrical steel coatings such as Voltatex 1175W and Voltatex 1075K. Axalta has been a global supplier in the manufacture of high-quality, high-performance liquid insulating systems and materials for over 70 years and it supplies its Energy Solutions range of Impregnating Resins, which provide mechanical stability and insulation for electrical motors in full electric as well as hybrid vehicles, to nearly all well-known light vehicle OEMs. Michael Glomp, Vice President of Axalta’s global Energy Solutions business, says, “The development of efficient, high-performance and reliable engines for hybrid and electric vehicles continually presents new requirements and challenges for electrical insulation materials.”
This latest release of Ansys Pervasive Engineering Simulation solutions empowers more users to accelerate the design process with its new single window, efficient workflows and patent-pending advanced meshing technology for computational fluid dynamics (Cfd). Users will greatly benefit from new processes for developing embedded software for safety-critical applications, dramatic computational speed and user experience improvements.
The Ansys systems suite has new features and functionalities that are essential for the development of digital twins, autonomous and electric vehicles. New capabilities in make it easier and faster to build, validate and deploy digital twins. Now users can visualize 3D fields of static Roms and view simulation results, like velocity and flow rate, on the 3D geometry.
With the recent acquisition of Optis, Ansys is introducing Ansys Vrxperience. This new solution takes predictive validation of vehicle systems to the next level – meeting any virtual reality simulation and validation need for autonomous vehicle simulation, including complex systems such as intelligent headlamps, interior and exterior lighting, autonomous vehicles controls and HMI validation. Vrxperience also enables users to fully and realistically simulate autonomous vehicles using real-world conditions, including various weather and road conditions, oncoming vehicles, pedestrian scenarios and anticipating the vehicle’s reaction to any critical situation.
Drives constitute an essential part of the manufacturing sector because they are the real “muscles” of CNC machines. in this article the main typologies available on the market are analysed.
The drive is a suitable system for performing a linear or rotary motion and includes both the motor and its control system. It is possible to classify them according to the three main application fields:
Drives for the spindle rotation;
Drives for x,y, z linear axes;
Drives for circular axes
Historically, concerning the spindle, they used systems with motion transfer to belt and gears: the latter allowed achieving a transmission whereas the belt reduced vibrations. Such system assured high power and torque values but low speed values. The motion transmission could occur also through a coupling: this represented a “safety” aspect for the machine tool because, in case of anomalies, it broke down without damaging the machine. In comparison with the first case analysed, the motion transmission through coupling assured higher speeds to the detriment of powers. Precisely the electrospindle has allowed finding the right compromise in terms of speed and power (that is to say, integrated motor and spindle). This has also enabled to obtain more compactness and lower vibrations.
Motors integrated into the spindle
Until 2000, DC motors were used but with the advent of technology and a substantial improvement of power electronics (more and more powerful microprocessors and development of inverters), it was possible to introduce AC ones. Direct current motors allow a precise regulation of torque and nominal power. However, they are scarcely sturdy and rather expensive, besides needing a quite ordinary maintenance of the collector and of brushes. Moreover, they are cumbersome motors (in general, speed increases hand in hand with sizes). As time went by, alternating current motors were developed. The have discretely adjustable speed through a speed gear but they also strongly depend on frequency, as indicated in the following formula:
n = 60*f/p
n= rotation speed (rpm)
f= net frequency
p=number of polar torque
A noteworthy novelty was the introduction of the inverter that, in alternating current motors, has allowed varying the net frequency, permitting to increase the variability range of the motor speed. AC motors are very reliable, simple and highly performing. In CNC machines is broadly used the so-called electrospindle, a very compact and stiff system, which allows achieving high torque and speed.
Motor of linear axes
To move the linear axes of the machine tool, rotary motors are almost always used and therefore it is necessary to combine a system that transforms motion from rotary to translating. The motion transformation system is composed by a system with re-circulating ball screw in case of CNC machines and by a screw-nut screw system in case of a conventional machine. In general, the characteristics demanded to a motor for linear axes are the following, as listed below:
Each axis must be equipped with an independent drive;
Motors must be compact;
They must permit progressive speed variations;
They must have very high rapid feed speeds to reduce transients as much as possible;
High pickup and braking currents;
Among the solutions most adopted, it is worth highlighting:
DC servomotor with permanent magnets. Generally, the DC motor that powers the spindle is equipped with windings on both the stator and on the rotor and therefore they are independent excitation motors. In the motor for linear axes, the windings on the stator are instead replaced with permanent magnets. Windings are mounted on the rotor and they receive electric current from brushes. The latter, however, are subjected to wear and, for that reason, they need periodic maintenance. To avoid that, “brushless” servomotors are used, in other words without brushes and with magnet on the rotor and winding on the stator part. In this way, motors become even more compact but the problem of the rotary magnetic field management emerges. Therefore, powering the winding on the stator in controlled manner becomes necessary, in order to minimize torque and speed oscillations. Hall-effect sensors are used, as they can manage the switchover of the winding on the stator as they detect the magnetic field generated by the rotor and its relative position as to the rotor. Concerning the switchover, it generates some torque instabilities called, precisely, torque ripples. The main advantages of a brushless motor, in comparison with a standard DC motor with permanent magnets, are the following:
Higher rotation speed;
Inferior nominal torque to the DC one but with a maintenance of the torque itself for a much longer time;
Smaller overall dimensions;
2. Stepper motor. It is a synchronous motor where the rotation speed is varied by changing the frequency of control pulses. The operation is very simple: whenever the motor detects a pulse, it rotates by a certain angle. The torque in this case is not constant but it rapidly decreases as the speed rises. It is a very precise motor and therefore it grants certain result sureness. Sizes are very small.
Motors for rotary tables
Recently, they have developed linear motors that allow solving the problem of the motion transformation from rotary to linear, because approximate 15% losses occurred with the motor transformation. The linear motor is a real “linearization” of the brushless motor. It is worth noticing that the motor is as long as the axis to be driven. Therefore, magnets must be perfectly aligned. Then, we refer to:
Long inductor, when magnets are positioned on the fixed part;
Short inductor, when magnets are positioned on the mobile part.
Among the advantages, we are pointing out:
Nevertheless, they are affected by some relevant limits, like: