Scania now launches its first fully electric truck. With a range of up to 250 km, the Scania electric truck can operate during the whole day and still return safely to its home depot for overnight charging. If there is a need for an extended range, the driver can fast charge the truck over a break or during natural stops in operation.
The truck is available with the option of either five, for a total of 165 kWh, or nine batteries totalling 300 kWh installed capacity. With five batteries the range is 130 km. The range is, of course, dependent on the weight, body type and topography.
With the combustion engine removed, space for batteries has been freed. Additional batteries are mounted on the chassis frame. The new electric motor delivers a continuous power of 230 kW or approximately 310 hp. The motor has two gears to provide high power over a wider speed span, thereby improving comfort.
One of the major benefits with an electric motor compared with combustion engine is its high controllability. In practice, the customer will experience this through faster acceleration and response from the powertrain.
Other components needed for fully electric propulsion, such as battery management units, battery cooling components, electrohydraulic steering system, electric air compressor and inverter are also mounted along the chassis frame.
Scania’s battery electric truck comes equipped with a CCS charging connector to charge from the electric grid. With 130 kW DC charging, the five battery packs will be charged in less than 55 minutes and the nine batteries in less than 100 minutes. The truck can also be charged through regenerative braking.
Scania’s new truck is equipped for a fully electric power take off. Instead of connecting auxiliaries to the interface that is usually located on the gearbox or engine, it is instead connected to an electrical connection box, called a DC box mounted on the chassis. This gives a DC link of up to 60 kW PTO for body auxiliaries such as refrigeration systems and hooklifts.The Scania electric truck is available with the L- and P-series cab, both of which are designed for urban operations. The low-floor L-series cab, particularly, is purpose-designed for congested city conditions with unrivalled visibility.
“Sustainable emission-free transport is an increasing requirement for transport companies,” says Anders Lampinen, Director, New Technologies. “Acquiring an electric truck is not just an investment in the customer’s fleet, but also in its brand and market. The electric truck enables the customer to stay ahead of the competition, learn about infrastructural challenges and start adapting for the future.”
Ken Block's Ford Fiesta ERX won this breakthrough event at the famous Holjes rallycross circuit in front of two identical Fords.
Built by Austrian firm STARD, the cars boast three electric motors, producing 600 horsepower and 1,000 Nm of torque combined. It can go from zero to 100km/h in 1.8 seconds, according to the race team, with a top speed of 240km/h. Each axle gets its own 2-speed transmission, although only one gear is used in races. Brake and torque bias is adjustable front to rear but the STARD powertrain does not have AWD torque vectoring.
Hyundai Motor successfully demonstrated its leadership in electrified mobility as three KONA Electric vehicles set a new range record.
Over the course of a three-day range mission, the pure electric subcompact SUVs each travelled 1,018.7, 1,024.1 and 1,026.0 kilometers (km), exceeding the goal of 1,000 km on a single battery charge. Each distance also represents a record in terms of 64 kWh battery capacity, as the power consumption figures of 6.28, 6.25 and 6.24 kWh per 100 km were well below the standard value of 14.7 kWh per 100 km determined by the Worldwide Harmonized Light Vehicle Test Procedure (WLTP).
“This mission has proven that our KONA Electric offers outstanding electric performance, efficiency and battery range,” said Michael Cole, President and CEO of Hyundai Motor Europe. “This lifestyleoriented vehicle will continue to offer customers a range of sophisticated technology and an attractive design of a compact SUV in addition to all the advantages of an environmentally friendly electric vehicle.”
The nearly 35-hour test took place at Lausitzring, a racetrack in northeast Germany. Dekra, a European vehicle inspection company that has operated at Lausitzring since 2017, monitored the test process and vehicles, recording 36 driver changes.
All vehicles used in the test were factory-spec and unmodified, equipped with standard Nexen N Fera SU1 low rolling resistance tires in the 215/55R17 size. Each vehicle’s air conditioning and entertainment systems remained off, with available power used solely for propulsion. Only the daytime running lights remained on to comply with the legal requirements for road traffic.
The drive teams - one from the renowned German trade magazine Auto Bild and two from Hyundai Motor Deutschland - recorded an average speed between 29 and 31 km/h to reflect typical innercity traffic speeds in Europe. On the third day, the vehicles managed to cover over 20 km with only 3 percent residual capacity. At zero percent charge, the vehicles continued to drive for several hundred meters before running out of power and coming to a stop.
“With this test, the KONAElectric confirmed what many of our customers already know: it is a reliably efficient and eco-friendly lifestyle SUV that is practical for everyday use,” said Jurgen Keller, Managing Director of Hyundai Motor Deutschland GmbH. “Customers driving the KONA Electric or other Hyundai EVs can expect to drive long distances without recharging or feeling range anxiety.”
Hyundai Motor recently revealed its plans to lead the global EV market with the launch of its new IONIQ brand dedicated to battery electric vehicles. The company will introduce three new EV models over the next four years and offer customer-centric EV experiences in line with its vision ‘Progress for Humanity’. Hyundai Motor Group, the company’s parent entity, aims to sell 1 million units of battery electric vehicles and take 10 percent market share to become a global EV leader by 2025.
Researchers from the Samsung Advanced Institute of Technology (SAIT) and the Samsung R&D Institute Japan (SRJ) presented a study on high-performance, long-lasting all-solid-state batteries to Nature Energy, one of the world’s leading scientific journals.
Compared to widely used lithium-ion batteries, which utilize liquid electrolytes, all-solid-state batteries support greater energy density, which opens the door for larger capacities, and utilize solid electrolytes, which are demonstrably safer. However, the lithium metal anodes that are frequently used in all-solid-state batteries, are prone to trigger the growth of dendrites1 which can produce undesirable side effects that reduce a battery’s lifespan and safety.
To overcome those effects, Samsung’s researchers proposed utilizing, for the first time, a silver-carbon (Ag-C) composite layer as the anode. The team found that incorporating an Ag-C layer into a prototype pouch cell enabled the battery to support a larger capacity, a longer cycle life, and enhanced its overall safety. Measuring just 5µm (micrometers) thick, the ultrathin Ag-C nanocomposite layer allowed the team to reduce anode thickness and increase energy density up to 900Wh/L. It also enabled them to make their prototype approximately 50 percent smaller by volume than a conventional lithium-ion battery.
This promising research is expected to help drive the expansion of electric vehicles (EVs). The prototype pouch cell that the team developed would enable an EV to travel up to 800km on a single charge, and features a cycle life of over 1,000 charges.
As Dongmin Im, Master at SAIT’s Next Generation Battery Lab and the leader of the project explained, “The product of this study could be a seed technology for safer, high-performance batteries of the future. Going forward, we will continue to develop and refine all-solid-state battery materials and manufacturing technologies to help take EV battery innovation to the next level.”
It won’t hurt your ears and doesn’t use a drop of fuel, but it’s projected to crush the quarter-mile in the low-8-second range at more than 170 mph. For the first time ever, Ford Performance introduces a one-off Mustang Cobra Jet factory drag racer with all-electric propulsion.
The battery-powered Mustang Cobra Jet 1400 prototype is purpose-built and projected to deliver over 1,400 horsepower and over 1,100 ft.-lbs. of instant torque to demonstrate the capabilities of an electric powertrain in one of the most demanding race environments.
“Ford has always used motorsport to demonstrate innovation,” said Dave Pericak, Global Director, Ford Icons. “Electric powertrains give us a completely new kind of performance and the all-electric Cobra Jet 1400 is one example of pushing new technology to the absolute limit. We’re excited to showcase what’s possible in an exciting year when we also have the all-electric Mustang Mach-E joining the Mustang family.”
Following the debut of the all-electric Ford Mustang Mach-E SUV – the first-ever, all-electric Mustang, the Mustang Cobra Jet 1400 prototype represents another opportunity to advance Mustang heritage and performance while simultaneously incorporating some of the most advanced technology coming to Ford’s future powertrains.
Mustang Cobra Jet 1400 also honors the original Cobra Jet that first dominated drag strips in the late 1960s and still is a major force in sportsman drag racing today.
"This project was a challenge for all of us at Ford Performance, but a challenge we loved jumping into,” said Mark Rushbrook, Global Director, Ford Performance Motorsports. “We saw the Cobra Jet 1400 project as an opportunity to start developing electric powertrains in a race car package that we already had a lot of experience with, so we had performance benchmarks we wanted to match and beat right now. This has been a fantastic project to work on, and we hope the first of many coming from our team at Ford Performance Motorsports."
Ford have yet to reveal any technical information about the electric Cobra Jet’s motors, batteries etc but we can have a few educated guesses:
Motors: 2x AM Racing Dual Stack 250 Motors. Most likely 2x of these motors are stacked vertically for a grand total of 4x HVH Remy 250 cores.
Transmission: The video sounds like a 2 speed Powerglide.
Rear-end: Most likely shortened Ford 9 inch diff - typical drag racing equipment.
*Note: RMS & AM Racing are now owned by Borg Warner under the new name Cascadia Motion. Remy is also owned by Borg Warner.
Ford Performance continues to test Cobra Jet 1400 ahead of its world debut later this year at a drag racing event where fans, media and competitors alike will get to meet the race car, as well as see exactly what it’s capable of up on the asphalt.
Before that, catch a sneak peek starting this Sunday, April 26 by watching MotorTrend On Demand’s “Hard Cell”, a showcase of electric vehicles pushing innovation boundaries.
To maximize the efficiency and effectiveness of the project, Ford Performance has teamed up with several capable and specialized suppliers:
MLe Racecars – Vehicle builder, designer, integrator and tuner
Watson Engineering – Chassis support and development, roll cage builder
AEM EV – Software and motor calibration and controls
Liebherr and Designwerk have developed the first fully electric truck mixers with 10 and 12 m³ drums on a 5-axle chassis. The first operations are planned for our customers Holcim and KIBAG in Switzerland. This design is perfect for Switzerland, where vehicles with a gross vehicle weight of 40 tonnes are allowed to drive on 5 axles.
Concrete production in the concrete plants is clean and environmentally friendly, as the mixing plants operate electrically. This is not yet the case when transporting the concrete to the construction site: Up to now, powerful diesel engines have been the norm for such applications - combined with emissions in terms of exhaust gases and noise.
The new ETM 1005 and 1205 truck mixers on a chassis from Futuricum will change that: They transport large quantities of concrete to the construction site quietly and reliably without exhaust emissions. Since distances from the concrete plant to the construction site are relatively short compared to freight traffic, this all-electric solution is particularly well suited for this application. Moreover, the vehicles return to the concrete plant again and again, where there is a charging infrastructure for the batteries. Thanks to large accumulator capacities, charging the batteries is normally only necessary overnight. The Futuricum chassis is extremely powerful, with the equivalent of 680 HP, and can easily cope with the weight of the concrete. Energy recovery during braking or downhill driving further increases the range of the truck and reduces operating and maintenance costs.
The drum drive developed by Liebherr and ZF consists of a low-maintenance and efficient unit of electric motor and mixer gearbox. For the first time, both the truck and the truck mixer body are powered jointly by the traction battery, eliminating the need for costly power electronics components. The new Liebherr Generation 05 electrified body offers further advantages: The compact electric drive for the mixing drum is flanged directly to the drum and its high efficiency ensures that power consumption for relieving the traction battery of the Futuricum truck remains low. It also eliminates the need for any hydraulic equipment - no hose connections, no pump, and therefore no risk of leakage. Liebherr's truck mixer body boasts a low net weight combined with the best possible transport volume, a long service life thanks to its special wear-resistant steel and the ergonomic design of the operation system and access points. A platform system on both sides allows flexible positioning and attachment of accessories or attachments to suit customer requirements.
All subassemblies, chassis and mixer bodies are optimally matched to each other by Liebherr and Futuricum. The weight distribution across the axles is ideal for very good driving characteristics. A temperature management system ensures that the components are cooled or heated as required. The ETM 1005 and 1205 on Futuricum chassis are a real breakthrough when it comes to environmentally friendly concrete transport.
Audi is systematically moving forward with its e-offensive: The Audi e-tron and the Audi e-tron Sportback are becoming more agile, sharper and more dynamic as S models.
The three electric motors, two of which are located on the rear axle, together provide 370 kW of boost power and 973 Nm (717.6 lb-ft) of torque. This allows the two purely electrically driven models to accelerate to 100 km/h (62.1 mph) in 4.5 seconds. The intelligent drive control raises vehicle safety, and dynamic handling in particular, to a new level: In addition to the electric all-wheel drive, there is the electric torque vectoring with active and fully variable torque distribution on the rear axle.
The driving experience of the two prototypes for the Audi e-tron S-models cannot fail to impress with its level of dynamism, agility and traction increased once more. In the S gear, both cars go from a standstill to 100 km/h (62.1 mph) in 4.5 seconds – almost seamlessly and nearly no noise – propulsion does not end until 210 km/h (130.5 mph), limited electronically. Thanks to a powerful cooling system, the drive gives the full boost power of 370 kW and 973 Nm (717.6 lb-ft) of torque in reproducible form for eight seconds in each case. The nominal values in the D gear without boost are 320 kW and 808 Nm (596.0 lb-ft).
In terms of handling, the electric S models cannot fail to impress with their outstanding agility and traction: They can accelerate from a curve as dynamically as a sports car, their drive character is much more focused on the rear wheels and much more sporty in nature. If the ESC stabilization control is set to “Sport” and the Audi drive select dynamic handling system is set to maximum performance with “Dynamic” mode, the drive layout facilitates a high level of transverse dynamics and, on request, controlled drifts as well. The driving behavior is predictable at all times, and is characterized by an ultra-high level of safety and reliability.
The drive layout: three electric motors in the future mass production
The new Audi e-tron S models will be the first electric cars worldwide with three motors in mass production. Their drive layout is based on the concept with two different asynchronous motors (ASM); the e-tron product line was designed in modular form in line with this from the start.
The larger electric motor, which powers the rear axle in the Audi e-tron 55 models (current consumption combined in kWh/100 km*: 26.4–21.9 (WLTP); 23.1–20.6 (NEDC), combinedCO2 emissions in g/km: 0), has now been installed on the front axle in an adapted design and configured for 124 kW of power, or 150 kW in the boost.
The smaller electric motor now works in a modified form in the rear, together with a counterpart that is identical in design; together, they offer 196 kW of power, or 264 kW in the boost.
Innovation from the quattro pioneer: twin motor with electrical torque vectoring
The drive has been programmed for efficiency in everyday life; in normal driving mode, only the rear electric motors work. The front drive is unpowered but switches itself on – with the driver barely noticing – if the driver needs more power. It also switches on predictively if the grip declines. It does so when friction values are low and during rapid cornering.
The electric all-wheel drive is complemented by a further technical innovation in the form of electrical torque vectoring, which brings the advantages of the conventional sport differential into the electric era. Each one of the rear electric motors sends the drive forces directly to the wheel via a transmission; there is no longer a mechanical differential.
40 years following the launch of quattro technology, Audi is thus raising the principle of the four powered wheels to a completely new level of technology. The result: more agile driving and self-steering characteristics, and thus a higher cornering speed.
One further advantage is the traction. If, during acceleration, a rear wheel comes into contact with a road surface with a low friction value, i.e. if the road surface is covered in black ice or has a loose subsurface, the moment can be distributed precisely and quickly between the two motors. The full moment is gradually distributed to the wheel with powerful traction, while the wheel with low traction continues moving with almost no moment.
The two prototypes of the e-tron S models drive on 20-inch alloy wheels in the 5-V-spokeS design as standard. Different wheels up to 22 inches in size are available on request. To achieve an S-typical transverse dynamism, the tire widths in the sizes 20 inches, 21 inches and 22 inches have all been enlarged to 285 mm (11.2 in). Black brake calipers with a red S rhombus, with six pistons at the front in each case, grip the large brake discs (front diameter: 400 mm (15.7 in)).
A further standard feature is the sporty progressive steering – its ratio becomes more and more direct, the further the driver turns the steering wheel. The front and rear axles have been created as a five-link design. Harmonization of the elastokinematics and of the dampers has also been optimized for the S models. In order to even further reduce the rolling movements during cornering, the stabilizers on both axles have been enlarged.
Up to 150 kW: peak power, even during charging
When the driver is on the road, the electric S models can be charged with up to 150 kW of direct current power (HPC), such as in the European Ionity network. This means that charging from 5 to 80% only takes around half an hour. An important factor for this is the elaborate thermal management system with a standard heat pump, which cools and heats the battery, the interior and the electric motors with four circuits. In addition, the Audi models will also be able to charge with up to 11 kW of alternating current (AC).
The Audi e-tron Charging Service guarantees convenient access to more than 140,000 public charging points in 24 European countries on request – with nothing more than a charging card. In the first year, Audi covers the basic fee for the transit rate, which also offers access to high power charging columns.
Over the last five years Rolls-Royce has been pioneering world-first technology that will contribute to the UK’s next-generation Tempest programme.
In an aim to be more electric, more intelligent and to harness more power, Rolls-Royce recognised that any future fighter aircraft will have unprecedented levels of electrical power demand and thermal load; all needing to be managed within the context of a stealthy aircraft.
Before the launch of the Tempest programme, Rolls-Royce had already started to address the demands of the future. Back in 2014, the company took on the challenge of designing an electrical starter generator that was fully embedded in the core of a gas turbine engine, now known as the Embedded Electrical Starter Generator or E2SG demonstrator programme.
Conrad Banks, Chief Engineer for Future Programmes at Rolls-Royce said: “The electrical embedded starter-generator will save space and provide the large amount of electrical power required by future fighters. Existing aircraft engines generate power through a gearbox underneath the engine, which drives a generator. In addition to adding moving parts and complexity, the space required outside the engine for the gearbox and generator makes the airframe larger, which is undesirable in a stealthy platform.”
Phase two of this programme has now been adopted as part of Rolls-Royce’s contribution to the Tempest programme.
As part of this journey, the company has been continuously developing its capabilities in the aerospace market, from gas turbine technologies through to integrated power and propulsion systems. The goal being to provide not only the thrust that propels an aircraft through the sky, but also the electrical power required for all the systems on board as well as managing all the resulting thermal loads.
Rolls-Royce is adapting to the reality that all future vehicles, whether on land, in the air or at sea will have significantly increased levels of electrification to power sensors, communications systems weapons, actuation systems and accessories, as well as the usual array of avionics.
The launch of phase one of the E2SG programme saw significant investment in the development of an integrated electrical facility – a unique test house where gas turbine engines can be physically connected to a DC electrical network.
The launch of the second phase of the project in 2017 saw the inclusion of a second electrical generator connected to the other spool of the engine. It also included an energy storage system in the electrical network and the ability to intelligently manage the supply of power between all these systems.
The two-spool mounted electrical machines allows, by combination of operation as either a motor or a generator, the production of a series of functional effects on the engine, including the transfer of power electrically between the two spools.
As part of the E2SG programme, Rolls-Royce is investigating the feasibility of using dual spool generation to influence the operability, responsiveness and efficiency of the engine. Another key technology under development is the Power Manager intelligent control system, which uses algorithms to make real time intelligent decisions about how to supply the current aircraft electrical demand while optimising other factors including engine efficiency to reduce fuel burn or engine temperature to extend component life.
Throughout the Tempest programme, Rolls-Royce will be continuing to mature the electrical technologies demonstrated by the E2SG programme, with a third phase of testing likely to include a novel thermal management system being integrated with the overall system, as well as more electric engine accessories.
The company also intends to showcase a full-scale demonstrator of an advanced power and propulsion system. There will be new technologies in all parts of the gas turbine, including twin spool embedded generation to higher power levels, an advanced thermal management system, an energy storage system tailored to the expected duty cycle of the future fighter and an intelligent power management system which will be able to optimise the performance of both the gas turbine and the power and thermal management system.
Projekt E will run as a support series at selected World RX events next year, using technology developed by Austria firm STARD. The firm will exclusively supply powertrain kits to the new series in 2020.
The powertrain will include three motors, one on the front axle and two at the rear. Supplied as a control kit to be installed into existing steel-body, teams will be able to buy a complete kit for €194,000
This car, the first Projekt E, delivering up to 1100 Nm torque and 450 kw, is using a Ford Fiesta body shell, but it’s possible for owners to have the choice of several makes and models.
“We are delighted to be partnering with IMG on this innovative project which will change the technical landscape in motorsport and rallycross in particular,” Manfred Strohl, President of Stohl Group, said.
“The performance of the racecar will be impressive when you consider that in terms of torque, the power unit is capable of 0-90% in about 32 milliseconds. The motors rotate at up to 14,000rpm. Projekt E will add a whole new, innovative dimension to rallycross in 2020.”
Porsche Engineering have revealed they are working on a torque control system for a next generation four-motor all-wheel-drive electric SUV powertrain that provides maximum stability and safety in every situation—without additional sensors on board.
As Porsche explains, what makes a four-motor powertrain desirable isn't so much more power, but more control. Each motor can be controlled individually and immediately, rather than relying on analogue mechanical differentials and inefficient hydraulic braking systems that don't react as fast or as precisely. Solid state digital control is good for safety and stability in inclement weather and for improved performance and handling in dry weather. Basically, it's the most high performance, responsive, adjustable and energy efficient torque-vectoring system possible.
An electric all-wheel-drive vehicle with multiple motors has a fundamental advantage over gasoline or diesel engines: The front and rear axles, indeed all four wheels, have their own electric motors, enabling extremely variable distribution of the drive power. “It’s almost as if you had a separate gas pedal for each axle or wheel,” explains Ulf Hintze of Porsche Engineering.
The e-tron SUV concept unveiled by sister company Audi back in 2015 was originally intended to come with three electric motors. Unfortunately the dual motor rear eAxle didn't make it into the production version.
In a possibly related development, Porsche recently increased their ownership stake in Rimac to 15.5% following their 2018 investment for 10% of the business. Rimac developed a quad motor all-wheel-drive torque vector system for their Concept One hypercar.
Thanks to variably distributable drive power, electric vehicles with separately powered wheels can remain stable even in critical situations— as long as the torque control reliably detects deviations from the target state and reacts immediately. Porsche Engineering has developed and tested a solution for e-SUVs that does precisely that. Without additional sensors— entirely through software.
It’s a situation that every driver dreads: a snow-covered road, a surprisingly tight corner, and barely any time to brake. With a normal vehicle, a dangerous loss of control is an all-too-real possibility. The rear could swing out, causing the car to spin and land in the ditch. Yet in this test, everything goes differently: The driver turns and the SUV steers confidently into the corner—without even slowing down. A glance at the speedometer (80 km/h is the reading) removes all doubt that this is no ordinary vehicle. The SUV being tested in this wintry environment is an electrically powered all-wheel-drive vehicle with four motors— one for each wheel.
Until now, this drive technology was seen only in Mars rovers, but now it has reached the everyday world: Porsche Engineering recently developed a torque control system for electrically powered series SUVs. It was truly pioneering work. “We had to develop a lot of it from the ground up,” says Dr. Martin Rezac, Team Leader for Function Development at Porsche Engineering. There was also an additional challenge: The driving characteristics had to be optimized exclusively through software. The Porsche engineers could not install any additional sensors and had to use the existing control devices. The task, in short, was essentially driving stability by app.
Purely electronic control of torque
An electric all-wheel-drive vehicle with multiple motors has a fundamental advantage over gasoline or diesel engines: The front and rear axles, indeed all four wheels, have their own electric motors, enabling extremely variable distribution of the drive power. “It’s almost as if you had a separate gas pedal for each axle or wheel,” explains Ulf Hintze of Porsche Engineering. In a conventional all-wheel-drive vehicle, there is just one engine at work, whose power is distributed to the axles through a central differential. As a rule, the torque ratio is fixed: one-third up front and two-thirds in the back, for instance. The ratio can, in theory, be changed, but additional mechanical gadgetry is required for that (multi-plate friction clutch), and it works rather sluggishly. In an electric vehicle, by contrast, the torque is purely electronically controlled, which works considerably faster than mechanical clutches. Every millisecond, intelligent software distributes the forces in such a way that the vehicle always behaves neutrally.
And Porsche Engineering developed just such a torque control system for all-wheel drive SUVs. The software can be used for different constellations and motor configurations—for other electric vehicle types as well, of course. In general, development begins with the base distribution, i.e. software that controls how much power is transmitted to the front and rear axle, respectively. For straight-line driving and balanced weight scenario, for example, a 50/50 distribution would make sense. If the driver accelerates, the software switches to full rear-wheel drive—or all frontwheel drive around a sharp bend. “This makes the vehicle noticeably more stable, even for the passenger,” says function developer Rezac. As the optimization is achieved entirely electronically, theoretically it would even be possible to offer the driver various different configurations: one mode for sports car sprightliness, another for smooth cruising.
The second task of the control software is to adjust the torque to the wheel speed. The algorithms follow a simple objective: All wheels are supposed to spin at the same speed. That’s easy to accomplish on a dry freeway, but it is considerably trickier when driving on a snowy mountain pass. If the front wheels encounter an icy patch, for example, they could—without electronic intervention—start spinning. But the torque control system detects the suboptimal situation immediately and directs the torque to the wheels that are turning more slowly and still have grip within fractions of a second. There is something similar in the world of combustion engines—the speed-sensing limited-slip differential, also known by the brand name Visco Lok. In this component, gear wheels and hydraulics ensure that no wheel turns faster than the others. But mechanical solutions are slow. In an electric SUV, by contrast, software assumes the role of the differential— with much swifter reactions and naturally entirely without wear.
The third and most important function of the torque control system lies in its control of lateral dynamics, i.e. the ability to neutralize critical driving situations like the one mentioned at the outset: a slippery surface, a tight corner, and high speed. An uncontrolled vehicle would quickly understeer in this situation. In other words, the driver initiates the turn, but the vehicle slides in a straight line without slowing down. The control software in the e-SUV immediately puts an end to understeering. In a left-hand turn, it would brake the rear left wheel and accelerate the right one until a neutral driving situation was restored. The system takes similar measures when oversteer occurs (rear end swinging out). The driver, meanwhile, ideally notices nothing of these interventions, because the torque control system acts very subtly and quickly. “It feels like driving on rails—an SUV behaves with the agility of a sports car,” says Hintze, summarizing the effect.
The observer module keeps watch
The driving state observer (shortened to simply the “observer” by the engineers) is involved in all intervention decisions. This software module continuously monitors a variety of factors: how forcefully the steering wheel was turned, how much the driver is accelerating, and how much the vehicle is turning around its vertical axis. The data is provided by a yaw sensor. This actual status is compared with a dynamic model of the vehicle that represents the target state under normal conditions. If the observer detects deviations, for instance due to oversteer or understeer, the software intervenes. If the vehicle is not turning into a corner as quickly as would be expected from the current steering wheel position and speed, individual wheels are selectively braked until the direction is back on line.
The same effect may be achieved by a conventional electronic stability control (ESP) system as well—but in an electrically powered all-wheel-drive vehicle, the safety system can do more: While a conventional ESP system only brakes, in an electric vehicle the individual wheels can be accelerated as well. This “pulls” the vehicle back onto the right track without losing speed. The intervention is also less jerky than in a hydraulic ESP system; the typical juddering familiar from anti-lock brake systems is omitted.
“The development of the vehicle observer was the biggest challenge,” says Rezac. The fact that so much development work was required here goes back to a fundamental problem: A car knows relatively little about its own state. It doesn’t know its own speed; it can only derive it from the speed of the wheels, which is difficult on ice and snow particularly. The observer therefore has to use additional information about the longitudinal and lateral acceleration in order to estimate the speed. The information regarding weight distribution is equally vague. While the suspension does capture the load on the individual wheels, even this information provides mere clues rather than certainty. If the shock absorbers report increased weight on the rear axle, for example, it could be due to the vehicle being parked on a slope—or simply being heavily loaded.
The data situation is decidedly meager. And because the client insisted that no additional sensors could be added, the SUV project called on the creativity of the software developers. “The observer has to estimate the vehicle’s important parameters,” explains Rezac. Some unusual data sources are brought to bear: The torque control system communicates with a sensor that detects the inclination of the car, for example, which is usually used for the automatic adjustment of the headlights.
The entire software package not only had to be developed, but calibrated in real test drives. And all that in a very short period of time: There were just two winters available in which the fine-tuning could be tested on a frozen river. It emerged, among other things, that the great advantage of electric motors—their rapid reaction times—sometimes resulted in undesired side effects. “The electric motors respond so quickly that vibrations can occur,” reports Hintze, who conducted the test drives with his team. In a few situations the software transfered the torque between the axles at increasingly fast intervals, which resulted in an audible revving of the motors. Thanks to close collaboration between the calibration team and the development team around Martin Rezac, however, they quickly managed to put a stop to this build-up through a modification of the software.
This detailed work is exactly where the challenge lies in such projects. As the software is to be used in a series vehicle, it has to be tested for every imaginable situation, no matter how improbable it might seem. If the sensor reports faulty data, for example, the torque control has to decide if it is still allowed to function even without the data source or should be switched off. Another hurdle was posed by the limits of the electric drive technology. It may be the case, for example, that individual e-motors cannot transmit the available battery power. The function developers had to take such limitations into account. “The control range collapses in this case,” says Hintze. Instead of 100 percent torque on one axle, perhaps only 60 percent might be available. And the torque control has to take that into account as well. But all involved are convinced: The pioneering work was well worth the effort, as electric vehicles with up to four motors will soon shed their exotic reputation. And many drivers will be grateful that they can drive through the snow as if on rails.