Testing under extreme conditions
Right up in the far north of Europe, winter offers the optimal prerequisites for car manufacturers to test vehicles under extreme conditions. For this reason, the brand with the four rings is also attracted to the Swedish part of Lapland each year during this season. Short summers and long, harsh winters with icy temperatures define the region. The public streets are almost empty; only rarely does another vehicle appear on the other side of the road, disappearing quickly again in the rear-view mirror. In the winter months, the snow blankets everything in cotton wool and naturally dulls the background noise. Endless forests are criss-crossed by lakes, which, depending on the weather, can already carry a remarkable layer of ice in the autumn. If this is thick and compact enough, the time for test drives under extreme conditions begins. Because even if this area is picture-perfect in good weather, it can be quite uncomfortable in Europe’s far north when strong winds drive the snow before them, or the night-time temperatures sink below –30° Celsius. But it is precisely these extremes that make Lapland such a thrilling test site. Pushing the limits to ensure the best possible quality.
More than 20 prototypes of the first purely electric series model from Audi have found their way to Lapland this winter. It is the third and final winter season. An exciting journey for the developers who, against a natural backdrop, test the various requirements in extreme cold on the tracks of the vast terrain one last time before the vehicle’s market launch. The development of the hardware has been completed. Now it’s all about the finer details. The settings in the software. Despite this – or maybe because of it – there is a mixture of euphoria and tension in the air. The demands on the quality of the vehicle are high. In a compact window of time, every day is used efficiently.
During this phase, the isolation of being in the middle of nowhere in Sweden brings with it a number of advantages: the technology of a modern vehicle is now highly complex, and all components must work together in unison. In order to achieve this goal, exchange and cooperation between the relevant departments is important. Lapland offers the optimal conditions for an efficient cooperation – starting with the test drive and ending with analysis of successive drives as a countercheck.
Dynamism and sporty performance
Various test tracks are available to the developers for testing purposes: both on the ice and on adjacent routes on land. There, all scenarios relating to the behaviour and handling of the vehicle can be played out – whether when pulling off, braking or during the journey. Occasionally the developers steer the prototypes across the test tracks at high speed. Drifts with swirling snow included. Never a product of chance, but planned precision work. ‘Sometimes during the drives, we purposefully push right to the limit so as to play out all eventualities,’ explains Ferdinand Hartinger, technical developer for the chassis. ‘This also means that thresholds are reached that exceed driving behaviour in normal road traffic.’ While the open area of circle testing on the lake would permit wide evasive manoeuvres across the specified route in the event of an emergency, on land, you need to keep to the predetermined lane as precisely as possible, which, for security reasons, is bordered by deep walls of snow.
To see and experience that the systems work even under challenging conditions is a special moment for the developers. ‘It must be said that the testing in Lapland is weirdly fun. This is exactly why we develop the systems – to facilitate a safe driving experience even under challenging conditions, and thus also promote driving pleasure,’ states Moritz Reiff, project coordinator drive functions for the quattro with e-tron technology.
‘We can precisely precondition the vehicles in cold chambers, which makes the on-site work very efficient. Thanks to the different routes, the range of options can be tested in a targeted way.’ The complexity of the technology generates a great deal of data. It is therefore essential to have a passenger: a laptop with the appropriate analytical software, which can be connected to the corresponding control unit in the vehicle. All data generated during the test can therefore be saved and subsequently analysed. In addition, and at the same time, the data is provided on a server in Ingolstadt to all the developers involved with this vehicle model.
‘As soon as we notice that the vehicle is not driving harmoniously in given situations, we reset that situation. If all measurements for the respective driving manoeuvres are logged, these will be analysed and discussed in our department with the appropriate experts. Due to the complexity of the control devices, of course, the project is always overseen by several experts. If the problem is detected, we can quickly program new software versions and install them in the vehicle. We then run through the drive again and the package is optimally defined.’
An important aspect in the vehicle’s handling, which, among other things, is placed under the microscope in Lapland, is the quattro technology, which is raised to a new level with the addition of the purely electric drive: for the prototypes of the first fully electric series vehicle, both axles can be regulated completely freely by two electric engines via software for the first time. ‘This calculates how much power is required on each axle and informs the engine in every driving situation how much power it should deliver. The software also evaluates over 400 input signals 200 times a second from the steering, the accelerator pedal, the assistance systems and other sensors,’ continues Reiff. Since there is no longer a need to move a clutch – just electrons – this all proceeds much faster than with an all-wheel drive for a vehicle without electric drive.
‘The electric engines have a much higher actuator speed compared to combustion engines. In other words, the time wherein the electric engine can generate torque is reached almost without any delay. For the field of chassis development, this means more degrees of freedom. Torque can be distributed more quickly and system interventions performed. We have developed new control system functions in the vehicle so that the performance of the drives is optimally used and can, for example, therefore be powerfully driven off from stationary on ice without much slipping. The tyres gain grip faster and regulate precisely along the slip threshold.’
Cold test for the lithium-ion battery technology
To improve vehicle performance, analysis of another central component is on the agenda in Lapland: the battery is also carefully tested. ‘The cells’ physics indicates that falling temperatures reduce the performance of batteries. For us, it is important to find out how the battery responds to cold and at which temperatures the customer could experience restrictions,’ says Andreas Birk from the Audi centre of expertise for high-voltage battery technology, which, among other things, deals with the development of software, packaging, cooling, protection and – in cooperation with body development – integration into the vehicle. The low temperatures in wintry Lapland are very well suited to this. In addition, cold chambers are available on the site to maintain constant temperatures or reproduce specific ones. ‘During the tests, the state of charge (SOC) and the defined start temperature of the battery vary. We use the cold chambers to get the vehicle exactly to the right temperature in advance,’ adds Birk. ‘Within two weeks, we test the whole repertoire that the customer could also experience later in the field using cold drives. This includes, for example, imaginary situations, such as: the customer takes the first purely electrically driven series model on a skiing holiday to a mountain hut in the evening. The temperatures are very low. He/she drives up with a low SOC. The next day, he/she can leave again and recover energy by recuperation. What does the battery do overnight? Will the car start again despite the icy temperatures? We play out all of these use cases together with the other specialist areas.’
Short charging time
The first fully electric series model from Audi allows fast charging with a capacity of up to 150 kilowatts and is therefore suitable for long distances again after half an hour of charging time. In order to be able to test charging with 150 kilowatts in extreme cold, there is an appropriate charging station on the site. ‘We are very pleased with the results of the tests here on-site. Even at very low temperatures, battery reliability can be guaranteed,’ concludes Andreas Birk.
Challenge accepted and mastered! The prototypes of the first purely electric series model from Audi have demonstrated their reliability and strong performance during the final test in Lapland. Even in the icy cold and in preproduction status, this vehicle already ensures electrifying moments.
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