Porsche Battery Testing in Detail

Discussion in 'In the News' started by xcel, Mar 13, 2023.

  1. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    [​IMG] One OEMs process to improve the future of the automobile.

    Porsche Engineering – CleanMPG – February 2, 2023

    Porsche High-voltage Battery Testing

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    Porsche Engineering uses state-of-the-art testing procedures for the development of electric drives, which include both real-life and lab testing conducted in a virtual environment. Their use can significantly shorten the development time and reduce the number of test vehicles needed.

    To continue to increase efficiency in the development of new components and systems for electric drives, Porsche Engineering uses test methods specifically adapted to the requirements of high-voltage technology. As an example, high-voltage batteries are tested on vehicle and component test benches at the Bietigheim-Bissingen and Nardò locations, while hardware-in-the-loop simulation environments are available for testing the software for pulse inverters (PIs). This involves testing the real hardware in a virtual vehicle system.

    The PI plays a key role in electric vehicles because it converts the DC voltage from the battery into the multiphase AC voltage and the associated rotating field for the electric drive motor. When energy recovery is active in overrun mode, the PI works in the opposite direction and converts the motor’s AC voltage into a DC voltage that is used to charge the battery. “Precise PI control for the various performance and comfort requirements in different driving situations requires highly complex control algorithms and safety functions that have to be tested before the drive is put into operation,” explains Rafael Banzhaf, Technical Project Leader at Porsche Engineering. “This involves, for example, ensuring the drive system enters a safe state in exceptional situations such as a crash with airbag deployment.” Prior to development of the PI-HiL system, the tests had to be carried out in the vehicle or on a real test bench, with there always being a risk that something could be damaged in the event of software errors in the control unit.

    Porsche Engineering has therefore developed a test bench concept for testing the PI software, in which the real PI ECU is integrated as hardware-in-the-loop (HiL).
    When the HiL tests are conducted, the PI control board does not activate real hardware, but rather a simulation of the PI power unit. This, in turn, is linked to simulations of the high-voltage battery, the electric drive motor, the bus system and the rest of the vehicle to factor in the impact on the PI control caused by vehicle systems such as airbags or the brake control system, and the driver, on the PI control. Conversely, the simulation delivers virtual sensor data such as phase currents and temperatures back to the PI control unit, thereby closing the control loop. Due to the high demands on the real-time capability, the simulations for the battery and the rest of the vehicle are carried out on a real-time computer (RTPC), while even faster FPGAs (field programmable gate arrays), which allow simulation times within the nanosecond range, are used for the power electronics and the electric motor.

    The test scopes possible on the HiL test bench primarily include functional tests according to specification requirements, but also flash tests of new software, validation tests as a safety step before further analyses are conducted in the vehicle, and tests of the interfaces, diagnostic functions, execution times and of cybersecurity and virtual endurance testing.

    The development of the PI-HiL test bench is the result of close cooperation between different Porsche Engineering locations. Six PI-HiL systems are currently in use, and there are plans for this capacity to increase. A special feature of our approach is full remote access to control the test benches allowing application engineers running tests in Sweden or the US to control the simulations from their location. Because all test benches are connected to each other, and to the archiving system, the data can be made available on the servers to all participants with immediate effect. The Shanghai location in particular offers great opportunities for high testing efficiency in this regard, as it allows round-the-clock test implementation and evaluation in the international network of teams due to the time difference between Europe and China.

    Another advantage of Porsche Engineering’s PI-HiL is its high level of automation. The requirements documentation for the PI control system supplied by customers is automatically imported. The test specifications are then automatically derived from the customer specifications and used to generate a variety of test cases and trials that can be implemented. Instead of spending several weeks creating the more than 1,000 test cases for a PI test series manually, only a few hours are necessary.

    In the future, there are also plans to employ artificial intelligence (AI) methods: Using natural language processing (NLP), AI is expected to correctly interpret requirements specifications delivered as a simple text document and convert them into machine-readable code. This is used as a basis to automatically generate the test sequences. Today, this activity is performed by experts who must have comprehensive overall system expertise.

    Even though virtual test procedures are covering more and more areas, they still cannot completely replace real-life trials of high-voltage batteries. For this reason, Porsche Engineering maintains an extensive infrastructure in Bietigheim-Bissingen, with vehicle as well as system and cell test benches. The former is used to analyze batteries more precisely at component level, while the latter even allow conclusions to be drawn at cell chemistry level. By means of a flexible adaptation of driving profiles and load spectrums, the driving situations relevant for the test can be simulated. Depending on the objective of the test, the battery’s charge and discharge behavior, its capacity, internal resistances, and temperature behavior are captured and recorded.

    Batteries can be tested in their installed state on the vehicle test benches, for example for measurements of battery capacity and currents in the WLTP driving cycle. This is particularly important for endurance test vehicles, where testing the battery every 20,000 kms is part of the mandatory scope of testing.
    The integrated workshop plays a key role in all battery tests in Bietigheim-Bissingen.

    Over the past two years, Porsche Engineering has set up a complete test facility at the NTC for ‘misuse tests’ on high-voltage batteries in accordance with GB/T and ECE. This involves examining how the battery responds in the event of a ‘thermal runaway’ of a battery cell, which might, for example, be caused by overheating. At the NTC, these misuse tests are conducted in a building.

    The engineering team in Nardò joined forces with the safety experts and firefighters at the NTC to develop a sophisticated safety concept. After delivery, the batteries are prepared for examination before undergoing testing. Fire extinguishing systems that are triggered automatically ensure a high level of safety. The battery status is assessed after the test. If critical, the battery must rest for 24 hours in a locked box equipped with fire detectors until the NTC experts can begin analyzing the damage and making their findings. After the examination, the battery is stored in a shelter that is also equipped with a fire protection system to await disposal.

    This is the basis on which the NTC offers a comprehensive service that not only includes overheating and spontaneous combustion tests of the cells, but also misuse tests of the battery specifically adapted to customer requirements, as well as analyses of the fire resistance of the battery housing. The scope of services ranges from storage, preparation and test execution to post-mortem analysis and detailed reporting.

    With its combination of real and virtual processes, Porsche Engineering can offer customized testing services. In either case, customers benefit from expert knowledge, methods, and services at the cutting edge of technology.

    Porsche Engineering uses test methods specifically adapted to the requirements of high-voltage technology. These include conventional test benches, but also HiL test benches for virtual testing of PI controllers. Artificial intelligence will help to save development time and costs there in the future.
     
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  2. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Porsche “One for All” BEV Platform

    Intelligent platform strategies reduce the time and costs involved in developing electric vehicles. Porsche Engineering has extensive expertise in platform development and supports its customers from the initial concept idea all the way to the production-maturity vehicle. The result is platforms that are flexible and positioned for the future.

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    One single platform for a multitude of vehicle models: This approach has been followed for years now for combustion-engine vehicles, helping to develop many different models and derivatives and to bring vehicles to series production at justifiable expenditure of time and money. In production, the approach results in economies of scale: Fewer components in high volumes reduce component costs and ensure high product quality. Volkswagen was one of the pioneers of a consistent platform strategy with its Modular Transverse Matrix (MQB). Since 2012, it has formed a shared foundation for many models with gasoline or diesel engines. More than 32 million vehicles based on this platform have been produced across the Group. Volkswagen was quick to apply the principle of the MQB to electric vehicles with its Modular Electric Drive Matrix (MEB), improving development and production efficiency in this field, too.

    The new Premium Platform Electric (PPE), developed in tandem by Audi and Porsche, adds to the electric vehicle platform concept’s scope of application. For Porsche, this creates new opportunities to launch high-volume models with high technical standards at profit, thus taking the electrification of its portfolio another step further. The Stuttgart sports car manufacturer intends for more than 80 percent of its new deliveries to be fully electric by 2030. The PPE makes it possible to capitalize on the benefits of an all-electric platform in a variety of ways. One example, beyond package and space, is integrating the lithium-ion battery into the underbody. In fleshing out the design amid the conflicting requirements of range, performance and sustainability, Porsche remained true to its philosophy by focusing on travel time. At the same time, the architecture offers lots of leeway when it comes to the wheelbase, track width, and ground clearance, allowing for a variety of performance levels for models with either RWD or AWD in different segments.

    This flexibility allows Porsche models to retain their strong, independent character. To start off with, system output will cap at 450 kW, with maximum torque at more than 1,000 Nm. The first Porsche based on the PPE will be the all-electric Macan. With its 800-volt architecture, powerful latest-generation electric motors, and advanced battery and charge management, this model offers the level of electric vehicle performance you’d expect of Porsche. The successor to the acclaimed compact SUV has its sights set on becoming the sportiest model in its segment. Besides reproducible best-in-class driving performances, development goals include a range suitable for long-distance travel and high-power fast charging.

    The benefits a platform for electric vehicles might offer are obvious - designing one, however, presents the engineers with a highly complex challenge. A myriad of aspects needs to be considered, while some of the development goals stand in outright opposition to one another. This is generally true for any kind of vehicle but applies especially to those with electric drives. After all, the individual drive components offer greater leeway when it comes to design than you get with a combustion engine—for example, in setting up the platform for broad scalability or making it flexible enough to allow the modular drive system to serve as a basis for entirely different vehicles. The platform makes it possible to implement rear-wheel, all-wheel, or front-wheel drive simply by choosing the position of the electric motor or even by adding another one— something a combustion engine does not allow.

    Over the years, Porsche Engineering has acquired extensive overall system expertise from projects in this field, enabling the developers to optimally coordinate platform concepts. Today, the company’s service portfolio covers all steps along the entire process chain for platform engineering—from the initial project idea to detailed platform definition. In most cases, the foundations are laid by an initial feasibility study, which examines whether a project is technically viable within the specified framework parameters. This takes the customer’s subjective preferences and converts them into objective, physically testable and measurable properties.

    Computer-Aided Engineering

    The next step is to work out the concept dimensions. The development team determines all of the vehicles and its components’ relevant dimensions.
    Precise specifications are created using simulations, for example for the shape of the body-in-white, for the battery, the seats, the powertrain, and the body support structure. Computer-aided engineering culminates in a virtual model, referred to as a digital mock-up (DMU), which includes definitions of the main components. At this point, the project version passes to the vehicle manufacturer to develop it further into a production-mature vehicle.

    Porsche Engineering continues to support its customers in development, simulation, and testing of components, systems, and the complete vehicle.
    Showcasing the brand to its best advantage

    It is easy to see how the battery plays a key role. It’s the electric vehicle’s energy store, of course, but for reasons of installation space and weight, it should also act as an integral part of the crash structure and underbody reinforcement and be a component of the cooling system.

    This includes, for example, the design of the driver’s seat and the seating position, which must be ergonomic, sporty yet comfortable, and suitable for a broad customer group worldwide. The overriding principle of platform development is that you should not start on a specific vehicle project until the platform has been defined. After all, it is only then that the individual development goals can be balanced in the best possible way and components such as the battery, front and rear axles, or even the size of the wheels, be designed optimally. Any changes after the fact are very time-consuming and costly, and sometimes just downright impossible. Many—often the smaller—automobile manufacturers don’t consider how a platform strategy might benefit them when they set out to develop a vehicle project.

    One example of a customer that sought cooperation with Porsche Engineering at an early stage, thereby saving considerable development expenses, is a customer that was planning to launch an electric vehicle model series.

    For the different wheelbases of the various vehicle models, for example, the development team defined the increments so that, for each wheelbase increase, the next-in-line battery module would plug the gap in the vehicle underbody. This way, the customer can cover all intended vehicle segments—from compact cars to sedans to SUVs— with one single platform.

    High Flexibility Mandated

    Another aspect when designing a modern platform is its future viability. Even if, for example, the first plans only include rear-wheel drive vehicles, other options should also be accommodated at this point. This way, the platform will be able to handle vehicle models that haven’t even been brought to table yet, for example front-wheel or all-wheel drive variants. A high degree of flexibility is just as important for the design, as there needs to be room to integrate future technologies.

    After all, electromobility and its components, like batteries and electric motors, as well as the electrical systems and electronics architecture, are progressing in leaps and bounds.

    Porsche Summary

    Platform concepts have aided in the development of different models and derivatives and the launch of production vehicles with reasonable time and cost for years now. For electric vehicles they offer many benefits. Designing one, however, presents a highly complex challenge: A myriad of aspects need to be considered, while some of the development goals stand in outright opposition to one another. Porsche Engineering supports its customers from the initial concept idea all the way to the production-mature vehicle.
     
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