Driving the Future of Automotive ElectronicsKarthi Gopalan – Infineon Technologies
Imagine a world where “Save the Air Day” is a historical lesson. Smog tests are outmoded, cities are no longer choking under a grey cloud and the public rarely worries about refueling, or, most likely, recharging, their vehicles. This ideal world and its realizations are being crafted by engineers working hard to maximize fuel efficiency, to create waste-less electric vehicles and scalable solutions.
“Throughout the world vehicle emission standards are tightening and in some cases accelerating. China is implementing the “National VI” vehicle emissions limits now, in 2017, three years ahead of the original plan to implement it in 2020” -Dan Moore, Infineon.
This ideal world and its realizations are being crafted by engineers working hard to maximize fuel efficiency, to create waste-less electric vehicles and scalable solutions.
This push toward “greener” automobiles also means a multitude of challenges for the engineers. For example, introducing more control over more systems and an increase in data gathering ultimately means running into space issues for all these new control systems, not to mention the associated costs from adding more components. Also, the demand for efficiency is steadily increasing, meaning a greater interest in avoiding wasted electrical power and fuel. A more looming challenge is the expectation for microcontrollers to perform well, running emission test algorithms that grow in complexity and executing AUTOSAR standard libraries at the same time. Fortunately for engineers faced with such challenges, companies like Infineon supply the most comprehensive automotive grade, electronic components necessary to implement each section of a Pollution Control System, those being – sensing, processing, actuating and communicating.
Tackling Size and Weight Restrictions with a Rising Count of Electrical Components
Keeping a vehicle sleek while adding to the list of different systems diminishes physical room in which new components are to be housed. Also, the addition of new parts must not impact the weight of the vehicle too heavily. Therefore, the components themselves must be kept as small and as light as possible to maintain similar performance. Two groups of inhabitants taking up room are high current electromechanical relays and fuses. Bulky and prone to sparking, relays do not allow the system to diagnose problems when they trigger. Likewise, fuses not only lack feedback, they must be replaced when blown and run the risk of damaging their sockets permanently.
However, suitable replacements for these electromechanical devices must provide similar benefits. Little power is wasted as heat and the devices can bear spikes in current and ringing during hard switching or high-frequency applications with soft switching. In modern vehicles, an additional expectation is handling high voltage, and the rising component count means replacements must not increase the usage of copper, a great concern since the price per ounce is on the rise.
One direction solutions can take is toward solid state technology. For example, MOSFETs, despite being very small, can handle high currents. As an added bonus, due to its technology, MOSFETs do not spark and are robust against current spikes and ringing. By incorporating sensing technology on the same die, switches now feed back vital information to give accurate hints to the root of failures. Similarly, solid state relays are fully integrated and are switchable, introducing a new concept of resettable fuses. Thus, the reduced size means a significant cut in copper usage. Removing the requirement of part replacement and the need to make the board accessible for maintenance, space is freed up for other systems.
Infineon offers this level of ruggedness in footprints as small as 10 by 12 mm. The PROFET™ family affords accurate current sense. Additionally, the CoolMOS™ family handles over half a kilovolt. Both of these families ensure less power lost and introduce the concept of smart, resettable fuses.
Power Regulation and Conversion Efficiency with a Noisy Battery
Given that the power system in a vehicle can be extremely noisy and suffer from various states like cranking, designing reliable and energy efficient voltage regulators can be challenging.
At the beginning of a vehicle’s power system, voltage from the battery must be regulated to provide controllers and sensors with a clean, DC output. For power intensive systems like drive trains, regulation is split into two stages. Pre-regulators are connected directly to the vehicle battery, generating a stable voltage line. Then post-regulators convert the output of the pre-regulator to final, desired voltage levels. Despite having two conversion stages, a short on the load side or another problem could potentially take down the whole system. Therefore, voltage trackers serve as auxiliary supplies to keep priority systems powered even while the main supply is overloaded, such as during cranking.
Next, low power systems like controllers and sensors use a dedicated supply called the system regulator, also wired directly to the battery. In charge of more sensitive devices, system regulators provide a safe electrical path in cases of faults. They also monitor all voltages at its inputs and outputs, so no voltage dip goes unnoticed. However, to keep the system safe, a redundancy system is needed to verify all voltage measurements, and the regulator has to gracefully recover from program freezes.
For pre- and post-regulators, the TLF502x series from Infineon is a group of automotive grade buck controllers. The TLF425x series boasts overvoltage, overcurrent, and more safety features, making it excellent as a voltage tracker.
Designed to enable implementation of ISO26262 systems, regulators like the TLF35584 boast multiple voltage references for a redundant voltage monitoring system and ensure a safe path in the event of a fault. To prevent a system-wide failure due to a fault in program execution, these system regulators use both functional and window watchdogs.
Control and Performance with New Emission Standards
“Today’s cars must be greener, safer and connected. To reduce the environmental footprint, hybridization and pure electric vehicles are the way forward. Advanced Driver Assistance Systems and Self Driving cars should increase car safety and more generally road safety, ultimately reducing the number of fatalities. Internet and audio/video feeds on board make the commute experience more pleasant and help to improve the driver and passenger’s mood in the face of increased traffic delays”. -Hector Moreno, Infineon Technologies.
Some of the key challenges automotive engineers currently face are the growing complexity of emission testing and an increase in the number of control systems. To meet both challenges, a digital solution appears to be the best, using software to execute emission tests and to precisely control automotive systems to maximize mile per gallon efficiency. Therefore, microcontrollers can be used.
Such microcontrollers would fulfill certain expectations. For example, emission testing algorithms, coupled with those from the AUTOSAR (AUTomotive Open System ARchitecture) standard libraries, demand high performance to keep up and to run the entire vehicle smoothly. However, there are also many different systems of varying performance requirements. Additionally, to ensure no vehicle is faulty, the solution must prove to be safe, and the manufacturing process of the microcontrollers must also be robust.
Some of the key challenges automotive engineers currently face are the growing complexity of emission testing and an increase in the number of control systems.
A solution that is both scalable and multipurpose would shorten time-to-market by allowing engineers to use the same platform. Below are two examples of what a multipurpose microcontroller would be applied to.
To meet performance demands, a microcontroller could take advantage of multiple cores, using parallel processing to speed up calculations. Having multiple cores also affords lockstep architecture, running the same command more than once in parallel. This creates a redundancy system to better guarantee the reliability of the system. And, to protect the system from tampering, the microcontroller might have a hardware-based security solution.
As a scalable, multipurpose solution, the AURIX™ family hosts a selection of microcontrollers to meet these requirements. Built to be used in a variety of automotive applications, including entertainment systems, these microcontrollers use TriCore™ technology, relieving developers of super-optimizing programs just to make the system functional. Additionally, the family hosts Hardware Security Modules (HSM) shielded from peripherals by a physical firewall in the architecture.
Infineon’s Zero Defect program ensures every single sold chip is functional, giving AURIX™ microcontrollers high reliability.
The drive towards a more environmentally friendly future for automobiles reveals new challenges for engineers, from innovating solid state technology to reducing size, weight, and copper usage, to reliably powering the vehicle with a series of regulators. Developers also face an increasing number of control systems and complicated emission testing, forcing new firmware to be as fast as possible. Infineon’s solutions including MOSFETs, regulators, and microcontrollers help shorten time-to-market: reducing design size, simplifying systems, and integrating safety features.