Which technologies are in the driving seat for the car of the future?



The automotive industry is at an exciting point in its history, as technology is enabling new driving experiences and levels of convenience.

Two major trends are forming an over-arching effect on vehicle design. One is the electrification of vehicles, replacing the internal combustion engine (ICE) with an electric motor. The second is the connected vehicle, where wireless networks make up the vehicle’s communications, safety, comfort, and security functions.

The first technology, electrification of vehicles, is wide ranging. This term refers to propelling a vehicle, using an electric motor rather than a conventional ICE. A desire to reduce pollution and fossil fuels’ decreasing availability are driving industry’s electric vehicle production. Some electric vehicles (EVs) use battery packs to store energy, whereas fuel cell EVs use hydrogen and a fuel cell for propulsion. Hybrid electric vehicles (HEVs) use petroleum gas as fuel and an electric system for energy efficiency, while plug-in HEVs (PHEVs) store energy from the power grid and use petroleum gas and electricity to propel the vehicle.

Although accounting for less than two percent of light vehicles on the roads around the world today, EV sales are experiencing considerable growth rates. There are still design areas that need to be addressed, however, says Sang Chon, C2000 Automotive Marketing Manager at Texas Instruments.

Electrification
Vehicle manufacturers must overcome three main challenges to accelerate the momentum behind electrification in cars. The first is to increase the driving range of a vehicle’s battery. Some areas of focus are to increase the efficiency of driving the traction motor as well as even the efficiency of the heating, ventilation, air conditioning (HVAC) compressor. “The compressor for an HVAC system is very different from that of an ICE or engine-based car today,” says Chon. “The HVAC system is not running off a belt, connected to an engine, it is connected directly to a 400V battery. EV HVAC systems can drain battery life.” he adds. The compressor, like a motor, will drain the battery life quickly, limiting the range of the vehicle.

Saving space in the vehicle is another focus for EV manufacturers. There are many bulky, high-voltage cables in vehicles. They are used to connect the battery to the on-board charger and the traction inverter. They take up a lot of room, and positioning them can be like an intricate game of Tetris, in a bid to maximize the space available. Therefore in order to save space within the vehicle, (original equipment manufacturers) OEMs are looking to reduce the size of the on-board charger, high voltage DCDC converter, and traction inverter modules (or even combine these modules into one.) OEMs are also looking to reduce the size of the actual EV motor itself.

Finally, the industry and EV users want faster charging. Some OEMs are trying to charge the battery up to 80% in 20 minutes. The drawback is that this means trying to get more throughput to the battery via an on-board charger or EV charging station. “A lot of on-board chargers today might be in production at 3.3kW or 6.6kW, but some of the OEMs are trying to get up to 22kW for the on-board charger. That means more power conversion throughput to charge the battery faster,” explains Chon.

Figure 1: Charging EVs from stations requires up to 350kW to reduce battery charge time.

Power conversion from the electric power grid to the EV battery can be done one of two ways. It can be directly into a converter in the vehicle using an on-board charger system that converts power from AC to DC in the car. Alternatively, charging stations perform the power conversion stage outside of the car. For user convenience, EV charging stations entering the market today can charge very fast, using up to 350kW to reduce the battery charge time.

Saving Space and Weight
One solution to space and weight concerns can be to increase power density of the power conversion modules in the EV vehicle, proposes Chon. This would make modules smaller and more powerful. Texas Instruments’ C2000™ real-time microcontrollers (MCUs) are designed specifically for power electronics and power conversion (Figure 2) and address all three of these electrification challenges.

The architecture of the C2000™ real-time MCU is designed to efficiently, and with very high actuation, drive Silicon Carbide (SiC) MOSFETs in EV power conversion modules to enable satisfying system requirements while increasing power density. For example when controlling SiC MOSFETs, precise actuation is needed to avoid a sudden current rush that can cause damage to the system. C2000 Real-time MCUs have integrated mechanisms such as high resolution dead-band control to precisely drive the pulse width modulation (PWM) channels to drive the high frequency SiC (or GaN) drivers.

“For over 20 years TI has evolved the C2000 PWM modules to be flexible, high performance and very efficient for power conversion technology,” says Chon. The result is “to provide an MCU that makes it easier for customers to design for any power electronics problem.”

A DC/DC converter converts power from the high voltage battery to the 12V battery, and to save space some vehicle OEMs are looking to combine the on-board charger with the DC/DC into one single module. Another option to save space is to combine the DC/DC converter with the traction inverter module that drives the motor itself.

Figure 2: The C2000 real-time MCU is specifically designed for power conversion.

Chon also explains another way how the C2000 real-time control MCU can be used to save space in EVs by reducing the EV motor size. In order to keep the same power level but to reduce the size of the motor requires the motor to spin at a very high RPM. C2000’s ADCs (analog to digital converters) quickly sense current and voltage levels, then C2000 MCU’s integrated DSP core can triple current loop bandwidth via special motor control algorithms, and finally flexible PWMs perform the actuation to enable the motor speed to be increased significantly, he says.

Again sensing current and voltage with on-chip resources, performing mathematical calculations to correctly set current and voltage levels and driving SiC (or GaN) drivers are all critical to be operated in real-time to avoid shoot-through, which puts the whole system at risk, he adds.

Battery Life
C2000 MCUs are also designed to increase efficiency to extend battery life. Improving the traction inverter and HVAC compressor efficiencies requires what Chon describes as very advanced motor control algorithms that run on the C2000 MCU.

Examples of these advanced motor control algorithms that are provided by TI are Fast Current Loop, which can help increase motor speed and thus reduce the size of an EV motor while improving the overall efficiency for a traction inverter, and Instaspin, which allows an EV HVAC compressor to run at a lower speeds (< 500rpm) at full torque to run the HVAC system with a wider dynamic range thus saving battery life.

Similarly, efficient power conversion contributes to extending battery life. A DC/DC converter that is converting 400V to a 12V system needs to operate at above 98% efficiency. The C2000 MCU can help control a wide variety of advanced power topologies required to implement a DC/DC converter, using integrated PWMs, A/D sensing, and compensation control with the C28x DSP core.

Charging Times
China and Europe allows for three-phase, rather than single-phase, AC/DC power conversion for EV charging. C2000 MCU can support advanced topologies such as a Vienna rectifier and Totem Pole PFC to control three-phase power conversion (all with SiC MOSFETs).

C2000 MCU’s C28x DSP core has an extended instruction set that helps perform sine and cosine math calculations. Typically, trigonmetric math calculations require a lot of CPU bandwidth, but the trigonometric math unit (TMU) instruction set can complete these instructions in two to three cycles. This significantly helps in a digital power implementation for advanced topologies such as a Vienna Rectifer or Totem Pole PFC that ultimately benefits an EV vehicle by saving energy and increasing overall system performance, points out Chon.

Since these topologies used in three-phase conversion demand a lot of processing performance from the DSP core, C2000 MCUs also offer an integrated co-processor, called the Control Law Accelerator (CLA) that can offload the main C28x DSP. It can be considered a true real-time system co-processor to the main C28x DSP core in that the CLA connects directly to the ADCs and PWMs on-chip, says Chon.

Autonomous Vehicles
As autonomous driving gains momentum, OEMs will also have to consider how best to integrate the electronics needed for processing data from an increasing number of radar systems around the vehicle, together with Cloud communication systems. Autonomous driving modules will also consume battery life, warns Chon, adding to the pressure to solve efficiency and range issues.

The Connected Car
Another significant trend in the automotive industry is the use of Bluetooth® low energy to make cars more intelligent. Bluetooth low energy is used in vehicles to share data without draining energy resources. As the amount of electronics in a vehicle increases, there is a pressing need to ensure power consumption is kept in check.

TI’s SimpleLink™ Bluetooth Low Energy CC2640 R2F-Q1 wireless MCU (Figure 3) is certified to Automotive Electronics Council (AEC)-Q100. This single-mode, Bluetooth low energy wireless controller integrates an RF transceiver, an MCU, and peripherals. “It has the most sensitive radio in the industry right now with level of -97dBm (at 1Mbps) and the best link power budget at 102dB (1Mbps). It supports full Bluetooth 5, to exchange data at high speeds of over 2Mbit per second and also support a long range of 1.5km (achieved in controlled environments),” says Daniel Torres, Product Marketing Engineer, for SimpleLink MCU platform, TI. The MCU draws just 6.1mA in RX and 7mA in TX (at 0 dB), and just 1.3µA in standby mode and 15nA in shut down mode. These characteristics extend the battery life of a wireless sensor within the vehicle.

Figure 3: The CC2640R2F-Q1 wireless MCU brings Bluetooth low energy to vehicles for user convenience and comfort.

“Bluetooth low energy can help the electrification of cars and make them more intelligent,” says Torres. It is primarily used for car access, where the ubiquitous smartphone is used as a key. “This use case is seeing a lot of momentum building up now with customers in industry,” continues Torres, citing the example of how it can be used for car rental, to allow customers to quickly and easily collect and drop off cars, as well as help manage the fleet inventory.

Another interesting use for Bluetooth low energy is a method to connect wireless sensors around the car. Reducing the number of wires reduces weight as well as assembly costs. “Wireless communication is a really good alternative to wired communication. It is something car manufacturers are thinking about as they want to make cars lighter to extend fuel economy and save costs,” says Torres.

“Initially, wireless sensors in cars were tire pressure monitors, but we are seeing the trend where those sensors may end up going to a Bluetooth low energy-based type of transceiver,” he adds.

They could enable the next generation of interface for vehicles’ computers and how those sensors interface with the end user, adds Torres. Taking the example of the engine sensor: “It is cryptic, it could mean many things have gone wrong in the car,” he says. “What Bluetooth low energy can do is use the phone as an extension of the instrument cluster and become another integral part of the human machine interface (HMI) and how the car is interacting with the users. You can get more information about what is happening with the sensors, and you can get a more compelling message and understand what’s going on with your car,” he believes.

A key trend in automotive now is having a key fob based on Bluetooth low energy, or having the phone as a key, says Torres. A smartphone can also be used as an intelligent remote keyless entry system. The car will recognize you as the driver and unlock the door, but also adjust the seat and steering wheel settings for convenience and comfort.

One feature of the CC2640R2F-Q1 wireless MCU worth spending time on here, is the sensor controller, which aggregates information from analog or digital sensors. A CPU on-chip manages the data coming from the sensors using serial interfaces or A/D converters. In this way, the main processor can be kept in low power mode.

The CC2640R2F-Q1 wireless MCU has an operating temperature range of -40°C to +105°C, making it suitable for use in various parts of a vehicle. Typical locations are in remote sensors, tailored to body control modules, used in engine control units, and in key fobs, confirms Torres.

The Bluetooth specification is well maintained, with many industry players contributing to the Special Interest Group (SIG), he points out. Added to that, Bluetooth’s configurability, with over-the-air updates and the ubiquity of the smartphone, he is confident that innovation will continue.

“Car manufacturers are always looking into how they can build cost effective and light cars, reduce the cost when it comes to sensors, modules etc. These are all trends happening with Bluetooth Low Energy for automotive applications,” concludes Torres.

TI is supporting developers with innovative products, and a compelling ecosystem, with Bluetooth-certified software and software development kit and support for the Bluetooth 4.0, 4.2, and 5 specifications. The SimpleLink MCU hardware ecosystem offering includes LaunchPad™ development kit and Booster Packs™ plug-in modules to help customers begin projects and reduce time to market.

 

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