Sensor applications and solutions for light electric vehicles
When we talk about light electric vehicles (LEVs), most people will picture a car. But electrification is not confined to the automotive industry: it encompasses other vehicles such as e-bikes, e-scooters and e-motorbikes, as well as golf carts and even forklift trucks. Whatever their shape or function, LEVs require semiconductors and microchip sensor systems to function correctly.
All types of LEVs have some common applications, including battery management, electric propulsion, wireless connectivity, and motion sensing. Where vehicles form part of a commercial fleet, there is also a requirement for precise, remote communication between individual vehicles and the fleet operator so that parameters such as location, vehicle status and battery charge levels can be monitored continuously. When we delve into specific vehicles, there are additional requirements for semiconductor technology.
LEV use cases
E-bikes, for example, represent a rapidly growing section of the LEV market as consumers seek alternative, cheaper, and cleaner modes of transport for commuting and leisure. Its worth in terms of semiconductor spend is predicted to reach $320 million globally by 2030. Much of the focus is on electric propulsion: the e-motor drive, battery management and cadence pedal sensor. However, e-bikes are also being designed with front and rear lighting controls, tire pressure monitors, and collision detection. Users are also coming to expect the same sophisticated navigation, connectivity, and security systems that they experience in automobiles, which means e-bikes need an integral human-machine interface (HMI).
At the other end of the LEV spectrum, electric forklift trucks are an even bigger market for semiconductor technology. They have grown in popularity as companies decarbonize their supply chain: and because vehicle exhaust fumes in confined spaces don’t make for a safe working environment. Applications include pallet loading and positioning sensors, localization, mapping, collision avoidance, and load engagement systems that mean the forklift can operate safely and efficiently in the confines of a busy warehouse. A typical forklift truck typically carries at least $500 worth of semiconductor technology on board.
LEV end-to-end solutions
Clearly, there is a growing demand for semiconductor technology in all LEVs, not just cars. ST Microelectronics portfolio contains semiconductor technology solutions for virtually every application.
For example, our STM32 range of general-purpose 32-bit MCUs is ideal for processing and control. Based on our cortex architecture, they offer enhanced graphics capabilities, smart peripherals, comprehensive motor control algorithms and various safety and security features compatible with LEV designs. For motor control, ST has a robust portfolio of discrete and integrated design options, incorporating all three aspects of BLDC motor control. These comprise power state MOSFETs, gate drivers and MCU algorithms and control. Longer run times and greater efficiency in power and battery management is possible thanks to our BMS chip and a wide selection of voltage regulators with a low quiescent current that is ideal for battery-powered applications. The portfolio is completed with a wide selection of motion MEMs sensors - including accelerometers, gyroscopes, six-axis IMUs, e-compasses and temperature sensors – which have machine learning and AI features integrated onto the chip.
Improving vehicle location technology is an ongoing challenge. ST offers chipsets or a complete GNSS module with a position receiver that is compatible with all global positioning standards relating to multi-band and multi-constellation satellite signal receivers. Our latest devices feature an integral six-axis MEMs sensor that helps to detect the precise location of a vehicle even when direct visibility with the GPS satellite is lost. This loss of signal can typically be caused by urban canyons and multi-storey car parks. The additional MEMs sensor makes it possible to ascertain on exactly which level of a carpark the vehicle has stopped, even without direct contact with the satellite.
Hybrid solutions
The LEV applications we have considered so far operate on 12-volt battery power. Hybrid vehicles, however, use a 48-volt supply. Until recently, the market for 48v hybrid vehicles was considered a dying market – particularly in Europe where the transition to pure electric vehicles is practically complete (at least from an OEM perspective). However, the US market has seen a resurgence in demand as consumers continue to consider multiple vehicle options.
ST is therefore continuing to develop products for 48v LEV applications. One example is our L9908 BLDC motor driver, which can be used to control the motor, power steering, oil pump, water pump or engine cooling fan in hybrid or electric vehicles of 12v, 24v or 48v. Acting as a gate driver for the Vset MOSFET bridge, the L9908 can be connected directly to a 48v power supply. It integrates a two-stage charge pump for generating the highest voltage for the motor bridge and features an SPI interface for configurability and diagnostics. It is also equipped with three current sensor amplifiers to measure the motor current in the low side path of each of the three motor current phases. The L9908 is certified to AEC-Q100, to operate in the high temperature environment beneath the hood, and to ASIL-D for functional safety.
Another exciting new development is the new VNF1048F gate driver – the first automotive grade, high side MOSFET driver with integrated, configurable e-fuse. The e-fuse provides additional protection for the MOSFET and the loads and actuators connected downstream in any 12v, 24v or 48v system. Equipped with completely digital diagnostics and an AD converter, the VNF1048F allows the application MCU to access information via the SPI interface regarding parameters such as junction temperature, operation voltage, output current, and drain source voltage.
The unique STi2 Fuse IP that ST has developed reduces weight and current load, while guaranteeing high precision and a rapid response. Crucially, this e-fuse can be reset rather than replaced following an incident, which makes it a key enabler for autonomous vehicles. Watch this space for more EV solutions featuring this technology!
Evolving market
From the rapid rise in e-bikes to the resurgence of electric hybrids, the LEV market is dynamic and continues to evolve. It therefore requires some agility to find timely solutions to emerging challenges and capitalize on new opportunities.
To help vehicle designers speed up application development, ST offers a complete motor control tool kit complete with software libraries for field-oriented control algorithms. The AutoDevKit includes plug-and-play development boards plus compatible software modules so that customers can build a complete application quickly. It is possible to realize a complete BLDC motor control application within hours using this tool. The AutoDevKit therefore enables faster prototyping and a shorter time to market for LEV designers and manufacturers.
Conclusion
The challenges of replacing the internal combustion engine with electric vehicles is still a work in progress. As a leading semiconductor technology manufacturer, ST continues to anticipate the challenges arising in the dynamic LEV sector to develop innovative sensor and control solutions that add value in terms of performance, reliability, and durability in demanding operating environments.
