Electric vehicles are now becoming popular due to their eco-friendly features in terms of quality, functional simplicity, and energy efficiency. The functional thrust is driven by an electric motor, which has a simple structure compared to an internal combustion engine. Regarding energy efficiency, the comparison between combustion cars and electric vehicles is symbolic: combustion cars have an energy efficiency of 16%, while electric vehicles have an energy efficiency of 85%. The electrical nature of propulsion has an advantage over the nature based on combustion - renewable energy.
Electricity offers a lot of flexibility, including the use of various forms of energy harvesting that help charge the battery, extending the operating time of the vehicle itself. Therefore, energy harvesting technology is a prospect for electric vehicle research and development solutions.
The autonomy of electric vehicles directly reflects the efficiency of their powertrain and energy management systems. In addition, the necessary infrastructure, such as powerful fast charging systems that now reach hundreds of kilowatts, are also needed to comply with strict pre-set size and efficiency limits. Through its specific physical properties, silicon carbide (SiC) can effectively respond to these new market needs.
Among hybrid and electric vehicles, the leading electronic power systems are DC/DC boost converters and DC/AC inverters. Electronic systems developed for electric vehicles range from temperature, current and voltage sensors to semiconductors based on SiC and gallium nitride (GaN).
Silicon carbide is powerful
Today, autonomy and long charging times have become important barriers to the adoption of electric vehicles. For fast charging, more power is required to charge in less time. Due to the limited space available in the car, battery charging systems must provide high power density. Only then will it be possible to integrate these systems into the vehicle.
In the center of any electric vehicle (EV) or plug-in hybrid vehicle (HEV), we can find high-voltage batteries (200 to 450 VDC) and their charging systems. On-board chargers (OBC) provide a way to charge batteries from AC power in your home or at a public or private charging station. From 3.6 kW three-phase high-power converters to 22 kW single-phase, today's OBCs must have the highest possible efficiency and reliability to ensure fast charging and meet limited space and weight requirements.
All fast charging systems require a compact and efficient charging station, and current SiC power modules allow the creation of systems with the required power density and efficiency. To achieve ambitious goals regarding power density and system efficiency, SiC transistors and diodes must be used.
The excellent electric field strength of high-hardness SiC substrates allows the use of thinner substrates. Compared to the silicon epitaxial layer, this can reach one-tenth of the thickness. The trend in batteries is to increase capacity, and this feature is associated with shorter charging times. This, in turn, requires an OBC with high power and efficiency, such as 11 kW and 22 kW.
With the introduction of the SCT3xHR series, ROHM now offers the broadest product line in the AEC-Q101 qualified SiC MOSFET field, guaranteeing the high reliability required for on-board chargers and DC/DC converters for automotive applications (Figure 1). STMicroelectronics also has a wide range of AEC-Q101 compliant MOSFETs, silicon and silicon carbide (SiC) diodes, and 32-bit SPC5 automotive microcontrollers that provide scalable, cost-effective, and energy-efficient solutions for implementing these demanding converters (Figure 2).
Vehicle to the grid
Millions of battery-powered electric vehicles are expected to appear on the road over the next decade, posing a huge challenge to the grid. As the production of non-programmable renewable resources expands, so does the need for balanced networks.
When car batteries are connected to the network through home charging wallboxes or corporate or public charging stations, their intelligent management becomes extremely attractive. On-board batteries can be used to power the network as well as draw power, depending on the immediate need to absorb power.
The system uses a remote control to provide the return of energy accumulated in the vehicle or the recovery through the network (to the battery). The key technology to implement this system is a bidirectional power inverter that is coupled directly to the high-voltage battery (300 to 500 volts) on the automatic side and on the low-voltage network side (Figure 3).
Vehicle-to-grid (V2G) technology has the potential to make the grid more balanced and efficient. As electricity demand increases, balancing supply and demand is crucial.
Wireless charging
Thanks to charging points located in garages or public parking lots, an exciting area is wireless charging of electric vehicles. The charging point does not necessarily have to be precisely aligned with the receiver under the car. In the long term, an attempt will be made to develop a micro-loading version that can integrate long loading plates and public roads to load EV / HEV vehicles even while driving, but this will depend on the number of difficulties encountered at the national and local administrative levels.
In order for V2G technology to operate uninterrupted, provide the benefits of network stability and allow vehicles to act as generators and data sources, wireless charging technology must be incorporated not only into the vehicle itself, but also into home and urban infrastructure. The vehicle is charged. This will make the vehicle highly usable if required.
Wireless charging based on magnetic resonance technology allows electric vehicles, regardless of type or size, to be charged automatically and safely by placing flexible coils on the source plate using materials such as concrete and asphalt. Wireless power will enable vehicles to charge autonomously and implement V2G technology that continuously excites and attenuates without human intervention (Figure 4).
conclusion
Broadband semiconductor technologies and fast charging stations enabled by digital network capabilities will help accelerate the adoption of electric vehicles. As global demand for electric vehicles increases, so does the need to support charging infrastructure. Innovative charging technologies for electric vehicles can be a catalyst for change, help promote the adoption of electric vehicles, and contribute a lot to the goal of reducing carbon emissions.
The power electronics of electric vehicles are enriched with SiC power devices to meet the needs of improvement: the energy efficiency of the system; the strength and power density of electric vehicles; and high-power applications that require high voltage and power – thus making an important contribution to system performance and long-term reliability. SiC MOSFETs and SiC Schottky barrier diodes (SBDs) ensure the highest switching efficiency at high frequencies.