“Electric vehicles (EVs) are becoming more and more popular because of environmental features such as quality, simple functions, and most importantly, energy saving. Compared with fuel vehicles, electric motors have a simpler structure. At the same time, electric vehicles have outstanding advantages in energy efficiency: fuel vehicles have an energy efficiency of 16%, while electric vehicles have an energy efficiency of 85%. Continuous innovation and new electrical technology can still be achieved. Energy regeneration.
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Electric vehicles (EVs) are becoming more and more popular because of environmental features such as quality, simple functions, and most importantly, energy saving. Compared with fuel vehicles, electric motors have a simpler structure. At the same time, electric vehicles have outstanding advantages in energy efficiency: fuel vehicles have an energy efficiency of 16%, while electric vehicles have an energy efficiency of 85%. Continuous innovation and new electrical technology can still be achieved. Energy regeneration.
Electricity provides a lot of flexibility, including the use of various forms of energy harvesting to help charge the battery, thereby extending the running time of the electric vehicle itself. Therefore, energy harvesting technology has broad prospects in the research and development of electric vehicles.
The autonomy of electric vehicles directly reflects the efficiency of its power system and energy management system. In addition, necessary infrastructure, such as powerful fast charging systems that have reached hundreds of kW of power, must also strictly comply with pre-set size and efficiency limits. Silicon carbide (SiC) effectively responds to the needs of these emerging markets with its unique physical properties.
In hybrid electric vehicles (HEV) and electric vehicles, the main power systems are DC/DC boost converters and DC/AC inverters. Electronic systems developed for e-Mobility include everything from temperature, current and voltage sensors to semiconductor components based on SiC and gallium nitride (GaN).
Powerful SiC components
Nowadays, autonomy and charging time greatly hinder the popularization of electric vehicles. In order to charge quickly, a higher-power power supply is required to complete the charging in a shorter time. Due to the limited space in the car, the battery charging system must have high power density; only in this way can the system be integrated into the vehicle.
At the center of any electric vehicle or plug-in hybrid vehicle, we can see a high-voltage battery (200~450V DC) and its charging system. Thanks to the on-board charger (OBC), the battery can be charged through a household AC power source or a public or private charging station socket. From a 3.6kW three-phase high-power converter to a 22kW single-phase converter, today’s on-board chargers must have extremely high efficiency and reliability to ensure fast charging and meet the limited space and weight requirements.
All fast charging systems require the design of compact and efficient charging stations, and current SiC power modules can create systems with the required power density and efficiency. In order to achieve the great goals of power density and system efficiency, it is necessary to use SiC transistors and diodes.
The superior electric field strength of the high-hardness SiC substrate allows the use of a thinner base structure. This makes its thickness only one-tenth of the silicon epitaxial layer. In the future, the capacity of batteries will increase day by day, and this feature is related to shortening the charging time, which requires on-board chargers with high power and high efficiency (such as 11kW and 22kW).
With the introduction of the SCT3xHR series, Rohm can now provide the most extensive product line in the field of SiC MOSFETs that meet the AEC-Q101 standard, thereby ensuring the high reliability required for car chargers and DC/DC converters for automotive applications (Figure 1 ). STMicroelectronics also has a variety of MOSFET, silicon and SiC diode components that meet the AEC-Q101 standard, as well as 32-bit SPC5 automotive microcontrollers to provide scalable, cost-effective and energy-saving converters for these demanding converters. Solution (Figure 2).
Figure 1 Thermal characteristics of SCT3XHR. (Data source: Rohm)
Figure 2 Frame diagram of electric vehicle power system. (Data source: STMicroelectronics)
Vehicle to grid (V2G)
In the next 10 years, millions of battery-powered electric vehicles are expected to be on the road, which poses a major challenge to the grid. With the popularity of non-programmable renewable energy production, the requirements for a balanced power network are increasing.
When car batteries are connected to the network through household wall sockets, enterprises or public charging stations, the intelligent management of their batteries becomes very attractive. Car batteries can be used to supply power to the grid or to obtain electricity, depending on the urgent need to absorb electrical energy.
The system can return the energy accumulated in the car to the charging station, or extract energy remotely through the network (on the battery). The key technology to realize the system is a two-way power inverter, which is directly coupled to the high-voltage battery (300~500V) on the vehicle side and the low-voltage network side (Figure 3).
Figure 3 V2G technology.
V2G technology has the potential to achieve a more balanced and efficient power grid. The balance of power supply and demand will be the key to power demand growth.
Wireless charging
Wireless charging of electric vehicles is an exciting area, thanks to charging stations located in garages or public parking lots, and the charging points do not have to be precisely aligned with the receiver under the car. In the future, manufacturers will try to develop a micro-loading version that can integrate long load boards with public roads so that electric vehicles/hybrid vehicles can be charged even while driving, but this depends on the country and The degree of hindrance that the local administrative management will cause for this type of development.
In order for V2G technology to operate uninterruptedly, provide network stability advantages, and allow vehicles to act as generators and data sources, wireless charging technology must not only be integrated into the vehicle itself, but also into the home and urban infrastructure that charges the vehicle. Only in this way can vehicles meet the needs of the public in time.
Wireless charging based on electromagnetic resonance technology can enable various types of electric vehicles to automatically and safely charge by placing flexible coils on the power pad and using materials such as concrete and asphalt. With the help of wireless power, the vehicle can be automatically charged and implemented V2G technology, without manual intervention, continuous excitation and decay cycles (Figure 4).
Figure 4 Framework diagram for wireless charging of electric vehicles.
in conclusion
With the support of digital network capabilities, wide band gap semiconductor technology and fast charging stations will help accelerate the popularization of electric vehicles. As the global demand for electric vehicles continues to grow, the demand for support for charging infrastructure will also increase. The innovative charging technology of electric vehicles can become a catalyst for change, help promote the popularization of e-Mobility, and make many contributions to the realization of the goal of reducing carbon emissions.
The use of SiC power components in the power system of electric vehicles can improve the system’s energy efficiency, electric vehicle strength and power density, as well as high-voltage, high-power and high-power applications, thereby greatly improving system performance and long-term reliability. SiC MOSFET and SiC Schottky diode (SBD) ensure the highest conversion efficiency at high frequencies.
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