Consumer demand continues to rise, and electric vehicles (EVs) must extend their range in order to compete with traditional internal combustion engine (ICE) vehicles. There are two main methods to solve this problem: increasing battery capacity without significantly increasing battery size or weight, or improving the operational energy efficiency of key high-power devices such as main drive inverters.

To cope with the huge power loss caused by conduction and switching losses of electronic components, car manufacturers are increasing the battery voltage to increase the vehicle's range.

As a result, the 800 V battery architecture is becoming increasingly popular and may eventually replace the current 400 V technology. However, the larger the battery capacity, the longer the charging time required, which is another concern for car owners, meaning that if they need to charge midway before arriving at their destination, they will have to wait for a long time.

Therefore, just as there is a need to increase battery voltage, car manufacturers must also keep up with the development of electric vehicle on-board chargers (OBCs), and the first consideration must be to support 800 V battery architectures and handle higher voltages. Therefore, the current standard of 650 V rated chip components needs to transition to chip components with a maximum rated voltage of 1200 V. In addition, to accelerate battery charging rate, the demand for higher rated power OBC is also increasing day by day.

Consumers urgently need better performance

OBC can convert alternating current into direct current, allowing cars to charge using AC power sources such as the power grid. The peak output of the charging station will significantly limit the charging speed, and similarly, the peak power processing capability of OBC is also a major factor affecting the charging speed.

In the current charging infrastructure, charging stations are divided into three levels:

The maximum power of level 1 is 3.6 kW

The power of level 2 ranges from 3.6 kW to approximately 22 kW, which is equivalent to the maximum capacity of OBC

Level 3 provides direct current without the need for OBC, with power ranging from 50 kW to 350+kW

Although fast 3-level DC charging stations have been put into use, their global distribution is limited, so OBC is still indispensable. In addition, many companies are striving to improve the performance of their existing Level 2 charging infrastructure and promote the adoption of higher voltage battery technologies, and the market demand for higher energy efficiency OBCs is expected to continue to grow.

Firstly, we need to clarify that charging is not a linear process. When the battery approaches full capacity (usually over 80%), the charging speed slows down to protect the battery's health. Simply put, the more fully charged the battery, the slower it can receive electrical energy. Electric vehicles are usually not fully charged, and many electric vehicle manufacturers do not recommend frequently waiting for the battery to deplete to 0% and then fully charging to 100%. Instead, they only need to charge a portion (such as up to 80%), which can significantly shorten the charging time. In addition, the trend of electrification is gradually extending to various types of vehicles such as buses, trucks, heavy vehicles, agricultural vehicles, and even ships. OBC will continue to develop with the goal of achieving higher power levels above 22 kW.

Automobile manufacturers can improve the charging speed of Level 2 charging stations by building more powerful OBCs, but this requires the use of economically efficient and reliable electronic components to achieve higher voltages (800 V instead of 400 V) and higher power levels.

Key design considerations for higher performance OBC

For higher performance OBCs, there are many factors to consider besides rated power and battery voltage. This includes heat management, packaging limitations, device costs, electromagnetic compatibility (EMC), and potential demand for bidirectional charging.

When it comes to heat management, it is easy to think of increasing the size and weight of the OBC. However, this simple solution is not ideal because the space of electric vehicles is limited, making it difficult to accommodate excessively large OBCs, and the increase in weight can also lead to a shortened range of the vehicle.

The 800 V battery architecture can bring many benefits, such as reducing conduction losses, improving performance, accelerating charging and power transmission speed, but it also poses many complex challenges for designers:

Device supply: Finding devices suitable for safe operation at 800 V may be difficult.

Derating to ensure reliability: Even qualified devices may require derating, which means operating at power below maximum capacity to ensure long-term reliability.

Safety issue: Higher voltage systems require strong insulation and safety functions.

Testing and verification: Verifying high-voltage systems is more complex and may require specialized equipment and expertise.

For this, it is necessary to use components with higher breakdown voltage, especially for MOSFETs. It has been proven that switching to high-performance silicon carbide (SiC) components would be highly beneficial in higher voltage applications that require faster MOSFET switching, such as OBC. When developing PCB layouts, it is also crucial to consider voltage levels, as it may be necessary to correspondingly increase the spacing between components and the distance between PCB traces. Similarly, other devices exposed to higher voltages (such as connectors, transformers, capacitors) also require higher ratings.

Improve OBC design to enhance performance and functionality

Onsemi is a trusted supplier of high-power automotive application power modules that can provide strong support for the transition to 800 V battery systems. Anson's advanced EliteSiC 1200 V MOSFET and Automotive Power Module (APM) have been widely recognized in the field of automotive design for their ability to achieve higher power density.

The APM32 power module series integrates advanced 1200 V SiC devices from Anson, optimized for an 800 V battery architecture, and is more suitable for high voltage and power level OBC. The APM32 series includes three-phase bridge modules for power factor correction (PFC) stages, such as NVXK2VR40WDT2 using 1200 V 40 m Ω EliteSiC MOSFET (integrated temperature sensing). This module is designed specifically for 11-22 kW OBC terminal applications.

Compared to discrete solutions, APM32 module technology has multiple advantages, including smaller size, better heat dissipation design, lower stray inductance, lower internal bonding resistance, stronger current capability, better EMC performance, and higher reliability, which helps to create high-performance bidirectional OBC (Figure 3). This not only enhances the functionality of vehicle OBC, but also allows electric vehicles to serve as mobile battery energy storage devices.

5.png

Figure 3: High power (11 kW-22 kW) bidirectional OBC scheme using EliteSiC 1200V APM32 power module

The OBC power stage example in Figure 3 includes a boost type three-phase PFC and a bidirectional CLLC full bridge converter, which are used to provide necessary power and voltage processing as well as advanced bidirectional charging functionality.

As the world gradually shifts towards sustainable energy sources such as solar and wind power, the power supply of the grid may sometimes be in short supply. Fully charged electric vehicles can serve as important energy storage resources to support peak demand of the power grid or in emergency situations where the main power source of a building is damaged. By utilizing modules such as Ansenmei APM32, OBC can achieve bidirectional energy transfer of electric vehicle batteries. As a result, the energy stored in the battery can provide temporary power to the house and can be charged at any time thereafter.

Reliable design and supply

Unlike some competitors who outsource packaging technology, Ansenmei's APM series is designed and manufactured internally, allowing for better control over heat dissipation optimization. In addition, Ansenmei provides manufacturers with a range of packaging and manufacturing options, including bare chips, discrete components, or modules, to ensure that there is a suitable solution to support any advanced OBC design.

conclusion

OBC technology is flourishing, not only helping car manufacturers meet consumers' demand for electric vehicles, but also effectively responding to new technological trends such as 800 V battery architecture. By utilizing Anson's system solutions, such as the APM32 power module, automotive designers can simplify processes and effectively meet new demands, ensuring higher quality, reliability, and supply chain consistency while significantly reducing design work.

In addition, Ansenmei also provides extensive technical support, simulation, and other power solutions, including EliteSiC 1200V M1 and M3S MOSFETs, EliteSiC 1200V D1 and D3 diodes, as well as matching devices such as electrically isolated gate drivers, CAN transceivers, and resettable fuses, aimed at achieving comprehensive and high-performance OBC design.

Download our OBC system solution guide and explore the use of various components and solutions from Anson to achieve high-performance OBC.

This is reported by Top Components, a leading supplier of electronic components in the semiconductor industry

They are committed to providing customers around the world with the most necessary, outdated, licensed, and hard-to-find parts.

Media Relations

Name: John Chen

Email: salesdept@topcomponents.ru