Background and Requirements
With increasing global focus on environmental protection and energy conservation, the automotive industry faces immense pressure to continuously explore and adopt new technologies to reduce emissions and improve fuel economy. Traditional 12V automotive electrical systems are proving inadequate to meet the growing electricity demands of modern vehicles. For example, the increasing number of electronic devices in vehicles, such as intelligent driving assistance systems and high-power in-vehicle entertainment systems, places higher demands on power supply. The 12V system struggles to ensure the stable operation of these devices and incurs significant energy losses when transmitting high power. Furthermore, to meet stringent emission regulations, automakers need to find solutions that effectively improve vehicle energy efficiency without significantly increasing costs and technological complexity; this is where the 48V automotive system comes in.
System Principles and Structure
A 48V automotive system adds a 48V voltage rail to a traditional 12V electrical system. Its core components include a 48V lithium-ion battery, a motor (such as a belt-driven starter/generator (BSG) or an integrated starter/generator (ISG), and a DC/DC converter. The 48V lithium-ion battery stores electrical energy, providing power to high-power devices and the motor. The BSG motor is connected to the engine via a belt; during vehicle start-up, it quickly starts the engine, reducing start-up time and vibration; during acceleration, it provides additional torque assistance, improving power performance; and during deceleration or braking, it converts kinetic energy into electrical energy and recovers it into the battery. The ISG motor is directly connected to the engine crankshaft, enabling more efficient energy recovery and auxiliary drive functions. The DC/DC converter converts the 48V voltage to 12V to power the vehicle's existing 12V electrical equipment, enabling the two voltage systems to work together.
Significant advantages
Energy saving and environmental protection
A 48V mild hybrid system can significantly improve a vehicle's fuel economy. Firstly, through an energy recovery system, the kinetic energy generated during braking or deceleration is converted into electrical energy and stored. This electrical energy is then used to assist in driving later, reducing the engine's workload and thus lowering fuel consumption. According to relevant tests, vehicles equipped with a 48V mild hybrid system can improve fuel economy by 10%-15% compared to traditional gasoline vehicles. Secondly, the reduced engine workload means reduced exhaust emissions, helping to reduce harmful gas pollution and better meet increasingly stringent environmental regulations.
Improve power performance
During vehicle start-up and acceleration, the 48V system's electric motor responds quickly, providing additional torque to the engine. This results in faster and smoother starts and smoother acceleration, effectively improving the driving experience. The advantages of the 48V system are particularly evident in congested urban traffic with frequent start-stop operations, reducing the time the engine spends in its inefficient operating range and enhancing the vehicle's overall power performance.
System cost and weight advantages
Compared to high-voltage hybrid or pure electric systems, 48V systems are less expensive. Their architecture is relatively simple, requiring no complex high-voltage safety measures, thus reducing the cost of related equipment. Furthermore, because 48V systems draw less current at the same power output, thinner and lighter cables and connectors can be used, reducing wiring harness costs and overall vehicle weight. This weight reduction further improves fuel economy, creating a virtuous cycle.
Current Application Status
Currently, 48V automotive systems are widely used in the field of mild hybrid vehicles. Many automakers have launched models equipped with 48V mild hybrid systems. For example, some Mercedes-Benz models use a 48V system, effectively improving vehicle power performance and fuel economy, while reducing vibrations during start-stop processes and enhancing ride comfort. Audi has also applied 48V technology in several models, optimizing vehicle dynamic response through the coordinated operation of the 48V system and engine. Furthermore, some domestic automotive brands such as Geely and Great Wall Motors are also actively developing 48V mild hybrid technology, applying it to many of their models, thus promoting the widespread adoption of 48V systems in the Chinese market.
Future development trends
With continuous technological advancements and market maturation, 48V automotive systems are expected to see wider application and further development in the future. On one hand, ongoing innovation in semiconductor technology will drive key components of 48V systems, such as power chips and controllers, towards higher performance and lower costs, further enhancing the overall performance and reliability of the system. On the other hand, 48V systems will be deeply integrated with emerging technologies such as intelligent driving and vehicle-to-everything (V2X) communication. For example, they will provide stable power support for sensors and controllers in intelligent driving, ensuring the efficient operation of the system; and through V2X technology, they will enable remote monitoring and management of the 48V system, optimizing energy distribution strategies and improving the overall intelligence level of the vehicle. Furthermore, as more automakers join the research and application of 48V systems, market competition will further reduce their cost, accelerating their adoption in the automotive market and making them one of the important trends in future automotive electrification.
