Exploring Dual Innovations in Power Technologies
Dual 48V and 12V battery systems in cars require bi-directional DC-DC controllers for optimal performance, explains Bruce Haug, a senior product marketing engineer at Analog Devices. As fuel economy standards tighten and autonomous driving with connectivity becomes more common, the traditional 12V automotive electrical system is hitting its power limits. Additionally, the increasing number of electronic systems in cars is creating both new engineering challenges and opportunities.
To address these challenges, the 12V lead-acid battery system, which has a 3kW power limit, is now being supplemented. A new automotive standard called LV148 is being proposed. This standard adds a secondary 48V system alongside the existing 12V system. The 48V system includes an Integrated Starter Generator (ISG) or Belt Start Generator, a 48V lithium-ion battery, and a bi-directional DC-DC converter. This setup can deliver up to 10kW of power from the combined 48V and 12V batteries, making it suitable for traditional internal combustion cars, as well as hybrid and mild hybrid vehicles. Car manufacturers aim to meet stricter CO2 emissions targets with this technology.
The 12V system will typically continue to power essential functions like ignition, lighting, and infotainment, while the 48V system will handle active chassis systems, air conditioning, adjustable suspensions, electric superchargers, turbos, and regenerative braking. Using a 48V system can also improve engine start, making stop-start operations smoother and reducing the need for large, heavy cables.
Modern cars can have more than 4 kilometers of wiring, making them akin to PCs and opening the door for various plug-and-play devices. With commuters spending an average of 9% of their day in their cars, adding multimedia and telematics can boost productivity and entertainment.
Key components for autonomous driving include computers, cameras, radar, and lidar sensors, which all need additional power. This extra energy ensures cars can connect not just to the internet, but to other vehicles, buildings, traffic signals, and other infrastructure. Furthermore, cars are moving from mechanical to electrical power for drivetrain components, power steering, and pumps for oil and water.
The shift to 48V systems is expected to happen sooner than the arrival of fully autonomous cars. Many automotive suppliers foresee strong demand for the technological components that will eventually enable self-driving cars. Some car manufacturers claim that a 48V electrical system can improve fuel economy by 10 to 15 percent in internal combustion engine vehicles, thus reducing CO2 emissions.
Future vehicles using both 48V and 12V systems will allow engineers to integrate electrical booster technology that operates independently of the engine, enhancing acceleration performance. The compressor, already in advanced development, will be placed between the induction system and intercooler and will use 48V to spin up the turbos.
Implementing an additional 48V supply network into cars presents significant design challenges for suppliers, especially those providing semiconductors and electronic control units (ECUs). These suppliers will need to adapt their products to handle higher voltages. Additionally, manufacturers of DC-DC converters will need to develop specialized integrated circuits (ICs) to facilitate high power transfer, leading to the design and development of new DC-DC converters.
