Over the past three decades, automotive electronics have undergone a remarkable evolution, transitioning from traditional internal combustion engines (ICE) to the emergence of battery electric vehicles (BEVs). This progression has not only transformed the way vehicles operate but has also driven significant changes in power distribution architectures and semiconductor components. In this blog post, we examine the three major stages of this evolution – from ICE to mild hybrid (MHEV) to BEV – and explore the role of low voltage power distribution in shaping the automotive landscape.

First Stage: Internal Combustion Engines (ICE)

In earlier years, automotive electronics were relatively straightforward, with mechanical systems dominating the scene. ICE vehicles of the 1990s and 2000s consumed minimal continuous electrical power, mainly for functions like electronic ignition, the radio, and electric windows or seats. The electrical demands peaked at about 12 kW for instantaneous engine starting. During this era, a direct connection between the battery and starter motor sufficed to provide the required power boost for ignition.

Second Stage: Mild-Hybrid Electric Vehicles (MHEV)

The advent of mild-hybrid technology marked the beginning of the electrification journey. Electric motors were incorporated to enable start-stop functionality and gradually assist in propulsion. Notable vehicles like the Honda Insight and Toyota Prius showcased the potential of electric motors in enhancing both power and fuel efficiency. With these advancements came a surge in electrical power requirements, escalating from 3 kW for simple start-stop systems to around 30 kW for advanced plug-in hybrids.

This increase in power needs required a transition from the conventional 12 V electrical system to a more robust 48 V system. The higher voltage allowed for the distribution of power to various components, including the electric drive, air conditioning, fuel and water pumps, power steering, and infotainment systems. This evolution towards 48 V distribution systems significantly reduced the load on wiring harnesses, enabling more efficient and cost-effective power delivery.

Third Stage: Battery Electric Vehicles (BEV)

The current automotive landscape is dominated by the rise of battery electric vehicles (BEVs). These vehicles are solely powered by electricity, and as a result, all functions must be continuously powered by electrical systems. While the power requirements for individual electrical loads are like those in MHEVs, minus the start stop function, the unique challenge in BEVs lies in the added need for electrical cabin heating and battery temperature management. BEVs generally require around 3 kW of electrical power.

Like MHEVs, BEVs benefit from the 48 V distribution system due to its efficiency and cost-effectiveness. However, the integration of BEV power systems with high-voltage traction drives (typically 400 V or 800 V) demands electrical isolation to ensure safety. This isolation is achieved through the incorporation of isolated power supplies and advanced conversion technologies, such as silicon carbide (SiC) or gallium nitride (GaN) transistors.

Why GaN for 48 V Automotive Systems

GaN FETs and ICs offer distinct advantages over traditional silicon-based solutions, making them well-suited for the high-performance power electronics applications needed for automotive power distribution systems. For 48 V bus systems, GaN technology increases efficiency, shrinks the size, and reduces system cost.

Efficiency: GaN devices have lower on-resistance and switching losses compared to their silicon counterparts. This translates to higher conversion efficiency which minimizes energy losses and helps improve overall vehicle efficiency.

Smaller Size: GaN devices are inherently smaller in size than traditional silicon devices. This reduced size allows for higher power density reducing the size and weight of the DC-DC converters used in the 48 V architecture.  In addition, the ability to switch at much higher frequencies can cut the size in half while reducing component counts by the same ratio.

Cost Savings: GaN-based solutions allow for less complex designs. As an example, due to the fast-switching speed, GaN-based solutions can operate at 250 kHz per phase as opposed to 125 kHz per phase for traditional MOSFET solutions. In a 3 kW 48 V – 12 V converter, the higher switching frequency results in the reduction from a five-phase system to a four-phase system, reducing both size and cost.

Emerging Trends and Future Directions

Drawing parallels with developments in artificial intelligence (AI) servers, which have transitioned to distributed power architectures for enhanced efficiency, automotive power distribution is also poised for similar advancements. The concept of zonal power architectures, with smaller DC-DC converters strategically placed around the vehicle, holds potential to streamline wiring systems and enhance efficiency. This approach could ultimately lead to the elimination of low-voltage batteries in favor of direct power supply from main battery systems.

For a larger discussion on this topic, read the article in Power Systems Design: The Evolution of Low Voltage Power Distribution in Automotive Electronics – From ICE to MHEV to BEV

Conclusion

The evolution of automotive electronics, from ICE to MHEV to BEV, has brought about substantial changes in power distribution architectures and technologies. The transition from 12 V to 48 V distribution systems has been driven by the increasing power demands of electrically assisted vehicles, both mild hybrids and BEVs. These shifts have prompted the adoption of advanced semiconductor technologies like GaN transistors, offering higher efficiency, smaller size, and cost-effectiveness. 

To learn more about how GaN is accelerating vehicle electrification, contact EPC.

Renee Yawger, Director of Marketing