Reducing wiring harness complexity and weight are vital benefits of using a zonal architecture in an EV, but they are not the only benefits. Zonal architectures can also support software-defined vehicle functionality that will optimize EV performance, and they support improved power distribution architectures that will, in turn, increase EV operating efficiency.
This FAQ begins with a review of existing domain architecture in automobiles, then presents alternative implementations of zonal architectures and looks at how those architectures will improve performance. Today’s domain architectures organize the electronic control units (ECUs) based on their functions. Examples of domain functions include infotainment, body control, telematics, advanced driver assistance systems (ADAS), and passive safety functions.
The ECUs in a domain are connected over a network optimized to perform specific functions and can also communicate with other domains, usually through a gateway (Figure 1). An optional domain controller can include multiple ECUs, reducing costs and improving performance.
In a zonal architecture, the ECUs are categorized based on their location within the vehicle. The controller is closer to the ECUs, reducing the needed cabling, simplifying the wiring harness, and reducing harness weight by up to 50% with a corresponding reduction in vehicle weight. A zonal architecture can improve data and power distribution.
Developing time-sensitive networking (TSN) in automotive Ethernet is an enabling technology for zonal architectures. It allows efficient communication between ECUs that were in the same domain but are now separated into different zones.
A zonal architecture also supports implementing software-defined vehicle (SDV) functionality. Instead of adding new hardware (ECUs) to add new functions, SDV enables new functions to be downloaded using over-the-air updates into the powerful central vehicle controller. This enables what’s termed continuous integration and continuous deployment (CI/CD) of new vehicle functions in near real-time. (For a discussion of SDVs and EVs, see the FAQ on software-defined vehicles.) The number of zone controllers can vary depending on the requirements and complexity of the vehicle (Figure 2).
Zonal power distribution advantages The zonal architecture also supports using smart power junction boxes that distribute power to the various ECUs and loads and are connected to the central vehicle controller. These smart junction boxes use semiconductor solutions to replace relays and fuses for power control and management. Smart fusing is an example of the benefits of a zonal architecture for EV power distribution.
A smart fuse uses a power MOSFET to quickly turn off the power in case of an overload. It can react faster than a conventional melting fuse, providing enhanced protection. Smart fuses can improve battery energy usage in an EV. That can be especially useful if the battery is getting low on charge. Smart fuses can shut down non-essential functions enable increased range, and extend battery operating life. For example, the heating, ventilation, and air conditioning (HVAC) system can be turned off for intervals too brief to impact occupant comfort but long enough to significantly impact a longer driving range.
Another example is to turn off the HVAC compressor during peak load demands on the battery, such as power steering during a sharp turn. Reducing the battery’s peak discharge rate can significantly improve the operating lifetime of the battery. A smart fuse can sense if the circuit it’s attached to experiences an increase in impedance and alert the central controller of the need for maintenance before a system failure occurs.
When using melting fuses, the power distribution wiring is usually designed 30% larger than needed for the basic power requirement to account for the peak loads required to melt a conventional fuse. With smart fuses in a zonal architecture, wiring can be sized for the load requirements, often meaning a reduction of one wire gauge size, reducing the size and weight of the power distribution wiring harness.
The use of zonal architectures in EVs will result in simpler wiring harnesses and a corresponding weight reduction enabling longer driving ranges. It will also allow the deployment of SDV functionality, improving driver experiences and EV performance.
Additionally, it will support the deployment of smart fusing that will enable the use of smaller power distribution wiring, further reducing the weight of the wring harness.
- How Zonal E/E Architectures with Ethernet Are Enabling Software-Defined Vehicles, NXP
- Processing the advantages of zone architecture in automotive, Texas Instruments
- Zone Controllers Build Bridge to Tomorrow’s Technology, Aptiv
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