In the electronic architecture of intelligent EVs, the communication network is like the nervous system of the vehicle. Understanding the wisdom of "collaboration in separation" is the key starting point to grasp the essence of modern automotive electronic architecture.
With the popularity of domain control architecture and automatic driving, the importance of chassis CAN and power CAN as "functional twins" is becoming more and more prominent. They not only undertake the most critical real-time control tasks of the vehicle, but also cooperate precisely through the gateway in the physical quarantine—this design philosophy perfectly illustrates the art of balancing "functional safety" and "system integration".
Main Differences between Chassis CAN and Power CAN
Core Functions and Purposes
Typical Connected ECUs
- Engine Control Unit
- Transmission Control Unit
- Motor Controller
- Battery Management System
- Vehicle Controller (power coordination)
- Electronic Accelerator Pedal
- ABS/ESP Control Module
- Electric Power Steering Control
- Electronic Parking Brake Control
- Adaptive Suspension Control
- Tire Pressure Monitoring System
- Four-Wheel Drive Control
Real-Time Requirements
Security and Quarantine
Main Connections between Chassis CAN and Power CAN
Both are High-Speed Vehicle Networks
Chassis CAN and Power CAN are typically high-speed CAN networks following ISO 11898-2 standard, using twisted pair with baud rates of 500kbps (most common) or 1Mbps. They are distinguished from body comfort CAN (125kbps) and infotainment CAN.
Interconnected via Central Gateway
The core link between the two networks. Modern EVs have central gateway modules that act as routers, firewalls, and protocol converters between different network domains. While physically separate, they are logically connected via the gateway for secure, controlled information exchange.
Information Interaction and System Collaboration
Critical information flows between networks: brake pedal signals inform the powertrain of deceleration needs; wheel speed/ESP signals request torque reduction during slip; powertrain status affects chassis control strategies; regenerative braking coordination requires pressure distribution adjustment.
Joint Support for ADAS and Autonomous Driving
Advanced driver assistance and autonomous driving functions require coordination between powertrain (acceleration/deceleration) and chassis (steering/braking) systems. The gateway must efficiently transfer sensor data and control commands between Power CAN and Chassis CAN.
Chassis CAN vs. Power CAN: Quick Comparison
| Characteristic | Power CAN | Chassis CAN | Connection |
|---|---|---|---|
| Core Functions | Powertrain control (engine/motor, transmission, BMS) | Driving control and dynamic stability (braking, steering, suspension, ESP) | High-speed on-board network (500kbps/1Mbps) |
| Primary ECUs | ECU, TCU, MCU, BMS, VCU (partial) | ABS/ESP, EPS, EPB, Suspension Control, TPMS | Interconnect via Central Gateway |
| Real-Time | Highest (millisecond level, 5-10ms common) | Very high (millisecond level, 10-50ms common) | Gateways enable secure, controlled information exchange |
| Security | Extremely high (failure may result in loss of power) | Extremely high (failure directly affects braking/steering safety) | Support the cooperative work of key functions |
| Data Content | Speed, torque, throttle, gear, battery status | Wheel speed, brake pressure, steering angle, yaw angle, tire pressure | Support ADAS and Autopilot functions together |
Future Trends and Evolution
Functional Integration
Intelligent driving domain controllers will take over some chassis control functions like automatic emergency steering.
Latency Challenges
L4 autonomous driving requires cross-network response speeds to exceed the 1ms threshold for safety-critical operations.
Safety Redundancy
Dual gateway architecture becomes standard in high-end vehicles for enhanced fault tolerance and system reliability.
The "separate cooperation" mode of chassis CAN and power CAN is undergoing a historic transformation. With the rise of vehicle-cloud integration and Gigabit Ethernet backbone networks, these classic networks will evolve into virtual channels within domain controllers. Their core design philosophies—"secure quarantine" and "precision collaboration"—will continue to influence next-generation electronic architectures.
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Frequently Asked Questions
Common questions about CAN networks in electric vehicles
Why are Chassis CAN and Power CAN separated in EV architecture?
Separating these networks provides critical fault isolation. If a non-critical system (like infotainment) fails or experiences network congestion, it won't affect the vehicle's power delivery or braking/steering systems. This separation enhances functional safety and system reliability, which is especially important in safety-critical automotive applications.
Can data from Power CAN directly communicate with Chassis CAN without a gateway?
No, direct communication between Power CAN and Chassis CAN is not recommended in modern vehicle architectures. The gateway serves as a controlled interface that filters, validates, and routes only necessary information between the networks. This controlled communication prevents potential issues like network overload, unauthorized access, or fault propagation between critical systems.
How does regenerative braking involve both Power CAN and Chassis CAN?
Regenerative braking requires close coordination between both networks. When the driver presses the brake pedal (signal on Chassis CAN), the braking system needs to determine how much braking should be done by the electric motor (regenerative, managed via Power CAN) versus the traditional hydraulic brakes (Chassis CAN). The gateway facilitates this coordination by sharing brake pressure data, motor status, and battery charge level between the networks.
Will Automotive Ethernet replace CAN networks in future EVs?
While Automotive Ethernet is increasingly used for high-bandwidth applications like cameras and infotainment, CAN networks will likely remain for safety-critical functions like power and chassis control due to their proven reliability, determinism, and cost-effectiveness. Future architectures will probably use a combination: Ethernet for backbone/high-speed data and CAN for dedicated control networks, with gateways bridging between them.
What happens if the gateway fails in an EV?
Gateway failure is a critical fault in modern vehicles. High-end EVs often implement redundant gateways or fail-safe modes. In case of gateway failure, systems typically revert to a safe state: power systems may continue basic operation, chassis systems maintain essential functions, but advanced features requiring cross-network coordination (like regenerative braking optimization or adaptive cruise control) may be disabled until the gateway is repaired.