The "eBooster + ESC" configuration has emerged as the dominant two-box solution for electric vehicles (EVs), balancing braking performance, energy recovery, and redundancy for advanced driver-assistance systems (ADAS).
Here's a concise breakdown of its core functions and challenges:
1. Core Functionality：Driver Braking Control
- Pedal Intent Detection: A pedal travel sensor in the eBooster measures pedal depth, transmitting data to the Driver Brake Request-Brake Force (DBR-F) module.
- Dynamic Force Allocation: The ESC (Electronic Stability Control) coordinates hydraulic braking (via wheel cylinders) and regenerative braking (via the electric motor). During braking, the ESC's high-capacity accumulator temporarily stores brake fluid, decoupling the master cylinder from wheel cylinders to optimize energy recovery.
- Energy Recovery: Regenerative braking converts kinetic energy into stored electrical energy via the motor's reverse torque, reducing reliance on friction brakes.
- Key Innovation: The ESC calculates a "virtual master cylinder pressure" using pre-calibrated torque curves (DBR-T module) to ensure consistent pedal feel despite fluid storage in the accumulator.
2. Brake Light Logic
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Normal Operation: The eBooster controls brake lights based on pedal input. The ESC activates lights only during stability interventions or ADAS-triggered braking.
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Fail-Safe Mode: If the eBooster malfunctions, the ESC's Hydraulic Brake Compensation (HBC) system takes over, managing both braking force and brake light activation.
3. ADAS Integration
The eBooster serves as the primary actuator for external ECUs (e.g., ADAS) due to its faster response and quieter operation compared to ESC-based braking, reducing long-term wear on the ESC system.
4. Advantages & Limitations
Strengths:
Dual redundancy (eBooster + ESC) supports ADAS and automated parking.
Enhanced energy recovery efficiency.
Adopted by major automakers: Tesla, Volkswagen ID series, Mercedes S-Class, NIO, XPeng, and Honda Accord.
Challenges:
Pedal Feel: Slightly less "natural" than traditional vacuum boosters due to electronic signal processing delays and regenerative-hydraulic coordination.
Complexity: Higher failure risks from interdependencies with ESC, ADAS, and powertrain systems.
Why It Matters:As EVs and ADAS proliferate, the two-box system strikes a critical balance between performance, efficiency, and safety. While not perfect, its scalability ensures widespread adoption across global automakers.