EVCC and CCS2: Theory, Architecture, Standards, and Compliance
Abstract: The Electric Vehicle Communication Controller (EVCC) is the digital intelligence that enables safe, interoperable, and future-ready electric vehicle charging under the Combined Charging System Type 2 (CCS2). This document provides a full academic-grade and OEM-oriented theoretical exposition of EVCC and CCS2, beginning from first principles and progressing toward modern protocol amendments, cybersecurity, and regulatory compliance.
Chapter 1: Introduction to Electric Vehicle Charging Communication
1.1 Why Charging Is Not “Just Electricity”
In early electric vehicles, charging was treated as a unidirectional energy transfer problem. However, as battery capacities increased, charging power rose from kilowatts to hundreds of kilowatts, and public charging networks proliferated, the limitations of “dumb charging” became evident.
Modern EV charging is a cyber-physical process involving:
- Electrical safety verification
- Battery capability negotiation
- Thermal and voltage supervision
- Authentication and billing
- Grid coordination and demand response
All these functions require structured, deterministic, and secure communication. The EVCC is the subsystem that performs this role within the vehicle.
1.2 Definition of EVCC
The Electric Vehicle Communication Controller (EVCC) is a dedicated logical and often physical controller within an electric vehicle that implements standardized communication protocols enabling interaction with Electric Vehicle Supply Equipment (EVSE).
From a systems engineering perspective, the EVCC is:
- A protocol endpoint
- A state-machine executor
- A security credential holder
- An interface between vehicle control units and external infrastructure
1.3 CCS2 in Global Context
The Combined Charging System (CCS) was developed to unify AC and DC charging under a single connector and communication framework. CCS2, based on the Type 2 connector, is dominant in:
- Europe
- India
- Middle East
- Large parts of Asia
Unlike legacy charging systems, CCS2 integrates high-speed digital communication using Power Line Communication (PLC) directly over the charging cable.
Chapter 2: Historical Evolution of EV Charging Communication
2.1 Pre-Standard Era
Early EVs relied on simple analog signaling. Chargers applied fixed voltage/current profiles with minimal feedback. This approach suffered from:
- Safety risks
- Battery degradation
- Lack of interoperability
2.2 Introduction of IEC 61851
IEC 61851 introduced the concept of Control Pilot (CP) and Proximity Pilot (PP) signals, allowing basic negotiation of current limits. However, it lacked:
- Vehicle identification
- Security
- Dynamic energy management
2.3 DIN 70121 – The First Digital Leap
DIN 70121 introduced digital messaging over PLC, enabling:
- Voltage and current negotiation
- DC fast charging
- Improved safety interlocks
However, DIN 70121 was intentionally limited in scope and not future-proof.
2.4 ISO 15118 – Communication as an Ecosystem
ISO 15118 transformed charging from a transaction into an ecosystem by introducing:
- Cryptographic identity
- Bidirectional energy concepts
- Smart grid integration
- Automated billing (Plug-and-Charge)
Chapter 3: Conceptual Role of EVCC Inside the Vehicle
3.1 EVCC vs VCU vs BMS
| Subsystem | Primary Responsibility | Interaction with Charging |
|---|---|---|
| EVCC | External communication & protocol handling | Direct |
| VCU | Vehicle-level coordination | Indirect |
| BMS | Battery protection & limits | Data provider |
3.2 Functional Boundary of EVCC
The EVCC does not directly control power electronics. Instead, it:
- Receives battery constraints from BMS
- Negotiates parameters with EVSE
- Authorizes charging sequences
- Reports status and faults
3.3 EVCC as a Cyber-Physical Gateway
The EVCC bridges:
- High-voltage electrical systems
- Low-voltage digital networks
- External public infrastructure
This makes it one of the most safety- and security-critical controllers in an EV.
Chapter 4: Why EVCC Matters for OEMs and Academia
4.1 OEM Perspective
- Interoperability across global chargers
- Regulatory compliance
- Brand reputation and charging experience
4.2 Academic Perspective
- Real-world application of communication theory
- Cybersecurity in embedded systems
- System-of-systems engineering
4.3 Policy and Infrastructure Perspective
- Grid stability
- Energy transition
- Standardization and regulation
End of PART 1
PART 2 will introduce **deep descriptive theory** covering:
- Communication layers (physical → application)
- PLC signaling explained intuitively
- State machines and charging phases
- Timing, retries, and fault handling
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