PLC Charger Scheduling for EV DC Command Latency
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Solution Overview
Problem
Power line communication systems face challenges in efficiently scheduling data messages between electric vehicle chargers and vehicles, particularly in ensuring low latency for DC commands while maintaining reliable communication for utility messages, especially in environments with restricted bandwidth.
Innovation Solution
Implementing a PLC device with a processor and memory that assigns different priorities to data messages, halting utility message communication when DC messages are queued, and using specific modulation schemes to optimize channel occupancy, ensuring DC messages have higher priority and are communicated promptly over a narrow-band PLC channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If DC messages are given higher priority with preemptive access to the PLC channel, then latency for DC commands is reduced, but utility message communication reliability may deteriorate
Solution Approach 1:
The patent introduces a MAC layer as an intermediary between the application layer and the physical PLC channel. This MAC layer implements a scheduler that mediates access to the PLC channel, allowing DC messages to preempt utility messages while maintaining proper protocol handling and acknowledgment mechanisms. The MAC layer acts as a buffer and controller that ensures both message types are handled appropriately according to their priority levels.
Solution Approach 2:
The patent implements dynamic priority-based channel access where the PLC channel allocation is not fixed but changes based on message type and urgency. DC messages can dynamically preempt utility message transmissions when they arrive, and the system dynamically adjusts channel occupancy based on real-time communication needs. This dynamic approach allows the system to adapt channel usage to immediate requirements while maintaining overall communication reliability.
2Productivity
If utility messages use higher order modulation schemes to increase bitrate, then communication efficiency improves, but robustness and reliability deteriorate
Solution Approach 1:
The patent applies different modulation schemes to different message types based on their specific requirements. DC messages use robust lower-order modulation schemes (BPSK, QPSK) suitable for their time-critical but small-size nature, while utility messages use higher-order modulation schemes (16-QAM, 64-QAM) to maximize bitrate for their larger data volumes. This local optimization of modulation quality matches the communication characteristics to the message requirements.
Solution Approach 2:
The patent changes modulation parameters dynamically based on message priority and channel conditions. The system selects from multiple modulation schemes (BPSK, QPSK, 16-QAM, 64-QAM, 256-QAM) depending on the message type being transmitted. This parameter adjustment allows the system to optimize between bitrate and robustness for different communication scenarios.
3Loss of time
If DC messages preempt utility messages on the PLC channel, then DC command latency is reduced, but channel occupancy efficiency may worsen
Solution Approach 1:
The patent allows DC messages to partially preempt utility message transmissions rather than completely interrupting the communication stream. The MAC layer scheduler manages the preemption by allocating specific time slots and channel access opportunities, ensuring that while DC messages get priority access when needed, the overall channel is still efficiently utilized through structured slot allocation and minimized idle time.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables efficient scheduling that meets strict latency requirements for DC messages while maintaining reliable communication for utility messages, achieving nearly 10× bitrate performance compared to using power mains and adhering to round trip latency requirements.
Implementation Method 1
PLC modulates communication signals over existing power lines
Implementation Method 2
using specific modulation schemes to optimize channel occupancy
Data Source
AI summary
Systems and methods for establishing scheduling for charger and electric vehicle communication in a PLC system are described. In an illustrative embodiment, a method performed by a PLC device. In a further embodiment, the PLC device may be configured to operate according to a narrow-band PLC communication protocol. In a further embodiment, the narrow-band PLC communications between PLC devices in the charger and the electric vehicle are conducted over a pilot wire coupling the charger to the electric vehicle. In still a further embodiment, the pilot wire may be one of a standard set of existing wires in a standard cable used for connecting the charger to the electric vehicle.