Split DC Metering for Secure EV Charging Billing Accuracy
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Solution Overview
Problem
Current electrical vehicle charging stations lack accurate and reliable measurement of actual power consumption during charging, necessitating a solution that is easy to install, manufacture, and operate while ensuring energy billing integrity.
Innovation Solution
A DC meter system comprising a meter unit and a sensor unit connected via an interconnection cable, with the sensor unit measuring current and voltage on the DC power supply lines and transmitting encrypted data to the meter unit for precise power computation, featuring unique identification and tamper-proof security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a DC meter system with separate sensor unit and meter unit is implemented, then measurement accuracy and reliability are improved, but device complexity increases
Solution Approach 1:
The DC meter is divided into two separate functional units: a sensor unit that measures voltage and current on the power lines, and a meter unit that processes the measurements and handles user interaction. This segmentation allows the measurement function to be optimized independently while simplifying the main controller's burden, resolving the contradiction between measurement accuracy and system complexity.
2Reliability
If encryption modules and unique identification numbers are implemented, then reliability and protection against manipulation are improved, but device complexity increases
Solution Approach 1:
Unique identification numbers are pre-programmed into both the sensor unit and meter unit before deployment. This preliminary action ensures that only authenticated pairs can communicate, providing security without requiring complex runtime authentication protocols, thus balancing reliability with manageable complexity.
3Ease of operation
If the sensor unit is connected distally via interconnection cable, then ease of installation and flexibility are improved, but loss of information may increase due to signal transmission
Solution Approach 1:
The interconnection cable serves as an intermediary transmission medium between the sensor unit and meter unit. By designing this cable with appropriate shielding and signal conditioning, the system achieves both installation flexibility and signal integrity, resolving the contradiction between ease of installation and information loss.
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
The system provides accurate, reliable, and secure measurement of energy consumption, easy installation, and economical operation, ensuring accurate billing and protection against manipulation, while being robust against electromagnetic interference and thermal variations.
Implementation Method 1
The sensor unit further comprises a voltage sensor for coupling to each of the pair of power supply lines for measuring a voltage difference therebetween
Implementation Method 2
the sensor unit being coupled to one of the pair of DC power supply lines configured for measuring the current flowing through said power line
Implementation Method 3
the sensor unit further comprising a microprocessor with analog to digital convertors (ADC) for converting the received analog voltage measurement and current measurement signals to digital signals
Data Source
AI summary
A DC meter for an electrical vehicle charging station having a pair of DC power supply lines extending from a charging station controller to an electrical vehicle connector, the DC meter comprising a meter unit and a sensor unit. The meter unit comprises a user interface, a sensor interface for connection to the sensor unit, a metering interface for connection to the charging station controller, and a microprocessor configured to receive and process signals received from the sensor unit, to exchange data with the charging station controller and to receive commands from the user interface and output information to the user interface. The sensor unit is separate and connected at a point distal from the meter unit via an interconnection cable for the transmission of measurement signals.