EV Charging Meter Voltage Sensing for Cable Loss Accounting
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Solution Overview
Problem
Existing electric meters for measuring electrical consumption in electric vehicles do not account for line losses in charging cables, and they lack the ability to assess the quality of electrical contacts and detect changes in line resistance over time.
Innovation Solution
An electric meter that measures voltage directly at the transfer point of the charging cable, allowing for accurate calculation of consumption by accounting for line losses, and enabling assessment of contact quality and detection of changes in line resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage is measured inside the electric meter before the charging cable, then the measurement setup is simple, but line losses in the charging cable are not accounted for and consumption calculation is inaccurate
Solution Approach 1:
The voltage measurement function is segmented into two separate measurement points: one inside the electric meter and one at the transfer point in the charging cable plug. This allows independent measurement of voltage at different locations in the circuit, enabling accurate accounting of line losses while maintaining modular system architecture.
Solution Approach 2:
The charging cable itself serves as an intermediary element that carries both power and measurement signals. By incorporating voltage measurement inputs directly into the plug at the transfer point, the system uses the existing cable infrastructure to deliver precise voltage data without requiring separate measurement devices.
2Reliability
If voltage is measured inside the electric meter, then the measurement system is simple, but contact quality at current connections cannot be assessed
Solution Approach 1:
The measurement system is segmented to include separate voltage measurement inputs at the plug's transfer point, allowing independent assessment of contact quality at each connection point. This enables monitoring of contact resistance and quality without complicating the overall measurement architecture.
Solution Approach 2:
The system implements feedback by continuously monitoring voltage at the transfer point and comparing it with expected values. Deviations indicate contact quality issues, providing real-time feedback on connection reliability and enabling preventive maintenance before failures occur.
3Measurement precision
If voltage is measured inside the electric meter, then the setup is straightforward, but changes in line resistance over time cannot be detected
Solution Approach 1:
The voltage measurement is segmented into multiple points along the power path (inside the meter and at the transfer point). By comparing voltage differences between these segmented measurement points while knowing the current, the system can calculate and track line resistance changes over time.
Solution Approach 2:
The system performs preliminary measurements of voltage and current at multiple points to establish baseline resistance values. These preliminary data collection actions enable future detection of resistance changes by comparing against the established baseline, allowing proactive identification of degradation trends.
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 solution provides accurate consumption billing by accounting for line losses, ensures reliable contact quality, and detects changes in line resistance, thereby improving the overall measurement accuracy and reliability.
Implementation Method 1
the current measuring device 11 can measure the charging current ILOAD, for example, by means of a low-ohmic current measuring resistance ('shunt')
Implementation Method 2
the voltage measuring device measures the electrical voltage directly at the transfer point of the charging cable
Data Source
AI summary
The invention relates to an electric meter (1) for measuring the electric consumption of an electric load (RLOAD), in particular while charging an electric vehicle. The electric meter according to the invention has a current measuring device (11) in order to measure a charging current (ILOAD) which flows through a charging cable (7) to a transfer point (9, 10) for the load (RLOAD), wherein the transfer point (9, 10) is preferably located in a plug (8) of the charging cable (7). Furthermore, the electric meter (1) according to the invention includes a voltage measuring device (12) for measuring a voltage. According to the invention, the voltage measuring device (12) measures the voltage directly at the transfer point (9, 10) of the charging cable (7) in order to determine line losses in the charging cable (7), in particular in order to take into consideration the line losses when calculating the consumption.