Method and apparatus for determining electric vehicle charging inlet terminal temperature
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Solution Overview
Problem
Existing methods for monitoring the temperature of electric vehicle charging inlet terminals using thermal sensors fail to account for temperature transient response, offset, or delay, which can lead to undetected thermal runaway events, especially with faulty charge couplers or high resistance connections.
Innovation Solution
A method that uses an electronic controller with temperature sensors to calculate the inlet terminal temperature by accounting for ambient temperature and time intervals, applying normalization factors derived from experimental measurements, and regulating power supply to maintain the temperature below a threshold, incorporating steps to determine and record temperature values, deltas, and fitting equations to model thermal resistance and time constants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal sensors are used to monitor inlet terminal temperature, then temperature monitoring capability is provided, but measurement precision deteriorates due to transient response, offset, and delay between sensor measurement and actual terminal temperature
Solution Approach 1:
The system performs preliminary actions by continuously monitoring the temperature gradient (rate of change) and using this information to predict future temperature conditions. The controller proactively adjusts power delivery before the actual temperature reaches dangerous levels, compensating for the sensor's transient response delay. This predictive approach allows the system to act on anticipated temperature conditions rather than waiting for the sensor to catch up.
Solution Approach 2:
The system implements a feedback mechanism where the temperature gradient measurement is continuously fed back to the controller, which then adjusts power delivery accordingly. The controller uses the rate of temperature change as feedback to modulate power levels, creating a closed-loop system that compensates for sensor lag. This dynamic feedback allows real-time adjustment despite the inherent delay between actual temperature and sensor reading.
2Device complexity
If fixed temperature threshold is used for shutdown, then simple control logic is achieved, but reliability deteriorates due to inability to detect thermal runaway events caused by sensor offset and delay
Solution Approach 1:
The system performs preliminary action by monitoring the temperature gradient and predicting thermal conditions before they reach the fixed threshold. By continuously assessing the rate of temperature change, the system can identify accelerating heating trends that precede thermal runaway events, enabling early intervention before the simple fixed threshold would trigger shutdown or fail to detect the problem.
Solution Approach 2:
The system introduces dynamics by transitioning from a static fixed-threshold approach to a dynamic gradient-based control strategy. The controller continuously adapts power delivery based on the real-time temperature gradient, allowing the control parameter to vary dynamically with thermal conditions. This dynamic approach maintains simplicity while significantly improving reliability by detecting thermal runaway through rate-of-change analysis rather than relying solely on absolute temperature values.
3Reliability
If thermal sensors are positioned near inlet terminals, then temperature monitoring coverage is improved, but measurement precision worsens due to exposure to ambient temperature variations and electrical interference
Solution Approach 1:
The system uses feedback by continuously measuring the temperature gradient and using this information to compensate for environmental interference. The gradient measurement provides feedback about the thermal state that is less susceptible to ambient variations, allowing the controller to distinguish between genuine heating from electrical resistance and temperature fluctuations from environmental sources.
Solution Approach 2:
The system changes parameters by shifting from monitoring absolute temperature values to monitoring the temperature gradient (rate of change). This parameter transformation makes the measurement less sensitive to ambient temperature variations and electrical interference, as these external factors typically cause slower, more gradual variations rather than rapid gradient changes. The gradient parameter effectively filters out low-frequency environmental noise.
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
Effectively prevents thermal runaway by accurately calculating and regulating the inlet terminal temperature, ensuring safe and efficient charging operations even with transient response or offset issues.
Implementation Method 1
The charging inlet may be configured to conduct alternating current (AC) direct current (DC) or a combination of the two. The thermal sensors are positioned in proximity to the inlet terminals that are being monitored
Data Source
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AI summary
An electric vehicle charging system (100) includes a temperature sensor (202) for measuring the temperature of an inlet terminal (204) of an electric vehicle charging inlet (100) and an electronic controller (206) configured to obtain an initial temperature value of the temperature sensor (202), obtain a current temperature value of the temperature sensor (202), calculate the inlet terminal temperature based on the initial temperature value, the current temperature value, a predetermined temperature sensor normalization factor, and a predetermined terminal normalization factor for the time after application of electrical power to the inlet terminal (204), and regulate the application of electrical power to the inlet terminal (204) to maintain the inlet terminal temperature below a predetermined temperature threshold based on the calculated inlet terminal temperature. A method (300) and a computer readable medium containing program instructions for determining an inlet terminal temperature of an electric vehicle charging inlet (100) are also disclosed.