Contactor Thermal Monitoring Using External Temperature Sensors
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Solution Overview
Problem
Contactors in electric vehicles face overheating issues due to high electrical currents, which can damage components, and installing temperature sensors inside the contactor is structurally challenging and costly, necessitating a more accurate and efficient method to prevent overheating.
Innovation Solution
A contactor arrangement with external temperature sensors and a control unit that computes internal temperature using external and ambient temperature readings, along with optional air pressure and current sensors, to predict and manage thermal stress accurately, avoiding damage by derating the contactor when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature sensor is installed inside the contactor in direct vicinity of the contact bridge, then measurement precision of internal temperature is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent introduces external temperature sensors as intermediary devices that measure temperature outside the contactor housing. These sensors indirectly monitor the thermal state of internal components through thermal coupling via the housing, eliminating the need to install sensors inside the contactor while still providing sufficient temperature monitoring capability.
Solution Approach 2:
The patent creates a thermal model that copies the internal temperature behavior based on external temperature measurements. By measuring external temperatures at multiple points and using thermal resistance networks, the system reconstructs the internal temperature field without physical sensors inside the contactor, achieving accurate monitoring through virtual copying.
2Reliability
If a temperature sensor is installed inside the contactor, then reliability for preventing overheating is improved, but manufacturing cost increases
Solution Approach 1:
The patent uses external temperature sensors and thermal modeling as an intermediary approach to achieve reliable overheating prevention. The external sensors combined with computational thermal models provide sufficient reliability for derating decisions without the added cost and complexity of internal sensor installation.
Solution Approach 2:
The patent replaces the mechanical approach of installing physical sensors inside the contactor with a computational approach. By using external sensor data combined with thermal resistance network calculations and control algorithms, the system achieves the same reliability function at lower manufacturing cost.
3Reliability
If large safety margins are applied to prevent overheating, then reliability is improved, but productivity and performance are reduced
Solution Approach 1:
The patent implements a feedback control system that continuously monitors external temperatures, computes internal temperatures in real-time, and dynamically adjusts the contactor's current carrying capacity. This allows the system to operate close to maximum temperature limits when conditions permit while maintaining reliability, eliminating the need for conservative fixed safety margins.
Solution Approach 2:
The patent transitions from static safety margins to dynamic derating based on real-time thermal conditions. The control unit continuously updates the allowable current rating based on computed internal temperatures, environmental conditions, and thermal models, allowing the contactor to operate at optimal performance levels while maintaining safety.
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
Enables safe operation close to the maximum operating temperature without performance loss, reducing the need for large safety margins and preventing thermal damage by accurately predicting internal temperatures.
Implementation Method 1
a first temperature sensor in direct contact with the first terminal or with a bus bar that is electrically connected to the first terminal
Implementation Method 2
The movable contact element can be moved by applying a force, such as a mechanical force or an electromagnetic force. For example, the contactor comprises a driver coil that switches the movable contact element by a magnetic force, if an electric current flows through the driver coil.
Implementation Method 3
heat is generated due to an electrical contact resistance between the movable and fixed contact elements
Data Source
AI summary
A contactor arrangement is specified herein, comprising:a contactor with a contact bridge for switching an electrical connection between a first terminal and a second terminal during operation,a first temperature sensor in direct contact with the first terminal or with a bus bar that is electrically connected to the first terminal,a second temperature sensor configured for measuring an ambient temperature outside of the contactor during operation, anda control unit configured for computing an internal temperature of the contact bridge inside the contactor, whereinthe internal temperature depends on temperature readings of the first temperature sensor and the second temperature sensor, andthe control unit is configured to provide a warning signal if the internal temperature exceeds a threshold value.Further, a method for operating a contactor arrangement is specified herein.