Contactor Coil Voltage Control for Temperature-Compensated Closing
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Solution Overview
Problem
Electrical switching devices, particularly high-power contactors, face challenges in maintaining consistent switching behavior across varying temperatures due to changes in coil resistance, leading to increased mechanical stress and wear, and require robust and expensive designs or temperature sensors for compensation.
Innovation Solution
A method that applies a constant first voltage to the coil for a fixed time period to measure the current, determining a second voltage based on this measurement to ensure consistent armature movement and contact closure without the need for a temperature sensor, using a simple microcontroller and existing current measuring means.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a temperature sensor is added to detect coil temperature for compensation, then temperature compensation is achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent uses coil inductance as an intermediary parameter to indirectly detect temperature effects. Instead of directly measuring temperature with a sensor, the system measures inductance changes caused by temperature variations in the coil and armature assembly, then uses this information to adjust the drive voltage accordingly
Solution Approach 2:
The patent replaces the need for physical temperature sensors with an electrical measurement approach. By measuring coil inductance electrical properties and processing this data through a control unit, the system substitutes direct thermal measurement with indirect electrical characterization, eliminating additional hardware sensors
2Reliability
If the drive is designed to be more robust to handle temperature variations, then reliability improves, but weight and cost increase
Solution Approach 1:
The patent implements dynamic voltage adjustment based on real-time inductance measurements. The drive voltage is not fixed but is continuously adapted according to the measured inductance value, allowing the system to maintain reliable switching behavior across temperature ranges without requiring an oversized, heavy robust design
Solution Approach 2:
The system changes the drive voltage parameter dynamically in response to temperature-induced inductance changes. By adjusting the voltage parameter based on measured inductance, the system compensates for temperature effects without requiring a heavier, more robust mechanical design
3Reliability
If a higher voltage is applied to the coil at high temperatures to ensure contact closure, then switching reliability improves, but energy consumption increases
Solution Approach 1:
The patent implements a feedback control mechanism where the measured inductance value feeds back to the control unit, which then adjusts the drive voltage accordingly. This closed-loop feedback ensures that voltage is increased only when and where needed (at high temperatures indicated by high inductance), rather than applying high voltage continuously, thus reducing overall energy consumption while maintaining contact closure reliability
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 temperature compensation without increasing hardware complexity or cost, ensuring consistent switching behavior across a wide temperature range without extending the pickup process.
Implementation Method 1
The coil (2) is energized in order to close the contacts (14) of the electrical switching device (1). The armature (3) of the electromechanical drive is connected with a movable contact (6) of the electrical switching device (1).
Implementation Method 2
a measurement value is determined by means of measurement means (12) either as a current value (IMess) or as a time value (T1)
Data Source
AI summary
Disclosed is a method for closing the contacts of an electrical switching device during a switch-on process, whereinfor a fixed first time period, the first time period and the first voltage being selected in such a way that the armature is not set into motion during the first time period,or the first voltage is applied to the coil until a certain current value is reached, the first time period being the time period until said certain current value is reached, and the first voltage being selected in such a way that the armature is not set into motion during the first time period,wherein a suitable second voltage is defined, the second voltage being greater than the first voltage and being applied to the coil during a second time period in order to move the armature from the open position into the closed position.