Force Measuring Coil Circuit with Bidirectional Current Switching
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Solution Overview
Problem
Existing force measuring devices, particularly balances using electromagnetic force compensation, face challenges in achieving accurate measurements due to rapid equilibrium adjustments and temperature variations caused by varying current intensities, necessitating complex arrangements and corrective networks.
Innovation Solution
A force measuring device with a current control circuit that dynamically switches between two conduction directions of a single inductor, using a control unit to adjust the switching times based on the force to be measured, allowing for a simple and efficient electromagnetic force compensation mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If current intensity is varied to control the induction force, then the compensation force can be adjusted, but temperature variations occur causing measurement inaccuracies
Solution Approach 1:
The patent applies periodic action by switching the current through the induction device in alternating directions at a high frequency (e.g., 100 Hz or higher). This periodic switching creates a time-averaged magnetic field that provides the necessary compensation force while preventing temperature variations, as the rapid alternation prevents significant heat buildup in any single direction.
Solution Approach 2:
The patent changes the parameter of current direction (polarity) while maintaining constant current magnitude. By switching between positive and negative current directions at a fixed amplitude, the system achieves force control through directional alternation rather than magnitude variation, thereby eliminating temperature-driven measurement errors while preserving compensation effectiveness.
2Measurement precision
If complex corrective networks are added to control temperature variations, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates the need for complex corrective networks by fundamentally changing the control approach. Instead of adding temperature compensation circuits or corrective networks to fix temperature variations, the invention removes the root cause by using constant magnitude alternating current, thereby achieving high measurement accuracy with simpler device architecture.
Solution Approach 2:
The patent replaces the mechanical/thermal control approach (corrective networks for temperature compensation) with an electrical control approach (alternating current switching). This substitution eliminates the need for complex thermal management circuits while achieving the same goal of temperature-stable measurements.
3Speed
If rapid equilibrium adjustment is used, then measurement response time improves, but physical motion of parts occurs causing instability
Solution Approach 1:
The patent uses periodic action at a frequency high enough (e.g., 100 Hz or higher) that the physical parts cannot follow the rapid oscillations. The time-averaged effect of the alternating current provides stable equilibrium while the high frequency ensures rapid response to changes in measured force, effectively decoupling response speed from physical instability.
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 force measurements by maintaining a constant current magnitude, reducing temperature variations, and enhancing energy efficiency while maintaining a stable equilibrium, suitable for both stationary and dynamic weighing applications.
Implementation Method 1
a force measuring device, in particular a balance, which operates based on the principle of electromagnetic force compensation (also referred to as electromagnetic force restoration)
Implementation Method 2
this force acts repulsively on a fixed magnet resulting in a motion of components in the device, which ultimately leads to an adjustment of the generated compensation force
Data Source
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AI summary
The present invention refers to a force measuring device, based on the principle of electromagnetic force-compensation, comprising an electronic circuit driven by direct current including an inductor, in particular a coil, a control unit controlling the current flowing through the inductor and thereby also the compensation force, the controlling being responsive to the force to be measured, and means for providing a measurement output indicative of the force to be measured. According to the invention controlling the current involves dynamic switching between two switch states associated with the two conduction directions of the inductor.