Force Measurement Current Control Using H-Bridge Inductor Switching
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Solution Overview
Problem
Existing force measuring devices face challenges in achieving accurate measurements due to rapid magnetic compensation and temperature variations, often requiring complex arrangements and additional coils to maintain precision.
Innovation Solution
A force measuring device with a current control circuit that dynamically switches between two conduction directions of a single inductor, using a H-bridge circuit and MOSFET switches to control current flow, allowing for fixed current magnitude and reduced temperature sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If rapid magnetic compensation is used to achieve quick equilibrium, then measurement speed is improved, but temperature variations increase causing measurement inaccuracy
Solution Approach 1:
The patent applies periodic action by implementing a switching circuit that alternates current flow through the inductor in discrete time intervals (first time interval and second time interval within each cycle). This periodic switching allows the system to achieve rapid equilibrium while controlling temperature variations through duty cycle adjustment, resolving the contradiction between measurement speed and temperature stability.
2Measurement precision
If complex arrangements with multiple coils are used to improve measurement accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the current control function into two distinct time intervals within each switching cycle: a first time interval where current flows in one direction, and a second time interval where current flows in the opposite direction. This temporal segmentation allows precise control of the magnetic field using a single inductor, achieving measurement accuracy without requiring multiple coils or complex spatial arrangements.
Solution Approach 2:
The patent implements dynamic control by varying the duty cycle (ratio of first time interval to total cycle time) based on the measured force. The control unit dynamically adjusts the switching parameters to maintain equilibrium, enabling accurate measurements with a single inductor instead of requiring static complex multi-coil arrangements.
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 with simplified circuitry, reduced temperature variations, and improved energy efficiency, enabling high resolution and stability in weighing systems.
Implementation Method 1
operates based on the principle of electromagnetic force compensation (also referred to as electromagnetic force restoration)
Implementation Method 2
controlling the current flowing through the inductor... involving a H-bridge circuit and MOSFET switches to control current flow
Data Source
AI summary
A force measuring device based on the principle of electromagnetic force-compensation is disclosed. The device includes an electronic circuit driven by direct current, which includes an inductor. A control unit of the device controls the current flowing through the inductor and thereby also the compensation force, where the controlling is responsive to the force to be measured. The device also includes a means for providing a measurement output indicative of the force to be measured. Controlling the current includes dynamic switching between two switch states associated with the two conduction directions of the inductor.