Inductive Welding Circuit Phase Shift Temperature Monitoring
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Solution Overview
Problem
Existing inductive heating circuits for welding thermoplastic materials face challenges in temperature monitoring and control, particularly in avoiding the use of electrically conductive cables, which can create disturbance zones and are impractical for mounting temperature sensors in the welding region.
Innovation Solution
A circuit that operates the load impedance at resonant frequency, measuring and logging the phase shift between exciter current and voltage to calculate temperature progression, utilizing the temperature-dependent resistance of the metal to be heated, allowing for contactless indirect temperature measurement and monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature sensor is provided in the welding region for monitoring, then temperature monitoring capability is improved, but mounting complexity and disturbance zones increase
Solution Approach 1:
The patent replaces mechanical/physical temperature sensors with an electrical measurement system. Temperature is determined indirectly by measuring the phase shift between exciter current and voltage, which changes with temperature-dependent resistance of the metal. This substitution eliminates the need for physical sensors in the welding region, avoiding mounting complexity and disturbance zones while maintaining measurement capability
Solution Approach 2:
The patent introduces an intermediary measurement approach where the phase shift between current and voltage serves as an intermediate parameter that correlates with temperature. Instead of directly measuring temperature with a sensor, the system measures the phase shift (which is affected by temperature-dependent resistance) and uses this as a proxy for temperature determination, thereby avoiding direct sensor placement in the welding region
2Power
If electrically conductive cables are used for supplying welding energy, then power transmission is improved, but disturbance zones and mounting difficulty increase
Solution Approach 1:
The patent replaces electrical cable transmission with electromagnetic field-based energy transmission through inductive heating. The transformer generates an alternating magnetic field that induces eddy currents in the metal, transmitting welding energy without physical cable contact. This eliminates disturbance zones at cable transition points while maintaining effective power delivery to the welding region
3Measurement precision
If direct temperature measurement with sensors is implemented, then temperature control accuracy is improved, but the risk of disturbance zones and mounting issues increases
Solution Approach 1:
The patent substitutes direct temperature sensing with indirect temperature determination through phase shift measurement. The phase shift between exciter current and voltage provides a reliable temperature indicator without requiring physical sensors in the welding region, thereby maintaining temperature control accuracy while eliminating mounting issues and improving welding security by avoiding disturbance zones
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 precise temperature monitoring and logging of the welding seam without direct electrical contact, ensuring secure welding and accurate determination of the melting point, with improved precision in temperature measurement and reduced risk of disturbance zones.
Implementation Method 1
a transformer, which induces eddy currents in the metal as a function of an exciter current and an exciter voltage
Implementation Method 2
induces eddy currents in the metal... via which the plate ring is heated
Implementation Method 3
a temperature progression, which is proportional to the phase shift, is calculated from the exciter current, the exciter voltage and the phase shift
Data Source
AI summary
An inductive welding device includes a circuit for the inductive heating of a metal that is embedded in a non-magnetic bed. A transformer induces eddy currents in the metal as a function of an exciter current and an exciter voltage and forms a load impedance together with the metal to be heated. Temperature monitoring is provided for the metal to be heated. The load impedance is operated in the region of the resonant frequency of the load impedance. The exciter current and exciter voltage and their phase shift relative to each other are measured and logged when the metal is heated. A temperature progression which is proportional to the phase shift is calculated from the exciter current, exciter voltage, and phase shift.