Resonant Load Power Conversion Device Switch Group Circuit
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Solution Overview
Problem
Existing resonant load power conversion devices face challenges in reducing switching frequency and minimizing the number of main circuit conductors, leading to increased costs and impedance variations, which affect the efficiency and reliability of induction heating applications.
Innovation Solution
The device employs switch group circuits with series and parallel connections of switching elements, along with a time division operation method to control the switching elements, reducing the switching frequency and the number of main circuit conductors, thereby minimizing impedance variations and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the switching frequency is increased to meet high-frequency voltage requirements for electro-resistance welding, then the induction heating performance is improved, but the switching element cannot respond due to its upper limit drive frequency
Solution Approach 1:
The patent divides the single-phase inverter into multiple sections (N-parallel connection) where each section operates at a lower switching frequency (1/N period). This segmentation allows the overall system to achieve high output frequency while each individual switching element operates within its reliable drive frequency range.
2Speed
If N-parallel connection of single-phase inverter is implemented to decrease switching frequency, then the drive frequency of switching element is reduced, but the number of main circuit conductors increases proportionally
Solution Approach 1:
The patent merges multiple switching elements (M series, N parallel) into integrated switch group circuits. This consolidation reduces the total number of main circuit conductors compared to traditional N-parallel connection, while maintaining the reduced switching frequency benefit.
3Speed
If the number of parallel-connected switching elements is increased to decrease switching frequency, then the drive frequency is reduced, but the cost and arrangement space of main circuit conductors increase
Solution Approach 1:
The patent combines M switching elements in series and N switching elements in parallel within integrated switch group circuits. This merging approach reduces the number of external main circuit conductors required, lowering both manufacturing cost and arrangement space compared to discrete parallel connections.
4Speed
If traditional N-parallel connection is used to reduce switching frequency, then the drive frequency is reduced, but impedance variations increase due to differences in route length
Solution Approach 1:
The patent integrates multiple switching elements into compact switch group circuits with standardized connection patterns. This merging reduces variations in route length between conductors, thereby minimizing impedance variations and improving system stability.
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 configuration decreases the switching frequency and reduces the number of main circuit conductors, enhancing efficiency, reducing costs, and minimizing impedance variations, thus improving the reliability and performance of resonant load power conversion devices for induction heating.
Implementation Method 1
By performing ON/OFF control of each switching element of this single-phase inverter, the AC-DC conversion device 10 outputs a rectangular wave voltage of resonance frequency
Implementation Method 2
an alternating current generated by the ON/OFF control of each switching element of the single-phase inverter flows in an LC resonance circuit formed by a coil and a capacitor, an eddy current flows in a heating part (an electric conductor) by an alternating field, which is generated by the flow of the alternating current
Implementation Method 3
the LC resonance circuit is heated from an inside of the LC resonance circuit by Joule heat generated by the flow of the eddy current
Implementation Method 4
the higher the frequency is, the more the depth of penetration of current is decreased. Since an electro-resistance-welded tube joint (a joint of a tube is connected by electric resistance welding for forming the tube) is performed by surface quenching (surface hardening), the resonant load AC-DC conversion device used for the induction heating is required to be able to output high frequency voltage
Data Source
AI summary
Present invention provides resonant load power conversion device capable of decreasing switching frequency of each switching element and reducing the number of main circuit conductors. Resonant load power conversion device has single-phase inverter whose DC input side (Vdc) is connected to DC voltage source and whose output side (Vout) is connected to resonant load and which outputs rectangular wave voltage at resonance frequency. Resonant load power conversion device includes switch group circuits 100U, 100V, 100X, 100Y connected to respective upper and lower arms of input and output sides of single-phase inverter and configured so that N (N=integer of 2 or more) series bodies each having 2 switching elements are connected parallel by main circuit conductors, and controller switching each switching element (U11 to U32, V11 to V32, X11 to X32, Y11 to Y32) of switch group circuits 100U, 100V, 100X, 100Y by time division of 1/(M×N).