Induction Heating Switching Element Voltage Control
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Solution Overview
Problem
Induction heating devices with a single switching element or IGBT and a parallel resonant circuit face reliability and service life issues under unfavorable operating conditions, particularly when using unsuitable cooking utensils.
Innovation Solution
A method that controls a controllable switching element to manage oscillations in a parallel resonant circuit, determining low points in the oscillation cycle to switch on only when necessary, preventing excessive voltage and current peaks, and using saucepan detection by counting oscillation cycles to determine the presence of a cooking vessel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single switching element or IGBT is used in the frequency converter, then cost is reduced, but reliability and service life are compromised under unfavorable operating conditions
Solution Approach 1:
The control device determines the low point voltage of the oscillation cycle before switching on the switching element. By performing this preliminary voltage assessment, the system ensures that the switching element is only activated when the voltage is within safe limits, preventing overload conditions that would compromise reliability and service life while still using a cost-effective single switching element configuration
Solution Approach 2:
The control device continuously monitors the low point voltage of the oscillation cycle and uses this feedback information to determine when to switch on the switching element. This feedback mechanism ensures that the switching element operates only under favorable voltage conditions, protecting against overload and extending service life while maintaining the economical single-switching-element design
2Productivity
If the switching element is switched on continuously, then heating efficiency is improved, but component wear increases and service life decreases
Solution Approach 1:
The switching element is activated periodically at specific moments in the oscillation cycle - specifically at the low points - rather than continuously. This periodic switching maintains heating efficiency by delivering energy at optimal moments while significantly reducing cumulative wear on the switching element, thereby extending its service life
Solution Approach 2:
By switching on the switching element at each low point of the oscillation cycle, the system maintains continuous useful heating action throughout the oscillation periods. The heating process remains effective and uninterrupted in terms of thermal output, while the switching element experiences reduced stress compared to continuous conduction mode, extending its operational lifespan
3Reliability
If a half-bridge circuit with two IGBTs is used, then reliability is improved, but cost increases
Solution Approach 1:
The invention extracts and removes one IGBT from the traditional half-bridge circuit, leaving only a single switching element. By combining this single switching element with the parallel resonant circuit and implementing low point voltage control, the system achieves reliable operation without the need for the second IGBT, thereby reducing cost while maintaining component protection
Solution Approach 2:
The invention changes the operating parameters and circuit configuration from a traditional half-bridge with two IGBTs to a single-switching-element configuration with parallel resonant circuit. By controlling the switching timing based on low point voltage detection, the system achieves reliable operation with fewer components, reducing cost while maintaining adequate component protection through intelligent control
4Measurement precision
If saucepan detection is implemented by monitoring oscillation cycles, then detection accuracy is improved, but system complexity increases
Solution Approach 1:
The existing control device that monitors low point voltage for switching control is made multi-functional by also using it for saucepan detection. By counting oscillation cycles using the same control logic already present in the system, the invention achieves accurate saucepan detection without adding separate dedicated detection hardware, thereby maintaining simplicity while improving measurement precision
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 ensures reliable, component-protecting operation with a longer service life for induction heating devices by minimizing wear on components and accurately detecting cooking vessels during heating operations.
Implementation Method 1
induction coil associated with a given hotplate and which are subject to the action of an alternating voltage or alternating current, so that eddy currents are induced in a cooking utensil to be heated
Implementation Method 2
eddy currents are induced in a cooking utensil to be heated which are magnetically coupled with the induction coil. The eddy currents bring about a heating of the cooking utensil
Implementation Method 3
induction heating device
Implementation Method 4
induction coil and a capacitor forming a parallel resonant circuit... an oscillation of the parallel resonant circuit is caused during a heating operation
Data Source
AI summary
The invention may enable provision of a method for facilitating operation of an induction heating device, and a pot detection method for an induction heating device and to an induction heating device. The induction heating device is characterized by determining a low point of a resonant cycle on a linking node of a parallel resonant circuit and a switching element, determining a low point voltage at the low point of the resonant cycle and switching on the switching element at the low point of the resonant cycle for a cycle duration that is determined depending on the low point voltage in such a manner that a low point voltage does not exceed a predetermined maximum value in the following resonant cycles.