Synchronization Circuit for Dual Induction Coil Heating Zones
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Solution Overview
Problem
Existing induction heating cooktops with multiple induction coils face synchronization issues, leading to interference between magnetic fields when power is supplied in a non-synchronized manner, requiring complex and costly microcontrollers to generate multiple phased PWM gate drive signals.
Innovation Solution
A cost-efficient power circuit using a single microcontroller to drive high-frequency switching elements, where inner and outer ring IGBTs and gate drive circuits are connected through a diode to ensure synchronous operation of the induction coils, eliminating the need for expensive microcontrollers to generate complex PWM signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single microcontroller is used to drive high-frequency switching elements for two induction coils, then cost is reduced, but synchronization of magnetic fields becomes difficult to achieve
Solution Approach 1:
A diode is introduced as an intermediary component between the microcontroller output pins and the IGBT gate drive circuits. The diode synchronizes the switching of inner and outer ring IGBTs by allowing current flow in only one direction, ensuring that both induction coils are powered simultaneously when the diode is forward-biased, thus maintaining magnetic field synchronization while using a single microcontroller.
2Reliability
If complex phased PWM gate drive signals are generated to synchronize coils, then magnetic field interference is avoided, but device complexity and cost increase
Solution Approach 1:
The control signals for inner and outer ring IGBTs are merged through a common diode connection. Instead of using separate complex phased PWM signals from a sophisticated microcontroller, the invention combines the control paths by connecting both IGBT gate drives to microcontroller output pins through a shared diode, simplifying the circuit while maintaining synchronous operation.
3Device complexity
If induction coils are powered in a non-synchronized manner, then circuit design is simpler, but magnetic fields cancel each other out causing energy loss
Solution Approach 1:
The invention implements periodic synchronous switching of both induction coils through the diode-controlled IGBT gate drive circuits. The microcontroller generates periodic PWM signals that, when passed through the diode, simultaneously switch both inner and outer ring IGBTs, ensuring that both coils are energized in synchrony during each switching cycle, preventing magnetic field cancellation and maximizing energy transfer efficiency.
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 solution allows for simultaneous and synchronized powering of concentrically disposed induction coils, enhancing energy transfer efficiency and reducing costs by avoiding the complexity of high-cost microcontrollers, while maintaining effective power control and adjustment based on pan size and power level.
Implementation Method 1
high-frequency alternating current is passed through a coil upon which a magnetic field of the same frequency is induced
Implementation Method 2
The two output pins of the microcontroller are connected through a diode such that the inner and outer ring induction coils are powered in a synchronous manner when said diode is forward-biased
Implementation Method 3
a high-frequency power switch such as an IGBT is accordingly used. A resonant converter in an induction heater circuit topology typically consists of a capacitor, an inductor and resistance
Implementation Method 4
The internal resistance of the pan causes heat dissipation due to Joule effect
Implementation Method 5
Resonance therefore occurs while the inductor and the capacitor involve in energy exchange
Data Source
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AI summary
The present invention relates to an induction heating cooktop (1) with at least one double-coil heater (3) having concentrically disposed induction coils in the form of inner and outer ring induction coils (9, 10) and a power circuit (4) for powering said double-coil heater (3), said power circuit (4) comprising a rectifier (12) rectifying the alternating signal, a filter circuit (F1, F2) and an inverter stage (S1, S2) associated with said inner and outer ring induction coils (9, 10), each inverter stage (S1, S2) comprising a respective inner and outer ring switching device (7, 8) in parallel with a reverse-biased freewheeling diode.