Induction Heating Relay Snubber Circuit Noise Elimination
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Solution Overview
Problem
Induction heating devices face challenges in eliminating interference noise and ensuring continuous output operations when heating multiple containers, often requiring additional devices like LDVs and resulting in overheating of switching elements.
Innovation Solution
The induction heating device incorporates a resonance circuit with a working coil and resonance capacitor, an inverter for switching operations, snubber capacitors, a DC link capacitor, and a relay to connect snubber capacitors to the DC link or resonance capacitor, allowing for adjustable pulse widths and reduced interference noise without additional devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If amplitude modulation is used to eliminate interference noise, then interference noise is reduced, but device complexity increases due to additional devices like LDV
Solution Approach 1:
The patent extracts and eliminates the need for complex additional devices like LDV by using a simplified approach where the relay directly connects/disconnects the second snubber capacitor based on duty cycle thresholds, achieving noise elimination without external measurement devices
Solution Approach 2:
The system uses its own internal components (relay, snubber capacitors, inverter) to eliminate interference noise through self-monitoring of duty cycle and automatic switching, without requiring external LDV or other measurement devices
2Power
If turn on/turn off control is performed to provide low output, then output control is achieved, but continuous output operations cannot be performed
Solution Approach 1:
The patent implements dynamic output control by continuously adjusting the duty cycle of the inverter based on temperature feedback from the cooking vessel, allowing smooth transitions between different power levels without abrupt on/off switching, thereby enabling continuous output operations
Solution Approach 2:
The system incorporates temperature feedback from the cooking vessel to dynamically adjust the inverter duty cycle, creating a closed-loop control system that maintains continuous stable operation across a wide range of output power levels
3Object-affected harmful factors
If fixed frequency is used for all containers, then interference noise is reduced, but output range is limited
Solution Approach 1:
The patent implements dynamic duty cycle adjustment within a fixed frequency framework, allowing the system to adapt to different container sizes and cooking requirements by varying the on-time proportion while maintaining frequency consistency, thus achieving both noise reduction and wide output range
Solution Approach 2:
The system changes the duty cycle parameter dynamically while keeping frequency fixed, enabling flexible output control across a wide range of power levels without generating interference noise, thereby achieving both noise reduction and adaptability
4Adaptability or versatility
If duty is adjusted to satisfy wide range of outputs, then output flexibility is improved, but switching elements overheat
Solution Approach 1:
The patent introduces the relay as an intermediary component that selectively connects or disconnects the second snubber capacitor based on duty cycle thresholds, providing a protective mechanism that prevents switching elements from overheating while maintaining output flexibility
Solution Approach 2:
The system provides beforehand protection by monitoring duty cycle and preemptively switching the snubber capacitor configuration to protect switching elements from overheating before damage occurs, enabling sustained flexible output control
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 effectively reduces or eliminates interference noise, enables continuous output operations across a wide range of outputs, and prevents overheating of switching elements, improving user satisfaction and product performance.
Implementation Method 1
an object (e.g., a cooking container) itself may be heated by eddy currents that are generated in the object made of metallic ingredients, using a magnetic field generated around a coil when a predetermined magnitude of high-frequency power is supplied to the coil
Implementation Method 2
heated by eddy currents that are generated in the object made of metallic ingredients
Implementation Method 3
an inverter configured to perform a switching operation to thereby supply a resonance current to the working coil
Implementation Method 4
a plurality of snubber capacitors electrically connected to the inverter, a direct current (DC) link capacitor electrically connected to the inverter
Data Source
AI summary
An induction heating device includes a working coil and a resonance capacitor, an inverter that performs a switching operation to supply a resonance current to the working coil, a plurality of snubber capacitors electrically connected to the inverter, a direct current (DC) link capacitor electrically connected to the inverter, and a relay configured to electrically connect one of the plurality of snubber capacitors to the DC link capacitor or the resonance.