Power Conversion Circuit for Induction Heating
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Solution Overview
Problem
Existing power conversion circuits in image forming apparatuses face inefficiencies in heating the fixing roller, as they rely on traditional rectification and inversion methods that do not optimize energy transfer for varying input voltages and temperatures.
Innovation Solution
A power conversion circuit with a high frequency power conversion system that switches between full bridge and half bridge inverter modes based on detected voltage and temperature, using MOSFETs or intelligent power modules, to optimize energy transfer and heat generation in the induction heating load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional rectification and inversion methods are used, then the power conversion circuit can operate with simple structure, but the heating efficiency of the fixing roller deteriorates due to non-optimized energy transfer
Solution Approach 1:
The patent applies dynamics by switching between half-bridge and full-bridge inverter configurations based on detected temperature and voltage conditions. The control circuit dynamically selects the optimal inverter mode to maximize heating efficiency while adapting to changing operating conditions, thereby resolving the contradiction between energy efficiency and system complexity.
Solution Approach 2:
The patent changes operational parameters by adjusting the inverter configuration (half-bridge vs. full-bridge) and switching frequency based on detected temperature and input voltage levels. This parameter adaptation optimizes energy transfer efficiency for different operating conditions without requiring a completely different system architecture.
2Adaptability or versatility
If fixed inverter mode is used, then the circuit structure remains simple, but the adaptability to input voltage fluctuations and temperature changes deteriorates
Solution Approach 1:
The patent implements feedback control by detecting temperature in the heating element and input voltage levels, then using this information to automatically select the appropriate inverter configuration. This closed-loop feedback system enables the circuit to adapt to varying conditions while maintaining manageable complexity through automated decision-making based on sensor inputs.
Solution Approach 2:
The patent achieves universality by designing a single power conversion circuit that can operate in multiple modes (half-bridge and full-bridge) depending on conditions. This multi-functional approach allows the same hardware to adapt to different voltage levels and temperature requirements without requiring separate dedicated circuits for each operating condition.
3Speed
If high switching frequency is used, then the response speed improves, but the energy loss in switching elements increases
Solution Approach 1:
The patent dynamically adjusts switching frequency based on operating conditions. During transient states requiring fast response, higher frequencies are used. During steady-state operation, the frequency is reduced to minimize switching losses in the MOSFETs and other switching elements, thereby resolving the contradiction between response speed and energy 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 enables stable and efficient power transmission to the induction heating load, allowing for flexible operation modes that adapt to input voltage fluctuations and temperature changes, thereby ensuring consistent heating performance.
Implementation Method 1
generates a pulsated positive voltage by full-wave rectifying a commercial power input which is an AC power supply with a diode bridge
Implementation Method 2
generates high frequency current from the pulsated positive voltage with a half bridge inverter and a full bridge inverter
Implementation Method 3
the high frequency current flows to a coil to generate an induced current (eddy current) in a load by the magnetic field generated in the coil
Implementation Method 4
generate an induced current (eddy current) in a load by the magnetic field generated in the coil
Implementation Method 5
The fixing roller is heated to a high temperature by the heat generated in the load
Data Source
AI summary
A power conversion circuit encompasses a rectifying circuit, a first switching element, a second switching element, a third switching element, a fourth switching element, a series connection of a capacitor and an induction coil, a voltage detection section and a control circuit. The series connection of the capacitor and the induction coil is connected between a first connection point and a second connection point. The control circuit switches a mode between a first operation mode in which pulse signals are input to the first switching element to the fourth switching element and a second operation mode in which the pulse signals are input to the first switching element and the second switching element, the third switching element is turned off and the fourth switching element is turned on.