Zero-Crossing Heating Power Circuit for Low-EMI Control
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Solution Overview
Problem
Conventional heating element power regulation methods in heating devices generate electromagnetic interference (EMI) and complicate electromagnetic compatibility (EMC) mitigation due to waveform chopping in silicon-controlled rectifiers.
Innovation Solution
A heating element power control circuit and method that uses a zero-crossing detection module, microcontroller, and switch control module to regulate power by controlling the conduction of complete waveforms during preset cycles, reducing EMI and simplifying EMC compliance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If silicon-controlled rectifier conduction phase angle control is used to adjust heating element power, then power regulation is achieved, but electromagnetic interference (EMI) is generated in the power supply
Solution Approach 1:
The patent employs periodic action by controlling the switch module to conduct complete AC waveforms in integer numbers during preset work cycles. The microcontroller generates control signals that enable the switch module to conduct 1, 2, 3, or 4 complete waveforms per work cycle, creating periodic on/off patterns that regulate power while maintaining waveform integrity and reducing EMI generation.
Solution Approach 2:
The patent applies preliminary action through the zero-crossing detection module that detects the zero-crossing point of the AC voltage signal before the control cycle begins. This preliminary detection allows the microcontroller to synchronize the control signal with the AC waveform start point, ensuring complete waveform conduction from the beginning of each cycle and preventing partial waveform switching that would generate EMI.
2Power
If silicon-controlled rectifier conduction phase angle control is used to adjust heating element power, then power regulation is achieved, but electromagnetic compatibility (EMC) mitigation becomes difficult
Solution Approach 1:
The patent extracts the problematic waveform chopping function from the control mechanism. Instead of using phase angle control that chops waveforms, the invention extracts only the necessary power regulation function by controlling the number of complete waveforms conducted during each work cycle. This separation eliminates the EMI-generating waveform chopping while preserving power adjustment capability, thereby simplifying EMC mitigation.
3Object-generated harmful factors
If complete waveform conduction control is used to reduce EMI, then electromagnetic compatibility is improved, but power control precision must be maintained
Solution Approach 1:
The patent applies dynamics by making the conduction time of the switch module variable and adjustable. The microcontroller dynamically changes the number of complete waveforms conducted during each work cycle based on the required heating power level. This dynamic control allows precise power adjustment through integer waveform counts while maintaining complete waveform conduction to minimize EMI, adapting to different heating requirements in real-time.
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
Reduces EMI generation and simplifies EMC compliance by controlling heating element power through the conduction of integer numbers of complete waveforms, enhancing electromagnetic compatibility in heating devices.
Implementation Method 1
The zero-crossing detection module is configured to detect a voltage signal and provide a zero-crossing signal to the microcontroller upon detecting a zero-crossing point of the voltage signal
Implementation Method 2
A third terminal of the switch module is connected to a first terminal of the heating element. The switch control module is configured to receive the control signal and control a conduction state and a conduction time of the switch module based on the control signal to further control power of the heating element
Data Source
AI summary
A heating element power control circuit and a control method using the same are provided. The heating element power control circuit includes a heating element power control circuit, including a zero-crossing detection module, a microcontroller, a switch control module, a switch module, and a heating element. A first terminal of the zero-crossing detection module is connected to a neutral line, a second terminal of the zero-crossing detection module is connected to a first terminal of the microcontroller, a third terminal of the zero-crossing detection module is connected to a live line. A second terminal of the microcontroller is connected to a first terminal of the switch control module. A second terminal of the switch control module is connected to a first terminal of the switch module, and second terminal of the switch module is connected to the live line.