Heating Apparatus Current-Feed Control for Harmonic Reduction
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Solution Overview
Problem
Conventional heating apparatuses face challenges in maintaining control accuracy of heating temperature while effectively restraining harmonic current, as stringent harmonic current standards demand improved methods beyond simple on/off current feeding techniques.
Innovation Solution
A heating apparatus with a current-feed switching circuit, temperature detector, and controller that performs ON lock and OFF lock current-feed control to maintain a predetermined current-feed ratio, reducing harmonic current occurrence while maintaining temperature control accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If simple on/off current feeding technique is used to restrain harmonic current, then harmonic current is reduced, but temperature control accuracy deteriorates
Solution Approach 1:
The patent applies periodic action by dividing the current feeding control into distinct periods: a first period where current is fed at a first ratio and a second period where current is fed at a second ratio. This periodic switching allows the system to restrain harmonic current by avoiding continuous on/off switching while maintaining temperature control accuracy through controlled periodic variation in current feeding ratios.
Solution Approach 2:
The patent employs dynamics by making the current feeding ratio variable rather than fixed. The current feeding ratio is dynamically adjusted between a first ratio during the first period and a second ratio during the second period, allowing the system to adapt to different operating conditions and maintain optimal temperature control while restraining harmonic current.
2Measurement precision
If current feed ratio is continuously adjusted for precise temperature control, then temperature control accuracy is improved, but harmonic current increases
Solution Approach 1:
The patent resolves this contradiction by implementing periodic action with two distinct current feeding ratios. Instead of continuous adjustment that generates harmonic current, the system switches between a first current feeding ratio during the first period and a second current feeding ratio during the second period. This periodic switching pattern restrains harmonic current while the controlled variation maintains temperature control accuracy.
Solution Approach 2:
The patent applies parameter changes by modifying the current feeding ratio parameter in a controlled manner. The system changes the current feeding ratio between two specific values (first ratio and second ratio) at different periods, rather than continuous adjustment. This discrete parameter change approach maintains temperature control while reducing harmonic current generation.
3Speed
If current feed is switched frequently to maintain temperature, then temperature responsiveness is improved, but harmonic current occurrence increases
Solution Approach 1:
The patent applies periodic action by establishing a regular pattern of switching between first and second current feeding ratios across multiple periods. This periodic switching provides temperature responsiveness through controlled changes while restraining harmonic current by avoiding frequent, irregular on/off switching. The harmonic current is reduced because the switching follows a predictable periodic pattern rather than frequent random transitions.
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
The solution effectively suppresses harmonic current occurrence while maintaining precise temperature control, ensuring the heating apparatus operates within target temperature ranges and adheres to stringent harmonic current standards.
Implementation Method 1
A heating apparatus switches turning-on/off of the current feeding from an AC power source to a heater
Data Source
AI summary
A heating apparatus includes a heater, a current-feed switching circuit configured to switch turning-on/off of current-feeding from an AC power source to the heater, thereby feeding current from the AC power source to the heater at a predetermined current-feed ratio, a temperature detector configured to detect a heating temperature of the heater, anda current-feed controller configured to control the current-feed ratio of the current-feed switching circuit such that the detection temperature of the temperature detector falls within a target range. The current-feed controller performs at least one pair of ON lock current-feed control to fix the current-feed ratio to almost 100% in a first period and OFF lock current-feed control to fix the current-feed ratio to almost 0% in a second period every predetermined control period of the current-feed switching circuit.