Integral Half Cycle Control for AC Power Flicker Reduction
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Solution Overview
Problem
Heating elements in electrical devices, such as printers and copiers, face challenges with AC power causing undesirable flicker and harmonics, which violate regulations due to the generation of sub-harmonics and AC harmonics.
Innovation Solution
The use of triacs and trigger signals for phase control and integral half-cycle control to manage power delivery, selectively allowing or blocking half-cycles of the AC signal, thereby minimizing flicker and harmonics by balancing half-cycles and adjusting their frequency to be outside the human-sensitive range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If AC power is used to heat elements, then efficient heat generation is achieved, but flicker and harmonics are generated that violate regulations
Solution Approach 1:
The patent applies periodic action by using integral half-cycle control, where complete half-cycles of the AC waveform are applied in a periodic manner. This maintains the efficiency of resistive heating while controlling the frequency and pattern of power delivery to minimize flicker and harmonic generation, directly addressing the contradiction between efficient heat generation and harmful electromagnetic effects
Solution Approach 2:
The patent changes the parameters of power delivery by adjusting the frequency and pattern of half-cycle application. By modifying these parameters, the system maintains effective heating while pushing the operational frequency outside the human-sensitive range (below 5 Hz or above 15 Hz), thereby reducing flicker perception and harmonics without sacrificing heating efficiency
2Power
If phase control is used to manage power delivery, then power levels are adjusted, but sub-harmonics and flicker are generated
Solution Approach 1:
The patent replaces traditional phase control with periodic integral half-cycle control, where complete half-cycles are applied periodically rather than using phase-angle trimming. This approach maintains power control capability while avoiding the sub-harmonics and flicker associated with phase control, as the periodic application of full half-cycles creates a more regular waveform pattern
Solution Approach 2:
The patent segments the AC waveform into discrete half-cycles and selectively applies them in integral units. This segmentation allows for precise control of power delivery by controlling the number and frequency of half-cycle applications, while maintaining waveform integrity to reduce harmful harmonics and sub-harmonics
3Object-generated harmful factors
If half-cycles are selectively removed to reduce flicker, then harmonics are minimized, but power delivery efficiency may be reduced
Solution Approach 1:
The patent optimizes the balance between harm reduction and power efficiency by carefully controlling the frequency and pattern of half-cycle application. By adjusting these parameters, the system achieves effective flicker and harmonic reduction while maintaining sufficient power delivery for heating applications, resolving the contradiction through parameter optimization
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 approach effectively reduces flicker and harmonics in the power grid, ensuring compliance with regulations and maintaining efficient heat generation for applications like toner fusion in printers.
Implementation Method 1
Heating elements and devices typically use an alternating current (AC) electrical signal as the energy source, and may use resistive elements to convert electrical energy to heat
Data Source
AI summary
Power to an electrical device is controlled using a phase control that changes a cutoff phase of an alternating current (AC) electrical signal delivered to the electrical device. The power delivered to the electrical device is increased to an operational level using the phase control. A level of the power delivered to the electrical device is maintained at the operational level using an integral half cycle control that selectively removes a plurality of half cycles from the AC electrical signal delivered to the electrical device such that a plurality of remaining half cycles in the AC electrical signal delivered to the electrical device have a frequency outside a range of sub-harmonic frequencies.