Dynamic Resistive Load Switching for Power Factor Correction
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Solution Overview
Problem
Existing methods for improving power factor in AC power systems are either costly, complex, or inefficient, as they often require significant system modifications and increased peak currents to compensate for circulating currents caused by phase delayed loads, which reduce the capacity of AC power systems.
Innovation Solution
An apparatus and method that determine the portions of the power cycle where the input current exceeds a threshold and couple a substantially resistive load to the low power factor load during different portions of the cycle, aligning the current waveform with the voltage waveform to reduce phase delay and improve power factor without increasing peak currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitance is added to the line to adjust away inductive phase delay, then power factor is improved for a specific inductive load, but the solution is only effective for one specific load and lacks adaptability
Solution Approach 1:
The patent employs a dynamic switching mechanism that connects or disconnects resistive loads based on real-time detection of power cycle phases and current thresholds. This dynamic adaptation allows the system to adjust to varying load conditions automatically, resolving the contradiction between maintaining reliable power factor correction and adapting to different load types without fixed capacitance values.
Solution Approach 2:
The system changes operational parameters by switching resistive loads on and off during different portions of power cycles based on detected current thresholds. This parameter modulation enables the system to maintain improved power factor across varying load conditions rather than being fixed for a single load type.
2Power
If a large LC circuit is used to provide resonance at 60 Hz, then additional power reservoir is provided when needed due to poor power factor, but the system size is substantially increased and efficiency is significantly reduced
Solution Approach 1:
Instead of using a single large LC circuit, the patent segments the power correction function into multiple smaller resistive loads that are switched independently during different portions of power cycles. This segmentation provides the necessary power reservoir capacity through temporal distribution rather than spatial concentration, reducing overall system size while maintaining power support capability.
Solution Approach 2:
The system uses periodic switching of resistive loads during different phases of the power cycle to create a distributed power reservoir effect. By activating loads periodically during specific power cycle portions when current exceeds thresholds, the system accumulates power support capacity over time without requiring a large continuous energy storage device.
3Reliability
If AC input is converted to DC via a high power factor converter and subsequently converted back to AC near the load, then only the wiring between the converter and the load experiences the low power factor, but the approach is complex and not cost effective
Solution Approach 1:
The patent extracts the power factor correction function from complex AC-DC-AC conversion systems and implements it directly at the load level using simple resistive loads switched during specific power cycle portions. This extraction eliminates the need for expensive and complex dual-converter systems while maintaining power factor improvement benefits at the source of the problem.
Solution Approach 2:
The system uses simple, inexpensive resistive loads that are switched on and off during different power cycle portions rather than investing in expensive, complex conversion equipment. This approach trades the use of cheap, simple components for the avoidance of costly, complex systems, achieving cost-effective power factor correction.
4Ease of operation
If reverse phase dimmers are used to drive capacitive loads, then certain types of capacitive loads are better driven, but the device is not designed to improve power factor
Solution Approach 1:
The patent designs a universal power factor correction system that can be applied to both inductive and capacitive loads by switching resistive loads during specific power cycle portions. Unlike reverse phase dimmers that are specialized for capacitive loads, this system provides multi-functional power factor improvement across different load types while maintaining ease of operation through automated threshold-based switching.
Data Source
AI summary
An apparatus, a method, and a computer program product are provided. The apparatus determines an input voltage and an input current of a power system driving a low power factor load, the input voltage varying based on a power cycle, determines at least a first portion of the power cycle at which the input current exceeds a threshold, and couples at least one substantially resistive load to the low power factor load during at least a second portion of the power cycle different from the at least a first portion of the power cycle.