Power Factor Corrector Hold-Time Control to Prevent Hunting
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Solution Overview
Problem
The on-off control of a power factor corrector can fail to recognize its state immediately after switching, leading to hunting, where the power factor corrector alternately turns on and off, causing disturbances in the current waveform and abnormal noise due to transitional recognition failures.
Innovation Solution
A power converter system with a controller that maintains the state of the power factor corrector for a predetermined time period after switching, regardless of parameter values, and then switches based on the latest parameter values detected during this period, to prevent continuous on-off cycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the controller turns on or off the power factor corrector based on parameter value comparison, then the power factor correction operation is controlled, but hunting occurs due to transitional recognition failure immediately after switching
Solution Approach 1:
The controller enters a predetermined time period after switching the power factor corrector, during which it maintains the current state without making new switching decisions. This preliminary action prevents immediate re-switching that would cause hunting, allowing the system to stabilize before the next control decision is made.
2Speed
If the controller responds immediately to parameter value changes, then the power factor corrector switches quickly, but continuous on-off cycling occurs
Solution Approach 1:
The controller pre-establishes a predetermined time period that begins when the power factor corrector is switched. During this period, the controller maintains the current state regardless of parameter value changes, preventing immediate reverse switching and ensuring operational stability while preserving quick response capability when needed.
3Measurement precision
If the power factor corrector switches frequently to maintain accurate power factor correction, then the power factor is corrected precisely, but waveform disturbance and noise increase
Solution Approach 1:
By establishing a predetermined time period after switching events, the controller prevents frequent back-and-forth switching that would generate waveform disturbances and noise. This approach maintains power factor correction accuracy by allowing proper switching when needed while preventing harmful oscillations during transitional periods.
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 reduces hunting by ensuring stable operation during the predetermined time period and correct switching based on updated parameter values, minimizing waveform disturbances and noise.
Implementation Method 1
a rectifier (22) configured to rectify an input alternate current (AC) from an AC power source (91)
Implementation Method 2
a power factor corrector (25) configured to perform a power factor correction operation on an input voltage (V1) output from the rectifier (22)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Reduced is occurrence of hunting in which a power factor corrector continuously turns on and off alternately for a short period of time. A power factor correction controller (31g) turns on a power factor corrector (25) if a parameter value for an input current (Im) into the power factor corrector (25) is greater than or equal to a first threshold, and turns off the power factor corrector (25) if the parameter value is smaller than or equal to a second threshold below the first threshold. Through a predetermined time period (Tg) from a moment when the power factor corrector (25) is switched either from on to off or from off to on, the power factor correction controller (31 g) maintains a state of the switched power factor corrector (25), regardless of the parameter value.