Power Factor Correction Circuit Reducing Total Harmonic Distortion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional power supply devices using on-time control methods for power factor correction suffer from increased total harmonic distortion (THD), which is not effectively addressed by existing technologies.
Innovation Solution
A power supply device incorporating a power factor correction circuit with an input side voltage detection circuit, an output side voltage detection circuit, a transformer, an error amplifier, a subtractor, an output comparator, and a flip-flop circuit, where the input voltage is detected and shaped to reduce THD by adjusting the on-time of the main switch based on the input voltage waveform.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If on-time control method is used for power factor correction, then circuit area and cost are reduced, but total harmonic distortion increases
Solution Approach 1:
The patent implements a feedback mechanism where the input voltage is detected and fed back to dynamically adjust the current detection threshold value. The threshold value is modified based on the instantaneous input voltage level, creating a closed-loop control system that compensates for the high THD characteristic of on-time control while maintaining its circuit simplicity.
Solution Approach 2:
The patent dynamically changes the parameter of the current detection threshold value based on the input voltage waveform. By adjusting this threshold parameter in real-time according to the input voltage level, the system optimizes the switching behavior to reduce harmonic distortion while preserving the advantages of on-time control methodology.
2Object-generated harmful factors
If current detection control method is used for power factor correction, then total harmonic distortion is reduced, but circuit area and cost increase due to multiplier requirement
Solution Approach 1:
The patent extracts and removes the multiplier component from the control circuit by implementing an alternative approach that uses dynamic threshold adjustment instead. This extraction eliminates the complex multiplication operation while achieving similar or better THD performance through the modified on-time control with voltage-dependent threshold.
Solution Approach 2:
The patent substitutes the complex mathematical multiplication operation with a simpler voltage-dependent threshold adjustment mechanism. By replacing the multiplier-based current detection control with this alternative method, the system achieves comparable harmonic performance without requiring complex computational hardware.
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 enables on-time control while significantly reducing total harmonic distortion, improving the power supply device's efficiency and performance.
Implementation Method 1
a primary side winding (L1) having one end that is connected to the first power supply terminal, the primary side winding being included in a transformer (T), a secondary side winding (L2) having one end that is connected to the second power supply terminal, the secondary side winding being included in the transformer (T)
Implementation Method 2
a rectifier circuit connected between the first input terminal and the second input terminal and configured to output, between a first power supply terminal and a second power supply terminal, a power supply voltage obtained by rectifying the AC voltage supplied from the AC power supply
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A power supply device according to the present invention detects a value of an input voltage (power supply voltage) by an input side voltage detection circuit, and decreases a comparative voltage (error voltage) that is compared with an on timer signal (timer signal) for determining an on time of a switching element based on the value of the input voltage. The power supply device employs an on-time control and at the same time reduces the total harmonic distortion.