Three-Phase Power Factor Correction with Constant Duty Control
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Solution Overview
Problem
Conventional power factor correction devices for AC power generators using natural energy, such as wind power, face complexity in switch control due to fluctuating outputs, leading to stability and reliability issues, and the addition of a separate DC/DC converter complicates the construction and control system, increasing costs.
Innovation Solution
A power factor correction device with a simple construction and control system that includes first, second, and third input terminals for three-phase AC, transformers with primary and secondary coils, switching elements controlled by a single control signal with a constant duty ratio, and rectifying devices to ensure effective power factor correction and insulation between input and output terminals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complicated switch control techniques such as PWM modulation are used to optimize power output, then power factor correction effectiveness is improved, but control system complexity and operational stability deteriorate
Solution Approach 1:
The patent changes the control parameter from complex PWM duty cycle modulation to a simple constant duty ratio (e.g., 50%). This parameter simplification maintains power factor correction effectiveness while dramatically reducing control system complexity and improving operational stability in fluctuating wind power conditions.
Solution Approach 2:
The transformer-based circuit automatically achieves power factor correction through its inherent electromagnetic coupling and rectification characteristics, without requiring external complex control systems. The circuit self-regulates to maintain unity power factor despite input fluctuations.
2Reliability
If a separate DC/DC convertor is added for insulation, then insulation between input and output is achieved, but construction complexity and cost increase
Solution Approach 1:
The patent merges the insulation function into the existing transformer-based power factor correction circuit. The transformer's galvanic isolation naturally provides input-output insulation, eliminating the need for a separate DC/DC convertor while maintaining insulation reliability.
Solution Approach 2:
The transformer serves multiple functions simultaneously: power factor correction, voltage transformation, and galvanic isolation. This multi-functionality reduces overall system complexity by consolidating what would otherwise require separate components.
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 effective power factor correction and stable power conversion with a simplified construction and control system, ensuring insulation between input and output terminals while reducing complexity and cost.
Implementation Method 1
first, second and third transformers (Tr, Ts, Tt) respectively having primary coils (Lr1, Ls1, Lt1) with one ends respectively connected to said first, second and third input terminals (R, S, T) and secondary coils (Lr2, Ls2, Lt2)
Implementation Method 2
first, second and third rectifying devices (D1, D2, D3) respectively disposed between the other ends of said secondary coils (Lr2, Ls2, Lt2) of said first, second and third transformers (Tr, Ts, Tt) and said positive electrode terminal (p) so as to pass current flow into said positive electrode terminal when the other ends of said secondary coils have forward-biased potentials
Data Source
AI summary
A power factor correction device for three-phase AC-DC conversion enables effective correction and stable power conversion with a simple construction and control system. The device may include input terminals to which three-phase AC is inputted, and Positive and negative electrode terminals each connected to a load device. Transformers each have a primary coil with an end connected to the input terminals. Switching element(s) have ends applied with the voltage of another end of the primary coil, other ends connected to a common potential terminal on the side of the primary coil, and control ends. Rectifying devices have ends applied with the voltage of another end of the secondary coil so as to pass current flow into the positive electrode terminal. A smoothing condenser is disposed between the positive and negative electrode terminals. The control ends of the switching elements are controlled by a control signal having a constant duty ratio.