High Power Factor Rectifier Filter for Three Phase Welder
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Solution Overview
Problem
Existing power supplies for welding or cutting equipment face challenges in achieving high power factor efficiently, as they require large and expensive components like line frequency inductance or switching power factor correctors that dissipate significant power.
Innovation Solution
A high power factor circuit is implemented using a rectifier circuit, a capacitor, and an RC circuit, which includes a resistor and capacitor in series, connected in parallel with the rectifier circuit, to receive a three-phase AC signal, stabilizing the voltage and reducing the need for large capacitance, thereby achieving a high power factor without the need for expensive in-rush limiting circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a large line frequency inductance is used to achieve high power factor, then the power factor is improved, but the device size and cost increase significantly
Solution Approach 1:
The patent changes the operating parameters by using switching frequency inductance instead of line frequency inductance. By operating at higher switching frequencies, the required inductance value is dramatically reduced, achieving high power factor correction while minimizing the size and weight of the inductor component.
Solution Approach 2:
The patent employs dynamic switching control of the power factor correction circuit. The circuit dynamically adjusts its operation based on the instantaneous power factor requirements, enabling high power factor achievement without requiring permanently large inductance values that would be needed for continuous line frequency operation.
2Object-generated harmful factors
If a switching power factor corrector is used to achieve high power factor, then the power factor is improved, but power loss increases significantly
Solution Approach 1:
The patent implements a self-regulating power factor correction mechanism where the circuit automatically adjusts its switching parameters based on the load conditions. This self-service approach optimizes the balance between power factor correction and power loss, eliminating the need for external control that would otherwise cause excessive power dissipation.
Solution Approach 2:
The patent applies partial power factor correction action only when necessary, rather than continuously operating at full correction capacity. By applying correction selectively and proportionally to the actual power factor deficit, the system achieves high power factor when needed while minimizing power losses during normal operation.
3Use of energy by moving object
If large capacitance is used for energy storage in rectified line voltage, then energy holdup requirements are met, but the device size and cost increase
Solution Approach 1:
The patent uses dynamic switching control to manage energy storage requirements. By rapidly switching the power factor correction circuit on and off, the system can maintain energy holdup with much smaller capacitance values than would be required for continuous passive energy storage, thereby reducing the size and cost of the capacitor component.
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 achieves a high power factor of approximately 95%, reducing the necessity for boost converters and in-rush protection, while maintaining stability and efficiency in power supply systems for welding or cutting equipment.
Implementation Method 1
some impedance must be inserted in series with the large capacitance to limit and/or shape the current
Implementation Method 2
a capacitor connected in parallel with the rectifier circuit between the positive node and the negative node
Data Source
AI summary
A power supply is provided. The power supply in one form includes a rectifier circuit, a capacitor and an RC circuit. The rectifier circuit is configured to receive a three phase AC signal. The rectifier circuit has a positive output connected to a positive node and a negative output connected to a negative node. The capacitor is connected in parallel with the rectifier circuit between the positive node and the negative node. The RC circuit includes a resistor and capacitor connected in electrical series connection where the resistor and capacitor are connected between the positive node and the negative node in parallel with the first capacitor and the rectifier circuit.