Power Factor Corrector Circuit Eliminating Harmonic Distortion
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Solution Overview
Problem
Conventional power converters with power factor correction (PFC) require complex computing circuits and numerous arithmetic operations, and the presence of low-pass filters introduces phase delay, offsetting the PFC effect and complicating signal handling across various frequency bands.
Innovation Solution
A power converter design that includes a rectifier and a PFC with a correcting circuit and a control circuit, where the correcting circuit uses an inductor and a transistor controlled by a driving signal to manage energy storage and discharge, and the control circuit generates comparison signals to adjust the driving signal, eliminating harmonic distortion without complex arithmetic operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a computing circuit with high linearity is used to perform arithmetic operations for power factor correction, then the power factor improvement is achieved, but the device complexity and manufacturing burden increase significantly
Solution Approach 1:
The patent extracts and eliminates the complex computing circuit from the power factor correction system. Instead of using a computing circuit to perform arithmetic operations on rectified voltage and current signals, the invention uses a simplified control circuit that directly compares rectified voltage with a reference signal to generate control signals for the switching transistor, achieving power factor correction without the burdensome computing hardware
Solution Approach 2:
The patent replaces the computational/mechanical arithmetic operations with an electrical comparison mechanism. The control circuit compares voltages directly using operational amplifiers and voltage dividers, substituting the need for complex digital or analog computing circuits with simpler electrical comparison and feedback mechanisms
2Stability of the object's composition
If a low-pass filter is added to filter out the sawtooth waveform from the inductor current, then the waveform quality is improved, but phase delay is introduced that offsets the power factor correction effect
Solution Approach 1:
The patent converts the potentially harmful sawtooth waveform component into a beneficial element by using it as part of the control signal generation process. The sawtooth waveform generated by the ramp generator is intentionally used in the comparison circuit to create pulse-width modulated control signals, transforming what would be a filterable distortion into a functional control mechanism that achieves both waveform control and power factor correction
Solution Approach 2:
The patent performs preliminary shaping of the control signal using the sawtooth waveform before it becomes a problem. The ramp generator creates the sawtooth pattern in advance, and this pattern is used to modulate the switching duty cycle, thereby pre-establishing the current waveform shape needed for power factor correction without requiring post-filtering that would introduce phase delay
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 design improves power factor correction by eliminating harmonic distortion in the current through the inductor, enhancing the power converter's performance without the need for complex computing circuits or arithmetic operations, and maintains stability across frequency bands.
Implementation Method 1
The correcting circuit includes an inductor, and current flowing from the rectifier flows through the inductor
Implementation Method 2
The correcting circuit further includes a transistor that is controlled by the driving signal to switch between conducting and non-conducting states to control in turn energy storing and energy discharging by the inductor
Data Source
AI summary
A power converter includes a rectifier and a power factor corrector. The rectifier is to be coupled to an alternating current power source and is configured to output a rectified signal. The power factor corrector includes a correcting circuit and a control circuit. The correcting circuit receives the rectified signal and is configured to generate an output voltage based on the rectified signal and a driving signal. The control circuit is configured to generate a first to-be-compared signal based on the rectified signal, to generate a second to-be-compared signal based on the output voltage, to compare the first and second to-be-compared signals, and to generate the driving signal based on a result of comparison performed thereby.