Flyback PFC Converter Variable On-Time Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional flyback power factor correction (PFC) topologies face limitations in achieving unity power factor and high total harmonic distortion (THD) due to the constant on-time switching, which results in distorted input current and voltage waveforms, affecting the efficiency and compliance with industry standards.
Innovation Solution
The implementation of a phase-lock-loop (PLL) module synchronized with the rectified line voltage signal and an output regulator module that dynamically adjusts the on-time of the switch within the flyback converter, using a microcontroller to correct the wave shape and improve power factor and THD by varying the on-time based on phase variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If constant on-time switching is used in flyback PFC topology, then device complexity is reduced, but power factor and total harmonic distortion performance deteriorate
Solution Approach 1:
The patent applies dynamics by transitioning from constant on-time switching to variable on-time switching controlled by a PLL module. The on-time of the switch is dynamically adjusted based on the phase-locked loop's synchronization with the rectified line voltage signal, enabling the system to adapt switching parameters in real-time to maintain sinusoidal current waveforms and improve power factor.
Solution Approach 2:
The patent implements feedback through the phase-lock-loop (PLL) module that continuously monitors the rectified line voltage signal and adjusts the switch on-time accordingly. The PLL detects phase variations and provides feedback control to shape the input current waveform, ensuring it remains in phase with the voltage signal and thereby improving power factor and reducing harmonic distortion.
2Ease of operation
If constant on-time switching is used in flyback PFC topology, then ease of operation is improved, but total harmonic distortion increases
Solution Approach 1:
The patent implements feedback through the phase-lock-loop (PLL) module that continuously monitors the rectified line voltage signal and adjusts the switch on-time accordingly. The PLL detects phase variations and provides feedback control to shape the input current waveform, ensuring it remains in phase with the voltage signal and thereby improving power factor and reducing harmonic distortion.
Solution Approach 2:
The patent replaces simple constant on-time control with an electronic control system based on phase-lock-loop technology. This substitution enables automatic waveform shaping and harmonic reduction through electronic feedback mechanisms, replacing what would otherwise require complex mechanical or manual adjustment systems.
3Use of energy by moving object
If variable on-time switching control is implemented with PLL module, then power factor is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by integrating multiple functions into the PLL module and microcontroller system. The same control circuitry that performs phase-locking also generates the variable on-time control signals for the switch, regulates output voltage, and shapes the input current waveform. This multi-functionality reduces the need for separate dedicated circuits for each function, thereby managing complexity while achieving improved power factor.
4Object-generated harmful factors
If variable on-time switching control is implemented with PLL module, then total harmonic distortion is reduced, but device complexity increases
Solution Approach 1:
The patent implements feedback through the phase-lock-loop (PLL) module that continuously monitors the rectified line voltage signal and adjusts the switch on-time accordingly. The PLL detects phase variations and provides feedback control to shape the input current waveform, ensuring it remains in phase with the voltage signal and thereby improving power factor and reducing harmonic distortion.
Solution Approach 2:
The patent applies universality by integrating multiple functions into the PLL module and microcontroller system. The same control circuitry that performs phase-locking also generates the variable on-time control signals for the switch, regulates output voltage, and shapes the input current waveform. This multi-functionality reduces the need for separate dedicated circuits for each function, thereby managing complexity while achieving improved power factor.
Data Source
AI summary
Techniques and corresponding circuitry and drivers are disclosed for improving power factor (PF) and total harmonic distortion (THD) of a flyback power factor correction (PFC) topology operating in transition-mode. In one or more embodiments, the PF and THD are improved by correcting the on-time of the switching element of the flyback PFC topology to actively shape the wave of the PFC input current. In some embodiments, the on-time is corrected using a phase-lock-loop module that synchronizes with the rectified input line voltage signal and a output regulator module that corrects the switch on-time. The control may be implemented using a digital or an analog controller.