Synchronous Harmonic Converter for Single-Stage PFC Voltage Regulation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing single stage power factor corrected converters face challenges in reducing switching current and improving voltage regulation, especially in low noise applications, due to large magnetic and switch currents, and output voltage ripple.
Innovation Solution
A single stage bidirectional power factor corrected converter is implemented using a synchronous average harmonic current control, merging power factor correction with a regulated resonant converter, where the primary bridge voltage is harmonically filtered and coupled across an isolation transformer, and the secondary bridge is synchronized using a synchronous average harmonic current controller to reduce recirculating bridge current and transformer ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single stage power factor corrected converter is used, then parts count is reduced, but switching current increases
Solution Approach 1:
The single stage converter is segmented into two independent full-bridge circuits operating at different frequencies. The first full-bridge operates at a lower frequency for power factor correction, while the second full-bridge operates at a higher frequency for voltage regulation. This segmentation allows each bridge to handle specific functions with optimized current levels, reducing overall switching current stress while maintaining the single-stage architecture.
Solution Approach 2:
The patent employs dynamic frequency operation where the first full-bridge operates at a variable frequency below the resonant frequency of the series resonant circuit, and the second full-bridge operates at a higher frequency. This dynamic frequency control enables the system to maintain power factor correction while regulating output voltage, thereby reducing switching current compared to fixed-frequency single-stage designs.
2Loss of energy
If power factor correction stage is combined with DC-to-DC converter stage, then efficiency is improved, but output voltage ripple increases
Solution Approach 1:
The combined power factor correction and DC-to-DC converter stages are segmented into two independent full-bridge circuits operating at different frequencies. The first full-bridge handles power factor correction at a lower frequency, while the second full-bridge performs DC-to-DC conversion at a higher frequency. This frequency separation prevents the coupling of power factor corrected input current ripple to the output, eliminating the need for additional regulation stages while maintaining efficiency.
Solution Approach 2:
The patent uses periodic switching at two different frequencies - a lower frequency for power factor correction and a higher frequency for voltage regulation. This periodic action at staggered frequencies ensures that the ripple components from power factor correction do not directly couple to the output, thereby reducing output voltage ripple while maintaining the efficiency benefits of the combined stage architecture.
3Manufacturing precision
If resonant network is used in series with isolation transformer, then voltage regulation is improved, but switching current increases
Solution Approach 1:
The system dynamically controls the operating frequency of the first full-bridge to be below the resonant frequency of the series resonant circuit. This dynamic frequency control, combined with the higher frequency operation of the second full-bridge, achieves improved voltage regulation through resonant effects while distributing the switching current across two bridges, thereby reducing the current burden on each individual switch.
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
This approach results in efficient voltage regulation with reduced switching current and parts count, achieving low noise regulation without additional power stages, enhancing efficiency and reducing conduction losses.
Implementation Method 1
a resonant network (305) in series with an isolation transformer (310) coupled between the primary bridge (301) and the secondary bridge (302)
Data Source
AI summary
A synchronous average harmonic current controller for a line connected bidirectional resonant power converter results in a harmonic voltage gain closely related to the commanded bridge duty cycles. A primary bridge has its duty cycle set to achieve controlled line power transfer and voltage regulation of a primary bus energy storage capacitor. A secondary bridge circuit has its duty cycle set to achieve voltage regulation of secondary bus energy storage capacitor. A first embodiment uses the independent energy storage elements to achieve power factor correction and low noise regulation using a single stage. A second embodiment uses feedforward duty cycle control to achieve isolated voltage regulation using the well-defined voltage gain resulting from the synchronous average harmonic current controller.