Partial-Power AC-DC Converter With Dual DC-Link Regulation
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Solution Overview
Problem
Existing power converter systems for automotive on-board chargers face challenges in achieving efficient and compact AC-DC power conversion with galvanic isolation, particularly due to the wide range of battery voltages, leading to reduced efficiency and larger transformer sizes.
Innovation Solution
A novel power conversion arrangement featuring a 5-level rectifier with two distinct variable DC-links for power factor correction, followed by a partial-power DC/DC converter for output voltage regulation and an isolated DC/DC converter for galvanic isolation, utilizing a series resonant converter operating at a fixed frequency to optimize efficiency and reduce transformer size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a two-stage system with constant DC-link voltage and frequency-modulated LLC resonant converter is used to achieve wide output voltage range, then adaptability is improved, but efficiency deteriorates due to higher reactive power and switching frequencies far from resonant frequency
Solution Approach 1:
The patent applies dynamics by making the DC-link voltage variable instead of constant. The first DC/DC converter dynamically adjusts the first DC-link voltage, and the second DC/DC converter adjusts the second DC-link voltage, enabling the system to adapt to wide output voltage ranges while maintaining switching frequencies close to the resonant frequency, thus preserving high efficiency.
Solution Approach 2:
The patent changes the operating parameters of the resonant converter by using two distinct DC-link voltages instead of one. This allows the converter to operate at optimal resonant frequencies across different operating conditions, avoiding the efficiency loss that occurs when switching frequencies deviate from resonance.
2Adaptability or versatility
If frequency modulation is used to regulate output voltage in LLC resonant converter, then adaptability is improved, but device complexity increases due to wide frequency range requirements
Solution Approach 1:
The patent segments the voltage regulation function into two independent DC/DC converters operating at different DC-link voltages. This segmentation allows each converter to operate within a narrower, more efficient frequency range while collectively providing wide output voltage adaptability, thereby reducing control complexity.
3Adaptability or versatility
If wide frequency range operation is implemented in LLC resonant converter, then adaptability is improved, but weight increases due to larger magnetic core size
Solution Approach 1:
By dynamically adjusting the DC-link voltages to match operating conditions, the system maintains resonant operation at fixed or narrow frequency ranges. This eliminates the need for oversized magnetic cores designed for wide frequency ranges, thereby reducing transformer weight while maintaining adaptability.
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 solution enhances the efficiency and compactness of power conversion, reduces the size of magnetic cores, and allows the use of lower voltage semiconductor devices, resulting in higher performance and lower costs for on-board chargers.
Implementation Method 1
a series resonant converter (SRC) operating with fixed frequency (at its resonance frequency) is preferred over a frequency-modulated LLC
Data Source
AI summary
The disclosure provides methods and a power converter arrangement for converting an alternating current (AC) voltage into a direct current (DC) voltage. The power converter arrangement includes: an AC-DC conversion stage being configured to convert an AC voltage into a first DC link voltage at a first DC link and into a second DC link voltage at a second DC link; a DC-DC conversion stage connected to the AC-DC conversion stage, the DC-DC conversion stage being configured to provide the DC voltage based on the first DC link voltage and the second DC link voltage; and a partial-power DC-DC converter coupled between the AC-DC conversion stage and the DC-DC conversion stage, the partial-power DC-DC converter being configured to exchange power between the first DC link and the second DC link.