Soft-Switching DC-DC Converter With Selective Voltage Doubling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional LLC resonant converters face challenges in achieving high power density and efficiency over a wide output voltage range for electric vehicle charging, leading to oversizing and increased costs due to restricted operating conditions and efficiency drops when operating away from resonance.
Innovation Solution
A soft switching power converter with an isolated DC-DC converter that includes a second stage capable of selectively converting high frequency AC voltage into DC voltage, doubling the overall gain, and using a control unit to switch power conversion switches based on EV battery voltage requirements, allowing for a wide range of DC output voltages without increasing component size or cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If LLC resonant converter operates at high switching frequencies to achieve high power density, then converter size is reduced, but switching losses increase and efficiency drops
Solution Approach 1:
The patent changes the switching mode from hard switching to soft switching, fundamentally altering the operating parameters of the power converter. This enables high-frequency operation with negligible switching losses, resolving the contradiction between power density and efficiency
2Adaptability or versatility
If LLC resonant converter is designed for wide output voltage range (150V to 1500V), then adaptability improves, but converter oversizes and cost increases
Solution Approach 1:
The patent introduces a dynamic second stage that can be selectively activated based on output voltage requirements. This dynamic configuration allows the converter to adapt its gain ratio between 1:1 and 2:1, enabling wide output voltage range without oversizing the converter components
Solution Approach 2:
The patent divides the power conversion process into two stages: a first stage for basic power conversion and a second stage for voltage doubling. This segmentation allows flexible combination of stages to meet different output voltage requirements, avoiding the need to design for maximum voltage in all cases
3Adaptability or versatility
If LLC resonant converter operates away from resonance to achieve wide voltage range, then adaptability improves, but efficiency drops
Solution Approach 1:
The resonant tank circuit is designed to maintain resonance across the wide output voltage range through coordinated control of switching frequency and second stage activation. This allows the converter to achieve both wide adaptability and high efficiency by keeping the resonant tank operating at or near resonance
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 high power density and efficiency across a wide output voltage range without increasing component size or cost, enabling efficient charging of various electric vehicles by selectively doubling the DC output voltage based on EV requirements.
Implementation Method 1
a resonant tank comprising a resonant inductor Lr, a resonant capacitor Cr and a transformer magnetizing inductor Lm operably connected to one another
Implementation Method 2
an intermediary stage electrically coupling the first stage and the resonant tank to the second stage
Data Source
AI summary
A power converter, a control unit, a charging device and a method for transferring power to an EV from a power grid are provided. The power converter includes an isolated DC-DC converter having a first stage converting a DC voltage into a high frequency AC voltage having an amplitude V1, an intermediary stage having a high frequency transformer, a resonant tank which outputs a resonant sinusoidal current scaled by the high frequency transformer, and a second stage, connected to a secondary winding of the high frequency transformer, including a power conversion switch, four diodes, and two or more capacitors, that selectively converts the high frequency AC voltage of amplitude V2 into a DC voltage of amplitude V2 or 2V2.