LLC Converter Bus Switching for Wide Voltage Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
LLC resonant converters face efficiency sacrifices when operating at voltages significantly above or below their optimal range, as they must adjust their operating frequency to maintain regulation, leading to reduced performance across a wide range of voltages.
Innovation Solution
A modified LLC resonant converter design that switches between a high-voltage bus and a low-voltage bus, controlled by a microcontroller, to maintain resonance and efficiency across a wide range of voltages, using a diode structure and transformer configuration that operates as a full-bridge or full-wave rectifier depending on the output voltage threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the LLC resonant converter operates at a lower voltage than its optimal efficiency design, then the operating frequency is raised significantly above the resonance of the tank circuit to achieve regulation, but this sacrifices efficiency
Solution Approach 1:
The patent divides the single output bus into two separate busses (first output bus and second output bus) with different voltage levels. The converter can switch between these busses depending on the required output voltage, allowing the tank circuit to operate near resonance for both high and low voltage conditions, thus maintaining efficiency across a wide voltage range.
Solution Approach 2:
The patent implements dynamic switching between two output busses based on the required output voltage. The converter dynamically selects which bus to use (first or second) depending on whether the output voltage is above or below a threshold, enabling the system to adapt its operating point to maintain resonance and efficiency under varying load conditions.
2Use of energy by moving object
If the LLC resonant converter operates at a higher voltage than its optimal efficiency design, then the operating frequency is lowered significantly below the resonance of the tank circuit to achieve regulation, but this also sacrifices efficiency
Solution Approach 1:
The patent segments the output voltage range into two zones by providing two separate output busses with different voltage levels. Each bus is optimized for a specific voltage range, allowing the converter to maintain efficient resonant operation in both zones by selecting the appropriate bus based on the required output voltage.
Solution Approach 2:
The patent changes the output voltage parameter by switching between two different output busses rather than adjusting the operating frequency over a wide range. This allows the system to maintain a narrow, efficient frequency range near resonance while achieving wide voltage regulation capability through bus selection.
3Ease of operation
If the operating frequency is adjusted significantly away from resonance to regulate output voltage, then voltage regulation is achieved, but power losses increase and overall efficiency decreases
Solution Approach 1:
The patent segments the voltage regulation function across two separate output busses, each optimized for a specific voltage range. This segmentation allows the converter to regulate voltage by switching between busses rather than by making large frequency adjustments, thereby minimizing power losses and maintaining high efficiency.
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 design maintains high efficiency by ensuring the converter operates at or near resonance across a wide range of voltages, reducing power losses and increasing overall efficiency, particularly in electric vehicle charging applications.
Implementation Method 1
This square wave is in turn fed to a resonant LLC tank that effectively filters out harmonics to provide a sinusoidal-like voltage and current output waveform
Implementation Method 2
The waveform in turn is fed to an isolation transformer that provides voltage scaling
Data Source
AI summary
A DC-DC converter includes an inverter converting a DC supply voltage to a time varying signal. A transformer has a primary winding coupled to the inverter through an LC-tank circuit. A diode structure includes a first diode pair coupled in series between a high-voltage bus and a negative output, and a second diode pair coupled in series between the high-voltage bus and the negative output. The transformer has a secondary winding with a first terminal coupled to a tap between the first diode pair and a second terminal coupled to a tap between the second diode pair. A high-voltage bus transistor selectively couples the high-voltage bus to a positive output in response to a high-voltage bus gate drive signal. A low-voltage bus transistor selectively couples a low-voltage bus at a center tap of the secondary winding to the positive output in response to a low-voltage bus gate drive signal.