Charger Voltage Amplitude Modulation for LLC Resonance Efficiency
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Solution Overview
Problem
Existing chargers for energy storage devices, such as batteries, operate sub-optimally due to frequency modulation, which prevents them from functioning at the resonance frequency for maximum efficiency, resulting in increased switching and conduction losses.
Innovation Solution
The charger employs voltage amplitude modulation (VAM) using feedback from the energy storage device, maintaining a constant frequency at the LLC resonance frequency, and utilizing a buck/boost configuration to optimize charging efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If frequency modulation is used to control charging voltage, then the charger can adapt to different charging stages, but the charger cannot operate at resonance frequency, resulting in increased switching and conduction losses
Solution Approach 1:
The patent changes the control parameter from frequency modulation to voltage amplitude modulation. By keeping the switching frequency constant at the resonance frequency and modulating only the voltage amplitude, the system achieves both optimal efficiency (operating at resonance) and adaptability (adjusting voltage for different charging stages).
Solution Approach 2:
The patent implements feedback control where the charger monitors the battery charging state and adjusts the voltage amplitude accordingly. This feedback mechanism allows the system to adapt to different charging stages while maintaining constant frequency operation at the resonance point, thereby reducing energy losses.
2Ease of operation
If frequency modulation is used, then charging control is achieved, but the LLC converter design becomes more complex
Solution Approach 1:
The patent simplifies the LLC converter design by fixing the switching frequency at the resonance frequency and eliminating frequency modulation circuitry. The control complexity is reduced from managing both frequency and amplitude to only managing voltage amplitude, thereby simplifying the overall converter design while maintaining charging control capability.
3Ease of operation
If frequency modulation is used, then voltage regulation is achieved, but component size increases
Solution Approach 1:
By operating at a fixed resonance frequency, the LLC converter can be optimized with smaller magnetic components and capacitors. The voltage regulation is achieved through amplitude modulation rather than frequency changes, allowing for more efficient component utilization and reduced overall component size compared to frequency-modulated designs.
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 allows the charger to operate at the resonance frequency, reducing switching and conduction losses, achieving higher efficiency and simplifying the LLC converter design, with potential for almost 100% efficiency and reduced component size.
Implementation Method 1
a softly switched LLC (i.e., with a capacitance Cr, a serial inductance Lr and a parallel inductance Lm) resonant converter is typically used to handle high power and produce variable voltage gains in different operating frequencies while providing soft switching for all involved semiconductor devices
Data Source
AI summary
Chargers and methods are provided which increase the charging efficiency of the chargers by implementing voltage amplitude modulation (VAM) instead of voltage frequency modulation. The charging voltage amplitude is modulated using feedback from at least one energy storage device that is being charged by the charger, while maintaining a charging voltage frequency constant at a LLC resonance frequency of the charger. A buck/boost configuration may be used to reduce maximal voltage levels and further optimize the charger's design.