AC-AC Power Converter with Dynamic Mode Switching
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Solution Overview
Problem
Conventional power converters are inefficient when operating at low loads due to their design for full power operation, resulting in low yield conversion of variable-frequency, variable-voltage AC power from wind turbines and flywheels to fixed-frequency, fixed-voltage AC power.
Innovation Solution
An AC to AC power converter system that uses a rectifier, an H-Bridge, and a processor to sample and modulate the output frequency, employing pulse density modulation or pulse width modulation schemes to achieve direct AC-AC power conversion without a DC link or storage devices, ensuring high efficiency across varying load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional power converters are designed for full power operation, then efficiency is improved at full load, but efficiency deteriorates at light load conditions
Solution Approach 1:
The patent implements dynamic operation modes that automatically switch between direct AC-AC conversion and rectifier-inverter conversion based on the magnitude of the phase difference between input and output frequencies. This dynamic adaptation allows the system to maintain high efficiency across varying load conditions by selecting the optimal conversion mode for each operating scenario.
Solution Approach 2:
The system changes its operational parameters by switching between different conversion modes (direct AC-AC vs. rectifier-inverter) depending on the frequency phase difference. This parameter change enables the converter to adapt to light load conditions while maintaining efficiency, resolving the contradiction between full-power optimization and light-load performance.
2Loss of energy
If direct AC-AC conversion without DC link is implemented, then efficiency is improved, but control complexity increases
Solution Approach 1:
The patent designs a universal power converter that can perform multiple functions: direct AC-AC conversion for small frequency differences and rectifier-inverter conversion for large frequency differences. This multi-functionality allows the system to achieve high efficiency across different operating conditions while using a single integrated device structure, thereby reducing overall complexity compared to having separate converters for each mode.
Solution Approach 2:
The system uses an intermediary control mechanism that monitors the phase difference between input and output frequencies and automatically selects the appropriate conversion mode. This intermediary control layer simplifies the overall system by providing a unified interface that manages the complexity of switching between different conversion topologies without requiring separate control systems for each mode.
3Stability of the object's composition
If variable frequency AC power is converted to fixed frequency AC power, then power quality is improved, but conversion loss increases
Solution Approach 1:
The patent implements dynamic mode switching that adapts to the frequency difference between input and output. When the frequency difference is small, the system uses direct AC-AC conversion which maintains output frequency stability with minimal conversion loss. When the frequency difference is large, it switches to rectifier-inverter conversion. This dynamic adaptation resolves the contradiction by minimizing conversion loss while maintaining the required output frequency stability across different operating conditions.
Data Source
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AI summary
An AC to AC power converter has a rectifier configured to receive an AC signal. An H-Bridge is coupled to the rectifier and the DC Filter. A processor is coupled to the rectifier and to the H-Bridge, wherein the processor is configured to produce a pulse to modulate a rectified input or a constant DC input to the H-Bridge. A wave filter is coupled to the H-Bridge and configured to modulate an output of the H-Bridge to an AC voltage of a desired frequency, wherein an output of the wave filter is coupled to the processor.