Series Power Converter Circuit for Grid Synchronization
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Solution Overview
Problem
Existing power converter systems face inefficiencies when converting relatively low DC supply voltages from photovoltaic modules into AC supply voltages compatible with power grids, due to large voltage differences and the need for synchronized control of multiple converters.
Innovation Solution
A power converter circuit comprising multiple converter units connected in series, with a voltage measurement circuit providing phase and frequency information to regulate AC output current, ensuring a specified phase difference with the external AC voltage, thereby optimizing conversion efficiency and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If several DC/AC converters are connected in parallel, then the AC voltage output matches power grid standards, but the conversion efficiency decreases due to large voltage difference between input and output
Solution Approach 1:
The system segments the voltage conversion task across multiple converter units connected in series, where each unit handles a portion of the voltage transformation. This allows the overall system to achieve high voltage compatibility while each individual unit operates at more efficient voltage levels, reducing total energy loss.
Solution Approach 2:
The patent changes the operating parameters of individual converter units by connecting them in series, allowing each unit to operate at optimized voltage levels. This parameter optimization improves conversion efficiency while the combined series output achieves the required AC voltage compatibility with power grid standards.
2Power
If several DC/AC converters are connected in series with centralized control, then voltage transformation is achieved, but the system complexity increases due to constant synchronized control requirements
Solution Approach 1:
Each converter unit is equipped with autonomous control capabilities that allow it to self-regulate its operation. The units independently manage their switching and synchronization without requiring complex centralized control, thereby achieving voltage transformation while reducing overall system control complexity.
Solution Approach 2:
The converter units are pre-configured with embedded control logic and synchronization mechanisms that are built into each unit beforehand. This preliminary configuration eliminates the need for complex real-time centralized synchronization, simplifying the overall control architecture while maintaining effective voltage transformation.
3Power
If high DC voltage is used for conversion, then the DC voltage exceeds peak AC voltage for effective conversion, but electric arcs become a critical safety hazard
Solution Approach 1:
The high DC voltage is segmented across multiple converter units connected in series, with each unit handling a manageable voltage portion. This segmentation achieves the required voltage level for effective AC conversion while distributing the voltage stress, thereby reducing the electric arc risk associated with concentrated high voltage.
Solution Approach 2:
The converter units act as intermediary components between the DC power source and the AC power grid. Each unit independently manages voltage conversion and isolation, serving as a protective barrier that reduces electric arc hazards while enabling effective voltage transformation to match power grid requirements.
Data Source
AI summary
A power converter circuit includes output terminals configured to receive an external AC voltage. At least one series circuit has at least two converter units. Each converter unit includes input terminals configured to be coupled to a DC power source. Output terminals provide an AC output current. The at least one series circuit is connected between the output terminals of the power converter circuit. A voltage measurement circuit is connected between the output terminals of the power converter circuit and configured to provide at least one measurement signal that includes information related to phase and frequency of the external AC voltage. At least one of the converter units is configured to receive the at least one measurement signal and is configured to regulate the generation of the AC output current dependent on the at least one measurement signal.