Series Power Converter Circuit with Synchronization for Grid Compatibility
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Solution Overview
Problem
There is a need for a power converter circuit that can efficiently transform relatively low DC supply voltages from photovoltaic modules into an AC supply voltage compatible with power grid voltage, addressing inefficiencies in existing conversion methods due to large voltage differences and the requirement for synchronized control in multi-level switching patterns.
Innovation Solution
A power converter circuit comprising multiple converter units connected in series, with a synchronization circuit generating a synchronization signal that regulates the output current's frequency and phase, allowing each converter unit to synchronize with the external AC voltage and optimize energy transfer without the need for constant centralized control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple DC/AC converters are connected in series with centralized synchronized control, then the AC output voltage can match power grid requirements, but the system complexity and control difficulty increase significantly
Solution Approach 1:
The patent divides the power conversion system into multiple independent converter units (first DC/AC converter unit, second DC/AC converter unit, etc.), each capable of autonomous operation. These units are connected in series to achieve the required AC output voltage while maintaining individual control independence, thereby reducing overall system complexity.
Solution Approach 2:
Each DC/AC converter unit is equipped with its own control unit that can autonomously regulate its output based on local DC voltage conditions. The control units self-synchronize without requiring complex centralized control, allowing each unit to serve itself while contributing to the overall system function.
2Adaptability or versatility
If multiple DC/AC converters are used to handle low DC voltages, then the system can operate with standard PV modules, but the conversion efficiency decreases due to large voltage differences
Solution Approach 1:
The patent segments the voltage transformation task across multiple converter units connected in series. Each unit handles a portion of the voltage conversion, reducing the voltage difference each individual unit must bridge, thereby improving overall conversion efficiency while maintaining compatibility with standard PV module voltages.
Solution Approach 2:
The control units dynamically adjust operating parameters such as switching frequencies and duty cycles to optimize the conversion process. By changing these parameters adaptively, the system maximizes efficiency at each conversion stage while handling the voltage transformation from low DC to grid-compatible AC levels.
Data Source
AI summary
A power converter circuit includes output terminals configured to receive an external voltage. A series circuit includes a number of converter units, each including input terminals configured to be coupled to a DC power source and output terminals configured to provide an output current. The series circuit is connected between the output terminals of the power converter circuit. A synchronization circuit is configured to generate a synchronization signal. The power converter circuit can be operated in a normal operation mode. In the normal operation mode, the synchronization circuit is configured to generate the synchronization signal dependent on the external voltage. In the normal operation mode, at least one converter unit of the plurality of converter units is configured to receive the synchronization signal and to regulate a generation of the output current such that a frequency and/or a phase of the output current is dependent on the synchronization signal.