Series-Connected Converter Units With Synchronization Circuit
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Solution Overview
Problem
Existing power converter circuits face inefficiencies in transforming relatively low DC supply voltages from photovoltaic modules into AC output signals compatible with power grid voltages, particularly due to large voltage differences and inefficiencies in existing DC/AC converter systems.
Innovation Solution
A power converter circuit comprising multiple DC/AC converter units connected in series, with a synchronization circuit generating a synchronization signal to synchronize the phase and frequency of the output currents with the external AC voltage, allowing each converter unit to regulate its output current to match the grid voltage, thereby achieving efficient conversion without the need for additional control loops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a plurality of DC/AC converters are provided with each converter connected to a PV module, then the DC voltage can be converted to AC voltage consistent with power grid, but the efficiency is reduced due to the large difference between input and output voltages
Solution Approach 1:
The system segments the PV modules into groups where multiple modules are connected in series to form higher voltage DC inputs for each DC/AC converter. This segmentation allows each converter to operate at higher input voltages, reducing the voltage transformation ratio and improving conversion efficiency while maintaining the ability to connect to the power grid through parallel AC outputs.
2Loss of energy
If several PV modules are connected in series to obtain high DC voltage, then the DC voltage can be converted to AC voltage using a DC/AC converter, but electric arcs may occur due to high DC voltage
Solution Approach 1:
The system divides the high voltage DC generation into two approaches: either connecting PV modules in series to achieve high voltage (with arc risk) or using multiple DC/AC converters operating at lower voltages with parallel AC outputs. This segmentation allows the system to avoid the harmful effects of high DC voltage while maintaining conversion efficiency through optimized voltage matching.
3Adaptability or versatility
If multiple DC/AC converters are used to handle low DC voltage from PV modules, then the voltage can be converted to grid-compatible AC voltage, but the efficiency decreases due to large voltage difference
Solution Approach 1:
The system segments the voltage transformation task by allowing DC/AC converters to operate optimally at their designed input voltage levels. Multiple PV modules connected in series provide higher voltage DC input to each converter, reducing the transformation ratio and improving efficiency. The parallel connection of AC outputs ensures grid compatibility while maintaining efficient conversion.
4Loss of energy
If cascaded DC-DC converters are used to transfer energy to a common DC bus, then the voltage can be converted, but additional control complexity is required
Solution Approach 1:
The invention extracts and eliminates the intermediate DC-DC conversion stage and common DC bus from the system architecture. By directly connecting PV modules in series to DC/AC converters, the system removes the unnecessary control complexity of cascaded converters while maintaining efficient energy transfer through optimized voltage matching and direct conversion.
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
The solution enables efficient transformation of low DC voltages into AC output signals that match power grid voltages, improving efficiency and stability by self-organization of the converter units, eliminating the need for external control loops and ensuring reactive power stabilization.
Implementation Method 1
a synchronization circuit (10) configured to generate at least one synchronization signal; wherein the power converter circuit can be operated in a normal operation mode, wherein in the normal operation mode, the synchronization circuit is configured to generate the at least one synchronization signal dependent on the external voltage
Data Source
Figure 1
Figure 2A~4D
Figure 3
AI summary
Disclosed is a power converter circuit, a power supply system and a method. The power converter circuit (1), comprises • at least one converter series circuit comprising a plurality of converter units (2), the at least one converter series circuit configured to output a series circuit output current (il OUT; i OUT- REC); and • a synchronization circuit (10) configured to generate at least one synchronization signal (S vi), wherein at least one of the plurality of converter units (2) is configured to generate an output current (il) such that at least one of a frequency and a phase of the output current (il) is dependent on the synchronization signal (S vl).