Zonal PV Inverter With Isolated Converters for Current Mismatch
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Solution Overview
Problem
Photovoltaic (PV) modules operate below 20% efficiency due to factors such as increasing PV cell temperature, variability in incident radiation, and cell imperfections, which lead to mismatches in short circuit current and open circuit voltage between PV cells.
Innovation Solution
The use of a zonal power inverter with series-connected voltage converters, each coupled to a photovoltaic cell, and a controller to modulate the input signals and regulate the output voltage, allowing for direct thermal cooling of PV cells and reducing current mismatch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PV cells are connected in series-parallel configuration in traditional inverters, then the system can handle variable power output, but current mismatch between cells reduces overall efficiency below 20%
Solution Approach 1:
The system divides the PV array into multiple independent zones, each with its own voltage converter. This segmentation allows each zone to operate independently at its own maximum power point, eliminating the current mismatch problem that occurs when cells are connected in traditional series-parallel configurations. The independent control of each zone enables the system to achieve over 90% efficiency by preventing energy loss from current mismatch.
2Reliability
If PV cells operate at higher temperatures, then the system can maintain operation in hot environments, but efficiency decreases by 0.4% per degree C increase
Solution Approach 1:
By segmenting the PV system into independently controlled voltage converters, each zone can be optimized for its specific operating conditions. This allows for targeted thermal management where each zone's converter can regulate voltage and current independently, enabling better heat dissipation control and maintaining higher efficiency even in hot environments.
Solution Approach 2:
The system dynamically adjusts operating parameters (voltage, current, duty cycle) of each voltage converter based on real-time conditions. By changing these parameters, the system can optimize performance across different temperature ranges, maintaining reliability in hot environments while minimizing efficiency loss through adaptive parameter control.
3Device complexity
If traditional single-stage inverters are used, then the device complexity is low, but the system cannot regulate output voltage for each individual PV cell
Solution Approach 1:
The inverter is segmented into multiple independent voltage converter modules, each capable of regulating output voltage for its associated PV zone. This modular segmentation provides fine-grained voltage regulation capability while maintaining reasonable system complexity through standardized module design. Each converter can be independently controlled, enabling precise voltage regulation that adapts to individual cell characteristics.
Solution Approach 2:
The system implements dynamic voltage regulation where each voltage converter can independently adjust its output based on real-time PV cell conditions. This dynamic adaptability allows the system to optimize performance for each individual cell or zone, responding to variations in irradiance, temperature, and cell characteristics without requiring complex centralized control.
4Ease of manufacture
If PV modules use standard housing and connections, then manufacturing cost is reduced, but thermal transfer from PV cells to environment is insufficient
Solution Approach 1:
The modular voltage converter design creates natural thermal zones that can be independently managed. Each converter module can incorporate localized thermal management features, allowing standard housing to be used while adding targeted thermal control where needed. This segmentation enables flexible thermal management that maintains manufacturing simplicity while improving heat dissipation.
Solution Approach 2:
The voltage converter electronics serve as an intermediary thermal management component between PV cells and the environment. By positioning converters strategically and using them as heat dissipation pathways, the system can transfer thermal energy from PV cells through the converter components to the environment, enhancing cooling without requiring complete redesign of standard housing.
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 configuration enhances the efficiency of PV cells by allowing each cell to operate at or near its maximum power point, reducing thermal losses, and improving overall power output.
Implementation Method 1
Many photovoltaic (PV) circuits include silicon PV cells
Implementation Method 2
each of the voltage converters being electrically isolated from one another except for their output terminals being connected in series
Data Source
AI summary
Technology for converting electricity generated by photovoltaic cells to AC or DC output power is disclosed. In some examples of the disclosed technology, a zonal power inverter has a plurality of voltage converters, the outputs of the voltage converters being connected in series and being electrically isolated from one another except for their output terminals being connected in series. The power inverter can further comprise a DC/AC converter coupled to a positive output terminal of one of the voltage converters. In some examples, an isolated multi-junction photovoltaic cell includes a plurality of photosensitive semiconductor active layers, each of the active layers being electrically isolated from the other active layers, and formed from a respective material having a different band gap than the other active layers. In some examples, the multi-junction photovoltaic cell is coupled to the input of the zonal power inverter.