Solar Module Power Converter Switching Control
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Solution Overview
Problem
Solar modules face challenges during start-up due to excessive no-load voltage from solar cells, which can exceed the permissible input voltage of power converters, leading to potential damage and inefficient operation, as existing solutions either require oversized converters or temporary choppers for voltage reduction.
Innovation Solution
Implementing a controller that adjusts the switching behavior of semiconductor switches in power converters to slow down during transient operations, reducing dynamic overvoltage and allowing the system to operate within safe voltage limits, even when the solar cell's no-load voltage is high, by increasing the resistance value of the base wiring or adjusting the control voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power converter is designed for the maximum no-load voltage of the solar cell, then the converter can handle start-up conditions, but it operates well below its dimensioning limits during normal operation, resulting in an oversized converter
Solution Approach 1:
The patent applies dynamics by making the switching behavior of the semiconductor switches adaptive rather than static. The controller modifies the switching behavior based on operating conditions (transient vs. normal operation), allowing the converter to handle high no-load voltages during start-up without being permanently oversized. This dynamic adaptation resolves the contradiction by enabling the converter to meet peak voltage requirements only when needed, while operating efficiently at normal levels during regular operation.
2Reliability
If a chopper is added to reduce the intermediate circuit voltage during start-up, then the converter can operate within voltage limits, but the device complexity increases
Solution Approach 1:
The patent extracts the voltage reduction function from a separate chopper circuit and integrates it into the existing semiconductor switches of the power converter. By utilizing the switching capability already present in the converter and modifying its control behavior, the system achieves voltage limitation during start-up without adding external chopper components. This extraction principle resolves the contradiction by removing the need for additional hardware while maintaining voltage compliance.
Solution Approach 2:
The semiconductor switches in the power converter are made multi-functional by enabling them to perform both their normal power conversion function and the additional function of limiting voltage during start-up through modified switching behavior. This universal approach allows the existing switches to handle high no-load voltages without requiring dedicated chopper components, thereby reducing device complexity while ensuring voltage limit compliance.
3Reliability
If the switching behavior is slowed down during transient operation, then dynamic overvoltage is reduced and semiconductor switches are protected, but switching losses increase
Solution Approach 1:
The patent applies dynamics by making the switching behavior adaptive rather than static. The controller modifies the switching behavior based on operating conditions (transient vs. normal operation), allowing the converter to handle high no-load voltages during start-up without being permanently oversized. This dynamic adaptation resolves the contradiction by enabling the converter to meet peak voltage requirements only when needed, while operating efficiently at normal levels during regular operation.
Solution Approach 2:
The patent applies periodic action by implementing different switching behaviors for different operational phases. During transient start-up operation, the switching behavior is modified to reduce dynamic overvoltage, while during normal operation, the standard switching behavior is maintained. This periodic alternation between different switching modes resolves the contradiction by limiting slow switching (and associated losses) to only the transient phase when protection is needed, rather than continuously.
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 approach prevents semiconductor switch damage, allows for efficient startup despite high solar cell voltages, and ensures the power converter operates within safe limits, minimizing thermal overload risks while maintaining efficiency during normal operations.
Implementation Method 1
Solar cells are used to generate regenerative energy
Implementation Method 2
The power converter contains at least one semiconductor switch and a controller which controls a switching input of the semiconductor switch
Implementation Method 3
This is due to the internal resistance of the solar cells
Data Source
Figure 1
Figure 2
AI summary
In a solar module (2) with a solar cell (4) generating a DC voltage (U), and with a power converter (6) converting the DC voltage (U) fed into its input (8), which includes at least one semiconductor switch (14) and a control unit (20) controlling a switching input (18) of the semiconductor switch (14), the control unit (20) is designed such that in a transitional operation (Ü) of the solar module (2) it controls at least one of the semiconductor switches (14) in such a way that it exhibits a switching behavior that is slower than in normal operation (N) such that a dynamic overvoltage at the semiconductor switch (14) is reduced in such a way that the voltage applied to the semiconductor switch (14) does not exceed the reverse voltage of the semiconductor switch (14).In a method for operating a solar module (2), the control unit (20) in a transitional mode (Ü) of the solar module (2) controls the semiconductor switch (14) in such a way that it exhibits a switching behavior that is slower than in normal mode (N) so that a dynamic overvoltage at the semiconductor switch (14) is reduced in such a way that the voltage applied to the semiconductor switch (14) does not exceed the blocking voltage of the semiconductor switch (14).