DC/DC Power-Side Shutdown Using Short-Circuit Reverse Current Relief
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Solution Overview
Problem
Power converters face risks of damage and serious consequences such as fires due to large reverse currents generated by abnormal operation conditions like reverse connection, reverse injection, or multi-point grounding at the power side, especially in systems with multiple DC power supplies connected in parallel.
Innovation Solution
A power-side shutdown protection method that short circuits the positive and negative electrodes of a target DC/DC conversion circuit, controls the connected switch to turn off, and verifies its actual turn-off status to safely disconnect the power side from the DC power supply, reducing turn-off currents and risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a switch at the power side is used to disconnect DC power supplies in abnormal conditions, then the power side can be protected from reverse currents, but the switch may fail to turn off completely causing continued reverse current flow and potential damage
Solution Approach 1:
The patent applies beforehand cushioning by introducing a short-circuiting branch with switching transistor Q before the main switch S1 turns off. This short-circuiting branch provides a safe discharge path for the DC power supply, cushioning the impact of potential switch failure and preventing reverse current damage to the photovoltaic modules.
Solution Approach 2:
The patent uses an intermediary approach by introducing a short-circuiting branch with switching transistor Q as a mediator between the DC power supply and the main switch S1. This intermediary structure ensures that even if S1 fails to turn off, the reverse current can still be safely discharged through the short-circuiting branch, preventing damage.
2Power
If multiple DC power supplies are connected in parallel to increase power capacity, then the system can handle higher power loads, but reverse currents can flow through multiple paths causing larger total reverse current and increased damage risk
Solution Approach 1:
The patent applies segmentation by dividing the power supply system into independent modules, each with its own short-circuiting branch. This segmentation isolates reverse current paths, ensuring that reverse current from one module does not affect other modules, thereby limiting the total reverse current magnitude even when multiple power supplies are connected in parallel.
Solution Approach 2:
The patent implements local quality by providing dedicated short-circuiting branches for each DC power supply module. Each module has its own local protection mechanism, ensuring that reverse current is contained within individual modules and does not propagate across the entire parallel-connected system.
3Reliability
If a short-circuiting branch with switching transistor is added to ensure safe shutdown, then reverse current protection is improved, but the device complexity and hardware costs increase
Solution Approach 1:
The patent applies universality by designing the short-circuiting branch with switching transistor Q to serve multiple functions: it acts as a protection mechanism during abnormal conditions, provides a discharge path for the DC power supply, and can be integrated into existing circuit topologies without requiring completely separate protection circuits.
Solution Approach 2:
The patent merges the protection function into the existing circuit structure by integrating the short-circuiting branch with the main switch S1 and DC power supply connection. This merging approach allows the protection mechanism to be implemented without adding completely separate hardware, thereby reducing overall device complexity.
Data Source
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AI summary
The present disclosure relates to the technical field of power electronics, and a power-side shutdown protection method for a power conversion circuit, a power converter, a combiner box, and a power conversion system are provided. With the power-side shutdown protection method, the DC/DC conversion circuit connected to the DC power supply with a reverse current is determined as a target DC/DC conversion circuit, and a positive electrode and a negative electrode at the power side of the target DC/DC conversion circuit are short circuited to provide another current circuit for some reverse currents, thereby reducing a turn-off current of a switch connected to the DC power supply with the reverse currents. A switch connected to the target DC/DC conversion circuit is controlled to be turned off to reduce the reverse current while reducing the risk of shutdown. Then, only in a case of determining the switch controlled to be turned off is actually turned off, the positive electrode and the negative electrode at the power side of the target DC/DC conversion circuit are stopped being short circuited, thereby avoiding not effectively reducing the reverse current after stopping short circuiting the positive electrode and the negative electrode at the power side of the target DC/DC conversion circuit due to the turn-off fault of the switch.