DC-DC Converter Current Bypass for Series Reliability
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Solution Overview
Problem
Distributed power harvesting systems face reliability issues due to component malfunctions in series and parallel connections, leading to disruptions in power supply and increased maintenance costs, especially in hard-to-reach locations like rooftops.
Innovation Solution
Incorporating current bypass paths in DC-DC converters to prevent open circuits in series connections and short circuits in parallel connections, allowing other converters to maintain operation even if one fails, with a controller selectively engaging buck or boost portions and bypass paths to ensure continuous power flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If DC-DC converters are connected in series to accumulate power from multiple low-voltage sources, then the output voltage and power are improved, but the system reliability deteriorates because an open circuit failure in one converter stops current flow in the entire series connection
Solution Approach 1:
The patent segments the series connection into independent parallel paths by introducing bypass circuits for each DC-DC converter. This allows the system to maintain series power accumulation while creating alternative current paths that isolate failures to individual converters rather than the entire system.
Solution Approach 2:
The patent implements bypass circuits as preventive measures before failures occur. These bypass paths are designed in advance to catch potential open circuit failures, ensuring that when a converter fails, the bypass circuit immediately activates to maintain system operation without interruption.
2Power
If DC-DC converters are connected in parallel to increase current capacity, then the current output is improved, but the system reliability deteriorates because a short circuit in one converter reduces voltage to zero across the parallel connection
Solution Approach 1:
The patent segments the parallel connection by introducing individual bypass circuits for each converter. This segmentation isolates potential short circuit failures to specific converters, preventing voltage collapse across the entire parallel connection and allowing other converters to continue operating.
Solution Approach 2:
The bypass circuit acts as an intermediary element between the parallel-connected converters. When a short circuit occurs in one converter, the bypass circuit mediates by providing an alternative path that prevents the short from affecting other converters, thus maintaining system voltage and operation.
3Reliability
If bypass circuits are added to improve reliability, then the system reliability is improved, but the device complexity increases due to additional circuit components
Solution Approach 1:
The bypass circuit is designed with multi-functionality to reduce overall system complexity. The same bypass circuit structure serves both series and parallel connection configurations, and can handle both open circuit and short circuit failures. This universal design reduces the need for different bypass solutions for different failure modes.
Solution Approach 2:
The patent utilizes parameter changes in the bypass circuit design, specifically using diodes with appropriate forward voltage drops and switches with specific on-resistances, to achieve reliable failure bypassing while minimizing the number of components needed. By optimizing these parameters, the bypass circuit becomes more efficient and less complex.
Data Source
AI summary
A converter circuit providing multiple current bypass routes between the output leads to provide reliability in a series connection of several converters. If the converter malfunctions due to component failure, the current bypass routes provide a path for the current that views the malfunctioning converter as substantially a short. Diodes prevent backflow into the power source connected to the converter. Redundancy is provided in the bypass portions of the converter circuit that provides alternate parallel paths in case a defective component in one of the paths opens the circuit along that path. In one example, the converter is implemented as a buck plus boost converter where either the buck or the boost portion or both are operative responsive to a controller controlling the switches of both portions. Most of the converter circuit may be implemented in an integrated circuit.