Parallel SSPC Current Sharing for Fault and Inrush Control
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Solution Overview
Problem
The implementation of solid state power controllers (SSPCs) in parallel for high voltage aircraft primary distribution systems faces challenges due to imperfect current sharing, manufacturing tolerances, and issues with switching off quickly during short circuits or handling high inrush currents, leading to potential tripping of individual SSPCs.
Innovation Solution
A power distribution system that connects at least two SSPCs in parallel, each with a current detection unit to determine a common load current, allowing synchronized control of the SSPCs to manage load currents and prevent tripping, ensuring simultaneous switching and handling of high inrush currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple SSPCs are connected in parallel to achieve larger current ratings, then the adaptability and current handling capability are improved, but the current sharing becomes imperfect and control complexity increases
Solution Approach 1:
The patent combines multiple SSPCs in parallel configuration to achieve larger current ratings. The control sections of multiple SSPCs are interconnected through communication lines to share control signals and coordinate switching operations, effectively merging their functionality while maintaining individual current detection and protection capabilities.
Solution Approach 2:
Each SSPC includes a current detection unit that continuously monitors the load current. The control sections receive feedback signals from these detection units and adjust their switching operations accordingly. This feedback mechanism ensures proper current sharing and coordinated tripping among parallel SSPCs when fault conditions occur.
2Speed
If SSPCs are switched off quickly during short circuits, then the protection speed is improved, but the risk of individual SSPC tripping due to manufacturing tolerances increases
Solution Approach 1:
The control sections of parallel SSPCs are connected through communication lines that allow sharing of tripping signals. When one SSPC detects a fault condition requiring rapid shutdown, it sends a signal through the communication network to all other parallel SSPCs, ensuring they all switch off simultaneously rather than individually, which prevents reliability issues from manufacturing tolerances.
Solution Approach 2:
The system establishes communication links and synchronization protocols between parallel SSPCs before fault conditions occur. This preliminary coordination ensures that when a short circuit happens, all SSPCs are already prepared to switch off simultaneously based on shared fault detection, eliminating the risk of staggered tripping due to tolerance variations.
3Power
If SSPCs handle high inrush currents, then the power distribution capability is improved, but the risk of false tripping due to current detection sensitivity increases
Solution Approach 1:
Current detection units in each SSPC continuously monitor load current and provide feedback to control sections. The control sections analyze this feedback in the context of system-wide conditions communicated through control lines, allowing them to distinguish between normal inrush currents during startup and actual fault conditions, thereby preventing false tripping while maintaining high power distribution capability.
Solution Approach 2:
Multiple SSPCs operate in parallel with interconnected control sections that share current detection data. This merged monitoring approach allows the system to evaluate inrush currents from multiple perspectives simultaneously, cross-validating readings and preventing individual SSPCs from falsely tripping due to transient conditions that are normal when multiple units share the load.
Data Source
Figure 1
AI summary
A power distribution system (10) configured to supply electric power from a power supply (14) to at least one load (16a, 16b, 16c), the power distribution system (10) comprising at least two solid state power controllers (12a, 12b, 12c) connected in parallel, each solid state power controller (12a, 12b, 12c) comprising: a solid state switching device (24a, 24b, 24c) having a first terminal (D) connected to the power supply (14), and a second terminal (S) connected to the load (16a, 16b, 16c), the solid state switching device (24a, 24b, 24c) configured to switch between an OFF operation mode in which the second terminal (S) is electrically disconnected from the power supply (14), and an ON operation mode in which the second terminal (S) is electrically connected to the power supply (14), and a load current detection unit (30a, 32a; 30b, 32b; 30c, 32c) configured to detect a load current (28a, 28b, 28c) through the solid state switching device (24a, 24b, 24c); wherein the power distribution system (10) is configured to determine a common load current (54) based on the load currents (28a, 28b, 28c) detected by the load current detection units (30a, 32a; 30b, 32b; 30c, 32c) of the at least two solid state power controllers (12a, 12b, 12c) connected in parallel and to control operation of the solid state switching devices (24a, 24b, 24c) of the at least two solid state power controllers (12a, 12b, 12c) connected in parallel according to the common load current (54).