Solid State Power Controller Current Sharing via Dual Amplifier Detection
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Solution Overview
Problem
The challenge in using solid state power controllers (SSPCs) in high voltage aircraft primary distribution systems is the imperfect current sharing between paralleled SSPCs due to manufacturing tolerances, leading to difficulties in simultaneous switching during short circuits or high inrush currents, and the need for accurate and high-bandwidth load current signals for control functions.
Innovation Solution
A solid state power controller design featuring a load current detection unit with both high-bandwidth and high-accuracy load current amplifiers, integrated into an application-specific integrated circuit (ASIC), allowing for precise load current measurement and synchronization of SSPCs connected in parallel, ensuring simultaneous switching and accurate control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple SSPCs are connected in parallel to achieve larger current ratings, then flexibility and current capacity are improved, but current sharing between SSPCs becomes imperfect due to manufacturing tolerances
Solution Approach 1:
The patent implements a feedback mechanism where load current signals from each paralleled SSPC are continuously monitored and fed back to a control unit. The control unit processes these signals and generates corrective control commands to adjust the switching of each SSPC, ensuring equal current sharing despite manufacturing tolerances in switch resistance.
Solution Approach 2:
The patent dynamically adjusts switching parameters (such as switching timing and duty cycle) of individual SSPCs based on real-time load current measurements. By changing these parameters in response to measured conditions, the system compensates for manufacturing variations and achieves balanced current distribution among paralleled SSPCs.
2Speed
If load current signal bandwidth is increased to improve temporal resolution for control functions, then switching response speed is improved, but signal accuracy deteriorates
Solution Approach 1:
The patent segments the load current signal processing into two distinct paths: a high-bandwidth path for temporal resolution and switching control, and a high-accuracy path for precise measurement. Each path is optimized for its specific function, with the high-bandwidth path filtering out noise for fast response and the high-accuracy path using lower bandwidth for precise current measurement.
Solution Approach 2:
The patent introduces an intermediary signal processing stage that separates the load current signal into different frequency components. High-frequency components are routed to the high-bandwidth amplifier for fast switching control, while low-frequency components are routed to the high-accuracy amplifier for precise measurement, thus mediating between the conflicting requirements.
3Reliability
If SSPCs are switched on simultaneously to handle high inrush current, then current sharing is improved, but risk of single SSPC tripping increases
Solution Approach 1:
The patent implements preliminary action by pre-coordinating the switching commands for all paralleled SSPCs before the actual switching event. The control unit generates synchronized gate signals that are applied to all SSPCs simultaneously, ensuring they turn on at the exact same moment and share the inrush current equally, preventing any single SSPC from being overloaded.
4Speed
If SSPCs are switched off quickly to protect against short circuits, then protection speed is improved, but current sharing control becomes more difficult
Solution Approach 1:
The patent implements a two-stage protection mechanism:第一阶段 uses high-bandwidth signals for immediate protection response that skips detailed current sharing control, and第二阶段 resumes normal current sharing control once the fault condition is cleared. This allows the system to respond quickly to short circuits while maintaining current sharing accuracy during normal operation.
Data Source
AI summary
A solid state power controller configured to supply electric power from a power supply to at least one load, comprises: a solid state switching device having a first terminal (D) connected to the power supply, and a second terminal (S) connected to the load, the solid state switching device configured to switch between an OFF operation mode in which the second terminal (S) is electrically disconnected from the power supply, and an ON operation mode in which the second terminal (S) is electrically connected to the power supply, and a load current detection unit configured to detect a load current through the solid state switching device; wherein the load current detection unit comprises a first load current amplifier and a second load current amplifier.