Virtual Delta-T Trip Criterion for Solid State Power Controllers
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Solution Overview
Problem
Solid state power controllers (SSPCs) face challenges in replicating the trip curve of traditional circuit breakers, especially when current is within 100% to 150% of the rated current, due to the limitations of the commonly used I2t trip criterion.
Innovation Solution
Implementing a virtual ΔT trip criterion through a thermal model that simulates the temperature rise of electrical wiring, allowing the SSPC to trip when the temperature exceeds a preset threshold, which can be realized either via software or hardware as a first-order system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the I2t trip criterion is used for solid state power controller, then the device can be operated, but the trip curve cannot accurately match the circuit breaker when current is within 100%-150%
Solution Approach 1:
The patent changes the trip criterion parameter from I2t to a thermal model-based ΔT (temperature rise) criterion. This parameter change enables accurate matching of the trip curve with circuit breaker characteristics across the full current range including 100%-150% of rated current, while maintaining implementation feasibility through software or hardware modeling approaches
2Reliability
If the I2t trip criterion is combined with multiple modifications like no-trip threshold and thermal memory, then the trip curve matching improves, but the device complexity and difficulty of implementation increase
Solution Approach 1:
The patent merges the no-trip threshold, thermal memory, and trip curve matching functions into a unified thermal model framework. By representing the wiring as a first-order thermal system with integrated parameters (thermal mass, thermal resistance, ambient temperature compensation), the solution achieves accurate trip curve matching while simplifying the overall implementation structure compared to separate modifications
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 provides a more accurate trip curve closer to that of a traditional circuit breaker, effectively protecting electrical wires from thermal damage by modeling the physical temperature rise in real-time, enhancing the reliability and precision of power distribution control.
Implementation Method 1
The first order system model simulates a rise in temperature ΔT of the electrical wiring
Implementation Method 2
This model represents a first-order system, which may be implemented either by software or hardware. The first order system model simulates a rise in temperature ΔT of the electrical wiring
Data Source
AI summary
A virtual ΔT trip criterion is implemented in an electrical power distribution system to provide current-based tripping for a solid state power switching device. A first-order system model is implemented either by hardware or software to represent a rise in temperature of the electrical wire through which power is supplied. When the simulated temperature exceeds a threshold, the solid state power switching device may be tripped.