Solid State Circuit Interrupter With DESAT Trip and Galvanic Isolation
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Solution Overview
Problem
Solid state circuit interrupters provide faster tripping than conventional mechanical circuit interrupters but have not been optimally utilized, and they present different safety and wellness concerns that need improvement.
Innovation Solution
A circuit interrupter with a solid state switch module controlled by a gate driver and an analog trip circuit, utilizing a desaturation function and current sensors for rapid current interruption, along with separable contacts for galvanic isolation, and a method to monitor the health of solid state switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If solid state components are used to switch current, then tripping speed is improved, but safety and wellness concerns worsen
Solution Approach 1:
The circuit interrupter is divided into two distinct switching systems: solid state switch modules for fast tripping and separable contacts for safe isolation. This segmentation allows each component to specialize in its strength while compensating for the other's weaknesses, resolving the contradiction between speed and safety
Solution Approach 2:
The separable contacts act as an intermediary between the solid state switch modules and the load. When the solid state switches open, the separable contacts provide a visible, physically isolated break in the circuit, ensuring safety while the solid state components handle the fast response requirement
2Speed
If solid state switch module opens first, then fast tripping is achieved, but bounce arcs may occur
Solution Approach 1:
The control system is designed to open the separable contacts before opening the solid state switch modules. This preliminary action of the separable contacts establishes a physical gap that prevents bounce arcs when the solid state switches subsequently open, even though the solid state switches provide the final fast interruption
3Measurement precision
If multiple sensing outputs are used, then detection precision is improved, but device complexity increases
Solution Approach 1:
The current sensor is designed with multi-functionality, providing multiple outputs (normal sensor output proportional to current and OCD output that changes at threshold) from a single device. This allows the system to achieve high detection precision across different current conditions without proportionally increasing device complexity
Solution Approach 2:
The current sensor automatically provides different types of output signals based on the current level, with the OCD output self-activating when the threshold is reached. This self-service capability reduces the need for additional complex control logic while maintaining high detection precision
Data Source
AI summary
A circuit interrupter including a current sensor having a normal sensor output and an over current detection output, a solid state switch module structured to have a closed state to allow current to flow through the circuit interrupter and an open state to interrupt current flowing through the circuit interrupter, a gate driver structured to control the solid state switch module including a desaturation function output, wherein the gate driver is structured to cause the solid state switch module to interrupt current flowing through the circuit interrupter when the DESAT function output changes to the on state, and an electronic trip circuit structured to output a trip signal to the gate driver when the normal sensor output reaches a first threshold level or the overcurrent detection output changes to the on state.