Solid State Circuit Breaker PWM Control for Fault Current Limiting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Solid state circuit breakers face challenges in distinguishing between fault and temporary overload conditions quickly, often leading to unnecessary tripping and potential damage due to their fast reaction time in low voltage AC systems.
Innovation Solution
A solid state circuit breaker apparatus comprising a solid state switch, current sensor, and control circuit that uses pulse width modulation to generate control pulses based on maximum interruption current and power factor, allowing the switch to open and close in a pattern that limits let-through current to a threshold level, thereby controlling the flow of current and determining trip time based on detected current levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the solid state circuit breaker opens the switch immediately upon detecting overcurrent, then fault protection is achieved, but unnecessary tripping occurs during temporary overload conditions
Solution Approach 1:
The system performs preliminary analysis of the current condition before executing the tripping action. By evaluating the current surge characteristics in advance and comparing them against fault patterns, the system determines whether immediate interruption is necessary or whether the condition represents a temporary overload that should be permitted.
Solution Approach 2:
The circuit breaker changes its operational parameters based on the detected current characteristics. When a temporary overload is detected, the system adjusts its tripping thresholds and response time, allowing the circuit to continue operating. When genuine fault conditions are identified, the parameters are adjusted to enable immediate interruption.
2Reliability
If the circuit breaker allows the circuit to operate for a period before opening the switch, then unnecessary tripping is reduced, but the solid state switch may be damaged by excessive current
Solution Approach 1:
The system employs periodic monitoring and evaluation of current conditions, using pulsed control signals to manage the switching operation. This periodic action allows the circuit to operate through temporary overloads while maintaining continuous surveillance to detect genuine faults that require interruption.
Solution Approach 2:
The control circuit acts as an intermediary between the current sensor and the solid state switch, mediating the decision to trip or continue operation. This intermediary layer processes current measurements, applies discrimination logic, and controls the switching timing to protect the solid state components while allowing temporary overloads.
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A solid state circuit breaker apparatus includes a solid state switch (230), a current sensor (210), and a control circuit (240). The control circuit is programmed to operate the solid state switch by, in response to receipt of a signal from the current sensor indicating that an overcurrent condition exists: (i) using pulse width modulation to generate a set of control pulses; and (ii) using the control pulses to trigger the solid state switch to open and close in a pattern that corresponds to the control pulses, and thus limit an amount of let- through current that the solid state switch may pass to a load. The amount of let-through current that the solid state switch may pass to the load may be, for example, a threshold level above which the overcurrent condition will exist.