Hybrid Circuit Breaker Cooling for Faster High-Current Commutation
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Solution Overview
Problem
Hybrid circuit breakers become bulky and face substantial electrical stress when conducting larger nominal currents due to the semiconductor circuit's inability to withstand high over and fault currents, leading to increased thermal energy conversion and complex cooling challenges, which are exacerbated by the slow commutation of the electro-mechanical bypass switch.
Innovation Solution
Incorporating an active cooling device near the electro-mechanical bypass switch to cool its movable parts, reducing their size and mass, thereby enhancing the commutation speed and reducing the stress on the semiconductor circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the semiconductor circuit is made massive to withstand high over and fault currents, then the current capacity is improved, but the device size increases and becomes bulky
Solution Approach 1:
The patent divides the current path into two segments: the electro-mechanical bypass switch handles the high current stress during normal and fault conditions, while the semiconductor circuit only handles the commutation transient. This segmentation allows the semiconductor circuit to be much smaller while maintaining the overall current capacity of the device.
Solution Approach 2:
The electro-mechanical bypass switch performs the preliminary action of carrying the high overcurrent and fault current before the semiconductor circuit needs to intervene. By the time the semiconductor circuit is activated for commutation, the bulk of the current stress has already been handled by the bypass switch, allowing the semiconductor components to be sized for transient handling rather than continuous high current.
2Reliability
If the electro-mechanical bypass switch is made with more massive conductive and movable parts to handle higher currents, then the current capacity is improved, but the commutation speed decreases
Solution Approach 1:
The patent changes the temperature parameter of the electro-mechanical bypass switch by introducing active cooling. By maintaining lower operating temperatures, the switch can use lighter conductive and movable parts that still handle high currents reliably, while the reduced mass enables faster commutation speeds.
3Device complexity
If the semiconductor circuit is cooled through the outer surface of the housing, then the thermal management is simplified, but the cooling effectiveness is insufficient due to thermal resistance and capacitance
Solution Approach 1:
The patent extracts the cooling function from the housing structure and implements it as a separate active cooling device. This allows the cooling system to be optimized for thermal effectiveness rather than being constrained by housing material properties, while the cooling device can be independently controlled and sized appropriately for the thermal load.
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
The hybrid circuit breaker can handle higher nominal currents without increasing size or cost, maintaining current interruption capability and reducing electrical stress on the semiconductor circuit, allowing for smaller and more efficient designs.
Implementation Method 1
the electric energy is converted to thermal energy in the semiconductor circuit, which has to be absorbed and dissipated
Implementation Method 2
an active cooling device in a vicinity of the electro-mechanical bypass switch. The active cooling device is adapted to cool movable parts of the electro-mechanical bypass switch
Data Source
AI summary
A hybrid circuit breaker includes: input connectors configured to receive electrical energy from a power grid; output connectors configured to transfer electrical energy to a load; current paths, each connecting a respective input connector, of the input connectors, and a respective output connector, of the output connectors; an electro-mechanical bypass switch in at least one of the current paths; a semiconductor circuit in parallel with the electro-mechanical bypass switch; a controller configured to control a commutation from the current path in which the electro-mechanical bypass switch is arranged to the semiconductor circuit in a switching operation; and an active cooling device in a vicinity of the electro-mechanical bypass switch. The active cooling device is adopted to cool movable parts of the electro-mechanical bypass switch.