Parallel Thomson Coil Actuator for Fast Fault Current Commutation
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Solution Overview
Problem
Existing hybrid circuit breakers face challenges in rapidly commutating fault currents from conventional vacuum interrupters to power electronic interrupters, due to high operational resistances in power electronic devices and limitations in mechanical switch opening speed.
Innovation Solution
An ultrafast actuator system utilizing a plurality of axisymmetric Thomson coils to rapidly rotate an armature, thereby quickly opening mechanical contacts and facilitating fast commutation of fault currents between vacuum and power electronic interrupters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional Thomson coil actuator with a single Thomson plate is used, then the structure is simple, but the opening velocity is reduced and the commutation time is increased due to high moving mass
Solution Approach 1:
The single Thomson plate is divided into multiple Thomson plates (first, second, third, and fourth Thomson plates) arranged around the axis of rotation. Each plate has a reduced mass compared to a single large plate, allowing faster acceleration and higher opening velocity while maintaining the required total thrust through parallel operation of multiple plates and coils
Solution Approach 2:
Multiple Thomson coils are combined to operate simultaneously on multiple Thomson plates. The coils are positioned at different angular locations around the axis of rotation and are energized in a sequence that produces cumulative rotational force, achieving high-speed commutation through combined action of multiple coil-plate pairs
2Speed
If power electronic interrupters are used to achieve fast interruption, then the interruption speed is improved, but the operational resistance causes high power losses
Solution Approach 1:
The Thomson coil actuator performs preliminary action by rapidly opening the mechanical switch before the fault current reaches the power electronic interrupter. This pre-commutation reduces the duration that the power electronic device must handle high current, minimizing I²R losses while still achieving fast overall interruption
Solution Approach 2:
The mechanical switch actuated by the Thomson coil serves as an intermediary that handles the bulk of the fault current interruption. The power electronic interruptor only needs to handle the commutated current portion, reducing its power losses while maintaining fast interruption capability
3Force
If the mass of the Thomson plate is increased to provide sufficient force, then the force is improved, but the opening velocity is reduced and commutation time is increased
Solution Approach 1:
The total required force is distributed across multiple lighter Thomson plates instead of concentrating it in a single heavy plate. Each plate experiences lower inertial resistance, allowing faster acceleration while the combined force from all plates achieves the required total thrust for reliable commutation
Solution Approach 2:
The Thomson coils are energized in a periodic sequence that produces impulsive forces on the Thomson plates. This periodic energization pattern creates a series of force pulses that accumulate to achieve the required total force while maintaining high acceleration and short commutation time
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 Thomson coil actuator system achieves rapid commutation of fault currents, reducing energy loss and enabling quicker interruption of fault currents, thus improving the efficiency and reliability of hybrid circuit breakers.
Implementation Method 1
An actuator with a support, an armature that is rotatable with respect to the support about an axis of rotation, and a plurality of Thomson coils that are each spaced from the axis of rotation
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
An actuator (4), which is a part of a combination that includes a pair of circuit interrupters (12, 16), advantageously employs a plurality of Thomson coils (88) that are electrically connected in parallel and that interact with a corresponding set of Thomson plates (40) of a rotatable armature (24) in order to perform useful work in a rapid fashion. In one embodiment, the useful work is to commutate current from one circuit interrupter to the other.