High-Energy Surge Current Limiter Using Magnetic Coupling
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Solution Overview
Problem
High-energy surge currents in power converter modules, particularly in multilevel voltage-source converters, are difficult to control during faults, leading to potential explosions, arc formation, and interference due to the uncontrolled release of energy, with existing solutions like RL combinations and fast fuses being inefficient or costly.
Innovation Solution
A high-energy surge current limiter using a primary winding magnetically coupled to a shorted secondary winding, where the secondary winding's ohmic resistance converts stored energy into heat, and the primary winding's inductive proportion limits current rise speed, effectively reducing energy and frequency of short-circuit currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RL combinations (resistor and inductance in parallel circuit) are used to limit surge current, then the shock current can be limited, but the mechanical configuration is material intensive, large, and adds significant stray inductance to the DC link
Solution Approach 1:
The patent replaces the mechanical RL combination with a magnetic coupling system consisting of a primary winding connected in series with the DC link and a secondary winding short-circuited. This substitution eliminates the need for massive resistors and inductors, significantly reducing mechanical complexity and stray inductance while maintaining surge current limitation capability through electromagnetic induction.
Solution Approach 2:
The patent changes the operational parameters of the limiting device by using a magnetically coupled system where the secondary winding's resistance and the primary winding's inductance dynamically respond to surge conditions. The magnetic coupling allows the system to adapt its limiting characteristics based on the surge severity, providing efficient protection without the fixed, bulky configuration of traditional RL combinations.
2Reliability
If fast fuses are used for shock current limitation, then the boundary conditions for shock current can be limited, but double-sided cooling is required and they are comparatively costly
Solution Approach 1:
The patent replaces fast fuses with a magnetic coupling-based limiting system that uses electromagnetic induction rather than thermal melting. This substitution eliminates the need for complex cooling systems and reduces manufacturing costs while maintaining effective shock current limitation through the natural electromagnetic response of the coupled windings.
3Reliability
If serial RL combinations are used for current limitation, then the protective effect in high power range is achieved, but the negative effects of high inductance on commutation in normal operation are significant
Solution Approach 1:
The patent segments the current limitation function into two separate windings: the primary winding handles the high-power protection function with appropriate inductance, while the secondary winding provides a low-inductance path that minimizes impact on normal commutation operations. This segmentation allows each component to be optimized for its specific function without compromising the other.
Solution Approach 2:
The magnetic coupling acts as an intermediary between the primary and secondary circuits, allowing the primary winding to limit surge currents while the secondary winding provides a path that minimizes interference with normal operations. The magnetic field serves as the mediator that transfers energy during surges while maintaining operational performance during normal commutation.
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 solution reliably limits high-energy surge currents with minimal impact on normal operation, reducing energy by up to 90% and stray inductance, while being cost-effective and scalable, with only copper losses during DC power application.
Implementation Method 1
the secondary winding being shorted... the secondary winding's ohmic resistance converts stored energy into heat
Implementation Method 2
the primary winding's inductive proportion limits current rise speed... effectively reducing energy and frequency of short-circuit currents
Implementation Method 3
A high-energy surge current limiter using a primary winding magnetically coupled to a shorted secondary winding
Data Source
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AI summary
The aim of the invention is a high-energy surge current limiter for a voltage link converter which, in a converter module, allows reliable limiting of the surge current in the event of a failure, even in the case of high and extremely high energy amounts, but has a relatively small influence on the switching of the converter module in normal operation. This aim is achieved in that the high-energy surge current limiter comprises a primary winding having two electrical connections and a secondary winding magnetically coupled to the primary winding, wherein the secondary winding is short-circuited.