Embedded Current Transformer With RLC Ringing Damping
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Solution Overview
Problem
Current transformers in power electronics face challenges in high-bandwidth current measurement and ringing suppression, particularly with wide band-gap semiconductors, as they either lack galvanic isolation, introduce mechanical choke-points, or have limited bandwidth, which impede the functionality of multi-chip power modules.
Innovation Solution
A current transformer with a magnetic core and a parallel RLC filter is integrated into multi-chip power modules, allowing for high-bandwidth current measurement and ringing suppression by selecting capacitance, inductance, and resistance values to maintain a minimum effective insertion impedance across a known frequency range, thereby distinguishing between desired and undesired frequency components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional current transformers are used, then galvanic isolation is provided, but mechanical choke-points are introduced which increase loop inductance and degrade transient behavior
Solution Approach 1:
The patent replaces the traditional mechanical current transformer structure with an integrated magnetic core current transformer that is embedded within the multichip module substrate. This substitution eliminates the need for external mechanical choke-points while maintaining galvanic isolation through magnetic coupling, thereby reducing loop inductance and improving transient response.
2Speed
If resistive shunts are used for current measurement, then high bandwidth is achieved, but galvanic isolation is lost
Solution Approach 1:
The patent introduces a magnetic core as an intermediary between the primary current-carrying conductor and the secondary measurement circuit. This magnetic intermediary enables galvanic isolation while maintaining high bandwidth current measurement capability, as the magnetic coupling preserves signal fidelity without requiring direct electrical contact.
3Power
If wide band-gap semiconductors are used, then power electronics performance is improved, but ringing and overshoot are excited due to fast di/dt and dv/dt
Solution Approach 1:
The patent converts the harmful ringing effect into a beneficial measurement signal by using the same parasitic resonance that causes ringing as the operating principle for the current transformer. The magnetic core and winding configuration are designed to couple with the parasitic inductance and capacitance, transforming the ringing into a measurable signal that provides both current measurement and damping effects.
4Volume of moving object
If current measurement is embedded in multichip modules, then compactness is improved, but device complexity increases
Solution Approach 1:
The patent merges the current measurement function with the multichip module structure by integrating the magnetic core and windings directly into the module substrate. This consolidation combines multiple functions (current measurement, galvanic isolation, and transient response optimization) into a single integrated structure, reducing overall device volume while managing complexity through unified design.
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 enables accurate high-bandwidth current measurement while suppressing parasitic-induced ringing, maintaining system stability and operational integrity without increasing the device's dimensions or introducing additional geometric constraints.
Implementation Method 1
a magnetic core current transformer having an insertion impedance Zin and turns ratio N
Implementation Method 2
a filter, the filter comprising a capacitance CP, an inductance LP and a resistance RP; wherein CP, LP and RP are selected such that Zin remains above a minimum effective value across a known frequency range
Data Source
AI summary
The current disclosure relates to the design of an apparatus for enhancing the operation and reliability of high-power multi-chip modules, which are used in the design and implementation of power electronics converters. This apparatus is especially useful for modules containing recently-commercialized, high-performance wide band-gap semiconductors such as Silicon Carbide (SiC), which commonly emit undesirable high-frequency ringing and oscillation in the “Near-RF” spectral band between 1-30 MHz. The disclosed apparatus provides near-complete elimination of this high frequency spectral content, while leaving the desired frequency range (1-100 kHz) of the module unaffected. In addition to the suppression of this undesirable high-frequency content, the disclosed apparatus also provides for accurate, galvanically-isolated, high-bandwidth, real-time current measurement, which is essential for some types of power electronics converters. Prior to the disclosure of this apparatus, these two features (ringing suppression and current measurement) have required physically-separate circuits for implementation, which increases the size, weight, and cost of the final implementation. The apparatus disclosed here provides both of these features in simple circuit topology that can be implemented compactly inside the geometry of a multi-chip power module.