Medium-Voltage LISN Circuit for Parasitic Impedance Control
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Solution Overview
Problem
Existing line impedance stabilization networks (LISNs) are inadequate for medium-voltage applications due to high parasitic parameters in inductors and capacitors, leading to deviations in impedance and noise coupling, which compromise electromagnetic compatibility (EMC) certification of wide-bandgap power electronics systems.
Innovation Solution
A single-phase, single-stage LISN design with parasitic parameter minimization techniques, including the use of coupled PCB traces for capacitor ESL reduction and optimized inductor design to suppress parasitic effects, ensuring compliance with CISPR 16-1-2 standards for 1.5 kV, 75 A, and 30 MHz measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional inductors and capacitors are used in LISN for medium-voltage applications, then the basic filtering function is provided, but high parasitic parameters cause impedance deviations and noise coupling
Solution Approach 1:
The patent introduces parasitic-inductance compensation capacitors that generate a parasitic inductance effect to counterbalance the harmful parasitic inductance of the inductor. Similarly, parasitic-capacitance compensation inductors generate parasitic capacitance to offset the harmful parasitic capacitance of capacitors. This converts the harmful parasitic effects into beneficial compensation mechanisms that improve impedance stability.
Solution Approach 2:
The patent applies preliminary anti-action by pre-configuring compensation networks that anticipate and counteract parasitic effects before they degrade performance. The parasitic-inductance compensation capacitors and parasitic-capacitance compensation inductors are designed to proactively neutralize parasitic parameters, preventing impedance deviations and noise coupling before they occur.
2Measurement precision
If standard LISN design is used, then basic EMC testing capability is provided, but parasitic parameter deviations compromise certification accuracy for wide-bandgap power electronics
Solution Approach 1:
The patent implements feedback mechanisms through compensation networks that continuously counteract parasitic parameter variations. The parasitic-inductance compensation capacitors and parasitic-capacitance compensation inductors form feedback loops that detect and correct impedance deviations caused by parasitic effects, maintaining measurement precision across varying operating conditions.
Solution Approach 2:
The patent employs parameter changes by selecting specific capacitor and inductor values designed to counterbalance parasitic parameters. The parasitic-inductance compensation capacitors are chosen with capacitance values that generate appropriate parasitic inductance, while parasitic-capacitance compensation inductors are selected with inductance values that produce compensating parasitic capacitance, thereby maintaining precise noise coupling characteristics.
3Reliability
If parasitic compensation networks are added to reduce parasitic effects, then impedance stability improves, but device complexity increases
Solution Approach 1:
The patent merges the compensation functions into the existing LISN circuit structure. The parasitic-inductance compensation capacitors are integrated with the input capacitor, and the parasitic-capacitance compensation inductors are combined with the main inductor, creating unified compensation networks that improve impedance stability without requiring entirely separate compensation circuits.
Solution Approach 2:
The compensation networks serve multiple functions simultaneously: they provide parasitic parameter compensation, maintain impedance stability, enable noise coupling, and support EMC testing. This multi-functionality reduces the need for additional dedicated components and simplifies the overall device complexity despite the added compensation capability.
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 proposed LISN achieves stable high-frequency noise coupling and isolation, meeting EMC certification requirements by minimizing parasitic effects, thereby facilitating the integration of wide-bandgap power electronics into modern energy systems.
Implementation Method 1
a first capacitor that is connected to the first circuit node, that defines a third circuit node, and that has a first parasitic inductance
Implementation Method 2
an inductor that defines a first circuit node and a second circuit node and that has a first parasitic resistance, a second parasitic resistance, and a first parasitic capacitance
Implementation Method 3
A configuration of the first circuit node generates a first mutual inductance that is based on the first parasitic resistance, the second parasitic resistance, the first parasitic capacitance, the first parasitic inductance, the third parasitic resistance, the second parasitic inductance, and the fourth parasitic resistance
Data Source
AI summary
A line impedance stabilization network (LISN) is disclosed. The LISN includes an inductor that defines a first circuit node and a second circuit node and that has a first parasitic resistance, a second parasitic resistance, and a first parasitic capacitance. The LISN further includes a first capacitor that is connected to the first circuit node, that defines a third circuit node, and that has a first parasitic inductance, and a third parasitic resistance. The LISN further includes a second capacitor that is connected to the second circuit node, that defines a fourth circuit node, and that has a second parasitic inductance and a fourth parasitic resistance. The LISN further includes a resistor that is connected to the fourth circuit node and the third circuit node. A configuration of the first circuit node generates a first mutual inductance. A configuration of the second circuit node generates a second mutual inductance.