Common-Mode Reactor Saturation Detection via Auxiliary Windings

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Solution Overview

Problem

Conventional technologies lack a method to simultaneously measure the saturation state of a common-mode reactor and determine the noise reduction effect, as existing solutions cannot perform these measurements simultaneously.

Innovation Solution

A power conversion device with a common-mode reactor featuring auxiliary windings and a detection circuit that superimposes an alternating current on one winding and measures the winding voltage in the other to detect saturation, allowing for continuous monitoring of the saturation state during normal operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional current sensor technology is used to detect saturation state, then the same terminal output voltage can be utilized for both current measurement and saturation detection, but these two measurements cannot be performed simultaneously

Engineering Contradiction:

Improvedual measurement capabilityVSAvoidsimultaneous measurement timing

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent divides the detection function into separate components: a first auxiliary winding for current measurement and a second auxiliary winding for saturation detection. This segmentation allows both measurements to occur simultaneously without interference, as each winding serves its specific detection purpose independently while being magnetically coupled to the common-mode reactor core.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces auxiliary windings as intermediary elements that enable simultaneous measurements. The first auxiliary winding acts as an intermediary for current measurement, while the second auxiliary winding serves as an intermediary for saturation state detection through induced voltage. These intermediaries allow both functions to coexist without conflicting for the same terminal output.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If no dedicated detection device is implemented, then the device complexity is reduced, but the saturation state of the common-mode reactor cannot be properly detected

Engineering Contradiction:

Improvesaturation detection accuracyVSAvoiddetection circuit structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The common-mode reactor performs self-diagnosis through its own auxiliary windings. The magnetic core's saturation state is detected by measuring the induced voltage in the second auxiliary winding, which naturally reflects the core's magnetic condition. This self-service approach enables reliable saturation detection without requiring external complex testing equipment or additional sensors.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The auxiliary windings serve multiple functions: they are integrated into the common-mode reactor structure and simultaneously enable both current measurement (first auxiliary winding) and saturation detection (second auxiliary winding). This multi-functionality reduces the need for separate dedicated detection devices, balancing reliability with acceptable device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

Enables proper detection of the saturation state and noise reduction effect of the common-mode reactor, allowing for continuous diagnosis during normal operation and enhancing resistance to disturbances.

Implementation Method 1

a winding voltage generated in the second auxiliary winding by the superimposed current

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS11442092B2Power conversion device and method for detecting magnetic saturation of common-mode reactor

Publication Date: 2022.09.13 MITSUBISHI ELECTRIC CORP

AI summary

A power conversion device includes a semiconductor power converter that converts direct current power into alternating current power for a motor, a common-mode reactor having first and second auxiliary windings added thereto, the common-mode reactor reducing common-mode current that may flow between the semiconductor power converter and the motor, a signal generator that superimposes an alternating current on the first auxiliary winding, and a detection circuit that detects a saturation state of the common-mode reactor on the basis of the superimposed current superimposed on the first auxiliary winding and a winding voltage generated in the second auxiliary winding by the superimposed current.