Circulating-Current Reducing Circuit for Parallel Transformers

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Solution Overview

Problem

Existing transformer devices with different specifications connected in parallel experience circulating currents, leading to ringing and potential damage, and existing solutions require complex control circuits to manage these currents, increasing cost and complexity.

Innovation Solution

A simplified circulating-current reducing circuit using diode and resistance element circuits connected between the primary coils of transformer devices to absorb and direct circulating currents, eliminating the need for a control circuit and reducing ringing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a control circuit with multiple switches is used to control circulating current, then the accuracy of circulating current control is improved, but the device complexity and cost increase

Engineering Contradiction:
Improveaccuracy of circulating current controlVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the control circuit from the system by using passive components (diodes and resistors) that automatically handle circulating current without requiring active control. This removes the complexity of control circuits while maintaining circulating current suppression functionality.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The circulating current suppression is achieved through self-service mechanisms where diodes and resistors automatically respond to circulating current conditions without external control. The circuit components inherently perform the suppression function based on their electrical characteristics, eliminating the need for control circuits.

Inventive Principle:
Principle #25Self-service

2Reliability

If a control circuit with multiple switches is used to control circulating current, then the circulating current suppression capability is improved, but the number of components and device size increase

Engineering Contradiction:
Improvecirculating current suppression capabilityVSAvoidnumber of components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes the control circuit and its multiple switches from the system, replacing them with a simpler configuration of diodes and resistors connected in parallel with the transformer primary coils. This extraction eliminates unnecessary components while maintaining the essential circulating current suppression function.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses simple, passive components (diodes and resistors) that are inexpensive and require no complex control logic. These components provide reliable circulating current suppression without the cost and complexity of active control circuits with multiple switches.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Adaptability or versatility

If transformer devices with different specifications are connected in parallel, then the circuit functionality and power capacity are improved, but circulating current occurs causing ringing and potential damage

Engineering Contradiction:
Improvecircuit functionalityVSAvoidcirculating current and ringing
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces diodes and resistors as intermediary components connected in parallel with each transformer primary coil. These intermediaries provide a controlled path for circulating current, preventing it from causing harmful ringing effects while allowing transformer devices with different specifications to operate in parallel.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the harmful circulating current into a beneficial effect by providing a controlled dissipation path through resistors. The circulating current that would otherwise cause ringing and damage is redirected through resistive elements where it is safely dissipated as heat, transforming a harmful phenomenon into a controlled and harmless process.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

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

Effectively suppresses circulating currents and prevents ringing in transformer units with differing specifications, simplifying the device configuration and reducing costs while ensuring operational safety.

Implementation Method 1

A simplified circulating-current reducing circuit using diode and resistance element circuits connected between the primary coils of transformer devices to absorb and direct circulating currents

Methodology Applied
Scientific EffectElectrical Resistance: Electrical Resistance

Data Source

PatentEP3435532B1Circulating-current reducing circuit and transformer unit
Publication Date: 2020.11.18 SUMIDA CORP
  • EP3435532B1 patent drawingFigure 1
  • EP3435532B1 patent drawingFigure 2A~2H
  • EP3435532B1 patent drawingFigure 3

AI summary

[Problem] Provided is a circulating-current reducing circuit that can suppress circulating current even with a simplified configuration having no control circuit used therein. [Solving Mean] Configured is a circulating-current reducing circuit that is connected to a transformer unit 1 to reduce circulating current, the transformer unit 1 including: a transformer device 21; a transformer device 22 that is connected to the transformer device 21 in parallel; and a switching element 15 that controls timing of supply of current to a primary coil portion 21a of the transformer device 21 and a primary coil portion 22a of the transformer device 22. At this time, the circulating-current reducing circuit includes a first circuit 11 that is connected between the primary coil portion 21a of the transformer device 21 and the switching element 15, and a second circuit 12 that is connected between the primary coil portion 22a of the transformer device 22 and the switching element 15.