ISOP Converter Voltage Control With Auxiliary Series Converters

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Solution Overview

Problem

Existing DC/DC converters in ISOP arrangements lack control over output voltage and equal load current distribution among paralleled branches, leading to potential overloading and reduced output power due to open-loop operation with fixed modulation parameters.

Innovation Solution

Implementing auxiliary converters in series with each electrical converter and using compensation signals to balance load currents and control output voltage across branches, allowing for closed-loop control and equal loading.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If multiple ISOP branches are parallel connected to increase maximum output power, then the output power capability is improved, but the load current distribution between branches becomes unbalanced due to losses and parasitic elements

Engineering Contradiction:
Improveoutput powerVSAvoidload current distribution
Core Design Contradiction:
PowerVSEase of operation

Solution Approach 1:

The patent implements a control system that measures the actual load current in each parallel ISOP branch and uses this feedback information to adjust the switching frequency of each branch. By adapting the switching frequency based on measured current values, the system achieves balanced load current distribution across all parallel branches, preventing overloading while maximizing total output power capability.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent changes the operating parameter (switching frequency) of each parallel ISOP branch individually based on its load conditions. By dynamically adjusting the switching frequency of each branch according to its actual current load, the system optimizes power distribution and ensures equal loading across all parallel connected branches, thereby achieving both high output power and balanced current distribution.

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If LLC converters are operated open-loop with fixed modulation parameters to simplify operation and enable soft-switching, then the ease of operation and switching efficiency are improved, but the control over output voltage and load current distribution is lost

Engineering Contradiction:
Improveoperation controlVSAvoidoutput voltage control
Core Design Contradiction:
Ease of operationVSAdaptability or versatility

Solution Approach 1:

The patent transitions from static fixed modulation parameters to dynamic adjustable parameters. The switching frequency of each ISOP branch is made dynamically adjustable based on real-time load conditions, allowing the system to maintain simplified operation while gaining the adaptability to control output voltage and balance load current distribution across parallel branches.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the modulation parameter (switching frequency) from a fixed value to a dynamically adjustable parameter. By allowing the switching frequency to vary based on load conditions and control requirements, the system maintains the simplicity of open-loop operation while gaining the versatility to control output voltage and achieve balanced load distribution across parallel branches.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4693855A1ISOP converter with fixed transformation ratio and auxiliary series converter for voltage control
Publication Date: 2026.02.11 ABB (SCHWEIZ) AG
  • EP4693855A1 patent drawingFigure 1~3
  • EP4693855A1 patent drawingFigure 4~5
  • EP4693855A1 patent drawingFigure 6~7

AI summary

A converter arrangement (20) for converting a first DC bus voltage into a second DC bus voltage is described. The converter arrangement (20) comprises: an input connection (38) for electrically coupling the converter arrangement (20) to an energy source, wherein the energy source is configured for providing the first DC bus voltage; an output connection (48) for electrically coupling the converter arrangement (20) to a load, wherein the load is configured for receiving the second DC bus voltage; two or more first electrical converters (22) each having a corresponding input terminal and a corresponding output terminal, wherein the input terminals of the first electrical converters (22) are electrically coupled to each other in series between a first pole of the input connection (38) and a second pole of the input connection (38) and wherein the output terminals of the first electrical converters (22) are electrically coupled to the output connection (48) in parallel; and at least one first auxiliary converter (24) electrically arranged in series between the output terminal of at least one of the first electrical converters (22) and the output connection (48) or between the input terminal of at least one of the first electrical converters (22) and the input connection (38).