Switching Control of Parallel Power Converters for DC Bus Stability

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Solution Overview

Problem

Existing power grids face significant power loss and inefficiency due to the use of multiple power converters, especially when dealing with fluctuations in DC bus voltage, which can drop or rise significantly, leading to unstable operation.

Innovation Solution

A power converter control method that uses a switching device with a switch to short-circuit an arbitrary power converter, either in series or in parallel, by gradually changing the ON-time of the switch or resistor value to stabilize the DC bus voltage, thereby maintaining efficient operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If multiple power converters are used in the power grid, then power conversion capability is improved, but power loss increases and efficiency decreases

Engineering Contradiction:

Improvepower conversion capabilityVSAvoidpower loss

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The power grid is divided into multiple segments with power converters positioned at specific locations. Each converter handles only the necessary power conversion for its local segment, reducing redundant conversions and associated losses while maintaining overall system capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Power conversion functionality is extracted from centralized locations and distributed to specific points in the power grid where it is most needed, eliminating unnecessary conversion stages and reducing total power loss.

Inventive Principle:

Principle #2Taking out (Extraction)

2Stability of the object's composition

If power converters are added to stabilize DC bus voltage, then voltage stability is improved, but power loss increases

Engineering Contradiction:

ImproveDC bus voltage stabilityVSAvoidpower loss

Core Design Contradiction:

Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The power converters are equipped with dynamic control mechanisms that adjust their operation in real-time based on DC bus voltage conditions. When voltage is stable, converters operate at minimal levels; when voltage fluctuates, they actively compensate, thereby maintaining stability while minimizing energy loss during normal operation.

Inventive Principle:

Principle #15Dynamics

3Reliability

If switching device ON-time is continuously increased to place converter in ON state, then converter reliability is improved, but peak current suppression capability deteriorates

Engineering Contradiction:

Improveconverter reliabilityVSAvoidpeak current

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The switching device employs periodic switching action with optimized duty cycles. Instead of continuous ON-state operation, the switch operates in controlled periodic cycles that maintain converter reliability through regular operation while distributing current demand over time, thereby suppressing peak current occurrences.

Inventive Principle:

Principle #19Periodic action

4Stability of the object's composition

If switching device is used to short-circuit power converters, then voltage fluctuation suppression is improved, but device complexity increases

Engineering Contradiction:

Improvevoltage fluctuation suppressionVSAvoidswitching device complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The switching device integrates multiple functions including short-circuit capability, voltage regulation, and converter control into a single unified component. This merging of functions achieves comprehensive voltage fluctuation suppression while minimizing the number of separate devices needed, thereby reducing overall system complexity.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS20260018879A1Power converter control method

Publication Date: 2026.01.15 NAGASAKI INSTITUTE OF APPLIED SCIENCE

AI summary

Provided is a power converter control method short-circuits, with use of a switching device that has a switch and that is connected to power converters in series or in parallel, an arbitrary one of the power converters. The power converter control method includes placing the switching device in an ON state by continuously increasing ON-time of the switch.