Parallel Motor Drive Control Using Global Current Feedback

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Solution Overview

Problem

Existing electronic control architectures for power converters face challenges in paralleling multiple motor drives, leading to issues such as circulating currents, limited bandwidth, and complexity, particularly in modular and multiplexed systems, which are critical for aircraft applications where components may not operate simultaneously.

Innovation Solution

A distributed control architecture with a central controller that receives local current measurements from each power converter, calculates a global current measurement, and transmits it back to regulate output currents, allowing each power converter to operate independently while ensuring synchronized power delivery to loads, reducing the need for reconfiguration and minimizing circulating currents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If multiple power converters are operated in parallel to handle wide power requirements, then the power capability and availability are improved, but the system complexity and risk of circulating currents increase

Engineering Contradiction:

Improvepower capabilityVSAvoidsystem complexity

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The control system is segmented into distributed local controllers within each power converter unit, each managing its own output current independently. This segmentation allows parallel operation without requiring complex centralized coordination, thus improving power capability while limiting the increase in system complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each power converter is equipped with local current measurement and control loops that continuously monitor and adjust their own output currents. This feedback mechanism enables automatic circulation current suppression without external intervention, resolving the contradiction between parallel power capability and control complexity.

Inventive Principle:

Principle #23Feedback

2Reliability

If heavy interphase transformers are used to suppress circulating currents, then the reliability of parallel operation is improved, but the system weight and size increase

Engineering Contradiction:

Improveparallel operation reliabilityVSAvoidsystem weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent replaces the mechanical/electromagnetic approach of using heavy interphase transformers with an electronic control approach. Distributed controllers with local feedback loops electronically suppress circulating currents by adjusting switching patterns, achieving the same reliability benefit without the weight penalty of large transformers.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The control system dynamically adjusts switching parameters and modulation indices of each power converter based on real-time current measurements. By changing these control parameters adaptively, the system suppresses circulating currents without requiring fixed heavy-duty transformer components, thus improving reliability while minimizing weight.

Inventive Principle:

Principle #35Parameter changes

3Stability of the object's composition

If a centralized control architecture is used to coordinate multiple power converters, then the synchronization is improved, but the bandwidth limitations and control complexity increase

Engineering Contradiction:

ImprovesynchronizationVSAvoidcontrol complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The centralized control function is segmented and distributed to individual power converter units. Each unit has its own controller that independently manages synchronization and current regulation, eliminating the need for a complex centralized control system while maintaining synchronization through coordinated local decision-making based on common reference signals.

Inventive Principle:

Principle #1Segmentation

4Power

If power converters are designed for maximum load power individually, then the power capability is improved, but the weight and cost of each converter increases

Engineering Contradiction:

Improvepower capabilityVSAvoidconverter weight

Core Design Contradiction:

PowerVSWeight of moving object

Solution Approach 1:

Multiple power converter units are merged in parallel to achieve the total required power capability. Each unit is designed for a fraction of the total power, reducing individual weight and cost, while the combined system delivers the full power requirement through coordinated operation controlled by distributed controllers.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS12027994B2Distributed control architecture for motor drives

Publication Date: 2024.07.02 HAMILTON SUNDSTRAND CORP

AI summary

There is provided a system for providing (e.g., configured to provide) power to one or more loads. The system comprises a plurality of power converters, wherein each power converter is configured to be arranged in a parallel configuration with one or more additional power converters so as to provide power to the one or more loads. The system further comprises a central controller configured to receive a plurality of local current measurement values from each of the power converters, output a global current measurement value based on the local current measurement values, and transmit the global current measurement value to each of the power converters, wherein each power converter comprises an inverter for receiving an input voltage and converting this to an output voltage having one or more associated output current(s).