Multi-Phase Converter Control via Segmented D-Q Circulation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current converter systems for wind power generation face challenges in controlling multi-phase generators with increased capacity, as existing methods are complex and inefficient, particularly when leakage inductance is small, leading to unstable control and poor current sharing among converters.
Innovation Solution
A control method and system that involves sampling real-time currents from each three-phase winding, averaging and processing them to generate mean and differential-mode current signals, and performing circulation current control using a d-q coordinate system to stabilize the multi-phase generator and enable current sharing among converters, with each converter having a dedicated controller to simplify the driving path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single generator-side controller is used to control multiple converters, then the control structure is simplified, but the sampling path and driving path become complex and difficult to implement
Solution Approach 1:
The patent divides the control system into multiple independent generator-side controllers, each dedicated to controlling a specific converter. This segmentation allows each controller to have its own simple sampling and driving paths, avoiding the complexity that would arise from a single controller managing multiple converters. Each controller independently processes current samples and generates driving signals for its associated converter.
Solution Approach 2:
The patent introduces a circulation current control mechanism that acts as an intermediary between the distributed generator-side controllers. This intermediary function coordinates the control actions among multiple controllers, enabling them to work together as a unified system while maintaining individual simplicity. The circulation current control ensures proper current sharing and coordination without requiring complex inter-controller communication paths.
2Ease of operation
If parallel connected converters are controlled individually without circulation current control, then the control implementation is simpler, but the controlling effect is poor and cannot be implemented when leakage inductance is small
Solution Approach 1:
The patent implements circulation current control that continuously monitors the current output of each converter and uses this feedback information to adjust the control signals. Each generator-side controller samples the current from its associated converter and uses this feedback, along with feedback from other converters, to regulate the circulation current. This feedback mechanism ensures stable control and proper current sharing even when leakage inductance is small, significantly improving the controlling effect compared to individual control without circulation control.
Solution Approach 2:
The patent combines individual converter control with circulation current control in a unified control framework. Each generator-side controller simultaneously performs local current regulation and participates in the overall circulation current control. This merging of control functions allows the system to benefit from both the simplicity of individual control and the stability of coordinated control, enabling implementation even with small leakage inductance.
3Power
If the number of back-to-back converters is increased to improve total converter capacity, then the converter system can handle higher power, but the control complexity and coordination difficulty increase
Solution Approach 1:
The patent divides the control of the multi-converter system into independent segments, with each generator-side controller managing its own converter. This segmentation allows the system to scale to higher power capacities by simply adding more independent control units, without proportionally increasing overall control complexity. Each controller operates autonomously with its own sampling and driving paths, making the system modular and easily expandable.
Solution Approach 2:
The patent uses circulation current control to dynamically adjust operating parameters of each converter based on system conditions. By changing control parameters such as current references and circulation current limits, the system can coordinate multiple converters efficiently. This parameter-based coordination allows high-power multi-converter systems to operate stably without requiring complex structural modifications to the control architecture.
Data Source
AI summary
A control method of a converter system includes: sampling a current of each three-phase winding to obtain a real-time current of each converter; obtaining a mean current by averaging the real-time current of each secondary converter and the real-time current of the primary converter, and transferring the mean current to each secondary converter; obtaining the differential-mode current corresponding to each secondary converter according to the mean current and the real-time current of each secondary converter; performing a circulation current control on the mean current and the differential-mode current of each secondary converter based on a d-q coordinate system to generate a mean-current conditioning signal and a differential-mode current conditioning signal, thereby controlling each secondary converter; and obtaining a sum of the differential-mode current conditioning signal of the secondary converters and negating the sum to obtain a differential-mode current conditioning signal of the primary converter, thereby controlling the primary converter.