Bearingless Motor Control via Segmented Stator Windings
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current control techniques for bearingless permanent magnet synchronous motors face challenges in coordinating the first and second converter stages, leading to limitations in force production and flux change speed, resulting in complex and costly systems.
Innovation Solution
A control device and method that determine first and second component currents to generate torque and direct magnetic levitation force to the rotor, with interconnected converter stages using reference currents, eliminating the need for complex control systems and allowing for efficient coordination between the converter stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If only intermediate points of stator phase-windings are utilized for force production, then the system is cost-effective with one additional three-phase converter, but force production capability and flux change speed are limited
Solution Approach 1:
The phase-windings are segmented into multiple sections with intermediate points, allowing independent current control in different winding sections. This segmentation enables the first converter stage to control terminal currents for torque generation while the second converter stage controls intermediate point currents for enhanced force production, resolving the contradiction between cost-effectiveness and force capability
Solution Approach 2:
The control system transitions from single-point control to multi-point control by adding a second converter stage that operates in another dimension (intermediate points) alongside the first converter stage (terminals). This dimensional expansion enables simultaneous torque and force control without sacrificing cost-effectiveness
2Device complexity
If only intermediate points of stator phase-windings are utilized for force production, then the system structure is simplified, but flux change speed is limited
Solution Approach 1:
The second converter stage is configured to supply force-generating currents to intermediate points in advance, enabling faster flux changes and improved dynamic response. This preliminary action at intermediate points complements the terminal control, achieving high-speed flux change without excessive system complexity
Solution Approach 2:
The control system implements dynamic current distribution where the first and second converter stages operate with different time constants and response characteristics. The intermediate point control provides fast dynamic response for flux changes while the terminal control handles steady-state torque generation, resolving the contradiction between structural simplicity and speed performance
3Adaptability or versatility
If different current requirements are imposed on different parts of stator phase-windings, then torque and force can be independently controlled, but control coordination becomes complex
Solution Approach 1:
The control device merges the control functions of two converter stages by determining reference currents for both stages based on common torque and force references. This merging approach enables independent torque and force control while avoiding complex coordination through unified current determination logic that accounts for interactions between terminal and intermediate point currents
Solution Approach 2:
The control system implements feedback mechanisms where the actual currents in both converter stages are monitored and used to adjust reference currents. This feedback ensures proper coordination between the first and second converter stages, maintaining independent torque and force control while managing system complexity through adaptive current distribution
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
This approach simplifies the coordination of converter stages, enhancing force production and flux change speed, thereby improving the performance and cost-effectiveness of bearingless electrical machines.
Implementation Method 1
an electrical machine comprising a stator and a rotor, a first converter stage connected to terminals of phase-windings of the stator, and a second converter stage connected to intermediate points of the phase-windings of the stator
Implementation Method 2
determine first component currents and second component currents so that torque is generated in accordance with electrical machine control and magnetic levitation force is directed to the rotor in accordance with levitation control
Data Source
AI summary
An electrical drive includes an electrical machine, a first converter stage connected to terminals of stator phase-windings of the electrical machine, and a second converter stage connected to intermediate points of the stator phase-windings. A control device determines first component currents and second component currents so that torque is generated in accordance with electrical machine control and magnetic levitation force is directed to a rotor of the electrical machine in accordance with levitation control when portions of the phase-windings between the terminals and the intermediate points carry both the first and second component currents and the other portions of the phase-windings carry the first component currents. The reference currents for the first converter stage are determined based on the first and second component currents, and the reference currents for the second converter stage are determined based on the second component currents.