Six-Phase Machine Control Switching for Fault-Tolerant Torque
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing multi-phase electric machines, particularly six-phase AC machines, face significant performance variations under healthy and faulty conditions, necessitating optimal control strategies with fault handling capabilities.
Innovation Solution
A controller is employed to apply different control strategies, switching between a six-phase control technique for healthy conditions and a three-phase control technique for faulty conditions, by disabling the faulty three-phase machine and maintaining phase-shifted operation for the healthy one.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single six-phase control method is used, then the control is simple under healthy conditions, but the performance degrades significantly under faulty conditions
Solution Approach 1:
The control system dynamically switches between different control strategies based on the operational state. A controller monitors the health status of the six-phase machine and automatically transitions from a unified six-phase control method under healthy conditions to separate three-phase control methods under faulty conditions, ensuring optimal performance across all operational states
Solution Approach 2:
The system changes control parameters based on fault detection. When a fault is detected in one of the three-phase machines, the control strategy changes from treating all six phases uniformly to applying distinct control parameters to the healthy three-phase machine, thereby maintaining reliability under faulty conditions
2Reliability
If different control strategies are implemented for healthy and faulty conditions, then reliability under faulty conditions is improved, but device complexity increases
Solution Approach 1:
The six-phase machine is segmented into two independent three-phase machines for control purposes. This segmentation allows the control system to apply different control strategies to each three-phase machine, simplifying the fault handling process while maintaining reliability. The controller can independently manage each three-phase machine, reducing the overall control complexity compared to managing all six phases simultaneously under fault conditions
Solution Approach 2:
The control system is designed with multi-functionality to handle both healthy and faulty conditions using a unified controller architecture. The same controller can operate in different modes (unified six-phase control or separate three-phase control) based on system needs, avoiding the need for completely separate control systems and thereby limiting the increase in device complexity
3Productivity
If all six phases are controlled simultaneously, then torque production is optimized under healthy conditions, but torque ripple increases under faulty conditions
Solution Approach 1:
When a fault is detected in one three-phase machine, the faulty machine is extracted from the active control system. The controller disables the faulty three-phase machine and continues to operate the healthy three-phase machine independently, thereby eliminating the source of torque ripple while maintaining productive torque output from the remaining healthy phases
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A method of controlling a multi-phase electric machine includes implementing a first control method to control the operation of a six-phase machine that is configured as a combination of two three-phase machines. The method also includes determining whether a fault exists in the six-phase machine. In response to determining that the fault exists in the six- phase machine, the method includes implementing a second and different control method to control the operation of the six-phase machine.