Six-Phase Machine Control With Fault-Tolerant Phase Switching
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Solution Overview
Problem
Existing multi-phase electric machines, such as six-phase AC machines, face significant performance variations under healthy and faulty conditions, necessitating the development of optimal control strategies with fault handling capabilities.
Innovation Solution
A controller applies different control strategies to operate a six-phase machine as a combination of two three-phase machines, switching to a three-phase control technique when a fault occurs, disabling the faulty three-phase machine and maintaining phase-shifted operation for the healthy one.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single six-phase control method is used to control all six phases, then the control structure is simple, but the system cannot handle faults effectively and performance varies greatly under faulty conditions
Solution Approach 1:
The six-phase machine is segmented into two independent three-phase machines (first three-phase machine with phases A-B-C and second three-phase machine with phases D-E-F). This segmentation allows independent control of each three-phase machine, enabling fault isolation where a fault in one three-phase machine does not affect the other, thereby improving reliability while maintaining manageable control complexity through modular control strategies.
2Reliability
If the system switches to three-phase control when a fault occurs, then fault tolerance is improved, but the control method complexity increases due to needing different control strategies for healthy and faulty conditions
Solution Approach 1:
The control system dynamically adapts its strategy based on the operational state. Under healthy conditions, a unified six-phase control method is used for optimal performance. When a fault is detected in one three-phase machine, the system dynamically switches to controlling only the healthy three-phase machine, disabling the faulty one. This dynamic adaptation enables fault tolerance while managing control complexity through state-dependent control strategies.
Solution Approach 2:
The control system is designed with multi-functionality to handle both healthy and faulty operational modes. The same controller can implement either the unified six-phase control method when both three-phase machines are healthy, or switch to controlling only the healthy three-phase machine when a fault occurs. This universal control capability improves fault tolerance while avoiding the need for completely separate control systems.
3Productivity
If all six phases are controlled under healthy conditions, then drive performance is maximized, but the system becomes vulnerable to faults that can cause complete failure
Solution Approach 1:
By segmenting the six-phase machine into two independent three-phase machines, the system can operate all six phases under healthy conditions to maximize drive performance. When a fault occurs in one three-phase machine, the segmentation allows the other three-phase machine to continue operating independently, preventing complete system failure and maintaining partial functionality, thus improving reliability without sacrificing normal operational performance.
Data Source
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.