Multiphase Motor Torque Control for Open Circuit Faults
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Solution Overview
Problem
Multiphase electric machines face significant torque ripple and sub-optimal control strategies when a phase is in an open circuit condition, lacking a generalized mathematical model to describe this behavior, which complicates maintaining average torque output and reducing ripple.
Innovation Solution
A method and system that determine a desired torque and retrieve a set of current values for other phases based on a model of the multiphase electric machine in an open circuit condition, applying these values to minimize torque ripple and maintain optimal performance, applicable to various synchronous machine configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional control strategies are used for multiphase electric machines with open circuit condition, then the machine can continue to operate, but torque ripple increases significantly and average torque output deteriorates
Solution Approach 1:
The invention changes the control parameters by deriving specific current references for the healthy phases based on the open circuit condition. The control strategy adjusts the amplitude and phase of current references for the remaining healthy phases to compensate for the missing phase, thereby maintaining acceptable torque output while minimizing torque ripple.
Solution Approach 2:
The invention segments the control strategy into different operational modes: healthy operation mode and open circuit fault mode. When an open circuit condition is detected, the system transitions to the fault mode where a specialized control algorithm is applied specifically for the remaining healthy phases, separating the control of faulty and healthy phases.
2Reliability
If conventional control strategies are used for multiphase electric machines with open circuit condition, then the machine can continue to operate, but the control complexity increases due to lack of generalized mathematical model
Solution Approach 1:
The invention provides a universal control strategy that can be applied to any multiphase electric machine regardless of the specific phase that fails. The generalized mathematical model and control algorithm work for any open circuit condition in any phase, making the solution multi-functional and applicable to all multiphase machine configurations without requiring machine-specific customization.
Solution Approach 2:
The control system automatically detects the open circuit condition and self-adjusts by deriving appropriate current references for the healthy phases without external intervention. The system performs self-diagnosis and self-correction, reducing the need for complex external control mechanisms.
3Reliability
If conventional control strategies are used for multiphase electric machines with open circuit condition, then the machine can continue to operate, but the average torque output decreases
Solution Approach 1:
The invention changes the control parameters by deriving specific current references for the healthy phases based on the open circuit condition. The control strategy adjusts the amplitude and phase of current references for the remaining healthy phases to compensate for the missing phase, thereby maintaining acceptable torque output while minimizing torque ripple.
Data Source
AI summary
A method for controller a multiphase electric machine includes, in response to a determination that a phase of the multiphase electric machine is in an open circuit condition, determining a desired torque to be generated by the multiphase electric machine and retrieving, based on the determination that the phase is in the open circuit condition and the desired torque, a set of current values to be applied to each of the other phases of the multiphase electric machine to achieve the desired torque. The method may also include applying respective current values of the set of current values to corresponding ones of the other phases of the multiphase electric machine, the set of current values being determined based on a model of the multiphase electric machine that includes the phase is in the open circuit condition.