Five-Phase PM Motor Fault-Tolerant Control With Fixed Switching
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Solution Overview
Problem
Existing fault-tolerant control methods for multi-phase permanent magnet motors, particularly five-phase systems, face challenges such as unfixed switching frequency, large torque and flux linkage ripple, and complex control algorithms, which compromise the reliability and efficiency of motor drive systems during open-circuit faults.
Innovation Solution
A unified open-circuit fault-tolerant control method for vector control (VC) and direct torque control (DTC) systems, utilizing chaotic pulse width modulation (CPWM) and mathematical modeling to manage currents and voltages, ensuring robust operation and minimizing system reconfiguration, thereby simplifying the control algorithm and reducing CPU and memory resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional hysteresis comparison control is used for fault-tolerant control, then the control system can operate during faults, but the switching frequency becomes unfixed and torque and flux linkage ripple increase
Solution Approach 1:
The patent transforms the control approach from hysteresis comparison to space vector pulse width modulation (SVPWM), fundamentally changing the control parameters and methodology. This parameter change enables fixed switching frequency operation while maintaining fault-tolerant capability and reducing torque and flux linkage ripple through optimized voltage vector selection and modulation
2Object-generated harmful factors
If space vector pulse width modulation (SVPWM) is used for fault-tolerant control, then switching frequency is fixed and torque ripple is reduced, but the control algorithm becomes complex requiring system reconfiguration
Solution Approach 1:
The patent develops a universal fault-tolerant control algorithm based on SVPWM that can handle various fault conditions (single-phase open circuit, two-phase open circuit, etc.) without requiring fundamental changes to the control structure. The same basic algorithm framework is applied across different fault scenarios, reducing overall system complexity despite the sophisticated modulation technique used
Solution Approach 2:
The patent pre-calculates and stores optimal voltage vector sequences and modulation parameters for different fault conditions in lookup tables. This preliminary preparation allows the controller to quickly switch to appropriate fault-tolerant modes without complex real-time calculations, simplifying the online control algorithm while maintaining performance
3Reliability
If two coordinate transformation matrices are used for fault-tolerant control, then the control can be implemented, but the control algorithms are not essentially simplified and system reconfiguration is required
Solution Approach 1:
The patent merges the fault detection, fault diagnosis, and fault-tolerant control functions into a unified control framework. The coordinate transformation and control algorithms are integrated such that the same transformation matrices serve both normal and fault-tolerant operation, eliminating the need for separate algorithms and reducing system reconfiguration requirements
Data Source
AI summary
A unified open-circuit fault-tolerant control method for a vector control (VC) drive system and a direct torque control (DTC) drive system of a five-phase permanent magnet fault-tolerant motor are provided. The control method adopts a unified open-circuit fault-tolerant control strategy. The unified open-circuit fault-tolerant control strategy includes: obtaining a predetermined torque, obtaining predetermined direct-axis and quadrature-axis voltages, analyzing a fault-tolerant mechanism to obtain fault-tolerant currents, obtaining winding phase voltages in a fault mode based on the fault-tolerant mechanism, and obtaining fault-tolerant voltages based on a back-electromagnetic force (EMF). The unified open-circuit fault-tolerant control strategy suitable for the VC drive system and the DTC drive system is proposed based on chaotic pulse width modulation (CPWM). The control method essentially reveals the fault-tolerant mechanism, and solves the problem of variable and complicated fault-tolerant control schemes corresponding to various basic control algorithms.