Motor Control Torque Ripple Estimation Using Flux-Linkage Inner Product
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Solution Overview
Problem
Conventional torque estimation methods for synchronous motors with embedded magnets fail to accurately estimate torque ripple, leading to motor control deterioration due to harmonic distortions in magnetic flux and inductance distributions, which also affects generator control.
Innovation Solution
A motor and generator control device that estimates torque fluctuation components using the inner product of flux-linkage and current vectors, and considers magnetic pole position changes and rotation speed to improve torque estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional torque estimation methods using exterior product of flux-linkage and current vectors are used, then the control system is simple to implement, but the torque fluctuation component (torque ripple) cannot be estimated accurately
Solution Approach 1:
The patent changes the mathematical operation from exterior product to inner product of flux-linkage and current vectors. This parameter change in the estimation method enables accurate detection of torque fluctuation components while maintaining computational simplicity. The inner product calculation (Σφ×i) directly captures the torque ripple caused by harmonic distortions without requiring complex additional measurements or computations.
2Measurement precision
If torque estimation is performed without considering harmonic components, then the estimation calculation is simple, but the error between instantaneous estimated torque and actual torque increases
Solution Approach 1:
The patent replaces complex mechanical measurement methods with an electrical calculation approach. Instead of using complex mechanical sensors or direct measurement systems to capture torque ripple, the invention uses electrical parameters (flux-linkage and current vectors) combined with inner product mathematics to substitute and infer the torque fluctuation components, achieving high precision without mechanical complexity.
Solution Approach 2:
The patent changes the mathematical operation from exterior product to inner product of flux-linkage and current vectors. This parameter change in the estimation method enables accurate detection of torque fluctuation components while maintaining computational simplicity. The inner product calculation (Σφ×i) directly captures the torque ripple caused by harmonic distortions without requiring complex additional measurements or computations.
3Object-affected harmful factors
If the motor control system does not estimate torque fluctuation components, then the control algorithm is simpler, but vibration and noise caused by torque ripple increase
Solution Approach 1:
The patent implements feedback control by continuously estimating torque fluctuation components using the inner product method and using this information to adjust the motor control. The estimated torque ripple is fed back to the control system, enabling real-time compensation that reduces vibration and noise while maintaining a relatively simple control algorithm structure.
Solution Approach 2:
The patent changes the mathematical operation from exterior product to inner product of flux-linkage and current vectors. This parameter change in the estimation method enables accurate detection of torque fluctuation components while maintaining computational simplicity. The inner product calculation (Σφ×i) directly captures the torque ripple caused by harmonic distortions without requiring complex additional measurements or computations.
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
The proposed solution effectively estimates and corrects torque ripple, enhancing motor and generator control precision and reducing vibration and noise caused by torque fluctuations.
Implementation Method 1
torque fluctuation component estimation unit for estimating a torque fluctuation component generated at the motor based on flux-linkage of the armature winding and an armature current that flows the armature winding
Implementation Method 2
estimates the torque fluctuation component based on an inner product of a flux-linkage vector which is a vectorial representation of the flux-linkage or a vector according to the flux-linkage and a current vector which is a vectorial representation of the armature current
Data Source
AI summary
To estimate a fluctuation component of the torque generated at the motor accurately, a motor control device (3) which controls a motor with a stator having armature winding and a rotor having a permanent magnet is provided to include a torque fluctuation component estimation unit for estimating a torque fluctuation component generated at the motor based on flux-linkage of the armature winding and an armature current that flows the armature winding. The torque fluctuation component estimation unit estimates the torque fluctuation component (Trp) based on an inner product (Fd·id+Fq·iq) of a flux-linkage vector which is a vectorial representation of the flux-linkage and a current vector which is a vectorial representation of the armature current.