PMSM Predictive Current Control for Harmonic Torque Suppression
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Solution Overview
Problem
Permanent-magnet synchronous machines experience torque ripples due to harmonic torque and nonlinear characteristics, leading to increased iron and copper losses, current overshoot, and safety hazards, which complicates control and limits their application scope.
Innovation Solution
A control method using a model predictive control algorithm to predict d-axis and q-axis currents, subtracting harmonic components, and determining control policies based on cost functions to simplify the system structure and suppress harmonic currents without the need for PI controllers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large number of PI controllers are used to suppress harmonic currents, then the harmonic current suppression effect is improved, but the control system complexity increases and parameter adjustment becomes complicated
Solution Approach 1:
The patent combines multiple PI controllers into a single model predictive control algorithm. Instead of using separate PI controllers for different harmonic components, the invention integrates harmonic suppression functionality into the predictive control framework, where the cost function simultaneously optimizes fundamental current tracking and harmonic current suppression, thereby reducing system complexity while maintaining suppression effectiveness
Solution Approach 2:
The patent changes the control approach from continuous parameter adjustment (PI controller gains) to discrete optimization (cost function evaluation). By formulating the control problem as an optimization task with a carefully designed cost function, the system eliminates the need for manual PI parameter tuning and reduces complexity through algorithmic parameter selection
2Manufacturing precision
If multiple PI controllers are integrated for harmonic suppression, then the harmonic torque elimination is improved, but the parameter adjustment process becomes complicated
Solution Approach 1:
The model predictive control algorithm performs self-optimization by automatically adjusting control parameters through cost function evaluation. The controller selects optimal voltage vectors based on predicted current errors and system state, eliminating the need for manual parameter adjustment and enabling the system to adapt automatically to changing operating conditions while maintaining high precision in harmonic torque elimination
3Device complexity
If traditional control methods are used, then the control system structure is simple, but torque ripples and harmonic losses increase
Solution Approach 1:
The patent applies preliminary action by predicting future current states before actual control actions are taken. The model predictive control algorithm calculates predicted currents for each possible voltage vector, evaluates cost functions based on these predictions, and selects the optimal control action in advance, thereby preventing harmonic current generation and reducing energy losses before they occur
Data Source
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AI summary
This application provides a permanent-magnet synchronous machine control method and device, and a permanent-magnet synchronous machine control system. The method includes: obtaining a d-axis current id and a q-axis current iq in a permanent-magnet synchronous machine control loop at a current moment; obtaining a fifth-order harmonic current id5th and a seventh-order harmonic current id7th in the d -axis current id in the permanent-magnet synchronous machine control loop at the current moment, and a fifth-order harmonic current iq5th and a seventh-order harmonic current iq7th in the q-axis current iq in the permanent-magnet synchronous machine loop at the current moment; determining a d-axis current idk+1 at a next moment in each switch state; determining a q-axis current iqk+1 at the next moment in each switch state based on the first current idk, the second current iqk, and the second voltage in each switch state; and determining a control policy of the permanent-magnet synchronous machine based on the d-axis current idk+1 at the next moment in each switch state and the q-axis current iqk+1 at the next moment in each switch state. In this way, the existing PI controller is cancelled and the complicated PI parameter adjustment is avoided.