PMSM Rotor Position Estimation Using Region-Based Current Costing
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Solution Overview
Problem
Existing sensorless control methods for permanent magnet synchronous motors require extensive iterative calculations and additional observers, leading to increased computational load and reduced dynamic performance.
Innovation Solution
A direct locating method that pre-divides the position plane into regions based on stator current characteristics, using a stator current cost function to directly calculate the rotor position without iterative optimization, reducing the computational load and improving dynamic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional sensorless control methods using sliding mode observer or finite position set-PLL are employed, then rotor position can be estimated, but extensive iterative calculations (at least 24 iterations) and additional observers are required, increasing computational load and reducing dynamic performance
Solution Approach 1:
The position plane is pre-divided into four regions based on stator current characteristics. By segmenting the estimation space, the method reduces the search range from the entire 360-degree plane to a limited region, thereby reducing the number of iterations required while maintaining estimation accuracy.
Solution Approach 2:
The position plane is pre-divided into regions and cost functions are pre-established before actual position estimation. This preliminary preparation eliminates the need for extensive real-time iterative calculations, as the system can directly calculate position within the predetermined regions using pre-computed cost functions.
2Device complexity
If traditional PLL with fixed gain is used, then the system is simple to implement, but the bandwidth of the control system is reduced and dynamic performance is affected
Solution Approach 1:
The invention replaces the fixed gain PLL with a dynamic cost function-based approach where the gain characteristics are adaptively determined by the stator current characteristics and position region. This dynamic adjustment enables the system to achieve higher bandwidth and faster response while maintaining implementation feasibility.
3Measurement precision
If more iterations are performed to obtain accurate position, then rotor position accuracy improves, but control period increases and carrier ratio decreases, harming dynamic performance
Solution Approach 1:
By segmenting the position plane into four regions, the method reduces the estimation search space significantly. This segmentation enables accurate position estimation with fewer iterations, thereby reducing the control period and improving the carrier ratio without sacrificing position accuracy.
Solution Approach 2:
The method changes the estimation approach by using region-specific cost functions that are optimized for each position region. This parameter change enables the system to achieve accurate results with minimal iterations, reducing the time loss while maintaining high position accuracy.
Data Source
AI summary
A direct locating method for calculating a position of a permanent magnet synchronous motor is provided. The direct locating method performed by a processor includes: three-phase stator currents of the permanent magnet synchronous motor are converted by coordinate to obtain the stator currents in the αβ two-phase stationary coordinate system, and the initial position region is determined. The stator currents in dq two-phase synchronous rotating coordinate system are obtained by coordinate conversion. The stator current cost model is established. Then the d-axis stator current is inputted into the cost model and the position is outputted, and the final estimated position is determined to realize the direct locating of the permanent magnet synchronous motor's position.