IPM Motor Controller Lookup Table Generation
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Solution Overview
Problem
Conventional methods for controlling Interior Permanent Magnet (IPM) machines, such as theoretical equations and finite element analysis, are inaccurate and time-consuming, and do not cover the full operating range in terms of speed and torque level, especially when considering voltage ellipses.
Innovation Solution
A method involving the generation of an initial operating points lookup table using a computer processing unit, which includes calculating maximum torque per Ampere (MTPA) trajectories and truncated voltage limit ellipses based on machine parameters, to determine direct and quadrature axis current values for various torque commands across different speeds, ensuring accurate control within the full operating range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If theoretical equations are used to find machine operating points, then the control method is simple, but the accuracy is insufficient
Solution Approach 1:
The patent pre-calculates and stores operating points (I_d, I_q pairs) for various torque commands and speeds in lookup tables before actual operation. This preliminary computation phase separates the complex calculations from real-time control, achieving both accuracy (through detailed pre-computation) and simplicity (through fast table lookup during operation).
Solution Approach 2:
The patent creates a simplified representation of the complex motor characteristics by copying essential operating data into lookup tables. Instead of performing complex theoretical calculations or finite element analysis during real-time control, the system uses pre-copied operating point data that can be quickly retrieved and applied.
2Measurement precision
If finite element analysis is used to find correct operating points, then the accuracy is improved, but the time consumption increases significantly
Solution Approach 1:
The patent performs the time-consuming finite element analysis and operating point calculations in advance, storing results in lookup tables. During actual motor control operation, the system simply retrieves pre-calculated data, eliminating real-time computation delays while maintaining accuracy.
Solution Approach 2:
The patent divides the operating range into discrete torque commands and speed levels, creating separate lookup table entries for each combination. This segmentation allows the system to pre-calculate and store specific operating points without needing to perform continuous real-time analysis, reducing computational time while covering the full operating range.
3Ease of operation
If conventional methods are used to determine operating region, then the control is simplified, but the full operating range in terms of speed and torque is not covered
Solution Approach 1:
The patent creates a universal lookup table structure that can provide operating points for any combination of torque commands and speeds within the motor's capabilities. The system generates voltage limit ellipses for multiple speeds and combines them with MTPA trajectories to create a comprehensive control solution that adapts to the full operating range while maintaining a unified control approach.
Solution Approach 2:
The patent extends the control approach by incorporating voltage limit ellipses as an additional dimensional constraint beyond traditional current limits. By considering the voltage-speed-torque relationship in three dimensions and projecting it onto the I_d-I_q plane, the system achieves comprehensive coverage of the operating range while maintaining manageable control complexity.
Data Source
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AI summary
Embodiments of the present invention provide a device and method for generating initial operating points for controlling an interior permanent magnet (IPM) machine. The method includes loading an inductance lookup- table (S110), first calculating a maximum torque per Ampere (MTPA) trajectory for a first threshold speed based on machine parameters of the IPM machine (S120), second calculating a truncated voltage limit ellipse with monotonicaliy increasing torque for a first speed based on the machine parameters (S130), if the first speed is higher than the first threshold speed, determining an operating trajectory at the first speed (S140) based on at least one of the calculated MTPA trajectory and the calculated truncated voltage limit ellipse, and generating an Id,Iq map that maps an Id value and an lq value to each torque command of a plurality of torque commands for the first speed based on the determined operating trajectory (S150).