PMSM Parameter Adjustment via Current Loop Integral Terms
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Solution Overview
Problem
Existing methods for controlling Permanent Magnet Synchronous Motors (PMSM) in variable speed drives face challenges in accurately estimating and adjusting motor parameters like stator resistance, inductance, and flux constant, especially under varying temperature and operational conditions, leading to potential performance degradation, consumption issues, and oscillations.
Innovation Solution
A method that adjusts motor parameters in real-time using the integral term of the current loop, without requiring temperature or torque measurements, by calculating correction values for stator resistance, inductance, and flux constant based on differences between torque and flux current references, and applying these adjustments to refine the motor model.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If motor parameters are estimated using preliminary identification or self-learning phase, then the motor model can be established, but the parameters may become inaccurate over time due to temperature changes and operational variations
Solution Approach 1:
The motor control system automatically adjusts its own parameters during operation by using the integral terms from current control loops. The system serves itself by continuously updating stator resistance, inductance, and flux constant based on real-time current measurements and control errors, without requiring external recalibration or additional sensors.
Solution Approach 2:
The patent implements continuous parameter adaptation by modifying motor model parameters (stator resistance Rs, inductance Ld/Lq, and flux constant Ke) based on operating conditions. The integral terms from current controllers contain information about parameter deviations, and these are used to dynamically update the parameters, allowing the system to adapt to temperature changes and operational variations.
2Measurement precision
If many sensors are used to measure motor temperature, voltages, torque, and rotation for parameter determination, then parameter accuracy can be improved, but the device complexity and cost increase significantly
Solution Approach 1:
The patent extracts useful parameter information from the integral terms of existing current control loops, which already contain measurement data from basic current sensors. Instead of adding new sensors, the method extracts parameter deviation information that is already embedded in the control errors, thereby avoiding additional measurement devices while still achieving accurate parameter identification.
Solution Approach 2:
The integral terms of the current controllers serve as intermediaries that carry information about motor parameter deviations. Rather than directly measuring parameters with dedicated sensors, the system uses these integral terms as mediators to infer parameter changes, enabling parameter adaptation through existing control loop information.
3Use of energy by moving object
If stator resistance value is inaccurate, then the current supplied to the motor may be greater than necessary, but correcting this requires continuous parameter adjustment during operation
Solution Approach 1:
The system uses feedback from the integral terms of current controllers to continuously monitor and correct parameter deviations. The integral terms provide feedback information about accumulated current errors, which are then used to update motor parameters, creating a closed-loop system that automatically maintains optimal energy efficiency without manual intervention.
4Manufacturing precision
If motor inductance values are not accurately known, then dynamic precision of torque supply deteriorates, but traditional methods cannot easily detect and correct these values during operation
Solution Approach 1:
The integral terms of the current controllers act as intermediaries that contain information about inductance deviations. By analyzing these integral terms during normal operation, the system can infer inductance parameter changes without requiring direct measurement, thereby overcoming the difficulty of detecting and measuring inductance values in real-time.
Data Source
Figure 1~2
AI summary
The method involves determining differences between motor torque current reference and measurement (I-Qref, I-Qm) and between motor flow reference and measurement (I-Dref, I-Dm). Statoric resistance, inductance and flow constant correction values (DELTARs, DELTAL, DELTAK-E) of a permanent magnet synchronous motor type triphase synchronous electric motor, are calculated from difference integral terms by using an adapter block (18). Parameter values of a motor model are adjusted from the values. Control voltages (U-D, U-Q) to be applied, to the motor are processed using the adjusted values. An independent claim is also included for a variable speed drive comprising an integrator block.