PMSM Sensorless Control via Winding-Magnet Temperature Compensation
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Solution Overview
Problem
Existing sensorless permanent magnet synchronous motor control methods face inaccuracies in estimating rotor position and rotational speed due to temperature variations, as they fail to accurately compensate for differences in winding and permanent magnet temperatures, leading to reduced efficiency and synchronization losses.
Innovation Solution
A controller for permanent magnet synchronous motors that includes a correction portion to accurately adjust interlinkage magnetic flux parameters based on the relationship between winding and permanent magnet temperatures, using a drive portion, current detector, estimating portion, and control unit to improve estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the motor temperature is calculated based on the measured winding resistance value and used as the temperature of both winding and permanent magnet for compensation, then the compensation process is simplified, but the accuracy of interlinkage magnetic flux compensation deteriorates because the winding and permanent magnet have different temperatures
Solution Approach 1:
The patent segments the temperature compensation process into two distinct parts: winding temperature compensation and permanent magnet temperature compensation. It separately calculates the temperature of the winding based on resistance measurement and the temperature of the permanent magnet based on the relationship with winding temperature, then applies appropriate compensation to the interlinkage magnetic flux parameter. This segmentation resolves the contradiction by maintaining compensation process simplicity while improving accuracy through differentiated temperature handling.
Solution Approach 2:
The patent applies local quality by recognizing that different parts of the motor (winding and permanent magnet) have different temperature characteristics and requiring different compensation approaches. The winding temperature is calculated from resistance, while the permanent magnet temperature is derived from the relationship between winding and magnet temperatures. This localized quality approach ensures each component is compensated according to its specific thermal characteristics, resolving the accuracy issue.
2Device complexity
If the winding temperature and permanent magnet temperature are assumed to be equal for compensation, then the measurement process is simplified, but the estimation accuracy of rotor position and rotational speed deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-establishing the relationship between winding temperature and permanent magnet temperature before the compensation process. It first calculates the winding temperature from resistance measurement, then uses the predetermined relationship to determine the permanent magnet temperature, and finally applies both temperatures to the estimation process. This preliminary preparation of temperature data improves estimation accuracy without significantly increasing measurement complexity.
3Device complexity
If temperature compensation is not applied to the interlinkage magnetic flux parameter, then the control system is simpler, but the efficiency of the permanent magnet synchronous motor deteriorates due to inaccurate position and speed estimation
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the interlinkage magnetic flux parameter based on temperature variations. It changes the parameter value according to the calculated winding and permanent magnet temperatures, ensuring accurate motor control across different operating conditions. This parameter adaptation improves motor efficiency while maintaining a relatively simple control system structure.
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
This solution enhances the accuracy of rotor position and rotational speed estimation, reducing errors and maintaining synchronization, thereby improving motor efficiency without the need for additional temperature sensors.
Implementation Method 1
a stator with windings and a rotor using a permanent magnet. In such permanent magnet synchronous motors, an alternating current is applied to the windings to cause a rotating magnetic field, which rotates the rotor synchronously therewith
Implementation Method 2
the temperature of the winding or of the permanent magnet changes in association with an ambient temperature or a temperature rise caused by drive
Data Source
AI summary
A controller for a permanent magnet synchronous motor includes an estimating portion configured to determine an estimated value of a rotational speed of the rotor and an estimated value of a position of magnetic poles of the rotor based on a value of the current detected by the current detector and a parameter value indicating an interlinkage magnetic flux caused by the permanent magnet across the winding; a control unit configured to control the drive portion to cause the rotating magnetic field based on the estimated value of the rotational speed and the estimated value of the position of the magnetic poles; and a correction portion configured to correct the parameter value indicating the interlinkage magnetic flux based on correction information, the correction information being determined based on a temperature of the winding and a relationship between the temperature of the winding and a temperature of the permanent magnet.