Sensorless Motor Control Phase Region Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The stability of sensorless control for permanent magnetic synchronous motors is compromised due to parameter errors in the motor and inverter, leading to inaccurate axial position estimation and potential step-out issues, especially at low revolution ranges.
Innovation Solution
A motor control device that includes current detecting, applied voltage detecting, rotor position detecting, and revolution number detecting means, with phase voltage setting means that defines a stable operation current phase region by accounting for individual differences in the motor and inverter, using data tables and interpolation to set target currents that prevent sensorless uncontrollable states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If sensorless control is used to eliminate physical sensors, then device complexity is reduced, but measurement precision of rotor position deteriorates due to parameter errors
Solution Approach 1:
The patent implements feedback control by continuously monitoring the actual current phase and comparing it with the target current phase. The axial position estimation error is calculated based on this phase difference, and feedback control is applied to correct the current phase commands, thereby compensating for parameter errors and improving rotor position detection accuracy without physical sensors.
Solution Approach 2:
The patent dynamically adjusts control parameters including current phase commands and axial position estimation based on detected operating conditions. By changing parameters adaptively according to actual motor behavior rather than relying on fixed model parameters, the system maintains accurate rotor position estimation despite parameter variations in the motor and inverter.
2Productivity
If maximum torque/current control is applied without considering parameter errors, then productivity is improved, but reliability deteriorates due to unstable sensorless control at low revolution ranges
Solution Approach 1:
The patent transitions from static maximum torque/current control to dynamic control that adapts to operating conditions. The control system continuously updates current phase commands and axial position estimation based on real-time feedback, making the control strategy flexible and adaptive. This dynamic approach maintains motor efficiency while ensuring stable sensorless control across the entire revolution range including low speed regions.
Solution Approach 2:
The patent modifies control parameters dynamically based on operating conditions rather than using fixed optimal parameters. By adjusting current phase commands and position estimation adaptively according to actual motor behavior and detected revolution range, the system maintains both high efficiency and reliability across varying operating conditions.
3Ease of operation
If assumed values from mathematical models are used for control parameters, then ease of operation is improved, but manufacturing precision requirements increase due to individual differences in motors and inverters
Solution Approach 1:
The patent enables the control system to self-correct for parameter variations by using feedback from actual motor behavior. The system automatically detects axial position estimation errors and adjusts control parameters accordingly, eliminating the need for precise manual parameter matching during manufacturing. This self-adjusting capability maintains ease of operation while compensating for individual differences in motors and inverters.
Solution Approach 2:
The patent uses feedback control to automatically compensate for parameter variations. By continuously monitoring actual motor response and comparing it with expected behavior, the system detects deviations caused by manufacturing tolerances and automatically adjusts control parameters, thereby maintaining accurate control without requiring high manufacturing precision.
Data Source
AI summary
Phase voltage setting means defines an actual current phase region including a current phase error range based on parameters including an individual difference of at least any one of a motor and an inverter, defines a stable operation current phase region in which a rotor position can be detected through sensorless control, and sets, as a target current, an electric current obtained by adding a predetermined phase difference corresponding to the number of revolutions detected by revolution number detecting means to an electric current set by current vector control such that the actual current phase region is within the stable operation current phase region.