Sensorless Motor Control Rotor Position Estimation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing sensorless motor control systems face challenges in accurately estimating rotor position, especially in high torque ranges due to magnetic saturation, which leads to angular errors and requires compensation for inductance changes based on driving points.
Innovation Solution
A motor control apparatus that includes a current controller, high frequency voltage generator, inverter, angle estimator, and compensator, which generates compensation signals to correct the current signal input to the angle estimator, considering torque commands and rotor positions, and uses reference tables to determine optimal compensation values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If signal injection method is used for sensorless motor control, then sensor cost and complexity are reduced, but angular error increases due to magnetic saturation in high torque region
Solution Approach 1:
The patent changes the parameter of inductance by estimating it through signal injection and using it to compensate the current signal. By dynamically adjusting the compensation based on estimated inductance values, the system maintains accurate rotor position estimation even under magnetic saturation conditions in high torque regions, thus resolving the contradiction between sensorless operation and measurement precision
Solution Approach 2:
The patent replaces the mechanical sensor-based position detection system with an electrical signal injection and estimation system. By injecting high-frequency signals and processing the resulting current responses through coordinate transformations and inductance estimation, the system substitutes physical sensors with computational methods, reducing hardware complexity while maintaining position estimation capability
2Device complexity
If conventional angle estimation method is used, then device complexity is reduced, but estimation accuracy deteriorates when current trajectory becomes circular due to magnetic saturation
Solution Approach 1:
The patent implements feedback by continuously estimating inductance from the current signal response to high-frequency voltage injection, and using this estimated inductance to compensate the current signal fed back to the angle estimator. This closed-loop feedback mechanism corrects the circular current trajectory distortion caused by magnetic saturation, maintaining angular estimation accuracy without increasing overall system complexity
Solution Approach 2:
The patent performs preliminary inductance estimation and compensation signal generation before the angle estimation process. By pre-calculating the compensation amount based on estimated inductance values and applying it to the current signal, the system prepares corrected input data for the angle estimator, ensuring accurate estimation even when the raw current trajectory becomes circular due to saturation
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 approach allows for accurate rotor position estimation across various driving points by correcting the magnitude and shape of the signal input to the angle estimator, reducing angular errors and enabling stable sensorless control in high torque ranges.
Implementation Method 1
a position information estimating technology through signal injection is widely used
Implementation Method 2
as a specific high frequency signal voltage is applied from an estimated synchronous coordinate system of a motor, a current having the same frequency as the voltage applied to a dq-axis on the estimated synchronous coordinate system appears at the motor stator
Data Source
AI summary
A motor control apparatus according to one embodiment of the present invention comprises: a current controller for generating a voltage command signal on the basis of a torque command for driving a motor and a fundamental wave current of the motor; a high frequency voltage generator for generating a high frequency voltage signal for injection into the voltage command signal; an inverter for applying a voltage to the motor on the basis of the voltage command signal and the high frequency voltage signal; an angle estimator for generating an estimated angle of a rotor of the motor on an estimated coordinate system on the basis of a current signal of the motor; and a compensator for adding a first compensation signal (icomp) to the current signal (isig), wherein the first compensation signal (icomp) may be related to the torque command and the estimated angle.