Accurate Magnetic Pole Position Estimation for AC Motors
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Summary
Problems
Existing methods for sensing the magnetic pole position in AC synchronous motors, particularly in linear motors, face inaccuracies due to initial position sensing errors, large static friction, and high calculation loads, leading to axis errors and reduced torque accuracy.
Innovation solutions
A magnetic pole position estimation method that controls the relative position or speed of the motor mover using a position/speed control unit, performing coordinate transformation with pole-error estimation values, and shifting current phases to approximate the true pole-error value, reducing detection errors and calculation load while maintaining accurate pole position estimation.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If the amplitude of the signal for magnetic pole position detection is increased to reduce estimation error, then the magnetic pole position estimation accuracy is improved, but the motor mover movements become larger and noises increase
Why choose this principle:
The patent changes the parameter of signal frequency instead of amplitude. By applying a detection signal at a specific frequency (resonant frequency of the motor mover), the system achieves high estimation accuracy without increasing signal amplitude, thereby avoiding large motor movements and excessive noises.
Principle concept:
If the amplitude of the signal for magnetic pole position detection is increased to reduce estimation error, then the magnetic pole position estimation accuracy is improved, but the motor mover movements become larger and noises increase
Why choose this principle:
The patent utilizes mechanical vibration by applying a detection signal at the resonant frequency of the motor mover. This causes the motor mover to vibrate at its natural frequency, amplifying the response to the detection signal and enabling accurate magnetic pole position estimation with minimal signal amplitude.
Application Domain
Data Source
AI summary:
A magnetic pole position estimation method that controls the relative position or speed of the motor mover using a position/speed control unit, performing coordinate transformation with pole-error estimation values, and shifting current phases to approximate the true pole-error value, reducing detection errors and calculation load while maintaining accurate pole position estimation.
Abstract
If there is static friction, the magnetic pole position estimation is completed at the time when error torque used for magnetic pole position estimation becomes less than the friction, so that there remains magnetic pole error. A problem has been that when the error torque becomes less than a forward static friction, there remains a positive magnetic pole deviation and when the error torque becomes less than a backward static friction, there remains a negative magnetic pole deviation. By shifting in the negative direction and the positive direction initial values for estimating a magnetic pole error in operation sets, a true pole-error estimation value is estimated in the use of a pole-error estimation value having a positive magnetic pole error obtained by the positive shift operation and a negative one obtained by the negative shift operation, which can reduce estimation error due to the static friction.