Motor Angle Estimation via Error Parameter Phase Correction

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Solution Overview

Problem

In sensorless motor control, the error parameter Xerr fluctuates and becomes disproportional to the angle error θerr near zero, degrading the accuracy of estimated rotator angle θest.

Innovation Solution

A phase correction mechanism is implemented to correct the error parameter Xerr, transforming it into a corrected error parameter Xec, which is used to accurately estimate the motor's speed and angle, ensuring high precision in motor control by aligning the zero-cross point with zero.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the error parameter Xerr is used directly for angle estimation without phase correction, then the estimation process is simple, but the accuracy of estimated rotator angle θest degrades when Xerr fluctuates and becomes disproportional to angle error θerr near zero

Engineering Contradiction:

Improveaccuracy of estimated rotator angleVSAvoidcomplexity of error parameter processing

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by transforming the error parameter Xerr through phase correction to obtain a corrected error parameter. This changes the phase angle parameter of Xerr to align its zero-cross point with zero, improving the proportionality between the error parameter and angle error near zero, thereby enhancing estimation accuracy without fundamentally changing the estimation architecture

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent substitutes a mechanical/proportional relationship assumption with a corrected mathematical model. Instead of relying on the direct proportionality between Xerr and θerr breaking down near zero, the phase correction applies a mathematical transformation to restore this proportionality, replacing the need for complex mechanical sensing with a refined computational approach

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If phase correction is applied to the error parameter to improve angle estimation accuracy, then the accuracy of motor angle and speed estimation is enhanced, but the processing complexity of the control system increases

Engineering Contradiction:

Improveaccuracy of motor angle and speed estimationVSAvoidcomplexity of control system processing

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The phase correction process modifies the phase parameter of the error parameter Xerr to align its zero-cross point with zero. This parameter transformation improves the linearity and proportionality of the error signal near zero, enabling more accurate angle and speed estimation while maintaining a relatively simple control structure

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The corrected error parameter is fed back into the angle and speed estimation process, creating a refined feedback loop. This feedback mechanism uses the phase-corrected signal to continuously improve estimation accuracy, allowing the system to maintain high precision while the increased processing complexity remains localized to the correction stage

Inventive Principle:

Principle #23Feedback

3Adaptability or versatility

If the zero-cross point of the error parameter is not aligned with zero, then the controllable range of angle error is limited, but aligning the zero-cross point requires additional phase correction processing

Engineering Contradiction:

Improvecontrollable range of angle errorVSAvoidphase correction processing requirement

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The phase correction process changes the phase parameter of the error parameter to align its zero-cross point with zero. This parameter adjustment expands the controllable range of angle error by ensuring the error parameter remains proportional to the angle error across a wider range, including near the zero-crossing region where uncorrected parameters would fail

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The phase correction is applied as a preliminary processing step before angle and speed estimation. By pre-aligning the zero-cross point of the error parameter, the system prepares the error signal in advance to ensure optimal performance across the full controllable range, preventing estimation errors before they occur

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS10133223B2Angle estimator, motor controller, motor driver, motor driving system, image forming apparatus, and conveyance device

Publication Date: 2018.11.20 RICOH CO LTD

AI summary

An angle estimator includes correction means for correcting a phase of an error parameter to obtain a corrected error parameter and estimation means for calculating an estimated speed and an estimated angle of the motor based on the corrected error parameter. The error parameter is a function of an angle error representing a difference between an actual angle and an estimated angle of a motor.