Sensorless Rotor Position Estimation Using Current Regulation Quality Index

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Solution Overview

Problem

The use of electromechanical sensors in IPM synchronous motor drive systems increases cost, size, weight, and complexity, and is prone to failures in harsh environments, necessitating the development of sensorless drive systems that can accurately estimate rotor position without physical sensors.

Innovation Solution

An adaptive speed-assisted position prediction scheme is implemented using a processor to estimate rotor position by obtaining a current regulation quality index and determining the estimated position based on this index and position estimation data, employing a combination of sliding mode observers and speed estimators to enhance system stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If electromechanical sensors (resolvers, optical encoders, hall-effect sensors) are used to obtain rotor position and speed, then measurement accuracy is improved, but device complexity, cost, size, and weight increase

Engineering Contradiction:

Improverotor position and speed measurement accuracyVSAvoidhardware wiring complexity and system structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the electromechanical sensors from the IPM synchronous motor drive system. By using sensorless control techniques with observers, the system obtains rotor position and speed information without physical sensors, thereby removing the associated hardware wiring complexity and structural burden while maintaining measurement capability through software-based estimation

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the electromechanical sensing system with an electronic/software-based observer system. Instead of using mechanical or electromagnetic sensors to directly measure rotor position and speed, the system uses mathematical models and observers to estimate these parameters electrically, substituting a mechanical measurement system with an electronic computation system

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If electromechanical sensors are mounted on the rotor, then rotor position measurement is improved, but system reliability deteriorates in harsh environments

Engineering Contradiction:

Improverotor position measurement capabilityVSAvoidsensor performance under harsh conditions

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent removes the vulnerable electromechanical sensors from the rotor assembly. By implementing sensorless control with observers that estimate rotor position and speed from electrical measurements, the system eliminates components that are prone to failure in harsh environments such as excessive temperature, super high-speed operation, and heavy load conditions

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The system uses its own electrical measurements and mathematical models to determine rotor position and speed without external sensing components. The observer-based sensorless control leverages the motor's back-EMF and current characteristics to self-determine its operational state, making the system inherently more reliable in adverse conditions

Inventive Principle:

Principle #25Self-service

3Device complexity

If sensorless drive systems with observers are used instead of sensors, then device complexity is reduced, but measurement precision and stability deteriorate

Engineering Contradiction:

Improvesystem structure and hardware requirementsVSAvoidrotor position estimation accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent implements observer-based sensorless control that uses feedback from electrical measurements (currents and voltages) to continuously estimate and update rotor position and speed. The observers process the electrical signals from the motor phases and provide feedback to the control system, enabling accurate position estimation without physical sensors

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The observer system performs multiple functions simultaneously: it estimates rotor position, determines rotor speed, and provides feedback for control adjustments. This multi-functional approach allows the system to achieve comprehensive measurement capability through a unified software-based solution rather than requiring separate sensing components for each parameter

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS10333439B2Methods of estimating a position of a rotor in a motor under transient and systems thereof

Publication Date: 2019.06.25 DEERE & CO

AI summary

At least one example embodiment discloses a method of estimating a position of a rotor in a motor. The method includes obtaining a current regulation quality index based on a current command and a measured current, determining an estimated position of the rotor based on the current regulation quality index and position estimation data and controlling the motor based on the estimated position of the rotor.