AC Motor Rotor Angle Detection Without Resolver

Solution Overview

Problem

Existing methods for driving AC motors require additional rotator location detecting apparatuses like resolvers, leading to increased size and manufacturing costs due to the need for additional components such as signal connection connectors, cables, and converters.

Innovation Solution

The method involves internally detecting the rotator angle of an AC motor by sequentially applying different dS-axis and qS-axis voltages and currents in a control injection period, using a matrix equation with an inductance matrix, voltage matrix, and current matrix to calculate the rotator angle without an additional rotator location detecting apparatus.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a resolver is used to detect rotator location, then measurement precision of rotator angle is improved, but device complexity and manufacturing cost increase due to additional components

Engineering Contradiction:

Improverotator angle measurement precisionVSAvoidapparatus complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The motor system uses its own existing components (stator windings, power supply, current sensors) to detect rotator position through injected voltages and measured current variations, eliminating the need for external detection apparatus. The system serves itself by utilizing its inherent electrical characteristics for position sensing.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The stator windings serve dual functions: they act as both the actuating components for motor operation and the sensing components for rotator position detection. The same electrical infrastructure used for motor control is also used for position measurement, reducing overall system complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Difficulty of detecting and measuring

If a resolver and associated components are added, then rotator location detection capability is improved, but manufacturing cost increases

Engineering Contradiction:

Improverotator location detection capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

Difficulty of detecting and measuringVSEase of manufacture

Solution Approach 1:

The motor system uses its own existing components (stator windings, power supply, current sensors) to detect rotator position through injected voltages and measured current variations, eliminating the need for external detection apparatus. The system serves itself by utilizing its inherent electrical characteristics for position sensing.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The detection function is extracted from a separate physical apparatus (resolver) and integrated into the control system using electrical measurements. The position detection capability is taken out from mechanical components and implemented through signal processing of electrical quantities already present in the system.

Inventive Principle:

Principle #2Taking out (Extraction)

3Measurement precision

If additional detection apparatus is added, then rotator angle measurement accuracy is improved, but apparatus size increases

Engineering Contradiction:

Improverotator angle measurement accuracyVSAvoidapparatus size

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

The motor system uses its own existing components (stator windings, power supply, current sensors) to detect rotator position through injected voltages and measured current variations, eliminating the need for external detection apparatus. The system serves itself by utilizing its inherent electrical characteristics for position sensing.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The position detection function is merged with the motor control system. The same stator windings used for motor actuation are also used for position sensing, and the detection signals are processed within the existing control circuitry, combining multiple functions into a single integrated system.

Inventive Principle:

Principle #5Merging (Combining)

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 reduces the size and manufacturing cost of the AC motor driving apparatus by eliminating the need for external rotator detection systems while maintaining accurate rotator angle determination.

Implementation Method 1

driving the AC motor by a dS-axis voltage, which is a voltage for an exciting current in a stationary reference frame, and a qS-axis voltage, which is a voltage for generating a rotational force in the stationary reference frame

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

obtaining a rotator angle by a dS-axis voltage value, a qS-axis voltage value, a dS-axis current value, and a qS-axis current value

Methodology Applied

Scientific EffectOhm's law and inductance relationship: Ohm's Law

Data Source

PatentUS8963459B2Method and apparatus for driving alternating-current motor

Publication Date: 2015.02.24 HANWHA AEROSPACE CO LTD

AI summary

A method of driving an alternating-current (AC) motor while periodically obtaining a rotator angle of the AC motor. The method includes: (a) driving the AC motor by a dS-axis voltage, which is a voltage for an exciting current in a stationary reference frame, and a qS-axis voltage, which is a voltage for generating a rotational force in the stationary reference frame, while sequentially applying different dS-axis voltages and different qS-axis voltages to the AC motor in a control injection period; and (b) obtaining a rotator angle by a dS-axis voltage value, a qS-axis voltage value, a dS-axis current value, and a qS-axis current value in the control injection period.