Motor Rotor Initial Position Detection Using Input Voltage Comparison

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Solution Overview

Problem

Conventional motor driving devices face challenges in quickly determining the initial position of a rotor, leading to prolonged startup times, vibrations, and excessive noise due to the use of random pulse signals and square waveform signals.

Innovation Solution

A device and method utilizing an initial position detector, lookup table module, and controller to detect the initial rotor position by comparing input voltages and waveform parameter values, constructing an activating sine waveform signal to accurately position the rotor without vibration or noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If random pulse signals are output to position the rotor, then the rotor can be moved from unknown position to specified positioning position, but the positioning takes a long time and causes excessive startup preparation time

Engineering Contradiction:

Improveinitial position detection accuracyVSAvoidstartup preparation time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system performs preliminary action by detecting the initial rotor position before the motor starts running. The initial position detector measures the input voltage at each phase's voltage input terminal before power is applied, allowing the rotor position to be determined in advance without requiring time-consuming positioning operations after startup.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces the conventional mechanical positioning method (outputting pulse signals to move the rotor) with an electrical detection method. By measuring the input voltage characteristics at each phase terminal, the system electronically determines the rotor's initial position without mechanical movement, thereby eliminating startup preparation time and positioning vibrations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If random pulse signals are used to move the rotor to positioning position, then the rotor positioning is achieved, but the motor vibrates and fan shakes causing excessively high decibel noise

Engineering Contradiction:

Improveinitial position detection accuracyVSAvoidnoise and vibration

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent replaces the mechanical positioning process (which causes vibration and noise) with an electrical voltage measurement process. By detecting the input voltage at each phase terminal before motor operation, the system determines rotor position without mechanical movement, thus eliminating vibration and noise generation during the positioning phase.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system extracts only the necessary information (initial rotor position) by measuring the input voltage characteristics at each phase terminal. This extraction method obtains position data without requiring the motor to actually move or operate, thereby separating the detection function from the mechanical operation that causes harmful vibrations and noise.

Inventive Principle:

Principle #2Taking out (Extraction)

3Productivity

If square waveform signal with significantly changed potentials is used to drive the motor, then the motor can be driven to run, but it generates louder noise compared to sine waveform

Engineering Contradiction:

Improvemotor driving capabilityVSAvoidnoise

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent applies parameter changes by switching from square waveform signals to sine waveform signals for motor drive. The controller generates sine waveform drive signals that smoothly vary in amplitude and frequency, avoiding the abrupt potential changes characteristic of square waves. This parameter change maintains motor driving capability while significantly reducing electromagnetic noise and vibration.

Inventive Principle:

Principle #35Parameter changes

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

Enables rapid and precise detection of the motor's initial position, reducing startup time and noise, allowing the motor to run smoothly without vibrations or excessive noise.

Implementation Method 1

The initial position detector is connected to a voltage input terminal of each of the phases of the motor. The initial position detector is configured to detect an input voltage at the voltage input terminal before the motor runs.

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS10637376B1Device and method for automatically detecting initial position of rotor of motor

Publication Date: 2020.04.28 ANPEC ELECTRONICS CORPORATION

AI summary

A device and a method for automatically detecting an initial position of a rotor of a motor are provided. The device includes an initial position detector, a lookup table module and a controller. The initial position detector detects input voltages of the motor. The controller compares the input voltages with each other to determine the initial position of the rotor of the motor. The controller obtains a waveform pattern from the lookup table module to construct an activating waveform signal to be outputted to one of steps of the motor that corresponds to the initial position of the rotor to control the motor to run.