Brushless DC Motor Phase Shift Calibration for Current Reduction

Solution Overview

Problem

Conventional brushless DC motors experience high power consumption due to position errors or low accuracy of Hall sensors and electronic components, leading to inappropriate phase shift positions of the rotor, which results in excessive phase current in coil windings.

Innovation Solution

A method for controlling a brushless DC motor that involves transmitting a phase-inversion signal after a stable state is reached, adjusting the phase shift by an offset electrical angle to find the optimum angle corresponding to the minimum phase current, and maintaining this adjustment to minimize power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If phase shift position is determined by Hall sensor or measuring unit, then motor can operate, but position errors or low accuracy cause high phase current and increased power consumption

Engineering Contradiction:

Improvephase shift position accuracyVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent applies preliminary action by performing phase shift calibration before normal motor operation. The system pre-determines the optimal phase shift position using a calibration routine that measures phase current at different offset angles and identifies the minimum current point. This preliminary calibration ensures that subsequent motor operation uses the optimal phase shift position, avoiding high power consumption during actual operation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback by continuously monitoring phase current and using this information to adjust the phase shift position. The system measures the actual phase current at the determined optimal position and uses this feedback to refine the phase shift calibration, ensuring the motor operates at minimum power consumption while maintaining accurate position control.

Inventive Principle:

Principle #23Feedback

2Measurement precision

If phase shift position is determined by Hall sensor or measuring unit, then motor can operate, but position errors cause excessive phase current in coil windings

Engineering Contradiction:

Improvephase shift position accuracyVSAvoidexcessive phase current

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent applies preliminary action by performing phase shift calibration before normal motor operation. The system pre-determines the optimal phase shift position using a calibration routine that measures phase current at different offset angles and identifies the minimum current point. This preliminary calibration ensures that subsequent motor operation uses the optimal phase shift position, avoiding high power consumption during actual operation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback by continuously monitoring phase current and using this information to adjust the phase shift position. The system measures the actual phase current at the determined optimal position and uses this feedback to refine the phase shift calibration, ensuring the motor operates at minimum power consumption while maintaining accurate position control.

Inventive Principle:

Principle #23Feedback

3Ease of operation

If conventional phase shift control is used, then motor operation is simple, but working efficiency is reduced due to high power consumption

Engineering Contradiction:

Improvecontrol simplicityVSAvoidworking efficiency

Core Design Contradiction:

Ease of operationVSProductivity

Solution Approach 1:

The patent applies preliminary action by performing phase shift calibration before normal motor operation. The system pre-determines the optimal phase shift position using a calibration routine that measures phase current at different offset angles and identifies the minimum current point. This preliminary calibration ensures that subsequent motor operation uses the optimal phase shift position, avoiding high power consumption during actual operation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies parameter changes by adjusting the phase shift angle parameter to its optimal value. The system varies the phase shift angle during calibration and identifies the specific angle that minimizes phase current. This optimized parameter setting maintains simple control operation while significantly improving working efficiency by reducing power consumption.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS8686674B2Method for controlling brushless DC motor

Publication Date: 2014.04.01 ZHONGSHAN BROAD OCEAN

AI summary

A method for controlling a brushless DC motor, comprising transmitting a phase-inversion signal to a motor control unit by a rotor position detecting unit after a motor enters a stable state, advancing or delaying phase shift by the motor control unit at an offset electrical angle, recording and comparing phase current values In at different offset electrical angles whereby obtaining an optimum offset angle αm corresponding to the minimum phase current value Imin, and advancing or delaying phase shift by the motor at the optimum offset angle αm. As the motor enters a stable state, the motor advances or delays phase shift at the optimum offset angle αm, at this time operating current of a coil winding of the motor is the minimum, which saves power and reduces cost.