Stand Mixer Sensorless BLDC Motor Control to Avoid Stall Under Load

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Stand mixers using brushed direct current (DC) motors face issues with motor life and maintenance costs due to brush degradation, and they struggle with stall conditions under heavy load conditions.

Innovation Solution

The implementation of a synchronous-type motor with a three-phase motor drive operating in a sensorless field-oriented control (FOC) scheme, along with a feedback system that uses a back electromotive force (EMF) observer to maintain motor control and avoid stall conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If brushed DC motors are used in stand mixers, then the motor can provide reliable torque for mixing operations, but the brushes break down over time resulting in decreased motor life and increased maintenance costs

Engineering Contradiction:

Improvemotor lifeVSAvoidmaintenance costs

Core Design Contradiction:

ReliabilityVSEase of repair

Solution Approach 1:

The patent replaces the brushed DC motor with a brushless DC motor (BLDC) that uses electronic commutation instead of mechanical brushes. The BLDC motor employs a three-phase inverter and controller to electronically switch current phases, eliminating the mechanical brush contact that causes wear and maintenance issues while maintaining the required torque characteristics for stand mixer operations

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If a synchronous-type motor with sensorless FOC is used, then the motor can operate efficiently at variable speeds, but stall conditions may occur under heavy load conditions

Engineering Contradiction:

Improvemixing efficiencyVSAvoidstall avoidance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent implements a feedback mechanism using a back-EMF observer that monitors the motor's electrical characteristics to detect stall conditions. The observer analyzes the relationship between applied voltage, current, and generated back-EMF to determine rotor position and speed. When a stall is detected (indicated by abnormal back-EMF patterns or current characteristics), the controller adjusts the inverter output to prevent sustained stalling, allowing the motor to recover and continue operation under heavy load conditions

Inventive Principle:

Principle #23Feedback

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 solution provides a reliable and efficient motor drive for stand mixers, maintaining control even under heavy load conditions and reducing maintenance costs by extending the life of the motor and avoiding stall conditions.

Implementation Method 1

a feedback system that uses a back electromotive force (EMF) observer to maintain motor control and avoid stall conditions

Methodology Applied

Scientific EffectBack electromotive force (EMF): Electromagnetic Induction

Data Source

PatentUS12341459B2Method for avoiding stalled motor in a stand mixer with sensorless BLDC drive

Publication Date: 2025.06.24 HAIER US APPLIANCE SOLUTIONS INC

AI summary

A method for operating an appliance, such as a stand mixer, is provided. In one example implementation, the method can include operating a motor of the appliance in a first direction. The method can further include detecting, by a feedback system of the appliance, a first trigger condition. The method can further include, responsive to detecting the first trigger condition, operating the motor of the appliance in a second direction that is different than the first direction.