Sensorless BLDC Motor Control for Stand Mixer Reliability
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Solution Overview
Problem
Stand mixers using brushed DC motors face reduced motor life and increased maintenance costs due to brush degradation, necessitating a more reliable and efficient motor drive system.
Innovation Solution
Implementing a synchronous-type motor with a three-phase motor drive operating in a sensorless six-step commutation scheme, utilizing a sensorless feedback system to obtain feedback measurements of electrical characteristics and a controller for precise motor operation without additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If brushed DC motors are used in stand mixers, then the motor can provide sufficient torque and speed control, but the brushes break down over time reducing motor life and increasing maintenance costs
Solution Approach 1:
The patent removes the brushes and commutator from the motor system by transitioning to a brushless DC motor design. The mechanical contact components (brushes) are extracted and replaced with electronic commutation using Hall effect sensors and a controller, eliminating wear and maintenance issues associated with brush degradation
Solution Approach 2:
The patent replaces the mechanical brush-and-commutator contact system with an electronic control system. The mechanical commutation is substituted with electronic switching controlled by a microcontroller that uses feedback from Hall effect sensors to determine rotor position and control stator winding activation sequences
2Measurement precision
If sensors are added to the motor drive system for feedback control, then motor operation precision is improved, but the system becomes more complex and sensors become damage-prone
Solution Approach 1:
The patent uses Hall effect sensors as intermediary devices that detect the magnetic field position of the rotor and convert it into electrical signals for the controller. These sensors act as mediators between the mechanical rotor position and the electronic control system, enabling precise commutation without requiring direct mechanical contact or complex measurement systems
Solution Approach 2:
The patent implements a feedback control system where Hall effect sensors continuously monitor rotor position and provide real-time information to the controller. The controller uses this feedback to dynamically adjust the switching sequence of the stator windings, ensuring precise motor control and optimal torque production throughout the rotation cycle
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
Provides a highly reliable and efficient motor drive system for stand mixers, reducing maintenance costs and improving operational reliability through a sensorless feedback system that eliminates the need for damage-prone sensors.
Implementation Method 1
the sensorless feedback system may obtain feedback measurements of the back electromotive force (BEMF) voltage of the floating phase winding
Implementation Method 2
a motor configured to provide torque to one or more driveshafts
Data Source
AI summary
A stand mixer appliance is provided. The stand mixer includes a base, a housing pivotally mounted to the base, a mixer shaft rotatably mounted on the housing, and a motor assembly. The motor assembly includes a motor having at least a rotor and a stator and is operably coupled to the mixer shaft such that the mixer shaft is rotatable by the motor, a motor drive, a sensorless feedback system having one or more feedback circuits coupled to the motor drive, and a controller operably coupled to the sensorless feedback system. The sensorless feedback system is configured to obtain feedback measurements of one or more electrical characteristics of the stator. The controller is configured to implement a six-step commutation control scheme and is further configured to operate the motor drive based at least in part on the feedback measurements obtained by the sensorless feedback system.