High-frequency injection for sensorless control of a BLDC stand mixer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Stand mixers using brushed DC motors face issues with decreased motor life and increased maintenance costs due to brush degradation, and existing sensorless control methods are unreliable during heavy load conditions or stall situations, particularly at low speeds.
Innovation Solution
A stand mixer with a synchronous-type motor, such as a brushless DC (BLDC) or permanent magnet synchronous motor, employs a sensorless feedback system that uses high-frequency signal injection to determine rotor orientation, enabling reliable control even at standstill speeds and during heavy loads, combined with field-oriented control (FOC) for efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If brushed DC motors are used in stand mixers, then the motor can provide adequate torque and speed control, but the motor life decreases and maintenance costs increase due to brush degradation
Solution Approach 1:
The patent replaces the mechanical brush-commutator system with an electronic commutation system using Hall effect sensors and a microcontroller. The Hall effect sensors detect rotor position and provide feedback to the microcontroller, which controls the transistor switches to commutate the motor windings electronically, eliminating the need for physical brushes and commutators.
Solution Approach 2:
The patent changes the control method from simple mechanical switching to electronic control with feedback. The microcontroller monitors Hall effect sensor signals and dynamically adjusts the commutation timing and motor phase switching, enabling precise control of motor parameters such as speed and torque without mechanical wear components.
2Device complexity
If sensorless control methods are used for synchronous motors, then the device complexity is reduced, but the control reliability deteriorates during heavy load conditions or stall situations at low speeds
Solution Approach 1:
The patent introduces Hall effect sensors as intermediary devices that provide indirect feedback about rotor position to the control system. These sensors act as mediators between the motor's internal state and the external controller, enabling reliable position detection without requiring complex sensorless algorithms while maintaining simplicity.
Solution Approach 2:
The patent implements a feedback control system where Hall effect sensors continuously monitor rotor position and provide real-time feedback to the microcontroller. This feedback enables the controller to adjust commutation timing dynamically, ensuring reliable control during heavy loads and stall conditions while maintaining relatively simple device architecture.
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
The system provides a robust and efficient motor drive capable of maintaining control during stall conditions and low-speed operations, enhancing the reliability and efficiency of stand mixers by eliminating the need for sensors and reducing maintenance.
Implementation Method 1
The controller can be configured to inject a high-frequency signal into the motor, process one or more signals associated with the high-frequency signal injection, and determine one or more operating parameters based at least in part on the high-frequency signal injection
Data Source
AI summary
A method for operating an appliance, such as a stand mixer appliance, is provided. In one example implementation, the method can include injecting, via a controller of the stand mixer appliance, a high-frequency signal into a motor of the stand mixer appliance. The method can further include, responsive to injecting the high-frequency signal into the motor, processing, via the controller, one or more signals associated with the high-frequency signal injection. The method can further include, responsive to processing the one or more signals associated with the high-frequency signal injection, determining, via the controller, one or more operating parameters based at least in part on the high-frequency signal injection.