Direct-Drive DC Mixer Motor Control for Intermittent Load Management
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing mixers face challenges in maintaining consistent motor speed and preventing current overload during intermittent loading conditions, such as when using a dough hook in a stand mixer, which can lead to motor damage and inefficient mixing.
Innovation Solution
A stand mixer with a motor control system that includes an electronic controller, current sensor, and driver circuit, which uses a substantially continuous function to adjust motor speed and current limits, ensuring smooth operation by incrementally reducing speed when current limits are exceeded, and employing a planetary gear system for complex rotational motion of mixing elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a planetary gear system is used to provide complex rotational motion for mixing elements, then mixing performance is improved, but the motor is subject to intermittent loading which can cause speed fluctuations and potential damage
Solution Approach 1:
The motor control system continuously monitors motor current and RPM, comparing actual values against target values. When deviations are detected due to intermittent loading from the planetary gear system, the controller adjusts motor power delivery in real-time to maintain consistent speed and prevent overload
Solution Approach 2:
The system dynamically adjusts motor operating parameters based on real-time load conditions. The controller modifies power delivery to the motor according to actual current consumption and speed feedback, enabling the motor to adapt to the varying load demands imposed by the planetary gear system during mixing operations
2Productivity
If motor speed is increased to improve mixing efficiency, then productivity is improved, but the risk of current overload and motor damage increases
Solution Approach 1:
The system monitors motor current in real-time and compares it against safe operating limits. When current approaches dangerous levels, the controller automatically reduces power delivery to prevent overload, allowing the motor to operate at high speeds safely within established current boundaries
Solution Approach 2:
The controller dynamically adjusts motor operating parameters including power delivery and speed based on real-time current measurements. By changing these parameters responsive to load conditions, the system maintains high mixing efficiency while preventing current from exceeding safe thresholds that could damage the motor
3Ease of operation
If a traditional gear system is used to transmit motor power to mixing elements, then mechanical motion is achieved, but speed control precision and responsiveness are reduced
Solution Approach 1:
The patent replaces traditional mechanical transmission systems with direct-drive architecture controlled by electronic systems. The motor control system uses electronic feedback and power delivery adjustment to achieve precise speed control, eliminating the need for complex mechanical gear systems while maintaining or improving control responsiveness and precision
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A mixer (10) comprising: a DC motor (18) having an output shaft (60); a revolutions-per-minute sensor (62) operable to generate a speed signal indicative of a rotational speed of the output shaft (60); a mixing element (24) coupled to the output shaft (60) of the DC motor (18); and an electronic controller (50) configured to accept the speed signal and for controlling an electrical energy applied to the DC motor (18) to control the motor speed and a resultant speed of the mixing element (24), wherein the electrical energy applied to the DC motor (18) is controlled with respect to a reference voltage.