Brushed DC Motor Rotation Detection via Complex Resistance
Solution Overview
Problem
Existing methods for detecting the rotation of brush-operated d.c. motors in automotive applications are costly and prone to failure due to the use of ring magnets or optical systems, which are susceptible to dirt.
Innovation Solution
A method that modulates an alternating voltage signal based on the rotation angle to detect changes in the complex resistance of the d.c. motor's winding branches, using electronic components like capacitors or resistors to amplify these changes, allowing for rotation detection without additional sensors or lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Hall sensors with ring magnets are used to detect rotation, then rotational speed and position can be detected, but additional costs and device complexity increase
Solution Approach 1:
The patent utilizes the d.c. motor's own winding branches and plates as the sensing elements. The complex resistance measurement system detects rotation by measuring changes in the motor's inherent electrical properties, eliminating the need for external Hall sensors and ring magnets. The motor structure serves dual purposes: both actuation and sensing.
Solution Approach 2:
The winding branches and plates of the d.c. motor are made to serve multiple functions: they are both part of the motor's actuation mechanism and the sensing elements for rotation detection. This multi-functionality reduces the overall device complexity by eliminating separate sensing components.
2Measurement precision
If optical systems are used to detect rotational speed, then detection can be achieved, but reliability decreases due to susceptibility to dirt
Solution Approach 1:
The patent replaces optical detection systems with an electrical measurement system. Instead of using light-based sensors that are susceptible to dirt and contamination, the invention uses electrical measurements of the motor's complex resistance, which are not affected by environmental contaminants like dirt.
Solution Approach 2:
The measurement system uses the motor's own electrical components (winding branches and plates) as the sensing elements. This self-service approach eliminates the need for separate optical sensors that would be vulnerable to dirt and contamination in the automotive environment.
3Loss of information
If additional sensors and measurement lines are added to detect rotation, then rotational information can be obtained, but device complexity and cost increase
Solution Approach 1:
The patent makes the motor's existing electrical components serve dual purposes. The winding branches and plates that are already part of the motor structure are used as the sensing elements, eliminating the need for additional sensors and measurement lines. The motor structure itself provides the rotation information through changes in its electrical properties.
Solution Approach 2:
The electrical components of the d.c. motor are designed to perform both actuation and sensing functions. This multi-functionality allows rotation detection without adding separate sensing systems, thereby reducing device complexity and cost while still obtaining the necessary rotation information.
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 approach provides a cost-effective and reliable method for detecting rotation, reducing the need for additional sensors and minimizing power loss, while maintaining high resolution and accuracy.
Implementation Method 1
the course of the complex resistance of the d.c. motor is ascertained and used to detect the rotation
Implementation Method 2
using electronic components like capacitors or resistors to amplify these changes
Data Source
AI summary
a method and a device for detecting the rotation of a brush-operated d.c. motor comprising a number of winding branches which are electrically connected between brushes, during the operation of the motor, by means of plates, according to the rotational angle. According to the invention, an alternating voltage signal is modulated on the basis of a supply direct voltage for the brushes, by which means the course of the complex resistance of the direct current motor is determined and used for the detection of rotation. In this way, the invention enables a cost-effective rotation detection that can be used in motor vehicle technology without requiring additional mechanical components.