Dual-Star-Point Electric Motor for Sensorless Speed Tracking
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Solution Overview
Problem
High-speed electric motors face limitations due to the size constraint imposed by the stator, exposure to pressure differences leading to wear, and thermal stress issues, particularly in high-temperature environments where permanent magnets' functionality is compromised.
Innovation Solution
An electric motor design featuring a rotor with permanent magnets and a stator with pole feet and coils divided into two groups connected through different star points, allowing for independent control of drive and tracking coils to manage torque, speed, and position, reducing thermal stress and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the motor operates at high speeds to increase productivity, then the frictional heat in the motor gap increases, but the permanent magnets deteriorate due to high temperatures
Solution Approach 1:
The coil system is segmented into two independent groups (first coil group and second coil group) with different star points, allowing separate control of drive function and tracking function. This segmentation enables independent optimization of each function to resolve the contradiction between high-speed operation and magnet protection.
Solution Approach 2:
The invention changes the electrical connection parameters by introducing two different star points for the two coil groups, transforming the single-controlled system into a dual-controlled system. This parameter change enables independent current control for drive and tracking, allowing high-speed operation while protecting permanent magnets through separate current management.
2Measurement precision
If additional sensors are added to improve measurement precision for position and speed control, then the device complexity increases
Solution Approach 1:
The coil groups serve dual purposes: the first coil group provides drive function while the second coil group provides tracking function with position detection. The system uses its existing components (coils and star points) to perform both propulsion and sensing functions, eliminating the need for separate sensors and achieving self-service measurement.
Solution Approach 2:
The second coil group serves multiple functions simultaneously: it acts as a tracking coil for position detection and as part of the drive system. This multi-functionality allows the same component to provide both measurement and actuation, reducing device complexity while maintaining measurement precision.
3Ease of operation
If the stator size is increased to accommodate more coils for better control, then the rotor size is limited by the stator housing
Solution Approach 1:
The coil system is divided into two groups with different star points, allowing independent optimization of control capability without proportionally increasing overall stator size. Each coil group can be sized appropriately for its specific function (drive or tracking), improving control efficiency without excessive size increase.
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 design enhances the efficiency and reliability of high-speed electric motors by minimizing thermal stress, reducing wear, and maintaining optimal magnet performance, while eliminating the need for additional sensors, thus improving operational stability and longevity.
Implementation Method 1
The coils (301, 302, 303, 304) are arranged in such a way that a coil of the first group of coils is arranged between two coils of the second group of coils, viewed from the rotation axis of the rotor (100). A controller (500) is provided, which is designed to provide the coils of the first group of coils with drive signals in order to provide the rotor (100) with a torque relative to the stator (200).
Implementation Method 2
The rotor (100) comprises a first number of permanent magnets (101, 102, 103, 104). The rotor (100) is magnetically mounted in a contactless manner within the stator (200).
Data Source
Figure 1
Figure 2A~2B
Figure 3~4
AI summary
An electric motor comprises the following features: a rotor (100) with a first number of permanent magnets (101, 102, 103, 104), wherein each permanent magnet comprises a first circular sector; a stator (200) with a second number of pole feet, wherein a coil is wound around each pole foot of the second number of pole feet, and wherein a pole foot comprises a second circular sector which is smaller than the first circular sector, wherein a first group of coils (301, 302, 303, 304) are electrically conductively connected to one another by means of a first star point (311), and wherein a second group of coils (321, 322, 323, 324) are electrically conductively connected to one another by means of a second star point (331), wherein the second star point (331) is electrically insulated from the first star point (311), wherein one coil of the first group of coils is arranged between two coils of the second group of coils; and a controller (500) for applying drive signals to the first group (301, 302, 303, 304) of coils in order to provide the rotor (102) with a torque in relation to the stator (200), and for applying a control signal, which differs from the drive signals, to at least one coil (321, 322, 323, 324) of the second group of coils.