Sensorless Electric Motor Rotor Position Detection
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Solution Overview
Problem
Existing electric motor technologies face challenges in accurately determining the rotor position relative to the stator during operation, especially at low speeds, leading to inefficient operation and increased production costs due to the need for additional sensors.
Innovation Solution
A method that involves disconnecting all electromagnet elements from the power supply while the rotor rotates, measuring induced electrical quantities, and determining the rotor position without additional sensors, allowing for precise determination of rotational speed and number of revolutions by repeating these measurements at different times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional sensors (e.g., Hall sensors) are used to determine rotor position, then measurement precision is improved, but device complexity and production costs increase sharply
Solution Approach 1:
The electric motor uses its own electromagnet elements to determine rotor position by measuring induced electrical quantities during operation. The electromagnet elements serve dual purposes: generating magnetic fields for torque and acting as sensors for position detection, eliminating the need for separate sensor components
Solution Approach 2:
The electromagnet elements are designed to perform multiple functions: they generate magnetic fields for torque production and simultaneously serve as measuring instruments for rotor position detection by detecting induced electrical quantities during current disconnection phases
2Device complexity
If sensorless operation with one segment operated without current is used, then device complexity is reduced, but torque transmission is reduced and measurement precision deteriorates at low speeds
Solution Approach 1:
All electromagnet elements remain connected to the power supply and continue to generate torque continuously. The measurement process involves temporarily disconnecting current from all electromagnet elements simultaneously, but this is done in a coordinated manner that maintains continuous torque production through the interaction of multiple magnetic fields, ensuring uninterrupted useful action
3Measurement precision
If all electromagnet elements are disconnected from power supply for measurement, then measurement precision is improved, but torque transmission is interrupted
Solution Approach 1:
The current disconnection for measurement purposes is performed periodically and temporarily, with all electromagnet elements being disconnected simultaneously for brief measurement intervals. During these periods, the rotor's inertia maintains its motion, and the induced electrical quantities are measured. The disconnection and reconnection cycles are coordinated to minimize impact on continuous torque production
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
Enables reliable and efficient operation of electric motors at low speeds without additional sensors, reducing energy consumption and production costs by optimizing torque application and commutation strategies.
Implementation Method 1
If an electric current is now applied to some of the electromagnet elements, a magnetic field is generated which interacts with the magnetic field of the rotor and transmits a torque to the rotor
Implementation Method 2
measuring an electrical quantity induced in the electromagnet elements
Data Source
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AI summary
The invention relates to a method for operating an electric motor (1), wherein a first method is applied at a rotational speed below a predetermined limit value and a second method is applied at a rotational speed above the predetermined limit value, wherein the first method is a method for operating an electric motor (1) that has a stator (4) and a rotor (2), wherein the stator (4) or the rotor (2) has at least three segments (6) each having at least one electromagnetic element (8), wherein the first method comprises the following steps: a) simultaneously de-energizing all electromagnetic elements (8) of all segments (6) while the rotor (2) rotates, b) measuring an electrical quantity (12, 14, 16) induced in the electromagnetic elements (8), in particular an induced voltage, for each segment (6), c) determining a rotor position of the rotor (2) in relation to the stator (4) from the measured electrical quantities (12, 14, 16), and wherein the second method is a method for operating an electric motor (1) that has a stator (4) and a rotor (2), wherein the stator (4) or the rotor (2) has at least three segments (6) each having at least one electromagnetic element (8), to which electromagnetic elements an electrical current can be supplied such that a segment magnetic field is formed, by means of which field a segment torque is applied to the rotor (2), the intensity of which depends on a segment position of the rotor (2) in relation to the segment (6), wherein the second method comprises the following steps: A) determining an expected time (18) at which the segment torque of a zero-crossing segment, which is one of the at least three segments (6), is expected to be equal to zero, B) de-energizing all of the electromagnetic elements (8) of the zero-crossing segment for a first measurement time interval (22) and for a second measurement time interval (24), wherein the first measurement time interval (22) lies before the expected time (18) and the second measurement time interval (24) lies after the expected time (18), C) measuring an electrical quantity (12, 14, 16) induced in the electromagnetic elements (8) of the zero-crossing segment, in particular an induced voltage, within the first measurement time interval (22) and within the second measurement time interval (24), D) determining an actual time (20) at which the segment torque of the zero-crossing segment was equal to zero from the measured electrical quantities (12, 14, 16).