Synchronous Machine Rotor Angle Detection Using Iterative Inductance Pulses
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Solution Overview
Problem
Existing methods for detecting the absolute angular position of electric motors, particularly synchronous machines, are complex, prone to errors, and require additional components or complex calculations, making them inaccurate and costly.
Innovation Solution
A method that uses inductance measurements from stator windings to determine the angular position of the rotor without additional sensors, employing a simplified calculation and iterative approach to achieve precise angle detection with minimal components and low computational power, allowing for high-resolution angle determination across 360°.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate sensors (inductive or optical) are used for angle detection, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The motor's own windings and rotor structure are utilized to detect rotor position through inductance measurements, eliminating the need for separate angle sensors. The motor serves itself by using its inherent components for both actuation and sensing functions.
Solution Approach 2:
The stator windings serve dual purposes: generating electromagnetic torque and simultaneously providing inductance measurements for rotor position detection. This multi-functionality eliminates dedicated sensor components while maintaining measurement capability.
2Measurement precision
If interpolation-based methods are used to determine rotor angle, then measurement precision is improved, but device complexity and computational requirements increase
Solution Approach 1:
The patent transforms the complex interpolation problem into a simpler parameter comparison task by measuring inductance at multiple discrete angular positions and using the measured values directly to determine rotor position, avoiding complex mathematical interpolation while maintaining precision.
3Measurement precision
If additional sensors and components are added for angle detection, then measurement precision is improved, but reliability decreases due to additional error sources
Solution Approach 1:
The motor uses its own windings and magnetic circuit for position detection, eliminating separate sensor components that would introduce additional error sources. The inherent components are already part of the motor's reliable structure.
Solution Approach 2:
The sensing function is extracted from separate physical sensors and integrated into the motor's existing windings and control electronics, removing the unreliable external sensor components while retaining the measurement capability.
4Measurement precision
If complex calculation methods are used for angle determination, then measurement precision is improved, but productivity decreases due to high computational requirements
Solution Approach 1:
The patent changes the computational approach from complex interpolation calculations to simple comparison of inductance measurements, significantly reducing computational requirements while maintaining angle detection precision and enabling faster startup.
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 method enables precise, cost-effective, and robust absolute angle detection with minimal installation space, reducing external interference and eliminating the need for complex interpolation, thus achieving maximum torque quickly during startup.
Implementation Method 1
A magnetic field is generated by a large number of stator windings that are offset relative to one another
Implementation Method 2
The rotor having a fixed direction of magnetization
Data Source
Figure 1a~1b
Figure 2a~2c
Figure 3~4
AI summary
The invention relates to a method for determining the angular position of a synchronous machine having a magnetically anisotropic rotor, having an (m) iteration step and an (n) iteration step. The (m) iteration step comprises: generating an (m) magnetic field having an (m) angular direction and an intensity changing over time by applying an (m) voltage pulse to the synchronous machine, and detecting an (m) peak value of the current pulse generated by the (m) voltage pulse; and providing at least two further (m+i) peak values generated in different (m+i) angular directions by magnetic fields, said directions differing from the (m) angular direction. The (n) iteration step following the (m) iteration step comprises: determining the angular directions in which the two largest or the two smallest peak values from a peak value group occur, as the (n+1) angular direction and the (n+2) angular direction, wherein the peak value group comprises the (m) peak value and the further (m+i) peak values; and providing an (n) angular direction positioned between the (n+1) angular direction and the (n+2) angular direction, as the angular direction output. As an alternative, the (n) iteration step provides the following: an (n) angular direction positioned between the (n+1) angular direction and the (n+2) angular direction, as the (n) angular direction, in which an (n) magnetic field is generated at a intensity changing over time by applying an (n) voltage pulse to the synchronous machine. In this manner, an (n) peak value of the current pulse generated by the (n) voltage pulse is detected. An iteration method may comprise any arbitrary number of iteration steps. The invention further relates to a device for the active and iterative actuation of a synchronous machine in order to detect the angular position thereof.