Rotor Position Detection Using High-Frequency Current Response
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Solution Overview
Problem
Existing methods for determining the absolute angular position of a rotor in multi-phase induction machines are inefficient, requiring significant effort and often relying on sensors or complex signal processing.
Innovation Solution
A method that generates a rotary field using a multi-phase test signal, measuring phase currents, and calculating products of current values to determine the angular position without the need for encoders, leveraging high-frequency signals and saturation effects in the stator iron.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-frequency signals are injected into the motor to determine rotor position, then measurement precision is improved, but device complexity increases due to required filtering and phase locked loops
Solution Approach 1:
The patent extracts only the essential information needed for rotor position determination by directly evaluating the high-frequency current response components. Instead of using complex phase locked loops and multiple filtering stages, the method extracts the position information directly from the current response to the injected high-frequency voltage, simplifying the overall system while maintaining measurement precision.
Solution Approach 2:
The patent uses the natural magnetic coupling between stator and rotor to create a simplified measurement system. By injecting high-frequency voltage into the stator windings and measuring the resulting current response, the system effectively copies the rotor position information through magnetic field interaction, eliminating the need for complex sensor systems or multiple processing stages.
2Measurement precision
If sensors or encoders are used to measure angular position, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent makes the motor itself serve the dual purpose of both actuation and position sensing. By utilizing the motor's own windings and magnetic fields to generate and detect position information through high-frequency signal injection, the system eliminates the need for separate sensors or encoders. The motor structure and operation are used to provide the measurement function, reducing device complexity and cost while maintaining precision.
3Measurement precision
If complex signal processing methods are used to determine rotor position, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The patent replaces complex mechanical or electronic sensor systems with an electrical signal processing approach. By injecting high-frequency voltage signals and evaluating the resulting current responses, the system uses electrical measurements and simple signal evaluation to determine rotor position, replacing what would otherwise require complex mechanical encoders or multiple sensor systems, thereby improving ease of operation.
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 significantly reduces the effort required to determine the angular position, providing accurate readings with minimal preparation, applicable to both salient and non-salient pole machines, and is suitable for field-oriented control, torque control, and speed control.
Implementation Method 1
A rotary field is generated in the rotary field machine with the aid of a multi-phase test signal
Implementation Method 2
leveraging high-frequency signals and saturation effects in the stator iron
Data Source
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AI summary
The present invention relates firstly to a method for determining the absolute angular position of a rotor of a multiphase rotating field machine without a sensor. Furthermore, the invention relates to a multiphase rotating field machine in which the angular position of its rotor can be measured without a sensor. In one step of the method according to the invention, a rotating field is generated with a multiphase test signal. The phase currents caused by the multiphase test signal are measured. In a further step, two current values iα and iβ, related to a two-phase system, are determined from the measured phase currents. According to the invention, two products iα·iα·iβ and iβ·iα·iβ are formed from the current values iα and iβ. Finally, an arc function value is determined for a quotient of the two products formed.