SRM Rotor Angle Estimation Using Dual Non-Energized Phases
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Switched reluctance machines (SRMs) operating in extreme environments, such as aerospace applications, face challenges in determining the rotor angle accurately due to the failure of electro-mechanical sensors caused by temperature and vibration, necessitating a sensorless method.
Innovation Solution
A controller for SRMs injects a high-frequency signal into two non-energized phases, measures the current, and applies an algorithm to determine the rotor angle, utilizing signal processing and averaging to enhance accuracy and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an electro-mechanical sensor is used to determine rotor angle, then the rotor angle can be determined, but the sensor may fail in extreme temperatures and vibrations
Solution Approach 1:
The patent replaces the electro-mechanical sensor with an electrical measurement system. Instead of using a physical sensor that is susceptible to environmental damage, the system uses signal injection into the machine phases and processes the electrical current responses to determine rotor angle, thereby eliminating the vulnerable mechanical component.
Solution Approach 2:
The patent introduces an intermediary measurement approach by injecting signals into the non-energised phases and using the resulting current measurements as an intermediate step to infer rotor angle. This indirect measurement method avoids direct contact with extreme environmental conditions that would damage a physical sensor.
2Measurement precision
If a signal is injected into only one non-energised phase, then the rotor angle can be determined, but the determination is susceptible to errors from noise or interference
Solution Approach 1:
The patent merges the measurements from two concurrently non-energised phases to determine the rotor angle. By combining information from both phases, the system achieves better measurement reliability as errors or noise in one phase can be compensated by the other, producing a more robust angle determination.
Solution Approach 2:
The patent applies different processing approaches to different phases based on their local characteristics. Each phase's current measurement is processed independently through filtering and algorithmic treatment, allowing optimization for each phase's specific noise profile while maintaining overall system reliability.
3Reliability
If a high frequency injection signal is used, then the rotor angle determination is more reliable, but torque ripple and acoustic noise may increase
Solution Approach 1:
The patent uses partial action by injecting the high-frequency signal only during specific intervals when the phases are non-energised, rather than continuously. This limited-time injection provides sufficient measurement data for reliable angle determination while minimizing the duration of high-frequency excitation, thereby reducing torque ripple and acoustic noise generation.
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
The method provides a robust and accurate determination of the rotor angle, reducing errors from electromagnetic interference and ensuring efficient operation of SRMs as motors or generators.
Implementation Method 1
in an injection stage, inject a signal into the two non-energised phases
Implementation Method 2
switched reluctance machine (SRM) includes a plurality of phases, a stator and a rotor
Data Source
AI summary
A controller for a switched reluctance machine, the machine comprising two concurrently energised phases and two concurrently non-energised phases. The controller is configured to, in an injection stage, inject a signal into the two non-energised phases; in a measurement stage, determine a current in each of the two non-energised phases; and in a calculation stage, apply an algorithm to the determined currents to determine a rotor angle.