Switched Reluctance Rotor Angle Estimation Using Dual-Phase Injection
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Solution Overview
Problem
Switched reluctance machines (SRMs) operating in extreme environments, such as aerospace, face challenges in determining the rotor angle without electro-mechanical sensors due to failure from extreme temperatures and vibrations.
Innovation Solution
A controller for SRMs that injects a high-frequency signal into two concurrently non-energized phases, determines the current in these phases, and applies an algorithm to calculate the rotor angle, utilizing signal processing and averaging from multiple phases to reduce errors and compensate for noise like EMI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an electro-mechanical sensor is used to determine rotor angle, then measurement precision is improved, but reliability deteriorates due to failure from extreme temperatures and vibrations
Solution Approach 1:
The patent replaces the electro-mechanical sensor with an electrical measurement system. Instead of using mechanical sensors that fail in extreme environments, the invention uses high-frequency signal injection into the machine phases and processes the resulting currents to determine rotor angle, thereby eliminating the mechanical component that causes reliability issues.
Solution Approach 2:
The patent introduces high-frequency signal injection as an intermediary method. Rather than directly measuring rotor angle with a sensor, the system injects signals into the phases and uses the resulting current responses as intermediaries to calculate the rotor angle, providing an indirect but more reliable measurement method.
2Device complexity
If signal is injected into only one non-energised phase, then device complexity is reduced, but measurement precision deteriorates due to susceptibility to noise and EMI
Solution Approach 1:
The patent divides the measurement task across multiple phases. Instead of relying on a single phase for rotor angle determination, the system injects signals into two concurrently non-energised phases and processes both current responses, segmenting the measurement function to improve accuracy and noise resistance.
Solution Approach 2:
The patent applies different processing treatments to the currents from different phases. Each phase's current response is processed individually through signal processing and algorithm application, allowing local optimization and compensation for phase-specific noise or interference before combining results.
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 provides a more reliable determination of the rotor angle, reducing errors and ensuring accurate operation of SRMs in harsh conditions by using multiple phase information and minimizing torque ripple and acoustic noise.
Implementation Method 1
in an injection stage, inject a signal into the two non-energised phases
Implementation Method 2
in a calculation stage, apply an algorithm to the determined currents to determine a rotor angle
Data Source
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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.