Switched Reluctance Generator Rotor Position Calibration
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Solution Overview
Problem
Current electric drive systems for switched reluctance generators face inefficiencies due to errors in initial rotor position detection, leading to substantial losses in efficiency, especially when sensor alignment is skewed or mechanically misaligned.
Innovation Solution
A method and system that estimate rotor speed and position by providing a source current to the stator, using sensor signals and phase currents to determine relative and absolute rotor positions, and calibrating sensor signals to eliminate offsets, thereby improving detection accuracy and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a mechanically aligned speed wheel is used to keep track of rotor position, then the system structure is simple, but measurement precision deteriorates due to sensor skew and mechanical misalignment
Solution Approach 1:
The patent replaces the mechanical speed wheel and sensor-based position detection system with an electrical field-based detection method. By measuring the electrical characteristics (current, voltage, frequency) of the generator phases, the system determines rotor position without mechanical sensors, thereby eliminating misalignment errors while maintaining structural simplicity.
Solution Approach 2:
The patent introduces electrical parameters (phase currents, voltages, frequencies) as an intermediary to indirectly determine rotor position. Instead of directly measuring mechanical position with sensors that require precise alignment, the system uses electrical field variations caused by rotor position to infer the position accurately without mechanical contact or alignment.
2Device complexity
If sensor alignment is skewed or mechanically misaligned, then device complexity remains low, but efficiency deteriorates due to position detection errors
Solution Approach 1:
The patent eliminates the need for precise mechanical alignment by replacing the mechanical sensor-based system with an electrical field-based detection system. The rotor position is determined through electrical measurements of phase currents and voltages, which are inherently synchronized with the rotor position through electromagnetic induction, thereby maintaining efficiency without alignment precision requirements.
Solution Approach 2:
The system uses its own electrical operating parameters (phase currents, voltages, frequencies) to determine rotor position. The generator's electromagnetic field naturally provides the position information through its electrical characteristics, eliminating the need for external mechanical alignment or separate sensing systems.
3Ease of manufacture
If traditional sensor-based position detection is used, then initial implementation is simple, but reliability deteriorates due to susceptibility to errors from skew and misalignment
Solution Approach 1:
The patent replaces mechanical sensor systems with electrical field-based detection, eliminating the reliability issues associated with mechanical skew and misalignment. The electrical measurements are inherently synchronized with rotor position through electromagnetic principles, providing reliable position detection without mechanical contact or alignment concerns.
Solution Approach 2:
The patent uses electrical parameters as an intermediary to reliably determine rotor position. By measuring phase currents, voltages, and frequencies—which are naturally coupled to rotor position through electromagnetic induction—the system achieves reliable position detection without the vulnerabilities of mechanical sensor systems.
Data Source
AI summary
A method of estimating rotor speed of a generator 106 having a rotor 110 and a stator 112 is provided. The method may provide a source current to the stator 112, determine a relative rotor speed based on a sensor signal provided by a rotor speed sensor 130, determine a relative rotor position corresponding to the relative rotor speed, determine an absolute rotor position based on the sensor signal and phase currents, and calibrate the sensor signal based on an offset between the relative rotor position and the absolute rotor position.