Sensorless Switched Reluctance Generator Control via Current Threshold
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Solution Overview
Problem
Conventional position sensors in switched reluctance generators often fail in harsh environments, limiting the reliability and universality of the system, and existing sensorless control methods require accurate mathematical models and are not suitable for phase current chopping control.
Innovation Solution
A position sensorless control method that detects the end position of maximum phase inductance by setting a current threshold and switching off the main switch when the current reaches this threshold, allowing the generator to enter a zero voltage natural freewheeling state, thereby determining the rotor position without external sensors or stored flux linkage data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a position sensor is installed in the switched reluctance generator, then the rotor position can be directly detected, but the construction complexity increases and reliability decreases in harsh environments
Solution Approach 1:
The patent removes the position sensor from the system entirely, extracting the sensing function and replacing it with a sensorless control method that uses existing electrical measurements (phase voltage and current) to estimate rotor position through an observer-based approach, thereby eliminating the reliability issues associated with physical sensors in harsh environments
Solution Approach 2:
The patent replaces the mechanical/electrical position sensor with a computational estimation approach using a state observer that processes electrical signals mathematically to derive rotor position information, substituting physical sensing with signal processing and mathematical modeling
2Measurement precision
If an accurate nonlinear mathematical model is established for sensorless control, then rotor position can be estimated accurately, but the device complexity and modeling requirements increase
Solution Approach 1:
The patent introduces a state observer as an intermediary computational mechanism that bridges the gap between measurable electrical quantities (voltage, current) and the unmeasurable rotor position, using the observer to process electrical signals through mathematical models and generate position estimates without requiring direct physical sensing
3Measurement precision
If phase current gradient method is used to detect peak current position, then end position of minimum inductance can be obtained, but the method is not suitable for phase current chopping control and limits speed adjustment range
Solution Approach 1:
The patent employs a dynamic state observer that continuously adapts to changing operating conditions including variable speeds and chopping control modes, using real-time electrical measurements to track rotor position dynamically rather than relying on static characteristics like peak current detection, thereby enabling versatility across different control strategies and speed ranges
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 enhances the reliability and universality of switched reluctance generators by eliminating the need for position sensors, offering high real-time response, stability, and dynamic performance, expanding their application domain and improving operational reliability.
Implementation Method 1
switched reluctance generator system comprises excitation power supply, windings of switched reluctance generator, and power converter
Data Source
AI summary
A control method for a switched reluctance generator employing dual switched-mode power converters does not require a position sensor. In the excitation stage, the upper tube and lower tube of the main switch of a phase in the power converter are switched on, and the phase current is detected. When the phase current rises to a preset threshold, the upper tube or lower tube of the main switch of the phase is switched off, changing the phase of the switched reluctance generator into a zero voltage natural freewheeling state. When the phase current drops to the valley value, the rotor position is the end position of maximum phase inductance of the phase. This rotor position is used as the switch-off position of the main switch of the phase of the switched reluctance generator, and the upper tube and lower tube for the main switch of the phase are switched off.