Sensorless SR Machine Control via Idle Phase Flux Decoupling
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Solution Overview
Problem
Existing control systems for switched reluctance machines are costly and prone to errors due to reliance on mechanical sensors and accumulation of offset errors, especially at low machine speeds and standstill, which affects efficiency and accuracy.
Innovation Solution
A sensorless control method that injects a test pulse into idle phases of the SR machine to determine rotor position based on decoupled flux values, calculated by subtracting mutual flux from total flux, allowing for accurate rotor position detection without mechanical sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mechanical sensors and speed wheels are used to detect rotor position, then rotor position detection is achieved, but system cost and complexity increase
Solution Approach 1:
The patent replaces mechanical sensors and speed wheels with an electrical measurement system that uses voltage flux integration and phase current analysis to determine rotor position. This substitution eliminates mechanical components while achieving accurate position detection through electrical characteristics of the SR machine phases.
Solution Approach 2:
The system uses the SR machine's own electrical characteristics (voltage and current in idle phases) to determine rotor position, rather than requiring external mechanical sensors. The machine's inherent electrical behavior during idle phase operation provides the necessary information for position detection.
2Measurement precision
If voltage integrator is used to compute total voltage flux, then rotor position can be determined, but offset errors accumulate at low speeds and standstill
Solution Approach 1:
The patent extracts only the relevant flux information from idle phases by integrating voltage only during the idle phase duration, rather than continuous integration. This selective integration approach prevents accumulation of offset errors that would occur with continuous integration, while still providing sufficient information for accurate rotor position determination at low speeds and standstill.
3Device complexity
If sensorless control is implemented to reduce cost, then system cost decreases, but offset error accumulation affects accuracy at low speeds
Solution Approach 1:
The system performs periodic voltage integration during each idle phase interval, using the periodic nature of SR machine operation to repeatedly update rotor position information. This periodic measurement approach allows the system to maintain accuracy at low speeds by continuously refreshing position data without requiring continuous integration that would accumulate errors.
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 reduces the cost and complexity of control systems, minimizes offset errors, and provides more accurate and reliable operation of SR machines at low speeds and standstill, enhancing efficiency and practicality.
Implementation Method 1
determining a decoupled flux value based at least partially on a total flux value corresponding to the test pulse and a mutual flux value
Data Source
AI summary
A method for determining rotor position of a switched reluctance (SR) machine having a rotor and a stator is provided. The method may include injecting a test pulse into one or more idle phases of the SR machine, determining a decoupled flux value based at least partially on a total flux value corresponding to the test pulse and a mutual flux value, and determining the rotor position based at least partially on the decoupled flux value.