HRSRM Rotor Position Estimation from Self and Mutual Inductance
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Solution Overview
Problem
High rotor pole switched reluctance machines (HRSRMs) face challenges in accurate rotor position estimation due to a flatter self-inductance profile and neglect of mutual inductances, leading to unreliable position sensing without additional hardware or memory.
Innovation Solution
A sensorless control system utilizing a combination of self-inductance and mutual inductance values, measured through terminal parameters like voltage and current, to estimate rotor position accurately without a rotor position sensor, using a hybrid approach that includes determining self-inductance and mutual-inductance values and storing them for precise position estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If self-inductance of the phase coil is used for position estimation in HRSRM, then the method is simple to implement, but the position estimation becomes unreliable due to the flatter inductance profile
Solution Approach 1:
The patent combines self-inductance measurement and mutual inductance measurement into a unified control method. By merging these two measurement approaches, the system overcomes the limitation of using self-inductance alone in HRSRM, where the flatter inductance profile leads to unreliable position estimation. The combination provides complementary information that restores measurement precision without significantly increasing system complexity.
Solution Approach 2:
The patent uses a composite estimation approach by combining data from two different inductance measurements (self-inductance and mutual inductance). This is analogous to using composite materials - each measurement type provides different characteristics, and their combination creates a more robust and accurate position estimation system than either measurement could provide alone.
2Reliability
If mutual inductance measurement technique is used, then position estimation can be obtained, but accuracy is insufficient because only mutual inductance is utilized
Solution Approach 1:
The patent merges mutual inductance measurement with self-inductance measurement to create a hybrid estimation method. This combination leverages the strengths of both approaches: mutual inductance provides reliable position information while self-inductance adds complementary data, together achieving higher measurement precision and accuracy than either method alone.
3Measurement precision
If shaft position sensor is used for rotor position feedback, then accurate position information is obtained, but the system size, weight, and cost increase
Solution Approach 1:
The patent enables the HRSRM system to determine its own rotor position using electrical measurements (self-inductance and mutual inductance) taken from its own phase coils. This self-service approach eliminates the need for external shaft position sensors, thereby reducing system size, weight, and complexity while maintaining accurate position information through the hybrid measurement method.
Solution Approach 2:
The patent replaces the mechanical shaft position sensor with an electrical measurement-based estimation system. By substituting the mechanical sensing approach with electrical inductance measurements and computational estimation, the system achieves the same functional goal (accurate position feedback) without the physical sensor hardware, reducing overall system complexity.
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 system provides reliable, robust, and cost-effective accurate rotor position estimation for HRSRMs, eliminating the need for additional hardware and ensuring operation irrespective of motor speed or direction.
Implementation Method 1
determining self-inductance and mutual-inductance values
Implementation Method 2
determining self-inductance and mutual-inductance values
Data Source
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AI summary
A system and method for reliable control of a high rotor pole switched reluctance machine (HRSRM) utilizing a sensorless reliable control system. The method comprising: energizing at least one of the plurality of stator phases; measuring a first current value and time taken by the first current value to reach a first peak value or preset threshold value of current; determining a self-inductance value; storing the self-inductance value and the first current value for each of the stator phases; measuring a second current value and time taken by an adjacent un-energized stator phase to reach a second peak value of current; determining a mutual inductance value; storing the mutual inductance value and the second current value for each of the stator phases; estimating a rotor position utilizing the self- inductance and mutual inductance values; and controlling the HRSRM based on the estimated rotor position.