Hall Sensor Rotor Position Determination Without BEMF
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Solution Overview
Problem
Conventional multi-phase motor systems rely on Back Electro Motive Force (BEMF) detection for determining rotor position and velocity, which requires additional circuitry and can lead to inefficient operation if the relative position and velocity are inaccurately determined.
Innovation Solution
A method and system that determine the position and velocity of a rotor relative to a stator without relying on BEMF, by driving the motor with varying magnetic field strengths and analyzing the detection signals from hall sensors to calculate the rotor angles and detector alignment, allowing for precise control of the motor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If BEMF detection is used to determine rotor position and velocity, then rotor position information can be obtained, but additional circuitry is required and measurement precision may be insufficient leading to inefficient operation
Solution Approach 1:
The patent extracts the position detection function from the BEMF detection circuitry and implements it directly within the hall sensors themselves. The hall sensors are modified to include position determination circuitry that calculates rotor position based on magnetic field measurements, eliminating the need for separate BEMF detection circuits and reducing overall device complexity while improving measurement precision
Solution Approach 2:
The patent introduces an intermediary calculation process within the hall sensor that determines rotor position by analyzing the relationship between magnetic field strength and sensor output signals. This intermediary computation layer transforms raw magnetic field measurements into precise position information without requiring additional external circuitry
2Reliability
If BEMF detection is used for rotor position determination, then position information is available, but inaccuracies in relative position and velocity determination can lead to improper motor operation
Solution Approach 1:
The patent implements a feedback mechanism where the hall sensor continuously monitors magnetic field changes and adjusts its position calculations based on the relationship between driving signal amplitude and detection signal phase. This feedback loop ensures high measurement precision for both position and velocity, preventing improper motor operation and improving reliability
Solution Approach 2:
The patent performs preliminary calibration of the hall sensor system during motor initialization, establishing the correct phase relationship between driving and detection signals before normal operation begins. This preliminary action ensures accurate position and velocity measurements from the start, preventing operational errors
3Productivity
If hall sensors are used without alignment correction, then the system is simpler, but inaccurate sensor alignment leads to inefficient motor operation
Solution Approach 1:
The patent enables the hall sensor system to automatically determine and correct its own alignment relative to the stator winding. The sensor performs self-calibration by analyzing the phase relationship between driving and detection signals at different amplitudes, eliminating the need for external alignment tools or complex manual adjustment procedures while improving motor efficiency
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 approach enables accurate determination of rotor position and velocity without additional circuitry, improving motor efficiency and preventing improper operation, such as repulsion or termination of rotation, by using the phase and amplitude of driving signals to calculate rotor angles and correct sensor alignment.
Implementation Method 1
The stator can receive a driving signal to produce a first magnetic field
Implementation Method 2
The rotor can rotate in a circle relative to the stator. The rotor has a magnetic portion that can emit a second magnetic field in a radial direction
Implementation Method 3
The detector can output a detection signal based on the position of the rotor
Data Source
AI summary
A method is provided for monitoring a motor having a stator, a rotor and a detector. The stator can receive a driving signal to produce a first magnetic field. The rotor can rotate in a circle relative to the stator. The rotor has a magnetic portion that can emit a second magnetic field in a radial direction. The detector can output a detection signal based on the position of the rotor.