Motor Control Noise Filtering via Hall Sensor and Load Model
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Solution Overview
Problem
Existing motor control systems face challenges in accurately distinguishing noise from normal signals in hall sensors, leading to speed instability and potential overcurrent issues, especially at low speeds and high RPMs, due to the difficulty in filtering noise from hall sensor signals.
Innovation Solution
A motor control method that calculates the measured and predicted RPM values using a hall sensor signal and a motor system load model, detects noise by comparing these values, and adjusts torque or speed control based on the reliability of the hall sensor signals, using a plurality of sensors to ensure accurate motor control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a narrow filter band is set to reduce error between estimated and actual speed, then measurement precision is improved, but noise filtering effectiveness is degraded
Solution Approach 1:
The patent dynamically adjusts the filter band width based on the motor's operating speed. At low speeds where model accuracy is high, a narrow filter band is applied to maintain precise speed measurement while still providing adequate noise filtering. At high speeds where model-actual speed discrepancy increases, the filter band is widened to maintain noise filtering effectiveness. This dynamic approach resolves the contradiction by adapting filtering characteristics to operational conditions.
2Reliability
If hall sensor signals are used for motor control, then position detection is enabled, but noise from friction and device interaction degrades control accuracy
Solution Approach 1:
The patent introduces a speed estimation model based on counter electromotive force as an intermediary to filter and validate hall sensor signals. The model provides an estimated speed that serves as a reference to identify and remove noise from the actual hall sensor measurements. This intermediary approach maintains the reliability of position detection while improving measurement precision by eliminating noise caused by friction and device interaction.
3Device complexity
If digital hall sensor signals are used for motor control, then signal transmission is simplified, but noise signal distinction becomes impossible leading to control instability
Solution Approach 1:
The patent implements feedback by continuously comparing the speed estimated from the hall sensor signals with the speed predicted from the motor model. When discrepancies exceed a threshold, the system identifies potential noise contamination and adjusts control accordingly. This feedback mechanism maintains simple digital signal transmission while ensuring control stability by detecting and compensating for noise-induced 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 approach effectively filters noise from hall sensor signals, enhancing motor control accuracy and stability across all speed ranges, reducing the occurrence of overcurrent and improving the reliability of motor RPM measurement.
Implementation Method 1
a hall sensor is installed on each phase of the stator to detect the position of the rotor. The hall sensor has a potential difference that is changed along with change in a magnetic flux.
Implementation Method 2
A motor stator uses a magnetic field formed by current flowing in a three-phase coil and a rotor uses a permanent magnet formed by repeatedly arranging N and S poles. To allow a motor to continuously revolve, a continuous revolving magnetic field of the motor needs to be formed
Data Source
AI summary
A motor control method and system are provided. The method includes calculating a measured value of a revolution per minute (RPM) of a motor based on a signal measured by a hall sensor installed in the motor and applying a motor system load model to calculate a predicted value of the RPM of the motor. Further, noise of a hall sensor signal is detected using the measured value of the RPM of the motor and the predicted value of the RPM of the motor.