Hall Sensor Failure Diagnosis for Brushless DC Motor Control
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Solution Overview
Problem
Existing methods for controlling brushless DC motors in electric oil pumps fail to accurately diagnose and respond to hall sensor failures, especially at low oil temperatures or RPMs, leading to motor instability and potential pump stoppage due to difficulty in determining which phase is out of order.
Innovation Solution
A method that continuously detects output signals from three phases of the hall sensor, diagnoses which phase is out of order by measuring signal differences, and outputs a virtual signal to the motor controller to prevent motor stoppage, ensuring continuous operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the motor is left in an inertial rotating state to determine hall sensor failure phase, then the failure phase can be diagnosed, but the motor may not smoothly allow inertial rotation due to pump resistance at low oil temperature or low RPM, causing stoppage
Solution Approach 1:
The control unit continuously monitors hall sensor output signals and detects failures before they cause motor stoppage. By performing preliminary detection and diagnosis of hall sensor failures, the system can prepare virtual signals in advance to maintain motor operation, preventing the contradiction between accurate failure diagnosis and continuous motor operation.
2Measurement precision
If the hall sensor output is monitored to detect failure, then the failure can be identified, but the motor rotation becomes unstable due to incorrect output signals
Solution Approach 1:
When a hall sensor failure is detected, the control unit generates virtual hall sensor output signals as intermediaries to replace the incorrect signals from the failed sensor. These virtual signals serve as a mediator between the failure detection and motor control, maintaining stable motor rotation by providing correct position information to the control algorithm despite the actual sensor failure.
Solution Approach 2:
The control unit creates copies of the normal hall sensor output signals by generating virtual signals that mimic the expected waveform patterns. These copied signals replace the abnormal signals from the failed hall sensor, allowing the motor control to continue with accurate position information without being affected by the sensor failure.
3Duration of action of stationary object
If a virtual waveform is output based on determined hall sensor failure, then continuous motor operation is achieved, but the control cannot be performed when it is difficult to determine which phase is out of order
Solution Approach 1:
The control unit continuously monitors the three-phase hall sensor output signals and compares them against expected patterns to detect failures. This feedback mechanism provides real-time information about sensor status, enabling the system to determine which phase has failed and generate appropriate virtual signals to maintain continuous motor operation.
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 diagnosis and prevention of motor stoppages by continuously monitoring and diagnosing hall sensor failures, ensuring the electric oil pump operates smoothly even at low temperatures or low RPMs, thereby maintaining vehicle drivability.
Implementation Method 1
The hall sensor is used to measure a rotating position and direction of the motor by sensing a hall effect. In detail, the hall sensor may detect a relative position of the rotor to the stator based on the magnetic field generated by the permanent magnet of the rotor.
Data Source
AI summary
A method for controlling a motor includes detecting output signals output from three phases of a hall sensor, determining a failure of the hall sensor depending on the output signals, diagnosing which of the three phases of the hall sensor is out of order based on the output signals if it is determined that the hall sensor detections deviate from a predicted order, and outputting a virtual signal for the phase which is determined as a failure among the three phases of the hall sensor to a motor controller.