Air Compressor Motor Sensorless Control Failure Diagnosis

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Solution Overview

Problem

Existing methods for sensorless control of air compressor motors in fuel cell systems struggle to quickly diagnose failures in positional alignment control, leading to divergent speed applications and potential motor driving failures.

Innovation Solution

A method involving real-time estimation of motor speed, determining if a preset condition for abnormality diagnosis is met based on the speed slope, and performing a control operation to decrease electric current, allowing for the determination of sensorless control failure and subsequent corrective actions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If sensorless control is used to eliminate the Hall sensor, then the motor can operate at higher speeds without heat-related sensor limitations, but the system loses the ability to directly measure rotor position and speed, making failure diagnosis difficult

Engineering Contradiction:

Improvemotor speedVSAvoidcontrol failure diagnosis capability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The system implements feedback by monitoring the estimated speed from sensorless control and comparing it with the commanded speed. When the absolute difference exceeds a threshold, the system diagnoses sensorless control failure and switches to Hall sensor-based control, ensuring reliable operation across all speed ranges

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The controller acts as an intermediary that manages multiple control modes. It selectively switches between sensorless control (for normal operation) and Hall sensor-based control (for failure diagnosis or high-speed operation), maintaining system reliability without requiring permanent use of the Hall sensor

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If Hall sensor is used for positional control, then direct rotor position measurement is available for reliable control, but the sensor is susceptible to heat and cannot operate reliably at high motor speeds

Engineering Contradiction:

Improvepositional control accuracyVSAvoidmotor speed

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The system dynamically adapts its control strategy based on operating conditions. At low speeds, sensorless control provides sufficient accuracy without heat issues. At high speeds or when failure is detected, the system automatically switches to Hall sensor-based control, optimizing performance across the entire speed range

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The control system changes operational parameters by switching between two control modes. The selection criterion is based on speed thresholds and failure detection, allowing the system to use the appropriate control method (sensorless or Hall sensor-based) depending on the current operating conditions

Inventive Principle:

Principle #35Parameter changes

3Duration of action of stationary object

If sensorless control fails without detection, then the system continues operating with divergent speed estimation, but this leads to potential motor driving failure and loss of vehicle drivability

Engineering Contradiction:

Improvecontinuous operation timeVSAvoidmotor driving reliability

Core Design Contradiction:

Duration of action of stationary objectVSReliability

Solution Approach 1:

The system continuously monitors the estimated speed from sensorless control and compares it with the commanded speed. When the absolute difference exceeds a threshold, the system diagnoses sensorless control failure and switches to Hall sensor-based control, ensuring reliable operation across all speed ranges

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system prepares for potential sensorless control failure by having Hall sensor-based control as a backup ready. When failure is detected through speed comparison, the system immediately switches to the backup control method, preventing motor driving failure and maintaining vehicle drivability

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS12215683B2Method of diagnosing abnormality of sensorless control of motor for air compressor

Publication Date: 2025.02.04 HYUNDAI MOTOR CO LTD

AI summary

Proposed is a method of diagnosing abnormality of sensorless control of a motor for an air compressor, the method including estimating a speed of a motor in real time when a motor starts determining whether or not a preset condition for activating a function of diagnosing abnormality of sensorless control is satisfied, from a slope of the estimated speed of the motor performing control for decreasing an amount of electric current to be applied to the motor, in a case where the preset condition is satisfied computing an amount of decrease in the slope of the estimated speed of the motor while the amount of the electric current is decreased; and determining whether or not the sensorless control fails, by comparing the amount of the decrease in the slope of the speed of the motor with a preset value for confirming diagnosis of the abnormality of the sensorless control.