Brake Motor Position Error Compensation via Temperature Adaptation
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Solution Overview
Problem
The challenge is to accurately diagnose the state of a motor in a brake system without incorrectly determining it as a failure state due to position data errors caused by ambient temperature variations and sensor misalignment.
Innovation Solution
A brake system and method that compensate for position data errors, specifically electric angle errors, by determining the ambient temperature based on phase current or voltage measurements and using pre-stored reference values to adjust the electric angle, thereby minimizing false failure diagnoses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If motor state diagnosis is performed using motor position sensor output values, then motor state can be monitored, but position data errors due to temperature variations cause false failure diagnoses
Solution Approach 1:
The patent changes the reference parameter from a fixed room temperature calibration value to temperature-adaptive reference values. The controller stores multiple reference electric angle values corresponding to different temperature ranges and selects the appropriate reference based on the current temperature, thereby adapting the diagnosis criteria to actual operating conditions and eliminating false failures caused by temperature-induced position errors.
Solution Approach 2:
The patent performs preliminary temperature measurement and reference value selection before conducting the motor state diagnosis. By determining the current temperature and selecting the corresponding reference electric angle value in advance, the system ensures that the diagnosis is performed using the most appropriate reference data for the current operating conditions, improving diagnostic accuracy.
2Measurement precision
If calibration is performed at room temperature, then accurate reference values can be obtained, but these references become inaccurate under harsh environmental conditions
Solution Approach 1:
The patent changes the reference parameter from a single room temperature calibration value to multiple temperature-adaptive reference values. By storing different reference electric angle values for different temperature ranges and selecting the appropriate reference based on current temperature, the system maintains measurement precision across varying environmental conditions.
Solution Approach 2:
The patent makes the reference value system universal by creating a set of reference values that can serve multiple temperature conditions. Instead of a single reference valid only at room temperature, the system uses a multi-functional reference set that adapts to various operating temperatures, making the diagnosis system versatile across different environmental conditions.
3Device complexity
If motor position sensor alignment is assumed perfect, then diagnosis can be simplified, but sensor unit error and assembly tolerance cause diagnosis inaccuracies
Solution Approach 1:
The patent changes the reference parameter from a fixed room temperature calibration value to temperature-adaptive reference values. The controller stores multiple reference electric angle values corresponding to different temperature ranges and selects the appropriate reference based on the current temperature, thereby adapting the diagnosis criteria to actual operating conditions and eliminating false failures caused by temperature-induced position errors.
Data Source
AI summary
A brake system includes a motor which drives an electro mechanical brake, a motor position sensor which generates and outputs a rotor position signal of the motor, and a controller which is electrically connected to the motor and the motor position sensor, and the controller monitors a current or a voltage of at least one phase of three phases of the motor while controlling the motor to fixedly drive any one phase of three phases of the motor, determines an ambient temperature of the motor by monitoring a current or a voltage of at least one phase, and compensates for an electric angle of the motor obtained by an output signal of the motor position sensor based on the determined ambient temperature.