Motor Torque Control for Vibration Reduction
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Solution Overview
Problem
In environmentally-friendly vehicles, the motor control system generates unwanted torque vibrations due to inherent motor characteristics, leading to uneven torque output and vehicle vibrations, which existing control methods fail to address effectively.
Innovation Solution
A motor control system that utilizes a nonlinear model to optimize torque commands by extracting and attenuating unwanted torque outputs using a torque command optimizer, comprising an unwanted torque extractor and a torque attenuator, to maintain uniform torque output based on motor and controller states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional motor control system is used, then the motor can generate driving torque, but unwanted torque vibrations occur due to nonlinear motor characteristics
Solution Approach 1:
The system performs preliminary identification of unwanted torque characteristics through offline experiments before actual operation. The identified unwanted torque values are stored in a lookup table, allowing the controller to pre-compensate for vibrations by adding these values to the torque command in advance, rather than reacting to vibrations after they occur.
Solution Approach 2:
The system implements feedback by continuously monitoring the motor's operating conditions (rotational speed, torque command) and using this information to query the lookup table for appropriate unwanted torque compensation values. This closed-loop approach ensures that the vibration compensation adapts to changing operating conditions.
2Device complexity
If linear control methods are used, then the control system is simple, but they fail to account for nonlinear motor characteristics causing uneven torque output
Solution Approach 1:
The system changes the control parameter from a simple linear torque command to a compensated torque command that accounts for nonlinear motor characteristics. By incorporating unwanted torque identification values into the torque command, the system adapts to nonlinear behaviors without requiring a completely complex nonlinear control model, thus improving torque uniformity while maintaining reasonable system complexity.
3Power
If torque command is increased to improve driving force, then vehicle acceleration improves, but vibration characteristics worsen
Solution Approach 1:
The unwanted torque identification values act as an intermediary between the torque command and the actual motor output. By introducing this intermediate compensation term, the system can increase driving force through higher torque commands while the intermediary automatically compensates for the associated vibrations, allowing both improved acceleration and reduced vibration.
Data Source
AI summary
A method and system for controlling a vehicle motor are provided. The system includes an inverter that controls the motor to receive a torque command from an external system and output a torque based on the torque command. Additionally, a current command is generated based on the torque command and a operation condition of the motor. A voltage command is generated to be applied to the motor based on the current command and the operation condition of the motor. A pulse width modulation (PWM) command is generated based on the voltage command and the operation condition of the motor. The PWM command is converted to a voltage in a PWM form based on the motor operation condition and is applied to the motor. Then, an unwanted torque output of the motor generated based on a nonlinear characteristic of the motor is added and subtracted to and from the torque command.