Torque Controller Variable Gain for Vibration Control and Gear Rattle Noise
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Solution Overview
Problem
Existing torque controllers in vehicles struggle to increase the frequency of sprung-portion-vibration control while effectively suppressing gear rattle noise, which occurs due to zero cross in output torque, leading to inhibited vibration control and increased noise levels.
Innovation Solution
A torque controller that determines the target motor torque by adding a variable gain to the sprung-portion-vibration-control torque, adjusting the gain based on the absolute value of the motor requested torque relative to the sprung-portion-vibration-control torque to prevent zero cross and enhance vibration control frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sprung-portion-vibration control is executed with high frequency, then vibration suppression performance is improved, but gear rattle noise increases due to zero cross in output torque
Solution Approach 1:
The patent applies dynamics by making the gain parameter variable rather than fixed. The gain is dynamically adjusted based on the absolute value of motor requested torque relative to sprung-portion-vibration-control torque. When |motor requested torque| is large, gain is set to 1 to maximize vibration control frequency. When |motor requested torque| is small, gain is reduced to prevent zero cross and gear rattle noise. This dynamic adjustment resolves the contradiction between vibration control frequency and noise suppression.
Solution Approach 2:
The patent changes the parameter (gain) based on operating conditions. By monitoring the ratio of motor requested torque to sprung-portion-vibration-control torque, the system adjusts the gain parameter to optimize performance. This parameter change strategy allows the system to achieve high vibration control frequency when conditions permit while preventing gear rattle noise when zero cross is likely to occur.
2Reliability
If the gain is increased to enhance vibration control, then vibration suppression effectiveness is improved, but zero cross occurs more frequently causing gear rattle noise
Solution Approach 1:
The gain is made dynamic rather than static. The system continuously monitors the torque conditions and adjusts the gain accordingly. When motor requested torque is large, high gain (value of 1) is applied for effective vibration control. When motor requested torque is small, gain is reduced to prevent zero cross. This dynamic behavior resolves the contradiction between control effectiveness and noise prevention.
Solution Approach 2:
The patent implements parameter changes by adjusting the gain value based on the absolute value of motor requested torque. This conditional parameter adjustment ensures that high gain is only applied when it won't cause zero cross, thereby maintaining vibration control effectiveness while preventing gear rattle noise.
3Object-generated harmful factors
If sprung-portion-vibration control is inhibited to suppress gear rattle noise, then noise levels are reduced, but vibration control frequency decreases
Solution Approach 1:
Instead of completely inhibiting vibration control to prevent noise, the patent applies partial action by using a reduced gain value. This allows some vibration control to continue even when motor requested torque is small, rather than completely disabling the control. This partial action approach suppresses gear rattle noise while maintaining some vibration control frequency.
Solution Approach 2:
The system dynamically adjusts the degree of vibration control application through variable gain. Rather than binary on/off control, the gain varies continuously based on operating conditions, allowing the system to optimize between noise suppression and vibration control frequency in real-time.
Data Source
AI summary
A drive system includes: a drive device including an electric motor; and a torque controller that controls operations of the electric motor to control torque output from the electric motor. The torque controller includes a target-motor-torque determiner that determines target motor torque based on a sum of motor requested torque and a value obtained by multiplying a gain by sprung-portion-vibration-control torque. The target motor torque is a target value of the torque output from the electric motor. The motor requested torque is determined based on vehicle requested torque requested for driving of the vehicle. The torque controller includes a gain determiner that determines the gain to a value that is less when an absolute value of the motor requested torque is small with respect to the sprung-portion-vibration-control torque than when the absolute value is large with respect to the sprung-portion-vibration-control torque.