Electric Motor Torque Control for EV Gear Rattle Suppression
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Solution Overview
Problem
Electric vehicles experience significant vibration and noise due to gear rattle when the output torque changes between positive and negative, affecting driving comfort and potentially causing damage to transmission mechanisms.
Innovation Solution
An electric-machinery control method that detects the relative deformation between driving and driven gears, determines a speed differential value, and controls the driving gear to perform a gear-approaching operation to reduce the speed difference upon re-contact, thereby minimizing vibration and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If regenerative braking is used to recover kinetic energy during deceleration, then energy efficiency is improved, but mechanical stress on the drive shaft increases due to sudden motor reversal
Solution Approach 1:
The control device performs preliminary action by gradually reducing the output torque of the motor before switching to regenerative braking mode. This gradual torque reduction allows the drive shaft to adapt to the changing load conditions, preventing sudden mechanical stress while still enabling energy recovery during deceleration.
2Loss of energy
If the motor is controlled to operate in generator mode during deceleration, then kinetic energy is recovered, but abnormal current may occur due to sudden load changes
Solution Approach 1:
The control device performs preliminary action by gradually reducing the output torque of the motor before switching to regenerative braking mode. This gradual torque reduction allows the drive shaft to adapt to the changing load conditions, preventing sudden mechanical stress while still enabling energy recovery during deceleration.
Solution Approach 2:
The control device monitors the operating state of the motor and drive shaft in real-time, and based on this feedback, dynamically adjusts the torque reduction rate and switching timing to optimal values. This feedback mechanism ensures smooth transition to generator mode and prevents abnormal current by continuously optimizing control parameters based on actual system conditions.
3Loss of energy
If direct switching to regenerative braking is performed, then energy recovery is maximized, but mechanical shock and noise increase
Solution Approach 1:
The control device performs preliminary action by gradually reducing the output torque of the motor before switching to regenerative braking mode. This gradual torque reduction allows the drive shaft to adapt to the changing load conditions, preventing sudden mechanical stress while still enabling energy recovery during deceleration.
Solution Approach 2:
The control device dynamically adjusts the torque reduction rate and switching timing based on real-time feedback from the motor and drive shaft operating conditions. This dynamic control ensures the smoothest possible transition to regenerative braking, minimizing mechanical shock and noise while maximizing energy recovery efficiency.
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
The method effectively reduces or eliminates vibration and noise by actively controlling the gear-approaching operation, improving driving comfort and performance without requiring hardware changes or additional sensors.
Implementation Method 1
a motor that generates an electromagnetic force to serve as a driving force for a drive shaft
Implementation Method 2
control the motor to operate in a generator mode during deceleration of the vehicle, thereby recovering kinetic energy
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The present application relates to the field of electric vehicles, and particularly to an electric vehicle and an electric-machinery control method therefor, an apparatus and a storage medium. The electric-machinery control method for the electric vehicle of the present application includes: detecting a relative deformation amount of a transmission system between a driving gear and a wheel end of an electric machinery; determining a first speed differential value between a first driving-gear rotational speed and a first wheel-end converted rotational speed when the relative deformation amount is a first threshold value, where the relative deformation amount being the first threshold value is used for indicating that the driving gear and a driven gear of the transmission system start to disengage, the first driving-gear rotational speed is a rotational speed of the driving gear at a disengagement moment that the driving gear and the driven gear disengage, and the first wheel-end converted rotational speed is a rotational speed obtained by performing a speed ratio conversion on a rotational speed of the wheel end of the electric vehicle at the disengagement moment; determining an output torque of the electric machinery according to the first speed differential value; controlling the driving gear to perform a gear-approaching operation relative to the driven gear according to the output torque, so as to reduce or even avoid problems of large vibration and noise of the electric machinery and the transmission system.