Electric Motor Torque Control for Industrial Vehicle Inertia
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In work vehicles equipped with electric-mechanical transmissions (EMT), the moment of inertia of rotating elements can cause torque imbalances, leading to uneven acceleration and deceleration, resulting in a feeling of unease for the operator due to the unpredictable vehicle behavior.
Innovation Solution
A control unit is implemented in the work vehicle to adjust the target torque of the electric motor based on the moment of inertia of both the motor and connected rotating elements, switching between different modes to optimize torque distribution and reduce the impact of inertia, thereby stabilizing vehicle behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the EMT uses an electric motor connected to planetary gear mechanism to enable continuous speed variation, then the rotation speed control flexibility is improved, but the moment of inertia of rotating elements causes torque imbalances leading to uneven acceleration and deceleration
Solution Approach 1:
The control unit dynamically adjusts the torque command to the electric motor based on real-time parameters including vehicle speed, acceleration demand, and calculated moment of inertia effects. By continuously monitoring and adjusting torque parameters, the system compensates for inertia-induced torque imbalances while maintaining flexible speed control through the planetary gear mechanism.
Solution Approach 2:
The system implements feedback control by calculating the moment of inertia of rotating elements and using this information to adjust the torque command. The control unit receives feedback on actual vehicle acceleration and compares it with commanded acceleration, then modifies the electric motor torque to compensate for inertia effects, ensuring stable vehicle behavior while maintaining speed control flexibility.
2Speed
If the electric motor rotates at higher speed compared to engine and other rotating elements, then the speed control range is improved, but the kinetic energy increases causing large impact on vehicle body behavior
Solution Approach 1:
The control unit calculates the moment of inertia of the electric motor rotor and connected rotating elements, then applies a counteracting torque to offset the inertial forces generated during acceleration and deceleration. This counter-torque compensates for the high-speed motor's kinetic energy impacts, reducing unwanted vehicle body movements while preserving the broad speed control range.
3Productivity
If the torque of electric motor is increased to overcome inertia during acceleration, then the acceleration performance is improved, but the torque imbalance causes uneven acceleration and deceleration
Solution Approach 1:
The system dynamically adjusts torque parameters based on real-time operating conditions including vehicle speed, acceleration demand, and calculated moment of inertia. By continuously optimizing the torque command parameters, the system achieves strong acceleration performance while maintaining uniform acceleration and deceleration characteristics through precise inertia compensation.
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 solution effectively reduces the impact of moment of inertia on vehicle behavior, enhancing operator comfort by ensuring consistent acceleration and deceleration, and improving control stability.
Implementation Method 1
an electric motor connected to a rotating element of the gear mechanism
Implementation Method 2
The gear mechanism has a planetary gear mechanism and transmits the rotation of the input shaft to the output shaft
Implementation Method 3
the torque caused by the moment of inertia of the rotating elements operates in the direction impeding the increase in the vehicle speed
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A power transmission device has an input shaft, an output shaft, a gear mechanism, and an electric motor. The gear mechanism has a planetary gear mechanism and transmits the rotation of the input shaft to the output shaft. The electric motor is connected to a rotating element of the planetary gear mechanism. The power transmission device is configured to change the rotation speed ratio of the output shaft with respect to the input shaft by changing the rotation speed of the electric motor. A control unit has a target torque determination unit and a target torque correcting unit. The target torque determination unit determines a target torque of the electric motor. The target torque correcting unit corrects the target torque according to a correction torque based on a moment of inertia of the electric motor.