Torque distribution improvement of electric wheel loader in shoveling process

A distributed electric wheel loader (DEWL) utilizes two motors to drive the front and rear axles simultaneously. However, the operation of traditional engine-driven wheel loaders (WLs) during work generates parasitic power, leading to significant energy losses and excessive tire wear. Additionally, during shoveling operations, the WL's center of gravity shifts significantly between the front and rear, reducing efficiency when identical drive motors are used. This study aims to analyze the dynamic characteristics of electric wheel loaders (EWLs) under shoveling conditions to optimize their efficiency. EWL models were established using MATLAB/Simulink, and theoretical analyses were conducted on key mechanical characteristics, including the driving theory of dual-motor drive EWLs, and the definition of parasitic power. A 5-ton rated load EWL was selected for investigation. Three groups of experiments— free shoveling, drive force, and phase-specific tests—were conducted to acquire performance data. Through analysis and formula derivation, several significant findings were revealed. The results show that parasitic power is generated when one drive motor operates at a higher speed than the other due to the center-of-gravity shift during shoveling. When the DEWL operates forward or backward at a set motor speed of 600 rpm in front-drive or rear-drive modes, the torque outputs of both motors are nearly identical, with torque fluctuations ranging from 0.16% to 1.28% and power fluctuations ranging from 0.02% to 1.29%. However, in dual-drive mode, the DEWL consumes more power compared to single-drive mode when operating in speed-target mode. Hydraulic pressure tests revealed a linear correlation between the vertical force on the front wheels and the hydraulic pressure in the tilt cylinder's base chamber. This relationship offers valuable insights for designing and controlling EWLs, serving as a crucial reference for enhancing performance and efficiency. Based on these findings, a new 5-ton rated load EWL was designed and produced. The design incorporated a switched reluctance motor (SRM) with a transmission ratio of 44.05 for the front drivetrain and a permanent magnet synchronous motor (PMSM) with a transmission ratio of 22.85 for the rear drivetrain. Performance was tested under torque distribution scenarios: even distribution between the front and rear wheels and distribution according to wheel load. Comparisons were made between the original EWL and the modified EWL with the SRM on the front axle: Walking tests revealed that at motor speeds of 200 rpm, 400 rpm, and 600 rpm, energy consumption in rear-drive mode was 68.56%, 71.88%, and 74.87%, respectively, compared to front-drive mode when two PMSMs were used. When an SRM with a transmission ratio of 44.05 was employed, energy consumption shifted to 73.90%, 70.35%, and 67.72%, respectively. These results demonstrate that rear motor-only driving under walking conditions yields significant energy savings. Shoveling tests further indicated that torque distribution according to wheel load reduces nearly 200% rear wheel slippage. Additionally, the SRM with a transmission ratio of 44.05 provided sufficient drive force while operating within a high-efficiency speed range, enhancing the EWL's performance during shoveling operations.

Text FK 2024 66 - Full Text.pdf Available under License Creative Commons Attribution Non-commercial No Derivatives. Download (17MB) Text FK 2024 66.pdf Restricted to Repository staff only Available under License Creative Commons Attribution Non-commercial No Derivatives. Download (18MB)

Actions (login required)

View Item