Technical Analysis of the All-Electric Drive Control System for Electric Skid-Steer Loaders——Innovation and Practice of Four-Wheel Independent Electric Drive Technology

System Composition and Architecture

The all-electric drive control system consists of LiFePO4 batteries, four-wheel drive motors, hydraulic cylinders, and distributed controllers (Figure 2), with the following core architecture:  

1. Power Source: High-capacity LiFePO4 batteries serve as the energy core, integrated into the rear battery box of the vehicle. Equipped with grille panels for optimized heat dissipation and protection, and an IP67 protection rating to withstand harsh conditions such as dust and water splashes.  

2. Driving System: Four-wheel systems are independently driven by permanent magnet synchronous motors, each connected to a planetary gear reducer for torque output. Precise control is achieved via the first to fourth controllers, also rated IP67 for durability in challenging environments.  

3. Working Mechanism: Two sets of hydraulic cylinders drive the lift arm and tilt bucket, independently regulated by the fifth and sixth controllers.  

4. Spatial Layout: Drive motors are embedded inside the vehicle chassis, reducers are externally mounted, and controllers are centrally installed, enabling a compact design.  

Figure 2

Core Advantages of Four-Wheel Independent Electric Drive

1. High Energy Efficiency, Breaking Traditional Limitations

Traditional hydraulic systems involve multi-stage energy conversion (engine → hydraulic pump → motor → wheel system), with single-stage efficiency at 60% and overall utilization below 40%. In contrast, the four-wheel independent electric drive simplifies the energy path to LiFePO4 battery → controller → drive motor → wheel system, eliminating hydraulic and chain-drive components. Tests show overall energy utilization exceeds 90%. Independent motor control further reduces idle losses, ideal for frequent start-stop operations.  

Figure 3

2. Independent Control Enhances Maneuverability and Adaptability

Four-motor independent drive grants the loader omnidirectional precision control:  

- Differential Steering: Achieves zero-radius turns by adjusting wheel speed differences, eliminating traditional axle structures and significantly reducing turning radius.  

- Torque Vectoring: Dynamically allocates torque to wheels on complex terrains (e.g., slippery or uneven surfaces), enhancing traction and mobility.  

- Redundancy Design: If one motor fails, the remaining three maintain basic mobility, improving system reliability.  

3. Lightweight Design and Low Maintenance Costs  

- Simplified Structure: Removal of hydraulic motors, valve groups, and complex oil circuits reduces vehicle weight by 15%-20% and minimizes leakage risks.  

- Ease of Maintenance: Planetary gear reducers feature modular designs with extended lifespans. Motors and controllers lack mechanical wear parts, requiring only periodic electrical inspections.  

4. Quiet Operation and Eco-Friendliness  

The all-electric system operates below 65 dB (traditional models exceed 85 dB) with zero emissions, making it ideal for confined spaces (e.g., tunnels, factories) and aligning with environmental regulations and occupational health standards.  

Key Technical Highlights

1. High-Efficiency Transmission via Planetary Gear Reducers

Compact planetary gear reducers offer high torque density, low backlash, and shock resistance, with a wide speed ratio range (5:1 to 100:1) adaptable to diverse working conditions. Their external design facilitates heat dissipation and maintenance, forming a highly integrated power unit with the drive motors.  

2. Distributed Intelligent Control Architecture  

Six controllers manage driving and working mechanisms, achieving:  

- Multi-Motor Coordination: CAN bus communication ensures synchronized wheel response and load balancing.  

- Automotive-Grade Chips and IGBT Power Modules: Utilize CAN 2.0 protocol for millisecond-level response, precisely controlling motor torque and hydraulic cylinder speed.  

3. Thermal Management and Safety Design

- Battery Box: Features insulation monitoring, precise state-of-charge calculation, and energy management, ensuring stable operation in -20°C to 50°C environments.  

- IP67 Controllers: Resistant to dust and water, with real-time monitoring of vehicle status (motors, controls, batteries), fault diagnosis, and protection protocols.  

- Electromagnetic Parking Brake: Automatically engages during power loss and allows manual release during system faults.  

Performance Comparison with Traditional Systems

Conclusion and Outlook

The four-wheel independent electric drive system addresses traditional skid-steer loaders' energy efficiency and environmental challenges through direct drive efficiency, intelligent control, and modular design. Future advancements in battery technology and autonomous driving algorithms will further propel electric construction machinery toward high precision, extended range, and full-scenario adaptability. This innovation not only revolutionizes skid-steer loaders but also provides a critical reference for the electrification of other specialized vehicles.