# The Current Development Status of Agricultural Machinery
## 2 Power System of Agricultural Machinery Chassis
### Hybrid Power System
Additionally, they proposed an adaptive equivalent fuel consumption minimization strategy integrated with real-time operation mode prediction to further improve system efficiency. [PERSON] et al. [78] designed a hydrogen fuel-cell-dominant hybrid power system supported by battery energy storage, aiming to mitigate both the environmental pollution caused by conventional diesel agricultural machinery and the limited operational duration of pure electric alternatives. The system incorporates a comprehensive energy management strategy (EMS) that integrates thermostat control, power tracking, and fuzzy logic control mechanisms. [PERSON] et al. [79] implemented a two-layer energy management strategy (EMS) for plug-in hybrid electric tractors to regulate power distribution among multiple energy sources. This strategy effectively reduces fuel consumption while simultaneously extending vehicle range. [PERSON] et al. [80] constructed a predictive vehicle model that integrates chassis longitudinal dynamics, rolling resistance modeling, drivetrain efficiency losses, and wheel speed-torque relationships. The proposed energy management strategy (EMS) is designed to optimize fuel consumption while maintaining the battery state-of-charge (SOC) within a desired range. [PERSON] et al. [81] classified the power system into two distinct components--power sources and energy storage units--and proposed a dual-source collaborative optimization-based EMS (DSC-EMS). This strategy improves fuel cell efficiency, reduces ammonia consumption, and extends battery service life. [PERSON] et al. [82] addressed the issue of insufficient battery discharge utilization in extended-range electric tractors by developing an EMS based on control parameter adjustment algorithms. The core innovation involves establishing a plowing-specific chassis dynamics energy consumption model, which segments the operational cycle into uniform acceleration, constant velocity, uniform deceleration, and turning phases. This model quantifies the energy required to overcome plowing resistance, rolling resistance, and gradient resistance, thereby significantly improving battery energy utilization efficiency and reducing overall fuel consumption. [PERSON] et al. [83] formulated an energy management strategy for charge-depleting charge-sustaining (CD-CS) extended-range electric tractors to ensure continuous operation and meet range requirements. By constructing tire-soil interaction models and coulter-soil engagement models, they quantified the influence of different soil types on rolling resistance and determined optimal soil-entry angles, leading to a notable extension of pure-electric driving duration. [PERSON] et al. [84] proposed an energy-efficienthydro-electric hybrid tracked chassis that integrates independent hydraulic and electric drive systems. Compared to traditional single-drive agricultural equipment, this configuration demonstrates advantages in terms of lower power consumption, faster response times, and extended operational endurance. To enhance energy utilization efficiency in extended-range electric tractors, [PERSON] et al. [85] established and experimentally validated a dual-motor independent drive energy management model. Their findings confirmed the theoretical soundness and practical feasibility of the proposed system. Hybrid agricultural machinery is increasingly integrated into modern farming practices, marking a transition of China's research from theoretical exploration to practical technological implementation. At the technical level, powertrain systems exhibit diversified development trajectories, while energy management strategies (EMSs) emphasize multi-objective collaborative optimization approaches. These include adaptive equivalent fuel consumption minimization strategies, fuzzy logic control algorithms, dual-source collaborative optimization frameworks, and hierarchical control architectures--each designed to balance fuel efficiency, operational range, battery durability, and emission constraints.