Design and performance analysis of an electric threshing drum and its speed control system for combine harvester

Abstract

In response to the challenges encountered by traditional combine harvester threshing drums, such as the difficulty in maintaining speed stability amidst load fluctuations leading to increased entrainment loss, and the difficulty in adjusting speed across a wide range with varying crop types and properties, this study introduces an electric threshing drum (ETD) for combine harvesters. A motor control strategy leveraging a fractional-order non-singular sliding mode observer (FONSSMO) and model predictive control (MPC) is developed to achieve precise speed control of the ETD under load fluctuations and disturbances, with its parameters optimised using a genetic algorithm. Simulation results demonstrate that the ETD can achieve swift and accurate speed regulation. In the presence of torque interference and load transients, the proposed control method reduces the RMS value of the threshing drum's speed error by 73.96 % and the maximum speed error by 75.10 %, significantly enhancing the system's robustness. The bench test validated the efficacy and feasibility of the control strategy. Furthermore, field test results from rice harvesting showed that the combine harvester equipped with the ETD can mitigate entrainment loss rate fluctuations due to changes in vehicle speed and load compared to conventional models. At a vehicle speed of 2 m s⁻¹, it can reduce entrainment loss by ∼19–20 %, effectively enhancing harvesting efficiency.