The Improved Quadrant Switching MCP–PID Electric Machine Speed Smooth Transition Algorithm for Forklift Lifting Hydraulic Drive

Abstract

ABSTRACT As electric forklifts advance, the electric machine‐pump/motor control system is key to their lifting system due to high efficiency. Traditional systems struggle with quadrant switching in permanent magnet synchronous machines and pump coupling, causing flow fluctuations, pressure shocks and load‐affected actuator response. This is due to electric machine control issues like speed overshoot, torque shock and varying speed response with inertia and load. In this paper, an improved multiple capacity process—proportional integral derivative electric machine speed smoothing algorithm for stable transitions during quadrant switching is proposed. Also, a generalized fast sliding mode load observer with inertia identification is designed to compensate for torque shocks from unknown loads and enhance speed response robustness. The test bench is built. Experiments are carried out. The results show the proposed method reduces overshoot by 20% compared to the traditional multiple capacity process, achieves zero speed overshoot and improves response speed to 0.6 s (an 80% enhancement). It also minimizes load observer overshoot, reduces inertia identification error and significantly improves speed response robustness, promoting reliable operation of the electric forklift lifting system.