Automatic restarting methods of electric forklifts in the free running state

Generally, electric forklifts are equipped with a controller which works as an inverter that runs on battery power. The controller rotates induction motors for driving and lifting of a forklift. It also manages faults of a forklift: when a truck is under abnormal conditions, the controller is designed to stop the truck by reason of safety. Although most of the faults can be under control, the controller is also designed to cut off the power supply to induction motors under certain uncontrollable situations, such as when motors are in the free running state, since the controller cannot stop the truck electrically. Until now, operators had to press the brake pedal and steer the wheel forcedly. They could also stop the truck with more polished methods such as automatic braking system with extra sensors or special mechanical actuators attached. However, there is a way to stop the trucks without any extra devices. We propose an electrical active alternative. In this study, we will discuss an application of the restarting method of induction motors, which is used in many industries, to forklifts. This paper describes the automatic restarting methods of electric forklifts in the free running state; thereby reducing the risk of accidents.