Analysis of a Hoist Motor Regenerated Energy System

High demand in industrial processes has resulted in technological advancements, particularly where materials need to be handled efficiently to realize profits. The overhead crane is a versatile machinery that diversely achieves movements of heavy objects that other material handling methods cannot manage in complex environments. The application of variable frequency drives (VFDs) on cranes achieves smooth and precise handling of heavy objects and consequently eliminates mechanical shock, thus prolonging machinery lifespan. To manoeuvre a load at the desired speed, the motors are often operated at a fraction of their rated speeds. At low speeds, the motor rotation opposes the generated torque. During this phase, the motor is electrically braking and behaving as a generator. The motor is feeding energy towards the VFD in what is known as regeneration. To mitigate the effects of the rising energy in the VFD, external resistors are connected to dissipate the energy as heat. The project aims to study VFD energy flow and design a system that recycles energy based on the findings. A VFD hoist has been constructed in laboratory conditions to investigate the compatibility of existing renewable energy storage technology to replace the resistors for crane-safe requirements.