24 Jul 2024


‘Droop’ function improves winch control efficiency

Engineers working for Danfoss in Denmark have developed a function that allows a single frequency converter to control winches that are designed to be driven by two or more motors. They have also applied the development to marine steering and propulsion systems, and to container cranes.

Many large winches, such as those used on offshore vessels, need to be powered by two or more motors. If one fails, the others can handle the load. The motors are usually connected to two or more frequency converters to ensure that the winch runs smoothly.

The engineers from Danfoss’ marine division have come up with a new function for the company’s VLT drives, that ensures that the winch motors create an equal torque at any speed and any load. Only one frequency converter is thus needed to control the winch.

They have also applied this “droop” function to marine steering and propulsion systems, and have recently tested it successfully on cranes that are used to lift containers.

“Actually, this is a simple function, but it turns out that we can apply it in many other places than on ships,” says Danfoss business development manager, Helge Vandel Jensen. “The function was first made to solve a concrete problem, but later it was found that the function was also useful for controlling propulsion systems, for example. So, over the course of a year, it has turned into major improvement to our drive.”

“By working outside-the-box and creatively, we have created solutions in a very short time that are much better compared to what the competitors have been offering over the past few years,” adds Danfoss product manager, Jørn Schulz. “Danfoss’ solution is different to those of competitors’ because theirs connect the two frequency converters driving the motor on the winch.”