What separates the eVSP from the conventional VSP?

There are two central reasons:

1. We see that electrification is advancing strongly in certain types of ships. This trend is becoming prolific in many sectors, not only in marine applications.
2. Beyond political motivation, the cost factor is triggering this moment for change. Prices for high-performance batteries and power electronics components have fallen rapidly in recent years. Electrification has quite simply become economical.

Furthermore, we noticed that the conventional VSP has already been used for several years in ships where an electric motor is at the head of the drive system. It was therefore logical for us to offer an original electric drive concept for the shipping industry. The eVSP is a system that optimally combines all the advantages of electrification with the many outstanding features of the VSP.

The most obvious is the integration of the electric motor into the eVSP. Because the motor is no longer positioned outside the propeller, the drive system requires less installation space. In addition, the shaft train between the motor and propeller is also eliminated. This not only means less installation space, but ship designers can also dispense with a high-maintenance element that is absolutely essential in conventional propulsion systems. All these factors also make the entire drive system more compact. Depending on the size of the eVSP, this amounts to a weight saving of between 12 and 30 percent.

Furthermore, replacing the VSP with an eVSP can increase the efficiency of the propulsion system compared to a mechanical drive train. It is common, especially in larger installations, for the drive of the mechanical propeller to include two gear stages. This means that the speed, regardless of whether it is generated by a diesel engine or an external electric motor, is reduced in two stages. With the eVSP, we eliminate these.

In addition, with eVSP we use a permanent-magnet synchronous motor. Particularly in the partial power range, this motor is more efficient than the otherwise common asynchronous machines. The partial power range is the main focus for ships in everyday operation. It is true that maritime applications are designed for a target speed in their rated power. However, a ship rarely runs on nominal speed in real operation. Most of the time, an engine runs at speeds well below that.

As an example, consider a ferry that is designed for a target speed of X knots in certain extreme wind and weather conditions. Most of the time, however, the wind and weather are much kinder, and lower power is sufficient to maintain the schedule. That's why it's an advantage to have an motor that is highly efficient over a very wide speed window. And this is where the permanent-magnet synchronous motor has an advantage.

First of all, we had a tight timeline. While we were still in the development phase, we had the first customer order at the beginning of 2020. With a tight schedule we delivered, we delivered the first system to a shipyard in Spain. We welcomed the fact that we had already won a customer order at an early stage. This enabled us to develop directly in line with the market’s needs. Sometimes there is a danger of developing something on a greenfield basis and thinking up the most amazing things that a customer might need. In reality, it happens just as often that the customer wants or needs something else – especially since the customer, Norwegian shipping company Østensjø, does not serve just any niche but the growing market of wind farm supply vessels. So, we knew from the start that our development would meet the needs of an important market.

And finally, integrating such a large, permanently excited synchronous machine into our propeller presented a challenge for the team. We did have ideas about where to put the motor and how to cool it. But the prototypes and design studies showed us that the way it was initially thought out on a white sheet of paper didn't work in all places. In the end simulations and prototype building helped us verify and optimize our thinking on engine cooling.