Situation

One of the world’s largest wind turbine manufacturers aims to strengthen its position in the rapidly growing offshore wind market. Offshore applications impose higher demands on reliability, availability, and low-maintenance design than onshore turbines.
To meet these requirements, the manufacturer decides to transition from the traditional drivetrain technology with a gearbox to a direct-drive generator based on permanent magnets. In this configuration, the rotor is directly coupled to the generator without an intermediate gearbox. This results in:

• fewer mechanical components,
• higher reliability,
• lower maintenance costs,
• and higher energy efficiency.

Complication

Although the advantages of direct drive are clear, the technology introduces significant technical challenges:

• Permanent magnets with very high field strength generate strong attractive and repulsive forces.
• Uncontrolled assembly can lead to:
  o dangerous situations for technicians,
  o damage to magnets or steel structures,
  o inaccurate positioning with negative effects on generator performance.

In addition, offshore applications require:

• excellent corrosion resistance (salt, moisture, temperature fluctuations),
• consistent magnetic performance over several decades,
• and a cost-efficient production process at high volumes.

The manufacturer lacks sufficient internal experience in designing, producing, and assembling such powerful magnetic systems. At the same time, there is strong time pressure to be the first to bring this new direct-drive solution to market.

Question

The customer needs a partner who can assist him in working out the optimal way to mount the magnetic modules. There is also a need for a partner who can take care of the magnet production and who has experience in assembling these powerful magnets. All this under the given time pressure.

Solution

Co-development of magnet modules

Together with Bakker Magnetics, the customer starts an intensive co-development program, integrating electromagnetic, mechanical, and manufacturing considerations. Key design aspects include:

• optimization of the magnet configuration (pole layout, flux density, magnetic homogeneity),
• selection of magnets with high remanence and coercivity to prevent demagnetization,
• minimization of torque ripple and magnetic losses.

Safe and efficient assembly concept

Bakker Magnetics develops a controlled assembly process, in which:

• magnets are first positioned in modular segments,
• mechanical tools and spacers control the magnetic forces,
• the risk of sudden magnetic attraction is eliminated.

This improves both operator safety and positioning accuracy, which is crucial for generator efficiency.

Production and corrosion protection

For offshore use, the magnet modules are equipped with:

• high-quality anti-corrosion coatings,
• seals that protect against moisture and salt exposure,
• mechanical encapsulation to withstand vibration and fatigue.

In addition, a task-oriented production line is established in which:

• magnets, steel components, and mounting materials are optimally matched,
• quality control is integrated into every production step,
• repeatability and scalability are ensured.

Result

Thanks to the close collaboration between the wind turbine manufacturer and Bakker Magnetics, a cost-efficient, safe, and scalable production line for direct-drive magnet modules has been successfully implemented. The advantages for the final application are significant:

• no failure-sensitive gearbox → less maintenance and lower downtime,
• higher reliability, essential for offshore installations,
• no external excitation required for the magnetic field → higher efficiency,
• lower operational costs over the entire lifetime of the turbine.

By combining expertise in magnetism, production, and offshore engineering, a clear win-win situation was created, enabling the customer to successfully strengthen its market position in offshore wind energy.