HMK helps make Vertical Axis Wind Turbine a reality

A new micro-generating wind turbine for small businesses, farms and local communities

UK company 4Navitas Green Energy Solutions Ltd has successfully developed a vertical axis wind turbine (VAWT) which is set to revolutionise the worldwide onshore wind turbine market, currently dominated by horizontal axis wind turbines (HAWT).

The focus of the design concept was to avoid fatigue, an ongoing issue in HAWTs with wind coming from all directions, creating bearing and gearbox stress due to yaw/pitch requirements, ultimately leading to failure or the need for extensive maintenance prior to the 20-year recommended lifespan.

With the VAWT, there is no need for a blade pitch control system, and with power, electronics, motor and gearbox at ground level for easy maintenance, wear is considerably reduced and performance improved well beyond the 20-year predicted lifespan.

Fully integrated Siemens drive system

4Navitas worked with HMK & Siemens over a period of 18 months to refine the design and engineering of the wind turbine, and from this long-term collaboration a robust and efficient turbine with excellent power output has been developed. Drive, motor, coupling and gearbox use the Siemens integrated drive system (IDS) for best performance and extended life. Output is now rated at up to 75kW with plans for a 1-megawatt version already in the pipeline.

The 4Navitas VAWT houses a Siemens FZG helical bevel gear unit at its base, and the IE3 rated motor is close coupled with the gearbox. The shaft is supported by bearings down the mast so gearbox load and fatigue transfer is significantly reduced.

The power from the wind is controlled by a Siemens S7-1200 PLC and a Siemens Sinamics S120 system. The S120 harnesses the wind power, even in turbulent conditions, and by using Active Front End (AFE) technology connected and synchronised to the supply, transmits power back to the 415V 3-phase grid.

HMK commented:

“By providing 4Navitas with engineering and technological support – including power curve support from our Siemens colleagues in Germany – we were able to develop and refine the function blocks, drive technology and software. What we were also able to bring was added value and partnership to meet the challenges together and produce the best solution”.

Near-silent running

Another significant advantage is that resonance and noise is reduced to just 40dB – the equivalent of a quiet library. Meaning the 4Navitas turbine can be situated in populated areas, near schools, hospitals and within communities. With a height of just 37 metres, it takes up a much smaller footprint with no need for a large concrete base.

The 4N-55 VAWTs are now moving into serial production, after receiving considerable interest worldwide, and after undergoing extensive and successful testing.

Significant advantages

As Dominic M’Benga confirmed, “We’ve over-engineered it to last 25 years and in fact the wings and spreaders have reserve factors as high as 64, showing that the mill will survive way beyond its operational life. By engaging with Siemens, we have been able to bring it to market much sooner and to feel confident in our UK designed and built product with the additional benefit of Siemens’ worldwide local support. The enquiries we’ve had are testament to this successful partnership”.

4Navitas is already working on developing a 1-megawatt VAWT turbine – again with Siemens and HMK – and aiming to achieve IEC 61400 accreditation in the near future. The company is also considering international licences for its worldwide manufacture.


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