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V3.5 Vertical Axis Wind Turbine System

The V3.5 VAWT has three major components, a turbine, a generator and an inverter.


Cleanfield's turbine is a simplistic design, having few moving parts, while the stationary centre structure can accommodate grounding for lightning protection.

The turbine was designed with a high aspect ratio in order to accommodate low nominal RPM of the turbine. As a result, a low blade speed ratio (ratio of blade speed to wind speed) minimises audible noise.

The blades are connected to the shaft by way of a pair of struts with an aerodynamic profile that has very low power losses, contributing to a better power coefficient of the turbine.

The turbine is equipped with a custom developed sensor/communication interface board which communicates with the inverter for data collection, supervision and protection of the turbine resulting in extended life expectancy and lowering of maintenance costs. The sensor board monitors turbine vibration for:

  • Resonant frequency skipping or to shutdown the turbine if excessive vibration is detected;
  • Generator temperature to reduce the output power of the turbine and eventually shut it down if thermal operating limits are approaching;
  • Ambient temperature to prevent the turbine start if outside temperature drops below -40°C and prevent the bearing from damage;
  • Electromechanical brake status to ensure controlled stoppage of the turbine and to control turbine speed to ensure that turbine is operated within safety limits and maximises efficiency.



The generator is a direct drive, low speed, permanent magnet generator (PMG) with an external rotor. Designed and built to match the turbine parameters it is an integral part of the system structure.

The Fail-safe Electro-mechanical brake with status feedback is included in the generator and will engage in case of power loss. Shutting down the power will stop the turbine from spinning and also allows service and maintenance work to proceed safely.


Inverter Electronics

The inverter has been designed with a custom algorithm for permanent magnet generator control. The flux vector control software provides an extremely sophisticated means of monitoring voltage, frequency, and current without costly and unreliable external sensors which is capable of profiling and predicting patterns and conditions.

The V3.5 RPM is custom controlled by regulating current to and from the generator. The control algorithm allows variable speed operation and the generator delivers the optimum power by following the power curve of the turbine while staying within safety limits. As a result, even in high wind or gusty conditions, the turbine RPM will not exceed 160 RPM. This control algorithm is fundamentally different than virtually all other small wind turbines available today, and is of significant advantage, providing improved performance and margins of safety.

Offsite monitoring by Cleanfield is available via Ethernet internet connection for a preventative maintenance program. Options are available to modify the interface to directly interface to a Building Management Systems (BMS).


Turbine Development & Validation

Cleanfield’s V3.5 VAWT has gone through extensive product engineering, testing (lab and field) and validation.

The following has been performed during product development and validation:

  • Wind tunnel testing to validate product performance. Extensive testing has been performed by McMaster University at the University of Waterloo's wind tunnel, University of Western Ontario's Wind Tunnel Laboratory and at the National Research Council wind tunnel in Ottawa;
  • Finite Element Analysis (FEA) of mechanical elements for static and fatigue analysis;
  • Structural cyclic fatigue testing of turbine shaft;
  • Structural testing of blades;
  • Inverter & generator tested and certified to CSA 22.2 No. 107.1-01


Turbine Mounting

The V3.5 can be either directly roof mounted or ground mounted. The Cleanfield V3.5 has been designed to mount directly onto existing and new-built commercial rooftop structures allowing for renewable energy generation in unused rooftop space, and for architectural enhancements to new and existing structures.

Cleanfield has pre-engineered rooftop mounts available for flat roofs and ground mount monopoles. All installations will require a structural engineering analysis.


Cleanfield V3.5 strengths

  • Designed for urban and suburban settings with variable speed operation;
  • Can be roof or ground mounted and does not need to be raised high above the rooftop to operate
  • Can provide an excellent wind energy solution where there are height restrictions set by local regulations in urban environments;
  • The generator and inverter has been designed as an integrated system resulting in optimized system performance;
  • An elegant design which is both simple and robust resulting in long life expectancy and minimal maintenance;
  • Low nominal RPM resulting in lower blade speed ratio and negligible audible noise;
  • Unique sensor board has been integrated into the turbine for data collection and supervision to monitor and protect the turbine;
  • It has an advanced emergency braking mechanism to manage turbine speed and lock down the turbine when wind speeds are excessive;
  • Turbine blades are made from gel coated reinforced fibreglass to help deal with icy conditions in the winter; and,
  • It has an offsite monitoring option by Cleanfield via a web enabled connection for preventative maintenance.


Feed in tariffs

This installation is not yet eligible for feed in tariffs in the UK but Cleanfield Energy is investigating becoming MCS certified.



Cleanfield's turbine has been designed for simplicity by having fewer moving parts and providing increased reliability while the stationary center structure can accommodate grounding for lightning protection.

V3.5 Vertical Axis Wind Turbine System

The turbine was designed with a high aspect ratio in order to accommodate low nominal RPM of the turbine. As a result, a low blade speed ratio (ratio of blade speed to wind speed) minimizes audible noise.

Wind tunnel testing at National Research Council, Ottawa

Contrary to the traditional horizontal axis wind turbines (HAWT), a vertical axis wind turbine (VAWT) rotates about the shafts vertical axis. A number of critical advantages are generated for this configuration in the urban environment. VAWTs can capture energy from the wind independent of the direction, not requiring any yaw mechanism. This is significant within the urban area since the wind is characteristically veering in direction. VAWTs also typically operate at lower rotational speeds, reducing / eliminating the turbine vibrations and generated noise.