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Follow the patents: toward even more efficient wind power

Photo by Andrew Schultz on Unsplash
Photo by Andrew Schultz on Unsplash

Wind power has been around for well over a thousand years. The Persians first used wind power in the first millennium. Over the last few hundred years, the most notable change has been in the shape and design of the blades. Today, all major wind turbine manufacturers use a very similar design for their wind turbine blades, making one manufacturer’s wind turbine barely distinguishable from another’s. As with all forms of power generation, there is always room for improvement, but the improvements that will be coming to wind power will not be at the top of the unit where blades capture kinetic energy from the wind, but in the conversion of that kinetic energy into electric current.

In this installment of Follow the Patents, we look into the crystal ball that patents provide for us a revealing look into four new technologies that address the challenge of making wind power yet more efficient.

U.S. Patent No. 7,843,077 for a “Pulsed Energy Transfer” enables wind turbines to generate electrical power during periods of low air flow. Wind turbines are highly efficient when the wind is blowing, but when wind velocity drops, they quickly become very expensive! The invention covered by this patent enables operation of wind turbines during periods of low-flow velocity by temporarily disconnecting the load to allow the turbine rotating mass to accumulate velocity and energy, and then dump it into a load as an energy pulse.

From independent inventor Douglas Arduini, the invention covered by this patent allows low-energy input charging power to be accumulated and then summed or integrated over a longer period. It can then be stored or transferred to an output load such as high-energy output discharging power over a shorter period of time. The result is improved efficiency and extended operating range for wind turbines during low-flow velocities. This technology also has applications for tidal and wave-power turbines.

The technology covered by this patent could be incorporated into the next generation of wind turbines by the turbine OEMs, or it can be implemented by the wind farm owner or by the local power company to optimize electrical power from the wind turbines it operates.

Figure 1 from U.S. Patent No. 7,843,077 is a block diagram of a pulsed generator based on this patent. It includes a converter (104), clutch (106), clutch control (107) and speed sensor (108).

U.S. Patent No. 10,247,262 for a “Variable and Centrifugal Flywheel and Centrifugal Clutch” borrows the flywheel and clutch technology that is a key element in internal combustion engines, and also addresses the problem of decreased air flow that slows the wind turbine down to the point that it is not generating electrical power. The invention begins with a centrifugal-force-controlled clutch, an automatic mechanical clutch that is controlled by the RPM of the turbine. The pulsated input power automatically maintains the RPM operating range while increasing the stored energy, leading to improved efficiency during periods of low air flow.

The invention incorporates a centrifugal flywheel that automatically controls the variable mass radius that is displaced linearly with RPM for stored energy. The flywheel covered by the invention adjusts to variations in input and output of energy better than the conventional fixed flywheels found on rotating turbines and machines, enabling it to operate near the “sweet spot RPM” for optimal efficiency. This includes the ability to store pulsed or low-energy inputs and transfer or discharge the energy as needed for constant long periods or short pulse periods of average or peak power, RPM or torque.

Also from independent inventor Douglas Arduini, this technology incorporates an adjustable or variable flywheel that provides a wide range of RPM and variable mass radius displacement control for stored energy. It maintains a constant RPM, torque or G-force despite variations in input energy, stored energy, output load energy, and input/output pulsed energy, and does so far more effectively than conventional fixed flywheels. Like the Pulsed Energy Transfer patent from Mr. Arduini, this technology also has applications for tidal and wave-powered turbines, and the invention can be incorporated into the next generation of wind turbines by the turbine manufacturers, or be added to the power-generating configuration by the wind farm owner or local power company.



Figure 3 from U.S. Patent No. 10,247,262 is an illustration of an assembly that uses a Return Spring, two Flywheel Arms and a Flywheel Counterbalance Weight.

U.S. Patent No. 8,502,403 for a “Multiple Generator Wind Turbine and Method of Operation thereof” adds a controller to a wind turbine that adds more power generation at higher speeds and totally shuts down at the lowest speeds. Today’s wind turbines are designed to operate at a fixed speed – despite constantly changing wind speeds – by means of a gear box. These gear boxes are expensive, and when they fail they result in down time for the wind turbine until the gear box is replaced or repaired. Some wind turbines use braking systems to slow the unit down during periods of high winds, but braking systems – like gear boxes – are wear items that result in down time when they fail. Additionally, braking systems must expend energy in order for them to effectively slow down the turbines.

The invention covered by this patent was developed by the R&D team at New World
Generation Inc., and it creates a wind turbine drive system that manages the torque transmitted through the mechanism. The technology provides the wind turbine with a variable-speed rotor and a plurality of generators with a controller that activates and de-activates these generators in response to variations in wind speed and direction as determined by a monitoring system. The invention also controls the “pitch” and “yaw” of the wind turbine along with multiple generators that allow wide ranging power production using friction-coupled mechanical drive components that prohibit torque from reaching a prescribed level.

For those readers who do not fly and are not familiar with these aeronautical terms, “pitch” refers to the slightly up or slightly down horizontal angle at which the wind approaches the turbines, and “yaw” defines the angle at which the wind is approaching the turbines from the right or left. The more directly aimed the turbines are into the flow of the wind – high or low (“pitch”) and right or left (“yaw”) – the more efficient the wind turbine. 

This patent creates a wind turbine with a variable-speed rotor and multiple generators that are activated and de-activated as needed based on variations in wind speed and direction that is monitoring against prescribed parameters. The invention covered by this patent is fairly complex. This is a meaty patent. It has 38 Claims and is cited by 63 other patents. This technology could be adapted by the wind turbine OEMs or integrated by the wind turbine operator.

This figure from U.S. Patent No. 8,502,403 is a partial perspective view of part of a drive system for a wind turbine based on this patent. The illustration shows multiple generators (22), at least one for each wheel.

U.S. Patent No. 7,420,288 for a “Stall Controller and Triggering Condition Control Features for a Wind Turbine” addresses control features for a wind turbine over a range of wind speeds while also addressing the noise, cost and reliability issues associated with other control devices. This invention uses electronic controls to adjust the torque produced by the electrical output generation device within the wind turbine. During normal operation, torque is adjusted for optimum aerodynamic performance and maximum output of power. When wind speeds increase, the control circuit regulates torque to lower aerodynamic performance to maintain the desired power level output.

From inventor David Calley, this patent is assigned to Southwest Windpower, Inc., and it also addresses specific “triggering conditions” such as control circuit failure or loss of some or all electrical output generation in extreme winds. This is accomplished by using a separate controller to increase torque from the electrical output generation device via a shorting of the windings that causes retardation of blade rotation.

This is an especially complex and foundational invention! The patent includes a whopping 75 claims, and it is cited by 44 other patents! This patent’s technology – like others in this article – could be incorporated into a future generation of wind turbines by the manufacturer, or it could be implemented as add-on technology by the wind turbine operator or the local power company.

Figure 7 from U.S. Patent No. 7,420,288 presents a schematic of various components of a next-generation wind turbine that incorporates multiple aspects of the patent. It includes a Radio Frequency (700) communication link with the turbine control system that allows the user to access information regarding turbine operation and output in real time.

The future of wind power? It’s all about incremental increases in operating efficiency and electrical power generation from several competing technologies.