Engines & Power Electronics

Most Recent Inventions

Integrated Vertical Axis Wind Turbine System Generates More Power from Less Wind with Smaller Turbines

An assistant professor of engineering technology at the University of Wisconsin-Green Bay has developed an innovation that improves the power generation efficiency of vertical axis wind turbine systems and reduces installation and maintenance costs. Conventional wind generation systems are currently limited by a configuration requiring one turbine to one power generator and drive train. The novel technology presented here removes this limitation by combining multiple vertical axis turbines with a single generator and drive train. This approach allows a reduction in size, weight and inertia of each turbine and a reduction in electrical and mechanical infrastructure. The result is a system that operates in less wind and generates more power per multi-turbine tower. In addition to increased capacity for electricity generation, other benefits related to this integrated turbine technology include ground level installation and maintenance of fewer generators and electrical components, options to reduce noise, and lower transportation barriers and costs.

Wound Field Synchronous Machines with Enhanced Saliency, Performance

UW–Madison researchers have designed a modified rotor structure for salient pole WFSMs that enhances saliency and leads to better performance (peak motoring power/torque capability) using the same amount of input current.

Compared to conventional designs, the new rotor structure features a flux barrier gap made of a low cost polymer that enlarges the reactance Xd - Xq, differential between rotor axes. Based on the particular end use, three different barrier designs could be employed (single barrier, multilayer barrier or axial laminated).

Lighter, Cheaper Multilevel Converter for Adjustable Speed Drives

UW–Madison researchers have developed a new multilevel converter design that does not require any extra capacitors, diodes or isolated voltage sources. This reduces costs, size and insulation requirements compared to conventional multilevel converters.

The new design is based on two multiphase inverters electrically coupled in series. The key feature is that they share the same input source (e.g., a single rectifier, DC grid or batteries). Other designs require separate isolated voltage sources. In this design, the output AC terminals of the inverters power different groups of machine windings, and the total output voltage is combined inside the machine without additional components.

Most Recent Patents

Vernier Permanent Magnet Machines with High Torque Density

UW–Madison researchers have developed a VPM rotor geometry that improves torque density and power factor by routing the stator flux in a way that boosts it. The new, single barrier design comprises an iron section with an air barrier near the rotor core to guide the stator magnet flux in a desirable path. This was created for the spoke-type configuration topology, where the magnets are aligned similar to the spokes of a bicycle wheel in the rotor. This design solution boosts the flux without compromising performance or cost.

Induction-Type Electrostatic Machine Improves Torque Profile, Design Flexibility

UW–Madison researchers have developed a versatile new design for large-scale electrostatic machines. The new design simplifies manufacturing by eliminating plates in favor of interdigitated pegs immersed in dielectric fluid. Concentric conducting ‘sleeves’ fit around/in between the rows of pegs and are used to shape the electrostatic field, reduce drag and improve torque characteristics and mechanical strength. Unlike conventional designs, torque is produced from electrostatic induction.

Converter Control with Reduced Link Capacitor

Building on their work, the researchers have now developed an improved modulation method that allows for the use of conventional switches. This new method tightly integrates the control of the source and loads, which is not traditionally done with current methods.

Reducing the energy at the DC bus led the inventors to modify how the source and load are controlled. Their method determines the switching intervals of the various solid state switching devices of the power conversion system in an integrated fashion and places them within each switching period in a particular sequence. This is determined by the desired voltage and current waveforms such that the stiffness of the DC link can be maintained without large amounts of energy storage, or additional voltage penalty compared to conventional approaches. New parameters for the source and load integration are factored into the controller algorithms.