Technologies

Engines & Power Electronics

Most Recent Inventions

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).
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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.
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Most Recent Patents

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.
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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.
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High Accuracy Angle Measuring Device for Industrial, Medical, Scientific or Recreational Use

A UW-Stout researcher has developed a high-accuracy angle measurement system that addresses the problems inherent to commercially available systems. In this novel device, a high accuracy rotary optical encoder is controlled by a microprocessor. The encoder consists of rotating optical disks and sensors that are precisely formed and placed to read angles with 0.001 arc second sensitivity (average) and better than ±0.1 arc second accuracy (single readings), which is comparable to the accuracy of the high-end commercial encoders currently on the market. This accuracy is maintained with strategies that combat the mechanical sources of error that are known disadvantages of other devices. The system can also be adjusted to compensate for any asymmetrical shifts that may occur. Mechanical sources of error and noise are further minimized by precision placement of disks and sensors, as well as low-friction reference points that keep components centered and level during rotation. In addition, multiple sensor heads eliminate major readout errors and remove the need for recalibration. All of these features and benefits are contained within a design that is both compact and portable. Beyond high accuracy and portability, the cost of this new angle measurement system is substantially lower than a high-end commercial system because it is easily constructed from readily available industrial grade components, bringing the production cost to roughly $2,000. Strikingly, this cost is comparable to the advertised price of other rotary position encoders that are less than one tenth as accurate. Its high accuracy, low cost, and portability make this new angle measurement system a strong option for use in virtually any of the current applications for absolute rotary encoders.
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