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).

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.

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.

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

Flux-Switching Permanent Magnet Machine for High Speed Operation

UW–Madison researchers have developed a new FSPM machine that can be run at high speed with less fundamental frequency required, therefore overcoming one of the largest barriers to adoption. The new design relies on innovative radial flux topology that features an offset rotor structure, dual stators and concentrated coil windings.

New Rotor Magnet Configuration Delivers Greater Efficiency at a Lower Price

UW–Madison researchers have developed a streamlined sinusoidal rotor magnet design for interior permanent magnet machines.

By altering the classic rectangular block design for embedded magnet stacks in favor of a sinusoidal, axially varied orientation, researchers have increased the efficiency of rotors in IPMMs in a twofold fashion: Not only does this new design reduce the amount of magnet material necessary for rotor production, but it also provides an optimized distribution of flux that significantly reduces torque pulsation and spatial harmonics. The new design is easy to manufacture and is complementary to rotors already in existence.

Combined Capacitor/Inductor with Improved Performance

UW–Madison researchers have now mitigated the problem of parasitic inductance. Their new design features a loop-back terminal structure that minimizes the net magnetic field induced by the capacitor current. In other words, the capacitor leads are routed back up through the middle of the core to cancel the increased inductance seen at the capacitor terminals.