Engines & Power Electronics

Most Recent Inventions

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.

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.

Axial Flux-Switching Permanent Magnet Machine for High Speed Operation

UW–Madison researchers have developed a new axial 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 features innovative axial flux topologies with offset rotor and/or stator structures.

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.

Most Recent Patents

Motor for Electric Vehicles Solves Load/Loss Tradeoff

UW–Madison researchers have developed a new IPM design methodology that offers a solution to conventional performance tradeoffs.

The new design features variable flux linkage characteristics to reduce iron and copper loss under low and high load conditions, respectively. The design does not compromise torque capability and exploits flux leakage already present in every PM machine. In other words, compared to previous IPMs, this technology is able to convert a weakness into an advantage.

More specifically, the rotor geometry is designed such that flux leakage can be shifted to cross the air gap and become desirable flux linkage when stator current is applied. It can be increased or decreased as needed based on load conditions.

Vernier Motor Uses Less Rare Earth Materials

UW–Madison researchers have developed a new vernier machine that outperforms other PMVM designs.

The new motor features a central rotor with spokes of magnets. The magnets can be ferrite-based or made of a minimal amount of rare earth material. The rotor is sandwiched by a pair of notched stators, each separated from the rotor by an air gap and wound by stator windings that form magnetic poles. In contrast to traditional PM machines, the number of rotor magnetic pole pairs is much greater than the number of stator winding pole pairs. Still, the motor is able to achieve smooth torque given its design.

In effect, the new design produces a rotating magnetic field that travels much faster around the air gap than the rotor. Increased rate of change of flux linkage means more voltage is induced.

Lower Cost Motor for Electric Vehicles

Building on their work, the researchers have developed an improved FI-IPM machine and control method. The new design employs thin, low-coercivity magnets and allows re-magnetization using the stator winding and system power control. Magnetic force is reduced, and voltage is limited in high-rotation zones in which normal motors require flux weakening control. Re-magnetization is performed in zones that require low rotation and high torque, and the desired magnetic flux is obtained in the magnets.