There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Wide bandgap semiconductors show superior material properties enabling potential power device operation at higher temperatures, voltages, and switching speeds than current Si technology. As a result, a new generation of power devices is being developed for power converter applications in which traditional Si power devices show limited operation. The use of these new power semiconductor devices will allow both an important improvement in the performance of existing power converters and the development of new power converters, accounting for an increase in the efficiency of the electric energy transformations and a more rational use of the electric energy. At present, SiC and GaN are the more promising semiconductor materials for these new power devices as a consequence of their outstanding properties, commercial availability of starting material, and maturity of their technological processes. This paper presents a review of recent progresses in the development of SiC- and GaN-based power semiconductor devices together with an overall view of the state of the art of this new device generation.

A Survey of Wide Bandgap Power Semiconductor Devices

A control circuit of a surgical device is disclosed. The control circuit includes a first circuit portion coupled to at least one switch operable between an open state and a closed state. The first circuit portion communicates with a surgical generator over a conductor pair to receive a control signal to determine a state of the at least one switch.

Surgical generator for ultrasonic and electrosurgical devices

A surgical instrument. The surgical instrument may comprise a transducer and an end effector. The transducer may be configured to provide vibrations along a longitudinal axis at a predetermined frequency and may comprise a piezoelectric stack positioned along the longitudinal axis. The transducer also may comprise a first metallic end mass positioned along the longitudinal axis adjacent a first end of the piezoelectric stack and a second metallic end mass positioned along the longitudinal axis adjacent a second end of the piezoelectric stack. The length of the transducer may be greater than or equal to of one wavelength and less than ½ of one wavelength. The end effector may be coupled to the transducer and may extend along the longitudinal axis. The length of the transducer and the end effector may be a multiple of ½ of one wavelength.

Ultrasonic surgical instruments

A surgical instrument for supplying energy to tissue may comprise a handle, a trigger, an electrical input, and a shaft extending from the handle. The surgical instrument may comprise and end effector first and second tissue engaging surfaces that are slanted with respect to a transection plane. The end effector may, for example, have an electrode defining a V-shaped cross sectional profile. The end effector may comprise a plurality of raised surfaces that are received by a plurality of indentions when the end effector is in the closed position. The end effector may comprise a cutting member having a plurality of bands. A surgical instrument for supplying energy to tissue may comprise a handle, a trigger, an electrical input, and a shaft extending from the handle. The surgical instrument may comprise an end effector. The end effector may comprise a cammed compression surface. The end effector may comprise an electrode comprising a tapered tissue contacting surface. Some surgical instruments may comprise an overload member.

Surgical instrument with jaw member

There is a need for charging electric vehicles (EVs) wirelessly since it provides a more convenient, reliable, and safer charging option for EV customers. A wireless charging system using a double-sided LCC compensation topology is proven to be highly efficient; however, the large volume induced by the compensation coils is a drawback. In order to make the system more compact, this paper proposes a new method to integrate the compensated coil into the main coil structure. With the proposed method, not only is the system more compact, but also the extra coupling effects resulting from the integration are either eliminated or minimized to a negligible level. Three-dimensional finite-element analysis tool ANSYS MAXWELL is employed to optimize the integrated coils, and detailed design procedures on improving system efficiency are also given in this paper. The wireless charging system with the proposed integration method is able to transfer 3.0 kW with 95.5% efficiency (overall dc to dc) at an air gap of 150 mm.

A New Integration Method for an Electric Vehicle Wireless Charging System Using LCC Compensation Topology: Analysis and Design

A semiconductor device includes (a) a vertical field effect transistor, the vertical field effect transistor including a drain electrode formed on a first surface of a first conductivity type of a semiconductor, a pair of first trenches formed from a second surface of the semiconductor, control regions of a second conductivity type formed respectively along the first trenches, a source region of the first conductivity type formed along the second surface of the semiconductor between the first trenches, a source electrode joined to the source region, and a gate electrode adjacent to the control regions, (b) a pair of second trenches formed from the second surface of the semiconductor independently of the field effect transistor, (c) control regions of the second conductivity type formed along the second trenches, and (d) a diode having a junction formed on the second surface between the second trenches.

Semiconductor device including a vertical field effect transistor, having trenches, and a diode

A power electronic package includes: first and second high thermal conductivity insulating non-planar substrates; and multiple semiconductor chips and electronic components between the substrates. Each substrate includes multiple electrical insulator layers and patterned electrical conductor layers connecting to the electronic components, and further includes multiple raised regions or posts, which are bonded together so that the substrates are mechanically and electrically connected. The number, arrangement, and shape of the raised regions or posts are adjusted to have mechanical separation between the substrates. The electrical conductor layers are separated and isolated one another so that multiple electric circuits are provided on at least one of the substrates.

Power electronic package having two substrates with multiple semiconductor chips and electronic components

This paper presents a compact integrated power electronic module (IPEM) which seeks to overcome the volumetric power density limitations of conventional packaging technologies. A key innovation has been the development of a substrate sandwich structure which permits double side cooling of the embedded dies whilst controlling the mechanical stresses both within the module and at the heat exchanger interface. A 3-phase inverter module has been developed, integrating the sandwich structures with high efficiency impingement coolers, delink capacitance and gate drive units. Full details of the IPEM construction and electrical evaluation are given in the paper.

Compact Double-Side Liquid-Impingement-Cooled Integrated Power Electronic Module

A method for manufacturing a silicon carbide semiconductor device includes the steps of: forming a trench mask on an upper surface of a semiconductor substrate; forming the trench such that the trench having an aspect ratio equal to or larger than 2 and having a trench slanting angle equal to or larger than 80 degrees is formed; and removing a damage portion in such a manner that the damage portion disposed on an inner surface of the trench formed in the semiconductor substrate in the step of forming the trench is etched and removed in hydrogen atmosphere under decompression pressure at a temperature equal to or higher than 1600° C.

Rajesh Kumar Malhan

Papers

A New Integration Method for an Electric Vehicle Wireless Charging System Using LCC Compensation Topology: Analysis and Design

Semiconductor device including a vertical field effect transistor, having trenches, and a diode

Power electronic package having two substrates with multiple semiconductor chips and electronic components

Compact Double-Side Liquid-Impingement-Cooled Integrated Power Electronic Module

Method for manufacturing semiconductor device having trench in silicon carbide semiconductor substrate