A New Filter Concept for High Pulse-Frequency 3-Phase AFE Motor Drives

The size of back-to-back converters with active front end is significantly determined by the size of the passive filter components. This paper presents a new complete EMC filter concept for this type of converter system that is effective on the input and the output. This involves filtering the main common mode interferences from the grid and motor sides with a single CM choke. Since only the difference of the generated common mode voltage-time areas of both converters is absorbed by this component, the size of the required filter can be greatly reduced compared to conventional filter concepts. The concept is validated on a grid feeding inverter that can be connected to the public distribution network with an output power of 63 kW. The size reduction is demonstrated by means of a design example on a system with the same power and electrical requirements. It is elaborated why, applying the new filter concept, the impedance of the DC link potentials to ground and other electrical potentials should be as high as possible and therefore associated parasitic capacitances should be minimized. From this requirement, rules for the design of the power modules of PFC and motor converters for the application of this filter concept are derived.

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Femtosecond-Laser Assisted Surgery of the Eye: Overview and Impact of the Low-Energy Concept

Micromachines ◽

10.3390/mi12020122 ◽

2021 ◽

Vol 12 (2) ◽

pp. 122

Author(s):

Catharina Latz ◽

Thomas Asshauer ◽

Christian Rathjen ◽

Alireza Mirshahi

Keyword(s):

Surgical Techniques ◽

Numerical Aperture ◽

Optical Breakdown ◽

Pulse Frequency ◽

Low Energy ◽

Human Cornea ◽

Energy Concept ◽

High Pulse Frequency ◽

Fs Laser ◽

High Pulse

This article provides an overview of both established and innovative applications of femtosecond (fs)-laser-assisted surgical techniques in ophthalmology. Fs-laser technology is unique because it allows cutting tissue at very high precision inside the eye. Fs lasers are mainly used for surgery of the human cornea and lens. New areas of application in ophthalmology are on the horizon. The latest improvement is the high pulse frequency, low-energy concept; by enlarging the numerical aperture of the focusing optics, the pulse energy threshold for optical breakdown decreases, and cutting with practically no side effects is enabled.

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Opposite Triangle Carrier with SVPWM for Common-Mode Voltage Reduction in Dual Three Phase Motor Drives

Energies ◽

10.3390/en14020282 ◽

2021 ◽

Vol 14 (2) ◽

pp. 282

Author(s):

Seon-Ik Hwang ◽

Jang-Mok Kim

Keyword(s):

Electromagnetic Interference ◽

Pulse Width Modulation ◽

Motor Drives ◽

Common Mode ◽

Pwm Inverter ◽

Common Mode Voltage ◽

Voltage Vector ◽

Three Phase ◽

The Common ◽

Zero Voltage

The common-mode voltage (CMV) generated by the switching operation of the pulse width modulation (PWM) inverter leads to bearing failure and electromagnetic interference (EMI) noises. To reduce the CMV, it is necessary to reduce the magnitude of dv/dt and change the frequency of the CMV. In this paper, the range of the CMV is reduced by using opposite triangle carrier for ABC and XYZ winding group, and the change in frequency in the CMV is reduced by equalizing the dwell time of the zero voltage vector on ABC and XYZ winding group of dual three phase motor.

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