Waleed M. Said

Current feedback based hybrid common-mode EMI filter for grid-tied inverter application

In this paper, a current feedback based hybrid common-mode EMI filter is presented for grid-tied inverter application, which employs passive filter with parallel damping branch. A current transformer is used to sense the target common-mode (CM) current, and the active circuit injects cancelation CM current via coupling capacitor. In particular, the proposed hybrid EMI filter with 2nd order high pass filter characteristic equivalently enhances the filter capacitance at high frequency range. Standalone and offline experimental results based on grid tied three-phase inverter system show that the proposed hybrid filter can improve the EMI attenuation by 10~20 dB beyond 150 kHz.

A Flight to Quality

Early Airplanes had very few loads that required electrical power. Batteries supplied a few amps for radio communications and a couple of cockpit lights. Later, alternators were employed on piston engine airplanes to generate more electrical power. As aircraft evolved, increasing amounts of electrical power were required, and power quality standards were introduced to govern the distributed airplane voltage and frequency. Those standards specified either a 28-V dc system or a three-phase system with a regulated voltage at a constant frequency.

Common mode choke optimization for three-phase motor drive systems

LC filters are commonly used in switch mode power supplies to suppress electromagnetic interference (EMI) noise. They are also a driving force for the weight of the system. Optimization of the passive filters has been studied in previous work, however, separately designing the converter and filter does not guarantee an optimal system design. This paper proposes an optimization process with consideration of both converter switching frequency and the corresponding impacts on the filter. Two case studies with different design considerations are presented to illustrate benefit of the proposed method in reducing the CM choke weight.