CM EMI Research Articles

The Effect of Gate Drive Resistance on the CM EMI Performance of the Balanced Inverter With Asymmetrical Parasitic Impedance Distribution

The Effect of Gate Drive Resistance on the CM EMI Performance of the Balanced Inverter With Asymmetrical Parasitic Impedance Distribution

An EMI Suppression Method in SiC Half-bridge Power Module Design

Abstract This paper presents a 1200V/24A SiC half-bridge power module with ultra-low parasitic capacitance and inductance for low CM EMI. This module is improved from a stacked substrate hybrid packaging structure by optimizing the copper pattern. The parasitic capacitance reduction methods and the trade-off optimization for geometrical parameters are given. The parasitic capacitance of the output node is reduced by 70% compared to the original module. The parasitic capacitance and inductance of the proposed module are 6.8pF and 5.5nH respectively. The EMI simulation shows the proposed module can reduce CM EMI by about 9 dB, while the EMI test result shows a maximum of 6 dB reduction.

Single Point Conducted EMI Sensor With Intelligent Inference for Detecting IT Appliances

Electrical grids need to embed smartness not just at the generation and distribution side but also at the consumption side. Specifically, in regard to office buildings, information technology (IT) loads such as desktops and printers, operating in non-working hours, can lead to significant energy wastage. Detailed understanding and quantification of this wastage can lead to motivational insights for reduction in this wastage. However, it is impractical to monitor such a large number of loads individually. In this paper, we propose a single point smart sensor to detect and track the operation of these IT appliances. Existing methods, based on state-of-the art sensors, have been ineffective at detecting IT loads that have time-varying power consumption patterns. Our proposed sensor detects IT loads using their common mode electromagnetic emissions (CM EMI) injected on the grid. The sensor is low cost, portable, and built using commercial off-the-shelf components. We use a nearest neighbor-based classification algorithm on the statistical features extracted from histograms of the measured CM EMI. Experimental evaluations carried out with multiple instances of commonly found IT appliances display up to 87% detection accuracy, thus validating the real world applicability of our proposed system.

Mitigation Strategy for AC Side to Suppress CM Current Flowing on DC Cables of the Motor Drive System

The electromagnetic interference of the motor drive system has a great influence on the performance. For the motor drive systems, the interference of CM current is important cause of conducted emission. AC side of motor drive system is high voltage and load is large inductive motor, so the AC side has a big impact on the DC side in the process of rapid on-off devices. The CM EMI current paths at frequency 30MHz are analyzed based on the distribution parameters of elements in current flowing circuit. The change of the CM EMI current will be analyzed through circuit and equation of the CM EMI current when the AC cable is added ferrite chokes or ferrite. The DC conducted emission electromagnetic interference suppression effect is obvious to add ferrite chokes or ferrite the AC cable in high frequency in the experiment, which is consistent with theoretical analysis. The results show that adding ferrite is more effective measure than adding ferrite choke to suppress the DC side conduction emission electromagnetic interference both in decreasing amplitude and larger frequency band.