An ESD Immunity Test for Battery-Operated Control Circuit Board in Myoelectric Artificial Hand System

Cheng JI  Daisuke ANZAI  Jianqing WANG  Ikuko MORI  Osamu FUJIWARA  

Publication
IEICE TRANSACTIONS on Communications   Vol.E98-B   No.12   pp.2477-2484
Publication Date: 2015/12/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E98.B.2477
Type of Manuscript: PAPER
Category: Electromagnetic Compatibility(EMC)
Keyword: 
ESD,  immunity test,  control board,  PWM signal,  photo-coupler,  

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Summary: 
We conduct, in accordance with IEC 61000-4-2, an electrostatic discharge (ESD) test for a small size battery-operated control circuit board in a myoelectric artificial hand system to investigate the influence of the induced noises by indirect ESDs from an ESD generator to a horizontal coupling plane (HCP) and a vertical coupling plane (VCP). A photo-coupler is set between the small size control board and a motor control circuit to suppress noise in the pulse width modulation (PWM) signals. Two types of ESD noise are observed at the output pins of PWM signals. One type is the ESD noise itself (called Type A) and the other one is the ESD noise superimposed over the PWM pulses (Type B). No matter which polarity the charge voltages of the ESD generator have, both types can be observed and the Type A is dominant in the output pulses. Moreover, the ESD interference in the HCP case is found to be stronger than that in the VCP case usually. In the PWM signals observed at the photo-coupler output, on the other hand, Type A noises tend to increase for positive polarity and decrease for negative polarity, while Type B noises tend to increase at -8kV test level in the HCP case. These results suggest that the photo-coupler does not work well for ESD noise suppression. One of the reasons has been demonstrated to be due to the driving capability of the photo-coupler, and other one is due to the presence of a parasitic capacitance between the input and output of the photo-coupler. The parasitic capacitance can yield a capacitive coupling so that high-frequency ESD noises pass through the photo-coupler.