Statistical analysis and filter design for conducted emission noise
Electromagnetic compatibility (EMC) is the ability of equipment and system to function as intended without degradation or malfunction in their intended operational electromagnetic environment. Further, the equipment or system should not adversely affect the operation of, or be adversely affect...
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Format: | Thesis |
Language: | English English English |
Published: |
2003
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Online Access: | http://eprints.uthm.edu.my/7681/1/24p%20MOHD%20SHAMIAN%20ZAINAL.pdf http://eprints.uthm.edu.my/7681/2/MOHD%20SHAMIAN%20ZAINAL%20COPYRIGHT%20DECLARATION.pdf http://eprints.uthm.edu.my/7681/3/MOHD%20SHAMIAN%20ZAINAL%20WATERMARK.pdf |
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Summary: | Electromagnetic compatibility (EMC) is the ability of equipment and system
to function as intended without degradation or malfunction in their intended
operational electromagnetic environment. Further, the equipment or system should
not adversely affect the operation of, or be adversely affected by any other
equipment. There are two categories of Electromagnetic Compatibility; (1)
Electromagnetic Susceptibility (EMS) (2) Electromagnetic Interference (EMI). EMS
and EMI can be further divided into two categories namely radiated and conducted.
Conducted emission is the unwanted currents that are produced by electronic and
electrical equipments emitted through the power lines. The main sources of
conducted emission are common mode current and differential mode current. These
currents will interfere with any equipments that are connected to the same power
lines. EMC standards pertaining to the conducted emission (such as EN55014) define
the limit lines that should not be exceeded or the product cannot be marketed. In
order to avoid non-compliance to the standards, most electronic/electrical
equipments have power line filter installed into them. However, these filters are not
effective enough because they were designed without considering the emission
currents characteristics. This project proposed a method to improve the design of a
power line filter by analyzing the characteristic of the emission current noise. The
results from the statistical measurements can be used to identify the range of
frequencies where most of the noises are located. Eighty four blenders were used as a
sample to identify the characteristic of the noise. It was found out that the conducted
emission exceed the limit line from 150kHz to 1MHz by 5dB and by lOdB at
frequencies from 1MHz to 30MHz. A butterworth filter with cut-off frequency of
70.56kHz and bandwidth from 0 to 120kHz was designed. The parameters of the
filter were based on the statistical data of the conducted emission. The test result
shows that the filter attenuate the noise about 42dB at frequency range of 150kHz to
10MHz and lOdB at frequency range from 10MHz to 30MHz. The low attenuation at
frequencies from 10MHz to 30MHz is due to the existence of capacitive and skin
effect. A better filter can be achieved if a higher quality component is used in the
fabrication. |
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