Filters for Electromagnetic Compatibility Applications

Filters for Electromagnetic Compatibility Applications
Mathias Magdowski
Chair for Electromagnetic Compatibility
Institute for Medical Engineering
Otto von Guericke University Magdeburg
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Mathias Magdowski (Chair for EMC) Filters for EMC Applications 1 / 53

On a scale of artificial intelligence, how are you doing today?
https://particify.esalsa.
de/p/04860461 Source: https://twitter.com/mhaseneyer/

Some words about myself
Personal background:
born in 1984
live in Magdeburg, Germany
married, two children

Some words about myself
Personal background:
born in 1984
live in Magdeburg, Germany
married, two children
Educational background:
2003 – 2008: studied “Electrical Engineering” at the Otto-von-Guericke-University in
Magdeburg
since 2008: Scientific co-worker at the Chair for EMC
2012: Ph. D. (Dr.-Ing.) with the dissertation “Comparison of the Coupling of
Deterministic and Stochastic Electromagnetic Field to Transmission Lines”
since 2015: teaching as flying faculty

Faculty for Electrical Engineering and Information Technology

Cathedral of Magdeburg seen from the river “Elbe”

Location of Magdeburg inside Germany
Magdeburg
Hannover Berlin
Dresden

Who was Otto von Guericke?

Same experiment – different force
Source: https://twitter.com/Isarmatrose/status/1465571898541187073

Organizational matters
Slides:
yes

Slides:
yes
Recording:
maybe

Slides:
yes
Recording:
maybe
Questions:
with pleasure

What is EMC?
Intermediate overview
1 What is EMC?
2 Examples
3 Reminder of Circuit Calculation
4 Filters

What is EMC?
What is electromagnetic compatibility?

What is EMC?
Survey: Have you heard of
EMC before?
https://particify.esalsa.de/p/04860461

What is EMC?
EMC before?
Electromagnetic compatibility . . .
. . . is the ability of electrical equipment and
systems to function acceptably in their
electromagnetic environment, by limiting the
unintentional generation, propagation and
reception of electromagnetic energy which
may cause unwanted effects such as
electromagnetic interference (EMI) or even
physical damage in operational equipment.

What is EMC?
EMC before?
Electromagnetic compatibility . . .
. . . is the ability of electrical equipment and
systems to function acceptably in their
electromagnetic environment, by limiting the
unintentional generation, propagation and
reception of electromagnetic energy which
may cause unwanted effects such as
electromagnetic interference (EMI) or even
physical damage in operational equipment.
Aspects:
Immunity
Emission

What is EMC?
Coupling model:
Source Coupling path Victim

What is EMC?
Coupling model:
Source Coupling path Victim
Example:

What is EMC?
Coupling paths
(a) conducted

What is EMC?
Coupling paths
(a) conducted (b) electric fields

What is EMC?
Coupling paths
(c) magnetic fields

What is EMC?
Coupling paths
(c) magnetic fields (d) wave fields

Examples
1 What is EMC?
2 Examples
4 Filters

Examples
Electric cars
Source: https://pixabay.com/photos/electric-car-car-electric-vehicle-1458836/

Examples
Schematic of the electric power flow in an electric car
Power
grid
Rectifier
Battery &
DC link
Inverter Motor

Examples
Rectifier
D1
D2
D3
D4
D5
D6
L1
L2
L3
UDC
0

Examples
Inverter
S1
S2
S3
S4
S5
S6
0
UDC
L1
L2
L3

Examples
Looking at the spectrum of signals
Trapezoidal pulse:
û
τ
tr
Time
Amplitude

Examples
Looking at the spectrum of signals
Trapezoidal pulse:
û
τ
tr
Time
Amplitude
Amplitude spectrum (envelope):
1
πτ
1
πtr
2ûτ
constant
−20 dB per decade
−40 dB per decade
Frequency (log.)
Spectral density in dB

Examples
Conflict between power electronics and EMC
Switch open Switching process Switch closed
Time
Amplitude
Energy loss in the switch
Current through the switch
Voltage across the switch
Power loss in the switch

Examples
Survey on other EMC examples

Reminder of Circuit Calculation
1 What is EMC?
2 Examples
4 Filters

What do you know about about current and voltage in circuits?

Kirchhoff’s voltage law (KVL):
N
X
i=1
Ui = 0 (1)
Ui: voltage drop at ith element (in V)

Kirchhoff’s voltage law (KVL):
N
X
i=1
Ui = 0 (1)
Ui: voltage drop at ith element (in V)
Kirchhoff’s current law (KCL):
N
X
i=1
Ii = 0 (2)
Ii: current flow at ith element (in A)

What else do you know about about current and voltage?

Ohm’s law:
U = R · I (3)
R: Resistance (in Ω)

Ohm’s law:
U = R · I (3)
Faraday’s & Lenz’s law:
U = L · dI
dt (4)
L: Inductance (in H)

Ohm’s law:
U = R · I (3)
Faraday’s & Lenz’s law:
U = L · dI
dt (4)
L: Inductance (in H)
Current and charge:
I = C · dU
dt (5)
C: Capacitance (in F)

What happens for harmonic (AC) signals in the frequency domain?

Resistor:
U = R · I (6)

Resistor:
U = R · I (6)
Inductor:
U = jωL · I (7)

Resistor:
U = R · I (6)
Inductor:
U = jωL · I (7)
Capacitor:
I = jωC · U (8)

Resistor:
U = R · I (6)
Inductor:
U = jωL · I (7)
Capacitor:
I = jωC · U (8)
ω = 2πf: angular frequency (in 1
s)

Resistors
Source: Gerald_G, https://openclipart.org/detail/8281/resistors

The colors, the colors!
Color Band 1 Band 2 Band 3 Multiplic. Tolerance
Black 0 0 0 100
(1Ω)
Brown 1 1 1 101
(10Ω) ± 1%
Red 2 2 2 102
(100Ω) ± 2%
Orange 3 3 3 103
(1kΩ)
Yellow 4 4 4 104
(10kΩ)
Green 5 5 5 105
(100kΩ) ± 0.5%
Blue 6 6 6 106
(1MΩ) ± 0.25%
Purple 7 7 7 107
(10MΩ) ± 0.1%
Gray 8 8 8 108
(100MΩ) ± 0.05%
White 9 9 9 109
(1GΩ)
Gold 10-1
(100mΩ) ± 5%
Silver 10-2
(10mΩ) ± 10%
5-Band-Resistor
4-Band-Resistor
234*100kΩ = 23.4MΩ @ 0.25%
23*10kΩ = 230kΩ @ 0.5%
Source: adlerweb, https://openclipart.org/detail/250258/resistor-color-code-table-german

This is why you need to learn it!
Source: https://twitter.com/pfmaggi/status/1576932773301932033

Measuring the frequency-dependent impedance of a resistor

Capacitors
Source: https://www.memedroid.com/memes/tag/capacitors

Important advice
Source: https://twitter.com/stargonewrong/status/1553205960658735104

Measuring the frequency-dependent impedance of a capacitor

Measuring the frequency-dependent impedance of an inductor

Filters
1 What is EMC?
2 Examples
4 Filters

Filters
What means filtering?

Filters
What means filtering?
Source: https://commons.wikimedia.org/w/index.php?curid=1691278

Filters
How must a low-pass filter look like?

Filters
How must a low-pass filter look like?
Requirements:
Pass band: at 50 Hz (almost) no attenuation
Stop band: at 10 kHz a reduction to 1⁄10

Filters
What is the transfer function of this filter?

Filters
Experiment: measuring the transfer function

Filters
High-pass filter
https://www.j3L7h2.de/wall/
index1.php?38N9w
Sketch the circuit schematic of a
first-order high-pass filter!

Filters
Answer: high-pass filter
index1.php?38N9w
Topologies of a first-order high-pass
filter:
U2(ω)
R
U1(ω) L
U2(ω)
C
U1(ω) R

Filters
High-pass filter
index1.php?38N9w
How does the amplitude response
function of a high-pass filter look like?
U2(ω)
C
U1(ω) R
ω (log.)
|U
2
(ω)|
|U
1
(ω)|
(log.)

Filters
Answer: high-pass filter
index1.php?38N9w
Amplitude response function of a
high-pass filter:
U2(ω)
C
U1(ω) R
ωc = 1
RC
1
ω (log.)
|U
2
(ω)|
|U
1
(ω)|
(log.)

Filters
Transfer function
index1.php?38N9w
Sketch the corresponding circuit
schematic for this transfer function!
U2(ω)
U1(ω)
=
R
R + jωL + 1
jωC

Filters
Answer: transfer function
index1.php?38N9w
Corresponding circuit schematic for
this transfer function:
U2(ω)
U1(ω)
=
R
R + jωL + 1
jωC
U1
L
C
U2
R

Filters
Filter
index1.php?38N9w
How does the amplitude response
function of this filter look like?
U1
L
C U2
R
ω (log.)
|U
2
(ω)|
|U
1
(ω)|
(log.)

Filters
Answer: filter
index1.php?38N9w
Amplitude response function of a
band-pass filter:
U1
L
C U2
R
ωc = 1
√
LC
1
ω (log.)
|U
2
(ω)|
|U
1
(ω)|
(log.)
Q = 1/2
Q = 1
Q = 2

Filters
Kahoot! quiz
https://create.kahoot.it/share/filters-for-emc-applications/55985b82-b058-4e3b-b59b-487a9eb02f54

Filters
Let’s ask ChatGPT!
Source: OpenAI, public domain, https://commons.wikimedia.org/w/index.php?curid=98220235

Filters
https://twitter.com/MarkusRidderbu8/status/
1523708966039351297
Thank you very much for
your attention!
Which questions do you
have?

Filters for Electromagnetic Compatibility Applications

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