01. ELECTROMAGNETIC COMPATIBILITY (EMC) Introduction EMC
Electromagnetic Compatibility EMI Electromagnetic Interference EMS
Electromagnetic Susceptibility Maximum Emission level Minimum
Immunity level Device Immunity level Device emission level
COMPATIBILITY MARGIN ENVIRONMENT CLASS Frequency spectrum Amplitude
value
Slide 6
01. ELECTROMAGNETIC COMPATIBILITY (EMC) Introduction EMC
Electromagnetic Compatibility Low frequency F Z> 150 kHz THD
Flicker EMI Electromagnetic Interference EMS Electromagnetic
Susceptibility Medium Frequency 150 kHz< f < 30MHz Conduced
High Frequency f < 30MHz Radiated Radio Frequency Conduced
Radiated Surges Electrical fast transients Electrostatic discharges
THD Voltage dips and interruptions IEC61800-3 EMC 2004/108/CE IEEE
519-1992
Slide 7
01. ELECTROMAGNETIC COMPATIBILITY (EMC) OMC | Radiated &
Conduced It is necessary to deal with two kind of emissions: The
electric noise is produced by the inverter bridge. It is due to the
interruption of the current signal when the thyristors commutate
their status (switch over ON and OFF and vice versa). For this
reason the electric noise is a high frequency current signal which
is coupled to the current that is flowing in the drive to the motor
and that additionally can be emitted.
Slide 8
RADIATED The RADIATED electric noise will be attenuated
considering: The use of metallic conductions. The use of shielded
wires. The own metallic cabinet of the drive will help to minimize
this effect. NOT NEEDED 01. ELECTROMAGNETIC COMPATIBILITY (EMC) OMC
| Radiated
Noise coupled to the INPUT SIGNAL of the drive 01.
ELECTROMAGNETIC COMPATIBILITY (EMC) OMC | Conduced | Input
Recommended use of RFI Input Filters (Radio Frequency
Interferences) as well called EMC Filters (Electro-Magnetic
Compatibility). Regulation which controls the selection of these
filters is UNE-EN 61800-3/A11:2002. See details on Annex I.
Slide 11
Noise coupled in the CURRENT FLOWING TO THE MOTOR - OUTPUT
Output Common Mode Ferrites, in case of the couple noise is common
mode noise, that means, noise signal coupled to the capacitances
existing between the phases and the earth and also between the
motor windings and the earth. This noise is the responsible of the
bearing damages. Sinusoidal / LC filters, deals with the problem by
converting the chopped signal into a sinusoidal signal reducing the
noise. dV/dt Output Filters, in case of the coupled noise is
differential noise, that means, noise signal coupled to the
capacitances existing between phases. This noise will produce
isolation drillings and additionally will increase the dV/dt
factor. These filters can be: Output Inductance (output coils in
series, one per phase) Iron Dust Toroids, in all output phases. 01.
ELECTROMAGNETIC COMPATIBILITY (EMC) OMC | Conduced | Output
Slide 12
It is possible to observe that the output waveform of the drive
is as follow: This is the result of the inverter bridge action.
Show film 01. ELECTROMAGNETIC COMPATIBILITY (EMC) OMC | Conduced |
Output
Slide 13
If the waveform is amplified, it is possible to observe that
the angle is not 90 exactly: DrivedV/dtLosses 132kW800V/s1380W
132kW4000V/s1100W 01. ELECTROMAGNETIC COMPATIBILITY (EMC) OMC |
Conduced | Output | dV/dt
Slide 14
By incrementing the dV/dt ramp is possible to reduce the drive
losses, that allows to the drives to dissipate less power and
consequently they can be smaller. DrivedV/dtLosses 132kW800V/s1380W
132kW4000V/s1100W The main disadvantage of this method is the
appearance of brusque over-impulses in the drive output which will
be higher at motor input. It is possible to check this in the
measurement realized using a competitor drive: Actual measurement
on competitor drive of 200A on load 01. ELECTROMAGNETIC
COMPATIBILITY (EMC) OMC | Conduced | Output | dV/dt
Slide 15
To solve this problem, Power Electronics works over the gate
resistor of the IGBTs, guaranteeing that those over-impulses do not
overcome a concrete value. Actual measurement on a drive of 200A on
load: COMPETITOR Rg is the gate resistor and it controls the load
of the capacitor which conform the IGBT. Actual measurement on a
drive of 200A on load: POWER ELECTRONICS 01. ELECTROMAGNETIC
COMPATIBILITY (EMC) OMC | Conduced | Output | dV/dt
Power Electronics for 690V drives integrates the CLAMP system.
01. ELECTROMAGNETIC COMPATIBILITY (EMC) OMC | Conduced | Output |
dV/dt This circuit injects the commutation peak voltage that occurs
in the IGBTs due to the inductance caused by the output cable and
the motor. This system avoids IGBTs and motor damage and reduce the
dv/dt filter overheat.
Slide 18
01. ELECTROMAGNETIC COMPATIBILITY (EMC) OMC| CONDUCED | Output
| Sinusoidal/LC filter L C Converts the chopped signal into a
sinusoidal signal
For higher cable lengths additional filters must be used. See
next pages. 01. ELECTROMAGNETIC COMPATIBILITY (EMC) OMC |
Competitors SUPPLIER A
Slide 21
DRIVE SUPPLIER A 01. ELECTROMAGNETIC COMPATIBILITY (EMC) OMC|
Competitors
Slide 22
SUPPLIER A 01. ELECTROMAGNETIC COMPATIBILITY (EMC) OMC|
Competitors
Slide 23
For higher cable lengths additional output chokes must be used.
For further details, see next page. SUPPLIER B 01. ELECTROMAGNETIC
COMPATIBILITY (EMC) OMC| Competitors
Slide 24
SUPPLIER B 01. ELECTROMAGNETIC COMPATIBILITY (EMC) OMC|
Competitors
Slide 25
SUPPLIER C 01. ELECTROMAGNETIC COMPATIBILITY (EMC) OMC|
Competitors
Slide 26
Input chokes (as standard) Output dV/dt filters (as standard)
Electronic control of the dV/dt of the IGBT Supply Voltage400Vac
(-20% to +10%) Frames1234567891011 Screened (m) 150 Unscreened (m)
300 Mechanical construction Design of PCBs Supply Voltage550Vac to
690Vac (-20% to +10%) Frames34567891011 Screened (m) 100 Unscreened
(m) 200 For higher cable length contact with Power Electronics
SD700 SERIES 01. ELECTROMAGNETIC COMPATIBILITY (EMC) OMC|
SD700
Slide 27
Admissible Peak voltage limit curves in AC motors terminals:
01. ELECTROMAGNETIC COMPATIBILITY (EMC) OMC| SD700
Slide 28
Slide 29
One sample of the tests to the SD700. 01. ELECTROMAGNETIC
COMPATIBILITY (EMC) OMC| SD700
01. ELECTROMAGNETIC COMPATIBILITY (EMC) Standards &
Regulations IEC61800-3 The CE certification for Variable Speed
Drive requires compliance with directive : EMC 2004/108/CE
IEC61800-3 compliance
Slide 33
WHERE? Classifying CriteriaApplication Limit First environment
Non restricted distributionC1 Restricted distributionC2 Second
environment Input current 100A C3 Input current > 100AC4 First
Environment: Includes domestic or residential use. It includes
also, places directly connected, without intermediate transformers,
to a power supply distribution system of low energy which
additionally gives supply to buildings used for domestic uses
(cinemas, theatres, shopping centres, hospitals,). Second
Environment: (Named also industrial). It includes all places
different from those which are directly connected to a power supply
distribution system of low energy which additionally gives supply
to buildings used for domestic uses (factories and facilities
supplied with transformer of medium voltage to low voltage). 01.
ELECTROMAGNETIC COMPATIBILITY (EMC) Standards & Regulations |
61800-3 IEC61800-3/A11
Slide 34
WHERE? Classifying CriteriaApplication Limit First environment
Non restricted distributionC1 Restricted distributionC2 Second
environment Input current 100A C3 Input current > 100AC4
Non-Restricted Distribution: Marketing modality where the power
supply of the drive does not depend on the customer or user
regarding to EMC issues for the application of operation.
Restricted Distribution: Marketing modality where the manufacturer
limits the supplying of the drive to those customers or users
which, in an independent or together way, have technical competence
on the EMC requirements for the application of operation.
IEC61800-3/A11 01. ELECTROMAGNETIC COMPATIBILITY (EMC) Standards
& Regulations | 61800-3
Slide 35
EMC PLAN I < 100A I > 100A RADIATED 01. ELECTROMAGNETIC
COMPATIBILITY (EMC) Standards & Regulations | 61800-3 CONDUCTED
C1 C2 C4C3 1 st Environment 2 nd Environment Quasi pick value
Average value
Slide 36
01 Electromagnetic Compatibility (EMC) 02 Total Harmonic
Distortion (THD) Index
Slide 37
> Basic principles > Measurement > Effects >
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FREEMAQ - Active Filters - Multipulses drives > Competitors
TOTAL HARMONIC DISTORTION 02 TOTAL HARMONIC DISTORTION Index
Slide 38
02 TOTAL HARMONIC DISTORTION Basic Principles | What is the
Harmonic Distortion? It can be demonstrate that any periodic
waveform (squared, triangular, ) can be represented as the sum of
several sinusoidal waves with different frequencies and phases. All
those waves constitute the harmonic spectrum of the wave.
Slide 39
02 TOTAL HARMONIC DISTORTION Basic Principles | What is the
Harmonic Distortion? If g 50Hz or 60 Hz If 5rd 5 f g If 7th 7 f g I
T = I 1 + I 5 ..+I n
Slide 40
Wave Fourier Transform THDi Value 02 TOTAL HARMONIC DISTORTION
Meassurement
Slide 41
In variable speed drives applications both the harmonic current
distortion and the harmonic voltage distortion are of interest. The
harmonic current and voltage distortion have different effects on
the power system and it is therefore important to separate them.
The harmonic current distortion is caused by the rectifier part of
the variable speed drive, typically a 6-pulse diode rectifier. The
harmonic currents can be described as a reactive current adding to
the active current. Consequently the harmonic current distortion is
increasing the RMS current and if not taking into account can
result in overheating of components such as the supply transformer
or cables. The amount of harmonic current distortion is often
described in percent of the fundamental current also known as the
total harmonic current distortion (THID). 02 TOTAL HARMONIC
DISTORTION Meassurement
Slide 42
The harmonic current is normally flowing from the harmonic
current generator (e.g. the diode rectifier) into the mains. The
voltage drop caused by the harmonic currents over the supply
impedance causes then the harmonic voltage distortion. I.e. the
harmonic voltage distortion is a product of the harmonic current
distortion and the supply impedance, where a grid with the largest
impedance yields the highest voltage distortion. The harmonic
voltage distortion can interfere with equipment connected to the
same line such as direct on-line motors or electronic equipment and
eventually cause this equipment to fail. The amount of harmonic
voltage distortion is often described in percent of the fundamental
voltage also known as the total harmonic voltage distortion (THVD).
02 TOTAL HARMONIC DISTORTION Meassurement
Slide 43
> Basic principles > Measurement > Effects >
Standards & Regulations > Solutions - Passive Filters -
FREEMAQ - Active Filters - Multipulses drives > Competitors
TOTAL HARMONIC DISTORTION 02 TOTAL HARMONIC DISTORTION Index
Slide 44
1) Electrical Grid and Power Transformer overload and heating.
2) Reduction of the Motor Efficiency, non sinusoidal waveforms
increases internal heating lost. 3) Resonance effects and power
capacitors banks overload, the power factor corrections systems do
not work properly increasing the energy bill. 4) Electronic and
computers underperformance. Low consumption and single phase
devices could be affected and do not work properly. 02 TOTAL
HARMONIC DISTORTION Effects
Slide 45
> Basic principles > Measurement > Effects >
Standards & Regulations > Solutions - Passive Filters -
FREEMAQ - Active Filters - Multipulses drives > Competitors
TOTAL HARMONIC DISTORTION 02 TOTAL HARMONIC DISTORTION Index
Slide 46
The legislation applicable for drives is that described in the
international regulation IEC61800- 3. Included in that general
regulation, there are some others regulations which refer to
harmonics such us IEC61000-2-4 (Class 3: THD=10%) or IEC61000-2-2
(THD=8%) Literal description extracted from regulation IEC61800-3:
The immunity levels used for the design regarding the THD of
voltage and the individual harmonics orders will be as minimum
equal to the permanent compatibility levels at the IEC61000-2-2
(class 3: THD=10%) or IEC61000-2-4 (THD=8%), for those situations
in permanent service. For transient situations (duration less than
15 seconds), the immunity levels used for the design will be
minimum 1.5 times the permanent levels. 02 TOTAL HARMONIC
DISTORTION Standards & Regulations
Slide 47
NORMSDESCRIPTION IEC61000-2-4 The norm establishes the
electromagnetic compatibility levels for low frequency conducted
distortions at industrial installations. IEC61000-2-2 The norm
establishes the electromagnetic compatibility levels for low
frequency distortions at public low voltage supply systems.
IEC61000-2-12 The norm established the electromagnetic
compatibility levels for low frequency distortions at public medium
voltage supply systems. 02 TOTAL HARMONIC DISTORTION Standards
& Regulations
Slide 48
This regulation refers to conducted distortions at frequency
ranges from 0kHz to 9kHz. It establishes the numeric values of
compatibility levels for industrial supply distribution systems and
no publics at nominal voltages up to 35kV and nominal frequencies
of 50Hz or 60Hz. ELECTROMAGNETIC ENVIRONMENT CLASSES CLASS 1 To
protected distribution systems and has compatibility levels lower
than the public power supply systems. It is related to the use of
the equipments very sensible to the supply distribution
distortions, as the electric instruments of technological
laboratories, some kind of automatic equipments and protection
equipments, some computers, etc CLASS 2 This class is generally
applied to PCC and PCI in industrial supply distribution systems
and some others no public supply systems. The compatibility levels
are generally identical to the corresponding to public supply
systems. For that reason, the equipments (in our case the VSD)
designed to be used in public power supply systems could also be
used in this class in industrial environment CLASS 3 This class is
applicable only for PCI at industrial environment. There should be
considered under the following conditions: Most par of the load is
supplied with converters, there are welding machines, the big
motors are often started, the load varies quickly. 02 TOTAL
HARMONIC DISTORTION Standards & Regulations | IEC61000-2
-4
Slide 49
Compatibility levels for Total Harmonic Distortions CLASS
1CLASS 2CLASS 3 Total Harmonic Distortion (THD) 5%8%10% Note: In
case of one part of the power supply system is used for important
non linear loads, the compatibility levels of class 3 for this par
of the supply distribution could be 1,2 times the above mentioned
values. Then it is necessary to take caution for those equipments
there connected. Nevertheless, in the CCP (public supply
distribution system) the values offered in norms IEC61000-2-2 and
IEC61000-2-12 will prevail. 02 TOTAL HARMONIC DISTORTION Standards
& Regulations | IEC61000-2 -4
Slide 50
This norm refers to the conducted distortions in the frequency
range from 0kHz to 9kHz, with amplified option to 148kHz for
signals transmission system to the supply distribution system.
These numerical values are offered for compatibility levels in case
of public supply distribution system of low voltage with nominal
voltage of 420V single-phase or 690V 3-phase and nominal frequency
of 50Hz or 60Hz. Compatibility levels for individual harmonics
voltages in low voltage distribution systems. Odd harmonics not
multiple of 3 Odd harmonics multiple of 3 (note) Even harmonics
Order of harmonic (h) Voltage of harmonic (%) Order of harmonic (h)
Voltage of harmonic (%) Order of harmonic (h) Voltage of harmonic
(%) 563522 7591,541 113,5150,460,5 133210,380,5 17 h 492,27 x
(17/h)-0,2721 h 450,210 h 500,25 x (10/h)+0,25 Note: The levels
indicated through odd harmonics multiples of three are applied to
the homopolar harmonics. So this, in a 3-phase distribution line
without neutral cable with no load connected between a phase and
ground, the value of the harmonics order 3 and 9 can be lower
enough than compatibility levels, depending on the distribution
line imbalance. 02 TOTAL HARMONIC DISTORTION Standards &
Regulations | IEC61000-2-2
Slide 51
This norm refers to the conducted distortions in the frequency
range from 0kHz to 9kHz, with amplified option to 148,5kHz for
signals transmission system to the supply distribution system.
These numerical values are offered for compatibility levels in case
of public supply distribution system of low voltage with nominal
voltage between 1kV and 35kV and nominal frequency of 50Hz or 60Hz.
The compatibility levels are specified for electromagnetic
distortion of those types that can be expected in the public power
supply distribution systems of medium voltage, with the target of
helping to define the following: a)The limits to be established for
distortions emissions (in our case of study, harmonics) in the
public power supply distribution systems. b)The immunity limits to
be established by products committees or for other devices which
support conducted emissions in the public power supply distribution
lines. The medium voltage systems covered by this norm are public
power supply distribution systems that supply to: a)Particular
installations where devices are connected directly or through
transformers. b)Sub-stations that supply to low voltage public
power supply distribution lines. 02 TOTAL HARMONIC DISTORTION
Standards & Regulations | IEC61000-2-12
Slide 52
Compatibility levels for individual harmonic voltages in
distribution lines of medium voltage. Odd harmonic not multiples of
3 Odd harmonics multiples of 3 (note) Even harmonics Harmonic order
(h) Harmonic voltage (%) Harmonic order (h) Harmonic voltage (%)
Harmonic order (h) Harmonic voltage (%) 563522 7591,541
113,5150,460,5 133210,380,5 17 h 492,27 x (17/h)-0,2721 h 450,210 h
500,25 x (10/h)+0,25 Note: The levels indicated through even
harmonics multiples of three are applied to the homopolar
harmonics. So this, in a 3-phase distribution line without neutral
cable with no load connected between a phase and ground, the value
of the harmonics order 3 and 9 can be lower enough than
compatibility levels, depending on the distribution line imbalance.
02 TOTAL HARMONIC DISTORTION Standards & Regulations |
IEC61000-2-12
Slide 53
SUMMARY It is necessary to clarify that in order to fulfill
standard regulations, it is required to fulfil the following
norms:IEC61000-2-2, IEC61000-2-4 or IEC61000-2-12 depending on the
location where the equipments are connected. If those regulations
above mentioned are fulfilled and the THD values in current are
above the specified ones in document IEEE-519, then it is possible
to state that both the installation and the equipments are have
compliance with the norms. Special applications General system
Dedicated system THD (voltage) 3%5%10% Maximum harmonic current
distortion Order of each harmonic Isc/IL
> Basic principles > Measurement > Effects >
Standards & Regulations > Solutions - Passive Filters -
FREEMAQ - Active Filters - Multipulses drives > Competitors
TOTAL HARMONIC DISTORTION 02 TOTAL HARMONIC DISTORTION Index
Slide 55
PASSIVE FILTERS Input Coils - Choke Inductances Passive 5 th
& 7 th Notch Filter HIGH INPUT IMPEDANCE NOTCH FILTER Low
Harmonic FREEMAQ ACTIVE FILTERS. Controller bridge rectifier -
Active filter VSD Active Front End MULTIPULSES DRIVES Low voltage
12, 18, 24 pulses drives Medium Voltage Multipulse Drive 02 TOTAL
HARMONIC DISTORTION Solutions
Slide 56
These passive filters can be placed in the rectifier bridge
input, realizing a double mission: First of all, they protect to
the rectifier from voltage variation of the mains. On the other
hand, they filter the produced harmonics making softer the
sinusoidal wave of current. SD700 Frame 1 & 2 SD700 Frames 3 on
They can also be placed in the DC bus. The rectifier bridge will
not be as protected as in the previous configuration, but this is
always a low cost option. Passive Filter Input Coils Choque
Inductances 02 TOTAL HARMONIC DISTORTION Solutions | Passive
filter
Slide 57
Zg L1 C1 1) LC Filters designed for an Specific Harmonic and
Grid Impedance ( Zg) 2) Variation on Zg Increase THDi 3) Variation
on Zg May cause Resonance 4) Valid for original installations, not
compatible with new Grid Loads f 5th f 7th 1 st 5 th 7 th 1 st 5 th
7 th Grid Impedance (Zg) Variation L2 C2 02 TOTAL HARMONIC
DISTORTION Solutions | Passive filter | 5th & 7th Notch
Filter)
Slide 58
Zg L1 C1 L2 L3 1) LCL Filters designed for General Harmonic
attenuation and Independent from the Grid Impedance ( Zg) 2)
Variation on Zg Do NOT affect to THDi. Z L1 >> Zg 3) Built in
with robust electric components 4) Never cause resonance 1 st 5 th
7 th 02 TOTAL HARMONIC DISTORTION Solutions | Low Harmonics
FREEMAQ
Slide 59
Zg C1 L1 L2 CONTROLLED BRIDGE RECTIFIER 1) Works as a Current
source. 2) LCL Filter in Parallel. 3) Smaller size of L1 and L2,
designed for switching frequency. 4) Built in with Semiconductors
and control software - reduce robustness 02 TOTAL HARMONIC
DISTORTION Solutions | Active Filter - Controller bridge rectifier
-(AAF)
Slide 60
Zg L1 C1 L2 1) Regenerates the braking energy 4 quadrants
drive. Increase the overall efficiency 2) Serie LCL Filter 3)
Smaller size of L1 and L2, designed for switching frequency. 4)
Built in with Semiconductors and control software - reduce
robustness 02 TOTAL HARMONIC DISTORTION Solutions | Active Filter |
VSD Active Front End (AFE)
Slide 61
The 12, 18, 24 pulses drive have two, three or four rectifier
bridges and the input voltage of each rectifier bridge is 30 / 15 /
7,5 diphase each other PULSESTHDi (%) 6 < 40 % 12 < 15 % 18
< 9 % 24 < 5% To do that, it is needed a special transformer
with multiple secondary windings is required. 02 TOTAL HARMONIC
DISTORTION Solutions | Active Filter | Multipulses
Slide 62
12 PULSES ELECTRIC SCHEME 02 TOTAL HARMONIC DISTORTION
Solutions | Active Filter | Multipulses
Slide 63
12 PULSES RECTIFYING BRIDGE We can suppose a quasi ideal system
applied to the rectifier, considering squared wave signal as
reference. Having into consideration that the double secondary,
explained before, enters a 30 phase shift in the currents applied
to each rectifier, the result is a waveform much more sinusoidal in
the inverter bridge: 02 TOTAL HARMONIC DISTORTION Solutions |
Active Filter | Multipulses
Slide 64
(*): Depending on the Grid Impedance Zg. Notch filter Re-design
for grid load changes. FILTER TECHNOLOGY LOAD 60% LOAD 75% LOAD
100% Passive 5th & 7th Notch Filter 7% (*) 6% (*) 5% (*) Low
Harmonic FREEMAQ 6.5%5%5% Active Filter 10%8%5% VSD Active Front
End 10%8%5% 02 TOTAL HARMONIC DISTORTION Solutions | THDi variation
with load
Slide 65
FILTER TECHNOLOGY LOAD 60% LOAD 75% LOAD 100% Passive 5th &
7th Notch Filter 96.5 97 97.5 Low Harmonic FREEMAQ 96.5 97 Active
Filter 96.5 97 VSD Active Front End 96 96.5 97 02 TOTAL HARMONIC
DISTORTION Solutions | Efficiency variation with load
Slide 66
XMV660 is multi-cell VFD with series multi-cell VFD with
series-connect units, high voltage input, high voltage output. VFD
is composed of transformer, power cells and control system.
Communication between power cells and control system is performed
by optic fibre that can handle the problem of separation between
heavy current and light current as well as electric magnetic
harassment. 02 TOTAL HARMONIC DISTORTION Solutions | Multipulses |
MV
Slide 67
Each power cell is AC-DC-AC voltage source and low voltage
transformer with 3-phase input, single phase output. The rectifying
side of power cell is rectified by diode 3-phase full bridge in the
mode of not-controllable full wave. Electrolytic capacitor is used
to filter wave and store energy in the middle, the output side is
formed by 4 pieces of IGB in the form of H bridge. Diode does not
control rectification, power factor of single power cell is 0.97.
Capacitor can buffer power supply impact. Equipment can keep on
working in case of insufficient voltage or power off within short
time. Structure and power cell working principle 02 TOTAL HARMONIC
DISTORTION Solutions | Multipulses | MV
Slide 68
At any moment, there are 3 types of possible output voltage. If
A+ is on with B-, the output voltage from U to V is +Ud, if B+ is
on with A, output voltage from U to V is Ud, if A+ is on with B+ or
A- is on with B-, output voltage from U to V is 0V. In the end,
equal amplitude PWM wave form can be obtained from U, V output
terminal through control on/off on the IGBT A+ A- B+ B-. Control
over Output Voltage of Power Cell 02 TOTAL HARMONIC DISTORTION
Solutions | Multipulses | MV
Slide 69
Frequency of output voltage of power cell is changed by
altering the cycled period between positive voltage and negative
voltage of PWM wave form. Size of AC basic wave of output voltage
from the power cell is changed by altering duty ratio between
positive and negative voltage of PWM wave form. Forma de onda
salida PWM durante Frecuencia de Alta Conmutacin Forma de onda de
salida PWM durante Frecuencia de Baja Conmutacin Frequency and
Voltage Varying principle of Power Cell 02 TOTAL HARMONIC
DISTORTION Solutions | Multipulses | MV
Slide 70
Output of neighboring power cells are connected in series in Y
form, which can realize high voltage output. Each power cell
undertakes 1/n phase voltage, 100% motor current, 1/3n output
efficiency. For 6KV VFD, if 5 steps in each phase are connected in
series, each power cell can output 693V, phase voltage is 3464V,
wire voltage is 6000V. Unit DC Bus voltage is lower than 980V. IGBT
resisting 1700V can be adopted. Output Connection of Power Cell 02
TOTAL HARMONIC DISTORTION Solutions | Multipulses | MV
Slide 71
En cualquier momento, la tensin de salida que cada clula puede
ofrecer es: Tensin= +600V en caso de que Q1 y Q4 estn en ON.
Tensin= -600V en caso de que Q2 y Q3 estn en ON. Tensin= 0V en caso
de que Q1 y Q3 estn en ON si Q2 y Q4 estn en ON. Q1 Q2 Q3 Q4 02
TOTAL HARMONIC DISTORTION Solutions | Multipulses | MV
Slide 72
Detail Level 1 : Power cell A2 offers 600V at the output, power
cells A1 and A3 offer 0V. Therefore, the voltage is +600V.
Multi-level Signal Generation 02 TOTAL HARMONIC DISTORTION
Solutions | Multipulses | MV
Slide 73
Multi-level Signal Generation Detail Level 2: Power cells A1
and A3 offer 600V at the output, power cell A2 offers 0V.
Therefore, the voltage is +1200V.. 02 TOTAL HARMONIC DISTORTION
Solutions | Multipulses | MV
Slide 74
Multi-level Signal Generation Detail Level 3: The three power
cells A1, A2 and A3 offer 600V at the output each one. Therefore,
the voltage is +1800V.. 02 TOTAL HARMONIC DISTORTION Solutions |
Multipulses | MV
Slide 75
Power cell in the same phase outputs basic wave voltage with
the same amplitude and phase position. But the carrier wave of
serial connected cells are separated at certain electric angle.
Phase shifting of triangle carrier wave is 360 /n electric angle of
carrier wave. Producing mechanism of Multi-cell and Phase-shifting
PWM 02 TOTAL HARMONIC DISTORTION Solutions | Multipulses | MV
Slide 76
Wave form of phase voltage and wire voltage (take 3 grade as
example). As for n grade system, there are 2n+1 cells in the phase
voltage and 4n+1 cells in the wire voltage. If the modulating
frequency of power cell is f, the equivalent on/off frequency of
output wire voltage is 2nf. The on/off frequency of IGBT is smaller
(the on/off loss is also small), the equivalent on/off frequency of
output is very high. As there is wave filtration of induction in
the motor, current content of output harmonic is very low. Phase
Voltage and wire Voltage of Multi-cell Phase shifting Output 02
TOTAL HARMONIC DISTORTION Solutions | Multipulses | MV
Slide 77
> Basic principles > Measurement > Effects >
Standards & Regulations > Solutions - Passive Filters -
FREEMAQ - Active Filters - Multipulses drives > Competitors
TOTAL HARMONIC DISTORTION 02 TOTAL HARMONIC DISTORTION Index
Slide 78
SUPPLIER A 1.DC CHOKES. 38% of drives standard built in 62% of
drives external option 2.LINE CHOKES. 100% of drives external
option DRIVE OTHER SUPPLIER 02 TOTAL HARMONIC DISTORTION
Competitors
Slide 79
SUPPLIER B 1.DC CHOKES. 100% of drives external option 2.LINE
CHOKES. 100% of drives external option 02 TOTAL HARMONIC DISTORTION
Competitors
Slide 80
FILTER SUPPLIER C 1.DC CHOKES. 100% of drives external option
2.LINE CHOKES. 100% of drives external option 02 TOTAL HARMONIC
DISTORTION Competitors