Title of Invention

METHOD FOR OPERATING A CONVERTER CIRCUIT, AND APPARATUS FOR CARRYING OUT THE METHOD

Abstract Disclosed is a method for operating a converter circuit comprising a converter unit (1) with a plurality of triggerable power semiconductor switches and an LCL filter (3) that is connected to each phase terminal (2) of the converter unit (1). According to said method, the triggerable power semiconductor switches are triggered by means of a triggering signal (S) formed from a hysteretic actual power value (d<SUB>P</SUB>), a hysteretic reactive power value (d<SUB>Q</SUB>), and a selected flux sector (&thetas;n). The hysteretic actual power value (d<SUB>P</SUB>) is formed from a differential actual power value (P<SUB>diff</SUB>), by means of a first hysteresis controller (16) while the differential actual power value (P<SUB>diff</SUB>)is formed by subtracting an estimated actual power value (P) and a damping actual power value (d<SUB>d</SUB>) from an actual power reference value (Pref). The damping actual power value (d<SUB>d</SUB>) is formed from a sum of a multiplication of an &agr; component of the space vector transformation of filter capacity currents (i<sub>Cf&agr</sub>;) of the LCL filter (3) with an a component of the space vector transformation of phase terminal currents (i<sub>fi&agr</sub>;) and a multiplication of a ß component of the space vector transformation of filter capacity currents (i<sub>Cfß</sub>) of the LCL filters (3) with a ß component of the space vector transformation of phase terminal currents (i<sub>fiß</sub>), said sum being weighted with an adjustable damping factor (k<sub>d</sub>). The hysteretic reactive power value (d<sub>Q</sub>) is formed from a differential reactive power value (Q<sub>diff</sub>) by means of a second hysteresis controller (17) while the differential reactive power value (Q<sub>diff</sub>) is formed by subtracting an estimated reactive power value (Q) and a damping reactive power value (Q<sub>d</sub>) from a reactive power reference value (Q<sub>ref</sub>). The damping reactive power value (Q<sub>d</sub>) is formed from a difference between a multiplication of the ß component of the space vector transformation of filter capacity currents (i<sub>Cfß</sub>) of the LCL filters (3) with the a component of the space vector transformation of phase terminal currents (i<sub>fi&agr</sub>;) and a multiplication of the &agr; component of the space vector transformation of filter capacity currents (i<sub>Cf&agr</sub>;) of the LCL filters (3) with the ß component of the space vector transformation of phase terminal currents (i<sub>fiß</sub>), said difference being weighted with an adjustable damping factor.(k<sub>d</sub>). Also disclosed is a device for carrying out the inventive method.
Full Text

Method for operating a converter circuit, and apparatus
for carrying out the method
DESCRIPTION
Technical field
The invention relates to the field of power electronics, based on a method for operating a converter circuit, and an apparatus for carrying out the method as claimed in the precharacterizing clauses of the independent claims.
Prior art
Conventional converter circuits have a converter unit with a multiplicity of drivable power semiconductor switches, which are connected in a known manner in order to switch at least two switching voltage levels. An LCL filter is connected to each phase connection of the converter unit. A capacitive energy store is also connected to the converter unit and is normally formed by one or more capacitors. An apparatus is provided for operating the converter circuit, which has a control device for producing a hysteresis power value, a hysteresis wattless component value and a selected flux sector, which control device is connected to the drivable power semiconductor switches via a drive circuit in order to form a drive signal from the hysteresis power value, the hysteresis wattless component value and the selected flux sector. The power semiconductor switches are therefore driven by means of the drive signal.
A converter circuit as mentioned above is subject to the problem that the LCL filters can cause permanent distortion, that is to say undesirable oscillations, in the filter output currents and filter output voltages

as a result of resonant oscillations of the LCL filters, as shown in the normal waveform of filter output currents shown in Figure 3. In an electrical AC voltage power supply system, which is typically connected to the filter outputs, or when an electrical load is connected to the filter outputs, . such distortion can lead to damage or even to destruction, and is therefore very highly undesirable.
Description of the invention
One object of the invention is therefore to specify a method for operating a converter circuit, by means of which it is possible to actively damp distortion, caused by LCL filters connected to the converter circuit, in the filter output currents and filter output voltages. A further object of the invention is to specify an apparatus by means of which the method can be carried out in a particularly simple manner. These obj ects are achieved by the features of claim 1 and claim 9 respectively. Advantageous developments of the invention are specified in the dependent claims.
The converter circuit has a converter unit with a multiplicity of drivable power semiconductor switches, and an LCL filter connected to each phase connection of the converter unit. In the method according to the invention for operating the converter circuit, the drivable power semiconductor switches are now driven by means of a drive signal formed from a hysteresis power value, from a hysteresis wattless component value and from a selected flux sector. According to the invention, the hysteresis power value is formed from a difference power value by means of a first hysteresis regulator and the difference power value is formed from the subtraction of an estimated power value and of a damping power value from a reference power value, with the damping power value being formed from a sum, weighted by a variable damping factor, of a multiplication of the a component of the space vector

transformation of filter capacitance currents of the LCL filters by an a component of the space vector transformation of phase connection currents and a multiplication of a (3 component of the space vector transformation of filter capacitance currents of the LCL filters by a P component of the space vector transformation of phase connection currents. Furthermore, the hysteresis wattless component value is formed from a difference wattless component value by means of a second hysteresis regulator, and the difference wattless component value is formed from the subtraction of an estimated wattless component value and of a damping wattless component value from a reference wattless component value with the damping wattless component value being formed from a difference, weighted by the variable damping factor of a multiplication of the P component of the space vector transformation of the filter capacitance currents of the LCL filters by the a component of the space vector transformation of phase connection currents and a multiplication of the a component of the space vector transformation of filter capacitance currents of the LCL filters by the P component of the space vector transformation of the phase connection currents.
The damping power value and the damping wattless component value advantageously make it possible to actively damp distortion, that is to say undesirable harmonics, in the filter output currents and filter output voltages, so that distortion is greatly reduced and, in the ideal case is very largely suppressed. A further advantage of the method according to the invention is that there is no need to connect any discrete, space-consuming, complex and therefore expensive damping resistor to the respective phase connection, in order to allow undesirable distortion to be effectively damped.
The apparatus according to the invention for carrying out the method for operating the converter circuit has

a control device which is used to produce a hysteresis power value, a hysteresis wattless component value and a selected flux sector and is connected via a drive circuit to the drivable power semiconductor switches in' order to form a drive signal.
According to the invention, the control device has a first calculation unit for forming the hysteresis power value, the hysteresis wattless component value and the selected flux sector, with the first calculation unit having a first hysteresis regulator for forming the hysteresis power value from a difference power value, a second hysteresis regulator for forming the hysteresis wattless component value from a difference wattless component value and a vector allocator for forming the selected flux sector. Furthermore, the control device has a first adder for forming the difference power value from the subtraction of an estimated power value and of a damping power value from a reference power value and a second adder for forming the difference wattless component value from the subtraction of an estimated wattless component value and of a damping wattless component value from a reference wattless component value. Moreover, the control device has a second calculation unit for forming the damping power value and the damping wattless component value, with the damping power value being formed from a sum, weighted by a variable damping factor, of a multiplication of an a component of the space vector transformation of filter capacitance currents of the LCL filters by an a component of the space vector transformation of phase connection currents, and a multiplication of a P component of the space vector transformation of filter capacitance currents of the LCL filter by a P component of the space vector transformation of phase connection currents. Furthermore, the damping wattless component value is formed from a difference, weighted by the variable damping factor, of a multiplication of the (3 component of the space vector transformation of filter

capacitance currents of the LCL filters by the a component of the space vector transformation of phase connection currents and a multiplication of the a component of the space vector transformation of filter capacitance currents of the LCL filters by the P component of the space vector transformation of phase connection currents.
The apparatus according to. the invention for carrying out the method for operating the converter circuit can thus be produced very easily and at low cost, since the circuit complexity can be kept extremely low and, furthermore, only a small number of components are required- to construct it. The method according to the invention can be carried out particularly easily by means of this apparatus.
These and further objects, advantages and features of the present invention will become clear from the following detailed description of preferred embodiments of the invention and in conjunction with the drawing.
Brief description of the drawings
In the drawings:
Figure 1 shows one embodiment of an apparatus
according to the invention for carrying out the method according to the invention for operating a converter circuit,
Figure 2 shows one embodiment of a seventh
calculation unit,
Figure 3 shows a conventional waveform of the
filter output currents, and
Figure 4 shows a waveform of the filter output
currents with active damping using the method according to the invention.

The reference symbols used in the drawing and their meanings, are listed in summary form in the list of reference symbols. In principle, identical parts are provided with the same reference symbols in the figures. The described embodiments represent examples of the subject matter of the invention and have no restrictive effect.
Approaches to implementation of the invention
Figure 1 shows one embodiment of an apparatus according to the invention for carrying out the method according to the invention for operating a converter circuit. As shown in Figure 1, the converter circuit has a converter unit 1 with a multiplicity of drivable power semiconductor switches and an LCL filter 3 connected to each phase connection 2 of the converter unit 1. Accordingly, each LCL filter 3 has a first filter inductance Lfi, a second filter inductance Lfg and a filter capacitance Cf with the first filter inductance Lfi being connected to the associated phase connection 2 of the converter unit 1, to the second filter inductance Lfg and to the filter capacitance Cf. Furthermore, the filter capacitances Cf of the individual LCL filters 3 are connected to one another. By way of example, Figure 1 shows a converter unit 1 as a three-phase unit. It should be mentioned that, in general, the converter unit 1 may be in the form of any converter unit 1 for switching > 2 switching voltage levels (multi-level converter circuit) relating to the voltage of a capacitive energy store 19 connected to the converter unit 1, in which case the capacitive energy store 19 is then formed by any desired number of capacitances, which are then connected such that they are matched to the appropriately designed partial converter circuit.
In the method according to the invention for operating the converter circuit, the drivable power semiconductor

switches of the converter unit 1 are now driven by means of a drive signal S formed from a hysteresis power value dp, from a hysteresis wattless component value dp and from a selected flux sector 0n. The drive signal is normally formed using a look-up table, in which hysteresis power values dp, hysteresis wattless component values dp and selected flux sectors 0n are permanently associated with corresponding drive signals S, or a modulator, which is based on pulse-width modulation. According to the invention, the hysteresis power value dP is formed from a difference power value Pdiff by means of a first hysteresis regulator 16 as shown in Figure 1. Furthermore, the difference power value Pdiff is formed from the subtraction of an estimated power value P and a damping power value Pd from a reference power value Pref, with the damping power value Pd being formed from a sum, weighted with a variable damping factor kd, of a multiplication of an a component of the space vector transformation of filter capacitance currents iCfa of the LCL filters 3 by an a component of the space vector transformation of phase connection currents ifiβ and a multiplication of a P component with the space vector transformation of filter capacitance currents iCfβ of the LCL filters 3 by a p component of the space vector transformation of phase connection currents ifcβ as is illustrated in particular by the following formula.
Pd = kd ' (iCfa * ifia + icfp * ifip)
The reference power value Pref is freely variable and is the nominal value of the power which is intended to be produced at the output of the LCL filters 3. Furthermore, the hysteresis wattless component value dQ is formed from a difference wattless component value Qdiff by means of a second hysteresis regulator 17 and the difference wattless component value Qdiff is formed from the subtraction of an estimated wattless component value Q and a damping wattless component value Qd from a reference wattless component value Qref, with the

damping wattless component value Qd being formed from a difference, weighted by the variable damping factor kd, of a multiplication of the β component of the space vector transformation of filter capacitance currents icfβ of the LCL filters 3 by the a component of the space vector transformation of phase connection currents ifiα and a multiplication of the a component of the space vector transformation of filter capacitance currents iCfα of the LCL filters 3 by the P component of the space vector transformation of phase connection currents ifiβ as illustrated in particular by the following formula.
QThe reference wattless component value Qref is freely variable and is the nominal value of the wattless component which is intended to be produced at the output of the LCL filters 3.
It should be mentioned that the space vector transformation is defined as follows:
X = Xa 4- jxp
where x is a complex variable, xa is the a component of the space vector transformation of the variable x and xp is the P component of the space vector transformation of the variable x . All of the space vector transformations of variables mentioned above and those which will be mentioned later are produced using the formula mentioned above.
The damping power value Pd and the damping wattless component value Qd can advantageously be used for active damping of distortion, that is to say undesirable oscillation, in the filter output currents ifgir ifg2f ifg3 and filter output voltages, so that this distortion is very greatly reduced and, ideally is very largely suppressed. A further advantage of the method

Lccording to the invention is that there is no need to ;onnect any discrete space-consuming, complex and thus expensive damping resistor to the respective phase :onnection 2, in order to allow effective damping of :he undesirable distortion.
According to Figure 1, the apparatus according to the
.nvention for carrying out the method according to the
invention for operating a converter circuit for this
purpose has a control device 4 which is used for
producing the hysteresis power value dP, the hysteresis
wattless component value dQ and the selected flux
sector 0n and is connected to the drivable power
semiconductor switches via a drive circuit 5 in order
:o form a drive signal S. By way of example, the drive
circuit 5 has a look-up table in which hysteresis power
p, hysteresis wattless component values dQ and
selected flux sectors 9n are permanently associated with
corresponding drive signal S, or a modulator which is
Dased on pulse-width modulation. According to the
Invention, the control device 4 has a first calculation
anit 6 for forming the hysteresis power value dP, the
hysteresis wattless component value dQ and the selected
flux sector 9n, with the first calculation unit 6 having
the first hysteresis regulator 16 for forming the
hysteresis power value dP from the difference wattless
component value Pdiff/ the second hysteresis regulator
17 for forming the hysteresis wattless component value
dQ from the difference wattless component value Qdiff and
a vector allocator 18 for forming the selected flux
sector 0n. Furthermore, the control device 4 has a first
adder 7 for forming the difference power value Pdiff
from the subtraction of the estimated power value P and
of the damping power value Pd from the reference power
value Pref and a second adder 8 for forming the
difference wattless component value Qdiff from the
subtraction of the estimated wattless component value Q
and of the damping wattless component value Qd from the
reference wattless component value Qref. Furthermore,
the control device 4 has a second calculation unit 9

for forming the damping power value Pd and the damping wattless component value Qd, with the damping power value Pd being formed from the sum, weighted by the variable damping factor kd, of the multiplication of the a component of the space vector transformation of filter capacitance currents iCfa of the LCL filters 3 by the a component of the space vector transformation of phase connection currents ifia, and the multiplication of the P component of the space vector transformation of filter capacitance currents iCfp of the LCL filter 3 by the P component of the space vector transformation of phase connection currents ifiβ , and the damping wattless component value Qd being formed from the difference, weighted by the variable damping factor kd/ of the multiplication of the P component of the space vector transformation of filter capacitance currents icfβ of the LCL filters 3 by the a component of the space vector transformation of phase connection currents ifia and a multiplication of the a component of the space vector transformation of filter capacitance currents iCfα of the LCL filters 3 by the β component of the space vector transformation of phase connection currents ifiβ . The apparatus according to the invention for carrying out the method for operating the converter circuit can accordingly be produced very easily and at low cost, since the circuit complexity can be kept extremely low and, furthermore, only a small number of components are required to construct it. The method according to the invention can therefore be carried out particularly easily by means of this apparatus.
The estimated power value P and the estimated wattless component value Q are in each case formed from an a component of the space vector transformation of filter output currents ifga, from a β component of the space vector transformation of filter output currents ifgp, from an a component of the space vector transformation of filter output fluxes ψLa and from a P component of the space vector transformation of filter output fluxes ψLp, as is illustrated in particular by the following


In order to form the estimated power value P and the estimated wattless component value Q, the control device 4 as shown in Figure 1 has a third calculation unit 10, by means of which the estimated power value P and the estimated wattless component value Q are each calculated using the appropriate formula as mentioned above.
The a component of the space vector transformation of filter output fluxes ψLa is formed from an a component of the space vector transformation of estimated filter capacitance fluxes ψcfct and from the a component of the space vector transformation of filter output currents if gar as illustrated in particular by the following formula:

Furthermore, the p component of the space vector transformation of filter output fluxes ψLp is formed from a P component of the space vector transformation of estimated filter capacitance fluxesψCfp and from the P component of the space vector transformation of filter output currents ifgβ, as indicated in particular by the following formula:

In order to form the a component of the space vector transformation of filter output fluxes ψLa and the p component of the space vector transformation of filter output fluxesψLa the control device 4 as shown in Figure 1 has a fourth calculation unit 11, by means of which the a component of the space vector transformation of filter output fluxesψLa and the P

component of the space vector transformation of filter output fluxes ψ/Lp are calculated, in each case using the appropriate formula as stated above.
The a component of the space vector transformation of filter output currents ifgα is formed from the a component of the space vector transformation of phase connection currents ifiα which is formed by space vector transformation of the phase connection currents ifi1ifi2 if 13 as shown in Figure 1, and from the a component of the space vector transformation of the filter capacitance currents icfa which is formed by space vector transformation of the filter capacitance currents iCfi, ict2 icf3, measured as shown in Figure 1, by addition. Furthermore, the (5 component of the space vector transformation of filter output currents ifgp, is formed from the P component of the space vector transformation of phase connection currents ifip, which is formed by space vector transformation of the phase connection currents ifii, ifi2* ifi3 measured as shown in Figure 1, and from the P component of the space vector transformation of the filter capacitance currents iCfp which is formed by space vector transformation of the filter capacitance currents icfi, i~c±2r icf3 measured as shown in Figure 1, by addition. There is therefore advantageously no need to measure the filter output currents ifgi, ifg2, ifg3 thus simplifying the apparatus, since no measurement sensors are required, in particular no current transformers. It should be mentioned that the space vector transformation of the measured phase connection currents ifii, ifi2, ifi3 and of the measured filter capacitance currents ion, icf2, icf3 as well as the other space-vector-transformed variables is or can be carried out within an associated calculation unit 9, 10, 13, 14 or separately in a space-vector transformation unit which is provided additionally for this purpose.
The a component of the space vector transformation of estimated filter capacitance fluxes V]/Cfa is once again

formed from an instantaneous DC voltage value udc of the capacitive energy store 19 connected to the converter unit 1, from the drive signal S and from the a component of the space vector transformation of phase connection currents ifiα, as indicated in particular by the following formula, with uCa being the a component of the phase connection voltage of the converter unit 1, formed from the instantaneous DC voltage value udc and from the drive signal.
In a corresponding manner, the α component of the space vector transformation of estimated filter capacitance fluxes ψCfp is formed from the instantaneous DC voltage value Udc of the capacitive energy store 19 connected to the converter unit 1, from the drive signal S and from the P component of the space vector transformation of phase connection currents ifβ, ucpa being the p component of the phase connection voltage of the converter unit 1, formed from the instantaneous DC voltage value udc and from the drive signal.
Vcfp = J ucpdt - Lfi ' ifip
In order to form the a component of the space vector transformation of estimated filter capacitance fluxes Vcfa a^d the p component of the space vector transformation of estimated filter capacitance fluxes β the control device 4 as shown in Figure 1 has a fifth calculation unit 12, by means of which the a component of the space vector transformation of estimated filter capacitance fluxes β and the p component of the space vector transformation of estimated filter capacitance fluxes \βp is in each case calculated using the appropriate formula as mentioned above.
In order to form the already mentioned difference wattless component value Qdiff, a compensation wattless

component value Qcomp is additionally added, with the compensation wattless component value QCOmp being formed by low-pass filtering of an estimated filter capacitance wattless component value Qcf by means of a low-pass filter 15. This therefore advantageously avoids undesirable wattless components of the LCL filters 3, in particular of the filter capacitances Cf of the LCL filters 3, being produced at the output of the LCL filters 3, thus making it possible to ensure that only a wattless component value corresponding to the selected reference wattless component value Qref is produced at the output of the LCL filters 3. As shown in Figure 1, the compensation wattless component value Qcomp is additionally supplied to the second adder 8. Furthermore, the estimated filter capacitance wattless component value Qcf is formed from the a component of the space vector transformation of the filter capacitance currents icfa, from the P component of the space vector transformation of the filter capacitance currents icfp, from the a component of the space vector transformation of the estimated filter capacitance fluxes ψcfa and from the P component of the space vector transformation of the estimated filter capacitance fluxes βCfp as illustrated in particular by the following formula:
Qcf = © * (Vcfa ' icfa + VcfP ' icfp)
In order to form the estimated filter capacitance wattless component value Qc± as shown in Figure 1, the control device 4 has a sixth calculation unit 13, by means of which the estimated filter capacitance wattless component value Qcf is calculated using the abovementioned formula.
In order to form the already mentioned difference power values Pdiff/ at least one compensation harmonic power value Ph relating to the fundamental of the filter output currents ifgi, ifg2, ifg3 is additionally added. Furthermore, in order to form the already mentioned

difference wattless component value Qdifft at least one compensation harmonic wattless component value Qh relating to the fundamental of the filter output currents ifgi, ifg2/ ifg3 is additionally added. As shown Ln Figure 1, in order to form the difference power /alue Pdiff/ the first adder 7 is additionally supplied vith the compensation harmonic power value Ph-furthermore, in order to form the difference wattless component value Qdiff as shown in Figure 1, the second adder 7 is additionally supplied with the compensation larmonic wattless component value Qh. The compensation larmonic power value Ph and the compensation harmonic vattless component value Qh are in each case formed from :he a component of the space vector transformation of :he filter output currents ifga/ from the [3 component of :he space vector transformation of the filter output currents ifgp, from the a component of the space vector :ransformation of the filter output fluxes v|/Lot, from the i component of the space vector transformation of the filter output fluxes \|/Lp, and from the fundamental angle ot relating to the fundamental of' the filter output :urrents ifgi, ifg2, ifg3- The fundamental angle cot is provided for the calculation units 9, 10, 13, 14 and :or the vector allocator 18 as shown in Figure 1 from a )hase locked loop (PLL) . As shown in Figure 1, the :ontrol device 4 has a seventh calculation unit 14 in )rder to form the compensation harmonic power value Ph md the compensation harmonic wattless component value )h, with one embodiment of the seventh calculation unit A being shown in Figure 2. The addition or application )f at least one compensation harmonic power value Ph in >rder to form the difference power value Pdiff and of at .east one compensation harmonic wattless component ralue Qh in order to form the difference wattless :omponent value Qdiff advantageously results in an ictive reduction in the harmonics, and thus overall in i further improvement in the reduction in the larmonics.
is shown in Figure 2, the a component of the space

vector transformation of the filter output currents ifga and the p component of the space vector transformation of the filter output currents ifgp is first of all formed from supplied filter output currents ifgi, ifg2, ifg3 by space vector transformation. The a component of the space vector transformation of the filter output currents ifga and the P component of the space vector transformation of the filter output currents ifgp are then Park-Clarke-transformed, low-pass filtered and emitted as the d component and the q component of the Park-Clarke transformation of at least one desired selected harmonic of the filter output currents ihd/ ihq relating to the fundamental of the filter output currents ifgi, ifg2/ ifg3- The index h represents the hth harmonic of these variables and those mentioned in the following text, where h = 1, 2, 3, ....
In general, the Park-Clarke transformation is defined as
x =(xd +jxq)ejtot
where x is a complex variable, xd is the d component of the Park-Clarke transformation of the variable x and xq is the q component of the Park-Clarke transformation of the variable x. One advantage of the Park-Clarke transformation is that not only the fundamental of the complex variable x is transformed, but also all of the harmonics of the complex variable x that occur. As shown in Figure 2, the d component and the q component of the Park-Clarke transformation of the desired selected hth harmonic of the filter output currents ihdf ihq are in each case regulated at an associated predetermined reference value i*hd/ i*hqf preferably based on a proportional integral characteristic, and are then inverse-Park-Clarke transformed, thus resulting in the formation of an a component of the space vector transformation of the hth harmonic of reference filter output currents i*ha and a p component of the space vector transformation of the hth harmonic



be implemented in a computer system, in particular in a digital signal processor.
Overall, it has been possible to show that the apparatus according to the invention, in particular as shown in Figure 1, for carrying out the method according to the invention for operating the converter circuit, can be produced very easily and at low cost, since the circuit complexity is extremely low and, furthermore, only a small number of components are required to construct it. This apparatus therefore allows the method according to the invention to be carried out particularly easily.

List of reference symbols
1 Converter unit
2 Phase connection of the converter unit
3 LCL filter
4 Control device
5 Drive circuit
6 First calculation unit
7 First adder
8 Second adder
9 Second calculation unit
10 Third calculation unit
11 Fourth calculation unit
12 Fifth calculation unit
13 Sixth calculation unit
14 Seventh calculation unit
15 Low-pass filter
16 First hysteresis regulator
17 Second hysteresis regulator
18 Vector allocator













PATENT CLAIMS
1. A method for operating a converter circuit, with the converter circuit having a converter unit (1) with a plurality of drivable power semiconductor switches and an LCL filter (3) connected to each phase connection (2) of the converter unit (1), in which the drivable power semiconductor switches are driven by means of a drive signal (S) which is formed from a hysteresis power value (dp) , from a hysteresis wattless-component value (dQ) and from a selected flux sector (0n) , characterized
in that the hysteresis power value (dp) is formed from a difference power value (Pdiff) by means of a first hysteresis regulator (16),
in that the difference power value (Pdiff) is formed from the subtraction of an estimated power value (P) and of a damping power value (Pd) from a reference power value (Pref) with the damping power value (Pd) being formed from a sum, weighted by a variable damping factor (kd) , of a multiplication of an a component of the space vector transformation of filter capacitance currents (iCfα) of the LCL filters (3) by an a component of the space vector transformation of phase connection currents (if±p) and a multiplication of a P component of the space vector transformation of filter capacitance currents (iCfp) of the LCL filters by a p component of the space vector transformation of phase connection currents (ifip) ,
in that the hysteresis wattless component value (dQ) is formed from a difference wattless component value (Qdiff) by means of a second hysteresis regulator (17), in that the difference wattless component value (Qdiff) is formed from the subtraction of an estimated wattless component value (Q) and of a damping wattless component value (Qd) from a reference wattless component value (Qref) with the damping wattless component value (Qd) being formed from a difference, weighted by the variable damping factor (kd) of a multiplication of the

P component of the space vector transformation of
filter capacitance currents (iCfp) of the LCL filters by
the a component of the space vector transformation of
phase connection currents (ifiα) and a multiplication of
the a component of the space vector transformation of
filter capacitance currents (iCfα) of the LCL filters by
the P component of the space vector transformation of
phase connection currents (ifip) .
2. The method as claimed in claim 1, characterized in that the estimated power value (P) and the estimated wattless component (Q) are each formed from an a component of the space vector transformation of filter output currents (ifga)r from a P component of the space vector transformation of filter output currents ifgβ) , from an a component of the space vector transformation of filter output fluxes (ψLa) and from a P component of the space vector transformation of filter output fluxes
3. The method as claimed in claim 2, characterized in that the a component of the space vector transformation of filter output fluxes ψLa) is formed from an a component of the space vector transformation of estimated filter capacitance fluxes (ψcfa) and from the a component of the space vector transformation of filter output currents (ifga) ,
and in that the p component of the space vector transformation of filter output fluxes ψ/Lp) is formed from a P component of the space vector transformation of estimated filter capacitance fluxes (ψcfp) and from the P component of the space vector transformation of filter output currents ifgβ) .
4. The method as claimed in claim 3, characterized in
that the a component of the space vector transformation
of estimated filter capacitance fluxes ψfa) is formed
from an instantaneous DC voltage value (UdC) of a
capacitive energy store (19) connected to the converter
unit (1), from the drive signal (S) and from the a

component of the space vector transformation of phase
connection currents (ifiα) , and
in that the p component of the space vector
transformation of estimated filter capacitance fluxes (Vcfp) is formed from the instantaneous DC voltage value (Udc) of the capacitive energy store (19) connected to
the converter unit (1), from the drive signal (S) and
from the P component of the space vector transformation
of phase connection currents (ifip) .
5. The method as claimed in claim 3 or 4, characterized in that a compensation wattless component value (Qcomp) is additionally added in order to form the difference wattless component value (Qdiff) * with the compensation wattless component value (Qcomp) being formed by low-pass filtering of an estimated filter capacitance wattless component value (Qcf) -
6. The method as claimed in claim 5, characterized in that the estimated filter capacitance wattless component value (QCf) is formed from the a component of the space vector transformation of the filter capacitance currents (iCfα) / from the P component of the space vector transformation of the filter capacitance currents (iCfp) / from the a component of the space vector transformation of the estimated filter capacitance fluxes (ψcfa) and from the P component of the space vector transformation of the estimated filter capacitance fluxes ψcfp) •
7. The method as claimed in one of claims 3 to 6, characterized in that at least one compensation harmonic power value (Ph) relating to the fundamental of the filter output currents (ifgi, ifg2, ifg3) is additionally added in order to form the difference power value (Pdiff) r and
in that at least one compensation harmonic wattless component value (Qh) relating to the fundamental of the filter output currents (ifgi, ifg2 ifg3) is additionally added in order to form the difference wattless



a first adder (7) for forming the difference power value (Pdiff) from the subtraction of an estimated power value (P) and of a damping power value (Pd) from a reference power value (Pref) r
a second adder (8) for forming the difference wattless component value (Qdiff) from the subtraction of an estimated wattless component value (Q) and of a damping wattless component value (Qd) from a reference wattless component value (Qref) /
a second calculation unit (9) for forming the damping power value (Pd) and the damping wattless component value (Qd) , with the damping power value (Pd) being formed from a sum, weighted by a variable damping factor (kd) , of a multiplication of an a component of the space vector transformation of filter capacitance currents (iCfα) of the LCL filters (3) by an a component of the space vector transformation of phase connection currents (ifiα) / and a multiplication of a P component of the space vector transformation of filter capacitance currents (icfp) of the LCL filter (3) by a (3 component of the space vector transformation of phase connection currents (ifip) , and the damping wattless component value (Qd) being formed from a difference, weighted by the variable damping factor (kd), of a multiplication of the P component of the space vector transformation of filter capacitance currents (iCfp) of the LCL filters 3 by the a component of the space vector transformation of phase connection currents (ifiα) and a multiplication of the a component of the space vector transformation of filter capacitance currents (iCfα) of the LCL filters (3) by the p component of the space vector transformation of phase connection currents (ifip) .
10. The apparatus as claimed in claim 9, characterized in that the control device (4) has a third calculation unit (10) for forming the estimated power value (P) and the estimated wattless component value (Q) in each case from an a component of the space vector transformation of filter output currents (ifga) from a P component of





16. The apparatus as claimed in claim 15, characterized in that the control device (4) has a seventh calculation unit (14) for forming the compensation harmonic power value (Ph) and the compensation harmonic wattless component value (Qh) in each case from the a component of the space vector transformation of the filter output currents (ifgα from the P component of the space vector transformation of the filter output currents ifgβ) , from the a component of the space vector transformation of the filter output fluxes ψLa) , from the P component of the space vector transformation of the filter output fluxes ψlp and from the fundamental angle (cat) relating to the fundamental of the filter output currents (ifgi,
ifg2/ ifg3) •


Documents:

3255-CHENP-2007 AMENDED CLAIMS 20-01-2011.pdf

3255-chenp-2007 correspondence others 10-12-2010.pdf

3255-chenp-2007 form-1 20-01-2011.pdf

3255-chenp-2007 form-3 20-01-2011.pdf

3255-CHENP-2007 OTHER PATENT DOCUMENT 20-01-2011.pdf

3255-CHENP-2007 POWER OF ATTORNEY 20-01-2011.pdf

3255-CHENP-2007 CORRESPONDENCE OTHERS 12-11-2010.pdf

3255-CHENP-2007 EXAMINATION REPORT REPLY RECEIVED 20-01-2011.pdf

3255-chenp-2007-abstract.pdf

3255-chenp-2007-claims.pdf

3255-chenp-2007-correspondnece-others.pdf

3255-chenp-2007-description(complete).pdf

3255-chenp-2007-drawings.pdf

3255-chenp-2007-form 1.pdf

3255-chenp-2007-form 3.pdf

3255-chenp-2007-form 5.pdf

3255-chenp-2007-pct.pdf


Patent Number 248691
Indian Patent Application Number 3255/CHENP/2007
PG Journal Number 32/2011
Publication Date 12-Aug-2011
Grant Date 05-Aug-2011
Date of Filing 24-Jul-2007
Name of Patentee ABB SCHWEIZ AG
Applicant Address Brown Boveri Strasse 6, CH-5400 Baden
Inventors:
# Inventor's Name Inventor's Address
1 PONNALURI, Srinivas Niederwiesstrasse 12, CH-5417 Untersiggenthal
2 SERPA, Leonardo Bucheggstrasse 170, CH-8057 Zürich
PCT International Classification Number H02M 7/53
PCT International Application Number PCT/CH05/00292
PCT International Filing date 2005-05-24
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 60/646,504 2005-01-25 U.S.A.