• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The invention relates to a magnetic throttle, which is intended for use in conjunction with a converter bridge for connection to n phases with in each case m bridge branches per phase. The reactor has a core with n sub-cores, each of the sub-cores having an initial node and an end node, and m core portions connecting the start node and the end node, and each of the core portions having a winding having first () and second winding terminals. The second winding terminals of the windings of the same sub-core form a common winding connection point. The windings on the core sections are oriented such that in each core section, a current flowing through the winding into the common winding connection point generates a magnetic voltage from the starting node to the end node of the partial core. The part cores are connected by their start and end nodes and form a circle. Furthermore, the invention relates to a converter section and a converter with such a throttle.
    公开号:CH713573A2
    申请号:CH00318/17
    申请日:2017-03-15
    公开日:2018-09-28
    发明作者:Schrittwieser Lukas；Leibl Michael；Haider Michael；Thöny Friedrich；Walter Kolar Johann
    申请人:Eth Zuerich；
    IPC主号:
    专利说明:

    description
    PRIOR ART In order to supply DC loads from the three-phase alternating current network, active rectifier circuits are used according to the state of the art in order to achieve regulation of the output voltage and low network perturbations.
    If the DC voltage to be generated lies between zero and 1.5 times the phase-phase voltage amplitude, systems with a step-down characteristic can be used for this purpose. Possible circuits for realizing an active three-phase rectifier with power factor correction and buck converter characteristic have been described in CH 704 553, a variant of which is shown in FIG. 1a. This rectifier allows power transmission from the three-phase alternating voltage network with the terminals a, b, c to a DC voltage output with the terminals p and n. For this purpose, the network voltages are filtered by three input inductances Lf from a rectifier unit 1 with the output nodes x, y and z consisting of a three-phase six-pulse diode bridge and three bidirectional phase selection switches sIyi: s6,6 sEyyt rectified whereby that phase selection switch is switched on whose instantaneous value of the assigned phase voltage lies between the other two instantaneous values of the phase voltages. This results in three sections sinusoidal voltages at the nodes x, y and z, which are zstabilisiert by three capacitors Cx, y, z, wherein the potential at node x is always greater than or equal to the potential at node y and the potential at node y is always greater or equal to that at node z. By means of a subsequent switching stage 2, consisting of two series-connected buck converter half-bridges with the active switches sx | J, sr "and two diodes ny [), oay, a constant voltage over a period of the switching frequency between the nodes p and n is generated , After a low-pass filtering by two inductors L and a capacitor Co results in the output DC voltage upn. This results in direct currents ip and in the filter inductances and sinusoidal input currents ia, ib and ic in the alternating voltage network. A disadvantage of this system lies in the discontinuous input currents i'x, i'y and i'z the switching stage whereby a comparatively strong schaltfrequenter Spannungsrippei on the filter capacitors Cx, y, z arises which disturb the commutation of the input stage 1 and thus cause distortions of the mains currents can.
    An alternative implementation is shown in Fig. 1b wherein here the switching stage 4 in comparison to Fig. 1a consists of two parallel-connected buck converter half-bridges which is connected in parallel with respect to the nodes x, y and z.
    The resulting output terminal pairs pi, P2 and ni, a2 are then brought together by two current-compensated chokes 5 (ICTP and ICTn) on the nodes ρ and n which have analog switching to Fig. 1a switching frequency components. The current-compensated chokes ICTP and ICTn, in conjunction with a suitable control, with the exception of a switching-frequency ripple, avoidance of circulating currents between the parallel-connected buck converter bridges, whereby a uniform distribution of output DC currents ip and in the switch pairs syyl, sxiH and sail, saz2 is ensured. By means of a suitable entangled clocking, that is, for example offset by half a pulse period, the switch swl, sxr., And saili, saz2 can additionally reduce the amplitude of the switching-frequency voltage components between the nodes p and n and double their frequency, which has advantages in terms of the realization of the Ausgangsfilterinduktivitäten 6 results. Likewise results in a doubling of the frequency and reduction of the amplitude of the switching-frequency ripple in the discontinuous input currents i'x, i'y and i'z the buck converter bridges, which reduces the switching frequency Spannungsrippei on the filter capacitors Cx, y, z.
    As shown in Fig. 1b, the Ausgangsfilterinduktivitäten 6 can be realized by two coupled inductors whose winding sense is selected so that the switching frequency common mode component of the potentials at the nodes p and n over the common mode choke Lcm drops and the push-pull proportion on the push-pull choke Ldm drops. This allows a more compact and / or lower-loss implementation of the output filter by implementing a larger inductance value of the common mode choke Lcm for filtering common mode noise currents.
    Compared to Fig. 1a, in the implementation of Fig. 1b lower distortion of the AC mains input currents ia, ib and ic and a low required attenuation of the input filter Lf and Cx, y, zzur observing Störstromvorschriften in AC mains , However, a higher outlay for the implementation of the magnetic components results because a total of four coupled inductors with two windings each are required.
    An object of the invention is to reduce the implementation cost of the output filter in terms of size, load capacity, number and / or cost of the components, with the same functionality.
    The object is achieved by a magnetic throttle and a converter section according to the claims.
    The magnetic choke is thus provided for use in conjunction with a converter bridge, for connection to n phases with in each case m bridge branches per phase, where n is at least two and m is at least two. The reactor has a core with n sub-cores, each of the sub-cores having an initial node and an end node, and m core portions connecting the start node and the end node, and each of the core portions has a winding having a first and a second winding terminal, the second Winding terminals of the windings of the same sub-core form a common winding connection point, and the windings are oriented on the core sections such that in each core section a current flowing through the winding into the common winding connection point generates a magnetic voltage from the starting node to the end node of the sub-core, and the sub-cores toward each other are connected to a magnetic network in that, for i = 1 ..n-1, the end node of the ith subkernel is connected to the start nodes of the (i + 1) th subkernel and the end node of the nth subkernel is connected to the start node of the first Part core is connected.
    A converter section having a first topology constructed thereon has such a choke and an inverter bridge with bridge branches, each bridge branch having a branch center, an upper switch and a lower switch, the upper switch between the branch center and an upper terminal of the bridge Converter bridge and the lower switch is connected between the branch center and a lower terminal of the converter bridge, and each of the first winding terminals of the m core portions of the n partial cores is connected to one of the branch centers of the mn bridge branches.
    A driven according to the same principle but another, second topology exhibiting inverter section has such a choke and a converter bridge with mn / 2Brückenzweigen, each bridge branch a branch center, an upper connection point, a lower connection point, an upper upper switch , a lower upper switch, an upper lower switch and a lower lower switch, wherein the upper upper switch is connected between an upper terminal of the inverter bridge and the upper connection point, the lower upper switch, which may be a passive switch, between the upper And the branch center, the upper lower switch, which may be a passive switch, is connected between the branch center and the lower connection point, the lower lower switch is connected between the lower connection point and a lower connection of the inverter bridge, and each of them Most of the m core sections of the n partial cores are connected to one of the set of upper and lower connection points of the mn / 2 bridge branches.
    A converter constructed thereon has a converter section with the second topology, and another converter bridge for connecting the upper terminal and the lower terminal of the converter bridge with filtered phase terminals of a q-phase polyphase network, and q center-point switches, each of which is connected between one of the filtered phase terminals and the branch center.
    BRIEF DESCRIPTION OF THE FIGURES In the following, the subject matter of the invention will be explained in more detail by means of preferred exemplary embodiments, which are illustrated in the accompanying drawings. Each show schematically:
    Fig. 1 three-phase rectifier circuits with buck converter characteristic according to the prior art, carried out without (a) and with (b) parallel half-bridge branches in the switching stages 2 and 4 respectively.
    Fig. 2 three-phase rectifier circuits with buck converter characteristic according to the invention with parallel half-bridge branches in the switching stage and with a current-compensated inductor 7 which simultaneously suppresses circular currents between the parallel-connected half-bridge branches, as well as common mode currents.
    FIG. 3 Possible realizations of a current-compensated choke for an application according to FIG. 2 with geometrically different cores and winding arrangements.
    4 shows characteristic voltage and current forms when using the invention as a three-phase rectifier with step-down characteristics according to FIG. 2.
    Fig. 5 Possible realization of a control of a three-phase rectifier with buck converter characteristic according to FIG. 2 which allows sinusoidal network currents and a uniform distribution of the DC output current to the parallel-connected half-bridge branches.
    Fig. 6 Possible application of a current-compensated choke in a three-phase rectifier with boost converter characteristic with three phases and with two parallel half-bridge branches.
    MODES FOR CARRYING OUT THE INVENTION With the invention, it is possible to reduce the implementation complexity of the output filter of a three-phase rectifier with step-down characteristic by a combination of more than two windings onto a common multi-core. In particular, as a result, the number of windings required for the same functionality can be reduced because the function of the common mode choke Lcm is integrated into this by a suitable magnetic coupling of the two current-compensated chokes ICTP and ICTn. The resulting circuit is shown in Fig. 2 with the novel coupled current-compensated choke 7 wherein the output filter 8, the common mode choke can be omitted and a pure push-pull choke Ldm, which can be performed coupled or uncoupled, sufficient.
    The rectifier system shown in Fig. 2 is connected by a single- or multi-stage input filter to the three-phase alternating voltage network wherein the last stage of the filter consists of three filter inductances Lf to which a three-phase six-pulse diode bridge is connected whose positive output is connected to the node x of the circuit and whose negative output is connected to the node z of the circuit. In addition, a bipolar blocking and conductive phase selection switch is connected to each of the three filter inductances, the remaining terminals of the three phase selection switches being connected to node y of the circuit. To the nodes x, y and z of the circuit three filter capacitors Cx, y, z are connected which can either form a common star point or can be connected in a delta connection to the nodes x, y and z.
    All the nodes x and y is connected to an upper buck converter bridge and to the nodes z and y is connected to a lower buck converter bridge. The upper buck converter bridge is formed by two parallel upper buck converter half-bridges whose outputs are referred to as pi and p2, each consisting of an active semiconductor switch and a diode. In this case, the semiconductor switch sxpi of the first upper buck converter half-bridge between the nodes x and pi and the semiconductor switch of the second upper buck converter half-bridge is connected between the nodes x and p2 so that a current flow from node x to the nodes Pi and P2 is possible. The diodes are switched so that a current flow from node y to Pi and from node y to P2 is possible. The lower buck converter bridge is formed by two parallel lower buck converter half-bridges whose outputs are referred to as ni and n2, these each consisting of an active semiconductor switch and a diode. In this case, the semiconductor switch s ", the first lower buck converter half-bridge between the nodes z and ni and the semiconductor switch s ,, 2, the second lower buck converter bridge between z and m connected so that ever a current flow from the nodes ni and 02 in the node z is possible and the diodes are switched so that a current flow from the nodes ni and n2 in the node y is possible. Connected to the nodes pi, p2, al and n2 are four windings having an identical number of windings of a current-compensated choke, which are wound around a common multi-limbed core whose embodiment is described below. The two remaining terminals of the windings which are connected to the nodes pi and p2 are connected together to the node P which is connected via an upper output inductance to the positive output terminal upn of the rectifier. The two remaining terminals of the windings which are connected to the nodes ni and 112 are connected together to the node n which is connected via a lower output inductance to the negative output terminal n of the rectifier. The upper and lower output inductance can alternatively also be coupled, in the sense of a push-pull choke on a common core. In addition, an output capacitor can be connected between the output terminals p and n which stabilizes the output DC voltage upn.
    A possible realization of the current-compensated choke with a core of high-permeability ferromagnetic material fa) with four legs and three windows is shown in FIG. 3a. Each of the four core legs carries one of the windings. The winding sense of the four windings is chosen so that cancel the DC components of the winding currents ip1, ip2, ini and in2 in each of the three core windows. This avoids saturation of the core material independent of the DC output current and avoids the need for air gaps in the core legs, allowing the implementation of high inductance values typically required for sufficient suppression of common mode currents in the AC grid. However, it is possible to insert an air gap in each of the four core limbs, which are designated in FIG. 3 a as δ1, δ2, δ3 and δ4, whereby the inductance values of the current-compensated choke can be reduced while the number of turns is unchanged.
    Due to the planar arrangement of the windings in a realization as described above results in a consequence of stray fields a different coupling between different pairs of windings. This can be avoided by using a core in which the 12 edges of a cube or cuboid are made of high permeability ferromagnetic core material and each lead to a winding of the current-compensated inductor around four parallel edges, the winding sense again being chosen so that in each side face of the Cube compensate for the currents passing through them. It can be distinguished between two possible arrangements of the windings because those two windings which are connected to the nodes Pi and p2 of the circuit either on immediately adjacent edges (Fig. 3b) or on diagonally opposite edges (Fig. 3c) can be wound , For the same permeability and dimensions of the core, for a directly adjacent arrangement according to FIG. 3b, a low common-mode inductance and a greater inductance for suppression of circulating currents between the parallel-connected buck converter half-bridges compared with a diagonally opposite arrangement of the pi, p2 windings. Again, as with a planar array, air gaps may be inserted to reduce the inductance values of the common mode choke while maintaining the number of turns, either inserting one air gap into each of the coil-carrying core legs, or inserting one air gap into each of eight coil-carrying core legs can.
    When considering the topology of the magnetic circuit, each of the legs of the core carrying a winding corresponds to a core portion. A number of m, in this case each of two, core sections forms a sub-core t-ι, t2. Each sub-kernel t-1, t2 is assigned to one of n phases, in this case one of two phases. Each subkernel has an initial node and an end node which are connected by the m core sections. In this case, a first common node ki is equal to the starting node of the first sub-kernel L and the end node of the second sub-kernel t2, and a second common node k2 is equal to the starting node of the second sub-kernel t2 and the end node of the first sub-kernel L. In Figs. 3b and 3c, the upper quadrangle of legs without windings forms the first common node and the lower quadrant forms the second common node. In the variant of a throttle 7 explained below in connection with FIG. 6, there are three partial cores, each with two core sections, which are connected to one another via the nodes k-i, k2, k3 and form a circle.
    Characteristic voltage and current waveforms in chokes according to FIG. 2 and FIG. 3 are shown in Fig. 4 as a function of the phase angle ωί the three-phase AC voltage. In Fig. 4a, the voltages of the nodes pi, p2, ni and n2 are shown against the neutral point N of the AC voltage network. This results in the voltages uw, p1, uw, p2, uw, ni and uw, n2 shown in FIGS. 4b and 4c at the terminals of the current-compensated choke as well as the currents ip1, ip2, i "i and i" 2 in the windings the current-compensated choke. The voltage uLdm shown in FIG. 4d thus remains at the windings of the push-pull inductor Ldm of the rectifier according to FIG. 2 and leads to an output current ip or in. Both uLdm and ip or in have in this case compared to the voltages "r> i," m and as compared to the winding voltages uw, p1, uw, p2, uw, ni and uw, n2 twice the frequency.
    The regulation of the rectifier is preferably carried out with two or four loops wherein the control of the switch, for example, as shown in Fig. 5, can be done by means of pulse width modulation (PWM) or with tolerance band control. In this case, an external output voltage regulator Gu compares the measured output DC voltage upn with a reference value and determines therefrom an output current nominal value to which at most the current measured in the supply line of the load can be added as a precontrol.
    From c, the current ί41 "is subtracted, which is calculated as the sum of the four measured winding currents ip1, ip2, ini and in2 of the current-compensated choke divided by two. The resulting error signal is fed to a subordinate current regulator Gdm whose output value the measured output DC voltage upn can be added in the sense of a precontrol. By means of a division by 1.5 times the amplitude of the input phase alternating voltage results in the modulation index M of the rectifier which is multiplied by two sectionwise sinusoidal signals sp and sn, which have an amplitude of 1 multiplied. This results in the duty cycles dp and dn of the upper (p) and lower (n) buck converter which the pulse width modulators (PWM in Fig. 5) for the switch sipb sxp2 and s, "; sJz2 be supplied. In order to obtain AC-side input currents ia, ib, ic which are in phase with the associated mains voltages, the signal sp can be obtained from the voltage ux between the node x and the neutral point N of the three-phase AC network by measuring the measured voltage ux by the amplitude ύ the mains phase voltage is divided. Furthermore, the signal sn is formed by dividing the voltage uz between the node z and the neutral point N of the three-phase AC network by C , the sign of the voltage must be swept because the potential of z is below the neutral point, but sn must be positive ,
    In order to ensure a uniform distribution of the currents in the windings of the current-compensated throttle in all operating cases, in particular during load changes, two additional current control loops can be added. For this purpose, the difference between the two currents iP2 and ip1 measured in the p-side windings of the current-compensated inductor is first calculated and fed to a controller Gim, p whose output signal is divided by the voltage Uxy between the nodes x and y. The resulting signal represents a differential duty cycle which is added to or subtracted from dp to produce two separate duty cycles dp1 and dp2, which are fed to two separate pulse width modulators for the switches sxpl and sIiH. In addition, the difference of the currents ini and i "2 is fed to a regulator Gim, n whose output signal is divided by the voltage uyz between the nodes y and z. The resulting differential duty cycle is then added to dn, or subtracted from this, whereby the duty cycles dni and d "2 result which are the pulse width modulators for sM and s, M supplied.
    In order to achieve the desired reduction of the switching-frequency Spannungsrippeis on the filter capacitors Cx, y, the pulse width modulators of the switch sx [11 and sxp2, as well as those of the switches s "zl and sa2 are controlled by offset by 180 ° carrier signals. Using the same carrier signal for s, and for sxfI results in a larger differential current ripple and at the same time a smaller common mode ripple compared to a timing in which the carrier signals of the pulse width modulators are out of phase sM1 and 90 ° out of s! Te2.
    The circuit described above allows only a unidirectional power flow from the three-phase AC voltage network to the DC output terminals due to the diodes used. An extension to bidirectional power flow is possible if in the circuit all diodes are replaced or supplemented by additional active switches, the additional switches always being turned on as long as the diodes would conduct in the original circuit. This makes it possible to reverse the direction of the DC output current, thereby establishing a power flow from the DC voltage terminals p and n to the three-phase AC mains.
    The above-described concept of a current-compensated choke which simultaneously allows the suppression and control of circular currents between parallel bridge branches and the filtering of common mode components is not limited to three-phase equalizer system with buck converter characteristic but can for n-phase DC and inverter systems with m parallel bridge branches are generalized per phase. For this purpose, one of the windings associated with one phase is mounted on one edge of an n-cornered, polygonal core, with a total of m such polygons being formed. These polygonal cores are then arranged in parallel so that the windings associated with one phase face each other, and the vertices of the polygonal cores are connected to pieces of core material orthogonally attached to the polygonal planes to achieve magnetic coupling. The winding sense of all windings is chosen so that in all closed loops of core material pass through the currents, neglecting switching frequency ripple, add to zero. Furthermore, air gaps can be inserted to reduce the inductance values of the current-compensated inductor with an unchanged number of turns, wherein one air gap can be inserted in each of the coil-carrying core legs and / or one air gap can be inserted into the non-winding core legs. A configuration for three phases and two parallel bridge branches per phase is shown in FIG.
    权利要求:
    Claims (3)
    [1]
    claims
    1. Magnetic choke (7) for use in conjunction with a converter bridge for connection to n phases with m bridge branches per phase, where n is at least two and m is at least two, characterized in that the choke (7) has a core with n partial cores (t-1, t2), each of the sub-cores (t-1, t2) each having an initial node and an end node and m core sections connecting the start node and the end node, each of the core sections having a winding with a first (pi, p2, Hi, n2; i'UìÈjìi and a second winding terminal <p, ö), the second winding terminals of the windings of the same sub-core form a common winding terminal point (p, n), and the windings on the core portions are oriented so that in each Core portion of a current flowing through the winding in the common winding connection point generates a magnetic voltage from the starting node to the end node of the sub-core, and the Te ilkerne (t-ι, t2) are connected to each other to form a magnetic network by for i = 1 ..n-1 each of the end node of the ith subkernel is connected to the initial node of the (i + 1) th subkernel and the end node of the nth subkernel is connected to the initial node of the first subkernel.
    [2]
    An inverter section comprising a choke (7) according to claim 1 and an inverter bridge having mn bridge branches, each bridge branch having a branch center, an upper switch and a lower switch, the upper switch between the branch center and an upper terminal (p) of Converter bridge and the lower switch is connected between the branch center and a lower terminal (n) of the converter bridge, and each of the first winding terminals (ai, bi, ci, a2, 52, 02) of the m core portions of the n partial cores is connected to one of the branch centers of mn bridge branches is connected. A converter section comprising a choke (7) according to claim 1 and an unirror bridge having mn / 2 bridge branches, each bridge branch having a branch center (y), an upper terminal, a lower terminal, an upper upper switch w, a lower upper switch , an upper lower switch and a lower lower snzi switch, wherein the upper upper switch <s "pd is connected between an upper terminal (x) of the inverter bridge and the upper terminal point, the lower upper switch being a passive switch may be connected between the upper connection point and the branch center (y), the upper lower switch, which may be a passive switch, is connected between the branch center (y) and the lower connection point, the lower lower switch (sàzi) between the lower ones Connection point and a lower terminal (z) of the converter bridge is connected, and each of the first winding terminals (pi, p2 , ni, n2) of the m core sections of the n sub-cores is connected to one of the set of upper and lower connection points of the mn / 2 bridge branches.
    [4]
    4. converter, comprising a converter section according to claim 3 and a further converter bridge for connecting the upper terminal (x) and the lower terminal (z) of the converter bridge with filtered phase terminals iw) a polyphase network with q phases, and with q center switches (säVä , scyc), each of which is connected between one of the filtered phase terminals σχυ and the branch center.
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    同族专利:
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    CH713573B1|2021-01-29|
    引用文献:
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    法律状态:
    2018-11-15| PCAR| Change of the address of the representative|Free format text: NEW ADDRESS: POSTFACH, 8032 ZUERICH (CH) |
    优先权:
    申请号 | 申请日 | 专利标题
    CH00318/17A|CH713573B1|2017-03-15|2017-03-15|Magnetic choke, converter section and converter.|CH00318/17A| CH713573B1|2017-03-15|2017-03-15|Magnetic choke, converter section and converter.|
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