DE102005005688A1 - Filter for backfeedable rectifier, has capacitor connected at each connection point of winding portions, which are arranged on common core in such a manner that their ampere turns mutually compensate during flow - Google Patents

Abstract

The filter has an inductor (22) with two winding portions, which are electrically connected with each other in a row. The winding portions (24) are arranged on a common core (28) in such a manner that their ampere turns mutually compensate during a flow, where the common core consists of a magnetic material. A capacitor (20) is connected at each connection point (30) of the winding portions.

Description

The The invention relates to a filter for one having a network commutating reactor provided regenerative power converter with fundamental frequency clocking of a voltage source inverter, each consisting of a choke and a capacitor per mains supply.

In the 1 is a voltage source inverter 2 with a regenerative converter 4 shown with fundamental frequency clocking. This voltage source inverter 2 has load side a self-commutated pulse converter 6 on, at whose outputs U, V, W a load 8th , For example, an induction motor is connected. DC side, the two power converters 4 and 6 by means of a DC voltage intermediate circuit 10 connected with each other. This DC voltage intermediate circuit 10 has as intermediate _circuit capacitor C _{DC to} an electrolytic capacitor. On the supply side is the regenerative converter 4 with fundamental frequency timing by means of a network commutation reactor 12 _{R, S, T} per power line R, S, T with a filter 14 linked, the input side with a feeding network 16 connected is.

The filter 14 , which is also referred to as a line filter or EMC filter, has per reactor phase R, S, T a throttle 18 _{R, S, T} and a capacitor 20 _{R, S, T} on. In this embodiment, these are capacitors 20 _{R, S, T} electrically connected in delta. These capacitors 20 _{R, S, T} can also be electrically switched to star. Through the throttles used 18 _{R, S, T} and capacitors 20 _{R, S, T} In general, this filter is also referred to as LC low-pass filter.

The regenerative converter 4 with fundamental frequency clocking has per phase R, S, T two electrically connected in series diodes D1, D2; D3, D4 and D5, D6, which form a six-pulse diode rectifier. Electrically parallel to these diodes D1 to D6 is in each case a turn-off semiconductor switch T1 to T6, in particular an insulated gate bipolar transistor (IGBT), connected. These turn-off semiconductor switches T1 to T6 are respectively turned on precisely when the associated diode D1 to D6 is conductive. Thus, control signals for these turn-off semiconductor switches T1 to T6 are generated such that the natural commutation of the diodes D1 to D6 a corresponding turn-off semiconductor switch T1 or T2 or T3 or T4 or T5 or T6 is turned on or off. These natural commutation times denote times at which the existing concatenated voltages u _RS , u _ST and u _{TR are} each zero. A possible drive circuit for such a regenerative power converter 4 with fundamental frequency timing is the DE 199 13 634 A1 refer to.

In such regenerative power converters 4 , which are clocked at mains frequency, therefore the term basic frequency clocking occur in regenerative operation during the shutdown steep changes in current. These steep current changes stimulate the network-side filter. Once the current has become zero, the filter oscillates 14 free with the mains inductance L _{N of} the supply network 16 , This leads to undesirable balancing processes in the mains voltage u _RST the other consumers of this feeding network 16 to disturb.

To prevent this, the filter could 14 be sufficiently damped. This requires resistors, which, however, cause losses and the size of the filter 14 enlarge. In addition, the filtering effect suffers from the use of damping resistors.

Another possibility is the inductance of the network commutation chokes 12 _{R, S, T} so large that the current gradient and thus the filter excitation is low. This measure also causes an increase in the size of the throttles 12 _{R, S, T} which also cause more costs.

Because the filter 14 free with the mains inductance L _{N of} the supply network 16 can swing, the use of a voltage source inverter 2 with a regenerative converter 4 with basic frequency clocking on feeding networks 16 be limited, which have a high short-circuit power compared to the inverter performance. A dining network 16 with high short-circuit power has a low impedance. This is only a limited application of such a converter 2 possible, which is a difficult marketing of this inverter 2 entails.

Another way to get the excitation of a filter 14 to prevent, is on such a line filter 14 to renounce. This measure also causes the voltage source inverter 2 with a regenerative converter 4 With basic frequency clocking can be used only limited, making this inverter is also difficult to market.

Of the Invention is now based on the object, a filter for a regenerative power converter with fundamental frequency clocking, with which the excited vibrations no longer visible in the mains voltage.

These Task is according to the invention with the Characteristics of claim 1 solved.

By the embodiment of the invention Throttling the filter, the floodings of the winding parts lift for low Frequencies on and for High frequencies reduce the effect of the choke on the stray inductances two winding parts. These leakage inductances are the network inductance and the Network commutating reactor of the regenerative power converter electrically connected in series. By lifting the flooding the winding parts acts at low frequencies only the main inductance.

There at low frequencies the core is not from the fundamental current is loaded, the core cross-section can be chosen very small. To big inductors To realize an air gap is not required.

With Help this throttle according to the invention is obtained Filter for a regenerative power converter with fundamental frequency clocking of a voltage source inverter, with the unwanted transients in the mains voltage as a result of an excited oscillation no longer occur. Disadvantages such as size, costs, Losses and bad filter effect are no longer necessary to be taken.

advantageous Embodiments of the filter can be found in the dependent claims 2 to 6.

to further explanation The invention is referred to the drawing, in which several embodiments a filter according to the invention are illustrated schematically.

1 shows a known voltage source inverter arrangement with a regenerative converter with fundamental frequency timing and a line filter,

2 shows a single-phase filter according to the invention, wherein the

3 an equivalent circuit diagram of the filter according to the invention 2 for low frequencies and the

4 an equivalent circuit diagram of the filter according to the invention 2 for high frequencies show in the

5 a first embodiment of a three-phase filter according to the invention is illustrated, wherein in the 6 a second embodiment of a three-phase filter according to the invention and in the

7 a third embodiment of a three-phase filter according to the invention are shown, the

8th shows a voltage source inverter assembly after 1 with a three-phase filter according to the invention according to 5 , and the

9 shows a section through a throttle according to the invention, wherein in the

10 a side view and in the

11 a plan view of a throttle according to the invention are shown.

The filter according to the invention, whose basic principle in the 2 shown in more detail, has a throttle 22 on, consisting of two electrically connected in series winding parts 24 and 26 consists. These two winding parts 24 and 26 are on a common core 28 arranged in this illustration by the over both winding parts 24 and 26 extending double line is clarified. Both winding parts are 24 and 26 so on the common core 28 arranged that if both winding parts 24 and 26 to be traversed by a stream, whose flux cancel each other out. This inventive arrangement of the two winding parts 24 and 26 is through the points on the winding parts 24 and 26 recognizable. At the connection point 30 the two winding parts 24 and 26 is a capacitor 20 of the filter 14 connected. The core material chosen is a magnetic material whose cutoff frequency is low compared to the predetermined cutoff frequency of the filter 14 is. As a material, for example, iron sheet is used. By this inventive design of the throttle 22 of the filter 14 you get two different effects of this throttle 22 ,

For low frequencies, the flux of the winding parts lift 24 and 26 on when both winding parts 24 and 26 to be traversed by the same stream. An equivalent circuit diagram of the throttle according to the invention 22 for low frequencies is in the 3 shown. According to this substitute circuit diagram acts on the throttle according to the invention 22 only the main inductance L _h . Because the core 28 is not burdened by the fundamental current, the core cross-section can be chosen very small. To have a large inductance of the choke 20 To obtain an air gap is not required.

For high frequencies (> 10kHz) this main inductance L _h disappears because of the core 28 the frequency can not be transmitted. The effect of the throttle according to the invention 22 reduces to the leakage inductances L _σ24 and L _{σ26 of} the two winding _parts 24 and 26 , An equivalent circuit diagram of the throttle according to the invention 22 for high frequencies in the 4 shown in more detail. These leakage inductances L _σ24 and L _σ26 are with the network inductance L _N and the network commutation reactor 12 of the regenerative converter 4 with fundamental frequency clocking electrically connected in series. These leakage inductances L _σ24 and L _σ26 are opposite to the network inductance L _N and the network commutation reactor 12 so small that they can be neglected.

As described at the beginning, steep current changes occur during the switch-off operation during the switch-off operation. When the current on the power converter side has become zero, the capacitor oscillates 20 with the net 16 , Because this oscillation is relatively low (<10 kHz), the throttle according to the invention acts 22 now with its main inductance L _h . Because this is greater than the line inductance L _N , the oscillation in the mains voltage is no longer visible (inductive voltage divider).

With this throttle according to the invention 22 you get a filter 14 for a regenerative power converter 4 with fundamental frequency clocking, with the unwanted balancing operations in the mains voltage of the supplying network 16 be prevented.

In the 5 . 6 and 7 are each versions of a three-phase filter 32 shown. These three-phase embodiments each consist of three single-phase filters according to 2 , wherein in the embodiment of 5 the capacitors 20 _{R, S, T} electrically in triangle and in the embodiments according to the 6 and 7 are each switched to star. The difference between the two embodiments according to the 6 and 7 is that the star point 34 in the 6 is free and in the 7 by means of another capacitor 36 is linked to a reference potential M (ground potential). Through this additional capacitor 36 Interference currents can also flow via the reference potential M. As a result, asymmetrical interference currents are compensated. The two embodiments according to the 5 and 6 are equivalent.

In the 8th is the voltage source inverter arrangement according to 1 illustrates where the filter 14 by a filter according to the invention 32 according to 5 is exchanged. By the use of this filter according to the invention 32 Become undesirable balancing operations in the mains voltages u _{R, S, T of} the feeding network 16 prevented.

In the construction of the throttle 22 make sure that the main inductance L _{h of} the choke 22 just over the core 28 is formed. A coupling proportion over air would not disappear at high frequencies and thus the filtering effect of the capacitor 20 affect. If conventional construction techniques for chokes do not adequately ensure this, the winding parts must 24 and 26 be arranged so that the coupling without nuclear material has a different sign than that with core 28 ,

In the 9 is a section through such a throttle 22 shown. The 10 shows a side view of a possible structure of the basic principle of the throttle structure with inverse air coupling according to 9 , An associated top view is in the 11 shown in more detail.

Claims (6)

Filter ( 32 ) for one with a network commutation reactor ( 12 ) provided with regenerative power converter ( 4 ) with fundamental frequency clocking of a voltage source inverter ( 2 ), each consisting of a throttle ( 32 _{R, S, T} ) and a capacitor ( 20 _{R, S, T} ) per power line (R, S, T), with each throttle ( 22 _{R, S, T} ) two winding parts ( 24 _{R, S, T,} 26 _{R, S, T} ), which are each electrically connected in series and so on a common core ( 28 _{R, S, T} ) are arranged so that their fluxes cancel each other in a current, and wherein at each connection point ( 30 _{R, S, T} ) of two winding parts ( 24 _{R, S, T} . 26 _{R, S, T} ) a capacitor ( 20 _{R, S, T} ) connected. Filter ( 32 ) according to claim 1, characterized in that the core ( 28 ) consists of a magnetic material whose cutoff frequency to the predetermined cut-off frequency of the filter ( 32 ) is low. Filter ( 32 ) according to one of claims 1 or 2, characterized in that the core ( 28 ) consists of iron sheets. Filter ( 32 ) according to one of the preceding claims, characterized in that the capacitors ( 20 _{R, S, T} ) are connected in delta. Filter ( 32 ) according to one of claims 1 to 3, characterized in that the capacitors ( 20 _{R, S, T} ) are in star. Filter ( 32 ) according to claim 5, characterized in that a star point ( 34 ) of the star connected capacitors ( 20 _{R, S, T} ) by means of a further capacitor ( 36 ) is linked to a reference potential (M).