DE102004034944A1 - Inverter with current rise limiter has capacitive dc circuit with two current limiting networks and bi-directional power semiconductor switches in parallel with loss limiting circuit - Google Patents

Abstract

Inverter with current rise limiter comprises a two series capacitance dc circuit (1) with two current-limiting networks (5,10) and four bidirectional controllable power semiconductor switches (S1-4) and two unidirectional switches (S5,6). A parallel resistance (15) and capacitance (16) circuit limits switch-off loss.

Description

technical area

The The invention relates to the field of power electronics. she is based on a converter circuit according to the preamble of claim 1.

Power semiconductor switches, in particular integrated thyristors with commutated drive electrode (IGCT), are currently being propagated in inverter technology and in particular In converter circuits for switching three voltage levels used. Such a converter circuit for switching three Stress levels is in "Characterization of IGCTs for Series Connected Operation, Conference Record of Annual Meeting of the IEEE Industry Applications Society, 2000, October Inverter circuit by a two series-connected capacitors formed DC voltage circuit, wherein the DC voltage circuit a first main terminal and a second main terminal and one through the two adjacent and interconnected capacitors having formed partial connection. The capacitance value of the two capacitors is usually the same size. Between the first main connection and the second main connection is a DC voltage, wherein between the first main terminal and the partial connection, i. thus half of the one condenser DC voltage is present and between the partial connection and the second main connection, i.e. consequently also half the DC voltage at the other capacitor at.

Further the converter circuit has a first current increase limiting network on, with an inductance and a resistor of the first current rise limit network connected to the first main terminal, a capacity of the first Current increase limit network with the resistance and with the Partial connection is connected and a diode of the first current increase limiting network with the inductance and connected to the connection point of the resistor to the capacitor is. Furthermore, the converter circuit has a second current increase limiting network on, with an inductance and a resistor of the second current increase limiting network with connected to the second main terminal, a capacity of the second Current increase limit network with the resistance and with the Partial connection is connected and a diode of the second current increase limiting network with the inductance and connected to the connection point of the resistor to the capacitor is. About that In addition, a first, second, third and fourth can be controlled bidirectional power semiconductor switch and a fifth and sixth non-controllable unidirectional power semiconductor switch provided, wherein the first, second, third and fourth power semiconductor switch are connected in series and the first power semiconductor switch with the connection point of the inductance and the diode of the first Current increase limit network and the fourth power semiconductor switch with the connection point of the inductance and the diode of the second Current increase limiting network is connected. The fifth and sixth power semiconductor switch is connected in series, wherein the connection point of the fifth Power semiconductor switch with the sixth power semiconductor switch connected to the sub-terminal, the fifth power semiconductor switch to the connection point of the first power semiconductor switch is connected to the second power semiconductor switch and the sixth power semiconductor switch with the connection point of third power semiconductor switch with the fourth power semiconductor switch connected is.

To the first, second, third and fourth controllable bidirectional Power semiconductor switch is in each case a series circuit of a Resistor with a capacity connected in parallel, the capacity having a value of typically 500nF and the resistor has a value typically 1Ohm. The respective series connection of the resistor with the capacity with the mentioned above values moderate Design serves to achieve a balanced stress distribution the associated Power semiconductor switch at switching state transitions, i. at the transition from the on state to the off state or off State to turn on state, reach.

Problematic in a converter circuit according to "Characterization of IGCTs for Series Connected Operation, Conference Record of the Annual Meeting of IEEE Industry Applications Society, 2000, October "is that through the described value-based interpretation of resistance and capacity the series circuit at the shutdown of the associated power semiconductor switch a high voltage increase occurs at the same time as high current, resulting in very high turn-off losses and dynamic overshoots of the electric field in the power semiconductor switch leads. Such increased Shutdown losses and field strengths but at the respective power semiconductor switch can damage this or even destroy it.

presentation the invention

task The invention is therefore an inverter circuit of the above mentioned type such that the turn-off minimized at power semiconductor switches of the converter circuit can be. This object is solved by the features of claim 1. In the dependent claims advantageous developments of the invention are given.

The invention Inverter circuit comprises one connected in series by two Capacitors formed DC circuit, the DC circuit a first main terminal and a second main terminal and one through the two adjacent and interconnected capacitors having formed partial connection. Further, a first current rise limit network provided, wherein an inductance and a resistance of the first Electricity increase network with the first main connection connected, a capacity of the first current increase boundary network with the resistor and connected to the sub-terminal and a diode of the first one Current increase limit network with inductance and with connected to the connection point of the resistor with the capacity is. Furthermore, the inventive converter circuit has a second current increase limiting network, wherein an inductance and a Resistance of the second current rise limit network with the second main terminal is connected, a capacity of the second Current increase limit network with the resistance and with the Partial connection is connected and a diode of the second current increase limiting network with the inductance and connected to the connection point of the resistor to the capacitor is. About that In addition, a first, second, third and fourth can be controlled bidirectional power semiconductor switch and a fifth and sixth non-controllable unidirectional power semiconductor switch provided, wherein the first, second, third and fourth power semiconductor switch are connected in series and the first power semiconductor switch with the connection point of the inductance and the diode of the first Current increase limit network and the fourth power semiconductor switch with the connection point of the inductance and the diode of the second Current increase limiting network is connected. The fifth and sixth power semiconductor switch is connected in series, wherein the connection point of the fifth Power semiconductor switch with the sixth power semiconductor switch connected to the sub-terminal, the fifth power semiconductor switch to the connection point of the first power semiconductor switch is connected to the second power semiconductor switch and the sixth power semiconductor switch with the connection point of third power semiconductor switch connected to the fourth power semiconductor switch is. According to the invention is the first, second, third and fourth controllable bidirectional Power semiconductor switch in each case a series connection of a resistor with a capacity connected in parallel, the capacity has a value greater than 1μF and the Resistance has a value of the order of magnitude between 2Ohm and 4Ohm.

Advantageous it is by means of the inventive respective series connection of the resistor with the capacity and their according to the invention value interpretation possible, the voltage increase during the shutdown of the associated power semiconductor switch limit, resulting in a significant reduction in turn-off as well as to a sig nificant increase of the maximum turn-off current of the power semiconductor switch leads. The respective power semiconductor switch can thereby largely from damage or destruction protected become. additionally allows the voltage limit is a significant increase in the inverter power.

These and other objects, advantages, and features of the present invention will be more preferred from the detailed description below embodiments the invention in conjunction with the drawing obvious.

Short description the drawings

It demonstrate:

1 a first embodiment of an inventive converter circuit and

2 A second embodiment of the inventive converter circuit

The used in the drawings and their meaning are summarized in the list of reference numerals. Basically in the figures, like parts with the same reference numerals. The described embodiments are exemplary for the subject invention and have no limiting effect.

Ways to execute the invention

In 1 a first embodiment of the inventive converter circuit is shown. The converter circuit according to 1 includes a capacitor connected in series by two capacitors Deten DC circuit 1 , where the DC voltage circuit 1 a first main line 2 and a second main line 3 and a partial terminal formed by the two adjacent and connected capacitors 4 having. Furthermore, in the inventive converter circuit according to 1 a first electricity upgrade border network 5 provided according to 1 an inductance 6 and a resistance 7 the first electricity boarder network 5 with the first main line 2 connected, a capacity 8th the first electricity boarder network 5 with the resistance 7 and with the partial connection 4 is connected and a diode 9 the first electricity boarder network 5 with the inductance 6 and with the connection point of the resistor 7 with the capacity 8th connected is. Furthermore, according to 2 a second current increase limit network 10 provided, wherein an inductance 11 and a resistance 12 of the second current increase limiting network 10 with the second main connection 3 connected, a capacity 13 of the second current increase limiting network 10 with the resistance 12 and with the partial connection 4 is connected and a diode 14 of the second current increase limiting network 10 with the inductance 11 and with the connection point of the resistor 12 with the capacity 13 connected is. In addition, the inventive converter circuit has a first, second, third and fourth controllable bidirectional power semiconductor switch S1, S2, S3, S4 and a fifth and sixth non-controllable unidirectional power semiconductor switch S5, S6. The fifth and sixth power semiconductor switches S5, S6 is a non-controllable unidirectional power semiconductor switch, each formed by a diode. Thus, the fifth and sixth power semiconductor switches S5 and S6 form a passive clamp switching group. Preferably, the first, second, third and fourth controllable bidirectional power semiconductor switches S1, S2, S3, S4 are each formed by an integrated thyristor with commutated drive electrode and by a diode connected in anti-parallel to the thyristor. Furthermore, the fifth and sixth non-controllable unidirectional power semiconductor switches S5, S6 are preferably each formed by a diode.

According to 1 the first, second, third and fourth power semiconductor switches S1, S2, S3, S4 are connected in series and the first power semiconductor switch S1 is connected to the connection point of the inductance 6 and the diode 9 the first electricity boarder network 5 and the fourth power semiconductor switch S4 with the connection point of the inductance 11 and the diode 14 of the second current increase limiting network 10 connected. Further, the fifth and sixth power semiconductor switches S5, S6 are connected in series, the connection point of the fifth power semiconductor switch S5 with the sixth power semiconductor switch S6 with the sub-terminal 4 the fifth power semiconductor switch S6 is connected to the connection point of the first power semiconductor switch S1 to the two th power semiconductor switch S2 and the sixth power semiconductor switch S6 connected to the connection point of the third power semiconductor switch S3 to the fourth power semiconductor switch S4. According to the invention, the first, second, third and fourth controllable bidirectional power semiconductor switches S1, S2, S3, S4 each have a series connection of a resistor 15 with a capacity 16 connected in parallel, with the capacity 16 a value of the order of magnitude greater than 1μF and the resistance 15 has a value in the order of between 2Ohm and 4Ohms. Preferably, the fifth and sixth power semiconductor switches S5, S6 are each optionally a series circuit of a resistor 15 with a capacity 16 connected in parallel, with the capacity 16 a value of the order of magnitude greater than 1μF and the resistance 15 has a value in the order of between 2Ohm and 4Ohms. The series connection of the resistor 15 with the capacity 16 and their value-based design according to the invention brings about a current into the capacitance during the switch-off process of the associated power semiconductor switch S1, S2, S3, S4, S5, S6 16 is driven, so that the voltage increase is limited to the associated power semiconductor switch S1, S2, S3, S4, S5, S6. This relieves the associated power semiconductor switch S1, S2, S3, S4, S5, S6 in two respects. On the one hand, the maximum switching power is reduced in the power semiconductor switch S1, S2, S3, S4, S5, S6, this maximum switching power correlated with the maximum turn-off current. On the other hand, the switching losses are reduced if during the voltage increase, a smaller part of the current in the power semiconductor switch S1, S2, S3, S4, S5, S6 flows itself. This reduction of the switching losses is a prerequisite for being able to use the increased turn-off capability to increase the converter power, without the operating temperature of the power semiconductor switch having to be increased or the switching frequency of the converter circuit having to be reduced. Overall, the limitation of the voltage increase advantageously leads to a significant reduction in the turn-off losses and to a significant increase in the maximum turn-off current at the respective power semiconductor switches S1, S2, S3, S4, S5, S6, whereby they can be largely protected from damage or destruction.

Optional is parallel to each resistor 15 the associated series connection of the resistor 15 with the capacity 16 a diode connected, whereby losses can be further reduced.

According to 1 the converter circuit according to the invention has a controllable short-circuit element 17 on which with the partial connection 4 and connected to the connection point of the second to the third power semiconductor switch S2, S3. The controllable short-circuit element 17 Thus, it is very easy to integrate into the existing network of power semiconductor switches S1, S2, S3, S4, S5, S6 of the converter circuit, so that space can advantageously be saved. The controllable short-circuit element 17 is used in a short circuit in one or more of the controllable power semiconductor switches S1, S2, S3, S4, S5, S6 to that caused by the short-circuiting short-circuit current from the capacitors of the DC voltage circuit 1 only very briefly over the short-circuited power semiconductor switches S1, S2, S3, S4, S5, S6 and then via the short-circuit element 17 for partial connection 4 is steered so that the or the short-circuited power semiconductor switches S1, S2, S3, S4, S5, S6 not further damaged, loaded or destroyed. The controllable short-circuit element 17 according to 1 Moreover, in the event of a short circuit at one or more phases of an electrical alternating voltage network connected to the converter circuit, a short-circuit current resulting from the short circuits from the phases is not or only with a small amplitude via the power semiconductor switches S1, S2, S3, S4, S5, S6 , in particular via the diodes of the power semiconductor switches S1, S2, S3, S4, S5, S6 flows, so that the power semiconductor switches S1, S2, S3, S4, S5, S6 no longer or not at all damaged, loaded or destroyed. Such a short-circuit current or fault current is in this case via the short-circuit element 17 for partial connection 4 directed. The short-circuit element 17 is then activated when a short-circuit current is detected by means of a detection device.

In 2 a second embodiment of the inventive converter circuit is shown. The second embodiment according to 2 differs from the first embodiment described in detail above 1 in that a controllable short-circuit element is provided which has an inductance 20 is connected to the connection point of the second with the third power semiconductor switch S2, S3, wherein a series connection of a resistor 18 with a capacity 19 parallel to the controllable short-circuit element 17 is switched. The inductance 20 and series connection of the resistor 18 with the capacity 19 are optional. The interconnection of the inductance described above 20 , the resistance 18 and the capacity 19 when switching on the short-circuit element 17 a current increase limiting device, ie the current increase when switching is limited, and when switching off the short-circuit element 17 a Spannungsanstiegsbegrenzungseinrichtung, ie the voltage increase during shutdown is limited, is. This controllable short-circuit element 17 according to 2 is used in the event of a short circuit at one or more phases of an electrical alternating voltage network connected to the converter circuit that a short circuit current caused by the short circuit from the phases is not or only with a small amplitude via the power semiconductor switches S1, S2, S3, S4, S5, S6, in particular via the diodes of the power semiconductor switch S1, S2, S3, S4, S5, S6 flows, so that the power semiconductor switches S1, S2, S3, S4, S5, S6 not further or not damaged, charged or destroyed. The short-circuit element 17 is then controlled when a short circuit current is detected by means of a detection device, wherein the controllable short-circuit element 17 then each with the shorting element 18 short circuits connected phases.

The short-circuit element 17 to 1 and 2 is formed with advantage of two antiparallel connected controllable power semiconductors with respective pressure contact, such as disc thyristors or GTOs. The respective controllable power semiconductor switch of the controllable short-circuit element 17 but can also be formed by an integrated thyristor with commutated drive electrode or by a triac.

According to 1 and 2 is a balancing resistor parallel to the series connection of the fifth and sixth power semiconductor switch S5, S6 21 connected. The balancing resistance 21 is used to advantage, for example, at a shutdown of all power semiconductor switches S1, S2, S3, S4, S5, S6 to achieve a nearly symmetrical voltage distribution across the power semiconductor switch S1, S2, S3, S4, S5, S6 and thus individual power semiconductor switch S1, S2, S3, S4, S5, S6 to protect against excessive voltages.

1

DC circuit

2

first main Line

3

second main Line

4

part connection

5

first Current rise limiting network

6

Inductance of the first Current rise limiting network

7

resistance the first electricity boarder network

8th

Capacity of the first Current rise limiting network

9

diode the first electricity boarder network

10

second Current rise limiting network

11

Inductance of the second Current rise limiting network

12

resistance of the second current increase limiting network

13

Capacity of the second Current rise limiting network

14

diode of the second current increase limiting network

15

resistance

16

capacity

17

controllable Short-circuit element

18

resistance

19

capacity

20

inductance

21

Symmeterisation resistance

S1

first Power semiconductor switch

S2

second Power semiconductor switch

S3

third Power semiconductor switch

S4

fourth Power semiconductor switch

S5

fifth power semiconductor switch

S6

sixth Power semiconductor switch

Claims (8)

Inverter circuit with a DC voltage circuit formed by two capacitors connected in series ( 1 ), where the DC voltage circuit ( 1 ) a first main connection ( 2 ) and a second main connection ( 3 ) and a partial connection formed by the two adjacent and interconnected capacitors ( 4 ), with a first current increase limiting network ( 5 ), wherein an inductance ( 6 ) and a resistor ( 7 ) of the first current increase limiting network ( 5 ) with the first main connection ( 2 ), a capacity ( 8th ) of the first current increase limiting network ( 5 ) with the resistance ( 7 ) and with the partial connection ( 4 ) and a diode ( 9 ) of the first current increase limiting network ( 5 ) with the inductance ( 6 ) and with the connection point of the resistor ( 7 ) with the capacity ( 8th ) is connected to a second current increase limiting network ( 10 ), wherein an inductance ( 11 ) and a resistor ( 12 ) of the second current increase limiting network ( 10 ) with the second main connection ( 3 ), a capacity ( 13 ) of the second current increase limiting network ( 10 ) with the resistance ( 12 ) and with the partial connection ( 4 ) and a diode ( 14 ) of the second current increase limiting network ( 10 ) with the inductance ( 11 ) and with the connection point of the resistor ( 12 ) with the capacity ( 13 ), a first, second, third and fourth controllable bidirectional power semiconductor switch (S1, S2, S3, S4) and a fifth and sixth non-energized unidirectional power semiconductor switch (S5, S6), wherein the first, second, third and fourth Power semiconductor switch (S1, S2, S3, S4) are connected in series and the first power semiconductor switch (S1) with the connection point of the inductance ( 6 ) and the diode ( 9 ) of the first current increase limiting network ( 5 ) and the fourth power semiconductor switch (S4) with the connection point of the inductance ( 11 ) and the diode ( 14 ) of the second current increase limiting network ( 10 ), and wherein the fifth and sixth power semiconductor switches (S5, S6) are connected in series, the connection point of the fifth power semiconductor switch (S5) to the sixth power semiconductor switch (S6) to the sub-terminal ( 4 ), the fifth power semiconductor switch (S6) is connected to the connection point of the first power semiconductor switch (S1) to the second power semiconductor switch (S2) and the sixth power semiconductor switch (S6) to the connection point of the third power semiconductor switch (S3) to the fourth power semiconductor switch ( S4), characterized in that to the first, second, third and fourth controllable bidirectional power semiconductor switches (S1, S2, S3, S4) are each a series circuit of a resistor ( 15 ) with a capacity ( 16 ) is connected in parallel, and that the capacity ( 16 ) has a value in the order of greater than 1μF and the resistance ( 15 ) has a value in the order of magnitude between 2 ohms and 4 ohms. Converter circuit according to Claim 1, characterized that the first, second, third and fourth controllable bidirectional Power semiconductor switch (S1, S2, S3, S4) each by a integrated thyristor with commutated drive electrode and through a diode connected in anti-parallel with the thyristor is formed. Converter circuit according to claim 1 or 2, characterized characterized in that the fifth and sixth non-controllable unidirectional power semiconductor switches (S5, S6) is each formed by a diode. Converter circuit according to one of claims 1 to 3, characterized in that a controllable short-circuit element ( 17 ) with the partial connection ( 4 ) and connected to the connection point of the second to the third power semiconductor switch (S2, S3). Converter circuit according to one of claims 1 to 3, characterized in that a controllable short-circuit element ( 17 ) is provided, which via an inductance ( 20 ) is connected to the connection point of the second to the third power semiconductor switch (S2, S3), and that a series connection of a resistor ( 18 ) with a capacity ( 19 ) parallel to the controllable short-circuit element ( 17 ) is switched. Converter circuit according to claim 4 or 5, characterized in that the controllable short-circuit element ( 17 ) is formed of two antiparallel connected controllable power semiconductor switches with respective pressure contact. Converter circuit according to claim 6, characterized in that the respective controllable power semiconductor switch of the controllable short-circuit element ( 17 ) is formed by an integrated thyristor with commutated drive electrode. Converter circuit according to one of the preceding claims, characterized in that parallel to the series circuit of the fifth and sixth power semiconductor switch (S5, S6) a balancing resistor ( 21 ) is switched.