Bidirectional converter with intermediate circuit

Abstract

The invention relates to a converter having a three-phase AC input and output (L1, L2, L3, N), a first converter stage (1) with a first input and output and a second input and output (13, 14), an intermediate circuit (3), a second converter stage (2) with a first input and output (21, 22) and a second input and output (23, 24), and a DC output (A), wherein the first input and output of the first converter stage (1) are electrically connected to the three-phase AC input and output (L1, L2, L3, N) and the second input and output (13, 14) of the first converter stage (1) are electrically connected to the intermediate circuit (3). The converter is used in a charging device for an electric vehicle. At present, known transformerless converters for charging an electric vehicle on a single-phase AC network, a two-phase AC network or a three-phase AC network require many power electronic stages, so that charging devices for universal use on a single-phase, two-phase or three-phase AC network are costly. There is therefore a need for a charging device for an electric vehicle which is inexpensive and compact. The balancing currents which can flow into the vehicle as a result of the parasitic leakage capacitances of the battery or other components should be suppressed in order not to adversely affect the function of the protective devices for preventing electrical danger to persons. The circuit parts required for single-phase or multi-phase operation should be used in different functions depending on the mode of operation in order to minimize the outlay for the charging device.

Description

TECHNICAL FIELD

[0001] The invention relates to a transformerless converter with a three-phase alternating current input and output, a first converter stage with a first input and output and a second input and output, an intermediate circuit, a second converter stage with a first input and output and a second input and output, and a direct current input and output, wherein the first input and output of the first converter stage are electrically connected to the three-phase alternating current input and output, and the second input and output of the first converter stage are electrically connected to the intermediate circuit, wherein the first input and output of the second converter stage are electrically connected to the intermediate circuit, and the second input and output of the second converter stage are electrically connected to the direct current input and output, wherein the first converter stage is a controlled six-pulse bridge circuit composed of controllable converter thyristors arranged in a half-bridge, wherein the intermediate circuit has a capacitor half-bridge, i.e. a first capacitor and a second capacitor, wherein the first capacitor is connected on the one hand to a first terminal of the second input and output of the first converter stage and to a first terminal of the first input and output of the second converter stage, and on the other hand to the second capacitor, wherein the second capacitor is connected on the one hand to a second terminal of the second input and output of the first converter stage and to a second terminal of the first input and output of the second converter stage, and on the other hand to the first capacitor, wherein the connection point between the first capacitor and the second capacitor is connected to a neutral conductor terminal of the three-phase alternating current input and output.

[0002] The invention also relates to

[0003] a method for rectifying two-phase current from a two-phase alternating current source with a transformerless converter, wherein the converter is connected to the two-phase alternating current source via the second and third external conductor terminals of the three-phase alternating current input and output, and

[0004] a method for rectifying single-phase current from a single-phase alternating current source with a transformerless converter, wherein the converter is connected to the single-phase alternating current source via the third external conductor terminal of the three-phase alternating current input and output. BACKGROUND

[0005] The first converter stage of the transformerless converter generates a direct current voltage from a one-, two- or three-phase current, which is fed to the second converter stage via the intermediate circuit. With the second converter stage it is possible to set the direct current voltage of the intermediate circuit to the voltage that should be applied at the direct current input and output of the converter.

[0006] A converter is used in a charging device for electric vehicles. At present, known transformerless converters for charging electric vehicles on a single-phase, two-phase or three-phase AC network require many power electronics stages, so that charging devices for universal use on a single-phase, two-phase or three-phase AC network are costly. There is therefore a need for a charging device for electric vehicles which is inexpensive and compact. The balancing currents which can flow into the vehicle as a result of the parasitic leakage capacitances of the battery or other components should be suppressed so as not to adversely affect the function of the protective devices for preventing electrical hazards for persons. The circuit parts required for single-phase or multiphase operation should be used in different functions depending on the mode of operation in order to minimize the outlay for the charging device. SUMMARY

[0007] The inventors therefore propose that the converter has a first half-bridge of controlled converter thyristors, which is connected to a first terminal and a second terminal of the output of the first converter stage, and that the connection point between the converter thyristors of the first half-bridge of converter thyristors is connected to the connection point of the capacitor half-bridge by means of a first choke. With this first half-bridge of converter thyristors, the voltage on the first capacitor and / or the second capacitor of the capacitor half-bridge of the intermediate circuit can be regulated. As a result, when charging with a three-phase converter on a single-phase or two-phase AC network, leakage currents in the vehicle can be avoided. The regulation is responsible for the voltage on the first capacitor being the same as the voltage on the second capacitor.

[0008] When the first half-bridge of converter thyristors is formed by a first half-bridge of a controlled six-pulse bridge circuit, the circuit outlay can be reduced. A special converter thyristor need not then be provided solely for the purposes of the invention. The existing infrastructure of a controlled six-pulse bridge circuit can be utilized.

[0009] If the first half-bridge of converter thyristors is formed by a first half-bridge of a controlled six-pulse bridge circuit, it is advantageous for the converter to have a first switch with which the operation on a three-phase AC supply can be switched back and forth with a supply having fewer phases.

[0010] The first switch can be a changeover switch in a first variant, the common intermediate terminal of which is connected to the connection point of the first half-bridge of converter thyristors, and the changeover switch is connected either to the first choke or, if necessary via a further choke, to the first external conductor terminal of the three-phase AC input and output, depending on the switch position.

[0011] In a second variant, the first switch can also be a changeover switch, whose common intermediate terminal is connected via the first choke to the connection point of the first converter rectifier tube half-bridge and the changeover switch is connected according to the switch position either to the connection point of the capacitor half-bridge or to the first external conductor terminal of the three-phase AC input and output.

[0012] In a third variant, the first switch can be an on / off switch, which connects the first external conductor terminal of the three-phase AC input and output to the connection point of the capacitor half-bridge, wherein the first external conductor terminal is connected via the first choke to the first input and output of the controlled six-pulse bridge circuit.

[0013] Further variants are possible. In any variant, in the case of a supply on a three-phase AC power supply, an electrically conductive connection from the connection point of the first converter rectifier tube half-bridge to the first external conductor terminal of the three-phase AC input and output should be able to be established by the first switch in order to also supply the converter from the first external conductor terminal, whereas in the case of a supply on a single-phase or two-phase AC power supply, an electrically conductive connection from the connection point of the first converter rectifier tube half-bridge via the first choke to the connection point of the capacitor half-bridge exists by the first switch in order to be able to use the converter rectifier tube of the first converter rectifier tube half-bridge for regulating, in particular constant, the voltage on the second capacitor of the capacitor half-bridge with the control of the first converter stage. By the constant voltage on the second capacitor, a constant voltage is applied on the connection point of the capacitor half-bridge, which is connected to the neutral conductor. Thereby, output ripple currents can be avoided. Since the neutral conductor on the side of the AC input and output can be connected to the PE terminal of the vehicle and the charging station or charging column, an unallowable reactive current due to the parasitic capacitance of the vehicle can be avoided.

[0014] When the converter has a second half-bridge composed of two controlled converter rectifier tubes, which is connected to the first and second terminals of the second input and output of the first converter stage, and whose connection point between the two controlled converter rectifier tubes is connected to the second terminal of the second input and output of the first converter stage by a series circuit composed of a second choke and a third capacitor, a further improvement of the quality of the current on the DC input and output of the converter when charging on a single-phase AC network is possible. With this second converter rectifier tube half-bridge, the voltage on the capacitor half-bridge of the intermediate circuit can be regulated, in particular kept constant. Thereby, when charging with a three-phase converter on a single-phase AC network, a ripple of the current of the DC output of the converter can be avoided.

[0015] It is possible that the second converter rectifier tube half-bridge operates with the third capacitor as a storage capacitor as an active ripple filter.

[0016] The converter can not only be operated as a rectifier, but also as an inverter. Here, in particular, as a single-phase inverter or as a three-phase inverter. The second converter stage can then be operated as a DC voltage converter, in particular as a step-up converter, which supplies a voltage to the intermediate circuit. This voltage is converted into an alternating voltage by the first converter stage, which is operated as an inverter. The first converter stage, i.e. the controlled six-pulse bridge circuit, can here be network-guided or, in particular in island operation, automatically guided and thus form a network. Even in the case of inverter operation, it is necessary not only to keep the power factor constant, but also to prevent leakage currents due to voltage ripples on the parasitic capacitances. Voltage ripples on the capacitor half-bridge of the intermediate circuit must therefore also be avoided in single-phase operation. Here, the voltage ripples can be avoided with the same means as in the case of rectifier operation.

[0017] When the second converter rectifier half-bridge is formed by the second of the half-bridges of the controlled six-pulse bridge circuit, the circuit expenditure can be reduced. No special converter rectifier need then be provided only for the purposes of the present application. The existing basic structure of the controlled six-pulse bridge circuit can be utilized.

[0018] If the second converter rectifier half-bridge is formed by the second of the half-bridges of the controlled six-pulse bridge circuit, it is advantageous for the converter to have a second switch with which the operation on a three-phase or two-phase alternating current supply and a supply with one phase can be switched back and forth.

[0019] The second switch can in a first variant be a switching switch, the common intermediate terminal of which is connected to the connection point of the second converter rectifier half-bridge and which, depending on the switch position, is either connected to the second choke or, if necessary, via a further choke to the second outer conductor terminal of the three-phase alternating current input and output.

[0020] In a second variant, the second switch can be a switching switch, the common intermediate terminal of which is connected to the connection point of the second converter rectifier half-bridge via the second choke and which, depending on the switch position, is either connected to the third capacitor or to the second outer conductor terminal of the three-phase alternating current input and output.

[0021] It is furthermore possible for the second switch to be an on and off switch in a third variant, which connects the second outer conductor terminal of the three-phase alternating current input and output to the third capacitor, wherein the second outer conductor terminal is connected to the first input and output of the controlled six-pulse bridge circuit via the second choke.

[0022] Further variants exist for the implementation of the second switch and the connection into the converter. In any variant, in the case of a three-phase or two-phase AC supply, an electrically conductive connection from the connection point of the second converter rectifier half-bridge to the second outer conductor terminal of the three-phase AC input and output should be able to be established by the second switch in order to also supply the converter via the second outer conductor terminal, while in the case of a single-phase AC supply, an electrically conductive connection from the connection point of the second converter rectifier half-bridge via a series circuit consisting of the second choke and the third capacitor to the second terminal of the second input and output of the first converter stage exists by means of the second switch in order to be able to use the converter rectifier of the second converter rectifier half-bridge for regulating the voltage in the intermediate circuit using the control of the first converter stage.

[0023] The second converter stage can be a DC converter, in particular a synchronous converter.

[0024] The second converter stage can comprise at least one converter rectifier half-bridge consisting of two converter rectifiers, wherein a first of the two converter rectifiers is connected to the first terminal on the one hand and a second of the two converter rectifiers is connected to the second terminal of the first input and output of the second converter stage on the one hand and to the connection point between the two converter rectifiers on the other hand. The connection point and the second terminal of the first input and output can be connected to the second input and output of the second converter stage via a low-pass filter. If the second converter stage has two such converter rectifier half-bridges, the capacitors of the low-pass filter can be combined into one structural element.

[0025] The converter rectifiers used in the present application can be transistors, power transistors, thyristors, IGBTs, FETs, MOS-FETs, etc. BRIEF DESCRIPTION OF DRAWINGS

[0026] The application is explained in more detail below with the aid of the drawings. The drawings each show a converter with an intermediate circuit having a capacitor half-bridge and a first converter rectifier half-bridge for regulating the voltage at the connection point of the capacitor half-bridge and a second converter rectifier half-bridge for regulating the voltage in the intermediate circuit. Herein are shown:

[0027] Figure 1a A converter is shown, wherein the first converter rectifier half-bridge and the second converter rectifier half-bridge are formed by converter rectifiers outside the first converter stage and the second converter stage is configured by a synchronous converter with a converter rectifier half-bridge,

[0028] Figure 1b A variant of the converter in Figure 1a is shown, wherein the first converter rectifier half-bridge and the second converter rectifier half-bridge are formed by converter rectifiers outside the first converter stage and the second converter stage is configured by a synchronous converter with a converter rectifier half-bridge, Figure 1aUnlike the converters in the first stage, the second converter stage is constructed using a synchronous converter with two converter rectifier half-bridges.

[0029] Figure 2a A converter is shown, wherein a first converter rectifier half-bridge is formed by the converter rectifier half-bridge of a first converter stage, and a second converter rectifier half-bridge is formed by converter rectifiers outside the first converter stage, and the second converter stage is constructed of a synchronous converter having converter rectifier half-bridges.

[0030] Figure 2b Show Figure 2a Variant schemes of converters in the middle, among which, with Figure 2a Unlike the converters in the first stage, the second converter stage is constructed using a synchronous converter with two converter rectifier half-bridges.

[0031] Figure 3a A converter is shown, wherein the first and second converter rectifier tube half-bridges outside the first converter stage are formed by the converter rectifier tube half-bridges of the first converter stage, and the second converter stage is constructed by a synchronous converter having converter rectifier tube half-bridges.

[0032] Figure 3b Showing according to Figure 3a Variant schemes of converters, wherein, according to Figure 3a Unlike the first converter, the second converter stage is constructed using a synchronous converter with two converter rectifier half-bridges.

[0033] Figure 4a A converter is shown, wherein a first converter rectifier half-bridge and a second converter rectifier half-bridge are formed by the converter rectifier half-bridges of the first converter stage, and the second converter stage is constructed by a synchronous converter having converter rectifier half-bridges.

[0034] Figure 4b Showing according to Figure 4a Variant schemes of converters, wherein, according to Figure 4a Unlike the first converter, the second converter stage is constructed using a synchronous converter with two converter rectifier half-bridges.

[0035] Figure 5a Show Figure 4a The variant scheme of the converter in the middle, and

[0036] Figure 5b Show Figure 4b A variant scheme for the converter in the process. Detailed Implementation

[0037] Now according to Figure 1a The converter described herein illustrates the principle of the converter according to the present invention.Figure 1a The converter according to the application, as in the other figures, is a bidirectional three-phase AC rectifier with a three-phase AC input and output L1, L2, L3, N, a first converter stage 1, an intermediate circuit 3, a second converter stage 2 and DC outputs 24, 25, the intermediate circuit comprising capacitor half-bridges C1, C2, with external conductor terminals L1, L2, L3 and a neutral conductor terminal N.

[0038] Figure 1a The first input and output of the first converter stage 1 of the converter in Fig. 1 are connected to the external conductor terminals L1, L2, L3 of the three-phase AC input and output L1, L2, L3, N via one choke I1, I2, I3 each, as in the input of the first converter stage 1 of the converter in Fig. 2. Figures 1b to 4b The three-phase AC input and output L1, L2, L3, N can be connected not only to a three-phase AC network, but the converter can also be connected to a two-phase AC network or a single-phase AC network using the three-phase AC input and output L1, L2, L3, N and operate on these networks.

[0039] The second input and output 13, 14 of the first converter stage 1 are connected to the intermediate circuit 3, as are the output 13, 14 of the first converter stage 1 of the converter in Fig. 2. Figures 1b to 5b The intermediate circuit of the converter is likewise connected to the first input and output 21, 22 of the second converter stage 2, the second input and output 23, 24 of the second converter stage forming the second input and output of the converter.

[0040] The first converter stage 1 is formed by a controlled six-pulse bridge circuit consisting of controllable converter rectifiers Q1, Q2, Q3, Q4, Q5, Q6 arranged in the half-bridges Q1, Q2; Q3, Q4; Q5, Q6. A control unit for operating the converter rectifiers Q1, Q2, Q3, Q4, Q5, Q6 is preferably provided, but is not shown. The connection points between the converter rectifiers Q1, Q2, Q3, Q4, Q5, Q6 of the half-bridges Q1, Q2; Q3, Q4; Q5, Q6 are connected to the external conductor terminals L1, L2, L3 via the first input and output of the first converter stage 1 and the chokes I1, I2, I3. The external terminals of the half-bridges Q1, Q2; Q3, Q4; Q5, Q6 are connected to the terminals 13, 14 of the first converter stage 1.

[0041] The capacitor half-bridge Cl, C2 is connected on the one hand to the first terminals 13, 21 of the second input and the output 13, 14 of the first converter stage 1 and of the first input and the output 21, 22 of the second converter stage 2 and on the other hand to the second terminals 14, 22 of the output 13, 14 of the first converter stage 1 and of the first input and the output 21, 22 of the second converter stage 2. The connection point 31 between the two capacitors Cl, C2 is connected to the neutral conductor terminal N.

[0042] When the voltage over the first capacitor Cl is not equal to the voltage over the second capacitor C2, an undesired leakage current can occur in the device connected to the converter when the converter is operated on a single-phase or two-phase AC supply.

[0043] The voltage present between the connection point 31 of the capacitor half-bridge and the neutral conductor N on the one hand and between the second terminal 14 of the output of the first converter stage 1 and the second terminal 22 of the output of the second converter stage 2 on the other hand is stabilized by the first converter thyristor half-bridge. In Figure 1a In the converter of the first embodiment, the first converter thyristor half-bridge is formed by the converter Q7, Q8. The connection point between the two converters Q7, Q8 is connected via the choke I4 to the connection point 31 of the capacitor half-bridge Cl, C2 and to the neutral conductor terminal N. The terminals of the converter thyristor half-bridge Q7, Q8 that are external are connected on the one hand to the first terminals 13, 21 of the second input and the output 13, 14 of the first converter stage 1 and of the first input and the output 21, 22 of the second converter stage 2 and on the other hand to the second terminals 14, 22 of the second input and the output 13, 14 of the first converter stage 1 and of the first input and the output 21, 22 of the second converter stage 2.

[0044] By the alternating closing and opening of the converter thyristors Q7, Q8 of the first converter thyristor half-bridge Q7, Q8 with variable duty cycle, the voltage between the connection point 31 and the first terminal 13 of the output 13, 14 can be set, which voltage drops over the capacitor C2. The converter thyristors Q7, Q8 of the first converter thyristor half-bridge Q7, Q8 are opened and closed in such a way that the voltages over the first capacitor Cl and the second capacitor C2 are equal or at least the voltage over C2 is maximally constant. Thereby, a leakage current can be avoided.

[0045] The voltage falling on the capacitor half-bridge Cl, C2, that is to say on the second input and output terminals 13, 14 of the first converter stage 1 and on the first input and output terminals 21, 22 of the second converter stage 2, can be stabilized by means of an active filter in order to avoid voltage ripples. The active filter is formed by a second converter rectifier half-bridge comprising the converter rectifier tubes Q9, Q10 and a series circuit consisting of the third capacitor C3 and the choke I5. The outer terminals of the converter half-bridge are connected on the one hand to the first terminal 13 of the second input and output terminals 13, 14 of the first converter stage 1 and to the first terminal 21 of the first input and output terminals 21, 22 of the second converter stage 2 and on the other hand to the second terminal 14 of the second input and output terminals 13, 14 of the first converter stage 1 and to the second terminal 22 of the first input and output terminals 21, 22 of the second converter stage 2. The connection point between the two converter rectifier tubes Q9, Q10 is connected via the series circuit C3, I5 to the second terminal 14 of the second input and output terminals 13, 14 of the first converter stage 1 and to the second terminal 22 of the first input and output terminals 21, 22 of the second converter stage 2. By closing and opening the converter rectifier tubes Q9, Q10, the voltage on the second converter rectifier half-bridge and thus the voltage on the second input and output terminals 13, 14 of the first converter stage 1 and on the first input and output terminals 21, 22 of the second converter stage 2 can be set. For this purpose, the capacitor C3 and the choke I5 can be charged in the case of the converter rectifier tube Q9 being open and the converter rectifier tube Q10 being closed and can be discharged in the case of the converter rectifier tube Q9 being closed and the converter rectifier tube Q10 being open. Thereby, voltage ripples can be prevented or at least reduced.

[0046] The second converter stage 2 is formed by a DC voltage converter, namely by a first synchronous converter. The converter rectifier half-bridge of this DC voltage converter, consisting of the two converter rectifier tubes Q11 and Q12, is connected with its outer terminals to the first input and output terminals 21, 22 of the second converter stage 2. The connection point between the converter rectifier tubes Q11, Q12 and the second terminal 22 of the first input and output terminals is connected to the second input and output terminals 23, 24 via a low-pass filter consisting of the choke I6 and the capacitor C4.

[0047] Figure 2a the converter shown in Fig. 1 and Figure 1aThe difference in the converter shown is that the first converter rectifier half-bridge is not formed by external structural components of the first converter stage 1, but by the first converter rectifier half-bridge Q1 and Q2 of the controlled six-pulse bridge circuit Q1, Q2, Q3, Q4, Q5, Q6. This first converter rectifier half-bridge is connected to the first external conductor terminal L1 of the three-phase AC input and output terminals L1, L2, L3, N during three-phase power supply. Figure 1a Unlike other converters, the connection points of the converter rectifier half-bridge Q1 and Q2 are not directly connected to the external conductor terminal L1 via chokes. Instead, they are connected to a common intermediate terminal of the switching switch S1. From this intermediate terminal, a connection to the external conductor terminal L1 can be established according to the control of the switching switch S1, or a connection to connection point 31 in the capacitor bridge circuit can be established via choke I4. When connected to the external conductor terminal L1, converter rectifiers Q1 and Q2 can be used to connect to a three-phase current source. When connected to choke I4, converter rectifiers (in the case of single-phase or two-phase connection to a current source) can be used to stabilize the voltage between connection point 31 or neutral conductor terminal N and the second terminals 14 of the second input and output terminals 13 and 14 of the first converter stage 1 and the second terminals 22 of the first input and output terminals 21 and 22 of the second converter stage 2.

[0048] Figure 3a The converter shown is Figure 1a The difference in the converter shown is that the second converter rectifier half-bridge is not formed by external structural components of the first converter stage 1, but by the second converter rectifier half-bridge in Q3 and Q4 of the controlled six-pulse bridge circuit Q1, Q2, Q3, Q4, Q5, Q6. This second converter rectifier half-bridge is connected to the second external conductor terminal L2 of the three-phase AC input and output terminals L1, L2, L3, N during three-phase power supply. Figure 1aUnlike other converters, the connection points of the converter rectifier tube half-bridge Q1 and Q2 are not directly connected to the external conductor terminal L2 via chokes. Instead, the connection points are connected to a common intermediate terminal of the switching switch S2. From this intermediate terminal, a connection to the external conductor terminal L2 can be established according to the control of the switching switch S2, or a connection can be established to the second terminals 14 of the second input and output terminals 13 and 14 of the first converter stage 1 and the second terminals 22 of the first input and output terminals 21 and 22 of the second converter stage 2 via a series circuit of choke I5 and capacitor C3. When connected to the external conductor terminal L2, the converter rectifier tubes Q1 and Q2 can be connected to a three-phase or two-phase power supply. When connected to the series circuit I5, C3, the converter rectifier tube (when connected to the current source in a single phase) can be used to stabilize the voltage between the first terminal 13 of the second input and output terminals 13, 14 of the first converter stage 1 and the first terminal 21 of the first input and output terminals 21, 22 of the second converter stage 2, and on the other hand, stabilize the voltage between the second terminal 14 of the second input and output terminals 13, 14 of the first converter stage 1 and the second terminal 21 of the first input and output terminals 21, 22 of the second converter stage 2.

[0049] exist Figure 4a The converter shown uses not only the first converter rectifier half-bridges Q1 and Q2, but also the second converter rectifier half-bridges Q3 and Q4 to stabilize the voltage on capacitor C2 or the voltage in intermediate circuit 3 when the converter is powered by single-phase or two-phase power. The first converter rectifier half-bridges Q1 and Q2 and the second converter rectifier half-bridges Q3 and Q4 can be connected to external conductor terminals L1 and L2 via switching switches S1 and S2, or to choke I4 or to a series circuit consisting of choke I5 and capacitor C3, as shown in the circuit. Figure 2a Or by Figure 3a As is possible in the converter.

[0050] Figure 5a The converter shown is Figure 4a The difference in the converter shown is that the number of structural components used is further reduced. This is achieved by replacing the switching switches S1 and S2 with on and off switches S1 and S2, and changing the connection points between switches S1 and S2 and the converter rectifier tubes Q1, Q2 or Q3, Q4. These connection points are... Figure 5a The converter is connected to switches S1 and S2 via choke coils I1 and I2.

[0051] When switch S1 is closed, a connection is established from the connection point between the converter rectifier tubes Q1 and Q2 via choke I1 to the neutral conductor terminal N or to connection point 31. Choke I1 here handles the connection from... Figure 1a ,2a The function of the choke I4 of the converter of 3a and 4a. The converter rectifier tubes Q1, Q2 are switched in single-phase or two-phase AC operation in such a way that the voltage on the capacitor C2 of the capacitor half-bridge Cl, C2 is as constant as possible. This is the case when the current through the choke I1 is opposite to the current through the choke I3.

[0052] When the switch S2 is closed, a connection to the capacitor C3 is established, so that there is then a connection from the connection point between the converter rectifier tubes Q3, Q4 via the choke I2 and the capacitor to the second terminal 14 of the second input and output 13, 14 of the first converter stage 1 and to the second terminal 22 of the first input and output 21, 22 of the second converter stage 2. The choke I2 here assumes the function of the first synchronous converter from the connection point between the converter rectifier tubes Q3, Q4 to the second terminal 14 of the second input and output 13, 14 of the first converter stage 1 and to the second terminal 22 of the first input and output 21, 22 of the second converter stage 2. Figure 1a , 2a The function of the choke I5 of the converter of 3a and 4a.

[0053] Figure 1b The converter in 3a and 4a differs from the converter in 2a and 2b in that the second converter stage 2 has, in addition to the first synchronous converter already provided in the second converter stage of the converter according to 2a and 2b, a second synchronous converter in parallel with the first synchronous converter. This second synchronous converter has two converter rectifier tubes Q13, Q14 in a half-bridge arrangement and a choke I6 connected to the connection point between the converter rectifier tubes Q13, Q14 and a capacitor C4 used by the two synchronous rectifiers. In the same way, the converter according to 3b and 4b differs from the converter shown in 1a and 1b. Figure 1a Figure 1a The converter in 3a and 4a differs from the converter in 2a and 2b in that the second converter stage 2 has, in addition to the first synchronous converter already provided in the second converter stage of the converter according to 2a and 2b, a second synchronous converter in parallel with the first synchronous converter. This second synchronous converter has two converter rectifier tubes Q13, Q14 in a half-bridge arrangement and a choke I6 connected to the connection point between the converter rectifier tubes Q13, Q14 and a capacitor C4 used by the two synchronous rectifiers. In the same way, the converter according to 3b and 4b differs from the converter shown in 1a and 1b. Figure 2b , 3b The converter of 4b and 5b differs from the converter shown in 3a and 3b. Figure 2a , 3a The converter of 4a and 5a differs from the converter shown in 2a and 2b.

[0054] List of reference signs

[0055] L1, L2, L3, N three-phase AC input and output

[0056] I1, I2, I3 chokes

[0057] 1 first inverter stage

[0058] 13, 14 second input and output of the first inverter stage

[0059] Q1, Q2, Q3, Q4, Q5, Q6 converter rectifier tubes of the first inverter stage

[0060] 2 second converter stage

[0061] 21, 22 first input and output of the second converter stage ​

[0062] 23, 24 second input and output of the second converter stage

[0063] Q11, Q12 first converter diode of the second converter stage

[0064] Q13, Q14 second converter diode of the second converter stage

[0065] 3 intermediate circuit

[0066] C1 first capacitor of the capacitor half-bridge

[0067] C2 second capacitor of the capacitor half-bridge

[0068] 31 connection point

[0069] S1 first switch

[0070] Q7, Q8 converter half-bridge

[0071] I4 choke

[0072] S2 second switch

[0073] Q9, Q10 converter half-bridge

[0074] I5 choke

[0075] C3 capacitor

[0076] I6 choke

[0077] I7 choke

[0078] C4 capacitor

Claims

1. A bidirectional converter with an intermediate circuit, the bidirectional converter comprising: a three-phase AC input and output terminal (L1, L2, L3, N), a first converter stage (1) with a first input and output terminal and a second input and output terminal, an intermediate circuit (3), a second converter stage (2) with a first input and output terminal and a second input and output terminal, and a DC input and output terminal. wherein The first input and output terminals of the first converter stage (1) are electrically connected to the three-phase AC input and output terminals (L1, L2, L3, N), and the second input and output terminals of the first converter stage (1) are electrically connected to the intermediate circuit (3). The first input and output terminals of the second converter stage (2) are electrically connected to the intermediate circuit (3), and the second input and output terminals of the second converter stage (2) are electrically connected to the DC input and output terminals. The first converter stage (1) is a controlled six-pulse bridge circuit composed of controllable converter rectifier tubes (Q1, Q2, Q3, Q4, Q5, Q6) arranged in a half-bridge. The six-pulse bridge circuit has chokes (I1, I2, I3) between each external conductor terminal of the three-phase AC input and output terminals and the bridge midpoint of each half-bridge. The intermediate circuit (3) has a capacitor half-bridge composed of a first capacitor and a second capacitor. The first capacitor is connected to the first terminal (13) of the second input and output terminals of the first converter stage (1) and the first terminal (21) of the first input and output terminals of the second converter stage (2) on one hand, and to the second capacitor (2) on the other hand. The second capacitor is connected to the second terminal (14) of the second input and output terminals of the first converter stage (1) and the second terminal (22) of the first input and output terminals of the second converter stage (2), and is also connected to the first capacitor. The connection point (31) between the first capacitor and the second capacitor is connected to the neutral conductor terminal (N) of the three-phase AC input and output terminals (L1, L2, L3, N). Its features are, The converter has a first half-bridge consisting of two controlled converter rectifier tubes. The first half-bridge is connected to the first terminal (13) and the second terminal (14) of the second input and output terminals of the first converter stage (1). The connection point of the first half-bridge between each converter rectifier tube of the first converter rectifier tube half-bridge is connected to the connection point (31) of the capacitor half-bridge through a first choke.

2. The current transformer of claim 1, wherein, The first converter rectifier half-bridge is formed by the first half-bridge of a controlled six-pulse bridge circuit (Q1, Q2, Q3, Q4, Q5, Q6).

3. The current transformer of claim 2, wherein, The converter has a first switch (S1).

4. The current transformer of claim 3, wherein, The first switch (S1) is a changeover switch, the common intermediate terminal of which is connected to the connection point of the first converter rectifier tube half-bridge, and which is connected either to the first choke depending on the switch position or to the first external conductor terminal of the three-phase AC input and output (L1, L2, L3, N).

5. The current transformer of claim 3, wherein, The first switch (S1) is a changeover switch, the common intermediate terminal of which is connected to the connection point of the first converter rectifier tube half-bridge via the first choke, and which is connected either to the connection point (31) of the capacitor half-bridge depending on the switch position or to the first external conductor terminal of the three-phase AC input and output (L1, L2, L3, N).

6. The current transformer of claim 3, wherein, The first switch (S1) is a changeover switch, the common intermediate terminal of which is connected to the connection point of the first converter rectifier tube half-bridge via the first choke, and which is connected either to the connection point (31) of the capacitor half-bridge depending on the switch position or to the first external conductor terminal of the three-phase AC input and output (L1, L2, L3, N).

7. The current transformer of any one of claims 1 to 6, characterized in that The converter has a second half-bridge consisting of two controlled converter rectifier tubes, which is connected to the first terminal (13) and the second terminal (14) of the second input and output of the first converter stage (1), and the connection point between the two controlled converter rectifier tubes of the second half-bridge is connected to the second terminal (14) of the second input and output of the first converter stage (1) via a series circuit consisting of a second choke and a third capacitor.

8. The current transformer of claim 7, wherein, The second converter rectifier tube half-bridge is formed by the second half-bridge in the half-bridge of the controlled six-pulse bridge (Q1, Q2, Q3, Q4, Q5, Q6).

9. The current transformer of claim 8, wherein, The converter has a second switch (S2).

10. The current transformer of claim 9, wherein, The second switch (S2) is a changeover switch, the common intermediate terminal of which is connected to the connection point of the second converter rectifier tube half-bridge, and which is connected either to the second choke depending on the switch position or to the second external conductor terminal of the three-phase AC input and output (L1, L2, L3, N).

11. The current transformer of claim 9, wherein, The second switch (S2) is a changeover switch, the common intermediate terminal of which is connected to the connection point of the second converter rectifier tube half-bridge via the second choke, and which is connected either to the third capacitor depending on the switch position or to the second external conductor terminal of the three-phase AC input and output (L1, L2, L3, N).

12. The current transformer of claim 9, wherein, The second switch (S2) is a changeover switch, the common intermediate terminal of which is connected to the connection point of the second converter rectifier tube half-bridge via the second choke, and which is connected either to the third capacitor depending on the switch position or to the second external conductor terminal of the three-phase AC input and output (L1, L2, L3, N). The second switch (S2) is a changeover switch, the common intermediate terminal of which is connected to the connection point of the second converter rectifier tube half-bridge via the second choke, and which is connected either to the third capacitor depending on the switch position or to the second external conductor terminal of the three-phase AC input and output (L1, L2, L3, N).

13. The current transformer of claim 3, wherein, The first switch (S1) is a switching switch, whose common intermediate terminal is connected with the connection point of the first converter rectifier tube half bridge, and which is either connected with the first choke according to the switch position or connected via the choke with the first external conductor terminal of the three-phase AC input and output (L1, L2, L3, N).

14. The current transformer of claim 9, wherein, The second switch (S2) is a switching switch, whose common intermediate terminal is connected with the connection point of the second converter rectifier tube half bridge, and which is either connected with the second choke according to the switch position or connected via the choke with the second external conductor terminal of the three-phase AC input and output (L1, L2, L3, N).

15. A method for rectifying two-phase electricity from a two-phase alternating current power supply with a current transformer according to any one of claims 3 to 5, wherein, The converter is connected with the two-phase AC power supply via the second and third external conductor terminals of the three-phase AC input and output (L1, L2, L3, N), characterized in that The first switch is in a switch position in which there is an electrically conductive connection from the connection point of the first converter rectifier tube half bridge via the first choke to the connection point of the capacitor half bridge, and with the control of the first converter stage, the converter rectifier tube pair of the first converter rectifier tube half bridge regulates the voltage on the first and / or second capacitor of the capacitor half bridge.

16. A method for rectifying single-phase electricity from a single-phase alternating current grid or for inverting direct current from a direct current grid with a converter according to any one of claims 3 to 6 and 9 to 14, wherein, The converter is connected with the single-phase AC network via the third external conductor terminal of the three-phase AC input and output (L1, L2, L3, N), the converter having a first switch (S1) and a second switch (S2), characterized in that The first switch (S1) is in a switch position in which there is an electrically conductive connection from the connection point of the first converter rectifier tube half bridge via the first choke to the connection point of the capacitor half bridge, and with the control of the first converter stage, the converter rectifier tube pair of the first converter rectifier tube half bridge regulates the voltage on the first and / or second capacitor of the capacitor half bridge, and The second switch (S2) is in a switch position in which there is an electrically conductive connection from the connection point of the second converter rectifier tube half bridge through the series circuit consisting of the second choke and the third capacitor to the second terminal (14) of the second input and output of the first converter stage (1), and with the control of the first converter stage (1), the converter rectifier tube pair of the second converter rectifier tube half bridge regulates the voltage on the capacitor half bridge.

17. The method of claim 16, wherein, The second converter rectifier tube half bridge operates with the third capacitor as a storage capacitor as an active ripple filter.

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