DE20221373U1 - Inverter for welding devices comprises two asymmetric high bridge circuits which alternately drive two separate primary coils of a main transformer - Google Patents

Abstract

Inverter comprises two asymmetric high bridge circuits (1a, 1b) which alternately drive two separate primary coils (3a, 3b) of a main transformer (3). A current multiplier rectifier (6) is connected to the secondary coil (3c) of the main transformer. A saturated inductive resistor (5a, 5b) is connected to each primary coil of the main transformer.

Description

The The invention relates to an inverter having two asymmetrical half-bridge circuits, alternately two separate primary windings of a main transformer drive, in which at the secondary winding of the main transformer turned on a current doubler rectifier is.

Of the Trend in inverter construction is increasingly in the direction of smaller dimensions and lighter weights. At the same time the requirements in increased in many aspects. Thus, the harmonic content of the mains current has to be increasingly stringent meet legal standards. This requires a considerable effort, elevated the weight and the volume of the whole device. All the more must the efficiency the power electronics are improved. An exemplary stand the technology is for this given in Scripture: "Design and Experimental Analysis of a 10kW 800V / 48V Dual Interleaved Two-Transistor DC / DC Forward Converter System Supplied by a VIENNA Rectifier I "by Johann Miniböck, Johann W. Kolar and Hans Ertl. This font was part of a public Seminar lecture distributed at the PCIM conference in Nuremberg 2002.

On Page 10 is a basic circuit according to the preamble of this invention displayed. The text already mentions that the two inverter systems - the here are connected in series - themselves probably affect each other because they only work on a single transformer work. Any voltage that is fed into a primary winding will transfer as well on the other half-bridge system and tries there disturbances. The realized circuit in this document from page 1 knows this Problems do not matter as they over has separate transformers. This circuit also works with a moderate switching frequency of 25kHz and is called 48V power supply for telecommunication equipment planned. However, to ads weight, the size and cost of a second To be able to save on transformers the authors suggest a circuit to page 10.

If now an inverter needed which is considerably higher Switching frequency should work, so there are new problems. Height Switching frequencies are e.g. needed in the pulse welding technique, as the Inverter controls must produce extremely fast current patterns, e.g. above 1000A / ms. At the same time an extremely fast control is needed because of the welding completely unpredictable and in a chaotic sequence arc shorts occur so the output power is within fractions of a millisecond around ranges of 95% of the full load can vary. For such High dynamic requirements require high switching frequencies and therefor It is advantageous to use transistors of the MOSFET type.

It An attempt has now been made to use MOSFETs in a circuit for a welder. There were enormous problems related to the fact that MOSFET transistors a parasitic diode inverse to the transistor. If one of the half-bridge circuits goes into the so-called freewheeling operation, this is the state in the primary winding of the main transformer degrades its magnetization via the freewheeling diodes, then start in the second inverter, the inverse freewheeling diodes to lead, then shortly thereafter a high du / dt load of the MOSFET he follows. This is a typical situation where a MOSFET is in can go to the destruction state "second break down" and this must be under all circumstances be prevented. The circuit described on page 10 is like this So not safe to operate with MOSFETs.

In certain limits just before the full scale of the inverter there were still significant problems with saturation phenomena in the main transformer.

A conventional Control with pulse-width-modulated drive signals led to a swinging of the magnetizing current in borderline situations. At the same time, the PWM system was in the event of short circuits in its speed too slow.

The The invention has the object of an inverter circuit to evolve in many aspects to operate with MOSFET transistors can be, with the magnetizing currents are cleanly controlled in the main transformer, an extremely fast control without transformer saturation is achievable and that all put to a welding machine Requirements fulfilled are.

These Task is achieved according to the invention in that with each primary of the main transformer is a saturable inductance is connected in series.

Of the Inverter can be divided into parallel subsystems, where the symmetry of the current distribution is always guaranteed, a balancing system for the Capacitive center in series connection of the half-bridge circuits can be found, the rules of harmonics in the mains are sustainable, the inverter system into the higher power ranges into it can be realized and a modular system is implemented to flexibly the Meet the requirements of the market.

For a welder, the weight is an outstanding size. With this design of the circuit, the smoothing throttles can be kept small and for very high powers, subsystems that are constructed in this way can be operated in parallel.

further developments the basic circuit are the numerous subclaims in particular, with the division of the inverter into several small partial inverters and the phase-shifted operation to deal with it. Also the rule structure of the partial and total system was improved and the repercussions reduced to the supply network.

At the Operation of such an inverter system with very small currents can the so-called intermittent operation begin, with both subsystems not more strictly alternate clocking. In a series connection of the half-bridge circuits occurs a shift of the center of the power supply on, leading to a destruction lead the subsystems can. On the other hand, a further education indicates a solution.

Especially feedback rejection Relationships and much calmer curves arise when in series with the output diodes of the current doubler rectifier each a second saturable inductance is switched.

A particularly simple realization arises when the first and second saturable inductors are formed by ring cores, through which the respective conductor leads.

Especially is effective and thermally advantageous when the torus of the saturable Inductance off amorphous or nanocrystalline strip material is made.

Especially small and inexpensive Ring cores can be used when the ring cores of the saturable inductors thermally conductive in holes of cooling profiles or heat transfer profiles are installed to heat dissipation considerably to improve.

A particularly advantageous embodiment of the inverter system provides that each one connection of the two primary windings together so by a Current converter led is that it detects a total current with alternating polarity and transforms.

A significant increase the regulatory stability in borderline cases arises when this current transformer is a compensation current transformer with magnetic field sensor, which is also resulting DC components can measure.

A Another embodiment with many advantages arises when the Inverter system over one Has cascade control, wherein a main controller using the output current value of the Output current or the output voltage from the output of the power unit and with the aid of the nominal value of the output current or the output voltage implemented as needed a current regulator or a voltage regulator and wherein the output of this main regulator as a guide signal a Regulator supplied which acts as a current-mode regulator for the primary current of the main transformer is realized.

One System with both control systems arises when the main controller both contains a current regulator as well as a voltage regulator, the in a detachment circuit so interconnected are that each of the controller receives the leadership, the smaller command signal generated.

at the design of the regulator also gives the advantageous way that the main regulator as a digital regulator with the usual means the processor technology is formed and that the analogue control signal via a D / A converter process is generated to use it as a current setpoint signal to supply to the current mode controller.

Around continue to use the bipolar signal of the current transformer is in an advantageous manner for forming the primary current actual value amount for the current-mode regulator, the primary current actual value rectified by the compensation current transformer with an absolute value generator.

A very simple and inexpensive structure of the common-mode controller is created by using an oscillator with a downstream pulse generator generates drive pulses, with the help of each one of the flip-flop memory associated with the half-bridge inverter associated with the half-bridge inverter alternately set and reset and that the respective setting or resetting of these flip-flop memory with the aid of downstream drive circuits for switching on or turning off the transistors of the associated half-bridge circuit leads.

In continuation it is advantageous if the current-mode controller at the input via a Comparator has, which is the primary current-actual value amount with the amplitude of the pilot signal compares, and that at a larger actual value the flip-flop memory reset so that ultimately the two transistors of the respective active half-bridge circuit be turned off again.

Depending on the level of mains supply, it is good if the two asymmetrical half-bridge circuits from the same supply chip can be fed.

at higher Mains voltages, however, it benefits if the two asymmetric half-bridge shafts are connected in series with their supply voltages.

One particularly stable behavior of the entire system, especially at the smallest Power extraction occurs when in a series connection of the half-bridge circuits a monitoring circuit the symmetry of the capacitive center terminal with respect to positive supply voltage and the negative supply voltage measures and that the output signal of this monitoring circuit is the asymmetric Indicates behavior with the information of the direction of Asymmetry.

Farther it helps in this case if the output signal of the monitoring circuit is used to to block the drive pulses of that half-bridge circuit or shorten, the over the has smaller supply voltage until the symmetry of the supply voltages is restored.

To the Construction of larger inverter systems There is the advantageous way that two half-bridge circuits and one main transformer (possibly provide with the first saturable inductors) and a current transformer and a current doubler rectifier (provided possibly with the second saturable Additional inductors) too be summarized a power section.

A even more extensive modularization arises when a power unit together with a drive transformer and with drive circuits and with a current-mode regulator be combined into a subsystem.

inverter systems with very high output powers can now be realized thereby that several subsystems are connected in parallel and that the Reference at the entrance the current mode knob for all subsystems is identical, and of a common main controller for the entire system he testifies, in which case the output current actual value represents the flow of the entire system.

A dramatic reduction of the ripple on the output current is achieved in the case of parallel connection of several subsystems, the oscillator with downstream pulse generator is common to all and that Setting the flip-flop memory for the various half-bridge circuits on as possible many out of phase moments is split, hence the resulting ripple the output current is minimal.

A particularly advantageous combination for compliance with the statutory Harmonic regulations on the supply network is created by the power section at the terminals of the positive supply voltage and the negative Supply voltage is a known boost converter circuit and a mains rectifier is connected upstream to the power input be controlled from the supply network.

Out the same reasons it is extremely beneficial that the upstream boost converter circuit itself from a Parallel connection of several boost converter circuits of smaller power is realized.

Around while achieving an equal distribution of power is provided that the setpoint signal for the Input current of the individual boost converter circuits for all identical is.

A particularly economical and advantageous from the point of view of EMC solution arises when the individual boost converter circuits in one pha senversetzten clock work, so that thus the ripple of the Input current is reduced.

A Component reduction and more stable EMC conditions arise when the Clock generation system for the subsystems and the clock generation for the boost converter circuits are synchronized with each other and made up of a single common Oscillator and a common pulse generator can be derived.

A Cost reduction leaves achieve in this inverter system also in that the four transistors of the two half-bridge circuits with a single drive transformer be driven over a primary winding and four separate secondary windings features.

Very High switching frequencies can be achieved by using the transistors the half-bridge circuits of the MOSFET type.

Further Assembly advantages and easier spare parts attitude arises, if a power unit with an upstream boost converter circuit mechanically combined as a module assembly, so that by direct parallel connection of several such module assemblies Power components high overall performance can be realized.

A advantageous standardization arises when each of these module assemblies a separate cooling profile has.

These Features vary depending on the required use of the inverter system can be combined with each other in a wide range.

in the Field of welding technology It is particularly advantageous, many smaller power parts operate in phase offset with each other, because thereby the weight the needed Chokes is greatly reduced. This is especially important with portable machines. When operating inverters on the three-phase three-phase network of 3 × 400 V is a series circuit of the half-bridge circuits very advantageous, because when using MOSFET transistors takes the ampacity drastically decreases with increasing dielectric strength, making more economical solutions revealed because transistors used with half dielectric strength can be.

By Combining most of these features has created an inverter system, in a very small space with low weight a high output power reached. To emphasize here is the hitherto unequaled high control dynamics and ripple poverty of an inverter of this size and weight class. The Rules of harmonic components is fully satisfied. The modular system yields big economical advantages.

The Invention will be described with reference to an embodiment shown in the drawings explained in more detail. It demonstrate:

1 the basic circuit of a power unit according to the invention,

2 the control structure of an inverter system according to the invention,

3 a possible parallel connection of the half-bridge modules,

4 a possible series connection of the half-bridge modules,

5 an inverter system with upstream boost converter circuit and power rectifier and

6 an example of a module assembly.

In 1 you see, like a first half-bridge circuit 1a is constructed. Two transistors 10a and 10b are together with two freewheeling diodes 11a and 11b connected in a known manner to a so-called symmetrical Hafbbrückenschaltung. The supply is at a positive supply connection 33 and a negative supply connection 34 and comes with a buffer capacitor 43a supported. You can see that the main transformer 3 two primary windings 3a and 3b having. The first primary winding 3a is now in the bridge diagonal of the half-bridge circuit 1a built in, with in series with the primary winding, a saturable inductor 5a is switched. Furthermore, the primary current flows through a current transformer 4 , which is a primary current feedback 42 generated.

The second half-bridge circuit 1b is constructed as shown in a completely analogous manner. It should be noted that the primary winding 3b and the current transformer 4 as shown are connected so that the magnetization of the transformer 3 and the current in the current transformer 4 at conducting transistors 10a and 10b in the half-bridge circuit 1a is opposite than at lei border transistors 10c and 10d in the half-bridge circuit 1b , At the secondary winding 3c is now the known per se power doubler rectifier 6 connected. The standard circuit consists of two smoothing reactors 9a and 9b , each of which carries half of the output current. Two output diodes 7a and 7b serve the rectification. The two output diodes are the two additional saturable inductors 8a and 8b connected in series. The whole arrangement is considered a power part 2 designated.

In 2 is the power unit 2 marked as a block. Now the regulation is described. A main regulator 13 implements a current controller depending on the requirement 20 or a voltage regulator 21 , The current regulator 20 is with the output current actual value 16 supplied by a known current measuring system. At the same time, it receives an output current setpoint from a higher instance 18 , The voltage regulator 21 receives the output voltage actual value 17 and an output voltage setpoint 19 , If at the same time both a current controller 20 and a voltage regulator 21 are required, is a known per se and schematically illustrated Ablöseschaltung 39 provided, which passes the controller to the controller, the smaller command signal 14 generated. The guide signal 14 is a new current setpoint for a known current-mode controller 15 , The current-mode control becomes a very fast and precise primary current-actual value amount 22 needed. For this purpose, the bipolar primary current actual value 42 from the current transformer 4 in an amount generator 23 rectified. The guide signal 14 and the primary current-actual value amount 22 are in the current-mode controller 15 on a comparator 27 guided. It is now every half-bridge circuit 1a or 1b each a flip-flop memory 26a respectively. 26b assigned, via a drive circuit 28a respectively. 28b and a drive transformer 12 to the transistors of the associated Halbbrückenschal device 1a respectively. 1b leads. For example, the flip-flop memory 26a set, then the transistors 10a and 10b the half-bridge circuit 1a turned on - the same applies vice versa and mutatis mutandis for the other Flip-flop memory 26b in conjunction with the half-bridge circuit 1b ,

Turning on and off the flip-flop memory 26a and 26b worried a pulse generator 25 that of an oscillator 24 is fed. In the process, the two flip-flop memories 26a and 26b with a maximum of 50% duty cycle alternately set and reset. Represents the comparator 27 however, notice that the primary current-actual value amount 22 the guide signal 14 exceeds, then the flip-flop memory reset immediately without any delay. This will cause the power flow in the main transformer 3 immediately interrupted. The current limitation of the inverter system thus reacts without principle-related delay, since a delay-free image of the output current is contained in the primary current. When connecting several subsystems in parallel 49 It is now particularly advantageous to the oscillator 24 and the pulse generator 25 only once and for all subsystems 49 to provide together, since thus the phase position of the individual half-bridge circuits can fan out further and thus the ripple of the output current of the overall system can be drastically reduced.

In 3 is the parallel connection of the two half-bridge circuits 1a and 1b shown. This variant is advantageous in the operation of inverters on the single-phase supply network of 230V suitable.

In 4 is contrary to 3 a series connection of the two half-bridge circuits 1a and 1b shown. This creates a capacitive center 32 Located in the middle between the positive supply connection 33 and the negative supply connection 34 to come to rest. To the center 32 It is advantageous to use a monitoring circuit at each operating point of the inverter to be stable in the middle 29 for the symmetry of the two partial stresses 40a and 40b to have. Shown is an embodiment with two resistors 30a and 30b and two optocouplers 31a and 31b , The optocoupler 31a becomes conductive when the supply voltage 40a larger, the optocoupler 31 becomes conductive accordingly when the supply voltage 40b gets bigger. With the output signals 35 becomes the current mode knob 15 controlled so that by known means the drive signals of those half-bridge circuit 1a or 1b be blocked, which is the lower supply voltage 40 having.

In 5 is shown that the power unit 2 between the positive supply connection 33 and the negative supply connection 34 a known boost converter circuit 36 is connected upstream. This in turn is powered by a mains rectifier 37 via the positive rectifier connection 45 and the negative rectifier terminal 46 provided. The rectifier itself feeds itself from the supply network 38 , which is usually a single-phase network of eg 230V or as shown a three-phase network of eg. 3 × 400V is. For the parallel connection of several subsystems 49 It is now particularly advantageous, the guide signal 14 and the setpoint signal for the input current 41 parallel to all subsystems 49 so that the power distribution to the subsystems is optimal.

In 6 becomes a module assembly 44 shown which from a power section 2 and an associated boost converter circuit 36 consists. Such module modules can now be easily connected in parallel with the control technology according to the above features, which can be implemented very high output inverter.

Claims (30)

Inverter with two asymmetrical half-bridge circuits ( 1a . 1b ) alternating two separate primary windings ( 3a . 3b ) of a main transformer ( 3 ), in which at the secondary winding ( 3c ) of the main transformer ( 3 ) a current doubler rectifier ( 6 ), characterized in that with each primary winding ( 3a . 3b ) of the main transformer ( 3 ) a saturable inductance ( 5a . 5b ) is connected in series. Inverter according to claim 1, characterized in that the current doubler rectifier ( 6 ) two output diodes ( 7a . 7b ), each having a saturable additional inductance ( 8a . 8b ) is connected in series. Inverter according to Claim 1 or 2, characterized in that the saturable inductors ( 5a . 5b ) and additional inductances ( 8a . 8b ) are formed as ring cores are guided by the associated conductor. Inverter according to Claim 3, characterized that the ring cores made of amorphous or nanocrystalline strip material consist. Inverter according to Claim 3 or 4, characterized that the ring cores thermally conductive in pictures of cooling profiles or heat transfer bodies installed are. Inverter with two asymmetrical half-bridge circuits ( 1a . 1b ) alternating two separate primary windings ( 3a . 3b ) of a main transformer ( 3 ), in which at the secondary winding ( 3c ) of the main transformer ( 3 ) a current doubler rectifier ( 6 ), characterized in that a respective connection of the two primary windings ( 3a . 3b ) so by a stream converter ( 4 ) are guided, that this emits a summation current with alternating polarity. Inverter according to claim 6, characterized in that the current transformer ( 4 ) is designed as a compensation current transformer with a magnetic field sensor and detects resulting DC components. Inverter with two asymmetrical half-bridge circuits ( 1a . 1b ) alternating two separate primary windings ( 3a . 3b ) of a main transformer ( 3 ), in which at the secondary winding ( 3c ) of the main transformer ( 3 ) a current doubler rectifier ( 6 ) is connected, characterized in that it is provided with a cascade controller, wherein a first main controller ( 13 ) depending on the actual value ( 16 ) of the output current or the output voltage of a power unit ( 2 ) and depending on the setpoint ( 18 ) of the output current or the output voltage, a current regulator ( 20 ) or a voltage regulator ( 21 ) whose output signal is used as a reference signal of the main controller ( 13 ) can be fed to another controller, which as a current-mode controller ( 15 ) for the primary current of the main transformer ( 3 ) serves ( 2 ). Inverter according to claim 8, characterized in that the main regulator ( 13 ) both a current controller ( 20 ) as well as a voltage regulator ( 21 ), which in a detachment circuit ( 30 ) are linked so that the one who takes the lead, which the small command signal ( 14 ) generated. Inverter according to claim 8 or 9, characterized in that the main controller ( 13 ) is constructed as a digital controller with commercially available means of processor technology and that the output analog control signal ( 14 ) via a digital-to-analog converter generates as a current setpoint the current mode controller ( 15 ) can be fed. Inverter according to one of claims 8 to 10, characterized in that for the formation of the amount ( 22 ) of the actual value of the primary current for the current-mode regulator ( 15 ) the actual value ( 42 ) of the primary current from the compensation current transformer ( 4 ) with an amount generator ( 23 ) is rectified. Inverter according to one of Claims 1 to 11, characterized in that each half-bridge circuit ( 1a . 1b ) an oscillator ( 24 ) with a downstream pulse generator ( 25 ) is assigned to drive pulses for associated flip-flop memory ( 26a . 26b ), which are alternately set and reset, and that with the setting and resetting of these flip-flop memory ( 26a . 26b ) downstream drive circuits ( 28a . 28b ) the switching transistors ( 10 ) of the associated half-bridge circuit ( 1a 1b ) are switched on and off. Inverter according to one of Claims 8 to 12, characterized in that a comparator ( 27 ) the input of the current mode controller ( 15 ) forms that the comparator ( 27 ) the amount ( 22 ) of the actual value of the primary current with the amplitude of the reference signal ( 14 ) and that the vast amount ( 22 ) of the actual value of the primary current, the flip-flop memory ( 26a . 26b ) and the transistors ( 10 ) of the respective active half-bridge circuit ( 1a . 1b ) turns off. Inverter according to one of Claims 1 to 13, characterized in that a common supply voltage ( 40 ) both half-bridge circuits ( 1a . 1B9 feeds ( 3 ). Inverter according to one of Claims 1 to 13, characterized in that each half-bridge circuit ( 1a . 1b ) a separate supply voltage ( 40a . 40b ) and that the two supply voltages ( 40a . 40b ) are connected in series ( 4 ). Inverter according to claim 15, characterized in that the series connection of the supply voltages ( 40a . 40b ) a monitoring circuit ( 29 ), which determines the symmetry of the capacitive center connection ( 32 ) with respect to the positive supply voltage ( 33 ) and the negative supply voltage ( 34 ) and that the output signal ( 35 ) of the monitoring circuit ( 29 ) characterizes the asymmetry and the direction of the same. Inverter according to claim 16, characterized in that the output signal ( 35 ) of the monitoring circuit ( 29 ) the drive pulses of that half-bridge circuit ( 1a . 1b ), which depends on the currently smaller supply voltage ( 40a or 40b ), blocked or shortened until the symmetry of the supply voltages ( 40a . 40b ) is restored. Inverter with two asymmetrical half-bridge circuits ( 1a . 1b ) alternating two separate primary windings ( 3a . 3b ) of a main transformer ( 3 ), in which at the secondary winding ( 3c ) of the main transformer ( 3 ) a current doubler rectifier ( 6 ), characterized in that two half-bridge circuits ( 1a . 1b ) and a main transformer ( 3 ), possibly provided with the saturable inductors ( 5a . 5b ), as well as a current transformer ( 4 ) and a current doubler rectifier ( 6 ), possibly provided with the seed applicable additional inductors ( 8a . 8b ), to the power unit ( 2 ) are summarized. Inverter according to claim 18, characterized in that a power unit ( 2 ) with a drive transformer ( 12 ), Drive circuits ( 28 ) and a current-mode controller ( 15 ) a subsystem ( 49 ) form. Inverter according to claim 19, characterized in that several subsystems ( 49 ) are connected in parallel (terminals 33 and 34 ) and a common output (terminals 47 and 48 ), and that the guide signal ( 14 ) the inputs of all current-mode controls ( 15 ) of subsystems ( 45 ), this identical command signal ( 14 ) from a common main controller ( 13 ) of the overall system and the actual value ( 16 ) of the output current represents the current of the entire system. Inverter according to one of Claims 12 to 20, characterized in that the oscillator ( 24 ) with a downstream pulse generator ( 25 ) for all subsystems ( 49 ) and that the setting of the flip-flop memory ( 26a . 26b ) for the various half-bridge circuits ( 1a . 1b ) is distributed over as many phase-offset times as possible in order to minimize the ripple of the output current. Inverter according to one of claims 18 to 21, characterized in that the power unit ( 2 ) on the input side (terminals 33 and 34 ) a known boost converter circuit ( 36 ) with mains rectifier ( 37 ), via which the current consumption from the supply network ( 38 ) is controllable. Inverter according to Claim 22, characterized in that the boost converter circuit ( 36 ) large power of several sub-boost converter circuits ( 36a . 36b ) smaller power is formed in parallel. Inverter according to Claim 23, characterized in that the sub-boost converter circuits ( 36a . 36b ) a setpoint signal for the setpoint ( 41 ) of the input current that can be fed to all partial boost converter circuits ( 36a . 36b ) is identical. Inverter according to claim 4, characterized in that the partial boost converter circuits ( 36a . 36b ) are out of phase controlled to reduce the ripple of the input current. Inverter according to one of claims 18 to 25, characterized in that the clock generating system for the power parts ( 2 ) and the partial boost converter circuits ( 36a . 36b ) are synchronized with each other and from the common oscillator ( 24 ) and the common pulse generator ( 25 ) are derived. Inverter according to one of Claims 1 to 26, characterized in that the half-bridge circuits ( 1a . 1b ) four transistors ( 10a . 10b . 10c . 10d ) with a single drive transformer ( 12 ), which is connected to a primary winding ( 12a ) and four separate secondary windings ( 12b . 12c . 12d . 12e ) is provided. Inverter according to one of Claims 1 to 27, characterized in that the half-bridge circuits ( 1a . 1b ) are constructed with transistors of the MOSFET type. Inverter according to one of claims 18 to 28, characterized in that a power unit ( 2 ) with a boost converter circuit ( 36 ) a mechanical module assembly ( 44 ) forms that several, such module assemblies ( 44 ) and that these module assemblies ( 44 ) by input side (terminals 45 and 46 of the rectifier) and the output side (terminals 47 and 48 the output terminals) are combined in parallel to a power component of high total power. Inverter according to claim 29, characterized in that each module assembly ( 44 ) has its own cooling profile.