DE2652275A1 - Sinusoidal mains frequency AC extraction - is performed by filter including rectifier and boosts converter with DC intermediate system - Google Patents

Abstract

A system is used for extracting almost purely sinusoidal mains-frequency current from a.c. voltage or three-phase voltage mains. It transfer the obtained electrical energy into electrically coupled d.c. voltage systems or d.c. voltage intermediate systems, without losses dependent on the design principle used. The supply a.c. voltage mains terminals are connected to an input filter, an uncontrolled rectifier, a boost-converter and the d.c. voltage system or d.c. voltage intermediate system. The boost-converter has at least one electric choke and one diode in boths its long limbs, the latter being connected together via an electronic switch. The d.c. voltage or d.c. voltage intermediate system's voltage is greater than that of the a.c. voltage supply mains, and the switch-over frequency of the electronic switch is high relative to that of the supply a.c. voltage mains.

Description

Description and claims

Facility without principle-related losses for the withdrawal of practical purely sinusoidal, line-frequency current from AC or three-phase systems and for transferring the extracted electrical energy into galvanically connected DC voltage systems or DC voltage intermediate systems The electrical energy networks, in particular those of highly industrialized countries are increasingly affected by harmonic currents influences which are caused by power electronics devices.

Above a certain level, these harmonic currents interfere with both the operation of the energy networks as well as other consumers connected there. It The task is therefore that of direct current systems or alternating and three-phase systems With a frequency not connected to the grid, the electrical energy required is the alternating or feeding Three-phase voltage networks via practically purely sinusoidal, network-frequency currents and to be taken as possible without losses due to the principle.

This object is achieved by the invention presented here.

In describing them, let us first focus on the extraction of energy AC voltage networks and only afterwards on the corresponding task in three-phase networks. Correspondingly, FIG. 1 shows, starting from the left, initially schematically a feeding AC voltage network (1), än its terminals one after the other an input filter terminating with a shunt capacitor (23 and acting as a low-pass filter) (3), an uncontrolled rectifier in a bridge circuit (4), a DC boost converter (5) in potential-connecting design (English designation: boost converter) and a DC voltage system or DC voltage intermediate system beginning with a shunt capacitor (6) are connected downstream, the DC step-up converter being configured in this way is that in its two longitudinal branches at least one electrical throttle (7) - hereinafter referred to as storage choke - and at least one diode (8) - hereinafter Called control diode - are arranged and the two longitudinal branches in the transverse direction via an electronic switch (9) - hereinafter referred to as the control switch - are connected to each other, each from the left, from the input side of the Seen from the step-up converter, the storage choke (s) before that through the control switch formed shunt arm and the control diode (s) are inserted after this shunt arm. A fast electronic circuit breaker is used as the control switch, which is exemplified in Fig. 1 as a bipolar power transistor.

Instead, of course, field effect transistors, Switchable thyristors (GTO's) or switchable thyristor combinations can be used.

To ensure the function of the boost converter (5 must be guaranteed be that the voltage of said DC voltage system or DC voltage intermediate system (6) is higher than the periodic peak value of the nominal voltage of the feeding AC voltage network (1).

FIG. 2 again shows the step-up converter from FIG. 1 together with the typical courses of the current iL (10) through the storage choke, which are shown here may have the inductance L of the current i5 (11) through the control switch and the current iD (12) through the setting diode. Furthermore, are entered in Fig. 2 the time interval Te (13) - hereinafter referred to as the duty cycle - during this the actuator switch is electrically conductive, the time interval Ta (14) - in the following Called switch-off time - during which the control switch is locked, and that Time interval T1 (15) - hereinafter referred to as the gap duration - during which the current iL has the value zero due to the storage choke.

It can easily be shown that if the gap duration T1 is constant chooses to zero, i.e., if you just turn the control switch then switches on again when the inductor current has reached the value zero, the middle one The input impedance of this step-up converter has the value 2L.

T e for constant. The step-up converter behaves in the switch-on period i.e. with regard to the arithmetic mean of the current it consumes like an ohmic resistance, i.e. this arithmetic mean value of the input current iL is proportional to the arithmetic mean of the input voltage UE (16). Of course, this only applies to positive values of the input voltage. Should accordingly the task mentioned, a current can be taken from an AC voltage network, whose arithmetic mean value the arithmetic mean value of the feeding AC voltage is proportional, so the step-up converter (17) according to FIG. 3 must have a rectifier (18) are connected upstream, which saves an expensive and heavy transformer is expediently carried out in a bridge circuit. So that flows there before the Bridge rectifier sketched in Fig. 3 top right, with the switching frequency the actuator switch modulated alternating current iwm (19) and the step-up converter gives to the DC voltage system or DC voltage intermediate system in FIG. 3 Sketched at the bottom right, with the switching frequency of the control switch and twice that value modulated the frequency of the feeding AC voltage system Direct current from him (20).

To ensure that the feeding mains with a practically pure sinusoidal current is loaded, so it is necessary between the bridge rectifier and the feeding AC voltage network an AC filter to switch, which, in order not to impair the function of the step-up converter, on the side to which the rectifier is connected, with a capacitor should be completed.

In order to ensure that the voltage of the energy absorbing DC voltage system or

DC voltage intermediate system despite the supply of the double modulated Direct current remains a largely pure direct voltage, is parallel to his To switch input terminals a capacitor, which also ensures that the Boost converter not due to line inductance on the DC voltage side gets destroyed.

By adding these two smoothing units, this results in 3 shows FIG. 1 presented at the beginning with the difference that there the DC voltage side Smoothing capacitor in the energy-absorbing DC voltage system or DC voltage intermediate system is involved.

From the diagrams in Fig. 3 it is immediately clear that in turn, the approximation of the absorbed current to the sinusoidal shape in particular is good, and on the other hand the AC filter (3), the storage choke (7) and the DC side smoothing capacitor in Fig. 1 turn out to be particularly small and light, all in all particularly favorable conditions exist when the switching frequency of the control switch (9) as large as possible compared to the frequency of the AC power supply is chosen. With electronic circuit breakers available today, maximum switching frequencies from 100 kHz to 200 kHz even in the range of higher powers already securely implement.

If, as previously assumed, the gap duration T is chosen to be zero, i.e. the control switch is switched on again when the throttle current has reached the value zero, the voltage taken from the feeding AC voltage network can be used Power can only be brought about by changing the duty cycle T e. Also corrections to the sinusoidal shape of the recorded alternating current, which are due to the non-ideal properties of the components used are required, can then only be carried out by modulating this duty cycle. It is the latter limitation is not very burdensome. The first limitation on the other hand, can be very annoying because they for a reduction in consumed power towards the value zero an increase in the switching frequency towards the value infinitely required.

This restriction does not apply - and it can then also be used, for example, with constant Switching frequency can be worked - if both the duty cycle and the The switch-off duration of the control switch can be changed.

In FIG. 4, the device according to FIG. 1 is shown again on the right. In addition, the characteristic currents and voltages are indicated there.

Their time courses are shown on the left in FIG. 4, specifically in the event that there is always a finite gap duration, the current through the So storage choke sits on the zero line once in each switching cycle.

One recognizes immediately from these curves that in this case both for variable as well as constant switch-on duration over the switch-off duration or

the gap duration coupled with this, as well as the sinusoidal shape of the input current ensure as well as the desired effective value of the input current and thus the desired power can be set.

In detail are shown in Fig. 4: the input filter (3) incoming alternating current iW (21), the voltage of the supplying alternating voltage system uW (22), the voltage at the output of the input filter uwm (23), the modulated alternating current flowing to the bridge rectifier (24), the current through the storage choke iL (25), the voltage of the DC voltage system or

of the DC voltage intermediate system uG (26), and that of the DC voltage system or the modulated direct current iGm flowing into the direct voltage intermediate system (27).

The DC voltage system or DC voltage intermediate system (6) in Fig. 1, both an energy absorbing Be a direct current system in which the electrical energy consumed is beneficial and is appropriately converted into other forms of energy, it can be with him but also, as the name suggests, a DC voltage intermediate system, from which the energy is fed into any, Potential-related coupled or separate, energy-absorbing direct current systems or alternating or three-phase systems of any frequency is transmitted.

In the device according to the invention itself was consciously on one Galvanic isolation is dispensed with, as there is such in downstream DC converters or make inverters much smaller, lighter and more cost-effective leaves.

As already became clear from Figure 3, the control switch is after its shutdown with the voltage UG of the energy absorbing direct voltage system respectively. DC voltage intermediate system loaded. So this tension shouldn't be too great are so as not to overload the control switch.

On the other hand, it must always remain greater than the peak value of the Voltage of the supplying AC voltage network, otherwise the current through the storage choke is no longer dismantled as required after the control switch has been switched off.

It is therefore advisable to use this voltage UG of the direct voltage system or DC voltage intermediate system by influencing the power supply to this (i.e. by influencing the effective value of the input filter incoming alternating current) and / or influencing the power dissipation of to keep this largely constant in such a way that if the value of UG less power is supplied and / or more power is dissipated and that at a too low a value of UG is influenced in the opposite way.

If no special measures are taken in favor of the control switch, so its performance is mostly due to its power dissipation Switching off limited. It is therefore advisable to protect the control switch from its power dissipation to relieve when switching off.

FIG. 5 shows the step-up converter from FIG. 2 after adding one known establishment which the control switch (28) from his Power loss stress when switching off via a so-called RCD network (29) exonerated. The functioning of this relief device (29) is from the relevant literature known.

FIG. 6 again shows the step-up converter from FIG. 2, now after Supplement to an arrangement without principle-related losses to relieve electrical loads or electronic one-way switch from their power dissipation Switching off (30) according to German patent application P 26 49 385.6.

The function of this arrangement (30) is described in the patent application mentioned described in detail.

It has the advantage of working without losses due to the principle and is therefore also suitable for high switching frequencies of the control switch (31). This property is according to the present with regard to the use in a facility Invention particularly advantageous because here. - as already stated - the step-up converter should be operated with high switching frequencies.

FIG. 6 a again shows the step-up converter from FIG. 2, now after Supplement to another facility without loss of workload due to the principle electrical or electronic one-way switches from their power dissipation when switching off (107) according to German patent application P 26 50 673.0. The function of this arrangement (107) is in this second-mentioned patent application again described in detail.

It also works without losses due to principle and is as a result particularly with regard to use in a device according to the present invention advantageous.

If the step-up converter contained in the device according to the invention, as shown in the diagrams in FIG. 3 and FIG. 4, always after switching off only switched on again when the current through the storage choke has previously been switched on Has assumed a value of zero, the control switch remains from a power loss load spared when switched on.

If you deviate from this, however, you are working with a non-incomplete one Current through the storage choke, then the control switch without additional precautions stressed during switch-on with a considerable switch-on power loss. This can be done in a known manner corresponding to the illustration in FIG. 7 by inserting a so-called switch-on throttle (32) can be remedied. However, this has the consequence that then the reverse voltage stress when switching off the control switch (33) adopts impermissibly high values. Again in a known way, by the insertion of a reverse voltage limiting Zener diode (34) can be remedied.

In addition to the one shown in Fig. 7, there are other devices, which make it possible to use the control switch both from high power dissipation when switching on as well as excessive reverse voltage stress when switching off to free.

FIG. 7 a again shows the step-up converter from FIG. 2, now supplemented both to a device (108) for liberating electrical or electronic One-way switch with high power dissipation stress during switch-on and excessive reverse voltage stress when switching off according to German patent application P 26 51 492.1 as well as a device (109) without principle-related losses for Relief of electrical or electronic one-way switches from their power dissipation when switching off according to German patent application P 26 50 673.0.

As is clear from both the diagrams in FIG. 3 and those in FIG. 4 becomes, in the device according to the invention, the energy-absorbing DC voltage system or a DC voltage intermediate system is supplied with a pulsating direct current iGm, which both with the switching frequency of the control switch and with double value the frequency of the feeding AC voltage network is modulated.

About the DC voltage system or DC voltage intermediate system and in particular the smoothing capacitor connected in parallel with this from the particular severe stress with the alternating current component of twice the mains frequency to relieve, it can be very useful with the device according to the invention, corresponding to the illustration in FIG. 8 to the DC voltage system or DC voltage intermediate system (35) to switch an electrical suction circuit (36) in parallel, its resonance frequency is twice as high as the frequency of the AC power supply.

As already explained, the control switch, which is in the device according to the invention is included, from a power loss stress spared when switched on, if it is switched on or switched on again at the earliest when no significant current flows through the storage choke.

Particularly simple conditions arise when the control switch is switched on again immediately if there is no significant value due to the storage choke Current flows more (see Fig. 3). If the duty cycle of the Control switch is given constant, so results like the one at the beginning have already shown, even with small ones, only on the switching frequency input filters matched to the control switch are practically purely sinusoidal Input current. However, this sets ideal properties of the components used in advance. The result is that this prerequisite is not given in practice in real circuits of this type, certain deviations from the input filter flowing into it Alternating current of the desired sinusoidal shape. An overall circuit operated in this way but can still be very advantageous because the effort required is particularly high is low. A dosage of the DC voltage system or the DC voltage intermediate system The electrical power supplied can then take place, for example, in such a way that the control switch in each case for whole multiples of full oscillations of the voltage of the feeding AC voltage network completely blocked and then again for whole multiples of full oscillations the voltage of the feeding AC voltage network for its described above Function is released again.

To compensate for the influences of the non-ideal properties of the used Components, it can be useful, the duty cycle of the control switch above one synchronized with the AC power supply system, digital or analog to modulate implemented function generator, with twice the frequency of the feeding AC voltage network.

Fig. 9 shows the typical curve which the duty cycle T (37) must have as a function of time e, if the flowing into the input filter Alternating current should have a sinusoidal shape that is as closely approximated as possible.

Fig. 10 shows the basic arrangement of the device according to the invention according to Fig. 1 after expansion by one with the feeding AC voltage network (38) synchronized, digital or analog implemented, time-dependent function generator (39), which influences the control unit (40) of the control switch (41), such that the duty cycle T e with twice the frequency of the feeding AC voltage network is modulated in the desired manner (cf. FIG. 9).

Another way the influences of the non-ideal properties To compensate for the components used, the duty cycle of the Control switch via a function generator, which is based on the instantaneous value a voltage is carried by a phase rotation causing a phase lag and subsequent Full wave rectification from the voltage of the feeding AC voltage network can be formed.

11 shows the basic arrangement of the device according to the invention according to Fig. 1 after expansion by one connected to the feeding AC voltage network Phase rotation device (42), from which an additional full-wave rectifier (43) the function generator (44) is controlled, which the duty cycle Te of the control switch as required with twice the frequency of the feeding AC voltage network (45) modulated.

Another way that influences the non-ideal properties To compensate for the components used, the duty cycle of the Control switch to be specified by a controller, which based on the comparison of the setpoint and actual value of the alternating current flowing to the input filter the sinusoidal shape and / or the rms value of the current flowing to the input filter concerned.

The setpoint for this controller can be derived from the voltage of the feeding AC voltage network are derived. Since, as Fig. 4 has clearly shown, the Voltage before the bridge rectifier (4) in Fig. 1 of the voltage of the feeding AC voltage network lags behind in its phase position, should the Setpoint value for the named controller in this case from the voltage of the feeding AC voltage network can be derived that initially generated a voltage via a phase rotation device which lags the voltage of the supply network in its phase position Off this voltage is then the controller setpoint in a simple manner via modules without Form timing behavior.

Fig. 12 shows the basic arrangement of the device according to the invention according to Fig. 1 after expansion by such a control system.

The actual value of the input filter is used here as an example AC current tapped at a measuring resistor (46), one - ideally possible - Full-wave rectification (47) and then the current controller (48) as the actual value fed. Its setpoint is taken from the feeding AC voltage network (49) a phase rotation device (50) and a Vpllweggleichricht - also ideally possible - (51) won.

The function of such a control device can be improved considerably if the switch-on duration of the control switch is also voltage-dependent or time-dependent function generator is precontrolled.

By way of example, FIG. 13 shows the arrangement according to FIG. 12 after completion a precontrol of the duty cycle T e via a snanning-dependent Function generator (52).

Instead of a direct specification of the duty cycle Te, as was previously the case has been described, a corresponding indirect specification can of course also be used step. This is the case, for example, when the control switch then is switched off again when the current through the storage choke has reached a limit value has reached, which with twice the frequency of the feeding AC voltage network is prescribed periodically. A pretty good approximation of the input filter inflowing alternating current to the desired sinusoidal shape can then already be achieved if the specified limit value for the current through the storage choke is proportional is prescribed to the instantaneous value of a voltage, which in already explained Way by a phase rotation causing a phase lag and a subsequent one Full-wave rectification formed from the voltage of the AC power supply can be.

A very good approximation of the alternating current flowing into the input filter to the desired sinusoidal shape can be achieved if the limit value mentioned for the current through the storage choke is specified via a function generator, which either is performed in the manner already explained from the instantaneous value of a voltage that is carried out by a phase rotation causing a phase lag and a subsequent full wave rectification can be formed from the voltage of the feeding AC voltage network, or , likewise in the manner already explained, than with the feeding AC voltage network synchronized, digital or analog implemented, time-dependent function generator is trained.

An even better approximation of that flowing into the input filter Alternating current to the desired sinusoidal shape can finally be achieved again, when the limit value of the current through the storage choke is specified by a controller is which, in the manner already explained, the setting of the sinusoidal shape and / or of the effective value of the current flowing to the input filter.

The function of this last-described arrangement can be repeated improve by the fact that the limit value of the current through the storage choke additionally is precontrolled via a time- or voltage-dependent function generator.

As can already be seen from what has been said so far, it can be very good be advantageous, the time- or voltage-dependent function generator described for the switch-on time of the control switch or for the limit value of the current to influence the storage choke via a signal voltage and via this signal voltage in the way of a control or regulation the setting of the sinusoidal shape and / or the ~ rms value of the alternating current flowing to the input filter obtain.

FIG. 14 shows the arrangement according to FIG. 11 after expanding the voltage-dependent function generator (53) by an additional one Signal voltage input (54) for the control voltage ust (55), which e.g. directly as a control variable for the DC voltage system or DC voltage intermediate system (56) supplied electrical power can serve.

It was already stated earlier that the tax options in the device according to the invention expand significantly when the control switch is only switched on again when the Current through the storage choke a certain time interval, the so-called.

Gap duration has expired.

This creates the possibility of supplementing one or in combination with one of the previously control procedure described the gap duration of the current through the storage choke.

This can be done in such a way that the gap duration of the current through the Storage choke via a synchronized with the feeding AC voltage network, digital or analog implemented function generator is specified and this function generator - possibly additionally - influenced by an additionally acting signal voltage which is used to set the sinusoidal shape and / or the effect invert of the input filter flowing alternating current is used.

However, it can also be more advantageous to reduce the current gap duration controlled by the storage choke via a function generator, which of the instantaneous value a voltage is carried by a phase rotation causing a phase lag and subsequent full-wave rectification from the voltage of the supplying AC voltage network can be formed and this function generator - possibly in addition - to Setting of the sine shape and / or the effective value of the input filter To influence alternating current via a supplementary acting signal voltage.

In both cases, the signal voltage applied to the function generator acts, e.g. from a Controller are specified, which the Setting of the sinusoidal shape and / or the effective value of the input filter AC worried.

Of course, the gap duration of the current through the storage choke can also be specified directly by a controller, which controls the setting of the Sinus form and / or the effective value of the current flowing to the input filter causes, preferably such that the setpoint for this controller via blocks without time behavior is formed from a voltage which corresponds to the voltage of the feeding AC voltage network lags behind in their phase position.

15 shows an example of such an arrangement, consisting of the basic arrangement of the device according to the invention according to FIG. 1, one in addition introduced control for the duty cycle T e by means of a voltage-dependent Function generator according to FIG. 11 and an additionally introduced regulation of the sine shape and the effect infert of the alternating current flowing into the input filter the gap duration T1 A phase rotation device is shown in detail in FIG (57) for the voltage of the feeding AC voltage network (58), a measuring resistor for the input filter (59) to be supplied Alternating current, a - if possible ideal - full-wave rectifier (60), which the actual value for the Controller (61) supplies another - ideally possible - full-wave rectifier (62), which supplies the setpoint for the controller (61) and via the function generator (63) the duty cycle T of the control switch (64) e prescribes while the controller (61) determines the gap duration T1 of the current through the storage choke. Both will effected via the control unit (65) of the control switch (64).

From what has been said so far it can be seen that there are numerous, very advantageous controls for the basic version of the device according to the invention it is very important to get a signal in a simple way that the Current through the storage choke has become zero. It can be used for this make that the current through the storage choke because of the carrier jam effect of the The setting diode changes its polarity for a short time after it has become zero, but then, after removing charge carriers from the setting diode, with practically sudden Reversal of the sign of its rate of change tends towards zero. If you bring an additional, small amount loaded auxiliary winding, its output voltage returns each time the Polarity of the rate of change of the current through the storage choke hers Sign changes and thus provides an excellent signal that the current is through the storage choke has become zero or no longer has a significant size.

However, there is a problem in that when the The voltage of the AC supply network has the value zero or very small values has, no or no significant inductor current flows and as a result the signal mentioned for the beginning of the gap period is omitted.

However, this can be said of the practically important control switches, especially with bipolar power transistors, but also with gate-turn-off thyristors (so-called GTO's) help by influencing the control path of the semiconductor when it is switched off with such a high power that this control path with high reverse voltage, preferably operated in its zener range.

This also results in such a high level in the main circuit of the semiconductor Current caused that applied to the storage choke Auxiliary winding the signal for the beginning of the gap period can also be tapped when the voltage of the AC supply network is zero or very small values having.

With the device according to the invention, three-phase voltage networks can of course also be used practically purely sinusoidal, mains-frequency current taken and the corresponding Energy galvanically connected DC voltage systems or DC voltage intermediate systems are fed.

In a now trivial combination in that three inventive Devices each to two outer conductors of the three-phase voltage network or to each an external conductor of the three-phase voltage network and its existing or supplementary formed center conductors are connected and the three-phase voltage network electrical energy in three galvanically separated DC voltage systems or DC voltage intermediate systems is convicted.

However, there is a desire to use the voltage taken from the three-phase network Energy in a uniform DC voltage system or DC voltage intermediate system to convict. This can be done in accordance with the illustration in FIG can be achieved in a very simple manner in that the three boost converters (66) uniformly and simply connected to one another at their DC voltage outputs will.

However, this has various disadvantages, some of which are quite serious. On the one hand, the function of this circuit must be ensured in principle Voltage UG of the DC voltage system or DC voltage intermediate system (67) - be times larger than when the three boost converters are set to three different, galvanically separated DC voltage systems or

DC intermediate systems would work, on the other hand result there are considerable restrictions on the location of the switch-on and switch-off times of the three boost converters relative to one another or - associated with this - poor utilization ratios this step-up converter and its components.

The disadvantages mentioned in the second place can be remedied by that the transmission of electrical energy from the three boost converters to the common DC voltage system or DC voltage intermediate system using additional Decoupling diodes takes place.

Fig. 17 shows an arrangement in which the three according to the invention Facilities at each an outer conductor of the three-phase voltage network (68) and on its existing or additionally formed center conductor t69) are connected.

The boost converters (70) have the same structure and are on the output side in a uniform manner to the DC voltage system or DC voltage intermediate system (71) connected. In addition, three decoupling diodes (72) are inserted so that that the boost converters now contain a diode in each output line.

This eliminates the disadvantages mentioned in the second place above.

This also applies to the arrangement shown in FIG Comparison with that according to FIG. 17 with the same current carrying capacity of the control switches (73) allows a higher output power, since the three devices according to the invention each connected to two outer conductors of the feeding three-phase voltage network (74) are.

The input filters are also shown here - only as an example (75) constructed symmetrically and also the step-up converter (76) in a symmetrical manner built with two storage chokes (77) each. The decoupling diodes (78) are as in Fig. 17 inserted so that the boost converters (76) are now in each output line a diode is included.

Both arrangements, that of Fig. 17 and that of Fig. 18, have but still the disadvantage that the voltage UG of the common DC voltage system or DC voltage intermediate system -J3rfold must be greater than if the three boost converters to three different, galvanically separated DC voltage systems or DC voltage intermediate systems would work.

This is more available today due to the limited voltage load capacity Control switch, a particularly serious disadvantage, is caused by the arrangement according to Fig. 19 avoided. With her the three devices according to the invention are again each to an outer conductor of the three-phase voltage network (79) and to its existing or additionally formed center conductor (80) connected.

Your three step-up converters (81) initially work on their outputs to one capacitor (82) each functioning as a buffer store. These three capacitors transmit the electrical energy flowing to them in a cyclical-symmetrical manner Sequence to the common DC voltage system or DC voltage intermediate system (83) what thyristor pairs (84) and a common throttle (85) takes place, which ensures that the buffer -Capacitors when the associated thyristor pair is enabled, the voltage UG is not suddenly applied of the common DC voltage system are discharged. Except for the very quickly current transfer from one thyristor pair to the next is here in each case only one thyristor pair conductive and thus only one intermediate storage capacitor the energy absorbing DC voltage system (83) electrically connected.

The advantage of this arrangement has already been mentioned. The reverse voltage stress the control switch is not higher than in the case of separately working individual systems. This also applies to the arrangement shown in FIG. With her is from everyone of the thyristor pairs introduced in FIG. 19, one copy is omitted, while the other remained, in such a way that in every connection line from the boost converters to the common DC voltage system or

DC voltage intermediate system at least one valve section remains, be it in the form of the setting diode itself or in the form of the remaining thyristor (87). The disadvantage of this simplified arrangement according to FIG. 20 compared to the complete one according to FIG. 19 there are restrictions with regard to the definition of the ignition timing the different thyristors relative to the phase position of the feeding voltage system to expression.

From the explanations and diagrams made so far, it emerged that that in solving the problem described above, the use of direct current boost converters in potential-connecting design (English designation: boost converter) especially is advantageous. This also applies to the utilization of the boost converters in these boost converters used control switches and their protection against overloads resulting from overvoltages could result in the feeding AC or three-phase voltage network. As a disadvantage must be accepted for the fact that these boost converters directly fed DC voltage systems or DC voltage intermediate systems or intermediate storage capacitors Must have voltages which are greater than the peak values of those alternating voltages which are connected to the AC connections of the bridge rectifiers connected upstream of the boost converters issue.

This restriction does not apply if instead of the previously used one DC boost converter in potential-connecting design (boost converter) so-called DC boost and buck converter in potential-connecting Execution (buck-boost-converter) can be used.

For this solution to the problem described at the outset, FIG. 21 shows starting from the left, initially again a feeding AC voltage network (88), at the terminals of which one after the other a shunt capacitor (89) terminates, Input filter (90) acting as a low-pass filter, an uncontrolled rectifier in a bridge circuit (91), a DC step-up and step-down converter (92) in a potential-connecting design (English designation: boost converter) and a starting with a shunt capacitor DC voltage system or DC voltage intermediate system (93) are connected downstream, wherein the DC step-up and step-down converter is designed such that in its two longitudinal branches at least one electronic control switch (94) and at least one setting diode (95) are arranged, and the two longitudinal branches in Are connected to one another in the transverse direction via an electrical storage choke (96), where, from the left, from the input side of the step-up and step-down converter Seen here, the control switch (s) before the one formed by the storage choke Cross arm and the control diode (s) are inserted after this cross arm.

FIG. 22 again shows the step-up and step-down converters from FIG. 21 together with the typical curves of the current i5 (974 through the control switch, the current iL C98) through the storage choke and the current iD (99) through the control diode.

Furthermore, the duty cycle T (100) is entered in Fig. 22 of the control switch, the switch-off duration Ta (101) of the control switch and the Gap duration T1 (102) of the current through the storage choke.

In FIG. 23, the step-up and step-down converter (103) is a bridge rectifier £ 104) upstream.

The flow in FIG. 23 on the right therefore flows there in front of the bridge rectifier AC current sketched above, modulated with the switching frequency of the control switch to (105), and the step-up converter outputs to the DC voltage system or DC voltage intermediate system that sketched in Fig. 23 at the bottom right, with the switching frequency of the control switch and the double value of the frequency of the feeding AC voltage system modulated Direct current from him (106).

No special explanation is required that the performance the device according to the invention can be increased in that the contained in it DC chopper by a combination of two or more parallel-connected, complete DC choppers is replaced. But then you will try to find the different Combine storage chokes to form a common storage choke. This is then possible without difficulty if the various control switches are dynamic are decoupled from each other.

Fig. 24 shows a device according to the invention, in which the originally contained DC boost converter by a combination (110) of two parallel-connected The step-up converter is replaced, the control switch (111) and associated control diodes (112) are dynamically decoupled from one another via a so-called suction throttle (113) and their originally separate storage chokes to form a common storage choke (114) are combined, with the connection facing away from the circuit input (115) this common storage throttle (114) to the center (116) of the suction throttle (113) is performed.

After the introduction of this suction throttle, the two control switches (111) can be switched on and off simultaneously without difficulty, since the suction throttle a symmetrical distribution of the current through the storage throttle on the two control switches and - after their switching off - on the two setting diodes also enforced when the forward voltages of these Components differ somewhat from one another.

In the DC / boost converter combination shown in FIG (110) the two control switches can also be switched on and off in this way that the switch-on times or the switch-off times of one of the two Control switch in the middle of the time interval between two switch-on times or between two switch-off times of the other control switch. In order to result for the electrical potential of the circuit input facing away from the circuit Connection (115) of the common storage choke has the following conditions: If both control switches (111) conduct, this point (115) takes the potential of the negative Rail (117) of the supplied DC voltage system (118) on> if both control switches block, the potential of this point (115) is the same as that of the positive Rail (119) of the fed DC voltage system and, if a control switch locks and the other forwards, this point assigns the arithmetic mean of the Potentials of the positive and the negative Rail of the fed DC voltage system. This can be used by the common storage choke (114) reduce the clamping time area to be taken up, thereby saving material and volume is made possible at this throttle.

Furthermore, with this mode of operation, based on the total transmitted power, a reduction in the transmission losses in the control switches. This second mode of operation is therefore fundamentally very advantageous. Provided but also here with a current through the storage choke that is on the zero line (114) can be in the range of mean instantaneous values of the voltage of the AC power supply system difficulties arise in that the Current through the storage choke increasing or decreasing voltage becomes very small and thus set comparatively low switching frequencies. Through this can in turn undesirably or impermissibly high harmonics in the input filter (120) flowing alternating current are caused. This can be done according to the invention thereby avoid that in this area of the input voltage to the previously described Control principle is passed over at which the two control switches (111) can be switched on and off at the same time.

In the described arrangement, the one facing away from the circuit input Connection (115) of the common storage choke (114) when a control switch blocks and the other conducts the arithmetic mean of the potentials of the positive and the negative rail of the fed DC voltage system. This potential can be increased or decreased by the connection points of the setting diodes or the control switch is shifted towards the center of the suction throttle will.

FIG. 25 shows, by way of example, the arrangement according to FIG. 24 after the Connection points of the actuator diodes (121) somewhat in the direction of the center point (122) of the The suction throttle (123) have been relocated. Thus, the one facing away from the circuit input Connection (124) of the common storage choke (125) when one of the two Control switch (126) conducts and the other blocks, a slightly higher potential as the arithmetic mean of the potentials of the positive (127) and the negative (128) rail of the fed DC voltage system (129).

Fig. 26 shows a device according to the invention, in which in more consequent Continuation of the thought the dynamic decoupling of the actuator switches together with the associated power controller diodes for DC power controllers operated in parallel Combined storage choke of the originally included DC boost converter replaced by a combination (130) of four step-up converters connected in parallel is whose control switch (131) and associated control diodes (132) via a Configuration of three suction throttles (133) are dynamically decoupled from one another and their originally separate storage chokes to form a common storage choke (134) are combined, with the connection facing away from the circuit input (135) this common storage throttle (134) to the center of the suction throttle (133) is led.

After the introduction of this configuration of three suction throttles you can the four control switches (131) again without difficulty, each at the same time or switched on and off cyclically symmetrically offset from one another. In the second-mentioned mode of operation, the potential of the circuit input changes remote connection (135) of the common storage choke (134) now in five Stages.

A larger number of control switches can also be used in a completely analogous manner dynamically decoupled operated in parallel, provided the total number the control switch is an integer power of the number 2.

L e r s e i t e

Claims (38)

Device without loss of principle due to the principle of extraction of practically purely sinusoidal, line-frequency current from AC voltage networks and. to convert the withdrawn electrical energy into galvanic connected DC voltage systems or DC voltage intermediate systems, thereby characterized in that the two terminals of the feeding AC voltage network one after the other an input filter terminating with a shunt capacitor and acting as a low-pass filter, an uncontrolled rectifier in a bridge circuit, a DC boost converter in a potential-connecting version (boost converter) and one with a shunt capacitor beginning DC voltage system or DC voltage intermediate system connected downstream and that the DC step-up converter is in a potential-connecting design is designed in its main flow part such that branches in its two longitudinal at least one electrical choke - hereinafter referred to as storage choke - and at least one diode - referred to below as a control diode - are arranged and the two series branches in the transverse direction via an electronic switch - in the following Control switch called -with each other are connected, where, respectively Seen from the input side of the step-up converter, the storage choke (s) in front the shunt branch formed by the control switch and the control diode (s) this shunt arm are inserted and that the voltage of said DC voltage system or DC voltage intermediate system is higher than the periodic peak value the nominal voltage of the feeding AC voltage network and that the switching frequency of the control switch is large compared to the frequency of the AC power supply and that the sinusoidal shape of the input filter flowing alternating current over the specification of that time interval - hereinafter referred to as the duty cycle - during this the actuator switch is electrically conductive, and / or via the specification of that time interval - hereinafter referred to as the switch-off time - during which the control switch is blocked is, and that the amplitude and the effective value of the input filter incoming alternating current via the specification of the duty cycle and / or via the Specification of the switch-off duration of the control switch is set. 2. Device according to claim 1, characterized in that from the DC voltage intermediate system mentioned there, energy-absorbing direct current systems or alternating or three-phase systems of any frequency are fed. 3. Device according to claim 1 or 2, characterized in that the voltage of the DC voltage system or DC voltage intermediate system mentioned there via influencing the power supply to this and / or a suitable influencing the power dissipation is kept largely constant by this. 4. Device according to one of claims 1 to 3, characterized in that that the control switch by an additional device from its power loss is relieved when switching off. 5. Device according to one of claims 1 to 4, characterized in that that the control switch by an additional device of high power dissipation during switch-on and excessive reverse voltage stress during switch-off is exempt 6. device according to one of claims 1 to 5, characterized characterized in that parallel to the DC voltage system or DC voltage intermediate system mentioned there an electrical suction circuit is connected, the resonance frequency of which is twice as high is like the frequency of the feeding AC voltage network. 7. Device according to one of claims 1 to 6, characterized in that that the control switch is switched on or switched on again at the earliest when no more significant current flows through the storage choke. 8. Device according to claim 7, characterized in that the duty cycle of the control switch is constant. 9. Device according to claim 7, characterized gekennzeichrvety that the duty cycle of the control switch via a synchronized with the supplying AC voltage network, digital or analog implemented, time-dependent function generator is controlled. 10. Device according to claim 7, characterized in that that the switch-on duration of the control switch is controlled by a function generator, which is guided by the instantaneous value of a voltage, which is caused by a phase lag causing phase rotation and subsequent full wave rectification from the voltage the feeding AC voltage network can be formed. 11. Device according to claim 8, characterized in that the duty cycle of the control switch is specified by a controller, which controls the setting of the Sinus form and / or the rms value of the current flowing to the input filter concerned. 12. The device according to claim 11, characterized in that the Setpoint for the controller named there via blocks without time behavior from a Voltage is formed which corresponds to the voltage of the feeding AC voltage network lags behind in their phase position. 13. Device according to claim 11 or 12, characterized in that that the switch-on duration of the control switch is also controlled by a function generator corresponding Claim 9 or 10 is piloted. 14. Device according to claim 7, characterized in that the actuator switch is then switched off again when the current through the storage choke has reached a limit value which is twice the frequency of the feeding AC voltage network is prescribed periodically. 15. Device according to claim 14, characterized in that the there stated limit value for the current through the storage choke proportional to Instantaneous value of a voltage is prescribed by a phase lag causing phase rotation and subsequent full wave rectification from the voltage the feeding AC voltage network can be formed. 16. The device according to claim 14, characterized in that the there mentioned limit value of the current through the storage choke via a with the supplying AC voltage network synchronized, implemented digitally or analogously, time-dependent function generator is specified. 17. Device according to claim 14, characterized in that the The limit value mentioned there for the current through the storage choke via a function generator is specified which is carried out by the instantaneous value of a voltage that is carried out by a phase rotation causing a phase lag and subsequent full wave rectification can be formed from the voltage of the feeding AC voltage network. 18. Device according to claim 14, characterized in that the There specified limit value of the current through the storage choke specified by a controller which is the setting of the sinusoidal shape and / or the effective value of the dem Input filter of the flowing current concerned. 19. The device according to claim 18, characterized in that the Setpoint for the controller named there via blocks without time behavior from a Voltage is formed which corresponds to the voltage of the feeding AC voltage network lags behind in their phase position. 20. Device according to claim 19, characterized in that that the limit value of the current through the storage choke additionally via a function generator according to claim 16 or 17 pre-controlled wlrd. 21. Device according to one of claims 9, 10, 16 or 17, characterized characterized in that the function generator mentioned there also has a signal voltage can be influenced and that this signal voltage by way of a controller or Control the setting of the sinusoidal shape and / or the effective value of the input filter worried about inflowing electricity. 22. Device according to one of claims 8 to 21, characterized in that that the control switch is switched on again immediately when through the Storage choke no longer flows appreciable current. 23. Device according to one of claims 8 to 2ts, characterized in that that the control switch is only switched on again when since last zero of the current through the storage choke a certain time interval - hereinafter referred to as the gap duration - has expired. 24. Device according to claim 23, characterized in that the Gap duration of the current through the storage choke via one with the feeding AC voltage network synchronized, digital or analog implemented, time-dependent function generator is specified and that this function generator for setting the sinusoidal shape and / or of the rms value of the alternating current flowing to the input filter via a Signal voltage is also influenced. 25. Device according to claim 23, characterized in that the Gap duration of the current through the storage choke is controlled by a function generator , which is carried out by the instantaneous value of a voltage, which is caused by a Phase rotation causing phase lag and subsequent full wave rectification can be formed from the voltage of the feeding AC voltage network and that this function generator for setting the sinusoidal shape and / or the effective value of the alternating current flowing to the input filter via a signal voltage being affected, 26. Device according to claim 23, characterized in that that the gap duration of the current through the storage choke is specified by a controller which the setting of the sinusoidal shape and / or the effective value of the dem Input filter of the flowing current concerned. 27. The device according to claim 26, characterized in that the Setpoint for the controller named there via blocks without time behavior from a Voltage is formed which corresponds to the voltage of the feeding AC voltage network lags behind in their phase position. 28. Device according to claim 26 or 27, characterized in that that the intervention of the regulator for the alternating current flowing to the input filter, takes place via the signal voltage of a function generator according to claim 24 or 25. 29. Device according to one of claims 7 to 28, characterized in that that the signal for the information that the current through the storage choke is zero has become or no longer has any significant size, on one, on the storage choke additionally applied Auxiliary winding is removed, whose Output voltage with each change in polarity of the rate of change of the Current through the storage choke reverses its sign. 30. Device according to claim 29, characterized in that the control power supplied to the control switch, especially when it is switched off, is chosen so large that the A signal for the auxiliary winding applied to the storage choke The current through the storage choke supplies zero when the voltage of the feeding AC voltage network has the value zero or very small values. 31. Arrangement for the extraction of practically purely sinusoidal current from three-phase networks and for transferring the drawn electrical energy in galvanically connected DC voltage systems or DC voltage intermediate systems characterized in that three devices according to one of claims 1 to 30 with their alternating voltage side to two outer conductors of the three-phase voltage network or to an outer conductor of the three-phase voltage network and its existing one or in addition formed center conductors are connected and that these three devices use additional electrical energy Decoupling diodes on a common DC voltage system or DC voltage intermediate system transfer. 32. Arrangement according to claim 31, characterized in that each of the three devices mentioned there according to one of claims 1 to 30 at their DC voltage output initially works on a capacitor buffer and that this capacitor buffer with the interposition of at least one thyristor each, but preferably below Interconnection of two thyristors each, the electrical energy supplied to them in a cyclical-symmetrical sequence via a common electrical throttle to the common DC voltage system or DC voltage intermediate system. 33. Device according to one of claims 1 to 32, characterized in that that instead of the DC boost converter used there in potential-connecting Execution (English: boost converter) so-called direct current High and Buck-boost converter in potential-connecting design can be used. 34. Device according to one of claims 1 to 32, characterized in that that the DC boost converter contained there by a combination of two DC step-up converter is replaced, their control switch and associated Actuator diodes are dynamically decoupled from one another via a so-called suction throttle are, and their originally separate storage chokes to form a common storage choke are summarized, with the terminal facing away from the circuit input of this common storage throttle is guided to the center of the suction throttle. 35. Device according to claim 34, characterized in that the The two control switches contained there are switched on and off at the same time will. 36. Device according to claim 34, characterized in that the two control switches contained there are switched on and off in such a way that the Switch-on times or switch-off times of one of the two Control switch in the middle of the time interval between two switch-on times or switch-off times of the other control switch. 37. Device according to claim 34, characterized in that at high and low instantaneous values of the voltage of the feeding AC voltage network according to the control principle according to claim 36 and with average instantaneous values according to the voltage of the AC supply system according to the control principle Claim 35 is proceeded. 38. Device according to one of claims 1 to 32, characterized in that that the DC boost converter contained there by a combination of DC boost converters is replaced, the number of which is an integer power of the number 2 and their control switches In addition to the associated setting diodes, dynamic via suction throttles connected in series are decoupled from each other, the number of these suction throttles being half as large like those of the control switches and their originally separate storage chokes to a common storage choke are combined, with that of the circuit input remote connection of this common storage choke to the center of the central Suction throttle is performed.