DE102016202169A1 - Operating an arrangement of generator-operated electrical machine and active bridge rectifier - Google Patents

Abstract

The invention relates to a method (100) for driving an arrangement of a generator-operated electric machine (1) and an active bridge rectifier (2), in the phase connections (U-Y) of the electric machine (2) depending on one and disconnectable first flow valves (UL-YL) are connected to a first DC voltage port (B-) and via second flow control valves (UH-YH) to a second DC voltage port (B +), the method comprising turning on all the first flow control valves (UL-YL), when an output voltage between the first (B) and the second DC voltage terminal (B +) exceeds an upper threshold, and turn off each first current valves (UL-YL) again only when the output voltage has fallen below a lower threshold thereafter at an underflow time, and further a phase current flowing through the DC voltage terminal (U-Y) with the respective first flow valve (UL-YL) t is below a Ausschaltschwellwerts. It is provided that, after a predetermined test period from the time of undershoot, it is checked whether each first flow control valve (UL-YL) has been switched off at least once after the underflow time and, if not, in the one or more phase connections (U-Y) or the first flow control valve (UL-YL) has not yet been turned off at least once after the underflow time, detects a local current minimum of the associated phase current within a predetermined time window and the first current valve (UL-YL) also detects at a time determined based on the detected current minimum is turned off.

Description

The present invention relates to a method for operating an arrangement of a generator-operated electric machine and an active bridge rectifier and means for implementing it.

State of the art

Conventionally come in passenger cars generators in Klauenpolbauweise with passive bridge rectifiers used. The power of such generators is set via the field exciter and this in turn by the excitation current. By controlling the exciter field, the output voltage of the generator can be kept constant regardless of the network load, the speed and the temperature.

If, in the following, simplified is a "generator", this can also be an electric machine which can be operated both as a generator and as a motor, for example a so-called starter generator. The invention is suitable not only for generators in Klauenpolbauweise, but for all at least regeneratively operable electric machines. In passenger cars, bridge rectifiers in six-, eight- or ten-pulse design are used in accordance with the commonly installed three-, four- or five-phase generators. However, the invention is also suitable for bridge rectifiers for other phase numbers.

A load jump in the connected network, for example, by switching on or off a consumer, leads to a load jump on the generator. Since the output power of the generator but can not be changed arbitrarily fast due to the inductance of the excitation field, the generator current initially remains approximately constant, which can lead to a significant increase in the output voltage at a load shedding (English load dump). The degradation of the exciter field can take several hundred milliseconds.

As long as a battery is present in the vehicle electrical system, this can usually absorb the excess generator power and thus prevent excessive voltage increase. However, if no battery is present, the output voltage rises very rapidly and is able to damage the vehicle electrical system components and / or the generator.

For generators with passive bridge rectifiers this is prevented by using zener diodes as rectifier diodes. The Zener diodes clamp the output voltage above their breakdown voltage and are therefore able to convert excess current into heat. In this way, a safe operation is always guaranteed.

Instead of the rectifier diodes, controllable current valves which can be switched on and off, in particular MOSFETs, can also be used in active bridge rectifiers. Advantage is the lower power loss in the on state and thus the better efficiency of the generator as a whole, especially in partial load operation. The control of the flow control valves can be done centrally or remotely. A central control means that a common control device monitors all AC phases and controls all current valves and optionally also the field of excitation of the generator. A decentralized control means that a respective control device monitors an AC phase and, depending on the phase voltage, activates only the current valves associated with the respective phase, ie only the current valves of a respective half-bridge. A decentralized control can be realized with or without communication between the individual decentralized control devices.

One way to prevent voltage peaks in the on-board network during a load shedding, with active bridge rectifiers, is to switch on the current valves of the upper or the lower rectifier branch in each half-bridge. In this way, the electric machine is short-circuited, but not the connected network.

The described measures are also referred to below as phase short circuit. A phase short circuit is in accordance with the language used here so by switching on (Leitendschalten) all to ground or a negative DC voltage connection (see also DC voltage connection B- in accordance with the below 1 ) switching current valves (Lowside current valves) or alternatively all after a positive DC voltage connection (see also DC voltage connection B + in 1 ) switching flow control valves (high-side flow control valves) of the rectifier initiated and canceled accordingly by switching off these flow control valves. If, for example, field-effect transistors are used as current valves, then these current valves are switched on by providing a corresponding control voltage at their gate terminal (activation), whereby the drain-source path of the current valves becomes conductive or low-resistance. Accordingly, the current valves are turned off by stopping the supply of the control voltage and the drain-source path is non-conductive or high impedance. Outside of a phase short circuit there is a regular rectifying (er) operation.

Is subsequently of a "phase short circuit" that performs a current valve of a phase initiates, repeals, etc., or by a "phase short circuit" in a phase of the speech, it is understood that the purpose provided flow control valve is permanently turned on in a corresponding phase. Only in the interplay of all correspondingly connected current valves or phases does this ultimately result in a total phase short circuit. This means that a flow control valve, which in the parlance of this application is "in the phase short circuit" is permanently driven, as is the case when a phase short circuit is initiated in its entirety and therefore all current valves of a branch of a corresponding inverter in a corresponding State are. The same applies to the rectifier operation.

However, problems can occur with corresponding methods, as explained below. The present invention seeks to remedy this situation.

Disclosure of the invention

A method is proposed for operating an arrangement of a generator-operated electric machine and an active bridge rectifier and means for implementing it having the features of the independent patent claims. Embodiments are the subject of the dependent claims and the following description.

A phase short circuit in the sense explained above can be initiated, for example, when the voltage between the DC voltage connections of the bridge rectifier or between a live DC voltage connection and ground exceeds an upper threshold value. The phase short circuit can then be reversed in the prior art at the same time in all phases, if this voltage then falls below a lower threshold. All phases simultaneously terminate the control used in the phase short circuit and start with the control used for regular rectifier operation.

If the phase short circuit at the same time falls below the mentioned lower threshold value at the same time for all AC phases, hereafter referred to as "phases", the current positive current phase will commutate into the upper valve, i. connected to the positive DC voltage rectifier branch, provided that the phase voltage exceeds the voltage in the connected network. Due to the asymmetry effects explained below, under certain circumstances high currents may have to be switched, which causes a corresponding load on the flow control valves involved. The high phase currents during a phase short circuit are also partly due to the missing ("dropped") load. The load on the flow control valves can lead to damage. Damage to the flow control valves can also be caused by the overvoltage which occurs when the phase short circuit is terminated at the same time. Corresponding voltage peaks can bring about a known avalanche effect in a metal oxide field effect transistor, for example, as a result of which the field effect transistor limits the voltage but has to absorb the energy released for this purpose and thus can be thermally damaged.

The cancellation of the phase short circuit can therefore also be carried out phase-specifically, which is understood in the context of this application that one or more criteria are defined for each of the phases, when terminated in the respective phase, the permanent control of the current valve used for the phase short circuit and in a regular rectifier operation to be transferred. The criterion or criteria apply after the voltage between the DC voltage connections of the bridge rectifier or between a live DC voltage connection and ground has fallen below the mentioned lower threshold value. Only after the fulfillment of the criterion (s) the control used in the phase short circuit is terminated for the respective phase and the control used for the regular rectifier operation is started. The phase short circuit as a whole is therefore only canceled when the defined criteria or criteria for all phases are fulfilled and in all phases again the control used for the regular rectifier operation takes place.

Due to the initiation of the phase short circuit, in each case an additional positive or negative direct component arises in the phase currents of the alternating current phases. If a phase short circuit is canceled, a further increase in voltage is effected because, depending on the number of phases of the electric machine, a current with a positive sign (from the generator view) flows at any time in one or more phases. As a result, the phase currents become more or less strongly asymmetrical, ie they no longer oscillate around a common mean or zero.

The one or a criterion for phase-specific cancellation of a phase short circuit as explained above, however, conventionally consists in that the phase current has a value of at most 0 amperes, that is, a zero crossing of the phase current is detected. This avoids that the respective flow valve then switches, if It causes high currents, which, as explained, could lead to problems. Asymmetry of the phase currents is not a problem as long as a zero crossing still occurs in each phase and therefore the said criterion is met. If the phase short circuit is reversed phase-specifically for those phases in which a zero crossing of the phase current has occurred, but due to the described asymmetry effects, one or more phases may remain in which the respective additionally impressed DC components in total become so high that here no zero crossing occurs anymore. A complete cancellation of the phase short circuit is thus no longer possible, because for the phases concerned the defined criterion for the transition to the regular control is no longer met. These phases remain in the control used for the phase short circuit and are thereby heavily loaded.

In other words, in order to avoid having to switch correspondingly high currents, in addition to the mentioned lower threshold value, which relates to the voltage present between the DC voltage terminals, further, individual threshold values can be set for each individual phase (hereinafter referred to as "phase-individual" threshold values or threshold values). "Turn-off thresholds") may be used. As a criterion for switching off a flow control valve, it can thus be provided that, on the one hand, the mentioned lower threshold value is undershot by the voltage present between the DC voltage connections and, in addition, the phase-specific off threshold value by the respective phase current. Typically used on-phase Ausschaltschwellwerte are when using the Lowside flow control valves for initiating and canceling a phase short circuit, as mentioned, at 0 amps, so that it is ensured that only the phases or their flow control valves after the time of falling below the lower threshold by between the voltage applied to the DC voltage terminals are switched off, to which no high current flows and thus there is no risk of damaging the corresponding flow control valves.

However, as mentioned above, the introduction of the short circuit results in each case in an additional positive or negative direct component in the phase currents of the alternating current phases. An additional DC component is created in individual phases additionally when switching off the flow control valves in one or more other phases. This can lead to the phase voltage in individual phases permanently above a corresponding phase-specific switch-off threshold value, for example above 0 amperes, and thus the criterion for switching off is no longer met. The regular rectifier operation may then no longer be made.

In summary, an asymmetry of the phase currents may occur in the event of a load shedding or load jump and a subsequent voltage overshoot in the event of a subsequent phase short circuit and the subsequent non-simultaneous (phase-specific) release. For at least one of the phase currents, this can lead to zero crossing of the phase current over one or more periods. In such a case, when the lower threshold is passed through the voltage applied between the DC voltage terminals, the phase shorts of the remaining symmetric phases are canceled, depending on the magnitude of the remaining load, the voltage at the positive DC voltage terminal or between the DC voltage terminals decreases further applied voltage come.

Advantages of the invention

Against this background, the present invention proposes a method for driving an arrangement of a generator-operated electric machine and an active bridge rectifier. In the bridge rectifier are, as far as known, phase connections of the electric machine in each case via on and off switchable first flow control valves connected to a first DC voltage connection and via second flow control valves to a second DC voltage connection. The method includes, as also known so far and explained above, to turn on all the first flow control valves when an output voltage between the first DC voltage terminal and the second DC voltage terminal exceeds an upper threshold, and turn off each first flow valve only when the output voltage thereafter at an undershoot timing a falls below the lower threshold and in addition a phase current flowing through the DC voltage connection with the respective first flow control valve is below an output threshold. A corresponding method is basically already from DE 10 2011 051 642 A1 known.

In the context of the present invention, it is now provided, in order to avoid that individual flow control valves are no longer switched off due to the described asymmetry effects, after a predetermined test period from the time of undershooting to check whether each first flow control valve has been turned off at least once after the underspeeding moment. If each of the flow control valves has been switched off at least once after the underflow time, it may be assumed that the phase current has fallen below the Ausschaltschwellwert in each of the phase terminals and thus asymmetry effects or at least not occurred in such a large extent that none of the flow control valves has gone back to normal operation, ie the cancellation of the phase shorts. If this is not the case, according to the invention, a local current minimum of the associated phase current is detected in each case in the one or more phase terminals in which the first current valve has not been switched off at least once, and the first current valve is based on the detected current minimum also switched off.

The present invention thus provides first of all to check whether individual of the phases have experienced such an asymmetry by the measures explained above that they can no longer be switched off by means of a conventional method because the switch-off threshold values are no longer achieved by the phase currents. As has been recognized according to the invention, it is particularly advantageous, in such cases, in the phase connection (s) which have not yet entered the regular rectifier mode due to the described asymmetry effects or in which the first current valves are still driven according to a control in a phase short circuit because the one or more of the respective phase currents have no zero crossing, to switch the first current valves at least to a minimum of the respective phase current, so that a regular rectifier operation can be re-established. This will be explained again in other words below.

The starting point of the method according to the invention is that asymmetric phase currents occur during a step-by-step, "phase-specific" cancellation of a short-circuit phase (ie low-side, ie by means of the low-side current valves) as explained above after a voltage increase due to a load current or load shedding the at least one phase current for at least one period no longer reaches a corresponding switch-off threshold value, for example 0 amperes.

Nevertheless, as far as hitherto known method usual, after falling below the lower threshold value by the voltage applied between the DC voltage terminals, the phase short circuit for the phases or canceled the current valves of the phases are switched off, for which the phase current is below the Ausschaltschwellwerts of, for example, 0 amps , At the same time, for example, a counter is started, as explained below, which runs through to a predetermined counter reading. Thus, when the counter reaches a certain value, an undershoot time with respect to the lower threshold value is a predetermined time (hereinafter also referred to as a "check period"), and the phase short circuit is not yet canceled for all the phases, i. a corresponding flow control valve is turned off, according to the invention, as mentioned, in each case in the one or more phase connections in which the first flow control valve has not been turned off at least once, a local current minimum of the associated phase current is detected and the first flow control valve is based on a of the detected current minimum also switched off. Due to these measures, it is ensured that the flow control valves revert to a regular rectification one after the other.

In the context of this application, a "local current minimum" designates a minimum value of the phase current within a predefined time window and / or a point of inflection of the phase current profile from a negative to a positive gradient. In particular, in the context of the present application, a period of the phase current can be selected as the time window, as it is anyway evaluated for speed detection in corresponding converters. In other words, a corresponding time window can be specified on the basis of a rotational speed of the electrical machine. A count of signal edges of the phase current profile can also be used to determine a corresponding time window. In particular, taking into account a corresponding time window, it is possible in the context of the present application to use all methods of minimum detection in signal progressions known and expedient to the person skilled in the art. The phase current profile can be sampled and processed in any desired manner for the detection of the minimum, for example a smoothing adapted to the characteristic of the phase current profile can be carried out in order to prevent a faulty minimum detection.

Since, due to evaluation and signal delays, activation of the respective first flow control valve absolutely at the same time as the detected minimum is not possible, it is proposed according to the invention to switch it off at a point in time determined on the basis of the detected flow minimum. This is also understood to mean that the first flow control valve switches off at the earliest possible time after the detection of the minimum, for example as soon as the signal edge of the current signal rises again. In principle, however, other methods are possible. For example, from a flattening of a falling signal edge of the current signal imminent minimum are detected. The control can be done in this case at the predicted time.

It is advantageous if a corresponding test period is also predetermined as a function of a rotational speed of the electrical machine, in particular as a function of a period of the phase currents, wherein, for example, a number of edges of the phase currents is predetermined.

As already explained, the method operates outside the steps explained above in a regular rectifier operation, thus also after carrying out the method according to the invention. This rectification operation comprises the alternating switching on and off of the current valves of each of the phase connections according to known control patterns, for example by means of a pulse-width-modulated and / or block drive.

A particularly advantageous method comprises the use of decentralized control units in the sense explained above, ie a method in which the flow control valves of each phase connection each have a control device. The control devices communicate via a communication signal. In the context of the present invention, it is provided that the communication signal at least indicates whether the output voltage between the first DC voltage terminal and the second DC voltage terminal has exceeded or fallen below the upper threshold, the phase current flowing through at least one of the DC voltage terminals, the Ausschaltschwellwert has fallen below at least once and the like.

Advantageously, a communication signal with, for example, three states, for example 0 volts, half the output voltage and the full output voltage of the rectifier is included. An example of this will be explained below.

For example, in decentralized control devices, the communication line or its signal, starting from the lowest voltage, for example 0 volts, only released to the next higher voltage level when all the current valves or their control units a corresponding voltage threshold, i. have detected the upper or lower threshold of the output voltage between the first DC voltage terminal and the second DC voltage terminal. As a condition for the transition to the next state, the current state of the communication line is now additionally queried by all phase modules or control units. This ensures that all phases always respond to the same voltage threshold. For normal operation, it is now necessary to reach the third voltage value, which is linked, for example, to a positive interrogation of a further condition, namely in the context of the present invention, that each first flow control valve has been switched off at least once after the underspeeding moment. If this condition is not met within a predetermined time period, i. achieved within a test period after the undershoot time, according to the invention, as mentioned, in each case in the one or more phase connections in which or the first flow control valve has not been turned off at least once after the undershoot time, a minimum detection and the corresponding wiring of the first flow control valve on this Basis carried out. For example, after a successful minimum detection in the one or more phases involved, the third voltage value can be released.

An arithmetic unit according to the invention, e.g. a control device of a motor vehicle is, in particular programmatically, configured to perform a method according to the invention. However, a purely analog implementation, for example in a suitable application-specific integrated circuit (ASIC) is possible.

The implementation of the method in the form of software is also advantageous, since this causes particularly low costs, in particular if an executing control device is still used for further tasks and therefore exists anyway. Suitable data carriers for providing the computer program are, in particular, floppy disks, hard disks, flash memories, EEPROMs, CD-ROMs, DVDs and the like. It is also possible to download a program via computer networks (Internet, intranet, etc.).

Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

Brief description of the drawings

1 shows an arrangement with a generator and an active bridge rectifier in a simplified, schematic representation.

2 shows waveforms for explaining the principles of a method according to an embodiment of the invention.

3 illustrates a method according to an embodiment of the invention in the form of a schematic flowchart.

4 shows waveforms for explaining the principles of a method according to an embodiment of the invention.

In the figures, corresponding elements are given identical reference numerals and will not be explained repeatedly.

Embodiment of the invention

In 1 is an arrangement with a generator 1 and an active bridge rectifier 2 , as it may be based on an embodiment of the present invention, illustrated schematically.

The generator 1 comprises a five-phase and Drudenfußschaltung formed stator 11 and a rotor 12 , The individual windings of the stator 11 and the rotor 12 are not designated separately. The generator 1 is connected via five phase terminals U to Y each on and off switchable, controllable flow valves, here labeled UL to YL and UH to YH, connected to the first DC voltage connection B and a second DC voltage connection B +. The method according to the invention is described below on the basis of an initiation of a phase short circuit in the current valves UL to YL of a lower rectifier branch ("lowside"), but can also be carried out with the current valves UH to YH in the upper rectifier branch ("highside"). The respective current valves involved in the phase short circuit are referred to in the context of this application as "first" flow control valves; at least these are switched on and off as well as controllable, for example, metal oxide field effect transistors. The switchable on and off, controllable flow valves UL to YL and UH to YH are simplified in the figure illustrated as a switch with parallel Zener diodes. The Zener diodes symbolize both the typical breakdown characteristic of a corresponding field effect transistor from a certain drain-source voltage and the inverse diode present in a corresponding field effect transistor.

The flow control valves UH to YH and UL to YL are by respective decentralized control devices 21 to 25 , as illustrated here with dashed control arrows, controllable. A generator controller 13 evaluates a voltage applied between the DC voltage terminals B + and B- (the DC voltage connection B- can be grounded) and controls, for example via a pulse-width-modulated current supply to the field winding of the rotor 12 , the output power of the generator 1 ,

In 2 In order to explain the principles of a method according to one embodiment of the invention, signal waveforms of phase currents in an arrangement with a generator and an active bridge rectifier, for example according to FIG 1 , illustrated. The phase currents are plotted in ampere on the ordinate against a time in milliseconds on the abscissa. The example shows the effects that result when one of the phases is permanently grounded (see B-in 1 ) is short circuited (the corresponding current flow is with 201 ), while the remaining phases (the corresponding current waveforms are with 202 are referred to) in regular rectification, so permanently switch between the potential of B + and B-. As explained above, such an effect can occur, for example, if, during phase-specific activation, a switch-off threshold value for switching off a corresponding current valve can no longer be achieved due to an excessively high DC component in the corresponding phase. The current of the phase shorted to ground (current curve 201 ) is permanently positive in this way.

In 3 a method according to an embodiment of the invention is shown in the form of a schematic flow chart and in total with 100 illustrated. The procedure works in one step 101 in a rectifying operation in which, as explained, the current valves of an active bridge rectifier are controlled by means of known control patterns. This is done as with step 102 illustrates, continuously or periodically reading the voltage applied between the DC terminals of the bridge rectifier voltage.

In one step 103 it is checked whether this voltage is above an upper threshold. If no (-), the process remains in regular rectifier operation as in step 101 illustrated. If yes (+), that is, if the output voltage between the first DC voltage connection and the second DC voltage connection has exceeded the upper threshold, is in one step 104 a short circuit initiated by simultaneous activation of all current valves used for this purpose, for example, the Lowside flow control valves. This is done until a review 105 it is determined that the voltage applied between the DC voltage terminals has fallen below a lower threshold value. As long as this is not the case (-), the short circuit will, as with step 104 illustrated, maintained.

However, the short circuit is still maintained phase-individually (+) as long as the voltage applied between the DC voltage connections has fallen below the lower threshold value (+), the corresponding one Phase current, as with step 107 checked, but still above 0 amps or a corresponding Ausschaltschwellwert is. At the same time a timer is started, as with step 106 which starts a test period and / or starts a corresponding counter. If the switch-off threshold has not fallen below (-), the short-circuit is maintained. If the phase current falls below a corresponding switch-off threshold (+), as with step 108 illustrates, for the flow control valves, for which this is the case, the removal of the short circuit and thus the switching off of a corresponding flow control valve.

Will still during the by in step 106 test period started or before a corresponding meter reading is reached, as with step 109 illustrates that all phases are in the regular state of rectification, because the corresponding phase currents have fallen below the switch-off threshold (+), is transferred back to the regular rectifying operation. If no (-), the end of in step 107 waited counter or the achievement of a corresponding counter value and / or the expiration of a corresponding test period.

Will be in one step 110 detected via an evaluation of a corresponding counter or a time recording that a corresponding counter reading has been reached or a test period has elapsed (+) and there are still phases in the short circuit (+), as already in step 109 determined, takes place. Otherwise (-) the meter reading has not yet been reached or the test period has not yet elapsed.

Will in step 110 If the counter reading has been reached or the test period has elapsed (+), then the procedure according to step 111 a minimum detection with respect to the phase (s) which has not yet been transferred to the regular rectification. The minimum detection according to step 111 is executed until a corresponding minimum has been detected (+). This is then carried out for the corresponding phase (s) according to a step 112 also the cancellation of the phase short circuit, so that these too in the regular rectification according to step 101 pass.

In 4 is in the form of diagrams 410 such as 421 and 422 the effect of the measures according to the invention again illustrated by means of correspondingly occurring signal waveforms. The waveforms are on a common time axis in milliseconds (indicated at graph 422 ) applied.

In diagram 410 is an output voltage as applied between the DC voltage terminals of an active bridge rectifier in the inventive method, and as it is composed of the contributions of the individual phase voltages, indicated in volts, in the diagrams 421 and 422 phase currents in amperes are shown. diagram 421 shows all five phase currents in a diagram, in diagram 422 two of these phase currents are shown separately again.

At a time of about 12.5 milliseconds (time 401 , see diagram 410 ) there is a load jump. This leads to a rapid increase in the output voltage up to a time of about 13 milliseconds (time 402 ). From this point in time, when the output voltage exceeds a predetermined upper threshold, a phase short circuit is initiated.

At a time of about 13.5 milliseconds (time 403 ), the output voltage falls below a lower threshold, so that the phase short circuit can now be repealed successively phase-individually again. This is done in each case for the phases in which the phase current is below the switch-off threshold value, for example below 0 ampere. As from the course of the phase currents according to diagram 421 and 422 As can be seen, this is the case initially for all phase currents, so that there are not yet excessive asymmetry effects. The course of all phase currents according to the diagram 421 and diagram 422 still has a zero crossing. Therefore, the phase short circuit becomes approximately 14 milliseconds (time 404 ) ended regularly. Due to the still not sufficient de-energizing of the electric machine, the output voltage increases again and it comes to cyclic repetition of the initiation and cancellation of the phase shorts.

For example, at about 22 milliseconds (time 405 ) it comes again to initiate a phase short circuit. But now in the diagram 421 and 422 each designated with a phase current induces such asymmetry effects that a phase short circuit can not be canceled regularly in this phase. Therefore, the method according to the invention is carried out and at the same time as the minimum in this phase current at approximately 24.5 milliseconds (time 406 ) nevertheless the regular rectification is resumed for all phases. The procedure is repeated accordingly for the diagram 421 and 422 30.2 milliseconds (time 407 ).

From a time of about 35 milliseconds (time 408 ), the cycle is completed because the excitation current has decayed sufficiently and thus the upper threshold value of the output voltage is no longer reached.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102011051642 A1 [0021]

Claims (11)

Procedure ( 100 ) for driving an arrangement of a generator-operated electrical machine ( 1 ) and an active bridge rectifier ( 2 ), in the phase connections (U-Y) of the electrical machine ( 2 ) are each connected to a first DC voltage connection (B-) by means of switchable first flow valves (UL-YL) and to a second DC voltage connection (B +) via second flow control valves (UH-YH), the method comprising all first flow control valves ( UL-YL) when an output voltage between the first DC voltage terminal (B-) and the second DC voltage terminal (B +) exceeds an upper threshold, and turn off each first current valve (UL-YL) one by one and then again when the output voltage increases thereafter Furthermore, a phase current flowing through the DC voltage terminal (U-Y) with the respective first flow valve (UL-YL) is below a Ausschaltschwellwerts, characterized in that during and / or after a predetermined test period is checked from the time of undershoot, if each first Stromv entil (UL-YL) was turned off at least once after the undershoot time and, if not, in each of the phase connections (U-Y), for the one or more the first flow valve (UL-YL) after the underflow time is not turned off at least once has been detected, a local current minimum of the associated phase current within a predetermined time window and the first flow control valve (UL-YL) is also turned off at a fixed time based on the current minimum time. Method according to Claim 1, in which the test period and / or the time window are dependent on a rotational speed of the electric machine ( 1 ) is given. Method according to Claim 1 or 2, in which the test period and / or the time window are predetermined as a function of a period of the phase currents. The method of claim 3, wherein the check period comprises a predetermined number of edges of the phase currents. Method according to one of the preceding claims, in which in each case a rectifying operation of the active bridge rectifier ( 2 ) is performed before the output voltage between the first DC voltage terminal (B-) and the second DC voltage terminal (B +) exceeds the upper threshold value and after all the first current valves (UL-YL) have been turned off for the first time. Method according to one of the preceding claims, in which the flow control valves (UL-YL, UH-YH) of each phase connection (U-Y) each have a control device ( 21 - 25 ), wherein the control device ( 21 - 25 ) communicate via a communication signal. The method of claim 6, wherein the communication signal at least indicates whether the output voltage between the first DC voltage terminal (B) and the second DC voltage terminal (B +) has exceeded or fallen below the upper threshold, and the phase current through at least one of the DC voltage terminals (U -Y) flows, the Ausschaltschwellwert has fallen below at least once. Arrangement of a generator-operated electric machine ( 1 ) and an active bridge rectifier ( 2 ), characterized in that the arrangement comprises means for carrying out a method ( 100 ) are arranged according to one of the preceding claims. Computing unit, in particular control unit ( 21 - 25 ) an arrangement according to claim 8, which is adapted to a method ( 100 ) according to one of claims 1 to 7. Computer program that causes a computing unit, in particular according to claim 9, to perform a method according to one of claims 1 to 7, when it is executed on the computing unit. A machine-readable storage medium having a computer program stored thereon according to claim 10.

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