DE102017104461A1 - Control of a superposition gear - Google Patents

Abstract

A drive system for a work machine includes a main electric drive; a switching device for connecting the main drive to a main electrical network; an electric auxiliary drive; a frequency converter for controlling a torque of the auxiliary drive; an output shaft for connection to the work machine; a planetary gear with a ring gear, a sun gear, a planetary gear and a planet carrier, wherein the ring gear to the main drive, the sun gear to the output shaft and the planet carrier is coupled to the auxiliary drive, and a control device which is adapted to the main drive means of the switching device and to control the auxiliary drive by means of the frequency converter. In this case, the control device is set up in particular, the control device is adapted to continuously accelerate or retard the auxiliary drive immediately after detecting a request for a start operation or stop operation of the output shaft.

Description

The invention relates to a drive system with a superposition gear, a main drive and an auxiliary drive. In particular, the invention relates to the control of a rotational speed of an output shaft of the superposition gearing.

State of the art

For driving mechanical systems, eg. As a hoist, a multi-motor assembly is used in the prior art in which a plurality of electric drive motors via a superposition gear (planetary gear) take over the performance in part, d. H. The speeds of the motors add up, while the torques on the sun or the ring gear in each case run parallel to the output. Usually, a main drive and one or more auxiliary drives are used, for safety reasons preferably also an operation without the main drive is possible.

A field of application is z. As the regulation of boiler feed pumps in thermal power plants. Here are several, usually three pumps, working together in a strand, usually one of the pumps is at a standstill. For safety reasons, this pump is kept as a reserve and can take over its task in the event of a failure of one of the active pumps. The pump must be accelerated as fast as possible to a nominal speed to keep the flow rate of the strand constant.

WO 2014 183 139 A1 relates to a method for starting a driveline with two drives, which act by means of a superposition gear to an output shaft. In this case, one of the drives is mechanically held at a standstill, while the other is turning up from standstill.

DE 10 2015 107 934 A1 relates to a drive system with a main drive and an auxiliary drive, which are coupled by means of a superposition gear to a working machine. It is proposed to switch an inverter, which is set up to control the auxiliary drive, to the main drive during a starting operation in order to start it up in a speed-controlled manner.

WO 2016 059 115 A1 assumes a similar drive system and shows its startup under temporary detection of the working machine.

DE 10 2014 210 870 A1 suggests starting a startup of a similar drive system while disabling a controller.

An object underlying the invention is to provide an improved technique for starting or stopping a drive system with a superposition gearbox and multiple drives. The invention solves this problem by means of the subjects of the independent claims. Subclaims give preferred embodiments again.

Disclosure of the invention

A drive system for a work machine includes a main electric drive; a switching device for connecting the main drive to a main electrical network; an electric auxiliary drive; a frequency converter for controlling a torque of the auxiliary drive; an output shaft for connection to the work machine; a planetary gear with a ring gear, a sun gear, a planetary gear and a planet carrier, wherein the ring gear to the main drive, the sun gear to the output shaft and the planet carrier is coupled to the auxiliary drive, and a control device which is adapted to the main drive means of the switching device and to control the auxiliary drive by means of the frequency converter. In this case, the control device is set up in particular, the control device is adapted to continuously accelerate or retard the auxiliary drive immediately after detecting a request for a start or stop operation of the output shaft.

In particular, the control device may be configured to perform a starting process with reduced load torque, a quick start or a quick stop. In the quick-start or quick-stop operation, the acceleration or deceleration preferably takes place without a waiting time, for example until a rotational speed of another shaft of the drive system has a predetermined rotational speed. The speed change preferably takes place essentially continuously, which mathematically can correspond to a monotonous function. Small deviations from the monotonous function, for example, to regulate the speed of the output shaft, may be allowed. Thus, an early and effective influencing of the rotational speed of the output shaft can be effected. The starting process or the stopping process can thus be carried out effectively.

The quick start procedure may be performed as an alternative to a known, usual starting procedure, which can be used if the work machine is to be accelerated less quickly and more gently. The starting process with reduced load torque can be provided as a further variant. Likewise, the control device can also be set up to carry out a usual stopping operation, which are used can if a normal stop is required instead of a quick or emergency stop. The quick start or the quick stop can put a heavy load on the drive system, so that a slower and gentler method can be implemented as an alternative. It can also be controlled by the control device several different rapid and gentle processes. Thus, the operation of the drive system can be adapted to currently applicable requirements. For example, a compressor in the offshore area can run on a weak electrical network, so that a gentle starting or stopping is usually preferable. For example, in the event of failure of another compressor can still be carried out in the manner described a quick start, so that the failure can be compensated quickly.

In general, one or more auxiliary drives can be provided. In the following, for simplicity, only one auxiliary drive is used, if one or more mechanically parallel-connected drive devices are meant.

It is further preferred that the control device is adapted to increase the torque of the auxiliary drive during the start or stop operation on its permanently deployable torque. The increase in the torque of the auxiliary drive may allow to perform the quick start or quick stop process faster. Already existing power reserves of an overloadable auxiliary drive can be mobilized for the quick start or rapid stop process. Preferably, the increase in the torque takes place in such a way that the auxiliary drive is not permanently damaged. Current-carrying components of the auxiliary drive, for example a winding, are preferably not permanently damaged. An increased mechanical load of the drive system by the quick-start or rapid stop process, especially on mechanical components, can be accepted. The increased load may relate in particular to a toothing, a shaft or a bearing.

The auxiliary drive can be operated at least temporarily in the field weakening area. An efficiency of the auxiliary drive or the inverter can be sacrificed for an increased speed of the auxiliary drive, so that the speed of the output shaft can be reduced faster or further. For controlling the auxiliary drive, the inverter may be part of a field-oriented control or field-oriented control.

In a preferred embodiment, the auxiliary drive comprises an asynchronous motor. These electric drive machines are usually overloaded from the house. For example, a standard asynchronous machine can be charged in the short term up to twice its permanently deliverable torque or up to 1.5 times its permanently realizable power without permanent damage occurring.

The limit on the performance of the auxiliary drive is usually determined by a maximum temperature, which is generally dependent on external operating conditions as well as the converted mechanical power and a load profile. The drive system may therefore comprise a temperature sensor on the auxiliary drive, which is preferably connected to the control device. The control device may be configured to boost the torque of the auxiliary drive only when the sensed temperature is below a predetermined threshold. In this way, a thermal load of the auxiliary drive can be taken into account, which stirs example of an ambient temperature or a previous torque increase. If no temperature sensor is provided, the temperature can be estimated based on a current, such as by means of an observer model.

In a further embodiment, the drive system comprises a temperature sensor, preferably connected to the control device, on the frequency converter. The control device is preferably configured to only increase the torque of the associated auxiliary drive if the sensed temperature is below a further predetermined threshold value. The frequency converter preferably comprises a supply device for supplying a DC voltage from an auxiliary electrical network, which provides AC power, and an inverter for providing an AC voltage for operating the auxiliary drive, usually in three electrical phases. A supply device can be set up to feed several inverters, which can be assigned to different auxiliary drives. The temperature sensor can be used in the supply device or in the inverter. Each temperature sensor can be assigned its own threshold value. It is also possible to use a plurality of temperature sensors on the same device, for example on individual power semiconductors.

The frequency converter may be dimensioned such that a current which can be permanently supplied by it is insufficient to increase the torque of the associated auxiliary drive. In other words, the frequency converter or one of its components can also be designed to be overloadable. The torque increase of the auxiliary drive may then require an overload of the frequency converter. This allows the Frequency converter in continuous operation suitable for the auxiliary drive dimensioned. A standard frequency converter is designed to withstand an overload of about 50% over a period of about 10 seconds. By only slightly larger dimensioning of elements of the frequency converter, these values can be increased. Usually, a smaller dimensioned frequency converter can be chosen for the smaller auxiliary drive, so that costs, a size or a weight can be reduced.

In one embodiment, the control device is configured to perform a quick start operation from an operating state in which the main drive and the auxiliary drive are at least substantially at rest. The work machine is initially also at least substantially quiet. It is preferred that the main drive is switched on and the auxiliary drive is simultaneously brought to speed as quickly as possible, in particular by utilizing an overload capability. The spin of the auxiliary drive can be maximized.

In a further embodiment, the control device is configured to perform a stop operation, in particular a quick stop, from an operating state in which the main drive is switched on and the auxiliary drive is operated at a positive speed. The main drive usually rotates initially at rated speed and the positive speed of the auxiliary drive raises the speed of the output shaft accordingly. The auxiliary drive is preferably brought as quickly as possible to zero speed and held there until the main drive has come to a standstill.

In yet another embodiment, the control device is configured to perform a quick stop operation from an operating state in which the main drive is turned on and the auxiliary drive is operated at negative speed. The speed of the auxiliary motor can be raised simultaneously with the shutdown of the main drive in the direction of zero. In one variant, the speed of the auxiliary drive is then kept at zero, while in another variant a positive speed is set at short notice, so that the output shaft comes to a standstill as quickly as possible. Remaining speeds of the main drive and the auxiliary drive compensate for substantially zero, so that the output shaft can be kept at a standstill. This allows the output shaft to be stopped even before the main and auxiliary drives reach standstill.

A method of controlling the above-described drive system includes steps of detecting a request to start or stop; activating or deactivating the main drive by means of the switching device; and the simultaneous driving of the frequency converter such that the auxiliary drive is accelerated or decelerated

The method can be carried out or controlled in particular by means of the control device described above. The control device may for this purpose comprise a programmable microcomputer or microcontroller and the method may be in the form of a computer program product which can run on the control device or be stored on a computer-readable data carrier. Features or advantages of the control device can be applied to the method and vice versa.

• 1 ein Antriebssystem;
• 2 ein Überlagerungsgetriebe;
• 3 eine Anordnung von Wellen in einem Überlagerungsgetriebe;
• 4 ein Steuerdiagramm eines Antriebssystems;
• 5 ein Drehzahldiagramm;
• 6 - 8 zeitliche Abläufe beim Beschleunigen eines Überlagerungsgetriebes; und
• 9 - 10 zeitliche Abläufe beim Abbremsen eines Überlagerungsgetriebes

darstellen.The invention will now be described in more detail with reference to the attached figures, in which:

• 1 a drive system;
• 2 a superposition gearbox;
• 3 an arrangement of shafts in a superposition gear;
• 4 a control diagram of a drive system;
• 5 a speed diagram;
• 6 - 8th temporal processes when accelerating a superposition gear; and
• 9 - 10 Timing during braking of a superposition gear

represent.

1 shows a schematic representation of a drive system 100 , To a work machine 102 To power are an electric main drive 104 and electric auxiliary drives 106 and 108 provided by means of a superposition gear 110 torque-locking with the working machine 102 are coupled. In other embodiments, only one auxiliary drive 106 or more than two auxiliary drives 106 . 108 be used.

The working machine 102 For example, it may include a centrifugal pump, a centrifugal compressor, a blower, a compressor or a coal grinder. The operation of the working machine 102 may be critical to the operation or safety of a higher-level facility such as a power plant or heating system. By means of the superposition gearbox 110 can the work machine 102 alternatively by means of the main drive 104 , one or more of the auxiliary drives 106 . 108 or a combination be driven out of it. As will be explained in more detail below, different operating states of the superposition gearing can be used 110 get supported.

A main electrical network 112 can by means of a switching device 114 with the main drive 104 either connected or disconnected. The main engine is running when connected to the main network 112 is connected, with a predetermined rated speed. The auxiliary drives 106 and 108 can preferably by means of associated inverter 116 and 118 be controlled, which consists of a DC link 120 be fed, which provides a DC voltage. The inverters 116 . 118 can each have a speed or a provided torque of the associated auxiliary drive 106 . 108 Taxes. For this purpose, a frequency or a voltage can be varied, the respective auxiliary drive 106 . 108 provided. The control of the auxiliary drives 106 . 108 is preferably done by means of a field-oriented control or regulation. The for the inverters 116 . 118 required DC voltage of the DC link 120 is usually by means of a supply device 122 from an electrical auxiliary network 124 provided. The auxiliary network 124 is usually separate from the main network 112 executed and less resilient. The combination of supply device 122 and inverters 116 . 118 is also called frequency converter.

A control device 126 is adapted to the drive system 100 and in particular the superposition gearbox 110 to control, in particular to the speed of the output shaft 240 to track a specification. The superposition gearbox 110 can have different operating conditions, in particular in response to a request for a speed to be provided on the machine 102 can be adjusted. A transition between the operating states can by the control device 126 be controlled transparently, so the drive system 100 only the target speed of the machine 102 may need as an external reference variable. For controlling the drive system 100 can the controller 126 one or more mechanical elements of the superposition gearing 110 and / or one of the inverters 116 . 118 to control a speed or torque of an auxiliary drive 106 . 108 to influence. Optionally, the control device 126 also with one or more sensors for scanning an operating state of the drive system 100 connected.

2 shows a preferred embodiment of a superposition gear 110 for use in a drive system 100 to 1 , For easier understanding is except the main drive 104 only an auxiliary drive 106 illustrated, but usually at least one additional auxiliary drive 108 provided (cf. 1 ). The auxiliary drives 106 . 108 are usually connected in parallel mechanically and can be electrically controlled individually or jointly.

The superposition gearbox 110 includes a planetary gear 205 with a ring gear 210 a sun wheel 215 , at least one planetary gear 215 and a planet carrier 225 , The planet wheel 215 stands with the ring gear 210 and the sun wheel 215 engaged and is rotatable relative to a bolt 230 stored, concentric with the sun gear 215 rotatable planet carrier is mounted. The ring gear 210 is with a drive shaft 235 for connection to the main drive 104 and the sun wheel 215 with an output shaft 240 for connection to the working machine 102 connected. The planetary gear 205 forms a summing gear that controls the rotational movements of the main drive 104 and the auxiliary drive 106 additively or subtractively and to the work machine 102 can deliver.

Next is a switchable clutch 245 provided, which can be opened or closed by means of an actuator 250. The coupling 245 can work positively, frictionally or by means of hydrodynamic conversion and is adapted to the rotational movement of the planet carrier 245 to the input shaft 235 or the ring gear 210 feed back. In the illustrated embodiment, one side is the coupling 245 by means of a gear stage 255 to the planet carrier 245 and the other side by means of a series of transmission wheels 260 with the input shaft 235 coupled. By means of the transmission wheels 260 can be formed another gear stage. The entire transmission of the rotational movement of the planet carrier 225 to the ring gear 210 is called coupling path.

In the illustrated embodiment, the auxiliary drive 106 via an auxiliary shaft 270 and preferably a further gear stage 270 to the planet carrier 225 tethered. In this embodiment, the one side of the clutch 245 also with the gear stage 270 and the other side via the transmission wheels 260 with the drive shaft 235 be connected. Transmission ratios of the gear stages 255 . 270 can be selected as needed.

• n1: Drehzahl Abtriebswelle 240 = Drehzahl Sonnenrad 215
• n2: Drehzahl Hauptantrieb 104 = Drehzahl Hohlrad 210
• n3: Drehzahl Hilfsantrieb 106, 108
• n-Zwischenwelle: Drehzahl im Kupplungspfad (an der Kupplung 245)
• i_PG: Übersetzung Planetengetriebe 205 (= n1 / n2)
• i_SG1: Übersetzung Getriebestufe (270) (= n3 / n-Planetenradträger 225)
• i_SG2: Übersetzung Getriebestufe (255) (= n2 / n3 oder = n-Zwischenwelle / n-Planetenradträger 225)
• i_SG3: Übersetzung Getriebestufe (260) (= n-Zwischenwelle / n2)

In general:

• n1: speed output shaft 240 = Speed sun gear 215
• n2: speed main drive 104 = Speed ring gear 210
• n3: speed auxiliary drive 106 , 108
• n intermediate shaft: speed in the clutch path (on the clutch 245 )
• i _PG : Translation planetary gear 205 (= n1 / n2)
• i _SG1 : transmission gear ratio ( 270 ) (= n3 / n planet carrier 225)
• i _SG2 : transmission gear ratio ( 255 ) (= n2 / n3 or = n-intermediate shaft / n-planet carrier 225)
• i _SG3 : gearbox ratio ( 260 ) (= n-intermediate wave / n2)

In a lower speed range, the working machine 102 with the main drive switched off 104 and closed clutch 245 be driven up to a speed which by the performance of the auxiliary drive 104 and the load capacities of the clutch 245 , of the planetary gear 205 , the gear stages 255 . 270 and the transmission wheels 260 is limited. This speed is usually about 40 - 60% of the maximum speed of the output shaft 240 , The speed of the working machine 102 can be about the speed of the auxiliary drive 106 . 108 be controlled from standstill. The speed of the main drive 104 is about the clutch 245 to the auxiliary drive 102 coupled.

In an upper speed range, the working machine 102 with the main drive switched on 104 and clutch are driven up to the maximum speed. The main drive 104 is not controllable in its speed, it usually runs at a fixed rated speed. The lowest speed of the output shaft in this operating condition is the rated speed of the main drive 104 specified. By controlling the auxiliary drive 106 can the speed of the output shaft 240 increased to the maximum speed, the speed of the auxiliary drive 106 and the load capacity of the superposition gearing 110 is dependent.

At a transition between the lower speed range (first operating state or range I) and the upper speed range (second operating state or range II) are usually the speed of the auxiliary drive 106 and the operating state of the clutch 245 changed. For a low-wear transition of the lower speed range is preferably selected such that the main drive 104 its rated speed by driving the superposition gear 110 only by means of the auxiliary drive 106 can reach. Will be the main engine 104 switched on at its rated speed, so may be a load on the main network 112 be kept low. In particular, a high inrush current, otherwise for accelerating the rotor of the main drive 104 is required and can be about 8 times the continuous current, omitted.

For speed control and overload protection, speed sensors can be used 280 at the main drive 104 , the auxiliary drive 106 and / or the work machine 102 be provided. Is the opening state of the clutch 245 known, one of the speeds from the other two can be determined, so that two speed sensors 280 at the superposition gearbox 110 can suffice. Optionally, also a temperature sensor 285 on one of the auxiliary drives 106 , 108 may be provided to prevent thermal overload. A temperature sensor 285 can also be at the inverter 116 . 118 or the utility 122 in 1 be provided.

3 shows an exemplary embodiment of an arrangement of the input shaft 235 , the auxiliary waves 265 and the output shaft 240 at a superposition gearbox 110 , Hidden elements are shown with broken lines. The viewing direction with respect to in 2 illustrated embodiment is marked A. Notwithstanding the in 2 illustrated embodiment are here two auxiliary shafts 265 on opposite sides of the output shaft 240 intended. The coupling 245 is preferred in the range of the gear stage 255 provided so that the axes of rotation of the clutch 245 and the auxiliary drives 106 . 108 pass through corners of a particular isosceles triangle. The drive shaft 235 is preferably concentric with the output shaft 240 ,

4 shows an exemplary control diagram 400 of the drive system 100 with the superposition gearbox 110 , In the horizontal direction is a speed N of the working machine 102 as a proportion of a predetermined maximum speed and in the vertical direction a relative torque M as a proportion of a predetermined maximum torque applied. A characteristic 405 shows the torque requirement of an exemplary selected machine 102 about the speed. The torque M of the characteristic 405 here follows an example of a quadratic or cubic function of the speed N. The stronger the moment M of the characteristic 405 increases with the speed N, the smaller is the relative torque at low speeds. The characteristic 405 may also show stronger growth, for example if it follows a higher-order polynomial. Be sufficient strong auxiliary drives 106 . 108 a slower growing function, such as a linear function, can be supported.

A section I shows possible operating points of the superposition gearbox 110 when the main drive 104 is switched off and the drive of the Work machine 102 exclusively on the auxiliary drives 106 . 108 he follows. The coupling 245 is closed. Area II shows possible operating points when the main drive is switched on 104 and open clutch 245 , To the work machine 102 For the entire speed range from 0% to 100%, the ranges I and II must be in one range 410 overlap and at least one point of the characteristic 405 the work machine 102 must be in this area 410 be included. For this design, depending on the available speed spread and the characteristic curve 405 approx. 20 - 30% electrical control power at the auxiliary drives 106 . 108 be installed. Thus, a speed control range of 50-100% is realized for the range II and the ratio of the clutch path must be selected so that the range I a speed range up to at least 50% of the maximum speed of the output shaft 240 covers. The resulting translation is preferred over the coupling 245 , between the electric auxiliary drives 106 . 108 and the input shaft 235 , so chosen that the rated speed of the main drive 104 also within the overlap area 410 lies. In this case, the operating state transition between area I (main drive 104 is deactivated) and area II (main drive 104 is activated) by the clutch 245 by means of the actuator 250 opened and the main drive 104 at or near its rated speed to the main electrical network 112 is switched. The described design allows a quasi-continuous speed control of the machine 102 along the load characteristic 405 ,

5 shows a first sequence when accelerating a superposition gear 110 , In this case, the electrical load of the main drive 104 is reduced as possible during its run-up to reduce its power consumption. The lower the load torque for the main drive 104 is, the faster he can reach his synchronous speed. Usually, the power requirement of the main drive decreases 104 only significantly when reaching the synchronous speed. The time to reach the synchronous speed can be kept as short as possible, which may be advantageous, for example, if the main network 112 weak.

In the horizontal direction of the representation is a time and in the vertical direction are from top to bottom, a speed N1 of the output shaft 240 , a speed N3 of the auxiliary drive 106 . 108 and a rotational speed N2 of the main drive 104. At the beginning of the process is the superposition gearbox 110 silent, the speeds N1, N2 and N3 are each zero. At a time t0, a request for starting the work machine is made by a superordinate control system or a user 102 posed. At this time at the latest, a speed N1_soll will be sent to the drive system 100 , in particular the control device 126 transmitted to the output shaft 240 with the work machine 102 should be accelerated. In one embodiment, the setpoint speed N1_soll is permanently present and only a release of the drive system takes place at the time t0 100 , Upon request, it will start 505 Initiated here in a first phase 510 until the output shaft 240 has reached the target speed N1_soll, and a second phase 515, until the main drive 104 has reached its rated speed, is subdivided. Is the boot process 505 completed, can be a normal operation 520 respectively.

In the first phase 510 becomes main propulsion 104 by means of the switching device 114 to the main network 112 connected. The auxiliary drive 106 . 108 is in the embodiment of 5 in the first phase 510 controlled so that its speed is zero. This usually requires a certain torque, which is also called support torque. Because the main drive 104 Uncontrolled starts up, the torque adjusts depending on its slip frequency. At standstill of the main drive 104 Their slip frequency is the largest and the torque provided is the smallest. A large part of the applied acceleration energy of the main drive 104 goes into the acceleration of the inertial masses of the drive system 100 , causing a rapid increase in the speed N2 of the main drive 104 , and thus an increase in the provided torque, counteracts. The first phase 510 is completed at a time t1 when the rotational speed N1 reaches the rotational speed N1_soll. At time t1 is the run-up of the main drive 104 usually not yet completed on their rated speed.

Having reached N1_soll by N1 must in the following second phase 515 the speed N3 of the auxiliary drive 106 . 108 be controlled in order to regulate the output speed N1 to the specification N1_soll and to avoid overshooting the speed N1. Stand the auxiliary drive 106 . 108 previously silent, it must now be rotated. At a time t2, the main drive 104 has stably reached its rated speed (100%) and the second phase 515 is finished, so that normal operation 520 can be included. The speed N3 of the auxiliary drive 106 . 108 can be further controlled to track the rotational speed N1 of the predetermined speed N1_soll, especially when changing the default or a load change by the machine 102 , If necessary, the speed of the auxiliary drive 106 , 108 negative.

As a rule, the work machine 102 has a load proportional to the speed results in a reduced load for the main drive by the described process control process. This can shorten the startup process and lower the load on the main electrical network 112 require.

6 shows a second sequence when accelerating a superposition gear 110 , as shown by 5 , In this embodiment, in the first phase 510 in addition to the main drive 104 also the auxiliary drive 106 . 108 speeds up the boot process 505 perform as quickly as possible and so realize a quick start. It is on the auxiliary drive 106 . 108 a predetermined, preferably a maximum torque, with further preferred simultaneous maximization of the rotational speed N3 driven in order to maximize the introduced power, which corresponds to the product of torque and the rotational speed N3. The rated torque of the auxiliary drive 106 , 108 can by means of the inverter 116 . 118 usually be controlled from standstill. The acceleration ends when a predetermined speed or a maximum speed is reached. The maximum speed can be achieved by the auxiliary drive 106 . 108 or a maximum frequency of the inverter 116 . 118 be determined. The maximum speed can also be limited by limitations of the superposition gearbox 110 be predetermined. It can be seen that the time t1, at which the output speed N1 corresponds to the specification N1_soll, approximately at the time t1 in the embodiment of FIG 5 corresponds to, but the default N1_soll there is about 60% and in this case about 90% of a maximum speed.

7 shows a third sequence in accelerating a superposition gear 110 , according to the representations of 5 and 6 , This is the auxiliary drive 106 . 108 driven to deliver a service that exceeds its permanently deliverable power. In particular, the inverter can do this 116 . 118 and the utility 122 be briefly operated above their specification. In one embodiment, the voltage is applied to phases of the auxiliary drive 106 . 108 excessive. In a further embodiment, the auxiliary drive 106 . 108 operated in the field weakening area, as with respect to 8th will be described in more detail. It can be seen that the time t1 at a predetermined speed N1_soll from about 90% of the maximum speed even faster than after the embodiment of 6 is reached. The elevation may already start with the second phase 515 be stopped when the auxiliary drive 106 . 108 has reached its predetermined speed. Previously overloaded elements of the drive system 100 can already cool down and recover thermally.

Limits for the maximum speed of the auxiliary drive 106 . 108 or other components of the drive system 100 apply as stated above. In a corresponding manner, the transmittable torque can also be limited. When operating components, in particular the auxiliary drive 106 . 108 , the inverter 116 . 118 or the utility 122 Above its permanently callable load, a temperature control is preferably carried out in order to avoid a thermal overload. The overload can be aborted if any on one of the components of the propulsion system 100 certain temperature exceeds an associated threshold.

8th shows a qualitative speed diagram 800 an electric asynchronous machine, as the auxiliary drive 106 . 108 is preferably carried out. In the horizontal direction, a torque M and in the vertical direction, a speed N is indicated. A first characteristic 805 refers to a normal operation in which the speed of the auxiliary drive 106 . 108 by means of an inverter 116 . 118 is controlled. A second characteristic 810 is opposite to the first characteristic 805 moved vertically upwards.

For speed control, the frequencies and voltages at the three electrical phases of the auxiliary machine 106 . 108 controlled. However, the maximum phase voltages are due to the voltage of the DC link 120 limited. Is the torque of the auxiliary machine 106 . 108 positive, while the phase voltages are less than or equal to the DC link voltage, so works the auxiliary machine 106 . 108 in the basic engine speed range 815 , If the torque M is negative under the same condition, the auxiliary machine operates 106 . 108 in the generator basic speed range 820 ,

To further increase the speed of the auxiliary machine 106 . 108 For example, the frequencies of the phase voltages can be further increased without the phase voltages exceeding the intermediate circuit voltage. To reduce the induced reverse voltage in the auxiliary drive 106 . 108 but then the magnetic field must be reduced so that the maximum possible torque is reduced. If the torque M is positive, the auxiliary drive is working 106 . 108 here in the motor field weakening area 825 , with negative torque in the regenerative field weakening range 830 ,

Nevertheless, to provide a high speed N at a high torque M, the voltage of the DC link 120 be raised so that the characteristic 810 in the speed diagram 800 applies. This overload of the auxiliary drive 106 . 108 and the electrical components 116 , 118, 120, 122 can usually be maintained for a short time without permanently damaging the components. For example, overloading of the electrical components 116 . 118 . 120 . 122 be allowed by about 50% for a period of about 10 seconds.

9 shows a further process when changing the speed provided a superposition gear 110 , analogous to the representations of 5 to 7 , In a reversal of the aforementioned embodiments, however, no startup procedure is involved 505 but a stop 705 carried out. The sequence shown is particularly advantageous at a high speed N1.

The stop process 705 is divided into a first phase here 710 until the auxiliary drive 106 . 108 has reached a standstill, and a second phase 715 until even the main drive 104 has reached a standstill. At time t0, the request is made to shut down the drive system 100 , analogous to the request for starting described above. Thereupon, in the first phase 710 the main drive 104 by means of the switching device 114 from the main network 112 separated. The main drive 104 can act as an asynchronous no electrical or electromagnetic braking torque and its runner acts as inertial mass, by the auxiliary drive 106 . 108 must be slowed down.

The auxiliary drive 106 . 108 is preferred in the motor area 815 or 825 operated to continue a positive supporting moment on the planet carrier 225 exercise. The speed of the auxiliary drive 106 . 108 is delayed by a ramp towards zero speed. The delay is due to reduction of the positive support torque. Reaches the speed of the auxiliary drive 106 . 108 At time t1, a value close to zero, the speed is kept at zero or in a predetermined band around zero.

10 shows a further sequence when switching off or braking a superposition gear 110 , as shown by 9 , The process shown is particularly advantageous at a low speed N1.

In this case, at the time t0, the rotational speed N3 of the auxiliary drive 106 . 108 negative, so that the speed N1 provided is below the rated speed of the main drive 104 is held.

In the first phase 710 becomes the main engine 104 switched off; at the same time the auxiliary drive 106 . 108 slowed down by introducing a positive torque from its negative speed to zero. When braking, the auxiliary drive runs 106 . 108 in generator mode 820 or 830 , In this case, a larger than the permanent by the auxiliary drive 106 . 108 available torque can be retrieved. Because the negative speed of the auxiliary drive 106 , 108 decreasing to the speed N1 of the output shaft 240 acts takes place by accelerating the auxiliary drive 106 . 108 against the speed zero, initially more an acceleration than a deceleration of the speed N1 of the output shaft 240 , The acceleration of the auxiliary drive 106 . 108 and braking the main drive 104 can first partially or completely compensate, so that the rotational speed N1 of the output shaft 240 remains essentially constant.

At time t1, the speed N1 starts to decrease and at time t1 'it reaches zero. At t1 'is the speed N2 of the main drive 104 but still positive and is compensated by a remaining negative residual speed of the auxiliary drive 106, 108. Only at time t2 also reach the speeds N2 and N3 zero. The auxiliary drive 106 . 108 can also be switched off when falling below a predetermined, low speed, for example below about 10 min ^-1 .

In a further embodiment, the negative speed of the auxiliary drive 106 . 108 be maintained as long as possible after the time t0 or even further increased in magnitude, to allow as early and as far as possible a reduction in the rotational speed N1. When the rotational speed N1 has reached zero, the rotational speeds N2 and N3 on the superposition gearing compensate each other 110 , The speed N3 of the auxiliary drive 106 . 108 can then be raised to zero, while the speed N2 of the main drive drops, so that the output shaft N1 remains substantially or completely stationary.

In yet another embodiment, the auxiliary drive 106 . 108 also from a state in which it first runs at positive speed N3, as part of the stop process 705 initially be brought to a negative speed to the output shaft 240 to slow down as early as possible. The output shaft 240 can stall due to the negative speed of the auxiliary drive 106 . 108 even before the main drive 104 to reach.

Conversely, the auxiliary drive can also be used as part of a quick start 106 . 108 initially controlled to a negative speed N3, so the main drive 104 virtually no load when the output shaft is stationary 240 can be brought to its rated speed. The speed N3 of the auxiliary machine 106 , 108 may then be raised to zero or further to a positive value with the output shaft 240 is accelerated.

LIST OF REFERENCE NUMBERS

100

drive system

102

working machine

104

main drive

106

first auxiliary drive

108

second auxiliary drive

110

Superposition gear

112

main electrical network

114

switching device

116

first inverter

118

second inverter

120

DC

122

supply device

124

electrical auxiliary network

126

control device

205

planetary gear

210

ring gear

215

sun

220

planet

225

planet

230

bolt

235

drive shaft

240

output shaft

245

clutch

250

actuator

255

gear stage

260

transmission wheel

265

auxiliary shaft

270

gear stage

280

Speed sensor

285

temperature sensor

400

control diagram

405

curve

410

Area

500

first course

505

starting procedure

510

first phase

515

second phase

520

business

705

stop operation

710

first phase

715

second phase

800

Speed diagram

805

first characteristic

810

second characteristic

815

basic engine speed range

820

regenerative basic speed range

825

motor field weakening area

830

regenerative field weakening range

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

• WO 2014183139 A1 [0004]
• DE 102015107934 A1 [0005]
• WO 2016059115 A1 [0006]
• DE 102014210870 A1 [0007]

Claims (11)

A drive system (100) for a work machine (102), the drive system (100) comprising: - a main electric drive (104); - A switching device (114) for connecting the main drive (104) with a main electrical network (112); - An electrical auxiliary drive (106, 108); - A frequency converter (116-122) for controlling a torque of the auxiliary drive (106, 108); - An output shaft (240) for connection to the working machine (102); - A planetary gear (205) having a ring gear (210), a sun gear (215), a planetary gear (220) and a planet carrier (225), wherein the ring gear (210) with the main drive (104), the sun gear (215) with the output shaft (240) and the planet carrier (225) is coupled to the auxiliary drive (106, 108); - a control device (126) which is adapted to control the main drive (104) by means of the switching device (114) and the auxiliary drive (106, 108) by means of the frequency converter (116-122); characterized in that - the control means (126) is arranged to continuously accelerate or decelerate the auxiliary drive (106, 108) immediately after detecting a request for a startup operation (505) or stop operation (705) of the output shaft (240). Drive system (100) after Claim 1 wherein the control means (126) is adapted to overshoot the torque of the auxiliary drive (106, 108) during start-up (505) or stop (705) over its permanently deliverable torque. Drive system (100) after Claim 1 or 2 , wherein the auxiliary drive (106, 108) is operated in the field weakening area. Drive system (100) according to one of the preceding claims, wherein the auxiliary drive (106, 108) comprises an electric asynchronous motor. Drive system (100) according to one of the preceding claims, further comprising a temperature sensor (285) on the auxiliary drive (106, 108), wherein the control device (126) is adapted to only increase the torque of the auxiliary drive (106, 108), if the sensed temperature is below a predetermined threshold. Drive system (100) according to one of the preceding claims, further comprising a temperature sensor (285) on the frequency converter (116-122), wherein the control device (126) is adapted to only increase the torque of the associated auxiliary drive (106, 108), when the sensed temperature is below a predetermined threshold. Drive system (100) according to one of the preceding claims, wherein the frequency converter (116-122) is dimensioned such that a durably be provided by him current is not sufficient to increase the torque of the associated auxiliary drive (106, 108). Drive system (100) according to one of the preceding claims, wherein the control device is adapted to perform a quick start operation (505) from an operating state in which the main drive (104) and the auxiliary drive (106, 108) stand still. Drive system (100) according to one of the preceding claims, wherein the control device is adapted to perform a quick stop (705) from an operating state in which the main drive (104) is turned on and the auxiliary drive (106, 108) is operated at a positive speed. Drive system (100) according to one of the preceding claims, wherein the control device is adapted to perform a quick stop operation (705) from an operating state in which the main drive (104) is turned on and the auxiliary drive (106, 108) is operated at negative speed. A method of controlling a drive system (100) comprising: - a main electric drive (104); - A switching device (114) for connecting the main drive (104) with a main electrical network (112); - An electrical auxiliary drive (106, 108); - A frequency converter (116-122) for controlling a torque of the auxiliary drive (106, 108); - An output shaft (240) for connection to the working machine (102); - A planetary gear (205) with a ring gear (210), a sun gear (215), a planetary gear (220) and a planet carrier (225), wherein the ring gear (210) with the main drive (104), the sun gear (215) with the output shaft (240) and the planet carrier (225) is coupled to the auxiliary drive (106, 108); the method comprising the steps of: - detecting a request to start (505) or stop (705); - Activation or deactivation of the main drive (104) by means of the switching device (114); and simultaneously driving the frequency converter (116-122) such that the auxiliary drive (106, 108) accelerated or decelerated immediately and continuously.

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