EP2534085B1 - Crane, in particular mobile harbour crane, with a hybrid drive system - Google Patents

Abstract

A crane comprising a diesel-electric drive, the three-phase generator of which supplies an AC voltage circuit, further comprising a DC voltage circuit connected to the AC voltage circuit, electric motors which drive at least one rotating mechanism, a lifting mechanism and a luffing mechanism of the crane, at least one brake resistor, and a short-term energy store, which is connected to the AC voltage circuit or to the DC voltage circuit for the intermediate storage of excess energy. At least one of the electric motors is connected to the AC voltage circuit and at least one is connected to the DC voltage circuit, and the AC voltage circuit is connected to the DC voltage circuit via a rectifier such that an energy exchange is possible between the AC voltage circuit and the DC voltage circuit.

Description

The invention relates to a crane, in particular mobile harbor crane, with a diesel-electric drive whose alternator feeds an alternating voltage circuit with a DC voltage circuit connected to the AC circuit, with electric motors that drive at least one slew, a hoist and a luffing crane, with at least one braking resistor and with a short-term energy storage, which is connected to the temporary storage of excess energy to the AC voltage circuit or to the DC voltage circuit.

From the German patent application DE 10 2004 010 988 A1 For example, a hybrid drive system for a straddle lift truck is known. Such straddle carriers are also known as straddle carriers and are used in seaports and container terminals for transporting and stacking containers. The hybrid propulsion system includes a power generator with a diesel engine that drives an alternator. The three-phase generator feeds a DC link via a rectifier to which driving, lifting and auxiliary motors are connected via inverters. In order to make the power generation unit considerably smaller and lighter, a short-term energy storage is connected via a charge and / discharge controller to the DC voltage intermediate circuit to cover kurzeitigen energy demand peaks, as they arise when starting and braking the traction drive of the straddle carrier or when lifting and lowering the container , This short-term memory can be charged during regenerative braking of the travel and lifting drives and thus does not have to be converted by the driving and lifting drives back into the DC link energy with braking resistors into heat. The short-term memory thus avoids these energy losses and serves as a buffer for the energy. The short-term energy storage is constructed of interconnected double-layer capacitors with very high capacities, which are also referred to as "ultracapacitors" or "Ultra Caps". In addition to the short-term energy storage, a further energy store is connected to the DC voltage intermediate circuit via a further charge and discharge controller. The further energy storage is designed as a lightweight high-energy battery, in particular sodium chloride, sodium-sulfur or nickel-metal hydride accumulator, to cover average power demand peaks, for example, when driving in the minute range occur. The charge and discharge controller for the short-time energy storage and the other energy storage is designed as a controllable two-quadrant DC / DC converter. Furthermore, an electrical control device is provided which is connected to the power generation unit, the short-time energy storage and the further energy storage in order to control these depending on the operating state of the hybrid drive system.

From the patent US Pat. No. 7,554,278 B2 or the associated publication US 2008/0048497 A1 is a hybrid drive system of a rubber-tired crane known, the input side has a DC circuit, which is fed on the one hand by a driven by an internal combustion engine alternator with a downstream rectifier and on the other by serving as an energy storage system battery unit with electrical energy. For supplying energy to the electrically operated crane drive motors, an alternating voltage circuit is also provided, with which all crane drives, in particular a lifting drive, are electrically connected. Also, a further circuit is provided, which can be switched to the DC voltage circuit and through which, for example, when lowering a load by regenerative braking of the lifting drive recovered electrical energy can be passed to charge the energy storage system in the battery unit.

Furthermore, from the published patent application US 2008/0121444 A1 another straddle carrier with a hybrid propulsion system known. Instead of a diesel engine, a micro gas turbine is used, which drives an alternator. The alternator is followed by a rectifier, which supplies a DC voltage circuit. At this DC circuit, the electric traction motors and the lifting motor and a hydraulic pump for a hydraulic system are connected. The aforementioned drives are each electric three-phase drives and are therefore each connected via an inverter to the DC voltage circuit.

Furthermore, so-called mobile harbor cranes are already known from the current company prospectus of Gottwald Port Technology GmbH, Dusseldorf, Germany with the title "Hafenkran Model 4", with which containers or bulk goods are transhipped into seaports or container terminals. Such a mobile harbor crane essentially consists of an undercarriage with which the Mobile Harbor Crane in the countryside, For example, a wharf, or supported on a floating pontoon, and a rotatably mounted about a vertical axis on the undercarriage superstructure. The undercarriage can be moved over tires on the quay or over rail wheels on rails. During the handling operation, the undercarriage is supported by supports. On the superstructure, a vertically extending tower, the rotary and lifting mechanisms for the rotation of the upper carriage and the lifting of a load and a counterweight are arranged. Furthermore, a boom is articulated on the tower approximately in the region of half its length and on the side facing away from the counterweight. The boom is connected to a pivotable about a horizontal rocker axis with the tower and additionally pivoted on a hinged to the boom and the bottom of the uppercar bevelled cylinder from its laterally projecting operating position into an upright rest position. In addition, the boom is formed in the usual way as a lattice mast.

Such mobile harbor cranes are in terms of their drive concept, the formation of a serial hybrid, since they work with a diesel-electric drive in which the chemical energy of the diesel fuel is converted by an internal combustion engine into mechanical work and fed by an alternator as electrical energy into an AC circuit. To drive the hoist, the slewing gear and the luffing gear and any other drives DC or AC motors are used in which a renewed conversion of the electrical energy takes place back into mechanical work, which is ultimately for lifting loads, for moving and turning the crane or used to move the boom. Energy that is fed back, for example by lowering loads on the boom in the AC circuit, is initially made available to other consumers. Once there is an excess of energy in the AC circuit, it will be converted to heat by braking resistors, destroying the returned energy, i. finally lost.

Based on this prior art, the present invention seeks to provide a crane, in particular mobile harbor crane, with an improved hybrid drive system.

This object is achieved by a crane, in particular mobile harbor crane with the features of claim 1. Advantageous embodiments of the invention are in the Subclaims 2 to 14 specified.

According to the invention, in a crane, in particular mobile harbor crane, with a diesel-electric drive whose alternator feeds an AC circuit, with a connected to the AC voltage circuit DC circuit, with electric motors that drive at least one slew, a hoist and a luffing crane, with at least one braking resistor and with a short-term energy storage, which is connected to the intermediate storage of excess energy to the AC circuit or to the DC circuit, an improvement of the hybrid drive system achieved in that at least one of the electric motors is connected to the AC voltage circuit, at least one of the electric motors is connected to the DC voltage circuit and the AC voltage circuit is connected to the DC voltage circuit via a rectifier such that an energy exchange between the AC voltage circuit and the DC voltage circuit is possible t. By using the short-term energy storage for the storage of, for example, regenerative braking of the drives recovered excess energy, the performance of the drive of the alternator combustion engine, in particular diesel engine can be improved so that the fuel consumption and thus the emission of pollutants lowered and the recovered Energy can be harnessed elsewhere. With a targeted modular design of the necessary assemblies and functionalities, the short-term energy storage can be retrofitted into existing mobile harbor cranes as an extension. In addition, it ensures that the mobile harbor crane can continue its normal operation in the event of failure of the short-term energy storage, as the braking resistor is still present. In this case, it is particularly advantageous that the rectifier which connects the AC voltage circuit and the DC voltage circuit is designed to be capable of regenerative feedback.

The recovery of energy is achieved in an advantageous manner in that at least the electric motors of the hoist and the luffing mechanism for the recovery of electrical energy in the AC voltage circuit or in the DC voltage circuit can be operated as a generator.

In an advantageous embodiment, the electric motors are designed as three-phase motors.

In a preferred embodiment it is provided that the short-time energy storage is connected via a DC-DC converter to the DC voltage circuit. By using the DC-DC converter, the short-time energy storage can be synchronized with the DC voltage circuit with respect to the voltage level.

It is particularly advantageously provided that the short-time energy storage is designed as a double-layer capacitor. Such double-layer capacitors are durable, maintenance-free and lightweight and have a low energy density at high power density. As a result, these are particularly suitable as a short-term energy storage. Compared to batteries, the double-layer capacitors can absorb or deliver significantly higher powers and their lifetime is not so much affected by the rapid and short-term switching between charging and discharging as batteries. Although the energy content per volume is lower than that of batteries, these features make double-layer capacitors ideal as short-time energy storage for use in mobile harbor cranes because lowering the loads of a mobile harbor crane results in very high power levels but low energy levels over a relatively short period of time occur for a few seconds and for acceleration processes during lifting and other crane movements high peak performance only occur at short notice.

In a preferred embodiment it is provided that the braking resistor is connected via a rectifier to the AC voltage intermediate circuit.

It is also of particular advantage that at least the electric motor of the luffing gear is connected to the AC voltage circuit.

In combination with the present invention, it is advantageous that the slewing gear has a three-phase motor which is connected via an inverter to the DC voltage circuit, the hoist has a three-phase motor which is connected via an inverter to the DC voltage circuit, and the luffing gear has a three-phase motor, which is connected directly to the AC voltage circuit. The short-time energy storage can then easily on an existing AC circuit without changing the concept of the electrical system be retrofitted to existing mobile harbor cranes.

Particularly advantageous is provided that a power control, which is set via an operating strategy, with the diesel-electric drive, the braking resistor or its rectifier, the short-term energy storage and the DC-DC converter of the short-term energy storage is connected and on the basis of the data of the alternator Active power meter and the state of charge of the short-term energy storage the short-term energy storage and controls the braking resistor as needed. As operating strategies either a recuperation strategy or a downsizing strategy are used. In the context of the recuperation strategy, the main objective is to absorb the entire energy fed back into the AC circuit, thus avoiding the use of braking resistors. The main objective of the downsizing strategy is to limit the power demand on the diesel-electric drive so that operation of the mobile harbor crane would also be possible with a reduced internal combustion engine and a reduced alternator without sacrificing performance. The short-term energy storage will go in this downsizing strategy usually only when reaching the maximum power of the internal combustion engine in the Boostzustand. According to the invention, the behavior of the double-layer capacitor and the operating states of the rest of the system is primarily defined as a function of the measured active power of the generator and the state of charge of the memory to optimize energy conservation. A controlled power output of the short-term energy storage can avoid hard load requirements on the internal combustion engine. The soft start prevents sudden loads, which has a positive effect on the transient fuel consumption and the exhaust emissions of the internal combustion engine.

It is particularly advantageous that is set via the power control of the short-term energy storage during a regular boost of the diesel-electric drive to a constant discharge or adjusted via the power control such that during the boost of the diesel-electric drive with a corresponding power request deviating from the constant discharge a higher discharge power is provided when the state of charge of the short-term energy storage is close to the maximum value after a charging phase. Setting to a constant discharge power increases the efficiency of the short-term energy storage during the regular boost. However, this does not rule out that in the context of the invention during the boosting with a corresponding power request of the consumer can also be deviated from the constant discharge, especially if the state of charge of the short-term energy storage is close to the maximum value after a charging phase.

According to one embodiment, a lower state of charge limit and upper state of charge limit is defined via the power control for the short-time energy store. Accordingly, the short-term energy storage can discharge to a fixed lower state of charge limit, which is defined by the lower voltage range of the inverter or the usable state of charge of the short-term energy storage.

The lower state of charge limit is defined as 25% of the upper state of charge limit. This refinement also serves to optimize the efficiency, since at higher voltage the losses due to the internal resistance of the short-time energy store are lower. This is taken into account when the working range of the short-term energy storage is in the highest possible voltage ranges above the defined lower state of charge limit for the discharge.

If according to a further feature of the invention, the power output of the short-term energy storage is reduced near the switching limit between boost mode and normal operation, also hard load requirements to the internal combustion engine when switching off the short-term energy storage can be avoided. This has a positive effect on consumption and exhaust gas behavior of the internal combustion engine.

The regenerative capacity of the hybrid drive system of the crane is advantageously increased by the fact that the luffing mechanism comprises a hydraulic cylinder and a hydraulic pump and that the electric motor driving the hydraulic pump can be regenerated.

• Figur 1 eine Ansicht eines Hafenmobilkrans und
• Figur 2 ein Blockschaltbild eines Hybridantriebes des Hafenmobilkranes nach Figur 1.

Hereinafter, an embodiment of the invention will be explained with reference to a drawing. It shows:

• FIG. 1 a view of a harbor mobile crane and
• FIG. 2 a block diagram of a hybrid drive of the mobile harbor crane after FIG. 1 ,

The FIG. 1 shows a view of a mobile harbor crane 1 for the handling of standardized containers, in particular ISO containers, between land and water or vice versa or within container terminals. Also, the mobile harbor crane 1 can be equipped with a grab for handling bulk materials. The mobile harbor crane 1 consists essentially of an undercarriage 2 and a superstructure 3 with a tower 4 and a boom 5. In the usual way, the mobile harbor crane 1 via its undercarriage 2 on land, here a quay 7, supported. About the undercarriage 2 with Radreifenfahrwerken 6 of the mobile harbor crane 1 on the quay 7 is movable and is supported during the Umschlagbetriebes via supports 8 on this. It is also possible that the mobile harbor crane 1 is mounted on rails movable or stationary on a floating pontoon. On the undercarriage 2 of the superstructure 3 is mounted, which is pivotable about a vertical axis of rotation D of a slewing gear D. The slewing gear d usually has a turntable in engagement with a drive gear. The superstructure 3 also carries a hoist h and in the rear area a counterweight 9. Also supported on the superstructure 3 extending in the vertical direction tower 4, at the top of a roller head 10 is fixed with sheaves. Furthermore, the boom 5 is articulated to the tower 4 approximately in the region of its half length and on the side facing away from the counterweight 9. The boom 5 is pivotally connected to the tower 4 about a horizontal rocking axis W and in addition via a pivoted on the boom 5 and the bottom of the uppercarriage 3 Wippwerk w, which is usually designed as a hydraulic cylinder, from its laterally projecting operating position into an upright rest position pivotable. In addition, the boom 5 is formed in a conventional manner as a lattice mast. At the tower 4 facing away from the tip of the boom 5 more sheaves are rotatably mounted on the basis of the hoist h hoists are guided over the roller head 10 to the load to be lifted.

The FIG. 2 shows a block diagram of a hybrid drive of the mobile harbor crane 1 after FIG. 1 , As described above, such mobile harbor cranes can be serial hybrids with respect to their propulsion concept, since they operate with a diesel-electric drive 11, in which the chemical energy of a diesel fuel is converted into mechanical work by an internal combustion engine 11 a. The internal combustion engine 11a drives an alternator 11b, which controls the mechanical Converts energy into electrical energy and fed into an AC circuit 12. The three-phase generator 11 b generates a three-phase alternating current with a voltage level of 440 V. The supply network for providing energy for the various electric motors of the mobile harbor crane 1 comprises in addition to the AC voltage circuit 12 a DC voltage circuit 17 which is connected via a rectifier 16 to the AC voltage circuit 12. By the rectifier 16, an energy exchange between the AC circuit 12 and the DC circuit 17 is possible, for example, by regenerative braking or regenerative operation of an electric motor recovered electrical energy in one of the voltage circuits 12, 17 there is an excess of energy and another electric motor has energy needs. To the AC circuit 12 is the drive of the luffing w and the DC circuit 17 are different consumers, in particular the respective drives of the hoist h and the slewing gear d, connected, in which a renewed conversion of electrical energy back into mechanical work takes place, the rocking of the boom 5, is used for lifting loads or for turning the mobile harbor crane 1. The hoist h and the slewing gear d have three-phase electric motors h1, d1, preferably asynchronous motors, which are each connected via an inverter h2, d2 to the DC voltage circuit 17. In the inverters h2, d2, the DC voltage is converted into AC voltage. However, it is also possible to connect the three-phase motors h1, d1 to the AC voltage circuit 12. For the luffing w a constant-speed three-phase motor w1 is connected to the AC voltage circuit 12, which drives a hydraulic pump w2, in particular axial piston pump. The hydraulic pump w2 is connected to a hydraulic cylinder w3, via which the boom 5 of the mobile harbor crane 1 can be pivoted about the luffing axis W. The hydraulic pump w2 and the three-phase motor w1 can be designed such that excess energy can not be returned, but is dissipated, for example, via throttles. However, it is also conceivable that the hydraulic pump w2 and the three-phase motor w1 are capable of being regenerated, so that an energy return into the AC voltage circuit 12 or via the rectifier 16 into the DC voltage circuit 17 can take place.

Furthermore, other drives, not shown, are present, which are connected directly to the engine 11 a or are connected to the AC voltage circuit 12. For example, here are the drive for the mobile harbor crane. 1 or to mention any drives for closing and opening a four-rope bulk grapple. Corresponding drives operated by three-phase motors can likewise be connected to the DC voltage circuit 17 via rectifiers. It is also possible to operate these drives via DC motors and to connect them to the DC voltage circuit 17 or via inverters to the AC voltage circuit 12. By the device of both the AC voltage circuit 12 and the DC voltage circuit 17, it is possible to vary the motors used for the respective drives.

In order to recover the energy which is fed back in the so-called regenerative braking of the three-phase motors d1, h1, and w1 in the AC voltage circuit 12 and in the DC voltage circuit 17, a short-term energy storage 13 is connected to the DC voltage circuit 17. The recoverable from this short-term energy storage 13 energy arises essentially when lowering and braking of the load and thus by the regenerative braking of the three-phase motor h1 of the hoist h. If a regenerative hydraulic pump w2 and a regenerative three-phase motor w1 are used, the energy returned by the hydraulic pump w2 can also be absorbed by the short-time energy storage 13. In principle, however, each of the electric motors can be designed in a regenerative manner and connected to the AC voltage circuit 12 or to the DC voltage circuit 17. Thus, at least indirectly both voltage circuits 12 and 17 of the power supply network to the energy storage system or the short-term energy storage 13 are connected.

In the event that the short-term energy storage 13 can store no energy or other energy, a braking resistor 14 is connected to the AC voltage circuit 12. About this braking resistor 14 then the voltage fed back by the regenerative braking of the three-phase motors d1, h1, and w1 in the AC circuit 12 voltage is converted into heat and thus destroyed.

The integration of the short-term energy storage 13 in the DC circuit 17 results in various new operating conditions for the hybrid drive of the mobile harbor crane 1. In addition to the usual operating state "normal operation", the means the internal combustion engine 11a serves the occurring during operation of the mobile harbor crane 1 different load requirements, and "resistance brakes" in which - possibly via the DC circuit 17 - is fed back into the AC circuit 12 energy in the braking resistors 14 is converted into heat come add additional operating conditions. Specifically, it is the operating conditions "load point increase" in which the engine 11 a is operated in a more favorable operating range with a higher efficiency by charging the short-term energy storage 13, "Boosten", the support of the internal combustion engine 11 a through the short-term energy storage 13 relates to "memory braking", which relates to the charging of the memory by the energy fed back into the AC intermediate circuit 12, and "memory / resistance braking", which is a mixed form of the operating states "memory braking" and "resistance braking" is. In the event that the short-term energy storage 13 is fully charged, there is a "resistance braking". The braking resistor 14 is connected via a rectifier 14a to the AC voltage circuit 12, thus, the braking resistor 14 can be switched as needed. A control takes place via a total power measurement. This is energetically beneficial.

The short-time energy storage 13 is designed as a double-layer capacitor, which is also referred to as "Ultracap" or "Supercap". Such double-layer capacitors are durable, maintenance-free and lightweight and have a low energy density at high power density. As a result, these are particularly suitable as a short-term energy storage. Compared to batteries can be absorbed by the double-layer capacitors significantly higher power or delivered. Although the energy content per volume is lower than that of batteries, these features make double-layer capacitors ideal as short-time energy storage for use in mobile harbor cranes, since lowering the loads of a mobile harbor crane 1 results in very high power but low energy over a relatively short time Period of a few seconds occur and for acceleration processes during lifting and other crane movements high peak performance only occur at short notice. The slewing gear d feeds only small amounts of energy back into the AC voltage intermediate circuit 12, since the rotational movement of the upper carriage 3 of the mobile harbor crane 1 is slow and thus the acceleration and deceleration processes are short and low in energy.

The short-time energy storage 13 is connected bidirectionally to the DC voltage circuit 17 with the interposition of a DC-DC converter 13a. The DC-DC converter 13a adopts the voltage adjustment to the DC voltage circuit 17.

By the short-term energy storage 13, a number of other functionalities can be integrated, with which a positive influence on the operating behavior of the internal combustion engine 11 a can be taken. As a result, besides other fuel savings, the pollutant emissions generated can also be significantly reduced. The short-time energy storage 13 can enable a soft start of the internal combustion engine 11a by corresponding boosting. This will avoid sudden, hard load requirements on the internal combustion engine 11 a. This has positive effects on the transient consumption and the exhaust gas behavior of the internal combustion engine 11a. Also, in phases of positive power demand, a definable basic engine load is maintained. This allows a faster response of the internal combustion engine 11a at sudden load requirements. Furthermore, it is ensured that the power of the short-term energy storage device 13 is gradually reduced near the switching limit between "boost" and "normal" operation. This in turn avoids a hard load request to the engine 13 when the boost operation is terminated.

The short-time energy storage 13 is controlled by a power controller 15, a so-called power coordinator, ie the charging or discharging power of the short-time energy storage 13 in amount and duration set. The power control 15 is parameterized by the operating strategy used. The power coordinator also controls the transition from charging the short-time energy storage 13 to the benefit of the braking resistors 14. The purpose of the power control 15 is therefore in particular to ensure that excess energy directly drives the drives or three-phase motors d1 connected to the AC voltage circuit 12 or the DC voltage circuit 17 , h1 and w1 are supplied in order to avoid losses occurring during temporary storage in the short-term energy store 13. Only when no consumer has more energy and at the same time the short-term energy storage 13 still has free charging capacity, a caching is made. The braking resistors 14 thus serve as an emergency system in the event that neither one of the drive motors or Three-phase motors d1, h1 and w1 energy requirement in the amount of energy fed back has yet the short-term energy storage 13 can absorb a corresponding amount of energy.

As operating strategies either a recuperation strategy or a downsizing strategy are used.

In connection with the recuperation strategy, the main goal is to absorb the entire energy fed back into the AC voltage circuit 12 or into the DC voltage circuit 17, and thus to avoid the use of the braking resistors 14. The load point boost is not used in this operating strategy. During the regular boost, the short-time energy storage 13 is discharged at a constant power. This discharge power is chosen so small that the short-term energy storage 13 discharges as far as possible to record the entire recuperation energy in the next charging cycle. Thus, the highest possible efficiency of the short-term energy storage 13 is achieved. In this context, a lower SOC limit (state of charge, charging status 0: completely emptied 1: fully charged) is defined for the discharge, so that the working range of the short-term energy storage device 13 lies in the highest possible voltage ranges. This also serves to optimize the efficiency, since at higher voltage, the losses due to the internal resistance of the short-time energy storage 13 are lower. Also, during the boost, it is possible to deviate from the constant discharge power in some cases. It can be boosted, for example, with a corresponding power request with maximum discharge power, if the state of charge of the short-time energy storage 13 is close to the maximum value after a charging phase.

The downsizing strategy provides as the main goal to limit the power demand on the diesel-electric drive 11 so that operation of the mobile harbor crane 1 would also be possible with a downsized internal combustion engine 11a and a downsized alternator 11b without sacrificing performance. To ensure this, takes the short-term energy storage 13 in addition to the fed back into the AC voltage circuit 12 energy by load point increase of the engine 11 a charge. This can be controlled by an upper SOC limit. The short-term energy storage 13 may discharge to a predetermined SOC lower limit. This is due to the lower tension range of the DC converter 13a - SOC> 0.25 - or the usable SOC range of the short-term energy storage 13 defines. The short-term energy storage 13 will go in this downsizing strategy usually only when reaching the maximum power of the engine 11 a in the boost state.

In addition to the operating strategy, other factors determine the set power of the short-term energy storage 13. The used DC-DC converter 13a limits the amount of possible power due to its possible voltage adjustment range. In addition, a temperature monitoring of the short-term energy storage 13 takes place in order to prevent a shortening of the life due to excessive heating.

The basis of the control of the short-time energy storage device 13 with the power control 15 is the regulation of the measured effective power of the three-phase generator 11 b to a defined desired value. In addition, the power controller 15 also controls the rectifier 14a of the braking resistor 14. In the case of insufficient charging power of the short-time energy storage 13, the excess power in the braking resistor 14 is converted into heat. In this way, the operating conditions described above are set automatically. Furthermore, the power controller 15 has a limiting module with which the selected operating strategy and thus the associated parameters are realized within the power controller 15. The switching limits which are dependent on the short-time energy store 13, the limitation by the voltage setting range of the DC-DC converter 13a and the temperature monitoring are implemented therein. The variable rise represents a definable ramp time for the DC-DC converter 13a of the short-time energy storage 13. This ensures the soft start of the internal combustion engine 11a and the soft exit from the boosting process.

The short-term energy storage 13 can be retrofitted by its modular design of the modules and functionalities as an extension into existing mobile harbor cranes 1. In addition, the receipt of the braking resistors 14 in addition to the short-term energy storage 13 ensures that the mobile harbor crane 1 can continue its operation in the event of failure of the short-term energy storage 13.

The power controller 15 and the operating strategy are implemented in a programmable logic controller (PLC) which controls the DC-DC converter 13a and thus the short-time power storage 13. *** " The basis for the power control 15 is the analog signal of an active power meter 11c, which continuously measures the power output of the alternator 11b and provides this information to the rectifier 14a of the braking resistors 14 and the DC-DC converter 13a of the short-time energy storage 13. The braking resistor 14 remains in the system and is used when, if the short-term energy storage 13 can not absorb the entire braking energy or fails.

The power controller 15 communicates via a bus system with a higher-level main controller (not shown) of the mobile harbor crane 1. Depending on which bus systems the controllers use, the communication takes place via an interface. For example, the power controller 15 uses a J1939 BUS to communicate with the short-term energy storage 13 and communicates with the DC-DC converter 13a to communicate with a CAN OPEN BUS, which is also used by the main controller of the mobile harbor crane 1.

LIST OF REFERENCE NUMBERS

1

Mobile Harbor Crane

2

undercarriage

3

superstructure

4

tower

5

boom

6

Radreifenfahrwerk

7

quay

8th

Support

9

counterweight

10

roller head

11

diesel-electric drive

11a

internal combustion engine

11b

Alternator

11c

Active power meter

12

AC circuit

13

Short-term energy storage

13a

DC converter

14

braking resistor

14a

rectifier

15

power control

16

rectifier

17

DC circuit

d

slewing

d1

Three-phase motor

d2

inverter

H

hoist

h1

Three-phase motor

h2

inverter

w

Boom elevation

w1

Three-phase motor

w2

hydraulic pump

w3

hydraulic cylinders

D

axis of rotation

W

rocking axis

Claims (14)

1. Crane, in particular a mobile harbour crane (1), having a diesel-electric drive (11) whose three-phase generator (11 b) supplies an a.c. circuit (12), having a d.c. circuit (17) connected to the a.c. circuit (12), having electric motors which drive at least one slewing mechanism (d), one lifting mechanism (h) and one luffing mechanism (w) of the crane, having at least one braking resistor (14), and having a means of short-term energy storage (13) which is connected to the a.c. circuit (12) or to the d.c. circuit (17) for the buffer storage of excess energy, characterised in that at least one of the electric motors is connected to the a.c. circuit (12), at least one of the electric motors is connected to the d.c. circuit (17), and the a.c. circuit (12) is connected to the d.c. circuit (17) via an rectifier (16) in such a way that an exchange of energy is possible between the a.c. circuit (12) and the d.c. circuit (17).
2. Crane according to claim 1, characterised in that, of the electric motors (h1, w1) of the lifting mechanism (h) and the luffing mechanism (w), at least one can be operated as a generator to feed electrical energy back into, respectively, the d.c. circuit (17) or the a.c. circuit (12).
3. Crane according to claim 1 or 2, characterised in that the electric motors (d1, h1, w1) take the form of three-phase motors.
4. Crane according to one of claims 1 to 3, characterised in that the means of short-term energy storage (13) is connected to the d.c. circuit (17) via a d.c. converter (13a).
5. Crane according to one of claims 1 to 4, characterised in that the means of short-term energy storage (13) takes the form of a double-layer capacitor.
6. Crane according to one of claims 1 to 5, characterised in that braking resistor is connected to the a.c. circuit (12) via a rectifier (14a).
7. Crane according to one of claims 1 to 6, characterised in that at least the electric motor (w1) of the luffing mechanism (w) is connected to the a.c. circuit (12).
8. Crane according to one of claims 1 to 7, characterised in that the slewing mechanism (d) has a three-phase motor (d1) which is connected to the d.c. circuit (17) via an inverter (d2), the lifting mechanism (h) has a three-phase motor (h1) which is connected to the d.c. circuit (17) via an inverter (h2), and the luffing mechanism (w) has a three-phase motor (w1) which is connected directly to the a.c. circuit (12).
9. Crane according to one of claims 6 to 9, characterised in that a power controlling system (15) which is set by means of an operating strategy is connected to the diesel-electric drive (11), the braking resistor (14) or rather its rectifier (14a), the means of short-term energy storage (13) and the d.c. converter (13a) of the means of short-term energy storage (13), and it actuates the means of short-term energy storage (13) and, if required, the braking resistor (14) on the basis of the data from a wattmeter (11c) associated with the three-phase generator (11 b) and on the basis of the state of charge of the means of short-term energy storage (13).
10. Crane according to claim 9, characterised in that the means of short-term energy storage (13) is set via the power controlling system (15) to a constant discharge power during regular boosting of the diesel-electric drive (11) or is set via the power controlling system (15) in such a way that, if there is a power demand to this effect, a higher discharge power and not the constant discharge power is made available during the boosting of the diesel-electric drive, if the state of charge of the means of short-term energy storage (13) is close to the maximum value after a charging phase.
11. Crane according to claim 9 or 10, characterised in that a lower limit for the state of charge and an upper limit for the state of charge are defined for the means of short-term energy storage (13) by means of the power controlling system (15).
12. Crane according to claim 11, characterised in that the lower limit for the state of charge is defined as 25% of the upper limit for the state of charge.
13. Crane according to one of claims 9 to 12, characterised in that the power output from the means of short-term energy storage (13) is reduced by means of the power controlling system (15) close to the switching limit between boosted operation and normal operation of the diesel-electric drive (11).
14. Crane according to one of claims 1 to 13, characterised in that the luffing mechanism (w) comprises a hydraulic cylinder (w3) and a hydraulic pump (w2) and the electric motor (w1) driving the hydraulic pump (w2) is capable of energy recovery.

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