NL2031515B1

NL2031515B1 - A hybrid propulsion system for a vessel and Method for controlling a hybrid propulsion system for a vessel

Info

Publication number: NL2031515B1
Application number: NL2031515A
Authority: NL
Inventors: Baar René
Original assignee: Wijnne & Barends Cargadoors En Agentuurkantoren B V
Priority date: 2022-04-06
Filing date: 2022-04-06
Publication date: 2023-10-25
Also published as: WO2023195851A1

Abstract

Title: A hybrid propulsion system for a vessel and Method for controlling a hybrid propulsion system for a vessel Abstract A hybrid propulsion system for a vessel, including: - a main propulsion engine (13) having a dedicated engine controller for controlling speed of an output shaft (1 1) of the engine (13), based on an engine speed setpoint signal; -a central controller (CS); - at least one electric motor-generator (12A, 12B), having an output shaft that is preferably directly connected to an output shaft (1 1) of the engine (13), wherein the at least one electric motor-generator (12A, 12B) has a dedicated electric motor-generator controller for controlling speed of the respective output shaft of the electric motor-generator (13), based on an electric motor-generator speed setpoint signal; wherein the central controller (CS) is configured for setting the electric motor-generator speed setpoint, such that the at least one electric motor- generator (12A, 12B) operates at substantially or nearly the same setpoint as the main propulsion engine (13).

Description

P132141NL00

Title: A hybrid propulsion system for a vessel and Method for controlling a hybrid propulsion system for a vessel

The invention relates to a hybrid propulsion system for a vessel.

Also, the invention provides a method for controlling a hybrid propulsion system for a vessel.

BACKGROUNG OF THE INVENTION

When ships are equipped with geared drives, the engine speed and propulsor speed are not coupled directly, because the output speed of medium- or highspeed combustion engines is higher than the speed required for efficient operation of the propulsor. When a medium- or highspeed combustion engine is used as prime mover, a reduction gearbox is implemented to reduce the rotational speed of the prime mover output to that required for the propulsor.

The gearbox normally consists of at least an input shaft to connect the medium- or highspeed combustion engine and an output shaft to connect to the propeller shaft.

When an electric shaft motor/generator is used in a geared drive this is often done through an extra PTO/PTI/PTH shaft which is connected through gears with the rest of the gearbox. When the system works in PTO (power Take Out), PTI (Power Take In) or PTH (Power Take Home) mode the torque on the electric motor/generator and hence the pressure on its tooth will always be in one direction. In such systems, normally, all shaft are connected through gears with one another.

When an electric shaft motor/generator is used the torque when generating, is in the reverse direction of that when motoring. This reversing will cause gear backlash when the electric shaft motor/generator is connected through gears, as is indicated in Figure 1. When gear backlash often occurs in marine transmissions, it will wear excessively.

SUMMARY OF THE INVENTION

The present invention aims to provide an improved hybrid propulsion system and method for a vessel. In particular the invention aims to provide a system that is more durable, smaller, less costly and more energy efficient than known battery hybrid systems on ships. Also, an aspect of the invention aims to provide an improved system that can be retrofitted with relative ease.

According to an aspect, a goal of the invention is to provide a ship propulsion system which is more economic overall (e.g. with respect to,

CAPEX, OPEX, fuel consumption, amount and size of necessary components and maintenance) than known systems, which general consist of a medium- or highspeed combustion engine which drives a propulsor and optional an electric shaft motor/generator through a gearbox.

According to an aspect of the invention one of more of the above- mentioned objects are achieved by the features of claim 1.

Advantageously, there is provided a hybrid propulsion system for a vessel, including: - a main propulsion engine having a dedicated engine controller for controlling speed of an output shaft of the engine, based on an engine speed setpoint signal; - at least one electric motor-generator, having an output shaft that is preferably directly connected to an output shaft of the engine, wherein the at least one electric motor-generator has a dedicated electric motor- generator controller for controlling speed of the respective output shaft of the electric motor-generator, based on an electric motor-generator speed setpoint signal; wherein the central controller is configured for setting the electric motor-generator speed setpoint, such that the at least one electric motor- generator operates at substantially or nearly the same setpoint as the main propulsion engine.

In this way, energy efficient propulsion can be achieved, at relatively low system components wear. In particular, outputs (output shafts) of the engine and electric motor-generator(s) are preferably directly linked so that no gear box or gear transmission is required there-between.

Moreover, preferably each electric motor-generator (EMG) operates at substantially or nearly the same setpoint (e.g. an rpm setpoint, i.e. shaft speed) as the main propulsion engine, in particular during a load-balancing period, allowing significant engine fuel consumption reduction, lowering sailing costs and increasing environment friendly operation. It follows that according to the embodiment of the invention, the hybrid ship propulsion system can be configured to provide load balancing, in particular during load fluctuations.

According to an embodiment, for example, the central controller can be communicatively connected to (a remote) electric motor-generator controller for setting the electric motor-generator speed setpoint by transmitting an electric motor-generator speed setpoint signal to the electric motor-generator controller, such that the at least one electric motor- generator operates at the same speed and substantially the same (or nearly the same) setpoint as the main propulsion engine.

Alternatively, for example, the electric motor-generator controller can be part of or integrated with the central controller, in which case the central controller can set the setpoint internally (i.e. without transmitting an electric motor-generator speed setpoint signal to a remote controller).

According to a preferred embodiment the output shaft of the engine and the output shaft of each electric motor-generator are arranged in-line with each other and/or integrated with each other.

This can provide a relatively compact, durable configuration. For example, the engine can be arranged in-between two electric motor- generators, wherein all shafts (of engine and EMGs being aligned and directly connected).

Besides, according to an embodiment, a said output shaft (e.g. of the engine) can be indirectly connected to a vessel propulsion shaft via a reduction gear system. In this way, efficient power transfer between vessel torque generators (i.e. the engine and each respective EMG) and a respective vessel propulsion shaft can be achieved.

The main propulsion engine can e.g. be a combustion engine, for example a diesel engine, gas engine or a multiple-fuel engine.

According to an embodiment, the engine controller can be configured to monitor engine speed and to adjust one or more adjustable engine components, e.g. a fuel quantity feed unit and/or an air feed unit and/or combustion initiation unit, based on monitored engine speed and the engine speed setpoint signal. The engine controller can e.g. include or be connected to a shaft speed sensor for detecting engine shaft speed. The engine controller can be part of the engine or integrated therewith, or be arranged remote from the engine. The engine controller can be or include for example an electronic fuel injection controller and/or an electronically controlled governor of the engine.

According to an embodiment, the or each electric motor-generator controller (EMG controller) can be configured to monitor EMG shaft speed and to adjust one or more adjustable electric motor-generator components, e.g. switching means for switching between the motor-generator between a torque generating mode and an energy regeneration mode, based monitored motor-generator shaft speed and the motor-generator speed setpoint signal.

For example, according to an embodiment, the EMG controller can be configured to have the EMG operate as an electric generator (taking up shaft torque) in case the EMG controller determines that the detected shaft speed is higher than the respective setpoint shaft speed (based on the received setpoint signal), and according to an embodiment, the EMG controller can be configured to have the EMG operate as an electric motor (generating torque) in case the EMG controller determines that the detected shaft speed is lower than the respective setpoint shaft speed (based on the received setpoint signal).

Each EMG controller can e.g. be part of the respective EMG or integrated therewith, or be arranged remote from the EMG. The EMG 5 controller can e.g. include a memory for storing a electric motor-generator setpoint signal received from the central controller. Additionally or alternatively, according to an example, each EMG controller can be integrated in the central controller (for example in respective EMG controller software code of software, e.g. a dedicated EMG controlling routine, executed by the central controller).

According to an embodiment, the system includes a least one inverter unit, for example a frequency invertor, for electrically connecting electric input/output terminals of the at least one electric motor-generator to at least one electric energy storage buffer.

For example, a said EMG controller or the central controller can be communicatively connected to the at least one invertor unit for setting or adjusting inverter operation, for example for setting electric power throughput based on the monitored electric motor-generator shaft speed (i.e. engine shaft speed) and the electric motor-generator speed setpoint signal.

In this way, load balancing can be achieved in a straight-forward manner, via the or each frequency invertor unit, under central control of, i.e. fed by one or more control signals from the EMG and/or the central controller.

It should be observed that, according to an embodiment, the EMG controller can be part of or integrated with the invertor unit (that is associated with that EMG). In other words, the EMG controller can also be called an invertor controller of the respective invertor that is associated with the EMG.

Similarly, according to an embodiment, the EMG controller can be part of or integrated with the central controller.

According to a preferred embodiment, the central controller is configured to detect or respond to electric overload in at least one system component, and/or to detect malfunction of at least one system component.

For example, the central controller can be configured to stop or reduce load balancing in case electric overload and/or a malfunction is detected, to avoid (further) damage or system failure.

Optionally, the central controller can be communicatively connected to the engine controller and can be configured for setting an engine speed setpoint by transmitting an engine speed setpoint signal to the engine controller. Further, alternatively, the central controller can be communicatively connected to the engine controller for receiving an engine speed setpoint from the dedicated engine controller. Also, optionally, the central controller and engine controller can be integrated with each other (e.g. engine controller software code can be part of software executed by the central controller).

According to an aspect of the invention, there is provided a method that is defined by the features of claim 12. In this way, the above-mentioned advantages can be achieved.

According to an embodiment there is provided a method for controlling a hybrid propulsion system for a vessel, the system e.g. being a system according to the invention, the hybrid propulsion system at least having a main propulsion engine and at least one electric motor-generator, wherein output shafts of the engine and the at least one electric motor- generator are directly connected, and preferably arranged in-line with each other and/or integrated with each other, the method including: - providing an engine speed setpoint signal to a dedicated engine controller for autonomous controlling the speed of the output shaft of the engine, and

- providing an electric motor-generator speed setpoint signal to at least one dedicated electric motor-generator controller for autonomous controlling the speed of the output shaft of at least one electric motor- generator, wherein a load balancing period is provided during which the transmitted electric motor-generator speed setpoint signal indicates substantially or nearly the same speed as a speed indicated by the engine speed setpoint signal.

Preferably, the method includes transmission of the electric motor- generator speed setpoint signal by a central controller.

According to an embodiment, the central controller receives the engine speed setpoint signal from an engine controller and/or transmits the engine speed setpoint to an engine controller, for example utilizing wired and/or wireless transmission.

The method preferably includes providing an initialization period (i.e. before said load balancing period, e.g. during acceleration of shaft speed from standstill or from a relatively low shaft speed) during which the speed of the output shaft of the engine is compared to a respective initial engine speed setpoint (and wherein initially no electric motor-generator speed setpoint signal is transmitted to the EMG controller, or only an EMG speed setpoint signal that differs from the engine speed setpoint signal), wherein the load balancing period is only started when it is determined that the speed of the output shaft of the engine has reached or exceeded the initial engine speed setpoint.

In this way, a reliable and fuel-efficient operation can be achieved.

Preferably, the load balancing period can be (automatically) stopped or interrupted in case an electric overload and/or malfunction in at least one system component is detected.

Further, an aspect of the invention provides a central controller program product, for example a computer program, comprising instructions which, when the program is executed by a central controller, cause the central controller to carry out the method of the invention. The central controller may optionally include or be integrated with an afore-mentioned engine controller. Alternatively or additionally, The central controller may optionally include or be integrated with an afore-mentioned EMG controller.

According to an embodiment of the invention the system uses a combination of at least one electrical drive and a medium- or highspeed combustion engine for the ship propulsor (the electric drive being implemented as an EMG). Depending on weather conditions and sea-state, the electric motor/generator (EMG) can be powerful enough to eliminate or strongly reduce transient loads due to wind and waves on the medium or highspeed combustion engine. As mentioned above, this elimination or strong reduction of the transient loads on the total drive train results in less wear and tear, a reduction of the fuel consumption and less harmful emissions.

According to a preferred embodiment, at least one electric motor/generator is connected in-line with the driveshaft of a (medium- or highspeed) combustion engine. This can be done e.g. by connecting the electric motor/generator in line through a gearbox via a through shaft (optional via a torsional vibration damper) to the combustion engine and/or via a torsional vibration damper to the non-drive end of the medium or highspeed combustion engine. Said gearbox can serve to couple the shafts to a propeller shaft.

According to an embodiment, generated electrical energy can be stored in a electrical buffer device; in general this buffer device can be (but not limited to) a supercapacitor( EDLC) system, lithium-ion capacitor system or battery system.

According to an embodiment, the electric motor/generator can be of an AC-type like (but not limited to) an induction machine, synchronous machine, permanent magnet synchronous machine, synchronous reluctance machine, permanent magnet assisted synchronous reluctance machine.

The energy from and too the electric motor/generator can e.g. be controlled by a said frequency inverter. The inverter unit can convert the

AC-voltage/current on the electric motor/generator side to a DC- voltage/current and vice versa. The energy flow from and to the frequency inverter on the DC-side can be fed through a bi-directional DC/DC-converter to a buffer system, for example a supercapacitor system. The advantage of a bi-directional DC/DC-converter compared to a direct connection of the buffer system is good control of a common DC-bus voltage of the frequency inverter and the DC/DC-converter. By doing this, there is more freedom of control for the energy storage system (ESS) and a power management system (PMS), for example a power management system that is provided by a central controller.

The presently proposed new hybrid propulsion system concept is well suited for conversion or upgrading of existing ships, without major change of existing components and without change to the existing control systems.

Further, the system can be configured such that when the hybrid system (or respective load balancing) is switched off the ships propulsion remains fully functional.

According to an embodiment, when using the/each electric motor/generator for load balancing (i.e. during a load balancing period) a torque direction of the electric motor/generator will normally change every time the bow of the ship hits or leaves a wave. This can happen multiple times a minute; this same phenomenon can happen to a larger extent, when the propulsor (partially) enters or leaves the water. To a lesser extent, the same can happen due to gusts of wind.

During load balancing, a resulting total torque of the combustion engine and the/each respective electric motor/generator can always be in one direction, because the torque of the combustion engine is generally always higher than that of the electric motor/generator(s) during normal use.

According to an embodiment, a motor/generator can be connected at a non-drive end of the combustion engine, and/or a motor/generator can be preferably connected in-line at a drive-end of the combustion engine, e.g. through a gearbox (that connects to drive end to a propeller shaft), preferably no extra backlash will occur compared to situations where the motor/generator only works in generator-mode or motor(boost)-mode (e.g. when connected through an extra gear).

In other words, the hybrid ship propulsion system preferably includes a (medium- or highspeed) combustion engine which drives at least one electric motor/generator (EMG) and a propulsor (e.g propeller shaft) per drivetrain. The propulsor is preferably driven indirectly, through a gearbox, at a desired speed. An electric motor/generator is preferably connected at a non-drive-end of the combustion engine and/or through the gearbox (via a through shaft) without gears and in line with the shaft of the combustion engine. During operation, the combustion engine can deliver an average propulsive power, plus the losses in the electric hybrid system (electric motor/generator, optional controls and other optional current-carrying parts). The or each respective electric motor/generator can handle transient loads caused by waves and wind fluctuations (acting on the respective propulsor). When a propulsive load (on the propulsor) is below an average load on the combustion engine, excess energy can be stored via the electric motor/generator(s) in an electric energy buffer. When the propulsive load is above the combustion engine average load, the buffered excess energy can be fed to the electric motor/generator(s) to support the main combustion engine in maintaining its power and speed (a favorable operating point).

The hybrid ship propulsion can be self-sustaining and regenerative, therefore it is suitable for ships with power limitations (among others, due to regulations, technical reasons, etc.) and relatively easy to retro-fit an existing (non-hybrid) drivetrain, without the need of an external energy source, since there is no need to feed additional energy to the propulsion system. The hybrid system is also suitable for most if not all mechanical (propeller(s), jet(s), etc.) driven ship propulsion systems, where additional energy is added or taken by means of motor/generators and/or the ships grid.

By connecting the electric motor/generator without gears (i.e. directly) to the (medium- or highspeed) combustion engine, preferably no mechanical gear backlash occurs during the switch from motoring to generating of the electric motor/generator and vice versa. The buffer for the electric energy generally consists of (but is not limited to) a number of supercapacitors, lithium-ion capacitors, batteries or a combination of mentioned buffers. Due to the frequent loading and un-loading mainly caused by waves, an electrical energy buffer which can endure many (millions) charging- and discharging cycles, with a low equivalent series resistance for efficiency reasons and high peak power is the preferred option. During the time of the invention, the only electrical energy buffer with all these characteristics, which are commercially widely available, appear to be supercapacitors (EDLC’s, Electric Double-Layer Capacitors), however, application of other types of buffers is not to be ruled out.

Moreover, the energy buffer can include a kinetic energy buffer, e.g. a flywheel.

According to an embodiment, power demand and favorable speed on the combustion engine can be maintained and most of the transient loads due to wind and waves are transferred to the at least one electric motor/generator, having faster dynamic response than an engine response, therefore, the combustion engine can run most economical and produce less harmful emissions. Also, due to the elimination or strong decrease in acceleration and deceleration and speed fluctuation (in the drive train) with respect to a desired value, the wear and tear of the total driveline will strongly reduce.

Further advantageous embodiments are described in the dependent claims. The invention will now be explained in more detail with reference to the drawings that depict non-limiting examples.

Figure 1 shows an example of gear backlash;

Figure 2 depicts part of an example of a hybrid propulsion system according to an embodiment of the invention;

Figure 3 is a diagram, in particular a single line diagram (SLD), of a further embodiment of the system shown in Figure 2, the system containing additional non-essential features;

Figure 4 shows a first detail of the diagram of Figure 3;

Figure 5 shows a second detail of the diagram of Figure 3, containing further non-essential features; and

Figure 6 depicts a graph of an example of engine setpoint control

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Figure 1 shows part of two gears 6, 8, that can be part of a prior art drive train of a hybrid propulsion system for a vessel. In such a known drive train, such interlinking gears 6, 8 can be part of a transmission for coupling e.g. an electromotor output shaft indirectly to an engine output shaft, for driving a propeller shaft. However, this can lead to gear backlash, indicated by the arrows in Figure 1, in particular when an electric shaft motor/generator is and torque when generating, is in the reverse direction of that when motoring. In particular, Figure 1 depicts a gear train and that there is space between gears, when frequent torque changes appear the gear tooth will wear excessively e.g. noted as gear backlash. To prevent excessive wear due to gear backlash it is preferred to connect the EMGf{s) and the engine in line with each other without gears.

Figure 2 shows a non-limiting example, wherein gear backlash can be significantly reduced or avoided. Figure 4 shows the example in more detail (as a Single Line Diagram). Besides, Figures 3 and 5 show that such a system can e.g. be provided with further (non-essential) features (such as one or more further, external or remote generators, motors, and/or devices)

In particular, Figures 2 and 4 schematically shows a hybrid propulsion system for a vessel, including a main propulsion engine 13. The main propulsion engine 13 can e.g. be a combustion engine, for example a diesel engine, gas engine or a multiple-fuel engine.

The engine 13 preferably has a dedicated engine controller 35 for controlling speed of an output shaft 11 of the engine 13, based on an engine speed setpoint signal.

The system also includes at least one electric motor-generator 124A, 12B, having an output shaft that is preferably directly connected to an output shaft 11 of the engine 13. Preferably, the at least one electric motor- generator 12A, 12B has a dedicated electric motor-generator controller (EMG controller) for controlling speed of the respective output shaft of the electric motor-generator), based on an electric motor-generator speed setpoint signal. According to an embodiment, the setpoint signal can be derived from an engine speed setpoint and a state of charge of an energy buffer E101.

The depicted system includes two EMGs, a first one 12A e.g. having a shaft 31 that is connected to a front output shaft 11A of the engine and a second one 12B that e.g. has a shaft 32 that is connected to a rear output shaft 11B of the engine.

As follows from the drawings, the output shaft 11 of the engine 13 can be indirectly connected to a vessel propulsion shaft 3, for example, a propeller shaft 3 (provided with a propulsor/propeller 1), for example via a transmission unit 5 (e.g. a gearbox) that preferably includes a reduction transmission.

For example, the transmission unit 5 can include an input shaft 9 that is coupled to the engine shaft 11. Optionally, the transmission unit 5 can be arranged between the combustion engine 13 and an EMG 12A. It is preferred that the input shaft 9 of the transmission unit is axially aligned with the output shaft 31 of the respective EMG 12A and the output shaft 11 of the engine 13.

The various shafts can be interconnected in various ways, e.g. including suitable shaft connectors 10A, 10B, 10C (known as such). For example, an EMG shaft 32 can be directly connected to an engine shaft 11B vla a respective shaft connector 10B. An engine output shaft 11A can be directly connected to a transmission unit input shaft 9 via a respective shaft connector 10C. Also, an EMG shaft 31 can be directly connected to a transmission unit input shaft 9 via a shaft connector 10A. A said shaft connector can e.g. be or include a torsional vibration damper, or a different type of connector.

The transmission unit 5 can include transmission means, e.g. a number of gears 6, 8 for transmitting torque between an input shaft 9 and output shaft 3 of the transmission unit 5.

The central controller CS can e.g. be communicatively connected to each electric motor-generator controller. The central controller CS can be configured for setting the electric motor-generator speed setpoint, e.g. by transmitting an electric motor-generator speed setpoint signal to the electric motor-generator controller in case that controller 15 remote from the central controller CS, or internally (in case the EMG controller is part of the central controller CS), such that the at least one electric motor-generator 12A, 12B operates at substantially the same, e.g. nearly (i.e. just below), setpoint as the main propulsion engine 13.

Further, the output shaft 11 of the engine 13 and the output shaft of each electric motor-generator 12A, 12B can be arranged in-line with each other and/or integrated with each other.

The engine controller 35 can be configured in various ways, for example it can be configured to (in particular autonomously) monitor engine speed and to adjust one or more adjustable engine components, e.g. a fuel quantity feed unit and/or an air feed unit and/or combustion initiation unit, based monitored engine speed and e.g. the engine speed setpoint signal (the setpoint signal for example indicating the engine speed that is to be instantaneously achieved by the engine 13, for example according to an engine control algorithm with respect to external distortions, as will be clear to the skilled person).

Each electric motor-generator controller can be configured to monitor motor-generator shaft speed. The electric motor-generator controller can be configured to adjust one or more adjustable electric motor- generator components, e.g. switching means for switching between the motor-generator between a torque generating mode and an energy regeneration mode, based monitored motor-generator shaft speed and the motor-generator speed setpoint signal. Said switching means can e.g. be provided by a least one inverter unit E105A (see Figures 4, 5), electrically connecting the EMG(s) 12A, 12B to an electric energy buffer E101.

In particular, the system can include a least one inverter unit

E105A, for example a frequency invertor, for electrically connecting electric input/output terminals of the at least one (or each) electric motor-generator 12A, 12B to at least one electric energy storage buffer. It is preferred that said central controller CS 1s communicatively connected to the at least one invertor unit E105A (e.g. via a communication link C2) for setting or adjusting inverter operation, for example for setting electric power throughput based on the monitored motor-generator shaft speed and the motor-generator speed setpoint signal. Optionally, a or each said EMG controller can be integrated in or be part of the invertor unit E1054, as will be appreciated by the skilled person.

The central controller CS can be configured to detect or respond to electric overload in at least one system component, and/or to detect malfunction of at least one system component.

The central controller CS can be communicatively connected to the engine controller 35 and configured for setting an engine speed setpoint by transmitting an engine speed setpoint signal to the engine controller 35, or alternatively for receiving an engine speed setpoint signal from the engine controller 35 in which case the engine controller 35 transmits the setpoint to the central controller CS.

Operation of the system, shown in Figures 2 and 4, can include a method for controlling a hybrid propulsion system for a vessel, the hybrid propulsion system at least having a main propulsion engine 13 and at least one electric motor-generator 12A, 12B. Output shafts of the engine 13 and the at least one electric motor-generator 12A, 12B are preferably directly connected, and preferably arranged in-line with each other and/or integrated with each other. The method can include at least the following steps: - providing an engine speed setpoint signal (to the engine controller 35) for autonomous controlling the speed of the output shaft 11 of the engine 13; and - providing (e.g. transmitting in case of a remote controller) an electric motor-generator speed setpoint signal to each dedicated electric motor-generator controller for autonomous controlling the speed of the output shaft of at least one electric motor-generator 12A, 12B, wherein a load balancing period is provided during which the transmitted electric motor-generator speed setpoint signal indicates (substantially, nearly) the same speed as a speed indicated by the engine speed setpoint signal.

During operation it is preferred that the electric motor-generator speed setpoint signal is being transmitted by the central controller CS. In particular, the central controller CS can receive the engine speed setpoint signal from the engine controller 35. Alternatively, or additionally, the central controller CS can transmit the engine speed setpoint to an engine controller 35.

It is preferred that the method includes providing an initialization period during which the speed of the output shaft 11 of the engine 13 is compared to a respective initial engine speed setpoint. The load balancing period is preferably only started when it is determined that the speed of the output shaft 11 of the engine 13 has reached or exceeded the initial engine speed setpoint. For example, the load balancing period can be (preferably automatically) be stopped or interrupted in case an electric overload and/or malfunction in at least one system component is detected.

As will be appreciated by the skilled person, there can be provided a central controller program product, for example a computer program, comprising instructions which, when the program is executed by a central controller, cause the central controller CS to carry out the afore-described innovative method. According to a non-limiting embodiment, functionality of the engine controller 35 can be partly or fully integrated with a central control unit or controller CS. The same holds for a said EMG controller.

More particularly, as follows from the above, Figures 2 and 4 (SLD) show a highly schematic mechanical illustration of an example of a hybrid driveline. The system preferably includes at least one propulsor 1 which is connected to the propulsor shaft 3 which e.g. runs through a shaft pipe 2.

The propulsor shaft 3 can be connected with a flange 4 of an output of a transmission 5. The transmission 5 can have engaging gears 6, 8 with a certain ratio, so that a speed of the (e.g. medium- or highspeed) combustion engine 13 matches with a desired speed of the propulsor 1.

The propulsor shaft 3 can be connected with a large gear 6. The combustion engine's shaft output shaft 11A can be connected to the input- shaft 9 of the transmission 5. The input-shaft 9 of the transmission can be connected with a smaller gear 8 (i.e. smaller than said large gear 6) of the transmission 5, such that an engine shaft speed is reduced by the transmission 5 to a lower propulsor shaft speed.

The input-shaft 9 of the transmission can extend through the transmission 5, e.g. to a side faced away from the engine, e.g. to be used as a

PTI/PTO or PTH. A first electric motor/generator 12A can be connected to the input-shaft 9 on such a PTI/PTO/PTH side of the transmission, e.g. via a torsional vibration damper 11A or a different type of coupler. Another option 1s to couple an electric motor/generator 12B via a connector (e.g. a torsional vibration damper) 10B directly to the combustion engine 13, or the connect both EMGs to the engine (as in Figures 2-4).

One or more optional generators 14 can be included (see Figures 3, 5) can be used to provide additional power to the system, e.g. to the main drive train. Such an optional generator 14 can e.g. feeds the EMG(s) 12A, 12B with electrical power, in particular in a situation wherein the EMG(s) 12A, 12B work as motor (e.g. in case where boost 1s required or when power to home -PTH- is required).

An example of electrical equipment of the hybrid propulsion system is shown in highly schematic form in Figures 3-5. It can include a said central controller CS, which can be communicatively connected to the engine 13 via a first signal line S1. The controller CS can be communicatively connected to the first EMG controller via a second signal line (communication link), for example signal a line C2 (see Figure 4) in case the controller is part of a respective invertor E105A of the first EMG. The controller CS can be communicatively connected to the second EMG controller via a third signal line (communication link), for example signal a line C2 (see Figure 4) in case the controller is part of a respective invertor

E105A for the second EMG.

Alternatively, in particular in case a said EMG controller is integrated in the central controller, no external communication line is required for connecting such EMG controller to the central controller, as will be appreciated by the skilled person.

Further, the controller CS can be communicatively connected to a said frequency inverter E105A via a respective signal line (communication link) C2. Optionally, a dedicated signal line S2 can be present for communication between the central controller CS and the energy buffer

E101, for example such that the controller can monitor the energy buffer

E101 and/or receive state-of-charge information from that buffer.

The system can include at least one bi-directional DC/DC convertor, electrically connected to electrical outputs of the frequency convertor E105A on one hand and the energy buffer E101 on the other, for ensuring that proper voltage levels are applied therebetween. Optionally, e.g. depending on the type of DC/DC-converter, an inductor unit E103 is installed between the DC/DC convertor E104 and the energy buffer E101.

The DC/DC-convertor is preferably communicatively connected to the central controller CS, via a respective communication link C1, for exchanging information or a signal there-between, e.g. concerning current, voltage and power level(s) at the DC/DC-convertor and/or DC-DC-convertor operation

At least a pre-charger E111 can be present, for charging the buffer independent of EMG and engine operation. A further signal line C3 can be present for communicatively connecting the pre-charger to the central controller CS, e.g. for controlling pre-charger operation by the controller CS and/or for providing pre-charger state information to the controller CS.

Further, the system can include a number of circuit-breakers

E107A, E102A, E102B, E102C, E112, E102F, E107C, for electrically connecting two system components when the breaker is in a closed state and for electrically disconnecting system those components when the breaker is in a opened state. Each such circuit breaker/contactor E107A, E102A,

E102B, E102C, E112, E102F, E107C is preferably controlled remotely, by the central controller CS.

Similarly, as will be appreciated by the skilled person, the system can include a number of fuses E106A (e.g. highspeed aR-fuses) at suitable fuse locations.

The system can include e.g. at least one power cable or busbar

E110A, E110B, E110C (electrical power conductors), as will be appreciated by the skilled person, for electrically interconnecting electrical system components (in particular electrical terminals of the components).

Depending on their location in the circuit, the power cable can carry/conduct

DC (direct current) or AC (alternating current) during use.

Preferably, a number of electrical components CS, E105A, E104,

E111 of the system can e.g. have or be connected to an external power supply (not shown), so that a respective integrated control can work independent of a state of charge of the electrical energy buffer E101.

Figure 6 schematically depicts a graph showing an example of an engine start-up process. The setpoint SP is send from the bridge to the engine controller 35. The engine controller has among others a speed controller, which 1s generally (but not limited to) a PI(D) speed controller.

When the setpoint is switched from (in this example) 0 to 10 rpm at t1, the engine will control itself towards the setpoint SP. In many cases the speed controller has a slight overshoot due the the settings of the PID) speed controller. The process value PV is the speed measured in rpm.

When the process value reaches the set point SP value at t2, the hybrid system is triggered and will prevent the overshoot and store the excessive energy in the energy buffer E101.

During operation, for example, when the hybrid system is turned on, the CS control system can first run an initialization process to check if all components and itself are in a desired operating state. For clarity the initialization can be described as a ‘zero state’.

The CS control system can check itself if everything works (e.g. as programmed). The CS control system can e.g. check the state of charge (SOC) and/or voltage of the electrical energy buffer E101. Preferably, when the SOC is too low (e.g. lower than a predefined threshold SOC) respective contactors E102-C, E102-B can be closed. A pre-charger E111 can then be switched on by the control system CS (using communication link C3), for charging the electrical energy buffer E101 to a desired level. When a desired charge level is reached (e.g. normally 15..90% of a common-DC voltage of a common conductor E110A) and before the inverter E105-A is turned on, the

E111 pre-charger is preferably (automatically) turned off, and contactors

E102C, E102B of a conductor connecting the charger to the energy bugger

E101 can be set to respective open states. Besides, for example, during initialization, when the state of charge of the energy buffer E101 is sufficient (normally 15..90% of the common-DC voltage E110A) there is no need for pre-charging. Preferably, various relevant states of the electrical energy buffer E101 (such as state of charge, voltage, temperature, balancing, etc..) can also be measured by the control system CS, or information concerning such states can be provided to the control system,

CS, via a respective communication link S2.

It is preferred that a common DC-bus conductor E110A can be pre- charged by the electrical energy stored in the electrical energy buffer E101, via a pre-charge circuit (not shown).

During operation (and e.g. when contactor E102A is closed), the bi- directional DC/DC-converter E104 can bring the voltage level of the common

DC-bus E110A to a desired level. The skilled person will appreciate that the bi-directional DC/DC-converter E104 can be of any type as long as it has the functional capabilities to keep a common DC-bus voltage at a desired level (in particular by transporting energy from and to the electrical energy buffer E101). As an example, it can be an interleaved DC/DC converter with coils E103 (as 1s shown).

Further, after initialization, in particular when the common DC- bus E110A is at a desired level, the frequency inverter E105A can be fully functional (e.g. after its own initialization), wherein energy can flow via that convertor from and to the/each EMG 12A, 12B.

Moreover, as is shown in Figure 6, after the combustion engine 13 has started (the starting e.g. being initiated from the bridge, setting a proper engine speed setpoint and transmitting the setpoint to the engine controller 35, the communication line between the engine controller and the central controller CS transmitting the setpoint to the central controller CS), the engine 13 will accelerate to its desired speed (as set by the respective setpoint). As is mentioned before, the combustion engine 13 can be fitted with a speed governor, for example having a PI(D) proportional integral (derivative) controller 35, for regulating engine speed.

The PI(D)-controller or engine controller 35 is preferably controlled so that the speed (process variable) will have a (small, acceptable) overshoot to reach its setpoint within an acceptable time (see Figure 6).

Also, the system (in particular the central controller CS) can be configured such that when no (small) overshoot occurs there is no need for running in hybrid mode and the hybrid mode can (automatically) be turned off.

It is preferred that after initialization, when the speed of the combustion engine 13 crosses the setpoint for a first time, the hybrid load balancing system starts to work (i.e. a respective load balancing period is started). The load balancing period can also be initiated at a different time, or based on other criteria. It is preferred that during the load balancing period, both the engine 13 and the one or more EMGs 12A, 12B are controlled by the respective controllers CS or the integrated controller of the inverter 105A to achieve exactly or nearly (e.g. substantially) the same setpoint SP (i.e. speed, rpm).

In particular, during the load balancing, the CS control system can get/acquire the same setpoint and process variable for the speed, as the medium speed combustion engine 13. It is preferred that an initial set point (speed) for each electric motor generator (12-A and/or 12B) is slightly below set point SP for the combustion engine 13, due to energy loss in the components of the dynamic hybrid system. Reaction speed of an electric motor/generator is generally multiple times faster than that of an combustion engine. It follows that -during the load balancing period- each electric motor generator 12A, 12B works as an electric generator (thereby limiting the overshoot and reach it’s setpoint within the power limits of the electrical components as fast as possible with respect to the state of charge of the energy buffer E101) and store the generated electrical energy in the electric energy buffer E101.

On the other hand, when the process variable PV becomes lower than the set point SP, each electric motor/generator(s) operates as motor, using energy from electric energy buffer E101 to keep the desired speed at the set point level. Thus, (regenerative) load balancing is achieved.

In an embodiment, the resulting hybrid ship propulsion with load balancing system can generate more energy in generator mode than it uses in motor load, due to losses to and from the electrical energy buffer E101 and the EMG(s). It 1s preferred that this process continues, e.g until the set point is changed. The skilled person will appreciate that when the process value PV reaches the new set point, the system will work as mentioned above(or in reverse direction when the setpoint is lower than the initial setpoint) and will continue this way until the set point is changed again or when the system is shutdown.

It is preferred that the energy level of the electrical energy buffer

E101 is constantly monitored by the control system CS. The control system is preferably configured to control the frequency inverter E105A in such a way that an average energy level in the electrical energy buffer E101 stays within the boundaries of a desired level (i.e. within a certain predetermined range).

According to an embodiment, during use, when load fluctuations become relatively large (e.g. too large for the system to maintain a constant speed at the desired set point SP), the control system CS can be configured to minimize the speed fluctuations within its capabilities. By doing this, the control system CS can protect electric system (E12-A and/or E12-B, E110-B,

E105-A, E110A, E104, E103, E102-A, E106-A, E101) in the circuit/energy loop from overload conditions.

It is preferred that one or more (preferably all) component in the electric circuit part of the system are fitted with sensors to sense overload or are protections by itself. In that case, when one of the components in the energy loop senses overload, the power flow is preferably automatically reduced, for example by the bi-directional DC/DC converter E104 and/or the frequency inverter E105, preferably under control of the central controller

CS. Similarly, it is preferred that when a malfunction is sensed and/or as one of the overload protections is activated, most or all the electric components shut down, wherein the ship propulsion continues to operate as without activity of those electric components (preferably with the exception of inertia of each EMG).

Moreover, during operation, the central controller CS can be configured such that when load fluctuation becomes too low to be economical viable, the load balancing period is stopped. When the hybrid system 1s switched off the ships propulsion, using e.g. the engine 13 only to generate torque for driving the propulsor 1, preferably remains fully functional.

The present invention provides various advantages, compared to known hybrid ship propulsion systems. The present system does not have to rely on extra energy sources (i.e. it can be fully self-generating). The system is very suitable for use in a ship having certain power limitations (e.g. due to technical and/or regulatory reasons). Also, no or substantially no necessary change is required to existing control and safety systems. A significantly reduced amount of power and energy storage capabilities can be required for the components, compared to motoring and/or generating only systems.

Optionally, a said electric-motor/generator can be used as shaft generator which is independent of the rotating speed when a grid converter 1s added to power a ships grid, for example as boost motor, as power to home motor and as a combination of such applications, while load balancing and as stand-alone for load balancing

Operation of the system can lead to significant energy reduction and therefore significant reduction of combustion engine exhaust gasses.

Moreover, the system leads to relatively low wear on the respective ship propulsion drive train. Besides, the present system and method can be retrofitted with relative ese to existing systems and methods.

The skilled person will appreciate that the invention is not limited by the above-described embodiment. The invention is not limited to these embodiments, the invention being defined by the claims that define the scope of the invention.

For example, a setpoint signal can be various types of signals, e.g. a digital signal or an analogue signal, and can be transmitted in various ways, e.g. via a wired or wireless transmission link. The setpoint signal can include information for a respective motor or engine setpoint (the setpoint being e.g. a predetermined rpm of an output shaft of the motor or engine).

An engine setpoint can e.g. be a predetermined engine output shaft speed (that 1s to be achieved by the engine). An electric motor-generator setpoint can e.g. be a predetermined electric motor-generator output shaft speed (that is to be achieved by the EMG).

Further, according to a preferred embodiment, the method according to the invention includes transmission of the electric motor- generator speed setpoint signal by a central controller (to the EMG).

Alternatively, in case the central controller is integrated with the engine controller, the engine controller can function as central controller of the electric motor-generator speed setpoint signal by a central controller and can transmit to the electric motor-generator speed setpoint signal to the

EMG. For example, in the latter case, the engine controller can include dedicated engine controller software that is executed by the engine controller, the software having an engine controller routine as well as an

EMG controller routine (both routines being executed by the controller), wherein setpoint information can be exchanged between the software routines to carry out the invention.

Further, preferably, the or each one electric motor-generator (124A, 12B) operates at substantially or nearly the same setpoint as the respective main propulsion engine (13), for example (during each load balancing cycle) at nearly or just below the setpoint of the respective main propulsion engine. For example, on average during a load balancing cycle, the or each one electric motor-generator (12A, 12B ) may operate at nearly the setpoint of the respective main propulsion engine such that the (on average) lower setpoint takes into account or compensates for electrical losses in the hybrid system (if any). Moreover or additionally, in case the setpoint of the or each

EMG is held at a constant level just below the setpoint for the engine (e.g. about 1% or about 2% below the setpoint for the engine), some additional electric energy can be generated.

Claims

ConclusiesConclusions

1. Hybride voortstuwingssysteem voor een vaartuig, omvattende: -een hoofdvoortstuwingsmotor (13) met een specifieke motorcontroller voor besturing van snelheid van een uitgangsas (11) van de motor (13), gebaseerd op een motorsnelheid-instelpuntsignaal; -ten minste een elektrische motorgenerator (12A, 12B), met een uitgangsas welke bij voorkeur direct is verbonden aan een uitgangsas (11) van de motor (13), waarbij de ten minste ene elektrische motorgenerator (12A, 12B) een specifieke elektrische motorgeneratorcontroller heeft voor besturen van snelheid van de respectieve utgangsas van de elektrische motorgenerator (13), gebaseerd op een elektrische motorgeneratorsnelheid- instelpuntsignaal; waarbij de centrale controller (CS) is geconfigureerd om het elektrische motorgeneratorsnelheid-instelpuntsignaal zodanig in te stellen, dat de ten minste ene elektrische motorgenerator (124A, 12B) werkzaam is bij in hoofdzaak of nabij hetzelfde instelpunt als de hoofdvoortstuwingsmotor (13).A hybrid propulsion system for a vessel, comprising: - a main propulsion engine (13) with a dedicated engine controller for controlling speed of an output shaft (11) of the engine (13), based on an engine speed set point signal; - at least one electric motor generator (12A, 12B), with an output shaft preferably directly connected to an output shaft (11) of the motor (13), the at least one electric motor generator (12A, 12B) having a specific electric motor generator controller for controlling speed of the respective output shaft of the electric motor generator (13) based on an electric motor generator speed set point signal; wherein the central controller (CS) is configured to adjust the electric motor generator speed setpoint signal such that the at least one electric motor generator (124A, 12B) operates at substantially or near the same setpoint as the main propulsion engine (13).

2. Het hybride voortstuwingssysteem volgens conclusie 1, waarbij de uitgangsas (11) van de motor (13) en de uitgangsas van elke elektrische motorgenerator (12A, 12B) op elkaar zijn uitgelijnd en/of met elkaar zijn geïntegreerd.The hybrid propulsion system according to claim 1, wherein the output shaft (11) of the engine (13) and the output shaft of each electric motor generator (12A, 12B) are aligned and/or integrated with each other.

3. Het hybride voortstuwingssysteem volgens conclusie 1 of 2, waarbij de uitgangsas (11) van de motor (13) indirect 1s gekoppeld aan een vaartuigvoortstuwingsas, bijvoorbeeld, een schroefas (1), bijvoorbeeld via een overbrengingseenheid (5) welke bij voorkeur een reductieoverbrenging omvat.The hybrid propulsion system according to claim 1 or 2, wherein the output shaft (11) of the engine (13) is indirectly coupled to a vessel propulsion shaft, for example, a propeller shaft (1), for example via a transmission unit (5) which is preferably a reduction gear. includes.

4. Het hybride voortstuwingssysteem volgens een der voorgaande conclusies, waarbij de hoofdvoortstuwingsmotor een verbrandingsmotor is, bijvoorbeeld een dieselmotor, gasmotor of een meervoudige-brandstof motor.4. The hybrid propulsion system according to any one of the preceding claims, wherein the main propulsion engine is a combustion engine, for example a diesel engine, gas engine or a multiple-fuel engine.

5. Het hybride voortstuwingssysteem volgens een der voorgaande conclusies, waarbij de motorcontroller is geconfigureerd om motorsnelheid te monitoren en om een of meer instelbare motorcomponenten, bijv. een brandstofhoeveelheidtoevoereenheid en/of een luchttoevoereenheid en/of verbrandingsinitialisatie-eenheid, aan te passen gebaseerd op gemonitorde motorsnelheid en het motorsnelheid-instelpuntsignaal.The hybrid propulsion system of any one of the preceding claims, wherein the engine controller is configured to monitor engine speed and to adjust one or more adjustable engine components, e.g., a fuel quantity supply unit and/or an air supply unit and/or combustion initialization unit, based on monitored engine speed and the engine speed setpoint signal.

6. Het hybride voortstuwingssysteem volgens een der voorgaande conclusies, waarbij de elektrische motorgeneratorcontroller is utgevoerd om motorgeneratorassnelheid te monitoren en om een of meer instelbare elektrische motorgeneratorcomponenten, bijvoorbeeld schakelmiddelen om de motorgenerator te schakelen tussen een koppelopwekkingsmode en een energieregeneratiemode, aan te passen gebaseerd op gemonitorde motorgeneratorassnelheid en het motorgeneratorsnelheid-instelpuntsignaal.6. The hybrid propulsion system according to any one of the preceding claims, wherein the electric motor generator controller is configured to monitor motor generator shaft speed and to adjust one or more adjustable electric motor generator components, for example switching means for switching the motor generator between a torque generation mode and an energy regeneration mode, based on monitored engine generator shaft speed and the engine generator speed setpoint signal.

7. Het hybride voortstuwingssysteem volgens een der voorgaande conclusies, omvattende ten minste een invertereenheid (E1054), bijvoorbeeld een frequentieinverter, voor elektrisch verbinden van elektrische ingangs/uitgangscontacten van de ten minste ene elektrische motorgenerator (12A, 12B) aan ten minste een elektrische energieopslagbuffer.The hybrid propulsion system according to any one of the preceding claims, comprising at least one inverter unit (E1054), for example a frequency inverter, for electrically connecting electrical input/output contacts of the at least one electrical motor generator (12A, 12B) to at least one electrical energy storage buffer .

8. Het hybride voortstuwingssysteem volgens conclusies 6 en 7, waarbij de EMG-controller en/of de centrale controller (CS) communicatief zijn verbonden aan de ten minste ene invertereenheid (E105A) om de inverteroperatie in te stellen of aan te passen, bijvoorbeeld om elektrische vermogensverwerking in te stellen gebaseerd om de gemonitorde motorgeneratorassnelheid en het motorgeneratorsnelheid-instelpuntsignaal.The hybrid propulsion system according to claims 6 and 7, wherein the EMG controller and/or the central controller (CS) are communicatively connected to the at least one inverter unit (E105A) to set or adjust the inverter operation, for example to electrical power processing based on the monitored engine generator shaft speed and the engine generator speed setpoint signal.

9. Het hybride voortstuwingssysteem volgens een der voorgaande conclusies, waarbij de centrale controller (CS) is uitgevoerd om elektrische overbelasting in ten minste een systeemcomponent te detecteren of daarop te reageren, en/of om een storing van ten minste een systeemcomponent te detecteren.9. The hybrid propulsion system according to any one of the preceding claims, wherein the central controller (CS) is designed to detect or respond to electrical overload in at least one system component, and/or to detect a malfunction of at least one system component.

10. Het hybride voortstuwingssysteem volgens een der voorgaande conclusies, waarbij de centrale controller (CS) communicatief is verbonden aan de motorcontroller, bijvoorbeeld om het motorsnelheid- instelpuntsignaal te ontvangen van de motorcontroller of voor het verzenden van het motorsnelheid-instelpuntsignaal naar de motorcontroller.The hybrid propulsion system according to any one of the preceding claims, wherein the central controller (CS) is communicatively connected to the engine controller, for example to receive the engine speed setpoint signal from the engine controller or to transmit the engine speed setpoint signal to the engine controller.

11. Het hybride voortstuwingssysteem volgens een der voorgaande conclusies, waarbij de centrale controller (CS) communicatief is verbonden aan de motorcontroller om een motorsnelheid-instelpuntsignaal te ontvangen van de motorcontroller.The hybrid propulsion system of any preceding claim, wherein the central controller (CS) is communicatively connected to the engine controller to receive an engine speed setpoint signal from the engine controller.

12. Werkwijze voor het besturen van een hybride voortstuwingssysteem voor een vaartuig, waarbij het hybride voortstuwingssysteem ten minste een hoofdvoortstuwingsmotor (13) en ten minste een elektrische motorgenerator (12A, 12B) heeft, waarbij uitgangsassen van de motor (13) en de ten minste ene motorgenerator (12A, 12B) direct zijn verbonden, bij voorkeur op elkaar zijn uitgelijnd en/of met elkaar zijn geïntegreerd, de werkwijze omvattende: -voorzien van een elektrisch motorgeneratorsnelheid-instelpuntsignaal aan ten minste een specifieke elektrische motorgeneratorcontroller voor autonoom besturen van de snelheid van de uitgangsas van ten minste een elektrische motorgenerator (12A, 12B), waarbij een belastingbalanceringsperiode wordt voorzien gedurende welke periode het verzonden elektrische motorgeneratorsnelheid-instelpuntsignaal in hoofdzaak of nagenoeg dezelfde snelheid aangeeft als een snelheid aangegeven door het motorsnelheid-instelpuntsignaal.12. Method of controlling a hybrid propulsion system for a vessel, the hybrid propulsion system having at least one main propulsion engine (13) and at least one electric motor generator (12A, 12B), wherein output shafts of the engine (13) and the at least one motor generator (12A, 12B) are directly connected, preferably aligned and/or integrated with each other, the method comprising: -providing an electric motor generator speed setpoint signal to at least one dedicated electric motor generator controller for autonomously controlling the speed of the output shaft of at least one electric motor generator (12A, 12B), providing a load balancing period during which the transmitted electric motor generator speed setpoint signal indicates substantially or substantially the same speed as a speed indicated by the engine speed setpoint signal.

13. Werkwijze volgens conclusie 12, omvattende verzending van het elektrische motorgeneratorsnelheid-instelpuntsignaal door een centrale controller (CS).The method of claim 12, including transmitting the electric motor generator speed setpoint signal by a central controller (CS).

14. Werkwijze volgens conclusie 13, waarbij de centrale controller het motorsnelheid-instelpuntsignaal ontvangt van een motorcontroller.The method of claim 13, wherein the central controller receives the engine speed setpoint signal from an engine controller.

15. Werkwijze volgens een der conclusies 12-14, omvattende voorzien van een initialisatieperiode gedurende welke de snelheid van de uitgangsas (11) van de motor (13) wordt vergeleken met een respectief initieel motorsnelheid-instelpunt, waarbij de belastingbalanceringsperiode slechts wordt gestart wanneer wordt bepaald dat de snelheid van de wtgangsas (11) van de motor (13) het initiële motorsnelheid-instelpunt heeft bereikt of overschreden, instelpunt, of omgekeerd wanneer het nieuwe instelpunt van de motor lager is dan het initiële snelheid-instelpunt.A method according to any one of claims 12 to 14, including providing an initialization period during which the speed of the output shaft (11) of the motor (13) is compared to a respective initial motor speed setpoint, the load balancing period being initiated only when determines that the speed of the motor's input shaft (11) (13) has reached or exceeded the initial motor speed setpoint, setpoint, or vice versa when the new motor setpoint is lower than the initial speed setpoint.

16. Werkwijze volgens een der conclusies 12-15, waarbij de belastingbalanceringsperiode wordt gestopt of onderbroken in het geval een elektrische overbelasting en/of storing in ten minste een systeemcomponent wordt gedetecteerd.Method according to any one of claims 12-15, wherein the load balancing period is stopped or interrupted in case an electrical overload and/or malfunction in at least one system component is detected.

17. Centrale controller programmaproduct, bijvoorbeeld een computerprogramma, omvattende instructies die, wanneer het programma door een centrale controller wordt uitgevoerd, de centrale controller (CS) de werkwijze volgens een der conclusies 12-16 laten uitvoeren.17. Central controller program product, for example a computer program, comprising instructions that, when the program is executed by a central controller, cause the central controller (CS) to execute the method according to any of the claims 12-16.