Method and apparatus for operating a power pack

Abstract

To provide a method and apparatus for dual operation of power packs that is cost-effective, safe, lightweight, and allows for the avoidance of bulky interference filters. In one embodiment, a first electric motor (101) is driven by a battery (104), and a second electric motor (102) is driven by a grid (106). The first and second electric motors (101, 102) are mechanically coupled (108) to each other such that when the second electric motor (102) is driven, it simultaneously operates (109) a power generator (103) and the first electric motor (101), and the first electric motor (101) functions as a high-power battery charger, recharging the battery (104) when the second electric motor (102) operates (109) the power generator (103). When the second electric motor is not in use, the first electric motor (101) is driven (104, 105), and the first electric motor (101) operates (108) the power generator (103).

Description

[Technical Field]

[0001] The present invention relates to a method and apparatus for operating a power pack, such as a hydraulic power pack. In particular, the present invention relates to a method and apparatus for operating a power pack by at least two different types of operation, for example for different environmental conditions. [Background technology]

[0002] Power generators, such as hydraulic pumps or compressors, are typically driven by electric motors. Depending on the environment, electric motors may be grid-driven or combustion-engine driven, although battery-powered electric motors are also used to drive generators. Battery-powered electric motors are commonly used in situations where combustion engines cannot be used, such as mining or tunneling sites or other sites with essentially closed environments, or when there is no external power distribution grid in use. Battery-powered electric motors are also often used in non-road mobile machinery that cannot be connected to a grid during operation. This may be due, for example, to the absence of a grid or the mobility of the machine.

[0003] Patent document 1 relates to a self-recharging generator system including a battery unit configured to communicate with an external system and supply the self-recharging generator system, an automatic switching unit configured to switch between a mains power supply and the self-recharging generator system, at least one electric motor configured to receive power from the battery unit, and at least one generator configured to produce power to be supplied to the external system when a failure occurs in the mains power supply, wherein the power produced by the at least one generator is further supplied to the automatic switching unit for continuous recharging of the self-recharging generator system.

[0004] However, there are several disadvantages associated with the known prior art, especially in low current conditions in closed environments, such as mining and tunneling sites. Grid-fed electric motors used to drive generators typically induce load peaks, especially during start-up (the current is much higher during start-up than during normal operation at nominal speed), which must be taken care of by using large or oversized grid feeders and power lines as well as appropriate interference filters. This is necessarily very difficult and expensive, especially in difficult environments such as temporary mining or tunneling works. In addition, the use of battery-powered motors can induce interference to other parts of the power grid system as well as sparks, which are at least noisy and can be very dangerous in closed environments. Therefore, prior art systems use various types of filters, which make the systems larger, more fragile, and more expensive. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent No. 8,994,215 Summary of the Invention [Means for solving the problem]

[0006] It is an object of the present invention to reduce or eliminate problems associated with the known prior art. In particular, it is an object of the present invention to provide a method and apparatus for dual operation of power packs that is cost-effective, safe, lightweight, and interference-free in operation, and that allows large interference filters to be avoided. Additionally, it is an object of the present invention to minimize the need for large and even oversized grid feeds, components, or power lines, and also allow the grid load to remain essentially constant.

[0007] The object of the invention may be achieved by means of the features of the independent claims.

[0008] The present invention relates to a dual action power pack as claimed in claim 1. Additionally, the present invention relates to a method for a dual action power pack as claimed in claim 11.

[0009] According to one embodiment of the present invention, a dual-actuation power pack includes an energy storage unit, first and second electric motors, and a power generator, the power generator being operated by the first and second electric motors. Advantageously, the first electric motor is driven by the energy storage unit, and the second electric motor is driven externally, e.g., by a power grid, a mains current, or the power of a combustion engine. Additionally, the first and second electric motors are mechanically coupled to each other such that, when the second electric motor is driven, it operates the first electric motor in addition to the power generator, with the first electric motor functioning as a charger or loader, recharging or recharging the energy storage unit. However, when the first electric motor is driven, it operates the power generator.

[0010] When the first and second electric motors are mechanically coupled to each other, pure galvanic isolation can be achieved, resulting in interference-free operation without the need for large interference filters, which is a clear advantage of the present invention. Additionally, monitoring of the entire system can be easily implemented, and in the event of a malfunction or other harmful or undesirable effect, for example, the electrically isolated electric motor can be easily turned off or isolated from the grid or other parts of the system, thereby minimizing or even eliminating interference. Furthermore, when the second electric motor is used as an actuator for a power generator, the first electric motor can be used as a generator, for example, a generator for charging the energy storage battery. However, when used as a charger or loader, particularly as the charger, the power of the first motor is very high because it is designed as a power source for operating the power generator. Furthermore, it should be noted that the first motor is further electrically isolated from the external power grid and the second electric motor, and therefore any interference that may be induced by the first electric motor or during charging can be effectively avoided without the need for electrical filters or devices.

[0011] The energy store is advantageously a battery, but can also be implemented in other ways, such as a rechargeable energy or electrical store, a fuel cell, a supercapacitor or a flywheel or a combination thereof. Naturally, depending on the type of energy store, the first electric motor as charger or loader must be adjusted in a corresponding manner, such as charging a supercapacitor or filling a flywheel with kinetic or other mechanical energy.

[0012] Additionally, according to one embodiment of the present invention, the first electric motor can also be used to soft-start the second electric motor in situations where the second electric motor is used as the primary power source to operate the power generator. Soft-starting can be accomplished, for example, by spinning the first electric motor at or near synchronous grid speed before connecting the second electric motor to the grid. Additionally, according to one embodiment, potential power peaks can be reduced by using the first electric motor. Also, additional power needed for the power generator, for example, temporarily for some reason, can be provided by using the first electric motor as a power source supplemental to the primary use of the second electric motor.

[0013] By means of the above-described embodiments, load peaks, especially at start-up, but also due to unexpected load peaks on the generator, can be minimized or even eliminated, which is a very important and advantageous feature, i.e., during start-up, the required current can be several times higher compared to normal operation at nominal speed. Thus, the grid feed and power lines can essentially be designed for nominal speed and normal operating conditions, without the need for oversizing.

[0014] The present invention offers advantages over known prior art, as already disclosed above in connection with embodiments of the present invention. Additionally, embodiments of the present invention allow for the production of compact-sized systems in a cost-effective manner, since galvanic isolation eliminates the need for expensive and bulky components such as interference filters. The present invention also allows for the use of different main voltages and a simple way to design a second electric motor for a different main voltage. Furthermore, and particularly, the present invention provides for a large load capacity of the energy storage, such as using the first electric motor as a high-power battery charger. The present invention also provides true dual operation, i.e., the same hydraulic components can still be used by both the first and second electric motors.

[0015] The exemplary embodiments presented herein should not be construed as imposing limitations on the applicability of the appended claims. The verb "comprise" is used herein as an open limitation that does not exclude the presence of unrecited features. Features recited in dependent claims may be freely combined with each other unless expressly stated otherwise.

[0016] The novel features which are believed to be characteristic of the invention are set forth with particularity in the appended claims. However, the invention itself, both as to its structure and its method of operation, together with further objects and advantages thereof, will best be understood from the following description of specific illustrative embodiments when read in connection with the accompanying drawings.

[0017] The invention will now be described in more detail with reference to exemplary embodiments according to the accompanying drawings. [Brief explanation of the drawings]

[0018] [Figure 1] 1 illustrates an exemplary apparatus principle for a dual actuation power pack in accordance with an advantageous embodiment of the present invention. [Figure 2] 1 illustrates an exemplary apparatus principle for a dual actuation power pack in accordance with an advantageous embodiment of the present invention. [Figure 3] 1 illustrates an exemplary apparatus principle for a dual actuation power pack in accordance with an advantageous embodiment of the present invention. [Figure 4] 1 illustrates an exemplary mechanical linkage principle for a dual acting power pack in accordance with an advantageous embodiment of the present invention. [Figure 5] 1 illustrates an exemplary mechanical linkage principle for a dual acting power pack in accordance with an advantageous embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] 1-3 illustrate the principles of an exemplary apparatus for a dual actuation power pack according to an advantageous embodiment of the present invention, where the dual actuation power pack 100, 200, 300 includes a battery 104 as an energy storage unit, a first electric motor 101, and a second electric motor 102. The first electric motor 101 is configured to be driven 111 by battery energy, and the second electric motor 102 is configured to be driven 112 by a grid 106 or a combustion engine. Additionally, the dual actuation power pack includes a power generator 103 configured to be operated by the first and second electric motors 101, 102.

[0020] The first and second electric motors 101, 102 are mechanically coupled to one another 108 (see also Figures 4 and 5) such that when the second electric motor 102 is driven, it activates the power generator 103 109, but also advantageously simultaneously activates the first electric motor 101. The first electric motor 101 may be implemented such that when activated, and thus in fact rotated, it functions as a high-power battery charger and charges the battery 104. In situations where there is no possibility to use external energy, such as a grid or combustion engine connection 106, the first electric motor 101 is used to activate the power generator 103 108. The first electric motor 101 is driven by the battery energy 104.

[0021] The mechanical linkage provides galvanic isolation 110 between the motors, thereby galvanically isolating the first electric motor and internal electrical equipment of the dual actuation power packs 100, 200, 300 from the external grid or electrical equipment. Thus, operation of the dual actuation power pack is virtually interference-free, eliminating the need for interference filters.

[0022] As can be seen, the mechanical linkages 108, 109 and the arrangement of the motors and power generators can be implemented in a number of ways. For example, the second electric motor 102 can be coupled at its first end 109 to the power generator 103 and at its second end 108 to the first electric motor 101, as shown in Figure 1, or the first electric motor 101 can be located "between" the second electric motor 102 and the power generator, as in Figures 2 and 3.

[0023] The power generator 103 may act as or include a converter for converting energy received from the first and second electric motors 101, 102 into movement of a medium, such as movement of a fluid like air or oil. Most advantageously, the power generator 103 is or includes a pump, a hydraulic pump or a hydraulic power pack, or a compressor, an air compressor or a pneumatic power pack.

[0024] According to an advantageous embodiment, the first electric motor 101 may also be used to soft-start the second electric motor 102 in situations where the second electric motor 102 is used to operate the power generator 103. This may be very advantageous, for example, when the grid design is very weak and the load peaks caused by starting the second electric motor on the grid during startup are high; soft starting may essentially eliminate the load peaks on the grid. Soft starting may be implemented, for example, by spinning the first electric motor 101 to or near synchronous grid 106 speed before connecting the second electric motor 102 to the grid 106, thereby minimizing the payload and requirements on grid components.

[0025] Furthermore, according to an advantageous embodiment, the first electric motor 101, in addition to suppressing power peaks, may also be used 108, 109 to provide additional power to the power generator (or second electric motor) (providing a power boost function) when the power draw from the power generator 103 exceeds the capacity or a set threshold of the second electric motor 102 during primary use of said second electric motor 102. In this way, not only can the grid load be kept essentially constant, but the need for oversizing of systems or components due to possible load peaks can also be minimized or eliminated.

[0026] The second electric motor 102 is typically an induction motor and is driven by a mains current 106 (grid connected). However, it should be noted that mains current or grid connected are examples only, and any type of external generator 106 or any type of external power source may be used to power the second electric motor 102, such as a combustion engine or a fuel cell. Depending on the type of external energy source connection used, parameters of the second electric motor may be adjusted, for example, the operating voltage may be adjusted to suit the second electric motor.

[0027] Additionally, the dual actuation power pack may also include a control system 107 for controlling the operation of the motors and power generators. For example, the control system 107 may regulate the current draw and load of the second electric motor 102, as well as the charge or load of the energy storage unit 104, such as the current of the battery 104. Additionally, the control system 107 may also control the load of the first motor 101, for example, by controlling the first motor 101 using the motor drive 105, as well as control soft start and provide power boost functionality.

[0028] The power and other parameters of the first and second electric motors 101, 102 may of course vary, but may for example be in the range of 20-90 kW, more preferably in the range of 30-75 kW, and most preferably about 50 kW. Naturally, the power of the first and second electric motors 101, 102 may differ from one another and may vary according to requirements and demands.

[0029] 4-5 illustrate the principles of exemplary mechanical connections 400, 500 for a dual actuation power pack in accordance with an advantageous embodiment of the present invention, with FIG. 4 showing a direct mechanical link from second electric motor 102 to power generator 103 via first electric motor 101. In this embodiment, mechanical connections 108, 109 may be implemented by a direct mechanical link so that the first electric motor is always running when the second electric motor is in use. Note that a clutch or free clutch or other connection and disconnection device may be used to mechanically disconnect the second electric motor so that the first electric motor does not rotate the second electric motor when the first electric motor is in use. Additionally, mechanical connections 108, 109 may be implemented by, for example, a shaft, clutch, or chain or belt, although other types of connection known to those skilled in the art may also be used.

[0030] 5 shows another example in which a geared mechanical linkage or gearbox 113 is used. Gears may be used to adjust the output speed ranges of the first and / or second electric motors 101, 102 relative to one another, for example, for different situations and / or optimal speed ranges of the power generator 103. For example, a hydraulic pump may have an optimal essentially constant RPM range to which the output speed ranges of the first and / or second electric motors 101, 102 should be adjusted.

[0031] The gears may have a fixed ratio, but gearboxes with different ratios may also be used, for example for soft start or other functions. Additionally, it should be noted that the control system 107 may also control the operation of the gearbox to achieve different speed ranges, for example for different loads or functions.

[0032] The present invention has been described above with reference to the aforementioned embodiments, and some advantages of the present invention have been shown. It is clear that the present invention is not limited to these embodiments, but rather includes all possible embodiments within the spirit and scope of the inventive concept and the following claims. For example, the battery described in connection with the figures is only one example of an energy storage unit, and the energy storage unit may, of course, be another type of energy storage unit, as disclosed elsewhere herein. The same applies to the type of external energy source used to provide energy to the second electric motor, and the external energy source may also be another type of energy source, as disclosed elsewhere herein. Furthermore, the arrangement of components shown in the figures is only an example.

[0033] The features recited in the dependent claims may be freely combined with one another unless expressly stated otherwise.

Claims

1. A dual acting power pack (100, 200, 300) comprising: an energy store (104), - first and second electric motors (101), (102); a power generator (103) operated by said first and / or second electric motor (101, 102); Including, the first electric motor (101) driven by the energy storage unit (104) and the second electric motor (102) are mechanically coupled (108) to each other and configured such that when the second electric motor (102) is driven, the second electric motor operates (109) the power generator (103), and when the first electric motor (101) is driven (104, 105), the first electric motor (101) operates (108, 109) the power generator (103); the first electric motor (101) and the second electric motor (102), which is a grid-driven (106) electric motor, are mechanically coupled (108) to each other and are further configured to operate (109) the first electric motor (101) when the second electric motor (102) is driven, wherein the first electric motor (101) functions as a charger or loader and is configured to recharge or refill the energy store (104); A dual operating power pack (100, 200, 300).

2. 2. The dual action power pack of claim 1, wherein the first and second electric motors (101, 102) and the power generator (103) are provided such that the second electric motor (102) is mechanically coupled at its first end (109) to the power generator (103) and at its second end (108) to the first electric motor (101).

3. 3. The dual action power pack of claim 1, wherein the mechanical linkage (108, 109) is implemented by a shaft, a clutch, a chain, or a belt, or the mechanical linkage includes a gearbox for adjusting the output speed range of the first and / or second electric motor to match the speed range of the power generator.

4. 4. The dual action power pack of claim 1, wherein the power generator (103) includes a converter for converting energy received from the first and second electric motors (101, 102) into movement of a medium.

5. The dual acting power pack of claim 4, wherein the power generator (103) comprises one of a pump, a hydraulic pump, a hydraulic power pack, a compressor, an air compressor, and a pneumatic power pack.

6. A dual action power pack according to any one of claims 1 to 5, wherein the second electric motor (102) is an induction motor and is configured to be driven by a main current (106).

7. 7. The dual action power pack of claim 1, wherein the first electric motor is configured to be used to soft start the second electric motor by spinning the first electric motor at or near synchronous grid speed before connecting the second electric motor to the grid.

8. 8. A dual action power pack according to any one of claims 1 to 7, wherein the first electric motor (101) is configured to be used (108, 109) to suppress power peaks and / or to provide additional power to the power generator (103) during primary use of the second electric motor (102) and when power draw from the power generator exceeds the capacity of the second motor (102).

9. 9. The dual action power pack of claim 1, further comprising a control system (107) configured to control the first motor (101) using a motor drive (105) to moderate the current draw and loading of the second electric motor (102) and the charging or loading of the energy storage (104), and / or the loading of the first motor (101).

10. The dual actuation power pack of any one of claims 1 to 9, wherein the energy storage (104) comprises an electrical energy storage, a rechargeable electrical storage, a battery, a fuel cell, a supercapacitor and / or a flywheel.

11. A method (100) for dual operation of a power pack, comprising at least: - mechanically coupling (108, 109) the first and second electric motors of said power pack to each other; - activating (108, 109) the power generator (103) of the power pack by the first electric motor (101) when the first electric motor (101) is driven by the energy store (104) of the power pack, and by the second electric motor (102) when the second electric motor (102) is driven (106), the first and second electric motors (101, 102) are mechanically coupled (108, 109) to each other, and when the second electric motor (102) is driven by a grid, the second electric motor (102) further operates (109) the first electric motor (101), which then recharges or recharges the energy storage (104); A method characterized by:

12. 12. The method of claim 11, further comprising soft starting the electric second motor (102) by spinning the first electric motor (101) at or near synchronous grid (106) speed before connecting the second electric motor (102) to the grid (106).

13. The method according to any one of claims 11 to 12, wherein the output speed range of the first and / or second electric motor is adjusted to the speed range of the power generator by the mechanical linkage (108, 109).

14. 13. The method according to any one of claims 11 to 12, wherein power peaks are reduced by using the first electric motor (101) and / or additional power is provided to the power generator by using the first electric motor during primary use of the second electric motor (102).

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