DISTRIBUTED PUMP ARCHITECTURE FOR MULTIFUNCTIONAL MACHINES

At least some embodiments of the present disclosure are directed to distributed pump architectures used in control systems for multifunctional machines. In some cases, a control system for a multifunctional machine includes three or more control circuits. At least two of the control circuits each has a hydraulic fluid pump and each of the pumps is controlled by a different control circuit. At least two of the hydraulic fluid pump have different flow rates.

TECHNICAL FIELD

This disclosure generally relates to distributed pumps architectures for multifunctional machines.

BACKGROUND

Machines are powered by various power systems, for example, internal combustion engines, electric power systems and hybrid power systems. In internal combustion engines, one or more fuel pumps deliver fuel to a common rail. Fuel is delivered by fuel injectors from the rail to cylinders of the engine for combustion to power operation of the system driven by the engine. Electric power systems typically use electric storage device(s) (e.g., battery) to power one or more electric motors/generators to provide other functions. The electric power systems may include an electric motor driven pump. Hybrid power system may include a hybrid control system, a battery, a motor/generator, and an engine (e.g., an internal combustion engine). The hybrid control system may control the engine and the motor/generator to provide power to a load (e.g., to move the machine or to provide electric power to a residence). Additionally, in some instances, the engine and motor/generator may also provide power to recharge the battery.

Some machines are multifunctional. For example, a construction machine may have the functions controlling and moving a shovel, a crane, a swing, a bucket, and/or a blade, besides the travel function. As another example, a multifunctional machine is an excavator.

SUMMARY

It is desirable to increase energy efficiency in power systems. For a multifunctional machine, a single pump or a pair of pumps having a same displacement is used and managed through a main valve to supply power to multiple functions (e.g., travel, boom, swing, etc.). This often results in energy losses (e.g., 40% energy loss). At least some embodiments of the present disclosure are directed to an architecture to decouple hydraulic systems to improve energy efficiency. At least some embodiments of the present disclosure are directed to an adaptable architecture of distributed pumps for a power system to improve energy efficiency. In some cases, a distributed pump architecture may be suitable for any one of a fuel power system, an electric power system and a hybrid power system.

One embodiment of the present disclosure is directed to a control system for a fuel power system. The control system includes a first control circuit, a second control circuit, and a third control circuit. The first control circuit includes a first pump and is configured to control a first hydraulic fluid flow from the first pump. The second control circuit includes a second pump and is configured to control a second hydraulic fluid flow from the second pump. The third control circuit includes a third pump and a hydraulic motor. The third control circuit is configured to control a third hydraulic fluid flow from the third pump and the hydraulic motor is configured to control a rotation movement. A first flow rate of the first hydraulic fluid flow is different from a second flow rate of the second hydraulic fluid flow. The first flow rate of the first hydraulic fluid flow is different from a third flow rate of the third hydraulic fluid flow. The second flow rate of the second hydraulic fluid flow is different from the third flow rate of the third hydraulic fluid flow.

One embodiment of the present disclosure is directed to a control system for an electric power system. The control system includes a first control circuit, a second control circuit, and a third control circuit. The first control circuit includes a first electric motor and a first pump. The first control circuit is configured to control a first hydraulic fluid flow from the first pump. The second control circuit includes a second electric motor and a second pump. The second control circuit is configured to control a second hydraulic fluid flow from the second pump. The third control circuit includes an electric motor/generator and is configured to control an electric power generated from the electric motor/generator. A first flow rate of the first hydraulic fluid flow is different from a second flow rate of the second hydraulic fluid flow.

One embodiment of the present disclosure is directed to a control system for a hybrid power system. The control system includes a first control circuit, a second control circuit, and a third control circuit. The first control circuit includes a first pump and is configured to control a first hydraulic fluid flow from the first pump. The second control circuit includes a second pump and is configured to control a second hydraulic fluid flow from the second pump. The third control circuit includes an electric motor/generator and is configured to control an electric power generated from the electric motor/generator. A first flow rate of the first hydraulic fluid flow is different from a second flow rate of the second hydraulic fluid flow. The first pump is a variable displacement pump. The second pump is also a variable displacement pump.

DETAILED DESCRIPTION

As used herein, when an element, component, device or layer is described as being “on” “connected to,” “coupled to” or “in contact with” another element, component, device or layer, it can be directly on, directly connected to, directly coupled with, in direct contact with, or intervening elements, components, devices or layers may be on, connected, coupled or in contact with the particular element, component or layer, for example. When an element, component, device or layer for example is referred to as being “directly on,” “directly connected to,” “directly coupled to,” or “directly in contact with” another element, component, device or layer, there are no intervening elements, components, devices or layers for example. As used herein, “powered” means a device receiving operational power.

Referring toFIG.1, a simplified schematic of a multifunctional machine100is shown. The multifunctional machine100is powered by a power system110. The power system110includes one or more pumps114, one or more motor/generators116, and one or more valves118. In some embodiments, the power system110includes an engine112, such as an internal combustion engine. In some embodiments, the power system110does not include an internal combustion engine. In some cases, the power system110includes one or more electric storage devices (e.g., a battery; not shown). In some embodiments, the multifunctional machine100includes multiple functional devices (e.g.,120,125,130,135, and140). In the example illustrated, the multifunctional machine100is an excavator including a boom component120, an arm component125, a bucket component130, a travel component135, and a swing component140. In some cases, the boom component120has one or more boom cylinders122. In some cases, the arm component125has an arm cylinder127. In some cases, the bucket component130has one or more bucket cylinders132. In one example, the multifunctional machine100includes a cabin145.

In some embodiments, the power system110is associated with a control system150. In some cases, the control system150includes one or more control circuits155. In some cases, the one or more control circuits155comprises the one or more pump controllers112. In one embodiment, the control circuit155is configured to control the hydraulic fluid flow of a pump114. For example, the control system150may include a boom control circuit155controlling a hydraulic fluid flow from a pump114to the boom cylinder122. In some cases, at least one of the one or more pumps114is a variable displacement pump. As used herein, a variable displacement pump refers to a pump configured to generate a variable fluid flow rate by changing pump displacement (e.g., swash plat angle), where the flow rate can be controlled by the control circuit155. Pump displacement refers to the volume of fluid transferred from a pump's inlet to its outlet in one revolution or cycle. In some cases, the flow rate of a pump is controlled to match with a load demand of a functional device. In some embodiments, the power system110propels the multifunctional machine100. In some cases, the power system110provides power to the one or more motor/generators116. In some cases, the one or more motor/generators116includes one or more hydraulic motors. In some cases, the one or more motor/generators116includes one or more electric motors. In some cases, the one or more motor/generators116includes one or more electric motor/generators. In some embodiments, a hydraulic motor refers to a mechanical actuator that converts hydraulic fluid pressure and flow into torque and angular displacements. As used herein, an electric motor refers to a motor powered by electricity and controlling movements, for example, linear movements, rotation movements, and the like. In some cases, an electric motor/generator referred to a combination of an electric motor and a generator capable of generating electricity.

In some embodiments, a motor/generator116, together with a pump in some cases, provides power to one or more functional devices (120,125,130,135, or140). In some cases, a motor/generator116is coupled to a pump114and controlled by a control circuit155of the control system150. The control circuit155can control the output of the motor/generator116and directly or indirectly controls a fluid flow rate of the pump114, by a control signal, for example. In certain implementations, the control circuit115receives a feedback signal from the pump114and/or the motor/generator116. In some cases, the control circuit115adjusts the control signal based on the feedback signal. In some cases, the functions of the control circuits155and the control system150may be performed by hardware and/or as computer instructions on a non-transitory computer readable storage medium.

In some embodiments, the control system150and the one or more control circuits155are configured to determine a flow rate to meet a load demand of a functional device and control a pump114and/or a motor/generator116to generate an output energy matching the demand(s) by the function. In some embodiments, a load demand of a functional device is provided as an input or selected by an operator. In one embodiment, the load demand is provided as or transformed into pressure. Flow rate is provided, for example, by the product of speed of pump and pump displacement. In some cases, pump displacement is controlled by an operator and/or the hydraulic system.

Referring toFIG.2, a simplified schematic of an example control system200for a fuel power system (e.g., an internal combustion engine) is shown. As illustrated, the control system200includes one example of a distributed pump architecture. The control system200includes a first control circuit210, a second control circuit220, and a third control circuit230. While the example illustrated inFIG.2includes three control circuits, the control system200may have more than three control circuits. The first control circuit210includes a first pump212and is configured to control a first hydraulic fluid flow213from the first pump212. The second control circuit220includes a second pump222and is configured to control a second hydraulic fluid flow223from the second pump222. The third control circuit230includes a third pump232and a hydraulic motor234. The third control circuit230is configured to control a third hydraulic fluid flow233from the third pump232. The hydraulic motor234is configured to control a linear movement and/or a rotation movement.

The first pump212, the second pump222, and/or the third pump232are coupled to an engine205. In some cases, the engine205is an internal combustion engine. In some cases, the engine205is a diesel engine. In some cases, at least one of the first pump212, the second pump222, and the third pump232is a variable displacement pump. In some cases, the first pump212is a variable displacement pump. In some cases, the second pump222is a variable displacement pump. In some cases, the third pump232is a variable displacement pump.

In some embodiments, the first control circuit210is configured to control the fluid flow and/or power supplies provided to a first functional device215. In some embodiments, the second control circuit220is configured to control the fluid flow and/or power supplies provided to a second functional device225. In the example illustrated, the second functional device225includes a plurality of functional devices225. In some embodiments, the third control circuit230is configured to control the fluid flow, power supplies provided to a third functional device235. In some cases, each of the first functional device215, the second functional device225, and the third functional device235may include a plurality of functional devices having a same load demand or various load demands.

In some embodiments, the first hydraulic fluid flow213has a flow rate different from the flow rate of the second hydraulic fluid flow223. In some embodiments, the flow rate of the first hydraulic fluid flow213is different from the flow rate of the third hydraulic fluid flow233. In some embodiments, the flow rate of the second hydraulic fluid flow223is different from the flow rate of the third hydraulic fluid flow233. In some cases, the flow rate of the first hydraulic fluid flow213is higher than the flow rate of the second hydraulic fluid flow223. In some cases, the flow rate of the first hydraulic fluid flow213is higher than the flow rate of the third hydraulic fluid flow233.

In some designs, the first functional device215, the second functional device225, and the third functional device235each has a different load demand. In some cases, the first functional device215has the highest load demand among the functional devices supported by the control system200. In some cases, the third functional device235has the lowest load demand among the functional devices supported by the control system200. In some implementations, the first functional device215has a higher load demand than the load demand for the second functional device225and/or the third functional device235.

In some implementations, the first functional device215has a higher hydraulic flow rate requirement than the hydraulic flow rate requirement for the second functional device225and/or the third functional device235. The first control circuit210is configured to control the power provided to the first functional device215. In some cases, the first control circuit210is configured to control the first hydraulic fluid flow213from the first pump212into one or more cylinders associated with the functional device215via a valve216. In some cases, the first control circuit210is configured to control a generation of higher power supply to meet the load demand of the first functional device215than the power supply controlled by the second control circuit220. In some cases, the first control circuit210is configured to control a generation of higher power supply to meet the load demand of the first functional device315than the power supply controlled by the third control circuit230. In one embodiment, the first functional device215is a boom of an excavator (e.g.,120ofFIG.1). In one embodiment, the first control circuit210is configured to feed the first hydraulic fluid flow213from the first pump212into a boom cylinder of an excavator (e.g.,122ofFIG.1).

In some embodiments, the flow rate of the third hydraulic fluid flow233is lower than the flow rate of the first hydraulic fluid flow213. In some embodiments, the flow rate of the third hydraulic fluid flow233is lower than the flow rate of the second hydraulic fluid flow223. In some implementations, the third functional device235has a lower load demand than the load demand for the first functional device215and/or the second functional device225. The third control circuit230is configured to control the power provided to the third functional device235. In some cases, the third control circuit230is configured to control a generation of lower power supply to meet the load demand of the third functional device235than the power supply controlled by the first control circuit210. In some cases, the third control circuit230is configured to control a generation of lower power supply to meet the load demand of the third functional device235than the power supply controlled by the second control circuit220. In some cases, the third functional device235is a swing of an excavator (e.g.,140ofFIG.1).

In some embodiments, the second control circuit220is configured to control the power provided to a plurality of functional devices225. In some cases, the second control circuit220is configured to control the second hydraulic fluid flow223from the second pump222into a plurality of cylinders (not shown). In some cases, the second control circuit220is configured to control the second hydraulic fluid flow223from the second pump222into a plurality of cylinders via a valve226. In some cases, the valve226may receive a control signal from the second control circuit210; and in response, the valve226may increase, decrease, change, or shut off the second hydraulic flow223going into a specific functional device225. In one embodiment, the functional devices225include a functional device227that has rotational movements. In some cases, the functional device227includes a hydraulic motor228and a device229. In one example, the device229is a travel component of an excavator (e.g.,135ofFIG.1). In some cases, the functional devices225includes an arm component of an excavator (e.g.,125ofFIG.1) and a bucket component of an excavator (e.g.,130ofFIG.1).

Referring toFIG.3, a simplified schematic of an example control system300for an electric power system (e.g., a pure electric power system, a plug-in electric power system, not a hybrid power system) is shown. The control system300illustrates one example of a distributed pump architecture. The control system300includes a first control circuit310, a second control circuit320, and a third control circuit330. While the example illustrated inFIG.3includes three control circuits, the control system300may have more than three control circuits. The first control circuit310includes a first electric motor311and a first pump312. The first control circuit310is configured to control the first electric motor311and a first hydraulic fluid flow313from the first pump312. The second control circuit320includes a second electric motor321and a second pump322. The second control circuit320is configured to control the second electric motor321and a second hydraulic fluid flow323from the second pump322. The third control circuit330includes an electric motor/generator332. In some cases, the third control circuit330is configured to control an electric power generated from the electric motor/generator332. In some cases, the flow rate of the first hydraulic fluid flow313is different from the flow rate of the second hydraulic fluid flow323. In some cases, the first electric motor311and/or the second electric motor321do not have electric generation functions.

In some embodiments, the control system300is electrically coupled to an electric storage device305(e.g., a battery). In some cases, the electric storage device305includes an energy management unit (not shown), an energy storage (e.g., plurality of battery/fuel cell packs) (not shown), and a thermal management system (not shown). In certain applications, the battery packs include a plurality of lithium-ion battery packs, although in other applications various other suitable energy storage technologies may be used. In some cases, the first electric motor311, the second electric motor321, and/or the electric motor/generator332are electrically coupled to the electric storage device305. In some embodiments, the electric storage device305is configured to provide electric power to the first electric motor311, the second electric motor321, and/or the electric motor/generator332. In some cases, the electric motor/generator332can supply electric power331to the electric storage device305, for example, to recharge the electric storage device305.

In some cases, at least one of the first pump312and the second pump322is a variable displacement pump. In some cases, the first pump312is a variable displacement pump. In some cases, the second pump322is a variable displacement pump. The first control circuit310is configured to control the fluid flow and/or power supplies provided to a first functional device315. The second control circuit320is configured to control the fluid flow and/or power supplies provided to a second functional device325. In the example illustrated, the second functional device325includes a plurality of functional devices325. In some embodiments, the third control circuit330is configured to control the power supplies provided to a third functional device335. In some cases, each of the first functional device315, the second functional device325, and the third functional device335may include a plurality of functional devices having a same load demand or various load demands.

In some designs, the first functional device315, the second functional device325, and the third functional device335each has a different load demand. In some cases, the first functional device315has the highest load demand among the functional devices supported by the control system300. In some cases, the third functional device335has the lowest load demand among the functional devices supported by the control system300.

In some implementations, the first functional device315has a higher load demand than the load demand for the second functional device325and/or the third functional device335. In some implementations, the first functional device315has a higher load demand than the load demand of the second functional device325. In some embodiments, the first hydraulic fluid flow313has a flow rate different from the flow rate of the second hydraulic fluid flow323. In some cases, the flow rate of the first hydraulic fluid flow313is higher than the flow rate of the second hydraulic fluid flow323. In some implementations, the first functional device315has a higher load demand than the load demand of the third functional device335. The first control circuit310is configured to control the power provided to the first functional device315. In some cases, the first control circuit310is configured to control the first hydraulic fluid flow313from the first pump312into one or more cylinders associated with the functional device315via a valve316. In some cases, the first control circuit310is configured to control a generation of higher power supply to meet the load demand of the first functional device315than the power supply controlled by the second control circuit320. In some cases, the first control circuit310is configured to control a generation of higher power supply to meet the load demand of the first functional device315than the power supply controlled by the third control circuit330. In one embodiment, the first functional device315is a boom of an excavator (e.g.,120ofFIG.1). In one embodiment, the first control circuit310is configured to feed the first hydraulic fluid flow313from the first pump312into a boom cylinder of an excavator (e.g.,132ofFIG.1).

In some implementations, the third functional device335has a lower load demand than the load demand of the first functional device315and/or the second functional device325. The third control circuit330is configured to control the power provided to the third functional device335. In some cases, the third control circuit330is configured to control a generation of lower power supply to meet the load demand of the third functional device335than the power supply controlled by the first control circuit310. In some cases, the third control circuit330is configured to control a generation of lower power supply to meet the load demand of the third functional device335than the power supply controlled by the second control circuit320. In some cases, extra electric power333supplied to the third functional device335can flow back to the electric motor/generator332. In some cases, the electric motor/generator332can generate extra electric power to be stored in the electric storage device305, for example, to recharge the electric storage device305. In some cases, the third functional device335is a swing of an excavator (e.g.,140ofFIG.1).

In some embodiments, the second control circuit320is configured to control the power provided to a plurality of functional devices325. The second control circuit320is configured to control the second hydraulic fluid flow323from the second pump322into a plurality of cylinders (not shown). In some cases, the second control circuit320is configured to control the second hydraulic fluid flow323from the second pump322into a plurality of cylinders via a valve326. In some cases, the valve326may receive a control signal from the second control circuit310; and in response, the valve may increase, decrease, change, or shut off the second hydraulic flow323going into a specific functional device325. In one embodiment, the functional devices325include a functional device327that has rotational movements. In some cases, the functional device327includes a hydraulic motor328and a device329. In one example, the device329is a travel component of an excavator (e.g.,135ofFIG.1). In some cases, the functional devices325includes an arm component of an excavator (e.g.,125ofFIG.1) and a bucket component of an excavator (e.g.,130ofFIG.1).

Referring toFIG.4, a simplified schematic of an example control system400for a hybrid power system is shown. As illustrated, the control system400includes one example of a distributed pump architecture. The control system400includes a first control circuit410, a second control circuit420, and a third control circuit430. While the example illustrated inFIG.4includes three control circuits, the control system400may have more than three control circuits. The first control circuit410includes a first pump412and is configured to control a first hydraulic fluid flow413from the first pump412. The second control circuit420includes a second pump422and is configured to control a second hydraulic fluid flow423from the second pump422. The third control circuit430includes an electric motor/generator432. In some cases, the third control circuit430is configured to control an electric power generated from the electric motor/generator432. In some cases, the flow rate of the first hydraulic fluid flow413is different from the flow rate of the second hydraulic fluid flow423.

In some embodiments, the control system400is coupled to an engine405. In some cases, the first pump412, the second pump422, and/or the electric motor/generator432are coupled to the engine405. In some cases, the engine405is an internal combustion engine. In some cases, the engine405is a diesel engine. In some embodiments, the control system400is electrically coupled to an electric storage device407(e.g., a battery). In some cases, the electric motor/generator432is electrically coupled to the electric storage device407. In some cases, the electric storage device407includes an energy management unit (not shown), an energy storage (e.g., plurality of battery/fuel cell packs) (not shown), and a thermal management system (not shown). In certain applications, the battery packs include a plurality of lithium-ion battery packs, although in other applications various other suitable energy storage technologies may be used. In some embodiments, the electric storage device407is configured to provide electric power to the electric motor/generator432. In some cases, the electric motor/generator432can supply electric power431to the electric storage device407, for example, to recharge the electric storage device407. In some cases, the engine405can supply power to the electric motor/generator432. Optionally, the third control circuit430includes a clutch409that is connected between the engine405and the electric motor/generator432. The clutch409can couple and decouple the engine405to the electric motor/generator432. The clutch409can control direction and source of power flow to the third control circuit430from engine405or energy storage407.

In some embodiments, the engine405is configured to provide power to the electrical motor/generator432, with the power generation controlled by the third control circuit430. In some cases, the first control circuit410is solely powered by the engine405. In some cases, the first control circuit410is not coupled to the electric storage device407and/or the electric motor/generator432. In some cases, the second control circuit420is solely powered by the engine405. In some cases, the second control circuit420is not coupled to the electric storage device407and/or the electric motor/generator432.

In some cases, at least one of the first pump412and the second pump422is a variable displacement pump. In some cases, the first pump412is a variable displacement pump. In some cases, the second pump422is a variable displacement pump. In some embodiments, the first control circuit410is configured to control the fluid flow and/or power supplies provided to a first functional device415. In some embodiments, the second control circuit420is configured to control the fluid flow, power supplies, and/or movements provided to a second functional device425. In the example illustrated, the second functional device425includes a plurality of functional devices425. In some embodiments, the third control circuit430is configured to control the power supplies provided to a third functional device435. In some cases, each of the first functional device415, the second functional device425, and the third functional device435may include a plurality of functional devices having a same load demand or various load demands.

In some designs, the first functional device415, the second functional device425, and the third functional device435each has a different load demand. In some cases, the first functional device415has the highest load demand among the functional devices supported by the control system400. In some cases, the third functional device435has the lowest load demand among the functional devices supported by the control system400.

In some embodiments, the first hydraulic fluid flow413has a flow rate different from the flow rate of the second hydraulic fluid flow423. In some cases, the flow rate of the first hydraulic fluid flow413is higher than the flow rate of the second hydraulic fluid flow423. In some implementations, the first functional device415has a higher load demand than the load demand of the second functional device425. In some implementations, the first functional device415has a higher load demand than the load demand of the third functional device435. The first control circuit410is configured to control the power provided to the first functional device415. In some cases, the first control circuit410is configured to control the first hydraulic fluid flow413from the first pump412into one or more cylinders associated with the functional device415via a valve416. In some cases, the first control circuit410is configured to control a generation of higher power supply to meet the load demand of the first functional device415than the power supply controlled by the second control circuit420. In some cases, the first control circuit410is configured to control a generation of higher power supply to meet the load demand the first functional device415than the power supply controlled by the third control circuit430. In one embodiment, the first functional device415is a boom of an excavator (e.g.,120ofFIG.1). In one embodiment, the first control circuit410is configured to feed the first hydraulic fluid flow413from the first pump412into a boom cylinder of an excavator (e.g.,132ofFIG.1).

In some implementations, the third functional device435has a lower load demand than the load demand for the first functional device415and/or the second functional device425. In one embodiment, the third control circuit430is configured to control the power provided to the third functional device435. In some cases, the third control circuit430is configured to control a generation of lower power supply to meet the load demand of the third functional device435than the power supply controlled by the first control circuit410. In some cases, the third control circuit430is configured to control a generation of lower power supply to meet the load demand of the third functional device435than the power supply controlled by the second control circuit420. In some cases, the extra electric power433supplied to the third functional device435can flow back to the electric motor/generator432. In some cases, the electric motor/generator432can generate extra electric power to be stored in the electric storage device305. In some cases, the third functional device435is a swing of an excavator (e.g.,140ofFIG.1).

In some embodiments, the second control circuit420is configured to control the power provided to a plurality of functional devices425. In some cases, the second control circuit420is configured to control the second hydraulic fluid flow423from the second pump422into a plurality of cylinders (not shown). In some cases, the second control circuit420is configured to control the second hydraulic fluid flow423from the second pump422into a plurality of cylinders via a valve426. In some cases, the valve426may receive a control signal from the second control circuit410; and in response, the valve426may increase, decrease, change, or shut off the second hydraulic flow423going into a specific functional device425. In one embodiment, the functional devices425include a functional device427that has rotational movements. In some cases, the functional device427includes a hydraulic motor428and a device429. In one example, the device429is a travel component of an excavator (e.g.,135ofFIG.1). In some cases, the functional devices425includes an arm component of an excavator (e.g.,125ofFIG.1) and a bucket component of an excavator (e.g.,130ofFIG.1).

In some embodiments, a control system for a hybrid power system includes a first control circuit comprising a first pump and configured to control a first hydraulic fluid flow from the first pump, a second control circuit comprising a second pump and configured to control a second hydraulic fluid flow from the second pump, and a third control circuit comprising an electric motor/generator and configured to control an electric power generated from the electric motor/generator. In some examples, a first flow rate of the first hydraulic fluid flow is different from a second flow rate of the second hydraulic fluid flow. In certain examples, the first pump is a variable displacement pump and the second pump is a variable displacement pump.

In certain embodiments, the control system further includes an electric storage device electrically coupled to the electric motor/generator, where the electric storage device is configured to provide power to the electric motor/generator. In some examples, the electric motor/generator is configured to supply power to the electric storage device. In certain examples, the third control circuit is configured to control a swing motor of an excavator.

In some examples, the first flow rate is higher than the second flow rate. In certain examples, the second control circuit is configured to feed the second hydraulic fluid flow from the second pump into a plurality of cylinders. In some designs, the second control circuit is configured to feed the second hydraulic fluid flow from the second pump into a plurality of cylinders via a main valve.

In some embodiments, the first control circuit is configured to feed the first hydraulic fluid flow from the first pump into a boom cylinder of an excavator. In some examples, the control system further includes a diesel engine configured to provide power to the electrical motor/generator, where the first control circuit is solely powered by the diesel engine and the second control circuit is solely powered by the diesel engine. In certain examples, the first control circuit is configured to provide a first power to a first functional device and the second control circuit is configured to provide a second power to a second functional device, wherein the first functional device has a first load demand and the second functional device has a second load demand, and wherein the first load demand is higher than the second load demand. In some designs, the second functional device includes a plurality of functional devices.