Load distribution and power grid support device

Abstract

A network support device comprising: a battery system; an AC power input; a power output; a power converter electrically connected between the battery system, the AC power input, and the power output; and a control unit electrically connected to the power converter and configured to detects a current of a load connected to the power output; compares the current intensity with a current threshold value; if the current is below the current threshold, at the same time Charging the battery system using the power converter using power from the AC power input, and Supplying power to the load via the power output using the power from the AC power input, and If the current is above the current threshold, discharge the battery system using the power converter to supplement AC power from the AC power input.

Description

Related RegistrationArea

[0001] The embodiments described here relate to a device for load distribution and network support. Summary

[0002] In some aspects, the techniques described herein relate to a grid support device comprising: a battery system; an AC power input; a power output; a power converter electrically connected between the battery system, the AC power input, and the power output; and a controller electrically connected to the power converter and configured to: sense a current of a load connected to the power output; compare the current to a current threshold;when the current is below the current threshold, simultaneously charging the battery system using the power converter with current from the AC power input and supplying power to the load via the power output using the current from the AC power input, and when the current is above the current threshold, discharging the battery system using the power converter to supplement AC power from the AC power input.;

[0003] In some aspects, the techniques described herein relate to a process of load balancing in a grid support device, the process comprising: sensing a current of a load electrically connected to a power output of the grid support device using a controller of the grid support device; comparing the current to a current threshold using the controller;when the current is below the current threshold, simultaneously charging a battery system of the grid support device using a power converter of the grid support device using power from an AC power input of the grid support device and supplying power using the power converter via the power output to the load using power from the AC power input, and when the current is above the current threshold, discharging the battery system of the grid support device using the power converter to supplement AC power from the AC power input;

[0004] In some aspects, the techniques described herein relate to a process of load balancing in a grid support device, the process comprising: determining a battery system power demand from a battery system of the grid support device using a control unit of the grid support device; determining a grid power estimate at a power input of the grid support device using the control unit based on a measured grid voltage and a measured grid current at the power input; determining a grid current estimate using the control unit based on the battery system power demand, the grid power estimate, and a grid current limit of a power grid; determining a duty cycle as a function of a difference between the grid current estimate and the measured grid current using the control unit;Generating PWM signals with the duty cycle using the control unit; and controlling the power converter using the control unit to convert AC power at the power input into DC power supplied to the battery system based on the PWM signals.

[0005] Before various embodiments are explained in detail below, it should be noted that the embodiments are not limited in their application to the details of the configurations and arrangements of components discussed in the following description and shown in the drawings. The embodiments may be realized or carried out in various ways. Furthermore, it should be understood that the terminology used herein is intended to be exemplary, illustrative, and not limiting. Phrases such as “include,” “comprise,” or “have” may include other elements in addition to those mentioned in connection therewith. Phrases such as “mounted,” “connected,” “held,” and “coupled” may refer to direct and indirect mountings, connections, supports, and couplings.

[0006] Unless the context of their use clearly requires otherwise, the articles "ein," "eine," and "der" should not be understood as "one" or "only one." Rather, these articles should be interpreted as "at least one" or "one or more." Similarly, when referring to a noun previously introduced by the indefinite article "ein" or "eine," the terms "der" or "genannter" mean "at least one" or "one or more," unless the context clearly indicates otherwise.

[0007] It should also be noted that embodiments may include hardware, software, and electronic components or modules, which for simplicity are described herein as if implemented solely by hardware. It should be apparent to those skilled in the art that, in at least one embodiment, the electronic-based aspects may be implemented in software (e.g., stored on a non-transitory, computer-readable medium) and executed by one or more processing units such as a microprocessor and / or application-specific integrated circuits (“ASICs”). It should be noted that a variety of hardware- and software-based devices, as well as a variety of different structural components, may be used to implement the embodiments. For example, references to “servers,” “computing devices,” “controllers,” “processors,” etc., may be made in the description.one or more processing units, one or more computer-readable media modules, one or more input / output interfaces, and various connections (e.g., a system bus) between the components.

[0008] Phrases such as "approximately," "approximately," "substantially," etc., with respect to quantities or conditions should be understood to include the stated value and interpreted according to the context (e.g., such terms include at least a degree of error associated with measurement accuracy, tolerances associated with the specified value [e.g., in manufacture, assembly, use, etc.], etc.). Such phrases include the range defined by the absolute values ​​of the two endpoints. For example, a phrase such as "from about 2 to about 4" also indicates the range "from 2 to 4." Approximations may include a range of a percentage plus or minus the stated value (e.g., 1%, 5%, 10%).

[0009] It should be noted that while certain drawings depict hardware and software in specific devices, these depictions are for illustrative purposes only. Functions described herein as being performed by one component may be performed in a distributed manner by multiple components. Likewise, functions performed by multiple components may be consolidated and performed by a single component. In some embodiments, the depicted components may be combined or separated into separate software, firmware, and / or hardware. For example, rather than being located in and executed by a single electronic processor, logic and processing may be distributed among multiple electronic processors.Regardless of how they are combined or distributed, hardware and software components may be located on the same computing device or distributed among different computing devices interconnected by one or more networks or other suitable communications links. Similarly, a component described as performing a particular function may also perform additional functions not described herein. For example, a device or structure "configured" in a particular manner is configured at least in that manner, but may also be configured in other ways not explicitly listed.

[0010] Thus, when the claims claim an apparatus, method, or system such as a controller, control unit, electronic processor, computing device, logic element, module, memory module, communications channel or network, or other element configured in a particular manner, for example, to perform various functions, the claim or claim element is to be interpreted to include one or more such elements, wherein any of the one or more elements may be configured as claimed to perform one or more recited functions, such that the one or more elements, in combination, collectively perform the multiple functions.

[0011] Other aspects of the embodiments will become apparent from the following description and the accompanying drawings. Short description of the drawings Fig. 1 is a simplified block diagram of a network support device according to some embodiments. Fig. 2A-2B are perspective views of mesh support devices according to some embodiments. Fig. 3 is a simplified block diagram of the network support device of Fig. 1 according to some embodiments. Fig. 4 is a schematic diagram of a dual-active bridge of the network support device of Fig. 1 according to some embodiments. Fig. 5 shows a block diagram of a control process of the network support device of Fig. 1 according to some embodiments. Fig. 6 shows a block diagram of a control process of the network support device of Fig. 1 according to some embodiments. Fig. Figure 7 is a diagram of the operation of the network support device of Fig. 1 according to some embodiments. Fig. 8 is a flowchart of an operation process of the network support device of Fig. 1 according to some embodiments. Fig. 9 shows a bidirectional power converter of the grid support device of Fig. 1 according to some embodiments. Detailed description

[0012] Fig. 1 shows a simplified block diagram of an exemplary grid support device 100 (also referred to as device 100). The grid support device 100 includes a battery system 110, an AC power input 120, a power output 130, and a power converter 140 electrically connected between the battery system 110, the AC power input 120, and the AC power output, also referred to as power output 130. The AC power input 120 may be connected to an AC power source 125. The AC power source 125 is, for example, an electrical power grid (also referred to as a grid or power grid), such as a 120V / 240V (volt) residential or commercial AC power source connected to the grid support device 100 via a power cord.The power output 130 may be an AC outlet and / or a DC outlet, which may be used to power one or more external electronic devices. In some examples, the power output 130 is provided to power an internal motor, heater, or other element configured to be electrically operated within the grid support device 100. The power converter 140 is configured to convert DC to AC, DC to DC, AC to DC, and / or AC to AC between the battery system 110, the AC power input 120, and the power output 130.For example, power converter 140 converts DC power from battery system 110 to AC power for power output 130 and converts AC power from AC power input 120 to DC power to charge battery system 110. Power converter 140 also provides pass-through power between AC power input 120 and power output 130.

[0013] The power converter 140 enables the grid support device 100 to efficiently control the flow of power between the battery system 110, the AC power input 120, and the power output 130. When an AC power source is available at the AC power input 120, the power converter 140 can convert the AC power to DC power, which is then used to charge the battery system 110. This ensures that the battery system 110 remains charged and ready to supply power when needed.Conversely, if no AC power source is available at the AC power input 120, or if the grid support device 100 requires more power than the AC power input 120 can supply, the power converter 140 can convert the DC power from the battery system 110 to AC power, which can then be supplied to the power output 130 to supplement the AC power from the AC power input 120. This configuration allows the grid support device 100 to continue operating smoothly even in the absence of AC power at the AC power input 120 or during periods of dynamically changing load demands that exceed the trigger limit of the grid power source. The power converter 140 enables the grid support device 100 to simultaneously charge the battery system 110 and power a load 135.For example, if a power demand at power output 130 is below a threshold, grid support device 100 may be configured to use power converter 140 to charge one or more batteries connected to battery system 110 without reducing the power output used by load 135.

[0014] The power converter 140 may include one bidirectional converter or multiple unidirectional converters. A unidirectional converter is designed to convert power in only one direction, from an input side to an output side. While a unidirectional converter may be useful in certain applications, it lacks the versatility and efficiency of a bidirectional converter. The bidirectional converter can help reduce the overall cost and complexity of the grid support device 100 by eliminating the need for separate charging and discharging circuits. A bidirectional converter can be used in the grid support device 100 to optimize its power management system, thereby improving overall reliability and reducing the number of required components.This not only makes the grid support device 100 more cost-effective, but also simplifies maintenance and troubleshooting processes. In some examples, the grid support device 100 is configured to detect a power level of the load 135. The grid support device 100 may determine the power level using a sensor that detects a current flow to the load 135.

[0015] Fig. 2A shows an example of a grid support device 100 in the form of a portable power source 100A. The portable power source 100A includes a housing 205 for receiving an internal battery module 210. The housing 205 also includes an input / output panel 215. The input / output panel 215 includes a power input 220 and an outlet 225. The outlet 225 is, for example, an AC outlet for powering AC electronic devices. The internal battery module 210 corresponds to the battery system 110. The power input 220 and the outlet 225 correspond to the AC power input 120 and the power output 130, respectively. The power converter 140 is coupled between the internal battery module 210, the power input 220, and the outlet 225. The power converter 140 converts direct current from the internal battery module 210 into alternating current for the socket 225.The power converter 140 also converts the AC power from the power input 220 to DC power for charging the internal battery module 210. The portable power source 100A may include additional components not described or illustrated herein. For example, the portable power source 100A may include additional outlets 225 (e.g., both AC and DC), a display, and the like.

[0016] The 140 power converter is designed for high currents, making it suitable for powering a wide range of electronic devices. The 225 outlet is an AC outlet capable of powering high-current devices such as power tools, household appliances, and large electronic devices. The 140 power converter's high current capacity allows the 100A portable power source to provide stable and reliable power to these devices without brownouts or other performance issues. For example, many power tools consume a lot of power under heavy operating load, and a standard electrical system may not be able to support these high current peaks. In such cases, the power switch / outlet may trip, interrupting the use of the connected power tool and requiring the power switch to be reset.However, by using the 100A portable power source, which includes the 140 power converter, these high current spikes can be mitigated, reduced, or completely eliminated.

[0017] In addition to powering external devices, the high current capability of the power converter 140 also enables faster charging of the internal battery module 210. When connected to an AC power source via the power input 220, the power converter 140 can efficiently convert the AC power to DC power, allowing the internal battery module 210 to be quickly charged. This is especially beneficial for users who need to quickly recharge the 100A portable power source between uses or during short work breaks.

[0018] The 100A portable power source may also include additional features that enhance its functionality and usability. For example, the device may include multiple outlets 225, including both AC and DC outlets, to connect a wider range of electronic devices. A display may be integrated into the housing 205 to provide users with real-time information about the charge level of the internal battery module 210, the power output, historical output current data, remaining battery charge time, and other relevant data. The high current capacity of the power converter 140 enables the 100A portable power source to be used in various other applications requiring reliable power, such as outdoor events, emergencies, or as a backup power source for homes and small businesses during short-term power outages.

[0019] Fig. 2B shows an example of a grid support device 100 in the form of a portable power source 100B. The portable power source 100B includes a housing 230 having a first battery interface 235A and a second battery interface 235B. The first battery interface 235A and the second battery interface 235B are configured to receive a first removable power tool battery pack 240A and a second removable power tool battery pack 240B, respectively. The first removable power tool battery pack 240A and the second removable power tool battery pack 240B, individually referred to as a removable power tool battery pack 240, are, for example, lithium-ion power tool battery packs having a nominal voltage of 12 volts, 18 volts, 24 volts, 36 volts, 54 volts, 72 volts, 90 volts, 108 volts, or the like.The detachable 240 power tool battery pack can be used to power cordless indoor and outdoor power tools. The 100B portable power source also includes a 245 power input and a 250 outlet. The 250 outlet, for example, is an AC outlet for AC-powered electronic devices.

[0020] The removable power tool battery packs 240 correspond to the battery system 110. The power input 245 and the power outlet 250 correspond to the AC power input 120 and the power output 130, respectively. The power converter 140 is coupled between the removable power tool battery packs 240, the power input 245, and the power outlet 250. The power converter 140 converts DC power from the removable power tool battery packs 240 to AC power for the power outlet 250. The power converter 140 also converts the AC power from the power input 245 to DC power for charging the removable power tool battery packs 240. The portable power source 100B may include additional components not described or illustrated herein. For example, the portable power source 100B may include additional outlets 250 (e.g., both AC and DC), a display, and the like.

[0021] Fig. 3 shows a block diagram 300 of an electronic control unit 305 for the grid support device 100. The electronic control unit 305 is electrically and / or communicatively connected to a variety of modules or components of the grid support device 100. For example, the electronic control unit 305 is connected to the power converter 140, a user input 310, other components 315 (e.g., a battery pack charge indicator, work lights [e.g., LEDs], current / voltage sensors, etc.), one or more display units 320 (e.g., LEDs), and one or more sensors 360 (e.g., current and / or voltage sensors).

[0022] The electronic control unit 305 includes combinations of hardware and software that serve, among other things, to control the operation of the network support device 100, as described below with respect to the Fig. 4 and Fig. 5. In some embodiments, the electronic control unit 305 includes a plurality of electrical and electronic components that power, operate, and protect the components and modules within the electronic control unit 305 and / or the grid support device 100. For example, the electronic control unit 305 includes, among other things, a processing unit 325 (e.g., a microprocessor, a microcontroller, or other suitable programmable device), a memory 330, input units 335, and output units 340. The processing unit 325 includes, among other things, a control unit 345, an arithmetic logic unit ("ALU") 350, and a plurality of registers 355 (in Fig. 3 as a group of registers) and is implemented using a known computer architecture (e.g., a modified Harvard architecture, a von Neumann architecture, etc.). The processing unit 325, the memory 330, the input units 335 and the output units 340, as well as the various modules connected to the electronic control unit 305, are connected by one or more control and / or data buses (e.g., a common bus 365). The control and / or data buses are shown for illustrative purposes in Fig. 3. The use of one or more control and / or data buses for interconnection and communication between the various modules and components would be known to one of ordinary skill in the art in light of the embodiments described herein.

[0023] The memory 330 is a non-transitory, computer-readable medium, including, for example, a program storage area and a data storage area. The program storage area and the data storage area may include combinations of different memory types, such as read-only memory ("ROM"), random access memory ("RAM") (e.g., dynamic RAM ("DRAM"), synchronous DRAM ("SDRAM"), etc.), electrically erasable programmable read-only memory ("EEPROM"), flash memory, a hard disk, an SD card, or other suitable magnetic, optical, physical, or electronic storage devices. The processing unit 325 is connected to the memory 330 and executes software instructions stored in a RAM of the memory 330 (e.g., during execution), a ROM of the memory 330 (e.g.,on a generally permanent basis) or other non-transitory, computer-readable medium such as another memory or a disc. The software included in the implementation of the network support device 100 may be stored in the memory 330 of the electronic control unit 305. The software includes, for example, firmware, one or more applications, program data, filters, rules, one or more program modules, and other executable instructions. The electronic control unit 305 is configured to retrieve and execute instructions related to, among other things, controlling the network support device 100 described herein from the memory. In other constructions, the electronic control unit 305 includes additional, fewer, or different components.

[0024] The grid support device 100 is configured to operate in various modes. For example, the grid support device 100 may operate in a pure charge mode. In the pure charge mode, the controller 305 controls the power converter 140 to convert AC power from the AC power input 120 to DC power at the appropriate DC level to charge the battery system 110. The grid support device 100 may operate in a pure discharge mode. In the pure discharge mode, the controller 305 controls the power converter 140 to convert DC power from the battery system 110 to AC power and / or DC power at a different DC level, which is supplied to the power output 130. The grid support device 100 may operate in a pure pass-through mode.In pass-only mode, the controller 305 may deactivate the power converter 140 and connect the AC power input 120 directly to the power output 130, or connect the AC power input 120 to the power output 130 via the power converter 140. The grid-assist device 100 may operate in a grid-assist mode. In the grid-assist mode, the controller 305 may control the power converter 140 to convert DC power from the battery system 110 to AC power, which is then used to supplement the power from the AC power input 120 supplied to the power output 130. Other modes, such as a charge-discharge mode, a charge-pass mode, and / or the like, are also available, and the controller 305 controls the power converter 140 accordingly in these modes.

[0025] Fig. 4 shows an example implementation of a dual-active bridge (DAB) 400 that may be used in power converter 140. DAB 400 is connected between battery system 110 and a DC bus and bidirectionally converts power between battery system 110 and the DC bus (e.g., a DC / DC conversion). For example, DAB 400 may convert power at a first voltage (e.g., 400 volts) on the DC bus to a second voltage on battery system 110 that corresponds to the charging voltage of battery system 110 to charge battery system 110. The DAB 400 can also convert power at a third voltage (e.g., the battery system voltage) on the battery system 110 to the first voltage (e.g., 400 volts) on the DC bus, which can be converted to AC to power the load 135.The DAB 400 includes a first H-bridge 405A on a first side, a second H-bridge 405B on a second side, and a transformer 410 electrically connected between the first H-bridge 405A and the H-bridge 405B.

[0026] The first H-bridge 405A is connected to a first DC bus 415A (e.g., the DAB 400 is electrically connected to the battery system 110 at a first end) and includes four switches 420 provided in an H-bridge configuration. The switches 420 include two high-side switches 420A, 420B electrically connected between a positive terminal of the first DC bus 415A and a first side 425 of the transformer 410, and two low-side switches 420C, 420D electrically connected between a negative terminal of the first DC bus 415A and the first side 425 of the transformer 410. The second H-bridge 405B is connected to a second DC bus 415B (e.g., the DAB 400 is electrically connected at a second end to a DC bus of the grid support device 100) and includes four switches 420 provided in an H-bridge configuration.The switches 420 include two high-side switches 420E, 420F electrically connected between a positive terminal of the second DC bus 415B and a second side 430 of the transformer 410, and two low-side switches 420G, 420H electrically connected between a negative terminal of the second DC bus 415B and the second side 430 of the transformer 410. In one example, the plurality of switches 420 include metal-oxide-semiconductor field-effect transistors (MOSFETs). In another example, the plurality of switches 420 include wide-bandgap semiconductor FETs, i.e., FETs based on gallium nitride (GaN) and / or silicon carbide (SiC). In another example, the plurality of switches 420A-H may include a combination of MOSFETs and wide-bandgap semiconductor FETs. The switches 420 are controlled by the control unit 305 using a gate driver.

[0027] The switches 420A-D are electrically connected to an inductor 435 on the first side 425 of the transformer 410. The transformer 410 can be a high-frequency transformer that increases, decreases, or maintains the voltage between the first side 425 and the second side 430 of the transformer 410. The DAB 400 converts a first voltage on the first DC bus 415A to a second voltage on the second DC bus 415B and vice versa (e.g., performing a DC / DC conversion between the first end and the second end). For example, the first H-bridge 405A converts the first DC voltage on the first DC bus 415A to a first AC voltage on the first side 425 of the transformer 410. The transformer 410 generates a second AC voltage on the second side 430 in response to the first AC voltage.The second H-bridge 405B converts the second AC voltage to the second DC voltage on the second DC bus 415B. A similar process can be used in reverse to convert the second DC voltage to the first DC voltage.

[0028] The DAB 400 enables a single connection between the battery system 110 and the power converter 140, or a single current path between the battery system 110 and the power converter 140, to both charge and discharge the battery system 100. The DAB 400 can be controlled using a phase angle between the two sides of the DAB 400. Specifically, the phase angle determines the direction and amount of power transfer between the first side and the second side of the DAB 400. This phase angle is used to offset the gate signals of the switches of the first H-bridge 405A relative to the switches of the second H-bridge 405B to control power transfer.

[0029] Fig. 5 shows a block diagram of a control system 500 of the grid support device 100. The control system 500 may generate control signals (i.e., the phase angle signals and the gate signals) for the DAB 400 and may be implemented by the control unit 305. In the illustrated example, the grid support device 100 is configured to operate in a "pass-through mode" in which the AC power from the AC power input 120 is passed to the power output 130. The power from the AC power input 120 may be supplemented by the battery system 110. The control system 500 may regulate DC bus voltages and currents to mitigate or eliminate any harmonic resonance of the battery system 110 that may occur.

[0030] The control system 500 includes a feedforward processing block 505 and a voltage regulator block 510. The feedforward processing block 505 is configured to receive an inverter power estimate 515 based on the current requirements of the load 135. For example, in some embodiments, a current sensor may be positioned at the output and configured to sense an output current, which is used by the control system 500 to determine the inverter power estimate 515. The voltage regulator block 510 is configured to determine an error 530 between a nominal DC bus voltage 520 and a measured DC bus voltage 525 (e.g., instantaneous or real-time voltage). The nominal voltage 520 and the measured voltage are DC bus voltages from the grid support device 100 (see, for example, Fig. 9). For example, the nominal voltage 520 may be a predetermined voltage level, such as 400 V on a DC bus of the grid support device 100.

[0031] The measured voltage 525 is, for example, the real-time measured voltage value of the DC bus of the grid support device 100, which is provided to the control system 500 by a voltage sensor (e.g., sensor 360). The voltage regulator block 510 determines a deviation 530 (e.g., difference) between the nominal voltage 520 and the measured voltage 525, for example, using a proportional-integral (PI) method. The voltage regulator block 510 generates the error signal 530 based on the difference between the nominal voltage 520 and the measured voltage 525. A first summing block 535 sums the error signal 530 with the inverter power estimate 515 from the feedforward control block 505 to generate a current estimate 540.

[0032] A current control block 545 receives the current estimate 540, a measured current 550, a charge limit 555, and a discharge limit 560. The measured current 550 may be a real-time measured current value of the DC bus of the grid support device 100. The charge limit 555 is a maximum amount of current for charging the battery system 110, and the discharge limit 560 is the maximum amount of current that may be discharged from the battery system 110. The current control block 545 generates a phase angle 565 based on the current estimate 540, the measured current 550, the charge limit 555, and the discharge limit 560. The phase angle 565 is used to generate the control signal for controlling the DAB 400.

[0033] The phase angle 565 can be summed with a proportional integral constant (π) 570 in a second summing block 575 to generate a shifted phase angle 580. A pulse width modulation (PWM) generator block 590 generates control signals to control the DAB based on the phase angle 565, the shifted phase angle 580, and the phase shift 585. The PWM generator block converts the phase angle 565 and the shifted phase angle 580 into pulse width modulation signals that directly control the switching elements (e.g., switches 420A-H) within the DAB 400.

[0034] Fig. 6 shows a block diagram of a control system 600 of the network support device 100 of Fig. 1 according to some examples. In the illustrated example, the grid support device 100 is configured to operate in a "pass-through mode" in which the AC power is passed from the AC power input 120 to the power output 130 and may be supplemented by the battery system 110. The control system 600 includes a processing block 605 and a grid power estimator block 610. The processing block 605 is configured to receive a battery power request 615, and the grid power estimator block 610 is configured to receive a grid voltage 620 and a grid current 625. The battery power request 615 is, for example, the amount of energy needed to charge the battery system 110 or available in the battery system 110.

[0035] The grid power estimation block 610 determines a grid power estimate 630 based on the grid voltage 620 and the grid current 625. The grid voltage 620 and the grid current 625 are the real-time measured voltage and current values ​​of the grid connected via the AC power input 120, and the measured voltage and current values ​​can be determined by a sensor 360.

[0036] A grid current control block 640 receives the grid power estimate 630, an upper limit 645, and a grid current limit 650. The upper limit 645 is the maximum current (e.g., a maximum current limit) that can be transferred (e.g., recirculated) back to the grid and can be set to 0. The grid current limit 650 is similarly set to a predefined constant value configured to limit the power transferred from the grid to the grid support device 100. For example, the grid current limit 650 can be set to a value of -18, which limits the power drawn from the grid to 18 amperes. For constant-voltage sources, such as the electrical grid, the power level corresponds to the amperage. Therefore, power level and amperage can be used interchangeably for constant-voltage power sources.In some cases, the grid current limiter 650 can be set to other values ​​to limit the power consumption to an arbitrary current value, such as 5 amps, 10 amps, 20 amps, or another current value. The grid current regulator block 640 can perform a continuous PI calculation using the grid power estimate 630, the battery power estimate 635, the cap 645, and the grid current limit 650 to output a regulated grid current 646.

[0037] A dq control block 655 transforms (e.g., by an inverse dq transformation) the output of the line current control block 640 into an AC signal. The dq control block 655 is also configured to receive an upper limit 660, similar to the upper limit 645, and a phase-locked loop 657. The phase-locked loop 657 provides frequency and phase synchronization of the dq control block 655. The output of the dq control block 655 is then sent to a current control block 675 as a line current estimate 670. The current control block 675 is also configured to receive the grid current 625 and use the grid current 625 and the grid current estimate 670 to perform a PI calculation, similar to the previously described current control block 545. For example, the current control block 675 determines an error (e.g., a difference) between the grid current 625 and the grid current estimate 670.

[0038] The control system 600 also includes a harmonic resonance compensator block 680 configured to receive the mains power 625. The harmonic resonance compensator block 680 is configured to attenuate or eliminate certain harmonic frequencies in the response of the control system 600 to reduce the presence of unwanted harmonic components that can cause distortion and other performance problems in the control system 600. In some examples, the harmonic resonance compensator block 680 is configured to specifically select the 3rd, 5th, and 7th harmonic resonance frequencies. In some cases, alternative or additional harmonic resonance frequencies are selected by the harmonic resonance compensator block 680.

[0039] The output of the harmonic resonant compensator 680 is then summed with the output of the current control block 675 to generate the frequency-compensated signal 685. The frequency-compensated signal 685 can then be summed with a cap voltage 690 to generate an inverter reference voltage 691. A duty cycle block 697 generates a duty cycle control signal 696 based on the inverter reference voltage 691 and the DC link voltage 695. For example, a duty cycle is determined as a function of a division between the inverter reference voltage and the DC link voltage 695 and provided as a duty cycle control signal 696 to the gate driver 699. The gate driver 699 generates PWM signals with the duty cycle to control the switches in the inverter.The inverter of the grid support device 100 converts direct current at the DC bus of the grid support device 100 into alternating current at the power output 130.

[0040] Fig. 7 is a diagram 700 illustrating the operation of the grid support device 100 including the power converter 140, according to some embodiments. The diagram 700 includes a plot of the grid power 705 and the inverter power 710, measured at the power output 715 (watts) over time 720. The diagram 700 illustrates a situation where a 2000-watt load is connected after 1.5 seconds and disconnected after 2.5 seconds. The grid power 705 may be limited to 1500 watts. During the period up to 1.5 seconds, the battery system 110 charges with 1000 watts of the 1500-watt power available from the AC power source 125.

[0041] During the period between 1.5 seconds and 2.5 seconds, the difference of 500 watts is provided by the inverter power 710 for the duration of the required power output. After 2.5 seconds, the power from the AC power source 125 is used to charge the battery system 110. In some cases, the grid power 705 is limited to a different power output value, for example, 1000 watts. Additionally, in some cases, the power output 715 may be limited to a predetermined value for a predetermined period of time. For example, the power output 715 may be limited to 1500 watts for a duration of 1 second. In some cases, the duration of the power output may take on other values, for example, between 1 second and 10 seconds, or any other duration greater than 0 seconds.

[0042] In some examples, grid support device 100 may provide reactive power to load 135 so that the grid provides as much power as possible relative to the power provided by battery system 110. In some examples, grid support device 100 mitigates the harmonic resonance between the grid and load 135. In some cases, the electronic device is configured to draw power output from the grid during times of low grid power demand. In some cases, the electronic device may be configured to return power to the grid during times of high grid power usage.

[0043] Fig. 8 is a flowchart of an example process 800 for load balancing. Process 800 may be performed by control unit 305. Process 800 includes receiving a maximum current limit (e.g., a current threshold) (at step 810). In some cases, the maximum current limit is determined as previously described in control system 500. For example, control system 500 allows grid support device 100 to regulate the power used by load 135 beyond a current limit provided by a conventional grid. This limit may be a predetermined value programmed into control system 500 or may be determined by a user of grid support device 100. Using control system 500, the grid current may be regulated to a user-defined maximum current depending on the work being performed.

[0044] The process 800 includes receiving a load current (in step 815). The load current may, for example, be a measured real-time current of the load 135. As the load 135 increases or decreases during use of the grid support device 100, the current of the load 135 is measured and processed by the control system 500. For example, the load 135 may have a measured current of 20 amps or 5 amps, or any other current value. The process 800 includes determining a state of charge or discharge (in step 820). The control unit 305 compares the load current to the current threshold (e.g., the maximum current limit), for example, in blocks 505, 510, and 545 of the control system 500. As previously described, a state of charge is, for example, a case where the required load current is less than the maximum current limit provided by the grid.Conversely, a discharge condition is, for example, a case where the required load current is greater than the maximum current limit provided by the grid. For example, if the grid includes a maximum current limit of 15 amperes (A), but the load 135 requires at least 20 A, the controller 305 supplies the remaining 5 A from the battery system 110. The process 800 enables the grid support device 100 to combine the maximum grid current with additional current from the battery system 110, thereby providing an output current greater than the amount provided by the grid alone.

[0045] In another example, the controller 305 draws power from the grid to charge the battery system 110 when the load 135 is below the maximum current limit. For example, if the maximum current limit is 15 amps, but the load 135 only requires 5 amps, the controller 305 may draw up to an additional 10 amps to charge the battery system 110. As previously described, in some cases, the amount of power drawn from the grid and supplied to the grid support device 100 may depend on a user-defined limit. For example, a user may limit the current drawn from the grid to any value, such as 1 amp, 5 amps, or any current level. Similarly, the amount of power provided by the grid support device 100 may also be limited by the user.For example, the user may limit the current delivered by the battery system 110 to a value such as 1 amp, 5 amps, or any desired current.

[0046] Process 800 includes controlling power converter 140 using controller 305 based on the charge / discharge state (at step 825). Controller 305 controls DAB 400 and the inverter of power converter 140 to ensure consistent charging and discharging of the battery pack. Fig. 5 and Fig. 6 illustrate some examples of control systems used to implement process 800. Other implementations may be used to supplement AC power from an input to support the power requirements at the power output of grid support device 100.

[0047] Fig.9 shows an embodiment of the power converter 140. In the illustrated example, the power converter includes the DAB 400, an AC-to-DC converter 910, and an inverter 920. The AC-to-DC converter 910 is electrically connected between the AC power input 120 and a DC bus 930 and converts AC power from the AC power input 120 to DC power at the DC bus 930. The DAB 400 is electrically connected between the DC bus 930 and the battery system 110 and bidirectionally converts DC power between the DC bus 930 and the battery system 110, for example, based on the control signals generated by the control system 500.The inverter 920 is electrically connected between the DC bus 930 and the AC power output 130 and converts DC power at the DC bus 930 to AC power at the AC power output 130, for example, based on the control signals generated by the control system 600. In some examples, the AC power input may be directly connected to the AC power output in parallel with the power path through the inverter 920. The control unit 305 is electrically connected to the components of the AC-to-DC converter 910, the DAB 400, and the inverter 920 to control these components by implementing the control systems 500, 600. The AC-to-DC converter 910 and the inverter 920 may be implemented using an H-bridge architecture similar to the first H-bridge 405A or the second H-bridge 405B of the DAB 400.

[0048] Although the disclosure has been described in detail with reference to certain preferred embodiments, variations and modifications are possible within the scope and spirit of one or more independent aspects of the disclosure as described. Various features and advantages are set forth in the following claims.

Claims

[1] A network support device comprising: a battery system; an AC power input; a power output; a power converter electrically connected between the battery system, the AC power input, and the power output; and a control unit electrically connected to the power converter and configured to detects a current of a load connected to the power output; compares the current intensity with a current threshold value; if the current is below the current threshold, at the same time Charging the battery system using the power converter using power from the AC power input, and Supplying power to the load via the power output using the power from the AC power input, and If the current is above the current threshold, discharge the battery system using the power converter to supplement AC power from the AC power input. [2] The network support device according to claim 1, wherein the network support device further comprises: a dual-active bridge electrically coupled to the battery system at a first end and to a DC bus at a second end and configured to perform DC / DC conversion between the first end and the second end. [3] The network support device according to claim 2, wherein the control unit is configured to to receive a measured DC bus voltage; to determine a DC bus voltage error between the DC bus voltage and a nominal DC bus voltage; determine a DC bus current estimate based on the load current and the DC bus voltage error; and charge / discharge the battery system using the power converter based on the DC bus current estimate. [4] The grid support device of claim 1, wherein the current threshold corresponds to a maximum current limit of a grid power source connected to the AC power input. [5] The grid support device according to claim 4, wherein the control unit is configured to regulate a current output of the power converter at the power output to a maximum current limit of the grid support device, wherein the maximum current limit of the grid support device is greater than the maximum current limit of the grid power source. [6] The network support device according to claim 1, wherein the control unit is configured to to determine a difference between a maximum power level of the AC power input and a power level of the AC power output; and to control the power converter to convert the difference from alternating current to direct current to charge the battery system. [7] The grid support device of claim 1, wherein the power converter comprises a bidirectional converter configured to convert power from the battery system to the power output and to convert power from the AC power input to the battery system. [8] The grid support device of claim 1, wherein the battery system comprises one or more removable battery packs, the grid support device further comprising: a housing; and a battery pack interface on the housing configured to receive the one or more removable battery packs.

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