Background

[0001] Computing systems can utilize devices such as an uninterruptible power system (UPS). The UPS can help provide backup power to the computing system when main power fails. When high voltage direct current (HVDC) is utilized to provide power to a load there can be a risk of an in-rush of current to a battery pack and/or load that can cause damage to the load upon start-up of a power source.

Brief Description of the Drawings

[0002] Figure 1 illustrates a diagram of an example of a system for increasing duty cycle consistent with the present disclosure.

[0003] Figure 2 illustrates a diagram of an example computing device for increasing duty cycle consistent with the present disclosure.

[0004] Figure 3 illustrates an example system for increasing duty cycle consistent with the present disclosure.

[0005] Figure 4 illustrates a flow chart of an example of a method for increasing duty cycle consistent with the present disclosure.

Detailed Description

[0006] A number of methods, systems, and computer readable medium for providing a soft-start from a source to a load are described herein. As used herein, the concept of soft-start refers to a process where input voltage is gradually brought up to full voltage at the output by increasing a duty cycle of power delivered to a load. A power system for computing applications can include a main power source that can provide power to a number of loads within the computing system. The system can also include a back-up power source (e.g., battery, battery pack, etc.) that can provide power to the number of loads upon failure of the main power source. Some systems can utilize a high voltage direct current (HVDC) main power source and an HVDC backup power source. Providing a soft-start for HVDC can prevent in-rush current from occurring in a load upon start-up of the main power source. As used herein, an in-rush of current includes an instantaneous input current drawn by an electrical device (e.g., load) when first turned on.

[0007] In some examples, the system can utilize a HVDC power source that can have a particular duty cycle for activating and/or deactivating (e.g., turning on and/or turning off, etc.). The duty cycle can imply a ratio between switch on-time when the input voltage is allowed to be imposed, and switch off-time, when the input voltage is decoupled. In some examples, the main power source or back-up power source can be turned on by increasing a duty cycle percentage from 0 percent to 100 percent over a plurality of incremental steps. In some examples, the plurality of incremental steps includes relatively small percentage increases of a duty cycle (e.g., increase of a quantity of time that a switch is activated to allow power from a source to a load). For example, the plurality of incremental steps can each comprise a 1 % duty cycle increase for each of the plurality of incremental steps. That is, the main power source can be activated for a portion of a complete duty cycle of the respective power source to incrementally build up a voltage at an inductor and/or a load. In some examples, the inductor can be coupled between a node of the first and second switch and the output to the load. Incrementally building up the voltage can provide a soft-start for the HVDC power source and prevent an in-rush of current to a load coupled to the HVDC power source.

[0008] Increasing a duty cycle (e.g., duty cycle percentage) of a power source can be performed by activating and deactivating switches (e.g., converter switches, switch SS1 352 as referenced in Figure 3, switch SS2 354 as referenced in Figure 3, etc.). Increasing the duty cycle can lead to a gradually rising voltage instead of a sudden impulse. This can prevent an inrush of current that could compromise hardware and/or cause input voltage to drop, leading to equipment shutdown.

[0009] Figures 1 and 2 illustrate examples of system 100 and computing device 214 consistent with the present disclosure. Figure 1 illustrates a diagram of an example of a system 100 for increasing duty cycle consistent with the present disclosure. The system 100 can include a database 104, a soft-start system 102, and/or a number of engines (e.g., controller engine 106). The soft-start system 102 can be in

communication with the database 104 via a communication link, and can include the number of engines (e.g., controller engine 106). The soft-start system 102 can include additional or fewer engines that are illustrated to perform the various functions as will be described in further detail in connection with Figures 3-4.

[0010] The number of engines (e.g., controller engine 106) can include a combination of hardware and programming, but at least hardware, that is configured to perform functions described herein (e.g., increase a duty cycle of power delivered to a load in a plurality of incremental steps through an activation of the switch, wherein the switch is coupled between a direct current (DC) source input and an output to the load, activates the switch for a first incremental step of the plurality of incremental steps and deactivates the switch for a corresponding stabilization cycle to stabilize the voltage when the switch is deactivated, etc.). The programming can include program

instructions (e.g., software, firmware, etc.) stored in a memory resource (e.g., computer readable medium, machine readable medium, etc.) as well as hard-wired program (e.g., logic).

[0011] The controller engine 106 can include hardware and/or a combination of hardware and programming, but at least hardware, to increase a duty cycle of power delivered to a load in a plurality of incremental steps through an activation of the switch, wherein the switch is coupled between a direct current (DC) source input and an output to the load. In addition, a second switch (e.g., stabilization switch) can be coupled between a DC backup input and the output to the load. In these examples, a node can exist at a point where the connection between the first switch and the second switch exists. That is, a node can be a position of the connection lines (e.g., wires, etc.) where the first switch, the second switch, and the load are all coupled together. In some examples, as described further herein, an inductor is coupled between the node of the first and second switch and the load. In some examples, the inductor can be coupled between the node of the first and second switch and the output to the load. In some examples, the second switch can comprise a free-wheeling diode (e.g., flyback diode, suppressor diode, etc.) to stabilize voltage during a stabilization cycle. A free-wheeling diode can be used to eliminate the sudden voltage spike across an inductive load when its supply voltage is suddenly reduced or removed. A stabilization cycle can include a time when the first switch is deactivated and a free-wheeling diode of the second switch helps circulate energy while the first switch is deactivated. That is, the free-wheeling diode can stabilize the voltage when the first switch is deactivated or turned off.

[0012] The controller engine 106 can increase a duty cycle of power delivered to a load in a plurality of incremental steps through an activation of the switch. That is, the controller engine 106 can increase a duty cycle percentage for each of a plurality of incremental steps to incrementally increase the voltage at the load to avoid an in-rush of current at the load. As described herein, an in-rush of current from a HVDC power source can damage components (e.g., electrical components, computing devices, etc.) of the load.

[0013] In some examples, the controller engine 106 can activate the first switch for a first duty cycle of the plurality of incremental steps and deactivate the first switch for a stabilization cycle to stabilize the voltage when the first switch is deactivated. The stabilization cycle superimposes the HVDC backup input (e.g., backup power source, backup battery, etc.) on an output of the first switch via a free-wheeling diode of the second switch. That is, superimposing power from the HVDC backup power input with power from the HVDC source input at the output of the first switch. This stabilized voltage at the output of the first switch allows for the voltage to be incrementally increased at an inductor coupled to a load and thus prevents the in-rush of current at the load upon startup of the power source and/or the load. Damage can be done to the components of the load when the voltage of the power source is not incrementally increased due to an in-rush of current as described here. [0014] Figure 2 illustrates a diagram of an example computing device 214 consistent with the present disclosure. The computing device 214 can utilize software, hardware, firmware, and/or logic to perform functions described herein.

[0015] The computing device 214 can be any combination of hardware and program instructions configured to share information. The hardware, for example, can include a processing resource 216 and/or a memory resource 220 (e.g., computer- readable medium (CRM), machine readable medium (MRM), database, etc.). A processing resource 216, as used herein, can include any number of processors capable of executing instructions stored by a memory resource 220. Processing resource 216 may be implemented in a single device or distributed across multiple devices. The program instructions (e.g., computer readable instructions (CRI)) can include instructions stored on the memory resource 220 and executable by the processing resource 216 to implement a desired function (e.g., activate a first switch coupled to a high voltage direct current (HVDC) input for a first incremental duty cycle, deactivate the first switch for a stabilization cycle to stabilize voltage when the first switch is deactivated, activate the first switch for a second incremental duty cycle, wherein the second incremental duty cycle includes a greater quantity of time compared to the first incremental duty cycle, etc.).

[0016] The memory resource 220 can be in communication with a processing resource 216. A memory resource 220, as used herein, can include any number of memory components capable of storing instructions that can be executed by processing resource 216. Such memory resource 220 can be a non-transitory CRM or MRM.

Memory resource 220 may be integrated in a single device or distributed across multiple devices. Further, memory resource 220 may be fully or partially integrated in the same device as processing resource 216 or it may be separate but accessible to that device and processing resource 216. Thus, it is noted that the computing device 214 may be implemented on a participant device, on a server device, on a collection of server devices, and/or a combination of the participant device and the server device.

[0017] The memory resource 220 can be in communication with the processing resource 216 via a communication link (e.g., a path) 218. The communication link 218 can be local or remote to a machine (e.g., a computing device) associated with the processing resource 216. Examples of a local communication link 218 can include an electronic bus internal to a machine (e.g., a computing device) where the memory resource 220 is one of volatile, non-volatile, fixed, and/or removable storage medium in communication with the processing resource 216 via the electronic bus.

[0018] A number of modules (e.g., controller module 222) can include CRI that when executed by the processing resource 216 can perform functions. The number of modules (e.g., controller module 222) can be sub-modules of other modules. For example, the controller module 222 and an additional module can be sub-modules and/or contained within the same computing device. In another example, the number of modules (e.g., controller module 222) can comprise individual modules at separate and distinct locations (e.g., CRM, etc.).

[0019] Each of the number of modules (e.g., controller module 222) can include instructions that when executed by the processing resource 216 can function as a corresponding engine as described herein. For example, the controller module 222 can include instructions that when executed by the processing resource 216 can function as the soft-start controller engine 106.

[0020] Figure 3 illustrates an example system 330 for increasing duty cycle consistent with the present disclosure. The system 330 can be utilized to provide a soft- start for a system that utilizes high voltage direct current (HVDC). The system 330 can include a main power source 332. The main power source 332 can be a HVDC power source that provides main power for the system 330. The main power source 332 can be coupled to an input 338 of a system module 334.

[0021] The input 338 of the system module 334 can be coupled to a fuse 340 and a switch 342. The switch 342 can be utilized for reverse polarity protection control. The power supply 346 can direct the received power from the input 338 to a controller 344.

[0022] The controller 344 can include a controller engine 106 as referenced in Figure 1 and/or a controller module 222 as referenced in Figure 2. The controller 344 can be coupled and/or communicatively coupled (e.g., connected to allow for a communication path between the soft-start controller 334 and other devices such as switches 352, 354) to switch 352 (e.g., first switch, main power switch) and switch 354 (e.g., stabilization switch, second switch, back-up power switch). The switch 352 and the switch 354 can each be HVDC switches that when activated (e.g., turned on) can allow HVDC to pass through and when deactivated (e.g., turned off) can prevent HVDC from passing through. The switch 352 and the switch 354 can each be reverse polarity protection semiconductors. For example, the switch 352 and the switch 354 can include diodes to allow current to flow only if the correct polarity is applied.

[0023] As shown in Figure 3, the switch 352 can be coupled to switch 342 and/or the input 338 that is coupled to the main power source 332. That is, the switch 352 is coupled to the main power source 332. In addition, the switch 352 can be coupled to an inductor 356 that is coupled to an output 358 of the module 334 and subsequently coupled to a load 336. Thus, the switch 352 is coupled between the main power source 332 (e.g., a direct current (DC) source input, high voltage direct current (HVDC) source input, etc.) and the load 336 (e.g., a load output, output to the load, etc.). The switch 354 can be coupled to the inductor 356 that is coupled to the output 358 of the module 334 and subsequently coupled to the load 336. In addition, the switch 354 can be coupled to a back-up power source 350. The back-up power source 350 can comprise a HVDC back-up power source such as a plurality of batteries coupled in series. In some examples, the back-up power source 350 can include a total of 64 battery cells in series to provide back-up power of 370 volts (V).

[0024] The controller 344 can activate and/or deactivate the switch 352 to provide a soft-start as described herein. In some examples, the controller 344 can be activated (e.g., turned on) upon a system 330 startup (e.g., start of the load 336, start of the power source 332, etc.). In some examples, the controller 344 can incrementally increase duty cycle percentage over a plurality duty cycles by activating and/or deactivating the switch 352 for each of the plurality of incremental steps. The plurality of incremental steps can include a plurality of incremental duty cycles for the power source 332 to power up from 0 V to the HVDC (e.g., about 400 V, about 370 V, etc.). That is, a complete duty cycle for the power source 332 can include a quantity of time that the power source 332 takes to power up from 0 V to a particular voltage (e.g., 370 V).

[0025] The plurality of incremental steps can be a portion of the complete duty cycle for the power source 332. By splitting the complete duty cycle into a plurality of incremental steps and/or into a plurality of incremental duty cycles, the voltage at the inductor 356 and/or module output 358 can gradually increase as the incremental duty cycles increase from 0 percent to 100 percent of the complete duty cycle over the plurality of incremental steps. The incremental duty cycles prevent an in-rush of current from the main power source 332 as described herein. When the main power source 332 utilizes a single complete duty cycle, there can be an in-rush of current at the load 336 that can damage components of the load 336.

[0026] The controller 344 can activate and deactivate the switch 352 for a number of duty cycles and/or a number of stabilization cycles. For example, the controller 344 can activate switch 352 coupled to the HVDC input 338 for a first incremental duty cycle. The first incremental duty cycle can include a first incremental duty cycle percentage of a complete duty cycle for the power source 332. That is, the first incremental duty cycle can include only a portion of the complete duty cycle for the power source 332 to power up to a HVDC level.

[0027] In addition, the controller 344 can deactivate the switch 352 for a stabilization cycle. The stabilization cycle can include a particular quantity of time where the voltage can be stabilized at the output of the switch 352 and/or at the inductor 356 when the switch 352 is deactivated. The stabilization cycle can prevent destabilization of the voltage or current provided by the power source 332, which can lead to an in-rush of current at the output 358 and/or the load 336.

[0028] Furthermore, the controller 344 can activate the switch 352 for a second incremental duty cycle, wherein the second incremental duty cycle includes a greater duty cycle percentage and/or quantity of time compared to the first incremental duty cycle. That is, the quantity of time that the switch 352 is activated can be greater for the second incremental duty cycle compared to the first incremental duty cycle. The process of activating and deactivating the switch 352 can continue for a plurality of incremental duty cycles to gradually build up the voltage at the output of switch 352.

[0029] The process of activating and deactivating the switch 352 can increase the duty cycle percentage over a plurality of incremental steps for each additional duty cycle and stabilization cycle. For example, the complete duty cycle for the power source 332 can be split into four incremental duty cycles or incremental steps. In this example, the first incremental duty cycle can have a duty cycle percentage of 1 percent, the second incremental duty cycle can have a duty cycle percentage of 2 percent, the third incremental duty cycle can have a duty cycle percentage of 3 percent, and the last incremental duty cycle (100 ^th increment) can have a duty cycle percentage of 100 percent. Thus, the voltage from the power source 332 can build up at the output of switch 352 and/or the input of inductor 356 with the corresponding duty cycle

percentage. The duty cycle percentages and/or incremental voltage increases can be distributed in a number of different ways based on specifications of the system 330. In some examples, the controller 344 can incrementally increase a DC voltage to the load from about 0 volts (V) to about 400 V.

[0030] In some examples, the system 330 can provide operation for hot-plug ability of the HVDC module in an already energized DC Bus. Thus far the apparatus described is that of an already connected power module or set of modules, after which the input source can be energized which can lead to soft-start and hence complete start-up.

[0031] When a module is connected to an already energized DC Bus (e.g., hot plug), it will detect the input HVDC and the auxiliary power supply can be activated (e.g., turned on). In these examples, the soft-start process can initiate and continue as described herein. Thus, the system 330 is able to carry out a soft-start in a hot plug situation. In some examples, the battery series of the back-up power source 350 can also have a soft-start method of its own. In some examples, the soft-start method of the back-up power source 350 can include turning on converters progressively. The soft- start method of the back-up power source 350 can be different because the

freewheeling diode of the switch 348 can be forward biased with respect to the battery HVDC output. The soft-start method of the back-up power source 350 can prevent instantaneous activation and current surge from the back-up power source 350, thereby protecting it, and ensuring a safe system

[0032] The system 330 can provide a back-up solution for HVDC systems by allowing for safe starting in various conditions and environments. As described herein, the system 330 provides a soft-start to prevent an in-rush of current to be applied to the load 336. The in-rush of current can cause damage to the components of the load 336. In addition, the system 330 can also prevent an in-rush of current to the back-up power supply 350, which could potentially damage components of the back-up power supply 350.

[0033] Figure 4 illustrates a flow chart of an example of a method 460 for increasing duty cycle consistent with the present disclosure. The method 460 can be implemented by a controller (e.g., engine 106 as referenced in Figure 1 , controller module 222 as referenced in Figure 2, controller 344 as referenced in Figure 3, soft- start controller, etc.) in a system (e.g., system 330, system module 334, etc.).

[0034] At 462, the method 460 can include activating a first high voltage direct current (HVDC) switch coupled to a HVDC input and an inductor for a first portion of a duty cycle, wherein the inductor is coupled to a load. In some examples, the first HVDC switch can comprise a reverse polarity protection semiconductor. As described herein, activating (e.g., turning on) the first HVDC switch can include allowing current to pass through the first HVDC switch and deactivating (e.g., turning off) the second HVDC switch can include not allowing current to pass through the second HVDC switch.

[0035] At 464, the method 460 can include deactivating the first HVDC switch for a stabilization cycle to stabilize voltage between the first HVDC switch and the inductor when the first HVDC switch is deactivated. In some examples, the stabilization cycle includes stabilizing voltage at a node between the first HVDC switch and the second HVDC switch. The node between the first HVDC switch and the second HVDC switch can be a point where a connection meets prior to being coupled to the inductor. For example, the inductor can be coupled to a single point that is also coupled to the first HVDC switch and the second HVDC switch. In this example, the single point is the node.

[0036] At 466, the method 460 can include activating the first HVDC switch for a second portion of the duty cycle, wherein the second portion of the duty cycle includes a greater quantity of time than the first portion of the duty cycle. In some examples, a complete duty cycle that is not separated into a plurality of duty cycle portions can damage a load. That is, the HVDC input damages the load during a complete duty cycle.

[0037] As used herein, "logic" is an alternative or additional processing resource to perform a particular action and/or function, etc., described herein, which includes hardware, e.g., various forms of transistor logic, application specific integrated circuits (ASICs), etc., as opposed to computer executable instructions, e.g., software firmware, etc., stored in memory and executable by a processor. Further, as used herein, "a" or "a number of something can refer to one or more such things. For example, "a number of widgets" can refer to one or more widgets.

[0038] The above specification, examples and data provide a description of the method and applications, and use of the system and method of the present disclosure. Since many examples can be made without departing from the spirit and scope of the system and method of the present disclosure, this specification merely sets forth some of the many possible example configurations and implementations.