Power supply system

Abstract

A power supply system includes an energy storage system having a rechargeable energy storage element and a converter connected to the rechargeable energy storage element and configured to be connected to a bus such that the energy storage system is connected in parallel with a load and a main power supply system. The energy storage system can cooperate with the main power supply system to supply power to the load, and the energy storage system and the main power supply system are both configured as voltage sources with corresponding droop functions. The system may include a control circuit configured to monitor the bus voltage and control the converter to charge or discharge the rechargeable energy storage element according to the bus voltage.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 581,320, filed on September 8, 2023, the disclosure of which is hereby incorporated by reference in its entirety for all contents and purposes taught thereby. Technical Field

[0003] The present disclosure generally relates to power supply systems and control methods to address peak loads, such as in facilities with unstable energy sources and / or highly dynamic loads. Background Art

[0004] Electrically powered devices require ever-increasing amounts of energy to maintain functionality. This creates a problem where power demand approaches the maximum architectural supply limit, while the external line input power cannot keep up with the dynamic demand. Electrical systems used in high dynamic load environments consist of two main components, the energy source or source and the load. Each component includes many different types, and it is important that the total amount of power available from the source and the total amount of power required by the load are balanced to avoid bus voltage fluctuations or sags that can cause protection events or even damage to equipment on either side. Summary of the invention

[0005] To overcome the above problems, the present disclosure provides a power supply system, comprising: an energy storage system, the energy storage system comprising: a rechargeable energy storage element; and a converter, the converter is connected to the rechargeable energy storage element and is configured to be connected to a bus, so that the energy storage system is connected in parallel with a load and a main power supply system, the energy storage system cooperates with the main power supply system to supply power to the load, and the energy storage system and the main power supply system are both configured as voltage sources with corresponding droop functions; and a control circuit, the control circuit is configured to: monitor the bus voltage; and control the converter to charge or discharge the rechargeable energy storage element according to the bus voltage.

[0006] The present disclosure also provides another power supply system, comprising: a bus; a main power supply system connected to the bus and configured as a voltage source with a droop function; a rechargeable energy storage system connected to the bus and configured as a voltage source with a droop function, the rechargeable energy storage system comprising a rechargeable energy storage element and a converter connected between the rechargeable energy storage element and the bus; and a control circuit, wherein the control circuit is configured to: monitor the bus voltage; and control the converter to charge or discharge the rechargeable energy storage element according to the bus voltage.

[0007] The present disclosure also provides another power supply system, comprising: a main power supply system having a voltage source output characteristic with a droop function; a bus configured to be connected to a load; a rechargeable energy storage system having a voltage source output characteristic with a droop function connected to the bus; and a control circuit, wherein the control circuit is configured to: monitor the bus voltage; and control the rechargeable energy storage system to charge or discharge the bus based on the bus voltage, wherein the output characteristics of the main power supply system and the output characteristics of the rechargeable energy storage system enable the main power supply system and the rechargeable energy storage system to adjust the bus voltage independently of each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 A block diagram of a related art power supply system is shown.

[0009] Figure 2 A block diagram of a power supply system according to at least one example embodiment is shown.

[0010] Figure 3 A power supply system including two unidirectional DC / DC converters according to at least one example embodiment is shown.

[0011] Figure 4 A power supply system including a bidirectional DC / DC converter according to at least one example embodiment is shown.

[0012] Figure 5 A power supply system including a plurality of interleaved bidirectional DC / DC converters having 1 to N phases according to at least one example embodiment is shown.

[0013] Figure 6 An example of a single capacitor direct current internal resistance (DCIR) voltage drop caused by a load current occurring within a single capacitor included in a series / parallel connected capacitor-based energy storage element is shown according to at least one example embodiment.

[0014] Figure 7 A parallel storage system having a capacitive energy storage system (CESS) and a primary power system (PSS) each configured as a voltage source is shown according to at least one example embodiment.

[0015] Figure 8 Output characteristics of a main power system controlled as a voltage source having a droop function according to at least one example embodiment are shown.

[0016] Fig. 9 Bidirectional output characteristics of a capacitive energy storage system (CESS) controlled as a voltage source with a droop function according to at least one example embodiment are shown.

[0017] Fig.10 A block diagram of a control system for a power converter having a CESS to achieve bidirectional charging / discharging behavior is shown according to at least one example embodiment.

[0018] Fig.11 The use of at least one example embodiment is shown Fig.10 The control mechanism ensures fast and smooth charging and discharging transitions.

[0019] Fig.12 A block diagram of components for implementing a SOC regulation mechanism of a CESS is shown according to at least one example embodiment.

[0020] Fig.13A and Fig. 13B According to at least one example embodiment, Fig.12 The control method implemented by the components shown in .

[0021] Fig.14 Waveforms of a CESS passive filtering scheme according to at least one example embodiment are shown.

[0022] Fig.15 A block diagram including components for dynamic current mitigation (DCM) control is shown according to at least one example embodiment.

[0023] Fig.16A According to at least one example embodiment, Fig.15 The DCM component is used to simulate load step / step conditions.

[0024] Fig. 16B According to at least one example embodiment, the use of Fig.15 Simulation of frequent pulse loads with DCM components.

[0025] Fig. 16C The results show that when two CESSs with different SOC and different capacitance are used, Fig.15 Simulation of the DCM components.

[0026] Fig.17 A block diagram of components for dynamic SOC regulation control according to at least one example embodiment is shown.

[0027] Fig.18A A waveform comparison of a CESS with a DSR control scheme and a system without a CESS under a load boost condition according to at least one example embodiment is shown.

[0028] Fig.18B A waveform comparison of a CESS with a DSR control scheme and a system without a CESS under a load step-down condition according to at least one example embodiment is shown.

[0029] Fig. 18C FIG. 1 shows a system having a CESS compared to a system without a CESS during a pulsed dynamic load according to at least one example embodiment. AC The ripple is quite small. DETAILED DESCRIPTION

[0030] The smooth balance of total power available from the power supply and total power required by the load is now vulnerable to the unpredictable characteristics of new technologies, such as renewable energy or the highly dynamic load demands of artificial intelligence (AI) computing workloads in computer data centers. In the case of the highly dynamic loads required by AI workloads, their synchronous nature acting at the level of individual server racks is amplified by the number of server racks in the data center. In these cases, power consumption throughout the data center rises and falls faster than the utility can respond, and voltage sags and frequency changes can occur at the utility level, tripping overcurrent protection devices in the data center itself.

[0031] In related art installations, users typically install an AC uninterruptible power supply (AC UPS) system as a buffer between the energy source or utility 14 and the load 30, such as Figure 1 As shown, the system 10 also includes a rectifier 18, an energy storage system 22, and an inverter 26. The energy storage system 22 has energy storage components inside, such as different types of batteries. When the dynamic load demand of the load 30 is greater than the capacity of the energy source 14, the energy storage component 22 in the UPS will begin to discharge, and conversely, when the load peak dissipates and the load drops below the level at which the energy source 14 has available capacity, the energy storage component 22 will begin to charge. Since the energy storage system 22 is cascaded in the power delivery path between the utility 14 and the load 30, the AC UPS system 10 lacks flexibility and redundancy.

[0032] Advantages of the embodiments of the present disclosure include at least the following: reduced imbalance in input / output power amounts between energy sources and load requirements; improved scalability and flexibility compared to AC UPS; improved current control capabilities of direct current (DC) UPS systems; extremely high cycle times; and fast charging time (return to ready state).

[0033] Figure 2A power supply system 100 is shown according to at least one example embodiment. The system 100 includes a primary power supply system 104 (also referred to herein as a "PSS"), which includes a power source 106 (e.g., a utility) and a rectifying component 108, a capacitive energy storage system (CESS) 112, which includes a chargeable capacitive energy storage element 116 (also referred to herein as an "ESS"), and a converter 120 (e.g., a DC / DC converter). The PSS 104 and the CESS 112 are connected in parallel to a load 128 via an appropriate high current power bus 124.

[0034] DC UPS applications having constituent elements similar to 112 in the proposed system 100 have higher reliability and efficiency than conventional AC UPS systems and have been widely adopted by data centers to manage backup functions during AC power outages. In addition, the CESS 112 in the proposed system 100 also has advantages over typical DC UPS systems that use batteries as energy storage systems (e.g., lithium batteries), which are recognized for their high energy density and effectiveness in backup applications. However, batteries have limited cycle life (typically less than 1,000 cycles) and asymmetric charge / discharge performance (with up to 20 times deviation between charge and discharge current capabilities), which makes batteries unsuitable for the fast and frequent charge / discharge requirements of AI workloads. AI workloads are typically the type of applications that can be referred to as having power filtering requirements. In addition, there are no dedicated control algorithms or symmetrical power delivery converters designed specifically for power filtering applications. As Figure 2 As shown, the exemplary embodiment proposes using capacitive rechargeable energy storage elements and introduces a new control mechanism to effectively manage power filtering of the illustrated CESS 112. The system 100 can be used to deliver power to the load 128 when system demand increases faster than the utility 106 can respond.

[0035] The energy storage element 116 may include a capacitance source, such as a series and parallel connection of capacitors (e.g., multiple groups of capacitors, each group of capacitors connected in parallel, and each group of capacitors connected in series). The capacitors in the energy storage element 116 may include rechargeable lithium ion capacitors and / or electric double layer (EDL) supercapacitors, which have the advantages of high cycle life (millions of cycles), high end voltage (2.6–3.8V), high volume energy density (26Wh / l), and extraordinary bidirectional power density (15kW / l) of the capacitors. EDL capacitors and lithium ion capacitors are particularly suitable for systems with very high power, fast dynamic load requirements and continuous cycling. The terms capacitor, supercapacitor, ultracapacitor, electric double layer capacitor (EDLC), electric double layer (EDL) capacitor, EDL supercapacitor, etc. are used interchangeably to describe rechargeable charge storage elements. For those skilled in the art, there are technical differences between these charge storage elements related to energy delivery performance, operating voltage, and energy storage capacity. It is understood that the series and parallel configuration of lithium capacitors or EDL (electric double layer) supercapacitors is to meet the energy storage requirements of the application, and also to meet the DCIR (direct current internal resistance) limitations imposed by the input voltage range of the DC-DC converter used when the capacitor current reaches the maximum level. In addition, the capacitor has a symmetrical charging and discharging characteristic, which means that the capacitor charges as fast as it discharges.

[0036] In some examples, the energy storage element 116 may additionally or alternatively include a battery. However, the advantages of a capacitor-based power source are threefold: the ability to charge and discharge for millions of cycles, relatively high power output capability, and the ability to charge and discharge at equal rates. Regardless of the exact composition of the energy storage element 116, the energy storage element 116 has high power density, small size, and extremely high cycle life to meet the technical requirements of the application.

[0037] As described in more detail herein, a CESS 112 is proposed to address the imbalance between energy input / output power and load requirements. The system includes a capacitive energy storage element, a control circuit, and a power flow control method of a DC-DC converter.

[0038] Embodiments of the present disclosure include using lithium capacitors or EDL supercapacitors as energy storage elements 116 in a high power, high density energy delivery system (referred to herein as CESS 112), and control algorithms and architectures for achieving seamless transitions when a power source or utility line input reaches a power output or instantaneous power limit.

[0039] Although not explicitly shown, it should be understood that system 100 may include additional hardware and software for controlling PSS 104 and CESS 112, such as components for measuring current and voltage at various points within the system (e.g., voltage and current of ESS 116, voltage and current on bus 124, voltage and current of PSS 104, etc.).

[0040] CESS112 can have Figure 3 , 4 and one of the structures shown in 5, respectively, CESS112a, 112b and 112c. It can be understood that Figure 3-5 The energy storage elements 116 shown in the figure may include a series and parallel configuration of lithium capacitors or EDL supercapacitors configured to meet the storage energy requirements of the application and also meet the DCIR limitations imposed by the input voltage range of the DC-DC converter used when the current through the capacitor is at its maximum level. It can be further understood that each CESS 112a to 112c shows a different configuration of the converter 120. In more detail, Figure 3 A CESS 112 a is shown having a converter 120 a that includes two unidirectional DC / DC converters—one converter for discharging the energy storage element 116 and another converter for charging the energy storage element 116 . Figure 4 A CESS 112b is shown having a converter 120b comprising a single bidirectional DC / DC converter. Figure 5 A CESS 112c having a converter 120c is shown, which is composed of a plurality of interleaved bidirectional DC / DC converters having 1 to N phases. It is understood that Figure 3-5 Further shown is a control system 118 for controlling the energy storage element 116 and / or the converters 120a-120c. Various aspects of the control system 118 and its functionality will be described in greater detail below. In general, however, the control system 118 may include processing and / or drive capabilities.

[0041] As described herein, systems and methods according to example embodiments solve various problems including, but not limited to: an imbalance in input / output power amounts between energy sources and load requirements; low scalability and flexibility; current control capability; low cycle times of energy storage devices, and slow charging times of energy storage devices.

[0042] The example embodiments are discussed in more detail below with reference to three sections: 1) the capacitive energy storage element electrical architecture, which explains the voltage range of individual capacitors and capacitor matrices as well as some important characteristics; 2) the control system of the energy storage element 116; and 3) the control scheme of the bidirectional DC-DC converter and the main objectives of the proposed application.

[0043] 1. ESS electrical architecture

[0044] The energy storage element 116 is designed to have a voltage that matches the input of the DC-DC converter 120. For example, the converter 120 can be a DC boost circuit with an output of 48V and an input range of 30V to 46V. The range can cover higher or lower voltages, but the efficiency will be reduced. The individual capacitors of the energy storage element 116 can be combined so that the sum of the voltage operating ranges of the series capacitors matches and is located at the center of the DC converter input range. For example, a lithium capacitor can be charged to 3.8V. When 12 such lithium capacitor arrays are electrically connected in series, the maximum voltage of each capacitor when fully charged is 45.6V, and the voltage of each capacitor is 3.8V, which is the upper limit of the voltage of each capacitor, but still within the range of 30V-46V of the above-mentioned DC-DC (boost) converter 120 example.

[0045] The capacitors of the energy storage element 116 can be combined in parallel to increase the total energy of the energy storage element 116. Capacitors can be characterized by the number of joules of energy available to the system. Increasing the total energy by connecting individual capacitors in parallel will increase the available energy before connecting the parallel elements in series. The total energy storage (in joules) of the capacitors in this series and parallel configuration, with the capacitance value of each capacitor being C element , as shown below

[0046] As shown in formula 1.

[0047]

[0048] Formula 1 - Formula for calculating the sum of the joules of all energy storage elements, where P is the number of parallel capacitors, S is the number of parallel capacitor blocks connected in series, at the maximum charge voltage (V max ) and the minimum discharge voltage (Vmin).

[0049] In some examples, the total energy (in joules) of the system can also be increased by combining multiple capacitors connected in series and / or parallel with multiple batteries connected in series and / or parallel. In this case, the voltage of the multiple capacitors is maintained higher than the voltage of the multiple batteries, so that the capacitors will discharge before the batteries, thereby reducing the discharge frequency and depth of the batteries in the system. When the capacitors are close to energy depletion, the batteries can be used to maintain the system voltage, which may extend the discharge time. In this case, the battery has a minimum discharge depth, thereby extending the cycle life.

[0050] Capacitors such as lithium capacitors and EDL supercapacitors have a measurable DC internal resistance (DCIR) that can be tracked. DCIR can be calculated by measuring the voltage drop (V2-V1) from no load to full load (I2-I1), according to DCIR = ΔV / ΔI, where I is the current (amperes) and V is the voltage (volts). Figure 6 An example of a DCIR voltage drop based on load is shown. As shown, when a load is applied, the DCIR will cause a voltage drop across the capacitor stack. This shift effectively shifts the output voltage curve under load to a lower terminal voltage when current is present - the greater the current, the greater the voltage shift. This shift must be considered when considering the appropriate number of series capacitors compared to the operating voltage at the DC-DC converter 120 input. The system equivalent DCIR (DCIR eq ) by scaling the DCIR of a single energy supply element by the number of series and parallel connections in the entire system. This is expressed in Equation 2 below.

[0051]

[0052] Equation 2 - The formula used to calculate the equivalent system DCIR related to the DCIR of a single energy storage element, scaled by the number of series (S) and parallel (P) energy storage elements.

[0053] 2. Energy storage element control architecture

[0054] Capacitive energy systems as described herein require continuous active monitoring and balancing of individual capacitor voltages during operation. When battery cells are replaced by capacitors, the system described in U.S. Patent 11,121,415 "Series Battery Cell Monitoring System" (incorporated herein by reference) is well suited for this task and can constitute Figure 4 At least a portion of the energy storage system controller 118 in the system. The method described in the patent has the advantage of coulomb counting, and the current capacitance value of each capacitor in the system can be determined on-site at any point in its service life, thereby facilitating comparison over time to measure the aging of the capacitor. The method also implements active cycle counting.

[0055] 3. Bidirectional power flow control architecture

[0056] Figure 7 1 shows a parallel energy storage system, where CESS 112 has a capacitive energy storage element 116, and a current source power supply system (PSS) 104. In other words, PSS 104 can be configured as a voltage V PSS_0A The voltage source is due to the resistance R PSS and has a resistance drop, and the CESS112 can be configured as a voltage V CESS_0A The voltage source is due to the resistance RCESS while having a resistance drop.

[0057] The objectives of the proposed power flow control architecture are: (1) to achieve bus voltage regulation by keeping V BUS at an appropriate level; and (2) to keep the CESS away from the system breakpoints, in other words, to avoid the state where the CESS is fully charged / discharged (0% < CESS state of charge (SOC) < 100%); and (3) AC harmonic filtering: filtering the dynamic power flow on the PSS side.

[0058] To achieve objective #1 (keeping V BUS at an appropriate level), the output characteristics of PSS104 and CESS112 represent voltage sources, which means that each system can regulate the bus voltage V BUS , without the help of other systems. For example, the output characteristics of PSS104 are controlled to be a voltage source with an output droop function, R PSS = (V PSS_0A – V PSS_MIN ) / (I PSS_MAX ), as Figure 8 shown. R PSS is the equivalent output resistance of PSS104, V PSS_0A and V PSS_MIN are the values that limit the bus regulation range, where V PSS_0A is the voltage of PSS104 at zero load, and V PSS_MIN is the voltage of PSS104 at maximum load. At the same time, I PSS_MAX is the maximum output current of PSS104 (e.g., at maximum load). The characteristic of CESS112 is to compensate for the power of the source / load demand and regulate the DC bus voltage. In at least one embodiment, the output characteristics of CESS112 are controlled to be a voltage source with a droop function (R CESS = (V CESS_MAX – V CESS_MIN ) / (2 * ΔI CESS_MAX )) as Fig. 9 shown, where R CESS is the equivalent output resistance of CESS112, V CESS_MAX and V CESS_MIN represent the maximum and minimum output bus voltage boundaries of CESS112 when operating at maximum load under charging or discharging conditions. At the same time, I CESS_MAX is the maximum output current of CESS112 (e.g., at maximum load).

[0059] Continuing to refer to Fig. 9 , for the output characteristics of CESS112, if the voltage V of bus 124 BUS(e.g., real-time bus voltage) is equal to the voltage V of CESS 112 CESS_0A (Where V CESS_0A is the zero current voltage set point of CESS112, which varies according to system design), there is neither discharge behavior nor charge behavior. However, when V BUS Greater than V CESS_0A CESS112 starts charging, and when V BUS Less than V CESS_0A In other words, if V BUS -V CESS_0A is negative, the CESS 112 releases energy to the DC bus 124 through the power converter 120. BUS -V CESS_0A If is positive, the energy storage element 116 is charged from the DC bus 124 through the power converter 120. Fig. 9 It can be seen that the amount of charging and discharging current depends on V BUS and V CESS_0A For example, with V BUS and V CESS_0A As the difference between the values ​​increases, the amount of charging and discharging current from the CESS 112 increases.

[0060] Fig.10 FIG. 4 shows a block diagram for realizing the above-mentioned bidirectional charging / discharging behavior. Fig.11 As shown, using Fig.10 The control mechanism of the charging and discharging switch is fast and smooth. In the simulation results, V CESS_0A The bus voltage is 50V, and the bus voltage is boosted from 49V to 51V within 1ms, and the current flow direction is immediately changed from discharge to charge. Fig.10 As shown, various components shown may be included in the control circuit 200 or correspond to the control circuit 200. In the example shown, the control circuit 200 includes a drive logic 204 for controlling the control signal V output by the control loop compensator 208. CONT Generates a gate drive signal for driving converter 120, where V CONT is generated based on the output of the summing circuit 212. The compensator 208 may include a circuit that converts the input signal into an appropriate control signal (e.g., V CONT ) or other signals suitable for digestion by downstream circuits. For example, compensator 208 can process V REF and (k V *V BUS +k I *I CESS ) to generate V CONTThe compensator 208 may be implemented by circuit (ie, hardware) or firmware coding. As shown in the figure, the summing circuit 212 receives and operates the reference voltage signal V REF and signals from circuits 216 and 220. The output of circuit 216 is based on V measured on bus 124. BUS , and the output of circuit 220 is based on I measured on bus 124 CESS Each circuit 216 and 220 can input V according to its own weight K BUS or I CESS Converted to an analog signal. The following formula 3 shows that V REF 、V BUS , K value and I CESS The relationship between.

[0061]

[0062] SOC Regulation Control (SRC)

[0063] To achieve goal #2 (keep the CESS away from the system breakpoint), the CESS 112 needs to maintain its energy storage level (i.e., SOC or capacitor voltage) within a certain appropriate range (e.g., 2.2V-3.8V for a single lithium capacitor). In at least one embodiment, the CESS 112 adjusts the capacitor voltage to adjust the SOC, thereby keeping the system away from the breakpoint. Fig.12 A block diagram showing components for implementing a SOC regulation mechanism is shown, Fig.13A and 13B The control method implemented by the control circuit 304 is shown.

[0064] refer to Figure 12-13B , the control circuit 304 includes some Fig.10 The same circuit is shown, where the drive logic 204 is used to drive the converter 120, compensator 208, summing circuit 212 and feedback block 216 of the CESS stage 112. The control circuit 304 also includes a SOC regulation control circuit, which includes a summing circuit 340 and a compensator 344. It can be understood that the summing circuit 212 receives and operates on the voltage value ΔV shown REF 、V REF and the output of feedback block 216 / 220, which outputs a signal based on V BUS and I CESS The signal (with Fig.10 216 and 220 in the same or similar manner). As shown in the figure, ΔV REF is the output of compensator 344, whose input comes from summing circuit 340, which determines the real-time capacitor voltage V CAP_RT and the target value V CAP_TGIt can be understood that the function provided by the compensator shown is similar to that of the reference Fig.10 The compensator 208 has the same or similar functions as described above. The drive logic 328, the compensator 332, the summing circuit 336, and the feedback block 348 may be the same as or perform the same functions as the drive logic 204, the compensator 208, the summing circuit 212, and the circuits 216 / 220, respectively.

[0065] refer to Fig.13A If the system load suddenly decreases and the bus voltage increases, CESS112 will start charging (t=T1). CESS( When T1) is less than 0A, the real-time charging state SOC RT will start to increase (here, SOC RT and SOC TG With V CAP_RT and V CAP_TG Related, can be directly related (ie, SOC RT Yes V CAP_RT , SOC TG Yes V CAP_TG ), or indirectly (i.e., SOC RT From V CAP_RT Derived or inferred, SOC TG From V CAP_TG Then, when SOC RT Greater than the target state of charge SOC TG When ΔV REF will increase, and the duration of the change is determined by the compensation parameters (e.g., K value). REF The V of CESS112 increases accordingly. CESS _ 0A The zero current set point is increased to reduce the discharge current (I CESS (T2)>0A) introduces bus 124 until SOC RT Equal to SOC TG .

[0066] refer to Fig. 13B If the system load suddenly increases and the bus voltage drops, CESS112 will start to discharge (t=T1). As the discharge process proceeds, when I CESS When (T1) is greater than 0A, SOC RT will begin to decrease. When SOC RT Greater than SOC TG When ΔV REF The duration of the change is determined by the compensation parameters (such as K value). REF The corresponding drop, zero current voltage set point V CESS_0A decreases accordingly to reduce the charging current (I CESS (T2) < 0A) introduces the bus until SOC RT Equal to SOC TG .

[0067] To achieve goal #3 (filtering the dynamic power flow on the PSS side), there are two methods / circuit examples to achieve this goal, passive filtering and active filtering are discussed below.

[0068] Passive filtering via droop

[0069] Given that Figure 8 and Fig. 9 Given the nature of the output characteristics of the PSS 104 and CESS 112 shown in FIG, the dynamic current sharing ratio between the two systems can be determined by Equation 4 to achieve passive filtering through droop.

[0070] ΔI CESS :ΔI PSS =R PSS :R CESS

[0071] Formula 4 - Dynamic current ratio between PSS and CESS through droop

[0072] The advantages of this method are: (1) the control scheme is simple and reliable; (2) it is noise-resistant; and (3) no data or signal transmission is required between the PSS and CESS. Fig.14 The system verification test results of the CESS passive filtering solution are shown, where SOC TG Set to 50% for simulation. Channel 1 is the CESS output current I CESS , channel 2 is the input AC current I of the PSS AC , Channel 3 is the bus voltage V BUS , channel 4 is the load current I LOAD As shown in the figure, I LOAD Frequent rise and fall, I AC Relatively stable, while I CESS Then it follows the sudden change behavior of the dynamic load current. It can be seen that at the moment of load change, V BUS There are virtually no voltage spikes or dips on the

[0073] By adjusting the PSS current information (I PSS_INFO ) for active filtering

[0074] The second method involves CESS112 actively regulating the implicit PSS104 output current information I PSS_INFO There are two signals with I PSS_INFO The relevant public signal, that is, I SHARE and VBUS I SHARE is an analog signal representing the PSS output current level and may correspond to a common bus signal for current sharing functionality between power supplies connected to the common bus. Additionally or alternatively, V BUS Can be used as I PSS_INFO basis, because Figure 8 As shown, due to the droop curve, the PSS output voltage is negatively proportional to its output current. The two active filtering control schemes, Dynamic Current Mitigation (DCM) control and Dynamic SOC Regulation (DSR) control, are discussed in more detail below.

[0075] Dynamic Current Mitigation (DCM) Control

[0076] The core idea of ​​the proposed DCM control is to monitor I PSS_INFO And by comparing the real-time value with the average value, its change slope is mitigated. When the real-time value is greater than the average value, it means that the load increases, and the CESS112 output voltage will increase to mitigate the output current change slope of the PSS104.

[0077] The block diagram of the proposed DCM controller is shown in Fig.15 As shown, I PSS_INFO The signal represents the PSS104 output current information fed into the dynamic current mitigation (DCM) control loop. Fig.15 As shown, the control circuit 400 includes some reference Fig.10 and 12 For DCM control, the control circuit 400 includes an averaging circuit 404 to obtain I PSS_INFO The average value changes over time, and the summing circuit 408 determines the output of the averaging circuit 404 and I PSS_INFO The output of the summing circuit 408 reaches the compensator 412, which generates a voltage for dynamic current mitigation V DCM The control signal is used to input to the summing circuit 416. The summing circuit 416 receives and processes the inputs from the compensators 412 and 344 and the CESS112V CESS_OFST The zero current offset point.

[0078] As shown in the figure, in order to achieve the above goal #2, Fig.15 The CESS 112 in the embodiment also includes a block for SOC regulation, which operates in the same manner as the reference Fig.12 The same as above, where V CAP_TG is the target value fixed for regulation, V CAP_RT is the real-time value of the capacitor voltage.

[0079] The reaction time of the DCM controller occurs within a few microseconds (eg, five microseconds), so the CESS 112 can provide or absorb energy caused by the dynamic load. On the other hand, the reaction time of the SOC regulation loop is about a few seconds to tens of seconds.

[0080] Fig.16A Shows Fig.15 The circuit simulation results of the load step-up / step-down conditions of the DCM control block proposed in FIG. 1 show the load current I_LOAD, PSS output current I_PSS, capacitor voltage V_CAP, CESS112 output offset voltage (CESS_OFST and V in the previous paragraph) CESS_0A The same) and bus voltage VBUS waveform. In this example, the SOC regulation target of V_CAP is 45.0V. Fig.16A It can be seen that the load boost occurs at 25 seconds, and due to the action of the DCM controller, CESS_OFST immediately boosts and mitigates the slope change of the PSS output current. As shown in the figure, the capacitor voltage begins to decrease at about the same time. Then, CESS_OSFT begins to gradually decrease, and I_PSS is correspondingly increased to a level higher than I_LOAD through the SOC control block to charge CESS to the regulation target (e.g. 45V). As shown in the upper part of the figure, in the steady state, I_PSS is equal to I_LOAD.

[0081] like Fig.16A As shown in the figure, when the load decreases at 75s, CESS_OFST immediately decreases through the DCM controller and eases the slope change of the PSS output current, while the capacitor voltage starts to rise at about the same time. Then, CESS_OSFT begins to increase gradually, and I_PSS is correspondingly reduced to a level below I_LOAD through the SOC control block to discharge CESS to the regulation target. As shown in the upper part of the figure, in the steady state, I_PSS is equal to I_LOAD.

[0082] Fig. 16B Figure 2 shows the simulation results of a circuit with frequent pulse loads. Fig. 16B As shown, I_PSS is almost constant at 60A current ripple, while the peak of the pulse load variation is 380A. The average SOC value in this example is still 45.0V.

[0083] Fig. 16CThe circuit simulation results of two CESS112 with different SOC and capacitance under frequent dynamic load are shown. The capacitance of CAP1 is 500F, and the capacitance of CAP2 is 400F; the initial value of V_CAP1 is 44.0V, and the initial value of V_CAP2 is 47.0V. After several dynamic load cycles, I_PSS is equivalent to the average value of I_LOAD, and the average value of V_CAP1 and V_CAP2 is equivalent to 45.0V.

[0084] according to Figures 16A-16C From the simulation results in FIG. 1 , it is apparent that the DCM controller according to the exemplary embodiment successfully mitigates the slew rate variation of the PSS output current under load ramp-up and ramp-down conditions, while the CESS also successfully regulates the capacitor voltage back to the reference target under steady-state conditions.

[0085] Dynamic SOC Regulation (DSR) control

[0086] The second solution for active filtering consists of an I-based PSS_INFO Adjust the SOC target value so that I PSS_INFO The higher the value, the lower the SOC adjustment target. The DSR control block diagram is as follows Fig.17 In more detail, Fig.17 A control circuit 500 is shown, which includes some Fig.10 The same components are not described here for the sake of brevity. The control circuit 500 also includes a conversion circuit 504 for converting I PSS_INFO Converted to capacitor voltage target value V CAP_TG , the summing circuit 508 converts the converted V CAP_TG and the real-time value of the capacitor voltage V CAP_RT The compensator 512 receives the output of the summing circuit 508 and generates a signal ΔV REF , the signal ΔV REF Input to ΔV REF and V CESS_OFST A summing circuit 516 is used to perform the operation.

[0087] In operation, such as during load step-up, I PSS_INFO Trying to increase and decrease V in the DSR control loop CAP_TG , CESS zero current output voltage set point V CESS_0A The CESS112 will increase accordingly and release energy to the bus 124, thereby reducing the slope change of the PSS output current. CAP_TG and V CAP_RT The error between V CESS_0A decreases accordingly, so the PSS output current I PSS and I PSS_INFO Increase. Understandably, IPSS Becomes equivalent to I LOAD , and the V of CESS112 CAP_RT will become stable with I PSS_INFO The corresponding value.

[0088] When the load voltage is reduced, I PSS_INFO Intended to reduce and increase V in the DSR control loop CAP_REF , the zero current output voltage set point of CESS112 is V CESS_0A The CESS 112 will then decrease and absorb energy from the bus 124, thereby alleviating the change in the slope of the PSS output current. CAP_TG With V CAP_RT The error between V CESS_0A As a result, the PSS output current I PSS and I PSS_INFO I PSS Become with I LOAD Equal, CESS121's V CAP_RT will become stable with I PSS_INFO The corresponding value.

[0089] Fig.18A The waveform comparison between the CESS 112 with DSR control scheme and the system without CESS is shown. Channel 1 is the bus voltage V BUS , channel 2 is the real-time capacitor voltage V CAP_RT , channel 3 is the load current I LOAD , Channel 4 is the PSS104AC input current I AC .according to Fig.18A , under load step-up condition, the AC input current of the PSS 104 gradually increases to a target value, while a system without a CESS experiences a sudden change in the AC input current of the PSS 104 . Fig.18B The same relationship is shown for load step-down conditions. Finally, Fig. 18C shows that during pulse-type dynamic loads, the I with CESS112 is reduced compared to the system without CESS112. AC The ripple is quite small.

[0090] In view of the foregoing, it should be appreciated that systems and methods according to example embodiments provide at least the following advantages: symmetrical charging and discharging capabilities; high power density; ability to achieve extremely high cycle times; faster charging and discharging rates than other technologies; high flexibility; high scalability; fast and smooth transitions between charging and discharging behaviors; high robustness and stability of DC bus voltage regulation; inherent smoothing of utility input current transients; and highly robust power flow management that avoids CESS breakpoints.

[0091] Elements of the system described herein include a voltage source PSS (power supply system) with a voltage drop, a voltage source CESS (capacitive energy storage system) with a voltage drop, a CESS including a combination of series and parallel lithium or EDL supercapacitors or series and parallel capacitor arrays and multiple series and parallel batteries. Example embodiments also provide a control algorithm for the CESS, which coordinates with the control mechanism of the PSS to achieve the following functions: reducing the slope of the PSS output power change, reducing power line harmonics in the utility input line current, and fast and smooth bidirectional power flow of the combined power system. Example embodiments also provide a bidirectional power flow control architecture that describes the output characteristics of the PSS and CESS and their interaction, as well as a control algorithm for a bidirectional DC-DC converter of the CESS to achieve instantaneous power flow direction change. Advantages of the systems and methods described herein include symmetrical charge and discharge capabilities, high power density, high cycle counts, faster charge and discharge rates than other technologies, high flexibility, high scalability, fast and smooth transitions between charge and discharge behaviors, high robustness and stability of DC bus voltage regulation, inherent smoothing of utility input current transients, highly robust power flow management to avoid CESS breakpoints, and / or adaptability to any PSS without any additional PSS system parameter modifications.

[0092] In view of the above, it should be appreciated that the example embodiments are directed to a power system 100 that includes an energy storage system 112 that includes a rechargeable energy storage element 116 and a converter 120 connected to the rechargeable energy storage element and configured to be connected to a bus 124 so that the energy storage system is connected in parallel with a load 128 and a main power system 104. In at least one embodiment, the energy storage system cooperates with the main power system to supply power to the load, wherein the energy storage system and the main power system are both configured as voltage sources with corresponding droop functions. The system 100 may include a control circuit that is configured to monitor the bus voltage and control the converter to charge or discharge the rechargeable energy storage element based on the bus voltage. In at least one embodiment, the droop function of the energy storage system is R CESS =(V CESS_MAX –V CESS_MIN ) / (2*ΔI CESS_MAX )), where R CESS is the equivalent output resistance of the energy storage system, V CESS_MAX is the maximum output voltage of the energy storage system under maximum load under charging conditions, V CESS_MIN is the minimum output voltage of the energy storage system under maximum load under discharge conditions, I CESS_MAX is the maximum output or input current of the energy storage system. In at least one embodiment, the droop function of the main power system is R PSS =(V PSS_0A -V PSS_MIN ) / (I PSS_MAX), where R PSS is the equivalent output resistance of the main power system, V PSS_0A The voltage of the main power system when it is zero-loaded, V PSS_MIN The voltage of the main power system at maximum load, I PSS_MAX The maximum output current of the main power system. In some cases, the control circuit is configured to adjust the zero current voltage set point of the converter upward and downward to regulate the state of charge (SOC) of the rechargeable energy storage element. For example, the control circuit is configured to adjust the zero current voltage set point of the converter based on the real-time voltage of the rechargeable energy storage element and the target voltage of the rechargeable energy storage element. In at least one embodiment, the control circuit is configured to filter the AC harmonics of the main power system. For example, the control circuit is configured to passively filter the AC harmonics based on an equivalent output resistance ratio between the main power system and the converter, which equivalent output resistance ratio determines the current ratio between the current change output by the converter and the current change output by the main power system. In at least one embodiment (for example, according to Fig.15 ), the control circuit is configured to actively filter AC harmonics by comparing the real-time current information of the main power system with the average current information. In another example (e.g., Fig.17 In some examples, the control circuit is configured to actively filter AC harmonics by adjusting the SOC target value of the rechargeable energy storage element based on the current information of the main power system. In combination with active filtering of AC harmonics, the control circuit can also be configured to adjust the zero current voltage set point of the converter up and down to regulate the SOC of the rechargeable energy storage element. In some examples, the rechargeable energy storage element includes a plurality of electrically connected capacitors.

[0093] According to at least one example embodiment, the power system 100 includes a bus 124, a main power system 104 connected to the bus and configured as a voltage source with a droop function; a rechargeable energy storage system 112 connected to the bus and configured as a voltage source with a droop function. The rechargeable energy storage system may include a rechargeable energy storage element 116 and a converter 120 connected between the rechargeable energy storage element and the bus. The system may include a control circuit configured to monitor the bus voltage and control the converter to charge or discharge the rechargeable energy storage element based on the bus voltage. In at least one example, the droop function of the main power system is R PSS =(V PSS_0A –V PSS_MIN ) / (I PSS_MAX ), where R PSS is the equivalent output resistance of the main power system, V PSS_0A is the voltage of the main power system at zero load, V PSS_MIN is the voltage of the main power system at maximum load, I PSS_MAX is the maximum output current of the main power system. In at least one example, the droop function of the energy storage system is RCESS =(V CESS_MAX –V CESS_MIN ) / (2*ΔI CESS_MAX )), where R CESS is the equivalent output resistance of the energy storage system, V CESS_MAX is the maximum output voltage of the energy storage system under maximum load under charging conditions, V CESS_MIN is the minimum output voltage of the energy storage system under maximum load under discharge conditions, I CESS_MAX is the maximum output current of the energy storage system. The control circuit can be configured to adjust the zero current voltage set point of the converter upward and downward to adjust the state of charge (SOC) of the rechargeable energy storage element. For example, the control circuit is configured to adjust the zero current voltage set point of the converter based on the real-time voltage of the rechargeable energy storage element and the target voltage of the rechargeable energy storage element. The control circuit can also be configured to filter the AC harmonics of the main power system. For example, the control circuit is configured to passively filter the AC harmonics based on the equivalent output resistance ratio between the main power system and the converter, which determines the current ratio between the current change output by the converter and the current change output by the main power system. In addition or alternatively, the control circuit is configured to actively filter the AC harmonics by comparing the real-time current information of the main power system with the average current information and / or by adjusting the SOC target value of the rechargeable energy storage element based on the current information of the main power system.

[0094] At least one embodiment is directed to a power system including a main power system 104 having an output characteristic of a voltage source with a droop function, a bus 124 configured to be connected to a load, a rechargeable energy storage system 112 connected to the bus having an output characteristic of a voltage source with a droop function, and a control circuit configured to monitor the bus voltage and control the rechargeable energy storage system to charge or discharge the bus based on the bus voltage. The output characteristic of the main power system and the output characteristic of the rechargeable energy storage system can enable the main power system and the rechargeable energy storage system to adjust the bus voltage independently of each other.

[0095] Here, it should be understood that one or more of the above elements can be included on a semiconductor chip as a system on chip (SoC). Each chip (or die) can include a semiconductor substrate (e.g., silicon) on which electronic components are mounted and / or formed. Such a chip can include an electronic memory, and another chip in the chip stack can include a processing / control circuit for controlling the electronic memory. The electronic memory can be a computer-readable medium, including instructions executable by a processor. The memory can include any type of computer memory device, and can be volatile or non-volatile. In some embodiments, the memory can include a plurality of different memory devices. Non-limiting examples of memory include random access memory (RAM), read-only memory (ROM), flash memory, electronically erasable programmable ROM (EEPROM), dynamic RAM (DRAM), etc. The memory can include instructions that enable the processor to control various functions and store data. The memory can be processor local (e.g., integrated with the processor) and / or separate from the processor. The processor can correspond to one or more computer processing devices. For example, the processor can be provided as a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), any other type of integrated circuit (IC) chip, an IC chip set, a microcontroller, a microcontroller set, etc. As a more specific example, the processor can be provided as a microprocessor, a central processing unit (CPU), or multiple microprocessors configured to execute an instruction set stored in a memory. The processor can perform read and / or write operations on the memory and / or enable various functions when executing instructions stored in the memory.

[0096] It should also be understood that the elements described herein may include one or more communication interfaces for communicating with other elements in the system. These communication interfaces include wired and / or wireless communication interfaces for exchanging data and control signals with each other. The example of wired communication interface / connection includes Ethernet connection, HDMI connection, connection that complies with PCI / PCIe standard and SATA standard, etc. The example of wireless interface / connection includes Wi-Fi connection, LTE connection, Bluetooth connection, NFC connection, etc.

[0097] The phrases "at least one", "one or more", "or", and "and / or" are open-ended expressions that are both conjunctions and disjunctions in operation. For example, each of the phrases "at least one of A, B, and C", "at least one of A, B, or C", "one or more of A, B, and C", "one or more of A, B, or C", "A, B and / or C", and "A, B, or C" means A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B, and C together.

[0098] The term "one" or "an" entity refers to one or more of the entity. Therefore, the terms "one" (or "an"), "one or more" and "at least one" can be used interchangeably herein. It should also be noted that the terms "including", "comprising" and "having" can be used interchangeably. Aspects of the present disclosure can take the form of fully hardware embodiments, fully software (including firmware, resident software, microcode, etc.) embodiments, or embodiments combining software and hardware aspects, which are generally referred to as "circuits", "modules" or "systems" herein. Any combination of one or more computer-readable media can be used. A computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium.

[0099] A computer-readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of computer-readable storage media (a non-exhaustive list) would include the following: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer-readable storage medium may be any tangible medium that can contain or store a program for use by or in connection with an instruction execution system, apparatus, or device.

[0100] As used herein, the terms "determine," "calculate," and variations thereof are used interchangeably and include any type of methodology, process, mathematical operation or technique.

[0101] One or more aspects / embodiments substantially disclosed herein.

[0102] One or more aspects / embodiments substantially disclosed herein may optionally be combined with one or more other aspects / embodiments substantially disclosed herein.

[0103] One or more devices adapted to perform one or more of the above-described aspects / embodiments substantially as disclosed herein.

Claims

1. A power supply system, characterized in that: The power supply system comprises: An energy storage system, the energy storage system comprising: Rechargeable energy storage elements; and a converter, the converter being connected to the rechargeable energy storage element and being configured to be connected to a bus, so that the energy storage system is connected in parallel with a load and a main power system, the energy storage system cooperates with the main power system to supply power to the load, and the energy storage system and the main power system are both configured as voltage sources with corresponding droop functions; and A control circuit, wherein the control circuit is configured as follows: Monitor bus voltage; and The converter is controlled according to the bus voltage to charge or discharge the rechargeable energy storage element.

2. The power supply system according to claim 1, characterized in that: The droop function of the energy storage system is R CESS =(V CESS_MAX –V CESS_MIN ) / (2*ΔI CESS_MAX )), where R CESS is the equivalent output resistance of the energy storage system, V CESS_MAX is the maximum output voltage of the energy storage system at maximum load in the charging state, V CESS_MIN is the minimum output voltage of the energy storage system at maximum load in the discharge state, I CESS_MAX is the maximum output or input current of the energy storage system.

3. The power supply system according to claim 2, characterized in that: The droop function of the main power system is R PSS =(V PSS_0A -V PSS_MIN ) / (I PSS_MAX ), where R PSS is the equivalent output resistance of the main power system, V PSS_0A is the zero-load voltage of the main power system, V PSS_MIN is the maximum load voltage of the main power system, I PSS_MAX is the maximum output current of the main power system.

4. The power supply system according to claim 1, characterized in that: The control circuit is configured to adjust a zero current voltage set point of the converter upward or downward to regulate a state of charge (SOC) of the rechargeable energy storage element.

5. The power supply system according to claim 4, characterized in that: The control circuit is configured to adjust the zero current voltage set point of the converter based on a real-time voltage of the rechargeable energy storage element and a target voltage of the rechargeable energy storage element.

6. The power supply system according to claim 1, characterized in that: The control circuit is configured to filter AC harmonics of the main power system.

7. The power supply system according to claim 6, characterized in that: The control circuit is configured to passively filter the AC harmonics based on an equivalent output resistance ratio between the main power system and the converter, the equivalent output resistance ratio determining a current ratio between a current change output by the converter and a current change output by the main power system.

8. The power supply system according to claim 6, characterized in that: The control circuit is configured to actively filter the AC harmonics by comparing real-time current information of the main power system with average current information.

9. The power supply system according to claim 6, characterized in that: The control circuit is configured to actively filter the AC harmonics by adjusting a SOC target value of the rechargeable energy storage element based on current information of the main power system.

10. The power supply system according to claim 6, characterized in that: The control circuit is configured to adjust a zero current voltage set point of the converter upward and downward to regulate the SOC of the rechargeable energy storage element.

11. The power supply system according to claim 1, characterized in that: The rechargeable energy storage element includes a plurality of electrically connected capacitors.

12. A power supply system, characterized in that: The power supply system comprises: bus; a main power supply system connected to the bus and configured as a voltage source with a droop function; a rechargeable energy storage system connected to the bus and configured as a voltage source with a droop function, the rechargeable energy storage system comprising a rechargeable energy storage element and a converter connected between the rechargeable energy storage element and the bus; and A control circuit, wherein the control circuit is configured as follows: Monitor bus voltage; and The converter is controlled according to the bus voltage to charge or discharge the rechargeable energy storage element.

13. The power supply system according to claim 12, characterized in that: The droop function of the main power system is R PSS =(V PSS_0A -V PSS_MIN ) / (I PSS_MAX ), where R PSS is the equivalent output resistance of the main power system, V PSS_0A is the zero-load voltage of the main power system, V PSS_MIN is the maximum load voltage of the main power system, I PSS_MAX is the maximum output current of the main power system.

14. The power supply system according to claim 13, characterized in that: The droop function of the energy storage system is R CESS =(V CESS_MAX –V CESS_MIN ) / (2*ΔI CESS_MAX )), where R CESS is the equivalent output resistance of the energy storage system, V CESS_MAX is the maximum output voltage of the energy storage system at maximum load in the charging state, V CESS_MIN is the minimum output voltage of the energy storage system at maximum load in the discharge state, I CESS_MAX is the maximum output current of the energy storage system.

15. The power supply system according to claim 12, characterized in that: The control circuit is configured to adjust a zero current voltage set point of the converter upward or downward to regulate a state of charge (SOC) of the rechargeable energy storage element.

16. The power supply system according to claim 15, characterized in that: The control circuit is configured to adjust the zero current voltage set point of the converter based on a real-time voltage of the rechargeable energy storage element and a target voltage of the rechargeable energy storage element.

17. The power supply system according to claim 12, characterized in that: The control circuit is configured to filter AC harmonics of the main power system.

18. The power supply system according to claim 17, characterized in that: The control circuit is configured to passively filter the AC harmonics based on an equivalent output resistance ratio between the main power system and the converter, the equivalent output resistance ratio determining a current ratio between a current change output by the converter and a current change output by the main power system.

19. The power supply system according to claim 17, characterized in that: The control circuit is configured to actively filter the AC harmonics by comparing real-time current information of the main power system with average current information or by adjusting the SOC target value of the rechargeable energy storage element based on the current information of the main power system.

20. A power supply system, characterized in that: The power supply system comprises: A main power supply system having a voltage source output characteristic with a droop function; A bus configured to be connected to a load; a rechargeable energy storage system having a voltage source output characteristic with a droop function connected to the bus; and A control circuit, wherein the control circuit is configured as follows: Monitor bus voltage; and The rechargeable energy storage system is controlled to charge or discharge the bus based on the bus voltage, wherein the output characteristics of the main power system and the output characteristics of the rechargeable energy storage system enable the main power system and the rechargeable energy storage system to adjust the bus voltage independently of each other.

Images