Power system

Abstract

A power system includes an energy storage system. The energy storage system includes a rechargeable energy storage element and a converter connected to the rechargeable energy storage element and configured to be connected to the bus such that the energy storage system is connected in parallel with the load and the primary power supply system. The energy storage system cooperates with the main power supply system to supply power to a load. The power supply system may include a control circuit configured to monitor a voltage of the bus and control the converter to charge or discharge the rechargeable energy storage element based on the voltage of the bus.

Description

[0001] This disclosure claims priority to U.S. Patent No. 63 / 534,728, filed on August 25, 2023, and U.S. Patent No. 63 / 562,137, filed on March 6, 2024, the disclosures of which are hereby incorporated by reference in their entirety for their teachings and all purposes. Technical Field

[0002] The present disclosure is generally directed to power systems and control methods for addressing peak loads, such as peak loads in facilities with unstable energy sources and / or highly dynamic loads. Background Art

[0003] Electric devices require ever-increasing energy demands to maintain functionality, which creates a problem where the power demand approaches the maximum building supply limit, while the external line input power cannot meet the dynamic demand. Electrical systems used in high dynamic load environments are composed of two main components, the energy source or power supply and the load. These components each include many different types, and it is important to balance the total amount of power available from the power supply with the total power required by the load to avoid bus voltage fluctuations or sags that cause protection events or even damage to equipment on both sides. Summary of the invention

[0004] In order to improve the problems of the prior art, the present disclosure proposes an electric power system, including an energy storage system and a control circuit. The energy storage system includes: 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 to a load and a main power system, and the energy storage system cooperates with the main power system to supply power to the load. The control circuit is configured to: monitor the voltage of the bus; and based on the voltage of the bus, control the converter to charge or discharge the rechargeable energy storage element.

[0005] In one embodiment, the energy storage system and the main power system supply power to the load such that the rechargeable energy storage element manages the voltage of the bus by charging when the voltage of the bus is below a control threshold and discharging when the voltage of the bus is above the control threshold.

[0006] In one embodiment, the energy storage system cooperates with the primary power system by stabilizing the AC source input of the primary power system.

[0007] In one embodiment, the amount of current flowing from the bus to charge the rechargeable energy storage element and the amount of current flowing to the bus by discharging from the rechargeable energy storage element vary according to the voltage of the bus.

[0008] In an embodiment, the amount of current used to charge the rechargeable energy storage element and the amount of current used to discharge the rechargeable energy storage element vary according to a difference between the voltage of the bus and a zero current set point voltage of the converter.

[0009] In one embodiment, as the difference between the voltage of the bus and the zero-current set point voltage of the converter becomes larger, the amount of current for charging and the amount of current for discharging become larger.

[0010] In one embodiment, the state of charge (SOC) of the rechargeable energy storage element is controlled to avoid overcharging and over-discharging.

[0011] In one embodiment, the power system further includes: a main power system; and an additional control circuit, wherein the additional control circuit is configured to adjust the output current of the main power system based on real-time current monitoring of the main power system, real-time current measurement of the converter and the SOC of the rechargeable energy storage element.

[0012] In one embodiment, the rechargeable energy storage element comprises a plurality of electrically connected capacitors.

[0013] In one embodiment, the plurality of capacitors include a plurality of lithium capacitors or a plurality of electric double layer capacitors.

[0014] In one embodiment, the rechargeable energy storage element comprises a plurality of electrically connected capacitors connected in parallel with a plurality of electrically connected batteries.

[0015] In one embodiment, the control circuit is configured to control the converter to charge the rechargeable energy storage element when the voltage of the bus is greater than a zero current set point voltage of the converter.

[0016] In one embodiment, the control circuit is configured to control the converter to discharge the rechargeable energy storage system when the voltage of the bus is less than the zero current set point voltage of the converter.

[0017] In one embodiment, the control circuit comprises a summing circuit; the summing circuit is configured to subtract a first value based on the voltage of the bus and a second value based on the current provided by the converter from a reference value.

[0018] In one embodiment, the reference value is a reference voltage.

[0019] In one embodiment, the control circuit includes gate drive logic configured to drive the converter based on an output of the summing circuit.

[0020] In one embodiment, the control circuit is further configured to: monitor the voltage of the rechargeable energy storage element; when the voltage of the rechargeable energy storage element is greater than the reference value, control the set point of the converter to increase to allow the rechargeable energy storage element to release energy to the bus; and when the voltage of the rechargeable energy storage element is less than the reference value, control the set point of the converter to decrease to allow the rechargeable energy storage system to absorb energy from the bus.

[0021] In one embodiment, the power system further includes: a main power system; an additional control circuit, wherein the additional control circuit is configured to adjust the output current of the main power system based on the voltage of the bus, the reference voltage of the bus and the real-time current of the main power system.

[0022] The present application also proposes an electric power system, comprising: a bus; a main power system, the main power system is connected to the bus and configured as a current source; a rechargeable energy storage system, the rechargeable energy storage system is connected to the bus and configured as a voltage source with a droop function, the rechargeable energy storage system comprises a rechargeable energy storage element and a converter connected between the rechargeable energy storage element and the bus; and a control circuit, the control circuit is configured to: monitor the voltage of the bus; and control the converter to charge or discharge the rechargeable energy storage element based on the voltage of the bus and the zero current set point voltage of the converter.

[0023] The present application also proposes an electric power system, comprising: a bus, the bus being configured to be connected to a load and a main power system; a rechargeable energy storage system, the rechargeable energy storage system being connected to the bus and configured as a voltage source with a droop function; and a control circuit, the control circuit being configured to: monitor the voltage of the bus; and control the rechargeable energy storage system to charge or discharge the bus based on the voltage of the bus and the zero current set point voltage of the rechargeable energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A block diagram showing a power system of the related art;

[0025] Figure 2 shows a block diagram of a power system according to at least one example embodiment;

[0026] Figure 3 An electric power system including two unidirectional DC-DC converters according to at least one example embodiment is shown;

[0027] Figure 4 An electric power system including a bidirectional DC-DC converter according to at least one example embodiment is shown;

[0028] Figure 5 An electric power system including a plurality of interleaved bidirectional DC-DC converters having 1 to N phases according to at least one example embodiment is shown;

[0029] Figure 6 An example of a single capacitor direct current internal resistance (DCIR) voltage drop caused by a load current and 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;

[0030] Figure 7 A parallel storage system having a capacitive energy storage system (CESS) configured as a voltage source and a main power supply system having a current source type is shown according to at least one example embodiment;

[0031] Figure 8 shows output characteristics of a main power system controlled as a current source according to at least one example embodiment;

[0032] Fig. 9 shows bidirectional output characteristics of a capacitive energy storage system controlled as a voltage source with a droop function according to at least one example embodiment;

[0033] Fig.10 A block diagram showing a control system for a power converter with a CESS to achieve bidirectional charging / discharging behavior according to at least one example embodiment;

[0034] Fig.11 The use of at least one example embodiment is shown Fig.10 Fast and smooth charge and discharge conversion with control mechanism;

[0035] Fig.12 A block diagram of a control system for keeping a CESS away from one or more breakpoints is shown according to at least one example embodiment;

[0036] FIG. 13A to FIG. 13C is a comparison of a waveform of a power system having CESS elements according to at least one example embodiment with a waveform of a power system not having CESS elements;

[0037] Fig.14 Waveforms of a CESS power stage and a main power stage under a load step-up condition and a load step-down condition are shown according to at least one example embodiment. DETAILED DESCRIPTION

[0038] Currently, the smooth balance of the total amount of power available from the power source and the total amount of power required by the load is easily affected by 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, the synchronous nature of their functioning 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 can rise and fall faster than the utility can respond, and there is the potential for voltage sags and frequency excursions at the utility level, as well as tripping of overcurrent protection devices within the data center itself.

[0039] In the facilities of the related art, users usually install an alternating current uninterruptable 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; 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. Because 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.

[0040] The advantages of the embodiments of the present disclosure include at least the following points: reducing the imbalance of input power / output power between energy sources and load requirements; improving scalability and flexibility compared to AC UPS; improving the current control capability of the direct current uninterruptable power supply (DC UPS) system; extremely high number of cycles; and fast charging time (recovery to ready state).

[0041] Figure 2A power supply system 100 is shown according to at least one example embodiment. The system 100 includes a main power supply system 104 (also referred to herein as a "PSS" and "PSU"), a capacitive energy storage system (CESS) 112, and a converter 120 (e.g., a DC-DC converter). The main power supply system 104 includes a power source 106 (e.g., a utility) and a rectifying component 108. The capacitive energy storage system (CESS) 112 includes a chargeable capacitive energy storage element 116 (also referred to herein as an "ESS"). The PSS 104 and the CESS 112 are connected in parallel to a load 128 via an appropriate high current power bus 124.

[0042] Compared to traditional AC UPS systems, DC UPS applications having constituent elements similar to 112 in the proposed system 100 have higher reliability and efficiency and have been widely adopted in data centers to manage backup functions during alternating current (AC) utility outages. In addition, the CESS 112 in the proposed system 100 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 1000 cycles) and asymmetric charge / discharge performance (with a deviation of up to 20 times between charging current capability and discharging current capability), which makes batteries unsuitable for the fast and frequent charging / discharging requirements of AI workloads. This type of application can be referred to as having power filtering requirements. In addition, there are no dedicated control algorithms or symmetrical power transmission converters designed specifically for power filtering applications. As Figure 2 As shown, the exemplary embodiment proposes the use of capacitive rechargeable energy storage elements and introduces a new control mechanism to effectively manage power filtering for 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.

[0043] The energy storage element 116 may include a capacitive power source, such as a series and parallel connection of capacitors (e.g., multiple groups of capacitors, the capacitors in each group are connected in parallel, and each group of capacitors is 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 provide the advantages of high cycle life (millions of cycles), high terminal voltage (2.6V~3.8V), high volume energy density (26Wh / l) and extremely large bidirectional energy 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 cycles. The terms "capacitor", "supercapacitor", "supercapacitor", "electric double layer capacitor (EDLC)" and "EDL supercapacitor" 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 configurations of lithium capacitors or EDL (electric double layer) supercapacitors are configured to meet the storage energy requirements of the application and also meet the DCIR (Direct Current Internal Resistance) limits imposed by the input voltage range of the DC / DC converter used when the current through the capacitor is at its maximum level. In addition, the capacitors have symmetrical charging and discharging characteristics, which means that the capacitors charge as fast as they discharge.

[0044] In some examples, additionally or alternatively, the energy storage element 116 may 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 energy density, small size, and extremely high cycle life to meet the technical requirements of the application.

[0045] As described in more detail herein, a CESS 112 is proposed to address the imbalance between input power / output power of an energy source and load requirements. The system includes a capacitive energy storage element, one or more control circuits, and a power flow control method for a DC / DC converter.

[0046] 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 transient power limit.

[0047] 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.).

[0048] CESS112 can have Figure 3 , Figure 4 and Figure 5 One of the architectures shown in FIG. 1 is CESS 112 a, 112 b and 112 c. It can be understood that Figures 3 to 5 The energy storage elements 116 shown in the diagram 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 will be further understood that each CESS 112a-112c illustrates a different configuration of the converter 120. In more detail, Figure 3 A CESS 112 a is shown having a converter 120 a including two unidirectional DC-DC converters—one converter for discharging an energy storage element 116 and another converter for charging the energy storage element 116 . Figure 4 A CESS 112b is shown with a converter 120b comprising a single bidirectional DC-DC converter. Figure 5 A CESS 112c having a converter 120c is shown, the converter 120c comprising a plurality of interleaved bidirectional DC-DC converters having 1 to N phases. It will be appreciated that Figures 3 to 5 Also 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 functions will be described in more detail below. However, in general, the control system 118 may include processing capabilities and / or drive capabilities.

[0049] As described herein, systems and methods according to example embodiments solve various problems including, but not limited to: input power quantity / output power quantity imbalance between energy sources and load requirements; low scalability and flexibility; weak current control capability; low cycle count of energy storage devices, and slow charging time of energy storage devices.

[0050] The example embodiments are discussed in more detail below with reference to three sections: Section 1) the electrical architecture of the capacitive energy storage element, which explains the voltage range of individual capacitors and capacitor matrices as well as some important characteristics, Section 2) the control system for the energy storage element 116, and Section 3) the control scheme for the bidirectional DC / DC converter and the main objectives of the proposed application.

[0051] 1. ESS electrical architecture

[0052] 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. This range can cover higher voltages or lower voltages, but at the expense of reduced efficiency. 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, lithium capacitors can be charged to 3.8V. When each capacitor is fully charged to 3.8V, an array of 12 such lithium capacitors electrically connected in series will provide a maximum voltage of 45.6V, which is the voltage upper limit of each capacitor, but is still within the 30V to 46V range of the above-mentioned DC / DC (boost) converter 120.

[0053] 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 are characterized by the number of joules of energy available to the system. Increasing the total energy by connecting a single capacitor in parallel before connecting the parallel elements in series will increase the available energy. The total energy storage (in joules) of the capacitors in this series and parallel configuration, with the capacitance value of each capacitor being C 元件 , as shown in the following equation

[0054] As shown in formula 1:

[0055]

[0056] Equation 1 – Equation used to calculate the sum of all energy storage elements in Joules, where P is the number of parallel capacitors and S is the number of parallel capacitor blocks connected in series, operating between the maximum charge voltage (Vmax) and the minimum discharge voltage (Vmin).

[0057] In some examples, the total energy (in joules) of the system can also be increased by combining multiple capacitors in series and / or multiple capacitors in parallel with multiple batteries in series and / or multiple batteries in parallel. In this case, the voltage of the multiple capacitors is kept higher than the voltage of the multiple batteries, so that the capacitors will discharge before the batteries, thereby reducing the discharge frequency and discharge 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 can extend the discharge time. In this case, the battery has a minimum discharge depth, thereby extending the cycle life.

[0058] Capacitors such as lithium capacitors and EDL supercapacitors have a measurable direct current 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, the DCIR will cause a voltage drop across the capacitor stack at the instant the load is applied. This offset 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 offset. This offset must be taken into account when considering the appropriate number of series capacitors when compared to the operating voltage at the input of the DC / DC converter 120. By scaling the DCIR of a single energy supply element according to the number of series connections and the number of parallel connections in the entire system, the system equivalent DCIR (DCIReq, equivalentDCIR) is obtained, which is expressed in Equation 2 below:

[0059]

[0060] Equation 2 – Equation used to calculate the equivalent system DCIR related to the DCIR of a single storage element, which scales with the number of storage elements in series (S) and in parallel (P).

[0061] 2. Energy storage element control architecture

[0062] Capacitive energy systems such as those described herein require continuous active monitoring and balancing of individual capacitor voltages during operation. The system described in U.S. Patent 11,121,415 for monitoring system for series-connected battery cells (incorporated herein by reference) is well suited to accomplish this task when battery cells are replaced by multiple capacitors and can constitute Figure 4At least a part of the energy storage system controller 118. The method described in this patent has the advantage of coulomb counting, which can determine the current capacitance value of each capacitor in the system on-site at any point in its service life, thus facilitating comparison over time to measure capacitor aging. The method also implements active cycle counting.

[0063] 3. Bidirectional power flow control architecture

[0064] Figure 7 A parallel storage system with a capacitive energy storage element 116 and a power supply system (PSS) 104 of current source type is shown. In other words, PSS 104 can be configured to have a constant current source with current I PSS while CESS 112 is configured as a voltage source with a voltage drop due to resistance R CESS resulting in voltage V CESS_0A .

[0065] The objectives of the proposed power flow control architecture are: (1) to filter dynamic power flow on the PSS side; (2) to keep V 总线 at an appropriate level; (3) to keep CESS away from the system break point, in other words, to avoid the fully charged / discharged state of CESS (0% < CESS state of charge (SOC) < 100%).

[0066] To achieve objective #1 (filter dynamic power flow on PSS 104), the output characteristics of PSS 104 are controlled as a current source, as Figure 8 shown. V PSS_MAX and V PSS_MIN represent the maximum output bus voltage boundary and the minimum output bus voltage boundary respectively if PSS 104 operates at zero load or maximum load. I PSS_MAX is the maximum output current limit point of PSS 104.

[0067] To achieve objective #2 (keep V 总线 at an appropriate level), CESS 112 needs to balance the power required by the source / load and maintain the voltage of DC bus 124. The output characteristics of CESS 112 are controlled as a voltage source with a droop function, as Fig. 9 shown. For the output characteristics of CESS 112, if the bus 124 voltage V 总线 (e.g., real-time bus voltage) is equal to the voltage V CESS_0A of CESS 112 (where V CESS_0A is the zero-ampere voltage set point of CESS 112, which varies according to system design), then there is neither discharge behavior nor charging behavior. However, when V 总线 is greater than V CESS_0ACESS112 starts charging, and when V 总线 Less than V CESS_0A In other words, if V 总线 -V CESS_0A is negative, the CESS 112 discharges to the DC bus 124 through the power converter 120; if V 总线 -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 charging current and discharging current depend on V 总线 and V CESS_0A For example, with V 总线 and V CESS_0A As the difference between the two increases, the amount of charging current and the amount of discharging current from the CESS 112 increase.

[0068] Fig.10 A block diagram for implementing the above-mentioned bidirectional charging / discharging behavior is shown. Fig.10 The control mechanism of the charging and discharging switch is fast and smooth. Fig.11 As shown 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 immediately changes 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 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 (kV*V 总线 +kI*I CESS ) to generate V CONT The compensator 208 may be implemented in circuit (ie, hardware) or firmware code. As shown, the summing circuit 212 receives and operates on the reference voltage signal V REF and signals from circuits 216 and 220. As shown, the output of circuit 216 is based on V measured on bus 124. 总线 , and the output of circuit 220 is based on I measured on bus 124 CESSEach circuit 216 and 220 can input V according to its own weight K 总线 or I CESS The following equation 3 shows that V 总线 , K value and I CESS The relationship between:

[0069]

[0070] To achieve goal #3 (keep CESS 112 away from system breakpoints), the average current flowing into / out of the capacitor needs to be zero. There are two methods / circuit examples to achieve this goal.

[0071] Example 1: PSS 104 output current command (I PSS_REF ) can be adjusted according to the load condition and the state of charge (e.g., real-time SOC) of the CESS 112, as shown in the following equation 4, where I CESS_LPF and I PSS_LPF are the average values ​​of the CESS and PSS output currents (e.g., real-time values), SOC represents the state of charge of the energy storage element (e.g., the real-time SOC of the energy storage element 116), and SOC TG is the SOC regulation target, K SOC To determine the compensation factor of the conversion rate between charging behavior and discharging behavior (SOC TG and K SOC is a design parameter that may vary according to the design and is selected based on empirical evidence and / or preference). The method may employ fast and frequent information transmission between the CESS and the PSS to maintain good dynamic power filtering function.

[0072]

[0073] Equation 4 – Equation used for PSS current command calculation in Example #1

[0074] Example #2: Fig.12 2 is a block diagram of implementation example 2. Here, the CESS implements its own SOC regulation function for the energy storage element 116. CAP is the capacitor voltage (e.g., the real-time voltage of the energy storage element 116), which can directly indicate the SOC level of the CESS, V CAP_REF is the target voltage value of the energy storage element 116 for SOC regulation. CAP Greater than V CAP_REF , CESS 112 increases its output set point to indicate and ultimately release energy (i.e., discharge) to bus 124. CAP Less than V CAP_REF, the CESS reduces its output set point to indicate and ultimately intend to absorb energy (i.e., charge) from the DC bus 124. The PSU monitors the bus voltage (V 总线 ) to determine whether to increase or decrease the current command (I PSS_REF ). When V 总线 Greater than V 总线_REF (which can be the specified operating voltage of the load), the PSU reduces the output current command. 总线 Less than V 总线_REF , the PSU increases the output current command.

[0075] The above functions of Example 2 are performed by control circuits 300 and 304. As shown, control circuit 300 includes drive logic 308 for driving the rectifier of PSU stage 104, compensator 312, and summing circuit 316, which receives and operates on the current value I shown. PSS_REFIPSSS and ΔI PSS_REF , where ΔI PSS_REF is the output from compensator 324, the input of compensator 324 is from summing circuit 320, which determines V 总线_REF and V 总线 Meanwhile, the control circuit 304 includes a drive logic 328 for driving the converter 120 of the CESS stage 112, a compensator 332, and a summing circuit 336, which receives and operates the voltage value V shown. CESS_0A , ΔV CESS_0A and the output of feedback block 348, which outputs a signal based on V 总线 and I CESS The signal, ΔV CESS_0A is the output of compensator 344, the input of which comes from summing circuit 340, which determines V CAP and V CAP_REF It will be appreciated that the compensator shown provides a Fig.10 The compensator 208 may perform the same or similar functions as described above.

[0076] FIG. 13A to FIG. 13C is a waveform comparison of a power system with and without a CESS power level, wherein the system implements the above control method example #1. In more detail, Fig.13A is a comparison between multiple systems during load step-up, Fig. 13B is a comparison between multiple systems during load step-down, Fig. 13C Channel 1 (yellow) is the bus voltage (V 总线 ), channel 2 (blue) is the capacitor voltage (VCAP ), Channel 3 (purple) is the load current (I 负载 ), channel 4 is the AC current (I AC ). As can be seen from the figure, for all load modes, the power system with CESS can greatly alleviate the slope change of IAC at load transient moments, which reduces AC current harmonics. In the example shown, the bus voltage is maintained at around 50V within the appropriate range.

[0077] Fig.14 The waveforms of the CESS stage and the PSU stage under load step-up condition and load step-down condition are shown, where the system implements the control method example #2 described above. Channel 1 (yellow) is the load current (I 负载 ), channel 2 (blue) is the bus voltage (V 总线 ), Channel 3 (purple) is the PSU current (IPSU), and Channel 4 is the AC current (I AC ).from Fig.14 It can be seen that at the moment of load transient, CESS greatly alleviates the slope variation of IAC, which reduces the AC current harmonics.

[0078] In view of the foregoing, it should be appreciated that the systems and methods according to example embodiments provide at least the following advantages: symmetrical charging and discharging capabilities; high energy density; ability to achieve extremely high cycle counts; faster charging and discharging rates than other technologies; high flexibility; high scalability; fast and smooth transition between charging and discharging behaviors; high robustness and stability of DC bus voltage regulation; inherent utility input current transient smoothing; and highly robust power flow management that avoids CESS breakpoints.

[0079] The elements of the system described herein include a PSS (power supply system) as a current source, a CESS (capacitive energy storage system) as a voltage source with a voltage drop, and a CESS; the CESS includes lithium or EDL supercapacitors connected in series and parallel, or a combination of a capacitor array connected in series and parallel and a plurality of batteries connected in series and parallel. Example embodiments also provide a control algorithm for the CESS, which coordinates with the control mechanism of the PSS to achieve a reduction in the slope of the PSS output power variation, a reduction in power line harmonics in the utility input line current, and a fast and smooth bidirectional power flow of the combined power system. Example embodiments also provide a bidirectional power flow control architecture that illustrates output characteristics of a PSS and a CESS and the interaction of the PSS and the CESS, a control algorithm for a bidirectional DC / DC converter of the CESS to achieve instantaneous power flow direction change, a control mechanism for regulating the current of the PSS by calculating the real-time output currents of the CESS and the PSS and the real-time SOC value of the CESS, a control algorithm for the CESS to regulate the SOC or voltage of its capacitor by adjusting its output offset point, and a control mechanism for regulating the current of the PSS by monitoring the system bus voltage without exchanging information between the PSS and the CESS.

[0080] In view of the above, it should be appreciated that example embodiments are directed to a power system 100. The power system 100 includes an energy storage system 112. The energy storage system 112 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, such that the energy storage system is connected in parallel to a load 128 and a main power system 104. In some examples, the energy storage system cooperates with the main power system to supply power to the load. The energy storage system may include a control circuit (e.g., 118, 200, and / or 304) configured to monitor a voltage of the bus (e.g., V 总线 ) and controls the converter to charge or discharge the rechargeable energy storage element based on the voltage of the bus.

[0081] In some examples, the energy storage system and the main power system supply power to the load, so that the rechargeable energy storage element is charged when the load current is below a control threshold (e.g., I PSS_REF ) and discharges when the load current is above a control threshold to manage the bus. In some examples, the energy storage system collaborates with the primary power system by stabilizing the AC source input of the primary power system (e.g., utility 106). Fig. 9It can be seen that the amount of current flowing from the bus for charging the rechargeable energy storage element and the amount of current flowing to the bus by discharging from the rechargeable energy storage element vary according to the voltage of the bus. In at least one embodiment, the amount of current used to charge the rechargeable energy storage element and the amount of current used to discharge the rechargeable energy storage element vary according to the difference between the voltage of the bus and the zero current set point voltage of the converter. For example, as the difference between the voltage of the bus and the zero current set point voltage of the converter increases, the amount of current used for charging and the amount of current used for discharging increase.

[0082] from Fig.12 It can be seen that the state of charge (SOC) of the rechargeable energy storage element is controlled to avoid overcharging and over-discharging.

[0083] In some examples, system 100 also includes a main power system; and additional control circuitry (e.g., 300) configured to regulate an output current of the main power system based on real-time current monitoring of the main power system, real-time current measurement of the converter, and the SOC of the rechargeable energy storage element.

[0084] As described herein, the rechargeable energy storage element may include a plurality of electrically connected capacitors. The plurality of capacitors may include a plurality of lithium capacitors or a plurality of double-layer capacitors. In at least one example, the rechargeable energy storage element includes a plurality of electrically connected capacitors connected in parallel with a plurality of electrically connected batteries.

[0085] from Fig. 9 It can be seen that in some examples, the control circuit is configured to turn on the zero current set point voltage (e.g., V CESS_0A ), the control converter is controlled to charge the rechargeable energy storage element. In some examples, the control circuit is configured to control the converter to discharge the rechargeable energy storage system when the voltage of the bus is less than the zero current set point voltage of the converter. Fig.10 As shown, in at least one embodiment, the control circuit includes a summing circuit (e.g., 212) configured to sum from a reference value (e.g., V REF ) by subtracting a first value based on the bus voltage and a first value based on the current provided by the converter (eg, I CESS_0A ), the reference value may be a reference voltage. Fig.10 As shown, the control circuit may include gate drive logic (eg, 204) configured to drive the converter based on the output of the compensator receiving the output of the summing circuit. Fig.12 In some examples, the control circuit is further configured to monitor the voltage of the rechargeable energy storage element and control the set point of the converter (e.g., V CESS_0A) increases, thereby allowing the rechargeable energy storage element to release energy to the bus, and when the voltage of the rechargeable energy storage element is less than the reference value, the set point of the converter is controlled to decrease, thereby allowing the rechargeable energy storage system to absorb energy from the bus.

[0086] As described above, the system may further include a main power system and an additional control circuit (eg, 300), the additional control circuit being configured to provide a control signal based on the bus voltage, a reference voltage of the bus (eg, V 总线_REF ) and the real-time current of the main power system (such as I PSS ) to regulate the output current of the main power system (for example, I PSS ).

[0087] In view of the description and the accompanying drawings, at least one example embodiment is directed to an electric power system 100, which includes a bus 124 and a main power system 104, which is connected to the bus and configured as a current source. The electric power system 100 may include 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 having a rechargeable energy storage element 116 and a converter 120 connected between the rechargeable energy storage element and the bus. The system may also include a control circuit (e.g., 118, 200, and / or 304) configured to monitor the voltage of the bus and control the converter based on the voltage of the bus and a zero current set point voltage (e.g., V CESS_0A ) to charge or discharge the rechargeable energy storage element.

[0088] In view of the description and the drawings, at least one example embodiment is directed to an electric power system 100, which includes a bus 124 configured to be connected to a load and a main power system 104 and a rechargeable energy storage system 112 connected to the bus and configured as a voltage source with a droop function. The electric power system may include a control circuit (e.g., 118, 200, and / or 304) configured to monitor the voltage of the bus and control the rechargeable energy storage system to charge or discharge the bus based on the voltage of the bus and a zero current set point voltage of the rechargeable energy storage system.

[0089] Here, it should be understood that one or more of the above elements can be included as a system-on-chip (SoC) on a semiconductor chip. Each chip (or die) may include a semiconductor substrate, such as silicon, on which electronic components are mounted and / or formed. Such a chip may include an electronic memory, and another chip in the chip stack may include a processing circuit / control circuit for controlling the electronic memory. The electronic memory may be a computer-readable medium including instructions that can be executed by a processor. The memory may include any type of computer memory device and may be volatile or non-volatile. In some embodiments, the memory may 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), and the like. The memory may include instructions that enable the processor to control various functions and store data. The memory may be local to the processor (e.g., integrated with the processor) and / or separate from the processor. The processor may correspond to one or more computer processing devices. For example, the processor may be provided as a Field Programmable Gate Array (FPGA), an Application-Specific Integrated Circuit (ASIC), any other type of integrated circuit chip, an IC (IC) chip set, a microcontroller, a microcontroller set, etc. As a more specific example, the processor may be provided as a microprocessor, a central processing unit (CPU), or a plurality of microprocessors configured to execute an instruction set stored in a memory. The processor may perform read and / or write operations on the memory, and / or implement various functions when executing instructions stored in the memory.

[0090] It should also be understood that the element described herein may include one or more communication interfaces, and the communication interface can realize the communication with other elements in the system. These communication interfaces include wired communication interface and / or wireless communication interface, for exchanging data and control signal between each other. The example of wired communication interface / connection includes Ethernet connection, HDMI (High Definition Multimedia Interface) connection, compliance with PCI / PCIe (Peripheral Component Interconnect / Peripheral Component Interconnect express, peripheral component interconnection standard / peripheral component interconnection standard high speed) standard and SATA (Serial ATA, Serial ATA) standard connection, etc. The example of wireless interface / connection includes Wi-Fi (Wireless Fidelity, wireless Internet access) connection, LTE (Long Term Evolution, long-term evolution) connection, Bluetooth connection, NFC (Near Field Communication, near field communication) connection, etc.

[0091] 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 expressions "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.

[0092] The terms "one or more" and "at least one" can be used interchangeably herein. It should also be noted that "including", "comprising" and "having" can be used interchangeably.

[0093] Aspects of the present disclosure may 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 herein as "circuits," "modules," or "systems." Any combination of one or more computer-readable media may be used. A computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium.

[0094] A computer-readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or apparatus, 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, erasable programmable read-only memory, or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM, compact disc read-only memory), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this article, a computer-readable storage medium may be any tangible medium that can contain or store a program that can be used by an instruction execution system, device, or apparatus, or the program can be used in conjunction with an instruction execution system, device, or apparatus.

[0095] As used herein, the terms "determine," "estimate," "calculate," and "calculate" and variations thereof are used interchangeably and include any type of methodology, process, mathematical operation or technique.

[0096] Any one or more aspects / embodiments substantially as disclosed herein.

[0097] Optionally, any one or more aspects / embodiments substantially disclosed herein are combined with any one or more other aspects / embodiments substantially disclosed herein.

[0098] One or more devices adapted to perform any one or more of the above aspects / embodiments substantially disclosed herein.

Claims

1. A power system, characterized in that: include: Energy storage system, including: Rechargeable energy storage elements; and a converter connected to the rechargeable energy storage element and configured to be connected to a bus to connect the energy storage system in parallel to a load and a main power system, the energy storage system cooperating with the main power system to supply power to the load; and A control circuit, wherein the control circuit is configured as follows: monitoring the voltage of the bus; and Based on the voltage of the bus, the converter is controlled to charge or discharge the rechargeable energy storage element.

2. The power system according to claim 1, characterized in that: The energy storage system and the main power system supply power to the load such that the rechargeable energy storage element manages the voltage of the bus by charging when the voltage of the bus is below a control threshold and discharging when the voltage of the bus is above the control threshold.

3. The power system according to claim 1, characterized in that: The energy storage system cooperates with the primary power system by stabilizing the AC source input to the primary power system.

4. The power system according to claim 1, characterized in that: The amount of current flowing from the bus line for charging the rechargeable energy storage element and the amount of current flowing to the bus line by discharging from the rechargeable energy storage element vary according to the voltage of the bus line.

5. The power system according to claim 4, characterized in that: The amount of current used to charge the rechargeable energy storage element and the amount of current used to discharge the rechargeable energy storage element vary according to a difference between the voltage of the bus and a zero current set point voltage of the converter.

6. The power system according to claim 5, characterized in that: As the difference between the voltage of the bus and the zero-current set point voltage of the converter becomes larger, the amount of current for charging and the amount of current for discharging become larger.

7. The power system according to claim 1, characterized in that: The state of charge (SOC) of the rechargeable energy storage element is controlled to avoid overcharging and overdischarging.

8. The power system according to claim 1, characterized in that: Further including: Main power supply system; and Additional control circuitry is configured to regulate output current of the primary power system based on real-time current monitoring of the primary power system, real-time current measurement of the converter, and the SOC of the rechargeable energy storage element.

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

10. The power system according to claim 9, characterized in that: The plurality of capacitors include a plurality of lithium capacitors or a plurality of electric double layer capacitors.

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

12. The power system according to claim 1, characterized in that: The control circuit is configured to control the converter to charge the rechargeable energy storage element when the voltage of the bus is greater than a zero current set point voltage of the converter.

13. The power system according to claim 12, characterized in that: The control circuit is configured to control the converter to discharge the rechargeable energy storage system when the voltage of the bus is less than the zero current set point voltage of the converter.

14. The power system according to claim 1, characterized in that: The control circuit includes a summing circuit; The summing circuit is configured to subtract a first value based on the voltage of the bus and a second value based on the current provided by the converter from a reference value.

15. The power system according to claim 14, characterized in that: The reference value is a reference voltage.

16. The power system according to claim 14, characterized in that: The control circuit includes gate drive logic configured to drive the converter based on an output of the summing circuit.

17. The power system according to claim 14, characterized in that: The control circuit is further configured as: Monitoring the voltage of the rechargeable energy storage element; When the voltage of the rechargeable energy storage element is greater than the reference value, controlling the set point of the converter to increase so as to allow the rechargeable energy storage element to release energy to the bus; as well as When the voltage of the rechargeable energy storage element is less than the reference value, the set point of the converter is controlled to decrease to allow the rechargeable energy storage system to absorb energy from the bus.

18. The power system according to claim 1, characterized in that: Also includes: Main power supply system; An additional control circuit is configured to adjust an output current of the main power system based on a voltage of the bus, a reference voltage of the bus, and a real-time current of the main power system.

19. A power system, characterized in that: include: bus; a main power system connected to the bus and configured as a current source; 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; as well as A control circuit, wherein the control circuit is configured as follows: monitoring the voltage of the bus; as well as The converter is controlled to charge or discharge the rechargeable energy storage element based on the voltage of the bus and a zero current set point voltage of the converter.

20. A power system, characterized in that: include: a bus configured to be connected to a load and a main power system; a rechargeable energy storage system connected to the bus and configured as a voltage source with a droop function; as well as A control circuit, wherein the control circuit is configured as follows: monitoring the voltage of the bus; as well as The rechargeable energy storage system is controlled to charge or discharge from the bus based on the voltage of the bus and a zero current set point voltage of the rechargeable energy storage system.

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