Battery energy storage parallel equalization converter topology and control method therefor

Abstract

The present invention provides a battery energy storage parallel equalization converter topology and a control method therefor. The battery energy storage parallel equalization converter topology comprises a series-connected battery energy storage parallel equalization converter, a main converter, and a plurality of groups of filter inductors; in the main converter, the input side of a DC / DC or DC / AC converter is connected in parallel to a parallel voltage-stabilizing capacitor, and the output side of the DC / AC or DC / AC converter is correspondingly connected to an AC or DC source load; the series-connected battery energy storage parallel equalization converter comprises a plurality of groups of small-capacity DC / DC converters and a common DC bus capacitor; the output sides of all the small-capacity DC / DC converters are connected in parallel by means of the common DC bus capacitor to form a common DC bus; the input side of one group of small-capacity DC / DC converters is connected in series to the input side of the main converter, and the input sides of other groups of small-capacity DC / DC converters are connected in series to a battery pack by means of the filter inductors, respectively. According to the present invention, in a battery charging and discharging process, only a small amount of power flows through the converter, reducing the capacity requirements of the converter, and reducing the transmission efficiency.

Description

A battery energy storage parallel balanced converter topology and control method thereof Technical Field

[0001] The present invention relates to the technical field of parallel energy storage converters, and in particular to a battery energy storage parallel balanced converter topology and a control method thereof. Background Art

[0002] To meet the growing capacity demands of energy storage systems, batteries are often used in groups of multiple battery packs connected in parallel. However, differences between battery packs during production and operation inevitably exist, resulting in a "bucket effect." Overcharging or over-discharging a battery pack will gradually degrade the performance of the entire pack, ultimately shortening its service life. Furthermore, differences in electrical characteristics such as port voltage and internal impedance between battery packs can generate parallel circulating currents, leading to overcurrent or overheating, and even safety hazards such as battery deformation and explosion. This has gradually become one of the "bottleneck" issues restricting the development of large-scale energy storage projects. A parallel balancing converter for battery energy storage has been proposed to respond to the differences in electrical and chemical characteristics between different battery packs, thereby achieving parallel circulating current suppression and active regulation of the charge and discharge power of each parallel battery pack.

[0003] Existing energy storage converter solutions primarily include centralized and distributed models. Centralized energy storage converters are configured with only one set on the busbar side. While using fewer components, the energy stored in each battery pack cannot be independently adjusted, resulting in a "bucket effect" and the risk of overheating and overcurrent caused by parallel circulation. Distributed parallel energy storage converters, in which each battery pack is equipped with a set of converters, allow for flexible adjustment of energy stored in each battery elevator, but suffer from the disadvantages of using more components, high cost, low efficiency, and low power density. Summary of the Invention

[0004] In view of the defects in the prior art, the purpose of the present invention is to provide a battery energy storage parallel balanced converter topology and a control method thereof.

[0005] According to one aspect of the present invention, a battery energy storage parallel balancing converter topology is provided, comprising a series battery energy storage parallel balancing converter, a main converter and multiple groups of filter inductors;

[0006] The main converter includes a DC / AC converter and a parallel voltage-stabilizing capacitor, or includes a DC / DC converter and a parallel voltage-stabilizing capacitor; the DC / AC converter or the DC / AC converter input side is connected in parallel with the parallel voltage-stabilizing capacitor, the DC / AC converter output side is connected to an AC source and load, and the DC / DC converter output side is connected to a DC source and load;

[0007] The series battery energy storage parallel balancing converter includes multiple groups of small-capacity DC / DC converters and a common DC bus capacitor; wherein the small-capacity DC / DC converter refers to a DC / DC converter whose capacity is much smaller than the rated charge and discharge power of the battery group.

[0008] The output sides of all small-capacity DC / DC converters are connected in parallel through common DC bus capacitors to form a common DC bus;

[0009] One group of small-capacity DC / DC converter input sides is connected in series with the main converter input side, and the other groups of small-capacity DC / DC converter input sides are connected in series via filter inductors and battery packs.

[0010] Preferably, the topology of the small-capacity DC / DC converter in the series-type battery energy storage parallel balancing converter includes Buck, Boost and Buck-Boost, etc.; the topology of the DC / AC converter in the main converter includes two-level topology, three-level topology and multi-level topology, etc., among which the three-level topology includes NPC type and flying capacitor type, etc.; the topology of the DC / DC converter in the main converter includes DAB and LLC, etc.

[0011] Preferably, each battery group is connected in parallel through the series-type battery energy storage parallel balancing converter to form a parallel energy storage system, thereby actively suppressing the parallel circulating current between each battery group; each battery group and the main converter are connected in series through the series-type battery energy storage parallel balancing converter and the filter inductor to form a series power regulation structure, thereby actively regulating the charge and discharge current of the battery group.

[0012] Preferably, the parallel circulating current between the battery packs is suppressed by adjusting the input voltage difference of the DC / DC converters connected between the battery packs; and the charge and discharge current of the battery pack is adjusted by adjusting the input voltage of the main converter.

[0013] Preferably, the filter inductor suppresses the harmonics of the charging and discharging currents of each battery pack; the common DC bus capacitor in the series battery energy storage parallel balancing converter maintains the stability of the common DC bus voltage and suppresses the common DC bus voltage harmonics; the parallel stabilizing capacitor in the main converter maintains the stability of the parallel DC bus voltage and suppresses the parallel branch bus voltage harmonics.

[0014] Preferably, the common DC bus voltage, the shunt stabilizing capacitor voltage and the filter inductor current ripple are designed to be within a preset range during operation.

[0015] Preferably, the filter inductor and the input inductor of the small-capacity DC / DC converter of the series-type battery energy storage parallel balancing converter can be integrated; the common DC bus capacitor of the series-type battery energy storage parallel balancing converter and the output capacitor of the small-capacity DC / DC converter can be integrated; the parallel stabilizing capacitor of the main converter and the input capacitor of the DC / DC converter or DC / AC converter can be integrated.

[0016] Preferably, the working principle of the battery energy storage parallel balancing converter topology is: the multi-branch energy storage parallel balancing converter topology is equivalent to the superposition of multiple single-branch energy storage parallel balancing converters; wherein, the multi-branch energy storage parallel balancing converter topology includes multiple groups of small-capacity DC / DC converters, and the single-branch energy storage parallel balancing converter only includes one group of small-capacity DC / DC converters.

[0017] Preferably, in the single-branch energy storage parallel balanced converter topology, the series battery energy storage parallel balanced converter includes two groups of Boost topologies and a common DC bus capacitor; each group of Boost topologies includes two groups of fully controlled devices and an input inductor, one group of fully controlled devices is S1, S2, and the other group of fully controlled devices is S n1 ,S n2 ; The Boost topology input side of the fully controlled devices S1 and S2 is connected in series with the main converter, and the other group of fully controlled devices is S n1 ,S n2 The Boost topology input side is connected in series with the battery pack through the filter inductor, and the two Boost topology output sides are connected in parallel through a common DC bus to adjust the voltage between each port; the common DC bus capacitor is connected in parallel to the common DC bus to maintain the voltage and filter out voltage harmonics to achieve stable operation.

[0018] Preferably, the first operating mode of the single-branch energy storage parallel balanced converter topology is:

[0019] Series battery energy storage parallel balancing converter switches S1 and S n1 Turn on, switches S2 and S n2 When turned off, the common DC bus capacitor is neither charged nor discharged;

[0020] The charging and discharging power starts from the parallel voltage stabilizing capacitor and passes through the series type battery energy storage parallel balancing converter switches S1 and S n1 , the filter inductor L and the battery pack return to the parallel voltage stabilizing capacitor to form a loop;

[0021] At this time, the time domain expression of charge and discharge power is:

[0022] Where L is the filter inductor, i lk, k=1,2…, n is the charge and discharge power of the kth battery group, R L is the internal resistance of the filter inductor, R E is the internal resistance of the battery pack, v cp is the voltage of the parallel stabilizing capacitor, e k is the voltage of the kth battery pack;

[0023] The second operating mode of the single-branch energy storage parallel balanced converter topology is:

[0024] Series battery energy storage parallel balancing converter switches S1 and S n2 Turn on, switches S2 and S n1 Shut down, the common DC bus capacitor is charged;

[0025] The charging and discharging power starts from the parallel voltage stabilizing capacitor and passes through the series type battery energy storage parallel balancing converter switch S1, the common DC bus capacitor, the series type battery energy storage parallel balancing converter switch S n2 , the filter inductor L and the battery pack return to the parallel voltage stabilizing capacitor to form a loop;

[0026] At this time, the time domain expression of charge and discharge power is:

[0027] Where vcs is the common DC bus voltage;

[0028] The third operating mode of the single-branch energy storage parallel balanced converter topology is:

[0029] Series battery energy storage parallel balancing converter switches S2 and S n2 Turn on, switches S1 and S n1 When turned off, the common DC bus capacitor is neither charged nor discharged;

[0030] The charging and discharging power starts from the parallel stabilizing capacitor, passes through the series battery energy storage parallel balancing converter switches S2 and Sn2, the filter inductor L and the battery pack, and returns to the parallel stabilizing capacitor, forming a loop;

[0031] At this time, the time domain expression of charge and discharge power is:

[0032] The fourth operating mode of the single-branch energy storage parallel balanced converter topology is:

[0033] Series battery energy storage parallel balancing converter switches S2 and S n1 Turn on, switches S1 and S n2 Turn off and put in parallel voltage stabilizing capacitor;

[0034] The charging and discharging power starts from the parallel voltage stabilizing capacitor and passes through the series battery energy storage parallel balancing converter switch S2, DC capacitor, S n1, the filter inductor L and the battery pack return to the parallel voltage stabilizing capacitor to form a loop;

[0035] At this time, the time domain expression of charge and discharge power is:

[0036] Preferably, the working principle of the battery energy storage parallel balancing converter topology is described by multiple expressions, including: a total or average charge and discharge current expression, a parallel circulating current expression, a common DC bus voltage expression, a parallel stabilizing capacitor voltage expression, a battery state of charge expression, and a modal current waveform;

[0037] The complex frequency domain expression of the average or total charge and discharge current is:

[0038] in is the average value of the charge and discharge power switching cycle, <v cp (t)> T is the average value of the shunt stabilizing capacitor voltage switching period, is the average value of the common-mode voltage switching cycle of the battery pack, is the average value of the switching period of the common-mode switching function of the small-capacity DC / DC converter connected to the battery pack, <s> T is the average value of the switching period of the switching function of the small-capacity DC / DC converter connected to the main converter, <v cs (t)> T is the average value of the common DC bus voltage switching period;

[0039] The complex frequency domain expression of the parallel differential mode current is:

[0040] Where <Δs k > T is the average switching period of the differential mode switching function of the small capacity DC / DC converter connected to the kth battery pack, <Δi lk > T is the average value of the switching cycle of the kth group of filter inductors in parallel circulation, <Δe k > T is the average value of the differential mode voltage switching cycle of the kth battery pack;

[0041] The complex frequency domain expression of the common DC bus voltage is:

[0042] Among them C S is the common DC bus capacitance value;

[0043] The complex frequency domain expression of the parallel stabilizing capacitor voltage is:

[0044] Among them C P is the parallel stabilizing capacitor value,<i(t)> T is the average value of the main converter current switching cycle;

[0045] The battery state of charge (SOC) expression includes the battery common mode state of charge (SOC) expression and the battery differential mode state of charge (SOC) expression;

[0046] The complex frequency domain expression of the battery common mode state of charge SOC is:

[0047] where Q r is the rated charge of the battery pack, is the average value of the common-mode state-of-charge switching cycle of the battery pack;

[0048] The complex frequency domain expression of the battery differential mode state of charge SOC is:

[0049] Where <ΔSOC k (t)> T is the average value of the differential mode state of charge switching cycle of the kth battery group.

[0050] According to a second aspect of the present invention, a control method for a battery energy storage parallel balanced converter topology is provided, comprising:

[0051] Charge and discharge power control: adjust the average or total charge and discharge current of all battery packs by adjusting the parallel DC bus voltage;

[0052] Parallel circulation control: By adjusting the differential mode switching function between each small-capacity DC / DC converter of the parallel balancing converter of the series-connected battery energy storage, the parallel circulation current between each battery group is adjusted;

[0053] Battery state of charge control: adjust the state of charge (SOC) of each battery pack by adjusting the charge and discharge power and parallel circulation current;

[0054] Common DC bus voltage control: The common DC bus voltage is regulated by adjusting the common-mode switching function of all small-capacity DC / DC converters in the parallel balancing converters of the series-connected battery energy storage.

[0055] Shunt DC bus voltage control: The shunt DC bus voltage is regulated by adjusting the main converter switching function.

[0056] Preferably, in the charge and discharge power control, the controller is designed to:

[0057] where K PI is the proportional coefficient of the charge and discharge power control method, K II is the integral coefficient of the charge and discharge power control method, i Lref is the reference value of charge and discharge power, v cpr is the parallel DC bus voltage reference value.

[0058] Preferably, in the parallel circulation control, the controller is designed as follows:

[0059] where K PI K is the proportional coefficient of the parallel circulation control method, which is the same as the proportional coefficient of the charge and discharge power control method; II is the integral coefficient of the charge and discharge power control method, which is the same as the integral coefficient of the charge and discharge power control method, Δi lk is the reference value of the parallel circulating current of the kth group of filter inductors.

[0060] Preferably, the battery state of charge control includes battery common mode state of charge control and battery differential mode state of charge control;

[0061] The battery common mode state of charge control adjusts the average (total) state of charge of the battery by adjusting the average (total) charge and discharge current of all battery packs. The controller is designed as follows:

[0062] where K PSOC K is the proportional coefficient of the battery common mode state of charge control method, ISOC is the integral coefficient of the battery common mode state of charge control method, SOC r is the reference value of the battery pack state of charge;

[0063] The battery common-mode state-of-charge control suppresses the difference in battery state-of-charge between battery packs by adjusting the parallel circulating current between the battery packs. The controller is designed as follows:

[0064] where K PSOC K is the proportional coefficient of the battery differential mode state of charge control method, which is the same as the proportional coefficient of the battery common mode state of charge control method; ISOC is the integral coefficient of the battery differential mode state of charge control method, which is the same as the proportional coefficient of the battery common mode state of charge control method.

[0065] Preferably, in the common DC bus voltage control, the controller is designed as follows:

[0066] where K PCS K is the proportional coefficient of the common DC bus voltage control method, ICS is the integral coefficient of the common DC bus voltage control method, v csr is the common DC bus voltage reference value.

[0067] Preferably, in the parallel DC bus voltage control, the controller is designed as follows:

[0068] where K PCP K is the proportional coefficient of the parallel DC bus voltage control method, ICP is the integral coefficient of the parallel DC bus voltage control method.

[0069] According to a third aspect of the present invention, there is provided a control terminal comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so as to enable the at least one processor to execute the control method for the battery energy storage parallel balancing converter topology.

[0070] Compared with the prior art, the embodiments of the present invention have at least one of the following beneficial effects:

[0071] The battery energy storage parallel balancing converter topology in the embodiments of the present invention is designed to connect a series-type battery energy storage parallel balancing converter in series with a battery pack. This topology allows only a small amount of power to flow through the converter during battery charging and discharging, reducing the converter's capacity requirements while also lowering transmission efficiency. Furthermore, this topology design features a small number of power devices and high power density.

[0072] The control method for the battery energy storage parallel balancing converter topology in the embodiment of the present invention can reduce the filter inductance value, the common DC bus capacitance value and the parallel DC bus capacitance value; the energy storage parallel balancing converter improves efficiency, increases power density and reduces cost on the basis of realizing parallel circulation and active regulation of charge and discharge power between each battery group. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0074] FIG1 is a schematic diagram of a topology of an energy storage parallel balanced converter according to an embodiment of the present invention;

[0075] FIG2 is a schematic diagram of a topology of a parallel balanced converter for battery energy storage in a preferred embodiment of the present invention;

[0076] FIG3 is a schematic diagram of a multi-branch equivalent topology of an energy storage parallel balanced converter in a preferred embodiment of the present invention;

[0077] FIG4 is a schematic diagram of a single-branch equivalent topology of an energy storage parallel balanced converter in a preferred embodiment of the present invention;

[0078] FIG5 is a schematic diagram of a single-branch equivalent topology mode of an energy storage parallel balanced converter in a preferred embodiment of the present invention;

[0079] FIG6 is a schematic diagram of a second single-branch equivalent topology mode of an energy storage parallel balanced converter in a preferred embodiment of the present invention;

[0080] FIG7 is a schematic diagram of three single-branch equivalent topology modes of an energy storage parallel balanced converter in a preferred embodiment of the present invention;

[0081] FIG8 is a schematic diagram of a fourth single-branch equivalent topology mode of an energy storage parallel balanced converter in a preferred embodiment of the present invention;

[0082] FIG9 is a control block diagram of a method for controlling charge and discharge power of an energy storage parallel balanced converter in a preferred embodiment of the present invention;

[0083] FIG10 is a control block diagram of a parallel circulating current control method for energy storage parallel balanced converters in a preferred embodiment of the present invention;

[0084] FIG11 is a control block diagram of a method for controlling a common-mode state of charge of batteries of an energy storage parallel balancing converter in a preferred embodiment of the present invention;

[0085] FIG12 is a control block diagram of a battery differential mode state of charge control method for an energy storage parallel balancing converter in a preferred embodiment of the present invention;

[0086] FIG13 is a control block diagram of a common DC bus voltage control method for energy storage parallel balanced conversion in a preferred embodiment of the present invention;

[0087] FIG14 is a control block diagram of a parallel DC bus voltage control method for energy storage parallel balanced converters in a preferred embodiment of the present invention;

[0088] FIG15 is a voltage waveform diagram of a single branch of an energy storage parallel balanced converter in one cycle in a preferred embodiment of the present invention;

[0089] FIG16 is a current waveform diagram of a single branch of an energy storage parallel balanced converter in one cycle in a preferred embodiment of the present invention;

[0090] FIG17 is a diagram showing simulated voltage and current waveforms of an energy storage parallel balanced converter in a preferred embodiment of the present invention.

[0091] In the figure, 101 is a parallel balancing converter for series battery energy storage, 102 is a main converter, 103 is a filter inductor, 104 is a small-capacity DC / DC converter, 105 is a DC bus capacitor, 106 is a DC / AC converter or a DC / DC converter, 107 is a parallel stabilizing capacitor, and 108 is a battery pack.

[0092] In the figure, 201 is a preferred structure of a parallel balancing converter with series battery energy storage, 202 is a preferred structure of a main converter, 203 is a filter inductor, 204 is a small-capacity DC / DC converter using a Boost topology, 205 is a DC bus capacitor, 206 is a preferred structure of a DC / AC converter using a two-level topology, 207 is a parallel stabilizing capacitor, and 208 is a battery pack. DETAILED DESCRIPTION

[0093] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several variations and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0094] This invention improves upon the existing centralized parallel energy storage converter topology by adding a small-capacity, low-cost parallel balancing converter for series battery storage, connected in series with different battery packs to form a series power regulation structure. Furthermore, optimized modulation and control methods are employed to reduce filter inductance and DC bus capacitance.

[0095] As shown in FIG1 , in one embodiment, a battery energy storage parallel balancing converter topology includes a series battery energy storage parallel balancing converter 101 , a main converter 102 , and multiple groups of filter inductors 103 ;

[0096] The main converter is composed of a DC / AC converter or a DC / DC converter 106 and a parallel stabilizing capacitor 107. The input side of the DC / AC converter or the DC / AC converter 106 is connected in parallel with the parallel stabilizing capacitor 107. The output side of the DC / AC converter is connected to an AC source and load, while the output side of the DC / DC converter is connected to a DC source and load.

[0097] The 101 series-type battery energy storage parallel balancing converter consists of multiple groups of small-capacity DC / DC converters 104 and a common DC bus capacitor 105. The output sides of all small-capacity DC / DC converters 104 are connected in parallel via the common DC bus capacitor 105 to form a common DC bus. The input side of one group of small-capacity DC / DC converters 104 in the series-type battery energy storage parallel balancing converter is connected in series with the input side of the main converter 102, while the input sides of the other DC / DC converters are connected in series with the battery pack via a filter inductor. A small-capacity DC / DC converter refers to a DC / DC converter whose capacity is much smaller than the rated charge and discharge power of the battery pack.

[0098] In this topology, only a small portion of the power passes through the converter during the battery charging and discharging process. The converter has a small capacity and low transmission efficiency, few power devices, and high power density.

[0099] In order to improve the regulation efficiency, in a preferred embodiment, each battery group is connected in parallel through a series battery energy storage parallel balancing converter to form a parallel energy storage system, which actively suppresses the parallel circulation current between the battery groups; each battery group and the main converter are connected in series through a series battery energy storage parallel balancing converter and a filter inductor to form a series power regulation structure, which actively regulates the charge and discharge current of the battery group.

[0100] Furthermore, the parallel circulating current between the battery packs is suppressed by adjusting the input voltage difference of the DC / DC converters connected between the battery packs; and the charge and discharge current of the battery pack is adjusted by adjusting the input voltage of the main converter.

[0101] Furthermore, the filter inductor suppresses the harmonics of the charge and discharge currents of each battery pack, preventing the increased losses and accelerated aging caused by repeated charge and discharge. The common DC bus capacitor in the parallel balancing converter for series-connected battery energy storage maintains the common DC bus voltage stability and suppresses common DC bus voltage harmonics. The parallel stabilizing capacitor in the main converter maintains the parallel DC bus voltage stability and suppresses the parallel branch bus voltage harmonics.

[0102] Furthermore, the filter inductor and the input inductor of the small-capacity DC / DC converter of the series-type battery energy storage parallel balancing converter can be integrated; the common DC bus capacitor of the series-type battery energy storage parallel balancing converter and the output capacitor of the small-capacity DC / DC converter can be integrated; the parallel stabilizing capacitor of the main converter and the input capacitor of the DC / DC converter or DC / AC converter can be integrated.

[0103] Based on the series-type battery energy storage parallel balancing converter and the main converter in the above embodiment, a preferred embodiment provides optional preferred topological structures. Specifically, the topology of the small-capacity DC / DC converter in the series-type battery energy storage parallel balancing converter includes topologies such as Buck, Boost, and Buck-Boost; the topology of the DC / AC converter in the main converter includes two-level topologies, three-level topologies such as NPC and flying capacitor types, and multi-level topologies; the topology of the DC / DC converter in the main converter includes topologies such as DAB and LLC.

[0104] Taking a series-type battery energy storage parallel balancing converter based on the Boost topology as an example, in a preferred embodiment, a preferred structure of a battery energy storage parallel balancing converter topology is provided, as shown in FIG2 , 201 is a preferred structure of a series-type battery energy storage parallel balancing converter, and 202 is a preferred structure of a main converter. Among them, the series-type battery energy storage parallel balancing converter includes multiple groups of small-capacity DC / DC converters 204 and DC bus voltage stabilizing capacitors 205 using the Boost topology. Each group of Boost topology consists of two fully controlled devices. One group of Boost topology input sides is connected in series with the main converter, and the other Boost topology input sides are connected in series with each battery group 208 through a filter inductor 203. All Boost topology output sides are connected in parallel through the DC bus to adjust the voltage between each port. The DC bus capacitor 205 is used to maintain the common DC bus voltage and filter out voltage harmonics to achieve stable operation of the device. The fully controlled device uses MOSFET or IGBT. The main converter is composed of a DC / AC converter or a DC / DC converter 206 and a parallel stabilizing capacitor 207. The input side of the DC / AC converter or the DC / AC converter 206 and the parallel stabilizing capacitor 207 are connected in parallel. The output side of the DC / AC converter is connected to an AC source and load, and the output side of the DC / DC converter is connected to a DC source and load.

[0105] To achieve low-cost, high-efficiency, and high-power-density energy storage in a battery energy storage parallel balancing converter topology, a preferred embodiment provides the operating principle of an energy storage parallel balancing converter, including: a multi-branch energy storage parallel balancing converter topology, which can be equivalent to the superposition of multiple single-branch energy storage parallel balancing converters. When the DC bus capacitor, shunt stabilizing capacitor, and filter inductor are properly designed, the DC bus capacitor voltage, shunt stabilizing capacitor voltage, and filter inductor current ripple are controlled to a relatively small range during operation. Therefore, the DC bus capacitor voltage ripple, shunt stabilizing capacitor voltage ripple, and filter inductor current ripple can be ignored during analysis without affecting the basic operating principle.

[0106] Furthermore, in a specific implementation, taking the Boost topology as an example, the multi-branch energy storage parallel balanced converter topology and the single-branch energy storage parallel balanced converter topology are shown in Figures 3 and 4 respectively, wherein the series battery energy storage parallel balanced converter of the single-branch energy storage parallel balanced converter topology includes two groups of Boost topologies and DC bus capacitors. Each group of Boost topologies consists of two fully controlled devices (such as MOSFET or IGBT). One group of Boost topology input side is connected in series with the main converter, and the other group of Boost topology input side is connected in series with the battery pack through a filter inductor. The two Boost topology output sides are connected in parallel through a common DC bus, thereby regulating the voltage between each port. The DC bus capacitor is connected in parallel to the common DC bus to maintain the common DC bus voltage, while filtering out voltage harmonics to achieve stable operation of the device.

[0107] Based on the single-branch energy storage parallel balanced converter topology in the above embodiment, in a preferred embodiment, it is pointed out that its working mode includes four working modes.

[0108] Mode 1: Series battery energy storage parallel balanced converter switches S1 and S n1 Turn on, switches S2 and S n2 When the DC bus capacitor is turned off, it neither charges nor discharges, as shown in Figure 5. The charging and discharging power starts from the parallel voltage stabilizing capacitor and passes through the series battery energy storage parallel balancing converter switches S1 and S2. n1 , filter inductor L and battery pack back to the parallel voltage stabilizing capacitor to form a loop.

[0109] At this time, the time domain expression of charge and discharge power is:

[0110] Where L is the filter inductor, i lk , k=1,2…, n is the charge and discharge power of the kth battery group, R L is the internal resistance of the filter inductor, R E is the internal resistance of the battery pack, v cp is the voltage of the parallel stabilizing capacitor, e k is the voltage of the kth battery pack.

[0111] Mode 2: Series battery energy storage parallel balanced converter switches S1 and S n2 Turn on, switches S2 and S n1 Turn off and charge the DC bus capacitor, as shown in Figure 6. The charging and discharging power starts from the parallel voltage stabilizing capacitor and passes through the series type battery energy storage parallel balancing converter switch S1, the DC bus capacitor, the series type battery energy storage parallel balancing converter switch S n2 , filter inductor L and battery pack back to the parallel voltage stabilizing capacitor to form a loop.

[0112] At this time, the time domain expression of charge and discharge power is:

[0113] where v cs is the DC bus capacitor voltage.

[0114] Mode 3 [t3-t4], series battery energy storage parallel balancing converter switches S2 and S n2 Turn on, switches S1 and S n1 When the DC bus capacitor is turned off, it neither charges nor discharges, as shown in Figure 7. The charging and discharging power starts from the parallel voltage stabilizing capacitor and passes through the series battery energy storage parallel balancing converter switches S2 and S n2 , filter inductor L and battery pack back to the parallel voltage stabilizing capacitor to form a loop.

[0115] At this time, the time domain expression of charge and discharge power is:

[0116] Mode 4: Series battery energy storage parallel balanced converter switches S2 and S n1 Turn on, switches S1 and S n2 Shut down and put the parallel voltage stabilizing capacitor into operation, as shown in Figure 8. The charging and discharging power starts from the parallel voltage stabilizing capacitor and passes through the series type battery energy storage parallel balancing converter switch S2, DC capacitor, S n1 , filter inductor L and battery pack back to the parallel voltage stabilizing capacitor to form a loop.

[0117] At this time, the time domain expression of charge and discharge power is:

[0118] Of the four modes mentioned above, only one of mode 2 and mode 4 appears in one switching cycle. Mode 2 is the charging of the DC bus capacitor, and mode 4 is the discharging of the DC bus capacitor. The voltage and current waveforms of each mode are shown in Figures 15 and 16.

[0119] It is worth noting that the present invention does not limit the operating mode. In other embodiments, other modal analyses with the same principle can be performed, that is, the single-branch energy storage parallel balanced converter topology can also form other operating modes by controlling the switch.

[0120] In order to achieve low cost, high efficiency and excellent power density energy storage of the battery energy storage parallel balancing converter topology, in a preferred embodiment, its working principle is elaborated in detail, including the average (total) charging and discharging current expression, the parallel circulating current expression, the DC bus capacitor voltage expression, the parallel stabilizing capacitor voltage expression, the battery state of charge (SOC) expression, and the modal current waveform of the working principle.

[0121] The complex frequency domain expression of the average (total) charge and discharge current is:

[0122] in is the average value of the charge and discharge power switching cycle, <v cp (t)> T is the average value of the shunt stabilizing capacitor voltage switching period, is the average value of the common-mode voltage switching cycle of the battery pack, is the average value of the switching period of the common-mode switching function of the small-capacity DC / DC converter connected to the battery pack, <s> T is the average value of the switching period of the switching function of the small-capacity DC / DC converter connected to the main converter, <v cs (t)> T is the average value of the DC bus capacitor voltage during the switching cycle.

[0123] The complex frequency domain expression of the parallel differential mode current is:

[0124] Among them <4s k > T is the average switching period of the differential mode switching function of the small capacity DC / DC converter connected to the kth battery pack, <4i lk > T is the average value of the switching cycle of the parallel circulating current of the kth group of filter inductors, <4e k > T is the average value of the differential mode voltage switching cycle of the kth battery pack.

[0125] The complex frequency domain expression of the DC bus capacitor voltage is:

[0126] Among them C S is the DC bus capacitance value.

[0127] The complex frequency domain expression of the parallel stabilizing capacitor voltage is:

[0128] Among them C P is the parallel stabilizing capacitor value,<i(t)> T It is the average value of the main converter current switching cycle.

[0129] The battery state of charge (SOC) expression includes the battery common mode state of charge (SOC) expression and the battery differential mode state of charge (SOC) expression.

[0130] The complex frequency domain expression of the battery common-mode state of charge (SOC) is:

[0131] where Q r is the rated charge of the battery pack, is the average value of the common-mode state-of-charge switching cycle of the battery pack.

[0132] The complex frequency domain expression of the battery differential mode state of charge (SOC) is:

[0133] Where <ΔSOC k (t)> T is the average value of the differential mode state of charge switching cycle of the kth battery group.

[0134] Based on the same inventive concept, the battery energy storage parallel balanced converter topology described in the above embodiments further utilizes optimized modulation and control methods to reduce filter inductance and DC bus capacitance. In a preferred embodiment, a control method for the battery energy storage parallel balanced converter topology is provided, specifically including charge and discharge power control, parallel circulating current control, battery state of charge control, energy storage parallel balanced converter DC bus voltage control, and parallel DC bus voltage control.

[0135] The charge and discharge power control method adjusts the average (total) charge and discharge current power of all battery packs by adjusting the parallel DC bus voltage. In a preferred embodiment, the controller can be designed as follows:

[0136] The control block diagram is shown in Figure 9.

[0137] where K PI is the charge and discharge power control proportional coefficient, K II is the integral coefficient of the charge and discharge power control method, i Lref is the reference value of charge and discharge power, v cpr is the DC bus capacitor voltage reference value.

[0138] It should be noted that the present invention is not limited to the charge and discharge power control method. In other embodiments, other methods of regulating the average (total) charge and discharge current of all battery packs by regulating the voltage of the parallel stabilizing capacitor can be used.

[0139] The parallel circulating current control method adjusts the parallel circulating current between each battery pack by adjusting the differential mode switching function between each small capacity DC / DC converter of the parallel balancing converter of the series battery energy storage. In a preferred embodiment, the controller can be designed as follows:

[0140] The control block diagram is shown in Figure 10.

[0141] where K PI K is the proportional coefficient of the parallel circulation control method, which is the same as the proportional coefficient of the charge and discharge power control method; II is the integral coefficient of the charge and discharge power control method, which is the same as the integral coefficient of the charge and discharge power control method, Δi lk is the reference value of the parallel circulating current of the kth group of filter inductors.

[0142] It is worth noting that the present invention is not limited to the parallel circulating current control method. In other implementations, other parallel circulating current control methods with the same principle may be used, namely, other methods that regulate the parallel circulating current between battery packs by adjusting the differential mode switching function between the small-capacity DC / DC converters of the parallel balancing converters of the series-connected battery energy storage.

[0143] The battery state of charge control method adjusts the state of charge (SOC) of each battery pack by adjusting the charge and discharge power and the parallel circulating current, including a battery common-mode state of charge control method and a battery differential-mode state of charge control method.

[0144] The battery common-mode state of charge control method adjusts the average (total) battery state of charge by adjusting the average (total) charge and discharge current of all battery packs. In a preferred embodiment, the controller can be designed as follows:

[0145] The control block diagram is shown in Figure 11.

[0146] where K PSOC K is the proportional coefficient of the battery common mode state of charge control method, ISOC is the integral coefficient of the battery common mode state of charge control method, SOC r It is the reference value of the battery pack state of charge.

[0147] The battery common-mode state of charge control method suppresses the difference in battery state of charge between battery packs by adjusting the parallel circulating current between the battery packs. In a preferred embodiment, the controller can be designed as follows:

[0148] The control block diagram is shown in Figure 12.

[0149] where K PSOC K is the proportional coefficient of the battery differential mode state of charge control method, which is the same as the proportional coefficient of the battery common mode state of charge control method; ISOC It is the integral coefficient of the battery differential mode state of charge control method, which is the same as the proportional coefficient of the battery common mode state of charge control method.

[0150] It is worth noting that the present invention is not limited to the battery state of charge control method. In other embodiments, other battery state of charge control methods with the same principle may be adopted, that is, other methods that adjust the state of charge (SOC) of each battery pack by adjusting the charge and discharge power and parallel circulation current.

[0151] The common DC bus voltage control method adjusts the common DC bus voltage by adjusting the common mode switching function of all small-capacity DC / DC converters of the parallel balanced converters of the series-connected battery energy storage. In a preferred embodiment, the controller can be designed as follows:

[0152] The control block diagram is shown in Figure 13.

[0153] where K PCS is the proportional coefficient of the common DC bus voltage control method, K ICS is the integral coefficient of the common DC bus voltage control method, v csr is the common DC bus voltage reference value.

[0154] It is worth noting that the present invention is not limited to the common DC bus voltage control method. In other implementations, other common DC bus voltage control methods with the same principle may be adopted, that is, other methods for adjusting the common DC bus voltage by adjusting the common-mode switching function of all small-capacity DC / DC converters of the series-connected battery energy storage parallel balancing converter.

[0155] The parallel DC bus voltage control method adjusts the parallel DC bus voltage by adjusting the main converter switching function. In a preferred embodiment, the controller can be designed as follows:

[0156] The control block diagram is shown in Figure 14.

[0157] where K PCP K is the proportional coefficient of the parallel DC bus voltage control method, ICP is the integral coefficient of the parallel DC bus voltage control method.

[0158] It is worth noting that the present invention is not limited to the parallel DC bus voltage control method. In other embodiments, other parallel DC bus voltage control methods with the same principle may be adopted, that is, other methods for regulating the parallel DC bus voltage by adjusting the main converter switching function.

[0159] The above embodiment improves efficiency, increases power density and reduces cost based on the energy storage parallel balancing converter realizing parallel circulation and active regulation of charge and discharge power among the battery packs.

[0160] Based on the same inventive concept, a control terminal is provided in one embodiment, comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the control method of the battery energy storage parallel balancing converter topology.

[0161] Through a carefully designed topology and control method, the converter in the above embodiment successfully constructs a low-cost, high-efficiency, high-power-density energy storage parallel balanced converter. To verify its performance advantages, a simulation experiment was conducted on a specific embodiment.

[0162] MATLAB / Simulink software was used to build a preferred topology of the energy storage parallel balanced converter shown in Figure 2. Simulation verification was performed on this topology. The simulation parameters are shown in Table 1, and the simulation waveforms are shown in Figure 17.

[0163] Table 1: Parallel current sharing topology simulation parameters

[0164] FIG17 a) is a waveform diagram of the filter inductor current connected to the first battery pack of a preferred embodiment of the energy storage parallel balancing converter according to the present invention, which is consistent with the waveform of the working principle; the average current is 50A, which is consistent with the reference value; the current ripple is less than 0.5A, which is consistent with the design value;

[0165] FIG17 b) is a waveform diagram of the filter inductor current connected to the second battery pack of a preferred embodiment of the energy storage parallel balancing converter according to the present invention, which is consistent with the waveform of the working principle; the average current is 50A, which is consistent with the reference value; the current ripple is less than 0.5A, which is consistent with the design value;

[0166] FIG17 c) is a waveform diagram of the filter inductor current connected to the third battery pack of a preferred embodiment of the energy storage parallel balancing converter according to the present invention, which is consistent with the waveform of the working principle; the average current is 50A, which is consistent with the reference value; the current ripple is less than 0.5A, which is consistent with the design value;

[0167] Figure 17d) is a DC bus capacitor voltage waveform diagram of a preferred embodiment of the energy storage parallel balancing converter according to the present invention, which is consistent with the operating principle waveform; the average voltage is 20V, which is consistent with the reference value; the current ripple is less than 0.1V, which is consistent with the design value;

[0168] The above examples prove that the topology, basic operating principle and control method of the energy storage parallel balancing converter implemented in this example are feasible and effective, and can realize the active regulation of parallel circulation current and charging and discharging power, thereby reducing volume and cost and improving efficiency and power density.

[0169] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various modifications or variations within the scope of the claims without affecting the essence of the present invention. The above preferred features may be used in any combination as long as they do not conflict with each other.

[0170] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various modifications or variations within the scope of the claims without affecting the essence of the present invention. The above preferred features may be used in any combination as long as they do not conflict with each other.< / s> < / s>

Claims

1. A battery energy storage parallel balanced converter topology, characterized in that: It includes a series battery energy storage parallel balancing converter, a main converter and multiple groups of filter inductors; The main converter includes a DC / AC converter and a parallel voltage-stabilizing capacitor, or includes a DC / DC converter and a parallel voltage-stabilizing capacitor; the DC / AC converter or the DC / AC converter input side is connected in parallel with the parallel voltage-stabilizing capacitor, the DC / AC converter output side is connected to an AC source and load, and the DC / DC converter output side is connected to a DC source and load; The series-type battery energy storage parallel balancing converter includes multiple groups of small-capacity DC / DC converters and common DC bus capacitors; the output sides of all small-capacity DC / DC converters are connected in parallel through the common DC bus capacitor to form a common DC bus; the input side of one group of small-capacity DC / DC converters is connected in series with the input side of the main converter, and the input sides of other groups of small-capacity DC / DC converters are connected in series with the battery group through filter inductors; wherein the capacity of the small-capacity DC / DC converter is less than the charge and discharge power of the connected battery group.

2. A battery energy storage parallel balanced converter topology according to claim 1, characterized in that: The topology of the small-capacity DC / DC converter in the series-type battery energy storage parallel balancing converter includes Buck, Boost and Buck-Boost; the topology of the DC / AC converter in the main converter includes two-level topology, three-level topology and multi-level topology, among which the three-level topology includes NPC type and flying capacitor type; the topology of the DC / DC converter in the main converter includes DAB and LLC.

3. The battery energy storage parallel balanced converter topology according to claim 1, characterized in that: The battery groups are connected in parallel through the series-type battery energy storage parallel balancing converter to form a parallel energy storage system, which actively suppresses the parallel circulation current between the battery groups; each battery group and the main converter are connected in series through the series-type battery energy storage parallel balancing converter and the filter inductor to form a series power regulation structure, which actively regulates the charge and discharge current of the battery group.

4. A battery energy storage parallel balanced converter topology according to claim 3, characterized in that: By adjusting the input voltage difference of the DC / DC converter in the series battery energy storage parallel balancing converter connected between the battery groups, the parallel circulating current between the battery groups is suppressed; and by adjusting the input voltage of the main converter, the charge and discharge current of the battery group is adjusted.

5. The battery energy storage parallel balanced converter topology according to claim 3, characterized in that: The filter inductor suppresses the harmonics of the charging and discharging currents of each battery pack; the common DC bus capacitor in the series battery energy storage parallel balancing converter maintains the stability of the common DC bus voltage and suppresses the common DC bus voltage harmonics; the parallel stabilizing capacitor in the main converter maintains the stability of the parallel DC bus voltage and suppresses the parallel branch bus voltage harmonics.

6. A battery energy storage parallel balanced converter topology according to claim 5, characterized in that: The common DC bus voltage, the shunt stabilizing capacitor voltage, and the filter inductor current ripple are designed to be within a preset range during operation.

7. The battery energy storage parallel balanced converter topology according to claim 3, characterized in that: The filter inductor and the input inductor of the small-capacity DC / DC converter of the series-type battery energy storage parallel balancing converter can be integrated; the common DC bus capacitor of the series-type battery energy storage parallel balancing converter and the output capacitor of the small-capacity DC / DC converter can be integrated; the parallel stabilizing capacitor of the main converter and the input capacitor of the DC / DC converter or DC / AC converter can be integrated.

8. The battery energy storage parallel balanced converter topology according to claim 5, characterized in that: The working principle of the battery energy storage parallel balancing converter topology is: the multi-branch energy storage parallel balancing converter topology is equivalent to the superposition of multiple single-branch energy storage parallel balancing converters; among them, the multi-branch energy storage parallel balancing converter topology includes multiple groups of small-capacity DC / DC converters, and the single-branch energy storage parallel balancing converter only contains one group of small-capacity DC / DC converters.

9. A battery energy storage parallel balanced converter topology according to claim 8, characterized in that: In the single-branch energy storage parallel balanced converter topology, the series battery energy storage parallel balanced converter includes two groups of Boost topologies and a common DC bus capacitor; each group of Boost topologies includes two groups of fully controlled devices and an input inductor, one group of fully controlled devices is S1, S2, and the other group of fully controlled devices is S n1 ,S n2 ; The Boost topology input side of the fully controlled devices S1 and S2 is connected in series with the main converter, and the other group of fully controlled devices is S n1 ,S n2 The Boost topology input side is connected in series with the battery pack through the filter inductor, and the two Boost topology output sides are connected in parallel through a common DC bus to adjust the voltage between each port; the common DC bus capacitor is connected in parallel to the common DC bus to maintain the voltage and filter out voltage harmonics to achieve stable operation.

10. A battery energy storage parallel balanced converter topology according to claim 9, characterized in that: The first operating mode of the single-branch energy storage parallel balanced converter topology is: Series battery energy storage parallel balancing converter switches S1 and S n1 Turn on, switches S2 and S n2 When turned off, the common DC bus capacitor is neither charged nor discharged; The charging and discharging power starts from the parallel voltage stabilizing capacitor and passes through the series type battery energy storage parallel balancing converter switches S1 and S n1 , the filter inductor L and the battery pack return to the parallel voltage stabilizing capacitor to form a loop; At this time, the time domain expression of charge and discharge power is: Where L is the filter inductor, i lk , k=1,2…, n is the charge and discharge power of the kth battery group, R L is the internal resistance of the filter inductor, R E is the internal resistance of the battery pack, v cp is the voltage of the parallel stabilizing capacitor, e k is the voltage of the kth battery pack; The second operating mode of the single-branch energy storage parallel balanced converter topology is: Series battery energy storage parallel balancing converter switches S1 and S n2 Turn on, switches S2 and S n1 Shut down, the common DC bus capacitor is charged; The charging and discharging power starts from the parallel voltage stabilizing capacitor and passes through the series type battery energy storage parallel balancing converter switch S1, the common DC bus capacitor, the series type battery energy storage parallel balancing converter switch S n2 , the filter inductor L and the battery pack return to the parallel voltage stabilizing capacitor to form a loop; At this time, the time domain expression of charge and discharge power is: where v cs is the common DC bus voltage; The third operating mode of the single-branch energy storage parallel balanced converter topology is: Series battery energy storage parallel balancing converter switches S2 and S n2 Turn on, switches S1 and S n1 When turned off, the common DC bus capacitor is neither charged nor discharged; The charging and discharging power starts from the parallel voltage stabilizing capacitor and passes through the series battery energy storage parallel balancing converter switches S2 and S n2 , the filter inductor L and the battery pack return to the parallel voltage stabilizing capacitor to form a loop; At this time, the time domain expression of charge and discharge power is: The fourth operating mode of the single-branch energy storage parallel balanced converter topology is: Series battery energy storage parallel balancing converter switches S2 and S n1 Turn on, switches S1 and S n2 Turn off and put in parallel voltage stabilizing capacitor; The charging and discharging power starts from the parallel voltage stabilizing capacitor and passes through the series battery energy storage parallel balancing converter switch S2, DC capacitor, S n1 , the filter inductor L and the battery pack return to the parallel voltage stabilizing capacitor to form a loop; At this time, the time domain expression of charge and discharge power is:

11. A battery energy storage parallel balanced converter topology according to claim 9, characterized in that: The operating principle of the battery energy storage parallel balancing converter topology is described by multiple expressions, including: total or average charge and discharge current expression, parallel circulating current expression, common DC bus voltage expression, parallel stabilizing capacitor voltage expression, battery state of charge expression, and modal current waveform; The complex frequency domain expression of the average or total charge and discharge current is: in is the average value of the charge and discharge power switching cycle, <v cp (t)> T is the average value of the shunt stabilizing capacitor voltage switching period, is the average value of the common-mode voltage switching cycle of the battery pack, is the average value of the switching period of the common-mode switching function of the small-capacity DC / DC converter connected to the battery pack, <s> T is the average value of the switching period of the switching function of the small-capacity DC / DC converter connected to the main converter, <v cs (t)> T is the average value of the common DC bus voltage switching period;< / s> <s> The complex frequency domain expression of the parallel differential mode current is: Where <Δs k > T is the average switching period of the differential mode switching function of the small capacity DC / DC converter connected to the kth battery pack, <Δi lk > T is the average value of the switching cycle of the kth group of filter inductors in parallel circulation, <Δe k > T is the average value of the differential mode voltage switching cycle of the kth battery pack; The complex frequency domain expression of the common DC bus voltage is: Among them C S is the common DC bus capacitance value; The complex frequency domain expression of the parallel stabilizing capacitor voltage is: Among them C P is the parallel stabilizing capacitor value,<i(t)> T is the average value of the main converter current switching cycle; The battery state of charge (SOC) expression includes the battery common mode state of charge (SOC) expression and the battery differential mode state of charge (SOC) expression; The complex frequency domain expression of the battery common mode state of charge SOC is: where Q r is the rated charge of the battery pack, is the average value of the common-mode state-of-charge switching cycle of the battery pack; The complex frequency domain expression of the battery differential mode state of charge SOC is: Where <ΔSOC k (t)> T is the average value of the differential mode state of charge switching cycle of the kth battery group.

12. A control method for a battery energy storage parallel balanced converter topology, characterized in that: include: Charge and discharge power control: adjust the average or total charge and discharge current of all battery packs by adjusting the parallel DC bus voltage; Parallel circulation control: By adjusting the differential mode switching function between each small-capacity DC / DC converter of the parallel balancing converter of the series-connected battery energy storage, the parallel circulation current between each battery group is adjusted; Battery state of charge control: adjust the state of charge (SOC) of each battery pack by adjusting the charge and discharge power and parallel circulation current; Common DC bus voltage control: The common DC bus voltage is regulated by adjusting the common-mode switching function of all small-capacity DC / DC converters in the parallel balancing converters of the series-connected battery energy storage. Parallel DC bus voltage control: The parallel DC bus voltage is regulated by adjusting the main converter switching function.

13. A control method for a battery energy storage parallel balanced converter topology according to claim 12, characterized in that: In the charge and discharge power control, the controller is designed as: where K PI is the proportional coefficient of the charge and discharge power control method, K II is the integral coefficient of the charge and discharge power control method, i Lref is the reference value of charge and discharge power, v cpr is the parallel DC bus voltage reference value.

14. A control method for a battery energy storage parallel balanced converter topology according to claim 12, characterized in that: In the parallel circulation control, the controller is designed as follows: where K PI K is the proportional coefficient of the parallel circulation control method, which is the same as the proportional coefficient of the charge and discharge power control method; II is the integral coefficient of the charge and discharge power control method, which is the same as the integral coefficient of the charge and discharge power control method, Δi lk is the reference value of the parallel circulating current of the kth group of filter inductors.

15. The control method of a battery energy storage parallel balanced converter topology according to claim 12, characterized in that: The battery state of charge control includes battery common mode state of charge control and battery differential mode state of charge control; The battery common mode state of charge control adjusts the average or total state of charge of the battery by adjusting the average charge and discharge current of all battery packs. The controller is designed as follows: where K PSOC K is the proportional coefficient of the battery common mode state of charge control method, ISOC is the integral coefficient of the battery common mode state of charge control method, SOC r is the reference value of the battery pack state of charge; The battery common-mode state-of-charge control suppresses the difference in battery state-of-charge between battery packs by adjusting the parallel circulating current between the battery packs. The controller is designed as follows: where K PSOC K is the proportional coefficient of the battery differential mode state of charge control method, which is the same as the proportional coefficient of the battery common mode state of charge control method; ISOC is the integral coefficient of the battery differential mode state of charge control method, which is the same as the proportional coefficient of the battery common mode state of charge control method.

16. A control method for a battery energy storage parallel balanced converter topology according to claim 12, characterized in that: In the common DC bus voltage control, the controller is designed as: where K PCS K is the proportional coefficient of the common DC bus voltage control method, ICS is the integral coefficient of the common DC bus voltage control method, v csr is the common DC bus voltage reference value.

17. The control method of a battery energy storage parallel balanced converter topology according to claim 12, characterized in that: In the parallel DC bus voltage control, the controller is designed as follows: where K PCP K is the proportional coefficient of the parallel DC bus voltage control method, ICP is the integral coefficient of the parallel DC bus voltage control method.

18. A control terminal, characterized in that: include: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the control method of the battery energy storage parallel balancing converter topology according to any one of claims 12 to 17. < / s>

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