Single-phase or multi-phase cascade hybrid H-bridge battery energy storage system, switch unit control state determination method thereof and computer readable storage medium

Abstract

The invention relates to a single-phase or multi-phase cascade hybrid H-bridge battery energy storage system, a switch unit control state determination method thereof and a computer readable storage medium. The system comprises a cascade hybrid H-bridge module and a filter circuit. The cascaded hybrid H-bridge module is connected with an external load or a power grid through a filter circuit; the cascaded hybrid H-bridge module comprises m capacitor H-bridge units and n battery H-bridge units which are cascaded; wherein m is larger than or equal to 1 and smaller than n, and n is larger than or equal to 2; the switching frequency of the capacitor H-bridge unit is in a high-frequency range, and the switching frequency of the battery H-bridge unit is in a low-frequency range. In a low-voltage scene, in order to reduce the total harmonic distortion, a small number of capacitance H-bridge units with high switching frequency can be utilized, and the switching frequency and switching loss of each H-bridge unit do not need to be increased, so that the overall switching frequency and switching loss of the system can be reduced, and the overall system efficiency is improved.

Description

Technical Field

[0001] The present application relates to the technical field of energy storage power supply, and in particular to a single- or multi-phase cascade hybrid H-bridge battery energy storage system, a method for determining a control state of a switch unit thereof, and a computer-readable storage medium. Background Art

[0002] As the proportion of renewable energy in the power generation sector continues to increase, battery energy storage systems are becoming increasingly important. The battery energy storage system (BES) system consists of battery packs, battery management systems (BMS) and power conversion systems (PCS). In large-scale energy storage applications, the cascaded H-Bridge (CHB) topology has attracted much attention as a power conversion system because of its modular design, which facilitates voltage level expansion, reduces power device voltage stress, improves reliability and service life; can generate high-quality voltage waveforms, reduce harmonic content, and reduce filter requirements; can also flexibly adjust energy, and has redundancy functions and other advantages.

[0003] In medium and low voltage scenarios, the number of H-bridge units in a cascaded H-bridge is usually limited. In order to reduce the total harmonic distortion (THD), the existing technology needs to combine the nearest level modulation (NLM) and pulse width modulation (PWM) to control the switches in the H-bridge units. Since the number of H-bridge units in low voltage scenarios is usually limited, the switching frequency and switching loss of the power devices will increase, which will inevitably reduce the overall system efficiency. Summary of the invention

[0004] Based on this, it is necessary to provide a single- or multi-phase cascade hybrid H-bridge battery energy storage system, a method for determining the control state of its switch unit, and a computer-readable storage medium to address the above technical problems.

[0005] In a first aspect, the present application provides a single-phase cascade hybrid H-bridge battery energy storage system, comprising: a cascade hybrid H-bridge module and a filtering circuit; the cascade hybrid H-bridge module is connected to an external load or a power grid through a filtering circuit; the cascade hybrid H-bridge module comprises m cascaded capacitor H-bridge units and n battery H-bridge units; wherein m is greater than or equal to 1 and less than n, and n is greater than or equal to 2 and less than or equal to a first preset value; the switching frequency of the capacitor H-bridge unit is in a high frequency range, and the switching frequency of the battery H-bridge unit is in a low frequency range.

[0006] In a second aspect, the present application further provides a method for determining a control state of a switch unit of one or more multi-phase cascade hybrid H-bridge battery energy storage systems, which is applied to the single-phase cascade hybrid H-bridge battery energy storage system as described in the first aspect, comprising:

[0007] Determine the total output voltage level number of the cascaded hybrid H-bridge module according to the voltage average value of each H-bridge unit in the cascaded hybrid H-bridge module and the bridge arm voltage reference value of the cascaded hybrid H-bridge module;

[0008] Determining a voltage deviation between the n battery H-bridge units and the m capacitor H-bridge units;

[0009] The control state of the switch unit in each H-bridge unit is determined according to the total number of output voltage levels, the bridge arm current of the cascaded hybrid H-bridge module and the voltage deviation.

[0010] In a third aspect, the present application also provides a single- or multi-phase cascade hybrid H-bridge battery energy storage system, comprising a plurality of single-phase cascade hybrid H-bridge battery energy storage systems described in the first aspect, wherein the control state of the switch unit in the system is determined by the method described in the second aspect.

[0011] In a fourth aspect, the present application further provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the method described in the second aspect or any one of its embodiments is implemented.

[0012] In a fifth aspect, the present application further provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the method described in the second aspect or any one of its embodiments is implemented.

[0013] In a sixth aspect, the present application further provides a computer program product, comprising a computer program, which, when executed by a processor, implements the method described in the second aspect or any one of its embodiments.

[0014] In a seventh aspect, the present application also provides a multi-phase cascade hybrid H-bridge battery energy storage system, comprising a plurality of single-phase cascade hybrid H-bridge battery energy storage systems as described in the first aspect, wherein the control state of the switch unit in the system is determined by the method described in the second aspect above.

[0015] The above-mentioned single-phase cascade hybrid H-bridge module includes m cascaded capacitor H-bridge units and n battery H-bridge units, wherein m is greater than or equal to 1 and less than n, and n is greater than or equal to 2; the switching frequency of the capacitor H-bridge unit is in the high frequency range, and the switching frequency of the battery H-bridge unit is in the low frequency range. By setting a large number of battery H-bridge units with low switching frequencies in the cascade hybrid H-bridge module, and setting a small number of capacitor H-bridge units with high switching frequencies, in this way, in a low-voltage scenario, in order to reduce total harmonic distortion, a small number of capacitor H-bridge units with high switching frequencies can be used to achieve it, without increasing the switching frequency and switching loss of each H-bridge unit, thereby reducing the overall switching frequency and switching loss of the system, and improving the overall system efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the drawings required for use in the embodiments or the related technical descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 A schematic diagram of a single-phase cascade hybrid H-bridge battery energy storage system and its submodule topology in one embodiment;

[0018] Figure 2 For an application Figure 1 A flow chart of a method for determining a control state of a switch unit in a single-phase cascade hybrid H-bridge battery energy storage system;

[0019] Figure 3 A control block diagram of a bridge arm voltage reference value of a cascaded hybrid H-bridge module using a dual-loop control strategy;

[0020] Figure 4 A control block diagram for determining the number of output voltage levels of n battery H-bridge units and the modulation ratio of pulse width modulation of the capacitor H-bridge unit;

[0021] Figure 5 A control block diagram for determining the control state of a switch unit of each battery H-bridge unit;

[0022] Figure 6 A schematic diagram of the state of a battery H-bridge unit;

[0023] Figure 7 A control block diagram for determining a control state of a switch unit of a capacitor H-bridge unit;

[0024] Figure 8A schematic diagram showing a comparison between the output voltage of the cascaded hybrid H-bridge module and the output voltage reference in an embodiment of the present application;

[0025] Fig. 9 It is a schematic diagram of the connection state change of the cascaded hybrid H-bridge unit module within two power frequency cycles;

[0026] Fig. 10A It is a schematic diagram of bridge arm voltage tracking;

[0027] Fig. 10B A schematic diagram of voltage balancing of a hybrid H-bridge unit module using the method provided in an embodiment of the present application;

[0028] Fig.11 It is a structural block diagram of a single-phase cascade H-bridge unit capacitor voltage enhancement balancing device;

[0029] Fig.12 is an internal structure diagram of a computer device in one embodiment;

[0030] Fig.13 Schematic diagram of a three-phase cascade hybrid H-bridge battery energy storage system. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0032] In medium and low voltage scenarios, the number of H-bridge units in a cascaded H-bridge is usually limited. In order to reduce the total harmonic distortion (THD), the existing technology needs to combine the nearest level modulation (NLM) and pulse width modulation (PWM) to control the switches in the H-bridge units. Since the number of H-bridge units in low voltage scenarios is usually limited, the switching frequency and switching loss of the power devices will increase, which will inevitably reduce the overall system efficiency.

[0033] In order to solve the above problems, an embodiment of the present application provides a single / multi-phase cascade hybrid H-bridge battery energy storage system, in which a large number of battery H-bridge units with low switching frequency are arranged, and a small number of capacitor H-bridge units with high switching frequency are arranged. In this way, in a low-voltage scenario, in order to reduce the total harmonic distortion, a small number of capacitor H-bridge units with high switching frequency can be used, and there is no need to increase the switching frequency and switching loss of each H-bridge unit, thereby reducing the overall switching frequency and switching loss of the system and improving the overall system efficiency.

[0034] In the embodiment of the present application, the single-phase cascade hybrid H-bridge battery energy storage system provided includes a cascade hybrid H-bridge module and a filter circuit, and the cascade hybrid H-bridge module is connected to an external load or a power grid through the filter circuit; the cascade hybrid H-bridge module includes m cascaded capacitor H-bridge units and n battery H-bridge units; wherein m is greater than or equal to 1 and less than n; n is greater than or equal to 2 and less than or equal to a first preset value; the switching frequency of the capacitor H-bridge unit is in the high frequency range, and the switching frequency of the battery H-bridge unit is in the low frequency range. When constructing the cascade hybrid H-bridge module, the connection order between the m capacitor H-bridge units and the n battery H-bridge units is flexible, and the cascade order of these units can be freely arranged according to the specific application requirements and system architecture without following a fixed order. As long as the H-bridge units are correctly cascaded with each other, the expected functions and performance can be achieved.

[0035] In some embodiments, the first preset value may be set according to an applicable voltage scenario. For example, in a medium or low voltage scenario, the first preset value may be greater than 2 and less than or equal to 10.

[0036] The high frequency range may refer to above kilohertz. Exemplarily, the switching frequency of the capacitor H-bridge unit may be in the kilohertz range, for example, the switching frequency of the capacitor H-bridge unit may be tens of kilohertz.

[0037] The above low frequency range may refer to below kilohertz. For example, the low frequency range may be greater than or equal to twice the load frequency of the load connected to the single-phase cascade hybrid H-bridge battery energy storage system, or 2 to 8 times the traditional power frequency (50 Hz or 60 Hz).

[0038] In some preferred embodiments, the above m is 1. That is, one high-frequency capacitor H-bridge unit and multiple low-frequency capacitor H-bridge units can be set in the cascade hybrid H-bridge module. Only one high-frequency capacitor H-bridge unit can be used to reduce the overall switching frequency and switching loss of the system in an extremely low-cost manner, thereby improving the overall system efficiency.

[0039] In some embodiments, m is 1 and n is 8. That is, one high-frequency capacitor H-bridge unit and eight low-frequency capacitor H-bridge units may be provided in the cascade hybrid H-bridge module.

[0040] For example, Figure 1 The figure shows a single-phase cascade hybrid H-bridge battery energy storage system in an embodiment, which includes a cascade hybrid H-bridge module and a filter circuit. The cascade hybrid H-bridge module includes a plurality of cascaded capacitor H-bridge units and a plurality of battery H-bridge units; the filter circuit includes an inductor L and a capacitor C1; the cascade hybrid H-bridge module is connected to a single-phase AC load 11 (or a power grid) through the filter circuit. The topological structure of the capacitor H-bridge unit is as follows: Figure 1 As shown in (a) of FIG. 1 , an H-bridge structure powered by a capacitor is used to maintain a stable DC voltage level, and its switching frequency is tens of kilohertz. The topology of the battery H-bridge unit is shown in FIG. Figure 1 As shown in (b), it is powered by a battery pack and is designed to store and release energy as needed. Its switching frequency is twice the load frequency. Both types of H-bridge units are composed of four switching units S1, S2, S3, and S4. By accurately controlling the switching states of these switching units, the output voltage of the H-bridge unit can be managed to produce the required level. The topology of the single-phase system is shown in Figure 1 As shown in (c), it is composed of a capacitor H-bridge unit and multiple (n) battery H-bridge units in cascade, and the output voltage of each H-bridge unit is combined into a step-like superimposed voltage waveform (such as Figure 1 (d) in the figure), and then pass through the LC filter (composed of the inductor L and capacitor C1 in the figure) to obtain a standard sine wave (such as Figure 1 (e) in the figure is for single-phase AC load power supply.

[0041] The above-mentioned cascaded hybrid H-bridge module includes m cascaded capacitor H-bridge units and n battery H-bridge units, wherein m is greater than or equal to 1 and less than n; n is greater than or equal to 2 and less than or equal to the first preset value; the switching frequency of the capacitor H-bridge unit is in the high frequency range, such as tens of kilohertz; the switching frequency of the battery H-bridge unit is in the low frequency range, such as 2 times the traditional power frequency (50Hz or 60Hz). In this way, it can be seen that a large number of battery H-bridge units with low switching frequencies are set in the cascaded hybrid H-bridge module, and a small number of capacitor H-bridge units with high switching frequencies are set. In this way, in a low-voltage scenario, in order to reduce total harmonic distortion, a small number of capacitor H-bridge units with high switching frequencies can be used to achieve it, without increasing the switching frequency and switching loss of each H-bridge unit, thereby reducing the overall switching frequency and switching loss of the system and improving the overall system efficiency.

[0042] An embodiment of the present application also provides a method for determining the control state of a switch unit that can be applied to the above-mentioned single-phase cascade hybrid H-bridge battery energy storage system. The method is used to determine the switch state of the switch unit in each H-bridge unit in the cascade hybrid H-bridge module to achieve control of the cascade hybrid H-bridge module so that the total output voltage of all H-bridge units tracks the bridge arm voltage reference value of the cascade hybrid H-bridge module.

[0043] like Figure 2 FIG. 1 is a flow chart of a method for determining a control state of a switch unit applied to the above-mentioned single-phase cascade hybrid H-bridge battery energy storage system, the method comprising:

[0044] S201, determining the total output voltage level number of the cascaded hybrid H-bridge module according to the voltage average value of each H-bridge unit in the cascaded hybrid H-bridge module and the bridge arm voltage reference value of the cascaded hybrid H-bridge module.

[0045] In some embodiments, the capacitor voltage of each capacitor H-bridge unit in the m capacitor H-bridges can be obtained first, and then the capacitor voltage of each battery H-bridge unit in the n capacitor H-bridges can be obtained, and finally the voltage average of the m+n H-bridge units is calculated, that is, the voltage average of each H-bridge unit in the above-mentioned cascaded hybrid H-bridge module is obtained.

[0046] In some embodiments, the bridge arm voltage reference value of the cascaded hybrid H-bridge module can be calculated by an output voltage controller. Specifically, the output voltage controller can adopt a dual-loop control strategy, including an outer voltage loop and an inner current loop. The control block diagram is shown in FIG. Figure 3 shown. Figure 3 FIG. 1 is a control block diagram of a dual-loop control strategy for calculating the bridge arm voltage reference value of a cascaded hybrid H-bridge module. Figure 3 As shown in the figure, the outer voltage loop consists of a load voltage reference and a load voltage value, and generates a bridge arm current reference value through a proportional integral (PI) controller. The inner current loop is responsible for fast current regulation, and the error between the bridge arm current reference value and the bridge arm current is input into another PI controller, and the output is a bridge arm voltage reference value (i.e., the bridge arm voltage reference value of the above-mentioned cascaded hybrid H-bridge module). The bridge arm voltage reference value is used to adjust the state of the capacitor H-bridge unit and the battery H-bridge unit to ensure efficient and reliable operation of the system.

[0047] Among them, the above-mentioned PI controller is a feedback control element composed of proportional and integral parts, and its output is the product of proportional gain and error signal and the sum of integral gain and integral of error signal. The proportional part can make the system respond to errors quickly, and the integral part can eliminate steady-state errors, but excessive proportional gain may lead to overshoot, and excessive integral effect may slow down the response or cause integral saturation. The above-mentioned output voltage controller adopts a dual-loop control strategy. The outer loop voltage loop takes the load voltage reference value and the load voltage value as input, generates the bridge arm current reference value through the PI controller, and pays attention to the stability of the output voltage; the inner loop current loop compares the bridge arm current reference value with the actual value, and the error is output through the PI controller. The bridge arm voltage reference value is used to adjust the state of the capacitor H-bridge unit and the battery H-bridge unit to ensure efficient and reliable operation of the system.

[0048] In the above embodiment, in the process of obtaining the bridge arm voltage reference value, the output voltage controller using the dual-loop control strategy plays an important role. The outer voltage loop takes the load voltage reference value and the load voltage value as input, and generates the bridge arm current reference value through the proportional integral (PI) controller. This link mainly focuses on the stability of the output voltage. By continuously comparing the load expected voltage reference value and the actual load voltage value, the characteristics of the PI controller (the proportional part enables the system to respond quickly to the error, and the integral part can eliminate the steady-state error) are used to generate a suitable bridge arm current reference value, which provides an accurate target value for the subsequent adjustment of the inner current loop, and overall ensures that the output voltage develops in a stable direction. The inner current loop is responsible for fast current regulation, and the error between the bridge arm current reference value and the bridge arm current is input into another PI controller, and the output is the bridge arm voltage reference value. This link plays a key role in ensuring the efficient and reliable operation of the system. By quickly responding to the deviation of the bridge arm current and adjusting it, the current is ensured to be within a reasonable range, avoiding problems such as system failure or reduced efficiency due to abnormal current. At the same time, by working in coordination with the outer voltage loop, the final output bridge arm voltage reference value can more accurately adjust the states of the capacitor H-bridge unit and the battery H-bridge unit, achieving efficient, stable and reliable control of the entire cascaded hybrid H-bridge system.

[0049] S202 : Determine a voltage deviation between the n battery H-bridge units and the m capacitor H-bridge units.

[0050] In some embodiments, the average battery voltage of n battery H-bridge units may be calculated first, then the average capacitor voltage of m capacitor H-bridge units may be calculated, and finally the difference between the average battery voltage and the average capacitor voltage may be calculated to obtain the voltage deviation.

[0051] In some embodiments, the total battery voltage value of n battery H-bridge units, the total capacitor voltage value of m capacitor H-bridge units, and finally the difference between the total battery voltage value and the total capacitor voltage value may be calculated to obtain the voltage deviation value.

[0052] S203 , determining the control state of the switch unit in each H-bridge unit according to the total number of output voltage levels, the bridge arm current and the voltage deviation of the cascaded hybrid H-bridge module.

[0053] In medium and low voltage scenarios, traditional technology needs to combine nearest level modulation (NLM) and pulse width modulation (PWM) to control the switch in the H-bridge unit to reduce THD, but it will increase the switching frequency and switching loss of the power device, reducing the overall system efficiency. The control state determination method shown in Figure 2 proposed in this application, by setting capacitor H-bridge units and battery H-bridge units with different switching frequencies, uses a smaller number of capacitor H-bridge units with higher switching frequencies to achieve the goal of reducing THD, without increasing the switching frequency and switching loss of each H-bridge unit, thereby effectively reducing the overall switching frequency and switching loss of the system, improving the overall system efficiency, and better meeting the requirements for power quality and system performance in medium and low voltage scenarios.

[0054] In the process shown in Figure 2, the total output voltage level is first determined based on the voltage average of each H-bridge unit in the cascaded hybrid H-bridge module and the bridge arm voltage reference value. This step lays the foundation for subsequent precise control. By obtaining the voltage information of different types of H-bridge units (capacitor H-bridge units and battery H-bridge units) and calculating the average value, the current voltage state of the system can be fully understood, and then the accurate total output voltage level is obtained in combination with the bridge arm voltage reference value, so that the system output voltage can be adjusted more accurately toward the desired level state.

[0055] In the above embodiment, in the step of determining the voltage deviation between the n battery H-bridge units and the m capacitor H-bridge units, whether the voltage deviation is obtained by calculating the difference in average values ​​or the difference in total voltage values, it provides a key basis for further fine-tuning the control state of the switch units in each H-bridge unit. According to this voltage deviation, combined with factors such as the total output voltage level number and the bridge arm current, the control state of each switch unit can be determined more accurately, thereby achieving fine adjustment of the output voltage of each H-bridge unit, ensuring that the total output voltage of all H-bridge units can accurately track the bridge arm voltage reference value of the cascaded hybrid H-bridge module, and effectively improving the stability and accuracy of the output voltage.

[0056] In summary, the control state determination method shown in Figure 2 has demonstrated significant beneficial effects in improving system performance, accurately controlling output voltage, and ensuring efficient and reliable operation of the system through the above series of steps and their mutual coordination, and provides strong support for the effective application of cascaded hybrid H-bridge modules in medium and low voltage scenarios.

[0057] In some embodiments, the number of output voltage levels of n battery H-bridge units and the modulation ratio of pulse width modulation of m capacitor H-bridge units can be determined according to the total number of output voltage levels, the bridge arm current of the cascaded hybrid H-bridge module, and the voltage deviation; the control state of the switch unit of each battery H-bridge unit is determined based on the number of output voltage levels of the n battery H-bridge units; and the control state of the switch unit of each capacitor H-bridge unit is determined based on the modulation ratio.

[0058] In some embodiments, the process of determining the number of output voltage levels of n battery H-bridge units and the modulation ratio of pulse width modulation of m capacitor H-bridge units according to the total number of output voltage levels, the bridge arm current and the voltage deviation of the cascaded hybrid H-bridge module may include but is not limited to the following:

[0059] (1) If the product of the voltage deviation and the bridge arm current is greater than 0, the total output voltage level number is rounded down to determine the output voltage level number of the n battery H-bridge units, and the difference between the total output voltage level number and the output voltage level number of the n battery H-bridge units is used as the modulation ratio of the pulse width modulation of the m capacitor H-bridge units.

[0060] (2) If the product of the voltage deviation and the bridge arm current is less than or equal to 0, the total output voltage level number is rounded up to determine the output voltage level number of the n battery H-bridge units, and the difference between the total output voltage level number and the output voltage level number of the n battery H-bridge units is used as the modulation ratio of the pulse width modulation of the m capacitor H-bridge units.

[0061] Figure 4 FIG. 1 is a control block diagram for determining the number of output voltage levels of n battery H-bridge units and the modulation ratio of the pulse width modulation of the capacitor H-bridge unit. Figure 4 As shown, a cascaded hybrid H-bridge module including a capacitor H-bridge and n battery H-bridge units is taken as an example for explanation. Figure 4 In the code, If means if, Else means otherwise, and End if means end.

[0062] Figure 4 In the above, the capacitor voltage Vc in the capacitor H-bridge unit and the battery voltages Vb1, ..., Vbn in the n battery H-bridge units can be averaged to obtain the voltage average value Vaver of each H-bridge unit in the cascaded hybrid H-bridge module, that is, Figure 4Then, the total output voltage level number Nref of the cascaded hybrid H-bridge module is obtained by dividing the bridge arm voltage reference value Vs* of the cascaded hybrid H-bridge module by the capacitor and battery voltage average value Vaver.

[0063] like Figure 4 As shown, the battery voltage average Vbat in the n battery H-bridge units can also be calculated.

[0064] like Figure 4 As shown, after obtaining the total output voltage level number Nref and the battery voltage average value Vbat, the output voltage level number Nbat of the n battery H-bridge units and the modulation ratio Ncap of the pulse width modulation of the capacitor H-bridge unit can be determined.

[0065] The process of determining the number of output voltage levels Nbat of the n battery H-bridge units and the modulation ratio Ncap of the pulse width modulation of the capacitor H-bridge unit may include:

[0066] If sgn(is)*sgn(Vbat-Vc) is greater than 0, then:

[0067] Nbat = floor(Nref);

[0068] Ncap = Nref - floor(Nref);

[0069] When sgn(is) and sgn(Vbat-Vc) are both positive or negative, it is determined that sgn(is)*sgn(Vbat-Vc) is greater than 0.

[0070] If sgn(is)*sgn(Vbat-Vc) is less than or equal to 0, then:

[0071] Nbat = ceil(Nref);

[0072] Ncap = Nref - ceil(Nref);

[0073] When sgn(is) is positive and sgn(Vbat-Vc) is negative, or when sgn(is) is negative and sgn(Vbat-Vc) is positive, it is determined that sgn(is)*sgn(Vbat-Vc) is less than 0. When one of sgn(is) or sgn(Vbat-Vc) is 0, sgn(is)*sgn(Vbat-Vc)=0.

[0074] The above sgn() is a symbolic function, is is Figure 4The bridge arm current is in, Vbat-Vc represents the voltage deviation calculated from the battery voltage mean Vbat and the capacitor voltage Vc. Nbat is an integer. When the nearest level modulation method is applied, the state change frequency of the battery H-bridge unit is twice the grid frequency; Ncap is a decimal between -1 and 1, which is used as the modulation ratio of PWM to facilitate the application of conventional PWM. The sum of Nbat and Ncap is equal to Nref, which realizes the accurate tracking of the bridge arm voltage reference value. floor() is a rounding function, and ceil() is a rounding function.

[0075] In the above embodiment, the output voltage level of the battery H-bridge unit and the modulation ratio of the capacitor H-bridge unit can be accurately determined. By considering the key factor of the product of the voltage deviation and the bridge arm current, it is determined whether the total output voltage level number is rounded up or down, thereby determining the output voltage level number of the battery H-bridge unit and the modulation ratio of the capacitor H-bridge unit. This method makes full use of the key electrical parameter information in the system, so that the determination of the output voltage level number and the modulation ratio is more in line with the actual operating state of the system. Whether the product of the voltage deviation and the bridge arm current is greater than 0 or less than or equal to 0, the level number and the modulation ratio can be accurately allocated, ensuring that the total output voltage can accurately track the bridge arm voltage reference value, effectively reducing the output voltage error and improving the power quality.

[0076] In the above embodiment, the sign function (sgn()) is used to accurately determine the positive and negative relationship between the voltage deviation and the bridge arm current, and combined with the floor function (floor()) and the ceiling function (ceil()), the accurate calculation of the output voltage level number (Nbat) of the battery H-bridge unit and the modulation ratio (Ncap) of the capacitor H-bridge unit under different conditions is realized. Nbat is an integer, which meets the application requirements of the nearest level modulation method, and its relationship with the bridge arm current can further guide the control of the battery H-bridge unit. Ncap, as a decimal between -1 and 1, is suitable for conventional PWM applications and provides accurate parameters for subsequent PWM-based capacitor H-bridge unit control. The sum of the two is equal to the total output voltage level number Nref, which fundamentally guarantees the accurate tracking of the bridge arm voltage reference value and improves the stability and accuracy of the output voltage of the entire cascaded hybrid H-bridge system.

[0077] In some embodiments, based on the number of output voltage levels of n battery H-bridge units, the control state of the switch unit of each battery H-bridge unit is determined, which may include but is not limited to: based on the number of output voltage levels and bridge arm currents of the n battery H-bridge units, the priorities of the n battery H-bridge units are determined; according to the priorities of the n battery H-bridge units and the number of output voltage levels of the n battery H-bridge units, the connection state of each battery H-bridge unit is determined; according to the connection state of each battery H-bridge unit, the control state of the switch unit of each battery H-bridge unit is determined.

[0078] The connection state includes: a positive series state, a bypass state, and a negative series state.

[0079] Wherein, based on the number of output voltage levels and bridge arm currents of the n battery H-bridge units, the priorities of the n battery H-bridge units are determined, which may include the following situations:

[0080] (A) If the product of the number of output voltage levels of the n battery H-bridge units and the bridge arm current is greater than 0, the priorities of the n battery H-bridge units are determined in descending order of battery voltage.

[0081] (B) If the product of the number of output voltage levels of the n battery H-bridge units and the bridge arm current is less than or equal to 0, the priorities of the n battery H-bridge units are determined in order of battery voltage from small to large.

[0082] In some embodiments, the process of determining the connection status of each battery H-bridge unit based on the priorities of the n battery H-bridge units and the number of output voltage levels of the n battery H-bridge units may include but is not limited to: comparing the priorities of the n battery H-bridge units with the absolute values ​​of the output voltage levels to obtain a first comparison result; determining the connection status of each battery H-bridge unit based on the first comparison result and the positive or negative number of the output voltage levels of the n battery H-bridge units.

[0083] For example, Figure 5 is a control block diagram for determining the control state of the switch unit of each battery H-bridge unit. Figure 5As shown, the battery voltages in the n battery H-bridge units can be sorted first. When sorting, the battery voltages can be sorted, either from large to small or from small to large. And the priority of the battery H-bridge unit is updated according to the output voltage level number Nbat of the above n battery H-bridge units and the positive and negative of the bridge arm current is. Exemplarily, the priority of the n battery H-bridge units can be set to be 1, 2, ..., n in order from the highest priority to the lowest priority. Specifically, when Nbat * is > 0, the battery in the battery H-bridge unit connected in series to the circuit will be discharged. At this time, the battery H-bridge unit with the highest battery voltage has the highest priority (serial number 1), and the battery H-bridge unit with the lowest battery voltage has the lowest priority (serial number n); when Nbat * is <= 0, the battery in the battery H-bridge unit connected in series to the circuit will be charged. At this time, the battery H-bridge unit with the lowest battery voltage has the highest priority (serial number 1), and the battery H-bridge unit with the highest battery voltage has the lowest priority (serial number n).

[0084] Figure 5 In the embodiment, the connection status of the n battery H-bridge units can also be determined according to the number Nbat of output voltage levels of the n battery H-bridge units and the priorities of the n battery H-bridge units.

[0085] Among them, Nbat is positive, and the voltage output sum of all battery H-bridge units is positive, so when Nbat is positive, the battery H-bridge unit is either in a forward series state or a bypass state. Nbat is negative, and the voltage output sum of all battery H-bridge units is negative, so when Nbat is negative, the battery H-bridge unit is either in a negative series state or a bypass state.

[0086] In some embodiments, the state of each battery H-bridge unit can be obtained by comparing the priority number of the battery H-bridge unit with the absolute value of Nbat. Specifically, when Nbat is greater than 0, the battery H-bridge unit with a priority number less than or equal to Nbat is in a forward series state, and the battery H-bridge unit with a priority number greater than Nbat is in a bypass state; when Nbat is less than or equal to 0, the battery H-bridge unit with a priority number less than or equal to -Nbat is in a negative series state, and the battery H-bridge unit with a priority number greater than -Nbat is in a bypass state.

[0087] After determining the connection state of the H-bridge unit, the control state of each switch unit in the n battery H-bridge units can be obtained according to the correspondence between the connection state of the H-bridge unit and the state of the switch unit in the H-bridge unit. Finally, a drive signal can be generated based on the control state of each switch unit in the n battery H-bridge units, and the switch unit in the battery H-bridge unit can be controlled based on the generated drive signal.

[0088] Figure 6 Figure 1 is a schematic diagram of the status of a battery H-bridge unit. Figure 6 As shown in Figure 6 In (a), the voltage output of the battery H-bridge unit V bat is positive, is is also positive, at this time the battery in the battery H-bridge unit connected in series to the circuit will be discharged, the control switch units S1 and S4 are closed, and the switch units S2 and S3 are disconnected; Figure 6 In (b), at V bat When is negative and is is positive, the battery in the battery H-bridge unit connected in series with the circuit will be charged, the control switch units S1 and S4 are disconnected, and the switch units S2 and S3 are closed; Figure 6 In (c), at V bat When is positive and is negative, the battery in the battery H-bridge unit connected in series with the circuit will be charged, and the control switch units S1 and S4 will be closed, and the switch units S2 and S3 will be disconnected; Figure 6 In (d), at V bat When is negative and is is also negative, the battery in the battery H-bridge unit connected in series to the circuit will be discharged, the control switch units S1 and S4 are disconnected, and the switch units S2 and S3 are closed; Figure 6 In (e) and (f), at V bat When is is 0, or is is 0, you can Figure 6 As shown in (e) in FIG. 1 , the switch units S2 and S4 are controlled to be disconnected, and the switch units S1 and S3 are controlled to be closed; or Figure 6 As shown in (f), the switch units S2 and S4 are controlled to be closed, and the switch units S1 and S3 are opened.

[0089] In the above embodiment, the priority sorting method of the battery H-bridge unit is determined by taking the product of the output voltage level number of the battery H-bridge unit and the bridge arm current as the judgment basis. This method fully considers the characteristics of the battery during the charging and discharging process, and reasonably arranges the use order of the battery H-bridge unit according to the relationship between voltage and current. When the product is greater than 0, the battery voltage is sorted from large to small, and the battery with high voltage can be used for discharge first; when the product is less than or equal to 0, the battery voltage is sorted from small to large, which is conducive to charging the battery with low voltage first, optimizing the battery charging and discharging process, improving the battery efficiency and life, and also making the energy management of the entire system more reasonable.

[0090] In the above embodiment, the connection state (forward series connection, bypass connection, negative series connection) of each battery H-bridge unit can be accurately determined based on the comparison result of the priority of the battery H-bridge unit and the absolute value of the output voltage level number, as well as the positive and negative of the output voltage level number. This precise connection state determination method enables the battery H-bridge unit to flexibly participate in voltage output or be in a bypass state according to the needs of the system, further optimizing the voltage output characteristics of the system. For example, when Nbat is greater than 0, the forward series and bypass battery H-bridge units are reasonably allocated according to the priority number, ensuring the accuracy and stability of the forward voltage output; when Nbat is less than or equal to 0, the accurate control of the negative series connection and bypass state realizes the effective management of the negative voltage output.

[0091] In some embodiments, based on the above-mentioned modulation ratio, the process of determining the control state of the switch unit of each capacitor H-bridge unit may include but is not limited to: comparing the modulation ratio and the instantaneous level of the high-frequency triangular carrier to obtain a second comparison result; determining the connection state of each capacitor H-bridge unit according to the second comparison result, and determining the control state of the switch unit of each capacitor H-bridge unit according to the connection state of each capacitor H-bridge unit.

[0092] The connection state includes one of a forward series state, a bypass state, and a negative series state.

[0093] For example, Figure 7 is a control block diagram for determining the control state of a switch unit of a capacitor H-bridge unit. Figure 7 As shown, the modulation ratio and the instantaneous level of the high-frequency triangular carrier can be compared. After the modulation ratio and the high-frequency triangular carrier are compared, when the second comparison result indicates that the capacitor needs to be charged, the capacitor H-bridge unit can be made to enter a positive series state or a negative series state. When the second comparison result indicates that the capacitor needs to be discharged, the connection state of the capacitor H-bridge unit can be a bypass state, and the capacitor may be discharged. Because the capacitor was previously in a series state to participate in the voltage output, when it is switched to the bypass state, the voltage difference across the capacitor will cause the capacitor to discharge through the circuit elements connected to it.

[0094] In the above embodiment, the control state of the capacitor H-bridge unit is determined by comparing the modulation ratio with the instantaneous level of the high-frequency triangular carrier, which provides an effective way for the precise control of the capacitor H-bridge unit. This method of determining the connection state based on the comparison result and then determining the control state of the switch unit can accurately manage the working mode of the capacitor in the circuit. When charging is required, the capacitor H-bridge unit is put into a positive series state or a negative series state, which ensures that the capacitor can obtain energy from the power supply and maintain a suitable voltage level to meet the system voltage output requirements, which helps to improve the system's energy reserves and output capacity. When the comparison result shows that discharge is required, the capacitor H-bridge unit is switched to a bypass state, and the voltage difference across the capacitor is used to discharge through the connected circuit elements. This automatic and accurate discharge control mechanism can not only reasonably release the energy stored in the capacitor, but also effectively avoid problems such as capacitor overcharging, thereby ensuring the safety and stable operation of the capacitor. At the same time, the clear division and flexible switching of the three connection states (forward series state, bypass state, and negative series state) enable the capacitor H-bridge unit to accurately participate in or exit the voltage output process according to the system's real-time power demand, greatly optimizing the voltage output characteristics of the entire circuit system, improving the efficiency and reliability of the system, and reducing the risk of power quality problems and circuit failures that may be caused by improper capacitor control.

[0095] For example, Figure 8 Schematic diagram of comparison between the output voltage of the cascaded hybrid H-bridge module and the output voltage reference in the embodiment of the present application. Figure 8 It can be seen that the embodiments of the present application can ensure reliable operation of the system and low harmonic distortion. Figure 8 The horizontal axis represents time (Time), and its time unit is second (s), and the vertical axis represents voltage value (Voltage).

[0096] in, Figure 8 The waveforms of the output voltage and the output voltage reference when the system is turned on are given in Figure 1. The system output voltage shows a fast transient response when tracking the voltage reference value, and can efficiently adapt to changes in the reference value. When the switching frequency of the capacitor H-bridge submodule is 10kHz, the total harmonic distortion (THD) is about 1.42%; when the switching frequency of the capacitor H-bridge submodule is 20kHz, the THD is about 0.53%.

[0097] For example, Fig. 9 Schematic diagram of the connection status change of the cascaded hybrid H-bridge unit module within two power frequency cycles. Fig. 9 In (a) and (b), the horizontal axis represents time (Time), and the time unit is second (s). Fig. 9 The upper step-shaped curve in (a) represents the Nbat value. Fig. 9 The other eight curves in (a) represent the connection status of the eight battery H-bridge units, where the horizontal axis represents time (Time), the time unit is second (s), and the vertical axis represents 1 for the positive series state, 0 for the bypass state, and -1 for the negative series state. Fig. 9 The curve (b) in the figure represents the Ncap value, the horizontal axis represents time (Time), the time unit is seconds (s), the vertical axis represents the Ncap value, and the curve represents the change of the Ncap value. Fig. 9 It can be seen that by maintaining the switching frequency of the switch units in the multiple battery H-bridge units at twice the load frequency, the solution in the embodiment of the present application can reduce the switching frequency to reduce the switching loss and thus improve the system efficiency.

[0098] For example, Fig. 10A This is a schematic diagram of bridge arm voltage tracking. Fig. 10A (a) in FIG. 1 includes the stack voltage and the stack voltage reference. Take a capacitor H-bridge unit and n battery H-bridge units as an example. Fig. 10A (b) includes the output voltage of the capacitor H-bridge unit (Cap-SM OutputVoltage) and the sum of the output voltages of n battery H-bridge units (Bat-SMs Output Voltage). Fig. 10A It can be seen that the bridge arm voltage tracking performance is excellent. Fig. 10A The horizontal axis represents time (Time), and its time unit is second (s), and the vertical axis represents voltage, and its voltage unit is V.

[0099] For example, Fig. 10B A schematic diagram of voltage balancing of a hybrid H-bridge unit module using the method provided in an embodiment of the present application. Fig. 10B In the figure, a cascaded hybrid H-bridge module consisting of 1 capacitor H-bridge unit and 8 battery H-bridge units is used as an example for explanation. Fig. 10B The curve in the figure represents the battery voltage (Capacitor Voltage) of the 8-battery H-bridge unit. Fig. 10B The straight line in represents the average voltage of the battery of the capacitor H-bridge unit. Fig. 10B The horizontal axis represents time (Time), and its time unit is seconds (s), and the vertical axis represents voltage, and its voltage unit is V. Fig. 10B It can be seen that the method provided in the embodiment of the present application shows that the voltage balance between the capacitor H-bridge unit and different battery H-bridge units is achieved, thereby extending the operating life of the system.

[0100] It should be understood that, although the steps in the flowcharts involved in the above embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps is not strictly limited in order, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above embodiments may include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0101] Based on the same inventive concept, the embodiment of the present application also provides a control state determination device for implementing the control state determination method involved above. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme recorded in the above method, so the specific limitations in one or more control state determination device embodiments provided below can refer to the limitations of the control state determination method above, and will not be repeated here.

[0102] In an exemplary embodiment, Fig.11 As shown, a structural block diagram of a control state determination device for a switch unit of a single-phase cascade hybrid H-bridge unit battery energy storage system is provided, including:

[0103] The level number determination module 1101 is used to determine the total output voltage level number of the cascaded hybrid H-bridge module according to the voltage average value of each H-bridge unit in the cascaded hybrid H-bridge module and the bridge arm voltage reference value of the cascaded hybrid H-bridge module;

[0104] A voltage deviation determination module 1102 is used to determine a voltage deviation between n battery H-bridge units and m capacitor H-bridge units;

[0105] The control module 1103 is used to determine the control state of the switch unit in each H-bridge unit according to the total output voltage level number, the bridge arm current and the voltage deviation of the cascaded hybrid H-bridge module.

[0106] In one embodiment, the control module 1103 is specifically used to: determine the number of output voltage levels of n battery H-bridge units and the modulation ratio of pulse width modulation of m capacitor H-bridge units according to the total number of output voltage levels, the bridge arm current and the voltage deviation of the cascaded hybrid H-bridge module;

[0107] Determining a control state of a switch unit of each battery H-bridge unit based on the number of output voltage levels of the n battery H-bridge units;

[0108] Based on the modulation ratio, the control state of the switch unit of each capacitive H-bridge unit is determined.

[0109] In one embodiment, the control module 1103 is specifically configured to:

[0110] If the product of the voltage deviation and the bridge arm current is greater than 0, the total output voltage level number is rounded down to determine the output voltage level number of the n battery H-bridge units, and the difference between the total output voltage level number and the output voltage level number of the n battery H-bridge units is used as the modulation ratio of the pulse width modulation of the m capacitor H-bridge units;

[0111] If the product of the voltage deviation and the bridge arm current is less than or equal to 0, the total output voltage level number is rounded up to determine the output voltage level number of the n battery H-bridge units, and the difference between the total output voltage level number and the output voltage level number of the n battery H-bridge units is used as the modulation ratio of the pulse width modulation of the m capacitor H-bridge units.

[0112] In one embodiment, the control module 1103 is specifically configured to:

[0113] Determine the priorities of the n battery H-bridge units based on the number of output voltage levels and bridge arm currents of the n battery H-bridge units;

[0114] Determine the connection state of each battery H-bridge unit according to the priority of the n battery H-bridge units and the number of output voltage levels of the n battery H-bridge units, where the connection state includes: one of a forward series state, a bypass state, and a negative series state;

[0115] According to the connection state of each battery H-bridge unit, the control state of the switch unit of each battery H-bridge unit is determined.

[0116] In one embodiment, the control module 1103 is specifically configured to:

[0117] Comparing the priorities of the n battery H-bridge units with the absolute values ​​of the output voltage levels of the n battery H-bridge units to obtain a first comparison result;

[0118] The connection state of each battery H-bridge unit is determined according to the first comparison result and the positive and negative numbers of the output voltage levels of the n battery H-bridge units.

[0119] In one embodiment, the control module 1103 is specifically configured to:

[0120] If the product of the output voltage level number of the n battery H-bridge units and the bridge arm current is greater than 0, the priorities of the n battery H-bridge units are determined in descending order of battery voltage;

[0121] If the product of the number of output voltage levels of the n battery H-bridge units and the bridge arm current is less than or equal to 0, the priorities of the n battery H-bridge units are determined in order of battery voltage from small to large.

[0122] In one embodiment, the control module 1103 is specifically configured to:

[0123] comparing the modulation ratio and the instantaneous level of the high frequency triangular carrier to obtain a second comparison result;

[0124] According to the second comparison result, determining the connection state of each capacitor H-bridge unit, the connection state includes: one of: a positive series state, a bypass state, and a negative series state;

[0125] According to the connection state of each capacitor H-bridge unit, the control state of the switch unit of each capacitor H-bridge unit is determined.

[0126] Each module in the above control state determination device can be implemented in whole or in part by software, hardware, or a combination thereof. Each module can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in a computer device in the form of software, so that the processor can call and execute operations corresponding to each module.

[0127] In an exemplary embodiment, a computer device is provided. The computer device may be a server, and its internal structure diagram may be as shown in FIG. Fig.12 As shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, referred to as I / O) and a communication interface. The processor, the memory and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store data. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a control state determination method is implemented.

[0128] Those skilled in the art will understand that Fig.12 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0129] In an exemplary embodiment, a computer device is provided, including a memory and a processor, wherein a computer program is stored in the memory, and each step in the above method embodiment is implemented when the processor executes the computer program.

[0130] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but are not limited to this.

[0131] In an exemplary embodiment, a multi-phase cascade hybrid H-bridge battery energy storage system is also provided, which includes a plurality of switch unit control state determination methods of the single-phase cascade hybrid H-bridge battery energy storage system as described above to determine the control state of the switch unit in each phase cascade hybrid H-bridge module.

[0132] like Fig.13The three-phase cascade hybrid H-bridge battery energy storage system shown in the figure includes three single-phase cascade hybrid H-bridge battery energy storage systems, each of which includes a single-phase cascade hybrid H-bridge battery energy storage system and a filter circuit, and is respectively connected to an external load or one phase of the power grid; the three single-phase cascade hybrid H-bridge battery energy storage systems are connected via a star connection (such as Fig.13 (a)) or triangle ( Fig.13 The control state of the switch unit in each cascade hybrid H-bridge module in the three-phase cascade hybrid H-bridge battery energy storage system is determined by the switch unit control state determination method of the single-phase cascade hybrid H-bridge battery energy storage system.

[0133] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0134] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A single-phase cascade hybrid H-bridge battery energy storage system, characterized in that: include: Cascaded hybrid H-bridge module and filter circuit; the cascaded hybrid H-bridge module is connected to an external load or a power grid through the filter circuit; The cascaded hybrid H-bridge module includes m cascaded capacitor H-bridge units and n battery H-bridge units; wherein m is greater than or equal to 1 and less than n; and n is greater than or equal to 2; The switching frequency of the capacitor H-bridge unit is in a high frequency range, and the switching frequency of the battery H-bridge unit is in a low frequency range.

2. The system according to claim 1, characterized in that The m is 1.

3. A method for determining the control state of a switch unit of a single-phase cascade hybrid H-bridge battery energy storage system, characterized in that: The single-phase cascade hybrid H-bridge battery energy storage system as claimed in claim 1 or 2 comprises: Determine the total output voltage level number of the cascaded hybrid H-bridge module according to the voltage average value of each H-bridge unit in the cascaded hybrid H-bridge module and the bridge arm voltage reference value of the cascaded hybrid H-bridge module; Determining a voltage deviation between the n battery H-bridge units and the m capacitor H-bridge units; The control state of the switch unit in each H-bridge unit is determined according to the total number of output voltage levels, the bridge arm current of the cascaded hybrid H-bridge module and the voltage deviation.

4. The method according to claim 3, characterized in that The step of determining the control state of the switch unit in each H-bridge unit according to the total number of output voltage levels, the bridge arm current of the cascaded hybrid H-bridge module, and the voltage deviation comprises: Determine the number of output voltage levels of the n battery H-bridge units and the modulation ratio of pulse width modulation of the m capacitor H-bridge units according to the total number of output voltage levels, the bridge arm current of the cascaded hybrid H-bridge module and the voltage deviation; Determining a control state of a switch unit of each of the battery H-bridge units based on the number of output voltage levels of the n battery H-bridge units; Based on the modulation ratio, a control state of the switch unit of each of the capacitive H-bridge units is determined.

5. The method according to claim 4, characterized in that The method of determining the number of output voltage levels of the n battery H-bridge units and the modulation ratio of pulse width modulation of the m capacitor H-bridge units according to the total number of output voltage levels, the bridge arm current of the cascaded hybrid H-bridge module and the voltage deviation comprises: If the product of the voltage deviation and the bridge arm current is greater than 0, the total output voltage level number is rounded down to determine the output voltage level number of the n battery H-bridge units, and the difference between the total output voltage level number and the output voltage level number of the n battery H-bridge units is used as the modulation ratio of the pulse width modulation of the m capacitor H-bridge units; If the product of the voltage deviation and the bridge arm current is less than or equal to 0, the total output voltage level number is rounded up to determine the output voltage level number of the n battery H-bridge units, and the difference between the total output voltage level number and the output voltage level number of the n battery H-bridge units is used as the modulation ratio of the pulse width modulation of the m capacitor H-bridge units.

6. The method according to claim 5, characterized in that The determining the control state of the switch unit of each of the battery H-bridge units based on the number of output voltage levels of the n battery H-bridge units includes: Determining the priorities of the n battery H-bridge units based on the number of output voltage levels of the n battery H-bridge units and the bridge arm current; Determine the connection state of each of the battery H-bridge units according to the priority of the n battery H-bridge units and the number of output voltage levels of the n battery H-bridge units, wherein the connection state includes: one of a forward series state, a bypass state, and a negative series state; According to the connection state of each of the battery H-bridge units, the control state of the switch unit of each of the battery H-bridge units is determined.

7. The method according to claim 6, characterized in that The determining the connection state of each of the battery H-bridge units according to the priority of the n battery H-bridge units and the number of output voltage levels of the n battery H-bridge units includes: Comparing the priorities of the n battery H-bridge units with the absolute values ​​of the output voltage levels of the n battery H-bridge units to obtain a first comparison result; The connection state of each of the battery H-bridge units is determined according to the first comparison result and the positive and negative numbers of the output voltage levels of the n battery H-bridge units.

8. The method according to claim 6, characterized in that The determining the priorities of the n battery H-bridge units based on the number of output voltage levels of the n battery H-bridge units and the bridge arm currents includes: If the product of the output voltage level number of the n battery H-bridge units and the bridge arm current is greater than 0, the priorities of the n battery H-bridge units are determined in descending order of battery voltage; If the product of the number of output voltage levels of the n battery H-bridge units and the bridge arm current is less than or equal to 0, the priorities of the n battery H-bridge units are determined in order of battery voltage from small to large.

9. The method according to claim 5, characterized in that The determining the control state of the switch unit of each of the capacitor H-bridge units based on the modulation ratio includes: comparing the modulation ratio and the instantaneous level of the high-frequency triangular carrier to obtain a second comparison result; Determine the connection state of each of the capacitor H-bridge units according to the second comparison result, wherein the connection state includes: a forward series state, a bypass state, and a negative series state; The control state of the switch unit of each of the capacitor H-bridge units is determined according to the connection state of each of the capacitor H-bridge units.

10. A multi-phase cascade hybrid H-bridge battery energy storage system, characterized in that: It comprises a plurality of single-phase cascade hybrid H-bridge battery energy storage systems as described in any one of claims 1-2, wherein the control state of the switch unit in the system is determined by the method as described in any one of claims 3-9.

11. A computer-readable storage medium, characterized in that: A computer program is stored thereon, and when the computer program is executed by a processor, the method according to any one of claims 3 to 9 is implemented.

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