Charging and discharging control method, control system and equipment of two-way battery energy storage inverter

Abstract

This invention discloses a charging and discharging control method, control system, and device for a dual-channel battery energy storage inverter. The method includes: detecting the DC bus voltage and comparing it with a target value to generate a bus voltage error signal; inputting the error signal into a voltage outer loop controller and outputting a total system current setpoint; acquiring the state of charge (SOC) values ​​of the first and second channels of batteries in real time; dynamically selecting a current distribution strategy: when both SOC values ​​are higher than or lower than the target SOC, a proportional distribution strategy is executed; when one SOC value is greater than the target SOC and the other is less than the target SOC, a forced equalization strategy is executed; and allocating the current setpoint as an independent current input to the corresponding inner current loop to generate a PWM signal to drive the switching transistor, so as to achieve proportional distribution to avoid overload in the same-direction state and forced equalization to achieve energy transfer in the reverse state, thereby extending battery life.

Description

Technical Field

[0001] This application relates to the fields of power electronics and energy storage technology, and more specifically, to a charging and discharging control method, control system and equipment for a dual-channel battery energy storage inverter. Background Technology

[0002] Current battery energy storage inverters generally adopt a single-battery structure, which suffers from problems such as low charging and discharging efficiency and imbalance between battery packs. Although a dual-battery structure can increase capacity, traditional control methods cannot dynamically allocate charging and discharging current according to the battery's state of charge (SOC), leading to accelerated battery life degradation and insufficient system stability. Summary of the Invention

[0003] The purpose of this application is to provide a charging and discharging control method, control system and equipment for a dual-channel battery energy storage inverter, which has the advantages of solving the problem of state imbalance between battery packs, avoiding overcharging of high SOC battery packs and under-discharging of low SOC battery packs, improving the efficiency of energy storage system and extending battery life.

[0004] This application provides a charging and discharging control method for a dual-channel battery energy storage inverter. The technical solution is as follows: The DC bus voltage Vbus is detected and compared with the target value Vbus_ref to generate a bus voltage error signal; the error signal is input to the voltage outer loop controller, which outputs the system total current setpoint Ibat_ref; the state of charge (SOC) values ​​of the first and second batteries are acquired in real time; a current distribution strategy is dynamically selected: when both SOC1 and SOC2 are higher than or lower than the target SOC, a proportional distribution strategy is executed; when one SOC value is greater than the target SOC and the other is less than the target SOC, a forced equalization strategy is executed; Ibat_ref is allocated as an independent current setpoint Ibat1_ref for Bat1 and an independent current setpoint Ibat2_ref for Bat2; Ibat1_ref and Ibat2_ref are input to the first and second BuckBoost current inner loops, respectively, to generate PWM signals to drive the two BuckBoost switches.

[0005] Furthermore, this application also proposes a proportional allocation strategy including: when Ibat_ref_0, performing joint charging: Ibat1_ref=Ibat_ref×SOC2 / (SOC1+SOC2), Ibat2_ref=Ibat_ref×SOC1 / (SOC1+SOC2).

[0006] At Ibat_ref_0, a common discharge is performed:

[0007] Ibat1_ref=Ibat_ref×SOC1 / (SOC1+SOC2), Ibat2_ref=Ibat_ref×SOC2 / (SOC1+SOC2).

[0008] Furthermore, this application proposes a forced equalization strategy including: when Ibat_ref_0 and SOC1_SOC2, performing unbalanced charging: Ibat1_ref = −Ibat_ref, Ibat2_ref = 2 × Ibat_ref; when Ibat_ref_0 and SOC1_SOC2, performing unbalanced charging: Ibat1_ref = 2 × Ibat_ref, Ibat2_ref = −Ibat_ref; when Ibat_ref_0 and SOC1_SOC2, performing unbalanced discharging: Ibat1_ref = 2 × Ibat_ref, Ibat2_ref = −Ibat_ref;

[0009] When Ibat_ref_0 and SOC1_SOC2, perform unbalanced discharge:

[0010] Ibat1_ref=−Ibat_ref,Ibat2_ref=2×Ibat_ref.

[0011] Furthermore, this application also proposes generating a PWM signal to drive two BuckBoost switches, including: for the first BuckBoost circuit: subtracting the independent current setpoint Ibat1_ref of the first battery from the actual current value Ibat1 to obtain a first current deviation signal; inputting the first current deviation signal into a first PI regulator and outputting a first current regulation value Ibat1_out; generating a first PWM signal to drive the first switch using the following formula: PWM1=1−Vbat1 / (|Ibat1_out|+Vbus_ref), where, Vb at1 is the voltage of the first battery, and Vbus_ref is the target value of the bus voltage. For the second BuckBoost circuit: the independent current setpoint Ibat2_ref of the second battery is subtracted from the actual current value Ibat2 to obtain the second current deviation signal; the second current deviation signal is input to the second PI regulator, and the second current regulation value Ibat2_out is output; the second PWM signal driving the second switch is generated by the following formula: PWM2=1−Vbat2 / (∣Ibat2_out∣+Vbus_ref), where Vbat2 is the voltage of the second battery.

[0012] Furthermore, this application also proposes a dual-path battery energy storage inverter control system, comprising: a bus voltage detection module connected to the DC bus to acquire Vbus signals; a voltage outer loop controller that receives Vbus error signals at its input and generates Ibat_ref at its output; a dynamic distributor configured to run the aforementioned current distribution strategy; and a first BuckBoost current inner loop and a second BuckBoost current inner loop connected in parallel.

[0013] Furthermore, this application also proposes that the dynamic allocator includes: a SOC comparison unit for determining the sign relationship between |SOC1-target SOC| and |SOC2-target SOC|; a strategy selection unit for activating a proportional allocation or forced equalization strategy based on the sign relationship; and a current calculation unit for outputting signed Ibat1_ref and Ibat2_ref.

[0014] Furthermore, this application also proposes that the output terminal of the inner current loop is used to generate a PWM1 signal to drive the first BuckBoost switch and to generate a PWM2 signal to drive the second BuckBoost switch.

[0015] Furthermore, this application also proposes that the target SOC is a programmable parameter, and the value range of the target SOC is 20% to 80%.

[0016] Furthermore, this application also proposes that the process of obtaining SOC1 and SOC2 includes: calculating the remaining power of the corresponding battery based on the Coulomb integral method according to the sampling period.

[0017] Furthermore, this application also proposes a dual-channel battery energy storage inverter device, comprising: the aforementioned control system; a first BuckBoost circuit: including an inductor L1, a switch Q1, and a diode D1, connected to Bat1 and Vbus; a second BuckBoost circuit: including an inductor L2, a switch Q2, and a diode D2, connected to Bat2 and Vbus; and an H4 inverter bridge circuit, with its input terminal connected to Vbus and its output terminal connected to the power grid.

[0018] As can be seen from the above, the charging and discharging control method, control system and equipment of the dual-channel battery energy storage inverter provided in this application effectively solves the overcharging and under-discharging problems caused by the difference in state of charge between battery packs by dynamically selecting proportional allocation or forced equalization strategies and combining the coordinated control of the voltage outer loop and the current inner loop, thereby improving system stability and battery life. Attached Figure Description

[0019] The accompanying drawings are provided to further understand the technical solutions of the present invention and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the technical solutions of the present invention, and do not constitute a limitation on the technical solutions of the present invention.

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments;

[0021] Figure 1 This is a schematic diagram of a dual-channel battery energy storage inverter device provided in an embodiment of the present invention;

[0022] Figure 2 A step diagram illustrating the charging and discharging control method for a dual-channel battery energy storage inverter provided in an embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of a dual-channel battery energy storage inverter control system provided in an embodiment of the present invention. Detailed Implementation

[0024] The technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. The components of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. It should be noted that similar reference numerals and letters in the following drawings indicate similar items; therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. Furthermore, in the description of this application, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0025] In existing technologies, battery storage inverters generally adopt a single-battery structure, which suffers from low charging and discharging efficiency and imbalance between battery packs. While a dual-battery structure can increase system capacity, traditional control methods cannot dynamically allocate charging and discharging current based on the battery's state of charge, leading to accelerated battery lifespan degradation and insufficient system stability. For example, in scenarios requiring simultaneous management of two batteries, a fixed current allocation method can easily cause overcharging or over-discharging when the states of charge of the two batteries differ, exacerbating the imbalance between battery packs.

[0026] To address the aforementioned issues, a control method capable of dynamically adjusting charging and discharging currents based on real-time state of charge (SBC) is needed. First, it's crucial to accurately detect the real-time SBC differences between the two batteries. Second, current allocation rules must be established for these differing SBC states. By introducing a SBC comparison mechanism, the differences in charging and discharging demands between the two batteries are determined, allowing for the selection of different allocation strategies. For SBC states in the same direction, proportional allocation is used to avoid overload; for SBC states in opposite directions, forced equalization is employed to achieve energy transfer, thereby extending battery lifespan while ensuring stable system operation.

[0027] Therefore, this application proposes a charging and discharging control method for a dual-battery energy storage inverter, comprising two independent BuckBoost circuits and an H4 inverter bridge topology. This method generates an error signal by detecting the DC bus voltage and comparing it with a target value, which is then output as the system's total current setpoint via the outer voltage loop controller. The state-of-charge (SOC) values ​​of the two batteries are acquired in real time, and a proportional distribution or forced balancing strategy is dynamically selected based on the SOC differences to distribute the total current into two independent current setpoints. Finally, the inner current loop control generates PWM signals to drive the two BuckBoost switches.

[0028] The following description of the proposed solution, in conjunction with the accompanying drawings, will be provided.

[0029] refer to Figure 1 , Figure 1 This is a schematic diagram of a dual-channel battery energy storage inverter device provided in an embodiment of the present invention. The dual-channel battery energy storage inverter device is a dual BuckBoost power circuit. The first channel is Bat1→L1→Q1 / D1→Vbus to realize bidirectional Buck / Boost conversion. The second channel is Bat2→L2→Q2 / D2→Vbus, which can provide independent charging and discharging physical paths for the two batteries and ensure current controllability.

[0030] In contrast, in this application, the outer loop of the bus voltage can maintain DC bus stability and respond to grid power demand by detecting Vbus → comparing with Vbus_ref → voltage outer loop controller → outputting Ibat_ref; the current distribution engine can obtain SOC1 / SOC2 → dynamically select strategy → output Ibat1_ref / Ibat2_ref, and dynamically distribute current according to battery status (proportional distribution / forced equalization); the dual current inner loop can track current commands and generate switching transistor drive signals through the following signal flow: Ibat1_ref --> | compare with actual Ibat1 | PI regulator 302 --> | output Ibat1_out | PWM calculation module --> PWM1 drives Q1, and Ibat2_ref --> | compare with actual Ibat2 | PI regulator 303 --> | output Ibat2_out | PWM calculation module --> PWM2 drives Q2.

[0031] It is understandable that the signal flow between the H4 inverter bridge and the grid is Vbus→H bridge→grid, which can realize DC-AC conversion and complete grid-connected / off-grid control.

[0032] Further reference Figure 2 , Figure 2 This invention provides a step-by-step diagram of a charging and discharging control method for a dual-channel battery energy storage inverter. The charging and discharging control method is applied to a topology including two independent BuckBoost circuits and an H4 inverter bridge. The method comprises the following steps:

[0033] Step S210: Detect the DC bus voltage Vbus and compare it with the target value Vbus_ref to generate a bus voltage error signal;

[0034] Step S220: Input the error signal into the outer loop voltage controller and output the total system current setpoint Ibat_ref;

[0035] Step S230: Real-time acquisition of the first battery state of charge value SOC1 and the second battery state of charge value SOC2;

[0036] Step S240, dynamically select the current distribution strategy: when both SOC1 and SOC2 are higher than or lower than the target SOC, execute the proportional distribution strategy; when one SOC value is greater than the target SOC and the other is less than the target SOC, execute the forced equalization strategy.

[0037] Step S250: Assign Ibat_ref as the independent current reference value Ibat1_ref for Bat1 and the independent current reference value Ibat2_ref for Bat2;

[0038] In step S260, Ibat1_ref and Ibat2_ref are input to the first BuckBoost current inner loop and the second BuckBoost current inner loop respectively to generate PWM signals to drive the two BuckBoost switching transistors.

[0039] The dynamic current allocation strategy refers to selecting different allocation modes based on the relative relationship between the state of charge (SBC) of the two batteries and the target value. Specifically, this can be implemented using a state comparator and logic circuitry. Proportional allocation is triggered when both battery SBCs are above or below the target value, and forced equalization is triggered when the SBCs are on opposite sides of the target value. This feature automatically switches the control mode according to the actual battery state, solving the overcharging or undercharging problems caused by traditional fixed allocation strategies.

[0040] The proportional allocation strategy refers to distributing charging and discharging currents based on the relative proportions of the states of charge (SOCs) of the two batteries. Specifically, this can be implemented using a SOC-weighted algorithm, where the battery with the lower SOC receives more charging current during joint charging, and the battery with the higher SOC receives more discharging current during joint discharging. This feature achieves a gradual balance between the states of the two batteries by dynamically adjusting the current allocation weights.

[0041] The forced balancing strategy refers to achieving energy transfer between two batteries through reverse current operation. Specifically, this can be implemented using current polarity reversal control technology. When one battery needs charging while the other needs discharging, a reverse current setpoint is used to force energy transfer from the high-charge-state battery to the low-charge-state battery. This feature can quickly eliminate state deviations between the two batteries, avoiding battery performance degradation caused by long-term imbalance.

[0042] In some embodiments, the working principle of this method includes five stages: voltage outer loop control, state monitoring, strategy selection, current distribution, and execution control. First, the voltage outer loop controller maintains a stable DC bus voltage and outputs the total system current demand. Then, the state of charge (SOC) of the two batteries is acquired in real time and compared with the target value. When the two batteries are in the same charging / discharging demand region, a proportional distribution strategy is used to allocate current according to SOC weights; when the two batteries are in opposite demand regions, a forced equalization strategy is used to achieve energy transfer through current reversal. Finally, the allocated current setpoint is converted into a PWM drive signal by the current inner loop controller to precisely control the duty cycle of the switching transistors in the two BuckBoost circuits.

[0043] Understandably, traditional dual-battery control methods, employing fixed-ratio allocation or simple current sharing strategies, cannot adapt to dynamic changes in battery state. This method introduces a state-of-charge feedback mechanism to construct a dynamic allocation system based on the actual needs of the batteries. Gradual balancing is used when battery states are similar, while active balancing is employed when state differences are significant. This ensures system stability and achieves healthy battery management. Through this technical solution, this application realizes intelligent charge and discharge management of a dual-battery energy storage system. Automatic switching of the dynamic allocation strategy solves the battery imbalance problem caused by traditional methods; the synergistic effect of proportional allocation and forced balancing optimizes battery usage while maintaining stable bus voltage; and precise control of the inner current loop ensures effective execution of the allocation strategy. This solution is particularly suitable for energy storage systems that need to manage multiple battery groups simultaneously and has significant application value in scenarios such as photovoltaic energy storage and electric vehicle charging stations.

[0044] This application further proposes a proportional allocation strategy including: when Ibat_ref_0, joint charging is performed, Ibat1_ref=Ibat_ref×SOC2 / (SOC1+SOC2), Ibat2_ref=Ibat_ref×SOC1 / (SOC1+SOC2); when Ibat_ref_0, joint discharging is performed, Ibat1_ref=Ibat_ref×SOC1 / (SOC1+SOC2), Ibat2_ref=Ibat_ref×SOC2 / (SOC1+SOC2).

[0045] In this context, `Ibat_ref_0` indicates the system is in charging mode, where the total current setpoint is positive. This can be determined by the output polarity of the voltage outer loop controller, representing the state of the battery needing to absorb energy. Conversely, `Ibat_ref_0` indicates the system is in discharging mode, where the total current setpoint is negative. This can be achieved through a current direction detection circuit, representing the state of the battery needing to release energy. `SOC1` and `SOC2` are the quantified states of charge (SOC) of the two batteries, achieved using coulomb integration combined with voltage-capacity curve fitting, reflecting the proportion of remaining usable energy. The denominator (`SOC1 + SOC2`) in the proportional allocation strategy is used for normalization, achieved through real-time addition, converting the SOC difference between the two batteries into current allocation weights.

[0046] In some embodiments, during charging mode, if the State of Charge (SOC) of both batteries is higher or lower than the target value, an inverse SOC allocation method is adopted. For example, when the SOC of the first battery is higher, its charging current Ibat1_ref is allocated as the ratio of the total current multiplied by the SOC2 to the sum of the SOCs of the two batteries, so that the battery with the higher SOC receives a smaller charging current, thereby slowing down its charging speed. Similarly, during discharging mode, the battery with the higher SOC will bear a larger proportion of the discharging current, and the energy state balance of the two batteries is achieved by dynamically adjusting the charging and discharging weights.

[0047] Understandably, traditional methods employ fixed ratios or current sharing during dual-battery charging and discharging, neglecting the differences in the actual state of charge (SOC) of the batteries. For example, continuing to apply the same current to a high-SOC battery during charging may accelerate its polarization effect. This solution, however, introduces a dynamic SOC weighting factor to match the current distribution with the actual battery state, effectively avoiding the risks of overcharging or over-discharging. Through this technical solution, this application can automatically adjust the charging and discharging current ratio based on the real-time energy state of the battery, achieving gentle and balanced control when the SOCs of the two batteries are similar, reducing the differences in battery aging rates caused by unreasonable current distribution, while maintaining the overall energy throughput efficiency of the system.

[0048] This application further proposes a forced equalization strategy including: when Ibat_ref_0 and SOC1_SOC2, performing unbalanced charging: Ibat1_ref = −Ibat_ref, Ibat2_ref = 2 × Ibat_ref; when Ibat_ref_0 and SOC1_SOC2, performing unbalanced charging: Ibat1_ref = 2 × Ibat_ref, Ibat2_ref = −Ibat_ref; when Ibat_ref_0 and SOC1_SOC2, performing unbalanced discharging: Ibat1_ref = 2 × Ibat_ref, Ibat2_ref = −Ibat_ref; when Ibat_ref_0 and SOC1_SOC2, performing unbalanced discharging: Ibat1_ref = −Ibat_ref, Ibat2_ref = 2 × Ibat_ref.

[0049] The forced balancing strategy refers to an algorithm that achieves rapid balancing by reversing current allocation when the states of charge (SOC) of two batteries deviate from the target value in opposite directions. Specifically, this can be achieved by using current command values ​​with opposite signs. For example, when the SOC of the first battery is higher than the target value while that of the second battery is lower, a discharge current command is applied to the first battery, while a charging current command is applied to the second battery. Uneven charging refers to applying current commands in different directions to the two batteries during the charging process. This can be achieved by setting positive and negative current command values. For example, when the total system current command value is positive, a negative current command is assigned to the battery with the higher SOC to discharge it, while a double positive current command is assigned to the battery with the lower SOC to charge it quickly. Uneven discharging refers to applying current commands in different directions to the two batteries during the discharging process. This can also be achieved by setting positive and negative current command values. For example, when the total system current command value is negative, a double negative current command is assigned to the battery with the higher SOC to discharge it quickly, while a positive current command is assigned to the battery with the lower SOC to charge it in reverse.

[0050] In some embodiments, when a deviation is detected between the two battery states of charge (SOC) and the target value—for example, the SOC of the first battery is higher than the target value while that of the second battery is lower than the target value—a forced balancing strategy is activated. At this time, if the system is charging, the first battery is assigned a negative current setpoint to initiate a discharge, while the second battery is assigned twice the positive current setpoint to accelerate charging. If the system is discharging, the first battery is assigned twice the negative current setpoint to accelerate discharging, while the second battery is assigned a positive current setpoint to reverse charge. This strategy dynamically adjusts the amplitude and direction of the two currents, allowing the battery with the higher SOC to quickly release energy and the battery with the lower SOC to quickly replenish energy, thereby achieving rapid balancing of the SOC between the two batteries.

[0051] Understandably, traditional methods, when the states of charge (SOC) of the two batteries show opposite deviations, only use a fixed ratio to allocate current, resulting in continuous charging of the high-SOC battery or continuous discharging of the low-SOC battery, thus accelerating battery aging. This solution, however, uses a forced reverse current allocation command to enable the two batteries to actively adjust the energy flow direction during charging and discharging, effectively shortening the equalization time. Through this technical solution, this application solves the problem of decreased charging and discharging efficiency caused by differences in SOC between the two batteries, avoiding capacity decay caused by long-term imbalance in the battery pack. Simultaneously, it improves the system's stability under abnormal operating conditions by dynamically adjusting the current direction. For example, when there is a cross-deviation in the battery pack's SOC, it can quickly switch the current allocation mode to prevent overcharging or over-discharging of a single battery, extending the overall battery life.

[0052] This application further proposes a method for generating PWM signals to drive two BuckBoost switches, including: for the first BuckBoost circuit, subtracting the independent current setpoint Ibat1_ref of the first battery from the actual current value Ibat1 to obtain a first current deviation signal; inputting the first current deviation signal into a first PI regulator and outputting a first current regulation value Ibat1_out; generating a first PWM signal to drive the first switch using the formula PWM1=1−Vbat1 / (∣Ibat1_out∣+Vbus_ref), where Vb at1 is the voltage of the first battery, and Vbus_ref is the target value of the bus voltage. For the second BuckBoost circuit, the difference between the independent current setpoint Ibat2_ref of the second battery and the actual current value Ibat2 is used to obtain the second current deviation signal. The second current deviation signal is input to the second PI regulator, and the second current regulation value Ibat2_out is output. The second PWM signal driving the second switch is generated by the formula PWM2=1−Vbat2 / (∣Ibat2_out∣+Vbus_ref), where Vbat2 is the voltage of the second battery.

[0053] The current deviation signal refers to the difference between the independent current setpoint and the actual current value. It can be implemented using a subtractor circuit or a digital signal processing algorithm to reflect the current tracking error. The PI regulator, or proportional-integral controller, can be implemented using analog circuits or digital control algorithms to dynamically adjust the output current regulation value based on the current deviation. In the PWM signal generation formula, Vbat1 and Vbat2 refer to the battery terminal voltage, which can be acquired in real time by a voltage sensor. This voltage is used to calculate the duty cycle of the switching transistor by combining the current regulation value and the target bus voltage value, thereby achieving dynamic control of the BuckBoost circuit's operating mode.

[0054] In some embodiments, when the first BuckBoost circuit needs to adjust its output, a deviation signal is generated by comparing the difference between Ibat1_ref and Ibat1. After processing by a PI regulator, the current adjustment value Ibat1_out is obtained. This adjustment value, along with the target bus voltage Vbus_ref and the battery voltage Vbat1, participates in the PWM duty cycle calculation. For example, when Vbat1 is 48V and Vbus_ref is 400V, the duty cycle calculation result can dynamically adapt to battery voltage fluctuations. The second circuit uses the same processing flow. The two PWM signals are generated independently but share the target bus voltage value, ensuring that the two circuits maintain stable bus voltage while working in coordination.

[0055] Understandably, traditional methods typically employ fixed duty cycles or single feedback loop control, which cannot simultaneously address battery voltage variations and bus voltage stability. For example, in existing technologies, a fixed duty cycle causes a drop in bus voltage when battery voltage decreases. This solution, however, introduces a dynamic parameter, Vbat, to automatically adjust the duty cycle according to battery voltage changes. For instance, when Vbat decreases, the denominator in the formula decreases, increasing the duty cycle and compensating for the impact of voltage drops on the bus. Through this technical solution, this application can dynamically generate PWM signals based on real-time battery voltage and current regulation values, automatically adjusting the switching transistor's duty cycle when battery voltage fluctuates, effectively suppressing bus voltage fluctuations caused by differences in battery pack conditions. For example, in scenarios where battery pack aging leads to a decrease in Vbat, the duty cycle calculated by the formula automatically increases, maintaining bus voltage stability and avoiding system instability caused by single-cell battery performance degradation.

[0056] refer to Figure 3 , Figure 3 This is a schematic diagram of a dual-channel battery energy storage inverter control system provided in an embodiment of the present invention; as shown. Figure 3 As shown, this application further proposes a dual-path battery energy storage inverter control system, including a bus voltage detection module, a voltage outer loop controller 301, a dynamic distributor 304, and a first BuckBoost current inner loop 302 and a second BuckBoost current inner loop 303 connected in parallel. The bus voltage detection module is connected to the DC bus to collect the Vbus signal. The voltage outer loop controller receives the Vbus error signal at its input terminal and generates Ibat_ref at its output terminal. The dynamic distributor is configured to execute a current distribution strategy that includes a proportional distribution strategy and a forced equalization strategy.

[0057] The bus voltage detection module refers to the hardware circuit used for real-time monitoring of the DC bus voltage. Specifically, it can be implemented using a voltage sensor combined with a signal conditioning circuit, for example, by acquiring the bus voltage signal using a Hall sensor and converting it into a processable analog quantity. The outer voltage loop controller is the closed-loop control unit used to regulate the bus voltage. Specifically, it can be implemented using a proportional-integral controller, which generates the system's total current setpoint based on the bus voltage error signal. The dynamic distributor is the computational unit used to dynamically adjust the current distribution between the two battery circuits. Specifically, it can be implemented using a microcontroller or digital signal processor, which selects different current distribution strategies based on the differences in battery state of charge. The parallel current inner loop refers to a closed-loop system that independently controls the current of the two BuckBoost circuits. Specifically, it can be implemented using a current tracking circuit with a PI regulator, for example, by comparing the current setpoint with the actual value to generate a PWM drive signal.

[0058] In some embodiments, the bus voltage detection module continuously acquires the DC bus voltage and compares it with the target value. The resulting error signal is processed by the voltage outer loop controller and outputs the total current setpoint. The dynamic distributor acquires the state of charge (SOC) values ​​of the two batteries in real time and selects a proportional allocation or forced equalization strategy based on the relative relationship between the SOC and the target value. For example, when both SOC values ​​are higher than the target value, the charging current is allocated proportionally according to the SOC. The allocated independent current setpoints are input to the two BuckBoost current inner loops respectively. The current inner loops compare the deviation between the setpoint and the actual current, generate a current adjustment value through a PI regulator, and finally calculate the PWM duty cycle based on the adjustment value and the battery voltage to drive the corresponding switching transistor.

[0059] Understandably, traditional single-channel battery systems cannot dynamically adjust current distribution based on differences in battery state, leading to uneven charging and discharging among battery packs. This solution uses a dynamic distributor to determine the SOC state in real time and switch strategies accordingly. For example, when there are SOC differences between battery packs, it forces equalization charging and discharging, thereby preventing overcharging or over-discharging of a single battery. Simultaneously, two independent current inner loops can control the BuckBoost circuit independently, allowing the two battery packs to operate in parallel without interference. Through the above technical solution, this application can dynamically adjust the charging and discharging current distribution according to the actual battery state. For example, when there is a large SOC difference between battery packs, it forces equalization current to shorten the equalization time, while when the difference is small, it distributes the current proportionally to maintain system efficiency. The two independently controlled current inner loops further improve current tracking accuracy, such as reducing current fluctuations when the BuckBoost circuit switches charging and discharging modes, thereby improving system stability and battery lifespan.

[0060] This application further proposes a dynamic allocator including a SOC comparison unit for determining the sign relationship between |SOC1-target SOC| and |SOC2-target SOC|; a strategy selection unit for activating a proportional allocation or forced equalization strategy based on the sign relationship; and a current calculation unit for outputting signed Ibat1_ref and Ibat2_ref.

[0061] The SOC comparison unit is a module used to detect the deviation direction of the two battery states of charge from the target value. It can be implemented using a differential comparator circuit or software algorithm. By calculating the absolute difference between the SOC of the two batteries and the target value in real time, it determines the sign relationship to identify the charging and discharging state differences of the battery pack. The strategy selection unit is a logic module that switches the control strategy based on the SOC comparison result. It can be implemented using a programmable logic device or embedded conditional statements. By identifying whether the deviation directions of the two SOCs are consistent, it triggers the corresponding current allocation mode. The current calculation unit is a calculation module that executes the current allocation algorithm. It can be implemented using an operational amplifier circuit or a digital signal processor. Based on the activated allocation strategy, it performs mathematical calculations on the total system current setpoint to generate two independent current command values.

[0062] In some embodiments, the SOC comparison unit continuously acquires the real-time SOC values ​​of the two batteries and calculates the absolute value of their deviation from the target SOC. When the deviation directions of the two SOCs are detected to be the same (e.g., both are higher than or lower than the target value), the strategy selection unit transmits the enable signal of the proportional allocation strategy to the current calculation unit. At this time, the current calculation unit allocates the total current according to the preset weighting coefficient. When the deviation directions of the two SOCs are detected to be opposite (e.g., one is higher than the target value while the other is lower than the target value), the strategy selection unit switches to the forced equalization strategy, and the current calculation unit executes the asymmetric current allocation algorithm. This process is implemented in real-time through hardware circuits or software threads to ensure that the current allocation logic dynamically matches the battery state.

[0063] This application further proposes that the output of the inner current loop be used to generate a PWM1 signal to drive the first BuckBoost switch, and to generate a PWM2 signal to drive the second BuckBoost switch.

[0064] The output of the inner current loop refers to the circuit node that generates the duty cycle control signal after processing by the proportional-integral regulator. Specifically, it can be implemented using the PWM output pin of a digital signal processor or microcontroller, used to convert the current regulation into a control signal for the on-time of the switching transistor. The PWM1 signal refers to the pulse width modulation waveform of the switching transistor in the first BuckBoost circuit, which can be implemented using a fixed-frequency, variable-duty-cycle modulation method. Adjusting the duty cycle controls the inductor charging and discharging time to regulate the battery charging and discharging current. The PWM2 signal refers to the pulse width modulation waveform of the switching transistor in the second BuckBoost circuit, which can be implemented using a duty cycle parameter with the same frequency as the first circuit but calculated independently, enabling decoupling control between the two circuits. The BuckBoost switching transistor is a power semiconductor device that implements the buck-boost topology, specifically an insulated-gate bipolar transistor (IGBT) or a metal-oxide-semiconductor field-effect transistor (MOSFET), which regulates the energy transfer direction between the battery and the DC bus through switching action.

[0065] In some embodiments, the first BuckBoost current inner loop inputs the deviation between the independent current setpoint Ibat1_ref and the actual current value Ibat1 into a proportional-integral regulator, outputting a current regulation value Ibat1_out, and generating a PWM1 signal using a duty cycle calculation formula. This signal is sent to the drive circuit of the first switching transistor, for example, through an optocoupler isolation circuit to control the switching transistor's on and off states. Simultaneously, the second current inner loop generates a PWM2 signal in the same manner, independently controlling the second switching transistor. The duty cycles of the two PWM signals are dynamically adjusted according to the real-time current regulation value; for example, when Ibat1_out increases, the on-time ratio of PWM1 increases accordingly to increase the charging current.

[0066] This application further proposes that the target SOC is a programmable parameter, and the value range of the target SOC is 20% to 80%.

[0067] The target SOC is a programmable parameter, meaning the system allows users or upper-level control units to adjust the target value of the state of charge according to actual needs. This can be remotely set through the embedded system's parameter configuration interface or communication protocol, enabling the system to adapt to different battery types or application scenarios. The value range of 20% to 80% means the target SOC setting is limited to this range. This is achieved through software algorithms that perform boundary checks on the input parameters. The selection of this range is based on the chemical characteristics of lithium batteries, avoiding battery capacity degradation caused by deep discharge or overcharging.

[0068] In some embodiments, the target SOC value in a dual-battery energy storage inverter control system can be dynamically configured through a human-machine interface or communication module. For example, when the system is applied to a grid peak-shaving scenario, the operator can set the target SOC to 40% to reserve more energy storage space; while in an off-grid power supply scenario, the target SOC can be adjusted to 70% to extend the power supply duration. When the system executes the current distribution strategy according to this parameter, it can ensure that the state of charge of both batteries is always within the preset safe range, avoiding battery performance degradation caused by overcharging or over-discharging.

[0069] This application further proposes a dual-channel battery energy storage inverter device, wherein the process of acquiring SOC1 and SOC2 includes calculating the remaining power of the corresponding battery based on the coulomb integral method and the sampling period.

[0070] The Coulomb integration method calculates the remaining battery capacity by integrating the battery's charging and discharging current in real time. Specifically, it uses a current sensor to collect instantaneous current values ​​and combines this with time integration. The advantage of this method is that it maintains calculation accuracy under dynamic operating conditions, avoiding the hysteresis error inherent in the voltage method. The sampling period refers to the time interval between current samplings, and can be in the millisecond range, such as 10ms to 100ms, which ensures real-time calculation while reducing the processor's computational load.

[0071] In some embodiments, during charging and discharging, current sensors collect instantaneous current values ​​from both batteries at fixed intervals, for example, once every 20ms. For the first battery, the current value of each sampling period is multiplied by the time interval, and the accumulated charge is obtained. This accumulated charge is then combined with the battery's rated capacity to calculate SOC1. The second battery uses the same process to calculate SOC2. By continuously updating the integral calculation, the estimation bias caused by polarization effects in the open-circuit voltage method can be eliminated, thereby providing accurate state-of-charge data for dynamic current distribution.

[0072] In some specific implementations, the current sensor can be a Hall effect sensor, whose measurement range can cover the peak value of the battery charging and discharging current, for example, ±50A. The integration module can be embedded in a microcontroller, triggering sampling and calculation via timer interrupts. To prevent cumulative integration errors, the system can be calibrated periodically using the open-circuit voltage method, for example, by initiating the calibration procedure when the battery has been idle for more than a set period of time.

[0073] This application further proposes a dual-channel battery energy storage inverter device, including a control system, a first BuckBoost circuit, a second BuckBoost circuit, and an H4 inverter bridge circuit. The first BuckBoost circuit includes an inductor L1, a switch Q1, and a diode D1, connected to Bat1 and Vbus; the second BuckBoost circuit includes an inductor L2, a switch Q2, and a diode D2, connected to Bat2 and Vbus; the input terminal of the H4 inverter bridge circuit is connected to Vbus, and the output terminal is connected to the power grid.

[0074] The BuckBoost circuit refers to a DC-DC converter circuit capable of step-up and step-down functions. It can be implemented using a topology combining inductors, switching transistors, and diodes. For example, the output voltage is adjusted by controlling the inductor's charging and discharging time through adjusting the duty cycle of the switching transistors. The H4 inverter bridge circuit is a full-bridge inverter structure composed of four switching devices, specifically IGBTs or MOSFETs, used to convert DC bus voltage to AC power for grid connection. Inductors L1 and L2 are used for energy storage and filtering, switching transistors Q1 and Q2 are controlled by PWM signals for on / off switching, and diodes D1 and D2 are used to prevent reverse current flow.

[0075] In some embodiments, the device connects to two batteries via two independent BuckBoost circuits, allowing independent control of the charging and discharging current of each battery. The control system dynamically allocates current based on the battery's state of charge (SOC). For example, when both batteries have an SOC above or below a target value, a proportional allocation strategy is used; when one battery has an SOC above the target value while the other has an SOC below the target value, a forced balancing strategy is used. The allocated current setpoint is input to the inner current loop of each of the two BuckBoost circuits, generating corresponding PWM signals to drive the switching transistors. The H4 inverter bridge converts the DC bus voltage into AC power, enabling energy exchange with the power grid.

[0076] The above are merely embodiments of this application and are not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A charging and discharging control method for a dual-channel battery energy storage inverter, applied to a topology including two independent BuckBoost circuits and an H4 inverter bridge, characterized in that, The method includes: Detect the DC bus voltage Vbus and compare it with the target value Vbus_ref to generate a bus voltage error signal; Input the error signal into the voltage outer-loop controller to output the system total current reference value Ibat_ref; Obtain the state of charge value SOC1 of the first battery and the state of charge value SOC2 of the second battery in real time; Dynamically select the current distribution strategy: when both SOC1 and SOC2 are higher than or lower than the target SOC, execute the proportional distribution strategy; when one SOC value > target SOC and the other < target SOC, execute the forced equalization strategy; Distribute Ibat_ref into the independent current reference value Ibat1_ref of Bat1 and the independent current reference value Ibat2_ref of Bat2; Input Ibat1_ref and Ibat2_ref into the first BuckBoost current inner-loop and the second BuckBoost current inner-loop respectively to generate PWM signals for driving the two BuckBoost switching tubes.

2. The charging and discharging control method for a dual-channel battery energy storage inverter according to claim 1, characterized in that, The proportional distribution strategy includes: When Ibat_ref > 0, perform common charging: Ibat1_ref = Ibat_ref × SOC2 / (SOC1 + SOC2), Ibat2_ref = Ibat_ref × SOC1 / (SOC1 + SOC2); When Ibat_ref < 0, perform common discharging: Ibat1_ref = Ibat_ref × SOC1 / (SOC1 + SOC2), Ibat2_ref = Ibat_ref × SOC2 / (SOC1 + SOC2).

3. The charging and discharging control method for a dual-channel battery energy storage inverter according to claim 1, characterized in that, The forced equalization strategy includes: When Ibat_ref > 0 and SOC1 > SOC2, perform unbalanced charging: Ibat1_ref = -Ibat_ref, Ibat2_ref = 2 × Ibat_ref; When Ibat_ref > 0 and SOC1 < SOC2, perform unbalanced charging: Ibat1_ref = 2 × Ibat_ref, Ibat2_ref = -Ibat_ref; When Ibat_ref < 0 and SOC1 > SOC2, perform unbalanced discharging: Ibat1_ref = 2 × Ibat_ref, Ibat2_ref = -Ibat_ref; When Ibat_ref < 0 and SOC1 < SOC2, perform unbalanced discharging: Ibat1_ref = -Ibat_ref, Ibat2_ref = 2 × Ibat_ref.

4. The charging and discharging control method for a dual-channel battery energy storage inverter according to claim 1, characterized in that, The generating of the PWM signals for driving the two BuckBoost switching tubes includes: For the first BuckBoost circuit: Subtract the independent current reference value Ibat1_ref of the first battery from the actual current value Ibat1 to obtain a first current deviation signal; Input the first current deviation signal into a first PI regulator to output a first current regulation value Ibat1_out; Generate a first PWM signal for driving the first switching tube through the following formula: PWM1 = 1 − Vbat1 / (|Ibat1_out| + Vbus_ref), where Vbat1 is the voltage of the first battery and Vbus_ref is the target value of the bus voltage; For the second BuckBoost circuit: the difference between the independent current setpoint Ibat2_ref of the second battery and the actual current value Ibat2 is used to obtain the second current deviation signal; the second current deviation signal is input to the second PI regulator, and the second current regulation value Ibat2_out is output; the second PWM signal driving the second switching transistor is generated by the following formula: PWM2 = 1 − Vbat2 / (∣Ibat2_out∣ + Vbus_ref), where Vbat2 is the voltage of the second battery channel.

5. A dual-channel battery energy storage inverter control system, characterized in that, include: Bus voltage detection module, connected to DC bus to acquire Vbus signal; The voltage outer loop controller receives the Vbus error signal at its input and generates Ibat_ref at its output. A dynamic allocator is configured to perform the current allocation strategy as described in any one of claims 1 to 4; The first BuckBoost current inner loop and the second BuckBoost current inner loop are connected in parallel.

6. The dual-channel battery energy storage inverter control system according to claim 5, characterized in that, The dynamic allocator includes: The SOC comparison unit is used to determine the sign relationship between |SOC1-target SOC| and |SOC2-target SOC|. The strategy selection unit is used to activate proportional allocation or forced equilibrium strategies based on symbolic relationships. The current calculation unit is used to output signed Ibat1_ref and Ibat2_ref.

7. The dual-channel battery energy storage inverter control system according to claim 5, characterized in that, The output of the inner current loop is used to generate a PWM1 signal to drive the first BuckBoost switch and a PWM2 signal to drive the second BuckBoost switch.

8. The dual-channel battery energy storage inverter control system according to claim 5, characterized in that, The target SOC is a programmable parameter, and the value range of the target SOC is 20% to 80%.

9. The dual-channel battery energy storage inverter control system according to claim 5, characterized in that, The process of obtaining SOC1 and SOC2 includes: calculating the remaining power of the corresponding battery based on the Coulomb integral method and the sampling period.

10. A dual-channel battery energy storage inverter, characterized in that, include: The control system as described in any one of claims 5 to 9; The first BuckBoost circuit includes an inductor L1, a switching transistor Q1, and a diode D1, connected to Bat1 and Vbus. The second BuckBoost circuit includes inductor L2, switching transistor Q2, and diode D2, connected to Bat2 and Vbus. The H4 inverter bridge circuit has its input terminal connected to Vbus and its output terminal connected to the power grid.

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