A charging control circuit, method and control device of an energy storage inverter battery

Abstract

The application discloses a charging control circuit, method and control device of an energy storage inverter battery, relates to the technical field of energy storage inverters, and comprises a bus voltage loop, an input end of which is connected with a bus voltage reference signal and a bus voltage feedback signal; a battery voltage loop, an input end of which is connected with a battery voltage reference signal and a battery voltage feedback signal; and an inner loop current given module, an output end of the bus voltage loop being connected with an inverter after which the output end of the battery voltage loop is jointly connected with an input end of a minimum selector, an output end of the minimum selector being connected to an input end of the inner loop current given module, the inner loop current given module being used for comparing a current given signal output by the minimum selector with a battery current feedback signal, outputting a duty cycle signal after adjustment by a PI controller, and the duty cycle signal being used for controlling the on and off time proportion of a switch tube in a Buck-Boost circuit corresponding to the energy storage inverter battery, so that the battery overvoltage can be effectively prevented and the charging process can be ensured to be safe.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage inverters, in particular to a charging control circuit, method and control device for an energy storage inverter battery. BACKGROUND

[0002] With the development of energy storage inverter technology, the accuracy and safety of battery charging control are increasingly required. Traditional energy storage inverter battery charging control circuits often have the following problems: after the battery is fully charged, due to insufficient control accuracy, a small current may continue to flow into the battery, causing overvoltage of the battery, which not only shortens the service life of the battery, but also may damage the battery. In addition, the existing charging control circuit cannot accurately control the switching tube when adjusting the charging current and voltage, thereby affecting the charging efficiency and stability of the system.

[0003] Currently, in some energy storage inverter systems, although a synchronous driving strategy is adopted to reduce loss and improve the efficiency of the battery charging part, due to design defects of the control loop, the problem of battery overvoltage cannot be completely solved. In order to overcome these shortcomings, a charging control circuit is needed that can accurately control the battery charging process, prevent overvoltage, and realize hardware shutdown after the battery is fully charged. SUMMARY

[0004] The purpose of the present application is to provide a charging control circuit, method and control device for an energy storage inverter battery, which has the advantages of preventing battery overvoltage, improving charging safety and prolonging the service life of the battery.

[0005] The present application provides a charging control circuit for an energy storage inverter battery, comprising: a bus voltage loop, the input end of which is connected to a bus voltage reference signal and a bus voltage feedback signal; a battery voltage loop, the input end of which is connected to a battery voltage reference signal and a battery voltage feedback signal; an inner loop current given module, the output end of the bus voltage loop is connected to an inverter after a phase inverter, and the output end of the battery voltage loop is commonly connected to the input end of a minimum selector, the output end of the minimum selector is connected to the input end of the inner loop current given module, the inner loop current given module is used to compare the current given signal output by the minimum selector with the battery current feedback signal, and output a duty cycle signal after adjustment by a PI controller, the duty cycle signal is used to control the on and off time proportion of the switching tube in the Buck-Boost circuit corresponding to the energy storage inverter battery.

[0006] In some embodiments, the bus voltage loop includes a bus voltage comparator configured to compare a bus voltage reference signal and a bus voltage feedback signal, and output a bus voltage error signal to an inverter; the battery voltage loop includes a battery voltage comparator configured to compare a battery voltage reference signal and a battery voltage feedback signal, and output a battery voltage error signal, and the battery voltage error signal is input to an input terminal of a minimum selector connected to the inverter.

[0007] In some embodiments, the inner loop current given module includes a current comparator configured to compare a current given signal output by the minimum selector and a battery current feedback signal, and output a current error signal; and a current PI controller having an input terminal connected to an output terminal of the current comparator, and configured to perform proportional integral control on the current error signal, and output a duty cycle signal.

[0008] In some embodiments, the battery of the energy storage inverter charging control circuit further includes a current sampling terminal connected to the inner loop current given module, and configured to collect the battery current feedback signal, and rectify the signal when the current is less than a preset current value, and retain only positive values.

[0009] In some embodiments, the battery of the energy storage inverter charging control circuit further includes a drive waveform control module connected to an output terminal of the PI controller, and configured to control drive waveforms of switching tubes in a Buck-Boost circuit according to the duty cycle signal: when the battery current is greater than a current threshold value, the Buck tube and the Boost tube are controlled to output complementarily; and when the battery current is less than the current threshold value, the Boost tube is controlled to exit, and only the Buck tube works.

[0010] In some embodiments, controlling the drive waveforms of the switching tubes in the Buck-Boost circuit according to the duty cycle signal further includes: when the battery current indicates that the energy storage inverter battery is in a full battery state, adjusting the duty cycle to make the Buck tube closed, and all tubes in the Buck-Boost circuit closed, to complete a hardware shutdown.

[0011] In some embodiments, a charging control method of an energy storage inverter battery includes: obtaining an error between a bus voltage reference signal and a bus voltage feedback signal through a bus voltage loop; obtaining an error between a battery voltage reference signal and a battery voltage feedback signal through a battery voltage loop; taking a minimum value of the bus voltage loop output signal and the battery voltage loop output signal after inverting the bus voltage loop output signal to obtain a current given signal; comparing the current given signal with the battery current feedback signal, and outputting a duty cycle signal through a PI controller; and controlling on and off time ratios of switching tubes in a Buck-Boost circuit corresponding to the energy storage inverter battery according to the duty cycle signal.

[0012] In some embodiments, further comprising: when the battery current is greater than the current threshold, controlling the Buck tube and the Boost tube to output complementary drive waveforms; when the battery current is less than the current threshold, controlling the Boost tube to exit and only the Buck tube to work; and when the battery is fully charged, adjusting the duty cycle to make the Buck tube closed and all Buck-Boost tubes closed to complete the hardware shutdown.

[0013] In some embodiments, a control device of a battery of an energy storage inverter, comprising: the above charging control circuit; a discharging control circuit, the discharging control circuit comprising a battery discharging control loop for controlling the battery to discharge to a load when the battery needs to be discharged.

[0014] In some embodiments, further comprising a control logic unit for calling the charging control circuit when the battery is charging and calling the discharging control circuit when the battery is discharging.

[0015] As can be seen from the above, the charging control circuit, method and control device of a battery of an energy storage inverter provided by the present application generate a current given signal through the signals output by the bus voltage loop and the battery voltage loop via a minimum selector, combine an inner loop current given module to accurately adjust a duty cycle signal, realize dynamic control of Buck-Boost circuit switching tubes, effectively prevent battery overvoltage and ensure the safety of the charging process, and have the advantages of improving charging efficiency and prolonging the service life of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0016] The accompanying drawings are used to provide a further understanding of the technical solutions of the present application, and constitute a part of the specification, and are used to explain the technical solutions of the present application together with the embodiments of the present application, and do not constitute a limitation to the technical solutions of the present application.

[0017] The present application will be further described below in combination with the drawings and embodiments;

[0018] Figure 1 A circuit schematic diagram of a charging control circuit of a battery of an energy storage inverter provided by an embodiment of the present application is provided.

[0019] Figure 2 A flowchart of a charging control method of a battery of an energy storage inverter provided by an embodiment of the present application is provided.

[0020] Figure 3 A circuit schematic diagram of a discharging control circuit of a battery of an energy storage inverter provided by an embodiment of the present application is provided.

[0021] Figure 4 A schematic diagram of Buck tube and Boost tube complementary output and Buck-Boost drive waveform provided by an embodiment of the present application is provided when the battery current is greater than a certain value.

[0022] Figure 5Provided by the embodiment of the application, the battery current is less than a certain value, the Boost tube exits, only the Buck tube has drive, the schematic diagram of the Buck-Boost drive waveform. DETAILED DESCRIPTION

[0023] The technical solutions in the application will be described clearly and completely below in combination with the drawings in the application. Obviously, the described embodiments are only some of the embodiments of the application, not all the embodiments. The components of the application described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the application provided in the drawings is not intended to limit the scope of the claimed application, but only represents selected embodiments of the application. Based on the embodiments of the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. Meanwhile, in the description of the application, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0024] In the prior art, the energy storage inverter battery charging control technology faces many challenges. The traditional control method is easy to cause small current to continue to flow into the battery due to insufficient control accuracy after the battery is fully charged, causing overvoltage phenomenon, affecting the service life and safety of the battery. Although some systems use synchronous driving strategy to improve efficiency, due to the design defects of the control loop, the overvoltage problem cannot be effectively solved. For example, in a photovoltaic energy storage system, when the photovoltaic panel output fluctuates, the charging circuit is difficult to coordinate the dynamic balance of the bus voltage and the battery voltage, resulting in unstable charging process.

[0025] In order to solve the above problems, the research and development team deeply analyzes the charging control logic. Research has found that the root cause of the overvoltage phenomenon is the lack of double closed loop coordinated control of bus voltage and battery voltage. Further experiments have found that if only relying on single voltage loop adjustment, current overshoot is easy to occur under system disturbance. Based on this, the team proposes to process the output signals of the bus voltage loop and the battery voltage loop together to participate in the decision of the current given value, and limit the upper limit of the charging current by selecting the minimum value. At the same time, in order to realize the hardware level shutdown protection, it is necessary to introduce the drive logic adjustment mechanism based on the duty cycle signal at the end of the control loop.

[0026] REFERENCE Figure 1 , Figure 1The circuit schematic of the charging control circuit of the energy storage inverter battery provided by the embodiment of the present application is shown in the figure, wherein 101 (IBatRef) represents a battery current reference value, which is a current given signal obtained after MIN module processing, used for subsequent comparison with a battery current feedback signal to adjust the battery charging current; (IBatFb) represents a battery current feedback signal, which is an actually measured battery current value, used for comparison with the reference value to form a closed-loop control; 103 (VbatRef) represents a battery voltage reference signal, which is a desired battery voltage value to be maintained, used for comparison in the battery voltage loop; 104 (VbusFb) represents a bus voltage feedback signal, which is an actually measured bus voltage value, used for comparison in the bus voltage loop; 105 (VbatFb) represents a battery voltage feedback signal, which is an actually measured battery voltage value, used for comparison in the battery voltage loop; the present application proposes a charging control circuit including a bus voltage loop, a battery voltage loop, a minimum selector and an inner loop current given module, the input end of the bus voltage loop is connected with a bus voltage reference signal and a feedback signal, the input end of the battery voltage loop is connected with a battery voltage reference signal and a feedback signal. The output of the bus voltage loop is processed by an inverter and is jointly connected to the minimum selector with the output of the battery voltage loop, and the output end thereof is connected to the inner loop current given module, which compares the current given signal with the battery current feedback signal and generates a duty cycle signal through a PI controller, used for controlling the on-off time ratio of the switch tube in the Buck-Boost circuit.

[0027] Further, corresponding Figure 1It can be understood that VbusRef is the bus voltage reference signal, which represents the bus voltage value expected to be maintained by the system; VbusFb is the bus voltage feedback signal, which represents the actually measured bus voltage value; VbatRef is the battery voltage reference signal, which represents the battery voltage value expected to be maintained by the system; VbatFb is the battery voltage feedback signal, which represents the actually measured battery voltage value; PI is a proportional-integral controller, which is used to convert the input signal (voltage error or current error) into a control signal to reduce the error and stabilize the system; MIN is a minimum selector, which is used to select the minimum value of the signal after the bus voltage loop output is inverted and the battery voltage loop output signal; IBatRef is the battery current reference value, which is the expected battery charge / discharge current value calculated according to the voltage error; IBatFb is the battery current feedback value, which represents the actually measured battery charge / discharge current value; IMax is the set maximum charge / discharge current limit, which is used to protect the battery from overcharging or overdischarging; -IMax is the negative value of the set maximum charge current limit, which is used to limit the direction of the charging current; the bus voltage loop is composed of the bus voltage reference signal (VbusRef) and the bus voltage feedback signal (VbusFb), which is used to generate a bus voltage error signal; the battery voltage loop is composed of the battery voltage reference signal (VbatRef) and the battery voltage feedback signal (VbatFb), which is used to generate a battery voltage error signal; the inner loop current given module is used to compare the current given signal output by the minimum selector with the battery current feedback signal (IBatFb), and the duty cycle signal is output after adjustment by the PI controller; the inverter is used to invert the output signal of the bus voltage loop; the BuckBoost circuit is a DC-DC conversion circuit topology, which is used to adjust the battery charging current and voltage, and the on and off time ratio of the switch tube is controlled by the duty cycle signal.

[0028] The bus voltage loop refers to a closed-loop control unit for monitoring the bus voltage state, which can be implemented by a voltage comparator and an error amplifier, and an adjustment signal is generated by comparing the difference between the bus voltage reference value and the actual feedback value. The battery voltage loop refers to a closed-loop control unit for monitoring the battery terminal voltage, which can be implemented by a voltage comparison circuit with a same-phase processing function, and the output signal represents the deviation of the battery charging voltage. The minimum selector refers to a logic device with multiple input signal filtering function, which can be implemented by an analog comparison circuit or a digital processing unit, and is used to select the minimum value of the input signal as the current given reference. The inner loop current given module refers to a control unit with current closed-loop regulation function, which can be implemented by a current regulator with PI compensation, and the duty cycle control signal is generated by comparing the difference between the given current and the actual current in real time.

[0029] Specifically, the charging control process is divided into multiple stages of coordinated regulation. The bus voltage loop continuously monitors the bus voltage state. When it is detected that the bus voltage exceeds the preset range, its output signal is inverted and input into the minimum selector together with the output signal of the battery voltage loop. The selector automatically selects the smaller value of the two signals as the current given reference, ensuring that the charging current is always within the safety threshold. The inner loop current given module compares the reference value with the actual collected battery current in real time, and the error signal is accurately adjusted by the PI controller to output a PWM signal with a specific duty cycle. This signal controls the on and off time of the switch tube in the Buck-Boost topology through the drive circuit, thereby dynamically adjusting the charging power. When the system detects that the battery is close to the full state, the duty cycle signal can be automatically zeroed to achieve hardware-level charging shutdown.

[0030] It is worth noting that, compared with the prior art, the present scheme effectively solves the overvoltage risk of traditional single-loop control systems through double-voltage ring coordinated control and minimum selection mechanism. The single PI regulator structure commonly used in the prior art cannot coordinate the competitive relationship between the bus voltage and the battery voltage, while the minimum selection strategy of the present scheme can automatically balance the output requirements of the two voltage loops. In addition, the existing charging circuit usually relies on software shutdown instructions after the battery is fully charged, which has a risk of response delay, while the duty cycle direct control mechanism of the present scheme can achieve millisecond-level hardware shutdown, significantly improving safety performance.

[0031] Through the above technical scheme, the present application can effectively prevent battery overvoltage phenomenon and ensure the safety and stability of the charging process. The double-closed-loop control structure enhances the adaptability of the system to bus voltage fluctuations, and the minimum selection mechanism can dynamically limit the maximum charging current to avoid battery overcharging. At the same time, the direct control method based on the duty cycle signal improves the response speed and can quickly cut off the charging circuit when the battery is full, eliminating the risk of residual current from the hardware level. This scheme is particularly suitable for energy storage inverter systems that require high-precision charging control and has significant advantages in photovoltaic energy storage, electric vehicle charging piles and other scenarios.

[0032] The present application further proposes a charging control circuit for a battery of an energy storage inverter, wherein the bus voltage loop includes a bus voltage comparator for comparing a bus voltage reference signal and a bus voltage feedback signal and outputting a bus voltage error signal to an inverter; the battery voltage loop includes a battery voltage comparator for comparing a battery voltage reference signal and a battery voltage feedback signal and outputting a battery voltage error signal, and connecting to the input end of the minimum selector after connecting to the phase inverter.

[0033] The bus voltage comparator refers to a voltage difference calculation module formed by an operational amplifier, and can be specifically implemented by a differential amplification circuit. The bus voltage comparator converts the difference between the bus voltage reference signal and the feedback signal into an error signal, and provides a basis for subsequent current setting. The inverter refers to a circuit module capable of changing the polarity of the input signal, and can be specifically implemented by a single-stage inverting amplifier circuit. The inverter adjusts the polarity of the bus voltage error signal and selects the minimum value with the battery voltage error signal. The same phase inverter refers to a buffer circuit module that maintains the polarity of the input signal, and can be specifically implemented by a voltage follower. The same phase inverter directly transmits the battery voltage error signal to the input end of the minimum value selector to avoid signal phase distortion.

[0034] Specifically, the bus voltage comparator receives the bus voltage reference signal and the feedback signal and outputs the bus voltage error signal. The error signal is adjusted in polarity by the inverter, so that the output signal of the bus voltage loop represents a negative error, while the battery voltage error signal output by the battery voltage loop is kept positive by the same phase inverter. After the two signals are input into the minimum value selector, the smaller current setting value can be accurately selected, so that the charging current is preferentially limited when the bus voltage or the battery voltage exceeds the set range. For example, when the bus voltage is lower than the reference value, the negative error signal output by the inverter will be automatically excluded by the minimum value selector, and at this time the positive error signal of the battery voltage loop will be used as the basis for current setting.

[0035] Compared with the prior art, the existing charging control scheme usually directly inputs the voltage error signal into the selector without polarity adjustment, resulting in a conflict in the signal polarity of the bus voltage loop and the battery voltage loop, which may cause the minimum value selector to misjudge. The combination of the inverter and the same phase inverter in the present scheme realizes the comparison of the two error signals under the same polarity reference, ensuring that the selector can accurately identify the voltage parameter that needs to be preferentially limited.

[0036] Through the above technical scheme, the application can accurately coordinate the control priority of the bus voltage and the battery voltage, preferentially maintain system stability when the bus voltage is abnormal, and preferentially protect the battery safety when the battery voltage is abnormal, thereby effectively avoiding the overvoltage or undervoltage problem caused by the conflict of the voltage loop control logic.

[0037] The application further proposes that the inner loop current setting module includes a current comparator and a current PI controller. The current comparator is used to compare the current setting signal output by the minimum value selector with the battery current feedback signal and output a current error signal. The input end of the current PI controller is connected with the output end of the current comparator, and is used to perform proportional integral control on the current error signal and output a duty cycle signal.

[0038] The current comparator refers to a device for comparing the difference between the current given signal and the battery current feedback signal in real time and generating an error signal. Specifically, it can be implemented by a differential amplifier or an operational amplifier circuit. Its function is to ensure the real-time tracking capability of the current closed-loop control system. The current PI controller refers to a regulator that combines proportional and integral operations. Specifically, it can be implemented by a digital signal processor or an analog circuit. It quickly responds to errors through the proportional element and eliminates steady-state errors through the integral element, achieving accurate regulation of the duty cycle signal.

[0039] Specifically, the current comparator continuously receives the current given signal from the minimum selector and the current feedback signal from the battery loop, and converts the difference between the two into an error signal in the form of voltage. The current PI controller dynamically adjusts the gain parameter according to the error signal, accumulates the error history value through integral operation, and finally outputs a duty cycle adjustment signal related to the error amplitude and time. The duty cycle signal is converted into a pulse width modulation waveform of the switching tube through the subsequent drive circuit, thereby accurately controlling the time and intensity of energy transmission in the Buck-Boost circuit.

[0040] In some embodiments, the Buck-Boost can include: a Buck circuit part (Buck) including a Buck switch tube (Buck tube), an output inductor (L), and an output capacitor (C); and a Boost circuit part (Boost) including a Boost switch tube (Boost tube), an input inductor (L'), and an output diode (D). The drive waveform control module is used to control the drive waveform of the Buck tube and the Boost tube. When the battery current is greater than a certain value, the Buck tube and the Boost tube are controlled to output complementarily. When the battery current is less than a certain value, the Boost tube is controlled to exit, and only the Buck tube works.

[0041] It can be understood that, compared with the prior art, the existing charging control circuit mainly uses single proportional regulation or open-loop control, which cannot simultaneously consider dynamic response speed and steady-state accuracy, and is prone to cause current overshoot or residual error. By introducing the current PI controller, the proportional fast response characteristic and the integral error compensation mechanism are combined, so that the regulation process of the current loop has both fast following capability and the ability to eliminate steady-state error caused by element parameter drift or load mutation.

[0042] Through the above technical solutions, the application can realize closed-loop accurate control of the battery charging current, avoid the risk of battery overvoltage caused by current regulation lag, and eliminate the small residual current at the end of charging through the integral element, ensuring that the charging circuit is completely cut off after the battery is fully charged.

[0043] The application further proposes a charging control circuit of the energy storage inverter battery, and the battery further includes a current sampling terminal connected with the inner loop current given module, the current sampling terminal is used for collecting a battery current feedback signal, and rectification processing is performed on the signal when the current is less than a preset current value, and only positive values are retained.

[0044] The current sampling terminal refers to a signal collection module used for acquiring an actual current value in a battery loop in real time, and can be specifically implemented by using a Hall sensor or a sampling resistor in cooperation with a signal conditioning circuit, and functions to convert a physical current into a voltage signal available for a control loop. The preset current value refers to a pre-set critical current threshold, which can be 0.5 A or 1 A for example, and is used for determining whether rectification processing needs to be performed on the current signal. The rectification processing refers to absolute value processing performed on an alternating component or a current signal with negative fluctuations, and can be specifically implemented by using a full-wave rectification circuit or an absolute value operation circuit, and functions to eliminate negative components in the current signal and avoid misjudgment of the control loop due to negative signals.

[0045] Specifically, in the battery charging process, the current sampling terminal continuously monitors the current value in the battery loop. When it is detected that the current value is lower than the preset current value, for example, a small ripple current occurring in the approach to the charging cutoff stage, the signal processing unit automatically starts the rectification processing function, and the negative half-wave form in the original current signal is flipped to a positive half-wave by the absolute value circuit composed of an operational amplifier, so that the finally output battery current feedback signal only contains positive components. The processed signal is transmitted to the inner loop current given module and compared with the current given signal generated by the minimum value selector, so as to ensure that the PI controller only generates a duty cycle adjustment amount based on a positive deviation signal under low current conditions, and to avoid abnormal adjustment of the duty cycle due to negative fluctuations of the current signal.

[0046] Compared with the prior art, the traditional current sampling circuit does not process the signal polarity under low current conditions, and when current oscillation occurs at the end of charging, the negative current signal may trigger the control loop to produce a reverse adjustment action, resulting in misoperation of the Buck-Boost circuit switch tube. However, the present scheme effectively eliminates the interference of negative signals on the control loop by applying rectification processing under certain conditions, so that the system can still maintain stable closed-loop regulation under low current conditions.

[0047] Through the above technical scheme, the application realizes accurate processing of the feedback signal at the end of battery charging or under low current conditions, avoids the problem of mis-triggering of the control loop caused by fluctuations in the polarity of the current signal, thereby preventing the risk of overvoltage caused by continuous injection of abnormal current when the battery is close to the full state, and improving the safety and control accuracy of the charging process.

[0048] The application further proposes that the charging control circuit of the energy storage inverter battery further comprises a drive waveform control module connected with the output end of the PI controller, used for controlling the drive waveform of the switching tube in the Buck-Boost circuit according to the duty cycle signal: when the battery current is greater than the current threshold, the complementary output of the Buck tube and the Boost tube is controlled; when the battery current is less than the current threshold, the Boost tube is controlled to exit, and only the Buck tube works.

[0049] The drive waveform control module refers to a logic unit for dynamically adjusting the working mode of the switching tube according to the current state, which can be realized by a digital signal processor or a programmable logic device, and a corresponding pulse width modulation waveform is generated by receiving the duty cycle signal. The complementary output refers to the fact that the drive signals of the Buck tube and the Boost tube are opposite in phase and have a dead time, which can be realized by setting a reverse drive circuit and a delay circuit to avoid short circuit of the upper and lower tubes. The current threshold refers to the critical value for dividing the high and low current working modes, which can be set by a programmable resistance voltage dividing network, for example, set to 10%-30% of the rated charging current. The Buck tube and the Boost tube refer to power switching devices used for buck and boost operations in the Buck-Boost topology, which can be realized by MOSFET or IGBT power modules. The hardware shutdown refers to the fact that the drive signal is directly cut off after detecting the full state of the battery, which can be realized by a comparator circuit or a latch, and circuit protection can be completed without relying on software instructions.

[0050] Specifically, after receiving the duty cycle signal from the current loop, the drive waveform control module monitors the battery current sample value in real time. When it is detected that the current is higher than the preset threshold, the module generates two complementary PWM signals to drive the Buck tube and the Boost tube respectively, so that the two tubes are alternately turned on to realize bidirectional energy flow. When the current is lower than the threshold, the module automatically turns off the drive signal of the Boost tube and only keeps the PWM output of the Buck tube, at which time the circuit works in pure buck mode. In the full state of the battery, the module adjusts the duty cycle to zero and immediately turns off all switching tube drive signals to realize the protection mechanism of hardware level circuit disconnection.

[0051] Compared with the prior art, the traditional scheme still maintains the Boost tube working when the load is light or close to the full state, resulting in additional switching loss and potential overcharging risk. The present scheme divides the working mode by the current threshold, disables the Boost tube in the low current working condition, and significantly reduces the switching loss and electromagnetic interference. In the hardware shutdown stage, the drive signal is directly cut off, which has faster response speed and higher reliability compared with software control.

[0052] By the technical solution, the application effectively solves the hidden danger of small current overcharge when the battery is close to the full state, and completely eliminates the residual current through the hardware shutdown mechanism. The dynamic switching strategy of the working mode not only guarantees the energy conversion efficiency in high current, but also optimizes the system loss in low current. The design combining complementary driving and dead zone control avoids the risk of switch tube through, and improves the stability and safety of the Buck-Boost circuit operation.

[0053] The application further adjusts the duty cycle to make the Buck tube close and all tubes of the Buck-Boost close to complete hardware shutdown after the battery is full.

[0054] Among them, adjusting the duty cycle means dynamically changing the time ratio of switch tube conduction and cut-off according to the battery current feedback signal, which can be realized by a current sensor combined with a microcontroller. When it is detected that the battery current is continuously lower than the set threshold, the duty cycle is gradually reduced to zero. Among them, hardware shutdown means directly cutting off the working signal of the switch tube through the driving circuit, which can be realized by a logic gate circuit or a driving chip. When the duty cycle is adjusted to zero, a low-level signal is output to make all switch tubes in the cut-off state.

[0055] Specifically, when the battery current continuously decreases to the threshold value representing the full state, the duty cycle signal is gradually adjusted to zero, at this time the driving signal of the Buck tube is cut off, the Boost tube is synchronously closed due to the complementary signal, and finally all switch tubes in the Buck-Boost circuit stop working. This process does not need to rely on software instructions, but directly realizes the shutdown action through hardware logic, avoiding the overcharge risk caused by software response delay.

[0056] Compared with the prior art, the existing scheme usually relies on software to detect the battery state and send shutdown instructions, which has the problem of signal transmission delay or program error leading to untimely shutdown. The present scheme directly responds to the zero state of the duty cycle through hardware logic, realizes fast shutdown at the physical level, and eliminates the uncertainty of software control.

[0057] Through the above technical solution, the application can immediately cut off the charging circuit after the battery is fully charged, avoiding the problem of battery overvoltage caused by residual current, and improving the system reliability through the hardware shutdown mechanism and reducing the battery life loss.

[0058] Reference Figure 2 , Figure 2 The application further provides a flowchart of a charging control method of a battery of an energy storage inverter; the application further provides a charging control method of a battery of an energy storage inverter, including the following steps:

[0059] Step S210, obtaining the error between the bus voltage reference signal and the bus voltage feedback signal through the bus voltage loop.

[0060] Step S220, obtaining the error between the battery voltage reference signal and the battery voltage feedback signal through the battery voltage loop;

[0061] Step S230, taking the minimum value of the bus voltage loop output signal and the battery voltage loop output signal after phase inversion processing to obtain the current given signal;

[0062] Step S240, comparing the current given signal with the battery current feedback signal, and adjusting the duty cycle signal through the PI controller;

[0063] Step S250, controlling the on and off time proportion of the switch tube in the Buck-Boost circuit corresponding to the energy storage inverter battery according to the duty cycle signal.

[0064] The bus voltage loop refers to a closed-loop control loop that generates an error signal by comparing the bus voltage reference signal and the bus voltage feedback signal. It can be implemented using a comparator combined with a PI controller, and is used to maintain the stability of the bus voltage. The phase inversion processing refers to the operation of inverting the polarity of the output signal of the bus voltage loop, for example, through an inverting amplifier circuit, so that the bus voltage error signal is converted into a negative adjustment amount. The minimum value selector refers to a logic module that selects the smaller value from two input signals, for example, through a digital comparator or an analog switch circuit, which is used to limit the amplitude of the current given signal to avoid exceeding the safe current range of the battery. The PI controller adjustment refers to the adjustment process of the proportional integral operation of the current error signal, which can be implemented using an operational amplifier circuit, and is used to eliminate steady-state error and improve dynamic response speed. The duty cycle signal control refers to controlling energy transmission by adjusting the on and off time proportion of the switch tube, for example, generating a driving waveform through a pulse width modulation circuit, which is used to accurately manage the energy flow during charging.

[0065] Specifically, the charging control method cooperates the bus voltage loop and the battery voltage loop to obtain error signals of the bus voltage and the battery voltage, respectively. The output of the bus voltage loop is phase-inverted and input into the minimum value selector together with the output of the battery voltage loop to dynamically select the smaller signal as the current given reference. The reference is compared with the real-time collected battery current feedback signal, and the generated error is converted into a duty cycle signal through the PI controller. The duty cycle signal directly acts on the switch tube driving circuit of the Buck-Boost circuit to adjust the on and off time proportion of the switch tube, realizing closed-loop control of the charging current. When the battery is close to the full state, the current given signal gradually decreases, and the duty cycle signal decreases accordingly, finally making the switch tube completely cut off, realizing hardware shutdown.

[0066] Compared with the prior art, the traditional charging control method usually only relies on a single voltage loop or current loop, and cannot effectively coordinate the balance of the bus voltage and the battery voltage, and is prone to overvoltage or overcurrent due to error accumulation. The method can dynamically limit the upper limit of the current given signal through the error signal of the double voltage loop and the minimum value selection logic, and prevent the battery from being overcharged. At the same time, by inversely processing the bus voltage error signal, the problem that current is still injected when the bus voltage is too high can be avoided, and the stability of the system under various working conditions can be ensured.

[0067] Through the above technical solutions, the battery charging process can be accurately controlled, the charging current is automatically reduced when the battery is close to full, and the overvoltage problem caused by the continuous flow of small current is avoided. By dynamically adjusting the duty cycle signal, it is ensured that the switch tube of the Buck-Boost circuit works within a safe range, effectively prolonging the service life of the battery. The hardware shutdown mechanism can completely cut off the energy transmission after the battery is fully charged, eliminating the delay risk existing in the traditional software shutdown, and improving the safety and reliability of the system.

[0068] The application further proposes that in the charging control method of the energy storage inverter battery, when the battery current is greater than the current threshold, the complementary output drive waveform of the Buck tube and the Boost tube is controlled; when the battery current is less than the current threshold, the Boost tube is controlled to exit, and only the Buck tube works; and when the battery is fully charged, the duty cycle is adjusted to make the Buck tube closed, and all tubes of the Buck-Boost are closed, and the hardware shutdown is completed.

[0069] The current threshold refers to a preset critical value for distinguishing the battery charging and discharging working modes, which can be realized by a programmable comparator, and different current threshold ranges are set to trigger the corresponding control logic switching. The complementary output drive waveform refers to the drive signals of the Buck tube and the Boost tube being opposite in phase, which can be generated by a PWM controller to avoid short circuit caused by the simultaneous conduction of the two tubes. The adjustment of the duty cycle refers to changing the on-time ratio of the switch tube, which can be realized by adjusting the output signal of the current loop PI controller to gradually reduce the duty cycle to zero, so that the Buck tube is completely shut down. The hardware shutdown refers to directly cutting off the drive signal of the switch tube, which can be realized by a logic gate circuit or the enable terminal of a drive chip to ensure that all tubes are in the off state.

[0070] Specifically, during the battery charging process, the current sampling module monitors the battery current in real time, and when the current value exceeds the preset threshold, the control circuit generates complementary PWM signals to drive the Buck tube and the Boost tube to alternate conduction, thereby reducing loss and improving efficiency through synchronous rectification. When the current decreases below the threshold, the drive signal of the Boost tube is disabled, and only the Buck tube works, avoiding the additional loss caused by the Boost circuit. After the battery voltage reaches the full state, the control circuit gradually reduces the duty cycle to zero, at which point the Buck tube is completely closed, and the drive signal is cut off by hardware logic, ensuring that the Boost tube is also in the off state, completely eliminating residual current.

[0071] Compared with the prior art, the traditional method only reduces the duty cycle after the battery is full through software control, and cannot completely eliminate the small current freewheeling problem caused by parasitic parameters. The present scheme directly cuts off the drive signal of all switching tubes through hardware shutdown logic, avoiding the delay or error existing in software control, and combining with the current threshold to divide the working mode, disabling the Boost tube in low current working condition, reducing the power device loss and improving the system efficiency.

[0072] Through the above technical scheme, the present application can completely solve the overvoltage problem caused by residual current after the battery is full, effectively prolong the service life of the battery, and at the same time, through dynamic adjustment of the working mode of the switching tube, reduce the system running loss and improve the energy conversion efficiency, enhance the safety and stability of the charging control.

[0073] The present application further proposes a control device of an energy storage inverter battery, which comprises a charging control circuit, a discharging control circuit and a control logic unit. The charging control circuit comprises a bus voltage loop, a battery voltage loop, an inner loop current given module and a drive waveform control module; the discharging control circuit comprises a battery discharging control loop for controlling the battery to discharge to the load when the battery needs to discharge; and the control logic unit is used to call the charging control circuit when the battery is charging, and call the discharging control circuit when the battery is discharging.

[0074] The charging control circuit refers to a circuit structure for cooperatively adjusting the duty cycle signal through double voltage loops and current loops, which can be specifically implemented by a bus voltage comparator, a battery voltage comparator, a minimum selector and a PI controller combination. Its function is to realize accurate tracking and control of voltage and current during the charging process.

[0075] In some embodiments, reference is made to Figure 3 , Figure 3The circuit schematic diagram of the discharge control circuit of the energy storage inverter battery provided by the embodiment of the application is a closed-loop regulation system for managing the battery discharge process, and can be implemented by using a discharge current sampling module, an error comparator, and a drive signal generation module. The discharge control circuit functions to ensure stable output of the discharge process and avoid over-discharge of the battery. The control logic unit is a decision module for switching the charge and discharge modes, and can be implemented by using a microcontroller or a programmable logic device. The control logic unit functions to automatically select a charge and discharge path according to the battery state and avoid control conflicts.

[0076] wherein VbusRef is the bus voltage reference signal, representing the bus voltage value expected to be maintained by the system; VbusFb is the bus voltage feedback signal, representing the actually measured bus voltage value; PI is a proportional-integral controller, used to convert the input signal (voltage error or current error) into a control signal to reduce the error and stabilize the system; Max is a maximum value selector, used to take the maximum value between the bus voltage loop output signal and zero to prevent the current from reversing; IBatRef is the battery current reference value, which is the expected battery charge / discharge current value calculated according to the voltage error; IBatFb is the battery current feedback value, representing the actually measured battery charge / discharge current value; and the battery discharge control loop is used to control the battery to discharge to the load when the battery needs to be discharged, and includes the bus voltage loop and the battery current loop.

[0077] Specifically, the charge control circuit collects voltage error signals through the bus voltage loop and the battery voltage loop, generates a current setpoint signal after processing by an inverter and a minimum value selector, outputs a duty cycle signal through a current comparator and a PI controller, and finally adjusts the on-time ratio of the switch tube in the Buck-Boost circuit through a drive waveform control module. The discharge control circuit adjusts the discharge current and generates the corresponding drive signal by monitoring the load demand in real time through the battery discharge control loop. The control logic unit switches between the charge and discharge modes by detecting the battery voltage or current signal, for example, switches to the discharge mode when the battery voltage reaches a preset threshold.

[0078] In some specific embodiments, the discharge control loop can integrate a current feedforward compensation function to cope with load mutations, for example, when the load power suddenly increases, the drive signal is quickly adjusted through feedforward compensation. The control logic unit can use a priority judgment mechanism, for example, when the power grid is powered off, the discharge control circuit is preferentially called to supply power to the critical load.

[0079] Compared with the prior art, the existing energy storage inverter control device usually only contains a charging control function, lacks a discharging control loop and mode switching logic, resulting in that the charging and discharging processes cannot be seamlessly connected, and there is a risk of over-discharging of the battery. The scheme realizes integrated management of the charging and discharging processes and hardware-level mode switching by integrating a charging and discharging double control loop and a control logic unit, and improves the system safety and response speed.

[0080] Through the above technical scheme, the application solves the problem that the traditional energy storage inverter battery control device cannot effectively coordinate the charging and discharging processes, avoids the life attenuation caused by overvoltage or overdischarge of the battery, and improves the system reliability through hardware shutdown and mode switching functions. For example, after the battery is fully charged, the control logic unit can immediately shut down the charging circuit and enable the discharging preparation state, thereby eliminating the damage of residual current to the battery.

[0081] The application further provides a control device for a battery of an energy storage inverter, comprising a charging control circuit, a discharging control circuit and a control logic unit; the discharging control circuit comprises a battery discharging control loop for controlling the battery to discharge to a load when the battery needs to be discharged; and the control logic unit is used for calling the charging control circuit when the battery is charging, and calling the discharging control circuit when the battery is discharging.

[0082] The control logic unit is a module for switching the charging and discharging modes based on the battery state, and can be realized by a microcontroller or a programmable logic device, which judges whether the charging or discharging operation needs to be performed by monitoring the battery voltage and current signals in real time. The battery discharging control loop is a closed-loop regulation system composed of a voltage comparator and a PI controller, which can adopt a double-loop structure of an outer voltage loop and an inner current loop, and realizes stable discharging by adjusting the load end voltage.

[0083] Specifically, when the battery is in a charging state, the control logic unit activates the charging control circuit, cooperatively adjusts the duty cycle of the Buck-Boost circuit through the bus voltage loop and the battery voltage loop, prevents overvoltage and realizes hardware shutdown; when it is detected that the battery needs to be discharged, the control logic unit automatically switches to the discharging control circuit, and starts the battery discharging control loop to adjust the voltage output to the load end. The two circuits are physically isolated by the control logic unit to avoid mutual interference of the charging and discharging operations. For example, the charging mode is enabled when the energy storage system stores energy at night, and the discharging mode is switched to when it supplies power during the day, and the whole process does not need manual intervention.

[0084] Compared with the prior art, the traditional control device usually adopts independent circuits to process charging and discharging respectively, but lacks a unified logic control unit, which is easy to cause overcharging or abnormal discharging of the battery due to mode switching delay. The existing scheme relies on software shutdown after the battery is fully charged, which has a risk of leakage current, while the present scheme directly cuts off the hardware circuit through the control logic unit, and integrates the discharging control loop to ensure the stability of the load power supply.

[0085] By the technical solution, the control lag problem during the switching of the charging and discharging modes is solved, the battery overvoltage damage is effectively prevented, the hardware shutdown for physical isolation is realized after the battery is fully charged, and the continuous charging caused by the leakage current is avoided. Meanwhile, the independent operation and the centralized control of the charging and discharging circuit take into account the system stability and the operation safety, and the service life of the battery is prolonged.

[0086] Reference Figure 4 and Figure 5 , Figure 4 For the embodiment provided by the application, when the battery current is greater than a certain value, the Buck tube and the Boost tube are complementary output, and a schematic diagram of a Buck-Boost drive waveform is shown in FIG. 1. Figure 5 For the embodiment provided by the application, when the battery current is less than a certain value, the Boost tube is withdrawn, and only the Buck tube is driven, and a schematic diagram of a Buck-Boost drive waveform is shown in FIG. 2. When the battery current is greater than a certain value, the Buck tube and the Boost tube are complementary output, and the Buck-Boost drive waveform is as shown in FIG. 1. When the battery current is less than a certain value, the Boost tube is withdrawn, and only the Buck tube is driven, and the Buck-Boost drive waveform is as shown in FIG. 2. When the battery is fully charged, the duty cycle of the battery charging control loop is adjusted to zero, and the Buck tube is also closed. At this time, all the tubes of the Buck-Boost are closed, and the hardware shutdown is completed, so that the battery can be completely disconnected, and the safety and reliability of the battery are ensured. When the load changes, the battery needs to be discharged, and the battery calls the discharging loop, as shown in FIG. 3, and the battery starts to discharge to the load. Figure 4 Figure 5 Figure 3

[0087] It can be understood that Figure 4 The complementary drive waveforms of the Buck tube and the Boost tube during the battery charging process are shown in FIG. 1. When the battery current is large, the drive waveforms of the Buck tube and the Boost tube are complementary, that is, when the Buck tube is turned on, the Boost tube is turned off, and vice versa. This complementary output mode ensures the continuous energy storage and release of the inductor, and improves the charging efficiency. Figure 5 FIG. 2 shows that when the battery current decreases to a certain value, the drive waveform of the Boost tube stops output (the Boost tube is withdrawn), and at this time only the drive waveform of the Buck tube is working. This mode switching helps to reduce the system loss in the small current charging stage, and improves the stability and safety of the charging.

[0088] ​​​The above merely provides an example of the present application, and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A charging control circuit for an energy storage inverter battery, characterized in that, include: The bus voltage loop has its input terminals connected to the bus voltage reference signal and the bus voltage feedback signal. The battery voltage loop has its input terminals connected to the battery voltage reference signal and the battery voltage feedback signal. The inner loop current setting module has its output terminal connected to an inverter and the output terminal of the battery voltage loop connected to the input terminal of a minimum value selector. The output terminal of the minimum value selector is connected to the input terminal of the inner loop current setting module. The inner loop current setting module is used to compare the current setting signal output by the minimum value selector with the battery current feedback signal, and outputs a duty cycle signal after adjustment by a PI controller. The duty cycle signal is used to control the on and off time ratio of the switching transistor in the BuckBoost circuit corresponding to the energy storage inverter battery. The bus voltage loop includes a bus voltage comparator, which compares the bus voltage reference signal and the bus voltage feedback signal, and outputs a bus voltage error signal to the inverter; the battery voltage loop includes a battery voltage comparator, which compares the battery voltage reference signal and the battery voltage feedback signal, outputs a battery voltage error signal, and connects to the input of the minimum value selector after being connected to the non-inverting inverter. The inner loop current setting module includes: A current comparator is used to compare the current setpoint signal output by the minimum value selector with the battery current feedback signal and output a current error signal. The PI controller, with its input terminal connected to the output terminal of the current comparator, is used to perform proportional-integral control on the current error signal and output the duty cycle signal.

2. The charging control circuit for the energy storage inverter battery according to claim 1, characterized in that, The charging control circuit of the energy storage inverter battery also includes a current sampling terminal, which is connected to the inner loop current setting module. The current sampling terminal is used to collect the battery current feedback signal and rectify the signal when the current is less than the preset current value, retaining only the positive value.

3. The charging control circuit for the energy storage inverter battery according to claim 1, characterized in that, The charging control circuit of the energy storage inverter battery also includes a drive waveform control module, which is connected to the output of the PI controller and is used to control the drive waveform of the switching transistor in the BuckBoost circuit according to the duty cycle signal. When the battery current is greater than the current threshold, the Buck transistor and Boost transistor are controlled to output complementary outputs. When the battery current is less than the current threshold, the Boost transistor is deactivated, and only the Buck transistor operates.

4. The charging control circuit for the energy storage inverter battery according to claim 3, characterized in that, The step of controlling the drive waveform of the switching transistor in the BuckBoost circuit according to the duty cycle signal further includes: Once the battery current indicates that the energy storage inverter battery is fully charged, the duty cycle is adjusted to turn off all BuckBoost switches, completing the hardware shutdown.

5. A charging control method for an energy storage inverter battery having the charging control circuit according to any one of claims 1 to 4, characterized in that, include: The error between the bus voltage reference signal and the bus voltage feedback signal is obtained through the bus voltage loop; The error between the battery voltage reference signal and the battery voltage feedback signal is obtained through the battery voltage loop; After inverting the output signal of the bus voltage loop, the minimum value of the output signal of the battery voltage loop is used to obtain the current command signal. The current command signal is compared with the battery current feedback signal, and the duty cycle signal is adjusted by the PI controller. The duty cycle signal controls the on and off time ratio of the switching transistors in the BuckBoost circuit corresponding to the energy storage inverter battery.

6. A control device for an energy storage inverter battery, characterized in that, include: The charging control circuit according to any one of claims 1 to 4; A discharge control circuit, comprising a battery discharge control loop, for controlling the battery to discharge to the load when the battery needs to discharge.

7. The control device for the energy storage inverter battery according to claim 6, characterized in that, It also includes a control logic unit for invoking the charging control circuit when the battery is charging and the discharging control circuit when the battery is discharging.

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