An inverter control circuit and method for improving dynamic response of a battery-free photovoltaic system

Abstract

The application relates to the technical field of photovoltaic power generation, and discloses an inverter control circuit and method for improving the dynamic response of a battery-free photovoltaic system, which significantly improves the machine transient load capacity and MPPT scanning speed through inverter self-control loop optimization; wherein, a bus lower limit control loop is quickly activated when the DC bus voltage drops, and outputs a negative adjustment amount to reduce the photovoltaic voltage given value, effectively inhibits the instantaneous bus voltage drop, cooperates with the voltage upper limit protection of the bus upper limit control loop, enhances the instantaneous load switching capacity of the photovoltaic inverter in the battery-free mode, and ensures that the load can be reliably started and stably operated; meanwhile, an MPPT scanning given generation module starts scanning from 0.8 times the open-circuit voltage of a photovoltaic component, greatly shortens the maximum power point optimization time, combines the power active clamping function of the power limit control loop, optimizes the MPPT scanning and tracking speed, and improves the overall energy capture efficiency and operation robustness.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic power generation technology, and in particular to an inverter control circuit and method for improving the dynamic response of a battery-free photovoltaic system. Background Technology

[0002] In photovoltaic systems, when a load is suddenly connected and generates a huge instantaneous power demand, the energy storage battery usually undertakes the task of providing instantaneous power buffering to ensure the stable operation of the system.

[0003] However, for battery-free photovoltaic systems, since the inverter is directly powered by the photovoltaic panels, the system faces the problem of insufficient instantaneous load-carrying capacity. Specifically, the control loop of traditional inverters mainly relies on the Maximum Power Point Tracking (MPPT) algorithm, which optimizes power through periodic scanning and adjustment, but its response speed is relatively slow. Due to the nonlinear output characteristics of the photovoltaic array and the inherent working mechanism of the conventional MPPT algorithm, the system struggles to provide the power required by the load instantaneously, resulting in a momentary drop in the inverter's DC bus voltage. This phenomenon easily triggers the undervoltage protection mechanism, causing the inverter to shut down unplanned, ultimately resulting in the inability to successfully drive the load or system startup failure.

[0004] Therefore, improvements to existing technologies are necessary.

[0005] The above information is provided as background information only to aid in understanding the present invention, and does not constitute an assertion or admission that any of the above content can be used as prior art relative to the present invention. Summary of the Invention

[0006] This invention provides an inverter control circuit and method for improving the dynamic response of a battery-free photovoltaic system, thereby solving the problems existing in the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] In a first aspect, the present invention provides an inverter control circuit for improving the dynamic response of a battery-free photovoltaic system, including a bus lower limit control loop, a bus upper limit control loop, an MPPT scan setpoint generation module, a power limiting control loop, and a voltage and current dual closed-loop control module.

[0009] The bus lower limit control loop is activated when the instantaneous value of the DC bus voltage, which is fed back in real time, drops to the preset bus voltage lower limit threshold, and outputs a negative adjustment amount to reduce the photovoltaic voltage setpoint.

[0010] The bus upper limit control loop is activated when the instantaneous value of the DC bus voltage, which is fed back in real time, rises to the preset upper limit threshold of the bus voltage, and outputs a positive adjustment amount to increase the photovoltaic voltage setpoint.

[0011] The MPPT scan given generation module is used to output a photovoltaic voltage given value based on the MPPT algorithm, and to start scanning from 0.8 times the open circuit voltage of the photovoltaic module when the system starts up or when MPPT is re-scanned.

[0012] The power limiting control loop is activated when the photovoltaic output power exceeds a preset maximum allowable power threshold, and outputs a positive adjustment amount to increase the photovoltaic voltage setpoint.

[0013] The voltage and current dual closed-loop control module is connected to the lower limit control loop of the bus, the upper limit control loop of the bus, the MPPT scan setpoint generation module and the power limiting control loop respectively, including an outer voltage loop and an inner current loop;

[0014] The outer voltage loop is used to output the given signal of the inner current loop based on the combined photovoltaic voltage given value obtained by superimposing the outputs of the lower limit control loop, the upper limit control loop, the MPPT scan given value generation module and the power limit control loop, as well as the real-time feedback of the instantaneous photovoltaic voltage value.

[0015] The inner current loop is used to adjust the PWM duty cycle based on the given signal and the instantaneous value of the photovoltaic current in real time.

[0016] Furthermore, in the inverter control circuit for improving the dynamic response of the batteryless photovoltaic system, the bus lower limit control loop receives the instantaneous value of the DC bus voltage in real time and the preset bus voltage lower limit threshold. When the instantaneous value of the DC bus voltage in real time drops to the preset bus voltage lower limit threshold, the error signal calculated based on the two is input to the PI controller of the bus lower limit control loop, and a negative adjustment amount is output to reduce the photovoltaic voltage setpoint.

[0017] Furthermore, in the inverter control circuit for improving the dynamic response of the batteryless photovoltaic system, the bus upper limit control loop receives the real-time feedback of the instantaneous value of the DC bus voltage and the preset bus voltage upper limit threshold. When the real-time feedback of the instantaneous value of the DC bus voltage drops to the preset bus voltage upper limit threshold, the error signal calculated based on the two is input to the PI controller of the bus upper limit control loop, and a positive adjustment amount is output to increase the photovoltaic voltage setpoint.

[0018] Furthermore, in the inverter control circuit for improving the dynamic response of the batteryless photovoltaic system, the power limiting control loop receives the photovoltaic output power and a preset maximum allowable power threshold. When the photovoltaic output power exceeds the preset maximum allowable power threshold, the error signal calculated based on the two is input to the PI controller of the power limiting control loop, and a positive adjustment amount is output to increase the photovoltaic voltage setpoint.

[0019] Furthermore, in the inverter control circuit for improving the dynamic response of the batteryless photovoltaic system, the outer voltage loop receives the comprehensive given value of the photovoltaic voltage and the instantaneous value of the photovoltaic voltage in real time, and inputs the error signal calculated based on the two into the PI controller of the outer voltage loop, and outputs the given signal of the inner current loop.

[0020] Furthermore, in the inverter control circuit for improving the dynamic response of the batteryless photovoltaic system, the inner current loop receives the given signal and the real-time feedback instantaneous value of the photovoltaic current, and inputs the error signal calculated based on the two into the PI controller of the inner current loop to adjust the PWM duty cycle.

[0021] Furthermore, in the inverter control circuit that improves the dynamic response of the batteryless photovoltaic system, when the batteryless photovoltaic system is instantly connected to the load and the photovoltaic output power is insufficient, the instantaneous value of the DC bus voltage fed back in real time drops to the preset lower limit threshold of the bus voltage.

[0022] When the load of the batteryless photovoltaic system is momentarily cut off or the photovoltaic output power is excessive, the instantaneous value of the DC bus voltage fed back in real time rises to the preset upper limit threshold of the bus voltage.

[0023] In a second aspect, the present invention provides an inverter control method for improving the dynamic response of a battery-free photovoltaic system, based on the inverter control loop provided in the first aspect above, comprising:

[0024] S1. Construct a bus lower limit control loop, which is activated when the instantaneous value of the DC bus voltage, which is fed back in real time, drops to the preset bus voltage lower limit threshold, and outputs a negative adjustment amount to reduce the photovoltaic voltage setpoint.

[0025] S2. Construct a bus upper limit control loop, which is activated when the instantaneous value of the DC bus voltage fed back in real time rises to the preset upper limit threshold of the bus voltage, and outputs a positive adjustment amount to increase the photovoltaic voltage setpoint.

[0026] S3. Build an MPPT scan given value generation module, based on the MPPT algorithm, output photovoltaic voltage given value, and start scanning from 0.8 times the open circuit voltage of the photovoltaic module when the system starts up or MPPT is re-scanned.

[0027] S4. Construct a power limiting control loop, which is activated when the photovoltaic output power exceeds the preset maximum allowable power threshold, and outputs a positive adjustment amount to increase the photovoltaic voltage setpoint.

[0028] S5. Construct a voltage and current dual closed-loop control module. Based on the comprehensive given value of photovoltaic voltage and the real-time feedback of instantaneous photovoltaic voltage, the voltage outer loop outputs the given signal of the current inner loop. The current inner loop, combined with the real-time feedback of instantaneous photovoltaic voltage, adjusts the PWM duty cycle.

[0029] Thirdly, the present invention provides a computer device including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the inverter control method for improving the dynamic response of a battery-free photovoltaic system as provided in the second aspect above.

[0030] Fourthly, the present invention provides a computer-readable storage medium having computer-executable instructions stored thereon, the computer-executable instructions being executed by a computer processor to implement the inverter control method for improving the dynamic response of a battery-free photovoltaic system as provided in the second aspect above.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] This invention provides an inverter control circuit and method for improving the dynamic response of battery-free photovoltaic systems. Through optimization of the inverter's own control loop alone, it significantly improves the machine's transient load-carrying capacity and MPPT scanning speed. Specifically, the lower bus limit control loop is rapidly activated when the DC bus voltage drops, outputting a negative adjustment to reduce the photovoltaic voltage setpoint, effectively suppressing instantaneous bus voltage drops. Combined with the voltage upper limit protection of the upper bus control loop, this enhances the photovoltaic inverter's instantaneous load switching capability in battery-free mode, ensuring reliable load startup and stable operation. Simultaneously, the MPPT scanning setpoint generation module starts scanning from 0.8 times the open-circuit voltage of the photovoltaic modules, significantly shortening the maximum power point optimization time. Combined with the power limit control loop's active power clamping function, this optimizes the MPPT scanning and tracking speed, improving overall energy capture efficiency and operational robustness.

[0033] The present invention has other features and advantages, which will be apparent from or will be set forth in detail in the accompanying drawings and the following detailed description, which together serve to explain the particular principles of the invention. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the functional modules of an inverter control circuit for improving the dynamic response of a battery-free photovoltaic system, provided in Embodiment 1 of the present invention.

[0036] Figure 2 This is a schematic diagram of a control loop (partial) of an inverter control circuit for improving the dynamic response of a battery-free photovoltaic system, provided in Embodiment 1 of the present invention.

[0037] Figure 3 This is a schematic diagram of another part of the control loop of an inverter control circuit for improving the dynamic response of a battery-free photovoltaic system, provided in Embodiment 1 of the present invention;

[0038] Figure 4 This is a flowchart illustrating an inverter control method for improving the dynamic response of a battery-free photovoltaic system, provided in Embodiment 2 of the present invention.

[0039] Figure 5 This is a schematic diagram of the structure of a computer device provided in Embodiment 3 of the present invention.

[0040] Figure label:

[0041] Bus lower limit control loop 1, bus upper limit control loop 2, MPPT scan setpoint generation module 3, power limit control loop 4, voltage and current dual closed loop control module 5;

[0042] Voltage outer loop 51, current inner loop 52. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] Example 1

[0045] Please refer to Figure 1 This invention provides an inverter control circuit for improving the dynamic response of a battery-free photovoltaic system, including a bus lower limit control loop 1, a bus upper limit control loop 2, an MPPT scan setpoint generation module 3, a power limit control loop 4, and a voltage and current dual closed-loop control module 5.

[0046] The bus lower limit control loop 1 is activated when the instantaneous value of the DC bus voltage fed back in real time drops to the preset bus voltage lower limit threshold, and outputs a negative adjustment amount to reduce the photovoltaic voltage setpoint, so as to move the photovoltaic operating point towards the high current direction and thus quickly improve the output power.

[0047] The bus upper limit control loop 2 is activated when the instantaneous value of the DC bus voltage fed back in real time rises to the preset upper limit threshold of the bus voltage, and outputs a positive adjustment amount to increase the photovoltaic voltage setpoint, so as to move the photovoltaic operating point towards the low current direction and thus suppress overvoltage.

[0048] The MPPT scan given generation module 3 is used to output the photovoltaic voltage given value based on the MPPT algorithm. When the system starts up or MPPT is re-scanned, the scan starts from 0.8 times the open circuit voltage of the photovoltaic module to approach the typical maximum power point voltage, thereby shortening the convergence time.

[0049] The power limiting control loop 4 is activated when the photovoltaic output power exceeds the preset maximum allowable power threshold, and outputs a positive adjustment amount to increase the photovoltaic voltage setpoint and reduce the photovoltaic output power, thereby ensuring that the system operates within a safe range.

[0050] The voltage and current dual closed-loop control module 5 is connected to the bus lower limit control loop 1, the bus upper limit control loop 2, the MPPT scan setpoint generation module 3 and the power limit control loop 4 respectively, and includes a voltage outer loop 51 and a current inner loop 52.

[0051] The voltage outer loop 51 is used to output the given signal of the current inner loop 52 based on the photovoltaic voltage comprehensive given value obtained by superimposing the outputs of the bus lower limit control loop 1, the bus upper limit control loop 2, the MPPT scan given value generation module 3 and the power limit control loop 4, and the real-time feedback photovoltaic voltage instantaneous value.

[0052] The inner current loop 52 is used to adjust the PWM duty cycle based on the given signal and the instantaneous value of the photovoltaic current in real time, so as to finally realize high dynamic and high precision power transmission of photovoltaic energy to the DC bus.

[0053] The inverter control circuit proposed in this invention achieves significant performance improvements simply by optimizing the inverter's own control loop. Specifically, this is reflected in the following aspects: First, it significantly improves the machine's transient load-carrying capacity and MPPT scanning speed. Specifically, the lower bus limit control loop 1 can quickly activate when the DC bus voltage drops, and promptly output a negative adjustment to reduce the photovoltaic voltage setpoint. This rapid response mechanism effectively suppresses the instantaneous drop in bus voltage. Simultaneously, in conjunction with the voltage upper limit protection function of the upper bus limit control loop 2, the two work together to greatly enhance the photovoltaic inverter's instantaneous load switching capability in battery-free mode. This ensures reliable load startup and stable operation when facing sudden load switching, avoiding system instability caused by load changes. Second, the innovative design of the MPPT scanning setpoint generation module 3, which starts scanning from 0.8 times the open-circuit voltage of the photovoltaic module, significantly shortens the maximum power point optimization time and improves the efficiency of MPPT scanning. By combining the active power clamping function of the power limiting control loop 4 with the precise adjustment capability of the voltage and current dual closed-loop control module, the MPPT scanning and tracking speed has been comprehensively optimized. This not only improves the overall energy capture efficiency, enabling the photovoltaic system to make fuller use of solar energy resources, but also enhances the robustness of system operation, effectively avoiding problems such as false triggering of undervoltage protection and unplanned shutdowns caused by bus voltage drops. Ultimately, it ensures stable operation and reliable startup of the system under load surges, providing a reliable technical guarantee for the practical application of battery-free photovoltaic systems.

[0054] In one embodiment of this example, different control mechanisms are used to address the operating characteristics of the battery-free photovoltaic system under different load variations.

[0055] When a battery-less photovoltaic (PV) system faces a sudden increase in load, and the PV output power cannot meet the load demand (i.e., a power shortage), the DC bus voltage within the system will be significantly affected. Due to the sudden increase in load and the failure of the PV power generation to match in time, an imbalance between energy supply and demand occurs on the DC bus, causing the instantaneous value of the real-time feedback DC bus voltage to drop rapidly. When this instantaneous voltage value drops to a pre-set lower limit threshold, a series of targeted control actions are triggered. The lower limit control loop 1 immediately activates, outputting a negative adjustment value according to its preset control logic. This negative adjustment value acts on the PV system, effectively reducing the PV voltage setpoint. As the PV voltage setpoint decreases, the PV operating point shifts towards higher current, causing the PV system output power to increase rapidly, compensating for the power gap caused by the load increase, striving to maintain the stability of the DC bus voltage, and ensuring the normal operation of the system.

[0056] Conversely, when the load of a battery-free photovoltaic system is momentarily disconnected, or when the photovoltaic output power is excessive (i.e., the photovoltaic power generation exceeds the actual load demand), energy gradually accumulates on the DC bus, causing the instantaneous value of the real-time feedback DC bus voltage to rise continuously. When this instantaneous voltage rises to the preset upper limit threshold of the bus voltage, the system responds quickly. The upper limit control loop 2 is activated, outputting a positive regulation value according to its predetermined control strategy. This positive regulation value acts on the photovoltaic system, increasing the photovoltaic voltage setpoint. As the photovoltaic voltage setpoint increases, the photovoltaic operating point shifts towards lower current, thereby suppressing the output power of the photovoltaic system, preventing the DC bus voltage from continuously rising due to excess energy, avoiding overvoltage damage to system equipment, and ensuring stable operation of the system within a safe voltage range.

[0057] Through the precise monitoring of DC bus voltage under different operating conditions and the synergistic effect of bus lower limit control loop 1 and bus upper limit control loop 2, the embodiments of the present invention can effectively cope with various situations of batteryless photovoltaic systems under load changes and power fluctuations, ensure the stability and reliability of the system, and improve the utilization efficiency of photovoltaic energy.

[0058] Please refer to Figure 2 In one embodiment of this example, the bus lower limit control loop 1 receives the instantaneous value of the DC bus voltage in real time and a preset bus voltage lower limit threshold. When the instantaneous value of the DC bus voltage in real time drops to the preset bus voltage lower limit threshold, the error signal calculated based on the two is input to the PI controller of the bus lower limit control loop 1, and a negative adjustment amount is output to reduce the photovoltaic voltage setpoint.

[0059] The PI controller, as a classic and effective control algorithm module, features proportional-integral (PI) regulation. It can perform complex calculations based on the input error signal, according to preset proportional and integral coefficients. Through proportional regulation, the PI controller can quickly respond to the error signal, generating an initial adjustment proportional to the error magnitude; while integral regulation allows for cumulative error analysis, eliminating steady-state errors and further improving control accuracy and stability.

[0060] After precise calculations by the PI controller, a negative regulation value is output. This negative regulation value acts on the photovoltaic system, effectively reducing the photovoltaic voltage setpoint. As the photovoltaic voltage setpoint decreases, the photovoltaic operating point shifts towards higher current, causing the photovoltaic system's output power to increase rapidly. This compensates for the power gap caused by load input, strives to maintain the stability of the DC bus voltage, and ensures that the battery-free photovoltaic system can still operate stably and reliably under complex and changing operating conditions.

[0061] Please refer to this again. Figure 2 In one embodiment of this example, the bus upper limit control loop 2 receives the instantaneous value of the DC bus voltage in real time and the preset upper limit threshold of the bus voltage. When the instantaneous value of the DC bus voltage in real time drops to the preset upper limit threshold of the bus voltage, the error signal calculated based on the two is input to the PI controller of the bus upper limit control loop 2, and a positive adjustment amount is output to increase the photovoltaic voltage setpoint.

[0062] After calculation by the PI controller, the final output positive regulation is applied to the photovoltaic system, effectively increasing the photovoltaic voltage setpoint. As the photovoltaic voltage setpoint increases, the photovoltaic operating point shifts towards lower current, thereby suppressing the output power of the photovoltaic system, preventing the DC bus voltage from continuously rising due to excess energy, avoiding overvoltage damage to system equipment, and ensuring stable and safe operation of the battery-free photovoltaic system under various complex operating conditions.

[0063] Please refer to this again. Figure 2 In one embodiment of this example, the power limiting control loop 4 receives the photovoltaic output power and a preset maximum allowable power threshold. When the photovoltaic output power exceeds the preset maximum allowable power threshold, the error signal calculated based on the two is input to the PI controller of the power limiting control loop 4, and a positive adjustment amount is output to increase the photovoltaic voltage setpoint.

[0064] After calculation by the PI controller, the final output positive regulation is applied to the photovoltaic system, effectively increasing the photovoltaic voltage setpoint. As the photovoltaic voltage setpoint increases, the photovoltaic operating point shifts towards lower current, thereby suppressing the output power of the photovoltaic system and gradually reducing it below the preset maximum allowable power threshold. This prevents power overload and ensures that the battery-free photovoltaic system can operate safely, stably, and efficiently in various complex environments.

[0065] Please refer to Figure 3 In one embodiment of this example, the outer voltage loop 51 receives the comprehensive given value of the photovoltaic voltage and the instantaneous value of the photovoltaic voltage in real time, and inputs the error signal calculated based on the two into the PI controller of the outer voltage loop 51, and outputs the given signal of the inner current loop 52.

[0066] After calculation by the PI controller, the outer voltage loop 51 outputs a given signal for the inner current loop 52. This given signal is transmitted to the inner current loop 52, providing a clear target for its further regulation. Based on this given signal and the real-time feedback of the instantaneous current value, the inner current loop 52 performs its own current regulation control, thereby achieving precise control of the photovoltaic system current. This ultimately ensures the stability of the photovoltaic system's output voltage, enabling the battery-free photovoltaic system to operate stably and reliably under various complex and changing operating conditions.

[0067] Please refer to this again. Figure 3 In one embodiment of this example, the inner current loop 52 receives the given signal and the real-time feedback instantaneous value of the photovoltaic current, and inputs the error signal calculated based on the two into the PI controller of the inner current loop 52 to adjust the PWM duty cycle.

[0068] After calculation by the PI controller, the inner current loop 52 ultimately outputs a control signal for adjusting the PWM duty cycle. The PWM (Pulse Width Modulation) duty cycle is a key parameter for controlling the switching state of power electronic devices. By adjusting the PWM duty cycle, the on and off times of the power switches in the photovoltaic system can be precisely controlled, thereby achieving precise regulation of the photovoltaic current. For example, when the error signal indicates that the actual photovoltaic current is less than the desired target current, the inner current loop 52 will output a control signal to increase the PWM duty cycle, making the power switch's on-time longer, thus increasing the output current of the photovoltaic system. Conversely, when the actual photovoltaic current is greater than the desired target current, it will output a control signal to decrease the PWM duty cycle, making the power switch's on-time shorter, thus reducing the output current of the photovoltaic system.

[0069] By precisely adjusting the PWM duty cycle through the inner current loop 52, it is possible to ensure that the photovoltaic current closely follows the given signal output by the outer voltage loop 51, thereby achieving stable control of the photovoltaic system current. In turn, together with the outer voltage loop 51, it ensures the stability of the output voltage and current of the battery-free photovoltaic system, enabling the system to operate efficiently and reliably under various complex operating conditions.

[0070] Although this invention frequently uses terms such as bus lower limit control loop and MPPT scan setpoint generation module, the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of this invention; interpreting them as any additional limitation would contradict the spirit of this invention.

[0071] Example 2

[0072] Please refer to Figure 4This is a flowchart illustrating an inverter control method for improving the dynamic response of a battery-free photovoltaic system according to Embodiment 2 of the present invention. This method is based on the inverter control loop provided in Embodiment 1 above. The method specifically includes the following steps:

[0073] S1. Construct a bus lower limit control loop, which is activated when the instantaneous value of the DC bus voltage, which is fed back in real time, drops to the preset bus voltage lower limit threshold, and outputs a negative adjustment amount to reduce the photovoltaic voltage setpoint.

[0074] S2. Construct a bus upper limit control loop, which is activated when the instantaneous value of the DC bus voltage fed back in real time rises to the preset upper limit threshold of the bus voltage, and outputs a positive adjustment amount to increase the photovoltaic voltage setpoint.

[0075] S3. Build an MPPT scan given value generation module, based on the MPPT algorithm, output photovoltaic voltage given value, and start scanning from 0.8 times the open circuit voltage of the photovoltaic module when the system starts up or MPPT is re-scanned.

[0076] S4. Construct a power limiting control loop, which is activated when the photovoltaic output power exceeds the preset maximum allowable power threshold, and outputs a positive adjustment amount to increase the photovoltaic voltage setpoint.

[0077] S5. Construct a voltage and current dual closed-loop control module. Based on the comprehensive given value of photovoltaic voltage and the real-time feedback of instantaneous photovoltaic voltage, the voltage outer loop outputs the given signal of the current inner loop. The current inner loop, combined with the real-time feedback of instantaneous photovoltaic voltage, adjusts the PWM duty cycle.

[0078] Through the coordinated operation of the above steps, the inverter control method provided in Embodiment 2 of the present invention can effectively improve the dynamic response capability of the battery-free photovoltaic system and ensure the stable, safe and efficient operation of the system under various operating conditions.

[0079] Example 3

[0080] Figure 5 This is a schematic diagram of the structure of a computer device provided in Embodiment 3 of the present invention. Figure 5 A block diagram of an exemplary computer device 12 suitable for implementing embodiments of the present invention is shown. Figure 5 The computer device 12 shown is merely an example and should not impose any limitation on the functionality and scope of use of the embodiments of the present invention.

[0081] like Figure 5 As shown, the computer device 12 is represented in the form of a general-purpose computing device. The components of the computer device 12 may include, but are not limited to: one or more processors or processing units 16, system memory 28, and bus 18 connecting different system components (including system memory 28 and processing unit 16).

[0082] Bus 18 represents one or more of several bus architectures, including a memory bus or memory controller, a peripheral bus, a graphics acceleration port, a processor, or a local bus using any of the various bus architectures. For example, these architectures include, but are not limited to, the Industry Standard Architecture (ISA) bus, the Micro Channel Architecture (MAC) bus, the Enhanced ISA bus, the Video Electronics Standards Association (VESA) local bus, and the Peripheral Component Interconnect (PCI) bus.

[0083] Computer device 12 typically includes a variety of computer system readable media. These media can be any available media that can be accessed by computer device 12, including volatile and non-volatile media, removable and non-removable media.

[0084] System memory 28 may include computer system readable media in the form of volatile memory, such as random access memory (RAM) 30 and / or cache memory 32. Computer device 12 may further include other removable / non-removable, volatile / non-volatile computer system storage media. By way of example only, storage system 34 may be used to read and write non-removable, non-volatile magnetic media (…). Figure 5 Not shown; usually referred to as a "hard drive"). Although Figure 5 Not shown, a disk drive for reading and writing to a removable non-volatile disk (e.g., a "floppy disk") and an optical disk drive for reading and writing to a removable non-volatile optical disk (e.g., a CD-ROM, DVD-ROM, or other optical media) may be provided. In these cases, each drive may be connected to bus 18 via one or more data media interfaces. Memory 28 may include at least one program product having a set (e.g., at least one) of program modules configured to perform the functions of the embodiments of the present invention.

[0085] A program / utility 40 having a set (at least one) of program modules 42 may be stored, for example, in memory 28. Such program modules 42 include, but are not limited to, an operating system, one or more application programs, other program modules, and program data. Each or some combination of these examples may include an implementation of a network environment. Program modules 42 typically perform the functions and / or methods described in the embodiments of the present invention.

[0086] Computer device 12 can also communicate with one or more external devices 14 (e.g., keyboard, pointing device, display 24, etc.), and with one or more devices that enable a user to interact with the computer device 12, and / or with any device that enables the computer device 12 to communicate with one or more other computing devices (e.g., network card, modem, etc.). This communication can be performed via input / output (I / O) interface 22. Furthermore, computer device 12 can also communicate with one or more networks (e.g., local area network (LAN), wide area network (WAN), and / or public networks, such as the Internet) via network adapter 20. As shown, network adapter 20 communicates with other modules of computer device 12 via bus 18. It should be understood that, although... Figure 5 As not shown, it can be used in conjunction with computer device 12 with other hardware and / or software modules, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage systems.

[0087] The processing unit 16 executes various functional applications and data processing by running programs stored in the system memory 28, such as implementing the inverter control method for improving the dynamic response of battery-free photovoltaic systems provided in the embodiments of the present invention.

[0088] Example 4

[0089] Embodiment 4 of the present invention provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the inverter control method for improving the dynamic response of a battery-free photovoltaic system as provided in all embodiments of the present invention.

[0090] Any combination of one or more computer-readable media may be used. A computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. A computer-readable storage medium can be, for example—but not limited to—an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples (a non-exhaustive list) of computer-readable storage media include: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this document, a computer-readable storage medium can be any tangible medium that contains or stores a program that can be used by or in connection with an instruction execution system, apparatus, or device.

[0091] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. Computer-readable signal media may also be any computer-readable medium other than computer-readable storage media, capable of sending, propagating, or transmitting programs for use by or in connection with an instruction execution system, apparatus, or device.

[0092] Program code contained on a computer-readable medium may be transmitted using any suitable medium, including—but not limited to—wireless, wire, optical fiber, RF, etc., or any suitable combination thereof.

[0093] Computer program code for performing the operations of this invention can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, as well as conventional procedural programming languages ​​such as "C" or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0094] Finally, it should be noted that although the above embodiments have been described in the description and drawings of this invention, this should not limit the scope of patent protection of this invention. Any technical solutions that are based on the essential concept of this invention, utilize the content described in the description and drawings of this invention to make equivalent structural or procedural substitutions or modifications, as well as the direct or indirect application of the technical solutions of the above embodiments to other related technical fields, are all included within the scope of patent protection of this invention.

Claims

1. An inverter control circuit for improving the dynamic response of a battery-free photovoltaic system, characterized in that, It includes a bus lower limit control loop (1), a bus upper limit control loop (2), an MPPT scan setpoint generation module (3), a power limit control loop (4), and a voltage and current dual closed-loop control module (5). The lower limit control loop (1) is activated when the instantaneous value of the DC bus voltage fed back in real time drops to the preset lower limit threshold of the bus voltage, and outputs a negative adjustment amount to reduce the photovoltaic voltage setpoint. The bus upper limit control loop (2) is activated when the instantaneous value of the DC bus voltage fed back in real time rises to the preset upper limit threshold of the bus voltage, and outputs a positive adjustment amount to increase the photovoltaic voltage setpoint. The MPPT scan given generation module (3) is used to output the photovoltaic voltage given value based on the MPPT algorithm, and to start scanning from 0.8 times the open circuit voltage of the photovoltaic module when the system starts up or MPPT is re-scanned. The power limiting control loop (4) is activated when the photovoltaic output power exceeds the preset maximum allowable power threshold, and outputs a positive adjustment amount to increase the photovoltaic voltage setpoint. The voltage and current dual closed-loop control module (5) is connected to the bus lower limit control loop (1), the bus upper limit control loop (2), the MPPT scan setpoint generation module (3) and the power limit control loop (4) respectively, including the voltage outer loop (51) and the current inner loop (52); The voltage outer loop (51) is used to output the given signal of the current inner loop (52) based on the combined photovoltaic voltage given value obtained by superimposing the outputs of the bus lower limit control loop (1), bus upper limit control loop (2), MPPT scan given value generation module (3) and power limit control loop (4), as well as the real-time feedback photovoltaic voltage instantaneous value. The inner current loop 52 is used to adjust the PWM duty cycle based on the given signal and the instantaneous value of the photovoltaic current in real time feedback.

2. The inverter control circuit for improving the dynamic response of a battery-free photovoltaic system according to claim 1, characterized in that, The bus lower limit control loop (1) receives the instantaneous value of DC bus voltage and the preset bus voltage lower limit threshold in real time. When the instantaneous value of DC bus voltage drops to the preset bus voltage lower limit threshold, the error signal calculated based on the two is input to the PI controller of the bus lower limit control loop (1) and outputs a negative adjustment amount to reduce the photovoltaic voltage setpoint.

3. The inverter control circuit for improving the dynamic response of a battery-free photovoltaic system according to claim 1, characterized in that, The bus upper limit control loop (2) receives the real-time feedback of the instantaneous value of the DC bus voltage and the preset bus voltage upper limit threshold. When the real-time feedback of the instantaneous value of the DC bus voltage drops to the preset bus voltage upper limit threshold, the error signal calculated based on the two is input to the PI controller of the bus upper limit control loop (2) and outputs a positive adjustment amount to increase the photovoltaic voltage setpoint.

4. The inverter control circuit for improving the dynamic response of a battery-free photovoltaic system according to claim 1, characterized in that, The power limiting control loop (4) receives the photovoltaic output power and the preset maximum allowable power threshold. When the photovoltaic output power exceeds the preset maximum allowable power threshold, the error signal calculated based on the two is input to the PI controller of the power limiting control loop (4) and outputs a positive adjustment amount to increase the photovoltaic voltage setpoint.

5. The inverter control circuit for improving the dynamic response of a battery-free photovoltaic system according to claim 1, characterized in that, The outer voltage loop (51) receives the comprehensive given value of photovoltaic voltage and the instantaneous value of photovoltaic voltage in real time, and inputs the error signal calculated based on the two into the PI controller of the outer voltage loop (51), and outputs the given signal of the inner current loop (52).

6. The inverter control circuit for improving the dynamic response of a battery-free photovoltaic system according to claim 1, characterized in that, The inner current loop 52 receives the given signal and the real-time feedback instantaneous value of the photovoltaic current, and inputs the error signal calculated based on the two into the PI controller of the inner current loop 52 to adjust the PWM duty cycle.

7. The inverter control circuit for improving the dynamic response of a battery-free photovoltaic system according to claim 1, characterized in that, When the batteryless photovoltaic system is instantly loaded and the photovoltaic output power is insufficient, the instantaneous value of the DC bus voltage fed back in real time drops to the preset lower limit threshold of the bus voltage. When the load of the batteryless photovoltaic system is momentarily cut off or the photovoltaic output power is excessive, the instantaneous value of the DC bus voltage fed back in real time rises to the preset upper limit threshold of the bus voltage.

8. An inverter control method for improving the dynamic response of a battery-free photovoltaic system, based on the inverter control loop as described in any one of claims 1-7, characterized in that, include: S1. Construct a bus lower limit control loop, which is activated when the instantaneous value of the DC bus voltage, which is fed back in real time, drops to the preset bus voltage lower limit threshold, and outputs a negative adjustment amount to reduce the photovoltaic voltage setpoint. S2. Construct a bus upper limit control loop, which is activated when the instantaneous value of the DC bus voltage fed back in real time rises to the preset upper limit threshold of the bus voltage, and outputs a positive adjustment amount to increase the photovoltaic voltage setpoint. S3. Build an MPPT scan given value generation module, based on the MPPT algorithm, output photovoltaic voltage given value, and start scanning from 0.8 times the open circuit voltage of the photovoltaic module when the system starts up or MPPT is re-scanned. S4. Construct a power limiting control loop, which is activated when the photovoltaic output power exceeds the preset maximum allowable power threshold, and outputs a positive adjustment amount to increase the photovoltaic voltage setpoint. S5. Construct a voltage and current dual closed-loop control module. Based on the comprehensive given value of photovoltaic voltage and the real-time feedback of instantaneous photovoltaic voltage, the voltage outer loop outputs the given signal of the current inner loop. The current inner loop, combined with the real-time feedback of instantaneous photovoltaic voltage, adjusts the PWM duty cycle.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the inverter control method for improving the dynamic response of a battery-free photovoltaic system as described in any one of claims 1-8.

10. A computer-readable storage medium having computer-executable instructions stored thereon, characterized in that, The computer-executable instructions are executed by a computer processor to implement the inverter control method for improving the dynamic response of a battery-free photovoltaic system as described in any one of claims 1-8.

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