CN117811083A

CN117811083A - Discharging control method of power supply circuit, power supply equipment and energy storage equipment

Info

Publication number: CN117811083A
Application number: CN202311868530.3A
Authority: CN
Inventors: 周茂强; 赵密; 陈熙; 王雷
Original assignee: Ecoflow Technology Ltd
Current assignee: Ecoflow Technology Ltd
Priority date: 2023-12-29
Filing date: 2023-12-29
Publication date: 2024-04-02

Abstract

The application provides a discharge control method of a power supply circuit, power supply equipment and energy storage equipment. The power supply circuit is arranged on the power supply system. The power supply system comprises a battery pack, a photovoltaic module, an inverter and a power supply circuit. The first end of the power supply circuit is used for being connected with the battery pack, and the second end of the power supply circuit, the output end of the photovoltaic module and the direct current input end of the inverter are all connected with the direct current bus. When the power supply circuit discharges, electric energy is obtained from the battery pack and is output to the direct current bus. The method comprises the following steps: obtaining photovoltaic parameters of a photovoltaic module, wherein the photovoltaic parameters comprise photovoltaic voltage; acquiring a discharge voltage of a power supply circuit; and moving the simulated discharge curve along with the photovoltaic voltage and the discharge voltage, and controlling the power supply circuit to discharge according to the moved simulated discharge curve. The discharging control method of the power supply circuit can improve the energy utilization rate of the photovoltaic module.

Description

Discharging control method of power supply circuit, power supply equipment and energy storage equipment

Technical Field

The application relates to the technical field of clean energy, in particular to a discharge control method of a power supply circuit, power supply equipment and energy storage equipment.

Background

In a photovoltaic power supply system with an energy storage device coupled to a direct current side, when the energy storage device discharges, the discharge power of the energy storage device and the generated power of a photovoltaic module are output to an input end of an inverter as total discharge power. Therefore, the discharge curve of the energy storage device may affect the maximum power tracking of the inverter, which in turn affects whether the photovoltaic module can operate at the maximum power point. In order to make the photovoltaic module work at the maximum power point, one of the discharging modes of the energy storage device constructs a power-voltage (PV) curve for the energy storage device to discharge in the form of a PV curve simulating the photovoltaic module, and the simulated PV curve needs to be matched with an actual PV curve of the photovoltaic module so as to maximize the energy utilization rate of the photovoltaic module under various working conditions, and in an ideal state, the maximum power point voltage of the simulated PV curve should overlap with the maximum power point voltage of the photovoltaic module.

However, even the same photovoltaic module has the PV curve that changes with the external environment, such as lighting conditions, ambient temperature, local shadow shielding, etc., which affect the open-circuit voltage and the maximum power point voltage of the photovoltaic module, and in practical application, the type and brand of the connected photovoltaic module may change, and the PV curve parameters of the photovoltaic module also change with different brands and different types. This means that the actual PV curve of the photovoltaic module will change frequently, and in actual operation, the energy storage device cannot obtain the actual PV curve of the photovoltaic module at any time, and the simulated PV curve of the energy storage device cannot perfectly follow the PV curve parameters of the photovoltaic module to make adjustment in real time, which will tend to reduce the energy utilization rate of the photovoltaic module.

Disclosure of Invention

In view of this, the application provides a discharge control method of a power supply circuit, a power supply device and an energy storage device, which can move a simulated discharge curve of a battery pack according to photovoltaic parameters of a photovoltaic module, thereby improving the utilization rate of the photovoltaic module.

A first aspect of the present application provides a discharge control method of a power supply circuit. The power supply circuit is arranged in a power supply system, and the power supply system comprises a battery pack, a photovoltaic module, an inverter and a power supply circuit. The first end of the power supply circuit is used for being connected with the battery pack, and the second end of the power supply circuit, the output end of the photovoltaic module and the direct current input end of the inverter are all connected to the direct current bus. When the power supply circuit discharges, electric energy is obtained from the battery pack and is output to the direct current bus. The method comprises the following steps: obtaining photovoltaic parameters of a photovoltaic module, wherein the photovoltaic parameters comprise photovoltaic voltage; acquiring a discharge voltage of a power supply circuit; and moving the simulated discharge curve along with the photovoltaic voltage and the discharge voltage, and controlling the power supply circuit to discharge according to the moved simulated discharge curve.

In an embodiment, the photovoltaic parameter further includes a power generation power of the photovoltaic module, moves the simulated discharge curve along with the photovoltaic voltage and the discharge voltage, and controls the power supply circuit to discharge according to the moved simulated discharge curve, including: when the photovoltaic voltage is larger than the first voltage threshold and the generated power is smaller than the first power threshold, the simulated discharge curve is moved along with the photovoltaic voltage and the discharge voltage, and the power supply circuit is controlled to discharge according to the moved simulated discharge curve.

In an embodiment, the method further comprises: when the photovoltaic voltage is smaller than or equal to a first voltage threshold, controlling the power supply circuit to discharge according to an initial discharge curve; the initial discharge curve is an initial simulated discharge curve, and the maximum power point and the open-circuit voltage of the initial discharge curve are set according to the target discharge power of the power supply circuit and MPPT scanning parameters of the inverter.

In an embodiment, the method further comprises: and when the photovoltaic voltage is larger than the first voltage threshold and the generated power is larger than or equal to the first power threshold, controlling the power supply circuit to discharge according to the target discharge power and the photovoltaic voltage.

In an embodiment, the MPPT scan parameters include a maximum scan voltage and a minimum scan voltage, and the method further includes, before controlling the power supply circuit to discharge according to the initial discharge curve: when the maximum scanning voltage is greater than or equal to the first scanning voltage, determining that the first voltage value is the open-circuit voltage of the initial discharge curve; when the maximum scanning voltage is smaller than the first scanning voltage, determining an open-circuit voltage of an initial discharge curve according to the maximum scanning voltage and the first voltage parameter; determining the maximum power point power of an initial discharge curve according to the target discharge power; determining the maximum power point voltage of the initial discharge curve according to the open circuit voltage and the second voltage parameter; and generating an initial discharge curve according to the open circuit voltage, the maximum power point power and the maximum power point voltage.

In an embodiment, when the photovoltaic voltage is greater than the first voltage threshold and the generated power is less than the first power threshold, the simulated discharge curve is moved along with the photovoltaic voltage and the discharge voltage, comprising: when the photovoltaic voltage is larger than a first voltage threshold value and the generated power is smaller than the first power threshold value, the open-circuit voltage of the simulated discharge curve is reduced according to a first preset step length to shift the simulated discharge curve to the left, and when the open-circuit voltage reaches the minimum open-circuit voltage of the power supply circuit or the open-circuit voltage is smaller than a dynamic voltage value, the left-shift simulated discharge curve is stopped, wherein the dynamic voltage value is dynamically set according to the discharge voltage.

In an embodiment, the dynamic voltage value is a sum of the discharge voltage and a first preset voltage value, and when the photovoltaic voltage is greater than the first voltage threshold and the generated power is less than the first power threshold, the method moves the simulated discharge curve along with the photovoltaic voltage and the discharge voltage, and further includes: stopping the left shift simulation discharge curve when the reduced open circuit voltage is smaller than the dynamic voltage value; and updating the open-circuit voltage of the simulated discharge curve according to the dynamic voltage value to shift the simulated discharge curve to the right.

In an embodiment, the method further comprises: when the photovoltaic voltage is changed from being greater than the first voltage threshold value to being less than or equal to the first voltage threshold value, updating the open-circuit voltage of the simulated discharge curve according to the second preset step length to move the simulated discharge curve until the moved simulated discharge curve is restored to the initial discharge curve.

A second aspect of the present application provides a power supply apparatus including a power supply circuit and a controller. The power supply equipment is arranged in the power supply system, the power supply system comprises a battery pack, a photovoltaic module, an inverter and power supply equipment, a first end of a power supply circuit is used for being connected with the battery pack, and a second end of the power supply circuit, an output end of the photovoltaic module and a direct current input end of the inverter are all connected to the direct current bus; when the power supply circuit discharges, electric energy is obtained from the battery pack and is output to the direct current bus; the controller is configured to execute the discharge control method of the power supply circuit according to any one of the above.

A third aspect of the present application provides an energy storage device comprising a power supply circuit, a battery pack, and a controller. The energy storage equipment is arranged in the power supply system, the power supply system comprises a battery pack, a photovoltaic module, an inverter and energy storage equipment, a first end of the power supply circuit is used for being connected with the battery pack, and a second end of the power supply circuit, an output end of the photovoltaic module and a direct current input end of the inverter are all connected to the direct current bus; when the power supply circuit discharges, electric energy is obtained from the battery pack and is output to the direct current bus; the controller is configured to execute the discharge control method of the power supply circuit according to any one of the above.

According to the discharge control method of the power supply circuit, photovoltaic voltage of the photovoltaic module and discharge voltage of the power supply circuit are obtained first, so that a simulated discharge curve is moved along with the photovoltaic voltage and the discharge voltage, and the power supply circuit is controlled to discharge according to the moved simulated discharge curve. The MPPT circuit is used for tracking the maximum power point of the MPPT circuit, and the MPPT circuit is used for tracking the maximum power point of the MPPT circuit. In this way, the power supply circuit is controlled to discharge according to the moved simulated discharge curve, and the energy utilization rate of the photovoltaic module can be improved while the target discharge power of the power supply circuit is met.

Drawings

It is appreciated that the following drawings depict only certain embodiments of the application and are therefore not to be considered limiting of its scope. Like elements are numbered alike in the various figures.

Fig. 1 is a circuit block diagram of a power supply system according to an embodiment of the present application.

Fig. 2 is a flow chart of a discharge control method of a power supply circuit according to an embodiment of the present application.

FIG. 3 is a flow chart illustrating the sub-steps for generating an initial discharge curve according to an embodiment of the present application.

Fig. 4 is a schematic diagram of a PV curve of a photovoltaic module in the related art.

Fig. 5 is a flowchart of the substeps of controlling the discharge of the power supply circuit according to the initial discharge curve according to an embodiment of the present application.

Fig. 6 is a schematic diagram of an initial discharge curve according to an embodiment of the present application.

FIG. 7 is a block flow diagram of a sub-step of simulating a discharge curve following a photovoltaic voltage and a discharge voltage movement according to an embodiment of the present application.

Fig. 8 is a schematic diagram of a first PV curve and a simulated discharge curve of a photovoltaic module in a low-light state.

Fig. 9 is a schematic diagram of a second PV curve and simulated discharge curve for a photovoltaic module in a low-light state.

Fig. 10 is a schematic diagram of a third PV curve and simulated discharge curve for a photovoltaic module in a low-light state.

FIG. 11 is a schematic diagram of the direction of movement of the simulated discharge curve when the photovoltaic voltage is changed from greater than the first voltage threshold to less than or equal to the first voltage threshold.

Fig. 12 is a schematic diagram of a discharge curve of the power supply circuit and a PV curve of the photovoltaic module when the photovoltaic module is in a strong illumination state.

Fig. 13 is a state switching schematic diagram of a state machine according to an embodiment of the present application.

Fig. 14 is a flowchart of determining a target discharge power according to an embodiment of the present application.

Fig. 15 is a control block diagram of a discharge control method of a power supply circuit according to an embodiment of the present application.

Fig. 16 is a circuit block diagram of a power supply system according to another embodiment of the present application.

Fig. 17 is a graph showing the power data and the voltage data related to the discharging of the first power supply circuit in fig. 16.

Fig. 18 is a block diagram of a power supply device according to an embodiment of the present application.

Fig. 19 is a block diagram of an energy storage device according to an embodiment of the present application.

Fig. 20 is a functional block diagram of a control device according to an embodiment of the present application.

Detailed Description

The following description of the technical solutions in the embodiments of the present application will be made with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are only some embodiments of the present application, but not all embodiments.

It is noted that when one component is considered to be "connected" to another component, it may be directly connected to the other component or intervening components may also be present. When an element is referred to as being "disposed" on another element, it can be directly on the other element or intervening elements may also be present. The terms "top," "bottom," "upper," "lower," "left," "right," "front," "rear," and the like are used herein for illustrative purposes only.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

Some embodiments will be described below with reference to the accompanying drawings. The following embodiments and features of the embodiments may be combined with each other without conflict.

Referring to fig. 1, fig. 1 is a schematic diagram of a power supply system 10 according to an embodiment of the present disclosure. The power supply system 10 includes a battery pack 110, a power supply circuit 120, a photovoltaic module 130, and an inverter 140. The first end of the power supply circuit 120 is configured to be connected to the battery pack 110, and the second end of the power supply circuit 120, the output end of the photovoltaic module 130, and the DC input end of the inverter 140 are all connected to DC buses (including a positive DC BUS dc_bus+ and a negative DC BUS dc_bus-). The output of inverter 140 is connected to grid 20 via an ac bus (including neutral N and hot L).

Further, one or more series and/or parallel cells are disposed within the battery pack 110. The battery pack 110 is used to store or release energy.

The power supply circuit 120 includes a direct current-to-direct current (Direct Current to Direct Current, DC/DC) conversion unit. The DC/DC conversion unit is configured to boost and buck the battery voltage of the battery pack 110 and then discharge the battery voltage through the DC bus, or boost and buck the charging voltage provided by the DC bus and then charge the battery pack 110. Specifically, when the power supply circuit 120 is charged, power is taken from the photovoltaic module 130 through the dc bus for power conversion, so as to charge the battery pack 110; the power supply circuit 120 receives power from the battery pack 110 and outputs the power to the dc bus when discharging.

It is understood that the DC/DC conversion unit may be composed of a BUCK circuit, a BOOST circuit, or a BUCK-BOOST circuit. Thus, by controlling the switching logic and the duty ratio of the BUCK circuit, the BOOST circuit or the BUCK-BOOST circuit, the DC/DC conversion unit can be controlled to operate in a charging mode or a discharging mode, and the output power of the DC/DC conversion unit can be controlled. In other embodiments, the DC/DC conversion unit may include a boost circuit and DAB (Dual Active Bridge, double active bridge) circuit, and may also include a boost circuit and LLC Series-parallel resonant (LLC Series-parallel resonant) circuit. The specific circuit structures of the boost circuit, the DAB circuit, and the LLC circuit are not limited herein.

The photovoltaic module 130 includes a number of photovoltaic panels. The photovoltaic panel outputs direct current to the inverter 140 by converting light energy into electrical energy and/or charges the battery pack 110 through the power supply circuit 120. It is understood that the present application is not limited to the manner in which the photovoltaic panels in the photovoltaic module 130 are connected. For example, in some embodiments, the photovoltaic panels in the photovoltaic module 130 may be connected in series, in parallel, or connected in series followed by parallel, etc.

The inverter 140 at least includes a direct current to alternating current (Direct Current to Alternating Current, DC/AC) conversion unit to convert the direct current of the photovoltaic module 130 and/or the power supply circuit 120, which is obtained from the direct bus, into alternating current at the direct input end, and output the alternating current to the alternating current bus to supply power to the load 30 and/or to the power grid 20. It is to be understood that the present application is not limited to a specific circuit configuration of the DC/AC converting unit, and for example, the DC/AC converting unit may be a full-bridge topology, a half-bridge topology, or the like. In some embodiments, due to the power generation characteristics of the photovoltaic module 130 as a photovoltaic power plant, the inverter 140 may also include a maximum power tracking (Maximum Power Point Tracking, MPPT) circuit to enable maximum power tracking of the photovoltaic power plant.

The power grid 20 may be, for example, a utility power grid. It is understood that the present application is not limited to the type of ac power of the power grid 20, and in other embodiments, the power grid 20 may be single-phase ac power, three-phase ac power, or other multi-phase ac power, etc. The load 30 may be various kinds of electric loads in the home, or may be an important load.

As can be appreciated, in a photovoltaic power supply system having an energy storage device (i.e., the battery pack 110) coupled to the dc side of the power supply system 10, when the energy storage device discharges, the discharge power of the energy storage device and the generated power of the photovoltaic module are output as the total discharge power to the input terminal of the inverter. Therefore, the discharge curve of the energy storage device may affect the maximum power tracking of the inverter, which in turn affects whether the photovoltaic module can operate at the maximum power point. In order to operate the photovoltaic module at a maximum power point, one of the discharge modes of the energy storage device is to construct a power-voltage (PV) curve for the energy storage device to simulate the discharge of the PV curve of the photovoltaic module. The simulated PV curve needs to be matched with the actual PV curve of the photovoltaic module so that the energy utilization rate of the photovoltaic module can be maximized under various working conditions, and in an ideal state, the maximum power point voltage of the simulated PV curve is overlapped with the maximum power point voltage of the photovoltaic module.

However, even the same photovoltaic module has the PV curve that changes with the external environment, such as lighting conditions, ambient temperature, local shadow shielding, etc., which affect the open-circuit voltage and the maximum power point voltage of the photovoltaic module, and in practical application, the type and brand of the connected photovoltaic module may change, and the PV curve parameters of the photovoltaic module also change with different brands and different types. This means that the actual PV curve of the photovoltaic module will change frequently, and in actual operation, the energy storage device cannot obtain the actual PV curve of the photovoltaic module at any time, and the simulated PV curve of the energy storage device cannot perfectly follow the actual PV curve of the photovoltaic module to make adjustment in real time, which will tend to reduce the energy utilization rate of the photovoltaic module.

Therefore, the present application provides a discharge control method of a power supply circuit, which can improve the energy utilization rate of the photovoltaic module 130. It will be appreciated that the control method may be performed by a controller of the power supply circuit 120. Referring to fig. 2, the control method includes the following steps:

step S201: and obtaining photovoltaic parameters of the photovoltaic module, wherein the photovoltaic parameters comprise photovoltaic voltage.

The photovoltaic voltage refers to an output voltage of the photovoltaic module 130.

In some embodiments, a voltage sensor, or other circuit or electronic device that may enable voltage sampling, may be provided at the output of the photovoltaic module 130 to periodically obtain the photovoltaic voltage at the output of the photovoltaic module 130.

Step S202: the discharge voltage of the power supply circuit is obtained.

In some embodiments, a voltage sensor, or other circuit or electronic device that may enable voltage sampling, may be provided at the second end of the power supply circuit 120 to periodically obtain the discharge voltage at the output of the power supply circuit 120.

Step S203: and moving the simulated discharge curve along with the photovoltaic voltage and the discharge voltage, and controlling the power supply circuit to discharge according to the moved simulated discharge curve.

The simulated discharge curve may be a preset discharge curve that simulates a PV curve of the photovoltaic module. And in the simulated discharge curve, the voltage (discharge voltage of the power supply circuit 120) is taken as an independent variable, and the power (discharge power given value of the power supply circuit 120) is taken as an independent variable. That is, similar to the PV curve, there is also a maximum power point power and a corresponding maximum power point voltage in the simulated discharge curve. And the maximum power point power is the target discharge power of the power supply circuit 120.

As can be appreciated, when the power supply circuit 120 discharges, the discharge power of the power supply circuit 120 and the generated power of the photovoltaic module 130 are output as the total discharge power to the input terminal of the inverter 140. Therefore, in the case of maximum power tracking, the inverter 140 actually performs maximum power tracking on the combined curve obtained by superimposing the analog discharge curve and the PV curve of the photovoltaic module 130. In an ideal situation, the maximum power point voltage of the simulated discharge curve should overlap with the maximum power point voltage of the photovoltaic module 130, so that the energy utilization of the photovoltaic module 130 can be maximized. However, in practical applications, the PV curve of the photovoltaic module 130 may vary with the external environment. In this way, when the photovoltaic voltage of the photovoltaic module 130 is greater than the discharge voltage of the power supply circuit 120, the voltage detected by the MPPT circuit of the inverter 140 during the maximum power tracking process is pulled down; when the voltage of the photovoltaic module 130 is smaller than the discharge voltage of the power supply circuit 120, the voltage detected by the MPPT circuit during the maximum power tracking process is raised, so that a larger error exists in the maximum power tracking performed by the MPPT circuit. In order to reduce the influence of the power supply circuit 120 on the maximum power tracking of the photovoltaic module 130, the scheme provided by the embodiment of the application can follow the photovoltaic voltage and the discharge voltage to move the simulated discharge curve, and the discharge voltage of the power supply circuit 120 is determined by the MPPT circuit and the simulated discharge curve together, so that the photovoltaic voltage of the photovoltaic module can fall into the scanning range of the MPPT circuit as soon as possible along with the photovoltaic voltage and the discharge voltage to move the simulated curve, the power of the photovoltaic module 130 is utilized as soon as possible, and when the maximum power tracking of the MPPT circuit reaches a steady state, the maximum power point voltage of the simulated discharge curve is close to or even overlaps with the maximum power point voltage of the PV curve as much as possible. That is, when the maximum power tracking of the MPPT circuit reaches a steady state, the discharge voltage of the power supply circuit 120 is the maximum power point voltage of the simulated discharge curve, and the photovoltaic voltage of the photovoltaic module 130 is the maximum power point voltage of the PV curve at this time. In this way, the power supply circuit 120 is controlled to discharge according to the shifted simulated discharge curve, so that the discharge power of the power supply circuit 120 is the maximum power (i.e. the target discharge power). Meanwhile, the generated power of the photovoltaic module 130 is also the maximum power, so that the energy utilization rate of the photovoltaic module 130 can be improved.

In summary, in the discharge control method of the power supply circuit provided in the present application, the photovoltaic voltage of the photovoltaic module 130 and the discharge voltage of the power supply circuit are obtained first, so as to move the simulated discharge curve along with the photovoltaic voltage and the discharge voltage and control the power supply circuit 120 to discharge according to the moved simulated discharge curve. The simulated discharge curve can be made to move towards the PV curve by following the photovoltaic voltage and the discharge voltage, so that the MPPT circuit is prevented from continuously tracking in a range far away from the photovoltaic voltage, the influence of the discharge voltage on the maximum power tracking of the MPPT circuit is reduced, and the maximum power point of the simulated discharge curve is made to move along with the maximum power point of the PV curve of the photovoltaic module 130. When the maximum power tracking of the MPPT circuit of the inverter 140 reaches a steady state, the maximum power point voltage of the simulated discharge curve is made to be as close to or even overlap with the maximum power point voltage of the PV curve as possible. In this way, the power supply circuit is controlled to discharge according to the moved simulated discharge curve, and the energy utilization rate of the photovoltaic module 130 can be improved while the target discharge power of the power supply circuit 120 is satisfied.

In some embodiments, the photovoltaic parameters further include a power generation of the photovoltaic module, and step S203 includes:

When the photovoltaic voltage is larger than the first voltage threshold and the generated power is smaller than the first power threshold, the simulated discharge curve is moved along with the photovoltaic voltage and the discharge voltage of the power supply circuit, and the power supply circuit is controlled to discharge according to the moved simulated discharge curve.

The generated power refers to the output power of the photovoltaic module 130. In some embodiments, a power sensor, or other circuit or electronic device that may implement power sampling, may be disposed at the output of the photovoltaic module 130 to periodically obtain the generated power of the photovoltaic module 130 at the output of the photovoltaic module 130. In other embodiments, a current sensor (e.g., a hall sensor) or other circuit or electronic device that can sample the current may be further disposed at the output end of the photovoltaic module 130, so as to periodically obtain the output current of the photovoltaic module 130 at the output end of the photovoltaic module 130. In this way, the generated power of the photovoltaic module 130 can be calculated according to the obtained photovoltaic voltage and the output current of the photovoltaic module 130.

The first voltage threshold is a threshold voltage threshold of the photovoltaic module 130 in the illuminated state and the non-illuminated state, and the first power threshold is a threshold power threshold of the photovoltaic module 130 in the strong illuminated state and the weak illuminated state. For example, the first voltage threshold may be 130V and the first power threshold may be 150W. When the photovoltaic voltage is greater than or equal to the first voltage threshold and the generated power is less than the first power threshold, it is indicated that the current illumination condition may enable the photovoltaic module 130 to generate the photovoltaic voltage, but the generated power of the photovoltaic module 130 is lower, and at this time, the photovoltaic module 130 may be considered to be in the first state, for example, the weak illumination state. It is understood that the low-light state may be, for example, a state in which the photovoltaic module 130 is in a period of low light such as the morning, evening, or cloudy day.

Understandably, the current-voltage characteristics of the photovoltaic module 130 may be different under different illumination. Specifically, in no illumination condition, the photovoltaic module 130 does not output current and photovoltaic voltage. Under weak illumination conditions, the photovoltaic module 130 has an output voltage, but the output power is small due to weak illumination, and almost no current is output. As the illumination increases, the output current of the photovoltaic module 130 increases as the output power increases, but the photovoltaic voltage remains substantially unchanged. When the illumination further increases, the output current of the photovoltaic module 130 continues to increase, and the photovoltaic voltage also increases. When the illumination reaches a certain level, the characteristic curve of the photovoltaic module 130 tends to be stable, and at this time, under the tracking of the MPPT circuit, the output current and the photovoltaic voltage of the photovoltaic module 130 are stable at the maximum power point. Thus, it can be considered that: under the condition of weak illumination, the photovoltaic voltage of the photovoltaic module 130 is low and the change degree of the PV curve is large; the PV curve of the photovoltaic module 130 is relatively stable under high light conditions. Since the output end of the photovoltaic module 130 and the power supply circuit 120 are both connected to the dc bus, when the discharge voltage is greater than the photovoltaic voltage, the photovoltaic module 130 cannot output the generated power under the influence of a reverse diode (not shown in the figure) on the dc bus.

Thus, when it is determined that the photovoltaic module 130 is in the weak illumination state according to the photovoltaic parameters, the principle of moving the simulated discharge curve along with the photovoltaic voltage and the discharge voltage is as follows: after the photovoltaic voltage is detected, continuously moving the simulated discharge curve leftwards, so that the maximum power point voltage of the simulated discharge curve approaches the photovoltaic voltage, and until the maximum power point voltage of the simulated discharge curve reaches the minimum discharge voltage value of the power supply circuit, or the discharge voltage is not reduced any more. It will be appreciated that in low light conditions, the PV module 130 is less powerful, and the PV curve is likely to be to the left of the simulated discharge curve (i.e., the maximum power point voltage of the PV curve is less powerful as well as the power). At this time, as long as the photovoltaic voltage is detected and the generated power is confirmed to be smaller than the first power threshold, the simulated discharge curve can be moved leftwards, so that the maximum power point of the simulated discharge curve can be quickly close to the maximum power point of the PV curve. For the MPPT circuit, in the process of moving the simulated discharge curve to the left and approaching the PV curve, the MPPT tracking range is continuously moved to the left until the discharge voltage of the power supply circuit 120 is adjusted to be near the maximum power point voltage of the photovoltaic module 130, or the discharge voltage cannot be reduced, so that the photovoltaic module 130 can output the generated power as soon as possible. Meanwhile, when the maximum power point of the simulated discharge curve is close to the maximum power point of the PV curve, if the discharge voltage increases, it indicates that the MPPT tracks rightward, that is, the maximum power point of the PV curve and the maximum power point of the composite curve are already located on the right side of the maximum power point of the simulated discharge curve, then the simulated PV curve should move rightward following the discharge voltage (i.e., the MPPT tracking voltage). By repeating the above steps, under the maximum power tracking of the inverter 140, the maximum power point voltage of the simulated discharge curve will be close to or even overlap with the maximum power point voltage of the PV curve, so that the power supply circuit 120 is controlled to discharge according to the moved simulated discharge curve, the influence on the photovoltaic module 130 can be reduced, and the energy utilization rate of the photovoltaic module 130 can be improved.

In some embodiments, the discharge control method of the power supply circuit further includes:

when the photovoltaic voltage is smaller than or equal to a first voltage threshold, controlling the power supply circuit to discharge according to an initial discharge curve; the initial discharge curve is an initial simulated discharge curve, and the maximum power point and the open-circuit voltage of the initial discharge curve are set according to the target discharge power of the power supply circuit and MPPT scanning parameters of the inverter.

Understandably, the photovoltaic module 130 can be considered to be in a second state, such as a no-illumination state, when the photovoltaic voltage is less than the first voltage threshold. The no-illumination state may be, for example, a state of the photovoltaic module 130 during a period of time in which there is no illumination at all at night.

Since the photovoltaic module 130 may be switched to the weak illumination state when the photovoltaic module 130 is in the no illumination state, the power supply circuit 120 is controlled to discharge according to the initial discharge curve when the photovoltaic module 130 is in the no illumination state, so that the photovoltaic module 130 can conveniently move along the PV curve of the photovoltaic module 130 when the state of the photovoltaic module 130 is switched.

Further, since the initial discharge curve is set according to the target discharge power of the power supply circuit 120 and the MPPT scan parameter of the inverter 140, compared with the prior art in which the discharge curve is established according to the parameter of the PV curve of the photovoltaic module 130, the initial discharge curve in the present application does not need to consider the real curve parameter of the photovoltaic module 130, so that the discharge control of the power supply circuit 120 can be more conveniently and rapidly realized while the energy utilization rate of the photovoltaic module 130 is improved.

and when the photovoltaic voltage is larger than the first voltage threshold and the generated power is larger than or equal to the first power threshold, controlling the power supply circuit to discharge according to the target discharge power and the photovoltaic voltage.

It can be appreciated that when the photovoltaic voltage is greater than or equal to the first voltage threshold and the generated power is greater than or equal to the first power threshold, the current illumination condition is illustrated such that the photovoltaic module 130 generates a higher photovoltaic voltage and generated power, and thus the photovoltaic module 130 can be considered to be in a third state, such as a strong illumination state. The high light status may be, for example, a status of the photovoltaic module 130 during a period of daytime light charging.

When the photovoltaic module 130 is in the strong illumination state, the photovoltaic voltage is in a more stable state, i.e., the maximum power point on the PV curve is more stable. At this time, the power supply circuit 120 is controlled to exit the simulated discharge curve, and the power supply circuit 120 is controlled to discharge according to the target discharge power and the photovoltaic voltage. Thus, the inverter 140 need only track the PV curve, corresponding to translating the PV curve upward.

Understandably, when the photovoltaic module 130 is in the strong illumination state, the power supply circuit 120 is directly controlled to discharge according to the target discharge power and the photovoltaic voltage, so that the control complexity can be reduced, and the computational power resource of the power supply circuit 120 can be saved.

In some embodiments, controlling the power supply circuit to discharge according to the target discharge power and the photovoltaic voltage may be: the discharge voltage of the power supply circuit 120 is controlled to be adjusted to the value of the photovoltaic voltage, and the discharge power of the power supply circuit 120 is controlled to be the target discharge power.

It is understood that the above-mentioned dividing the low-light state, the no-light state and the high-light state according to the first voltage threshold and the first power threshold is only a dividing method in an embodiment of the present application. In other embodiments, the low-light state, the no-light state and the high-light state may be further classified according to other thresholds, which are not limited by the division basis or the specific threshold value.

For example, in other embodiments, the discharge control method of the power supply circuit further includes:

when the photovoltaic voltage is smaller than the second voltage threshold, controlling the power supply circuit to discharge according to the initial discharge curve; wherein the second voltage threshold is less than the first voltage threshold, e.g., the second voltage threshold may be 125V;

and when the photovoltaic voltage is greater than or equal to a second voltage threshold and the generated power is greater than or equal to a second power threshold, controlling the power supply circuit to discharge according to the target discharge power and the photovoltaic voltage, wherein the second power threshold is greater than the first power threshold, and for example, the second power threshold can be 500W.

Thus, by adding the second voltage threshold and the second power threshold, a voltage return difference and a power return difference can be formed, so that the power supply circuit 120 is prevented from repeatedly switching back and forth between determining that the photovoltaic module 130 is in the weak illumination state and the no illumination state.

In summary, according to the discharging control method of the power supply circuit provided by the application, the state of the photovoltaic module 130 is determined according to the photovoltaic parameters by obtaining the photovoltaic parameters such as the photovoltaic voltage and the generated power of the photovoltaic module 130. Further, when the photovoltaic module 130 is in the weak illumination state, the power supply circuit 120 moves the simulated discharge curve along with the photovoltaic voltage and the discharge voltage, and controls the power supply circuit to discharge according to the moved simulated discharge curve, so that the maximum power point voltage of the simulated discharge curve and the maximum power point voltage in the PV curve of the photovoltaic module are close to or even overlap, and the maximum power tracking of the MPPT circuit can be tracked to the vicinity of the maximum power point in the PV curve when reaching a steady state, thereby improving the utilization rate of the photovoltaic module. In the no-illumination state of the photovoltaic module 130, the power supply circuit 120 is controlled to discharge according to the initial discharge curve so as to conveniently follow the PV curve movement of the photovoltaic module 130 when the photovoltaic module 130 is switched to the no-illumination state. The initial discharge curve is set according to the MPPT scan parameter of the inverter 140, so that the real PV curve parameter of the photovoltaic module 130 is not required to be considered, and the problem of distortion of the initial discharge curve caused by the external environment is not required to be worried, so that the discharge control of the power supply circuit 120 can be more conveniently and rapidly realized while the energy utilization rate of the photovoltaic module 130 is improved. In the state that the photovoltaic module 130 is in the strong illumination state, the power supply circuit 120 is directly controlled to discharge according to the target discharge power and the photovoltaic voltage, so that the power supply circuit 120 synchronously works at the maximum power point of the photovoltaic module 130 under the MPPT tracking of the inverter 140. In this way, the discharge control method of the power supply circuit provided by the application can enable the maximum power point voltage tracked by the MPPT of the inverter to be always close to the maximum power point voltage of the photovoltaic module through switching in the three states, so that the energy utilization rate of the photovoltaic module is improved.

With continued reference to fig. 3, in some embodiments, the MPPT scan parameters include a maximum scan voltage and a minimum scan voltage, and the method further includes, before controlling the power supply circuit to discharge according to the initial discharge curve:

step S301: when the maximum scan voltage is greater than or equal to the first scan voltage, determining the first voltage value as an open circuit voltage of the initial discharge curve.

The first scan voltage is a preset maximum scan voltage reference value. The first voltage value is an open circuit voltage preset value. And the first voltage value is smaller than the first scanning voltage.

It can be appreciated that, since the MPPT circuit of the inverter 140 has a limited voltage scan range when performing the maximum power tracking, the analog discharge curve is moved along with the photovoltaic voltage and the discharge voltage, i.e. the analog discharge curve is moved within the voltage scan range of the inverter 140. Thus, in order to shorten the time required for the movement, the initial simulated discharge curve, i.e., the discharge voltage on the initial discharge curve should be located approximately in the middle region within the voltage scanning range of the conventional inverter 140. Although the MPPT scanning parameters of different inverters are different, the voltage scanning ranges of most common inverters are relatively similar. For example, an inverter having a maximum sweep voltage greater than the first sweep voltage has been able to determine a voltage sweep range common to such inverters, i.e., 0V to the first sweep voltage. The first voltage value is located in a middle region of a voltage sweep range of the portion of the inverter. Therefore, when the maximum scan voltage of the inverter 140 is greater than the first scan voltage, the open circuit voltage of the initial discharge curve may be determined based on the first scan voltage and the first voltage value such that the final initial discharge curve is located approximately in the middle region of the voltage scan range of this type of inverter.

In step S301, the first scan voltage may be 550V, for example, and the first voltage value may be 500V, for example.

Step S302: and when the maximum scanning voltage is smaller than the first scanning voltage, determining the open-circuit voltage of the initial discharge curve according to the maximum scanning voltage and the first voltage parameter.

The first voltage parameter is a preset difference between the open-circuit voltage and the maximum scanning voltage.

It can be appreciated that when the maximum scan voltage of the inverter 140 is smaller than the first scan voltage, the open circuit voltage of the initial discharge curve is directly determined according to the maximum scan voltage of the inverter 140 and the first voltage parameter, so that the discharge voltage of the initial discharge curve is within the voltage scan range of the inverter 140.

In some embodiments, the value obtained by subtracting the first voltage parameter from the maximum scan voltage may be used as the open circuit voltage.

In step S302, the first voltage parameter may be, for example, 50V.

Step S303: and determining the maximum power point power of the initial discharge curve according to the target discharge power.

The target discharge power is an ideal value of the discharge power of the power supply circuit 120 calculated according to the closed loop power control between the power supply system 10 and the power grid 20.

In step S303, the value of the maximum power point power may be set to the value of the target discharge power. In this way, when the maximum power tracking of the analog discharge curve reaches the steady state, the inverter 140 can make the power supply circuit 120 operate at the maximum power point of the initial discharge curve, so that the discharge power of the power supply circuit 120 is the target discharge power.

Step S304: and determining the maximum power point voltage of the initial discharge curve according to the open circuit voltage and the second voltage parameter.

The second voltage parameter is a preset difference value between the open-circuit voltage and the maximum power point voltage.

In some embodiments, the value of the open circuit voltage minus the second voltage parameter may be taken as the maximum power point voltage.

In step S304, the second voltage parameter may be, for example, 100V.

Step S305: and generating an initial discharge curve according to the open circuit voltage, the maximum power point power and the maximum power point voltage.

Understandably, because the real PV curve formulation is complex, software is not easy to implement and implementation is not significant. The PV curve of the photovoltaic module can thus be imitated, and the initial discharge curve is characterized by a correlation function.

Specifically, referring to fig. 4, fig. 4 is a conventional shape of a PV curve of a photovoltaic module. In fig. 4, (1) represents the open circuit voltage of the PV curve; (2) representing a current photovoltaic voltage; (3) representing a maximum power point voltage; (4) representing a maximum power point power; (5) representing the current generated power corresponding to the current photovoltaic voltage. By observing the PV curve shown in fig. 4, the PV curve can be roughly divided into two curves: the first section of curve is a curve between zero point and the maximum power point (namely zero point to (4)); the second curve is a curve between the maximum power point and the point where the open circuit voltage is located (i.e., (4) to (4)).

Similarly, in the case that the open circuit voltage, the maximum power point power, and the maximum power point voltage have been determined in steps S301 to S304, the shapes of two curves of the voltage zero point to the maximum power point and the maximum power point to the point where the open circuit voltage is located may be fitted with a function in step S305 to form an initial discharge curve.

It is understood that the functions used to form the initial discharge curve include, but are not limited to, exponential functions, quadratic functions, or composite functions formed by a combination of multiple function types. The specific function of forming the initial discharge curve is not limited in this application, and the initial discharge curve may be similar to the PV curve (e.g., approximately inverted V-shaped) shown in fig. 4, and the initial discharge curve has the maximum power point power, the maximum power point voltage and the open circuit voltage determined in steps S301 to S304.

In summary, in step S301 to step S305, the open-circuit voltage and the maximum power point voltage of the initial discharge curve are determined according to the MPPT scan parameter of the inverter 140, the maximum power point power of the initial discharge curve is determined according to the target discharge power of the power supply circuit 120, and then the curve between the zero point and the maximum power point and the point between the maximum power point and the open-circuit voltage is fitted by a function to form the initial discharge curve. Thus, the initial discharge curve formed by the method does not need to consider the real PV curve parameters of the photovoltaic module 130, and the problem of distortion of the initial discharge curve caused by the external environment is not required.

Referring to fig. 5, when the photovoltaic voltage is smaller than the first voltage threshold, controlling the power supply circuit to discharge according to the initial discharge curve includes:

step S501: and when the discharge voltage is smaller than or equal to the maximum power point voltage, determining a given value of the discharge power according to the target discharge power and the maximum power point voltage.

It will be appreciated that since the initial discharge curve is a simulated conventional PV discharge curve, the discharge power setpoint is greater when the discharge voltage is closer to the maximum power point voltage when the discharge voltage is less than or equal to the maximum power point voltage, similar to the conventional PV curve. That is, when the discharge voltage is less than or equal to the maximum power point voltage, the gap between the discharge power given value and the maximum power point voltage minus the discharge voltage is in a negative correlation, and the discharge power given value reaches a maximum value when the discharge voltage is equal to the maximum power point voltage, and the maximum value of the discharge power given value is the maximum power point power.

Step S502: and when the discharge voltage is larger than the maximum power point voltage and smaller than or equal to the open-circuit voltage, determining a given value of the discharge power of the power supply circuit according to the reserved power, the target discharge power, the open-circuit voltage and the maximum power point voltage.

Wherein the reserved power is the power required by the power supply circuit 120 to establish the open circuit voltage of the initial discharge curve. Understandably, in a conventional PV curve such as that shown in fig. 4, when the photovoltaic voltage is an open circuit voltage, the generated power is 0. However, in the power supply circuit, in order to maintain the discharge voltage of the power supply circuit 120 at the open circuit voltage, the power supply circuit 120 needs to output at least the discharge power, otherwise, in the case where the discharge power is 0, the discharge voltage of the power supply circuit 120 is also 0 at this time, and the discharge voltage cannot be maintained at the open circuit voltage. Thus, in step S502, when the discharge voltage is equal to the open circuit voltage, the discharge power set value is the minimum value, and the minimum value is the reserve power.

Understandably, like the conventional PV curve shown in fig. 4, when the discharge voltage is greater than the maximum power point voltage and the discharge voltage is less than or equal to the open circuit voltage, the farther the discharge voltage is from the maximum power point voltage and the closer the discharge voltage is to the open circuit voltage, the smaller the discharge power set point. That is, when the discharge voltage is greater than the maximum power point voltage and less than or equal to the open circuit voltage, the discharge power given value and the discharge voltage minus the maximum power point voltage have a negative correlation.

Step S503: and when the discharge voltage is larger than the open circuit voltage, determining the given value of the discharge power as the reserved power.

In step S503, the reserved power is also used to maintain and respond to the MPPT function of the inverter 140 while maintaining the power supply circuit in the state of open circuit voltage. As can be appreciated, since the second end of the power supply circuit 120 and the dc input end of the inverter 140 are both connected to the dc bus, if the set value of the discharge power is configured to be 0 when the discharge voltage is greater than the open circuit voltage, when the photovoltaic module is in the no-illumination state and the discharge voltage is greater than the open circuit voltage, the set value of the discharge power is 0, the power supply circuit 120 stops outputting the discharge power, so that the inverter 140 cannot continue to track the maximum power or even work normally. Therefore, in step S503, when the discharge voltage is greater than the open circuit voltage, it is determined that the discharge power set value is the reserve power to maintain the inverter 140 to operate normally.

In some embodiments, the reserved power is 20W. It is understood that the reserved power can be adjusted according to specific circuit parameters of the power supply circuit 120 and the inverter 140, and the reserved power is not limited in value.

Step S504: and controlling the power supply circuit to discharge according to the set value of the discharge power.

In step S504, the power supply circuit 120 is closed-loop controlled with the discharge power given value as a target of adjustment, and then the discharge power output from the power supply circuit 120 to the inverter 140 is made to approach the discharge power given value by a deviation controller such as a P controller (proportional controller ), PI controller (proportional integral controller, proportional integral controller), PID controller (Proportion Integration Differentiation, proportional-integral-derivative controller), or the like.

In this way, by executing steps S501 to S504, when the photovoltaic voltage is less than the first voltage threshold, the power supply circuit is controlled to discharge according to the initial discharge curve, so as to improve the self-use efficiency of the photovoltaic system. It is understood that when the photovoltaic voltage is less than the first voltage threshold, the discharge power of the power supply circuit 120 is the main power source of the dc input of the inverter 140. Therefore, when the maximum power tracking of the inverter 140 reaches the steady state, the power supply circuit 120 is enabled to stably discharge to the inverter 140 at the maximum power point of the initial discharge curve, i.e. the power supply circuit 120 outputs the target discharge power to the inverter 140.

Referring to fig. 6, fig. 6 is an initial discharge curve obtained according to steps S501 to S505 in an embodiment of the present application. Illustratively, in some scenarios, the function of the initial discharge curve may be:

in this function, P is a discharge power given value of the power supply circuit 120; u is the discharge voltage of the power supply circuit 120; pwr_tag is the maximum power point power (i.e., target discharge power); mid_vol is the maximum power point voltage; open_vol is open circuit voltage, reserved power is 20W.

It is apparent that the function shown in fig. 6 can satisfy the requirement of calculating the discharge power given value of step S501 to step S503.

It is understood that the function of the initial discharge curve is not limited to the above-described function, and the present application does not limit the function of the initial discharge curve.

In some embodiments, when the photovoltaic voltage is greater than the first voltage threshold and the generated power is less than the first power threshold, moving the simulated discharge curve along with the photovoltaic voltage and the discharge voltage of the power supply circuit, and controlling the power supply circuit to discharge according to the moved simulated discharge curve, comprising:

when the photovoltaic voltage is larger than a first voltage threshold value and the generated power is smaller than the first power threshold value, the open-circuit voltage of the simulated discharge curve is reduced according to a first preset step length to shift the simulated discharge curve to the left, and when the open-circuit voltage reaches the minimum open-circuit voltage of the power supply circuit or the open-circuit voltage is smaller than a dynamic voltage value, the left-shift simulated discharge curve is stopped, wherein the dynamic voltage value is dynamically set according to the discharge voltage.

It will be appreciated that the controller of the power supply circuit 120 can only take the photovoltaic voltage and cannot determine that the maximum power point of the photovoltaic module 130 is to the left or right of the current discharge voltage, so the power supply circuit 120 cannot actually determine whether the simulated discharge curve should be shifted left or right to be close to the maximum power point of the PV curve of the photovoltaic module 130. However, since the current photovoltaic module 130 is in the weak illumination state and the maximum power point of the photovoltaic module 130 in the weak illumination state may be far to the left than the maximum power point of the photovoltaic module 130 in the strong illumination state, the open circuit voltage (and the maximum power point voltage) of the active control simulated discharge curve in the embodiment is shifted to the left to increase the chance that the maximum power point voltage of the simulated discharge curve and the maximum power point voltage of the PV curve overlap.

The first preset step length represents the change amount of each left shift of the open-circuit voltage. For example, the first preset step size may be 0.5V/S. And reducing the open-circuit voltage of the simulated discharge curve according to the first preset step length to shift the simulated discharge curve leftwards, namely, shifting the position of the open-circuit voltage of the simulated discharge curve leftwards by 0.5V so as to obtain a new simulated discharge curve.

It is understood that, since the maximum power point voltage is related to the open circuit voltage, the open circuit voltage of the analog discharge curve is lowered according to the first preset step size, and at the same time, the maximum power point voltage of the analog discharge curve is lowered according to the first preset step size, thereby shifting the analog discharge curve to the left.

The specific value of the first preset step is not limited in this application.

The minimum open circuit voltage characterizes the lower limit of the open circuit voltage due to the circuit parameters of the power supply circuit 120. It will be appreciated that the power supply circuit 120 discharges with the lowest discharge voltage, i.e., the magnitude of the left shift of the simulated discharge curve is limited in terms of the circuit performance parameters of the power supply circuit 120 itself. Accordingly, by setting the minimum open circuit voltage, the left shift is stopped when the discharge voltage approaches the lower discharge voltage limit of the power supply circuit 120. In some embodiments, the minimum open circuit voltage may be the lowest discharge voltage of the power supply circuit 120 in the full power state, and the minimum open circuit voltage may be 210V. Thus, the left shift amplitude of the open circuit voltage can be conveniently controlled by comparing the magnitude relation between the left shifted open circuit voltage and the minimum open circuit voltage.

In other embodiments, the minimum open circuit voltage may be the sum of the minimum discharge voltage of the power supply circuit 120 and the second voltage parameter. It will be appreciated that, since the difference between the open-circuit voltage of the simulated discharge curve and the maximum power point voltage is the second voltage parameter, setting the minimum open-circuit voltage to the sum of the minimum discharge voltage and the second voltage parameter may enable the power supply circuit 120 to operate at the maximum power point even at the minimum discharge voltage.

In other embodiments, the minimum open circuit voltage may also be set according to different circuit parameters of the power supply circuit, and the specific value of the minimum open circuit voltage is not limited in this application.

The dynamic voltage value is used to characterize the dynamic open circuit voltage range derived from the discharge voltage. It can be appreciated that since there is a preset distance (e.g., the value of the second voltage parameter in step S304) between the maximum power point voltage and the open circuit voltage on the analog discharge curve, if the inverter 140 mainly tracks the analog discharge curve, the discharge voltage should be closer to the maximum power point voltage, i.e., the discharge voltage is less than the open circuit voltage, and the discharge voltage has a distance slightly less than the preset distance from the open circuit voltage. Thus, a dynamic open circuit voltage range can be calculated based on the discharge voltage. Thus, when the open circuit voltage after the shift is smaller than the dynamic value, the current left shift is excessive, and the left shift should be stopped.

In summary, the embodiment controls the left shift of the simulated discharge curve by reducing the open circuit voltage on the simulated discharge curve, so as to increase the probability of overlapping the maximum power point voltage of the simulated discharge curve and the maximum power point voltage of the PV curve when the photovoltaic module 130 is in the weak illumination state, thereby improving the energy utilization rate of the photovoltaic module 130.

With continued reference to fig. 7, in some embodiments, the dynamic voltage value is a sum of the discharge voltage and a first predetermined voltage value. When the photovoltaic voltage is greater than the first voltage threshold value and the generated power is less than the first power threshold value, the simulated discharge curve is moved along with the photovoltaic voltage and the discharge voltage of the power supply circuit, and the method further comprises the following steps:

step S701: and stopping leftwards shifting the simulated discharge curve when the reduced open circuit voltage is smaller than the dynamic voltage value.

The first preset voltage value is used for representing a voltage difference between the discharge voltage and the shifted open-circuit voltage. In some embodiments, the first preset voltage value is, for example, 95V, and the sum of the discharge voltage and the first preset voltage value can be calculated as the dynamic voltage value.

Since the value obtained by subtracting the second voltage parameter from the open circuit voltage is taken as the maximum power point voltage in step S304, the second voltage parameter is 100V. Thus, the reduced open circuit voltage is smaller than the dynamic voltage value, and the difference obtained by subtracting the maximum power point voltage of the left-shifted simulated discharge curve from the discharge voltage is larger than 5V. It is understood that the discharge voltage minus the maximum power point voltage after the left shift is greater than 5V, which should be affected by the photovoltaic module 130, to indicate that the maximum power point voltage of the photovoltaic module 130 may be tracked currently, and the maximum power point voltage of the composite curve (the PV curve of the photovoltaic module 130 is combined with the simulated discharge curve) is greater than the maximum power point voltage of the simulated discharge curve after the left shift, so that the MPPT circuit of the inverter tracks to the right. Therefore, the left-shift simulated discharge curve should be stopped at this time, but the simulated discharge curve is shifted right according to the discharge voltage (i.e., the MPPT voltage of the inverter) so as to be closer to the PV curve of the photovoltaic module 130, so as not to reduce the generated power of the photovoltaic module 130.

The specific value of the first preset voltage value is not limited in this application. In other embodiments, the first preset voltage value may also be other values.

Step S702: and updating the open-circuit voltage of the simulated discharge curve according to the dynamic voltage value to shift the simulated discharge curve to the right.

In some embodiments, the dynamic voltage value may be taken as an updated open circuit voltage. In this way, when it is determined in step S701 that the left-shifted open circuit voltage is smaller than the dynamic voltage value, the updated open circuit voltage is directly converted to the dynamic voltage value in step S702 to increase the open circuit voltage of the simulated discharge curve so as to shift the simulated discharge curve to the right. In this way, when the generated power of the photovoltaic module 130 causes the inverter 140 to track right, the simulated discharge curve can be shifted right in time, and finally the maximum power tracking of the inverter 140 reaches a steady state, so that the maximum efficiency utilizes the energy of the photovoltaic module 130.

Further, the operation of the power supply circuit 120 when the photovoltaic module 130 is in the low-light state will be described below with the scenes shown in fig. 8 to 10. Fig. 8 is a schematic diagram of a first PV curve and a simulated discharge curve of the photovoltaic module 130 in a weak illumination state;

FIG. 9 is a schematic diagram of a second PV curve and simulated discharge curve for a photovoltaic module 130 in a low-light state; fig. 10 is a schematic diagram of a third PV curve and a simulated discharge curve of the photovoltaic module 130 in a low-light state.

Referring to fig. 8, in fig. 8, a curve P81 is a PV curve; curve P82 is a simulated discharge curve. As shown by the curve P81 of fig. 8, the maximum power point power on the curve P81 is much smaller than the maximum power point power on the curve P82. In this way, the PV curve of the photovoltaic module 130 has little influence on the inverter 140 during the maximum power tracking, and the inverter 140 mainly tracks the simulated discharge curve during the maximum power tracking. It can be appreciated that during the process of shifting the open circuit voltage of the curve P82 to the left according to the first preset step-down curve P82, the inverter 140 keeps tracking the maximum power, but since the inverter 140 mainly tracks the simulated discharge curve during the maximum power tracking, the discharge voltage is always near the maximum power point voltage of the simulated discharge curve, and the condition of shifting the simulated discharge curve to the right is triggered with a low probability. In this way, the simulated discharge curve is not stopped until the open circuit voltage reaches the minimum open circuit voltage open_vol_min. In this case, the photovoltaic module 130 may not operate at the maximum power point of the PV curve, but the photovoltaic utilization is almost lossless because the generated power of the photovoltaic module 130 itself is small under such a condition.

Referring to fig. 9, in fig. 9, a curve P91 is a PV curve, and a curve P92 is a simulated discharge curve. The maximum power point of the curve P91 is on the left side of the maximum power point of the curve P92, and the power difference between the maximum power point power of the curve P91 and the maximum power point power of the curve P92 is small. As can be appreciated, during the process of reducing the open-circuit voltage of the curve P92 according to the first preset step to shift left to simulate the discharge curve, the inverter 140 continuously performs the maximum power tracking, and when the curve P92 moves to the point that the maximum power point voltage of the curve P92 and the maximum power point voltage of the curve P91 overlap each other, the maximum power tracking of the inverter 140 reaches a steady state, and at this time, the energy utilization rate of the photovoltaic module 130 is maximum. If the left shift simulation discharge curve is continued so that the maximum power point of the curve P92 is left of the maximum power point of the curve P91, and the power of the curve P92 decreasing when it is disturbed leftwards is smaller than the power of the curve P91 increasing when it is disturbed rightwards, the inverter 140 will increase the power when it is disturbed rightwards, and thus the MPPT circuit of the inverter 140 will pull the photovoltaic voltage and the discharge voltage rightwards. At this time, if the discharge voltage and the left shifted open circuit voltage satisfy the preset distance relationship, or the discharge voltage and the left shifted maximum power point voltage satisfy the preset distance relationship, that is, the reduced open circuit voltage is smaller than the dynamic voltage value, the left shift curve P91 is stopped, and the open circuit voltage of the curve P92 is updated according to the dynamic voltage value to shift the curve P92 to the right. Finally, by continuously moving the curve P92 left and right, when the maximum power tracking of the inverter 140 reaches a steady state, the maximum power point voltages of the curve P92 and the curve P91 are close to each other or even overlap, so as to improve the energy utilization rate of the photovoltaic module 130.

It can be appreciated that in fig. 9, when the open circuit voltage of the curve P92 is reduced to shift left according to the first preset step, if the curve P92 is continuously shifted left, a situation may occur in which the maximum power point of the simulated curve is left of the maximum power point of the PV, as shown in fig. 10. Referring to fig. 10, in fig. 10, a curve P101 is a PV curve, and a curve P102 is a simulated discharge curve. The maximum power point of the curve P101 is on the right side of the maximum power point of the curve P102, and the power difference between the maximum power point power of the curve P101 and the maximum power point power of the curve P102 is small. Similarly, if the power dropped by the left disturbance of the curve P102 is smaller than the power added by the right disturbance of the curve P101, the power added by the right disturbance of the inverter 140 will occur, and thus, the MPPT circuit of the inverter 140 pulls the photovoltaic voltage and the discharge voltage to the right. Taking fig. 10 as an example, the curve P102 has moved excessively left, and it is assumed that the inverter tracks the maximum power point A0 of the curve P102, and when the inverter is perturbed leftwards from A0 to A1, the total input power P becomes smaller, which means that the power of the curve P102 decreasing from A0 to A1 is smaller than the power of the curve P101 increasing from A1 to A0, and the inverter returns to A0 and tracks rightwards to the maximum power point of the curve P101. Therefore, if the discharge voltage and the left shifted open circuit voltage satisfy the preset distance relationship, or the discharge voltage and the left shifted maximum power point voltage satisfy the preset distance relationship, that is, the reduced open circuit voltage is smaller than the dynamic voltage value, the left shift curve P101 is stopped, and the open circuit voltage of the curve P102 is updated according to the dynamic voltage value to shift the curve P102 to the right. Finally, by continuously moving the curve P102 left and right, when the maximum power tracking of the inverter 140 reaches a steady state, the maximum power point voltages of the curve P102 and the curve P101 are close to each other or even overlap, so as to improve the energy utilization rate of the photovoltaic module 130.

In summary, as shown in fig. 8 to 10, the discharging control method of the power supply circuit provided by the present application can work under various working conditions of simulating the discharging curve and the PV curve, and improve the utilization rate of the photovoltaic module 130 when the maximum power tracking of the inverter 140 reaches a steady state.

when the photovoltaic voltage is changed from being greater than the first voltage threshold value to being less than or equal to the first voltage threshold value, updating the open-circuit voltage of the simulated discharge curve according to the second preset step length to move the simulated discharge curve until the moved simulated discharge curve is restored to the initial discharge curve.

It is understood that the photovoltaic voltage changes from being greater than the first voltage threshold to being less than or equal to the first voltage threshold, i.e., the photovoltaic module 130 switches from the low-light state to the no-light state, or the photovoltaic module 130 switches from the high-light state to the no-light state.

The second preset step represents the amount of change in the open circuit voltage each time the simulated discharge curve is updated. In some embodiments, the second preset step size may be 0.1V/S.

In this embodiment, the shifted simulated discharge curve is restored to the initial discharge curve, that is, the open circuit voltage of the shifted simulated discharge curve is equal to the open circuit voltage in the initial discharge curve.

Thus, updating the open circuit voltage of the simulated discharge curve according to the second preset step length to move the simulated discharge curve until the moved simulated discharge curve is restored to the initial discharge curve, comprising:

when the open-circuit voltage of the simulated discharge curve is smaller than the open-circuit voltage in the initial discharge curve, increasing the open-circuit voltage according to a second preset step length to shift the simulated discharge curve to the right until the shifted simulated discharge curve is restored to the initial discharge curve;

when the open-circuit voltage of the simulated discharge curve is larger than the open-circuit voltage in the initial discharge curve, the open-circuit voltage is reduced according to the second preset step length to shift the simulated discharge curve left until the shifted simulated discharge curve is restored to the initial discharge curve.

For example, referring to fig. 11, fig. 11 is a schematic diagram illustrating a moving direction of a simulated discharge curve when a photovoltaic voltage is changed from greater than a first voltage threshold to less than or equal to the first voltage threshold. Wherein, the curve P111 is an initial discharge curve; curve P112 is a simulated discharge curve with an open circuit voltage less than the open circuit voltage of the initial discharge curve; curve P113 is a simulated discharge curve for an open circuit voltage greater than the open circuit voltage of the initial discharge curve.

It is understood that when the photovoltaic voltage changes from greater than the first voltage threshold to less than or equal to the first voltage threshold, if there is an analog discharge curve, such as curve P112, with an open circuit voltage less than the open circuit voltage of the initial discharge curve, the open circuit voltage is increased according to the second preset step to shift the curve P112 to the right until the curve P112 is restored to the curve P111.

When the photovoltaic voltage is changed from being greater than the first voltage threshold value to being less than or equal to the first voltage threshold value, if an analog discharge curve, such as curve P113, exists in which the open circuit voltage is greater than the open circuit voltage of the initial discharge curve, the open circuit voltage is reduced according to the second preset step to shift the curve P113 to the left until the curve P113 is restored to the curve P111.

It will be appreciated that in other embodiments, the second preset step may be other values, and the specific values of the second preset step are not limited in this application.

Understandably, the first preset step length and the second preset step length mentioned in the application may be fixed preset values or dynamic change values; or one of the first preset step length and the second preset step length may be a preset value, and the other of the first preset step length and the second preset step length may be a dynamically changing value. Thus, when the first preset step length and/or the second preset step length are/is a dynamic change value, the movement of the open-circuit voltage and the maximum power point voltage on the simulated discharge curve can be controlled more accurately and rapidly.

Referring to fig. 12, fig. 12 is a schematic diagram illustrating a discharge curve of the power supply circuit 120 and a PV curve of the photovoltaic module 130 when the photovoltaic module 130 is in a strong illumination state. The curve P121 is a PV curve, and the curve P122 is a discharge curve of the power supply circuit 120.

As can be seen from fig. 12, when the photovoltaic module 130 is in the strong illumination state, the power supply circuit 120 exits the simulated discharge curve, and discharges with constant power according to the target discharge power and the photovoltaic voltage.

In some embodiments, the power supply circuit 120 is also configured with a state machine that is run by a controller of the power supply circuit 120 to implement discharge control logic for the power supply circuit.

Referring to fig. 13, in some embodiments, the state machine includes 4 states, such as a low-light discharge state, a no-light discharge state, a high-light discharge state, and a standby state. When a preset event is generated in the power supply circuit 120, a corresponding task state may be executed in response to the preset event. The preset events include, for example, a first preset event, a second preset event, a third preset event, and a fourth preset event. The first preset event comprises that the photovoltaic voltage is larger than a first voltage threshold value, and the generated power is smaller than the first power threshold value; the second preset event includes the photovoltaic voltage being less than or equal to the first voltage threshold; the third preset event comprises that the photovoltaic voltage is larger than a first voltage threshold value, and the generated power is larger than or equal to the first power threshold value; the fourth preset event includes the power supply circuit stopping discharging.

The power supply circuit 120 defaults to a weak light discharge state after starting from a standby state to perform an initialization operation in the weak light discharge state, thereby generating an initial discharge curve.

Understandably, in response to the first preset event, the no-light discharge state or the strong-light discharge state is switched to the weak-light discharge state to move the simulated discharge curve following the photovoltaic voltage and the discharge voltage of the power supply circuit 120 in the weak-light discharge state, and to control the power supply circuit 120 to discharge according to the moved simulated discharge curve.

In response to the second preset event, the weak light discharge state or the strong light discharge state is switched to the no light discharge state to control the power supply circuit 120 to discharge according to the initial discharge curve in the no light discharge state.

In response to the third preset event, the weak light discharge state or the no light discharge state is switched to the strong light discharge state to control the power supply circuit 120 to discharge according to the target discharge power and the photovoltaic voltage in the strong light discharge state.

In response to the fourth preset event, the weak light discharge state, the no light discharge state, or the strong light discharge state is switched to the standby state to control the power supply circuit 120 to exit the discharge mode.

It will be appreciated that, in other embodiments, the power supply circuit 120 may enter the no-illumination discharge state by default after being started from the standby state, so as to perform the initializing operation in the no-illumination discharge state, thereby generating the initial discharge curve.

It is to be understood that the specific discharge control method of the power supply circuit has been described above, and will not be described herein.

With continued reference to fig. 14, in some embodiments, the output of the inverter is connected to the grid via an ac bus that is also used for load access to the grid. And the discharging control method of the power supply circuit further comprises the following steps:

step S141: and acquiring actual grid-connected power between the alternating current bus and the power grid.

Referring to fig. 1 together, it can be appreciated that when the output of the inverter 140 is connected to the grid 20 via an ac bus, it is referred to as grid-tie. The actual grid-tied power is used to represent the power supply relationship between the inverter 140 connected to the ac bus and the load 30 and the grid 20. For example, the actual grid-tied power may be positive, negative, or 0, depending on the inverter 140 and the direction of energy flow between the load 30 and the grid 20. For example, when the inverter 140 outputs 10W (watts) to the grid 20 through the ac bus, then the actual grid-tied power is 10W; when the power grid 20 outputs 10W to the alternating current bus to supply power for the load 30, the actual grid-connected power is-10W; when the output power of the inverter 140 just meets the required power of the load 30, that is, the inverter 140 outputs no power to the grid 20, and the grid 20 outputs no power to the load 30, the actual grid-connected power is 0.

It is understood that the definition of positive and negative numbers for actual grid-tied power is merely exemplary. In other embodiments, the grid may also be indicated to supply power to the load when the actual grid-tied power is positive, and the inverter 140 may be indicated to sell power to the grid 20 when the actual grid-tied power is negative.

In some embodiments, a grid monitoring module (not shown) may be provided between the local micro grid system consisting of the power supply system 10 and the load 30 and the grid 20, i.e. between the common connection point of the output of the inverter 140 and the load 30 and the grid 20. The grid monitoring module is used to monitor the grid-tie parameters between the ac bus and the grid 20. The grid-connected parameters may include grid-connected current, grid-connected voltage, actual grid-connected power, and the like. In this way, the controller of the power supply circuit 120 can obtain the actual grid-connected power output from the inverter 140 to the grid 20 or the grid 20 to the load 30 by communicating with the grid monitoring module. In some embodiments, the grid monitoring module may be a smart meter, and the smart meter may transmit actual grid-tied power.

It is understood that the communication between the controller and the power grid monitoring module may be wireless communication (such as bluetooth communication, zigBee communication, etc.), or may be wired communication (such as serial communication based on RS-485 serial bus, or controller area network (Controller Area Network, CAN) bus, or other parallel communication modes), which is not limited in this application.

In other embodiments, the controller may communicate with the inverter 140 and the load 30 to obtain the actual output power of the inverter 140 and the actual power consumption of the load 30, so as to calculate the actual grid-connected power according to the actual output power and the actual power consumption.

Step S142: and determining target discharge power according to the actual grid-connected power and the target grid-connected power.

In step S142, the target grid-tie power is used to characterize an ideal value of the actual grid-tie power between the ac bus and the grid 20. For example, in some embodiments, the target grid-tie power is 0, at which point the power output by inverter 140 just meets the demand power of load 30. As such, the inverter 140 does not have to purchase electricity from the grid 20 nor sell electricity to the grid 20. In some embodiments, the target grid-tie power may also be negative or positive. The meaning of the target grid-connected power is negative or positive, which is substantially the same as the meaning of the actual grid-connected power is positive or negative, and will not be described in detail herein. It is understood that the present application does not limit the specific value of the target grid-tie power.

It will be appreciated that when the actual grid-tie power is greater than the target grid-tie power, it is indicated that the power output by the inverter 140 to the grid 20 is greater than expected at this time, and thus, a portion of the energy output by the photovoltaic module 130 can be stored in the battery pack 110 by charging the battery pack 110. When the actual grid-connected power is smaller than the target grid-connected power, it indicates that the power output by the inverter 140 is insufficient to meet the requirement of the load 30, and the load 30 draws power from the power grid, so that the power supply circuit 120 can obtain the electric energy of the battery pack 110 and then discharge the electric energy, so as to increase the actual output power of the inverter 140 and reduce the power drawing from the power grid 20.

Thus, in step S142, when the actual grid-connected power is smaller than the target grid-connected power, the difference obtained by subtracting the actual grid-connected power from the target grid-connected power may be used as the target discharge power.

The specific calculation mode of the target discharge power calculated in step S142 is not limited, as long as the inventive concept of determining the target discharge power based on the difference between the actual grid-connected power and the target grid-connected power is satisfied. For example, in other embodiments, the power loss in the power supply system, or the error of the smart grid monitoring module may be further combined, so as to determine the target discharge power according to the difference between the actual grid-connected power and the target grid-connected power.

With continued reference to fig. 15, fig. 15 shows a specific control block diagram and a power trend diagram for implementing a discharge control method of a power supply circuit according to an embodiment of the present application by using a closed-loop control algorithm. The following describes a specific workflow of a discharge control method of the power supply circuit according to fig. 15:

first, the actual grid-connected power p_real between the ac bus and the power grid 20 is obtained by the smart meter 40, so as to calculate the deviation power p_dev between the actual grid-connected power p_real and the target grid-connected power p_ aim by the first adder 151. The target discharge power p_dsg of the power supply circuit 120 is then determined according to the deviation power p_dev and a deviation adjustment algorithm preset in the first PI controller 152.

Further, the controller 150 executes the discharge control method of the present application, obtains a discharge power set value p_dsg_tag of the power supply circuit 120 from the target discharge power p_dsg and the simulated discharge curve of the power supply circuit 120, and controls the power supply circuit 120 to output the discharge power p_dsg_real (p_dsg_real≡p_dsg_tag in the steady state of discharge). Since the discharge power p_dsg_real and the photovoltaic power p_pv are commonly input to the dc input terminal of the inverter 140, the sum of the discharge power p_dc and the photovoltaic power p_pv is calculated by the second adder 154 to obtain the dc power p_dc obtained from the dc input terminal of the inverter 140. Inverter 140 power converts dc power p_dc received at the dc input to output ac power p_ac to the ac bus to provide at least a portion of the demanded power p_feed to load 30.

It is to be understood that the PI controller 152 is exemplified by an existing controller in the related art such as PI controller (proportional integral controller, proportional-integral controller). In other embodiments, other controllers such as PID controllers (proportional integral Differentiation controller, proportional-integral-derivative controllers) and the like may be employed, as the present application is not limited in this regard. Correspondingly, the deviation adjustment algorithm may be a PI adjustment algorithm (proportional integral control, proportional integral adjustment), a PID adjustment algorithm (ProportionIntegration Differentiation control, proportional integral differential adjustment), or the like, but may be other adjustment algorithms.

It can be appreciated that, the process of the power supply circuit 120 outputting the discharge power p_dc according to the target discharge power p_dsg may be implemented by the discharge control method of the power supply circuit provided in the present application, for example, by a computer program stored in the controller, and details of the implementation are not repeated herein.

In this way, after determining the target discharge power p_dsg of the power supply circuit 120, the discharge control method based on the power supply circuit may control the power supply circuit 120 to output the discharge power, thereby improving the energy utilization rate of the photovoltaic module 130 while realizing the self-use of the micro-grid system formed by the power supply system 10 and the load 30.

In some embodiments, when the power supply circuit 120 in the power supply system 10 is plural, each power supply circuit can also discharge according to the discharge control method of the power supply circuit provided in any of the embodiments. For example, referring to fig. 16, in one embodiment, the power supply circuit 120 includes a first power supply circuit 121 and a second power supply circuit 122. Accordingly, the inverter 140 is an inverter configured with a plurality of input channels. As shown IN fig. 16, the inverter 140 includes a first input inv_in1+/inv_in1-and a second input inv_in2+/inv_in2-. And the first power supply circuit 121 and the second power supply circuit 122 may be connected to different photovoltaic modules, such as the first photovoltaic module 131 and the second photovoltaic module 132, respectively. In other embodiments, multiple single input channel inverters may be provided in parallel. In this way, in the power supply system 10a shown in fig. 16, after the total discharge power of the power supply circuit 120 is determined according to the actual grid-connected power and the target grid-connected power, the first discharge power is allocated to the first power supply circuit 121 as the target discharge power of the first power supply circuit, and the second discharge power is allocated to the second power supply circuit 122 as the target discharge power of the second power supply circuit, according to the total discharge power. Furthermore, the first power supply circuit 121 may execute the discharge control method provided in any of the above embodiments according to the first discharge power, the photovoltaic parameter of the first photovoltaic module 131, and the discharge voltage of the first power supply circuit 121, so as to improve the energy utilization rate of the first photovoltaic module 131. Similar to the first power supply circuit 121, the second power supply circuit 122 may also execute the discharge control method provided in any of the above embodiments to improve the energy utilization rate of the second photovoltaic module 132.

For example, the specific operation of the power supply system described above is described with the first power supply circuit 121. Referring to fig. 17, fig. 17 is a graph showing the time-dependent power data and voltage data of the first power supply circuit 121 in fig. 16 when discharging according to an embodiment of the present application. The curve P171 is a target discharge power curve of the first power supply circuit 121, the curve P172 is a discharge power set point curve of the first power supply circuit 121, the curve P173 is a discharge voltage curve of the first power supply circuit 121, the curve P174 is a light Fu Dianya curve of the first photovoltaic module 131, the curve P175 is a power generation power curve of the first photovoltaic module 131, and the curve P176 is an actual grid-connected power curve measured by the electric meter. In this embodiment, the minimum scan voltage and the maximum scan voltage in the voltage scan parameters of the inverter 140 are 160V and 1000V, respectively.

At time t0, the required power of the load 30 is 4000W, the actual grid-connected power measured by the electric meter is 4000W, and the photovoltaic voltage is 0V, so that the power supply circuit 120 needs to be controlled to discharge, so that the actual grid-connected power approaches 0, and the spontaneous self-use of the micro-grid system is realized. That is, the total discharge power of the power supply circuit 120 is 4000W. In the present embodiment, the total discharge power is equally distributed, and the target discharge powers of the first power supply circuit 121 and the second power supply circuit 122 are 2000W, respectively.

At time t1, the first power supply circuit 121 generates an initial discharge curve in which the open circuit voltage is 500V, the maximum power point voltage is 400V, the maximum power point power is 2000W, and the reserve power is 20W. At this time, the first photovoltaic module 131 and the second photovoltaic module 132 are not yet connected, and the discharge voltage of the first power supply circuit 121 is 500V, so that the given value of the discharge power of the first power supply circuit 121 is 20W according to the initial discharge curve. At the same time, the inverter 140 starts tracking.

At time t2, the inverter 140 has traced to the maximum power point of the initial discharge curve, at which time the discharge voltage of the first power supply circuit 121 is 400V, and according to the initial discharge curve, the given value of the discharge power of the first power supply circuit 121 is 2000W, similarly, the given value of the discharge power of the second power supply circuit 122 is 2000W, at which time the actual grid-connected power measured by the electric meter is 0W. In this way, the required power of the load is completely supplemented by the discharge of the power supply circuit 120.

At time t3, the first photovoltaic module 131 and the second photovoltaic module 132 are connected, and the PV curves of the first photovoltaic module 131 and the second photovoltaic module 132 are the same. Specifically, the open circuit voltage of the PV curve is 300V, the maximum power point voltage is 250V, and the maximum power point power is 1000W. At time t3, since the open circuit voltage of the first photovoltaic module 131 is lower than the discharge voltage of the first power supply circuit 121, the first photovoltaic module 131 cannot output the generated power due to the reverse diode. After the first power supply circuit 121 detects the photovoltaic voltage of the first photovoltaic module 131, it starts to shift left to simulate the PV curve, and at the same time, the inverter 140 performs maximum power tracking synchronously, and under the MPPT effect of the inverter 140, the discharge voltage of the first power supply circuit 121 gradually decreases.

At time t4, the maximum power point voltage of the simulated discharge curve of the first power supply circuit 121 shifts to 300V to the left, the generated power of the first photovoltaic module gradually increases, and the discharge power of the first power supply circuit 121 gradually decreases. Thereafter, when the generated power of the first photovoltaic module 131 increases to 500W, that is, when the first photovoltaic module 131 is in a strong illumination state, the first power supply circuit 121 exits the simulated discharge curve and discharges according to the target discharge power and the photovoltaic voltage. The inverter 140 then tracks only the PV curve of the first photovoltaic module 131.

At time t5, the inverter 140 tracks to the maximum power point of the PV curve, at which time the generated power of the first photovoltaic module 131 is 1000W, the discharge power of the first power supply circuit 121 is 1000W, and similarly, the generated power of the second photovoltaic module 132 is 1000W, and the discharge power of the second power supply circuit 122 is 1000W. In this way, the first photovoltaic module 131, the first power supply circuit 121, the second photovoltaic module 132 and the second power supply circuit 122 together meet the required power of the load, and the power supply system 10a is stable.

It is understood that the present application does not limit the number of power supply circuits 120. In other embodiments, the power supply system may further include 3 and more power supply circuits.

Referring to fig. 18, the present application further provides a power supply apparatus 100, including a power supply circuit 120 and a controller 150. The power supply apparatus 100 is provided to the power supply system 10. The power supply system 10 includes a battery pack 110, a photovoltaic module 130, an inverter 140, and a power supply apparatus 100. The first end of the power supply circuit 120 is used for connecting to the battery pack 110, and the second end of the power supply circuit 120, the output end of the photovoltaic module 130, and the dc input end of the inverter 140 are all connected to the dc bus. The power supply circuit 120 receives power from the battery pack 110 and outputs the power to the dc bus when discharging. The controller 150 is configured to execute the discharge control method of the power supply circuit described in any one of the embodiments.

In some embodiments, the dc bus is configured within the power supply apparatus 100. In other embodiments, the dc bus may also be configured by other electronic devices connected to the power supply device 100, such as by the inverter 140.

Referring to fig. 19, the present application further provides an energy storage device 200. The energy storage device 200 includes a power supply circuit 120, a battery pack 110, and a controller 150. The energy storage device 200 is disposed in the power supply system 10. The power supply system 10 includes a battery pack 110, a photovoltaic module 130, an inverter 140, and an energy storage device 200. The first end of the power supply circuit 120 is used for connecting to the battery pack 110, and the second end of the power supply circuit 120, the output end of the photovoltaic module 130, and the dc input end of the inverter 140 are all connected to the dc bus. The power supply circuit 120 receives power from the battery pack 110 and outputs the power to the dc bus when discharging. The controller 150 is configured to execute the discharge control method of the power supply circuit according to any one of the embodiments described above.

It is appreciated that in some embodiments, a dc bus may also be provided in the energy storage device 200. In other embodiments, the dc bus may also be configured by other electronics coupled to the energy storage device 200, such as by the inverter 140.

It is understood that the energy storage device 200 may be various electronic devices provided with the battery pack 110, such as, for example, a mobile energy storage device, a home energy storage device, a mobile air conditioner, a mobile refrigerator, etc., and the present application is not limited to the specific functions of the energy storage device 200.

As can be appreciated, the controller 150 is loaded with the energy management system EMS (Energy Management System), and the EMS is configured to perform the discharge control method of the power supply circuit provided herein, so as to implement uniform control over the energy storage device 200. The controller 150 may be a processor independent of the battery pack 110 and the power supply circuit 120, or the controller 150 may be a processor for controlling the battery pack 110, which is loaded with the battery management system BMS (Battery Management System) at the same time. The present application is not limited to the specific form of the controller.

In some embodiments, the controller 150 may communicate with the battery pack 110 via a CAN bus, and the controller 150 may communicate with the power circuit 120 and the electricity meter via an RS-485 serial bus. In other embodiments, the controller 150 may also communicate with the battery pack 110 and the power supply circuit 120 by other wired or wireless communication methods, which is not limited in this application.

An embodiment of the present application further provides a control device applied to the power supply circuit 120 or the electronic device integrated with the power supply circuit 120. Fig. 20 schematically shows a block diagram of a control device 300 provided in an embodiment of the present application. As shown in fig. 20, the control device 300 includes:

the first obtaining module 310 is configured to obtain a photovoltaic parameter of the photovoltaic module 130, where the photovoltaic parameter includes a photovoltaic voltage.

The second acquisition module 320 is configured to acquire a discharge voltage of the power supply circuit 120.

The control module 330 is configured to move the simulated discharge curve along with the photovoltaic voltage and the discharge voltage, and control the power supply circuit 120 to discharge according to the moved simulated discharge curve.

Specific details of the control device 300 for implementing the discharge control method of the power supply circuit provided in the embodiment of the present application have been described in detail in the embodiment of the discharge control method of the corresponding power supply circuit, and are not described herein again.

The present application also provides a computer-readable medium on which a computer program is stored which, when executed by a processor, implements a discharge control method of a power supply circuit as in the above technical solutions. The computer readable medium may take the form of a portable compact disc read only memory (CD-ROM) and include program code that can be run on a terminal device, such as a personal computer. However, the program product of the present invention is not limited thereto, and in this document, a readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.

The program product described above may take the form of any combination of one or more readable media. The readable medium may be a readable signal medium or a readable storage medium. The readable storage medium can be, for example, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or a combination of any of the foregoing. More specific examples (a non-exhaustive list) of the readable storage medium would include the following: an electrical connection having one or more wires, a portable 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), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

The computer readable signal medium may include a data signal propagated in baseband or as part of a carrier wave with readable program code embodied therein. Such a propagated data signal may take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination of the foregoing. A readable signal medium may also be any readable medium that is not a readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device.

Program code embodied on a readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.

Program code for carrying out operations of the present invention may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, C++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computing device, partly on the user's device, as a stand-alone software package, partly on the user's computing device, partly on a remote computing device, or entirely on the remote computing device or server. In the case of remote computing devices, the remote computing device may be connected to the user computing device through any kind of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or may be connected to an external computing device (e.g., connected via the Internet using an Internet service provider).

Furthermore, the above-described drawings are only schematic illustrations of processes included in the method according to the exemplary embodiment of the present invention, and are not intended to be limiting. It will be readily appreciated that the processes shown in the above figures do not indicate or limit the temporal order of these processes. In addition, it is also readily understood that these processes may be performed synchronously or asynchronously, for example, among a plurality of modules.

The foregoing is merely a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any equivalent modifications or substitutions will be apparent to those skilled in the art within the scope of the present application, and these modifications or substitutions should be covered in the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. The discharging control method of the power supply circuit is characterized in that the power supply system comprises a battery pack, a photovoltaic module, an inverter and the power supply circuit, wherein a first end of the power supply circuit is used for being connected with the battery pack, and a second end of the power supply circuit, an output end of the photovoltaic module and a direct current input end of the inverter are all connected to a direct current bus; when the power supply circuit discharges, electric energy is obtained from the battery pack and is output to the direct current bus; the method comprises the following steps:

obtaining photovoltaic parameters of the photovoltaic module, wherein the photovoltaic parameters comprise photovoltaic voltage;

acquiring a discharge voltage of the power supply circuit;

and moving the simulated discharge curve along with the photovoltaic voltage and the discharge voltage, and controlling the power supply circuit to discharge according to the moved simulated discharge curve.

2. The method of claim 1, wherein the photovoltaic parameters further comprise a generated power of the photovoltaic module, the moving the simulated discharge curve following the photovoltaic voltage and the discharge voltage, and controlling the power supply circuit to discharge according to the moved simulated discharge curve, comprising:

and when the photovoltaic voltage is larger than a first voltage threshold and the generated power is smaller than the first power threshold, moving the simulated discharge curve along with the photovoltaic voltage and the discharge voltage of the power supply circuit, and controlling the power supply circuit to discharge according to the moved simulated discharge curve.

3. The method according to claim 2, wherein the method further comprises:

when the photovoltaic voltage is smaller than or equal to the first voltage threshold, controlling the power supply circuit to discharge according to an initial discharge curve; the initial discharge curve is an initial simulated discharge curve, and the maximum power point and the open-circuit voltage of the initial discharge curve are set according to the target discharge power of the power supply circuit and the MPPT scanning parameters of the inverter.

4. The method according to claim 2, wherein the method further comprises:

And when the photovoltaic voltage is larger than the first voltage threshold and the generated power is larger than or equal to the first power threshold, controlling the power supply circuit to discharge according to the target discharge power of the power supply circuit and the photovoltaic voltage.

5. The method of claim 3, wherein the MPPT sweep parameters include a maximum sweep voltage and a minimum sweep voltage, the method further comprising, prior to said controlling the discharge of the power supply circuit according to an initial discharge curve:

when the maximum scanning voltage is greater than or equal to a first scanning voltage, determining a first voltage value as the open-circuit voltage of the initial discharge curve;

when the maximum scanning voltage is smaller than the first scanning voltage, determining the open-circuit voltage of the initial discharge curve according to the maximum scanning voltage and a first voltage parameter;

determining the maximum power point power of the initial discharge curve according to the target discharge power;

determining the maximum power point voltage of the initial discharge curve according to the open circuit voltage and the second voltage parameter;

and generating the initial discharge curve according to the open-circuit voltage, the maximum power point power and the maximum power point voltage.

6. The method of claim 2, wherein the moving the simulated discharge curve following the photovoltaic voltage and the discharge voltage when the photovoltaic voltage is greater than a first voltage threshold and the generated power is less than a first power threshold comprises:

and when the photovoltaic voltage is larger than a first voltage threshold value and the generated power is smaller than a first power threshold value, reducing the open-circuit voltage of the analog discharge curve according to a first preset step length to shift the analog discharge curve leftwards until the open-circuit voltage reaches the minimum open-circuit voltage of the power supply circuit or the open-circuit voltage is smaller than a dynamic voltage value, stopping leftwards shifting the analog discharge curve, wherein the dynamic voltage value is dynamically set according to the discharge voltage.

7. The method of claim 6, wherein the dynamic voltage value is a sum of the discharge voltage and a first preset voltage value, the moving the simulated discharge curve following the photovoltaic voltage and the discharge voltage when the photovoltaic voltage is greater than a first voltage threshold and the generated power is less than a first power threshold, further comprising:

stopping shifting the simulated discharge curve leftwards when the reduced open circuit voltage is smaller than the dynamic voltage value;

And updating the open circuit voltage of the simulated discharge curve according to the dynamic voltage value to shift the simulated discharge curve to the right.

8. A method according to claim 3, characterized in that the method further comprises:

and when the photovoltaic voltage is changed from being greater than a first voltage threshold value to being less than or equal to the first voltage threshold value, updating the open-circuit voltage of the simulated discharge curve according to a second preset step length so as to move the simulated discharge curve until the moved simulated discharge curve is restored to the initial discharge curve.

9. The power supply equipment is characterized by comprising a power supply circuit and a controller, wherein the power supply equipment is arranged in a power supply system, the power supply system comprises a battery pack, a photovoltaic module, an inverter and the power supply equipment, a first end of the power supply circuit is used for being connected with the battery pack, and a second end of the power supply circuit, an output end of the photovoltaic module and a direct current input end of the inverter are all connected to a direct current bus; when the power supply circuit discharges, electric energy is obtained from the battery pack and is output to the direct current bus; the controller is configured to execute the discharge control method of the power supply circuit according to any one of claims 1 to 8.

10. The energy storage device is characterized by comprising a power supply circuit, a battery pack and a controller, wherein the energy storage device is arranged in a power supply system, the power supply system comprises the battery pack, a photovoltaic module, an inverter and the energy storage device, a first end of the power supply circuit is used for being connected with the battery pack, and a second end of the power supply circuit, an output end of the photovoltaic module and a direct current input end of the inverter are all connected to a direct current bus; when the power supply circuit discharges, electric energy is obtained from the battery pack and is output to the direct current bus; the controller is configured to execute the discharge control method of the power supply circuit according to any one of claims 1 to 8.