Control method of power conversion equipment and power conversion equipment

Abstract

The invention provides a control method of power conversion equipment and the power conversion equipment. The control method comprises the following steps: determining a size relationship between a first bus voltage given value and a second bus voltage given value according to a current working mode of the power conversion equipment; acquiring the actual bus voltage of the DC bus and the battery voltage of the battery module; a first driving signal is generated according to the actual bus voltage and the first bus voltage given value so as to control the bidirectional DC / AC conversion circuit; and generating a second driving signal according to the battery voltage, the actual bus voltage and a second bus voltage given value so as to control the bidirectional DC / DC conversion circuit. According to the control method of the power conversion equipment provided by the invention, the voltage stability of the direct current bus can be improved.

Description

Technical Field

[0001] The present application relates to the field of clean energy technology, and in particular to a control method for a power conversion device and a power conversion device. Background Art

[0002] In the related art, when the power conversion device cooperates with the distributed power source, the grid-connected control is usually realized on the AC side. In the power supply system formed by the distributed power source connected to the power conversion device, each input module in the power supply system is completely independent and the coordinated control is complex. In this power supply system, any instability of any module connected to the DC bus in the power conversion device will affect the bus voltage on the DC bus. Therefore, there is an urgent need for a power conversion device and a control method thereof, which can realize the coordinated control of each module in the power supply system and improve the voltage stability of the DC bus. Summary of the invention

[0003] In view of this, the present application provides a control method for a power conversion device and a power conversion device, which can achieve system coordinated control and improve the voltage stability of a DC bus.

[0004] The first aspect of the present application provides a control method for a power conversion device. The power conversion device includes a bidirectional DC / DC conversion circuit, a bidirectional DC / AC conversion circuit, a first DC / DC conversion circuit and a DC bus. The first end of the bidirectional DC / DC conversion circuit is used to connect to a battery module, and the first end of the first DC / DC conversion circuit is used to connect to a renewable DC power supply; the second end of the bidirectional DC / DC conversion circuit, the second end of the first DC / DC conversion circuit and the DC end of the bidirectional DC / AC conversion circuit are all connected to the DC bus, and the AC end of the bidirectional DC / AC conversion circuit is connected to a power grid and / or an AC load through the AC bus; the first DC / DC conversion circuit is used to convert the voltage input from the renewable DC power supply and output a voltage to the DC bus according to a conversion voltage threshold. The control method includes: configuring the magnitude relationship between a first bus voltage given value and a second bus voltage given value according to the current working mode of the power conversion device, wherein the first bus voltage given value is a voltage given value of a DC terminal of a bidirectional DC / AC conversion circuit, the second bus voltage given value is a voltage given value of a second terminal of the bidirectional DC / DC conversion circuit, the first bus voltage given value is not equal to the second bus voltage given value, and the first bus voltage given value and the second bus voltage given value are both less than a conversion voltage threshold; obtaining an actual bus voltage of a DC bus and a battery voltage of a battery module; generating a first drive signal according to the actual bus voltage and the first bus voltage given value to control the bidirectional DC / AC conversion circuit; generating a second drive signal according to the battery voltage, the actual bus voltage and the second bus voltage given value to control the bidirectional DC / DC conversion circuit.

[0005] The second aspect of the present application also provides a power conversion device, including a bidirectional DC / DC conversion circuit, a bidirectional DC / AC conversion circuit, a DC bus and a control circuit. The first end of the bidirectional DC / DC conversion circuit is used to connect to the battery module, the second end of the bidirectional DC / DC conversion circuit and the DC end of the bidirectional DC / AC conversion circuit are both connected to the DC bus, the DC bus is also used to connect to the photovoltaic module, and the AC end of the bidirectional DC / AC conversion circuit is connected to the power grid and / or AC load through the AC bus; the control circuit is used to execute the control method of the power conversion device as described in any of the above items.

[0006] The control method of the power conversion device provided by the present application first determines the magnitude relationship between the first bus voltage given value and the second bus voltage given value according to the current working mode of the power conversion device, and the first bus voltage given value and the second bus voltage given value are both less than the conversion voltage threshold. Among them, the first bus voltage given value is the voltage given value of the DC end of the bidirectional DC / AC conversion circuit, the second bus voltage given value is the voltage given value of the second end of the bidirectional DC / DC conversion circuit, and the conversion voltage threshold is the voltage given value of the second end of the first DC / DC conversion circuit. Then, the actual bus voltage of the DC bus and the battery voltage of the battery module are obtained, and a first drive signal is generated according to the actual bus voltage and the first bus voltage given value to control the bidirectional DC / AC conversion circuit, and a second drive signal is generated according to the battery voltage, the actual bus voltage and the second bus voltage given value to control the bidirectional DC / DC conversion circuit. Through the embodiment of the present application, the voltage at the DC end of the bidirectional DC / AC conversion circuit is always close to the first bus voltage given value, and the voltage at the second end of the bidirectional DC / DC conversion circuit is always close to the second bus voltage given value. Even when the energy outputted from the renewable DC power source to the DC bus through the first DC / DC conversion circuit is small or even nonexistent, and the actual bus voltage is pulled down to a value between the first bus voltage given value and the second bus voltage given value, based on the magnitude relationship between the first bus voltage given value and the second bus voltage given value, the bidirectional DC / AC conversion circuit and the bidirectional DC / DC conversion circuit can clamp each other, so as to form a corresponding energy path on the DC bus while enabling each circuit connected to the DC bus to eventually reach a power balance state, thereby achieving the effect of stabilizing the DC bus voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present application and should not be regarded as limiting the scope of protection of the present application. In each of the drawings, similar components are numbered similarly.

[0008] Figure 1A circuit block diagram of a power conversion device provided in one embodiment of the present application.

[0009] Figure 2 This is a flow chart of a control method for a power conversion device provided in one embodiment of the present application.

[0010] Figure 3 This is provided for an embodiment of the present application.

[0011] Figure 4 Schematic diagram of the flow of sub-steps of step S203 in an embodiment of the present application.

[0012] Figure 5 This is a control block diagram for implementing steps S401 to S404 in one embodiment of the present application.

[0013] Figure 6 Figure (A) is a schematic diagram of the current at the DC end of the bidirectional DC / AC conversion circuit when the power conversion device is switched from a backup power priority mode with a fully charged battery module to a self-generated and self-used mode in an embodiment of the present application, without using the method of clearing the control loop integral value.

[0014] Figure 6 Figure (B) is a schematic diagram of the current at the DC end of the bidirectional DC / AC conversion circuit when the power conversion device switches from a backup power priority mode with a fully charged battery module to a self-generated and self-used mode in another embodiment of the present application, using the method of clearing the control loop integral value.

[0015] Figure 7 Figure (A) is a schematic diagram of the current at the DC end of the bidirectional DC / AC conversion circuit in an embodiment of the present application, when the power conversion device is in a self-generated and self-used mode and the bidirectional DC / DC conversion circuit suddenly fails, and the method of clearing the control loop integral value is not adopted.

[0016] Figure 7 (B) is a schematic diagram of the current at the DC end of the bidirectional DC / AC conversion circuit when the power conversion device is in a self-generated and self-used mode and the bidirectional DC / DC conversion circuit suddenly fails, and the method of clearing the integral value of the control loop is adopted in an embodiment of the present application.

[0017] Figure 8 Schematic diagram of the flow of sub-steps of step S404 in one embodiment of the present application.

[0018] Fig. 9 Schematic diagram of the flow of sub-steps of step S404 in another embodiment of the present application.

[0019] Fig.10 A control block diagram for controlling a bidirectional DC / AC conversion circuit provided in one embodiment of the present application.

[0020] Fig.11 A circuit diagram of a bidirectional DC / DC conversion circuit provided in accordance with an embodiment of the present application.

[0021] Fig.12 A flowchart of the sub-steps of step S204 provided in an embodiment of the present application.

[0022] Fig.13 A flowchart of the sub-steps of step S125 provided in one embodiment of the present application.

[0023] Fig.14 A control block diagram for implementing steps S121 to S126 provided in one embodiment of the present application.

[0024] Fig.15 A circuit block diagram of a power conversion device provided in one embodiment of the present application.

[0025] Fig.16 A circuit block diagram of an energy storage device provided in one embodiment of the present application.

[0026] Fig.17 A module block diagram of a control device provided in one embodiment of the present application.

[0027] Fig.18 A schematic diagram of a computer-readable storage medium provided in accordance with an embodiment of the present application. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0029] It should be noted that when a component is considered to be "connected" to another component, it may be directly connected to the other component or there may be a central component at the same time. When a component is considered to be "located on" another component, it may be directly located on the other component or there may be a central component at the same time. The terms "top", "bottom", "upper", "lower", "left", "right", "front", "back", and similar expressions used herein are for illustrative purposes only.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0031] Some embodiments will be described below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0032] In the related art, when the power conversion device cooperates with the distributed power source, the grid-connected control is usually realized on the AC side. In the power supply system formed by the distributed power source connected to the power conversion device, each input module in the power supply system is completely independent and the coordinated control is complex. In this power supply system, any instability of any module connected to the DC bus in the power conversion device will affect the bus voltage on the DC bus. Therefore, there is an urgent need for a power conversion device and a control method thereof, which can realize the coordinated control of each module in the power supply system and improve the voltage stability of the DC bus.

[0033] First, see Figure 1 , Figure 1 The circuit block diagram of the power conversion device 10 to which the technical solution of the present application is applied is shown. The power conversion device 10 can be connected to at least the battery module 20, the power grid 30, the AC load 40 and the renewable DC power source 50. In this way, the power conversion device 10 can store the DC power generated by the renewable DC power source 50 in the battery module 20, and can also convert the DC power output by the renewable DC power source 50 and / or the battery module 20 into AC power, and output it to the power grid 30 and / or the AC load 40. The power conversion device 10 can also convert the AC power input from the power grid 30 into DC power to charge the battery module 20.

[0034] The power conversion device 10 includes a bidirectional DC / AC conversion circuit 110, a bidirectional DC / DC conversion circuit 120, a first DC / DC conversion circuit 130 and a DC bus, wherein the DC bus includes a positive DC bus BUS+ and a negative DC bus BUS-. The first end of the bidirectional DC / DC conversion circuit 120 is used to connect the battery module 20. The first end of the first DC / DC conversion circuit 130 is used to connect the renewable DC power supply 50. The second end of the bidirectional DC / DC conversion circuit 120, the second end of the first DC / DC conversion circuit 130 and the DC end of the bidirectional DC / AC conversion circuit 110 are all connected to the DC bus. The AC end of the bidirectional DC / AC conversion circuit 110 is connected to the power grid 30 and / or the AC load 40 through the AC bus (at least including the neutral line N and the live line L). An energy storage module is also connected between the positive DC bus BUS+ and the negative DC bus BUS-, and the energy storage module is, for example, a first capacitor C1.

[0035] When the bidirectional DC / AC conversion circuit 110 is in the inverter mode, it is used to convert the DC power received at the DC end into AC power and output it to the AC bus through the AC end, so as to at least supply power to the AC load 40 and / or feed power to the grid 30. When the bidirectional DC / AC conversion circuit 110 is in the rectifier mode, it is used to convert the AC power received at the AC end into DC power and output it to the DC bus through the DC end, so as to at least charge the battery module 20.

[0036] It is understandable that the bidirectional DC / AC conversion circuit 110 may include a rectifier circuit and an inverter circuit. By controlling the switching logic and duty cycle of the rectifier circuit and the inverter circuit, the mode switching between the rectifier mode and the inverter mode of the bidirectional DC / AC conversion circuit 110 and the control of the output voltage are achieved. It is understandable that the bidirectional DC / AC conversion circuit 110 may select an existing bidirectional DC / AC conversion circuit, which is not limited here.

[0037] When the bidirectional DC / DC conversion circuit 120 is in the charging mode, it is used to convert the voltage of the direct current received at the second end and output it through the first end to charge the battery module 20. When the bidirectional DC / DC conversion circuit 120 is in the discharging mode, it is used to convert the voltage of the direct current received at the first end and output it through the second end to discharge the battery module 20 to the DC bus.

[0038] Understandably, the bidirectional DC / DC conversion circuit 120 may use a dual active bridge (DAB) circuit or an LLC circuit. Alternatively, the bidirectional DC / DC conversion circuit 120 may be composed of a BUCK circuit, a BOOST circuit, and a drive circuit. In this way, by controlling the switching logic and duty cycle of the BUCK circuit and the BOOST circuit through the drive circuit, the bidirectional DC / DC conversion circuit 120 may be controlled to operate in a charging mode or a discharging mode, and the conversion voltage of the bidirectional DC / DC conversion circuit 120 may be controlled.

[0039] The first DC / DC conversion circuit 130 is used to convert the voltage input from the renewable DC power source 50 and output a voltage to the DC bus according to a conversion voltage threshold. The first DC / DC conversion circuit 130 can be, for example, a boost circuit, a buck circuit, and / or a buck-boost circuit.

[0040] The renewable DC power source 50 may be, for example, a photovoltaic module, a DC wind-driven wind power, etc. In particular, when the renewable DC power source 50 is a photovoltaic module, the first DC / DC conversion circuit 130 may be a maximum power point tracking (MPPT) circuit to adjust the voltage output by the photovoltaic module to achieve maximum power tracking. The present application does not limit the maximum power tracking algorithm used when the first DC / DC conversion circuit 130 is an MPPT circuit. When the renewable DC power source 50 is a photovoltaic module, it may include a number of photovoltaic panels. The photovoltaic panel converts light energy into electrical energy to output direct current to the power conversion device 10. The present application does not limit the connection method of the photovoltaic panel in the photovoltaic module. For example, in some embodiments, the photovoltaic panels in the photovoltaic module may be connected in series, in parallel, or in series and then in parallel. In other embodiments, the renewable DC power source 50 may also be replaced by other electronic devices that can output direct current, such as batteries, supercapacitors, etc.

[0041] The battery module 20 includes one or more battery cells connected in series and / or in parallel. The battery module 20 is used to store or release energy. In some embodiments, the battery module 20 can be an independently arranged energy storage device or battery pack, or a battery module arranged in an electronic device. The present application does not limit the specific type of the battery module 20.

[0042] The power grid 30 may be, for example, a mains power grid. The present application does not limit the type of AC power of the power grid 30. In other embodiments, the power grid 30 may be single-phase AC power, three-phase AC power, or other multi-phase AC power.

[0043] The AC load 40 may be any type of electrical load.

[0044] See also Figure 2 , Figure 2 A control method for a power conversion device provided in one embodiment of the present application. In some embodiments, a controller (not shown in the figure) in the power conversion device 10 loads an energy management system EMS (Energy Management System). The EMS is used to execute the control method for the power conversion device provided in the present application, thereby achieving unified control of each circuit in the power conversion device 10.

[0045] The control method of the power conversion device provided in the present application comprises the following steps:

[0046] Step S201: Determine the magnitude relationship between a first bus voltage given value and a second bus voltage given value according to the current working mode of the power conversion device.

[0047] Among them, the first bus voltage given value is the voltage given value of the DC end of the bidirectional DC / AC conversion circuit 110, the second bus voltage given value is the voltage given value of the second end of the bidirectional DC / DC conversion circuit 120, the first bus voltage given value is not equal to the second bus voltage given value, and the first bus voltage given value and the second bus voltage given value are both less than the conversion voltage threshold. The conversion voltage threshold is the voltage given value of the second end of the first DC / DC conversion circuit 130. Under normal working conditions, the first DC / DC conversion circuit 130 can obtain the DC power input by the renewable DC power supply 50 for conversion, and output the corresponding DC voltage to the DC bus, thereby improving the energy conversion rate of the power conversion device 10 to the renewable DC power supply 50. In some embodiments, the conversion voltage threshold may be the sum of the output voltage peak value of the renewable DC power supply 50 and the first preset value, and the conversion voltage threshold range is the first limit interval. For example, the first preset value may be 45V, and the first limit interval may be [440V, 543V]. In different working modes, the maximum value of the first bus voltage given value and the second bus voltage given value can be determined according to the sum of the output voltage peak value of the renewable DC power supply 50 and the second preset value. After the maximum value is determined, the range of the first bus voltage given value or the second bus voltage given value corresponding to the maximum value is the second limit interval. For example, the second preset value can be 25V, and the second limit interval can be [420V, 530V]. In some embodiments, the minimum value of the first bus voltage given value and the second bus voltage given value should at least be able to maintain the normal operation of the first DC / DC conversion circuit 130, and also avoid the power of the power grid 30 from being fed back to the DC bus. In some embodiments, after determining the working mode, the minimum value can be determined according to the first voltage and the second voltage. Among them, the first voltage is the sum of the peak-to-peak voltage of the power grid 30 and the first compensation value. The second voltage is the sum of the output voltage peak value of the renewable DC power supply 50 and the second compensation value. For example, the first compensation value can be 15V, and the second compensation value can be 10V. After determining the minimum value, the range of the first bus voltage given value or the second bus voltage given value corresponding to the minimum value is the third limit interval, for example, the third limit interval may be [360V, 523V]. In some embodiments, when the working mode is the first mode, the limit interval of the first bus voltage given value may be [420V, 530V], and the limit interval of the second bus voltage given value may be [360V, 523V]. When the working mode is the second mode, the limit interval of the first bus voltage given value may be [360V, 523V], and the limit interval of the second bus voltage given value may be [420V, 530V].

[0048] The working mode may be a preset working mode, and the power conversion device 10 may switch to the corresponding working mode when receiving the control instruction. In some embodiments, the control instruction may be sent to the power conversion device 10 by the host computer of the power conversion device 10 or the energy storage device where the battery module 20 is located through wireless communication or wired communication (such as CAN communication). For example, the host computer may be a control device or server that communicates with the power conversion device 10 by wire, or a mobile communication device or cloud server that communicates with the power conversion device 10 wirelessly. In other embodiments, a physical start button or a touch screen may be set on the power conversion device 10, and the power conversion device 10 may be switched to the corresponding working mode by pressing the physical start button or sending the corresponding control instruction on the touch screen. In other embodiments, the EMS may also be preset with a preset switching condition, and when the EMS confirms that the preset switching condition is met, it switches to the corresponding working mode. This application does not limit the sending method or generation method of the control instruction. In the implementation of the present application, the current working mode of the power conversion device 10 may be determined according to the needs of the user, the power generation information of the renewable DC power supply 50, the weather information and other relevant information.

[0049] Understandably, different working modes have different energy transmission paths to meet different needs. In order to stabilize the DC bus voltage of the power conversion device 10, the EMS needs to make each circuit connected to the DC bus reach a power balance state (that is, each circuit connected to the DC bus can reach a power supply and demand balance state) under the energy transmission path corresponding to each working mode to stabilize the bus voltage. In particular, when the energy input from the renewable DC power supply 50 to the power conversion device 10 is small or even non-existent, since the bidirectional DC / AC conversion circuit 110 and the bidirectional DC / DC conversion circuit 120 are both bidirectional conversion circuits, it is necessary to determine the magnitude relationship between the first bus voltage given value and the second bus voltage given value according to the current working mode of the power conversion device 10, so that when the bidirectional DC / AC conversion circuit 110 is controlled to work according to the first bus voltage given value, and the bidirectional DC / DC conversion circuit 120 is controlled to work according to the second bus voltage given value, the energy transmission path on the DC bus conforms to the corresponding working mode and reaches a power balance state. Please continue to understand the specific working principle in conjunction with the remaining steps below.

[0050] Step S202: Acquire the actual bus voltage of the DC bus and the battery voltage of the battery module.

[0051] The actual bus voltage may be a sampled voltage value across the first capacitor C1. In some embodiments, the voltage value across the first capacitor C1 may be obtained as the actual bus voltage by a voltage sampling circuit or a voltage sensor. Understandably, each circuit connected to the DC bus may affect the actual bus voltage. For example, in the present application, the bidirectional DC / AC conversion circuit 110, the bidirectional DC / DC conversion circuit 120, and the first DC / DC conversion circuit may all affect the actual bus voltage.

[0052] In some embodiments, the total voltage of the battery ports in the battery module 20 can be obtained as the battery voltage through a voltage sampling circuit or a voltage sensor. In other embodiments, the battery voltage of the battery module 20 can also be obtained by communicating with the battery management system (BMS) in the battery module 20 through the EMS.

[0053] This application does not limit the specific method of obtaining the actual bus voltage and battery voltage in step S202.

[0054] Step S203: Generate a first drive signal according to the actual bus voltage and the first bus voltage given value to control the bidirectional DC / AC conversion circuit.

[0055] The first bus voltage given value is used to characterize the ideal voltage value of the DC terminal of the bidirectional DC / AC conversion circuit 110. Understandably, in step S203, the voltage deviation between the first bus voltage given value and the actual bus voltage can be obtained, and then based on the relationship between the current, voltage and power, the electrical parameters such as the current, voltage or power on the bidirectional DC / AC conversion circuit 110 are determined according to the voltage deviation, and then the first driving signal is generated according to the corresponding electrical parameters, so that the actual bus voltage is close to the first bus voltage given value.

[0056] The first driving signal may be a driving signal for driving the switch tube on the bidirectional DC / AC conversion circuit 110, for example, a PWM (Pulse Width Modulation) signal for driving the switch tube in the bidirectional DC / AC conversion circuit 110. It can be understood that the first driving signal can control the voltage at the DC end of the bidirectional DC / AC conversion circuit 110, that is, the first driving signal can control the bidirectional DC / AC conversion circuit 110 to work in the rectification mode or the inverter mode, and control the voltage at its DC end.

[0057] In step S203, based on the first preset loop control model, a first drive signal can be generated according to the first bus voltage set value and the actual bus voltage to control the voltage at the DC end of the bidirectional DC / AC conversion circuit 110, so that the DC end voltage of the bidirectional DC / AC conversion circuit 110 approaches the first bus voltage set value. In some embodiments, the first preset control loop model may include a feedback control loop (e.g., at least one of a voltage loop, a current loop, a power loop, etc.) and / or a feedforward control loop, etc.

[0058] Step S204: Generate a second drive signal according to the battery voltage, the actual bus voltage and the second bus voltage given value to control the bidirectional DC / DC conversion circuit.

[0059] The second bus voltage given value is used to represent the ideal bus voltage value of the second end (i.e., the end connected to the DC bus) of the bidirectional DC / DC conversion circuit 120. Similarly, in step S204, a second driving signal can be generated according to the voltage deviation between the second bus voltage given value and the actual bus voltage, so that the actual bus voltage is close to the second bus voltage given value.

[0060] Understandably, the bidirectional DC / DC conversion circuit 120 is used to obtain DC power from the DC bus to charge the battery module 20; or to control the discharge of the battery module 20 to output DC power to the DC bus. However, due to the risks of battery overvoltage, battery undervoltage and overcurrent that may exist in the battery module 20, in step S204, in addition to controlling the bidirectional DC / DC conversion circuit 120 according to the two parameters of the actual bus voltage and the second bus voltage given value, it is also necessary to add the battery voltage parameter to realize the control of the bidirectional DC / DC conversion circuit 120, so as to achieve more precise control while reducing the safety risk of the power conversion device 10.

[0061] The second driving signal may be a driving signal for driving the switch tube on the bidirectional DC / DC conversion circuit 120, for example, a PWM (Pulse Width Modulation) signal for driving the switch tube in the bidirectional DC / DC conversion circuit 120. Understandably, the second driving signal may control the voltage at the second end of the bidirectional DC / DC conversion circuit 120, that is, the first driving signal may control the bidirectional DC / DC conversion circuit 120 to operate in the charging mode or the discharging mode, and control the voltage at the second end thereof.

[0062] In step S204, based on the second preset loop control model, a second drive signal can be generated according to the battery voltage, the actual bus voltage and the second bus voltage given value to control the voltage of the second end of the bidirectional DC / DC conversion circuit 120, so that the voltage of the second end of the bidirectional DC / DC conversion circuit 120 approaches the second bus voltage given value. In some embodiments, the second preset control loop model may also include a feedback control loop (for example, at least one of a voltage loop, a current loop, a power loop, etc.) and / or a feedforward control loop, etc. In other embodiments, other loop control models may also be used, and the present application does not limit the loop control model included in the second preset control loop model.

[0063] In this way, after executing the above steps S201 to S204, the voltage at the DC end of the bidirectional DC / AC conversion circuit 110 always approaches the first bus voltage given value, and the voltage at the second end of the bidirectional DC / DC conversion circuit 120 always approaches the second bus voltage given value.

[0064] Since the conversion voltage threshold is greater than the first bus voltage given value and greater than the second bus voltage given value, when the energy output by the renewable DC power source 50 is large enough, the actual bus voltage can be greater than the first bus voltage given value and the second bus voltage given value, for example, maintained at the conversion voltage threshold. At this time, regardless of the magnitude relationship between the first bus voltage given value and the second bus voltage given value, the bidirectional DC / AC conversion circuit 110 and the bidirectional DC / DC conversion circuit 120 can obtain electrical energy from the DC bus, so that each circuit connected to the DC bus reaches a power balance state, and the DC bus voltage can be stabilized.

[0065] When the energy output by the renewable DC power source 50 is small or even zero, and the actual bus voltage is pulled down to between the first bus voltage given value and the second bus voltage given value, since the voltage at the DC end of the bidirectional DC / AC conversion circuit 110 tends to approach the first bus voltage given value, the voltage at the second end of the bidirectional DC / DC conversion circuit 120 tends to approach the second bus voltage given value. In this way, based on the magnitude relationship between the first bus voltage given value and the second bus voltage given value, the bidirectional DC / AC conversion circuit 110 and the bidirectional DC / DC conversion circuit 120 can be mutually clamped.

[0066] For example, when the first bus voltage given value is greater than the second bus voltage given value, the bidirectional DC / AC conversion circuit 110 will pull up the actual bus voltage when it is running, and the bidirectional DC / DC conversion circuit 120 will pull down the actual bus voltage when it is running. In this way, by periodically executing the above steps S201 to S204, the bidirectional DC / AC conversion circuit 110 and the bidirectional DC / DC conversion circuit 120 are mutually clamped, so that the first DC / DC conversion circuit 130 outputs direct current to the DC bus, the bidirectional DC / AC conversion circuit 110 takes power from the AC end and rectifies it into direct current and outputs it to the DC bus, and the bidirectional DC / DC conversion circuit 120 obtains direct current from the DC bus to charge the battery module 20. The energy transmission path is achieved, and the power supply and demand are balanced, so that the voltage on the DC bus is in a relatively stable state. For another example, when the first bus voltage given value is less than the second bus voltage given value, the bidirectional DC / AC conversion circuit 110 will pull down the actual bus voltage when it is running, and the bidirectional DC / DC conversion circuit 120 will pull up the actual bus voltage when it is running. In this way, by periodically executing the above steps S201 to S204, the bidirectional DC / AC conversion circuit 110 and the bidirectional DC / DC conversion circuit 120 are mutually clamped, so that the first DC / DC conversion circuit 130 outputs direct current to the DC bus, the bidirectional DC / DC conversion circuit 120 controls the battery module 20 to discharge to output direct current to the DC bus, and the bidirectional DC / AC conversion circuit 110 draws power from the DC bus and inverts it into alternating current through the AC end to output the energy transmission path, and reaches a state of power supply and demand balance, so that the voltage on the DC bus is in a relatively stable state.

[0067] In summary, the control method of the power conversion device provided by the present application first determines the magnitude relationship between the first bus voltage given value and the second bus voltage given value according to the current working mode of the power conversion device 10, and the first bus voltage given value and the second bus voltage given value are both less than the conversion voltage threshold. Among them, the first bus voltage given value is the voltage given value of the DC end of the bidirectional DC / AC conversion circuit 110, the second bus voltage given value is the voltage given value of the second end of the bidirectional DC / DC conversion circuit 120, and the conversion voltage threshold is the voltage given value of the second end of the first DC / DC conversion circuit 130. Then, the actual bus voltage of the DC bus and the battery voltage of the battery module 20 are obtained, and a first drive signal is generated according to the actual bus voltage and the first bus voltage given value to control the bidirectional DC / AC conversion circuit 110, and a second drive signal is generated according to the battery voltage, the actual bus voltage and the second bus voltage given value to control the bidirectional DC / DC conversion circuit 120. In this embodiment, the voltage at the DC end of the bidirectional DC / AC conversion circuit 110 is always close to the first bus voltage given value, and the voltage at the second end of the bidirectional DC / DC conversion circuit 120 is always close to the second bus voltage given value. Even when the energy inputted into the power conversion device by the renewable DC power source 50 is small or even non-existent, and the actual bus voltage is pulled down to between the first bus voltage given value and the second bus voltage given value, based on the magnitude relationship between the first bus voltage given value and the second bus voltage given value, the bidirectional DC / AC conversion circuit 110 and the bidirectional DC / DC conversion circuit 120 can be mutually clamped, so as to form a corresponding energy path on the DC bus, and at the same time, each circuit connected to the DC bus finally reaches a power balance state, thereby achieving the effect of stabilizing the DC bus voltage.

[0068] Understandably, in some embodiments, the power conversion device 10 includes at least two controllers, such as a first microcontroller unit (MCU) and a second MCU (not shown in the figure). The first MCU is used to control the bidirectional DC / AC conversion circuit 110, and the second MCU is used to control the bidirectional DC / DC conversion circuit 120. The first MCU, the second MCU or other controllers in the power conversion device are loaded with EMS. EMS implements the control method of the power conversion device provided in the present application through information interaction with the first MCU and the second MCU, so as to coordinate the energy management and information interaction in the power conversion device 10.

[0069] For example, in step S201, the EMS configures the first bus voltage given value and the second bus voltage given value by sending a data packet to the first MCU and the second MCU. In some embodiments, the data packet may include the first bus voltage given value, the second bus voltage given value, the actual bus voltage and the battery voltage, so that the first MCU and the second MCU can respectively decode the received data packet to obtain the corresponding data. In other embodiments, the first MCU and the second MCU are both provided with a reference bus voltage given value. The data packet includes at least the actual bus voltage, the battery voltage and the flag data used to indicate the size relationship. For example, when the flag data is "0", it indicates that the corresponding bus voltage given value is greater than the reference bus voltage given value, and when the flag data is "1", it indicates that the corresponding bus voltage given value is less than the reference bus voltage given value. After the first MCU and the second MCU respectively decode the data packet to obtain the corresponding flag data, the corresponding first bus voltage given value and the second bus voltage given value can be determined according to the flag data, the reference bus voltage given value and the preset calculation rule.

[0070] Then, the first MCU executes step S203 according to the acquired actual bus voltage and the first voltage given value, thereby realizing control over the bidirectional DC / AC conversion circuit 110. The second MCU executes step S204 according to the acquired second bus voltage given value, the actual bus voltage and the battery voltage, thereby realizing control over the bidirectional DC / DC conversion circuit 120.

[0071] In some embodiments, the working modes of the power conversion device 10 include a backup power priority mode and a self-generation mode.

[0072] See also Figure 3 In some embodiments, the power conversion device 10 further includes a switch circuit, which includes a grid-connected relay (K11 / K12 / K31 / K32), an off-grid relay (K21 / K22), and a bypass relay (K41 / K42 / K51 / K52). A grid-connected relay is provided between the bidirectional DC / AC conversion circuit 110 and the power grid 30, an off-grid relay is provided between the bidirectional DC / AC conversion circuit 110 and the AC load 40, and a bypass relay is provided between the power grid 30 and the AC load 40.

[0073] When the power conversion device 10 is in the backup power priority mode, the off-grid relay is in the disconnected state. Figure 1 and Figure 3, when the power conversion device 10 is in the backup power priority mode, if the battery module 20 is not fully charged, the power conversion device 10 uses the power provided by the renewable DC power source 50 and / or the power grid 30 to charge the battery module 20 first, so that the battery module 20 is fully charged as soon as possible, and the grid-connected relay is in a closed state. In some embodiments, in the backup power priority mode, when the power conversion device 10 is connected to the AC load 40 and the AC load 40 has a power demand, the power conversion device 10 closes the bypass relay so that the power grid 30 supplies power to the AC load 40 through the bypass relay.

[0074] When the power conversion device 10 is in the self-generation and self-use mode, the grid-connected relay is in the disconnected state. Figure 1 and Figure 3 , when the power conversion device 10 is in the self-generation and self-use mode, if the AC load 40 has a power demand and the energy output by the renewable DC power supply 50 is large enough, the power conversion device 10 uses the power provided by the renewable DC power supply 50 to preferentially supply power to the AC load 40 by closing the off-grid relay, and charges the battery module 20 when there is excess power. If the energy output by the renewable DC power supply 50 is insufficient to meet the power demand of the AC load 40, the power conversion device 10 also uses the power provided by the battery module 20 to supply power to the AC load 40 through the off-grid relay. In the self-generation and self-use mode, the power conversion device 10 preferentially uses the power provided by the renewable DC power supply 50 and / or the battery module 20 to supply power to the AC load 40. In some embodiments, in the self-generation and self-use mode, if the power provided by the renewable DC power supply 50 and the battery module 20 together still cannot meet the demand of the load 40, the bypass relay is closed, and the load 40 is supplied with power by the renewable DC power supply 50, the battery module 20 and the power grid 30.

[0075] Thus, when the working mode of the power conversion device 10 includes the backup power priority mode and the self-generation and self-use mode, step S201 includes:

[0076] When the working mode is the backup power priority mode, the first bus voltage set value is greater than the second bus voltage set value;

[0077] When the working mode is the self-generation and self-use mode, the first bus voltage set value is less than the second bus voltage set value.

[0078] Among them, when the EMS confirms that the SOC of the battery module 20 is less than the first preset SOC (for example, 20%), it means that the battery module 20 needs to be charged immediately, and the EMS controls the current working mode of the power conversion device 10 to switch to the backup power priority mode. In some embodiments, when the EMS receives a first control instruction sent by the host computer or a terminal (that is, the APP end) configured with the corresponding APP (Application) and the battery module 20 is not fully charged (that is, the SOC of the battery module 20 is less than 100%), the EMS responds to the first control instruction to control the current working mode of the power conversion device 10 to switch to the backup power priority mode. In some embodiments, the APP end can send a first control instruction based on the information obtained. The information obtained includes but is not limited to weather information, power outage information, etc. For example, when the APP end confirms that a storm is about to or has arrived based on weather information, it means that the battery module 20 needs to be charged to prepare for bad weather in advance, and the APP end sends a first control instruction to the EMS. For another example, when the APP side confirms that there will be a power outage at night based on the acquired power outage information, indicating that the battery module 20 needs to be charged to prepare for evening power consumption, the APP side sends a first control instruction to the EMS.

[0079] Understandably, when the magnitude relationship is configured such that the first bus voltage given value is greater than the second bus voltage given value, and the energy output by the renewable DC power supply 50 is small or even nonexistent, for the bidirectional DC / AC conversion circuit 110, the bidirectional DC / DC conversion circuit 120 will pull down the actual bus voltage when it is running, so that the actual bus voltage is less than the first bus voltage given value. Therefore, the bidirectional DC / AC conversion circuit 110 is in a rectification mode, so that the AC power is obtained from the AC end and then rectified and then outputted to the DC bus, so that the voltage at its DC end is close to the first bus voltage given value. At the same time, for the bidirectional DC / DC conversion circuit 120, the bidirectional DC / AC conversion circuit 110 will pull up the actual bus voltage when it is running, so that the actual bus voltage is greater than the second bus voltage given value. Therefore, the bidirectional DC / DC conversion circuit 120 is in a charging mode, so that the electric energy is obtained from the DC bus to charge the battery module 20, so that the voltage at its second end is close to the second bus voltage given value. In this scenario, the power conversion device 10 uses the electric energy provided by the power grid 30 and the renewable DC power source 50 to charge the battery module 20, meeting the requirements of the backup power priority mode, and can make the DC bus eventually reach a power balance state, so that the actual bus voltage on the DC bus tends to be stable.

[0080] In some embodiments, the user may control the power conversion device 10 to switch to the self-generation mode through an external terminal or a button or interface on the power conversion device 10 .

[0081] Understandably, when the magnitude relationship is configured such that the first bus voltage given value is less than the second bus voltage given value, and the energy output by the renewable DC power supply 50 is small or even nonexistent, for the bidirectional DC / AC conversion circuit 110, the bidirectional DC / DC conversion circuit 120 will pull up the actual bus voltage when it is running, so that the actual bus voltage is greater than the first bus voltage given value. Therefore, the bidirectional DC / AC conversion circuit 110 is in the inverter mode, and the DC power is obtained from the DC bus at the DC end for inversion to output the AC voltage to the power grid 30, so that the voltage at its DC end is close to the first bus voltage given value. At the same time, for the bidirectional DC / DC conversion circuit 120, the bidirectional DC / AC conversion circuit 110 will pull down the voltage on the DC bus when it is running, so that the actual bus voltage is less than the second bus voltage given value. Therefore, the bidirectional DC / DC conversion circuit 120 is in the discharge mode, obtains electrical energy from the battery module 20 and outputs DC power to the DC bus, so that the voltage at its second end is close to the second bus voltage given value. In this scenario, the power conversion device 10 uses the electric energy output by the battery module 20 and the renewable DC power source 50 to power the AC load 40 without drawing electricity from the power grid 30, thereby meeting the requirements of the self-generation and self-use mode and allowing the DC bus to eventually reach a power balance state so that the voltage on the DC bus tends to stabilize.

[0082] It is understandable that the present application does not limit the working mode of the power conversion device 10. In other embodiments, the power conversion device 10 may also be in other working modes, and configure a corresponding size relationship for the first bus voltage set value and the second bus voltage set value according to the working mode.

[0083] See also Figure 4 In some embodiments, step S203 includes the following sub-steps:

[0084] Step S401: Obtain a first voltage deviation value between a first bus voltage set value and an actual bus voltage.

[0085] The first voltage deviation value is used to characterize the difference between the first bus voltage set value and the actual bus voltage.

[0086] Exemplarily, a difference value obtained by subtracting the actual bus voltage from the first bus voltage set value may be used as the first voltage deviation value.

[0087] Step S402: performing deviation adjustment on the first voltage deviation value to obtain a first reference current value.

[0088] In step S402, the first voltage deviation value is deviation-adjusted, that is, the first reference current value is obtained by deviation-adjusting the first bus voltage given value and the actual bus voltage at the current moment. The first reference current value represents the reference current value of the DC end of the corresponding bidirectional DC / AC conversion circuit 110 when the actual bus voltage at the next moment is adjusted to the first bus voltage given value.

[0089] It can be understood that the algorithm used for the deviation regulation mentioned in this article can be a PI regulation algorithm (proportional integral control), a PID regulation algorithm (Proportion Integration Differentiation control), etc., and of course it can also be other regulation algorithms.

[0090] Step S403: performing a limiting process on the first reference current value to obtain a first target current.

[0091] Among them, the limiting process can be to process the first reference current value according to the maximum current value and the minimum current value of the DC end of the bidirectional DC / AC conversion circuit 110 to obtain the first target current. For example, when the first reference current value is less than or equal to the maximum current value, and greater than or equal to the minimum current value, the first reference current value is determined to be the first target current; when the first reference current value is greater than the maximum current value, the maximum current value is determined to be the first target current; when the first reference current value is less than the minimum current value, the minimum current value is determined to be the first target current. In this way, the first target current obtained after the limiting process can meet the current requirements of the DC end of the bidirectional DC / AC conversion circuit 110, thereby improving the safety of the power conversion device 10.

[0092] The first target current can be used to adjust the voltage of the DC terminal of the bidirectional DC / AC conversion circuit 110. In this way, when the current of the DC terminal of the bidirectional DC / AC conversion circuit 110 at the next moment is the first target current, the actual bus voltage is close to the first bus voltage given value.

[0093] Step S404: generating a first driving signal according to the first target current.

[0094] Exemplarily, step S404 can calculate the first target duty cycle according to the first target current and output it to the PWM modulator (not shown in the figure). Then, the PWM modulator modulates the first drive signal including the first target duty cycle according to the first target duty cycle. In this way, based on the control of the switching logic of the switch tube in the bidirectional DC / AC conversion circuit 110 by the first drive signal, the actual bus voltage at the DC end of the bidirectional DC / AC conversion circuit 110 approaches or reaches the first bus voltage given value.

[0095] In other embodiments, step S404 may also include: determining a current deviation value according to the first target current and an actual bus current at the DC end of the bidirectional DC / AC conversion circuit 110, and then performing deviation adjustment on the current deviation value to obtain a driving signal.

[0096] In summary, by executing steps S401 to S404, the first drive signal can be determined according to the first bus voltage set value and the actual bus voltage, so that under the control of the first drive signal, the actual bus voltage at the DC end of the bidirectional DC / AC conversion circuit 110 is close to or reaches the first bus voltage set value.

[0097] In some embodiments, in order to facilitate the calculation of the actual grid-connected power between the power conversion device 10 and the power grid 40 and to more accurately realize the self-generation and self-use control, the direction of energy flow in the power conversion device 10 can also be specified. For example, it can be specified that: the current flows from the DC end to the AC end of the bidirectional DC / AC conversion circuit 110 as a positive direction. The current flows from the AC end to the DC end of the bidirectional DC / AC conversion circuit 110 as a negative direction. The current flows from the second end to the first end of the bidirectional DC / DC conversion circuit 120 as a negative direction. The current flows from the first end to the second end of the bidirectional DC / DC conversion circuit 120 as a positive direction.

[0098] When the first bus voltage given value is greater than the actual bus voltage, the bidirectional DC / AC conversion circuit 110 can rectify the AC power provided by the power grid 30 to output DC power to the DC bus, so that the actual bus voltage increases to approach or reach the first bus voltage given value, at this time, the current direction of the DC end of the bidirectional DC / AC conversion circuit 110 is negative. When the first bus voltage given value is less than the actual bus voltage, the bidirectional DC / AC conversion circuit 110 inverts the DC power on the DC bus to output AC power, so that the actual bus voltage decreases to approach or reach the first bus voltage given value, at this time, the current direction of the DC end of the bidirectional DC / AC conversion circuit 110 is positive. Since the first bus voltage given value minus the actual bus voltage can obtain the first voltage deviation value, the first voltage deviation value can obtain the first reference current value after deviation adjustment, therefore, the first reference current value also needs to be updated so that the direction of the updated first reference current value conforms to the above-mentioned specified direction.

[0099] In some embodiments, before executing step S403, the control method further includes:

[0100] The first reference current value is inverted to update the first reference current value.

[0101] Exemplarily, inverting the first reference current value to update the first reference current value includes: when the first reference current value is positive or negative, obtaining the opposite of the first reference current value as the updated first reference current value; when the first reference current value is 0, the first reference current value remains unchanged.

[0102] In this way, by updating the first reference current value through the inversion process, the direction of the updated first reference current value can be made to conform to the above-mentioned specified direction.

[0103] Furthermore, after the first reference current value is updated through the inversion process, step S403 to step S404 are continued to be executed, so that the energy flow direction of the bidirectional DC / AC conversion circuit 110 under the control of the first driving signal also complies with the above regulations.

[0104] In some embodiments, based on the above-specified direction, the maximum current value mentioned in step S403 may be the maximum current value of the DC end of the bidirectional DC / AC conversion circuit 110 when operating in the inverter mode; the minimum current value mentioned in step S403 may be the maximum current value of the DC end of the bidirectional DC / AC conversion circuit 110 when operating in the rectification mode, which is obtained by inverting the maximum current value.

[0105] It is understandable that the above-specified direction is only one implementation of the present application. In other embodiments, it can also be specified as follows: the current flows from the DC end of the bidirectional DC / AC conversion circuit 110 to the AC end as a negative direction. The current flows from the AC end of the bidirectional DC / AC conversion circuit 110 to the DC end as a positive direction. The current flows from the second end to the first end of the bidirectional DC / DC conversion circuit 120 as a positive direction. The current flows from the first end to the second end of the bidirectional DC / DC conversion circuit 120 as a negative direction. The present application does not limit this. For the convenience of description, in the following, the control method involved in the present application is introduced with the current flowing from the DC end of the bidirectional DC / AC conversion circuit 110 to the AC end as a positive direction.

[0106] It is understandable that when the current working mode of the power conversion device 10 is the backup power priority mode, since the first bus voltage set value is greater than the second bus voltage set value, the bidirectional DC / AC conversion circuit 110 is in the rectification mode, and the bidirectional DC / DC conversion circuit 120 is in the charging mode, and the power conversion device 10 at least obtains the energy of the power grid 30 to charge the battery module 30. When the bidirectional DC / AC conversion circuit 110 charges the battery module 30 to a full charge state, the current at the second end of the bidirectional DC / DC conversion circuit 120 will be adjusted to 0 under the control of the second drive signal, so that the energy of the DC bus no longer flows to the battery module 30 through the bidirectional DC / DC conversion circuit 120. Ideally, the current at the DC end of the bidirectional DC / AC conversion circuit 110 also needs to be greater than or equal to 0 at this time, so that the bidirectional DC / AC conversion circuit 110 works in the inverter mode or stops working, thereby stopping the input current to the DC bus and avoiding overvoltage of the DC bus.

[0107] However, due to the different bandwidths of different control loops, the problem may arise that the control loop of the bidirectional DC / DC conversion circuit 120 is faster and the control loop of the bidirectional DC / AC conversion circuit 110 is slower. In this way, when the control loop of the bidirectional DC / DC conversion circuit 120 has adjusted the current at its second end to 0, the DC end of the bidirectional DC / AC conversion circuit 120 may still output current to the DC bus, thereby causing the bus voltage to continue to rise, resulting in bus overvoltage.

[0108] In order to solve the above problem, in some embodiments, before executing step S403, the control method further includes:

[0109] When the bidirectional DC / AC conversion circuit is in a rectification mode, the battery voltage is greater than or equal to the preset battery voltage and the first reference current value is greater than 0, the first reference current value is configured to be 0.

[0110] The preset battery voltage may be a battery voltage threshold when the battery module 20 is fully charged. When the battery voltage is greater than or equal to the preset battery voltage, it indicates that the battery module 20 is fully charged. For example, the preset battery voltage may be 830V.

[0111] From step S401 to step S402, it can be known that the first reference current value can actually be considered as the control loop integral value obtained based on the deviation between the first bus voltage given value and the actual bus voltage in step S401 to step S402. When the first reference current value is greater than 0, it means that the current first bus voltage given value is greater than the actual bus voltage. If the first reference current value is not configured to 0, then at the next moment, the bidirectional DC / AC conversion circuit 110 will continue to output current to the DC bus according to the first reference current value, so that the actual bus is over-voltage.

[0112] In the present embodiment, when the bidirectional DC / AC conversion circuit is in the rectification mode, the battery voltage is greater than or equal to the preset battery voltage and the first reference current value is greater than 0, the first reference current value is configured to be 0, that is, the control loop integral value is cleared, so that when continuing to execute steps S403 to S404, the bidirectional DC / AC conversion circuit 110 can stop outputting current to the DC bus at the next moment to prevent the DC bus from overvoltage.

[0113] It is understandable that in some embodiments, after executing step S402, the control method of the power conversion device further includes:

[0114] When the first integral clearing condition is not met, the first reference current value is inverted to update the first reference current value, wherein the first integral clearing condition includes: the bidirectional DC / AC conversion circuit is in rectification mode, the battery voltage is greater than or equal to the preset battery voltage and the first reference current value is greater than 0; the first reference current value is limited to obtain a first target current; and a first drive signal is generated according to the first target current.

[0115] In this way, by executing the control method of the power conversion device provided in this embodiment, the probability of DC bus overvoltage can be reduced when the working mode of the power conversion device 20 is the backup power priority mode and the battery module 20 is fully charged.

[0116] Understandably, when the current working mode of the power conversion device 10 is the self-generation and self-use mode, since the first bus voltage set value is less than the second bus voltage set value, the bidirectional DC / AC conversion circuit 110 is in the inverter mode, and the bidirectional DC / DC conversion circuit 120 is in the discharge mode, the power conversion device 10 supplies power to the AC load 40 through the bidirectional DC / AC conversion circuit 110. When the bidirectional DC / DC conversion circuit 120 suddenly fails and stops discharging to the DC bus, ideally, the bidirectional DC / AC conversion circuit 110 should also stop drawing power from the DC bus to reduce the risk of DC bus undervoltage.

[0117] However, due to the problem that the control loop of the bidirectional DC / DC conversion circuit 120 is faster and the control loop of the bidirectional DC / AC conversion circuit 110 is slower, when the control loop of the bidirectional DC / DC conversion circuit 120 has adjusted the current at its second end to 0, the DC end of the bidirectional DC / AC conversion circuit 120 may still obtain current from the DC bus, causing bus undervoltage.

[0118] In order to solve the above problem, in some embodiments, before executing step S403, the control method further includes:

[0119] When the bidirectional DC / AC conversion circuit is in the inverter mode, the actual bus voltage is less than the preset voltage threshold and the first reference current value is less than 0, the first reference current value is configured to be 0.

[0120] The preset voltage threshold may be a difference between the first bus voltage set value and the preset fluctuation value. For example, the preset fluctuation value may be 10V.

[0121] When the first reference current value is less than 0, it indicates that the current first bus voltage setting value is less than the actual bus voltage. If the first reference current value is not configured to 0, then at the next moment the bidirectional DC / AC conversion circuit 110 will obtain current from the DC bus according to the first reference current value to cause the bus to be undervoltage.

[0122] In the present embodiment, when the bidirectional DC / AC conversion circuit is in the inverter mode, the actual bus voltage is less than the preset voltage threshold and the first reference current value is less than 0, the first reference current value is configured to be 0, and the control loop integral value is cleared, so that when continuing to execute steps S303 to S304, the bidirectional DC / AC conversion circuit 110 can stop obtaining current from the DC bus at the next moment to prevent the DC bus from being under-voltage.

[0123] It is understandable that in some embodiments, after executing step S402, the control method of the power conversion device further includes:

[0124] When the second integral clearing condition is not met, the first reference current value is inverted to update the first reference current value, wherein the second integral clearing condition includes: the bidirectional DC / AC conversion circuit is in inverter mode, the actual bus voltage is less than the preset voltage threshold and the first reference current value is less than 0, and step S403 and step S404 are continued.

[0125] In this way, by executing the control method of the power conversion device provided in this embodiment, the probability of DC bus undervoltage can be reduced when the working mode of the power conversion device 20 is the self-generation mode and the bidirectional DC / DC conversion circuit 120 suddenly stops outputting current.

[0126] Please continue reading Figure 5 , Figure 5 This is a specific control block diagram for completely implementing the above steps S401 to S404 provided in an embodiment of the present application. Figure 5 The specific workflow is described.

[0127] First, the first adder 61 calculates the first voltage deviation value U_dev1 according to the first bus voltage given value U_ref1 and the actual bus voltage U_fdbk. The first PI regulator 62 performs deviation adjustment on the first voltage deviation value U_dev1 to obtain the first reference current value I_ref1. Then, the first inverter 63 inverts the first reference current value I_ref1 to obtain the updated first reference current value I_ref1*. Wherein, when the first integral clearing condition is met or the second integral clearing condition is met, the controller (for example, the first MCU) controls the first selector 64 through the first selection signal sel1 to obtain 0 as the updated first reference current value output to the first current limiter 65; otherwise, the controller controls the first selector 64 through the first selection signal sel1 to obtain the updated first reference current value I_ref1* output to the first current limiter 65. Then, the first current limiter 65 limits the input first reference current value (ie, I_ref1* or 0) according to the maximum current value Imax and the minimum current value -Imax to output the first target current I_aim1, so that the value of the first target current I_aim1 is between the maximum current value Imax and the minimum current value -Imax.

[0128] So, through Figure 5 The specific control block diagram provided can implement the specific control method in step S401 to step S404, and realize the control of the bidirectional DC / AC conversion circuit 110, so that for the bidirectional DC / AC conversion circuit 110, while realizing the actual bus voltage close to the first bus voltage given value, the probability of bus voltage overvoltage or undervoltage is reduced.

[0129] Understandably, the first PI regulator 62 mentioned above takes an existing controller in the related art, such as a PI controller (proportional integral controller) as an example. In other embodiments, other controllers such as a PID controller (proportional integral differential controller) and the like may also be used, and the present application does not limit this. Correspondingly, the deviation adjustment algorithm may also be a PI adjustment algorithm (proportional integral control, proportional integral adjustment), a PID adjustment algorithm (Proportion Integration Differentiation control, proportional integral differential adjustment), and the like, and of course, may also be other adjustment algorithms.

[0130] Understandably, Figure 5The control process of the control block diagram shown can be implemented by a computer program stored in the controller, and the specific implementation details are not repeated here.

[0131] In some embodiments, when the power conversion device 10 is in the backup power priority mode and the battery module 20 is fully charged, the second switching instruction can be triggered, so that the power conversion device 10 switches to the self-generation mode. In this way, the bidirectional DC / AC conversion circuit 110 switches from the rectification mode to the inverter mode, that is, the current at the DC end of the bidirectional DC / AC conversion circuit 110 switches from a negative value to a positive value. Please continue to refer to Figure 6 , Figure 6 (A) is a schematic diagram of the current at the DC end of the bidirectional DC / AC conversion circuit 110 when the power conversion device 10 switches from a backup power priority mode with the battery module 20 fully charged to a self-generation mode in an embodiment of the present application, without using the method of clearing the control loop integral value. Figure 6 (B) is a schematic diagram of the current at the DC end of the bidirectional DC / AC conversion circuit 110 when the power conversion device 10 switches from a backup power priority mode with the battery module 20 fully charged to a self-generation and self-use mode in an embodiment of the present application, using the method of clearing the control loop integral value.

[0132] Compare Figure 6 As can be seen from (A) and (B), Figure 6 When the battery module 20 is fully charged at time t1, the method of clearing the integral value of the control loop in the present application is not adopted, so the integral desaturation process still exists in the control loop during the time period t1-t2. During the desaturation process, the bidirectional DC / AC conversion circuit 110 still outputs current to the DC bus. Since the battery module 20 is fully charged at this time, there is a risk of DC bus overvoltage. Figure 6 In (B), after adopting the method for clearing the control loop integral value when the first clearing integral condition is met provided in the present application, when it is detected that the battery module 20 is fully charged, the current direction can be immediately changed by clearing the control loop integral value, so that the bidirectional DC / AC conversion circuit 110 stops outputting current to the DC bus.

[0133] Please continue reading Figure 7 , Figure 7 (A) is a schematic diagram of the current at the DC end of the bidirectional DC / AC conversion circuit 110 when the power conversion device 10 is in a self-generated and self-used mode and the bidirectional DC / DC conversion circuit 120 suddenly fails in an embodiment of the present application, and the method of clearing the control loop integral value is not adopted. Figure 7(B) is a schematic diagram of the current at the DC end of the bidirectional DC / AC conversion circuit 110 when the power conversion device 10 is in a self-generated and self-used mode and the bidirectional DC / DC conversion circuit 120 suddenly fails and the method of clearing the integral value of the control loop is adopted in one embodiment of the present application.

[0134] according to Figure 7 It can be seen that Figure 7 When the battery module 20 is fully charged at time t1, the integral desaturation process still exists in the control loop during the time period t1-t2 because the method of clearing the integral value of the control loop in the present application is not adopted. During the desaturation process, the bidirectional DC / AC conversion circuit 110 still obtains current from the DC bus, and there is a risk of DC bus undervoltage. Figure 7 In (B), after adopting the method for clearing the control loop integral value when the second clearing integral condition is met provided in the present application, when it is detected at t1 that the actual bus voltage is less than the preset voltage threshold, the control loop integral value is cleared to immediately change the current direction so that the bidirectional DC / AC conversion circuit 110 stops obtaining current from the DC bus.

[0135] See also Figure 8 In some embodiments, step S404 includes the following sub-steps:

[0136] Step S801: obtaining a second voltage deviation value between a third bus voltage given value and an actual bus voltage, wherein the third bus voltage given value is a bus voltage given value of a surplus power on-grid control loop of a bidirectional DC / AC conversion circuit.

[0137] Among them, the third bus voltage given value is less than the conversion voltage threshold, and the third bus voltage given value is greater than the first bus voltage given value and greater than the second bus voltage given value. In this way, it is ensured that the power on the DC bus first meets the power demand of the battery module 20 before being fed to the power grid 30 and / or supplying power to the AC load 40. The third bus voltage given value can be the sum of the output voltage peak of the renewable DC power supply 50 and the fourth preset value, and the conversion voltage threshold range is the fourth limit interval. The fourth preset value can be 35V, and the second limit interval can be [430V, 536V].

[0138] In some embodiments, the third bus voltage given value can be obtained according to the conversion voltage threshold and the reference voltage difference. For example, the difference obtained by subtracting the reference voltage difference from the first bus voltage given value can be used as the third bus voltage given value. The reference voltage difference can be 15V, for example. In other embodiments, the third bus voltage given value can also be calculated according to other methods, and the present application does not limit the specific values ​​of the third bus voltage given value and the reference voltage difference.

[0139] The surplus power on-grid control loop is used to output the excess power to the grid after the renewable DC power source 50 outputs enough energy so that the power on the DC bus meets the charging power demand of the battery module 20 and / or the power demand of the AC load 40. And the surplus power on-grid control loop can work when the power conversion device 10 is in the backup power priority mode and the self-generation and self-use mode. For example, when the power conversion device 10 is in the backup power priority mode, if the power output to the DC bus by the first DC / DC conversion circuit 130 is greater than the maximum charging power of the battery module 20 and the power demand of the AC load 40, the excess power can be fed to the grid 30 through the bidirectional DC / AC conversion circuit 110 under the control of the surplus power on-grid control loop. For another example, when the power conversion device 10 is in the self-generation and self-use mode, if the power output to the DC bus by the first DC / DC conversion circuit 130 is greater than the maximum charging power of the battery module 20 and the power demand of the AC load 40, the excess power can be fed to the grid 30 through the bidirectional DC / AC conversion circuit 110 under the control of the surplus power on-grid control loop.

[0140] The second voltage deviation value is used to characterize the gap between the third bus voltage set value and the actual bus voltage.

[0141] Exemplarily, a difference value obtained by subtracting the actual bus voltage from the third bus voltage set value may be used as the second voltage deviation value.

[0142] Step S802: performing deviation adjustment on the second voltage deviation value to obtain a reference power value.

[0143] The reference power value represents the power value of the AC end of the bidirectional DC / AC conversion circuit 110 when the actual bus voltage of the bidirectional DC / AC conversion circuit 110 at the next moment is adjusted to the third bus voltage given value. In step S802, the second voltage deviation value is deviation-adjusted, that is, the reference power value is obtained by deviation-adjusting according to the third bus voltage given value and the actual bus voltage at the current moment.

[0144] Step S803: obtaining feedback power at the AC end of the bidirectional DC / AC conversion circuit.

[0145] The feedback power refers to the actual output power of the AC end of the bidirectional DC / AC conversion circuit 110 .

[0146] In some embodiments, a power sensor, or other circuits or electronic devices capable of implementing power sampling, may be provided at the AC end of the bidirectional DC / AC conversion circuit 110 to periodically obtain feedback power.

[0147] Step S804: determining a second target current according to the reference power value and the feedback power.

[0148] In some embodiments, step S804 further includes the following sub-steps:

[0149] The reference power value is inverted to update the reference power value; the updated reference power value is limited to update the reference power value again; the power deviation value is determined according to the updated reference power value and the feedback power; the power deviation value is deviation-adjusted to determine the second target current.

[0150] The negation process includes: when the reference power value is a positive value or a negative value, obtaining the opposite of the reference power value as the first reference power value; when the reference power value is 0, obtaining 0 as the first reference power value. The first reference power value is the reference power value after the initial update. In this way, through the negation process, the result output by the residual power on-grid control loop can be made to conform to the energy flow direction specified above.

[0151] The limiting process includes: when the first reference power value is greater than or equal to 0, obtaining the first reference power value as the second reference power value; when the first reference power value is less than 0, obtaining 0 as the second reference power value. The second reference power value is a reference power value obtained after the reference power value after the initial update is updated again. In this way, it can be ensured that when the actual bus voltage is less than the third bus voltage given value, the surplus power on-grid control loop can limit the output power of the AC end of the bidirectional DC / AC conversion circuit 110 to 0.

[0152] Exemplarily, the difference between the second reference power value and the feedback power can be obtained as the power deviation value. And the power deviation value is deviation-adjusted, that is, the second target current is obtained by deviation adjustment according to the second reference power value and the feedback power. The second target current represents the reference current value of the DC end of the corresponding bidirectional DC / AC conversion circuit 110 when the feedback power is adjusted to the second reference power value at the next moment.

[0153] In some embodiments, the second target current is also limited to update the second target current. Specifically, the second target current is limited to: when the second target current is greater than or equal to 0, the second target current is used as the updated second target current; when the second target current is less than 0, 0 is used as the updated value of the second target current. In this way, it can be ensured that the second target current output by the surplus power on-grid control loop can make the bidirectional DC / AC conversion circuit 110 work in the inverter mode to output the excess power on the DC bus to the power grid 30 and / or power the AC load 40.

[0154] Step S805: obtaining the minimum value of the first target current and the second target current.

[0155] Step S806: generating a first driving signal according to the minimum value.

[0156] Since the first drive signal is used to control the current at the DC end of the bidirectional DC / AC conversion circuit 110, the minimum value of the first target current and the second target current is selected as the target output current value of the DC end of the bidirectional DC / AC conversion circuit 110. The bus voltage control loop and the surplus power online control loop can be weighed. While achieving bus voltage control of the bidirectional DC / AC conversion circuit 110, the surplus power online can be maximized, thereby improving the energy utilization efficiency of the renewable DC power supply 50 and the economic benefits of using the power conversion device 10.

[0157] In some embodiments, before executing step S804, the control method further includes:

[0158] When the backflow prevention mode is triggered, the reference power value is configured to be 0.

[0159] In this embodiment, when the power conversion device 10 operates in the anti-backflow mode, the external power source such as the power grid 30 is prohibited from being input from the AC end of the bidirectional DC / AC conversion circuit 110. Therefore, when the anti-backflow mode is triggered, the reference power value (i.e., the second reference power value) updated again in the configuration step S804 is 0.

[0160] In some embodiments, when the anti-backflow mode is triggered, the power conversion device 10 is prohibited from feeding power to the power grid 30 and / or supplying power to the AC load 40. In this way, the AC power of the power grid 30 can be prevented from being fed back to the power conversion device 10 to the greatest extent, thereby improving the safety of the power conversion device 10 during operation.

[0161] See also Fig. 9 In some embodiments, step S404 includes the following sub-steps:

[0162] Step S901: obtaining a third target current output by another control loop of the bidirectional DC / AC conversion circuit.

[0163] In some embodiments, other control loops of the bidirectional DC / AC conversion circuit 110 may include at least one of an active power limiting loop and a bidirectional DC / AC conversion circuit maximum output current loop. The active power limiting loop may control active power based on factors such as over-temperature detection, power factor curve, over-voltage detection, active power percentage, and over-current detection.

[0164] Accordingly, step S901 may include: obtaining a third target current output by at least one control loop of an active power limiting loop and a maximum output current loop of a bidirectional DC / AC conversion circuit.

[0165] Step S902: obtaining the minimum value of the first target current and each third target current.

[0166] Step S903: generating a first driving signal according to the minimum value.

[0167] In this way, the bus voltage control loop and other control loops of the bidirectional DC / AC conversion circuit 110 can be balanced, thereby preventing the related control loops of the bidirectional DC / AC conversion circuit 110 from overshooting.

[0168] In other embodiments, the minimum value among the first target current, the second target current and each third target current can also be obtained, and the first drive signal is generated according to the obtained minimum value. In this way, the bus voltage control loop, the surplus power access control loop and other control loops of the bidirectional DC / AC conversion circuit 110 can be weighed, which not only ensures the safety of the bidirectional DC / AC conversion circuit 110, but also maximizes the surplus power access to the grid and improves economic benefits.

[0169] In other embodiments, the first reference current value obtained in step S402 can be used to represent the reference current value of the AC end of the bidirectional DC / AC conversion circuit 110. At this time, the first target current obtained in step S403 is correspondingly used to make the current at the AC end of the bidirectional DC / AC conversion circuit 110 at the next moment be the first target current, so that the actual bus voltage is close to the first bus voltage given value; accordingly, the second target current represents the reference current value of the AC end of the corresponding bidirectional DC / AC conversion circuit 110 when the feedback power is adjusted to the second reference power value at the next moment; the third target current is also used to represent the reference current value of the AC end of the bidirectional DC / AC conversion circuit 110.

[0170] Please continue reading Fig.10 , Fig.10 FIG. 2 is a specific control block diagram of a control method (i.e., step S203) of a bidirectional DC / AC conversion circuit 110 in an embodiment of the present application. Fig.10 As shown, the control loop of the bidirectional DC / AC conversion circuit 110 includes a bus voltage control loop 60, a surplus power on-grid control loop 70, and an active power limiting loop 80. In this embodiment, the bus voltage control loop 60, the surplus power on-grid control loop 70, and the active power limiting loop 80 perform loop competition, and the minimum value of the target currents output by the three loops is used as the target output current value of the bidirectional DC / AC conversion circuit 110, so as to generate a first drive signal according to the target output current value finally determined.

[0171] Specifically, the bus voltage control loop 60 is used to control the voltage of the DC end of the bidirectional DC / AC conversion circuit 110 according to the actual bus voltage. Figure 5 The relevant description will not be repeated here.

[0172] The surplus power on-grid control loop 70 is used to control the output power of the AC end of the bidirectional DC / AC conversion circuit 110 according to the actual bus voltage. The control process is as follows:

[0173] The second adder 71 calculates the second voltage deviation value U_dev2 according to the third bus voltage given value U_ref3 and the actual bus voltage U_fdbk. The second PI regulator 72 performs deviation adjustment on the second voltage deviation value U_dev2 to obtain the reference power value P_ref1. Then, the second inverter 73 performs inversion processing on the reference power value P_ref1 to obtain the reference power value P_ref2 after the initial update. The power limiter 74 performs limiting processing on the reference power value P_ref2 after the initial update to obtain the reference power value P_ref3 after the re-update. Then, the controller (for example, the first MCU) controls the second selector 75 to select the re-updated reference power value P_ref3 or 0 as the output through the second selection signal sel2 according to whether the anti-backflow mode is triggered. Among them, when the anti-backflow mode is not triggered, the controller controls the second selector 75 through the second selection signal sel2 to select the reference power value P_ref3 updated again as the output; when the anti-backflow mode is triggered, the controller controls the second selector 75 through the second selection signal sel2 to select 0 as the output. Then, the third adder 76 calculates the power deviation value P_dev according to the output of the second selector 75 and the feedback power P_fdbk of the AC end of the bidirectional DC / AC conversion circuit 110. The third PI regulator 77 performs deviation adjustment on the power deviation value P_dev to obtain the second target current I_aimi. Finally, the second current limiter 78 performs a limiting process on the second target current I_aimi to output the updated second target current I_aim2.

[0174] The active power limiting loop 80 implements active power control of the bidirectional DC / AC conversion circuit 110 based on factors such as over-temperature detection, power factor curve, over-voltage and over-load detection, active power percentage, and over-current detection. The control process is as follows:

[0175] The power derating factor minimizer 86 obtains the power derating factors F1, F2, F3, F4 and F5 output by the derating factor calculation module 81 based on over-temperature detection, the derating factor calculation module 82 based on the power factor curve, the derating factor calculation module 83 based on overvoltage and overload detection, the derating factor calculation module 84 based on the active power percentage and the derating factor calculation module 85 based on overcurrent detection, and selects the minimum value among F1-F5 as the target power derating factor F_min. Among them, each power derating factor is greater than or equal to 0 and less than or equal to 1. And when the power derating factor is 0, it means that the power at the output end of the bidirectional DC / AC conversion circuit 110 is 0; when the power derating factor is 1, it means that the power at the output end of the bidirectional DC / AC conversion circuit 110 is the rated power. The target power derating factor F_min is used to indicate the target output power of the output end, for example, the product of the target power derating factor F_min and the rated power can be used as the target output power. The dq-axis power calculator 87 determines the target output power according to the received target power derating factor F_min, and calculates the d-axis current reference value as the third target current I_aim3 according to the detected d-axis voltage and q-axis voltage. In the inverter mode, the output end is the AC end of the bidirectional DC / AC conversion circuit 110; in the rectifier mode, the output end is the DC end of the bidirectional DC / AC conversion circuit 110.

[0176] Finally, the loop output minimizer 90 uses the minimum value of the first target current I_aim1, the second target current I_aim2 and the third target current I_aim3 outputted by the bus voltage control loop 60, the surplus power on-grid control loop 70 and the active power limiting loop 80 as the target current value I_aimf, that is, only one control loop of the bus voltage control loop 60, the surplus power on-grid control loop 70 and the active power limiting loop 80 is effective. In this way, the controller generates a first drive signal according to the target current value I_aimf, which can balance the control loops of the bidirectional DC / AC conversion circuit 110, so that the DC bus power is balanced while the surplus power on-grid control is realized, and the bidirectional DC / AC conversion circuit 110 is prevented from over-temperature, over-voltage, over-load or over-current, thereby improving the safety of the power conversion device 10.

[0177] In some embodiments, the execution cycles of the bus voltage control loop 60, the surplus power on-grid control loop 70, and the active power limiting loop 80 may be equal or unequal. For example, the execution cycle of the bus voltage control loop 60 is 50 microseconds (us), the execution cycle of the surplus power on-grid control loop 70 is 1 millisecond (ms), and the execution cycle of the active power limiting loop 80 is 5 milliseconds (ms). In addition, the bus voltage control loop 60, the surplus power on-grid control loop 70, and the active power limiting loop 80 may be controlled by controllers at different levels, respectively, to optimize the control level and save digital signal processing (DSP) chip resources in the power conversion device 10.

[0178] See also Fig.11 In some embodiments, the bidirectional DC / DC conversion circuit 120 includes a first switch tube Q1, a second switch tube Q2, a second capacitor C2 and an inductor L1. The first switch tube Q1 and the second switch tube Q2 are connected in series to the positive port VB+ and the negative port VB- of the battery module 20. The two ends of the second capacitor C2 are respectively connected to the positive port VB+ and the negative port VB-. One end of the inductor L1 is connected between the first switch tube Q1 and the second switch tube Q2, and the second end of the inductor L1 is connected to the positive DC bus BUS+. The first end of the first capacitor C1 is connected to the second end of the inductor L1. The second end of the first capacitor C1 is connected between the second switch tube Q2 and the negative port VB-. The second end of the first capacitor C1 is also connected to the negative DC bus BUS-. By controlling the working states of the first switch tube Q1 and the second switch tube Q2, the actual bus voltage on the DC bus is boosted to charge the battery module 20.

[0179] Please also read Fig.11 and Fig.12 In some embodiments, step S204 includes the following sub-steps:

[0180] Step S121: Obtain a third voltage deviation value between the second bus voltage set value and the actual bus voltage.

[0181] The actual bus voltage can be Fig.11 Exemplarily, the difference between the second bus voltage set value and the actual bus voltage can be used as the third voltage deviation value.

[0182] Step S122: performing deviation adjustment on the third voltage deviation value to obtain a compensation current value.

[0183] Similarly, the third voltage deviation value is subjected to deviation adjustment, that is, the compensation current value is obtained by deviation adjustment according to the second bus voltage given value and the actual bus voltage at the current moment. The compensation current value represents the current change amount of the second end of the corresponding bidirectional DC / DC conversion circuit 120 when the actual bus voltage at the next moment is adjusted to the second bus voltage given value.

[0184] In some embodiments, in order to avoid the problem of overshoot of the actual bus voltage caused by the compensation current value being too large or too small, the compensation current value can also be updated by limiting the current compensation value. For example, limiting the current compensation value may include: when the compensation current value is greater than or equal to the first limiting threshold, and the compensation current value is less than or equal to the second limiting threshold (the first limiting threshold is less than the second limiting threshold), obtaining the compensation current value as the updated compensation current value; when the compensation current value is less than the first limiting threshold, using the first limiting threshold as the updated compensation current value; when the compensation current value is greater than the second limiting threshold, using the second limiting threshold as the updated compensation current value.

[0185] Step S123: obtaining a feedback current at the second end of the bidirectional DC / DC conversion circuit.

[0186] In some embodiments, the current flowing from the second end of the inductor L1 to the positive DC bus BUS+ may be sampled by a current sampling circuit or a current sensor to serve as a feedback current.

[0187] Step S124: determining a second reference current value according to the compensation current value and the feedback current.

[0188] Exemplarily, the sum of the updated compensation current value and the feedback current may be used as the second reference current value.

[0189] Step S125: limiting the second reference current value according to the battery voltage to obtain a target charge and discharge current value.

[0190] It is understandable that the battery module 20 is limited to a maximum charging voltage and a minimum discharging voltage during charging and discharging to prevent damage to the battery module 20 and safety accidents. In this way, the deviation between the battery voltage and the corresponding charging and discharging voltage can be obtained, and the charge and discharge current limit threshold can be determined based on the deviation adjustment. Furthermore, in step S115, the second reference current value can be limited according to the charge and discharge current limit threshold obtained by the battery voltage to obtain the target charge and discharge current value, so that when the voltage at the second end of the bidirectional DC / DC conversion circuit 120 is controlled according to the target charge and discharge current value, safety can be taken into account.

[0191] Step S126: performing deviation adjustment based on the target charge and discharge current value to generate a second drive signal.

[0192] In some embodiments, step S116 may include:

[0193] Determine a current deviation value according to a target charge and discharge current value and an inductor current; perform deviation adjustment on the current deviation value to obtain a charge and discharge voltage compensation value; perform limiting processing on the charge and discharge voltage compensation value to update the charge and discharge voltage compensation value; determine a target DC bus voltage according to the charge and discharge voltage compensation value, the inductor voltage and the actual bus voltage; calculate a second target duty cycle according to the target DC bus voltage and the battery voltage; and generate a second drive signal according to the second target duty cycle.

[0194] Among them, the inductor current refers to the current flowing through Fig.11 The current of the inductor L1 in the circuit. For example, the difference between the target charge and discharge current value and the inductor current can be used as the current deviation value. The charge and discharge voltage compensation value is used to represent the corresponding actual bus voltage (i.e. Fig.11 The voltage change of the voltage across the first capacitor C1 in .

[0195] Understandably, in order to prevent overshoot, the charge and discharge voltage compensation value may be limited based on the voltage compensation upper limit value and the voltage compensation lower limit value. Specifically, the charge and discharge voltage compensation value may include: when the charge and discharge voltage compensation value is less than or equal to the voltage compensation upper limit value, and the charge and discharge voltage compensation value is greater than or equal to the voltage compensation lower limit value, the charge and discharge voltage compensation value is used as the updated charge and discharge voltage compensation value; when the charge and discharge voltage compensation value is greater than the voltage compensation upper limit value, the voltage compensation upper limit value is used as the updated charge and discharge voltage compensation value; when the charge and discharge voltage compensation value is less than the voltage compensation lower limit value, the voltage compensation lower limit value is used as the updated charge and discharge voltage compensation value.

[0196] For example, the sum of the charge-discharge voltage compensation value, the inductor voltage and the actual bus voltage can be used as the target DC bus voltage. The target DC bus voltage is used to represent the target value of the actual bus voltage.

[0197] For example, a value obtained by dividing the target DC bus voltage by the battery voltage may be used as the second target duty cycle. Furthermore, the controller may modulate a second drive signal including the second target duty cycle based on the PWM modulator.

[0198] In summary, by executing step S121 to step S126, the bidirectional DC / DC conversion circuit 120 can be controlled while taking into account the charge and discharge restrictions of the battery module 20, thereby ensuring the safety of charge and discharge.

[0199] See also Fig.13 In some embodiments, step S115 includes the following sub-steps:

[0200] Step S131: obtaining a first voltage difference between a lower limit value of a discharge voltage of a battery module and a battery voltage.

[0201] The lower limit of the discharge voltage may be a voltage threshold that triggers the over-discharge protection of the battery module 20; or the lower limit of the discharge voltage may be obtained by subtracting a preset value (e.g., 50V) from a given voltage at the first end of the bidirectional DC / DC conversion circuit 120. Exemplarily, the difference obtained by subtracting the battery voltage from the lower limit of the discharge voltage may be used as the first voltage difference.

[0202] Step S132: performing deviation adjustment on the first voltage difference to determine a first discharge current value.

[0203] In step S132, the first voltage difference is subjected to deviation adjustment, that is, a first discharge current value is obtained by deviation adjustment according to the discharge voltage lower limit value and the battery voltage at the current moment. The first discharge current value represents a reference current value of the first end of the corresponding bidirectional DC / DC conversion circuit 120 when the battery voltage at the next moment is adjusted to the discharge voltage lower limit value.

[0204] In step S132 , in order to make the first discharge current value conform to the energy flow direction specified above, the first discharge current value is further inverted to update the first discharge current value.

[0205] Step S133: selecting a minimum value between the first discharge current value and the preset discharge current value as the discharge current upper limit value, and both the first discharge current value and the preset discharge current value are greater than or equal to zero.

[0206] In this embodiment, in order to ensure that the first discharge current value is greater than or equal to 0 to comply with the energy flow direction specified above, the first discharge current value after the inversion process in step S132 may be limited to be updated again. In step S133, the limiting process includes: when the first discharge current value after the inversion process is less than or equal to 0, 0 is used as the first discharge current value after the update; when the first discharge current value after the inversion process is greater than 0, the first discharge current after the inversion process is used as the first discharge current value after the update.

[0207] The preset discharge current value may be a discharge current value corresponding to the discharge power of the second end of the bidirectional DC / DC conversion circuit 120 and sent by the EMS.

[0208] Step S134: obtaining a second voltage difference between the upper limit value of the charging voltage of the battery module and the battery voltage.

[0209] The upper limit value of the charging voltage may be a voltage threshold that triggers overcharge protection of the battery module 20; or the upper limit value of the charging voltage may be obtained by adding a preset value (e.g., 10V) to a given voltage at the first end of the bidirectional DC / DC conversion circuit 120. Exemplarily, the difference obtained by subtracting the battery voltage from the upper limit value of the charging voltage may be used as the second voltage difference.

[0210] Step S135: performing deviation adjustment on the second voltage difference to determine the first charging current value.

[0211] In step S135, the second voltage difference is subjected to deviation adjustment, that is, a first charging current value is obtained by deviation adjustment according to the charging voltage upper limit value and the battery voltage at the current moment. The first charging current value represents a reference current value of the first end of the corresponding bidirectional DC / DC conversion circuit 120 when the battery voltage at the next moment is adjusted to the charging voltage upper limit value.

[0212] In step S135 , in order to make the first charging current value conform to the energy flow direction specified above, the first charging current value is further inverted to update the first charging current value.

[0213] Step S136: selecting a maximum value between the first charging current value and the preset charging current value as the charging current lower limit, and both the first charging current value and the preset charging current value are smaller than 0.

[0214] In this embodiment, in order to ensure that the first charging current value is less than or equal to 0 to comply with the energy flow direction specified above, the first charging current value after the inversion process in step S135 may be limited to be updated again. In step S136, the limiting process includes: when the first charging current value after the inversion process is greater than or equal to 0, 0 is used as the first charging current value after the update; when the first discharge current value after the inversion process is less than 0, the first charging current after the inversion process is used as the first charging current value after the update.

[0215] The preset charging current value may be a charging current value corresponding to the charging power of the second end of the bidirectional DC / DC conversion circuit 120 and sent by the EMS.

[0216] Step S137: performing a limiting process on the second reference current value according to the upper limit value of the discharge current and the lower limit value of the charge current to obtain a target charge and discharge current value.

[0217] Exemplarily, step S137 may include: when the second reference current value is greater than or equal to the lower limit value of the charging current, and the second reference current value is less than or equal to the upper limit value of the discharging current, using the second reference current value as the target charging and discharging current value; when the second reference current value is less than the lower limit value of the charging current, using the lower limit value of the charging current as the target charging and discharging current value; when the second reference current value is greater than the upper limit value of the discharging current, using the upper limit value of the discharging current as the target charging and discharging current value.

[0218] In summary, by executing steps S131 to S137 , the second reference current value can be limited according to the battery voltage to obtain a target charge and discharge current value, thereby ensuring the safety of the bidirectional DC / DC conversion circuit 120 when charging and discharging the battery module 20 .

[0219] Please continue reading Fig.14 , Fig.14 FIG. 2 is a specific control block diagram of a control method (ie, step S204) of a bidirectional DC / DC conversion circuit 120 in an embodiment of the present application. Fig.14 As shown, the control loop of the bidirectional DC / DC converter circuit 120 includes a discharge current limiting loop 150, a charging current limiting loop 160 and a bus voltage limiting loop 170. In this embodiment, the discharge current upper limit value and the charging current lower limit value are determined by the discharge current limiting loop 150 and the charging current limiting loop 160, so as to limit the second reference current value in the bus voltage limiting loop 170 by the discharge current upper limit value and the charging current lower limit value to obtain the target charge and discharge current value, thereby generating a second drive signal according to the target charge and discharge current value finally determined. The control process is as follows:

[0220] Specifically, in the discharge current limiting loop 150, the fourth adder 151 calculates the first voltage difference U_dev_d according to the discharge voltage lower limit U_ref_disc and the battery voltage U_bat. The fourth PI regulator 152 performs deviation adjustment on the first voltage difference U_dev_d to obtain the first discharge current value I_ref_d1. Then, the third inverter 153 performs inversion processing on the first discharge current value I_ref_d1 to obtain the first discharge current value I_ref_d2 after the initial update. The third current limiter 154 performs limiting processing on the first discharge current value I_ref_d2 after the initial update to obtain the first discharge current value I_ref_d3 after the re-update. Then, the current minimizer 155 selects the minimum value between the first discharge current value I_ref_d3 after the re-update and the preset discharge current value I_limit_trig as the discharge current upper limit value I_limit_d.

[0221] In the charging current limiting loop 160, the fifth adder 161 calculates the second voltage difference U_dev_c according to the charging voltage upper limit value U_ref_cha and the battery voltage U_bat. The fifth PI regulator 162 performs deviation adjustment on the second voltage difference U_dev_c to obtain the first charging current value I_ref_c1. Then, the fourth inverter 163 performs inversion processing on the first charging current value I_ref_c1 to obtain the first charging current value I_ref_c2 after the initial update. The fourth current limiter 164 performs limiting processing on the first charging current value I_ref_c2 after the initial update to obtain the first charging current value I_ref_c3 after the re-update. Then, the current maximizer 165 selects the maximum value between the first charging current value I_ref_c3 after the re-update and the preset charging current value -I_limit_trig as the charging current lower limit I_limit_c.

[0222] In the bus voltage limiting loop 170, the sixth adder 171 calculates the third voltage deviation value U_dev3 based on the second bus voltage given value U_ref2 and the actual bus voltage U_fdbk. The sixth PI regulator 172 performs deviation adjustment on the third voltage deviation value U_dev3 to obtain the compensation current value I_com1. The fifth current limiter 173 performs a limiting process on the compensation current value I_com1 according to the first limiting threshold -IL_limit_1 and the second limiting threshold +IL_limit_1 to obtain the updated compensation current value I_com2. Then, the seventh adder 174 calculates the second reference current value I_giv1 based on the updated compensation current value I_com2 and the feedback current I_out. Then, the sixth current limiter 175 performs a limiting process on the second reference current value I_giv1 according to the discharge current upper limit value I_limit_d and the charging current lower limit value I_limit_c to obtain the target charge and discharge current value I_trig. The eighth adder 176 calculates the current deviation value I_dev according to the target charge and discharge current value I_trig and the inductor current I_Lcurr. Then, the seventh PI regulator 177 performs deviation adjustment on the current deviation value I_dev to obtain the charge and discharge voltage compensation value U_com1. The voltage limiter 178 performs a limiting process on the charge and discharge voltage compensation value U_com1 according to the voltage compensation upper limit value limit_U and the voltage compensation lower limit value -limit_U to obtain the updated charge and discharge voltage compensation value U_com2. The ninth adder 179 calculates the target DC bus voltage U_aim according to the updated charge and discharge voltage compensation value U_com2, the inductor voltage Ldi / dt and the actual bus voltage Vout. Then, the multiplier 180 calculates the second target duty cycle duty according to the target DC bus voltage U_aim and the inverse of the battery voltage 1 / U_bat. The PWM modulator 181 generates a second drive signal according to the second target duty cycle duty.

[0223] It is understandable that in other embodiments, other control loops may also be used to implement the control method described in step S204.

[0224] Please refer again Figure 1, the following takes the renewable DC power source 50 as an example of a photovoltaic component to introduce the working process of the power conversion device 10 in the backup power priority mode and the self-generation and self-use mode. Specifically, when the power conversion device 10 is in the backup power priority mode: when the energy of the photovoltaic component is large enough, the actual bus voltage on the DC bus can be maintained at a voltage equal to the conversion voltage threshold (for example, the photovoltaic voltage of the photovoltaic component plus 45V). At this time, since the first bus voltage set value and the second bus voltage set value are both less than the conversion voltage threshold, the bidirectional DC / AC conversion circuit 110 and the bidirectional DC / DC conversion circuit 120 both obtain energy from the DC bus. When the photovoltaic component outputs energy at its maximum capacity, but the energy is still insufficient to maintain the actual bus voltage at the conversion voltage threshold, if the actual bus voltage drops to less than the first bus voltage set value, since the second bus voltage set value is less than the first bus voltage set value at this time, the output of the surplus power online control loop is limited to 0, and the bidirectional DC / AC conversion circuit 110 obtains electric energy from the power grid 30 to charge the battery module 20. If the photovoltaic assembly cannot output energy, the bidirectional DC / AC conversion circuit 110 only obtains electrical energy from the power grid 30 to charge the battery module 20 until the battery module 20 is fully charged.

[0225] When the power conversion device 10 is in the self-generation and self-use mode: when the energy of the photovoltaic component is large enough, the bidirectional DC / AC conversion circuit 110 and the bidirectional DC / DC conversion circuit 120 both obtain energy from the DC bus. When the photovoltaic component outputs energy at its maximum capacity, but the energy is still insufficient to maintain the actual bus voltage at the conversion voltage threshold, if the energy of the battery module 20 is sufficient, the actual bus voltage is maintained at the second bus voltage given value by the bidirectional DC / DC conversion circuit 120 (and the second bus voltage given value is greater than the first bus voltage given value at this time), and the bidirectional DC / AC conversion circuit 110 obtains energy from the DC bus to power the AC load 40. If the energy of both the photovoltaic component and the battery module 20 is insufficient, that is, the battery module 20 is unable to maintain the DC bus voltage at the second bus voltage given value at this time, the actual bus voltage is maintained at the first bus voltage given value by the bidirectional DC / AC conversion circuit 110. If the SOC (State of Charge) of the battery module 20 drops to a preset SOC (e.g., 10%), the battery module 20 stops outputting energy to the DC bus and waits for the renewable DC power source 50 to replenish power. At this time, if the connected AC load 40 has power demand, the AC load 40 draws power from the grid 30 through the bypass relay.

[0226] Among them, no matter the power conversion device 10 is in the backup power priority mode or the self-generation mode, when the energy output by the photovoltaic module is large enough and the power conversion device 10 is allowed to feed power to the power grid 30, if the actual bus voltage is less than the third bus voltage given value, the output of the surplus power on-grid control loop is limited to 0. If the actual bus voltage is greater than or equal to the third bus voltage given value, the output of the surplus power on-grid control loop is positive, and integration begins to increase the surplus power on-grid power, that is, the output power of the AC end of the bidirectional DC / AC conversion circuit 110 is increased. If the actual bus voltage begins to fall back to the third bus voltage given value due to the increase in the surplus power on-grid power, although the reference power value after the inversion processing in the surplus power on-grid control loop is a negative value at this time, due to the action of the integrator, the output of the surplus power on-grid control loop will still remain positive, but it will be reduced, and the surplus power on-grid power will begin to decrease. After repeated adjustments, the actual bus voltage will finally stabilize at the second bus voltage given value, and the surplus power on-grid power will also converge to the current maximum surplus power on-grid power. If the sunlight becomes stronger and the energy output by the photovoltaic module makes the actual bus voltage maintain at the conversion voltage threshold, the reference power value after the inversion processing in the surplus power on-grid control loop is a positive value, so that the surplus power on-grid power continues to increase, and finally converges to the third bus voltage given value. If the sunlight becomes weaker, so that the actual bus voltage stabilizes at the second bus voltage given value, the reference power value after the inversion processing in the surplus power on-grid control loop is a negative value, so that the surplus power on-grid power decreases, the actual bus voltage rises, and finally converges back to the third bus voltage given value.

[0227] See also Fig.15 The present application also provides a power conversion device 10, including a bidirectional DC / DC conversion circuit 110, a bidirectional DC / AC conversion circuit 120, a first DC / DC conversion circuit 130, a DC bus and a control circuit 140. The first end of the bidirectional DC / DC conversion circuit 120 is used to connect to the battery module 130, and the first end of the first DC / DC conversion circuit 120 is used to connect to the renewable DC power supply 50; the second end of the bidirectional DC / DC conversion circuit 120, the second end of the first DC / DC conversion circuit 130 and the DC end of the bidirectional DC / AC conversion circuit 130 are all connected to the DC bus, and the AC end of the bidirectional DC / AC conversion circuit 110 is connected to the power grid 30 and / or the AC load 40 through the AC bus; the first DC / DC conversion circuit 130 is used to convert the voltage input by the renewable DC power supply 50 and output the voltage to the DC bus according to the conversion voltage threshold. The control circuit 140 is used to execute the control method of the power conversion device described in any of the above embodiments.

[0228] In some embodiments, the control circuit 140 includes at least two controllers, such as a first microcontroller unit (MCU) and a second MCU (not shown in the figure). The first MCU is used to control the bidirectional DC / AC conversion circuit 110, and the second MCU is used to control the bidirectional DC / DC conversion circuit 120. The first MCU, the second MCU or other controllers in the power conversion device 10 are loaded with EMS. EMS implements the control method of the power conversion device provided in the present application through information interaction with the first MCU and the second MCU to coordinate the energy management and information interaction in the power conversion device 10.

[0229] See also Fig.16 , the present application also provides an energy storage device 100. The energy storage device 100 includes a bidirectional DC / DC conversion circuit 110, a bidirectional DC / AC conversion circuit 120, a first DC / DC conversion circuit 130, a DC bus, a control circuit 140 and a battery module 20. The first end of the bidirectional DC / DC conversion circuit 120 is used to connect the battery module 130, and the first end of the first DC / DC conversion circuit 120 is used to connect the renewable DC power supply 50; the second end of the bidirectional DC / DC conversion circuit 120, the second end of the first DC / DC conversion circuit 130 and the DC end of the bidirectional DC / AC conversion circuit 130 are all connected to the DC bus, and the AC end of the bidirectional DC / AC conversion circuit 110 is connected to the power grid 30 and / or the AC load 40 through the AC bus; the first DC / DC conversion circuit 130 is used to convert the voltage input by the renewable DC power supply 50 and output the voltage to the DC bus according to the conversion voltage threshold. The control circuit 140 is used to execute the control method of the power conversion device described in any of the above embodiments.

[0230] It is understandable that the energy storage device 100 can be various electronic devices equipped with a battery module 20, such as a mobile energy storage device, a household energy storage device, a mobile air conditioner, a mobile refrigerator, etc., or it can be a separately provided battery pack, etc. The present application does not limit the specific device type of the energy storage device 100.

[0231] It is understandable that the control circuit 140 may be a circuit independent of the bidirectional DC / DC conversion circuit 110, the bidirectional DC / AC conversion circuit 120, and the first DC / DC conversion circuit 130, and the control circuit 140 may also be a processing circuit disposed in the power conversion device 10 or the energy storage device 100. The present application does not limit the specific form of the control circuit 140.

[0232] An embodiment of the present application further provides a control device, which is applied to the power conversion device 10 or an electronic device integrated with the power conversion device 10 . Fig.17The structure block diagram of the control device 200 provided in the embodiment of the present application is schematically shown. Fig.17 As shown, the control device 200 includes:

[0233] The determination module 210 is used to determine the magnitude relationship between the first bus voltage given value and the second bus voltage given value according to the current working mode of the power conversion device.

[0234] The acquisition module 220 is used to acquire the actual bus voltage of the DC bus and the battery voltage of the battery module.

[0235] The first control module 230 is used to generate a first drive signal according to the actual bus voltage and the first bus voltage given value to control the bidirectional DC / AC conversion circuit.

[0236] The second control module 240 is used to generate a second drive signal according to the battery voltage, the actual bus voltage and the second bus voltage given value to control the bidirectional DC / DC conversion circuit.

[0237] The specific details of the control method for implementing the power conversion device by the control device 200 provided in the embodiment of the present application have been described in detail in the embodiment of the control method of the corresponding power conversion circuit, and will not be repeated here.

[0238] The present application also provides a computer-readable storage medium 300 on which a computer program 310 is stored, and when the computer program 310 is executed by a processor, a control method for a power conversion device as in the above technical solution is implemented. The computer-readable medium can be a portable compact disk read-only memory (CD-ROM) and include program code, and can be run on a terminal device, such as a personal computer. However, the program product of the present invention is not limited to this. In this document, the readable storage medium can be any tangible medium containing or storing a program, which can be used by or in combination with an instruction execution system, an apparatus or a device.

[0239] In addition, the above-mentioned figures are only schematic illustrations of the processes included in the method according to an exemplary embodiment of the present invention, and are not intended to be limiting. It is easy to understand that the processes shown in the above-mentioned figures do not indicate or limit the time sequence of these processes. In addition, it is also easy to understand that these processes can be performed synchronously or asynchronously, for example, in multiple modules.

[0240] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A control method for a power conversion device, characterized in that: The power conversion device comprises a bidirectional DC / DC conversion circuit, a bidirectional DC / AC conversion circuit, a first DC / DC conversion circuit and a DC bus, wherein the first end of the bidirectional DC / DC conversion circuit is used to connect to a battery module, and the first end of the first DC / DC conversion circuit is used to connect to a renewable DC power supply; the second end of the bidirectional DC / DC conversion circuit, the second end of the first DC / DC conversion circuit and the DC end of the bidirectional DC / AC conversion circuit are all connected to the DC bus, and the AC end of the bidirectional DC / AC conversion circuit is connected to a power grid and / or an AC load through the AC bus; the first DC / DC conversion circuit is used to convert the voltage input by the renewable DC power supply and output a voltage to the DC bus according to a conversion voltage threshold; the method comprises: Determine, according to the current working mode of the power conversion device, a magnitude relationship between a first bus voltage given value and a second bus voltage given value, wherein the first bus voltage given value is a voltage given value of a DC terminal of the bidirectional DC / AC conversion circuit, the second bus voltage given value is a voltage given value of a second terminal of the bidirectional DC / DC conversion circuit, the first bus voltage given value is not equal to the second bus voltage given value, and the first bus voltage given value and the second bus voltage given value are both less than the conversion voltage threshold; Acquiring an actual bus voltage of the DC bus and a battery voltage of the battery module; generating a first drive signal according to the actual bus voltage and the first bus voltage given value to control the bidirectional DC / AC conversion circuit; A second drive signal is generated according to the battery voltage, the actual bus voltage and the second bus voltage given value to control the bidirectional DC / DC conversion circuit.

2. The method according to claim 1, characterized in that Determining the magnitude relationship between the first bus voltage given value and the second bus voltage given value according to the current working mode of the power conversion device includes: When the working mode is the backup power priority mode, the first bus voltage given value is greater than the second bus voltage given value; When the working mode is the self-generation and self-use mode, the first bus voltage given value is less than the second bus voltage given value.

3. The method according to claim 1, characterized in that The generating a first drive signal according to the actual bus voltage and the first bus voltage given value comprises: Obtaining a first voltage deviation value between the first bus voltage set value and the actual bus voltage; performing deviation adjustment on the first voltage deviation value to obtain a first reference current value; performing a limiting process on the first reference current value to obtain a first target current; The first driving signal is generated according to the first target current.

4. The method according to claim 3, characterized in that Before the first reference current value is limited to obtain the first target current, the method further includes: When the bidirectional DC / AC conversion circuit is in a rectification mode, the battery voltage is greater than or equal to a preset battery voltage and the first reference current value is greater than 0, configuring the first reference current value to be 0; or When the bidirectional DC / AC conversion circuit is in an inverter mode, the actual bus voltage is less than a preset voltage threshold and the first reference current value is less than 0, the first reference current value is configured to be 0.

5. The method according to claim 3, characterized in that: The generating the first driving signal according to the first target current includes: Acquire a second voltage deviation value between a third bus voltage given value and the actual bus voltage, wherein the third bus voltage given value is a bus voltage given value of a surplus power on-grid control loop of the bidirectional DC / AC conversion circuit; performing deviation adjustment on the second voltage deviation value to obtain a reference power value; Acquiring feedback power at an AC end of the bidirectional DC / AC conversion circuit; Determine a second target current according to the reference power value and the feedback power; Obtaining a minimum value between the first target current and the second target current; The first driving signal is generated according to the minimum value.

6. The method according to claim 5, characterized in that Before determining the second target current according to the reference power value and the feedback power, the method further includes: When the backflow prevention mode is triggered, the reference power value is configured to be 0.

7. The method according to claim 3, characterized in that The generating the first driving signal according to the first target current further includes: Obtaining a third target current output by another control loop of the bidirectional DC / AC conversion circuit; Obtaining a minimum value of the first target current and each of the third target currents; The first driving signal is generated according to the minimum value.

8. The method according to claim 1, characterized in that The generating a second drive signal according to the battery voltage, the actual bus voltage and the second bus voltage given value comprises: Obtaining a third voltage deviation value between the second bus voltage set value and the actual bus voltage; performing deviation adjustment on the third voltage deviation value to obtain a compensation current value; Obtaining a feedback current at a second end of the bidirectional DC / DC conversion circuit; Determine a second reference current value according to the compensation current value and the feedback current; Performing a limiting process on the second reference current value according to the battery voltage to obtain a target charge and discharge current value; The second drive signal is generated by performing deviation adjustment based on the target charge and discharge current value.

9. The method according to claim 8, characterized in that The step of performing a limiting process on the second reference current value according to the battery voltage to obtain a target charge and discharge current value includes: Acquire a first voltage difference between a lower limit value of a discharge voltage of the battery module and the battery voltage; performing deviation adjustment on the first voltage difference to determine a first discharge current value; The minimum value between the first discharge current value and the preset discharge current value is selected as the discharge current upper limit value, and the first discharge current value and the preset discharge current value are both greater than or equal to 0; Acquire a second voltage difference between an upper limit value of a charging voltage of the battery module and the battery voltage; performing deviation adjustment on the second voltage difference to determine a first charging current value; The maximum value between the first charging current value and the preset charging current value is selected as the charging current lower limit, and the first charging current value and the preset charging current value are both less than 0; The second reference current value is limited according to the discharge current upper limit value and the charge current lower limit value to obtain the target charge and discharge current value.

10. A power conversion device, characterized in that: The power conversion device includes a bidirectional DC / DC conversion circuit, a bidirectional DC / AC conversion circuit, a first DC / DC conversion circuit, a DC bus and a control circuit, wherein the first end of the bidirectional DC / DC conversion circuit is used to connect to a battery module, and the first end of the first DC / DC conversion circuit is used to connect to a renewable DC power supply; the second end of the bidirectional DC / DC conversion circuit, the second end of the first DC / DC conversion circuit and the DC end of the bidirectional DC / AC conversion circuit are all connected to the DC bus, and the AC end of the bidirectional DC / AC conversion circuit is connected to a power grid and / or an AC load through an AC bus; the first DC / DC conversion circuit is used to convert the voltage input by the renewable DC power supply and output a voltage to the DC bus according to a conversion voltage threshold; the control circuit is used to execute the control method of the power conversion device according to any one of claims 1 to 9.

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