Power Conversion Unit Control Method and Device, Charging and Discharging Module

Abstract

The present invention provides a control method and device for a power conversion unit and a charge and discharge module. The power conversion unit includes a DC / DC topology and a DC / AC topology connected in sequence. The control method for the power conversion unit includes: if the current of the power conversion unit flows from the DC / AC topology to the DC / DC topology, obtaining the bus voltage of the power conversion unit, and controlling the DC / AC topology based on the bus voltage; obtaining the output voltage and output current of the DC / DC topology, determining a target control loop based on the output voltage and output current of the DC / DC topology, and performing constant power control on the DC / DC topology according to the target control loop; the target control loop is a voltage loop or a current loop. The present invention can effectively control the output current of the DC / DC topology, thereby solving the problem of bus imbalance caused by inaccurate current sampling during current interruption and ensuring system stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of circuit control, and more specifically, relates to a control method and device for a power conversion unit, and a charge and discharge module. Background Art

[0002] For a power conversion unit including a DC / DC topology and a DC / AC topology, different directions of energy flow can be achieved according to different current directions. Among them, the current flowing from the DC / AC topology to the DC / DC topology is defined as the charging mode, and the current flowing from the DC / DC topology to the DC / AC topology is defined as the discharging mode. In the charging mode, the system (referring to the power conversion unit) can work stably and realize the charging function from the AC side to the DC side; in the discharging mode, the control target of the system is to achieve current stability within the full power range and meet the THDI index requirements. Therefore, how to control the stable operation of the system in the charging mode and make the current THDI in the discharging mode meet the index requirements is particularly important for the power conversion unit.

[0003] However, during actual operation, a bus imbalance phenomenon will occur in the charging mode, and a current oscillation phenomenon will occur for a period of time after the DC side loses power in the discharging mode. These two problems seriously affect the reliability and stability of the system. Therefore, how to ensure the stable operation of the system has become an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0004] The purpose of the present invention is to provide a control method and device for a power conversion unit, and a charge and discharge module to ensure the stable operation of the system.

[0005] It is known that in the charging mode, the sampling deviation caused by the discontinuous charging current will make the energy extracted from the DC side to the positive and negative buses unbalanced, and further cause the machine to be protected due to the bus imbalance, that is, a bus imbalance phenomenon will occur. In view of this problem, in the first aspect of the present invention, a control method for a power conversion unit mainly for the above-mentioned charging mode is provided. The power conversion unit includes a DC / DC topology and a DC / AC topology connected in sequence; the power conversion unit control method includes:

[0006] If the current of the power conversion unit flows from the DC / AC topology to the DC / DC topology, obtain the bus voltage of the power conversion unit, and control the DC / AC topology based on the bus voltage;

[0007] Obtain the output voltage and output current of the DC / DC topology, determine the target control loop based on the output voltage and output current of the DC / DC topology, and perform constant power control on the DC / DC topology according to the target control loop; the target control loop is a voltage loop or a current loop.

[0008] In a possible implementation, determining the target control loop based on the output voltage and output current of the DC / DC topology includes:

[0009] Determining the voltage loop control quantity corresponding to the DC / DC topology based on the output voltage of the DC / DC topology and a preset voltage given value;

[0010] Determining the current loop control quantity corresponding to the DC / DC topology based on the output current of the DC / DC topology and a preset first current given value;

[0011] Determining the target control loop according to the magnitude relationship between the voltage loop control quantity corresponding to the DC / DC topology and the current loop control quantity corresponding to the DC / DC topology.

[0012] In a possible implementation, determining the target control loop according to the magnitude relationship between the voltage loop control quantity corresponding to the DC / DC topology and the current loop control quantity corresponding to the DC / DC topology includes:

[0013] If the voltage loop control quantity corresponding to the DC / DC topology is less than the current loop control quantity corresponding to the DC / DC topology, then use the voltage loop as the target control loop;

[0014] If the current loop control quantity corresponding to the DC / DC topology is less than the voltage loop control quantity corresponding to the DC / DC topology, then use the current loop as the target control loop;

[0015] If the current loop control quantity corresponding to the DC / DC topology is equal to the voltage loop control quantity corresponding to the DC / DC topology, then use either the current loop or the voltage loop as the target control loop.

[0016] In a possible implementation, performing constant power control on the DC / DC topology according to the target control loop includes:

[0017] If the target control loop is the voltage loop, perform constant power control on the DC / DC topology according to the voltage loop control quantity of the DC / DC topology corresponding to the voltage loop;

[0018] If the target control loop is the current loop, perform constant power control on the DC / DC topology according to the current loop control quantity of the DC / DC topology corresponding to the current loop.

[0019] It is known that in the discharge mode, the DC side controls the bus voltage and the AC side controls the current. When the DC side loses power, the AC side current waveform will oscillate. In view of this problem, in the second aspect of the present invention, a power conversion unit control method mainly for the above discharge mode is provided. The power conversion unit includes a DC / DC topology and a DC / AC topology connected in sequence; the power conversion unit control method includes:

[0020] If the current of the power conversion unit flows from the DC / DC topology to the DC / AC topology, obtain the bus voltage of the power conversion unit, and control the DC / DC topology based on the bus voltage;

[0021] Determine the actual current reference value based on the bus voltage, a preset lower limit value of the bus voltage, and a preset second current reference value; obtain the output current of the DC / AC topology, and control the DC / AC topology based on the actual current reference value and the output current of the DC / AC topology.

[0022] In a possible implementation manner, the determining the actual current reference value based on the bus voltage, a preset lower limit value of the bus voltage, and a preset second current reference value includes:

[0023] Determine a third current reference value based on the bus voltage and a preset lower limit value of the bus voltage;

[0024] Take the smaller value of the third current reference value and the preset second current reference value as the actual current reference value.

[0025] In a possible implementation manner, the determining the third current reference value based on the bus voltage and a preset lower limit value of the bus voltage includes:

[0026] Determine a voltage error value corresponding to the DC / AC topology based on the bus voltage and the preset lower limit value of the bus voltage;

[0027] Input the voltage error value corresponding to the DC / AC topology into a preset voltage control loop to obtain the third current reference value.

[0028] In a third aspect of the present invention, there is also provided a method for controlling a power conversion unit. The power conversion unit includes a DC / DC topology and a DC / AC topology connected in sequence, and both the DC / DC topology and the DC / AC topology are bidirectional topologies. That is to say, the following method for controlling a power conversion unit provided by the present invention can also be applied to a scenario where energy flows bidirectionally; the method for controlling a power conversion unit includes:

[0029] If the current of the power conversion unit flows from the DC / AC topology to the DC / DC topology, obtain the bus voltage of the power conversion unit, and control the DC / AC topology based on the bus voltage; obtain the output voltage and output current of the DC / DC topology, determine a target control loop based on the output voltage and output current of the DC / DC topology, and perform constant power control on the DC / DC topology according to the target control loop; the target control loop is a voltage loop or a current loop;

[0030] If the current of the power conversion unit flows from the DC / DC topology to the DC / AC topology, obtain the bus voltage of the power conversion unit, and control the DC / DC topology based on the bus voltage; determine the actual current set value based on the bus voltage, a preset lower limit value of the bus voltage, and a preset second current set value; obtain the output current of the DC / AC topology, and control the DC / AC topology based on the actual current set value and the output current of the DC / AC topology.

[0031] In a fourth aspect of the present invention, there is also provided a power conversion unit control device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the above-described power conversion unit control method are implemented.

[0032] In a fifth aspect of the present invention, there is also provided a charge and discharge module, including: the above-described power conversion unit and power conversion unit control device.

[0033] The beneficial effects of the power conversion unit control method, device, and charge and discharge module provided by the present invention are as follows:

[0034] When the power conversion unit is in the charging mode, the present invention determines whether to use a voltage loop or a current loop for constant power control based on the output voltage and output current (or charging current) on the DC side. Compared with the traditional double closed-loop control scheme, the present invention supports the switching of the control loop when the current sampling is inaccurate in the current discontinuous mode, which can effectively reduce the impact of the current discontinuous mode on the bus balance, thereby ensuring the stability of the system.

[0035] When the power conversion unit is in the discharging mode, considering that the fundamental cause of current oscillation is that after the DC side shuts down, the bus energy comes from the energy stored in the bus electrolytic capacitor. If the discharging power on the AC side is large and the energy of the bus electrolytic capacitor decreases to a level insufficient to support the minimum modulation ratio requirement of the DC / AC topology, current oscillation will occur. The present invention introduces the lower limit value of the bus voltage into the control of the DC / AC topology to stabilize the bus voltage to the lower limit value of the bus voltage when the bus voltage drops below the lower limit value of the bus voltage, thereby preventing current oscillation and ensuring the stability of the system. Description of the Drawings

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0037] Figure 1Schematic flow chart of the power conversion unit control method provided by an embodiment of the present invention;

[0038] Figure 2 Schematic flow chart of the power conversion unit control method provided by an embodiment of the present invention;

[0039] Figure 3 Schematic structural diagram of the power conversion unit control device provided by an embodiment of the present invention;

[0040] Figure 4 Schematic structural diagram of the charge and discharge module provided by an embodiment of the present invention;

[0041] Figure 5 Schematic structural diagram of the power conversion unit provided by an embodiment of the present invention;

[0042] Figure 6 Control loop diagram of the DC / DC topology in the charging mode provided by an embodiment of the present invention;

[0043] Figure 7 Control loop diagram of the DC / AC topology in the discharging mode provided by an embodiment of the present invention. Detailed implementation manners

[0044] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0045] The present invention will be further described in detail below with reference to the accompanying drawings and specific implementation manners.

[0046] It is known that in the charging mode, the sampling deviation caused by the discontinuous charging current will cause the energy extracted from the positive and negative buses on the DC side to be unbalanced, and further cause the machine to be protected due to the bus imbalance, that is, the bus imbalance phenomenon will occur. In view of this problem, in the first aspect of the present invention, a power conversion unit control method mainly for the above charging mode is provided, which can be referred to Figure 5 , the power conversion unit includes a DC / DC topology and a DC / AC topology connected in sequence. Among them, the DC / DC topology can be implemented by adopting a Buck / Boost + CLLC full-bridge two-stage scheme, and the DC / AC topology can be implemented by adopting a T-type three-level topology. The specific implementation method is not limited herein.

[0047] Please refer to Figure 1 , Figure 1 Schematic flow chart of the power conversion unit control method provided by an embodiment of the present invention. The power conversion unit control method provided by the embodiment of the present invention includes:

[0048] S101: If the current of the power conversion unit flows from the DC / AC topology to the DC / DC topology, obtain the bus voltage of the power conversion unit, and control the DC / AC topology based on the bus voltage.

[0049] S102: Obtain the output voltage and output current of the DC / DC topology, determine the target control loop based on the output voltage and output current of the DC / DC topology, and perform constant power control on the DC / DC topology according to the target control loop. The target control loop is a voltage loop or a current loop.

[0050] In this embodiment, the operating mode of the power conversion unit when the current of the power conversion unit flows from the DC / AC topology to the DC / DC topology can be defined as the charging mode. For example, in practical applications, an energy storage device (battery) or other DC load can be externally connected to the DC side, and the power grid can be externally connected to the AC side. When the current flows from the DC / AC topology to the DC / DC topology, that is, the power grid is used to charge the DC load, so this mode can be defined as the charging mode.

[0051] In the charging mode, to solve the aforementioned bus imbalance problem, this embodiment mainly improves the control scheme of the DC / DC topology. The control scheme of the DC / AC topology can directly adopt the existing scheme. For example, the DQ loop control plus the seven-segment modulation scheme can be adopted on the AC side, which can stabilize the total bus voltage, but the ability to control the balance of the positive and negative bus voltages is weak. Therefore, the bus balance degree mainly depends on the balance degree of the energy extraction from the positive and negative buses on the DC side. If the energy extracted by the positive and negative half topologies on the DC side is the same, the positive and negative buses can be kept balanced, otherwise, the bus imbalance phenomenon will occur.

[0052] For example, in the prior art, due to the wide charging voltage range (for example, it can be 200 - 950V), the charging direction is the Buck topology, and the charging control is constant power control. Therefore, the higher the charging voltage, the smaller the charging current, and the longer the Buck topology works in the discontinuous mode. The current sampling is inaccurate in the discontinuous mode, resulting in uneven energy extraction from the positive and negative buses on the DC side, and further leading to bus imbalance, making the system unable to charge and operate normally. Using the traditional voltage-current double closed-loop control, in the current discontinuous mode, the feedback deviation of the current inner loop is large, resulting in a large deviation of the positive and negative duty cycles, and finally causing different energy extraction from the positive and negative halves, resulting in positive and negative bus imbalance. Therefore, the embodiment of the present invention adopts the above-mentioned steps S101 - S102, that is, switches the control loop according to the (DC) output voltage and (DC) output current (i.e., the charging current) of the DC / DC topology, so as to reduce the impact of the current discontinuous mode on the bus balance and ensure the bus balance.

[0053] As can be seen from the above description, when the power conversion unit is in the charging mode, the present invention determines whether to use a voltage loop or a current loop for constant power control based on the output voltage and output current (or charging current) on the DC side. Compared with the traditional double closed-loop control scheme, the present invention supports the switching of the control loop when the current sampling is inaccurate in the current discontinuous mode, which can effectively reduce the impact of the current discontinuous mode on the bus balance, thereby ensuring the stability of the system.

[0054] In a possible implementation, please refer to Figure 6 , and determining a target control loop based on the output voltage and output current of the DC / DC topology includes:

[0055] Determining a voltage loop control quantity corresponding to the DC / DC topology based on the output voltage of the DC / DC topology and a preset voltage given value. Determining a current loop control quantity corresponding to the DC / DC topology based on the output current of the DC / DC topology and a preset first current given value.

[0056] Determining the target control loop according to the magnitude relationship between the voltage loop control quantity corresponding to the DC / DC topology and the current loop control quantity corresponding to the DC / DC topology.

[0057] In this embodiment, the method for determining the voltage loop control quantity corresponding to the DC / DC topology is: determining the voltage error value corresponding to the DC / DC topology according to the preset voltage given value and the output voltage of the DC / DC topology, and inputting the voltage error value corresponding to the DC / DC topology into the preset voltage loop controller corresponding to the DC / DC topology ( Figure 6 taking a PI controller as an example, and other controllers can also be used in actual applications), to obtain the voltage loop control quantity corresponding to the DC / DC topology.

[0058] In this embodiment, the method for determining the current loop control quantity corresponding to the DC / DC topology is: determining the current error value corresponding to the DC / DC topology according to the preset first current given value and the output current of the DC / DC topology (corresponding to Figure 6 the output current 1 therein), and inputting the current error value corresponding to the DC / DC topology into the preset current loop controller corresponding to the DC / DC topology ( Figure 6 taking a PI controller as an example, and other controllers can also be used in actual applications), to obtain the current loop control quantity corresponding to the DC / DC topology.

[0059] In a possible implementation, please refer to Figure 6 , and determining the target control loop according to the magnitude relationship between the voltage loop control quantity corresponding to the DC / DC topology and the current loop control quantity corresponding to the DC / DC topology includes:

[0060] If the voltage loop control quantity corresponding to the DC / DC topology is less than the current loop control quantity corresponding to the DC / DC topology, then the voltage loop is used as the target control loop.

[0061] If the current loop control quantity corresponding to the DC / DC topology is less than the voltage loop control quantity corresponding to the DC / DC topology, then the current loop is used as the target control loop.

[0062] If the current loop control quantity corresponding to the DC / DC topology is equal to the voltage loop control quantity corresponding to the DC / DC topology, then either the current loop or the voltage loop is used as the target control loop.

[0063] In this embodiment, reference can be made to Figure 6 , that is, the loop with the smaller control quantity is used as the target control loop. When the feedback deviation of the current loop is large, the output of the current loop is large (that is, the current loop control quantity corresponding to the DC / DC topology is large), and at this time the output of the voltage loop is small (that is, the voltage loop control quantity corresponding to the DC / DC topology is small). Therefore, the control is switched to the voltage loop. Since the charging is a constant power control, the voltage loop can effectively control the charging voltage, and then the charging current can also be effectively controlled, thus solving the problem of bus imbalance caused by inaccurate current sampling in the discontinuous mode.

[0064] In this embodiment, maintaining a constant power (constant power) is the product of the preset voltage given value and the preset first current given value.

[0065] In a possible implementation manner, please refer to Figure 6 , and perform constant power control on the DC / DC topology according to the target control loop, including:

[0066] If the target control loop is the voltage loop, perform constant power control on the DC / DC topology according to the voltage loop control quantity of the DC / DC topology corresponding to the voltage loop.

[0067] If the target control loop is the current loop, perform constant power control on the DC / DC topology according to the current loop control quantity of the DC / DC topology corresponding to the current loop.

[0068] In this embodiment, that is, use the loop with the smaller control quantity to perform constant power control on the DC / DC topology to solve the problem of bus imbalance caused by inaccurate current sampling in the discontinuous mode.

[0069] It is known that in the discharge mode, the DC side controls the bus voltage and the AC side controls the current. When the DC side loses power, there will be an oscillation phenomenon in the AC side current waveform. For this problem, in the second aspect of the present invention, a power conversion unit control method mainly for the above discharge mode is provided. Reference can be made to Figure 5, the power conversion unit includes a DC / DC topology and a DC / AC topology connected in sequence. Among them, the DC / DC topology can be implemented by a Buck / Boost + CLLC full-bridge two-stage scheme, and the DC / AC topology can be implemented by a T-type three-level topology. The specific implementation method is not limited here.

[0070] Please refer to Figure 2 , Figure 2 is a schematic flowchart of the power conversion unit control method provided by an embodiment of the present invention. The power conversion unit control method provided by the embodiment of the present invention includes:

[0071] S201: If the current of the power conversion unit flows from the DC / DC topology to the DC / AC topology, obtain the bus voltage of the power conversion unit, and control the DC / DC topology based on the bus voltage.

[0072] S202: Determine the actual current reference value based on the bus voltage, a preset lower limit value of the bus voltage, and a preset second current reference value. Obtain the output current of the DC / AC topology, and control the DC / AC topology based on the actual current reference value and the output current of the DC / AC topology.

[0073] In this embodiment, the operating mode of the power conversion unit when the current of the power conversion unit flows from the DC / DC topology to the DC / AC topology can be defined as the discharging mode. For example, in actual applications, a energy storage device (battery) or other DC load can be externally connected to the DC side, and the power grid can be externally connected to the AC side. When the current flows from the DC / DC topology to the AC / DC topology, that is, grid-connected discharging, so this mode can be defined as the discharging mode.

[0074] In the discharging mode, the DC side controls the bus voltage to be stable, and the AC side controls the grid-connected current to reach the set value. When the DC side loses power, since the shutdown command is generated by the DC side and sent to the AC side through communication, there will be a phenomenon that the DC side shuts down immediately and the AC side shuts down with a delay. During the delay time, the DC side has shut down, and at this time the bus voltage is the voltage on the electrolytic capacitor, while the AC side is still operating in grid connection. If the discharging power of the AC side is large at this time and the energy stored in the bus electrolytic capacitor cannot meet the minimum modulation ratio requirement of the DC / AC topology on the AC side, the grid-connected current oscillation phenomenon will occur. To solve the above problems, the embodiment of the present invention adopts the solution of the above steps S201 - S202. Among them, the control of the DC / AC topology is mainly improved, that is, the lower limit value of the bus voltage is introduced into the calculation of the actual current reference value, so as to consider the influence of the bus voltage dropping below the lower limit value of the bus voltage on the grid-connected current, thereby solving the above grid-connected current oscillation problem. Among them, the control of the DC / DC topology can be implemented by conventional means in the art and will not be elaborated here.

[0075] As can be seen from the above description, when the power conversion unit is in the discharge mode, considering the root cause of current oscillation: after the DC side shuts down, the bus energy comes from the energy stored in the bus electrolytic capacitor. If the AC side discharge power is large and the energy of the bus electrolytic capacitor decreases to a level insufficient to support the minimum modulation ratio requirement of the DC / AC topology, current oscillation will occur. The present invention introduces the lower limit value of the bus voltage into the control of the DC / AC topology, so as to stabilize the bus voltage to the lower limit value of the bus voltage when the bus voltage drops below the lower limit value of the bus voltage, thereby preventing current oscillation and ensuring system stability.

[0076] In a possible implementation, please refer to Figure 7 , determining the actual current reference value based on the bus voltage, a preset lower limit value of the bus voltage, and a preset second current reference value, includes:

[0077] Determining a third current reference value based on the bus voltage and the preset lower limit value of the bus voltage.

[0078] Taking the smaller value of the third current reference value and the preset second current reference value as the actual current reference value.

[0079] In this embodiment, to solve the problem of grid-connected current oscillation, in the discharge mode, the AC side can calculate the lower limit value of the bus voltage that can satisfy the minimum modulation ratio of the DC / AC topology according to the real-time grid voltage. When the AC side current loop is working, the bus voltage loop is also calculating in real time with the lower limit value of the bus voltage as the reference.

[0080] In this embodiment, determining the third current reference value based on the bus voltage and the preset lower limit value of the bus voltage, includes:

[0081] Determining the voltage error value corresponding to the DC / AC topology based on the bus voltage and the preset lower limit value of the bus voltage. Inputting the voltage error value corresponding to the DC / AC topology into a preset voltage control loop ( Figure 7 which is a PI control loop in this case, and other control loops can also be used), to obtain the third current reference value.

[0082] In this embodiment, the smaller value of the third current reference value and the preset second current reference value can be taken as the actual current reference value. If the third current reference value is equal to the preset second current reference value, any one of the third current reference value and the preset second current reference value can be selected as the actually adopted current reference value.

[0083] In this embodiment, when the actual bus voltage is higher than the lower limit value of the bus voltage, the output of the AC-side voltage loop is relatively large and greater than the second current reference value. Therefore, at this time, only the grid-connected current loop on the AC side controls the grid-connected current. When the actual bus voltage drops below the lower limit value of the bus voltage, the output of the AC-side bus voltage loop decreases and becomes less than the second current reference value. At this time, the bus loop is added to the closed-loop control to form a voltage-current double closed-loop. The voltage loop can stabilize the bus voltage to the lower limit value of the bus voltage. (If the power conversion unit is bidirectional, the system energy can be switched from the discharge mode to the charge mode to stabilize the bus), thereby solving the problem of current oscillation.

[0084] Among them, after determining the actual current reference value, the control quantity of the DC / AC topology can be determined according to the output current of the DC / AC topology (corresponding to Figure 7 the output current 2 therein, that is, the grid-connected current) and the actual current reference value, and then the control of the DC / AC topology can be realized.

[0085] In the third aspect of the present invention, a control method for a power conversion unit is further provided. Reference can be made to Figure 5 , and the power conversion unit includes a DC / DC topology and a DC / AC topology connected in sequence. Among them, the DC / DC topology can be implemented by adopting a Buck / Boost + CLLC full-bridge two-stage scheme, and the DC / AC topology can be implemented by adopting a T-type three-level topology. The specific implementation method is not limited here. That is to say, the following control method for the power conversion unit provided by the present invention can also be applied to the scenario of bidirectional energy flow. The control method for the power conversion unit provided by the embodiments of the present invention includes:

[0086] If the current of the power conversion unit flows from the DC / AC topology to the DC / DC topology, the bus voltage of the power conversion unit is obtained, and the DC / AC topology is controlled based on the bus voltage. The output voltage and output current of the DC / DC topology are obtained, the target control loop is determined based on the output voltage and output current of the DC / DC topology, and the DC / DC topology is subjected to constant power control according to the target control loop. The target control loop is a voltage loop or a current loop.

[0087] If the current of the power conversion unit flows from the DC / DC topology to the DC / AC topology, the bus voltage of the power conversion unit is obtained, and the DC / DC topology is controlled based on the bus voltage. The actual current reference value is determined based on the bus voltage, a preset lower limit value of the bus voltage, and a preset second current reference value. The output current of the DC / AC topology is obtained, and the DC / AC topology is controlled based on the actual current reference value and the output current of the DC / AC topology.

[0088] That is to say, the specific solutions provided by the above embodiments of the present invention can also be applied to a bidirectional power conversion unit, and the specific implementation manner can refer to the above embodiments and will not be elaborated here.

[0089] In a fourth aspect of the present invention, there is also provided a power conversion unit control device 300, comprising: one or more processors 301, one or more input devices 302, one or more output devices 303, and one or more memories 304. The above-mentioned processors 301, input devices 302, output devices 303, and memories 304 communicate with each other through a communication bus 305. The memory 304 is used to store computer programs, and the computer programs include program instructions. The processor 301 is used to execute the program instructions stored in the memory 304. Among them, the processor 301 is configured to call the program instructions to execute the steps of the above method embodiments. It should be understood that in the embodiments of the present invention, the so-called processor 301 may be a central processing unit (CPU). The processor may also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc. The input device 302 may include a touchpad, a fingerprint sensor (for collecting the fingerprint information and the direction information of the fingerprint) of a user, a microphone, etc., and the output device 303 may include a display (such as an LCD), a speaker, etc. The memory 304 may include a read-only memory and a random access memory, and provide instructions and data to the processor 301. A part of the memory 304 may also include a non-volatile random access memory. For example, the memory 304 may also store information about the device type. In a specific implementation, the processors 301, input devices 302, and output devices 303 described in the embodiments of the present invention may implement the implementation manners described in the first and second embodiments of the power conversion unit control method provided by the embodiments of the present invention.

[0090] Please refer to Figure 4 In a fifth aspect of the present invention, there is also provided a charge and discharge module 40, comprising: the above-mentioned power conversion unit 500 and the power conversion unit control device 300.

[0091] The above are only the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A control method for a power conversion unit, characterized in that The power conversion unit includes a DC / DC topology and a DC / AC topology connected in sequence; the control method of the power conversion unit in the current discontinuous mode includes: If the current of the power conversion unit flows from the DC / AC topology to the DC / DC topology, obtain the bus voltage of the power conversion unit, and control the DC / AC topology based on the bus voltage; Obtain the output voltage and output current of the DC / DC topology, determine the voltage loop control quantity corresponding to the DC / DC topology based on the output voltage of the DC / DC topology and a preset voltage given value; determine the current loop control quantity corresponding to the DC / DC topology based on the output current of the DC / DC topology and a preset first current given value; If the voltage loop control quantity corresponding to the DC / DC topology is less than the current loop control quantity corresponding to the DC / DC topology, then use the voltage loop as the target control loop; if the current loop control quantity corresponding to the DC / DC topology is less than the voltage loop control quantity corresponding to the DC / DC topology, then use the current loop as the target control loop; if the current loop control quantity corresponding to the DC / DC topology is equal to the voltage loop control quantity corresponding to the DC / DC topology, then use either the current loop or the voltage loop as the target control loop; Perform constant power control on the DC / DC topology according to the target control loop.

2. The power conversion unit control method according to claim 1, characterized in that, The performing constant power control on the DC / DC topology according to the target control loop includes: If the target control loop is the voltage loop, perform constant power control on the DC / DC topology according to the voltage loop control quantity corresponding to the DC / DC topology; If the target control loop is the current loop, perform constant power control on the DC / DC topology according to the current loop control quantity corresponding to the DC / DC topology.

3. A control method for a power conversion unit, characterized in that The power conversion unit includes a DC / DC topology and a DC / AC topology connected in sequence; the control method of the power conversion unit when the DC side loses power in the discharge mode includes: If the current of the power conversion unit flows from the DC / DC topology to the DC / AC topology, obtain the bus voltage of the power conversion unit, and control the DC / DC topology based on the bus voltage; Determine the voltage error value corresponding to the DC / AC topology based on the bus voltage and a preset lower limit value of the bus voltage; Input the voltage error value corresponding to the DC / AC topology into a preset voltage control loop to obtain a third current given value; Use the smaller value of the third current given value and a preset second current given value as the actual current given value; Obtain the output current of the DC / AC topology, and control the DC / AC topology based on the actual current given value and the output current of the DC / AC topology.

4. A control method for a power conversion unit, characterized in that, The power conversion unit includes a DC / DC topology and a DC / AC topology connected in sequence, and both the DC / DC topology and the DC / AC topology are bidirectional topologies; the control method of the power conversion unit in the current discontinuous mode includes: If the current of the power conversion unit flows from the DC / AC topology to the DC / DC topology, obtain the bus voltage of the power conversion unit, and control the DC / AC topology based on the bus voltage; obtain the output voltage and output current of the DC / DC topology, and determine the voltage loop control quantity corresponding to the DC / DC topology based on the output voltage of the DC / DC topology and a preset voltage given value; determine the current loop control quantity corresponding to the DC / DC topology based on the output current of the DC / DC topology and a preset first current given value; if the voltage loop control quantity corresponding to the DC / DC topology is less than the current loop control quantity corresponding to the DC / DC topology, then use the voltage loop as the target control loop; if the current loop control quantity corresponding to the DC / DC topology is less than the voltage loop control quantity corresponding to the DC / DC topology, then use the current loop as the target control loop; if the current loop control quantity corresponding to the DC / DC topology is equal to the voltage loop control quantity corresponding to the DC / DC topology, then use either the current loop or the voltage loop as the target control loop; perform constant power control on the DC / DC topology according to the target control loop; If the current of the power conversion unit flows from the DC / DC topology to the DC / AC topology, obtain the bus voltage of the power conversion unit, and control the DC / DC topology based on the bus voltage; determine the actual current given value based on the bus voltage, a preset lower limit value of the bus voltage, and a preset second current given value; obtain the output current of the DC / AC topology, and control the DC / AC topology based on the actual current given value and the output current of the DC / AC topology.

5. A power conversion unit control device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, the steps of the method according to any one of claims 1 to 4 are implemented.

6. A charge and discharge module, characterized in that, Comprising: A power conversion unit applied according to any one of claims 1-4 and a power conversion unit control device according to claim 5.

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