CN117318242B

CN117318242B - Power conversion device, control method of power conversion device and energy storage system

Info

Publication number: CN117318242B
Application number: CN202311371741.6A
Authority: CN
Inventors: 龙海洋; 李世军
Original assignee: If New Energy Technology Jiangsu Co ltd
Current assignee: If New Energy Technology Jiangsu Co ltd
Priority date: 2023-10-23
Filing date: 2023-10-23
Publication date: 2024-03-29
Anticipated expiration: 2043-10-23
Also published as: CN117318242A

Abstract

The application relates to the technical field of new energy, and particularly discloses a power conversion device, a control method of the power conversion device and an energy storage system. The power conversion device includes: the power conversion device comprises a switch module, a first power conversion module, a second power conversion module and a control module; the first connecting end of the first power conversion module is electrically connected with the alternating current power supply through the switch module, the second connecting end of the first power conversion module is electrically connected with the first connecting end of the second power conversion module through the direct current bus, and the second connecting end of the second power conversion module is electrically connected with the battery; the control module is used for acquiring the voltage of the direct current bus after determining that the power conversion device enters a battery wake-up mode; and the voltage control module is used for controlling the direct current bus voltage and the voltage of the second connecting end of the second power conversion module to synchronously increase in response to the direct current bus voltage being smaller than or equal to a preset bus voltage threshold value. By adopting the method, the damage risk of the device can be reduced, and the safety is improved.

Description

Power conversion device, control method of power conversion device and energy storage system

Technical Field

The present disclosure relates to the field of new energy technologies, and in particular, to a power conversion device, a control method of the power conversion device, and an energy storage system.

Background

In general, in order to ensure normal use of the battery and safety of the battery cell, when the battery management system detects that the energy of the battery cell is too low, a connection loop between the battery cell and external energy is cut off, so that the battery enters a dormant state. In some situations, when a battery in a dormant state is charged, electric energy needs to be extracted from a dc bus energy source through an inverter charger (inverter charger), and a stable voltage is output to a battery port to wake up a battery management system in the battery, and then the battery enters a charging state.

However, a switching tube is arranged in a control loop between the direct current bus and the battery port, and when the battery in the dormant state is awakened, because a large voltage difference exists between the direct current bus voltage and the battery port voltage, the switching tube is subjected to great stress, and the switching tube is damaged.

Disclosure of Invention

In view of the foregoing, it is desirable to provide a power conversion device, a control method of the power conversion device, and an energy storage system that can reduce the risk of device damage and improve the battery charging safety.

In a first aspect, the present application provides a power conversion apparatus comprising: the power conversion device comprises a switch module, a first power conversion module, a second power conversion module and a control module; the first connecting end of the first power conversion module is electrically connected with an alternating current power supply through the switch module, the second connecting end of the first power conversion module is electrically connected with the first connecting end of the second power conversion module through a direct current bus, and the second connecting end of the second power conversion module is electrically connected with a battery;

The control module is used for acquiring the voltage of the direct current bus after determining that the power conversion device enters a battery wake-up mode; and the voltage synchronous increasing device is used for controlling the direct current bus voltage and the voltage of the second connecting end of the second power conversion module to synchronously increase in response to the direct current bus voltage being smaller than or equal to a preset bus voltage threshold value.

In one embodiment, the control module is further configured to control the switch module to switch to an off state in response to the dc bus voltage being greater than the preset bus voltage threshold, and switch the first power conversion module to a preset operation mode until the dc bus voltage is less than or equal to the preset bus voltage threshold.

In one embodiment, the control module is further configured to, prior to determining that the power conversion device enters the battery wake mode, control the power conversion device to enter the battery wake mode upon determining that one or more of the following conditions are met:

determining the type of the battery as the type of the battery to be awakened;

determining that the voltage of the second connection end of the second power conversion module is smaller than or equal to a first preset battery voltage threshold;

Determining that the output voltage of the alternating current power supply meets a preset condition;

and determining that the current working condition of the power conversion device can be awakened by a battery.

In one embodiment, the control module is configured to control the switch module to switch to a charging state to enable the first power conversion module to raise the dc bus voltage and control the second power conversion module to raise the voltage of the second connection end of the second power conversion module in response to the dc bus voltage being less than or equal to a preset bus voltage threshold.

In one embodiment, the control module is further configured to control the second power conversion module to switch to a closed state and periodically obtain the voltage of the second connection end of the second power conversion module in response to the voltage of the second connection end of the second power conversion module being greater than or equal to a second preset battery voltage threshold;

and the voltage of the second connection end of the second power conversion module is larger than a third preset battery voltage threshold value within the first preset time, the battery wake-up mode is exited, and the battery is started to be charged, wherein the second preset battery voltage threshold value is smaller than the third preset battery voltage threshold value.

In one embodiment, the control module is further configured to, in response to the voltage of the second connection end of the second power conversion module being less than or equal to a fourth preset battery voltage threshold in a second preset time, exit the battery wake-up mode, and/or send an abnormal alarm signal, where the fourth preset battery voltage threshold is less than the second preset battery voltage threshold.

In a second aspect, the present application further provides a control method of a power conversion apparatus, where the power conversion apparatus includes: the power conversion device comprises a switch module, a first power conversion module, a second power conversion module and a control module; the first connecting end of the first power conversion module is electrically connected with an alternating current power supply through the switch module, the second connecting end of the first power conversion module is electrically connected with the first connecting end of the second power conversion module through a direct current bus, and the second connecting end of the second power conversion module is electrically connected with a battery;

the method comprises the following steps:

after determining that the power conversion device enters a battery wake-up mode, acquiring a direct current bus voltage;

and controlling the direct current bus voltage and the voltage of the second connecting end of the second power conversion module to synchronously increase in response to the direct current bus voltage being smaller than or equal to a preset bus voltage threshold.

In one embodiment, the method further comprises:

and controlling the switch module to switch to an off state in response to the direct current bus voltage being greater than the preset bus voltage threshold, and switching the first power conversion module to a preset working mode until the direct current bus voltage is less than or equal to the preset bus voltage threshold.

In one embodiment, the method further comprises:

controlling the second power conversion module to switch to a closed state in response to the voltage of the second connection end of the second power conversion module being greater than or equal to a second preset battery voltage threshold;

periodically acquiring the voltage of a second connection end of the second power conversion module;

and responding to the fact that the voltage of the second connecting end of the second power conversion module is larger than a third preset battery voltage threshold value within a first preset time, exiting the battery wake-up mode, and starting to charge the battery, wherein the second preset battery voltage threshold value is smaller than the third preset battery voltage threshold value.

In one embodiment, prior to determining that the power conversion device enters battery wake mode, the method further comprises controlling the power conversion device to enter battery wake mode upon determining that one or more of the following conditions are met:

Determining the type of the battery as the type of the battery to be awakened;

In one embodiment, the method further comprises:

and when the direct current bus voltage is smaller than or equal to a preset bus voltage threshold, controlling the switch module to switch to a charging state so that the first power conversion module lifts the direct current bus voltage, and controlling the second power conversion module to lift the voltage of a second connecting end of the second power conversion module.

In one embodiment, the method further comprises:

and responding to the voltage of the second connecting end of the second power conversion module to be smaller than or equal to a fourth preset battery voltage threshold value in a second preset time, exiting the battery wake-up mode, and/or sending an abnormality alarm signal, wherein the fourth preset battery voltage threshold value is smaller than the second preset battery voltage threshold value.

In a third aspect, embodiments of the present disclosure further provide an energy storage system, including a power conversion device and a battery according to any one of the embodiments of the present disclosure, where the power conversion device converts direct current from the battery into alternating current for delivery to a power grid or load, or converts alternating current from the alternating current power source into direct current for charging the battery.

In a fourth aspect, embodiments of the present disclosure also provide a computer device. The computer device comprises a memory storing a computer program and a processor implementing the steps of the method of any of the embodiments of the present disclosure when the computer program is executed.

In a fifth aspect, embodiments of the present disclosure also provide a computer-readable storage medium. The computer readable storage medium has stored thereon a computer program which, when executed by a processor, implements the steps of the method of any of the embodiments of the present disclosure.

In a sixth aspect, embodiments of the present disclosure also provide a computer program product. The computer program product comprises a computer program which, when executed by a processor, implements the steps of the method according to any of the embodiments of the present disclosure.

In the power conversion device, a first connection end of a first power conversion module is electrically connected with an ac power supply through a switch module, a second connection end of the first power conversion module is electrically connected with a first connection end of a second power conversion module through a dc bus, and a second connection end of the second power conversion module is electrically connected with a battery. When a battery in a dormant state is awakened, after the power conversion device is determined to enter a battery awakening mode, the control module acquires a direct current bus voltage, and when the direct current bus voltage is smaller than or equal to a preset bus voltage threshold value, the control module controls the direct current bus voltage and the voltage of a second connecting end of the second power conversion module to synchronously increase, so that the voltage difference between the direct current bus voltage and the voltage of the second connecting end of the second power conversion module is always kept at a smaller level, and in the process of slowly increasing the direct current bus voltage, energy is provided for a battery port to awaken the battery; the risk of damage to components of the second power conversion module caused by larger stress to the components due to overlarge voltage difference between the DC bus voltage and the battery port voltage in the wake-up process is reduced, the stability and safety of the battery charging process are ensured, the reliability of the power conversion device and the battery is improved, and the power conversion device is suitable for more application scenes.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the related art, the following description will briefly explain the drawings required to be used in the embodiments or the related technical descriptions, and it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained according to the drawings without any inventive effort for those skilled in the art.

FIG. 1 is a schematic diagram of a power conversion device in one embodiment;

FIG. 2 is a schematic circuit diagram of a power conversion device according to an embodiment;

FIG. 3 is a flow chart of a method of controlling a power conversion device according to an embodiment;

FIG. 4 is a flow chart of a method of controlling a power conversion device according to an embodiment;

FIG. 5 is a flow chart of a method of controlling a power conversion device according to one embodiment;

FIG. 6 is a flow chart of a method of controlling a power conversion device according to one embodiment;

FIG. 7 is a waveform diagram of voltages during a battery wake-up process according to one embodiment of the prior art;

FIG. 8 is a waveform diagram of voltages during battery wakeup in one embodiment;

FIG. 9 is a waveform diagram of voltages during a battery wakeup process when the DC bus voltage is too high in one embodiment;

Fig. 10 is an internal structural view of a computer device in one embodiment.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the present application.

It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element. It will be further understood that, as used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context indicates otherwise. Furthermore, the terms "or," "and/or," "including at least one of," and the like, as used herein, are to be construed as inclusive, or mean any one or any combination. An exception to this definition will occur only when a combination of elements, functions, steps or operations are in some way inherently mutually exclusive.

It should be understood that although the terms first, second, third, etc. may be used herein to describe various parameters or modules, these parameters or modules should not be limited by these terms. These terms are only used to distinguish one parameter or module from another of the same type. For example, a first parameter may also be referred to as a second parameter, and similarly, a second parameter may also be referred to as a first parameter, without departing from the scope herein. The words "if", as used herein, may be interpreted as "at … …" or "at … …" or "in response to a determination" or "in response to a detection", depending on the context. Similarly, the phrase "if determined" or "if detected (stated condition or event)" may be interpreted as "when determined" or "in response to determination" or "when detected (stated condition or event)" or "in response to detection (stated condition or event), depending on the context. Furthermore, components, features, and elements that are identically named in different embodiments of the present application may have the same meaning or may have different meanings, the particular meaning of which is to be determined by its interpretation in this particular embodiment or further in connection with the context of this particular embodiment.

It should be understood that, although the steps in the flowcharts in the embodiments of the present application are sequentially shown as indicated by arrows, these steps are not necessarily sequentially performed in the order indicated by the arrows. The steps are not strictly limited in order and may be performed in other orders, unless explicitly stated herein. Moreover, at least some of the steps in the figures may include multiple sub-steps or stages that are not necessarily performed at the same time, but may be performed at different times, the order of their execution not necessarily occurring in sequence, but may be performed alternately or alternately with other steps or at least a portion of the other steps or stages.

It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the claims.

In one embodiment, as shown in fig. 1, there is provided a power conversion apparatus 100, comprising: a switching module 110, a first power conversion module 120, a second power conversion module 130, and a control module 140; the first connection end of the first power conversion module 120 is electrically connected to the ac power supply 200 through the switch module 110, the second connection end of the first power conversion module 120 is electrically connected to the first connection end of the second power conversion module 130 through a dc bus, and the second connection end of the second power conversion module is electrically connected to the battery 300;

In an embodiment of the disclosure, a power conversion device is provided, where the power conversion device includes a switch module, a first power conversion module, a second power conversion module, and a control module. The first connecting end of the first power conversion module is electrically connected with the alternating current power supply through the switch module, the second connecting end of the first power conversion module is electrically connected with the first connecting end of the second power conversion module through the direct current bus, and the second connecting end of the second power conversion module is electrically connected with the battery. In one example, the power conversion device may further be electrically connected to the load at the first connection end of the first power conversion module under different application scenarios, so as to supply the load with the electric energy of the battery 300. In this embodiment, during the charging process of the battery, the current output by the ac power supply is converted into a current capable of providing electric power for the battery after passing through the power conversion device, and the current is output to the battery. In one example, when the battery is charged by using an AC power source, the current is converted by the power conversion device, wherein the first power conversion module may be configured as an AC-DC converter (i.e., AC/DC converter), the second power conversion module may be configured as a DC-DC converter (i.e., DC/DC converter), the first power conversion module outputs DC power, and the second power conversion module adjusts the DC power output by the first power conversion module to output DC power capable of charging the battery. In one example, the first power conversion module may be derived based on an H-bridge inverter setting and the second power conversion module may be derived based on an isolated LLC converter setting. When the battery is not activated, the battery port voltage is almost zero, so that the voltage difference between the direct current bus voltage and the battery port voltage is large, and large stress can be caused to a switching tube in the second power conversion module, so that the switching tube is damaged. The control module is in communication connection with the switch module and can control the switch module to be opened and closed and acquire the working state of the switch module; the control module can acquire parameters such as current values and voltage values of the first power conversion module and the second power conversion module through the sampling module, and can adjust working parameters of the first power conversion module and the second power conversion module through outputting control signals. In this embodiment, the ac power source may include, but is not limited to, a power grid, an inverter outputting ac power, and the like, and may be specifically determined according to an actual application scenario.

FIG. 2 is a schematic circuit diagram of a power conversion device according to an exemplary embodiment, wherein a first power conversion module may receive an AC input and establish a DC bus voltage; the first power conversion module may also be connected to a load, which is powered by the battery. The control module includes a sampling unit, which may collect the ac power supply voltage Vac, the dc bus voltage Vbus, and the voltage at the second connection end of the second power conversion module (i.e., the battery port voltage) Vbat.

In general, in order to ensure normal use of the battery and safety of the battery core, the battery enters a sleep state when the battery power is too low, and when the battery in the sleep state needs to be charged, the battery needs to be awakened first. In this embodiment, after determining that the power conversion device enters the battery wake-up mode, the control module obtains the dc bus voltage, where a manner of determining whether the power conversion device enters the battery wake-up mode may be determined according to an actual application scenario, for example, whether the power conversion device enters the battery wake-up mode may be determined according to an ac power source connected with the power conversion device and parameters of a battery; the control module is further configured to determine whether the power conversion device enters the battery wake-up mode by determining whether to send a control instruction for switching to the battery wake-up mode when the power conversion device enters the battery wake-up mode. After the direct current bus voltage is obtained, the direct current bus voltage and the voltage of the second connecting end of the second power conversion module are controlled to be synchronously increased in response to the fact that the direct current bus voltage is smaller than or equal to a preset bus voltage threshold value.

Specifically, when the power conversion device enters the battery wake-up mode, it is considered that the battery is in a sleep state due to too low power, and the battery needs to be woken up by the input voltage and enter a charging state. In this embodiment, when the battery is awakened, the dc bus voltage of the power conversion device needs to be sampled and obtained first, and when the dc bus voltage is smaller than or equal to the preset bus voltage threshold, it is indicated that the voltage difference between the dc bus and the battery port meets the preset requirement, so that the switching tube in the power conversion module cannot bear the stress caused by the excessive peak voltage. In this case, the control module controls the dc bus voltage to increase in synchronization with the voltage of the second connection terminal of the second power conversion module. The preset bus voltage threshold value can be determined in advance according to an actual application scene, and when the direct current bus voltage is smaller than or equal to the preset bus voltage threshold value, the alternating current power supply can charge the direct current bus at the moment, namely the direct current bus voltage can be increased along with the connection of the alternating current power supply; in one example, when the dc bus voltage is greater than the preset bus voltage threshold, it may be considered that the dc bus voltage is greater at this time, and after the ac power is turned on, the dc bus voltage will continue to increase, so as to bring greater stress impact to components such as a switching tube. In one example, the preset bus voltage threshold may be set according to a power supply parameter of the ac power supply, and different ac power supplies may correspond to different preset bus voltage thresholds, for example, when the ac power supply is a power grid, the preset bus voltage threshold may be a product of a power grid voltage peak value and a preset coefficient k, where 0 < k < 1. In one possible implementation manner, when the dc bus voltage is greater than the preset bus voltage threshold, the first power conversion module and/or the second power conversion module may be controlled to consume dc bus energy first, so that the dc bus voltage is reduced until the dc bus voltage is less than or equal to the preset bus voltage threshold, for example, the first power conversion module may be controlled to perform open-loop modulation, and the dc bus energy is consumed by an energy loop of the inverter bridge, so that the dc bus voltage is reduced below the preset bus voltage threshold and then the battery activation adjustment is performed. In one example, when the voltage of the direct current bus and the voltage of the second connection end of the second power conversion module are controlled to be increased synchronously, that is, when the voltage of the direct current bus is smaller than or equal to a preset bus voltage threshold value, the voltage of the direct current bus and the voltage of the second connection end of the second power conversion module are raised synchronously, so that the voltage difference between the two can be kept within the bearable range of components such as a switch tube all the time, and the components are protected from overlarge impact. When the voltage of the second connection end of the second power conversion module is raised, the voltage control can be realized by controlling the working mode of the second power conversion module, for example, the voltage of the battery port is raised by enabling the second power conversion module to charge the battery port by using the electric energy of the direct current bus.

In one example, the control module may include a sampling unit, a driving unit, and a control unit. The control unit comprises, for example, at least one of a digital signal processor (digital signal processing, DSP), a complex programmable logic device (complex programmable logicdevice, CPLD), a field programmable gate array (field programmable gate array, FPGA), a central processing unit (central processingunit, CPU) or a micro control unit (microcontroller unit, MCU). The sampling unit can collect circuit parameters related in the embodiment, such as the voltage of the direct current bus and the voltage of the second connection end of the second power conversion module. The driving unit is used for driving devices such as a switching tube in the first power conversion module and the second power conversion module to work according to a desired mode according to the driving signals. The control unit can generate corresponding driving signals according to the circuit parameters acquired by the sampling unit.

In the power conversion device, a first connection end of a first power conversion module is electrically connected with an ac power supply through a switch module, a second connection end of the first power conversion module is electrically connected with a first connection end of a second power conversion module through a dc bus, and a second connection end of the second power conversion module is electrically connected with a battery. When the power conversion device determines that the battery enters the wake-up sleep state, the control module acquires the DC bus voltage after determining that the power conversion device enters the battery wake-up mode, and when the DC bus voltage is smaller than or equal to a preset bus voltage threshold value, the control module controls the DC bus voltage and the voltage of the second connecting end of the second power conversion module to synchronously increase, so that the voltage difference between the DC bus voltage and the voltage of the second connecting end of the second power conversion module is always kept at a smaller level, and in the process of rising the DC bus voltage, the voltage is established for the battery port to wake up the battery at the same time, so that the risk of damaging components caused by overlarge voltage difference between the DC bus voltage and the battery port voltage in the wake-up process is reduced, the stability and the safety of the battery charging process are ensured, the reliability of the power conversion device and the battery is improved, and the power conversion device is suitable for more application scenes.

In one embodiment, the control module is further configured to control the switch module to switch to an off state in response to the dc bus voltage being greater than the preset bus voltage threshold, and switch the first power conversion module to a preset operating mode until the dc bus voltage is less than or equal to the preset bus voltage threshold.

In the embodiment of the disclosure, when the dc bus voltage is greater than a preset bus voltage threshold, the switch module is controlled to switch to an off state, and the first power conversion module is switched to a preset working mode until the dc bus voltage is less than or equal to the preset bus voltage threshold. When the voltage of the direct current bus is larger than the preset bus voltage threshold, the direct current bus voltage is considered to be larger at the moment, the alternating current power supply continuously supplies energy to the direct current bus to enable the voltage of the direct current bus to be continuously increased, and then components in the power conversion module bear larger impact stress. At this time, the dc bus energy may be consumed by the first power conversion module. In this embodiment, the switch module is controlled to switch to an off state, that is, the connection between the first power conversion module and the ac power supply 200 is cut off, and the first power conversion module is switched to a preset working mode, where the preset working mode can be set according to the circuit structure and the actual application scenario of the first power conversion module, and when the first power conversion module is in the preset working mode, the energy of the dc bus can be consumed, so that the voltage of the dc bus is reduced. In one example, the first power conversion module includes an inverter bridge, and the preset operation mode may be set to an open loop modulation mode, in which an energy loop of the inverter bridge may consume dc bus energy. In one example, after the first power conversion module switches to the preset operation mode, the dc bus voltage may be continuously obtained, or the dc bus voltage may be periodically obtained, and the obtained dc bus voltage may be compared with a preset bus voltage threshold until the obtained dc bus voltage is less than or equal to the preset voltage threshold. And controlling the direct current bus voltage and the voltage of the second connecting end of the second power conversion module to synchronously increase after the obtained direct current bus voltage is smaller than or equal to a preset voltage threshold.

According to the embodiment of the disclosure, when the DC bus voltage is larger than the preset bus voltage threshold value, the working mode of the first power conversion module is controlled, so that the DC bus energy can be consumed, the DC bus voltage is reduced, synchronous rising of the DC bus voltage and the battery port voltage is realized in the subsequent battery awakening process, the problem that the DC bus voltage cannot be increased due to overhigh DC bus voltage and the voltage difference between the DC bus voltage and the battery port voltage is large due to overhigh DC bus voltage is avoided, the risk of damage to components of the second power conversion module in the battery awakening process is reduced, the reliability and the safety of a power conversion device and a battery are improved, and the service life of the power conversion device is effectively prolonged.

In one embodiment, the control module is further configured to control the power conversion device to enter a battery wake mode upon determining that one or more of the following conditions are met, prior to determining that the power conversion device enters the battery wake mode:

determining the type of the battery as the type of the battery to be awakened;

In embodiments of the present disclosure, the determination may be made by one or more conditions when determining whether the power conversion device enters a battery wake mode.

Specifically, the type of the battery is determined to be the type of the battery needing to be awakened, the corresponding settings of different battery types may have differences, part of the batteries enter a dormant state when the electric quantity is too low, the corresponding battery types are the type of the battery needing to be awakened, the battery may not enter the dormant state when the battery type is the type of the battery not needing to be awakened, no awakening process exists during charging, and the power conversion device does not need to enter the battery awakening mode. In terms of distance, the lithium battery belongs to a battery type that needs to be awakened because the lithium battery has a battery management system BMS that can enter a sleep state. The power conversion apparatus 100 may communicate with the battery 300 to acquire battery type information, or the battery type information may be set in the power conversion apparatus 100 by a user.

Determining that the voltage of the second connection end of the second power conversion module is smaller than or equal to a first preset battery voltage threshold, wherein the second connection end of the second power conversion module is electrically connected with the battery, the voltage of the second connection end can be regarded as the port voltage of the battery, the first preset battery voltage threshold can be set according to an actual application scene, when the voltage of the second connection end of the second power conversion module is smaller than or equal to the first preset voltage threshold, the battery can be considered to be in a dormant state, in one example, the first preset battery voltage threshold can be set to be zero or a voltage value (such as 1V) slightly higher than zero, when the voltage of the second connection end is smaller than or equal to the first preset battery voltage threshold, the battery can be considered to be closed at the moment, and therefore the power conversion device is required to enter a battery wake-up mode to activate the battery.

The method comprises the steps of determining that the output voltage of an alternating current power supply meets preset conditions, wherein the preset conditions can be obtained by setting according to actual application scenes, and when the output voltage of the alternating current power supply meets the preset conditions, the alternating current power supply can be considered to normally output alternating current to a power conversion device to realize a wake-up process. In one example, the preset condition may be set such that the output voltage is within a preset voltage range, and when the output voltage is within the preset voltage range, the ac power output state may be considered to be normal at this time; when the output voltage is out of the preset range, the output voltage is considered to be too high or too low, and the alternating current power supply may be abnormal and cannot be output normally.

Determining that the current working condition of the power conversion device can be used for battery awakening, and when the current working condition of the power conversion device is good and the battery awakening can be performed, enabling the power conversion device to enter a battery awakening mode; when the current working condition of the power conversion device is poor and the working state operation in the battery wake-up process cannot be normally executed, the power conversion device can be considered to be incapable of entering the battery wake-up mode. In one example, operating conditions of the power conversion device may include, but are not limited to, device temperature, device pressure, whether the device is in a shutdown state, whether the device is in a fault state, etc., e.g., when the temperature of the power conversion device is within a preset temperature range, the current operating conditions of the power conversion device may be considered to be capable of battery wakeup. When judging the working condition of the power conversion device, the judging result can be obtained through one device parameter or combining a plurality of device parameters.

When determining whether the power conversion device enters the battery wake-up mode, the power conversion device can be judged through one or more of the conditions, and the power conversion device can be obtained according to actual application scene setting. In one example, it may also be determined whether the power conversion device enters a battery wake mode in conjunction with other decision conditions, which is not limiting of the present disclosure.

According to the embodiment of the disclosure, whether the power conversion device enters the battery wake-up mode or not can be comprehensively determined according to the multi-dimensional factors such as the battery type, the battery port voltage, the alternating current power supply and the working condition of the power conversion device, so that the accuracy and the reliability of the mode switching of the power conversion device are ensured, the power conversion device can be quickly and accurately switched to the battery wake-up mode when the battery is required to be wake-up, and the efficiency and the reliability of battery charging are improved; the method is suitable for various application scenes based on factor judgment of different dimensions, improves the flexibility of mode switching of the power conversion device, adjusts and sets the conditions for entering the wake-up mode according to the application scenes, further improves the reliability and safety of the power conversion device, and ensures the wake-up efficiency of the battery in different scenes; the safety of the battery and the power conversion device in the battery awakening process is ensured through the judgment of the working conditions of the battery, the alternating current power supply and the power conversion device, and the service lives of the battery and the power conversion device are effectively prolonged.

In one embodiment, the control module is configured to control the switch module to switch to a charging state to cause the first power conversion module to boost the dc bus voltage and control the second power conversion module to boost the voltage of the second connection terminal of the second power conversion module in response to the dc bus voltage being less than or equal to a preset bus voltage threshold.

In the embodiment of the disclosure, when the voltage of the direct current bus is smaller than or equal to a preset bus voltage threshold, the switch module is controlled to switch to a charging state, so that the first power conversion module lifts the voltage of the direct current bus and controls the second power conversion module to lift the voltage of the second connecting end of the second power conversion module. When the voltage of the direct current bus is smaller than or equal to a preset bus voltage threshold, the switch module is controlled to be switched to a charging state, namely, the switch module is closed, the alternating current power supply outputs alternating current to the first power conversion module, so that the first power conversion module lifts the voltage of the direct current bus, meanwhile, the working mode of the second power module is controlled, the second power conversion module lifts the voltage of the second connecting end of the second power conversion module, and the simultaneous lifting of the voltage of the direct current bus and the voltage of the second connecting end of the second power conversion module is realized. Because the second connection end of the second power conversion module is electrically connected with the battery, the voltage of the second connection end of the second power conversion module can be regarded as the battery port voltage, and through the embodiment, the direct current bus voltage and the battery port voltage are raised at the same time. The manner of controlling the second power conversion module to raise the voltage of the second connection terminal may be determined according to an actual application scenario, for example, the duty ratio of the driving signal of the second power conversion module may be adjusted to raise the voltage of the second connection terminal.

According to the embodiment of the disclosure, when the voltage of the direct current bus is smaller, the control of the voltage is realized through the control switch module and the second power conversion module, and the simultaneous lifting of the voltage of the direct current bus and the voltage of the second connecting end of the second power conversion module can be rapidly and accurately realized, so that the awakening efficiency of the battery is effectively improved, the risk of damage of components of the second power conversion module due to overlarge stress is reduced, and the realization mode and control logic are simple and are suitable for more application scenes.

In one embodiment, the control module is further configured to control the second power conversion module to switch to the off state and periodically obtain the voltage of the second connection terminal of the second power conversion module in response to the voltage of the second connection terminal of the second power conversion module being greater than or equal to a second preset battery voltage threshold;

In the embodiment of the disclosure, in the process of synchronously raising the voltage of the dc bus and the voltage of the second connection end of the second power conversion module, the control module is further configured to control the second power conversion module to switch to the off state in response to the voltage of the second connection end of the second power conversion module being greater than or equal to a second preset battery voltage threshold, periodically acquire the voltage of the second connection end of the second power conversion module, and in the first preset time, the voltage of the second connection end of the second power conversion module is greater than a third preset battery voltage threshold, so that the battery port voltage of the power conversion device can be considered to be stably established, and at the moment, the BMS of the battery can be awakened and receive the charge of the power conversion device under the condition that the voltage signal is acquired. In one possible implementation, when the voltage of the second connection terminal of the second power conversion module is less than the second preset battery voltage threshold, the operation mode of the second conversion module may be adjusted to continuously raise the voltage of the second connection terminal, and in one example, the driving signal duty ratio of the second power conversion module may be increased in a step manner. In one example, in response to the voltage of the second connection of the second power conversion module being greater than or equal to a second preset battery voltage threshold, the first power conversion module and the second power conversion module are controlled to operate according to a normal charging strategy; when the second power conversion module is turned off and the voltage of the second connection end of the second power conversion module is still smaller than the third preset battery voltage in the first preset time, the first power conversion module and the second power conversion module are controlled to continue to operate according to the normal charging strategy until the voltage of the second connection end of the second power conversion module is larger than the third preset battery voltage threshold in the first preset time, for example, the second power conversion module can be switched to be in a turned-off state according to a preset period, and the voltage of the second connection end is detected and judged; the time for switching the second power conversion module to the off state can also be set according to the circuit parameter value in the actual application scene.

In one possible implementation manner, when the voltage of the second connection end of the second power conversion module is still less than or equal to the third preset battery voltage threshold within the first preset time, the second power conversion module may be continuously controlled to raise the voltage of the second connection end, and in one example, when the raising is continuously controlled, the duty ratio of the driving signal of the second power conversion module may be adjusted up, and the voltage of the second connection end of the second power conversion module may be monitored and judged until the voltage of the second connection end of the second power conversion module is greater than the third preset battery voltage threshold within the first preset time.

The second preset battery voltage threshold and the third preset battery voltage threshold may be determined in advance according to an actual application scenario and battery parameters of the battery, where the second preset battery voltage threshold is smaller than the third preset battery voltage threshold. When the voltage of the second connection terminal is greater than or equal to the second preset battery voltage threshold, it may be considered that the battery port voltage has already met the voltage condition capable of normal charging at this time, in an example, the second preset battery voltage threshold may be set to the rated charging voltage of the battery, and when the voltage of the second connection terminal of the second power conversion module is raised to the rated charging voltage of the battery, the battery port voltage meets the voltage condition capable of normal charging; further, the second preset battery voltage threshold can be set to be the difference between the rated charging voltage and the preset buffer voltage of the battery, according to practical application scenes, the second preset battery voltage threshold can be set to be a value slightly smaller than the rated charging voltage, so that the voltage difference between the direct-current bus voltage and the battery port voltage can be kept at a smaller level, a battery charging loop can be built to start charging more quickly, the efficiency of waking up the battery to the state of charge switching is effectively improved, and the battery charging efficiency is guaranteed. And when the voltage of the second connecting end of the second power conversion module is larger than or equal to a second preset battery voltage threshold value, closing the second power conversion module, and further judging whether the battery port voltage meets the condition or not, thereby determining whether the battery is awakened or not. After the second power conversion module is closed, the voltage of the second connection end of the second power conversion module is periodically obtained, when the voltage of the second connection end of the second power conversion module is larger than a third preset battery voltage threshold value in a first preset time, the battery can be determined to be awakened at the moment, normal charging can be performed, a battery awakening mode is exited, and the battery is started to be charged. In one example, the third preset battery voltage threshold may be set to an under-voltage protection value of the battery, and when the acquired voltage of the second connection terminal is greater than the third preset battery voltage threshold in the first preset time, the battery port voltage may be considered to be greater than the third preset battery voltage threshold in the first preset time, and the battery is already awakened and is not in an under-voltage sleep state. In this embodiment, the first preset time may be determined according to an actual application scenario, and in one example, the first preset time may be determined based on whether the battery is awakened or not according to an actual application scenario, for example, a period of time of a preset duration from when the second power conversion module is switched to the off state may be set as the first preset time.

According to the embodiment of the disclosure, when the direct current bus voltage and the voltage of the second connecting end of the second power conversion module are controlled to rise, the battery state is judged according to the voltage of the second connecting end and the second preset battery voltage threshold value, the second power conversion module is closed, whether the condition of exiting the battery awakening mode is met or not is further determined by combining the third preset battery voltage threshold value, the implementation mode is simple, the method is suitable for more application scenes, accurate judgment of the battery state can be achieved, the working state and the working mode of the second power conversion module are adjusted according to the voltage of the second connecting end, and therefore the battery is switched to a normal charging state to charge after awakening the battery.

In one embodiment, the control module is further configured to, in response to the voltage of the second connection terminal of the second power conversion module being less than or equal to a fourth preset battery voltage threshold for a second preset time, exit the battery wake-up mode, and/or send an abnormality alert signal, where the fourth preset battery voltage threshold is less than the second preset battery voltage threshold.

In this embodiment of the present disclosure, the control module is further configured to control to exit from the battery wake-up mode in response to the voltage of the second connection end of the second power conversion module being less than or equal to the fourth preset battery voltage threshold in the second preset time, and in one example, may further send an abnormal alarm signal to prompt related personnel to perform timely processing. In this embodiment, the fourth preset battery voltage threshold may be set according to an actual application scenario, where the fourth preset battery voltage threshold is smaller than the second preset battery voltage threshold, and when the voltage of the second connection end of the second power conversion module is smaller than or equal to the fourth preset battery voltage threshold in the second preset time, it may be considered that there is an abnormality at this time, and the abnormality type may include, but is not limited to, a power conversion device fault, a battery fault, an ac power supply fault, and the like. In one example, the fourth preset battery voltage threshold may be set to zero or a small voltage value near zero (e.g., 1V), and so on. In one example, the anomaly type may be further determined in combination with other parameters in the circuit. The second preset time may be set according to an actual application scenario, in an example, the second preset time may include one or more preset time periods, for example, a time period between when the second power conversion module is switched to a closed state and when the voltage of the second connection end of the second power conversion module continues to rise is taken as a preset time period, and when the voltage of the second connection end of the second power conversion module in the multiple preset time periods is less than or equal to a fourth preset battery voltage threshold in the second preset time period, the battery wake-up mode is exited; the second preset time may also be set to a time for the power conversion module to enter the battery wake-up mode for a preset duration. The transmission mode and the signal content of the abnormality alarm signal may be set according to an actual application scenario, for example, the abnormality alarm signal may include a sound signal, an optical signal, and the like, and in one example, the abnormality alarm signal may also be transmitted to the target terminal through a communication connection.

According to the embodiment of the disclosure, when the voltage of the second connection end of the second power conversion module is not consistent with the charging condition all the time within the second preset time, the abnormality can be considered to exist, the battery wake-up mode is exited, the energy waste is avoided, the risk of device damage caused by the failure is reduced, the safety and the reliability of the power conversion device and the battery are improved, and the power conversion device and the battery are suitable for more application scenes; by sending the abnormal alarm signal, related personnel can be timely prompted to timely process, timeliness of abnormality removal and fault repair is improved, and safety risk problems caused by untimely fault discovery are avoided.

The various modules in the power conversion apparatus described above may be implemented in whole or in part by software, hardware, and combinations thereof. The above modules may be embedded in hardware or may be independent of a processor in the computer device, or may be stored in software in a memory in the computer device, so that the processor may call and execute operations corresponding to the above modules.

Based on the same inventive concept, the embodiments of the present application further provide a method for controlling a power conversion device using the power conversion device, where the implementation of the method for solving the problem is similar to the implementation described in the device, so specific limitations in the embodiments of the method for controlling one or more power conversion devices provided below may be referred to the above limitations of the power conversion device, and will not be repeated herein. In one example, the control method of the power conversion apparatus is applied to the control module.

In one embodiment, as shown in fig. 3, there is provided a control method of a power conversion apparatus including: the power conversion device comprises a switch module, a first power conversion module, a second power conversion module and a control module; the first connecting end of the first power conversion module is electrically connected with an alternating current power supply through the switch module, the second connecting end of the first power conversion module is electrically connected with the first connecting end of the second power conversion module through a direct current bus, and the second connecting end of the second power conversion module is electrically connected with a battery;

the method comprises the following steps:

step S310, after determining that the power conversion device enters a battery wake-up mode, obtaining a DC bus voltage;

step S320, in response to the dc bus voltage being less than or equal to a preset bus voltage threshold, controlling the dc bus voltage and the voltage of the second connection terminal of the second power conversion module to increase synchronously.

In one embodiment, as shown in fig. 4, the method further comprises:

step S312, in response to the dc bus voltage being greater than the preset bus voltage threshold, controls the switch module to switch to an off state, and switches the first power conversion module to a preset operation mode until the dc bus voltage is less than or equal to the preset bus voltage threshold.

In one embodiment, as shown in fig. 5, the method further comprises:

step S330, in response to the voltage of the second connection end of the second power conversion module being greater than or equal to a second preset battery voltage threshold, controlling the second power conversion module to switch to a closed state;

step S340, periodically acquiring a voltage of the second connection end of the second power conversion module;

and step 350, in response to the voltages of the second connection terminals of the second power conversion modules being greater than a third preset battery voltage threshold within the first preset time, exiting the battery wake-up mode and starting to charge the battery, wherein the second preset battery voltage threshold is smaller than the third preset battery voltage threshold.

determining the type of the battery as the type of the battery to be awakened;

In one embodiment, the method further comprises:

Fig. 6 is a flowchart of a control method of a power conversion device according to an exemplary embodiment, and referring to fig. 6, whether a wake-up condition is satisfied is determined according to a preset determination condition of a battery wake-up mode, if the wake-up condition is satisfied, a wake-up process is entered, and if the wake-up condition is not satisfied, the process is ended. Step 1, obtaining a direct current bus voltage Vbus, and judging whether the direct current bus voltage is smaller than or equal to a preset bus voltage threshold value; if yes, the fact that the bus voltage can be built at the moment is indicated, and step 2 is executed, so that the direct-current bus voltage and the voltage of the second connecting end of the second power conversion module are synchronously increased; if not, it is indicated that the dc bus voltage is too high at this time, which may cause the ac power source to fail to charge the dc bus, so step 6 is performed until the dc bus voltage is less than or equal to the preset bus voltage threshold. And 2, closing the switch module to enable the switch module to be switched to a charging state, so that the alternating current power supply charges the direct current bus, and simultaneously driving the second power conversion module to operate according to a set duty ratio so as to charge the battery port. Step 3, continuously obtaining the battery port voltage (i.e. the voltage of the second connection end of the second power conversion module) Vbat, judging whether the voltage is greater than or equal to a second preset battery voltage threshold, in one example, the second preset battery voltage threshold=target value-buffer value, the target value is the rated charging voltage of the battery, the buffer value can be set by itself, as long as a stable charging voltage can be established without causing excessive stress to components, and the charging loop can be established earlier by reserving the buffer value; if the voltage of the second power conversion module is greater than the second preset battery voltage threshold, controlling the second power conversion module to operate according to normal charging logic, for example, performing voltage loop and current loop double-loop modulation (i.e. modulating according to the voltage and current of the battery port), and executing the step 4; if the voltage is still smaller than the second preset battery voltage threshold, step 5 is executed. Step 4, after the battery port voltage Vbat is operated for a period of time according to the normal charging logic, the second power conversion module is turned off, and whether the battery port voltage Vbat is greater than a third preset battery voltage threshold is detected, wherein in one example, the third preset battery voltage threshold may be set to a battery under-voltage protection value, if so, it is indicated that the battery has been awakened, and the battery can be exited from the battery awakening mode for normal charging; if not, the normal charging logic operation is continued, and the judgment is carried out after the port voltage is kept waiting for a period of time to rise. Step 5, if the battery port voltage Vbat is still less than or equal to the third preset battery voltage threshold value within the first preset time, gradually increasing the duty ratio of the driving signal of the second power conversion module according to the set step value until Vbat is greater than the third preset battery voltage threshold value; if the Vbat value is measured repeatedly (e.g., within the second preset time) to be less than or equal to the fourth preset battery voltage threshold, it indicates that there is an abnormality, and the battery wake-up mode is exited and an error is reported, and in one example, the fourth battery voltage threshold may be set to 1V, which indicates that the inverter is abnormal, and the wake-up function is exited and an error is reported. Step 6, under the condition that the voltage of the direct current bus is higher, the bus voltage needs to be reduced below a preset bus voltage threshold value, the control switch module is switched to an off state, a loop between the first power conversion module and the alternating current power supply is cut off, the first power conversion module is switched to a preset working mode, the direct current bus energy is consumed, in one example, the first power conversion module is realized based on an inverter bridge, and the process can be realized by the following steps: and (3) carrying out open-loop modulation on the first power conversion module (namely the inverter bridge), consuming the energy of the direct current bus by using an energy loop of the inverter bridge, reducing the Vbus, and returning to the judgment flow in the step (1) until the Vbus is smaller than or equal to a preset direct current bus threshold value.

Fig. 7 is a waveform diagram of each voltage during battery wake-up in the conventional technology according to an exemplary embodiment, and fig. 8 is a waveform diagram of each voltage during battery wake-up after the method according to the embodiment. Referring to fig. 7, in the conventional technology, a dc bus voltage is first established, and then a battery wake-up process is started, in the battery wake-up process, a larger voltage difference exists between a battery port voltage and the dc bus voltage, so that a stress on components is larger, the components are maximally subjected to a peak voltage of 880V, and a larger damage risk exists. Referring to fig. 8, after the embodiment is adopted, in the process of waking up the battery, the voltage difference between the voltage of the direct current bus and the voltage of the battery port is maintained at a smaller level, the stress on components is smaller, the maximum peak voltage of the components needs to bear 370V is obviously smaller than that of fig. 7, the risk of damage to the components is greatly reduced, and the safety and reliability of the power conversion device and the battery are improved.

Fig. 9 is a waveform diagram of voltages in a battery awakening process when a dc bus voltage is too high, and referring to fig. 9, when the dc bus voltage is high, a voltage difference between the dc bus voltage and a battery port voltage is large, the dc bus energy is firstly consumed through a first power conversion module, the dc bus voltage is reduced, when the dc bus voltage is less than or equal to a preset bus voltage threshold value, the dc bus voltage and the battery port voltage are controlled to be lifted synchronously, so that impact caused by the large voltage difference due to the too high dc bus voltage is effectively avoided, the risk of damage to components is greatly reduced, and the safety and reliability of the power conversion device and the battery are improved.

It should be understood that, although the steps in the flowcharts related to the embodiments described above are sequentially shown as indicated by arrows, these steps are not necessarily sequentially performed in the order indicated by the arrows. The steps are not strictly limited to the order of execution unless explicitly recited herein, and the steps may be executed in other orders. Moreover, at least some of the steps in the flowcharts described in the above embodiments may include a plurality of steps or a plurality of stages, which are not necessarily performed at the same time, but may be performed at different times, and the order of the steps or stages is not necessarily performed sequentially, but may be performed alternately or alternately with at least some of the other steps or stages.

Embodiments of the present disclosure also provide an energy storage system comprising a power conversion device and a battery according to any one of the embodiments of the present disclosure, where the power conversion device converts direct current from the battery into alternating current for delivery to a power grid or load, or converts alternating current from the alternating current power source into direct current for charging the battery.

In one exemplary embodiment, a computer device is provided, which may be a server, and the internal structure thereof may be as shown in fig. 10. The computer device includes a processor, a memory, an Input/Output interface (I/O) and a communication interface. The processor, the memory and the input/output interface are connected through a system bus, and the communication interface is connected to the system bus through the input/output interface. Wherein the processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, computer programs, and a database. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage media. The database of the computer device is used for storing data related to the embodiment, such as dc bus voltage data. The input/output interface of the computer device is used to exchange information between the processor and the external device. The communication interface of the computer device is used for communicating with an external terminal through a network connection. The computer program is executed by a processor to implement a method of controlling a power conversion device.

It will be appreciated by those skilled in the art that the structure shown in fig. 10 is merely a block diagram of some of the structures associated with the present application and is not limiting of the computer device to which the present application may be applied, and that a particular computer device may include more or fewer components than shown, or may combine certain components, or have a different arrangement of components.

In an embodiment, there is also provided a computer device comprising a memory and a processor, the memory having stored therein a computer program, the processor implementing the steps of the method embodiments described above when the computer program is executed.

In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored which, when executed by a processor, carries out the steps of the method embodiments described above.

In an embodiment, a computer program product is provided, comprising a computer program which, when executed by a processor, implements the steps of the method embodiments described above.

The foregoing embodiment numbers of the present application are merely for describing, and do not represent advantages or disadvantages of the embodiments.

In this application, the same or similar term concept, technical solution, and/or application scenario description will generally be described in detail only when first appearing, and when repeated later, for brevity, will not generally be repeated, and when understanding the content of the technical solution of the present application, etc., reference may be made to the previous related detailed description thereof for the same or similar term concept, technical solution, and/or application scenario description, etc., which are not described in detail later.

In this application, the descriptions of the embodiments are focused on, and the details or descriptions of one embodiment may be found in the related descriptions of other embodiments.

The technical features of the technical solutions of the present application may be arbitrarily combined, and for brevity of description, all possible combinations of the technical features in the above embodiments are not described, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the present application.

From the above description of the embodiments, it will be clear to those skilled in the art that the above-described embodiment method may be implemented by means of software plus a necessary general hardware platform, but of course may also be implemented by means of hardware, but in many cases the former is a preferred embodiment. Based on such understanding, the technical solution of the present application may be embodied essentially or in a part contributing to the prior art in the form of a software product stored in a storage medium (e.g. ROM/RAM, magnetic disk, optical disk) as above, comprising several instructions for causing an electronic device to perform the method of each embodiment of the present application.

The foregoing description is only of the preferred embodiments of the present application, and is not intended to limit the scope of the claims, and all equivalent structures or equivalent processes using the descriptions and drawings of the present application, or direct or indirect application in other related technical fields are included in the scope of the claims of the present application.

Claims

1. A power conversion device, the power conversion device comprising: the power conversion device comprises a switch module, a first power conversion module, a second power conversion module and a control module; the first connecting end of the first power conversion module is electrically connected with an alternating current power supply through the switch module, the second connecting end of the first power conversion module is electrically connected with the first connecting end of the second power conversion module through a direct current bus, and the second connecting end of the second power conversion module is electrically connected with a battery;

the control module is used for acquiring the voltage of the direct current bus after determining that the power conversion device enters a battery wake-up mode; and the voltage of the second connecting end of the second power conversion module is synchronously increased, wherein the voltage of the direct current bus is controlled to be smaller than or equal to a preset bus voltage threshold value; the control module is further configured to control the switch module to switch to an off state in response to the dc bus voltage being greater than the preset bus voltage threshold, and switch the first power conversion module to a preset working mode until the dc bus voltage is less than or equal to the preset bus voltage threshold.

2. The power conversion device of claim 1, wherein the control module, prior to determining that the power conversion device enters the battery wake mode, is further configured to control the power conversion device to enter the battery wake mode upon determining that one or more of the following conditions are met:

determining the type of the battery as the type of the battery to be awakened;

3. The power conversion device according to claim 1, wherein the control module is configured to control the switch module to switch to a charging state to cause the first power conversion module to boost the dc bus voltage and control the second power conversion module to boost the voltage of the second connection terminal of the second power conversion module in response to the dc bus voltage being less than or equal to a preset bus voltage threshold.

4. The power conversion device according to claim 1, wherein the control module is further configured to control the second power conversion module to switch to an off state and periodically obtain the voltage of the second connection terminal of the second power conversion module in response to the voltage of the second connection terminal of the second power conversion module being greater than or equal to a second preset battery voltage threshold;

5. The power conversion device of claim 4, wherein the control module is further configured to exit the battery wake mode and/or send an abnormality alert signal in response to the voltage at the second connection of the second power conversion module being less than or equal to a fourth preset battery voltage threshold for a second preset time, wherein the fourth preset battery voltage threshold is less than the second preset battery voltage threshold.

6. A control method of a power conversion apparatus, characterized in that the power conversion apparatus includes: the power conversion device comprises a switch module, a first power conversion module, a second power conversion module and a control module; the first connecting end of the first power conversion module is electrically connected with an alternating current power supply through the switch module, the second connecting end of the first power conversion module is electrically connected with the first connecting end of the second power conversion module through a direct current bus, and the second connecting end of the second power conversion module is electrically connected with a battery;

The method comprises the following steps:

controlling the direct current bus voltage and the voltage of the second connecting end of the second power conversion module to synchronously increase in response to the direct current bus voltage being smaller than or equal to a preset bus voltage threshold;

the method further comprises the steps of: and controlling the switch module to switch to an off state in response to the direct current bus voltage being greater than the preset bus voltage threshold, and switching the first power conversion module to a preset working mode until the direct current bus voltage is less than or equal to the preset bus voltage threshold.

7. The control method according to claim 6, characterized in that the method further comprises:

8. An energy storage system comprising a power conversion device according to any one of claims 1 to 5 and a battery, the power conversion device converting dc power from the battery to ac power for delivery to a grid or load, or converting ac power from the ac power source to dc power for charging the battery.