Energy conversion device, inverter device, and energy conversion system

Abstract

An energy conversion device, an inverter device, and an energy conversion system. The energy conversion device at least comprises: a first transmission interface, comprising a battery connection terminal adapted to be connected to a battery pack; a second transmission interface, configured to be at least capable of accessing an alternating-current power grid; an energy conversion circuit, which can at least convert electric energy input by the first transmission interface and then feed the converted electric energy to the second transmission interface; and a controller, which is at least in communication connection with the first transmission interface and is electrically connected to the energy conversion circuit, wherein the controller is configured to at least control, when the temperature of the battery pack is less than or equal to a temperature threshold, the energy conversion circuit to perform energy conversion on the energy input by the first transmission interface, so that the battery pack at least obtains heat energy for heating.

Description

Energy conversion device, inverter device and energy conversion system

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on November 24, 2023, with application number 202311589105.0, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to a low-temperature processing technology for an energy device, for example, to an energy conversion device, an inverter device and an energy conversion system. Background Art

[0003] With the advancement of battery technology, DC power tools are gradually replacing engine tools. As the power source for DC power tools, battery performance directly affects their performance. In particular, in low-temperature environments, lithium batteries experience deteriorating power characteristics, reduced cycle life, and reduced usable capacity, impacting the user experience of power tools in winter. Furthermore, these batteries face safety issues such as difficulty charging at low temperatures and the potential for lithium deposition during DC charging.

[0004] This section provides background information related to the present application which is not necessarily prior art. Summary of the Invention

[0005] One object of the present application is to solve or at least alleviate part or all of the above problems. To this end, one object of the present application is to provide an energy conversion device that can achieve low-temperature heating of a battery pack.

[0006] In order to achieve the above objectives, this application adopts the following technical solutions:

[0007] An energy conversion device comprises at least: a first transmission interface, comprising a battery connection terminal suitable for connecting to a battery pack; a second transmission interface, configured to at least be able to access an AC power grid; an energy conversion circuit, capable of at least converting the electrical energy input by the first transmission interface and feeding it to the second transmission interface; a controller, communicatively connected to at least the first transmission interface and electrically connected to the energy conversion circuit; wherein the controller is configured to: when the temperature of the battery pack is less than or equal to a temperature threshold, at least control the energy conversion circuit to convert the energy input by the first transmission interface so that the battery pack obtains at least heating thermal energy.

[0008] In some embodiments, the electric energy conversion circuit includes: an inverter circuit, configured to invert the electric energy input from the first transmission interface and feed it to the AC power grid at least when the temperature of the battery pack is less than or equal to the temperature threshold.

[0009] In some embodiments, the inverter circuit is further configured to convert the electric energy input from the second transmission interface into electric energy for charging the battery pack.

[0010] In some embodiments, the electric energy conversion circuit includes: a heating circuit, which is electrically coupled to at least the first transmission interface; the controller is configured to control the heating circuit to operate in a first operating mode when the temperature of the battery pack is less than or equal to the temperature threshold, so that the battery pack can at least obtain heating thermal energy.

[0011] In some embodiments, the heating circuit includes a plurality of switching elements; and the controller is configured to control the switching elements to change conduction states to change the transmission direction of the electrical energy at the first transmission interface at least twice in the first operating mode.

[0012] In some embodiments, the heating circuit further includes an energy storage element, which is configured to store the electrical energy released by the battery pack and transmit the stored electrical energy to the battery pack.

[0013] In some embodiments, the controller is configured to at least control the energy conversion circuit to convert energy input from the second transmission interface to charge the battery pack when the temperature of the battery pack is greater than the temperature threshold.

[0014] In some embodiments, the controller is configured to, when the temperature of the battery pack is greater than the temperature threshold, control the heating circuit to operate in a second operating mode so that the battery pack obtains charging power.

[0015] An energy conversion system includes a battery pack, an AC power grid and an energy conversion device; the battery pack is configured to be coupled to an electric tool to power the electric tool; the energy conversion device is configured to be connected to the battery pack and the AC power grid, and to convert the electric energy input by the battery pack and feed it to the AC power grid; wherein, when the temperature of the battery pack is less than or equal to a temperature threshold, the energy device can convert the energy input by the battery pack so that the battery pack obtains at least heating heat energy.

[0016] In some embodiments, when the temperature of the battery pack is less than or equal to a temperature threshold, the energy device converts the electrical energy input from the battery pack and feeds it to the AC power grid, so that the battery pack obtains heating energy.

[0017] In some embodiments, when the temperature of the battery pack is less than or equal to a temperature threshold, the energy device changes the transmission direction of electrical energy between the battery pack and the energy device at least twice so that the battery pack obtains heating energy.

[0018] An inverter device comprises at least: a first transmission interface, comprising battery connection terminals suitable for connecting to a battery pack; a second transmission interface, configured to at least be able to access an AC power grid; an inverter circuit, arranged between the first transmission interface and the second transmission interface, and having multiple operating modes; a heating circuit, arranged between the first transmission interface and the inverter circuit, and having multiple operating modes; a controller, electrically connected to at least the inverter circuit and the heating circuit; the controller being configured to: when the temperature of the battery pack is less than or equal to a temperature threshold, control the inverter circuit and / or the heating circuit to convert energy input from the first transmission interface so that the battery pack obtains at least heating heat energy.

[0019] In some embodiments, when the temperature of the battery pack is less than or equal to the temperature threshold, the heating circuit operates in a first operating mode, and the inverter circuit is in a disconnected state, so that the battery pack can obtain heating energy.

[0020] In some embodiments, when the temperature of the battery pack is greater than the temperature threshold, the heating circuit operates in a second operating mode, and the inverter circuit has at least a rectification mode, so that the battery pack obtains charging power.

[0021] In some embodiments, when the temperature of the battery pack is less than or equal to the temperature threshold, the heating circuit operates in a third operating mode, and the inverter circuit has at least an inverter mode, so that the battery pack can be fed into the AC power grid.

[0022] An energy conversion device includes a DC / DC charger, wherein one side of the DC / DC charger is connected to a battery pack and the other side is connected to another battery pack; a temperature detection module is provided in the DC / DC charger to detect the temperature of the battery pack connected thereto. When the temperature of the battery pack is less than or equal to a temperature threshold, the battery pack on one side of the DC / DC charger can be controlled to discharge and the battery pack on the other side to charge, and the reverse can be reversed after a preset time.

[0023] In some embodiments, the battery packs connected to both sides of the DC / DC charger are of the same type.

[0024] In some embodiments, the battery packs connected to both sides of the DC / DC charger are of different types. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG1 is a schematic diagram of an energy conversion system according to an embodiment of the present application;

[0026] FIG2 is a schematic diagram of the internal circuit structure of the energy conversion device in an embodiment of the present application;

[0027] FIG3 is a schematic diagram of the internal circuit structure of the energy conversion device in an embodiment of the present application;

[0028] 4a to 4d are schematic diagrams of circuit transformations during heating of a battery pack by an energy conversion device in one embodiment of the present application;

[0029] 5a to 5h are schematic diagrams of circuit transformations during heating of a battery pack by an energy conversion device in another manner according to an embodiment of the present application;

[0030] 5i to 5p are schematic diagrams of circuit transformations during charging of a battery pack by an energy conversion device in one embodiment of the present application;

[0031] FIG6 is a schematic diagram of a module for mutual heating between battery packs in one embodiment of the present application;

[0032] FIG7 is a schematic diagram of a charger circuit for achieving mutual heating between battery packs in one embodiment of the present application;

[0033] FIG8 is a schematic diagram of a portion of an electric tool used with a battery pack according to an embodiment of the present application. DETAILED DESCRIPTION

[0034] Before any embodiments of the present application are explained in detail, it is to be understood that the application is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the foregoing drawings.

[0035] In this application, the terms "comprises," "includes," "has," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not preclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0036] In this application, the term "and / or" describes a relationship between related objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Additionally, the character " / " in this application generally indicates that the related objects are in an "and / or" relationship.

[0037] In this application, the terms "connect," "combine," "couple," and "install" may refer to direct connection, combination, coupling, or installation, or indirect connection, combination, coupling, or installation. For example, a direct connection refers to two parts or components being connected together without an intermediary, and an indirect connection refers to two parts or components being connected to at least one intermediary, with the two parts or components being connected via the intermediary. Furthermore, "connect" and "couple" are not limited to physical or mechanical connections or couplings and may include electrical connections or couplings.

[0038] In this application, it will be understood by those skilled in the art that relative terms (e.g., "about," "approximately," "substantially," etc.) used in conjunction with quantities or conditions include the values ​​and have the meaning indicated by the context. For example, the relative terms include at least the degree of error associated with the measurement of a specific value, the tolerance caused by manufacturing, assembly, use, etc. associated with a specific value. Such terms should also be considered to disclose a range defined by the absolute values ​​of the two endpoints. Relative terms may refer to plus or minus a certain percentage (e.g., 1%, 5%, 10% or more) of the indicated value. Numerical values ​​that do not use relative terms should also be disclosed as specific values ​​with tolerances. In addition, "substantially" may refer to plus or minus a certain degree (e.g., 1 degree, 5 degrees, 10 degrees or more) on the basis of the indicated angle when expressing a relative angular position relationship (e.g., substantially parallel, substantially perpendicular).

[0039] In this application, it will be understood by those skilled in the art that the function performed by an assembly can be performed by one assembly, multiple assemblies, one part, or multiple parts. Similarly, the function performed by a part can also be performed by one part, one assembly, or a combination of multiple parts.

[0040] In the present application, the terms "upper", "lower", "left", "right", "front", "back" and other directional words are described based on the orientation and positional relationship shown in the accompanying drawings, and should not be understood as limiting the embodiments of the present application. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to the other element "upper" or "lower", but also be indirectly connected to the other element "upper" or "lower" through an intermediate element. It should also be understood that directional words such as upper side, lower side, left side, right side, front side, back side, etc. not only represent the positive orientation, but can also be understood as the lateral orientation. For example, below can include directly below, lower left, lower right, lower front and lower back, etc.

[0041] In this application, the terms "controller," "processor," "central processing unit," "CPU," and "MCU" are used interchangeably. Where a unit "controller," "processor," "central processing unit," "CPU," or "MCU" is used to perform a particular function, unless otherwise specified, the function may be performed by a single unit or multiple units.

[0042] In this application, the terms "device", "module" or "unit" can be implemented in the form of hardware or software to achieve specific functions.

[0043] In this application, the terms "calculate", "judge", "control", "determine", "identify", etc. refer to the operations and processes of a computer system or similar electronic computing device (e.g., controller, processor, etc.).

[0044] In this application, the energy conversion device 10 may also be referred to as a bidirectional power supply device, a bidirectional inverter, an inverter device, an adapter, a charger, etc. In this embodiment, the energy conversion device 10 has at least a first transmission interface 101 connected to the battery connection terminals of the battery pack 20, and a second transmission interface 102 connected to the AC power grid 30. In other embodiments, the energy conversion device 10 may further include a third transmission interface capable of connecting to a power tool.

[0045] In one embodiment, the energy conversion device 10 can act as a charger, converting the AC power provided by the AC power grid 30 to charge the battery pack 20. The conversion can include rectification, filtering, step-up or step-down conversions. In one embodiment, the energy conversion device 10 can act as an inverter, converting the electrical energy input by the battery pack 10 and feeding it to the AC power grid 30. The energy conversion can include inversion, filtering, step-up or step-down conversions. In one embodiment, the energy conversion device 10 can also act as an adapter to supply the electrical energy provided by the battery pack 20 to an AC power tool, or it can convert the electrical energy provided by the AC power grid 30 to power a DC power tool.

[0046] In this embodiment, the AC power grid 30 may include a power grid with a standard voltage of 100V or greater and 600V or less, as is standard in various countries. For example, it may be an AC power grid of approximately 110V, or approximately 220V, or approximately 240V, or approximately 380V, etc., which are not listed here. In other embodiments, the AC power grid 30 may also include a photovoltaic power grid, i.e., a power grid generated by solar power.

[0047] In one embodiment, the energy conversion device 10 , the battery pack 20 , and the AC power grid 30 may constitute the energy conversion system 100 shown in FIG. 1 .

[0048] In this embodiment, after the battery pack 20 is connected to the energy conversion device 10 via the first transmission interface 101, it can not only transmit electrical energy but also transmit communication data to the energy conversion device 10. The communication data includes at least the temperature of the battery pack 20, such as the temperature around the battery cells in the battery pack 20, the temperature within the battery pack 20, the temperature inside the battery cells in the battery pack 20, or the ambient temperature around the battery pack 20. The energy conversion device 10 can at least change its internal energy conversion method or energy conversion process based on the temperature data transmitted by the battery pack 20.

[0049] 2 , the energy conversion device 10 may include at least an energy conversion circuit 11 and a controller 12 capable of controlling the operating state of the energy conversion circuit 11. In this embodiment, the controller 12 may be communicatively connected to at least the first transmission interface 101 to receive communication data transmitted by the battery pack 20 via the first transmission interface 101.

[0050] When the controller 12 determines that the temperature of the battery pack 20 is less than or equal to the temperature threshold, it can be considered that the battery pack 20 is in a low temperature environment. At this time, if the battery pack 20 is charged or discharged, it may be difficult to charge due to the low temperature or affect the battery cycle life or other safety issues.

[0051] To avoid the aforementioned issues, the controller 12 can control the energy conversion circuit 11 to change its circuit state based on the temperature of the battery pack 20, at least preventing the battery pack 20 from charging or discharging. In this embodiment, the controller 12 can also control the energy conversion circuit 11 to convert energy input from the first transmission interface 101 based on the temperature of the battery pack 20, so that the battery pack 20 can at least obtain thermal energy for heating. In other words, the energy conversion device 10 can heat the battery pack 20 through energy conversion at least when the temperature of the battery pack 20 is relatively low, for example, below a temperature threshold.

[0052] In one embodiment, the energy conversion circuit 11 can include at least an inverter circuit 111. The inverter circuit 111 is provided between the first transmission interface 101 and the second transmission interface 102. The inverter circuit 111 can have multiple operating modes, thereby enabling the energy conversion device 10 to have multiple energy conversion states.

[0053] In one implementation, the controller 12 can control the inverter circuit 111 to operate in an inverter mode when the temperature of the battery pack 20 is less than or equal to a temperature threshold, so that the energy conversion device 10 can obtain electrical energy from the battery pack 20 and feed the converted energy to the AC power grid 30. During the process of the battery pack 20 feeding power to the AC power grid 30 through the energy conversion device 10, the internal resistance within the battery pack 10 will generate heat and generate thermal energy, thereby increasing the temperature of the battery pack 20. After the temperature of the battery pack 20 increases to greater than the temperature threshold, the controller 12 can control the inverter circuit 111 to operate in a rectifier mode or control the inverter circuit 111 to be in a disconnected state. Specifically, when the inverter circuit 111 is in the rectifier mode, the energy conversion device 10 can obtain charging power from the AC power grid 30, and perform rectification, filtering, and other conversions on the power to charge the battery pack 20. When the inverter circuit 111 is in the disconnected state, at least the electrical connection between the energy conversion device 10 and the AC grid 30 is disconnected. When the inverter circuit 111 is disconnected, energy cannot be fed to the AC grid 30, nor can it obtain electrical energy from the AC grid.

[0054] In one embodiment, the energy conversion circuit 11 may further include a heating circuit 112, which is electrically coupled to at least the first transmission interface 101. In this embodiment, the heating circuit 112 is connected between the first transmission interface 101 and the inverter circuit 111 and can have multiple operating modes. In different operating modes, the energy conversion device 10 can have different energy conversion functions.

[0055] In one implementation, the controller 12 can control the heating circuit 112 to operate in a first operating mode and control the inverter circuit 111 to be in a disconnected state when the temperature of the battery pack 20 is less than or equal to a temperature threshold, thereby enabling the battery pack 20 to obtain heat energy. In this embodiment, because the inverter circuit 111 is disconnected, the heating circuit 112 in the first operating mode cannot transmit the electrical energy transmitted by the battery pack 20 to the rear inverter circuit 111 or to the AC power grid 30. In this case, the heating circuit 112 can convert the transmission direction or amount of electrical energy, or store or release the electrical energy transmitted by the battery pack 20. In this implementation, the electrical energy transmitted from the battery pack 20 to the energy conversion device 10 undergoes at least two changes in current transmission direction within the heating circuit 112, thereby enabling the battery pack 20 to be charged and discharged at least once. Before the temperature of the battery pack 20 reaches the temperature threshold, the heating circuit 112 can control the cyclic charge and discharge of the battery pack 20 itself based on the electric energy transmitted from the battery pack 20 to the energy conversion circuit 11 , thereby heating the battery pack 20 .

[0056] In one implementation, when the temperature of the battery pack 20 is less than or equal to a temperature threshold, the controller 12 can control the heating circuit 112 to operate in a third operating mode and the inverter circuit 111 to operate in an inverter mode, so that the energy conversion device 10 can obtain electrical energy from the battery pack 10 and feed the converted energy to the AC power grid 30. The heating circuit 112 in the third operating mode can ensure that the electrical energy transmitted from the battery pack 20 is properly transmitted to the inverter circuit 111, and that the inverter circuit 111 at least inverts the electrical energy before feeding it to the AC power grid 30, thereby increasing the temperature of the battery pack 20 during the feeding process.

[0057] In one implementation, the controller 12 does not need to heat the battery pack 20 when the temperature of the battery pack 20 is greater than the temperature threshold, so the energy conversion device 10 can operate normally. The so-called normal operation can be understood as being able to charge the battery pack 20 when connected to the AC power grid 30, or being able to power the power tool when connected to the battery pack 20. Exemplarily, the controller 12 can control the heating circuit 112 to operate in the second operating mode, and the inverter circuit 111 to operate at least in the rectification mode, so that the electric energy connected to the AC power grid 30 can charge the battery pack 20 after energy conversion. The heating circuit 112 in the second operating mode can ensure that the electric energy from the inverter circuit 111 can be transmitted to the battery pack 20 and charge the battery pack 20.

[0058] Referring to the energy conversion system 100 shown in FIG3 , the heating circuit 112 in the energy conversion device 10 can be a bridge circuit comprising at least a plurality of switching elements Q1 to Q4 and an energy storage device L. A controller 12 is connected to the control terminals of the switching elements Q1 to Q4 and can control the conduction states of the switching elements Q1 to Q4. The energy storage device L can be an inductive element and can store or release energy during at least the switching state of the switching elements Q1 to Q4.

[0059] In this embodiment, the temperature detection module 113 can detect the temperature of the battery pack 20. When the temperature is less than or equal to a temperature threshold, for example, less than or equal to 0°C, the controller 12 controls the heating circuit 112 to perform AC preheating to heat the battery pack 20. The temperature detection module 113 can be a receiving module within the energy conversion device 10 that can receive temperature data transmitted by the battery pack 20, or a detection device that can directly detect the temperature of the battery pack 20, or a data acquisition or storage module built into the controller 12. In this embodiment, the AC preheating process of the heating circuit 112 can refer to the process shown in Figures 4a to 4d:

[0060] When the controller 12 detects that the temperature of the battery pack 20 is less than or equal to the temperature threshold, as shown in Figure 4a, the controller 12 first controls the switching elements Q1 and Q4 in the heating circuit 112 to turn on. At this time, the battery pack 20 begins to discharge, and the current iL in the energy storage element L, namely, the inductor L, increases in the direction shown in Figure 4a. Subsequently, as shown in Figure 4b, Q1 and Q4 are turned off. However, because the direction of the current iL in the inductor L cannot change suddenly, it maintains its original direction, turning on the body diodes D2 and D3 of the switching elements Q2 and Q3, thereby achieving soft switching of Q2 and Q3. Referring to Figure 4c, after Q2 and Q3 are turned on, the current iL in the inductor L can initially maintain the current direction shown in Figure 4c and then increase in the reverse direction after reaching zero. Continuing with Figure 4d, as the current iL increases in the reverse direction shown in Figure 4c, it naturally turns on the body diodes D1 and D4 of Q1 and Q4, thereby achieving soft switching of Q1 and Q4. During the AC preheating process shown in Figures 4a and 4b, the direction of power transmission at the first transmission interface 101 connected to the battery pack 20 changes at least four times. In Figure 4a, the battery pack 20 discharges while the inductor L stores energy. After switching to the state shown in Figure 4b, the stored energy in the inductor L reverses and charges the battery pack 20. After the charging energy gradually decreases to zero, the battery pack 20 can discharge again, and the inductor L stores energy again. After switching to Figure 4d, the inductor L discharges again to charge the battery pack 20. The above process represents one AC preheating operation in the heating circuit 112. Generally, after at least one AC preheating operation, if the temperature of the battery pack 20 reaches the temperature threshold, the controller 12 controls the heating circuit 112 to exit AC preheating. It is understood that during the AC preheating operation of the heating circuit 112, the inverter circuit 111 is in the off state. In this embodiment, the AC preheating operation of the heating circuit 112 can also be understood as the first operating mode described above.

[0061] In other embodiments, the heating circuit 112 may also adopt other circuit structures, which are not specifically limited here.

[0062] In some embodiments, the heating circuit 112 and the inverter circuit 111 are not strictly distinguished. That is, the heating circuit 112 and the inverter circuit 111 indicate a division made to easily distinguish the functions of some circuits. In fact, the energy conversion circuit 11 itself is a complete circuit module, and its internal circuit can be composed of an SRC series resonant module, an inverter module, a power factor correction module (PFC), or a resonant circuit (LLC), etc., and the different circuit modules therein can overlap or reuse each other. In other embodiments, the energy conversion circuit 11 can also include a totem pole PFC, a half-bridge circuit, or a full-bridge circuit. The current control method in the energy conversion circuit 11 includes but is not limited to pulse width modulation, frequency modulation, or wave-by-wave current limiting.

[0063] In one embodiment, Figures 5a through 5h illustrate the power feeding process implemented by various circuit modules in the energy conversion circuit 11 to the AC power grid 30. As shown in Figure 5a, the energy conversion circuit 11 can be divided into at least an SRC circuit submodule 110 and an inverter circuit submodule 120. The primary-side switches Q1 through Q4 of the SRC circuit submodule 110 alternately switch diagonally at high frequency. On the secondary side, Q5 through Q8 function as synchronous rectifiers, conducting diagonally, or the body diodes D5 through D8 conduct diagonally naturally, depending on the current direction. The inverter circuit submodule 120 is divided into power-frequency transistors and high-frequency transistors, which cooperate with control logic to generate AC power that is fed back to the AC power grid 30.

[0064] In one embodiment, Figures 5i through 5p illustrate the process by which each circuit module in the energy conversion circuit 11 implements charging of the battery pack 20. The energy conversion circuit 11 can be divided into a PFC circuit submodule 130 and an LLC circuit submodule 140. The PFC circuit submodule 130 comprises power-frequency diodes and high-frequency diodes, which, in conjunction with control logic, generate high-voltage DC power. The LLC circuit submodule 140 employs primary-side switching transistors Q5 through Q8, which alternately switch diagonally at high frequency. On the secondary side, depending on the current flow direction, Q1 through Q4 function as synchronous rectifiers, conducting diagonally, or body diodes D1 through D4 conduct diagonally naturally, converting the high-voltage power into low-voltage power to charge the battery pack 20.

[0065] In one embodiment, multiple battery packs 20 can also charge each other to increase their respective temperatures. In one implementation, referring to FIG6 , at least two battery packs 20 can charge each other through a DC / DC charger 40. For example, a temperature detection module is provided in the DC / DC charger 40 to detect the temperature of the battery pack 20 connected thereto. When the temperature of the battery pack 20 is less than or equal to a temperature threshold, the battery pack 20 on one side of the DC / DC charger 40 can be controlled to discharge, while the battery pack 20 on the other side can be charged. After a preset time, the process is reversed, i.e., the originally charged battery pack 20 is discharged, while the originally discharged battery pack 20 is charged. By cyclically switching the charge and discharge states of the two battery packs, the capacity of the battery pack 20 can be kept basically unchanged, and current flows through both battery packs 20, so that the internal resistance of the battery cells in the battery pack 20 can be used to generate heat, thereby increasing the temperature of the battery pack 20 itself.

[0066] In some embodiments, the at least two battery packs 20 connected to the DC / DC charger 40 may be of the same type, different types, or partially the same type. The so-called battery pack type may include the rated voltage, capacity, energy, discharge capability, or materials constituting the battery cells within the battery pack.

[0067] In some embodiments, the DC / DC charger 40 can also be integrated into the battery pack 20. In some application scenarios, the user can manually sense that the ambient temperature is very low, such as below zero degrees Celsius. Two battery packs 20 can be connected together to heat each other through a cycle of charging and discharging. When the temperature reaches a certain level, the charging and discharging circuits are automatically disconnected.

[0068] In this embodiment, the charge-discharge circuit within the DC / DC charger 40 may be a four-switch Buck-Boost circuit (FSBB circuit) as shown in FIG7 . In other embodiments, the charge-discharge circuit within the DC / DC charger 40 may also employ an isolated or non-isolated topology. In this embodiment, control of the FSBB circuit includes, but is not limited to, single-mode control, dual-mode control, and hybrid single-mode control. Current control methods for the FSBB circuit include, but are not limited to, pulse width modulation, frequency modulation, and wave-by-wave current limiting.

[0069] In this application, the battery pack in the energy conversion system is compatible with various types of power tools. As shown in FIG8 , power tool 50 may include a riding lawn mower 50a, a handheld electric drill 50b, a chainsaw 50c, a lawn trimmer 50d, and a hair dryer 50e. The power tool may be a handheld power tool, such as a drill, a pruner, or a sander. Alternatively, the power tool may be a benchtop tool, such as a table saw or a miter saw. Alternatively, the power tool may be a push power tool, such as a push lawn mower or a push snow blower. Alternatively, the power tool may be a riding power tool, such as a riding lawn mower, a riding vehicle, or an all-terrain vehicle. Alternatively, the power tool may be a robotic tool, such as a lawn mower or a snow blower. In some embodiments, the power tool may be an electric drill, an electric light, or an electric vehicle. In some embodiments, the power tool may be a garden tool, such as a pruner, a hair dryer, a lawn mower, or a chainsaw. Alternatively, the power tool may also be a decoration tool, such as a screwdriver, a nail gun, a circular saw, a sander, etc. In some embodiments, the power tool may also be a vegetation care tool, such as a lawn mower, a lawn mower, a pruner, a chain saw, etc. Alternatively, the power tool may also be a cleaning tool, such as a hair dryer, a snow blower, a cleaning machine, etc. Alternatively, the power tool may also be a drilling tool, such as a drill, a screwdriver, a wrench, an electric hammer, etc. Alternatively, the power tool may also be a sawing tool, such as a reciprocating saw, a jig saw, a circular saw, etc. Alternatively, the power tool may also be a bench tool, such as a table saw, a miter saw, a metal cutter, an electric milling machine, etc. Alternatively, the power tool may also be a grinding tool, such as an angle grinder, a sander, etc. Alternatively, the power tool may also be other tools, such as a lamp, a fan, etc. Of course, the load may also include other types of household electrical appliances.

[0070] The above shows and describes the basic principles, main features and advantages of this application. Those skilled in the art should understand that the above embodiments do not limit this application in any form, and any technical solutions obtained by equivalent replacement or equivalent transformation fall within the scope of protection of this application.

Claims

1. An energy conversion device, comprising at least: A first transmission interface, comprising a battery connection terminal adapted to be connected to a battery pack; The second transmission interface is configured to at least be able to access an AC power grid; an energy conversion circuit, capable of at least converting the electric energy input from the first transmission interface and feeding it to the second transmission interface; A controller, at least in communication connection with the first transmission interface, and electrically connected with the energy conversion circuit; Wherein, the controller is configured as: When the temperature of the battery pack is less than or equal to a temperature threshold, at least the energy conversion circuit is controlled to perform energy conversion on the energy input from the first transmission interface so that the battery pack at least obtains heating heat energy.

2. The energy conversion device according to claim 1, wherein: The electric energy conversion circuit includes: an inverter circuit, which is configured to invert the electric energy input from the first transmission interface and feed it to the AC power grid at least when the temperature of the battery pack is less than or equal to the temperature threshold.

3. The energy conversion device according to claim 2, wherein: The inverter circuit is further configured to convert the electric energy input from the second transmission interface into electric energy for charging the battery pack.

4. The energy conversion device according to claim 2, wherein: The controller is configured to control the inverter circuit to operate in an inverter mode when the temperature of the battery pack is less than or equal to a temperature threshold.

5. The energy conversion device according to claim 2, wherein: The controller is configured to: when the temperature of the battery pack increases to be greater than a temperature threshold, control the inverter circuit to operate in a rectification mode or control the inverter circuit to be in a disconnected state.

6. The energy conversion device according to claim 1, wherein: The electric energy conversion circuit includes: a heating circuit, which is electrically coupled to at least the first transmission interface; the controller is configured to control the heating circuit to operate in a first operating mode when the temperature of the battery pack is less than or equal to the temperature threshold, so that the battery pack can at least obtain heating heat energy.

7. The energy conversion device according to claim 6, wherein: The heating circuit includes a plurality of switch elements; the controller is configured to control the switch elements to change the conduction state in the first working mode so as to change the transmission direction of the electric energy at the first transmission interface at least twice.

8. The energy conversion device according to claim 6, wherein: The heating circuit further includes an energy storage element, which is configured to store the electric energy released by the battery pack and transmit the stored electric energy to the battery pack.

9. The energy conversion device according to claim 8, wherein: The energy storage element includes an inductor element.

10. The energy conversion device according to claim 1, wherein: The controller is configured to at least control the energy conversion circuit to convert energy input from the second transmission interface to charge the battery pack when the temperature of the battery pack is greater than the temperature threshold.

11. The energy conversion device according to claim 6, wherein: The controller is configured to control the heating circuit to operate in a second operating mode when the temperature of the battery pack is greater than the temperature threshold, so that the battery pack obtains charging power.

12. An energy conversion system comprising a battery pack, an AC power grid and an energy conversion device; The battery pack is configured to be coupled to an electric tool to power the electric tool; The energy conversion device is configured to be connected to the battery pack and the AC power grid, and to convert the electric energy input by the battery pack and feed it to the AC power grid; in, When the temperature of the battery pack is less than or equal to a temperature threshold, the energy device can convert the energy input from the battery pack so that the battery pack can at least obtain heating heat energy.

13. The energy conversion system according to claim 12, wherein: When the temperature of the battery pack is less than or equal to a temperature threshold, the energy device converts the electric energy input from the battery pack and feeds it to the AC power grid, so that the battery pack obtains heating thermal energy.

14. The energy conversion system according to claim 12, wherein: When the temperature of the battery pack is less than or equal to a temperature threshold, the energy device changes the transmission direction of electric energy between the battery pack and the energy device at least twice, so that the battery pack obtains heating energy.

15. An inverter device, comprising at least: A first transmission interface, comprising a battery connection terminal adapted to be connected to a battery pack; The second transmission interface is configured to at least be able to access an AC power grid; An inverter circuit, arranged between the first transmission interface and the second transmission interface, having multiple working modes; A heating circuit, arranged between the first transmission interface and the inverter circuit, having multiple working modes; A controller, electrically connected to at least the inverter circuit and the heating circuit; The controller is configured to: When the temperature of the battery pack is less than or equal to a temperature threshold, the inverter circuit and / or the heating circuit is controlled to perform energy conversion on the energy input by the first transmission interface so that the battery pack obtains at least heating heat energy.

16. The inverter device according to claim 15, wherein: When the temperature of the battery pack is less than or equal to the temperature threshold, the heating circuit operates in the first operating mode, and the inverter circuit is in a disconnected state, so that the battery pack can obtain heating energy.

17. The inverter device according to claim 15, wherein: When the temperature of the battery pack is greater than the temperature threshold, the heating circuit operates in a second operating mode, and the inverter circuit has at least a rectification mode, so that the battery pack obtains charging power.

18. The inverter device according to claim 15, wherein: When the temperature of the battery pack is less than or equal to the temperature threshold, the heating circuit operates in a third operating mode, and the inverter circuit has at least an inverter mode, so that the battery pack can be fed into the AC power grid.

19. The inverter device according to claim 15, wherein: When the temperature of the battery pack is less than or equal to a temperature threshold, the inverter circuit operates in an inverter mode.

20. The inverter device according to claim 15, wherein: When the temperature of the battery pack increases to a value greater than a temperature threshold, the inverter circuit operates in a rectification mode or is in a disconnected state.

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