Energy conversion device, inversion device and energy conversion system

Abstract

The invention discloses an energy conversion device, an inversion device and an energy conversion system, and the energy conversion device at least comprises a first transmission interface which comprises a battery connection terminal suitable for being connected to a battery pack; the second transmission interface is arranged to be at least capable of accessing an alternating current power grid; the energy conversion circuit at least can convert the electric energy input by the first transmission interface and then feed the electric energy to the second transmission interface; the controller is at least in communication connection with the first transmission interface and is electrically connected with the energy conversion circuit; wherein the controller is configured to at least control the energy conversion circuit to carry out energy conversion on the energy input by the first transmission interface when the temperature of the battery pack is smaller than or equal to a temperature threshold value, so that the battery pack at least obtains heating heat energy.

Description

Technical Field

[0001] The present application relates to a low-temperature treatment technology for an energy device, and more particularly to an energy conversion device, an inverter device, and an energy conversion system. Background Art

[0002] With the development of battery technology, DC power tools have gradually replaced engine tools. As the power source of DC power tools, the performance of the battery directly affects the working performance of the power tools. In particular, in a low-temperature environment, the power characteristics of lithium batteries deteriorate, the cycle life decays, and the available capacity decreases, affecting the use experience of power tools in winter; at the same time, there are safety problems such as difficult low-temperature charging and easy lithium plating during DC charging.

[0003] This section provides background information related to the present application, which is not necessarily prior art. Summary of the Invention

[0004] An object of the present application is to solve or at least mitigate some or all of the above problems. To this end, an object of the present application is to provide an energy conversion device capable of heating a battery pack at low temperature.

[0005] To achieve the above object, the present application adopts the following technical solutions: An energy conversion device, at least comprising: a first transmission interface including a battery connection terminal adapted to be connected to a battery pack; a second transmission interface configured to be capable of accessing at least an AC power grid; an energy conversion circuit capable of converting at least the electric energy input from 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 from the first transmission interface so that the battery pack obtains at least heating thermal energy.

[0006] In some embodiments, the electric energy conversion circuit includes: an inverter circuit configured to at least invert the electric energy input from the first transmission interface and feed it to the AC power grid when the temperature of the battery pack is less than or equal to the temperature threshold.

[0007] In some embodiments, the inverter circuit is further configured to convert the electric energy input from the second transmission interface and charge the battery pack.

[0008] In some embodiments, the electric energy conversion circuit includes: a heating circuit 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 obtains at least heating thermal energy.

[0009] In some embodiments, the heating circuit includes a plurality of switching elements; the controller is configured to control the switching elements to change the conduction state in the first operating mode so as to change the power transmission direction at the first transmission interface at least twice.

[0010] In some embodiments, the heating circuit further includes an energy storage element configured to store the electrical energy released by the battery pack and transmit the stored electrical energy to the battery pack.

[0011] In some embodiments, the controller is configured to control the energy conversion circuit to perform energy conversion on the energy input at the second transmission interface to charge the battery pack when the temperature of the battery pack is greater than the temperature threshold.

[0012] In some embodiments, the controller is configured to control the heating circuit to operate in a second operating mode to enable the battery pack to obtain charging electrical energy when the temperature of the battery pack is greater than the temperature threshold.

[0013] An energy conversion system includes a battery pack, an AC power grid, and an energy conversion device; the battery pack is configured to be combined with a power tool to supply power to the power tool; the energy conversion device is configured to access the battery pack and the AC power grid and convert the electrical 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 perform energy conversion on the energy input by the battery pack so that the battery pack obtains at least heating thermal energy.

[0014] In some embodiments, when the temperature of the battery pack is less than or equal to the temperature threshold, the energy device converts the electrical energy input by the battery pack and feeds it to the AC power grid so that the battery pack obtains heating thermal energy.

[0015] In some embodiments, when the temperature of the battery pack is less than or equal to the temperature threshold, the energy device changes the power transmission direction between the battery pack and the energy device at least twice so that the battery pack obtains heating thermal energy.

[0016] An inverter device includes at least: a first transmission interface including battery connection terminals adapted to be connected to a battery pack; a second transmission interface configured to be connected to at least an AC power grid; an inverter circuit disposed between the first transmission interface and the second transmission interface and having multiple operating modes; a heating circuit disposed between the first transmission interface and the inverter circuit and having multiple operating modes; and 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, control the inverter circuit and / or the heating circuit to perform energy conversion on the energy input to the first transmission interface so that the battery pack obtains at least heating thermal energy.

[0017] 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 an off state, and the battery pack can obtain heating thermal energy.

[0018] 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 electrical 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 third operating mode, and the inverter circuit has at least an inversion mode so that the battery pack can feed power to the AC power grid. Description of the Drawings

[0020] Figure 1 is a schematic diagram of an energy conversion system in an embodiment of the present application; Figure 2 is a schematic diagram of the internal circuit structure of an energy conversion device in an embodiment of the present application; Figure 3 is a schematic diagram of the internal circuit structure of an energy conversion device in an embodiment of the present application; Figures 4a to 4d is a schematic diagram of circuit transformation during the process of heating a battery pack by an energy conversion device in an embodiment of the present application in one way; Figures 5a to 5h is a schematic diagram of circuit transformation during the process of heating a battery pack by an energy conversion device in an embodiment of the present application in another way; Figures 5i to 5p is a schematic diagram of circuit transformation during the process of charging a battery pack by an energy conversion device in an embodiment of the present application in one way; Figure 6 is a schematic diagram of a module for mutual heating between battery packs in an embodiment of the present application; Figure 7It is a schematic diagram of a charger circuit for realizing mutual heating between battery packs in an embodiment of the present application; Figure 8 It is a schematic diagram of some power tools used in the battery pack in an embodiment of the present application. Detailed implementation manners

[0021] Before explaining any embodiment of the present application in detail, it should be understood that the present application is not limited to the structural details and component arrangements described in the following description or shown in the above drawings.

[0022] In the present application, the terms "include", "comprise", "have" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device including a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "including a..." does not exclude the presence of additional identical elements in the process, method, article or device including the element.

[0023] In the present application, the term "and / or" is a relationship describing associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Additionally, in the present application, the character " / " generally represents an "and / or" relationship between the associated objects before and after.

[0024] In the present application, the terms "connect", "combine", "couple", "mount" can be direct connection, combination, coupling or mounting, or can be indirect connection, combination, coupling or mounting. Among them, by way of example, direct connection means that two parts or components are connected together without the need for an intermediate member, and indirect connection means that two parts or components are respectively connected to at least one intermediate member, and these two parts or components are connected through the intermediate member. In addition, "connect" and "couple" are not limited to physical or mechanical connection or coupling, and can include electrical connection or coupling.

[0025] In this application, those of ordinary skill in the art will understand that relative terms used in connection with quantities or conditions (such as "about", "approximately", "substantially", etc.) are intended to include the recited value and have the meaning indicated by the context. For example, such relative terms include at least the degree of error associated with the measurement of a particular value, tolerances resulting from manufacturing, assembly, use in relation to a particular value, etc. Such terms should also be considered to disclose a range defined by the absolute values of two endpoints. A relative term may refer to a plus or minus of a certain percentage (such as 1%, 5%, 10% or more) of the indicated value. Numerical values that do not employ relative terms should also be disclosed as specific values with tolerances. In addition, when expressing a relative angular positional relationship (such as substantially parallel, substantially perpendicular), "substantially" may refer to a plus or minus a certain number of degrees (such as 1 degree, 5 degrees, 10 degrees or more) from the indicated angle.

[0026] In this application, those of ordinary skill in the art will understand that the functions performed by a component can be performed by one component, multiple components, one part, or multiple parts. Similarly, the functions performed by a part can also be performed by one part, one component, or a combination of multiple parts.

[0027] In this application, the orientation terms such as "upper", "lower", "left", "right", "front", "rear", etc. are described based on the orientation and positional relationship shown in the drawings, and should not be construed as limiting the embodiments of this application. In addition, in the context, it should also be understood that when it is mentioned that one element is connected "above" or "below" another element, it can not only be directly connected "above" or "below" another element, but also be indirectly connected "above" or "below" another element through an intermediate element. It should also be understood that the orientation terms such as the upper side, lower side, left side, right side, front side, rear side, etc. not only represent the positive orientation, but can also be understood as the side orientation. For example, the lower side may include directly below, lower left, lower right, lower front, and lower rear, etc.

[0028] In this application, the terms "controller", "processor", "central processor", "CPU", "MCU" can be used interchangeably. When using the units "controller", "processor", "central processor", "CPU", or "MCU" to perform specific functions, unless otherwise specified, these functions can be performed by a single one of the above units or multiple of the above units.

[0029] In this application, for the terms "device", "module", or "unit" to achieve a specific function, they can be implemented in the form of hardware or software.

[0030] 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 devices (such as a controller, a processor, etc.).

[0031] In this application, the energy conversion device 10 can also be referred to as a bidirectional power supply device, or a bidirectional inverter, or an inversion device, or an adapter, or a charger, etc. In this embodiment, the energy conversion device 10 at least has a first transmission interface 101 connected to the battery connection terminal 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 (not shown) that can be connected to a power tool.

[0032] In one embodiment, the energy conversion device 10 can be used as a charger to convert the alternating current provided by the AC power grid 30 and charge the battery pack 20. The conversion may include rectification, filtering, boosting, or bucking, etc. In one embodiment, the energy conversion device 10 can be used as an inverter to convert the electrical energy input from the battery pack 10 and feed it to the AC power grid 30. The energy conversion may include inversion, filtering, boosting, or bucking, etc. In one embodiment, the energy conversion device 10 can also be used as an adapter to supply the electrical energy provided by the battery pack 20 to a power tool powered by alternating current, or can convert the electrical energy provided by the AC power grid 30 and supply it to a DC power tool.

[0033] In this embodiment, the AC power grid 30 may include power grids with standard voltages of various countries greater than or equal to 100V and less than or equal to 600V. For example, it can be an AC power grid of about 110V, or an AC power grid of about 220V, or an AC power grid of about 240V, or an AC power grid of about 380V, etc., which will not be listed one by one here. In other embodiments, the AC power grid 30 may further include a photovoltaic power grid, that is, a power grid formed by solar power generation.

[0034] In one embodiment, the energy conversion device 10, the battery pack 20, and the AC power grid 30 can form Figure 1 the energy conversion system 100 as shown.

[0035] In this embodiment, after the battery pack 20 is connected to the energy conversion device 10 through the first transmission interface 101, in addition to transmitting electrical energy, it can also transmit communication data to the energy conversion device 10. Among them, the communication data at least includes the temperature of the battery pack 20. For example, it can be the temperature around the battery cells in the battery pack 20, or the temperature inside the battery pack 20, or the temperature inside the battery cells in the battery pack 20, or the ambient temperature around the battery pack 20, etc. The energy conversion device 10 can at least change its internal energy conversion method or energy conversion process according to the temperature data transmitted by the battery pack 20.

[0036] Refer to Figure 2, the energy conversion device 10 can at least include 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 can be at least communicatively connected to the first transmission interface 101 to receive communication data transmitted by the battery pack 20 through the first transmission interface 101.

[0037] 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 charging and discharging operations are performed on the battery pack 20, problems such as difficult charging at low temperatures, affecting the battery cycle life, or other safety issues may occur.

[0038] To avoid the above problems, the controller 12 can control the energy conversion circuit 11 to change the circuit state according to the temperature of the battery pack 20, at least not charging the battery pack 20 or not discharging using the battery pack 20. In this embodiment, the controller 12 can also control the energy conversion circuit 11 to convert the energy input to the first transmission interface 101 according to the temperature of the battery pack 20 so that the battery pack 20 can at least obtain heating heat energy. That is to say, the energy conversion device 10 can at least heat the battery pack 20 by energy conversion when the temperature of the battery pack 20 is low, for example, below the temperature threshold.

[0039] In one embodiment, the energy conversion circuit 11 can at least include an inverter circuit 111. The inverter circuit 111 is arranged between the first transmission interface 101 and the second transmission interface 102, and the inverter circuit 111 can have multiple operating modes, so that the energy conversion device 10 has multiple energy conversion states.

[0040] In one implementation, when the temperature of the battery pack 20 is less than or equal to the temperature threshold, the controller 12 can control the inverter circuit 111 to operate in the inverter mode, so that the energy conversion device 10 can obtain electrical energy from the battery pack 20 side 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 in the battery pack 10 will generate heat energy, thereby increasing the temperature of the battery pack 20. After the temperature of the battery pack 20 rises above the temperature threshold, the controller 12 can control the inverter circuit 111 to operate in the rectification mode or control the inverter circuit 111 to be in the off state. Among them, in the rectification mode of the inverter circuit 111, the energy conversion device 10 can obtain charging electrical energy from the AC power grid 30 side and rectify and filter the electrical energy for charging the battery pack 20. When the inverter circuit 111 is in the off state, at least the electrical connection between the energy conversion device 10 and the AC power grid 30 is disconnected. When the inverter circuit 111 is disconnected, the energy can neither be fed to the AC power grid 30 nor obtain electrical energy from the AC power grid.

[0041] In one embodiment, the energy conversion circuit 11 may further include a heating circuit 112, and the heating circuit 112 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 may have different energy conversion functions.

[0042] In one implementation, when the temperature of the battery pack 20 is less than or equal to the temperature threshold, the controller 12 can control the heating circuit 112 to operate in the first operating mode and control the inverter circuit 111 to be in the off state, so that the battery pack 20 can obtain heating thermal energy. In this embodiment, since the inverter circuit 111 is off, after the heating circuit 112 in the first operating mode obtains the electric energy transmitted by the battery pack 20, it cannot be transmitted to the subsequent inverter circuit 111 nor to the AC grid 30. In the above case, the heating circuit 112 can convert the transmission direction or the magnitude of the electric energy, or store or release the electric energy transmitted by the battery pack 20. In the above implementation, the electric energy transmitted from the battery pack 20 to the energy conversion device 10 has at least two changes in the current transmission direction inside the heating circuit 112, so as to realize at least one charge and discharge of the battery pack 20. Before the temperature of the battery pack 20 reaches the temperature threshold, the heating circuit 112 can perform cyclic charge and discharge control on the battery pack 20 itself based on the electric energy transmitted from the battery pack 20 to the energy conversion circuit 11, so as to heat the battery pack 20.

[0043] In one implementation, when the temperature of the battery pack 20 is less than or equal to the temperature threshold, the controller 12 can control the heating circuit 112 to operate in the third operating mode and control the inverter circuit 111 to be in the inversion mode, so that the energy conversion device 10 can obtain electric energy from the battery pack 10 side and feed the energy after conversion to the AC grid 30. Among them, the heating circuit 112 in the third operating mode can ensure that the electric energy transmitted from the battery pack 20 side can be normally transmitted to the inverter circuit 111, and at least invert the electric energy through the inverter circuit 111 and then feed it to the AC grid 30, so that the temperature of the battery pack 20 rises during the power feeding process.

[0044] In one implementation, when the temperature of the battery pack 20 is greater than the temperature threshold, the controller 12 does not need to heat the battery pack 20, 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 the battery pack 20 and the AC grid 30 are connected, or being able to supply power to the power tool when the battery pack 20 and the power tool are connected, etc. Exemplarily, the controller 12 can control the heating circuit 112 to operate in the second operating mode, and the inverter circuit 111 operates at least in the rectification mode, so that the electric energy connected from the AC grid 30 can be converted and used to charge the battery pack 20 after energy conversion. The heating circuit 112 in the second operating mode can ensure that the electric energy coming from the inverter circuit 111 can be transmitted to the battery pack 20 and charge the battery pack 20.

[0045] Referring to Figure 3 the energy conversion system 100 shown, the heating circuit 112 in the energy conversion device 10 can be a bridge circuit, which at least includes a plurality of switching elements Q1 to Q4 and an energy storage device L. The 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 at least store or release energy during the process of switching the conduction states of the switching elements Q1 to Q4.

[0046] In this embodiment, the temperature detection module 113 can detect the temperature of the battery pack 20, and when the temperature is less than or equal to the temperature threshold, for example, when the temperature is 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. Among them, the temperature detection module 113 can be a receiving module in the energy conversion device 10 that can receive the temperature data transmitted by the battery pack 20, or a detection device that can directly detect the temperature of the battery pack 20, or can be a data acquisition or storage module built in the controller 12, etc. In this embodiment, the process of AC preheating of the heating circuit 112 can refer to Figures 4a to 4d the process shown: When the controller 12 detects that the temperature of the battery pack 20 is less than or equal to the temperature threshold, such as Figure 4a the controller 12 first controls the switching elements Q1 and Q4 in the heating circuit 112 to conduct. At this time, the battery pack 20 starts to discharge, and the current iL of the energy storage element L, that is, the inductor L, rises along the Figure 4a direction shown. After that, as shown in Figure 4b Q1 and Q4 are turned off, but since the direction of the current iL on the inductor L cannot change suddenly, it still maintains the original direction and can conduct the body diodes D2 and D3 of the switching elements Q2 and Q3, so as to realize the soft switching of Q2 and Q3. Referring to Figure 4c , after Q2 and Q3 are turned on, the current iL of the inductor L can first maintain Figure 4c the current direction in and decrease, and after it is about to reach 0, it increases in the reverse direction. Continuing to refer toFigure 4d , during the process of the reverse increase of the current iL in Figure 4c , the body diodes D1 and D4 of Q1 and Q4 can be naturally turned on, thereby realizing the soft switching of Q1 and Q4. During Figures 4a to 4b the shown AC preheating process, the power transmission direction at the first transmission interface 101 connected to the battery pack 20 changes at least 4 times. During Figure 4a , the battery pack 20 discharges and the inductor L stores energy. After switching to Figure 4b the shown state, the energy stored in the inductor L is reversed to charge the battery pack 20. After the charging power 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 is a process of one-time AC preheating in the heating circuit 112. Generally, if the temperature of the battery pack 20 can reach the temperature threshold after at least one-time AC preheating, the controller 12 controls the heating circuit 112 to exit the AC preheating. It can be understood that during the AC preheating process of the heating circuit 112, the inverter circuit 111 is in the off state. In this embodiment, the working mode of the AC preheating of the heating circuit 112 can also be understood as the above-mentioned first working mode.

[0047] In other embodiments, the heating circuit 112 can also adopt other forms of circuit structures, which are not specifically limited here.

[0048] In some embodiments, there is no strict distinction between the heating circuit 112 and the inverter circuit 111. That is to say, the heating circuit 112 and the inverter circuit 111 are artificial divisions made for the convenience of distinguishing the functions of some circuits. In fact, the energy conversion circuit 11 itself is a complete circuit module, and its internal circuits can include an SRC series resonance module, or an inverter module, or a power factor correction module (PFC), or a resonance circuit (LLC), etc., and different circuit modules therein can overlap or be reused. In other embodiments, the energy conversion circuit 11 can also include a totem pole PFC, or a half-bridge circuit or a full-bridge circuit. The control methods of the current in the energy conversion circuit 11 include but are not limited to pulse width modulation, or frequency modulation, or wave-by-wave current limiting, etc.

[0049] In one embodiment, Figures 5a to 5h shows the feeding process in which each circuit module in the energy conversion circuit 11 feeds power to the AC power grid 30. Among them, as Figure 5aThe energy conversion circuit 11 shown can be at least divided into an SRC circuit sub-module 110 and an inverter circuit sub-module 120. Among them, the primary side switching transistors Q1 to Q4 of the SRC circuit sub-module 110 perform diagonal alternating high-frequency switching, and on the secondary side, according to the current direction, Q5 to Q8 act as synchronous rectifier diodes to conduct diagonally, or the body diodes D5 to D8 conduct naturally diagonally; the inverter circuit sub-module 120 is divided into power frequency transistors and high-frequency transistors, and cooperates with the control logic to generate alternating current and feedback it to the AC power grid 30.

[0050] In one embodiment, Figures 5i to 5p The process of each circuit module in the energy conversion circuit 11 realizing charging the battery pack 20 is shown. The energy conversion circuit 11 can be divided into a PFC circuit sub-module 130 and an LLC circuit sub-module 140. Among them, the PFC circuit sub-module 130 is divided into power frequency transistors and high-frequency transistors, and cooperates with the control logic to generate high-voltage direct current. The primary side switching transistors Q5 to Q8 of the LLC circuit sub-module 140 perform diagonal alternating high-frequency switching, and on the secondary side, according to the current direction, Q1 to Q4 act as synchronous rectifier diodes to conduct diagonally, or the body diodes D1 to D4 conduct naturally diagonally, and convert the high-voltage electricity into low-voltage electricity to charge the battery pack 20.

[0051] In one embodiment, multiple battery packs 20 can also charge each other to increase their respective temperatures. In one implementation, referring to Figure 6 , at least two battery packs 20 can charge each other through the DC / DC charger 40. For example, a temperature detection module can be set in the DC / DC charger 40 to detect the temperature of the battery pack 20 connected to it. When the temperature of the battery pack 20 is less than or equal to the temperature threshold, the battery pack 20 on one side of the DC / DC charger 40 can be controlled to discharge, and the battery pack 20 on the other side can be charged, and after a preset time, vice versa, that is, the originally charged battery pack 20 discharges, and the originally discharged battery pack 20 charges. 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 there is current flowing through both of the two battery packs 20, so that heat can be generated by the internal resistance of the battery cells in the battery pack 20 itself, and the temperature of the battery pack 20 itself can be increased.

[0052] In some embodiments, the types of at least two battery packs 20 connected to the DC / DC charger 40 can be the same or different, or can be partially the same. The so-called type of battery pack can include the rated voltage, capacity, energy, discharge capacity of the battery pack, or the material of the battery cells constituting the battery pack, etc.

[0053] In some embodiments, the DC / DC charger 40 can also be built into the battery pack 20 after integration. In some application scenarios, the user can artificially sense that the ambient temperature is very low, for example, below zero degrees Celsius, and can connect two battery packs 20 together to heat each other through mutual cycle charging and discharging, and automatically disconnect the charging and discharging circuit after reaching a certain temperature.

[0054] In this embodiment, the charging and discharging circuit in the DC / DC charger 40 can be as follows: Figure 7 The four-switch Buck-Boost circuit (FSBB circuit) shown in FIG. 4 is a four-switch Buck-Boost circuit (FSBB circuit). In other embodiments, the charging and discharging circuit in the DC / DC charger 40 may also be an isolated topology or a non-isolated topology. In this embodiment, the control of the FSBB circuit includes but is not limited to single-mode control, dual-mode control, and hybrid single-mode control, and the current control method of the FSBB circuit is not limited to pulse width modulation, frequency modulation, wave-by-wave current limiting, etc.

[0055] In this application, the battery pack in the energy conversion system is adapted to various types of power tools, such as Figure 8 The power tool 50 shown may include a riding lawn mower 50a, a handheld electric drill 50b, a chain saw 50c, a lawn mower 50d, and a hair dryer 50e. The power tool may be a handheld power tool, such as a drill, a pruning machine, a sander, etc. Alternatively, the power tool may also be a bench tool, such as a bench saw, a miter saw, etc. Alternatively, the power tool may also be a hand-pushed power tool, such as a hand-pushed lawn mower, a hand-pushed snow blower. Alternatively, the power tool may also be a riding power tool, such as a riding lawn mower, a riding vehicle, an all-terrain vehicle, etc. Alternatively, the power tool may also be a robot tool, such as a lawn mowing robot, a snow sweeping robot, etc. In some embodiments, the power tool may be an electric drill, an electric light, an electric car, etc. In some embodiments, the power tool may also be a garden tool, such as a pruning machine, a hair dryer, a lawn mower, a chain saw, etc. 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 sweeper, 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 saw 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 bench saw, a miter saw, a metal cutter, a bakelite 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.

[0056] The basic principles, main features and advantages of the present application have been shown and described above. Those skilled in the art should understand that the above embodiments do not limit the present application in any form. Any technical solutions obtained by means of equivalent replacement or equivalent transformation fall within the protection scope of the present application.

Claims

1. An energy conversion device, at least comprising: A first transmission interface, including a battery connection terminal adapted to be connected to a battery pack; A second transmission interface, configured to be able to access at least 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, 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 from the first transmission interface so that the battery pack obtains at least heating thermal energy.

2. The energy conversion device according to claim 1, wherein, The electric energy conversion circuit includes: an inverter circuit, configured to at least invert the electric energy input from the first transmission interface and feed it to the AC power grid 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 also used to convert the electric energy input from the second transmission interface and charge the battery pack.

4. The energy conversion device according to claim 1, wherein, The electric energy conversion circuit includes: a heating circuit, at least electrically coupled to 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 obtains at least heating thermal energy.

5. The energy conversion device according to claim 4, wherein, The heating circuit includes a plurality of switching elements; the controller is configured to control the switching elements to change the conduction state in the first operating mode to change the transmission direction of the electric energy at the first transmission interface at least twice.

6. The energy conversion device according to claim 4, wherein, The heating circuit further includes an energy storage element, and the energy storage element is configured to store the electric energy released by the battery pack and transmit the stored electric energy to the battery pack.

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

8. The energy conversion device according to claim 4, 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 electric energy.

9. An energy conversion system, including a battery pack, an AC power grid and an energy conversion device; The battery pack is configured to be combined with a power tool to supply power to the power tool; The energy conversion device is configured to be able to access the battery pack and the AC power grid, and convert the electric energy input from 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 the temperature threshold, the energy device can convert the energy input by the battery pack so that the battery pack obtains at least heating thermal energy.

10. The energy conversion system according to claim 9, wherein, when the temperature of the battery pack is less than or equal to the temperature threshold, the energy device converts the electric energy input by the battery pack and feeds it to the AC power grid so that the battery pack obtains heating thermal energy.

11. The energy conversion system according to claim 9, wherein, when the temperature of the battery pack is less than or equal to the temperature threshold, the energy device changes the transmission direction of the electric energy between the battery pack and the energy device at least twice so that the battery pack obtains heating thermal energy.

12. An inverter device, at least comprising: a first transmission interface including a battery connection terminal adapted to be connected to a battery pack; a second transmission interface configured to be able to access at least an AC power grid; an inverter circuit disposed between the first transmission interface and the second transmission interface and having multiple working modes; a heating circuit disposed between the first transmission interface and the inverter circuit and 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 the temperature threshold, control the inverter circuit and / or the heating circuit to convert the energy input to the first transmission interface so that the battery pack obtains at least heating thermal energy.

13. The inverter device according to claim 12, wherein, when the temperature of the battery pack is less than or equal to the temperature threshold, the heating circuit operates in a first working mode and the inverter circuit is in an off state, and the battery pack can obtain heating thermal energy.

14. The inverter device according to claim 12, wherein, when the temperature of the battery pack is greater than the temperature threshold, the heating circuit operates in a second working mode and the inverter circuit has at least a rectification mode so that the battery pack obtains charging electric energy.

15. The inverter device according to claim 12, wherein, when the temperature of the battery pack is less than or equal to the temperature threshold, the heating circuit operates in a third working mode and the inverter circuit has at least an inversion mode so that the battery pack can feed power to the AC power grid.

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