Charging circuit of battery and electric vehicle

Abstract

The invention discloses a charging circuit of a battery and an electric vehicle. The charging circuit comprises the battery, a direct current charging interface, a switch tube combination circuit and a heating control contactor. The battery comprises a first part of battery cell and a second part of battery cell which are connected in series through a series node; the switch tube combination circuit is connected between the direct current charging interface and the battery; the heating control contactor is connected between the switch tube combination circuit and the series connection node. When the heating control contactor is conducted and the switch tube combination circuit is configured to be a booster circuit, the switch tube combination circuit is used for charging the battery after boosting the direct current input from the direct current charging interface, and alternately controlling the first part of battery core to discharge and charge the second part of battery core at the same time. Or after the second part of battery cells are discharged, the first part of battery cells are charged. Self-heating of the battery is realized by utilizing internal resistance heating of the battery.

Description

Technical Field

[0001] The present application relates to the field of batteries, and more specifically to a battery charging circuit and an electric vehicle. Background Art

[0002] With the rapid development of new energy vehicles, the proportion of electric vehicles in the automobile market has increased year by year, and the range anxiety is an urgent problem for new energy vehicle manufacturers. Correspondingly, the charging efficiency of electric vehicles has also become an issue of increasing concern. To solve this problem, the current solutions are mainly high-power DC charging technology or battery replacement technology. However, in a low temperature environment, the battery performance decreases due to the reduced activity of the electrochemical substances inside the battery, resulting in low efficiency of lithium-ion battery charging. The current mainstream method is to set a heating device on the outside of the battery to increase the overall temperature of the battery. Specifically, there are heating methods such as heating the battery with a PTC heating film or heating the battery with a liquid medium conduction. In these external heating methods, heat is transferred from the heat source to the battery, and the energy loss in the middle leads to low efficiency of external heating. In addition, the high-voltage power supply system of the whole vehicle needs to distribute power to the battery heating device, and it is also necessary to set up a condensation flow channel and circulation system of the battery heating device, resulting in a high total cost. Summary of the invention

[0003] The present invention is proposed to solve at least one of the above problems. According to the first aspect of the present application, a charging circuit of a battery is provided, the charging circuit comprising: a battery, a DC charging interface, a switch tube combination circuit and a heating control contactor. Wherein, the battery comprises a first part of battery cells and a second part of battery cells connected in series through a series node; the switch tube combination circuit is connected between the DC charging interface and the battery; the heating control contactor is connected between the switch tube combination circuit and the series node; when the heating control contactor is turned on and the switch tube combination circuit is configured as the boost circuit, the switch tube combination circuit is used to: while charging the battery after boosting the DC power input from the DC charging interface, it also alternately controls the first part of battery cells to charge the second part of battery cells after discharging, or the second part of battery cells to charge the first part of battery cells after discharging.

[0004] In one embodiment of the present application, the switch tube combination circuit includes a first positive electrode, a first negative electrode, a second positive electrode and a second negative electrode; the first positive electrode and the first negative electrode are respectively connected to the positive electrode and the negative electrode of the DC charging interface, and the second positive electrode and the second negative electrode are respectively connected to the positive electrode and the negative electrode of the battery; the series node is also connected to the first positive electrode through the heating control contactor.

[0005] In one embodiment of the present application, the switch tube combination circuit further includes: at least one group of bridge arms and at least one inductor. Each group of bridge arms includes an upper bridge arm and a lower bridge arm connected in series; and when the number of groups of the bridge arms is at least two, at least two groups of bridge arms are connected in parallel; the positive electrode of each group of bridge arms is connected to the second positive electrode, and the negative electrode of each group of bridge arms is connected to the first negative electrode and the second negative electrode. The at least one inductor corresponds to the at least one group of bridge arms one by one, and one end of each inductor is connected to the connection node between the upper bridge arm and the lower bridge arm of the corresponding group of bridge arms, and the other end is connected to the first positive electrode.

[0006] In one embodiment of the present application, the number of groups of the bridge arms is three, and the number of the inductors is three.

[0007] In one embodiment of the present application, the three groups of bridge arms and the three inductors are all bridge arms and inductors in a motor controller.

[0008] In one embodiment of the present application, the second positive electrode of the switch tube combination circuit is also connected to the positive electrode of the DC charging interface through a direct charging contactor.

[0009] In one embodiment of the present application, the DC charging interface includes a first DC charging interface and a second DC charging interface, and the switch tube combination circuit includes a first switch tube combination circuit and a second switch tube combination circuit; the first switch tube combination circuit is connected between the first DC charging interface and the battery, and the second switch tube combination circuit is connected between the second DC charging interface and the battery; at least one of the first switch tube combination circuit and the second switch tube combination circuit is connected to the series node through the heating control contactor.

[0010] In one embodiment of the present application, the first DC charging interface is respectively connected to the positive and negative electrodes of the battery through the first switch tube combination circuit; the second DC charging interface is shunt-connected to the positive and negative electrodes of the battery through the second switch tube combination circuit; at least one of the first positive electrodes of the two switch tube combination circuits is connected to the series node through the heating control contactor.

[0011] In one embodiment of the present application, the number of the heating control contactors is one; the first positive electrode of the first switch tube combination circuit is connected to the series node between the first part of the battery cells and the second part of the battery cells through the heating control contactor.

[0012] In one embodiment of the present application, the heating control contactor includes a first heating control contactor and a second heating control contactor; the first positive pole of the first switch tube combination circuit is connected to the series node between the first part of the battery cells and the second part of the battery cells through the first heating control contactor; the first positive pole of the second switch tube combination circuit is connected to the series node between the first part of the battery cells and the second part of the battery cells through the second heating control contactor.

[0013] In one embodiment of the present application, the second positive electrode of the first switch tube combination circuit is also connected to the positive electrode of the first DC charging interface through a direct charging contactor; and / or, the second positive electrode of the second switch tube combination circuit is also connected to the positive electrode of the second DC charging interface through a direct charging contactor.

[0014] In one embodiment of the present application, the number of battery cells in the first part of battery cells and the second part of battery cells each accounts for half of the total battery cells of the battery.

[0015] According to a second aspect of the present application, an electric vehicle is provided, comprising: a vehicle body, and a charging circuit for any one of the above-mentioned batteries arranged on the vehicle body.

[0016] According to the battery charging circuit and electric vehicle provided by the embodiment of the present application, the series node between the first part of the battery cell and the second part of the battery cell is connected to the switch tube combination circuit through the heating control contactor. When the heating control contactor is turned on and the switch tube combination circuit is configured as a boost circuit, the switch tube combination circuit charges the battery after boosting the DC power input from the DC charging interface, and is also used to alternately control the first part of the battery cell to charge the second part of the battery cell after discharging, or to charge the first part of the battery cell after discharging the second part of the battery cell. Through the switch tube combination circuit and the heating control contactor, the first part of the battery cell and the second part of the battery cell are alternately charged and discharged with each other, and the internal resistance of the battery is used to generate heat to achieve self-heating of the battery. The self-heating temperature rise efficiency is high, and the charging speed of the battery at low temperature is improved. Compared with the external heating method, the battery self-heating scheme shown in the embodiment of the present application has less energy loss and improves the heating efficiency. And there is no need to distribute power to the battery heating device additionally, and there is no need to set up a condensation flow channel, a circulation system, etc. of the battery heating device, which reduces costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0018] Figure 1 A schematic block diagram of a battery charging circuit provided by an embodiment of the present invention;

[0019] Figure 2 A charging circuit diagram of a battery provided in another embodiment of the present invention;

[0020] Figure 3-4 Based on Figure 2 A schematic diagram of a current path of a battery charging circuit when charging using a first DC charging interface is shown;

[0021] Figure 5-6 Based on Figure 2 A schematic diagram of a current path of a battery charging circuit when charging using a second DC charging interface is shown;

[0022] Figure 7 to Figure 10 Based on Figure 2 A schematic diagram of the current path of the battery charging circuit when the battery is self-charging;

[0023] Fig.11 A charging circuit diagram of a battery provided in another embodiment of the present invention;

[0024] Fig.12 A charging circuit diagram of a battery provided in another embodiment of the present invention;

[0025] Fig.13 Based on Fig.12 The diagram shows a schematic diagram of a current path of a battery charging circuit when charging using a first DC charging interface. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the present invention more obvious, the exemplary embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments of the present invention, and it should be understood that the present invention is not limited to the exemplary embodiments described herein. Based on the embodiments of the present invention described in the present invention, all other embodiments obtained by those skilled in the art without creative work should fall within the protection scope of the present invention.

[0027] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present invention. However, it is apparent to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some technical features well known in the art are not described.

[0028] It should be understood that the present invention can be implemented in different forms and should not be interpreted as limited to the embodiments set forth herein. On the contrary, these embodiments are provided to make the disclosure thorough and complete and to fully convey the scope of the present invention to those skilled in the art.

[0029] In order to fully understand the present invention, a detailed structure will be proposed in the following description to illustrate the technical solution proposed by the present invention. The optional embodiments of the present invention are described in detail as follows, but in addition to these detailed descriptions, the present invention may also have other implementations.

[0030] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0031] The present application embodiment provides a battery charging circuit, referring to Figure 1 , Figure 2 , Fig.11 and Fig.12 The charging circuit includes: a battery, a DC charging interface, a switch tube combination circuit and a heating control contactor. The battery includes a first part of cells and a second part of cells connected in series through a series node; the switch tube combination circuit is connected between the DC charging interface and the battery; the heating control contactor is connected between the switch tube combination circuit and the series node; when the heating control contactor is turned on and the switch tube combination circuit is configured as a boost circuit, the switch tube combination circuit is used to: boost the DC power input from the DC charging interface to charge the battery, and alternately control the first part of cells to discharge and then charge the second part of cells, or the second part of cells to discharge and then charge the first part of cells.

[0032] In the above scheme, by connecting the series node between the first part of the battery cells and the second part of the battery cells through the heating control contactor and the switch tube combination circuit, when the heating control contactor is turned on and the switch tube combination circuit is configured as a boost circuit, the switch tube combination circuit charges the battery after boosting the DC power input from the DC charging interface, and is also used to alternately control the first part of the battery cells to charge the second part of the battery cells after discharging, or to charge the first part of the battery cells after discharging the second part of the battery cells. Through the switch tube combination circuit and the heating control contactor, the first part of the battery cells and the second part of the battery cells are alternately charged and discharged with each other, and the internal resistance of the battery is used to generate heat to achieve self-heating of the battery. The self-heating temperature rise efficiency is high, and the charging speed of the battery at low temperature is improved. Compared with the external heating method, the battery self-heating scheme shown in the embodiment of the present application has less energy loss and improves the heating efficiency. And there is no need to distribute power to the battery heating device additionally, and there is no need to set up a condensation flow channel, a circulation system, etc. of the battery heating device, which reduces the cost. The above structures are described in detail below in conjunction with the accompanying drawings.

[0033] When setting up a battery, the battery may include a large number of battery cells, which may be first formed into a battery cell group, and then multiple battery cell groups may be combined into a battery pack as a battery. The battery cells in the battery cell group may be connected in series or in parallel to form a battery cell group, and different battery cell groups may be connected in parallel or in series. The battery cells in the battery may be divided into two parts, namely a first part of battery cells and a second part of battery cells, and the battery cells in each part of the first part of battery cells and the second part of battery cells may be connected in series or in parallel. However, the first part of battery cells and the second part of battery cells are connected in series, such as Figure 2 to Figure 13 As shown, there is a series node between the first part of the battery cells and the second part of the battery cells, and the series node can be led out of the battery and electrically connected to the outside. Specifically, the series node can be led out to the battery management system and electrically connected to the outside.

[0034] When dividing the first part of the battery cells and the second part of the battery cells, a variety of methods can be used. For example, the number of battery cells in the first part of the battery cells and the second part of the battery cells can each account for half of the total number of battery cells in the battery. That is, the number of battery cells in the first part of the battery cells and the second part of the battery cells is equal, and each accounts for half of the total number of battery cells in the battery. Of course, in addition to the above-mentioned methods, other division methods can also be used, not limited to the division method of each accounting for half.

[0035] When setting up a DC charging interface, the DC charging interface is a connector set on the vehicle and used to connect to an external charging gun. It can adopt a plug-in connection method such as a male or female connector to facilitate external electrical connection, so that external DC power can be input through the DC charging interface.

[0036] When setting up the switch tube combination circuit, refer to Figure 1 , the switch tube combination circuit is connected between the DC charging interface and the battery. When the switch tube combination circuit is configured as a boost circuit, the switch tube combination circuit is used to boost the DC power input from the DC charging interface and then charge the battery. That is, the switch tube combination circuit can be configured as a DC boost circuit, which boosts the DC power input from the DC charging interface and then charges the battery, so as to increase the charging voltage for charging the battery, thereby increasing the charging rate.

[0037] When the switch tube combination circuit is connected between the DC charging interface and the battery, multiple methods can be used. Figure 1 , Figure 2 , Fig.11 and Fig.12, the switch tube combination circuit may include a first positive electrode, a first negative electrode, a second positive electrode and a second negative electrode. Among them, the first positive electrode and the first negative electrode are respectively connected to the positive electrode and the negative electrode of the DC charging interface. The second positive electrode and the second negative electrode are respectively connected to the positive electrode and the negative electrode of the battery. That is, the first positive electrode and the first negative electrode in the switch tube combination circuit tend to be connected to one side of the DC charging interface, while the second positive electrode and the second negative electrode of the switch tube combination circuit tend to be connected to one side of the battery. It should be understood that the above only shows an exemplary connection method. In addition to this, other methods of connecting the switch tube combination circuit between the DC charging interface and the battery can also be used.

[0038] There are many ways to set the switch tube combination circuit. The following is an exemplary introduction to one setting method. It should be understood that the embodiment shown below is a specific introduction to the switch tube combination circuit of the present application, and is not intended to limit the switch tube combination circuit.

[0039] For example, refer to Figure 2 , the switch tube combination circuit may also include: at least one group of bridge arms and at least one inductor. Each group of bridge arms includes an upper bridge arm and a lower bridge arm connected in series; and when the number of bridge arm groups is at least two, at least two groups of bridge arms are connected in parallel; the positive electrode of each group of bridge arms is connected to the second positive electrode, and the negative electrode of each group of bridge arms is connected to the first negative electrode and the second negative electrode. At least one inductor corresponds to at least one group of bridge arms, and one end of each inductor is connected to the connection node between the upper bridge arm and the lower bridge arm of the corresponding group of bridge arms, and the other end is connected to the first positive electrode.

[0040] When determining the number of bridge arm groups, the number of bridge arm groups can be one group, two groups, three groups or more groups, and when the number of bridge arm groups is at least two groups, at least two groups of bridge arms are connected in parallel. Correspondingly, the number of inductors can also be one, two, three or more, and the number of inductors is equal to the number of bridge arm groups, and each group of bridge arms corresponds to a coil. Exemplarily, the number of bridge arm groups can be three groups, and the number of inductors can be three. In a more preferred embodiment, the three groups of bridge arms and the three inductors can all be bridge arms and inductors in the motor controller, that is, the bridge arms and inductors in the motor controller are reused as the bridge arms and inductors in the switch tube combination circuit of the present application, and there is no need to set up additional bridge arm circuits and inductors for the switch tube combination circuit of the present application, thereby reducing costs. Of course, the switch tube combination circuit is not limited to the above-mentioned methods. In addition, other methods can also be used. For example, the switch tube combination circuit can also be composed of an inductor, a group of bridge arm IGBTs and a bus capacitor.

[0041] refer to Figure 1 , Figure 2 , Fig.11 and Fig.12, the series node between the first part of the battery cells and the second part of the battery cells is also connected to the first positive electrode through the heating control contactor. When the heating control contactor is turned on and the switch tube combination circuit is configured as a boost circuit, the switch tube combination circuit is also used to alternately control the first part of the battery cells to charge the second part of the battery cells after discharging, or to charge the first part of the battery cells after discharging the second part of the battery cells. The internal resistance of the battery is used to generate heat to achieve self-heating of the battery, and the self-heating temperature rise efficiency is high, which improves the charging speed of the battery at low temperatures. Compared with the external heating method, the battery self-heating scheme shown in the embodiment of the present application has less energy loss and improves the heating efficiency. There is no need to distribute power to the battery heating device, and there is no need to set up a condensation flow channel, a circulation system, etc. for the battery heating device, thereby reducing costs.

[0042] When determining the number of DC charging interfaces, the number of DC charging interfaces can be one (as shown in the figure) or two. Correspondingly, the number of the above switch tube combination circuits is equal to the number of DC charging interfaces, and each DC charging interface corresponds to a switch tube combination circuit, so that the DC power flowing into each DC charging interface is boosted to charge the battery, thereby improving the charging efficiency.

[0043] Exemplary, reference Figure 1 , Figure 2 , Fig.11 , Fig.12 , the DC charging interface may include a first DC charging interface and a second DC charging interface, and the switch tube combination circuit may include a first switch tube combination circuit and a second switch tube combination circuit. At this time, the first switch tube combination circuit is connected between the first DC charging interface and the battery, and the second switch tube combination circuit is connected between the second DC charging interface and the battery. The specific connection method can be adopted in a variety of ways. Exemplarily, the first DC charging interface can be connected to the positive and negative electrodes of the battery respectively through the first switch tube combination circuit, that is, the first switch tube combination circuit is used to boost the DC power flowing into the first DC charging interface and charge the battery. The second DC charging interface can be connected to the positive and negative electrodes of the battery through the second switch tube combination circuit, that is, the second switch tube combination circuit is used to boost the DC power flowing into the second DC charging interface and charge the battery.

[0044] When two DC charging interfaces and two switch tube combination circuits are provided, for example, at least one first positive electrode of the two switch tube combination circuits can be connected to the series node between the first part of the battery cells and the second part of the battery cells through a heating control contactor. Figure 1 , Figure 2 , Fig.12, the first positive electrode of one of the two switch tube combination circuits can be connected to the series node between the first part of the battery cells and the second part of the battery cells through the heating control contactor, and the switch tube combination circuit can be the first switch tube combination circuit or the second switch tube combination circuit. Fig.11 , the first positive electrodes in the two switch tube combination circuits can also be connected to the series node between the first part of the battery cells and the second part of the battery cells through the heating controller. It should be understood that the connection method between the heating control contactor and the two switch tube combination circuits can be other than the above-mentioned method.

[0045] Continue to refer Figure 1 , the heating control contactor is connected between the switch tube combination circuit and the series node. When the heating control contactor is turned on and the switch tube combination circuit is configured as a boost circuit, the switch tube combination circuit is used to: while charging the battery after boosting the DC power input from the DC charging interface, it also alternately controls the first part of the battery cells to charge the second part of the battery cells after discharging, or the second part of the battery cells to charge the first part of the battery cells after discharging. That is, when the heating control contactor is turned on and the switch tube combination circuit is configured as a boost circuit, the switch tube combination circuit is used to: while charging the battery after boosting the DC power input from the DC charging interface, it also alternately controls the first part of the battery cells to charge the second part of the battery cells after discharging, or the second part of the battery cells to charge the first part of the battery cells after discharging. Through the switch tube combination circuit and the heating control contactor, the first part of the battery cells and the second part of the battery cells are alternately charged and discharged with each other, and the internal resistance of the battery is used to generate heat to achieve self-heating of the battery. The self-heating temperature rise efficiency is high, which improves the charging speed of the battery at low temperatures. Compared with the external heating method, the battery self-heating solution shown in the embodiment of the present application has less energy loss and improves heating efficiency. It also does not require additional power distribution to the battery heating device, and does not require the installation of a condensation flow channel, circulation system, etc. of the battery heating device, thereby reducing costs.

[0046] Exemplarily, at least one of the first switch tube combination circuit and the second switch tube combination circuit can be connected to the series node through a heating control contactor. Specifically, the first switch tube combination circuit can be connected to the series node through a heating control contactor, while the second switch tube combination circuit is not connected to the series node through the heating control contactor; the second switch tube combination circuit can be connected to the series node through a heating control contactor, while the first switch tube combination circuit is not connected to the series node through the heating control contactor; the first switch tube combination circuit can also be connected to the series node through a heating control contactor, and the first switch tube combination circuit is also connected to the series node through a heating control contactor.

[0047] Exemplary, reference Figure 1 , Figure 2, Fig.12 The number of heating control contactors can be one, so that the first positive electrode of the first switch tube combination circuit can be connected to the series node between the first part of the battery cells and the second part of the battery cells through the heating control contactor. It should be understood that in addition to the above-mentioned method, other methods can be used to connect a heating control contactor to the switch tube combination circuit.

[0048] Exemplary, reference Fig.11 The heating control contactor may include a first heating control contactor and a second heating control contactor. The first positive pole of the first switch tube combination circuit is connected to the series node between the first part of the battery cells and the second part of the battery cells through the first heating control contactor. The first positive pole of the second switch tube combination circuit is connected to the series node between the first part of the battery cells and the second part of the battery cells through the second heating control contactor. It should be understood that in addition to the above-mentioned method, other methods can be used to connect the two heating control contactors to the switch tube combination circuit.

[0049] In other embodiments, reference Fig.12 , the second positive electrode of the switch tube combination circuit can also be connected to the positive electrode of the DC charging interface through a direct charging contactor. When the number of the switch tube combination circuit is one, it is only necessary to connect the second positive electrode of the switch tube combination circuit to the positive electrode of the DC charging interface through a direct charging contactor.

[0050] When the number of switch tube combination circuits is two, illustratively, the second positive electrode of the first switch tube combination circuit can be connected to the positive electrode of the first DC charging interface through a direct charging contactor; and / or, the second positive electrode of the second switch tube combination circuit can be connected to the positive electrode of the second DC charging interface through a direct charging contactor. Specifically, the second positive electrode of the first switch tube combination circuit can be connected to the positive electrode of the first DC charging interface through a direct charging contactor, while the second positive electrode of the second switch tube combination circuit is not connected to the positive electrode of the second DC charging interface. The second positive electrode of the second switch tube combination circuit can also be connected to the positive electrode of the second DC charging interface through a direct charging contactor, while the second positive electrode of the first switch tube combination circuit is not connected to the positive electrode of the first DC charging interface. The second positive electrode of the first switch tube combination circuit can also be connected to the positive electrode of the first DC charging interface through a direct charging contactor, and the second positive electrode of the second switch tube combination circuit can also be connected to the positive electrode of the second DC charging interface through a direct charging contactor.

[0051] Several implementation modes are described below by way of example with reference to the accompanying drawings.

[0052] like Figure 2 to Figure 10As shown, there are two DC charging interfaces and switch tube combination circuits, the DC charging interfaces are respectively the first DC charging interface and the second DC charging interface, and the switch tube combination circuits are respectively the first switch tube combination circuit and the second switch tube combination circuit. The first switch tube combination circuit is connected to the positive and negative electrodes of the battery and the first DC charging interface. Specifically, the first positive electrode and the first negative electrode of the first switch tube combination circuit are respectively connected to the positive and negative electrodes of the first DC charging interface, and the second positive electrode and the second negative electrode of the first switch tube combination circuit are respectively connected to the positive and negative electrodes of the battery. The second switch tube combination circuit is connected to the positive and negative electrodes of the battery and the second DC charging interface. Specifically, the first positive electrode and the first negative electrode of the second switch tube combination circuit are respectively connected to the positive and negative electrodes of the second DC charging interface, and the second positive electrode and the second negative electrode of the second switch tube combination circuit are respectively connected to the positive and negative electrodes of the battery.

[0053] Among them, the first switch tube combination circuit is composed of the three-phase IGBT VT1, VT2, VT3, VT4, VT5, VT6 of the motor controller and the bus capacitor C2 of the motor controller, and the second switch tube combination circuit is composed of the three-phase IGBT VT7, VT8, VT9, VT10, VT11, VT12 of the motor controller and the bus capacitor C4 of the motor controller.

[0054] The charging circuit also includes a pre-charging contactor K1, a pre-charging resistor R1, a main positive contactor K2, a main negative contactor K3, a DC charging positive contactor K4, a DC charging negative contactor K5, a first DC charging interface step-down side capacitor C1, a DC charging positive contactor K6, a DC charging negative contactor K7, a second DC charging interface step-down side capacitor C3, and a first heating control contactor K8.

[0055] Among them, the first DC charging interface, the DC charging positive contactor K4, the DC charging negative contactor K5, the first DC charging interface step-down side capacitor C1, the motor controller three-phase IGBT VT1, VT2, VT3, VT4, VT5, VT6, and the motor controller bus capacitor C2 constitute the first DC charging circuit. The second DC charging interface, the DC charging positive contactor K6, the DC charging negative contactor K7, the second DC charging interface step-down side capacitor C3, the motor controller three-phase IGBT VT7, VT8, VT9, VT10, VT11, VT12, and the motor controller bus capacitor C4 constitute the second DC charging circuit. One end of the first heating control contactor K8 is connected to the first positive electrode of the first switch tube combination circuit (i.e., the common node of the three first inductors), and the other end is connected to the half-pack position of the battery pack (the series node between the first part of the battery cell and the second part of the battery cell).

[0056] In addition, reference Figure 1A control unit can also be provided, which can communicate with an external charging pile, control the first charging circuit and the second charging circuit to charge the battery, and control the first switch tube combination circuit to realize alternating control of the first part of the battery cells to charge the second part of the battery cells after discharging, or the second part of the battery cells to charge the first part of the battery cells after discharging. The internal resistance of the battery is used to generate heat to achieve self-heating of the battery. The control unit can include two sets of independent DC charging control guidance circuits, which interact with the charging pile through CAN signals through the charging subnet to control each stage of DC charging and the DC charging contactors of the two DC charging circuits.

[0057] Combine the following Figure 3 to Figure 6 The working control flow of two charging circuits is introduced by way of example.

[0058] 1. The control process when charging through the first DC charging port is as follows:

[0059] When the control unit detects the signal that the first DC charging interface is plugged into the charging gun, the first DC charging circuit process can be entered. Before starting boost charging, the control unit closes the DC charging positive contactor K4, the DC charging negative contactor K5, the main positive contactor K2, and the main negative contactor K3. Boost charging is divided into the following two stages:

[0060] (1) Control the lower bridge arms VT2, VT4, and VT6 to charge the first inductor. The current flows as follows: Figure 3 shown.

[0061] (2) The lower bridge arms VT6, VT4, and VT2 are turned off, and the upper bridge arms VT5, VT3, and VT1 are turned on. Since the current direction in the first inductor does not change, the voltage output by the first inductor is superimposed on the voltage output by the first DC charging interface to achieve voltage boosting, and then the battery is charged. The current flows as follows: Figure 4 shown.

[0062] 2. The control flow when charging through the second DC charging port is as follows:

[0063] When the control unit detects the signal that the second DC charging interface is plugged into the charging gun, the second DC charging circuit process can be entered. Before starting boost charging. The control unit closes the DC charging positive contactor K6, the DC charging negative contactor K7, the main positive contactor K2, and the main negative contactor K3. Boost charging is divided into two stages:

[0064] (1) Control the lower bridge arms VT8, VT10, and VT12 to charge the second inductor. The current flows as follows: Figure 5 shown.

[0065] (2) Control the lower bridge arms VT8, VT10, and VT12 to turn off, and the upper bridge arms VT7, VT9, and VT11 to turn on. Since the current direction in the second inductor does not change, the voltage output by the second inductor is superimposed on the voltage output by the second DC charging interface to achieve voltage boost, and then the battery is charged. The current flows as follows: Figure 6 shown.

[0066] The above two charging circuits can be controlled independently. When there is a charging interaction process in any circuit, the control unit controls the charging process accordingly. Any circuit can be charged separately, or both circuits can be charged simultaneously. Charging both circuits simultaneously can increase the charging speed and meet the high-power charging needs of the vehicle. A switch tube combination circuit is configured in each of the first DC charging circuit and the second DC charging circuit for boost charging, which is compatible with national standard DC charging piles of different voltage platforms on the market. In the scenario where only 500V charging piles are available, it can ensure that the vehicle can be charged with DC, thereby improving compatibility.

[0067] The charging performance of the battery decreases at low temperatures. The charging circuit shown in the example of this application can heat the battery, increase the battery temperature to increase the charging current. And the charging circuit shown in the embodiment of this application can realize the self-heating of the battery by using the first switch tube combination circuit when charging any charging circuit or charging two circuits at the same time, so as to realize the simultaneous charging and battery self-heating and improve the charging efficiency.

[0068] The process of realizing charging + battery heating control is as follows:

[0069] The control unit can charge the battery according to the above charging control process. The current path is the same as above and will not be repeated here. The control unit can control VT1, VT3, and VT5 to be turned on at the same time, control VT1, VT3, and VT5 to be turned off at the same time, control VT2, VT4, and VT6 to be turned on at the same time, control VT2, VT4, and VT6 to be turned off at the same time, and control the timing of VT1, VT3, and VT5 to be turned on at the same time according to a certain frequency cycle control. The corresponding current direction is as follows: Figure 7 , Figure 8 , Fig. 9 , Fig.10 As shown, the currents between the first part of the battery cells and the second part of the battery cells oscillate with each other to perform pulse charging and discharging. Due to the internal resistance of the battery, the battery itself generates heat, thereby achieving self-heating of the battery.

[0070] like Fig.11 In another embodiment shown, Figure 2 Based on the charging circuit shown, the first positive electrode of the second switch tube combination circuit can be connected to the half pack position of the battery pack (the series node between the first part of the battery cell and the second part of the battery cell) through the second heating control contactor K9. Fig.11, one end of the second heating control contactor K9 is connected to the first positive pole of the second switch tube combination circuit (i.e., the common node of the three second inductors), and the other end is connected to the half-pack position of the battery pack (the series node between the first part of the battery cells and the second part of the battery cells). In the above manner, it can be achieved that when one of the DC charging circuits is boosted and charged, the switch combination circuit in the other DC charging circuit is self-heated. For example, when the first DC charging circuit is boosted and charged, the second switch tube combination circuit can be used for self-heating. The self-heating circuit can be selected by closing or opening the second heating control contactor K8 and the second heating control contactor K9.

[0071] like Fig.12 In another embodiment shown, Figure 2 On the basis of the charging circuit shown, the second positive electrode of the first switch tube combination circuit is also connected to the positive electrode of the first DC charging interface, and a direct charging contactor K10 is added to the first DC charging circuit, so that the first switch tube combination circuit can be used for self-heating when the first DC charging circuit is directly charged. At this time, it is not necessary to use the first switch tube combination circuit in the first DC charging circuit for boosting. Fig.13 As shown, after the DC charging direct connection contactor K9 is closed, the DC charging direct connection contactor K9, the DC charging negative contactor K5, the main positive contactor K2, and the main negative contactor K3 can be controlled to be closed, so that the first DC charging interface is directly connected to the battery for charging without boosting. Of course, the first DC charging circuit can also be boosted by disconnecting the direct charging contactor K10. The boost charging current path of the first DC charging circuit is as follows Figure 3 , Figure 4 The boost charging current path of the second DC charging circuit is as shown in Figure 5 , Figure 6 The self-heating control current path is as shown in Figure 7 to Figure 10 It should be noted that the above DC circuit can also be added to the second DC charging circuit. Specifically, the second positive electrode in the second switch tube combination circuit can be connected to the positive electrode of the second DC charging interface, and a DC charging contactor can be added between the two.

[0072] In the various embodiments shown above, by connecting the series node between the first part of the battery cells and the second part of the battery cells to the switch tube combination circuit through the heating control contactor, when the heating control contactor is turned on and the switch tube combination circuit is configured as a boost circuit, the switch tube combination circuit charges the battery after boosting the DC power input from the DC charging interface, and is also used to alternately control the first part of the battery cells to charge the second part of the battery cells after discharging, or to charge the first part of the battery cells after discharging the second part of the battery cells. Through the switch tube combination circuit and the heating control contactor, the first part of the battery cells and the second part of the battery cells are alternately charged and discharged with each other, and the internal resistance of the battery is used to generate heat to achieve self-heating of the battery. The self-heating temperature rise efficiency is high, and the charging speed of the battery at low temperatures is improved. Compared with the external heating method, the battery self-heating scheme shown in the embodiment of the present application has less energy loss and improves the heating efficiency. And there is no need to distribute power to the battery heating device additionally, and there is no need to set up a condensation flow channel, a circulation system, etc. of the battery heating device, which reduces costs.

[0073] In addition, an embodiment of the present application further provides an electric vehicle, which includes: a vehicle body, and a charging circuit for any of the above-mentioned batteries arranged on the vehicle body. The electric vehicle may be an electric passenger vehicle, an electric commercial vehicle, an electric engineering vehicle, etc. The vehicle body may specifically include a frame, a vehicle, a vehicle shell, wheels, etc. The battery may be a power battery on the electric vehicle, or an energy storage battery used in a battery swap station, or other types of batteries.

[0074] The present invention has been described by the above embodiments, but it should be understood that the above embodiments are only for the purpose of example and description, and are not intended to limit the present invention to the scope of the described embodiments. In addition, it can be understood by those skilled in the art that the present invention is not limited to the above embodiments, and more variations and modifications can be made according to the teachings of the present invention, and these variations and modifications all fall within the scope of the protection claimed by the present invention. The protection scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A battery charging circuit, characterized in that: include: A battery, comprising a first portion of cells and a second portion of cells connected in series via a series node; DC charging interface; A switch tube combination circuit, connected between the DC charging interface and the battery; A heating control contactor connected between the switch tube combination circuit and the series node; Wherein, when the heating control contactor is turned on and the switch tube combination circuit is configured as the boost circuit, the switch tube combination circuit is used to: boost the DC power input from the DC charging interface to charge the battery, and also alternately control the first part of the battery cells to discharge and then charge the second part of the battery cells, or to discharge and then charge the first part of the battery cells.

2. The charging circuit according to claim 1, characterized in that: The switch tube combination circuit comprises a first positive electrode, a first negative electrode, a second positive electrode and a second negative electrode; The first positive electrode and the first negative electrode are connected to the positive electrode and the negative electrode of the DC charging interface respectively, and the second positive electrode and the second negative electrode are connected to the positive electrode and the negative electrode of the battery respectively; The series node is connected to the first positive electrode through the heating control contactor.

3. The charging circuit according to claim 2, characterized in that: The switch tube combination circuit also includes: At least one group of bridge arms, each group of bridge arms includes an upper bridge arm and a lower bridge arm connected in series; and when the number of groups of bridge arms is at least two, at least two groups of bridge arms are connected in parallel; the positive electrode of each group of bridge arms is connected to the second positive electrode, and the negative electrode of each group of bridge arms is connected to the first negative electrode and the second negative electrode; At least one inductor, wherein the at least one inductor corresponds one-to-one to the at least one group of bridge arms; one end of each of the inductors is connected to a connection node between an upper bridge arm and a lower bridge arm of the corresponding group of bridge arms, and the other end is connected to the first positive electrode.

4. The charging circuit according to claim 3, characterized in that: The number of groups of the bridge arms is three, and the number of the inductors is three.

5. The charging circuit according to claim 4, characterized in that: The three groups of bridge arms and the three inductors are all bridge arms and inductors in a motor controller.

6. The charging circuit according to claim 3, characterized in that: The second positive electrode of the switch tube combination circuit is also connected to the positive electrode of the DC charging interface through a direct charging contactor.

7. The charging circuit according to any one of claims 2 to 6, characterized in that: The DC charging interface includes a first DC charging interface and a second DC charging interface, and the switch tube combination circuit includes a first switch tube combination circuit and a second switch tube combination circuit; the first switch tube combination circuit is connected between the first DC charging interface and the battery, and the second switch tube combination circuit is connected between the second DC charging interface and the battery; At least one of the first switch tube combination circuit and the second switch tube combination circuit is connected to the series node through the heating control contactor.

8. The charging circuit according to claim 7, characterized in that: The first DC charging interface is connected to the positive electrode and the negative electrode of the battery respectively through the first switch tube combination circuit; the second DC charging interface is connected to the positive electrode and the negative electrode of the battery in a shunt through the second switch tube combination circuit; At least one of the first positive electrodes of the two switch tube combination circuits is connected to the series node through the heating control contactor.

9. The charging circuit according to claim 8, characterized in that: The number of the heating control contactor is one; The first positive electrode of the first switch tube combination circuit is connected to the series node between the first part of the battery cells and the second part of the battery cells through the heating control contactor.

10. The charging circuit according to claim 8, characterized in that: The heating control contactor comprises a first heating control contactor and a second heating control contactor; The first positive electrode of the first switch tube combination circuit is connected to the series node between the first part of the battery cells and the second part of the battery cells through the first heating control contactor; The first positive electrode of the second switch tube combination circuit is connected to the series node between the first part of the battery cells and the second part of the battery cells through the second heating control contactor.

11. The charging circuit according to claim 8, characterized in that: The second positive electrode of the first switch tube combination circuit is also connected to the positive electrode of the first DC charging interface through a direct charging contactor; and / or, The second positive electrode of the second switch tube combination circuit is also connected to the positive electrode of the second DC charging interface through a direct charging contactor.

12. The charging circuit according to claim 1, characterized in that: The number of battery cells in the first part of battery cells and the number of battery cells in the second part of battery cells each account for half of the total battery cells of the battery.

13. An electric vehicle, characterized in that: include: Vehicle body; A battery charging circuit according to any one of claims 1 to 12 provided on the vehicle body.

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