A charging device and an electric vehicle

Abstract

The application provides a charging device and an electric vehicle. The electric vehicle is provided with a first battery group for providing power, and a second battery group. The device is connected with the first battery group and the second battery group. The charging device comprises a control unit and a voltage conversion unit connected with the control unit. The control unit is used for controlling the voltage conversion unit to convert the voltage provided by the second battery group into the charging voltage of the first battery group, so that the second battery group charges the first battery group through the charging device when the electric quantity of the first battery group is lower than a first preset threshold. The control unit is also used for controlling the voltage conversion unit to convert the voltage provided by the first battery group into the charging voltage of the second battery group, so that the first battery group charges the second battery group through the charging device when the charging electric quantity of the first battery group is higher than a second preset threshold. In this way, the universality of the battery is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a charging device and an electric vehicle. BACKGROUND

[0002] In the modern society with developed transportation, many new energy transportation tools such as electric motorcycles and electric vehicles appear. These new energy transportation tools abandon the previous oil supply mode, reduce environmental pollution, and gradually become a new direction of vehicle development.

[0003] The existing electric vehicles have different endurance capabilities. Different power layout schemes need to be designed according to different endurance requirements, which results in a large workload of the research and development personnel. In addition, different specifications of batteries are required in each scheme. Different specifications of batteries are required for different endurance requirements of electric vehicles. The batteries of electric vehicles with different endurance requirements cannot be used universally, which results in poor universality of the batteries. SUMMARY

[0004] Therefore, the present application provides a charging device and an electric vehicle to solve the problem of poor universality of the batteries in the prior art.

[0005] In a first aspect, an embodiment of the present application provides a charging device applied to an electric vehicle, comprising:

[0006] A first battery pack for providing power is arranged on the electric vehicle, characterized in that a second battery pack is also arranged on the electric vehicle, and the charging device is connected with the first battery pack and the second battery pack; the charging device comprises a control unit and a voltage conversion unit connected with the control unit.

[0007] The control unit is configured to control the voltage conversion unit to convert the voltage provided by the second battery pack into the charging voltage of the first battery pack, so that the second battery pack charges the first battery pack through the charging device when the power of the first battery pack is lower than a first preset threshold.

[0008] The control unit is also configured to control the voltage conversion unit to convert the voltage provided by the first battery pack into the charging voltage of the second battery pack, so that the first battery pack charges the second battery pack through the charging device when the charging power of the first battery pack is higher than a second preset threshold, wherein the second preset threshold is greater than the first preset threshold.

[0009] Preferably, the charging device further comprises:

[0010] The control unit is specifically configured to, when receiving a first control instruction sent by the second battery pack, control the voltage conversion unit to convert a voltage provided by the second battery pack into a charging voltage of the first battery pack according to the first control instruction.

[0011] Or,

[0012] When receiving a second control instruction sent by the first battery pack, control the voltage conversion unit to convert a voltage provided by the first battery pack into a charging voltage of the second battery pack according to the second control instruction.

[0013] Preferably, the voltage conversion unit comprises a first switch, a second switch, a third switch, a fourth switch and an inductor.

[0014] The control terminals of the first switch, the second switch, the third switch and the fourth switch are connected with the control unit; a first terminal of the first switch is connected with one end of the first battery pack, a second terminal of the first switch is connected with a first terminal of the second switch and a first terminal of the inductor; a second terminal of the second switch is connected with another end of the first battery pack; a first terminal of the third switch is connected with a second terminal of the inductor and a first terminal of the fourth switch, a second terminal of the third switch is connected with one end of the second battery pack, and a second terminal of the fourth switch is connected with another end of the second battery pack.

[0015] Preferably, the voltage conversion unit further comprises a first resistor and a second resistor.

[0016] The second terminal of the second switch being connected with another end of the first battery pack comprises:

[0017] The second terminal of the second switch is connected with another end of the first battery pack through the first resistor.

[0018] One end of the first resistor connected with another end of the first battery pack is grounded.

[0019] The second terminal of the third switch being connected with one end of the second battery pack comprises:

[0020] The second terminal of the third switch is connected with one end of the second battery pack through the second resistor.

[0021] One end of the second resistor connected with one end of the second battery pack is grounded.

[0022] Preferably, the first control instruction comprises: a first pulse width modulation signal received by the control end of the first switch, a second pulse width modulation signal received by the control end of the second switch, a third pulse width modulation signal received by the control end of the third switch, and a fourth pulse width modulation signal received by the control end of the fourth switch; wherein the first, second, third and fourth pulse width modulation signals all have a first period as a signal period, and in the first period, the duty cycle of the fourth switch is less than the difference between 1 and the duty cycle of the second switch.

[0023] Alternatively, the first control instruction comprises: a fifth pulse width modulation signal received by the control end of the first switch, a sixth pulse width modulation signal received by the control end of the second switch, a seventh pulse width modulation signal received by the control end of the third switch, and an eighth pulse width modulation signal received by the control end of the fourth switch; wherein the fifth, sixth, seventh and eighth pulse width modulation signals all have a second period as a signal period, and in the second period, the duty cycle of the fourth switch is greater than the difference between 1 and the duty cycle of the second switch.

[0024] Preferably, the second control instruction comprises: a ninth pulse width modulation signal received by the control end of the first switch, a tenth pulse width modulation signal received by the control end of the second switch, an eleventh pulse width modulation signal received by the control end of the third switch, and a twelfth pulse width modulation signal received by the control end of the fourth switch; wherein the ninth, tenth, eleventh and twelfth pulse width modulation signals all have a third period as a signal period, and in the third period, the duty cycle of the first switch is less than the difference between 1 and the duty cycle of the third switch.

[0025] Alternatively, the second control instruction comprises: a thirteenth pulse width modulation signal received by the control end of the first switch, a fourteenth pulse width modulation signal received by the control end of the second switch, a fifteenth pulse width modulation signal received by the control end of the third switch, and a sixteenth pulse width modulation signal received by the control end of the fourth switch; wherein the thirteenth, fourteenth, fifteenth and sixteenth pulse width modulation signals all have a fourth period as a signal period, and in the fourth period, the duty cycle of the first switch is greater than the difference between 1 and the duty cycle of the third switch.

[0026] In a second aspect, the embodiments of the present application provide an electric vehicle, wherein the electric vehicle is provided with a first battery pack for providing power, and the electric vehicle can also be provided with a second battery pack and a charging device, and the charging device is the charging device of any one of the first aspect.

[0027] Preferably, the second battery pack is connected with the first battery pack, and is configured to acquire a charging voltage of the first battery pack when the electric quantity of the first battery pack is lower than a first preset threshold, and determine the first control instruction according to the charging voltage of the first battery pack and a voltage provided by the second battery pack, and send the first control instruction to a control unit of the charging device.

[0028] Preferably, the second battery pack is configured to acquire the charging voltage of the first battery pack when the electric quantity of the first battery pack is lower than the first preset threshold, and determine the first control instruction according to a first pulse width modulation signal received by a control end of the first switch, a second pulse width modulation signal received by a control end of the second switch, a third pulse width modulation signal received by a control end of the third switch, and a fourth pulse width modulation signal received by a control end of the fourth switch when the charging voltage of the first battery pack is lower than the voltage provided by the second battery pack, and send the first control instruction to the control unit of the charging device.

[0029] Preferably, the second battery pack is configured to acquire the charging voltage of the first battery pack when the electric quantity of the first battery pack is lower than the first preset threshold, and determine the first control instruction according to a first pulse width modulation signal received by a control end of the first switch, a second pulse width modulation signal received by a control end of the second switch, a third pulse width modulation signal received by a control end of the third switch, and a fourth pulse width modulation signal received by a control end of the fourth switch when the charging voltage of the first battery pack is lower than the voltage provided by the second battery pack, and send the first control instruction to the control unit of the charging device.

[0030] Preferably, the first battery pack is further configured to send a power supplement request message to the second battery pack when the electric quantity of the first battery pack is lower than the first preset threshold, and the power supplement request message carries the charging voltage of the first battery pack.

[0031] The second battery pack is configured to receive the power supplement request message, and acquire the charging voltage of the first battery pack from the power supplement request message when the electric quantity of the second battery pack is greater than a third preset threshold.

[0032] Preferably, the first battery pack is further configured to acquire a charging voltage of the second battery pack when the charging electric quantity of the first battery pack is higher than a second preset threshold, and determine the second control instruction according to the charging voltage of the second battery pack and a voltage provided by the first battery pack, and send the second control instruction to the control unit of the charging device.

[0033] Preferably, the first battery pack is specifically configured to acquire the charging voltage of the second battery pack when the charging capacity of the first battery pack is higher than a second preset threshold, and when the voltage provided by the first battery pack is greater than the charging voltage of the second battery pack, determine the ninth pulse width modulation signal received by the control end of the first switch, the tenth pulse width modulation signal received by the control end of the second switch, the eleventh pulse width modulation signal received by the control end of the third switch, and the twelfth pulse width modulation signal received by the control end of the fourth switch as the second control instruction, wherein the ninth pulse width modulation signal, the tenth pulse width modulation signal, the eleventh pulse width modulation signal, and the twelfth pulse width modulation signal all have the third period as the signal period, and in the third period, the difference between the duty cycle of the first switch and the duty cycle of the third switch is less than 1.

[0034] When the voltage provided by the first battery pack is less than the charging voltage of the second battery pack, determine the thirteenth pulse width modulation signal received by the control end of the first switch, the fourteenth pulse width modulation signal received by the control end of the second switch, the fifteenth pulse width modulation signal received by the control end of the third switch, and the sixteenth pulse width modulation signal received by the control end of the fourth switch as the second control instruction, wherein the thirteenth pulse width modulation signal, the fourteenth pulse width modulation signal, the fifteenth pulse width modulation signal, and the sixteenth pulse width modulation signal all have the fourth period as the signal period, and in the fourth period, the difference between the duty cycle of the first switch and the duty cycle of the third switch is greater than 1.

[0035] Preferably, the first battery pack is further configured to send a charging request message to the second battery pack when the first battery pack is in a mode of being charged by an external power supply and the battery capacity of the first battery pack is greater than a second preset threshold.

[0036] The second battery pack is further configured to receive the charging request message and return an acceptance charging response message to the first battery pack when the battery capacity of the second battery pack is less than a fourth preset threshold, wherein the acceptance charging response message carries the charging voltage of the second battery pack.

[0037] The first battery pack is specifically configured to receive the acceptance charging response message and acquire the charging voltage of the second battery pack according to the acceptance charging response message.

[0038] The application provides a charging device applied to an electric vehicle. The electric vehicle is provided with a first battery group for providing power, and is also provided with a second battery group. The charging device is connected with the first battery group and the second battery group. The charging device comprises a control unit and a voltage conversion unit connected with the control unit. The control unit is used for controlling the voltage conversion unit to convert the voltage provided by the second battery group into the charging voltage of the first battery group, so that the second battery group charges the first battery group through the charging device when the electric quantity of the first battery group is lower than a first preset threshold. The control unit is also used for controlling the voltage conversion unit to convert the voltage provided by the first battery group into the charging voltage of the second battery group, so that the first battery group charges the second battery group through the charging device when the charging electric quantity of the first battery group is higher than a second preset threshold, wherein the second preset threshold is greater than the first preset threshold. That is to say, the bidirectional charging between the first battery group and the second battery group can be realized through the charging device. When the electric quantity of the first battery group of the electric vehicle is insufficient in the driving state of the electric vehicle, the second battery group can directly charge the first battery group through the charging device, so that the first battery group can continue to supply power to the motor drive and meet the long endurance requirement. When the charging electric quantity of the first battery group is higher than the second preset threshold in the charging state of the electric vehicle, the first battery group charges the second battery group through the charging device, so that the second battery group can store electric quantity. In addition, for different endurance requirements, the first battery group does not need to be redesigned, and only the electric quantity of the second battery group needs to be redesigned according to the endurance requirement of the electric vehicle, thereby improving the universality of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative labor.

[0040] Figure 1 A structural schematic diagram of a charging device provided by the embodiments of the present application;

[0041] Figure 2 A structural schematic diagram of a voltage conversion unit provided by the embodiments of the present application;

[0042] Figure 3 A control signal schematic diagram provided by the embodiments of the present application;

[0043] Figure 4 Another control signal schematic diagram provided by the embodiments of the present application;

[0044] Figure 5Another control signal schematic diagram provided by the embodiment of the present application;

[0045] Figure 6 Another control signal schematic diagram provided by the embodiment of the present application;

[0046] Figure 7 Another voltage conversion unit structure schematic diagram provided by the embodiment of the present application;

[0047] Figure 8 An electric vehicle structure schematic diagram provided by the embodiment of the present application;

[0048] Figure 9 Another electric vehicle structure schematic diagram provided by the embodiment of the present application;

[0049] Figure 10 Another electric vehicle structure schematic diagram provided by the embodiment of the present application; DETAILED DESCRIPTION

[0050] In order to better understand the technical solutions of the present application, the embodiments of the present application are described in detail below in combination with the drawings.

[0051] It should be clear that the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0052] The terms used in the embodiments of the present application are only for the purpose of describing the specific embodiments, and are not intended to limit the present application. The singular forms "a", "an" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0053] It should be understood that the term "and / or" used herein is only to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents that the front and rear associated objects are a "or" relationship.

[0054] Before specifically introducing the embodiments of the present application, first explain the terms applied or possibly applied by the embodiments of the present application.

[0055] CAN(Controller Area Network, controller area network): CAN bus is a serial data communication protocol developed to solve the data exchange between numerous control and test instruments in modern vehicles. It is a multi-master bus, and the communication medium can be twisted pair, coaxial cable or optical fiber. The communication rate can be up to 1 Mbps. CAN bus can connect multiple unit buses, and any node on the CAN bus can actively send information to other nodes on the network at any time without distinction, so free communication can be achieved between nodes.

[0056] MOS tube: MOSFET is the abbreviation of MOSFET, MOSFET metal-oxide semiconductor field effect transistor, also known as gold-oxygen field effect transistor. MOS tube is a voltage-controlled element, and as long as the required voltage is added to the voltage-controlled element, the MOS tube can be turned on. MOS tube is often used as a switch, and when the MOS tube is turned on, it is equivalent to closing the switch.

[0057] Duty cycle: refers to the time the circuit is turned on as a percentage of the entire circuit working period.

[0058] Pulse width modulation (PWM, Pulse Width Modulation): It is an analog control method. According to the change of the corresponding load, the bias of the transistor base or MOS tube gate is modulated to change the conduction time of the transistor or MOS tube. Using digital control to generate a square wave with different duty cycles (a signal that is constantly switching between on and off) to control the analog output, thereby realizing the change of the output of the switching power supply. This method can make the output voltage of the power supply remain constant when the working conditions change. It is a very effective technology for using digital signals of microprocessors to control analog circuits.

[0059] Boost circuit: It is a traditional boost converter, which is a switching DC boost circuit. By controlling the off of the MOS tube in the circuit, the output voltage can be higher than the input voltage. According to the input voltage and output voltage parameters, the duty cycle can be determined to make the circuit output the required input voltage.

[0060] Buck circuit: It is a traditional buck converter, which is a switching DC buck circuit. By controlling the off of the MOS tube in the circuit, the output voltage can be lower than the input voltage. According to the input voltage and output voltage parameters, the duty cycle can be determined to make the circuit output the required input voltage.

[0061] In the related art, the endurance capabilities of existing electric vehicles are configured differently, and different power layouts need to be designed for different endurance capability requirements, resulting in a large workload for researchers. Moreover, different specifications of batteries are required in each scheme, and different specifications of batteries need to be configured for different endurance requirements of electric vehicles. The batteries of electric vehicles with different endurance requirements cannot be used universally due to different specifications, resulting in poor universality of the batteries.

[0062] To solve the above problems, an embodiment of the present application provides a charging device applied to an electric vehicle. The electric vehicle is provided with a first battery pack for providing power, and is also provided with a second battery pack. The charging device is connected with the first battery pack and the second battery pack. The charging device comprises a control unit and a voltage conversion unit connected with the control unit. The control unit is configured to control the voltage conversion unit to convert the voltage provided by the second battery pack into the charging voltage of the first battery pack, so that the second battery pack charges the first battery pack through the charging device when the power of the first battery pack is lower than a first preset threshold. The control unit is also configured to control the voltage conversion unit to convert the voltage provided by the first battery pack into the charging voltage of the second battery pack, so that the first battery pack charges the second battery pack through the charging device when the charging power of the first battery pack is higher than a second preset threshold, wherein the second preset threshold is greater than the first preset threshold. That is, the charging device can realize bidirectional charging between the first battery pack and the second battery pack. When the power of the first battery pack of the electric vehicle is insufficient in the driving state of the electric vehicle, the second battery pack can directly charge the first battery pack through the charging device, so that the first battery pack can continue to supply power to the motor drive to meet the long endurance requirement. When the charging power of the first battery pack is higher than the second preset threshold in the charging state of the electric vehicle, the first battery pack charges the second battery pack through the charging device, so that the second battery pack can store power. Moreover, for different endurance capability requirements, it is not necessary to redesign the first battery pack, but only to redesign the power of the second battery pack according to the endurance requirement of the electric vehicle, thereby improving the universality of the battery. The following will be described in detail.

[0063] Figure 1 A charging device structure schematic diagram is provided for an embodiment of the present application, which is applied to an electric vehicle. The electric vehicle is provided with a first battery pack for providing power, and is also provided with a second battery pack. The charging device is connected with the first battery pack and the second battery pack. As shown in the figure, the charging device 100 comprises: Figure 1

[0064] ​The control unit 101 is connected with the voltage conversion unit 102, and is configured to control the voltage conversion unit 102 to convert the voltage provided by the second battery pack into the charging voltage of the first battery pack, so that the second battery pack charges the first battery pack through the charging device when the electric quantity of the first battery pack is lower than the first preset threshold.

[0065] The control unit 101 is further configured to control the voltage conversion unit 102 to convert the voltage provided by the first battery pack into the charging voltage of the second battery pack, so that the first battery pack charges the second battery pack through the charging device when the charging electric quantity of the first battery pack is higher than the second preset threshold, wherein the second preset threshold is greater than the first preset threshold.

[0066] In the embodiment of the present application, the charging device 100 is connected with the first battery pack and the second battery pack, and the charging device 100 comprises the control unit 101 and the voltage conversion unit 102. The control unit 101 is connected with the voltage conversion unit 102. When the electric quantity of the first battery pack is lower than the first preset threshold, the second battery pack can charge the first battery pack through the charging device. At this time, the control unit 101 can control the voltage conversion unit 102 to convert the voltage provided by the second battery pack into the charging voltage of the first battery pack. When the charging electric quantity of the first battery pack is higher than the second preset threshold, the first battery pack can charge the second battery pack through the charging device. At this time, the control unit 101 controls the voltage conversion unit 102 to convert the voltage provided by the first battery pack into the charging voltage of the second battery pack.

[0067] It should be noted that the charging electric quantity of the first battery pack is the battery electric quantity of the first battery pack in the charging state.

[0068] It should be noted that the second preset threshold is greater than the first preset threshold. For example, the first preset threshold can be 10% of the total electric quantity of the first battery pack, or can be 15% of the total electric quantity of the first battery pack; the second preset threshold can be 85% of the total electric quantity of the first battery pack, or can be 90% of the total electric quantity of the first battery pack. Of course, the first preset threshold and the second preset threshold can also be other values, and the present application does not limit this.

[0069] As a possible implementation manner, the control unit 101 is specifically configured to, when receiving the first control instruction sent by the second battery pack, control the voltage conversion unit 102 to convert the voltage provided by the second battery pack into the charging voltage of the first battery pack according to the first control instruction.

[0070] Or,

[0071] When receiving the second control instruction sent by the first battery pack, the control unit 101 controls the voltage conversion unit 102 to convert the voltage provided by the first battery pack into the charging voltage of the second battery pack according to the second control instruction.

[0072] Specifically, when the first battery pack has a low power, the second battery pack can charge the first battery pack through the charging device, the second battery pack sends a first control instruction to the control unit 101 of the charging device, the control unit 101 receives the first control instruction, and controls the voltage conversion unit 102 to convert the voltage provided by the second battery pack into the charging voltage of the first battery pack according to the first control instruction. When the charging power of the first battery pack is higher than the second preset threshold, the first battery pack can charge the second battery pack through the charging device, the first battery pack sends a second control instruction to the control unit 101 of the charging device, the control unit 101 receives the second control instruction, and controls the voltage conversion unit 102 to convert the voltage provided by the first battery pack into the charging voltage of the second battery pack according to the second control instruction.

[0073] As a possible implementation manner, as shown in Figure 2 The voltage conversion unit 102 includes a first switch Q1, a second switch Q2, a third switch Q3, a fourth switch Q4, and an inductor L.

[0074] The control ends of the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 are connected with the control unit 101; the first end of the first switch Q1 is connected with one end of the first battery pack, and the second end of the first switch Q1 is connected with the first end of the second switch Q2 and the first end of the inductor L; the second end of the second switch Q2 is connected with the other end of the first battery pack; the first end of the third switch Q3 is connected with the second end of the inductor L and the first end of the fourth switch Q4, the second end of the third switch Q3 is connected with one end of the second battery pack, and the second end of the fourth switch Q4 is connected with the other end of the second battery pack.

[0075] In the embodiment of the present application, by controlling the on-off of the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 in the voltage conversion unit 102, the circuit of the voltage conversion unit 102 is converted into a voltage boosting circuit or a voltage reducing circuit, so as to boost or reduce the voltage provided by the second battery pack to convert into the charging voltage required by the first battery pack, or boost or reduce the voltage provided by the first battery pack to convert into the charging voltage required by the second battery pack.

[0076] As one possible implementation, when the charge of the first battery pack is lower than a first preset threshold, the second battery pack charges the first battery pack via a charging device. The second battery pack generates a first control command and sends it to the control unit 101 of the charging device 100. The control unit 101 receives the first control command. At this time, the first control command includes: a first pulse width modulation signal received by the control terminal of the first switch Q1, a second pulse width modulation signal received by the control terminal of the second switch Q2, a third pulse width modulation signal received by the control terminal of the third switch Q3, and a fourth pulse width modulation signal received by the control terminal of the fourth switch Q4; wherein the first, second, third, and fourth pulse width modulation signals all have a first cycle as their signal period, and in the first cycle, the duty cycle of the fourth switch Q4 is less than the difference between 1 and the duty cycle of the second switch Q2.

[0077] Alternatively, the first control command includes: a fifth pulse width modulation signal received by the control terminal of the first switch Q1, a sixth pulse width modulation signal received by the control terminal of the second switch Q2, a seventh pulse width modulation signal received by the control terminal of the third switch Q3, and an eighth pulse width modulation signal received by the control terminal of the fourth switch Q4, wherein the fifth, sixth, seventh, and eighth pulse width modulation signals have a second period as their signal period, and in the second period, the duty cycle of the fourth switch Q4 is greater than the difference between 1 and the duty cycle of the second switch Q2.

[0078] In other words, the second battery pack has determined the on / off state of each switch. At this point, the control signals of each switch control terminal can be directly sent to the control unit 101 as the first control command. The control unit 101 can directly control the on / off state of each switch in the voltage conversion unit 102 according to the control signals of each switch control terminal in the first control command.

[0079] Specifically, when the control unit 101 receives a first control command, the first control command includes: a first pulse width modulation signal received by the control terminal of the first switch Q1, a second pulse width modulation signal received by the control terminal of the second switch Q2, a third pulse width modulation signal received by the control terminal of the third switch Q3, and a fourth pulse width modulation signal received by the control terminal of the fourth switch Q4; wherein the first, second, third, and fourth pulse width modulation signals all have a first cycle as their signal period, and in the first cycle, the duty cycle of the fourth switch Q4 is less than the difference between 1 and the duty cycle of the second switch Q2. At this time, the circuit of the voltage conversion unit 102 described above can realize step-down charging of the first battery pack from the second battery pack. For example... Figure 3As shown, high level indicates that the switch is on, low level indicates that the switch is off, and the duty cycle of the fourth switch Q4 is less than the difference between 1 and the duty cycle of the second switch Q2. In order to avoid the problem of short circuit caused by the simultaneous conduction of the first switch Q1 and the second switch Q2, the second switch Q2 is in an off state when the first switch Q1 is on, and the first switch Q1 is in an off state when the second switch Q2 is on. Since there may be a situation that the first switch Q1 is on before the second switch Q2 is off, a dead zone is set, in which the first switch Q1 and the second switch Q2 are both in an off state. That is, the first switch Q1 is turned on after a period of time after the second switch Q2 is turned off, which can avoid the problem that the first switch Q1 is turned on before the second switch Q2 is turned off. Similarly, in order to avoid the problem of short circuit caused by the simultaneous conduction of the third switch Q3 and the fourth switch Q4, the fourth switch Q4 is in an off state when the third switch Q3 is on, and the third switch Q3 is in an off state when the fourth switch Q4 is on. A dead zone is also set, in which the third switch Q3 and the fourth switch Q4 are both in an off state, so as to avoid the problem that the third switch Q3 is turned on before the fourth switch Q4 is turned off.

[0080] It should be noted that the time of the dead zone can be set according to actual needs, and the present application does not limit this.

[0081] Alternatively, when the control unit 101 receives a first control instruction, wherein the first control instruction includes: a fifth pulse width modulation signal received by the control end of the first switch Q1, a sixth pulse width modulation signal received by the control end of the second switch Q2, a seventh pulse width modulation signal received by the control end of the third switch Q3, and an eighth pulse width modulation signal received by the control end of the fourth switch Q4, wherein the fifth pulse width modulation signal, the sixth pulse width modulation signal, the seventh pulse width modulation signal and the eighth pulse width modulation signal have a second period as a signal period, and in the second period, the duty cycle of the fourth switch Q4 is greater than the difference between 1 and the duty cycle of the second switch Q2. At this time, the circuit of the voltage conversion unit 102 described above can realize the boost charging of the first battery pack by the second battery pack. As Figure 4As shown, in the second period, the high level indicates that the switch is turned on, and the low level indicates that the switch is turned off. The duty cycle of the fourth switch Q4 is greater than the difference between the duty cycle of the second switch Q2 and 1. In order to avoid the problem of short circuit caused by the simultaneous conduction of the first switch Q1 and the second switch Q2, the second switch Q2 is in an off state when the first switch Q1 is turned on, and the first switch Q1 is in an off state when the second switch Q2 is turned on. Since there may be a situation that the second switch Q2 is not turned off before the first switch Q1 is turned on, a dead zone is set, in which the first switch Q1 and the second switch Q2 are both in an off state. That is, the first switch Q1 is turned on after the second switch Q2 is turned off for a period of time, which can avoid the problem that the second switch Q2 is turned on before the first switch Q1 is turned off. Similarly, in order to avoid the problem of short circuit caused by the simultaneous conduction of the third switch Q3 and the fourth switch Q4, the fourth switch Q4 is in an off state when the third switch Q3 is turned on, and the third switch Q3 is in an off state when the fourth switch Q4 is turned on. A dead zone is set, in which the third switch Q3 and the fourth switch Q4 are both in an off state, so as to avoid the problem that the third switch Q3 is turned on before the first switch Q1 is turned off.

[0082] Specifically, since the voltage provided by the second battery pack may be higher or lower than the charging voltage required by the first battery pack, the voltage provided by the second battery pack can be converted into the charging voltage required by the first battery pack through the voltage conversion unit 102 for charging the first battery pack. When the voltage provided by the second battery pack is higher than the charging voltage required by the first battery pack, the voltage conversion unit 102 needs to perform corresponding voltage reduction processing on the voltage provided by the second battery pack to convert it into the charging voltage required by the first battery pack. For example, the second battery pack sends a first control instruction to the control unit 101, and after receiving the first control instruction, the control unit 101 can control the first switch Q1 in the voltage conversion unit 102 to work according to the received first pulse width modulation signal, the second switch Q2 to work according to the received second pulse width modulation signal, the third switch Q3 to work according to the received third pulse width modulation signal, and the fourth switch Q4 to work according to the received fourth pulse width modulation signal, so as to reduce the voltage provided by the second battery pack to the charging voltage required by the first battery pack. The voltage reduction ratio can be adjusted by adjusting the duty cycle of the fourth switch Q4 and the duty cycle of the second switch Q2.

[0083] When the voltage provided by the second battery pack is lower than the charging voltage required by the first battery pack, the voltage conversion unit 102 needs to perform corresponding voltage boosting processing on the voltage provided by the second battery pack to convert it into the charging voltage required by the first battery pack. For example, the second battery pack sends a first control instruction to the control unit 101, and after receiving the first control instruction, the control unit 101 can control the first switch Q1 in the voltage conversion unit 102 to work according to the received fifth pulse width modulation signal, the second switch Q2 to work according to the received sixth pulse width modulation signal, the third switch Q3 to work according to the received seventh pulse width modulation signal, and the fourth switch Q4 to work according to the received eighth pulse width modulation signal, so as to raise the voltage provided by the first battery pack to the charging voltage required by the second battery pack. The voltage boosting ratio can be adjusted by adjusting the duty cycle of the second switch Q2 and the duty cycle of the fourth switch Q4.

[0084] In a possible implementation, the adjustment of the step-up / down ratio can be determined by the following formula:

[0085]

[0086] wherein V o is the output voltage of the voltage conversion unit, i.e., the charging voltage required by the first battery pack; V i is the input voltage, i.e., the voltage provided by the second battery pack; Dbu1 is the duty cycle of the fourth switch Q4, and Dbo1 is the duty cycle of the second switch Q2. When the voltage provided by the second battery pack is higher than the charging voltage required by the first battery pack, the voltage conversion unit 102 needs to perform corresponding voltage reduction on the voltage provided by the second battery pack to convert it into the charging voltage required by the first battery pack. At this time, the voltage conversion unit 102 can adjust the duty cycle Dbu1 of the fourth switch Q4 and the duty cycle Dbo1 of the second switch Q2 so that Dbu1 < 1-Dbo1, so that the ratio of Dbu1 to 1-Dbo1 will be less than 1, and the voltage reduction function can be realized. When the voltage provided by the second battery pack is lower than the charging voltage required by the first battery pack, the voltage conversion unit 102 needs to perform corresponding voltage boosting on the voltage provided by the second battery pack to convert it into the charging voltage required by the second battery pack. At this time, the voltage conversion unit 102 can adjust the duty cycle Dbu1 of the fourth switch Q4 and the duty cycle Dbo1 of the second switch Q2 so that Dbu1 > 1-Dbo1, so that the ratio of Dbu1 to 1-Dbo1 will be greater than 1, and the voltage boosting function can be realized.

[0087] It should be noted that the first control instruction can also be charging related information used by the second battery pack to charge other battery packs, and required charging information of the first battery pack, so that the control unit 101 can determine the on-off of each switch according to the first control instruction, and further control the on-off of each switch. The present application does not limit this.

[0088] As a possible implementation manner, when the first battery pack is in a charging state, if the charging capacity of the first battery pack is higher than the second preset threshold, the first battery pack can charge the second battery pack through the charging device at this time. The first battery pack generates a second control instruction and sends the second control instruction to the control unit 101 of the charging device 100. The control unit 101 receives the second control instruction. The second control instruction includes: a ninth pulse width modulation signal received by the control end of the first switch Q1, a tenth pulse width modulation signal received by the control end of the second switch Q2, an eleventh pulse width modulation signal received by the control end of the third switch Q3, and a twelfth pulse width modulation signal received by the control end of the fourth switch Q4. The ninth pulse width modulation signal, the tenth pulse width modulation signal, the eleventh pulse width modulation signal, and the twelfth pulse width modulation signal all have a third period as a signal period, and in the third period, the duty cycle of the first switch Q1 is less than the difference between the duty cycle of the third switch Q3 and 1.

[0089] Alternatively, the second control instruction includes: a thirteenth pulse width modulation signal received by the control end of the first switch Q1, a fourteenth pulse width modulation signal received by the control end of the second switch Q2, a fifteenth pulse width modulation signal received by the control end of the third switch Q3, and a sixteenth pulse width modulation signal received by the control end of the fourth switch Q4. The thirteenth pulse width modulation signal, the fourteenth pulse width modulation signal, the fifteenth pulse width modulation signal, and the sixteenth pulse width modulation signal all have a fourth period as a signal period, and in the fourth period, the duty cycle of the first switch Q1 is greater than the difference between the duty cycle of the third switch Q3 and 1.

[0090] That is, the first battery pack has determined the on-off state of each switch, at this time, the control signals of the control ends of each switch can be directly sent to the control unit 101 as the second control instruction. The control unit 101 can directly control the on-off of each switch in the voltage conversion unit 102 according to the control signals of the control ends of each switch in the second control instruction.

[0091] Specifically, when the control unit 101 receives the second control command, which includes: the ninth pulse width modulation signal received by the control terminal of the first switch Q1, the tenth pulse width modulation signal received by the control terminal of the second switch Q2, the eleventh pulse width modulation signal received by the control terminal of the third switch Q3, and the twelfth pulse width modulation signal received by the control terminal of the fourth switch Q4; wherein the ninth, tenth, eleventh, and twelfth pulse width modulation signals all have a third cycle as their signal period, and in the third cycle, the duty cycle of the first switch Q1 is less than the difference between the duty cycle of the third switch Q3 and 1. The control unit 101 controls the first switch in the voltage conversion unit 102 to operate according to the received ninth pulse width modulation signal, the second switch Q2 to operate according to the received tenth pulse width modulation signal, the third switch Q3 to operate according to the received eleventh pulse width modulation signal, and the control terminal of the fourth switch Q4 to operate according to the received twelfth pulse width modulation signal. At this time, the circuit of the voltage conversion unit 102 can realize the step-down charging of the first battery pack to the second battery pack. Figure 5 As shown, in the third cycle, a high level indicates the switch is on, and a low level indicates the switch is off. The duty cycle of the first switch Q1 is less than the difference between the duty cycle of the third switch Q3 and 1. Furthermore, as described above... Figure 3 Similarly, to avoid a short circuit caused by the simultaneous conduction of the first switch Q1 and the second switch Q2, or the third switch Q3 and the fourth switch Q4, the circuit is controlled such that when the first switch Q1 is on, the second switch Q2 is off, and when the second switch Q2 is on, the first switch Q1 is off. Similarly, the circuit is controlled such that when the third switch Q3 is on, the fourth switch Q4 is off, and when the fourth switch Q4 is on, the third switch Q3 is off. A dead zone is also set to further prevent a short circuit caused by the simultaneous conduction of the first switch Q1 and the second switch Q2, or the third switch Q3 and the fourth switch Q4. See the above for details. Figure 3 , Figure 4 This will not be elaborated upon here.

[0092] Or, when the control unit 101 receives the second control instruction, wherein the second control instruction comprises: the thirteenth pulse width modulation signal received by the control end of the first switch Q1, the fourteenth pulse width modulation signal received by the control end of the second switch Q2, the fifteenth pulse width modulation signal received by the control end of the third switch Q3, and the sixteenth pulse width modulation signal received by the control end of the fourth switch Q4; wherein the thirteenth pulse width modulation signal, the fourteenth pulse width modulation signal, the fifteenth pulse width modulation signal and the sixteenth pulse width modulation signal all have the fourth period as the signal period, and in the fourth period, the duty cycle of the first switch Q1 is greater than the difference between the duty cycle of the third switch Q3. The control unit 101 controls the first switch Q1 in the voltage conversion unit 102 to work according to the received thirteenth switch pulse width modulation signal, the second switch Q2 to work according to the received fourteenth pulse width modulation signal, the third switch Q3 to work according to the received fifteenth pulse width modulation signal, and the fourth switch Q4 to work according to the received sixteenth pulse width modulation signal. At this time, the circuit of the voltage conversion voltage 102 described above can realize the boost charging of the first battery pack to the second battery pack. As shown in Figure 6 , in the third period, high level indicates that the switch is turned on, low level indicates that the switch is turned off, and the duty cycle of the first switch Q1 is greater than the difference between the duty cycle of the third switch Q3. And, as described above Figure 3 , for the same reason as 4, in order to avoid the problem of circuit short circuit caused by the simultaneous conduction of the first switch Q1 and the second switch Q2, or the simultaneous conduction of the third switch Q3 and the fourth switch Q4, the second switch Q2 is in the off state when the first switch Q1 is turned on, the first switch Q1 is in the off state when the second switch Q2 is turned on, the fourth switch Q4 is in the off state when the third switch Q3 is turned on, and the third switch Q3 is in the off state when the fourth switch Q4 is turned on. And set the dead zone to further avoid the problem of circuit short circuit caused by the simultaneous conduction of the first switch Q1 and the second switch Q2, or the simultaneous conduction of the third switch Q3 and the fourth switch Q4. For details, please refer to the above Figure 3 、 Figure 4 , which will not be repeated here.

[0093] Specifically, since the voltage provided by the first battery pack can be higher or lower than the charging voltage required by the second battery pack, the voltage provided by the first battery pack can be converted into the charging voltage required by the second battery pack by the voltage conversion unit 102 through corresponding voltage boosting or voltage reducing processing, so as to charge the second battery pack. When the voltage provided by the first battery pack is higher than the charging voltage required by the second battery pack, the voltage provided by the first battery pack needs to be reduced by the voltage conversion unit 102 to convert into the charging voltage required by the second battery pack. For example, the first battery pack sends a second control instruction to the control unit 101, and after the control unit 101 receives the second control instruction, the control unit 101 can control the first switch Q1 in the voltage conversion unit 102 to work according to the received ninth pulse width modulation signal, the second switch Q2 to work according to the received tenth pulse width modulation signal, the third switch Q3 to work according to the received eleventh pulse width modulation signal, and the control end of the fourth switch Q4 to work according to the received twelfth pulse width modulation signal, so as to reduce the voltage provided by the first battery pack to the charging voltage required by the second battery pack. Wherein, the duty cycle of the first switch Q1 and the duty cycle of the third switch Q3 can be adjusted to adjust the voltage reduction ratio.

[0094] When the voltage provided by the first battery pack is lower than the charging voltage required by the second battery pack, the voltage provided by the first battery pack needs to be boosted by the voltage conversion unit 102 to convert into the charging voltage required by the second battery pack. For example, the first battery pack sends a second control instruction to the control unit 101, and after the control unit 101 receives the second control instruction, the control unit 101 can control the first switch Q1 in the voltage conversion unit 102 to be turned on, the second switch Q2 to be turned off, the third switch Q3 to work in pulse width modulation, and the fourth switch Q4 to be turned on, so as to increase the voltage provided by the first battery pack to the charging voltage required by the second battery pack. Wherein, the duty cycle of the first switch Q1 and the duty cycle of the third switch Q3 can be adjusted to adjust the voltage boosting ratio. At this time, the adjustment of the voltage boosting ratio can be determined by the above formula, which is as follows:

[0095]

[0096] Wherein, V o is the output voltage of the voltage conversion unit, i.e. the charging voltage required by the second battery pack; V iDbu2 is the duty cycle of the first switch Q1, and Dbo2 is the duty cycle of the third switch Q3. When the voltage provided by the first battery pack is higher than the charging voltage required by the second battery pack, the voltage conversion unit 102 needs to reduce the voltage provided by the first battery pack accordingly to convert it into the charging voltage required by the second battery pack. At this time, the voltage conversion unit 102 can adjust the duty cycle Dbu2 of the first switch Q1 and the duty cycle Dbo2 of the third switch Q3 so that Dbu2 < 1-Dbo2, and then the ratio of Dbu2 to 1-Dbo2 will be less than 1, which can realize the function of voltage reduction. When the voltage provided by the first battery pack is lower than the charging voltage required by the second battery pack, the voltage conversion unit 102 needs to increase the voltage provided by the first battery pack accordingly to convert it into the charging voltage required by the second battery pack. At this time, the voltage conversion unit 102 can adjust the duty cycle Dbu2 of the first switch Q1 and the duty cycle Dbo2 of the third switch Q3 so that Dbu2 > 1-Dbo2, and then the ratio of Dbu2 to 1-Dbo2 will be greater than 1, which can realize the function of voltage increase.

[0097] Further, as shown in FIG. 2, the voltage conversion unit 102 further includes a first resistor R1 and a second resistor R2. Figure 7

[0098] At this time, the connection of the second end of the second switch Q2 to the other end of the first battery pack includes that the second end of the second switch Q2 is connected to the other end of the first battery pack through the first resistor R1, and one end of the first resistor R1 connected to the other end of the first battery pack is grounded.

[0099] The connection of the second end of the third switch Q3 to one end of the second battery pack includes that the second end of the third switch Q3 is connected to one end of the second battery pack through the second resistor R2, and one end of the second resistor R2 connected to one end of the second battery pack is grounded.

[0100] In the embodiments of the present application, if the first switch Q1 and the second switch Q2 are turned on at the same time, the positive and negative electrodes of the first battery pack will be connected, which will be short-circuited, and at this time, a safety accident will be caused. Similarly, if the third switch Q3 and the fourth switch Q4 are turned on at the same time, the second battery pack will also be short-circuited. Therefore, the first resistor R1 and the second resistor R2 are added in the voltage conversion unit 102 to protect the battery pack from being short-circuited. At this time, one end of the first resistor R1 is connected to one end of the second switch Q2, the other end of the first resistor R1 is grounded and connected to one end of the first battery pack; one end of the second resistor R2 is connected to one end of the third switch Q3, and the other end of the second resistor R2 is grounded and connected to one end of the second battery pack, which can protect the first battery pack and the second battery pack from being short-circuited, and improve the safety performance.

[0101] ​In a possible embodiment, the first switch Q1, the second switch Q2, the third switch Q3 and the fourth switch Q4 can be MOS tubes.

[0102] Through the above process, when the second battery pack charges the first battery pack, if the voltage provided by the second battery pack does not match the charging voltage of the first battery pack, the voltage provided by the second battery pack can be adjusted to the charging voltage of the first battery pack by the voltage conversion unit 102 of the charging device 100; when the first battery pack charges the second battery pack, if the voltage provided by the first battery pack does not match the charging voltage of the second battery pack, the voltage provided by the first battery pack can also be adjusted to the charging voltage of the second battery pack by the voltage conversion unit 102 of the charging device 100.

[0103] The application further provides an electric vehicle, Figure 8 A structural schematic diagram of an electric vehicle provided by the application is shown in the figure. Figure 8 As shown in the figure, the electric vehicle is provided with a first battery pack 801 for providing power, and the electric vehicle can also be provided with a second battery pack 803 and a charging device 802. The charging device 802 in the electric vehicle is the charging device described in the above embodiments.

[0104] In a possible implementation, the second battery pack 803 is connected with the first battery pack 801, and is configured to acquire the charging voltage of the first battery pack 801 when the electric quantity of the first battery pack 801 is lower than a first preset threshold, and determine a first control instruction according to the charging voltage of the first battery pack 801 and the voltage provided by the second battery pack 803, and send the first control instruction to the control unit of the charging device 802.

[0105] Further, the second battery pack 803 is specifically configured to acquire the charging voltage of the first battery pack 801 when the electric quantity of the first battery pack 801 is lower than the first preset threshold, and determine the first control instruction as a first pulse width modulation signal received by the control end of the first switch Q1, a second pulse width modulation signal received by the control end of the second switch Q2, a third pulse width modulation signal received by the control end of the third switch Q3 and a fourth pulse width modulation signal received by the control end of the fourth switch Q4 when the charging voltage of the first battery pack 801 is less than the voltage provided by the second battery pack 803. The first pulse width modulation signal, the second pulse width modulation signal, the third pulse width modulation signal and the fourth pulse width modulation signal all have the first period as the signal period, and the duty ratio of the fourth switch Q4 is less than the difference between the duty ratio of the second switch Q2 and 1 in the first period.

[0106] When the charging voltage of the first battery pack 801 is greater than the voltage provided by the second battery pack 803, the fifth pulse width modulation signal received by the control end of the first switch Q1, the sixth pulse width modulation signal received by the control end of the second switch Q2, the seventh pulse width modulation signal received by the control end of the third switch Q3, and the eighth pulse width modulation signal received by the control end of the fourth switch Q4 are determined as the first control instruction. The fifth pulse width modulation signal, the sixth pulse width modulation signal, the seventh pulse width modulation signal, and the eighth pulse width modulation signal have the second period as the signal period, and in the second period, the duty cycle of the fourth switch Q4 is greater than the difference between the duty cycle of the second switch Q2.

[0107] Specifically, when the power of the first battery pack 801 is lower than the first preset threshold, it indicates that the power of the first battery pack 801 is low, and at this time, the second battery pack 803 can charge the first battery pack 801 to maintain its normal work. Since the voltage provided by the second battery pack 803 can be higher or lower than the charging voltage of the first battery pack 801, the voltage provided by the second battery pack 803 needs to be stepped down or stepped up to meet the charging voltage of the first battery pack 801. Therefore, before charging, the second battery pack 803 needs to first obtain the charging voltage of the first battery pack 801, and determine whether the charging needs to be stepped down or stepped up according to the charging voltage of the first battery pack 801 and the voltage provided by the second battery pack 803, and determine the first control instruction. When the charging voltage of the first battery pack 801 is less than the voltage provided by the second battery pack 803, the second battery pack 803 determines that the charging needs to be stepped down, and at this time, the first pulse width modulation signal received by the control end of the first switch Q1, the second pulse width modulation signal received by the control end of the second switch Q2, the third pulse width modulation signal received by the control end of the third switch Q3, and the fourth pulse width modulation signal received by the control end of the fourth switch Q4 are determined as the first control instruction. When the charging voltage of the first battery pack 801 is greater than the voltage provided by the second battery pack 803, the second battery pack 803 determines that the charging needs to be stepped up, and at this time, the fifth pulse width modulation signal received by the control end of the first switch Q1, the sixth pulse width modulation signal received by the control end of the second switch Q2, the seventh pulse width modulation signal received by the control end of the third switch Q3, and the eighth pulse width modulation signal received by the control end of the fourth switch Q4 are determined as the first control instruction. After the first control instruction is determined, the first control instruction is sent to the control unit of the charging device 802, and the control unit of the charging device 802 controls the voltage conversion unit to charge the first battery pack 801.

[0108] It should be noted that the first preset threshold is pre-set.

[0109] In the embodiments of the present application, the first battery pack 801 and the second battery pack 803 can be connected through a CAN bus to obtain information. For example, the first battery pack 801 and the second battery pack 803 are both connected to the CAN bus, the first battery pack 801 can send the charging voltage to the CAN bus, and the second battery pack 803 can obtain the charging voltage of the first battery pack 801 through the CAN bus, so as to realize the information interaction between the first battery pack 801 and the second battery pack 803 through the CAN bus communication.

[0110] As a possible implementation, Figure 9 Another structural schematic diagram of an electric vehicle is provided in the embodiments of the present application. As shown in Figure 9 When the first battery pack 801 is insufficient, the second battery pack 803 needs to charge the first battery pack 801 through the charging device 802, so that the first battery pack 801 can supply power to the motor of the electric vehicle.

[0111] The first battery pack 801 is further configured to send a power compensation request message to the second battery pack 803 when the battery power of the first battery pack 801 is lower than the first preset threshold. The power compensation request message carries the charging voltage of the first battery pack 801.

[0112] The second battery pack 803 is specifically configured to receive the power compensation request message and obtain the charging voltage of the first battery pack 801 from the power compensation request message when the power of the second battery pack 803 is greater than the third preset threshold.

[0113] Specifically, when the battery power of the first battery pack 801 is lower than the first preset threshold, the power compensation request message is sent to the second battery pack 803. The power compensation request message carries the charging voltage of the first battery pack 801.

[0114] In the embodiment of the present application, when the battery power of the first battery pack 801 is less than the first preset threshold, it indicates that the battery power of the first battery pack 801 is too low at this time, and the second battery pack 803 needs to supply power to it to maintain the normal work of the first battery pack 801. Therefore, when the battery power of the first battery pack 801 is less than the first preset threshold, the first battery pack 801 can send a power supply request message to the second battery pack 803, and the power supply request message carries the charging voltage of the first battery pack 801. After the second battery pack 803 receives the power supply request message, it detects the battery power of itself, and if the battery power of itself is greater than the third preset threshold, it indicates that the battery power stored in the second battery pack 803 is high, and the second battery pack 803 can supply power to the first battery pack 801. At this time, the second battery pack 803 can obtain the charging voltage of the first battery pack 801 by analyzing the power supply request message, and then can determine the first control instruction according to the charging voltage of the first battery pack 801 and the voltage provided by the second battery pack 803. When the charging voltage of the first battery pack 801 is less than the voltage provided by the second battery pack 803, the second battery pack 803 determines that it needs to be charged by step-down, at this time, the first pulse width modulation signal received by the control end of the first switch Q1, the second pulse width modulation signal received by the control end of the second switch Q2, the third pulse width modulation signal received by the control end of the third switch Q3, and the fourth pulse width modulation signal received by the control end of the fourth switch Q4 are determined as the first control instruction; when the charging voltage of the first battery pack 801 is greater than the voltage provided by the second battery pack 803, the second battery pack 803 determines that it needs to be charged by step-up, at this time, the fifth pulse width modulation signal received by the control end of the first switch Q1, the sixth pulse width modulation signal received by the control end of the second switch Q2, the seventh pulse width modulation signal received by the control end of the third switch Q3, and the eighth pulse width modulation signal received by the control end of the fourth switch Q4 are determined as the first control instruction. After the first control instruction is determined, the first control instruction is sent to the control unit of the charging device 802, and the voltage conversion unit of the charging device 802 is controlled by the control unit to charge the first battery pack 801. The determined first control instruction is sent to the charging device 802, so that the charging device 802 adjusts the voltage provided by the second battery pack 803 according to the first control instruction, and transmits the adjusted voltage to the first battery pack 801 to supply power to the first battery pack 801.

[0115] It should be noted that the third preset threshold is pre-set.

[0116] As a possible implementation manner, Figure 10 is another structural schematic diagram of an electric vehicle provided by the embodiment of the present application. As shown in Figure 10As shown, one end of the first battery pack 801 is connected with a charger device, and the charger device can charge the first battery pack 801. The first battery pack 801 can charge the second battery pack 803 through the charging device 802.

[0117] In the charging mode, the first battery pack 801 is further configured to acquire a charging voltage of the second battery pack 803 when the charging capacity of the first battery pack 801 is higher than the second preset threshold, and determine a second control instruction according to the charging voltage of the second battery pack 803 and the voltage provided by the first battery pack 801, and send the second control instruction to the control unit of the charging device 802.

[0118] Further, the first battery pack 801 is specifically configured to acquire the charging voltage of the second battery pack 803 when the charging capacity of the first battery pack 801 is higher than the second preset threshold, and determine the second control instruction as a ninth pulse width modulation signal received by the control end of the first switch Q1, a tenth pulse width modulation signal received by the control end of the second switch Q2, an eleventh pulse width modulation signal received by the control end of the third switch Q3, and a twelfth pulse width modulation signal received by the control end of the fourth switch Q4 when the voltage provided by the first battery pack 801 is greater than the charging voltage of the second battery pack 803. The ninth pulse width modulation signal, the tenth pulse width modulation signal, the eleventh pulse width modulation signal, and the twelfth pulse width modulation signal all have a third period as a signal period, and in the third period, the duty ratio of the first switch Q1 is less than the difference between the duty ratio of the third switch Q3 and 1.

[0119] In the charging mode, the first battery pack 801 is further configured to acquire a charging voltage of the second battery pack 803 when the charging capacity of the first battery pack 801 is higher than the second preset threshold, and determine a second control instruction according to the charging voltage of the second battery pack 803 and the voltage provided by the first battery pack 801, and send the second control instruction to the control unit of the charging device 802.

[0120] Specifically, since the first battery pack 801 provides power for the electric vehicle, and the second battery pack 803 is only used to store the excess power of the first battery pack 801, the second battery pack 803 can only be charged when the first battery pack 801 is externally charged. That is, the first battery pack 801 provides the charging function to the second battery pack 803 only when the first battery pack 801 is in the charging mode. When the first battery pack 801 charges the second battery pack 803, since the voltage provided by the first battery pack 801 can be higher or lower than the charging voltage of the second battery pack 803, the voltage provided by the first battery pack 801 needs to be stepped down or stepped up to meet the charging voltage of the second battery pack 803. Therefore, before charging, the first battery pack 801 needs to obtain the charging voltage of the second battery pack 803, and determine whether the voltage needs to be stepped down or stepped up according to the charging voltage of the second battery pack 803 and the voltage provided by the first battery pack 801, and determine the second control instruction. When the voltage provided by the first battery pack 801 is greater than the charging voltage of the second battery pack 803, the first battery pack 801 determines that the voltage needs to be stepped down, and the ninth pulse width modulation signal received by the control end of the first switch Q1, the tenth pulse width modulation signal received by the control end of the second switch Q2, the eleventh pulse width modulation signal received by the control end of the third switch Q3, and the twelfth pulse width modulation signal received by the control end of the fourth switch Q4 are determined as the second control instruction. When the voltage provided by the first battery pack 801 is less than the charging voltage of the second battery pack 803, the first battery pack 801 determines that the voltage needs to be stepped up, and the thirteenth pulse width modulation signal received by the control end of the first switch Q1, the fourteenth pulse width modulation signal received by the control end of the second switch Q2, the fifteenth pulse width modulation signal received by the control end of the third switch Q3, and the sixteenth pulse width modulation signal received by the control end of the fourth switch Q4 are determined as the second control instruction. After the second control instruction is determined, the second control instruction is sent to the control unit of the charging device 802, and the control unit of the charging device 802 controls the voltage conversion unit of the charging device 802 to charge the second battery pack 803.

[0121] It should be noted that the second preset threshold is pre-set.

[0122] As a possible implementation manner, the first battery pack 801 is further configured to send a charging request message to the second battery pack 803 when the first battery pack 801 is in the mode of being charged by the external power supply and the battery power of the first battery pack 801 is greater than the second preset threshold.

[0123] The second battery pack 803 is further configured to receive the charging request message, and return an acceptance charging response message to the first battery pack 801 when the battery power of the second battery pack 803 is less than the fourth preset threshold. The acceptance charging response message carries the charging voltage of the second battery pack 803.

[0124] The first battery pack 801 is configured to receive the accept charging response message and obtain the charging voltage of the second battery pack 803 according to the accept charging response message.

[0125] Specifically, since the first battery pack 801 provides power for the electric vehicle, and the second battery pack 803 is only used to store the excess power of the first battery pack 801, the second battery pack 803 can only be charged when the first battery pack 801 is externally charged. That is, the first battery pack 801 provides the charging function to the second battery pack 803 only when the first battery pack 801 is in the charging mode. When the first battery pack 801 is in the charging mode and the battery power of the first battery pack 801 reaches the second preset threshold, it indicates that the first battery pack 801 has been charged to a higher power, and at this time the second battery pack 803 can be charged. Therefore, when the first battery pack 801 is in the charging mode and the battery power of the first battery pack 801 is greater than the second preset threshold, the first battery pack 801 can send a charging request message to the second battery pack 803 to inquire whether the second battery pack 803 needs to be charged. After receiving the charging request message, the second battery pack 803 detects the battery power of the second battery pack 803. If the battery power of the second battery pack 803 is less than the fourth preset threshold, it indicates that the battery power is too low and needs to be charged. The second battery pack 803 returns an accept charging response message to the first battery pack 801 to inform the first battery pack 801 that the second battery pack 803 needs to be charged. Moreover, the accept charging response message carries the charging voltage of the second battery pack 803. When the first battery pack 801 receives the accept charging response message, it can determine that the second battery pack 803 needs to be charged. By analyzing the accept charging response message, the first battery pack 801 can obtain the charging voltage of the second battery pack 803, and then determine whether the second battery pack 803 needs to be step-down charged or step-up charged according to the charging voltage of the second battery pack 803 and the voltage provided by the first battery pack 801, and determine the second control instruction. When the voltage provided by the first battery pack 801 is greater than the charging voltage of the second battery pack 803, the first battery pack 801 determines that the second battery pack 803 needs to be step-down charged, and at this time the first battery pack 801 determines the ninth pulse width modulation signal received by the control end of the first switch Q1, the tenth pulse width modulation signal received by the control end of the second switch Q2, the eleventh pulse width modulation signal received by the control end of the third switch Q3, and the twelfth pulse width modulation signal received by the control end of the fourth switch Q4 as the second control instruction. When the voltage provided by the first battery pack 801 is less than the charging voltage of the second battery pack 803, the first battery pack 801 determines that the second battery pack 803 needs to be step-up charged, and determines the thirteenth pulse width modulation signal received by the control end of the first switch Q1, the fourteenth pulse width modulation signal received by the control end of the second switch Q2, the fifteenth pulse width modulation signal received by the control end of the third switch Q3, and the sixteenth pulse width modulation signal received by the control end of the fourth switch Q4 as the second control instruction. After the second control instruction is determined, the second control instruction is sent to the charging device 802, so that the charging device 802 adjusts the voltage provided by the first battery pack 801 according to the second control instruction, and transmits the adjusted voltage to the second battery pack 803 to charge the second battery pack 803.

[0126] It should be noted that the fourth threshold is pre-set.

[0127] The above describes the process of charging the second battery pack by the first battery pack in the first battery pack charging mode. Therefore, in the embodiment of the present application, the energy conversion from the first battery pack to the second battery pack can be realized by the charging device, so that the second battery pack can store the excess power of the first battery pack to meet the high endurance requirement of the electric vehicle.

[0128] From the above process of charging the first battery pack by the second battery pack and the process of charging the second battery pack by the first battery pack, it can be known that in the embodiment of the present application, the bidirectional energy conversion between the first battery pack and the second battery pack can be realized by the charging device to realize the intelligent power distribution. Moreover, the charging device proposed in the present application is suitable for the bidirectional energy conversion between the first battery pack and the second battery pack with different power, and can improve the versatility of the module. For example, in the charging mode, the voltage conversion unit of the charging device can convert the voltage provided by the first battery pack into the charging voltage required by different second battery packs. Of course, the voltage conversion unit of the charging device can convert the voltage provided by different second battery packs into the charging voltage required by different first battery packs to meet the different endurance requirements of the electric vehicle. Therefore, the charging device can improve the versatility of the battery module.

[0129] Those skilled in the art can clearly understand that the technology in the embodiment of the present application can be realized by means of software and necessary general hardware platform. Based on such understanding, the technical solutions in the embodiment of the present application can be embodied in the form of software product, which can be stored in a storage medium such as ROM / RAM, magnetic disc, optical disc, etc., and includes a plurality of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute the method described in the various embodiments or some parts of the embodiments of the present application.

[0130] The same and similar parts among various embodiments in the present specification can be referred to each other. Especially, for the device embodiments and the terminal embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the description in the method embodiments.

Claims

1. A charging device applied to an electric vehicle, wherein a first battery pack for providing power is provided on the electric vehicle, characterized in that, The electric vehicle is further provided with a second battery pack, and the charging device is connected with the first battery pack and the second battery pack; the charging device comprises a control unit and a voltage conversion unit connected with the control unit; The control unit is configured to control the voltage conversion unit to convert the voltage provided by the second battery pack into the charging voltage of the first battery pack, so that in the driving state of the electric vehicle, when the electric quantity of the first battery pack is lower than a first preset threshold, the second battery pack charges the first battery pack through the charging device; The control unit is further configured to control the voltage conversion unit to convert the voltage provided by the first battery pack into the charging voltage of the second battery pack, so that in the charging state of the electric vehicle, when the charging electric quantity of the first battery pack is higher than a second preset threshold, the first battery pack charges the second battery pack through the charging device, wherein the second preset threshold is greater than the first preset threshold.

2. The device of claim 1, wherein The control unit is specifically configured to, when receiving a first control instruction sent by the second battery pack, control the voltage conversion unit to convert the voltage provided by the second battery pack into the charging voltage of the first battery pack according to the first control instruction; or When receiving a second control instruction sent by the first battery pack, control the voltage conversion unit to convert the voltage provided by the first battery pack into the charging voltage of the second battery pack according to the second control instruction.

3. The device of claim 2, wherein The voltage conversion unit comprises a first switch, a second switch, a third switch, a fourth switch and an inductor; The control terminals of the first switch, the second switch, the third switch and the fourth switch are connected with the control unit; one end of the first switch is connected with one end of the first battery pack, and the other end of the first switch is connected with the first end of the second switch and the first end of the inductor; the second end of the second switch is connected with the other end of the first battery pack; the first end of the third switch is connected with the second end of the inductor and the first end of the fourth switch, the second end of the third switch is connected with one end of the second battery pack, and the second end of the fourth switch is connected with the other end of the second battery pack. The voltage conversion unit further comprises a first resistor and a second resistor; 4. The apparatus of claim 3, wherein, The second end of the second switch being connected with the other end of the first battery pack comprises: The second end of the second switch is connected with the other end of the first battery pack through the first resistor; One end of the first resistor connected with the other end of the first battery pack is grounded; The second end of the third switch being connected with one end of the second battery pack comprises: The second end of the third switch is connected with one end of the second battery pack through the second resistor; One end of the second resistor connected with one end of the second battery pack is grounded.

5. The device of claim 3 or 4, wherein ​ The first control instruction comprises: a first pulse width modulation signal received by the control end of the first switch, a second pulse width modulation signal received by the control end of the second switch, a third pulse width modulation signal received by the control end of the third switch, and a fourth pulse width modulation signal received by the control end of the fourth switch; wherein the first pulse width modulation signal, the second pulse width modulation signal, the third pulse width modulation signal, and the fourth pulse width modulation signal all have a first period as a signal period, and in the first period, the duty cycle of the fourth switch is less than the difference between 1 and the duty cycle of the second switch; Alternatively, the first control instruction comprises: a fifth pulse width modulation signal received by the control end of the first switch, a sixth pulse width modulation signal received by the control end of the second switch, a seventh pulse width modulation signal received by the control end of the third switch, and an eighth pulse width modulation signal received by the control end of the fourth switch; wherein the fifth pulse width modulation signal, the sixth pulse width modulation signal, the seventh pulse width modulation signal, and the eighth pulse width modulation signal all have a second period as a signal period, and in the second period, the duty cycle of the fourth switch is greater than the difference between 1 and the duty cycle of the second switch.

6. The device of claim 3 or 4, wherein The second control instruction comprises: a ninth pulse width modulation signal received by the control end of the first switch, a tenth pulse width modulation signal received by the control end of the second switch, an eleventh pulse width modulation signal received by the control end of the third switch, and a twelfth pulse width modulation signal received by the control end of the fourth switch; wherein the ninth pulse width modulation signal, the tenth pulse width modulation signal, the eleventh pulse width modulation signal, and the twelfth pulse width modulation signal all have a third period as a signal period, and in the third period, the duty cycle of the first switch is less than the difference between 1 and the duty cycle of the third switch; Alternatively, the second control instruction comprises: a thirteenth pulse width modulation signal received by the control end of the first switch, a fourteenth pulse width modulation signal received by the control end of the second switch, a fifteenth pulse width modulation signal received by the control end of the third switch, and a sixteenth pulse width modulation signal received by the control end of the fourth switch; wherein the thirteenth pulse width modulation signal, the fourteenth pulse width modulation signal, the fifteenth pulse width modulation signal, and the sixteenth pulse width modulation signal all have a fourth period as a signal period, and in the fourth period, the duty cycle of the first switch is greater than the difference between 1 and the duty cycle of the third switch.

7. An electric vehicle having a first battery pack for providing power thereon, characterized by, The electric vehicle can further be provided with a second battery pack and a charging device, and the charging device is the charging device of any one of claims 1-6.

8. The electric vehicle of claim 7, wherein, Further comprising: The second battery pack is connected to the first battery pack, and when the electric quantity of the first battery pack is lower than a first preset threshold, the charging voltage of the first battery pack is obtained, and a first control instruction is determined according to the charging voltage of the first battery pack and the voltage provided by the second battery pack, and the first control instruction is sent to the control unit of the charging device.

9. The electric vehicle of claim 8, wherein The second battery group is specifically configured to, when the electric quantity of the first battery group is lower than a first preset threshold, acquire the charging voltage of the first battery group, and when the charging voltage of the first battery group is lower than the voltage provided by the second battery group, determine, as the first control instruction, a first pulse width modulation signal received by the control end of the first switch, a second pulse width modulation signal received by the control end of the second switch, a third pulse width modulation signal received by the control end of the third switch, and a fourth pulse width modulation signal received by the control end of the fourth switch, wherein the first pulse width modulation signal, the second pulse width modulation signal, the third pulse width modulation signal, and the fourth pulse width modulation signal all have the first period as the signal period, and in the first period, the duty ratio of the fourth switch is less than the difference between the duty ratio of the second switch and 1. When the charging voltage of the first battery group is higher than the voltage provided by the second battery group, determine, as the first control instruction, a fifth pulse width modulation signal received by the control end of the first switch, a sixth pulse width modulation signal received by the control end of the second switch, a seventh pulse width modulation signal received by the control end of the third switch, and an eighth pulse width modulation signal received by the control end of the fourth switch, wherein the fifth pulse width modulation signal, the sixth pulse width modulation signal, the seventh pulse width modulation signal, and the eighth pulse width modulation signal have the second period as the signal period, and in the second period, the duty ratio of the fourth switch is greater than the difference between the duty ratio of the second switch and 1.

10. The electric vehicle of claim 8, wherein The first battery group is further configured to, when the electric quantity of the first battery group is lower than the first preset threshold, send a power supplement request message to the second battery group, and the power supplement request message carries the charging voltage of the first battery group. The second battery group is specifically configured to receive the power supplement request message, and when the electric quantity of the second battery group is greater than a third preset threshold, acquire the charging voltage of the first battery group from the power supplement request message.

11. The electric vehicle of any one of claims 7-10, wherein The first battery group is further configured to, when the charging electric quantity of the first battery group is higher than a second preset threshold, acquire the charging voltage of the second battery group, and determine a second control instruction according to the charging voltage of the second battery group and the voltage provided by the first battery group, and send the second control instruction to the control unit of the charging device.

12. The electric vehicle of claim 11, wherein The first battery pack is specifically configured to acquire the charging voltage of the second battery pack when the charging capacity of the first battery pack is higher than a second preset threshold, and determine the ninth pulse width modulation signal received by the control end of the first switch, the tenth pulse width modulation signal received by the control end of the second switch, the eleventh pulse width modulation signal received by the control end of the third switch, and the twelfth pulse width modulation signal received by the control end of the fourth switch as the second control instruction when the voltage provided by the first battery pack is greater than the charging voltage of the second battery pack, wherein the ninth pulse width modulation signal, the tenth pulse width modulation signal, the eleventh pulse width modulation signal, and the twelfth pulse width modulation signal all have the third period as a signal period, and in the third period, the difference between the duty cycle of the first switch and the duty cycle of the third switch is less than 1. The first battery pack is specifically configured to acquire the charging voltage of the second battery pack when the charging capacity of the first battery pack is higher than a second preset threshold, and determine the ninth pulse width modulation signal received by the control end of the first switch, the tenth pulse width modulation signal received by the control end of the second switch, the eleventh pulse width modulation signal received by the control end of the third switch, and the twelfth pulse width modulation signal received by the control end of the fourth switch as the second control instruction when the voltage provided by the first battery pack is greater than the charging voltage of the second battery pack, wherein the ninth pulse width modulation signal, the tenth pulse width modulation signal, the eleventh pulse width modulation signal, and the twelfth pulse width modulation signal all have the third period as a signal period, and in the third period, the difference between the duty cycle of the first switch and the duty cycle of the third switch is less than 1.

13. The electric vehicle of claim 11, wherein The first battery pack is further configured to send a charging request message to the second battery pack when the first battery pack is in a mode of being charged by an external power supply and the battery capacity of the first battery pack is greater than a second preset threshold. The second battery pack is further configured to receive the charging request message and return an accept charging response message to the first battery pack when the battery capacity of the second battery pack is less than a fourth preset threshold, wherein the accept charging response message carries the charging voltage of the second battery pack. The first battery pack is specifically configured to receive the accept charging response message and acquire the charging voltage of the second battery pack according to the accept charging response message.

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