Charging circuit and charging system

Abstract

The utility model discloses a charging circuit and a charging system, and relates to the technical field of battery charging. The charging circuit comprises a buck-boost unit and a switch unit. The switch unit is connected with the buck-boost unit, is suitable for being connected with the power battery and the power supply device, and is configured to enable the power battery to be directly connected with the power supply device or enable the power battery to be connected with the power supply device through the buck-boost unit; and the buck-boost unit is configured to increase or decrease the output voltage of the power supply device to a charging voltage range required by the power battery. Therefore, an all-working-condition charging mode of boost charging, buck charging and direct charging can be realized, the compatibility of a power supply device is improved, and the cost is low.

Description

TECHNICAL FIELD

[0001] The utility model relates to battery charging technical field especially relates to a charging circuit and charging system. BACKGROUND

[0002] With the advocacy of low carbon emission concept and the continuous development of new energy technology, electric vehicles have been widely popularized, and the problems brought along are that the capacity of electric vehicle power battery will continuously decay with the increase of service life, and when it decays to a certain proportion, it needs to be retired. But these retired power batteries still have great utilization space, so it is necessary to carry out secondary utilization to these retired power batteries.

[0003] In the related art, when the retired power battery is used for secondary utilization, the charging circuit used involves a multi-stage voltage conversion process, the architecture is relatively complicated, more electrical components are involved, and the cost is relatively high. Moreover, the charging circuit can only realize step-up and step-down charging, and has poor compatibility with the power supply device. UTILITY MODEL CONTENT

[0004] The utility model aims at at least in a certain extent solve one of the technical problems in the related art. For this purpose, the purpose of the utility model is to provide a kind of charging circuit and charging system, to realize the full working condition charging mode of step-up charging, step-down charging, direct charging, improve the compatibility of power supply device, and reduce cost.

[0005] In the first aspect, the utility model provides a kind of charging circuit, comprising: step-up and step-down unit and switch unit;The switch unit is connected with the step-up and step-down unit, and is adapted to connect power supply device and power battery, is configured to make the power battery and the power supply device direct connection, or make the power battery connect with the power supply device through the step-up and step-down unit;The step-up and step-down unit is configured to rise or drop the output voltage of the power supply device to the required charging voltage range of the power battery.

[0006] In some examples, the switch unit comprises a first switch assembly and a second switch assembly, a first end of the first switch assembly is adapted to be connected to a positive pole of the power supply device, a second end of the first switch assembly is connected to a first end of the voltage-lifting and voltage-lowering unit and a first end of the second switch assembly respectively, a third end of the first switch assembly is connected to a second end of the voltage-lifting and voltage-lowering unit and a second end of the second switch assembly respectively, a third end of the second switch assembly is adapted to be connected to a positive pole of the power battery, a third end of the voltage-lifting and voltage-lowering unit is adapted to be connected to a negative pole of the power battery and a negative pole of the power supply device; wherein the first end of the first switch assembly is selectively connected or disconnected to the second end and the third end respectively, the first end, the second end and the third end of the second switch assembly are selectively connected or disconnected to each other in pairs, and the first end of the voltage-lifting and voltage-lowering unit is selectively connected or disconnected to the second end and the third end respectively.

[0007] In some examples, the first switch assembly comprises a first switch and a second switch, a first end of the first switch and a first end of the second switch serve as the first end of the first switch assembly, a second end of the second switch serves as the second end of the first switch assembly, and a second end of the second switch serves as the third end of the first switch assembly.

[0008] In some examples, the second switch assembly comprises a third switch, a fourth switch and a fifth switch, a first end of the third switch is connected to a first end of the fourth switch and a first end of the fifth switch respectively, a second end of the third switch serves as the third end of the second switch assembly, a second end of the fourth switch serves as the first end of the second switch assembly, and a second end of the fifth switch serves as the second end of the second switch assembly.

[0009] In some examples, the switch unit further comprises a third switch assembly, the third switch assembly comprises a sixth switch, a first end of the sixth switch is adapted to be connected to a negative pole of the power supply device, and a second end of the sixth switch is connected to a third end of the voltage-lifting and voltage-lowering unit and adapted to be connected to a negative pole of the power battery.

[0010] In some examples, the voltage-lifting and voltage-lowering unit comprises a bridge arm and an inductor, one end of the inductor is connected to a midpoint of the bridge arm, the other end of the inductor serves as the first end of the voltage-lifting and voltage-lowering unit, a positive pole end of the bridge arm serves as the second end of the voltage-lifting and voltage-lowering unit, and a negative pole end of the bridge arm serves as the third end of the voltage-lifting and voltage-lowering unit.

[0011] In some examples, the number of bridge arms is three, and the number of inductors is three, one-to-one correspondence between the three bridge arms and the three inductors, one end of the inductor is connected to the midpoint of the corresponding bridge arm, the other end of the three inductors is connected in a converging manner, and the three bridge arms are connected in parallel.

[0012] In some examples, the bridge arm multiplexes at least one phase bridge arm of an electric vehicle motor drive circuit, and the inductor multiplexes at least one phase motor winding inductance of the motor drive circuit.

[0013] In some examples, the first switch, the second switch, the third switch, the fourth switch and the fifth switch are all contactors, and the third switch, the fourth switch and the sixth switch multiplex part of the contactors in the electric vehicle battery charging and discharging circuit.

[0014] In some examples, the charging circuit further comprises an overcurrent protection unit, a first end of the overcurrent protection unit being connected with a second end of the third switch, and a second end of the overcurrent protection unit being adapted to be connected with a positive electrode of the power battery.

[0015] In some examples, the charging circuit further comprises a controller configured to control the switching unit and the step-up and step-down unit to realize direct charging, step-up charging or step-down charging of the power supply device to the power battery.

[0016] In some examples, the controller multiplexes part of the controller devices of the electric vehicle battery management system.

[0017] In the second aspect, the utility model provides a charging system, include: power battery, photovoltaic power supply device and the charging circuit of the first aspect.

[0018] In some examples, the power supply device comprises a photovoltaic power supply device.

[0019] In some examples, the power battery is a retired power battery of a vehicle.

[0020] The charging circuit and the charging system of the utility model realize the full working condition charging mode of the charging device to the retired power battery by a step-up and step-down unit and a switching unit, improve the compatibility of the power supply device, and are low in cost. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 Fig. 1 is a schematic diagram of the charging circuit of the first embodiment of the utility model;

[0022] Figure 2 Fig. 2 is a schematic diagram of the charging circuit of one specific embodiment of the utility model;

[0023] Figure 3 Fig. 3 is a schematic diagram of the charging circuit of another specific embodiment of the utility model;

[0024] Figure 4is a schematic diagram of the charging circuit of the second embodiment of the utility model;

[0025] Figure 5 is a schematic diagram of the charging circuit of the third embodiment of the utility model;

[0026] Figure 6 is the current flow chart of the photovoltaic direct current charging mode of one embodiment of the utility model;

[0027] Figure 7 is the current flow chart under the boost timing 1 of one embodiment of the utility model;

[0028] Figure 8 is the current flow chart under the boost timing 2 of one embodiment of the utility model

[0029] Figure 9 is the current flow chart under the buck timing 1 of one embodiment of the utility model;

[0030] Figure 10 is the current flow chart under the buck timing 2 of one embodiment of the utility model;

[0031] Figure 11 is the structure block diagram of the charging system of the embodiment of the utility model.

[0032] Reference signs:

[0033] charging system 1000;

[0034] charging circuit 100;Photovoltaic power supply device 200, power battery 300;

[0035] boosting and bucking unit 10, switch unit 20, first switch assembly 21, second switch assembly 22, third switch assembly 23, first switch 1, second switch 4, third switch 3, fourth switch 2, fifth switch 5, sixth switch 6, overcurrent protection unit 80, controller 90. Specific implementation

[0036] The embodiments of the utility model are described in detail below, and the examples of the embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the utility model, and cannot be understood as limiting the utility model.

[0037] The charging circuit and charging system of the embodiments of the utility model are described below with reference to the drawings.

[0038] Figure 1 is the structure schematic diagram of the charging circuit of the embodiment of the utility model.

[0039] As Figure 1 shown in the figure, the charging circuit 100 comprises a boost-buck unit 10, a switch unit 20.

[0040] In this embodiment, referring to Figure 1 , the switch unit 20 is connected with the boost-buck unit 10 and is adapted to connect the power supply device 200 and the power battery 300, and is configured to directly connect the power battery 300 with the power supply device 200 or connect the power battery 300 with the power supply device 200 through the boost-buck unit 10; the boost-buck unit 10 is configured to raise or lower the output voltage of the power supply device 200 to the charging voltage range required by the power battery 300.

[0041] Exemplarily, the power supply device 200 can comprise a photovoltaic power supply device, a charging pile, a power grid, etc., and the power battery can be a retired power battery of a vehicle.

[0042] Specifically, through the setting of the boost-buck unit 10 and the switch unit 20, the output voltage of the power supply device 200 can be raised or lowered to the charging voltage range required by the power battery 300, so as to enable the power battery 300 to be normally charged and obtain ideal charging efficiency; through the setting of the switch unit 20, the power supply device 200 can also directly charge the power battery 300. Thus, the secondary utilization of the retired power battery 300 is realized, resource waste is reduced, and meanwhile, the full-working-condition charging mode of boost charging, buck charging and direct charging can be realized, the compatibility to the power supply device 200 is improved, and the structure of the whole circuit is simple, without the need for multiple voltage conversions, easy to realize and low in cost.

[0043] In some embodiments of the utility model, as Figure 1 shown in the figure, the switch unit 20 comprises a first switch assembly 21 and a second switch assembly 22, the first end of the first switch assembly 21 is adapted to connect the positive pole of the power supply device 200, the second end of the first switch assembly 21 is connected with the first end of the boost-buck unit 10 and the first end of the second switch assembly 22 respectively, the third end of the first switch assembly 21 is connected with the second end of the boost-buck unit 10 and the second end of the second switch assembly 22 respectively, the third end of the second switch assembly 22 is adapted to connect the positive pole of the power battery 300, and the third end of the boost-buck unit 10 is adapted to connect the negative pole of the power battery 300 and the negative pole of the power supply device 200.

[0044] Among them, the first end of the first switch assembly 21 is selectively communicated or disconnected with the second end and the third end respectively, the first end, the second end and the third end of the second switch assembly 22 are selectively communicated or disconnected with each other respectively, and the first end of the boost-buck unit 10 is selectively communicated or disconnected with the second end and the third end respectively.

[0045] Specifically, by connecting the first end of the first switch assembly 21 with the third end, and connecting the second end of the second switch assembly 22 with the third end, the power supply device 200 can directly charge the power battery 300. By connecting the first end of the first switch assembly 21 with the second end, and connecting the first end of the first switch assembly 21 with the second end of the voltage-lifting and voltage-lowering unit 10, and connecting the second end of the second switch assembly 22 with the third end, the power supply device 200 can charge the power battery 300 with voltage lifting. By connecting the first end of the first switch assembly 21 with the second end, and connecting the first end of the first switch assembly 21 with the second end of the voltage-lifting and voltage-lowering unit 10, and connecting the second end of the second switch assembly 22 with the first end, and connecting the first end of the voltage-lifting and voltage-lowering unit 10 with the third end, and connecting the second end of the second switch assembly 22 with the first end, the power supply device 200 can charge the power battery 300 with voltage lowering. Thus, by using a simple switch circuit, the power supply device 200 can realize all working conditions of charging, including voltage lifting, voltage lowering, and direct charging, thereby improving the compatibility of the power supply device 200 and reducing the cost.

[0046] In some examples, referring to Figure 1 The first switch assembly 21 includes the first switch 1 and the second switch 4, the first end of the first switch 1 and the first end of the second switch 4 serve as the first end of the first switch assembly 21, the second end of the first switch 1 serves as the second end of the first switch assembly 21, and the second end of the second switch 4 serves as the third end of the first switch assembly 21.

[0047] Optionally, the first end of the first switch 1 and the first end of the second switch 4 can be respectively connected to the power supply device 200 in the form of a single connector, or the first end of the first switch 1 and the first end of the second switch 4 can be connected and then connected to the power supply device 200 in the form of a single connector.

[0048] The first end of the first switch assembly 21 can be selectively connected or disconnected with the second end and the third end by using two switches, which is simple in implementation and low in cost.

[0049] For example, the first switch assembly 21 can also include a single-pole double-throw switch, the fixed end of the single-pole double-throw switch serves as the first end of the first switch assembly 21, and the two movable ends serve as the second end and the third end of the first switch assembly 21, respectively.

[0050] In some examples, referring to Figure 1The second switch assembly 22 comprises a third switch 3, a fourth switch 2 and a fifth switch 5, the first ends of the third switch 3 are connected with the first end of the fourth switch 2 and the first end of the fifth switch 5 respectively, the second end of the third switch 3 is the third end of the second switch assembly 22, the second end of the fourth switch 2 is the first end of the second switch assembly 22, and the second end of the fifth switch 5 is the second end of the second switch assembly 22.

[0051] The first end, the second end and the third end of the second switch assembly 22 can be selectively connected or disconnected between each other through the three switches, and the implementation is simple and low in cost.

[0052] Exemplarily, the second switch assembly 22 can comprise a single-throw double-pole switch and the fourth switch 2, the fixed end of the single-throw double-pole switch is the third end of the second switch assembly 22, one movable end is the second end of the second switch assembly 22, and the other movable end is connected with one end of the fourth switch 2, and the other end of the fourth switch 2 is the first end of the second switch assembly 22.

[0053] In some examples, referring to Figure 1 The switch unit 20 further comprises a third switch assembly 23, the third switch assembly 23 comprises a sixth switch 6, the first end of the sixth switch 6 is adapted to be connected with the negative electrode of the power supply device 200, the second end of the sixth switch 6 is connected with the third end of the voltage-lifting and voltage-lowering unit 10 and is adapted to be connected with the negative electrode of the power battery 300. Optionally, the number of the sixth switch 6 can be one or multiple, and the multiple sixth switches 6 can be connected in series or in parallel.

[0054] It should be noted that the implementation structure of the first switch assembly 21, the second switch assembly 22 and the third switch assembly 23 can also be other manners, which are not limited herein.

[0055] In some embodiments of the utility model, the voltage-lifting and voltage-lowering unit 10 comprises: a bridge arm and an inductor, one end of the inductor is connected with the midpoint of the bridge arm, the other end of the inductor is the first end of the voltage-lifting and voltage-lowering unit 10, the positive electrode end of the bridge arm is the second end of the voltage-lifting and voltage-lowering unit 10, and the negative electrode end of the bridge arm is the third end of the voltage-lifting and voltage-lowering unit 10.

[0056] Exemplarily, one bridge arm can comprise an upper bridge arm and a lower bridge arm and can be composed of two series-connected switch tubes, the switch tube can adopt a MOS (Metal-Oxide-Semiconductor Field-Effect Transistor) tube, an IGBT (Insulate-Gate Bipolar Transistor) tube or the like, and the switch tube can also be reversely connected with a diode in parallel.

[0057] In some examples, as Figure 2As shown, the number of bridge arms is 3, the number of inductors is 3, the 3 bridge arms correspond to the 3 inductors one by one, one end of the inductor is connected to the midpoint of the corresponding bridge arm, and the other end of the 3 inductors is connected in a converging manner, and the 3 bridge arms are connected in parallel.

[0058] As an implementation form, the bridge arm can be reused for at least one phase bridge arm of an electric vehicle motor driving circuit, and the inductor can be reused for at least one phase motor winding inductor (such as a motor stator winding inductor) of the motor driving circuit.

[0059] As another implementation form, the bridge arm can be reused for at least one bridge arm of an electric vehicle DCOBC (DC Onboard Charger, vehicle-mounted DC charger), and the inductor can be reused for at least one phase motor winding inductor of the electric vehicle motor driving circuit.

[0060] By reusing the bridge arm of the electric vehicle motor driving circuit and the motor winding inductor, or reusing the bridge arm of the electric vehicle DCOBC and the motor winding inductor of the electric vehicle motor driving circuit, the cost of the charging circuit 100 can be reduced. Compared with reusing the bridge arm of the DCOBC, reusing the bridge arm of the motor driving circuit requires less topology change and is easier to implement.

[0061] In some embodiments of the utility model, as shown in Figure 3 The first switch 1, the second switch 4, the third switch 3, the fourth switch 2, the fifth switch 5 and the sixth switch 6 can all use contactors.

[0062] By selecting the contactor as the control switch, the charging circuit 100 has the advantages of strong current breaking capacity, rapid action, safe operation, frequent control and remote control, etc. Alternatively, the contactor can be replaced by other controllable switches, such as relays, etc.

[0063] As an implementation form, refer to Figure 3 The fourth switch 2, the third switch 3 and the sixth switch 6 reuse part of the contactors in the electric vehicle battery charging and discharging circuit. Therefore, the cost of the charging circuit 100 can be further reduced.

[0064] In some embodiments of the utility model, as shown in Figure 4 The charging circuit 100 further comprises an overcurrent protection unit 80, the first end of the overcurrent protection unit 80 is connected to the second end of the third switch 3, and the second end of the overcurrent protection unit 80 is adapted to be connected to the positive electrode of the power battery 300.

[0065] Exemplarily, refer to Figure 4 The overcurrent protection unit 80 can use a fuse to melt when the current in the circuit is too large, thereby protecting the circuit.

[0066] In some embodiments of the utility model, as shown inFigure 5 As shown, the charging circuit 100 further comprises a controller 90.

[0067] The controller 90 is connected to the control terminals of the voltage-lifting and -lowering unit 10, the first switch 1, the second switch 4, the third switch 3, the fourth switch 2, the fifth switch 5 and the sixth switch 6 respectively, configured to perform voltage-lifting and -lowering control on the voltage-lifting and -lowering unit 20, and on-off control on the first switch 1, the second switch 4, the third switch 3, the fourth switch 2, the fifth switch 5 and the sixth switch 6.

[0068] Specifically, as an example of the embodiment shown, the controller 90 can control the on-off of each bridge arm switch tube in the voltage-lifting and -lowering unit 20, and control the on-off of each contactor through the coil of each contactor, so as to raise or lower the output voltage of the power supply device 200 to the required charging voltage range of the power battery 300, and charge the power battery 300, thereby facilitating the subsequent secondary use of the power battery 300. Figure 4

[0069] As an implementation, the controller 90 can reuse part of the controller devices of the electric vehicle BMS (Battery Management System), thereby reducing the cost of the charging circuit 100.

[0070] It should be noted that the above-mentioned reused components and part of the architecture of the high-voltage system are for the retired electric vehicles, so as to facilitate "refitting", and also achieve the secondary use of part of the components and architecture of the retired electric vehicles, further reducing resource waste.

[0071] The working principle of the charging circuit of the embodiment of the utility model will be described below in combination with Figure 6- Figure 10 As an example, the voltage-lifting and -lowering unit 10 reuses the three-phase bridge arm and the motor three-phase stator winding inductance of the motor drive circuit, the fourth switch 2, the third switch 3 and the sixth switch 6 reuse part of the contactor in the battery charging and discharging circuit of the electric vehicle, the power supply device 200 is a photovoltaic power supply device, and the power battery 300 is a retired power battery.

[0072] The charging circuit 100 of the utility model combines the secondary energy storage use of the photovoltaic power supply device 200 and the retired power battery 300 for the household energy storage direction, not only can realize direct DC charging of the retired power battery 300 by the photovoltaic power supply device 200, but also can realize voltage-lifting charging and voltage-lowering charging of the retired power battery 300 by the photovoltaic power supply device 200.

[0073] Specifically, as an example of the embodiment shown, the controller 90 can control the on-off of each bridge arm switch tube in the voltage-lifting and -lowering unit 20, and control the on-off of each contactor through the coil of each contactor, so as to raise or lower the output voltage of the power supply device 200 to the required charging voltage range of the power battery 300, and charge the power battery 300, thereby facilitating the subsequent secondary use of the power battery 300. Figure 6 ​As shown, the third switch 3, the sixth switch 6, the fifth switch 5 and the second switch 4 are controlled to be attracted (the other switches are turned off), at this time, the retired power battery 300 can be directly charged by the photovoltaic power supply device 200, and the current flow direction is as shown by the orange arrow in Figure 6 .

[0074] The boost charging principle is: by controlling the conduction and turn-off of the six power switch tubes of the motor controller in the motor drive circuit, using the freewheeling effect of the motor three-phase stator winding inductance, the functions of boost charging or buck charging can be realized.

[0075] For boost charging, boost timing 1 shown in Figure 7 and boost timing 2 shown in Figure 8 can be realized.

[0076] Boost timing 1: refer to Figure 7 , first attract the first switch 1 and the sixth switch 6 (the other switches are turned off), control the conduction of the lower bridge arm switch tube of a phase (such as the U phase in Figure 7 ) of the motor controller, and the output current of the photovoltaic power supply device 200 passes through the stator winding inductance of the motor and the lower bridge arm of the motor controller to form a closed loop. At this time, the inductance is charged by the photovoltaic power supply device 200, and the current flow direction is as shown by the orange arrow in Figure 7 .

[0077] Boost timing 2: refer to Figure 8 , continue to attract the fifth switch 5 and the third switch 3 (the first switch 1 and the sixth switch 6 are still in the attracted state), control the turn-off of the switch tube conducted in the last boost timing 1, at this time, due to the freewheeling effect of the inductance, the output current of the photovoltaic power supply device 200 passes through the stator winding inductance of the motor, the diode in the upper bridge arm of the bridge arm of the switch tube conducted in the last boost timing 1, and the power battery 300, to form a closed loop. At this time, the power battery 300 is boosted and charged by the photovoltaic power supply device 200 through the inductance to form a boost circuit, and the current flow direction is as shown by the orange arrow in Figure 8 .

[0078] For buck charging, buck timing 1 shown in Figure 9 and buck timing 2 shown in Figure 10 can be realized.

[0079] Buck timing 1: refer to Figure 9 , first attract the second switch 4, the fourth switch 2, the third switch 3 and the sixth switch 6 (the other switches are turned off), control the conduction of a phase (such as the U phase in Figure 9The U-phase upper bridge arm switch is turned on, and the output current of the photovoltaic power supply device 200 passes through the upper bridge arm of the motor controller, the stator winding inductance of the motor, and the power battery 300 to form a closed loop. Figure 9

[0080] The voltage reduction sequence 2: refer to Figure 10 The second switch 4 and the sixth switch 6 are turned off, and the switch turned on in the last sequence is turned off; at this time, due to the freewheeling effect of the inductance, the inductance current flows through the power battery 300 and the diode in the lower bridge arm of the bridge arm in which the switch turned on in the last voltage reduction sequence 1 is located, to form a closed loop; at this time, the inductance discharges, and the power battery 300 is charged at a reduced voltage, and the current flows as shown by the orange arrow in Figure 10

[0081] It should be noted that in the above voltage boosting and voltage reduction charging process, the motor stator winding can be used in multiple different ways, for example: 1) one phase of the motor three-phase stator winding inductance and a pair of motor controller bridge arms connected thereto can be used; 2) each phase of the motor three-phase stator winding inductance or each two-phase stator winding inductance and the motor controller bridge arms connected thereto can be used in turn; 3) the three-phase stator winding of the motor and the three-phase motor controller bridge arms connected thereto can be used to boost and reduce the voltage for charging, and the like. The specific use mode can be determined according to the actual scene and user demand, as long as the motor winding can be cooled and the temperature can be kept within an acceptable range. Of course, in the above scheme, if the motor stator winding inductance is not reused, a suitable inductance can be added externally to replace the motor three-phase stator winding inductance for use.

[0082] In the use process of the charging circuit 100, the selection of the charging mode (direct charging, voltage boosting charging, and voltage reduction charging) can be determined according to the actual output voltage of the photovoltaic power supply device 200. In the above voltage boosting and voltage reduction charging process, by setting the duty cycle of the switch, the output voltage of the photovoltaic power supply device 200 can be raised or lowered to the required charging voltage range of the power battery 300, so as to ensure that the battery pack can be normally charged and obtain a relatively ideal charging efficiency.

[0083] In addition, Figure 4 , Figure 6- Figure 10 ​​The AC (Air Conditioning), PTC (Positive Temperature Coefficient), DCOBC, BASU (Battery Sampling and Execution Unit), and the fuses on the AC PTC and DCOBC lines are all original architectures and components of the electric vehicle.

[0084] The charging circuit of the embodiment of the utility model can be designed for a household energy storage system, and the motor controller, the motor and part of the original circuit in the retired electric vehicle are reused, and only by adding a contactor and designing part of the topology, the full working condition charging mode of boost charging, buck charging and direct charging under the condition of photovoltaic can be completed, the compatibility with the photovoltaic power supply device is improved, and an external boost-buck converter is not needed, so that the cost is greatly reduced. Moreover, the electric energy from the photovoltaic to the end of the retired power battery does not need to be designed as a common bus, and does not need to be converted through multiple boost-buck converters (or first converted through an inverter and then converted through an energy storage converter), so that the battery pack can obtain the required voltage through only one boost-buck conversion in the boost-buck charging process, which is simple to implement and saves cost.

[0085] Figure 11 The utility model embodiment's charging system's structure block diagram.

[0086] As Figure 11 The charging system 1000 includes the power battery 300, the photovoltaic power supply device 200 and the charging circuit 100 described in the above embodiment.

[0087] The charging system of the embodiment of the utility model can realize the charging of the retired power battery by the photovoltaic power supply device through the boost-buck unit and the switching unit in the charging circuit, realizes the secondary use of the retired power battery, and thus reduces the resource waste. By reusing at least part of the circuit of the motor drive circuit of the electric vehicle through the boost-buck unit and part of the contactor in the battery charging and discharging circuit through part of the switching unit, only a few contactors and related topologies need to be added, and the boost charging, buck charging and direct charging of the retired power battery pack under the condition of photovoltaic can be realized, the compatibility with the photovoltaic power supply device is improved, and the cost is low.

[0088] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the utility model. In the description of the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0089] In the description of the utility model, it is understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the utility model and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the utility model.

[0090] In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the utility model, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0091] In the utility model, unless otherwise specifically defined and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication or interaction relationship between two elements, unless otherwise specifically limited. For ordinary skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances.

[0092] In the utility model, unless another definite provision and limitation, first feature is on second feature "on" or "under" can be first and second feature direct contact, or first and second feature indirectly contact through intermediate medium. Moreover, first feature is on second feature "on", "above" and "on" can be first feature is on second feature directly above or obliquely above, or just indicate first feature horizontal height is higher than second feature. First feature is on second feature "under", "below" and "under" can be first feature is on second feature directly below or obliquely below, or just indicate first feature horizontal height is less than second feature.

[0093] Although the embodiments of the utility model have been shown and described above, it can be understood that the above-mentioned embodiments are exemplary, and cannot be understood as the limitation of the utility model, and the ordinary skilled in the art can change, modify, replace and transform the above-mentioned embodiments within the scope of the utility model.

Claims

1. A charging circuit, characterized by, The application relates to a switching unit and a voltage conversion unit. The switching unit is connected with the voltage conversion unit and is adapted to connect a power supply device and a power battery, and is configured to directly connect the power battery with the power supply device or connect the power battery with the power supply device through the voltage conversion unit. The voltage conversion unit is configured to increase or decrease the output voltage of the power supply device to a charging voltage range required by the power battery. The switching unit comprises a first switching component and a second switching component, a first end of the first switching component is adapted to connect a positive electrode of the power supply device, a second end of the first switching component is connected with a first end of the voltage conversion unit and a first end of the second switching component respectively, a third end of the first switching component is connected with a second end of the voltage conversion unit and a second end of the second switching component respectively, a third end of the second switching component is adapted to connect a positive electrode of the power battery, a third end of the voltage conversion unit is adapted to connect a negative electrode of the power battery and a negative electrode of the power supply device.

2. The charging circuit of claim 1, wherein, The first end of the first switching component is selectively connected or disconnected with the second end and the third end respectively, the first end, the second end and the third end of the second switching component are selectively connected or disconnected with each other respectively, and the first end of the voltage conversion unit is selectively connected or disconnected with the second end and the third end respectively. The first switching component comprises a first switch and a second switch, a first end of the first switch and a first end of the second switch serve as the first end of the first switching component, a second end of the first switch serves as the second end of the first switching component, and a second end of the second switch serves as the third end of the first switching component.

3. The charging circuit of claim 2, wherein, The second switching component comprises a third switch, a fourth switch and a fifth switch, a first end of the third switch is connected with a first end of the fourth switch and a first end of the fifth switch respectively, a second end of the third switch serves as the third end of the second switching component, a second end of the fourth switch serves as the first end of the second switching component, and a second end of the fifth switch serves as the second end of the second switching component.

4. The charging circuit of claim 3, wherein, The switching unit further comprises a third switching component, the third switching component comprises a sixth switch, a first end of the sixth switch is adapted to connect a negative electrode of the power supply device, and a second end of the sixth switch is connected with a third end of the voltage conversion unit and adapted to connect a negative electrode of the power battery.

5. The charging circuit of claim 4, wherein, The voltage conversion unit comprises bridge arms and inductors, one end of the inductor is connected with a midpoint of the bridge arm, the other end of the inductor serves as the first end of the voltage conversion unit, a positive electrode end of the bridge arm serves as the second end of the voltage conversion unit, and a negative electrode end of the bridge arm serves as the third end of the voltage conversion unit.

6. The charging circuit of claim 2, wherein, The number of the bridge arms is three, the number of the inductors is three, one inductor corresponds to one bridge arm, one end of the inductor is connected with a midpoint of the corresponding bridge arm, the other ends of the three inductors are connected in a converging mode, and the three bridge arms are connected in parallel.

7. The charging circuit of claim 6, wherein, ​ 8. The charging circuit of claim 6, wherein, The at least one phase bridge arm of the bridge arm multiplexing electric vehicle motor drive circuit multiplexes at least one phase motor winding inductance of the motor drive circuit.

9. The charging circuit of claim 5, wherein, The first switch, the second switch, the third switch, the fourth switch and the fifth switch are contactors, and the third switch, the fourth switch and the sixth switch multiplex part of the contactors in the electric vehicle battery charging and discharging circuit.

10. The charging circuit of claim 4, wherein, The charging circuit further comprises an overcurrent protection unit, a first end of the overcurrent protection unit is connected with a second end of the third switch, and a second end of the overcurrent protection unit is adapted to be connected with a positive electrode of the power battery.

11. The charging circuit according to any one of claims 1 to 10, wherein The charging circuit further comprises a controller configured to control the switch unit and the buck-boost unit to realize direct charging or boost charging or buck charging of the power supply device to the power battery.

12. The charging circuit of claim 11, wherein, The controller multiplexes part of the controller devices of the electric vehicle battery management system.

13. A charging system, characterized by The charging circuit comprises: The power supply device, the power battery, and the charging circuit according to any one of claims 1-12.

14. The charging system of claim 13, wherein, The power supply device comprises a photovoltaic power supply device.

15. The charging system of claim 13, wherein, The power battery is a retired power battery of a vehicle.

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