Charging and discharging circuits, charging and discharging systems, and vehicles

Abstract

The present invention discloses a charging and discharging circuit, a charging and discharging system, and a vehicle, which relate to the technical field of new energy vehicles and aim to improve the charging or discharging efficiency of a vehicle during the charging or discharging process. The charging and discharging circuit includes an inverter circuit and a drive motor. The first end of the inverter circuit is connected to the first pole of the battery pack, and the second end of the inverter circuit is connected to the second pole of the battery pack; the inverter circuit includes a plurality of switching elements. The first end of the drive motor is connected to the third end of the inverter circuit, the second end of the drive motor is electrically connected to the first end of the charging and discharging port, and the second end of the charging and discharging port is electrically connected to the second pole of the battery pack and the second end of the inverter circuit. The switching frequency of at least one of the plurality of switching elements is determined according to the current value flowing through the second end of the drive motor.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicles, and in particular to a charging and discharging circuit, a charging and discharging system, and a vehicle. Background Art

[0002] As the number of electric vehicles in the market continues to grow, the charging efficiency of the vehicle is one of the reference items for consumers when purchasing a vehicle. How to improve the charging efficiency of electric vehicles to achieve fast charging is one of the research directions of those skilled in the art. Summary of the invention

[0003] The object of the present invention is to provide a charging and discharging circuit, a charging and discharging system, and a vehicle.

[0004] In a first aspect, the present invention provides a charging and discharging circuit. The charging and discharging includes an inverter circuit and a drive motor. The first end of the inverter circuit is electrically connected to the first pole of the battery pack, and the second end of the inverter circuit is electrically connected to the second pole of the battery pack; the inverter circuit includes a plurality of switching elements. The first end of the drive motor is electrically connected to the third end of the inverter circuit; the second end of the drive motor is electrically connected to the first end of the charging and discharging port, and the second end of the charging and discharging port is electrically connected to the second pole of the battery pack and the second end of the inverter circuit. Among them, the switching frequency of at least one of the plurality of switching elements is determined according to the current value flowing through the second end of the drive motor.

[0005] The charging and discharging circuit provided in the embodiment of the present application can determine the switching frequency of the switching elements of the inverter circuit according to the charging or discharging current of the battery pack, and control the switching elements of the inverter circuit to operate at the determined switching frequency, thereby improving the charging or discharging power of the battery pack, and further improving the charging or discharging efficiency of the battery pack, and reducing the time required for the battery pack to charge or discharge.

[0006] In some embodiments, the switching frequency of at least one switching element is based on the current value of the second end of the driving motor, and the charging or discharging efficiency of the charging and discharging circuit meets the switching frequency required by the set requirements.

[0007] In some embodiments, the switching frequency is selected from an efficiency mapping table, which is used to characterize the corresponding relationship between the current flowing through the second end of the drive motor and the switching frequency of at least one switching element when the charging or discharging efficiency of the charging and discharging circuit meets the set requirements.

[0008] In some embodiments, the set requirement is that the charging or discharging efficiency is greater than or equal to a set value, or the charging or discharging efficiency is optimal.

[0009] In some embodiments, the inverter circuit includes multi-phase bridge arms connected in parallel, and each phase bridge arm is electrically connected between a first end and a second end of the inverter circuit.

[0010] Each phase bridge arm includes a first switch element and a second switch element, and the plurality of switch elements include the first switch element and the second switch element. The first end of the first switch element is electrically connected to the first end of the inverter circuit, the second end of the first switch element is electrically connected to the first end of the second switch element, and the second end of the second switch element is electrically connected to the second end of the inverter circuit. The common end of a first switch element and a second switch element is a third end of the inverter circuit.

[0011] The drive motor includes multiple groups of winding coils, a first end of a group of winding coils is connected to the common end of the first switching element and the second switching element of a phase bridge arm, and a second end of a group of winding coils is connected to the second end of the drive motor.

[0012] In some embodiments, when charging the battery pack, the voltage provided by the charging and discharging ports is boosted by the inverter circuit and the drive motor and then output to the battery pack.

[0013] In some embodiments, during the boost process, the charge and discharge circuit includes switching between a first stage and a second stage.

[0014] In the first stage, the second switch element of at least one phase bridge arm of the inverter circuit is turned on from the first end to the second end, so that the charging and discharging port, the winding coil, and the second switch element electrically connected to the winding coil form a loop.

[0015] In the second stage, the first switching element of at least one phase bridge arm of the inverter circuit is turned on from the second end to the first end, and the second switching element is turned off, so that the charging and discharging port, the winding coil, the first switching element electrically connected to the winding coil, and the battery pack form a loop.

[0016] In some embodiments, the charge and discharge circuit also includes a first relay and a second relay, the first relay is electrically connected between the second end of the drive motor and the first end of the charge and discharge port, and the second relay is electrically connected between the second pole of the battery pack and the second end of the charge and discharge port.

[0017] In some embodiments, the first end of the inverter circuit is also electrically connected to the first end of the charge and discharge port. The charge and discharge system also includes a third relay, one end of the third relay is electrically connected to the first pole of the battery pack, and the other end of the third relay is electrically connected to the first end of the inverter circuit.

[0018] In some embodiments, when the battery pack is discharging, the voltage output by the battery pack is stepped down by the inverter circuit and the drive motor and then output to the charge and discharge port to power the device to be charged.

[0019] In some embodiments, during the voltage reduction process, the charge and discharge circuit includes switching between the third stage and the fourth stage.

[0020] In the third stage, the third relay is turned on, and the first end to the second end of the first switch element of at least one phase bridge arm of the inverter circuit is turned on, and the battery pack, the third relay, the first switch element, the drive motor, and the device to be charged form a loop.

[0021] In the fourth stage, the third relay is disconnected, and the second end to the first end of the second switch element of at least one phase bridge arm of the inverter circuit is connected, and the drive motor, the device to be charged, and the second switch element form a loop.

[0022] In some embodiments, the charge and discharge circuit further includes a fourth relay, one end of the fourth relay is electrically connected to the first pole of the battery pack, and the other end of the fourth relay is electrically connected to the first end of the charge and discharge port.

[0023] In some embodiments, when an external power source is connected to the charge and discharge port to charge the battery pack, if the voltage of the charge and discharge port is greater than or equal to the voltage of the battery pack, the fourth relay is turned on, or both the first relay and the fourth relay are turned on.

[0024] When an external power source is connected to the charge and discharge port to charge the battery pack, if the voltage of the charge and discharge port is lower than the voltage of the battery pack, the first relay is turned on.

[0025] In some embodiments, the charge and discharge circuit further includes a fifth relay, one end of the fifth relay is connected to the first pole of the battery pack, and the other end of the fifth relay is connected to the second end of the drive motor.

[0026] In some embodiments, when charging the battery pack, the voltage provided by the charging and discharging ports is stepped down by the inverter circuit and the drive motor and then output to the battery pack.

[0027] In some embodiments, during the voltage reduction process, the charge and discharge circuit includes switching between a fifth stage and a sixth stage.

[0028] In the fifth stage, the fourth relay and the fifth relay are turned on, and the first switching element of at least one phase bridge arm of the inverter circuit is turned on from the first end to the second end, so that the charging and discharging port, the fourth relay, at least one first switching element, the winding coil connected to the first switching element, the fifth relay, and the battery pack form a loop.

[0029] In the sixth stage, the fourth relay is disconnected, the fifth relay is turned on, and the second switching element of at least one phase bridge arm of the inverter circuit is turned on from the second end to the first end, so that the winding coil, the fifth relay, the battery pack, and the second switching element form a loop.

[0030] In some embodiments, when the battery pack is discharging, the voltage output by the battery pack is boosted by the drive motor and the inverter circuit and then output to the charge and discharge port to power the device to be charged.

[0031] In some embodiments, during the boost process, the charge and discharge circuit includes switching between a seventh stage and an eighth stage.

[0032] In the seventh stage, the fourth relay is disconnected, the fifth relay is turned on, and the first end to the second end of the second switching element of at least one phase bridge arm of the inverter circuit is turned on, so that the battery pack, the fifth relay, the winding coil, and the second switching element connected to the winding coil form a loop.

[0033] In the eighth stage, the fourth relay and the fifth relay are turned on, and the second end to the first end of the first switching element of at least one phase bridge arm of the inverter circuit is turned on, so that the battery pack, the fifth relay, the winding coil, the first switching element connected to the winding coil, the fourth relay, and the device to be charged form a loop.

[0034] In a second aspect, the present invention provides a charging and discharging system. The charging and discharging system comprises a charging and discharging circuit as described in any of the above embodiments, and a controller. The controller is electrically connected to the control terminals of a plurality of switching elements of the inverter circuit. The controller is configured to output a pulse width modulation signal to the at least one switching element to adjust the switching frequency of the at least one switching element.

[0035] In some embodiments, the controller is further configured to determine a switching frequency of at least one of the plurality of switching elements according to a charging current flowing through the second end of the drive motor when charging the battery pack.

[0036] In some embodiments, the controller is further configured to determine a switching frequency of at least one of the plurality of switching elements according to a discharge current flowing through the second end of the drive motor when the battery pack is discharging.

[0037] The above-mentioned charging and discharging system has the same structure and beneficial technical effects as the charging and discharging circuits provided in some of the above-mentioned embodiments, which will not be repeated here.

[0038] In a third aspect, the present invention provides a vehicle, wherein the vehicle comprises a charging and discharging system as provided in any of the above embodiments.

[0039] The above-mentioned vehicle has the same structure and beneficial technical effects as the charging and discharging circuits provided in some of the above-mentioned embodiments, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0041] Figure 1 is a circuit structure topology diagram of a charge and discharge circuit according to some embodiments;

[0042] Figure 2 Based on Figure 1 The current flow diagram of the charging and discharging circuit in the first stage is shown;

[0043] Figure 3 Based on Figure 1 The current flow diagram of the charging and discharging circuit in the second stage is shown;

[0044] Figure 4 Based on Figure 1 The current flow diagram of the charging and discharging circuit in the third stage is shown;

[0045] Figure 5 Based on Figure 1 The current flow diagram of the charging and discharging circuit in the fourth stage is shown;

[0046] Figure 6 is a circuit structure topology diagram of a charge and discharge circuit according to some other embodiments;

[0047] Figure 7 Based on Figure 6 A current flow diagram of the charging and discharging circuit shown in the figure during the charging process of the battery pack;

[0048] Figure 8 Based on Figure 6 Another current flow diagram of the charging and discharging circuit shown in the figure during the charging process of the battery pack;

[0049] Fig. 9 Based on Figure 6 A current flow diagram of the charging and discharging circuit shown in the battery pack discharge process;

[0050] Fig.10 is a circuit structure topology diagram of a charge and discharge circuit according to some other embodiments;

[0051] Fig.11 Based on Fig.10 The current flow diagram of the charging and discharging circuit in the fifth stage is shown;

[0052] Fig.12 Based on Fig.10 The current flow diagram of the charging and discharging circuit in the sixth stage is shown;

[0053] Fig.13 Based on Fig.10 The current flow diagram of the charge and discharge circuit in the seventh stage is shown;

[0054] Fig.14 Based on Fig.10The current flow diagram of the charge and discharge circuit in the eighth stage is shown;

[0055] Fig.15 Based on Fig.10 A current flow diagram of the charging and discharging circuit shown in the figure during the charging process of the battery pack;

[0056] Fig.16 Based on Fig.10 A current flow diagram of the charging and discharging circuit shown in the battery pack discharge process;

[0057] Fig.17 Based on Fig.10 Another current flow diagram of the charging and discharging circuit shown in the figure during the charging process of the battery pack;

[0058] Fig.18 Based on Fig.10 Another current flow diagram of the charging and discharging circuit shown in the battery pack discharge process;

[0059] Fig.19 is a curve diagram showing changes in charging current versus charging time during charging of a battery pack by a charging and discharging circuit according to some embodiments;

[0060] Fig. 20 is an efficiency mapping table of a charging and discharging system according to some embodiments.

[0061] Reference numerals:

[0062] L1, first winding coil; L2, second winding coil; L3, third winding coil;

[0063] S1, S3, S5, first switch element; S2, S4, S6, second switch element;

[0064] K1, first relay; K2, second relay; K3, third relay; K4, fourth relay; K5, fifth relay;

[0065] C1, first capacitor; C2, second capacitor. DETAILED DESCRIPTION

[0066] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0067] In the description of the present invention, it should be understood that the terms "upper", "lower", "left", "right", "front", "back", "inside", "outside" and the like indicate directions or positional relationships based on the directions or relative positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention. Unless otherwise specified, the above-mentioned directional description can be flexibly set in the process of actual application under the condition that the relative positional relationship shown in the accompanying drawings is satisfied.

[0068] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0069] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection. It can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0070] In the embodiments of the present invention, the terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, article or device including the element.

[0071] In the embodiments of the present invention, words such as "exemplary" or "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present invention should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0072] Some embodiments of the present disclosure provide a vehicle, which includes a charging and discharging system.

[0073] The transportation tools described in the present application include but are not limited to vehicles, airplanes, ships, etc., and the transportation tools have a charging and discharging system.

[0074] The following uses a vehicle as an example to illustrate some embodiments of the present application.

[0075] In some embodiments, a vehicle includes a battery pack and a charging and discharging system. The charging and discharging system includes a charging and discharging circuit and a controller.

[0076] The battery pack is charged or discharged by the charging and discharging system. The battery pack is electrically connected to a load, and the battery pack is configured to provide electrical energy to the load electrically connected thereto.

[0077] Exemplarily, the battery pack may include one or more power batteries, and multiple (two or more) power batteries are connected in sequence to form a power battery group.

[0078] In some embodiments, Figure 1 As shown, the load includes a drive motor, which is electrically connected to the battery pack. The drive motor is configured to convert the electrical energy provided by the battery pack into a driving force to drive the vehicle.

[0079] The battery pack is a DC voltage source. When the drive motor is an AC drive motor, the electric energy provided by the battery pack needs to be converted into AC current before being provided to the drive motor.

[0080] Based on this, Figure 1 As shown, in some embodiments, the charging and discharging circuit further includes an inverter circuit.

[0081] The inverter circuit includes a plurality of parallel-connected bridge arms, each of which is electrically connected between a first end and a second end of the inverter circuit. Each of which includes a first switching element S1 / S3 / S5 (such as Figure 1 The S1, S3, and S5 shown in the figure are all first switching elements) and second switching elements S2 / S4 / S6 ( Figure 1 S2, S4, and S6 shown in the figure are all second switching elements), the first end of the first switching element S1 / S3 / S5 is electrically connected to the first end of the inverter circuit, the second end of the first switching element S1 / S3 / S5 is electrically connected to the first end of the second switching element S2 / S4 / S6, and the second end of the second switching element S2 / S4 / S6 is electrically connected to the second end of the inverter circuit.

[0082] In the case where the drive motor is an AC drive motor, the inverter circuit is configured to convert the DC current provided by the battery pack into AC current and transmit the converted AC current to the drive motor.

[0083] In some embodiments, Figure 1As shown, the inverter circuit includes a plurality of switching elements ( Figure 1 The plurality of switch elements include a plurality of first switch elements S1 / S3 / S5 and a plurality of second switch elements S2 / S4 / S6. The inverter circuit includes a multi-phase bridge arm, and one phase bridge arm includes a first switch element S1 / S3 / S5 and a second switch element S2 / S4 / S6 connected in series.

[0084] like Figure 1 As shown, the first end of the first switch element S1 / S3 / S5 is electrically connected to the first end of the inverter circuit, the second end of the first switch element S1 / S3 / S5 is electrically connected to the first end of the corresponding second switch element S2 / S4 / S6, and the second end of the second switch element S2 / S4 / S6 is electrically connected to the second end of the inverter circuit. The common terminal of the first switch element S1 / S3 / S5 and the second switch element S2 / S4 / S6 of one phase bridge arm of the inverter circuit is a third terminal of the inverter circuit.

[0085] Exemplarily, the inverter circuit may be an inverter. The drive motor may be a three-phase drive motor, and the inverter circuit may be a three-phase inverter. Some embodiments of the present application are described below by taking the drive motor as a three-phase drive motor and the inverter circuit as a three-phase inverter as an example.

[0086] In some embodiments, Figure 1 As shown, the drive motor includes multiple groups of winding coils, a first end of a group of winding coils of the drive motor is electrically connected to the common end of the first switching element S1 / S3 / S5 and the second switching element S2 / S4 / S6 of a phase bridge arm, and a second end of a group of winding coils is electrically connected to the second end of the drive motor.

[0087] A common terminal of a first switching element S1 / S3 / S5 and a second switching element S2 / S4 / S6 is a third terminal of the inverter circuit.

[0088] Take the example that the drive motor includes three sets of winding coils and the inverter circuit includes three-phase bridge arms. Figure 1 As shown, the drive motor includes a first winding coil L1, a second winding coil L2 and a third winding coil L3, and the inverter circuit includes a first bridge arm, a second bridge arm and a third bridge arm.

[0089] The first bridge arm of the inverter circuit includes a first switch element S1 and a second switch element S2 , and a first end of a first winding coil L1 of the drive motor is electrically connected between the first switch element S1 and the second switch element S2 .

[0090] The second bridge arm of the inverter circuit includes a first switch element S3 and a second switch element S4 , and a first end of the second winding coil L2 of the drive motor is electrically connected between the first switch element S3 and the second switch element S4 .

[0091] The third bridge arm of the inverter circuit includes a first switch element S5 and a second switch element S6 , and the third winding coil L3 of the drive motor is electrically connected between the first switch element S5 and the second switch element S6 .

[0092] For example, a switch element may include a MOS tube (Metal-Oxide-Semiconductor Field-Effect Transistor), or a switch element may include a transistor and a diode connected in parallel.

[0093] When a switching element includes a MOS tube, the first electrode of the MOS tube included in the first switching element is connected to the first end of the inverter circuit, the second electrode of the MOS tube included in the first switching element is connected to the first electrode of the MOS tube of a second switching element, and the second electrode of the MOS tube of the second switching element is connected to the second end of the inverter circuit; the common terminal of the MOS tube included in the first switching element and the MOS tube of the second switching element is a third end of the inverter circuit.

[0094] By controlling the on-off of the MOS tube included in the first switch element, the on-off of the first end and the third end of the inverter circuit can be controlled; and by controlling the conduction direction of the MOS tube included in the first switch element, the conduction direction between the first end and the third end of the inverter circuit can be controlled.

[0095] By controlling the on-off of the MOS tube included in the second switch element, the on-off of the second end and the third end of the inverter circuit can be controlled; and by controlling the conduction direction of the MOS tube included in the second switch element, the conduction direction between the second end and the third end of the inverter circuit can be controlled.

[0096] In the case where a switching element comprises a transistor and a diode connected in parallel, such as Figure 1 As shown, the first end of the diode is electrically connected to the second end of the transistor, the second end of the diode is electrically connected to the first end of the transistor, the first end of the transistor and the second end of the diode are both electrically connected to the first end of the inverter circuit, and the second end of the transistor and the first end of the diode are both electrically connected to the second end of the inverter circuit.

[0097] When the transistor is turned on, the first end to the second end of the transistor is turned on, and in other cases, the transistor is considered to be open; the first end to the second end of the diode is turned on, and the second end to the first end of the diode is cut off (considered to be open); and in each switch element, the transistor and the diode are turned on in time. In this case, the transistor can be an IGBT (Insulated Gate Bipolar Transistor).

[0098] Exemplarily, the charging and discharging system further includes a controller, which is electrically connected to the control terminals of the plurality of switch elements of the inverter circuit. By controlling the on and off of the transistor and the diode, the conduction direction of the switch element can be controlled. When the transistor is turned on and the diode is turned off, the switch element is turned on from the first terminal to the second terminal; when the transistor is turned off and the diode is turned on, the switch element is turned on from the second terminal to the first terminal.

[0099] During the driving process of the vehicle, the inverter circuit can convert the DC power provided by the battery pack into power and provide it to the drive motor to drive the drive motor to work. The battery pack can store a limited amount of electrical energy. Based on this, the battery pack can also be electrically connected to the charge and discharge port to transmit electrical energy to the battery pack through the charge and discharge port to charge the battery pack.

[0100] In some embodiments, Figure 1 As shown, one end of the charge and discharge circuit is connected to the battery pack, and the other end of the charge and discharge circuit is connected to the charge and discharge port. The battery pack and the charge and discharge port transmit electric energy through the charge and discharge circuit. The electric energy transmission between the battery pack and the charge and discharge port can be that an external power source charges the battery pack through the charge and discharge port, or the battery discharges to the outside through the charge and discharge port.

[0101] Exemplarily, when an external power source is connected to the charging and discharging port, the external power source charges the battery pack. The external power source may be a DC power source, for example, a DC charging pile or a DC energy storage power source (such as a battery pack in a mobile charging vehicle, an energy storage device, or another means of transportation).

[0102] When the battery discharges to the outside through the charge and discharge port, the charge and discharge port can be connected to a DC charging pile, a DC energy storage power supply, or an external load.

[0103] When charging the battery pack or discharging the battery pack, if the voltage of the battery pack and the voltage of the charge and discharge port do not match, for example, the difference between the voltage of the battery pack and the voltage of the charge and discharge port is not within the set range, then it is necessary to set a voltage regulation circuit between the battery pack and the charge and discharge port to adjust the voltage of the battery pack or the voltage of the charge and discharge port to match.

[0104] The following describes some situations where the voltage of the battery pack and the voltage of the charging and discharging ports do not match.

[0105] 1. Charge the battery pack. The voltage at the charging and discharging ports should be less than or equal to the voltage of the battery pack.

[0106] 2. When charging the battery pack, the voltage of the charging and discharging ports is greater than the voltage of the battery pack, and the difference between the two voltages is greater than the set range.

[0107] 3. The battery pack is discharged externally, and the voltage of the battery pack is less than or equal to the voltage of the charge and discharge ports.

[0108] 4. The battery pack is discharged externally, and the voltage of the battery pack is greater than the voltage of the charge and discharge port, and the difference between the two voltages is greater than the set range.

[0109] Take charging a battery pack with a DC charging pile as an example. For example, the rated voltage of the battery pack is 800V, and the power supply voltage provided by the charge and discharge port is 400V. In this case, the power supply voltage of the charge and discharge port is lower than the rated voltage of the battery pack. Therefore, the charge and discharge port cannot directly supply power to the battery pack to charge the battery pack. It is necessary to boost the 400V power supply voltage provided by the charge and discharge port to 800V, and provide the boosted 800V power supply voltage to the battery pack to charge the battery pack.

[0110] In order to make the vehicle compatible with different charging piles, a boost converter can be installed in the vehicle. However, the greater the boost pressure difference (voltage difference before and after boost) that the boost converter can achieve, the greater the weight and volume of the boost converter, and the higher the price, which will lead to an increase in the weight of the vehicle. In addition, a larger space needs to be reserved in the vehicle for the boost converter, which compresses the vehicle space and causes an increase in the cost of the vehicle.

[0111] Based on this, some embodiments of the present application provide a charging and discharging circuit that can utilize the vehicle's own inverter circuit and drive motor to achieve voltage matching and regulation between the battery pack and the charging and discharging ports.

[0112] In some embodiments, Figure 1 As shown, the charge and discharge circuit also includes a first relay K1 and a second relay K2. The first relay K1 is electrically connected between the second end of the drive motor and the first end of the charge and discharge port, and the second relay K2 is electrically connected between the second pole of the battery pack and the second end of the charge and discharge port.

[0113] Exemplarily, the charge and discharge circuit further includes a first capacitor C1. One end of the first capacitor C1 is connected to the common terminal of the first relay K1 and the first end of the charge and discharge port, and the other end of the first capacitor C1 is connected to the second end of the charge and discharge port. When the battery pack is charged or the battery pack is discharged, the first capacitor C1 is connected in parallel to both ends of the charge and discharge port.

[0114] The first capacitor C1 itself has good voltage balancing characteristics. The first capacitor C1 is connected in parallel at both ends of the battery pack. When the battery pack includes multiple power batteries, it can form voltage distribution among the multiple power batteries in the battery pack, achieve battery voltage balancing, and ensure voltage balance among the power batteries in the battery pack.

[0115] In addition, the first capacitor C1 connected in parallel at both ends of the battery pack can improve the transient discharge performance of the battery pack and achieve high current output in a short time. The first capacitor C1 can store electrical energy. When the vehicle starts and accelerates, the first capacitor C1 can quickly release the stored energy to increase the output power of the battery pack. It plays an important role when the output of the battery pack cannot meet the instantaneous demand and can effectively protect the battery pack from instantaneous high current discharge.

[0116] In some embodiments, Figure 1 As shown, the first end of the inverter circuit is also electrically connected to the first end of the charge and discharge port. The charge and discharge system also includes a third relay K3, one end of the third relay K3 is electrically connected to the first pole of the battery pack, and the other end of the third relay K3 is electrically connected to the first end of the inverter circuit.

[0117] Exemplarily, the charge and discharge circuit further includes a second capacitor C2. One end of the second capacitor C2 is connected to the common terminal of the third relay K3 and the first end of the inverter circuit, and the other end of the second capacitor C2 is connected to the second electrode of the battery pack. When the battery pack is charged or discharged, the second capacitor C2 is connected in parallel to both ends of the battery pack.

[0118] By providing the second capacitor C2, the current provided by the charging and discharging port can be filtered, thereby reducing the influence of the ripple current in the current provided by the charging and discharging port on the charging and discharging circuit.

[0119] In some embodiments, Figure 2 and Figure 3 As shown, when the battery pack is charged, the voltage provided by the charge and discharge ports is boosted by the inverter circuit and the drive motor and then output to the battery pack.

[0120] Exemplarily, during the voltage boost process, a switching frequency of at least one switching element among a plurality of switching elements included in the drive motor is determined according to a current value flowing through the second end of the drive motor.

[0121] When charging the battery pack through the charge and discharge circuit, the appropriate switching frequency is selected based on the value of the battery pack charging current, and the switching elements in the inverter circuit are controlled to operate at the selected switching frequency, so that the charge and discharge circuit can charge the battery pack with the charging power required to meet the set requirements, thereby improving the charging efficiency of the charge and discharge circuit and reducing the charging time of the battery pack.

[0122] In some embodiments, Figure 2 and Figure 3 As shown, during the boost process, the charge and discharge circuit includes switching between a first stage and a second stage.

[0123] like Figure 2 As shown, in the first stage, the first relay K1 and the second relay K2 are turned on, the third relay K3 is turned off, and the second switch element S2 / S4 / S6 of at least one phase bridge arm of the inverter circuit is turned on from the first end to the second end, so that the charge and discharge port, the first relay K1, the winding coil, the second switch element S2 / S4 / S6 electrically connected to the winding coil and the second relay K2 form a loop. Among them, the switching frequency of the second switch element S2 / S4 / S6 is determined according to the current value flowing through the second end of the drive motor.

[0124] like Figure 3 As shown, in the second stage, the first relay K1, the second relay K2 and the third relay K3 are turned on, the first switch element S1 / S3 / S5 of at least one phase bridge arm of the inverter circuit is turned on from the second end to the first end, and the second switch element S2 / S4 / S6 is turned off, so that the charging and discharging port, the first relay K1, the winding coil, the first switch element S1 / S3 / S5 electrically connected to the winding coil, the third relay K3, the battery pack and the second relay K2 form a loop. Among them, the switching frequency of the first switch element S1 / S3 / S5 is determined according to the current value flowing through the second end of the drive motor.

[0125] In this embodiment, in the first stage, in the multi-phase bridge arm of the inverter circuit, the first end to the second end of the second switch element S2 / S4 / S6 of at least one phase bridge arm is turned on. Figure 2 As shown, at least one of the second switch element S2 , the second switch element S4 , and the second switch element S6 is conductive from the first end to the second end.

[0126] In the second stage, in the multi-phase bridge arm of the inverter circuit, the second end to the first end of the first switch element S1 / S3 / S5 of at least one phase bridge arm is turned on. Figure 3 As shown, the second end to the first end of at least one of the first switch element S1 , the first switch element S3 and the first switch element S5 is conductive.

[0127] like Figure 2 and Figure 3 As shown, the winding coil in the second stage is equivalent to another power supply connected in series with the charge and discharge port. The two together supply power to the battery pack, thereby increasing the voltage on the power supply side and realizing the boost charging of the battery pack by the charge and discharge port.

[0128] There is a mapping relationship between the current flowing through the second end of the drive motor and the switching frequency of at least one switching element.

[0129] Optionally, in this embodiment, in both the first stage and the second stage, a switching frequency that meets the set requirements can be selected from the efficiency mapping table according to the current flowing through the second end of the drive motor, and the switching elements (at least one of the first switching element S1 / S3 / S5 or the second switching element S2 / S4 / S6) in the inverter circuit that participate in the first stage and the second stage are operated at the switching frequency, thereby improving the energy storage efficiency of the energy storage process of the winding coil in the first stage and the charging efficiency of the battery pack in the second stage. The mapping table can be, but is not limited to, obtained by calibration.

[0130] In some embodiments, Figure 4 and Figure 5 As shown, when the battery pack is discharging, the voltage output by the battery pack is stepped down by the inverter circuit and the drive motor and then output to the charge and discharge port to power the device to be charged.

[0131] Exemplarily, during the voltage reduction process, a switching frequency of at least one switching element among a plurality of switching elements included in the drive motor is determined according to a current value flowing through the second end of the drive motor.

[0132] When the battery pack is discharged through the charge and discharge circuit, a suitable switching frequency is selected based on the value of the battery pack discharge current, and the switching elements in the inverter circuit are controlled to operate at the selected switching frequency, so that the charge and discharge circuit can discharge at a charging power that meets the set requirements, thereby improving the discharge efficiency of the charge and discharge circuit.

[0133] In some embodiments, Figure 4 and Figure 5 As shown, during the voltage reduction process, the charge and discharge circuit includes switching between the third stage and the fourth stage.

[0134] like Figure 4 As shown, in the third stage, the third relay K3 is turned on, the first end to the second end of the first switch element S1 / S3 / S5 of at least one phase bridge arm of the inverter circuit is turned on, and the battery pack, the third relay K3, the first switch element, the drive motor, and the device to be charged form a loop.

[0135] like Figure 5 As shown, in the fourth stage, the third relay K3 is disconnected, and the second end to the first end of the second switch element S2 / S4 / S6 of at least one phase bridge arm of the inverter circuit is turned on, and the drive motor, the device to be charged, and the second switch element form a loop.

[0136] In this embodiment, in the third stage, in the multi-phase bridge arm of the inverter circuit, the second end to the first end of the first switch element S1 / S3 / S5 of at least one phase bridge arm is turned on. Figure 4As shown, the second end to the first end of at least one of the first switch element S1 , the first switch element S3 and the first switch element S5 is conductive.

[0137] In the fourth stage, in the multi-phase bridge arm of the inverter circuit, the second end to the first end of the second switch element S2 / S4 / S6 of at least one phase bridge arm is turned on. Figure 5 As shown, the second end to the first end of at least one of the second switch element S2, the second switch element S4 and the second switch element S6 is conductive.

[0138] like Figure 4 and Figure 5 As shown, in the fourth stage, the winding coil is equivalent to the power supply supplying power to the charging and discharging port, and the output voltage of the winding coil is lower than the voltage of the battery pack, thereby reducing the voltage on the power supply side and realizing the voltage reduction discharge of the battery pack to the outside.

[0139] Moreover, in both the third stage and the fourth stage, the switching frequency required to meet the set requirements can be selected in the efficiency mapping table according to the current flowing through the second end of the drive motor, and the switching elements participating in the third stage or the fourth stage (at least one of the first switching element S1 / S3 / S5 or the second switching element S2 / S4 / S6) can be operated at the switching frequency, thereby improving the energy storage efficiency of the winding coil in the energy storage process in the third stage and the discharge efficiency of the winding coil in the external discharge process in the fourth stage.

[0140] In some embodiments, Figure 6 As shown, the charge and discharge circuit further includes a fourth relay K4, one end of the fourth relay K4 is electrically connected to the first pole of the battery pack, and the other end of the fourth relay K4 is electrically connected to the first end of the charge and discharge port.

[0141] In some embodiments, Figure 7 and Figure 8 As shown, when an external power source is connected to the charge and discharge port to charge the battery pack, if the voltage of the charge and discharge port is greater than or equal to the voltage of the battery pack, the fourth relay K4 is turned on, or both the first relay K1 and the fourth relay K4 are turned on.

[0142] When the external power source connected to the charging and discharging port matches the power source of the battery pack, such as Figure 7 As shown, in the charge and discharge circuit, the first relay K1, the second relay K2, the third relay K3 and the fourth relay K4 may be turned on. In this case, the second end to the first end of the first switch element of at least one phase bridge arm of the inverter circuit is turned on, forming two current branches between the first pole of the battery pack and the first end of the charge and discharge port.

[0143] The current flow direction of the first branch is: the first end of the charging and discharging port → the fourth relay K4 → the third relay K3 → the first pole of the battery pack, and the current flow direction of the second branch is: the first end of the charging and discharging port → the first relay K1 → at least one group of winding coils → the first switching element connected to the winding coils → the third relay K3 → the first pole of the battery pack.

[0144] In some embodiments, when the external power source connected to the charging and discharging port matches the power source of the battery pack, such as Figure 8 As shown, in the charge and discharge circuit, the first relay K1 can be disconnected, the second relay K2, the third relay K3 and the fourth relay K4 can be turned on, the charge and discharge port and the battery pack form a loop, and the external power supply charges the battery pack through the charge and discharge port.

[0145] Based on this, in some embodiments, when the battery pack is discharged and the voltage of the battery pack matches the voltage of the charge and discharge port, as Fig. 9 As shown, in the charge and discharge circuit, the second relay K2, the third relay K3 and the fourth relay K4 may be turned on, the charge and discharge port and the battery pack form a loop, and the battery pack discharges to the outside through the charge and discharge port.

[0146] In some embodiments, Figure 6 As shown, when an external power source is connected to the charge and discharge port to charge the battery pack, if the voltage of the charge and discharge port is lower than the voltage of the battery pack, the first relay K1 is turned on.

[0147] If the external power supply connected to the charging and discharging port does not match the power supply of the battery pack, refer to Figure 2 , Figure 3 and Figure 6 In this case, the fourth relay K4 is disconnected, which is equivalent to an open circuit. Figure 6 The circuit structure shown is Figure 1 The circuit structure shown is the same as that shown in the figure. The charging process of the battery pack is as described above. Figure 2 and Figure 3 The description is not repeated here.

[0148] In some embodiments, Fig.10 As shown, the charge and discharge circuit further includes a fifth relay K5, one end of the fifth relay K5 is connected to the first pole of the battery pack, and the other end of the fifth relay K5 is connected to the second end of the drive motor.

[0149] Exemplarily, when the charge-discharge circuit includes the first relay K1 and the fifth relay K5 , one end of the fifth relay K5 is connected to the second end of the drive motor and the common end of the first relay K1 .

[0150] In the case where the charge and discharge circuit includes the third relay K3 and the fifth relay K5 , one end of the fifth relay K5 is connected to the first pole of the battery pack and the common terminal of the third relay K3 .

[0151] In some embodiments, Fig.11 and Fig.12 As shown, when the battery pack is charged, the voltage provided by the charge and discharge ports is stepped down by the inverter circuit and the drive motor and then output to the battery pack.

[0152] Exemplarily, during the voltage reduction process, a switching frequency of at least one switching element among a plurality of switching elements included in the drive motor is determined according to a current value flowing through the second end of the drive motor.

[0153] When charging the battery pack through the charge and discharge circuit, the appropriate switching frequency is selected based on the value of the battery pack charging current, and the switching elements in the inverter circuit are controlled to operate at the selected switching frequency, so that the charge and discharge circuit can charge the battery pack with the charging power required to meet the set requirements, thereby improving the charging efficiency of the charge and discharge circuit and reducing the charging time of the battery pack.

[0154] In some embodiments, Fig.11 and Fig.12 As shown, during the voltage reduction process, the charge and discharge circuit includes switching between the fifth stage and the sixth stage.

[0155] like Fig.11 As shown, in the fifth stage, the fourth relay K4 and the fifth relay K5 are turned on, and the first switch element S1 / S3 / S5 of at least one phase bridge arm of the inverter circuit is turned on from the first end to the second end, so that the charging and discharging port, the fourth relay K4, at least one first switch element S1 / S3 / S5, the winding coil connected to the first switch element S1 / S3 / S5, the fifth relay K5, and the battery pack form a loop.

[0156] Fig.12 As shown, in the sixth stage, the fourth relay K4 is disconnected, the fifth relay K5 is turned on, and the second switch element S2 / S4 / S6 of at least one phase bridge arm of the inverter circuit is turned on from the second end to the first end, so that the winding coil, the fifth relay K5, the battery pack, and the second switch element S2 / S4 / S6 form a loop.

[0157] In this embodiment, in the fifth stage, in the multi-phase bridge arm of the inverter circuit, the second end to the first end of the first switch element S1 / S3 / S5 of at least one phase bridge arm is turned on. Fig.11 As shown, the second end to the first end of at least one of the first switch element S1 , the first switch element S3 and the first switch element S5 is conductive.

[0158] In the sixth stage, in the multi-phase bridge arm of the inverter circuit, the second end to the first end of the second switch element S2 / S4 / S6 of at least one phase bridge arm is turned on. Fig.12 As shown, the second end to the first end of at least one of the second switch element S2, the second switch element S4 and the second switch element S6 is conductive.

[0159] like Fig.11 and Fig.12 As shown, in the sixth stage, the winding coil is equivalent to a power supply supplying power to the charging and discharging port, and the output voltage of the winding coil is lower than the voltage of the battery pack, thereby reducing the voltage on the power supply side and realizing the voltage reduction discharge of the battery pack to the outside.

[0160] Moreover, in the fifth stage and the sixth stage, the switching frequency required to meet the set requirements can be selected in the efficiency mapping table according to the current flowing through the second end of the drive motor, and the switching elements participating in the fifth stage and the sixth stage (at least one of the first switching element S1 / S3 / S5 or the second switching element S2 / S4 / S6) can be operated at the switching frequency, thereby improving the energy storage efficiency of the energy storage process of the winding coil in the fifth stage and the discharge efficiency of the internal winding coil in the external discharge process in the sixth stage.

[0161] In some embodiments, Fig.13 and Fig.14 As shown, when the battery pack is discharging, the voltage output by the battery pack is boosted by the drive motor and the inverter circuit and then output to the charge and discharge port to power the device to be charged.

[0162] Exemplarily, during the voltage boost process, a switching frequency of at least one switching element among a plurality of switching elements included in the drive motor is determined according to a current value flowing through the second end of the drive motor.

[0163] When the battery pack is discharged through the charge and discharge circuit, a suitable switching frequency is selected based on the value of the battery pack charging current, and the switching elements in the inverter circuit are controlled to operate at the selected switching frequency, so that the battery pack can be discharged at the charging power required to meet the set requirements, thereby improving the discharge efficiency of the charge and discharge circuit.

[0164] In some embodiments, Fig.13 and Fig.14 As shown, during the boost process, the charge and discharge circuit includes switching between the seventh stage and the eighth stage.

[0165] like Fig.13As shown, in the seventh stage, the fourth relay K4 is disconnected, the fifth relay K5 is turned on, and the first end to the second end of the second switch element S2 / S4 / S6 of at least one phase bridge arm of the inverter circuit is turned on, so that the battery pack, the fifth relay K5, the winding coil, and the second switch element S2 / S4 / S6 connected to the winding coil form a loop.

[0166] like Fig.14 As shown, in the eighth stage, the fourth relay K4 and the fifth relay K5 are turned on, and the second end to the first end of the first switch element S1 / S3 / S5 of at least one phase bridge arm of the inverter circuit is turned on, so that the battery pack, the fifth relay K5, the winding coil, the first switch element S1 / S3 / S5 connected to the winding coil, the fourth relay K4, and the device to be charged form a loop.

[0167] In this embodiment, in the seventh stage, in the multi-phase bridge arm of the inverter circuit, the second end to the first end of the first switch element S1 / S3 / S5 of at least one phase bridge arm is turned on. Fig.13 As shown, the second end to the first end of at least one of the first switch element S1 , the first switch element S3 and the first switch element S5 is conductive.

[0168] In the eighth stage, in the multi-phase bridge arm of the inverter circuit, the second end to the first end of the second switch element S2 / S4 / S6 of at least one phase bridge arm is turned on. Fig.14 As shown, the second end to the first end of at least one of the second switch element S2, the second switch element S4 and the second switch element S6 is conductive.

[0169] like Fig.13 and Fig.14 As shown, in the eighth stage, the winding coil is equivalent to another power source connected in series with the battery pack, and the two jointly supply power to the charge and discharge port, thereby increasing the voltage on the power supply side and realizing the boost discharge of the battery pack to the outside.

[0170] Moreover, in the seventh stage and the eighth stage, the switching frequency required to meet the set requirements can be selected in the efficiency mapping table according to the current flowing through the second end of the drive motor, and the switching elements participating in the seventh stage and the eighth stage (at least one of the first switching element S1 / S3 / S5 or the second switching element S2 / S4 / S6) can be operated at the switching frequency, thereby improving the energy storage efficiency of the energy storage process of the winding coil in the seventh stage and the discharge efficiency of the internal winding coil in the external discharge process in the eighth stage.

[0171] Based on any of the above embodiments, in some embodiments, the switching frequency of at least one switching element is based on the current value of the second terminal of the driving motor, and the charging or discharging efficiency of the charging and discharging circuit meets the switching frequency required by the set requirement. The set requirement is that the charging or discharging efficiency is greater than or equal to the set value, or the charging or discharging efficiency is optimal.

[0172] In some embodiments, the switching frequency is selected from an efficiency mapping table, which is used to characterize the corresponding relationship between the current flowing through the second end of the drive motor and the switching frequency of at least one switching element when the charging or discharging efficiency of the charging and discharging circuit meets the set requirement. The set requirement is that the charging or discharging efficiency is greater than or equal to a set value, or the charging or discharging efficiency is optimal.

[0173] In some embodiments, when the external power source connected to the charging and discharging port matches the power source of the battery pack, such as Fig.15 As shown, in the charge and discharge circuit, the first relay K1 and the fifth relay K5 may be disconnected, the second relay K2, the third relay K3 and the fourth relay K4 may be turned on, the charge and discharge port and the battery pack form a loop, and the external power supply charges the battery pack through the charge and discharge port.

[0174] Based on this, in some embodiments, when the battery pack is discharged and the voltage of the battery pack matches the voltage of the charge and discharge port, as Fig.16 As shown, in the charge and discharge circuit, the first relay K1 and the fifth relay K5 may be disconnected, the second relay K2, the third relay K3 and the fourth relay K4 may be turned on, the charge and discharge port and the battery pack form a loop, and the battery pack discharges externally through the charge and discharge port.

[0175] In other embodiments, when the external power source connected to the charging and discharging port matches the power source of the battery pack, such as Fig.17 As shown, in the charge and discharge circuit, the third relay K3 and the fourth relay K4 may be disconnected, the first relay K1, the second relay K2 and the fifth relay K5 may be turned on, the charge and discharge port and the battery pack form a loop, and the external power supply charges the battery pack through the charge and discharge port.

[0176] Based on this, in other embodiments, when the battery pack is discharged and the voltage of the battery pack matches the voltage of the charge and discharge port, as Fig.18 As shown, in the charge and discharge circuit, the third relay K3 and the fourth relay K4 may be disconnected, the first relay K1, the second relay K2 and the fifth relay K5 may be turned on, the charge and discharge port and the battery pack form a loop, and the battery pack discharges externally through the charge and discharge port.

[0177] Fig.19The figure is a curve diagram showing the change of the charging / discharging current of the charging / discharging circuit as a function of the charging / discharging time according to an embodiment of the present invention.

[0178] Take charging the battery pack as an example. Fig.19 As shown, the process of charging the battery pack includes a charging start-up phase (pre-charging phase, such as Fig.19 0~t1 stage shown in), high current charging stage (such as Fig.19 t1~t2 stage shown in the figure) and the small current trickle charging stage (such as Fig.19 t2~t3 stage shown in ).

[0179] In the charging startup phase, the external power supply is connected to the charging and discharging port, and the charging and discharging circuit is connected and matched with the external power supply. In this phase, the battery pack is first charged with a small current. The charging matching process has high requirements for the output voltage ripple of the charging and discharging circuit. By looking up the efficiency mapping table, a higher switching frequency f1 is selected, and the switching elements of the inverter circuit that are turned on in this phase work at the switching frequency f1. By increasing the switching frequency, the charging ripple voltage and ripple current can be reduced, the matching success rate of the charging and discharging circuit and the external power supply can be improved, and the charging efficiency in the charging startup phase can also be improved.

[0180] In the high-current charging stage, after the charging and discharging circuit successfully matches the external power supply, the output current of the charging and discharging port gradually increases, and accordingly, the charging power also gradually increases. The higher switching frequency will cause the inverter circuit to generate more heat and cause over-temperature and other faults. Therefore, in the high-current charging stage, the efficiency mapping table is searched to use a lower switching frequency f2, and the switching elements of the inverter circuit that are turned on in this stage work at the switching frequency f2, so as to perform long-term high-current charging. In this way, while improving the charging efficiency, it can also avoid over-temperature and other faults during the charging process.

[0181] In the small current trickle charging stage, when the battery pack SOC (State Of Charge) reaches a higher level (for example, greater than or equal to 95%, this value is only an example and is not a limitation of the present application. It can be adaptively designed as needed), in order to protect the battery pack and avoid overcharging of the battery pack, it will enter the small current trickle charging stage. In this stage, a higher switching frequency f3 is adopted by looking up the switching frequency efficiency mapping table, and the switching elements of the inverter circuit that are turned on in this stage operate at the switching frequency f3, thereby improving the charging efficiency.

[0182] In this way, the charging and discharging circuit of the present application can select an appropriate switching frequency for the switching element of the inverter circuit based on the current charging current of the charging and discharging circuit through an efficiency mapping table, thereby improving the matching success rate between the charging and discharging circuit and the external power supply during the charging startup phase.

[0183] During the entire charging process, whether in the process of connecting and matching the charging and discharging circuit with the external power supply or in the subsequent process, the charging and discharging system can be charged with the charging power required to meet the set requirements, so as to improve the charging efficiency of the charging and discharging system.

[0184] Correspondingly, the charging and discharging system of the present application can also select a suitable switching frequency for the switching elements of the inverter circuit based on the current discharge current through the efficiency mapping table during the process of the battery pack discharging. This allows the charging and discharging system to discharge at a discharge power that meets the set requirements during the entire discharge process, thereby improving the discharge efficiency of the charging and discharging system.

[0185] Fig. 20 This is an efficiency mapping table of the charging and discharging system of some embodiments of the present application.

[0186] Combinations of different charging or discharging currents and different switching frequencies can obtain different charging or discharging efficiencies. In the efficiency mapping table of the switching frequency, the charging or discharging efficiencies corresponding to different combinations of charging or discharging currents and switching frequencies can be obtained through offline calibration.

[0187] For example, on a charge and discharge circuit test bench, according to Fig. 20 Under the working conditions shown, the charging or discharging efficiency under different charging or discharging currents and switching frequencies is tested and recorded in a table. When the charging or discharging circuit is charging or discharging, the switching frequency corresponding to the optimal efficiency can be found through the table for charging or discharging.

[0188] In any of the aforementioned embodiments, during the charging or discharging process of the battery pack, at least one phase bridge arm among the multi-phase bridge arms of the inverter circuit participates in the charging or discharging process, and the first switching element S1 / S3 / S5 and the second switching element S2 / S4 / S6 of the bridge arm participating in the charging or discharging process are alternately turned on and off.

[0189] For example, in the high-current charging stage, the three-phase bridge arm of the inverter circuit can be used to work together, and in the low-current charging stage (charging startup stage or low-current trickle charging stage), only one-phase bridge arm or two-phase bridge arm of the inverter circuit can be used to work, which can increase the equivalent inductance of the winding coil of the drive motor and further improve the low-current charging efficiency.

[0190] It should be noted that the inverter circuit is not limited to the above-mentioned three-phase inverter circuit, but can also be a four-phase inverter circuit, a five-phase inverter circuit, etc., which is not limited here. Similarly, the above-mentioned motor is not limited to the above-mentioned three-phase motor, but can also be a four-phase motor, a five-phase motor, etc., which is not limited here.

[0191] Based on any of the above embodiments, in the charging and discharging systems of some embodiments, when charging the battery pack, the controller determines the duty cycle of the pulse width modulation signal according to the voltage difference between the battery pack and the charging and discharging port, and determines the switching frequency of at least one switching element among the multiple switching elements according to the current flowing through the second end of the drive motor; and outputs a pulse width modulation signal to at least one switching element according to the determined duty cycle and switching frequency.

[0192] Based on the above embodiments, in the charging and discharging systems of some embodiments, the controller is electrically connected to the control ends of the plurality of switch elements of the inverter circuit.

[0193] In some embodiments, the controller is configured to output a pulse width modulation signal to at least one switching element among the plurality of switching elements of the inverter circuit to adjust a switching frequency of the at least one switching element.

[0194] Exemplarily, the controller is further configured to determine a duty cycle of the pulse width modulation signal according to a voltage difference between the battery pack and the charge and discharge port, and output the pulse width modulation signal to at least one switching element according to the determined duty cycle and switching frequency.

[0195] The charging and discharging system provided in some embodiments of the present application can adjust the duty cycle of the switching element of the inverter circuit according to the voltage difference between the battery pack and the charging and discharging port, so as to match and adjust the voltage between the battery pack and the charging and discharging port, so that the voltage difference between the battery pack and the charging and discharging port satisfies the charging or discharging conditions of the battery pack.

[0196] In addition, the charging and discharging circuit can also select the optimal switching frequency according to the charging or discharging current between the battery pack and the charging and discharging port in combination with the efficiency mapping table, and adjust the switching elements of the inverter circuit to operate at the determined switching frequency, thereby improving the charging or discharging power of the battery pack, and then improving the charging or discharging efficiency of the battery pack.

[0197] In some embodiments, the controller is configured to determine the switching frequency of at least one of the plurality of switching elements according to the charging current flowing through the second terminal of the drive motor when charging the battery pack. The controller is also configured to determine the switching frequency of at least one of the plurality of switching elements according to the discharging current flowing through the second terminal of the drive motor when discharging the battery pack.

[0198] In the charging and discharging circuit of the present application, the on-off control of the switching elements in the inverter circuit is achieved through pulse width modulation signals, so that the battery pack, inverter circuit, drive motor and charging and discharging port can form different charging or discharging circuits, thereby adjusting the voltage matching of the battery pack and the charging and discharging port, and adjusting the voltage difference between the battery pack and the charging and discharging port to within the adaptation range.

[0199] The current flowing through the second end of the drive motor is called the charging or discharging current of the charging and discharging circuit. When the charging and discharging circuit charges the battery pack, or the battery pack discharges to the outside through the charging and discharging circuit, the controller selects the corresponding switching frequency based on the value of the charging or discharging current, so that the charging and discharging circuit can charge or discharge at the charging power required to meet the set requirements, thereby improving the charging or discharging efficiency of the charging and discharging circuit and reducing the charging or discharging time of the charging and discharging circuit.

[0200] The present application also provides a control method for a charge and discharge circuit.

[0201] In some embodiments, the charge and discharge circuit includes: an inverter circuit, the inverter circuit includes a plurality of switch elements; during the charging or discharging process of the battery pack, the inverter circuit is electrically connected between the battery pack and the charge and discharge port. The control method of the charge and discharge circuit includes:

[0202] A1. During the process of charging or discharging the battery pack, the duty cycle of the pulse width modulation signal is determined according to the voltage difference between the battery pack and the charging and discharging port.

[0203] A2. Determine a switching frequency of at least one switching element among the plurality of switching elements according to the current flowing through the second end of the drive motor.

[0204] A3. Output a pulse width modulation signal to at least one switching element according to the determined duty cycle and switching frequency.

[0205] The control method of the charge-discharge circuit can be used to control the charge-discharge circuit provided by any of the above embodiments. The specific control process and beneficial effects refer to the description of the working process and beneficial effects of the charge-discharge system above, which will not be repeated here.

[0206] In the description of this specification, specific features, structures or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0207] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A charging and discharging circuit, characterized in that: include: Inverter circuit; The first end of the inverter circuit is electrically connected to the first pole of the battery pack, and the second end of the inverter circuit is electrically connected to the second pole of the battery pack; the inverter circuit includes a plurality of switch elements; a drive motor; a first end of the drive motor is electrically connected to a third end of the inverter circuit; a second end of the drive motor is electrically connected to a first end of a charge and discharge port, and a second end of the charge and discharge port is electrically connected to a second pole of the battery pack and a second end of the inverter circuit; Among them, the switching frequency of at least one switching element among the multiple switching elements is determined according to the current value flowing through the second end of the drive motor; the switching frequency is selected from an efficiency mapping table, and the efficiency mapping table is used to characterize the correspondence between the current flowing through the second end of the drive motor and the switching frequency of the at least one switching element when the charging or discharging efficiency of the charging and discharging circuit meets the set requirements; the set requirements are that the charging or discharging efficiency is greater than or equal to the set value, or the charging or discharging efficiency is optimal.

2. The charge and discharge circuit according to claim 1, characterized in that: The inverter circuit comprises multi-phase bridge arms connected in parallel, and each phase of the bridge arm is electrically connected between a first end and a second end of the inverter circuit; The bridge arm of each phase includes a first switch element and a second switch element, and the plurality of switch elements include the first switch element and the second switch element; the first end of the first switch element is electrically connected to the first end of the inverter circuit, the second end of the first switch element is electrically connected to the first end of the second switch element, and the second end of the second switch element is electrically connected to the second end of the inverter circuit; the common terminal of a first switch element and a second switch element is a third terminal of the inverter circuit; The drive motor includes multiple groups of winding coils, a first end of one group of the winding coils is connected to the common end of the first switching element and the second switching element of one phase of the bridge arm, and a second end of one group of the winding coils is electrically connected to the second end of the drive motor.

3. The charge and discharge circuit according to claim 2, characterized in that: When the battery pack is charged, the voltage provided by the charge and discharge port is boosted by the inverter circuit and the drive motor and then output to the battery pack.

4. The charge and discharge circuit according to claim 3, characterized in that: During the boost process, the charge and discharge circuit includes switching between a first stage and a second stage; In the first stage, the second switch element of at least one phase bridge arm of the inverter circuit is turned on from the first end to the second end, so that the charging and discharging port, the winding coil, and the second switch element electrically connected to the winding coil form a loop; In the second stage, the first switching element of the at least one phase bridge arm of the inverter circuit is turned on from the second end to the first end, so that the charging and discharging port, the winding coil, the first switching element electrically connected to the winding coil, and the battery pack form a loop.

5. The charge and discharge circuit according to any one of claims 1 to 4, characterized in that: The charging and discharging circuit further includes: a first relay and a second relay; The first relay is electrically connected between the second end of the drive motor and the first end of the charge and discharge port; The second relay is electrically connected between the second pole of the battery pack and the second end of the charge and discharge port.

6. The charge and discharge circuit according to claim 5, characterized in that: The first end of the inverter circuit is also electrically connected to the first end of the charge and discharge port; The charging and discharging circuit further includes: a third relay; one end of the third relay is electrically connected to the first pole of the battery pack, and the other end of the third relay is electrically connected to the first end of the inverter circuit.

7. The charge and discharge circuit according to claim 6, characterized in that: When the battery pack is discharging externally, the voltage output by the battery pack is stepped down by the inverter circuit and the drive motor and then output to the charge and discharge port to supply power to the device to be charged.

8. The charge and discharge circuit according to claim 7, characterized in that: During the voltage reduction process, the charge and discharge circuit includes switching between a third stage and a fourth stage; In the third stage, the third relay is turned on, the first end to the second end of the first switch element of at least one phase bridge arm of the inverter circuit is turned on, and the battery pack, the third relay, the first switch element, the drive motor, and the device to be charged form a loop; In the fourth stage, the third relay is disconnected, the second end to the first end of the second switch element of at least one phase bridge arm of the inverter circuit is turned on, and the drive motor, the device to be charged, and the second switch element form a loop.

9. The charge and discharge circuit according to claim 2, characterized in that: The charging and discharging circuit further includes: a fourth relay; one end of the fourth relay is electrically connected to the first pole of the battery pack, and the other end of the fourth relay is electrically connected to the first end of the charging and discharging port.

10. The charge and discharge circuit according to claim 9, characterized in that: The charging and discharging circuit further includes: a first relay, the first relay being electrically connected between the second end of the driving motor and the first end of the charging and discharging port; When an external power source is connected to the charge and discharge port to charge the battery pack, if the voltage of the charge and discharge port is greater than or equal to the voltage of the battery pack, the fourth relay is turned on, or the first relay and the fourth relay are both turned on; when the external power source is connected to the charge and discharge port to charge the battery pack, if the voltage of the charge and discharge port is less than the voltage of the battery pack, the first relay is turned on.

11. The charge and discharge circuit according to claim 9 or 10, characterized in that: The charging and discharging circuit further includes: a fifth relay; one end of the fifth relay is connected to the first pole of the battery pack, and the other end of the fifth relay is connected to the second end of the driving motor.

12. The charge and discharge circuit according to claim 11, characterized in that: When the battery pack is charged, the voltage provided by the charge and discharge port is stepped down by the inverter circuit and the drive motor and then output to the battery pack.

13. The charge and discharge circuit according to claim 12, characterized in that: During the voltage reduction process, the charge and discharge circuit includes switching between a fifth stage and a sixth stage; In the fifth stage, the fourth relay and the fifth relay are turned on, and the first switch element of at least one phase bridge arm of the inverter circuit is turned on from the first end to the second end, so that the charge and discharge port, the fourth relay, at least one of the first switch elements, the winding coil connected to the first switch element, the fifth relay, and the battery pack form a loop; In the sixth stage, the fourth relay is disconnected, the fifth relay is turned on, and the second switching element of at least one phase bridge arm of the inverter circuit is turned on from the second end to the first end, so that the winding coil, the fifth relay, the battery pack, and the second switching element form a loop.

14. The charge and discharge circuit according to claim 11, characterized in that: When the battery pack is discharging externally, the voltage output by the battery pack is boosted by the drive motor and the inverter circuit and then output to the charge and discharge port to supply power to the device to be charged.

15. The charge and discharge circuit according to claim 14, characterized in that: During the boosting process, the charge and discharge circuit includes switching between a seventh stage and an eighth stage; In the seventh stage, the fourth relay is disconnected, the fifth relay is turned on, and the first end to the second end of the second switch element of at least one phase bridge arm of the inverter circuit is turned on, so that the battery pack, the fifth relay, the winding coil, and the second switch element connected to the winding coil form a loop; In the eighth stage, the fourth relay and the fifth relay are turned on, and the second end to the first end of the first switch element of at least one phase bridge arm of the inverter circuit is turned on, so that the battery pack, the fifth relay, the winding coil, the first switch element connected to the winding coil, the fourth relay, and the device to be charged form a loop.

16. A charging and discharging system, characterized in that: comprising a charge and discharge circuit as claimed in any one of claims 1 to 15; and A controller electrically connected to control terminals of a plurality of switch elements of the inverter circuit; The controller is configured to output a pulse width modulation signal to the at least one switching element to adjust a switching frequency of the at least one switching element.

17. The charging and discharging system according to claim 16, characterized in that: The controller is further configured to, when charging the battery pack, determine a switching frequency of at least one of the plurality of switching elements according to a charging current flowing through the second end of the drive motor; and / or The controller is further configured to determine a switching frequency of at least one of the plurality of switching elements according to a discharge current flowing through a second end of the drive motor when the battery pack is discharged.

18. A means of transport, characterized in that: Comprising the charging and discharging system as claimed in claim 16 or 17.

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