Charging and discharging circuit, charging and discharging system, and vehicle

Abstract

A charging and discharging circuit, a charging and discharging system, and a vehicle. The charging and discharging circuit comprises an inverter circuit and a drive electric motor. A first end of the inverter circuit is connected to a first electrode of a battery pack, and a second end of the inverter circuit is connected to a second electrode of the battery pack. The inverter circuit comprises a plurality of switch elements. A first end of the drive electric motor is connected to a third end of the inverter circuit, and a second end of the drive electric motor is electrically connected to a first end of a charging and discharging port. A second end of the charging and discharging port is electrically connected to the second electrode of the battery pack and the second end of the inverter circuit. The switching frequency of at least one switch element among the plurality of switch elements is determined on the basis of the value of a current flowing through the second end of the drive electric motor.

Description

Charging and discharging circuit, charging and discharging system and vehicle

[0001] The present application claims priority to the Chinese patent application No. 202411071258.0, filed on August 6, 2024, the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present disclosure 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

[0003] With the increasing number of electric vehicles in the market, the charging efficiency of the vehicle is one of the reference items for consumers when purchasing a vehicle. SUMMARY

[0004] The present disclosure provides a charging and discharging circuit, a charging and discharging system and a vehicle.

[0005] In a first aspect, a charging and discharging circuit is provided. The charging and discharging circuit includes an inverter circuit and a drive motor. A first end of the inverter circuit is electrically connected to a first pole of a battery pack, and a second end of the inverter circuit is electrically connected to a second pole of the battery pack. The inverter circuit includes a plurality of switching elements. 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 charging and discharging port, and a 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. A switching frequency of at least one switching element of the plurality of switching elements is determined according to a current value flowing through the second end of the drive motor.

[0006] The charging and discharging circuit provided by some embodiments of the present disclosure 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 work 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 by the battery pack during charging or discharging.

[0007] In some embodiments, the switching frequency of the at least one switching element is based on the current value of the second end of the drive motor and the switching frequency required for the charging or discharging efficiency of the charging and discharging circuit to meet the set requirement.

[0008] In some embodiments, the switching frequency is selected from an efficiency mapping table. The efficiency mapping table is used to represent the corresponding relationship 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 requirement.

[0009] 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 maximum.

[0010] In some embodiments, the inverter circuit comprises a plurality of phase legs connected in parallel, each phase leg of the plurality of phase legs being electrically connected between the first end and the second end of the inverter circuit.

[0011] Each phase leg comprises a first switching element and a second switching element, the plurality of switching elements comprising the first switching element and the second switching element. A first end of the first switching element is electrically connected to the first end of the inverter circuit, a second end of the first switching element is electrically connected to a first end of the second switching element, and a second end of the second switching element is electrically connected to the second end of the inverter circuit. A common connection of one first switching element and one second switching element is a third end of the inverter circuit.

[0012] The drive motor comprises a plurality of sets of winding coils. A first end of a set of winding coils of the plurality of sets of winding coils is connected to the common connection of the first switching element and the second switching element of a phase leg of the plurality of phase legs, and a second end of the set of winding coils is connected to a second end of the drive motor.

[0013] In some embodiments, in a case of charging the battery pack, the voltage provided by the charge-discharge port is boosted by the inverter circuit and the drive motor and then output to the battery pack.

[0014] In some embodiments, during the boosting, the charge-discharge circuit is capable of switching between a first phase and a second phase.

[0015] In the first phase, the first end to the second end of the second switching element of at least one phase leg of the inverter circuit is turned on, so that a loop is formed by the charge-discharge port, the winding coils, and the second switching element electrically connected to the winding coils.

[0016] In the second phase, the second end to the first end of the first switching element of at least one phase leg of the inverter circuit is turned on, so that a loop is formed by the charge-discharge port, the winding coils, the first switching element electrically connected to the winding coils, and the battery pack.

[0017] In some embodiments, the charge-discharge circuit further comprises 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-discharge port, and the second relay is electrically connected between the second pole of the battery pack and the second end of the charge-discharge port.

[0018] In some embodiments, the first end of the inverter circuit is also electrically connected to the first end of the charge-discharge port. The charge-discharge system further comprises a third relay. A first end of the third relay is electrically connected to the first pole of the battery pack, and a second end of the third relay is electrically connected to the first end of the inverter circuit.

[0019] In some embodiments, in the case of discharging the battery pack to the outside, the voltage output by the battery pack is stepped down by the inverter circuit and the driving motor, and then output to the charging and discharging port to supply power to the device to be charged.

[0020] In some embodiments, during the voltage step-down process, the charging and discharging circuit can switch between the third stage and the fourth stage.

[0021] In the third stage, the third relay is turned on, the first end to the second end of the first switching element of at least one phase bridge arm of the inverter circuit is turned on, and the battery pack, the third relay, the first switching element, the driving motor, and the device to be charged form a loop.

[0022] In the fourth stage, the third relay is turned off, the second end to the first end of the second switching element of at least one phase bridge arm of the inverter circuit is turned on, and the driving motor, the device to be charged, and the second switching element form a loop.

[0023] In some embodiments, the charging and discharging circuit further comprises a fourth relay, the first end of the fourth relay is electrically connected to the first pole of the battery pack, and the second end of the fourth relay is electrically connected to the first end of the charging and discharging port.

[0024] In some embodiments, the charging and discharging circuit further comprises a first relay, which is electrically connected between the second end of the driving motor and the first end of the charging and discharging port. In the case of charging the battery pack by connecting an external power source to the charging and discharging port, if it is determined that the voltage of the charging and discharging 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.

[0025] In the case of charging the battery pack by connecting an external power source to the charging and discharging port, if it is determined that the voltage of the charging and discharging port is less than the voltage of the battery pack, the first relay is turned on.

[0026] In some embodiments, the charging and discharging circuit further comprises a fifth relay. The first end of the fifth relay is connected to the first pole of the battery pack, and the second end of the fifth relay is connected to the second end of the driving motor.

[0027] In some embodiments, in the case of charging the battery pack, the voltage provided by the charging and discharging port is stepped down by the inverter circuit and the driving motor, and then output to the battery pack.

[0028] In some embodiments, during the voltage step-down process, the charging and discharging circuit can switch between the fifth stage and the sixth stage.

[0029] In the fifth stage, the fourth relay and the fifth relay are turned on, the first end to the second end of the first switching element of at least one phase bridge arm of the inverter circuit is turned on, and the charging and discharging port, the fourth relay, the first switching element, the winding coil connected to the first switching element, the fifth relay, and the battery pack form a loop.

[0030] In the sixth stage, the fourth relay is turned off, the fifth relay is turned on, the second end to the first end of the second switching element of the at least one phase bridge arm of the inverter circuit is turned on, so that the winding coil, the fifth relay, the battery pack, and the second switching element form a loop.

[0031] In some embodiments, in the case of discharging the battery pack to the outside, the voltage output by the battery pack is boosted through the driving motor and the inverter circuit, and then output to the charge-discharge port to supply power to the device to be charged.

[0032] In some embodiments, during the boosting process, the charge-discharge circuit can switch between the seventh stage and the eighth stage.

[0033] In the seventh stage, the fourth relay is turned off, the fifth relay is turned on, the first end to the second end of the second switching element of the 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.

[0034] In the eighth stage, the fourth relay and the fifth relay are turned on, the second end to the first end of the first switching element of the 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.

[0035] In a second aspect, a charge-discharge system is provided. The charge-discharge system includes the charge-discharge circuit and the controller described above. The controller is electrically connected to the control ends of the 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.

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

[0037] In some embodiments, the controller is further configured to determine the switching frequency of at least one switching element in the plurality of switching elements according to the discharging current flowing through the second end of the driving motor when discharging the battery pack.

[0038] The charge-discharge system described above has the same structure and beneficial technical effects as the charge-discharge circuit described above, and will not be repeated here.

[0039] In a third aspect, a vehicle is provided. The vehicle includes the charge-discharge system described above.

[0040] The vehicle described above has the same structure and beneficial technical effects as the charge-discharge circuit described above, and will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings needed to be used in the embodiments will be briefly introduced below. However, the drawings in the following description are only some embodiments of the present disclosure, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0042] FIG. 1 is a circuit structure topology diagram of a charge-discharge circuit according to some embodiments;

[0043] FIG. 2 is a current flow diagram of the charge-discharge circuit shown in FIG. 1 in a first stage;

[0044] FIG. 3 is a current flow diagram of the charge-discharge circuit shown in FIG. 1 in a second stage;

[0045] FIG. 4 is a current flow diagram of the charge-discharge circuit shown in FIG. 1 in a third stage;

[0046] FIG. 5 is a current flow diagram of the charge-discharge circuit shown in FIG. 1 in a fourth stage;

[0047] FIG. 6 is a circuit structure topology diagram of another charge-discharge circuit according to some embodiments;

[0048] FIG. 7 is a current flow diagram of the charge-discharge circuit shown in FIG. 6 in a process of charging a battery pack;

[0049] FIG. 8 is another current flow diagram of the charge-discharge circuit shown in FIG. 6 in the process of charging the battery pack;

[0050] FIG. 9 is a current flow diagram of the charge-discharge circuit shown in FIG. 6 in a process of discharging the battery pack;

[0051] FIG. 10 is a circuit structure topology diagram of yet another charge-discharge circuit according to some embodiments;

[0052] FIG. 11 is a current flow diagram of the charge-discharge circuit shown in FIG. 10 in a fifth stage;

[0053] FIG. 12 is a current flow diagram of the charge-discharge circuit shown in FIG. 10 in a sixth stage;

[0054] FIG. 13 is a current flow diagram of the charge-discharge circuit shown in FIG. 10 in a seventh stage;

[0055] FIG. 14 is a current flow diagram of the charge-discharge circuit shown in FIG. 10 in an eighth stage;

[0056] FIG. 15 is a current flow diagram of the charge-discharge circuit shown in FIG. 10 in a process of charging the battery pack;

[0057] FIG. 16 is a current flow diagram of the charge and discharge circuit shown in FIG. 10 during a battery pack discharge process;

[0058] FIG. 17 is another current flow diagram of the charge and discharge circuit shown in FIG. 10 during a battery pack charging process;

[0059] FIG. 18 is another current flow diagram of the charge and discharge circuit shown in FIG. 10 during a battery pack discharge process;

[0060] FIG. 19 is a graph of the charging current of the charge and discharge circuit during a battery pack charging process according to some embodiments. DETAILED DESCRIPTION

[0061] The technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the drawings in the embodiments of the present disclosure. However, the described embodiments are only some of the embodiments of the present disclosure, not all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present disclosure.

[0062] In the description of the present disclosure, it should be understood that the terms "upper", "lower", "left", "right", "front", "back", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings based on the orientation or relative position shown in the drawings, and are only for the purpose of facilitating the description of the present disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present disclosure. Unless otherwise specified, the above orientation description can be flexibly arranged in the actual application process under the condition of meeting the relative position relationship shown in the drawings.

[0063] The terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present disclosure, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0064] In the description of the present disclosure, it should be noted that, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection", "communication" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected. It can be directly connected, or indirectly connected through an intermediate medium, or the communication between the two elements inside. For those skilled in the art, the specific meaning of the above terms in the present disclosure can be understood according to the specific circumstances.

[0065] In embodiments of the present disclosure, the terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the presence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0066] In embodiments of the present disclosure, the word "exemplary" or "for example" is used to mean serving as an example, instance, or illustration. Any implementation or design solution described as "exemplary" or "for example" in embodiments of the present disclosure is not necessarily to be construed as preferred or advantageous over other implementations or design solutions.

[0067] "at least one of A, B, and C" has the same meaning as "at least one of A, B, or C" and includes the following combinations: only A, only B, only C, a combination of A and B, a combination of A and C, a combination of B and C, and a combination of A, B, and C.

[0068] Some embodiments of the present disclosure provide a vehicle. The vehicle includes a charging and discharging system.

[0069] The vehicle described in some embodiments of the present disclosure includes, but is not limited to, a vehicle, an airplane, or a ship, etc., and the vehicle has a charging and discharging system.

[0070] The following describes some embodiments of the present disclosure by taking a vehicle as an example.

[0071] In some embodiments, the 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.

[0072] The battery pack is charged or discharged through the charging and discharging system. The battery pack is electrically connected with a load, and the battery pack is configured to provide electric energy to the load electrically connected with the battery pack.

[0073] For example, the battery pack can include one or more power batteries, and a plurality of (two or more) power batteries are connected in sequence to form a power battery pack.

[0074] In some embodiments, as shown in FIG. 1, the load includes a drive motor, and the drive motor is electrically connected with the battery pack. The drive motor is configured to convert the electric energy provided by the battery pack into driving force to drive the vehicle to travel.

[0075] The battery pack is a direct current voltage source. In the case that the driving motor is an alternating current driving motor, the electric energy provided by the battery pack needs to be converted first, and the direct current is converted into alternating current before being provided to the driving motor.

[0076] Based on this, as shown in FIG. 1, in some embodiments, the charging and discharging circuit further includes an inverter circuit.

[0077] The inverter circuit includes a plurality of phase bridge arms connected in parallel, and each phase bridge arm is electrically connected between the first end and the second end of the inverter circuit. Each phase bridge arm includes a first switching element S1, S3, S5 (for example, the switching elements S1, S3, S5 shown in FIG. 1 are all first switching elements) and a second switching element S2, S4, S6 (for example, the switching elements S2, S4, S6 shown in FIG. 1 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.

[0078] In the case that the driving motor is an alternating current driving motor, the inverter circuit is configured to convert the direct current provided by the battery pack into alternating current, and transmit the converted alternating current to the driving motor.

[0079] In some embodiments, as shown in FIG. 1, the inverter circuit includes a plurality of switching elements (for example, the switching elements S1 to S6 shown in FIG. 1). The plurality of switching elements includes a plurality of first switching elements S1, S3, S5 and a plurality of second switching elements S2, S4, S6. The inverter circuit includes a plurality of phase bridge arms, and one phase bridge arm includes one first switching element S1, S3, S5 and one second switching element S2, S4, S6 connected in series.

[0080] As shown in FIG. 1, 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 corresponding 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. The common connection end of the first switching element S1, S3, S5 and the second switching element S2, S4, S6 of one phase bridge arm of the inverter circuit is a third end of the inverter circuit.

[0081] For example, the inverter circuit can be an inverter. The driving motor can be a three-phase driving motor, and the inverter circuit can be a three-phase inverter. The following describes some embodiments of the present disclosure by taking the driving motor as a three-phase driving motor and the inverter circuit as a three-phase inverter.

[0082] In some embodiments, as shown in FIG. 1, the driving motor includes a plurality of groups of winding coils. A first end of a group of winding coils of the driving motor is electrically connected to the common terminals 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 the group of winding coils is electrically connected to the second end of the driving motor.

[0083] The common terminals of a first switching element S1, S3, S5 and a second switching element S2, S4, S6 are a third end of the inverter circuit.

[0084] For example, the driving motor includes three groups of winding coils, and the inverter circuit includes three phase bridge arms. As shown in FIG. 1, the driving 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.

[0085] The first bridge arm of the inverter circuit includes a first switching element S1 and a second switching element S2, and a first end of the first winding coil L1 of the driving motor is electrically connected between the first switching element S1 and the second switching element S2.

[0086] The second bridge arm of the inverter circuit includes a first switching element S3 and a second switching element S4, and a first end of the second winding coil L2 of the driving motor is electrically connected between the first switching element S3 and the second switching element S4.

[0087] The third bridge arm of the inverter circuit includes a first switching element S5 and a second switching element S6, and the third winding coil L3 of the driving motor is electrically connected between the first switching element S5 and the second switching element S6.

[0088] In some embodiments, a switching element can include a Metal-Oxide-Semiconductor Field-Effect Transistor (MOS), or a switching element can also include a transistor and a diode in parallel.

[0089] In the case where a switching element includes a MOS, a first pole of the MOS included in a first switching element is connected to the first end of the inverter circuit, a second pole of the MOS included in the first switching element is connected to a first pole of the MOS included in a second switching element, and a second pole of the MOS included in the second switching element is connected to the second end of the inverter circuit. The common terminals of the MOS included in the first switching element and the MOS included in the second switching element are a third end of the inverter circuit.

[0090] 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.

[0091] 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.

[0092] In the case where one switch element includes one transistor and one diode in parallel, as shown in FIG. 1, the first end of the diode is electrically connected to the second end of the transistor, and 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.

[0093] When the transistor is on, the first end to the second end of the transistor is on, and in other cases, the transistor is considered to be open; the first end to the second end of the diode is on, and the second end to the first end of the diode is 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 Insulated Gate Bipolar Transistor (IGBT).

[0094] In some embodiments, the charge-discharge system further includes a controller electrically connected to the control end of the plurality of switch elements of the inverter circuit. By controlling the on-off of the transistor and the diode, the conduction direction of the switch element can be controlled. When the transistor is on and the diode is off, the first end to the second end of the switch element is on; when the transistor is off and the diode is on, the second end to the first end of the switch element is on.

[0095] During vehicle driving, the inverter circuit can convert the direct current power provided by the battery pack into power and provide it to the drive motor to drive the drive motor to work. The electrical energy that the battery pack can store is limited. Based on this, the battery pack can also be electrically connected to the charge-discharge port, and electrical energy can be transmitted to the battery pack through the charge-discharge port to charge the battery pack.

[0096] In some embodiments, as shown in FIG. 1, the first end of the charge-discharge circuit is connected to the battery pack, and the second end of the charge-discharge circuit is connected to the charge-discharge port. The electrical energy transmission between the battery pack and the charge-discharge port is carried out through the charge-discharge circuit, and the electrical energy transmission between the battery pack and the charge-discharge port can be that the external power source charges the battery pack through the charge-discharge port, or that the battery discharges externally to the charge-discharge port.

[0097] For example, in the case that the external power source accesses the charge-discharge port, the external power source charges the battery pack. The external power source can be a direct current power source, for example, a direct current charging pile or a direct current energy storage power source (for example, a mobile charging vehicle, an energy storage device, and a battery pack in another vehicle, etc.).

[0098] In the case that the battery discharges externally by accessing the charge-discharge port, the charge-discharge port can be connected with a direct current charging pile, can be connected with a direct current energy storage power source, or can be connected with an external load.

[0099] In the case that the battery pack is charged or the battery pack discharges externally, in the case that the voltage of the battery pack and the voltage of the charge-discharge port are not matched, for example, in the case that the difference between the voltage of the battery pack and the voltage of the charge-discharge port is not within a set range, a voltage adjustment circuit needs to be arranged between the battery pack and the charge-discharge port to adjust the voltage of the battery pack or the voltage of the charge-discharge port, so that the voltage of the battery pack or the voltage of the charge-discharge port is matched.

[0100] Some cases in which the voltage of the battery pack and the voltage of the charge-discharge port are not matched are described below.

[0101] 1. The battery pack is charged, and the voltage of the charge-discharge port is less than or equal to the voltage of the battery pack.

[0102] 2. The battery pack is charged, and the voltage of the charge-discharge port is greater than the voltage of the battery pack, and the difference between the voltages of the two is greater than a set range.

[0103] 3. The battery pack discharges externally, and the voltage of the battery pack is less than or equal to the voltage of the charge-discharge port.

[0104] 4. The battery pack discharges externally, and the voltage of the battery pack is greater than the voltage of the charge-discharge port, and the difference between the voltages of the two is greater than a set range.

[0105] Taking the charging of the battery pack by the direct current 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-discharge port is 400V. In this case, the power supply voltage of the charge-discharge port is lower than the rated voltage of the battery pack, therefore, the charge-discharge port cannot directly supply power to the battery pack to charge the battery pack, and the 400V power supply voltage provided by the charge-discharge port needs to be boosted to 800V, and the boosted 800V power supply voltage is provided to the battery pack to charge the battery pack.

[0106] In order to enable the vehicle to match different charging piles, a boost conversion device can be arranged in the vehicle. However, the greater the boost voltage difference (voltage difference before and after boost) that can be achieved by the boost conversion device, the greater the weight and volume of the boost conversion device, and the higher the price, which will cause the weight of the vehicle to increase, and the space in the vehicle that needs to be reserved for the boost conversion device will also be larger, which will compress the space of the vehicle and cause the cost of the vehicle to rise.

[0107] Based on this, some embodiments of the present disclosure provide a charge-discharge circuit. The charge-discharge circuit can utilize the inverter circuit and the driving motor of the vehicle to achieve voltage matching adjustment between the battery pack and the charge-discharge port.

[0108] In some embodiments, as shown in FIG. 1, the charge-discharge circuit further includes a first relay K1 and a second relay K2. The first relay K1 is electrically connected between the second end of the driving motor and the first end of the charge-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-discharge port.

[0109] In some embodiments, as shown in FIG. 1, the charge-discharge circuit further includes a first capacitor C1. The first end of the first capacitor C1 is connected to the common connection end of the first relay K1 and the first end of the charge-discharge port, and the second end of the first capacitor C1 is connected to the second end of the charge-discharge port. In the case of charging the battery pack or discharging the battery pack to the outside, the first capacitor C1 is connected in parallel across the charge-discharge port.

[0110] By arranging the first capacitor C1, the current provided by the charge-discharge port can be filtered, and the influence of the ripple current in the current provided by the charge-discharge port on the charge-discharge circuit can be reduced.

[0111] In some embodiments, as shown in FIG. 1, the first end of the inverter circuit is also electrically connected to the first end of the charge-discharge port. The charge-discharge circuit further includes a third relay K3. The first end of the third relay K3 is electrically connected to the first pole of the battery pack, and the second end of the third relay K3 is electrically connected to the first end of the inverter circuit.

[0112] In some embodiments, as shown in FIG. 1, the charge-discharge circuit further includes a second capacitor C2. The first end of the second capacitor C2 is connected to the common connection end of the third relay K3 and the first end of the inverter circuit, and the second end of the second capacitor C2 is connected to the second pole of the battery pack. In the case of charging the battery pack or discharging the battery pack to the outside, the second capacitor C2 is connected in parallel across the battery pack.

[0113] The second capacitor C2 has good voltage balancing characteristics. By connecting the second capacitor C2 in parallel across the battery pack, in the case where the battery pack includes a plurality of power batteries, voltage distribution can be formed among the plurality of power batteries within the battery pack, battery voltage balancing is achieved, and the voltage of each power battery within the battery pack is ensured to be balanced.

[0114] In addition, the second capacitor C2 connected in parallel across the battery pack can improve the transient discharge performance of the battery pack and achieve high current output in a short time. The second capacitor C2 can store electrical energy. When the vehicle starts and accelerates, the second capacitor C2 can quickly discharge the stored energy, improve the output power of the battery pack side, thereby playing an important role when the output of the battery pack cannot meet the instantaneous demand, and can effectively protect the battery pack from instantaneous large current discharge.

[0115] In some embodiments, as shown in FIGS. 2 and 3, in the case of charging the battery pack, the voltage provided by the charge-discharge port is boosted by the inverter circuit and output to the battery pack.

[0116] For example, in the boosting process, the switching frequency of at least one of the plurality of switching elements included in the inverter circuit is determined according to the current value flowing through the second end of the driving motor.

[0117] When the battery pack is charged by the charge-discharge circuit, based on the value of the battery pack charging current, a suitable switching frequency is selected, and the switching elements in the inverter circuit are controlled to operate at the selected switching frequency, so that the charge-discharge circuit can charge the battery pack with the required charging power that meets the set requirements, improve the charging efficiency of the charge-discharge circuit, and reduce the charging time of the battery pack.

[0118] In some embodiments, as shown in FIGS. 2 and 3, in the boosting process, the charge-discharge circuit switches between the first stage and the second stage.

[0119] As shown in FIG. 2, in the first stage, the first relay K1 and the second relay K2 are turned on, and the third relay K3 is turned off. The first end to the second end of the second switching element S2, S4, S6 of at least one phase leg of the inverter circuit is turned on, so that the charge-discharge port, the first relay K1, the winding coil, the second switching element S2, S4, S6 electrically connected to the winding coil, and the second relay K2 form a loop. The switching frequency of the second switching element S2, S4, S6 is determined according to the current value flowing through the second end of the driving motor.

[0120] As shown in FIG. 3, in the second stage, the first relay K1, the second relay K2 and the third relay K3 are turned on, the second end to the first end of the first switching element S1, S3, S5 of at least one phase bridge arm of the inverter circuit is turned on, and the second switching element S2, S4, S6 is turned off, so that the charging and discharging port, the first relay K1, the winding coil, the first switching element S1, S3, S5 electrically connected with the winding coil, the third relay K3, the battery pack and the second relay K2 form a loop. The switching frequency of the first switching element S1, S3, S5 is determined according to the current value flowing through the second end of the driving motor.

[0121] In some embodiments of the present disclosure, in the first stage, in the multi-phase bridge arm of the inverter circuit, the first end to the second end of the second switching element S2, S4, S6 of at least one phase bridge arm is turned on. As shown in FIG. 2, the first end to the second end of at least one of the second switching element S2, the second switching element S4 and the second switching element S6 is turned on.

[0122] In the second stage, in the multi-phase bridge arm of the inverter circuit, the second end to the first end of the first switching element S1, S3, S5 of at least one phase bridge arm is turned on. As shown in FIG. 3, the second end to the first end of at least one of the first switching element S1, the first switching element S3 and the first switching element S5 is turned on.

[0123] As shown in FIG. 2 and FIG. 3, the winding coil in the second stage is equivalent to another power supply connected in series with the charging and discharging port, and the charging and discharging port and the winding coil jointly supply power to the battery pack, thereby improving the voltage on the power supply side and realizing the boost charging of the battery pack by the charging and discharging port.

[0124] There is a mapping relationship between the current flowing through the second end of the driving motor and the switching frequency of the at least one switching element.

[0125] For example, in the first stage and the second stage, the required switching frequency meeting the set requirements can be selected in the efficiency mapping table according to the current flowing through the second end of the driving motor, and the switching element (such as at least one of the first switching element S1, S3, S5 or the second switching element S2, S4, S6) participating in the first stage or the second stage in the inverter circuit is operated at the switching frequency, thereby improving the energy storage efficiency of the winding coil in the energy storage process in the first stage and the charging efficiency of the battery pack in the charging process in the second stage. The mapping table can be, but is not limited to, a mapping table obtained by calibration.

[0126] In some embodiments, as shown in FIG. 4 and FIG. 5, in the case that the battery pack discharges to the outside, the voltage output by the battery pack is output to the charging and discharging port after being stepped down by the inverter circuit and the driving motor to supply power to the to-be-charged device.

[0127] For example, in the process of voltage reduction, the switching frequency of at least one of the plurality of switching elements included in the driving motor is determined according to the current value flowing through the second end of the driving motor.

[0128] When the battery pack discharges through the charge-discharge circuit, based on the value of the discharge current of the battery pack, a suitable switching frequency is selected, and the switching elements in the inverter circuit are controlled to operate at the selected switching frequency, so that the charge-discharge circuit can discharge at the required discharge power that meets the set requirements, improving the discharge efficiency of the charge-discharge circuit.

[0129] In some embodiments, as shown in FIGS. 4 and 5, in the process of voltage reduction, the charge-discharge circuit switches between the third phase and the fourth phase.

[0130] As shown in FIG. 4, in the third phase, the third relay K3 is turned on, and the first end to the second end of the first switching element S1, S3, S5 of at least one phase leg of the inverter circuit is turned on. The battery pack, the third relay K3, the first switching element, the driving motor, and the device to be charged form a loop.

[0131] As shown in FIG. 5, in the fourth phase, the third relay K3 is turned off, and the second end to the first end of the second switching element S2, S4, S6 of at least one phase leg of the inverter circuit is turned on, and the driving motor, the device to be charged, and the second switching element form a loop.

[0132] In some embodiments of the present disclosure, in the third phase, in the multi-phase bridge arm of the inverter circuit, the first end to the second end of the first switching element S1, S3, S5 of at least one phase leg is turned on. As shown in FIG. 4, the first end to the second end of at least one of the first switching element S1, the first switching element S3, and the first switching element S5 is turned on.

[0133] In the fourth phase, in the multi-phase bridge arm of the inverter circuit, the second end to the first end of the second switching element S2, S4, S6 of at least one phase leg is turned on. As shown in FIG. 5, the second end to the first end of at least one of the second switching element S2, the second switching element S4, and the second switching element S6 is turned on.

[0134] As shown in FIGS. 4 and 5, in the fourth phase, the winding coil is equivalent to the power supply supplying power to the charge-discharge port, and the output voltage of the winding coil is less than the voltage of the battery pack, thereby reducing the voltage on the power supply side and achieving the voltage reduction discharge of the battery pack to the outside.

[0135] And, in the third stage and the fourth stage, the required switching frequency can be selected in the efficiency mapping table according to the current flowing through the second end of the driving motor, and the switching element (at least one of the first switching elements S1, S3, S5 or the second switching elements S2, S4, S6) participating in the third stage or the fourth stage is operated at the switching frequency, so as to improve 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.

[0136] In some embodiments, as shown in FIG. 6, the charging and discharging circuit further comprises a fourth relay K4. The first end of the fourth relay K4 is electrically connected to the first pole of the battery pack, and the second end of the fourth relay K4 is electrically connected to the first end of the charging and discharging port.

[0137] In some embodiments, as shown in FIGS. 7 and 8, in the case of charging the battery pack by connecting the external power supply to the charging and discharging port, if the voltage of the charging and discharging 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.

[0138] In the case that the power supply of the external power supply connected to the charging and discharging port matches the power supply of the battery pack, as shown in FIG. 7, in the charging and discharging circuit, the first relay K1, the second relay K2, the third relay K3 and the fourth relay K4 can be turned on. In this case, 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, and two current branches are formed between the first pole of the battery pack and the first end of the charging and discharging port.

[0139] The current flow 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. The current flow of the second branch is: the first end of the charging and discharging port→the first relay K1→at least one set of winding coils→the first switching element connected to the winding coils→the third relay K3→the first pole of the battery pack.

[0140] In some embodiments, in the case that the power supply of the external power supply connected to the charging and discharging port matches the power supply of the battery pack, as shown in FIG. 8, in the charging and discharging circuit, the first relay K1 is turned off, and the second relay K2, the third relay K3 and the fourth relay K4 can be turned on, so that the charging and discharging port and the battery pack form a loop, and the external power supply charges the battery pack through the charging and discharging port.

[0141] Based on this, in some embodiments, when the battery pack discharges externally and the voltage of the battery pack matches the voltage of the charging and discharging port, as shown in FIG. 9, in the charging and discharging circuit, the first relay K1 is disconnected, the second relay K2, the third relay K3 and the fourth relay K4 are turned on, so that the charging and discharging port forms a loop with the battery pack, and the battery pack discharges externally through the charging and discharging port.

[0142] In some embodiments, as shown in FIG. 6, when the external power source is connected to the charging and discharging port to charge the battery pack, if the voltage of the charging and discharging port is less than the voltage of the battery pack, the first relay K1 is turned on.

[0143] In the case that the external power source connected to the charging and discharging port does not match the power source of the battery pack, the charging and discharging circuit in FIG. 6 can use the mode shown in FIG. 2 and FIG. 3 for step-up charging, at this time the fourth relay K4 is disconnected and equivalent to open circuit. The circuit structure shown in FIG. 6 is similar to the circuit structure shown in FIG. 1, and the charging process of the battery pack can refer to the description of FIG. 2 and FIG. 3 above, which will not be repeated here.

[0144] In some embodiments, as shown in FIG. 10, the charging and discharging circuit further includes a fifth relay K5. The first end of the fifth relay K5 is connected to the first pole of the battery pack, and the second end of the fifth relay K5 is connected to the second end of the driving motor.

[0145] For example, in the case that the charging and discharging circuit includes the first relay K1 and the fifth relay K5, the second end of the fifth relay K5 is connected to the common connection end of the second end of the driving motor and the first relay K1.

[0146] In the case that the charging and discharging circuit includes the third relay K3 and the fifth relay K5, the first end of the fifth relay K5 is connected to the common connection end of the first pole of the battery pack and the third relay K3.

[0147] In some embodiments, as shown in FIG. 11 and FIG. 12, in the case of charging the battery pack, the voltage provided by the charging and discharging port is output to the battery pack after being stepped down by the inverter circuit and the driving motor.

[0148] For example, in the process of stepping down, the switching frequency of at least one of the plurality of switching elements included in the inverter circuit is determined according to the current value flowing through the second end of the driving motor.

[0149] When charging the battery pack through the charging and discharging circuit, based on the value of the battery pack charging current, a suitable switching frequency is selected, and the switching elements in the inverter circuit are controlled to work at the selected switching frequency, so that the charging and discharging circuit can charge the battery pack with the required charging power that meets the set requirements, improve the charging efficiency of the charging and discharging circuit, and reduce the charging time of the battery pack.

[0150] In some embodiments, as shown in FIG. 11 and FIG. 12, during the voltage reduction process, the charge-discharge circuit switches between the fifth stage and the sixth stage.

[0151] As shown in FIG. 11, in the fifth stage, the fourth relay K4 and the fifth relay K5 are turned on, the first end to the second end of the first switching element S1, S3, S5 of at least one phase bridge arm of the inverter circuit is turned on, so that the charge-discharge port, the fourth relay K4, at least one first switching element S1, S3, S5, the winding coil connected with the first switching element S1, S3, S5, the fifth relay K5, and the battery pack form a loop.

[0152] As shown in FIG. 12, in the sixth stage, the fourth relay K4 is turned off, the fifth relay K5 is turned on, the second end to the first end of the second switching element S2, S4, S6 of at least one phase bridge arm of the inverter circuit is turned on, so that the winding coil, the fifth relay K5, the battery pack, and the second switching element S2, S4, S6 form a loop.

[0153] In some embodiments of the present disclosure, in the fifth stage, in the multi-phase bridge arm of the inverter circuit, the first end to the second end of the first switching element S1, S3, S5 of at least one phase bridge arm is turned on. As shown in FIG. 11, the first end to the second end of at least one of the first switching element S1, the first switching element S3, and the first switching element S5 is turned on.

[0154] In the sixth stage, in the multi-phase bridge arm of the inverter circuit, the second end to the first end of the second switching element S2, S4, S6 of at least one phase bridge arm is turned on. As shown in FIG. 12, the second end to the first end of at least one of the second switching element S2, the second switching element S4, and the second switching element S6 is turned on.

[0155] As shown in FIG. 11 and FIG. 12, in the sixth stage, the winding coil is equivalent to the power supply supplying power to the charge-discharge port, and the output voltage of the winding coil is less than the voltage of the battery pack, thereby reducing the voltage of the power supply side and achieving the voltage reduction charging of the battery pack.

[0156] In addition, in the fifth stage and the sixth stage, the required switching frequency that meets the set requirements can be selected in the efficiency mapping table according to the current flowing through the second end of the driving motor, and the switching element (such as at least one of the first switching element S1, S3, S5 or the second switching element S2, S4, S6) participating in the fifth stage or the sixth stage is operated at the switching frequency, thereby improving the energy storage efficiency of the winding coil in the energy storage process in the fifth stage and the discharge efficiency of the winding coil in the external discharge process in the sixth stage.

[0157] In some embodiments, as shown in FIGS. 13 and 14, in the case of discharging the battery pack to the outside, the voltage output by the battery pack is boosted by the driving motor and the inverter circuit, and then output to the charge-discharge port to supply power to the device to be charged.

[0158] For example, in the process of boosting, the switching frequency of at least one of the switching elements included in the inverter circuit is determined according to the current value flowing through the second end of the driving motor.

[0159] When the battery pack discharges to the outside through the charge-discharge circuit, based on the value of the battery pack charging current, a suitable switching frequency is selected, and the switching elements in the inverter circuit are controlled to operate at the selected switching frequency, so that the battery pack can discharge to the outside with the required discharging power that meets the set requirements, and the discharging efficiency of the charge-discharge circuit is improved.

[0160] In some embodiments, as shown in FIGS. 13 and 14, in the process of boosting, the charge-discharge circuit switches between the seventh stage and the eighth stage.

[0161] As shown in FIG. 13, in the seventh stage, the fourth relay K4 is turned off, the fifth relay K5 is turned on, and the first end to the second end of the second switching elements S2, S4, S6 of at least one phase arm of the inverter circuit is turned on, so that the battery pack, the fifth relay K5, the winding coil, and the second switching elements S2, S4, S6 connected to the winding coil form a loop.

[0162] As shown in FIG. 14, 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 switching elements S1, S3, S5 of at least one phase arm of the inverter circuit is turned on, so that the battery pack, the fifth relay K5, the winding coil, the first switching elements S1, S3, S5 connected to the winding coil, the fourth relay K4, and the device to be charged form a loop.

[0163] In some embodiments of the present disclosure, in the seventh stage, in the multi-phase bridge arms of the inverter circuit, the first end to the second end of the second switching elements S2, S4, S6 of at least one phase arm is turned on. As shown in FIG. 13, the first end to the second end of at least one of the second switching element S2, the second switching element S4, and the second switching element S6 is turned on.

[0164] In the eighth stage, in the multi-phase bridge arms of the inverter circuit, the second end to the first end of the first switching elements S1, S3, S5 of at least one phase arm is turned on. As shown in FIG. 14, the second end to the first end of at least one of the first switching element S1, the first switching element S3, and the first switching element S5 is turned on.

[0165] As shown in FIG. 13 and FIG. 14, in the eighth stage, the winding coil in the eighth stage is equivalent to another power supply in series with the battery pack, and the two together supply power to the charge-discharge port, thereby increasing the voltage on the power supply side and achieving the voltage boost discharge of the battery pack to the outside.

[0166] In the seventh stage and the eighth stage, the required switching frequency of the switching element can be selected according to the current flowing through the second end of the driving motor in the efficiency mapping table, and the switching element (such as at least one of the first switching elements S1, S3, S5 or the second switching elements S2, S4, S6) participating in the seventh stage or the eighth stage is operated at the switching frequency, thereby improving the energy storage efficiency of the winding coil in the energy storage process in the seventh stage and the discharge efficiency of the winding coil in the external discharge process in the eighth stage.

[0167] Based on any of the above embodiments, in some embodiments, the switching frequency of the at least one switching element is based on the current value of the second end of the driving motor, and the switching frequency required for the charging or discharging efficiency of the charge-discharge circuit to meet 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 maximum.

[0168] In some embodiments, the switching frequency is selected from the efficiency mapping table. The efficiency mapping table is used to characterize the correspondence between the current flowing through the second end of the driving motor and the switching frequency of the at least one switching element when the charging or discharging efficiency of the charge-discharge 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 maximum.

[0169] In some embodiments, when the external power source connected to the charge-discharge port matches the power source of the battery pack, as shown in FIG. 15, in the charge-discharge circuit, the first relay K1 and the fifth relay K5 are disconnected, the second relay K2, the third relay K3 and the fourth relay K4 are turned on, the charge-discharge port forms a loop with the battery pack, and the external power source charges the battery pack through the charge-discharge port.

[0170] Based on this, in some embodiments, when the battery pack discharges to the outside and the voltage of the battery pack matches the voltage of the charge-discharge port, as shown in FIG. 16, in the charge-discharge circuit, the first relay K1 and the fifth relay K5 are disconnected, the second relay K2, the third relay K3 and the fourth relay K4 are turned on, the charge-discharge port forms a loop with the battery pack, and the battery pack discharges to the outside through the charge-discharge port.

[0171] In other embodiments, as shown in FIG. 17, when the external power source connected to the charging and discharging port matches the power source of the battery pack, in the charging and discharging circuit, the third relay K3 and the fourth relay K4 are disconnected, the first relay K1, the second relay K2 and the fifth relay K5 are turned on, the charging and discharging port forms a loop with the battery pack, and the external power source charges the battery pack through the charging and discharging port.

[0172] Based on this, in other embodiments, when the battery pack discharges externally and the voltage of the battery pack matches the voltage of the charging and discharging port, as shown in FIG. 18, in the charging and discharging circuit, the third relay K3 and the fourth relay K4 are disconnected, the first relay K1, the second relay K2 and the fifth relay K5 are turned on, the charging and discharging port forms a loop with the battery pack, and the battery pack discharges externally through the charging and discharging port.

[0173] FIG. 19 is a curve diagram of the charging or discharging current of the charging and discharging circuit of some embodiments of the present disclosure varying with the charging or discharging time length.

[0174] Taking charging the battery pack as an example, as shown in FIG. 19, the process of charging the battery pack includes a charging starting stage (a pre-charging stage, such as the 0-t1 stage shown in FIG. 19), a large-current charging stage (such as the t1-t2 stage shown in FIG. 19) and a small-current trickle charging stage (such as the t2-t3 stage shown in FIG. 19).

[0175] In the charging starting stage, the external power source is connected to the charging and discharging port, and the charging and discharging circuit is connected and matched with the external power source. In this stage, the battery pack is first charged with a small current, and the charging matching process has a higher requirement 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 stage 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 source can be improved, and the charging efficiency in the charging starting stage can also be improved.

[0176] In the large-current charging stage, after the charging and discharging circuit is successfully matched with the external power source, the output current of the charging and discharging port gradually increases, and correspondingly, the charging power also gradually increases. At this time, since a higher switching frequency will cause the inverter circuit to generate a large amount of heat and cause over-temperature and other faults, in the large-current charging stage, a lower switching frequency f2 is adopted by looking up the efficiency mapping table, and the switching elements of the inverter circuit that are turned on in this stage work at the switching frequency f2 for long-time large-current charging. In this way, while the charging efficiency is improved, over-temperature and other faults in the charging process can also be avoided.

[0177] In the small current trickle charging stage, when the state of charge (SOC) of the battery pack reaches a high level (for example, the state of charge is greater than or equal to 95%, which is only an exemplary illustration and is not a limitation on the present disclosure, and can be adaptively designed as needed), the small current trickle charging stage is entered to protect the battery pack and avoid overcharging of the battery pack. 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 are operated at the switching frequency f3, so as to improve the charging efficiency.

[0178] In this way, the charging and discharging circuit of some embodiments of the present disclosure can select a suitable switching frequency for the switching elements of the inverter circuit based on the current charging current of the charging and discharging circuit through the efficiency mapping table, so as to improve the matching success rate of the charging and discharging circuit and the external power supply in the charging start stage.

[0179] During the entire charging process, whether in the connection matching process of the charging and discharging circuit and the external power supply or in the subsequent process, the charging and discharging system can be charged at the required charging power that meets the set requirements, so as to improve the charging efficiency of the charging and discharging system.

[0180] Correspondingly, the charging and discharging system of some embodiments of the present disclosure can also select a suitable switching frequency for the switching elements of the inverter circuit based on the current discharging current during the discharging process of the battery pack to the outside, so that the charging and discharging system can discharge at the required discharging power that meets the set requirements during the entire discharging process, so as to improve the discharging efficiency of the charging and discharging system.

[0181] Table 1 is an efficiency mapping table of the charging and discharging system of some embodiments of the present disclosure.

[0182] Table 1 efficiency mapping table

[0183] Different combinations of charging or discharging current and switching frequency can obtain different charging or discharging efficiencies. In the switching frequency efficiency mapping table, the charging or discharging efficiencies corresponding to different combinations of charging or discharging current and switching frequency can be obtained by offline calibration.

[0184] For example, according to the working conditions shown in Table 1, the charging or discharging efficiency under different charging or discharging current and switching frequency is tested on the charging and discharging circuit test bench, and is recorded in the table. In this way, when the charging and discharging circuit is charging or discharging, the switching frequency corresponding to the maximum efficiency can be found through the table to charge or discharge.

[0185] In any of the foregoing embodiments, during charging or discharging of the battery pack, at least one of the multi-phase bridge arms of the inverter circuit participates in the charging or discharging process, and the first switching elements S1, S3, S5 and the second switching elements S2, S4, S6 of the bridge arm participating in the charging or discharging process are alternately turned on and off.

[0186] For example, during a large-current charging phase, the three-phase bridge arms of the inverter circuit can be used together, and during a small-current charging phase (such as a charging start phase or a small-current trickle charging phase), only one or two of the phase bridge arms of the inverter circuit can be used, so that the equivalent inductance of the winding coil of the driving motor can be improved, and the small-current charging efficiency can be further improved.

[0187] It should be noted that the inverter circuit is not limited to the three-phase inverter circuit described above, but can also be a four-phase inverter circuit, a five-phase inverter circuit, etc., which is not limited herein. Similarly, the motor described above is not limited to the three-phase motor described above, but can also be a four-phase motor, a five-phase motor, etc., which is not limited herein.

[0188] Based on any of the foregoing embodiments, in the charging and discharging system of some embodiments, when charging the battery pack, the controller can determine the duty cycle of the pulse width modulation signal according to the voltage difference between the battery pack and the charging and discharging port; determine the switching frequency of at least one of the plurality of switching elements according to the current flowing through the second end of the driving motor; and output the pulse width modulation signal to the at least one switching element according to the determined duty cycle and switching frequency.

[0189] Based on the foregoing embodiments, in the charging and discharging system of some embodiments, the controller is electrically connected to the control terminals of the plurality of switching elements of the inverter circuit.

[0190] In some embodiments, the controller is configured to output a pulse width modulation signal to at least one of the plurality of switching elements of the inverter circuit to adjust the switching frequency of the at least one switching element.

[0191] For example, the controller is further configured to determine 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 output the pulse width modulation signal to the at least one switching element according to the determined duty cycle and switching frequency.

[0192] The charging and discharging system provided by some embodiments of the present disclosure can adjust the duty cycle of the switching elements 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 meets the charging or discharging condition of the battery pack.

[0193] And, the charging and discharging circuit is also capable of selecting an 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 adjusting the switching elements of the inverter circuit to work at the determined switching frequency, so as to improve the charging or discharging power of the battery pack, and further improve the charging or discharging efficiency of the battery pack.

[0194] 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 end of the driving 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 end of the driving motor when discharging the battery pack.

[0195] In the charging and discharging circuit of some embodiments of the present disclosure, the on-off control of the switching elements in the inverter circuit is realized by the pulse width modulation signal, so that the battery pack, the inverter circuit, the driving motor and the charging and discharging port can form different charging or discharging loops, thereby matching and adjusting the voltages of the battery pack and the charging and discharging port, and adjusting the difference between the voltages of the battery pack and the charging and discharging port to be within the adaptive range.

[0196] The current flowing through the second end of the driving motor is referred to as 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 externally 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 required charging or discharging power that meets 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.

[0197] Some embodiments of the present disclosure also provide a control method of a charging and discharging circuit.

[0198] In some embodiments, the charging and discharging circuit comprises an inverter circuit. The inverter circuit comprises a plurality of switching elements. During the process of charging the battery pack or discharging the battery pack externally, the inverter circuit is electrically connected between the battery pack and the charging and discharging port. The control method of the charging and discharging circuit comprises the following steps:

[0199] In step A1, during the process of charging the battery pack or discharging the battery pack externally, 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.

[0200] In step A2, the switching frequency of at least one of the plurality of switching elements is determined according to the current flowing through the second end of the driving motor.

[0201] In step A3, the pulse width modulation signal is output to the at least one switching element according to the determined duty cycle and switching frequency.

[0202] The control method of the charging and discharging circuit can be used to control the charging and discharging circuit provided by any of the above embodiments. The corresponding control process and advantages can be referred to the description of the working process and advantages of the charging and discharging system, which will not be repeated here.

[0203] In the description of the present specification, specific features, structures or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0204] The above is only a specific implementation of the present disclosure, but the protection scope of the present disclosure is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present disclosure, which should be covered within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. A charging and discharging circuit, comprising: an inverter circuit; a first end of the inverter circuit is electrically connected to a first pole of a battery pack, and a second end of the inverter circuit is electrically connected to a second pole of the battery pack; the inverter circuit comprises a plurality of switching elements; and 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 charging and discharging port, and a 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; wherein a switching frequency of at least one switching element of the plurality of switching elements is determined according to a current value flowing through the second end of the drive motor.

2. The charge and discharge circuit according to claim 1, wherein The switching frequency of the at least one switching element is based on the current value of the second end of the drive motor, and a switching frequency required for a charging or discharging efficiency of the charging and discharging circuit to meet a set requirement.

3. The charge and discharge circuit according to claim 2, wherein The switching frequency is selected from an efficiency mapping table, which is used to represent the corresponding relationship 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 requirement.

4. The charge and discharge circuit according to claim 2 or 3, wherein 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 maximum.

5. The charge and discharge circuit according to any one of claims 1 to 4, wherein The inverter circuit comprises a plurality of parallel multi-phase bridge arms, each phase bridge arm of the multi-phase bridge arms is electrically connected between the first end and the second end of the inverter circuit; each phase bridge arm comprises a first switching element and a second switching element, and the plurality of switching elements comprises the first switching element and the second switching element; a first end of the first switching element is electrically connected to the first end of the inverter circuit, a second end of the first switching element is electrically connected to a first end of the second switching element, and a second end of the second switching element is electrically connected to the second end of the inverter circuit; a common connection end of the first switching element and the second switching element is the third end of the inverter circuit; the drive motor comprises a plurality of groups of winding coils, a first end of a group of winding coils of the plurality of groups of winding coils is connected to the common connection end of the first switching element and the second switching element of a phase bridge arm of the multi-phase bridge arms, and a second end of the group of winding coils is electrically connected to the second end of the drive motor.

6. The charge and discharge circuit according to claim 5, wherein In the case of charging the battery pack, the voltage provided by the charging and discharging port is boosted through the inverter circuit and the drive motor and then output to the battery pack.

7. The charge and discharge circuit according to claim 6, wherein During the boosting process, the charging and discharging circuit can be switched between a first stage and a second stage; in the first stage, 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 charging and discharging port, the winding coil, and the second switching element electrically connected to the winding coil form a loop; in the second stage, the second end to the first end of the first switching element of the at least one phase bridge arm of the inverter circuit is turned on, 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.

8. The charge and discharge circuit according to any one of claims 5 to 7, further comprising: a first relay and a second relay; The first relay is electrically connected between the second end of the driving motor and the first end of the charge-discharge port. The second relay is electrically connected between the second pole of the battery pack and the second end of the charge-discharge port.

9. The charge and discharge circuit according to any one of claims 5 to 8, wherein The first end of the inverter circuit is also electrically connected to the first end of the charge-discharge port. The charge-discharge circuit further comprises a third relay, the first end of the third relay is electrically connected to the first pole of the battery pack, and the second end of the third relay is electrically connected to the first end of the inverter circuit.

10. The charge and discharge circuit according to claim 9, wherein In the case that the battery pack discharges externally, the voltage output by the battery pack is stepped down by the inverter circuit and the driving motor, and then output to the charge-discharge port to supply power to the device to be charged.

11. The charge and discharge circuit according to claim 10, wherein During the voltage step-down process, the charge-discharge circuit can switch between a third phase and a fourth phase. In the third phase, the third relay is turned on, the first end to the second end of the first switching element of at least one phase arm of the inverter circuit is turned on, and the battery pack, the third relay, the first switching element, the driving motor, and the device to be charged form a loop. In the fourth phase, the third relay is turned off, the second end to the first end of the second switching element of at least one phase arm of the inverter circuit is turned on, and the driving motor, the device to be charged, and the second switching element form a loop.

12. The charge-discharge circuit of any one of claims 5 to 11, further comprising a fourth relay, the first end of the fourth relay is electrically connected to the first pole of the battery pack, and the second end of the fourth relay is electrically connected to the first end of the charge-discharge port.

13. The charge-discharge circuit of claim 12, further comprising a first relay, the first relay is electrically connected between the second end of the driving motor and the first end of the charge-discharge port. In the case that the external power source is connected to the charge-discharge port to charge the battery pack, if it is determined that the voltage of the charge-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. In the case that the external power source is connected to the charge-discharge port to charge the battery pack, if it is determined that the voltage of the charge-discharge port is less than the voltage of the battery pack, the first relay is turned on.

14. The charge and discharge circuit according to claim 12 or 13, further comprising: A fifth relay, the first end of the fifth relay is connected to the first pole of the battery pack, and the second end of the fifth relay is connected to the second end of the driving motor.

15. The charge and discharge circuit according to claim 14, wherein In the case that the battery pack is charged, the voltage provided by the charge-discharge port is stepped down by the inverter circuit and the driving motor, and then output to the battery pack.

16. The charge and discharge circuit according to claim 15, wherein During the voltage step-down process, the charge-discharge circuit can switch between a fifth phase and a sixth phase. In the fifth phase, the fourth relay and the fifth relay are turned on, the first end to the second end of the first switching element of at least one phase arm of the inverter circuit is turned on, and the charge-discharge port, the fourth relay, the first switching element, the winding coil connected to the first switching element, the fifth relay, and the battery pack form a loop. In the sixth stage, the fourth relay is turned off, the fifth relay is turned on, 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, so that the winding coil, the fifth relay, the battery pack, and the second switch element form a loop.

17. The charge and discharge circuit according to any one of claims 14 to 16, wherein, In the case of discharging the battery pack, the voltage output by the battery pack is boosted through the driving motor and the inverter circuit, and then output to the charging and discharging port to supply power to the device to be charged.

18. The charge and discharge circuit according to claim 17, wherein During the boosting process, the charging and discharging circuit can switch between the seventh stage and the eighth stage; In the seventh stage, the fourth relay is turned off, the fifth relay is turned on, 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, 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.

19. A charging and discharging system comprising the charging and discharging circuit according to any one of claims 1 to 18; and a controller electrically connected to the control end of the plurality of switch elements of the inverter circuit; wherein The controller is configured to output a pulse width modulation signal to the at least one switch element to adjust the switching frequency of the at least one switch element.

20. The charge and discharge system according to claim 19, wherein The controller satisfies at least one of the following: The controller is further configured to determine the switching frequency of at least one switch element in the plurality of switch elements according to the charging current flowing through the second end of the driving motor when charging the battery pack; Or The controller is further configured to determine the switching frequency of at least one switch element in the plurality of switch elements according to the discharging current flowing through the second end of the driving motor when discharging the battery pack.

21. A vehicle comprising the charging and discharging system according to claim 19 or 20.

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