Electric vehicle battery system and control method

Abstract

The present invention provides an electric vehicle battery system and control method. The system is provided with a load interface and a charging interface, and further includes: a power battery pack; at least one extended-range battery pack interface, each of which can be connected to an extended-range battery pack; a bidirectional DC / DC converter is provided between each of the extended-range battery packs and the power battery pack, for converting a DC input voltage / current into an output voltage / current that matches the charging voltage / current of the power battery pack or the extended-range battery pack; when at least one extended-range battery pack interface is connected to an extended-range battery pack, the power battery pack and the extended-range battery pack form a parallel output. The system of the present invention can use battery packs of different specifications to meet the needs of on-demand rental and flexible use; at the same time, by controlling the bidirectional DC / DC converter, the magnitude and transmission direction of its output voltage / current can be controlled, thereby obtaining a better energy storage solution and increasing the cruising range of the electric vehicle.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to an electric vehicle battery system and a control method thereof. Background Art

[0002] At present, the application of electric vehicles is becoming more and more widespread. Many electric vehicles adopt the technical solution of multi-battery parallel power supply. Some electric vehicles can include a power battery pack and a detachable range-extending battery pack. The existing electric vehicles of this type can only charge the power battery pack through the range-extending battery pack, or power the motor in parallel with the power battery pack. For example, in the patent (ZL202120758843.3), the battery system for electric vehicles consists of two sets of battery packs. One set of battery packs is used as the main battery pack, which has a lower power and a wider operating voltage range and is fixed on the vehicle; the other set of battery packs is used as the slave battery pack, which has a higher power and a narrower operating voltage range. The slave battery pack is fixed on the electric vehicle or used as a battery replacement battery pack. The main battery pack and the slave battery pack are connected in parallel. This patent addresses the issue of inaccurate remaining range in electric vehicles when the charge level is low, preventing the vehicle from breaking down and reminding the driver to charge or replace the battery promptly. It is suitable for both charging and battery replacement applications. In battery replacement applications, the secondary battery pack serves as the battery pack for battery replacement, and its high capacity makes battery replacement more energy efficient. The primary battery pack does not require dedicated charging; the secondary battery pack can automatically charge the power battery pack while the vehicle is running or parked. However, there is no technical solution for charging the range-extending battery with a power battery pack.

[0003] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to ordinary technicians in this field. Summary of the Invention

[0004] In response to the problems in the prior art, the present invention aims to provide an electric vehicle battery system and control method. The electric vehicle battery system can flexibly use extended-range battery packs of different specifications through a bidirectional DC / DC converter between the power battery pack and each extended-range battery pack, thereby maximally meeting the needs of on-demand rental and flexible use; at the same time, by controlling the bidirectional DC / DC converter, the magnitude and transmission direction of its output voltage / current can be controlled, thereby obtaining a better energy storage solution and increasing the cruising range of the electric vehicle.

[0005] A first aspect of the present invention provides an electric vehicle battery system, provided with an interface for connecting to a load, comprising:

[0006] Power battery pack;

[0007] at least one bidirectional DC / DC converter;

[0008] At least one range-extended battery pack interface, each of which can be connected to a range-extended battery pack, and a bidirectional DC / DC converter is provided between each range-extended battery pack and the power battery pack, for converting a DC input voltage / current into an output voltage / current compatible with the charging voltage / current of the power battery pack or the range-extended battery pack;

[0009] When at least one of the range-extending battery pack interfaces is connected to a range-extending battery pack, the power battery pack and the range-extending battery pack form a parallel output.

[0010] According to the first aspect of the present invention, the electric vehicle battery system further includes a charging interface for connecting to charging power, and the charging interface is respectively connected to the power battery pack and each of the bidirectional DC / DC converters.

[0011] According to the first aspect of the present invention, the system further comprises a battery information processing module connected to the power battery pack, each of the bidirectional DC / DC converters and the charging interface;

[0012] The battery information processing module includes a data unit, a monitoring unit and a calculation unit;

[0013] The data unit is used to obtain electric vehicle parameters, battery pack parameters of the power battery pack, battery pack parameters of each of the extended-range battery packs and / or parameters of the charging interface;

[0014] The monitoring unit is used to monitor the power parameters of the power battery pack, the power parameters corresponding to each of the extended-range battery packs and / or the power parameters of the charging interface;

[0015] The calculation unit is used to determine the target value and transmission direction of the output voltage / current of each bidirectional DC / DC converter according to the parameters obtained by the data unit and the electric energy parameters monitored by the monitoring unit.

[0016] According to the first aspect of the present invention, the bidirectional DC / DC converter includes a DC / DC control unit;

[0017] The DC / DC control unit is used to control the output voltage / current and transmission direction of the bidirectional DC / DC converter according to the target value of the output voltage / current determined by the calculation unit.

[0018] According to the first aspect of the present invention, the bidirectional DC / DC converter is a digital DC / DC converter.

[0019] According to the first aspect of the present invention, the power battery pack adopts a power type battery or a capacity type battery;

[0020] The range-extending battery pack adopts a power-type battery or a capacity-type battery.

[0021] A second aspect of the present invention provides a control method for an electric vehicle battery system, which is applicable to the electric vehicle battery system, and the electric vehicle battery system is connected to at least one range-extending battery pack. The control method comprises the following steps:

[0022] Acquiring electric vehicle parameters, and determining the mode of the electric vehicle according to the electric vehicle parameters;

[0023] When it is determined that the electric vehicle is in the charging mode,

[0024] Get the preset charging strategy;

[0025] Determining the battery pack to be charged according to the charging strategy;

[0026] The charger charges the battery pack to be charged according to the battery pack parameters;

[0027] When it is determined that the electric vehicle is in a driving mode, the electric vehicle battery system provides a power source for the electric vehicle motor.

[0028] According to a second aspect of the present invention, the charger determines the battery pack to be charged according to the battery pack parameters, and the steps include:

[0029] Determine the type of battery pack to be charged;

[0030] If it is a power battery pack, the charger charges the power battery pack;

[0031] If it is an extended-range battery pack, the battery pack parameters of the extended-range battery pack are obtained, and the output voltage / current of the charger is converted into the charging voltage / current of the extended-range battery pack through a bidirectional DC / DC converter.

[0032] According to a second aspect of the present invention, the calculation unit is configured to determine a target value of voltage / current required by the charging interface based on the parameters acquired by the data unit and the electric energy parameters monitored by the monitoring unit;

[0033] The charger is configured to control the voltage / current required by the charging interface according to the target value of the voltage / current required by the charging interface determined by the calculation unit;

[0034] Before the charger determines the battery pack to be charged according to the battery pack parameters, the control method further includes the steps of:

[0035] The data unit obtains parameters of the charger and determines parameters of the battery pack to be charged, wherein the parameters of the charger include the maximum output power of the charger, and the parameters of the battery pack include determining the maximum allowable charging power of the battery pack to be charged;

[0036] Determine whether the maximum output power of the charger is greater than or equal to the maximum allowable charging power of the battery pack to be charged;

[0037] If the maximum output power of the charger is greater than or equal to the maximum allowable charging power of the battery pack to be charged, the calculation unit determines the target value of the voltage / current required by the charging interface according to the maximum allowable charging power of the battery pack to be charged obtained by the data unit; and / or

[0038] If the maximum output power of the charger is less than the maximum allowable charging power of the battery pack to be charged, the calculation unit determines the target value of the voltage / current required by the charging interface based on the maximum output power of the charger obtained by the data unit, and calculates the output power target value of each of the bidirectional DC / DC converters.

[0039] The electric vehicle battery system provides a power source for the electric vehicle motor, comprising:

[0040] Get the preset discharge strategy;

[0041] Determining the battery pack to be discharged according to the discharge strategy;

[0042] The battery pack to be discharged is determined to provide a power source for the electric vehicle motor.

[0043] According to a second aspect of the present invention, when it is determined according to the discharge strategy that the battery pack to be discharged is at least one extended-range battery pack;

[0044] The steps of determining at least one extended range battery pack to provide a power source for the electric vehicle motor include:

[0045] Obtaining an electric energy parameter of at least one range-extending battery pack, and determining whether a discharge power of the at least one range-extending battery pack is greater than a requirement of a motor of the electric vehicle based on the electric energy parameter;

[0046] If the discharge power of the at least one range-extending battery pack is greater than the requirement of the electric vehicle motor, the at least one range-extending battery pack provides a power source for the electric vehicle motor, and

[0047] The at least one range-extending battery pack charges the power battery pack; and / or

[0048] If the discharge power of the at least one range-extending battery pack is less than the requirement of the electric vehicle motor, the at least one range-extending battery pack and the power battery pack provide a power source for the electric vehicle motor.

[0049] According to the second aspect of the present invention, if the discharge power of the at least one range-extending battery pack is equal to the demand of the electric vehicle motor, the at least one range-extending battery pack provides a power source for the electric vehicle motor.

[0050] According to a second aspect of the present invention, the step of charging the power battery pack by the at least one extended-range battery pack includes:

[0051] Obtaining battery pack parameters of the power battery pack;

[0052] Obtaining the output voltage / current of the at least one range-extended battery pack;

[0053] The output voltage / current of the at least one range-extending battery pack is converted into the charging voltage / current of the power battery pack by a bidirectional DC / DC converter.

[0054] The electric vehicle battery system of the present invention utilizes a bidirectional DC / DC converter between the power battery pack and each range-extending battery pack, allowing for the flexible use of range-extending battery packs of different specifications without being restricted by the specifications of the range-extending batteries, thereby maximally meeting the needs of on-demand rental and flexible use. Furthermore, for different usage scenarios, by controlling the bidirectional DC / DC converter, the output voltage / current and transmission direction can be changed based on the number of configured range-extending batteries, the charger's input power, and the charging preference, enabling the power battery pack and each range-extending battery pack to charge each other, thereby achieving a better energy storage solution and increasing the electric vehicle's range. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Other features, objects and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings.

[0056] Figure 1 This is a state diagram of a charging mode of an electric vehicle battery system loaded with n range-extending battery packs according to an embodiment of the present invention;

[0057] Figure 2 This is a driving mode state diagram of an electric vehicle battery system loaded with n range-extending battery packs according to an embodiment of the present invention;

[0058] Figure 3 This is a structural diagram of a battery information processing module of an electric vehicle battery system according to an embodiment of the present invention;

[0059] Figure 4 This is a flow chart of a control method for an electric vehicle battery system according to an embodiment of the present invention;

[0060] Figure 5 The present invention is a flowchart for determining that at least one range-extending battery pack provides a power source for a motor of an electric vehicle according to an embodiment of the present invention. DETAILED DESCRIPTION

[0061] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in a variety of forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present invention will be comprehensive and complete and will fully convey the concepts of the example embodiments to those skilled in the art. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention. Identical reference numerals in the figures represent identical or similar structures, and thus their repeated description will be omitted.

[0062] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include one or more features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0063] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections, electrical connections, or mutual communication; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0064] The disclosure below provides many different embodiments or examples for implementing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numbers and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0065] In order to solve the problems in the prior art, some embodiments of the present invention provide an electric vehicle battery system and a control method. The electric vehicle battery system is provided with a load interface connected to a load and a charging interface connected to a charger, including: a power battery pack; at least one extended-range battery pack interface, each of the extended-range battery pack interfaces can be connected to an extended-range battery pack, and a bidirectional DC / DC converter is provided between each of the extended-range battery packs and the power battery pack, for converting a DC input voltage / current into an output voltage / current that is compatible with the charging voltage / current of the power battery pack or the extended-range battery pack; when at least one of the extended-range battery pack interfaces is connected to an extended-range battery pack, the power battery pack and the extended-range battery pack form a parallel output. The electric vehicle battery system of the present invention utilizes a bidirectional DC / DC converter between the power battery pack and each range-extending battery pack, allowing for the flexible use of range-extending battery packs of different specifications without being restricted by the specifications of the range-extending batteries, thereby maximally meeting the needs of on-demand rental and flexible use. Furthermore, for different usage scenarios, by controlling the bidirectional DC / DC converter, the output voltage / current and transmission direction can be changed based on the number of configured range-extending batteries, the charger's input power, and the charging preference, enabling the power battery pack and each range-extending battery pack to charge each other, thereby achieving a better energy storage solution and increasing the electric vehicle's range.

[0066] The electric vehicle battery system and control method thereof of the present invention are further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments are not intended to limit the scope of protection of the present invention.

[0067] Figure 1 and Figure 2 Figure 1 shows different states of an electric vehicle battery system with n extended-range battery packs as loads according to an embodiment of the present invention. Specifically, the electric vehicle battery system includes a load interface 90 connected to a load 900 and a charging interface 80 connected to a charger 800. In some embodiments, the load interface 90 and the charging interface 80 may be the same interface. The loads may be electric vehicle motors, electric vehicle lighting systems, etc. The system includes:

[0068] Power battery pack 11;

[0069] Multiple bidirectional DC / DC converters; namely, the first bidirectional DC / DC converter 201 to the nth bidirectional DC / DC converter 20 n ;

[0070] At least one extended range battery pack interface, namely the first extended range battery pack interface 301 to the nth extended range battery pack interface 30 nEach of the range-extending battery pack interfaces can be connected to an extended-range battery pack. The number of range-extending battery pack interfaces in the present invention is not limited. Accordingly, the electric vehicle battery system can be connected to an extended-range battery pack with a number equivalent to that of the range-extending battery pack interfaces, that is, the first range-extending battery pack 401 to the nth range-extending battery pack 40 n .

[0071] A bidirectional DC / DC converter is provided between each of the range-extended battery packs and the power battery pack 11, such as a first bidirectional DC / DC converter 201 provided between the first range-extended battery pack interface 301 and the power battery 11. Each of the bidirectional DC / DC converters is configured to convert a DC input voltage / current into an output voltage / current compatible with the charging voltage / current of the power battery pack or the range-extended battery pack.

[0072] When at least one of the range-extending battery pack interfaces is connected to a range-extending battery pack, the power battery pack 11 and the range-extending battery pack form a parallel output.

[0073] In the electric vehicle battery system of the present invention, a bidirectional DC / DC converter is added between the power battery pack and each of the range-extending battery packs. The circuit for converting electric energy of the bidirectional DC-DC converter can convert a DC power supply into a DC power supply of different voltage / current. That is, the present invention can realize mutual charging between the power battery pack and each of the range-extending battery packs with different charging voltages / currents, wherein each bidirectional DC / DC converter converts the voltage / current into a charging voltage / current compatible with each battery pack.

[0074] For everyday, short-range urban driving, electric vehicles using the battery system of the present invention can simply use the vehicle's onboard power battery pack to meet their power and range requirements, and this power battery pack can be recharged using a charger. For occasional longer-distance driving, however, any number of extended-range battery packs can be added as needed to meet the required driving distance. The onboard extended-range battery packs can then be removed to return to basic, everyday use, reducing vehicle battery usage. Because the extended-range battery packs are connected to the battery system via a bidirectional DC / DC converter, they can flexibly accommodate battery packs of varying specifications and brands. Specifically, the power battery packs of the present invention can utilize either power or capacity batteries, and similarly, the extended-range battery packs can utilize either power or capacity batteries. Therefore, in areas with multiple battery exchange service networks, the required extended-range battery packs can be rented without restrictions, maximizing on-demand rental and flexible usage. In other words, in this scenario, the extended-range battery packs can be rented temporarily to meet specific needs or used long-term as part of the electric vehicle's battery system.

[0075] In actual use, an electric vehicle battery system may also include a power battery pack capable of high-rate charge and discharge, as well as several groups of range-extending battery packs that can be added or subtracted as needed. In this case, the power battery pack capable of high-rate charge and discharge is responsible for providing the maximum power required for the entire vehicle and the energy required for the range required for general daily travel. Its function is similar to the battery system on the current plug-in hybrid electric vehicle (PHEV) extended-range hybrid vehicle, which basically has the ability to charge and discharge at a high rate and has a smaller capacity than the battery system of a pure battery electric vehicle (BEV). In these embodiments, the range-extending battery pack does not need to be responsible for the main power output and therefore does not need to have special high-rate charge and discharge capabilities, which can effectively reduce the cost of the battery.

[0076] In some embodiments, the charging interface 80 is connected to the power battery pack 11 and each of the bidirectional DC / DC converters. That is, when the electric vehicle battery system is connected to the charger 800 via the charging interface 80, the charger 800 can charge the power battery pack 11 and each of the connected range-extended battery packs.

[0077] In some embodiments, the electric vehicle battery system further includes a power battery pack 11 and each of the bidirectional DC / DC converters (201 ... 20 n ) and the battery information processing module M120 connected to the charging interface 80, Figure 3 Schematic diagram of the structure of a battery information processing module of an electric vehicle battery system according to an embodiment of the present invention; specifically, the battery information processing module includes a data unit M121, a monitoring unit M122, and a calculation unit M123;

[0078] The data unit M121 is used to obtain electric vehicle parameters, battery pack parameters of the power battery pack, battery pack parameters of each of the range-extending battery packs, and / or parameters of the charging interface; electric vehicle parameters include but are not limited to parameters characterizing the mode of the electric vehicle, such as vehicle speed, engine speed, etc. The battery pack parameters of the power battery pack include but are not limited to parameters such as the optimal charging voltage / current / power, optimal discharging voltage / current / power, maximum charging voltage / current / power, maximum discharging voltage / current / power, and estimated charging time of the power battery pack; the battery pack parameters of each of the range-extending battery packs include but are not limited to parameters such as the optimal charging voltage / current / power, optimal discharging voltage / current / power, maximum charging voltage / current / power, maximum discharging voltage / current / power, and estimated charging time of each of the range-extending battery packs; the parameters of the charging interface include but are not limited to parameters such as the rated voltage, rated current, and maximum output voltage / current / power of the charger connected to the charging interface.

[0079] The monitoring unit M122 is used to monitor the power parameters of the power battery pack 11, the power parameters corresponding to each of the range-extending battery packs, and / or the power parameters of the charging interface. The power parameters of the power battery pack 11 include, but are not limited to, the voltage / current of the input or output of the power battery pack, the battery temperature, the remaining battery capacity percentage (SOC), the battery health (SOH), and other parameters; the power parameters of each of the range-extending battery packs include, but are not limited to, the voltage / current of the input or output of each of the range-extending battery packs, the battery temperature, the remaining battery capacity percentage (SOC), the battery health (SOH), and other parameters; the power parameters of the charging interface include parameters such as the voltage / current received by the charging interface. The monitoring unit M122 can monitor the above-mentioned power parameters, and can also monitor the above-mentioned power parameters periodically.

[0080] The calculation unit M123 is configured to determine target output voltage / current values ​​and transmission directions of each bidirectional DC / DC converter based on the parameters acquired by the data unit M121 and the power parameters monitored by the monitoring unit M122. For example, when the range-extended battery pack is charging the power battery pack, the data unit M121 acquires the battery pack parameters of the range-extended battery pack and the battery pack parameters of the power battery pack, and determines, based on the optimal charging voltage / current of the power battery pack, the target output voltage / current values ​​of the bidirectional DC / DC converter to the power battery pack, i.e., the optimal charging voltage / current of the power battery pack. Simultaneously, based on the power parameters of the range-extended battery pack and the power battery pack monitored by the monitoring unit M122, if the remaining charge of the power battery pack is detected to be 100%, the target output voltage / current values ​​of the bidirectional DC / DC converter to the power battery pack are determined to be zero, i.e., charging of the power battery pack is stopped.

[0081] The battery information processing module can be arranged in the existing electric vehicle driving controller ECU, and can also be arranged in other control modules of the electric vehicle.

[0082] At the same time, each of the bidirectional DC / DC converters includes a DC / DC control unit, and the electric vehicle battery system may include: a first DC / DC control unit M201 to an nth DC / DC control unit M20 n. Each of the DC / DC control units is used to control the output voltage / current and transmission direction of the bidirectional DC / DC converter according to the target value of the output voltage / current determined by the calculation unit. It should be noted that controlling the output voltage / current of the bidirectional DC / DC converter includes controlling the magnitude and direction of the output voltage / current of the bidirectional DC / DC converter. Preferably, the bidirectional DC / DC converter is a digital DC / DC converter. The digital DC / DC converter has a wider adjustable range, a faster dynamic response, and a more stable voltage / current output. The use of the digital DC / DC converter enables the battery system of the present invention to be connected to battery packs of more specifications and to operate more stably.

[0083] When the electric vehicle battery system is in the discharge mode, the DC / DC control unit can transmit the electric energy of the extended-range battery pack connected thereto to the load 900 according to the settings; when the electric vehicle battery system is in the charging mode, the DC / DC control unit can transmit the electric energy of the charging interface to the extended-range battery pack connected thereto according to the settings, or the DC / DC control unit can transmit the electric energy of the extended-range battery pack to the power battery pack according to the settings, etc.

[0084] When the battery system of the present invention is not equipped with a range-extending battery pack, the charging and discharging method of the power battery pack is the same as that of a basic rechargeable electric vehicle, which will not be described in detail here.

[0085] The present invention also provides a control method applicable to the electric vehicle battery system, and the electric vehicle battery system is connected to at least one extended-range battery pack, that is, the control method of the present invention is applicable to the situation where the electric vehicle battery system is connected to at least one extended-range battery pack.

[0086] Figure 4 This is a flow chart of a control method for an electric vehicle battery system according to an embodiment of the present invention. Specifically, the control method includes the following steps:

[0087] S100: Obtaining electric vehicle parameters;

[0088] S200: Determine the mode of the electric vehicle according to the electric vehicle parameters. The mode of the electric vehicle may be determined by a communication signal connected to the battery system.

[0089] When it is determined that the electric vehicle is in a driving mode, the electric vehicle battery system provides a power source for the electric vehicle motor. Providing a power source for the electric vehicle motor may specifically include the following steps:

[0090] S320: Obtaining a preset discharge strategy;

[0091] S420: Determine the battery pack to be discharged according to the discharge strategy;

[0092] S520: Determine that the battery pack to be discharged provides a power source for the electric vehicle motor.

[0093] like Figure 2 As shown, where P DPB is the output power of the power battery pack, P DPB The timing represents the discharge of the power battery pack, P DPB When it is negative, it means the power battery pack is charging; P DEB1 is the output power of the first extended range battery pack, P DEBn is the output power of the n-th extended range battery pack, P L is the load power, load power P L Equal to the sum of the output power of the power battery pack and each range-extending battery pack (P L＝ P DPB +P DEB1 +…+…+P DEBn In the process of providing power to the electric vehicle motor, the bidirectional DC / DC converter transfers the electric energy of the range-extended battery pack to the battery system at a nearly constant rate that does not exceed the maximum discharge rate allowed by the range-extended battery pack at that time.

[0094] In one embodiment, when it is determined in step S420 that the battery pack to be discharged is at least one extended-range battery pack according to the discharge strategy;

[0095] Step S520 is to determine that at least one extended-range battery pack provides a power source for the electric vehicle motor, and specifically, may include the following steps:

[0096] S600: Obtaining power parameters of at least one range-extended battery pack;

[0097] S700: Determining, based on the electric energy parameter, whether the discharge power of the at least one range-extending battery pack is greater than the requirement of the electric vehicle motor;

[0098] If the discharge power of the at least one range-extending battery pack is greater than the requirement of the electric vehicle motor, S710 is executed: the at least one range-extending battery pack provides a power source for the electric vehicle motor, and the at least one range-extending battery pack charges the power battery pack.

[0099] Specifically, the step of charging the power battery pack by the at least one extended-range battery pack includes:

[0100] Obtaining battery pack parameters of the power battery pack;

[0101] Obtaining the output voltage / current of the at least one range-extended battery pack;

[0102] The output voltage / current of the at least one range-extending battery pack is converted into the charging voltage / current of the power battery pack by a bidirectional DC / DC converter. In the above steps, that is, during normal driving, the range-extending battery pack provides power to the battery system while charging the power battery pack.

[0103] If the discharge power of the at least one extended-range battery pack is equal to the electric vehicle motor requirement, then S720: the at least one extended-range battery pack provides a power source for the electric vehicle motor. In the above steps, that is, during normal driving, the extended-range battery pack mainly works to provide power to the battery system.

[0104] The above strategy gives priority to the discharge power of the extended-range battery pack. The strategy of giving priority to the power battery pack is similar to the above strategy and will not be repeated here.

[0105] The preset discharge strategy may also include setting a discharge mode for each extended-range battery pack, such as an average discharge mode for each extended-range battery pack, a sequential discharge mode for each extended-range battery pack, etc. For example, the average discharge mode for each extended-range battery pack may be to first release the extended-range battery pack with a higher SOC based on the SOC state of each extended-range battery pack, while meeting the average load power of the electric vehicle power system. When the SOC of the extended-range battery pack with the highest SOC after discharge reaches the same level as the extended-range battery pack with the next highest SOC, all extended-range battery packs with the same SOC will evenly share the discharge power of the average load power of the electric vehicle power system, and so on.

[0106] The sequential discharge mode of each extended-range battery pack is based on the SOC state of each extended-range battery pack. Under the condition of meeting the average load power of the electric vehicle's power system, the extended-range battery pack with the lowest SOC will release energy first, and so on. In other words, as much as possible of the extended-range battery packs are kept in a fully charged state, so that the number of uncharged extended-range battery packs is minimized. In other words, the extended-range batteries are kept in a fully charged or discharged state as much as possible. In this way, when batteries are swapped, the maximum capacity of the entire electric vehicle's battery system can be maintained by exchanging the minimum number of extended-range battery packs. In this mode, the extended-range battery packs are allowed to transfer power from the extended-range battery pack with a lower SOC to the extended-range battery pack with a higher SOC through the DC / DC control unit to achieve the above-mentioned goal of keeping the most extended-range batteries fully charged.

[0107] When the discharge power of at least one extended-range battery pack is greater than or equal to the demand of the electric vehicle motor, the power battery pack is in a standby state and does not need to participate in work, and the excess power of the extended-range battery pack can be absorbed by the power battery pack. Of course, when the excess charging power of the extended-range battery pack exceeds the charging current that the power battery can accept, the bidirectional DC / DC converter will reduce the conversion power and charge the power battery pack and provide load requirements with a current that does not exceed the power battery pack's tolerance to protect the power battery pack until the maximum voltage set for the power battery pack is reached. The above solution realizes the maximum use of the power of the extended-range battery pack.

[0108] If the discharge power of the at least one extended-range battery pack is less than the demand of the electric vehicle motor, then 730: the at least one extended-range battery pack and the power battery pack provide a power source for the electric vehicle motor. When the electric energy provided by the extended-range battery pack is insufficient to meet the demand of the electric vehicle motor, the power battery pack will participate in the power supply, and the two battery packs will provide a power source for the electric vehicle motor at the same time. This process can adopt a battery pack balanced discharge mode, that is, according to the average load power demand of the electric vehicle power system, the battery pack with a high SOC is discharged first, which can be a power battery pack or an extended-range battery pack, until the SOC of all battery packs is the same, and then the battery packs are discharged synchronously according to the effective capacity ratio of each battery pack, with the goal of all batteries being discharged together in the end. The main application scenario of this mode is to obtain the maximum endurance of the battery system, or it is mainly a charging mode rather than an application scenario for battery replacement.

[0109] When it is determined that the electric vehicle is in the charging mode, this step can be determined by detecting a signal such as a charger being connected to a charging port, and then the following steps are executed:

[0110] S310: Obtain a preset charging strategy; the charging strategy here can be set according to different usage scenarios, that is, the preset charging strategy can be a strategy for prioritizing charging the power battery pack or the extended-range battery pack, or a strategy for charging both battery packs at the same time.

[0111] S410: Determine the battery pack to be charged according to the charging strategy;

[0112] S510: The charger charges the battery pack determined to be charged based on the battery pack parameters. The charger charges the battery pack at a current that does not exceed the total charging current of the battery system configured in the entire vehicle (including the power battery pack and all extended range battery packs).

[0113] Specifically, the step of charging the battery pack to be charged by the charger in step S510 according to the battery pack parameters may further include:

[0114] S511: Determine the type of battery pack to be charged;

[0115] If it is a power battery pack, then S512: the charger charges the power battery pack;

[0116] If the battery pack is an extended-range battery pack, then S513: obtain battery pack parameters for the extended-range battery pack and convert the output voltage / current of the charger into the charging voltage / current of the extended-range battery pack via a bidirectional DC / DC converter. That is, when the electric vehicle stops and accepts charging from an external charger, the power provided by the charger can be used to charge the extended-range battery pack on the vehicle via the serially connected bidirectional DC / DC converter.

[0117] If two battery packs are charged simultaneously, the charging steps S512 and S513 are performed simultaneously.

[0118] The present invention can manage and set the output power and transmission direction of the bidirectional DC / DC converter between the range-extending battery pack and the power battery pack according to the number of configured range-extending battery packs, the input power of the charger, and the charging preference setting.

[0119] Furthermore, in some embodiments, the calculation unit M123 is configured to determine a target value of voltage / current required by the charging interface based on the parameters acquired by the data unit and the power parameters monitored by the monitoring unit;

[0120] The charger is configured to control the voltage / current required by the charging interface according to the target value of the voltage / current required by the charging interface determined by the calculation unit;

[0121] Before the charger determines the battery pack to be charged according to the battery pack parameters, the control method further includes the following steps:

[0122] The data unit obtains parameters of the charger and determines parameters of the battery pack to be charged, the parameters of the charger include the maximum output power of the charger, and the parameters of the battery pack include the maximum allowable charging power of the battery pack to be charged; it is judged whether the maximum output power of the charger is greater than or equal to the maximum allowable charging power of the battery pack to be charged. It should be noted that when it is determined that the battery pack to be charged is a battery pack, such as a power battery pack, or an extended-range battery pack, the maximum allowable charging power is the maximum allowable charging power of the battery pack; when it is determined that the battery pack to be charged is a plurality of battery packs, such as the battery pack to be charged includes a power battery pack and an extended-range battery pack, the maximum allowable charging power is the sum of the maximum allowable charging power of the power battery pack and the maximum allowable charging power of the extended-range battery pack, that is, the sum of the maximum allowable charging powers of the plurality of battery packs.

[0123] If the maximum output power of the charger is greater than or equal to the maximum allowable charging power of the battery pack to be charged, the calculation unit determines the target value of the voltage / current required by the charging interface based on the maximum allowable charging power of the battery pack to be charged obtained by the data unit; that is, the maximum output power of the charger can meet the maximum power charging of multiple battery packs to be charged at the same time. At this time, the charging power of the charger is set to the sum of the maximum allowable charging powers of all battery packs.

[0124] If the maximum output power of the charger is less than the maximum allowable charging power of the battery pack to be charged, the calculation unit determines the target value of the voltage / current required by the charging interface based on the maximum output power of the charger obtained by the data unit, and calculates the output power target value of each of the bidirectional DC / DC converters.

[0125] The above charging mode can be regarded as charging each battery pack in a fast charging mode. The purpose of adopting the above mode is to replenish the power of the battery system at the fastest speed under the maximum allowable charging power allowed by each battery pack.

[0126] Of course, the above-mentioned charging mode can be included in the preset charging strategy. In actual scenarios, other non-fast charging modes can be adopted. The non-fast charging mode is to charge each battery pack of the system at a lower power within the allowable charging time to reduce the load on the charger or the regional power grid, or to extend the battery life.

[0127] It should be noted that the charging power of the charger is the sum of the charging power of the power battery pack and all extended-range battery packs, and the charging power of the power battery pack and each extended-range battery pack can be dynamically adjusted at any time according to the set charging time, the residual capacity (SOC) of each battery, the health status (SOH) and temperature and other parameters. While meeting the charging time requirements, the charging power of the battery pack can be reduced as much as possible, so that it can work in a lower rate charging mode to extend the battery life.

[0128] In actual scenarios, part of the current provided by the charger will directly charge the power battery according to the range that the power battery pack can withstand. If there is any remaining current, it will be transferred to the range-extended battery pack through the bidirectional DC / DC converter connected between the range-extended battery pack and the power battery pack to charge the range-extended battery pack according to the set amount and not exceeding the charging current that the range-extended battery pack can withstand. Figure 1 As shown, P C The charging power of the charger, P CPB P is the power of charging the power battery pack. CEB1 To charge the first extended range battery pack power, P CEBn The charging power of the charger is equal to the sum of the power of the power battery pack and each range-extending battery pack (PC =P CPB +P CEB1 +…+…+P CEBn ).

[0129] In the control method of the present invention, the charging current of each relevant battery pack is distributed so as not to exceed the charging current that each battery pack can withstand. The charging strategy can be preset according to user preferences. That is, the charging strategy can be set to prioritize charging the power battery pack or the range-extending battery pack. It can also be set to a mode that charges the battery as quickly as possible, thereby achieving a control mode that prioritizes protecting battery life or charging the battery as quickly as possible, thereby controlling the conversion power of each bidirectional DC / DC converter.

[0130] For example, the default charging strategy is a charging mode that prioritizes the power battery pack. In this mode, the charger first charges the power battery pack before charging the range-extending battery pack.

[0131] If the maximum output charging power of the charger is less than the maximum allowable charging power acceptable to the power battery, the charger output charging power is set to the maximum output charging power of the charger, and the charging power of each extended-range battery pack is set to 0, that is, the total charging power of all extended-range batteries is equal to 0. The charger first charges the power battery pack. When the residual power percentage of the power battery pack is greater than or equal to the fast charge value default value (such as 90%), or when it has reached the constant voltage charging mode, the allowable charging power of the power battery pack begins to decrease. When the maximum allowable charging power of the power battery pack drops below the maximum output charging power of the charger, it means that the charger has excess power to charge the extended-range battery pack, so the charging power of each extended-range battery pack can be set to increase. At this time, the charging power of each extended-range battery pack can be set on average to one nth of the difference between the charger output charging power and the power battery pack charging power. Here, n represents the number of extended-range battery packs to be charged, that is, the extended-range battery packs to be charged are charged evenly. The extended-range batteries can also be charged in sequence, that is, the maximum allowable charging power of the extended-range battery pack with a high priority is set as the charging power of the extended-range battery pack, until the sum of the charging power of all extended-range battery packs and the charging power of the power battery equals the charger output charging power.

[0132] If the power battery pack is fully charged, that is, when the charging power of the power battery pack is 0, the charging power output by the charger is set to the sum of the charging powers of all the extended-range battery packs. During all processes, the battery information processing module and each DC / DC control unit charges each corresponding extended-range battery pack at the set charging power.

[0133] If the maximum output charging power of the charger is greater than the maximum allowable charging power of the power battery pack, because the charger output charging power is equal to the sum of the charging power of the power battery pack and the charging power of all extended-range battery packs, the charging power of the power battery pack can be set to the maximum allowable charging power of the power battery pack, and the sum of the charging power of all extended-range battery packs is equal to the difference between the maximum output charging power of the charger and the charging power of the power battery pack.

[0134] Because the total charging power of all extended-range battery packs is greater than zero, the charging power of each extended-range battery pack can be set to an average of one-nth of the total charging power of all extended-range battery packs, where n represents the number of extended-range battery packs to be charged. This means that all extended-range battery packs to be charged are charged evenly. Alternatively, the extended-range battery packs can be charged sequentially, with the charging power of higher-priority extended-range battery packs being prioritized at their maximum allowable charging power. The total charging power of all extended-range battery packs equals the total maximum allowable charging power of all extended-range battery packs until the sum of the charging power of all extended-range battery packs and the charging power of the power battery pack equals the charging power output by the charger. If the power battery pack is fully charged (i.e., the charging power of the power battery pack is zero), the charger's output charging power is set to the larger or smaller of the total charging power of all extended-range battery packs. Throughout this process, the battery information processing module and each DC / DC control unit charge each extended-range battery pack at the set charging power.

[0135] If the preset charging strategy is the range-extended battery pack priority charging mode, in this mode the charger will first charge the range-extended battery pack before charging the power battery pack.

[0136] Because the charging power output by the charger is equal to the sum of the charging power of the power battery pack and the charging power of all extended-range battery packs:

[0137] If the maximum output charging power of the charger is less than or equal to the sum of the maximum allowable charging power of all extended-range battery packs, it means that the maximum output charging power of the charger is less than the sum of the maximum allowable charging power that the extended-range battery packs can accept. At this time, the charging power of the charger will be used entirely to charge the extended-range battery, and the charging power of the power battery pack will be 0.

[0138] Set the charger output charging power to the maximum output charging power of the charger. If all the extended range battery packs are charged evenly, then

[0139] The charging power of each extended-range battery pack can be set to an average of one-nth of the maximum output charging power of the charger, where n represents the number of extended-range battery packs to be charged.

[0140] The charger can also charge each extended-range battery pack in sequence, that is, the charging power of the extended-range battery pack with a higher priority is set to its maximum allowable charging power, and so on, until the charging power of all extended-range battery packs is equal to the maximum allowable charging power of the charger, that is, the total charging power of all extended-range battery packs is equal to the maximum output charging power of the charger.

[0141] In this mode, the charger first charges the extended-range battery pack. Then, as the extended-range battery packs are fully charged in sequence or their residual power percentage reaches the default value and the battery temperature and other factors are taken into consideration, the charging power of each extended-range battery pack changes, that is, the total charging power of the extended-range battery pack changes. If the maximum output charging power of the charger is greater than the total charging power of the extended-range battery packs, that is, the charging power of the charger is sufficient to charge all the extended-range battery packs and there is still room for it, the excess charging capacity can be used to start charging the power battery pack. At this time, the charging power of the power battery pack is equal to the difference between the charger output charging power and the total charging power of the extended-range battery pack, and the charger output charging power is still equal to the charger's maximum output charging power.

[0142] As the total charging power of the extended-range battery packs continues to decrease, the charging power of the power battery packs will increase in a complementary manner. When the charging power of the power battery packs increases to the maximum allowable charging power of the power battery packs, the charger output charging power setting must be reduced. In other words, the charger output charging power must be equal to the sum of the charging power of the power battery packs and the charging power of all extended-range battery packs to avoid battery damage. Throughout this process, the battery information processing module and each DC / DC control unit charge each extended-range battery pack at the set charging power.

[0143] If the maximum output charging power of the charger is greater than the sum of the maximum allowable charging power of all extended-range battery packs, but less than the sum of the maximum allowable charging power of the power battery pack and the maximum allowable charging power of all extended-range battery packs, that is, the charging power of the charger still has margin besides charging the extended-range battery pack to be charged at the maximum power, but this margin is not enough to charge the power battery pack at the maximum power at the same time, the charging power of each extended-range battery pack can still be set to its maximum allowable charging power, and the charger output charging power is set to its maximum output charging power. At this time, the charging power of the power battery pack is equal to the difference between the charger output charging power and the sum of the maximum allowable charging power of all extended-range battery packs.

[0144] If the maximum output charging power of the charger is greater than the sum of the maximum allowable charging power of the power battery pack and the maximum allowable charging power of all extended-range battery packs, the following settings can be used:

[0145] The charging power of the power battery pack is its maximum allowable charging power;

[0146] The charging power of each extended-range battery pack is its maximum allowable charging power;

[0147] The charging power output by the charger is equal to the sum of the charging power of the power battery pack and the charging power of all extended-range battery packs.

[0148] The functional implementation of each functional unit of the control module in the electric vehicle battery system of the embodiment can be implemented by adopting the specific implementation of each step in the above control method. For example, the data unit M121, the battery pack control unit M122, the calculation unit M123 and the DC / DC control unit M20 n The functions of the present invention can be achieved by using the specific implementations of steps S100 to S510, S100 to S710, S100 to S720, or S100 to S730, respectively. The present invention can effectively reduce the battery capacity of typical electric vehicles and flexibly meet specific requirements for longer battery life. This can significantly reduce overall battery usage in the electric vehicle industry, utilizing increasingly scarce battery resources in the most economical manner. This presents an effective and innovative approach to configuring and managing electric vehicle battery systems.

[0149] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A control method for an electric vehicle battery system, characterized in that: Applicable to an electric vehicle battery system, the battery system is provided with a load interface connected to a load, and a charging interface connected to a charger, including: Power battery pack; at least one bidirectional DC / DC converter; At least one range-extended battery pack interface, each of which can be connected to a range-extended battery pack, and a bidirectional DC / DC converter is provided between each range-extended battery pack and the power battery pack, for converting a DC input voltage / current into an output voltage / current compatible with the charging voltage / current of the power battery pack or the range-extended battery pack; When at least one of the range-extending battery pack interfaces is connected to a range-extending battery pack, the power battery pack and the range-extending battery pack form a parallel output; The electric vehicle battery system further includes a charging interface for connecting to charging power, wherein the charging interface is respectively connected to the power battery pack and each of the bidirectional DC / DC converters; The system further includes a battery information processing module connected to the power battery pack, each of the bidirectional DC / DC converters, and the charging interface; The battery information processing module includes a data unit, a monitoring unit and a calculation unit; The data unit is used to obtain electric vehicle parameters, battery pack parameters of the power battery pack, battery pack parameters of each of the extended-range battery packs and / or parameters of the charging interface; The monitoring unit is used to monitor the power parameters of the power battery pack, the power parameters corresponding to each of the extended-range battery packs and / or the power parameters of the charging interface; The calculation unit is used to determine the target value and transmission direction of the output voltage / current of each bidirectional DC / DC converter according to the parameters obtained by the data unit and the power parameters monitored by the monitoring unit; The electric vehicle battery system is connected to at least one range-extending battery pack, and the control method comprises the following steps: Get electric vehicle parameters; determining the mode of the electric vehicle according to the electric vehicle parameters; When it is determined that the electric vehicle is in the charging mode, Get the preset charging strategy; Determining the battery pack to be charged according to the charging strategy; The charger charges the battery pack to be charged according to the battery pack parameters; When it is determined that the electric vehicle is in a driving mode, the electric vehicle battery system provides a power source for the electric vehicle motor; The calculation unit is used to determine a target value of voltage / current required by the charging interface based on the parameters obtained by the data unit and the electric energy parameters monitored by the monitoring unit; The charger is configured to control the voltage / current required by the charging interface according to the target value of the voltage / current required by the charging interface determined by the calculation unit; Before the charger determines the battery pack to be charged according to the battery pack parameters, the control method further includes the steps of: The data unit obtains parameters of the charger and determines parameters of the battery pack to be charged, wherein the parameters of the charger include the maximum output power of the charger, and the parameters of the battery pack include determining the maximum allowable charging power of the battery pack to be charged; Determine whether the maximum output power of the charger is greater than or equal to the maximum allowable charging power of the battery pack to be charged; If the maximum output power of the charger is greater than or equal to the maximum allowable charging power of the battery pack to be charged, the calculation unit determines the target value of the voltage / current required by the charging interface according to the maximum allowable charging power of the battery pack to be charged obtained by the data unit; and / or If the maximum output power of the charger is less than the maximum allowable charging power of the battery pack to be charged, the calculation unit determines the target value of the voltage / current required by the charging interface based on the maximum output power of the charger obtained by the data unit, and calculates the output power target value of each of the bidirectional DC / DC converters.

2. The control method of the electric vehicle battery system according to claim 1, characterized in that: The charger determines the battery pack to be charged according to the battery pack parameters, and the charging steps include: Determine the type of battery pack to be charged; If it is a power battery pack, the charger charges the power battery pack; If it is an extended-range battery pack, the battery pack parameters of the extended-range battery pack are obtained, and the output voltage / current of the charger is converted into the charging voltage / current of the extended-range battery pack through a bidirectional DC / DC converter.

3. The control method according to claim 1, wherein: The electric vehicle battery system provides a power source for the electric vehicle motor, comprising: Get the preset discharge strategy; Determining the battery pack to be discharged according to the discharge strategy; The battery pack to be discharged is determined to provide a power source for the electric vehicle motor.

4. The control method according to claim 3, characterized in that: When it is determined according to the discharge strategy that the battery pack to be discharged is at least one extended-range battery pack; The steps of determining at least one extended range battery pack to provide a power source for the electric vehicle motor include: Obtaining an electric energy parameter of at least one range-extending battery pack, and determining whether a discharge power of the at least one range-extending battery pack is greater than a requirement of a motor of the electric vehicle based on the electric energy parameter; If the discharge power of the at least one range-extending battery pack is greater than the requirement of the electric vehicle motor, the at least one range-extending battery pack provides a power source for the electric vehicle motor, and The at least one range-extending battery pack charges the power battery pack; and / or If the discharge power of the at least one range-extending battery pack is less than the requirement of the electric vehicle motor, the at least one range-extending battery pack and the power battery pack provide a power source for the electric vehicle motor.

5. The control method according to claim 4, characterized in that: If the discharge power of the at least one range-extending battery pack is equal to the requirement of the electric vehicle motor, the at least one range-extending battery pack provides a power source for the electric vehicle motor.

6. The control method according to claim 5, characterized in that: The step of charging the power battery pack by the at least one extended-range battery pack includes: Obtaining battery pack parameters of the power battery pack; Obtaining the output voltage / current of the at least one range-extended battery pack; The output voltage / current of the at least one range-extending battery pack is converted into the charging voltage / current of the power battery pack by a bidirectional DC / DC converter.

7. The control method of the electric vehicle battery system according to claim 1, characterized in that: The bidirectional DC / DC converter includes a DC / DC control unit; The DC / DC control unit is used to control the output voltage / current and transmission direction of the bidirectional DC / DC converter according to the target value of the output voltage / current determined by the calculation unit.

8. The control method of the electric vehicle battery system according to claim 1, characterized in that: The bidirectional DC / DC converter is a digital DC / DC converter.

9. The control method of the electric vehicle battery system according to claim 1, characterized in that: The power battery pack adopts power type battery or capacity type battery; The range-extending battery pack adopts a power-type battery or a capacity-type battery.

Images