Power battery system, electric vehicle, and control method

Abstract

Provided are a power battery system, an electric vehicle, and a control method. The power battery system comprises at least two power batteries, a switching module (130), and a control module (140), the power batteries being connected to the switching module, and the switching module being connected to the control module. The switching module, under the control of the control module, enables the power battery system to enter the following modes: a series charging mode, in which the at least two power batteries are connected in series to a charging end, a target power battery supplies power to the load of the entire vehicle, and the target power battery is at least one of the at least two power batteries; a partial discharge mode, in which the at least two power batteries are connected in parallel to a load end of the entire vehicle, and a power battery other than the target power battery supplies power to the load of the entire vehicle; and a parallel discharge mode, in which the at least two power batteries are connected in parallel to the load end of the entire vehicle, and the at least two power batteries simultaneously supply power to the load of the entire vehicle. By means of the control module controlling the action of the switching module, rapid charging and various requirements for load power supply are achieved without requiring a DC-DC voltage converter, which reduces the cost of the entire vehicle, and improves the electromagnetic compatibility of an electric control system of the entire vehicle.

Description

Power battery system, electric vehicle and control method

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on August 17, 2023, with application number 202311039756.2. The entire contents of the above application are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of power battery technology, for example, to a power battery system, an electric vehicle, and a control method. Background Art

[0003] As the number of new energy electric vehicles increases, the disadvantage of long charging times (fast charging takes about an hour) is becoming increasingly prominent, becoming a key challenge to the popularization of electric vehicles. Therefore, high-rate, ultra-fast charging (supercharging) batteries that "make charging as fast as refueling" have become a key development direction in the new energy industry.

[0004] To achieve supercharging of electric vehicles, not only do they need supercharging batteries, but they also need charging piles with higher charging power. Under the constraints of limiting the charging current to limit loads such as motors and electronic controls, as well as the size of cables, some car manufacturers and charging pile manufacturers have adopted a supercharging solution that combines a high-voltage (approximately 550V to 930V) vehicle electrical system architecture with a high-voltage charging pile. However, most electric vehicles currently still use a low-voltage (approximately 230V to 450V) electrical system architecture. To enable supercharging of such vehicles, a theoretically feasible approach is to essentially retain the original low-voltage system architecture for the entire vehicle while integrating a new high-voltage battery charging solution. After charging, a DC-DC (Direct Current-Direct Current, DC-DC) voltage converter is used to convert the battery system's 900V high voltage into a low voltage of 450V for use by the vehicle's loads, thereby improving the compatibility of electric vehicles in terms of charging input and discharge output. However, DC-DC voltage converters take up a lot of space, are expensive, and require a water-cooled plate for heat dissipation. Moreover, the inductive components in the DC-DC voltage converters generate strong electromagnetic interference, which leads to poor electromagnetic compatibility of the vehicle's electronic control system and makes it prone to failure. Therefore, the practical feasibility of this approach is not high.

[0005] Summary of the Invention

[0006] The present application provides a power battery system, an electric vehicle, and a control method, which can not only realize the smooth switching of the vehicle electrical system architecture between high and low voltages, but also reduce the cost of the vehicle and improve the electromagnetic compatibility of the vehicle electronic control system, and has high practical feasibility.

[0007] In a first aspect, the present application provides a power battery system, comprising: at least two power batteries, a switching module, and a control module;

[0008] The at least two power batteries are connected to the switching module, and the switching module is connected to the control module;

[0009] The switching module is configured to operate under the control of the control module, so that the power battery system enters a series charging mode, a partial discharge mode, or a parallel discharge mode:

[0010] In the series charging mode, the at least two power batteries are connected in series to a charging terminal, and a target power battery supplies power to the vehicle load, and the target power battery is at least one of the at least two power batteries;

[0011] In the partial discharge mode, the at least two power batteries are connected in parallel to the vehicle load, and power batteries other than the target power battery supply power to the vehicle load;

[0012] In the parallel discharge mode, the at least two power batteries are arranged to be connected in parallel to the vehicle load end, and the at least two power batteries supply power to the vehicle load.

[0013] Optionally, the switching module is further configured to operate under the control of the control module, so that the power battery system enters:

[0014] A parallel charging mode, in which the at least two power batteries are connected in parallel to the charging terminal.

[0015] Optionally, the at least two power batteries are two power batteries, namely a first power battery and a second power battery;

[0016] The switching module includes a first switching switch, a second switching switch, a third switching switch, a fourth switching switch, a fifth switching switch and a unidirectional diode;

[0017] The first end of the first switch is configured to be connected to the positive electrode of the charging terminal, and the second end of the first switch is connected to the positive electrode of the first power battery;

[0018] The negative electrode of the first power battery is connected to the first end of the second switch, and the second end of the second switch is connected to the positive electrode of the second power battery;

[0019] The negative electrode of the second power battery is configured to be connected to at least one of the negative electrode of the load end of the vehicle and the negative electrode of the charging end;

[0020] The first end of the third switch is connected to the second end of the first switch, the second end of the third switch is connected to the first end of the fourth switch, the second end of the fourth switch is connected to the positive electrode of the second power battery, and the first end of the fourth switch is configured to be connected to the positive electrode of the vehicle load terminal;

[0021] A first end of the fifth switch is connected to the negative electrode of the first power battery, and a second end of the fifth switch is configured to be connected to the negative electrode of the vehicle load end;

[0022] The anode of the one-way diode is connected to the positive electrode of the second power battery, and the cathode of the one-way diode is connected to the second end of the third switch.

[0023] The switching module further includes a sixth switching switch, a seventh switching switch and a pre-charging resistor;

[0024] The first end of the sixth switch is connected to the second end of the third switch, and the second end of the sixth switch is configured to be connected to the positive electrode of the vehicle load end;

[0025] The pre-charging resistor and the seventh switch are connected in series between the second end of the third switch and the positive electrode of the vehicle load end.

[0026] Optionally, the switching module further includes an eighth switching switch, a first end of the eighth switching switch is connected to the second end of the fifth switching switch, and a second end of the eighth switching switch is configured to be connected to the negative pole of the vehicle load end.

[0027] Optionally, the power battery system further includes a fuse, which is connected in series to a wire connected to the positive electrode of the power battery.

[0028] Optionally, the control module includes:

[0029] A charging category identification unit, configured to identify the charging category of the charging pile when the electric vehicle interacts with the charging pile;

[0030] a voltage value acquiring unit, configured to acquire voltage values ​​of the at least two power batteries in response to a high voltage request instruction from a vehicle controller;

[0031] a voltage difference calculation unit, configured to calculate a difference between a voltage value of another power battery among the at least two power batteries and a voltage value of a target power battery;

[0032] a judgment unit configured to judge whether a difference between the voltage value of the other power battery and the voltage value of the target power battery is greater than a preset value;

[0033] A mode switching control unit is configured to control the switching module to switch the power battery system to a series charging mode in response to the charging category being fast charging, control the switching module to switch the power battery system to a parallel charging mode in response to the charging category being normal charging, control the switching module to switch the power battery system to a partial discharge mode in response to the presence of a difference greater than a preset value, and control the switching module to switch the power battery system to a parallel discharge mode in response to the absence of a difference greater than the preset value.

[0034] In a second aspect, the present application also provides an electric vehicle, comprising the power battery system provided in the first aspect of the present application.

[0035] In a third aspect, the present application further provides a control method for a power battery system, comprising:

[0036] When the electric vehicle interacts with the charging pile, the control module in the power battery system identifies the charging type of the charging pile;

[0037] In response to the charging category being fast charging, the control module controls the switching module in the power battery system to switch the power battery system to a series charging mode; in the series charging mode, at least two power batteries in the power battery system are connected in series to a charging terminal, and a target power battery supplies power to a vehicle load, the target power battery being at least one of the at least two power batteries;

[0038] In response to the high-voltage request instruction of the vehicle controller, the control module controls the operation of the switching module to switch the power battery system to a partial discharge mode or a parallel discharge mode; in the partial discharge mode, the at least two power batteries are connected in parallel to the vehicle load end, and the power batteries other than the target power battery supply power to the vehicle load; in the parallel discharge mode, the at least two power batteries are connected in parallel to the vehicle load end, and the at least two power batteries supply power to the vehicle load.

[0039] Optionally, in response to a high voltage request instruction from a vehicle controller, the control module controls the switching module to switch the power battery system to a partial discharge mode or a parallel discharge mode, including:

[0040] In response to a high-voltage request instruction from a vehicle controller, obtaining voltage values ​​of the at least two power batteries;

[0041] Calculating a difference between a voltage value of another power battery among the at least two power batteries and a voltage value of a target power battery;

[0042] determining whether a difference between the voltage value of the other power battery and the voltage value of the target power battery is greater than a preset value;

[0043] In response to a difference greater than a preset value, the switching module is controlled to operate to switch the power battery system to a partial discharge mode; in the partial discharge mode, the at least two power batteries are connected in parallel to the vehicle load terminal, and power batteries other than the target power battery supply power to the vehicle load until the voltage of the power batteries other than the target power battery drops to within a preset range of the voltage of the target power battery;

[0044] In response to the absence of a difference greater than a preset value, the switching module is controlled to operate and switch the power battery system to a parallel discharge mode. In the parallel discharge mode, the at least two power batteries are connected in parallel to the vehicle load end, and the at least two power batteries supply power to the vehicle load.

[0045] Optionally, the control method of the power battery system further includes:

[0046] In response to the charging category being normal charging, the control module controls the switching module to switch the power battery system to a parallel charging mode; in the parallel charging mode, the at least two power batteries are connected in parallel to the charging end.

[0047] Optionally, switching the power battery system to a series charging mode includes:

[0048] closing the fourth switch in the switching module, opening the third switch in the switching module, opening the fifth switch in the switching module, closing the second switch in the switching module, and closing the first switch in the switching module;

[0049] Switching the power battery system to a partial discharge mode includes:

[0050] Opening the first switch in the switching module, opening the second switch in the switching module, closing the third switch in the switching module, opening the fourth switch in the switching module, and closing the fifth switch in the switching module;

[0051] Switching the power battery system to a parallel charging mode includes:

[0052] closing the fourth switch in the switching module, closing the third switch in the switching module, closing the fifth switch in the switching module, opening the second switch in the switching module, and closing the first switch in the switching module;

[0053] Switching the power battery system to a parallel discharge mode includes:

[0054] Opening the first switch in the switching module, opening the second switch in the switching module, closing the third switch in the switching module, closing the fourth switch in the switching module, and closing the fifth switch in the switching module;

[0055] Wherein, the switching module further includes a unidirectional diode;

[0056] A first end of the first switch is connected to the positive electrode of the charging end, and a second end of the first switch is connected to the positive electrode of the first power battery among the at least two power batteries;

[0057] A first end of the second switch is connected to the negative electrode of the first power battery, and a second end of the second switch is connected to the positive electrode of the second power battery among the at least two power batteries;

[0058] The negative electrode of the second power battery is connected to at least one of the negative electrode of the load end of the vehicle and the negative electrode of the charging end;

[0059] The first end of the third switch is connected to the second end of the first switch, the second end of the third switch is connected to the first end of the fourth switch, the second end of the fourth switch is connected to the positive electrode of the second power battery, and the first end of the fourth switch is connected to the positive electrode of the vehicle load end;

[0060] A first end of the fifth switch is connected to the negative electrode of the first power battery, and a second end of the fifth switch is connected to the negative electrode of the vehicle load end;

[0061] The anode of the one-way diode is connected to the positive electrode of the second power battery, and the cathode of the one-way diode is connected to the second end of the third switch.

[0062] Optionally, the method further includes:

[0063] During the process of supplying power to the vehicle load, the seventh switch in the switching module is closed, and the sixth switch in the switching module is opened. After the voltage value of the load capacitor in the vehicle load reaches a preset voltage value, the seventh switch is opened and the sixth switch is closed;

[0064] Wherein, the switching module further includes a pre-charging resistor;

[0065] The first end of the sixth switch is connected to the second end of the third switch, and the second end of the sixth switch is connected to the positive electrode of the vehicle load end;

[0066] The pre-charging resistor and the seventh switch are connected in series between the second end of the third switch and the positive electrode of the vehicle load end. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The present application will be described below with reference to the accompanying drawings and embodiments.

[0068] FIG1 is a schematic structural diagram of a power battery system provided in an embodiment of the present application;

[0069] FIG2 is a circuit diagram of a power battery system provided in an embodiment of the present application;

[0070] FIG3 is a circuit connection diagram in series charging mode;

[0071] FIG4 is a circuit connection diagram in partial discharge mode;

[0072] FIG5 is a circuit connection diagram in parallel charging mode;

[0073] FIG6 is a circuit connection diagram in parallel discharge mode;

[0074] FIG7 is a circuit connection diagram of the pre-filling circuit;

[0075] FIG8 is a schematic structural diagram of a control module provided in an embodiment of the present application;

[0076] FIG9A is a flow chart of a control method for a power battery system provided in an embodiment of the present application;

[0077] FIG9B is a flowchart of another method for controlling a power battery system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0078] The following will illustrate the technical solutions of the embodiments of the present application with reference to the accompanying drawings. The embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of this application.

[0079] In this application, unless otherwise clearly specified and defined, the terms "first" and "second" are only used to distinguish in description and have no special meaning.

[0080] An embodiment of the present application provides a power battery system. FIG1 is a schematic structural diagram of a power battery system provided in an embodiment of the present application. As shown in FIG1 , the power battery system includes: a first power battery 110, a second power battery 120, a switching module 130, and a control module 140. This embodiment uses two power batteries as an example for description. In other embodiments, the power battery system may also include multiple power batteries, which is not limited in this application.

[0081] The first power battery 110 and the second power battery 120 are both connected to the switching module 130 , and the switching module 130 is connected to the control module 140 .

[0082] The switching module 130 operates under the control of the control module 140 so that the power battery system can switch between the following modes.

[0083] Series charging mode. In the series charging mode, the first power battery 110 and the second power battery 120 are connected in series to the charging terminal, and the target power battery supplies power to the vehicle load. The target power battery is at least one of the two power batteries. For example, the target power battery is the second power battery 120. In other embodiments of the present application, the number of power batteries in the power battery system can also be multiple, and the target power battery can be one or more of the multiple power batteries. The embodiments of the present application are not limited here. When the electric vehicle interacts with the charging pile, the control module 140 identifies the charging category of the charging pile. When the charging category is fast charging (for example, the charging terminal voltage is high voltage, about 550V-930V), the control module 140 controls the switching module 130 to operate and switch the power battery system to the series charging mode. In the series charging mode, the first power battery 110 and the second power battery 120 are charged in series to achieve high-voltage super-fast charging. The second power battery 120 is connected to the vehicle load terminal of the electric vehicle to supply power to the vehicle load (for example, the voltage required by the vehicle load is about 230V-450V). Because the second power battery 120 supplies power to the entire vehicle load during charging, the charging current of the second power battery 120 is lower than that of the first power battery 110. Consequently, the first power battery 110 is fully charged before the second power battery 120. Since the two power batteries are charged in series, when the first power battery 110 is fully charged, the control module 140 controls the switching module 130 to disconnect the charging terminal, halting charging. As a result, after rapid charging is complete, the voltage of the first power battery 110 is higher than that of the second power battery 120.

[0084] Partial discharge mode: In partial discharge mode, the first power battery 110 and the second power battery 120 are connected in parallel to the vehicle load, and power batteries other than the target power battery (i.e., the first power battery 110) power the vehicle load. As previously mentioned, after fast charging, the voltage of the first power battery 110 is higher than that of the second power battery 120. If the first power battery 110 and the second power battery 120 are directly connected in parallel to power the vehicle load, the first power battery 110 will replenish power from the second power battery 120, resulting in a very large current and causing a short circuit. If only the first power battery 110 is used for discharge, the voltage of the first power battery 110 will continue to drop, and the voltage difference between the first power battery 110 and the second power battery 120 will increase, affecting battery consistency. In this embodiment of the present application, upon receiving a command for applying high voltage to the vehicle load and the voltage differential between the first power battery 110 and the second power battery 120 is greater than a preset value (e.g., 3V), the control module 140 controls the switching module 130 to switch the power battery system to a partial discharge mode. In this partial discharge mode, the first power battery 110 and the second power battery 120 are connected in parallel to the vehicle load, with only the first power battery 110 supplying power to the vehicle load until the voltage of the first power battery 110 drops to within a preset range of the voltage of the second power battery 120 (e.g., the voltage differential between the first power battery 110 and the second power battery 120 is less than 3V), thereby aligning the voltages of the first power battery 110 and the second power battery 120. After the voltage differential between the first power battery 110 and the second power battery 120 is less than or equal to the preset value, the first power battery 110 and the second power battery 120 can be connected in parallel to supply power to the vehicle load.

[0085] Parallel charging mode: In parallel charging mode, the first power battery 110 and the second power battery 120 are connected in parallel to the charging terminal. For example, when the electric vehicle interacts with the charging pile, the control module 140 identifies the charging type of the charging pile. When the charging type is normal charging (for example, the charging terminal voltage is 230V-450V), the control module 140 controls the switching module 130 to switch the power battery system to parallel charging mode. In parallel charging mode, the first power battery 110 and the second power battery 120 are connected in parallel to the charging terminal to achieve normal fast charging. In addition, the charging terminal can also directly power the entire vehicle load.

[0086] Parallel discharge mode: In parallel discharge mode, the first power battery 110 and the second power battery 120 are connected in parallel to the vehicle load, and the first power battery 110 and the second power battery 120 supply power to the vehicle load. For example, upon receiving a command to apply high voltage to the vehicle load, and the difference between the voltage of the first power battery 110 and the voltage of the second power battery 120 is less than or equal to a preset value, the control module 140 controls the switching module 130 to operate, switching the power battery system to parallel discharge mode. In parallel discharge mode, the first power battery 110 and the second power battery 120 are connected in parallel to the vehicle load, and the first power battery 110 and the second power battery 120 supply power to the vehicle load, thereby ensuring battery consistency between the first power battery 110 and the second power battery 120.

[0087] The power battery system provided in an embodiment of the present application includes at least two power batteries, a switching module, and a control module. The power batteries are connected to the switching module, which is connected to the control module. The switching module operates under the control of the control module, so that the power battery system can enter the following modes: a series charging mode, in which at least two power batteries are connected in series to the charging terminal, and a target power battery supplies power to the vehicle load, and the target power battery is at least one of the at least two power batteries; a partial discharge mode, in which at least two power batteries are connected in parallel to the vehicle load terminal, and power batteries other than the target power battery supply power to the vehicle load; and a parallel discharge mode, in which at least two power batteries are connected in parallel to the vehicle load terminal, and at least two power batteries supply power to the vehicle load. The present application controls the operation of the switching module by the control module to achieve multiple requirements of fast charging and load power supply, without the need for a DC-DC voltage converter, thereby reducing the cost of the vehicle and improving the electromagnetic compatibility of the vehicle's electronic control system.

[0088] FIG2 is a circuit diagram of a power battery system provided in an embodiment of the present application. As shown in FIG2 , the switching module 130 includes a first switch RL3 , a second switch RL6 , a third switch RL8 , a fourth switch RL5 , a fifth switch RL7 and a unidirectional diode D1 .

[0089] The first end of the first switching switch RL3 is connected to the positive terminal DC+ of the charging terminal, and the second end of the first switching switch RL3 is connected to the positive terminal of the first power battery 110. The negative terminal of the first power battery 110 is connected to the first end of the second switching switch RL6, and the second end of the second switching switch RL6 is connected to the positive terminal of the second power battery 120. The negative terminal of the second power battery 120 is connected to the negative terminal HV- of the vehicle load terminal and / or the negative terminal DC- of the charging terminal. The first end of the third switching switch RL8 is connected to the second end of the first switching switch RL3, and the second end of the third switching switch RL8 is connected to the first end of the fourth switching switch RL5. The second end of the fourth switching switch RL5 is connected to the positive terminal of the second power battery 120, and the first end of the fourth switching switch RL5 is connected to the positive terminal HV+ of the vehicle load terminal. The first end of the fifth switching switch RL7 is connected to the negative terminal of the first power battery 110, and the second end of the fifth switching switch RL7 is connected to the negative terminal HV- of the vehicle load terminal.

[0090] As shown in FIG2 , the anode of the one-way diode D1 is connected to the positive electrode of the second power battery 120 , and the cathode of the one-way diode D1 is connected to the second end of the third switch RL8 .

[0091] As shown in Figure 2, the switching module 130 also includes a sixth switching switch RL1, a seventh switching switch RL2 and a pre-charging resistor R1. The first end of the sixth switching switch RL1 is connected to the second end of the third switching switch RL8, and the second end of the sixth switching switch RL1 is connected to the positive electrode HV+ of the vehicle load end. The pre-charging resistor R1 and the seventh switching switch RL2 are connected in series between the second end of the third switching switch RL8 and the positive electrode HV+ of the vehicle load end. Exemplarily, the first end of the pre-charging resistor R1 is connected to the second end of the third switching switch RL8, the second end of the pre-charging resistor R1 is connected to the first end of the seventh switching switch RL2, and the second end of the seventh switching switch RL2 is connected to the positive electrode HV+ of the vehicle load end.

[0092] As shown in FIG2 , the switching module 130 further includes an eighth switch RL4 . A first end of the eighth switch RL4 is connected to the second end of the fifth switch RL7 , and a second end of the eighth switch RL4 is connected to the negative electrode HV- of the vehicle load terminal. The eighth switch RL4 can function as a main grounding switch and is a normally closed switch.

[0093] The switching switch in the above embodiment may be a relay switch, and the control end of the relay switch is connected to the control module 140 .

[0094] As shown in Figure 2, the power battery system also includes fuses Fuse1 and Fuse2. Fuse1 is connected in series to the wire connected to the positive electrode of the first power battery 110, and fuse Fuse2 is connected in series to the wire connected to the positive electrode of the second power battery 120. The fuses serve as current limiting protection. When the current in the circuit is too large, the fuses burn out and disconnect the circuit.

[0095] Figure 3 is a circuit connection diagram for series charging mode. As shown in Figure 3, for example, when the control module 140 identifies the charging pile as fast charging, it controls the closing of the fourth switch RL5 and the sixth switch RL1, the opening of the seventh switch RL2, the opening of the third switch RL8, the opening of the fifth switch RL7, the closing of the second switch RL6, and the closing of the first switch RL3, thus entering series charging mode. In series charging mode, the first power battery 110 and the second power battery 120 are connected in series for fast charging, with the second power battery 120 supplying power to the vehicle load. In the figure, the solid line represents the charging circuit, and the dashed line represents the portion of the power supply circuit that is used independently and not shared with the charging circuit.

[0096] FIG4 is a circuit connection diagram in partial discharge mode. As shown in FIG4, for example, when a high voltage instruction is received for the entire vehicle load, and the voltage difference between the first power battery 110 and the second power battery 120 is greater than a preset value (for example, greater than 3V), the control module 140 controls the first switch RL3 to be disconnected, the second switch RL6 to be disconnected, the third switch RL8 to be closed, the fourth switch RL5 to be disconnected, the fifth switch RL7 to be closed, the sixth switch RL1 to be closed, and the seventh switch RL2 to be disconnected, thus entering partial discharge mode. In the partial discharge mode, the first power battery 110 and the second power battery 120 are connected in parallel to the vehicle load. Because the cathode voltage of the one-way diode D1 is higher than the anode voltage, the one-way diode D1 does not conduct, and only the first power battery 110 supplies power to the vehicle load until the voltage of the first power battery 110 drops to within a preset range of the voltage of the second power battery 120 (for example, the voltage difference between the first power battery 110 and the second power battery 120 is less than 3V), bringing the voltages of the first power battery 110 and the second power battery 120 closer together. In this embodiment of the present invention, after the voltage of the first power battery 110 drops to within the preset range of the voltage of the second power battery 120, the one-way diode D1 conducts, the discharge circuit of the second power battery 120 is opened, and the first power battery 110 and the second power battery 120 discharge in parallel.

[0097] FIG5 is a circuit connection diagram in parallel charging mode. As shown in FIG5 , illustratively, when an electric vehicle interacts with a charging pile, the control module 140 identifies the charging type of the charging pile. When the charging type is normal charging (charging terminal voltage is 230V-450V), the control module 140 controls the fourth switch RL5 and the sixth switch RL1 to be closed first, the seventh switch RL2 to be opened, and then the third switch RL8 and the fifth switch RL7 to be closed, the second switch RL6 to be opened, and then the first switch RL3 to be closed, thereby entering parallel charging mode. In parallel charging mode, the first power battery 110 and the second power battery 120 are connected in parallel to the charging terminal to achieve 450V normal fast charging. In the figure, the solid line represents the charging circuit, and the dotted line represents the portion of the power supply circuit that is used independently and not shared with the charging circuit.

[0098] FIG6 is a circuit connection diagram in the parallel discharge mode. As shown in FIG6 , illustratively, upon receiving a command for high voltage on the vehicle load and the voltage difference between the first power battery 110 and the second power battery 120 is less than a preset value, the control module 140 controls the first switch RL3 to be opened, the second switch RL6 to be opened, the third switch RL8 to be closed, the fourth switch RL5 to be closed, the fifth switch RL7 to be closed, the sixth switch RL1 to be closed, and the seventh switch RL2 to be opened, thereby entering the parallel discharge mode. In the parallel discharge mode, the first power battery 110 and the second power battery 120 are connected in parallel to the vehicle load end, and the first power battery 110 and the second power battery 120 supply power to the vehicle load, thereby ensuring battery consistency of the first power battery 110 and the second power battery 120.

[0099] The entire vehicle load usually has a load capacitor. When the entire vehicle load is powered, if the entire vehicle load is directly connected and the load capacitor is turned on, the voltage difference between the power battery and the capacitor can reach hundreds of volts, which is equivalent to a direct short circuit and can easily cause serious damage to the entire charging system. Therefore, in the embodiment of the present application, the switching module 130 also includes a sixth switch RL1, a seventh switch RL2, and a pre-charge resistor R1. FIG7 is a circuit connection diagram of the pre-charge circuit. As shown in FIG7, taking the case of powering the entire vehicle load in partial discharge mode as an example, after disconnecting the first switch RL3, disconnecting the second switch RL6, closing the third switch RL8, disconnecting the fourth switch RL5, and closing the fifth switch RL7, the sixth switch RL1 is first disconnected and the seventh switch RL2 is closed to form a pre-charge circuit to pre-charge the load capacitor of the entire vehicle load. When the voltage of the load capacitor reaches a preset voltage value, the sixth switch RL1 is closed and the seventh switch RL2 is disconnected, and the entire vehicle load is officially powered.

[0100] FIG8 is a schematic diagram of the structure of a control module provided in an embodiment of the present application. As shown in FIG8 , in some embodiments of the present application, the control module 140 includes:

[0101] The charging type identification unit 141 is configured to identify the charging type of the charging pile, for example, fast charging or normal charging, when the electric vehicle interacts with the charging pile.

[0102] The voltage value acquisition unit 142 is configured to acquire voltage values ​​of the plurality of power batteries in response to a high voltage request instruction from the vehicle controller.

[0103] The voltage difference calculation unit 143 is connected to the voltage value acquisition unit 142 and is configured to calculate the difference between the voltage value of the other power batteries and the voltage value of the target power battery.

[0104] The judging unit 144 is connected to the voltage difference calculating unit 143 and is configured to judge whether there is a difference greater than a preset value.

[0105] The mode switching control unit 145 is connected to the charging category identification unit 141 and the judgment unit 144 respectively, and is configured to control the switching module 130 to operate when the charging category is fast charging, switch the power battery system to the series charging mode, and when the charging category is normal charging, control the switching module 130 to operate and switch the power battery system to the parallel charging mode. When there is a difference greater than a preset value, control the switching module 130 to operate and switch the power battery system to the partial discharge mode, and when there is no difference greater than the preset value, control the switching module 130 to operate and switch the power battery system to the parallel discharge mode. The specific process of the mode switching control unit 145 controlling the switching module 130 to operate has been described in detail in the aforementioned embodiment and will not be repeated in this embodiment of the present application.

[0106] The present application also provides an electric vehicle, including the power battery system provided by any of the aforementioned embodiments. An electric vehicle is a vehicle that is powered by an onboard power source, uses an electric motor to drive its wheels, and complies with all requirements of road traffic and safety regulations. In the present application, the electric vehicle may be a pure electric vehicle or a hybrid electric vehicle, and the present application does not limit this.

[0107] As shown in FIG9A , an embodiment of the present application further provides a control method for a power battery system, including:

[0108] S1. When an electric vehicle interacts with a charging pile, a control module in a power battery system identifies the charging type of the charging pile;

[0109] S2. In response to the charging type being fast charging, the control module controls the switching module in the power battery system to switch the power battery system to a series charging mode; in the series charging mode, at least two power batteries in the power battery system are connected in series to a charging terminal, and a target power battery supplies power to a vehicle load, the target power battery being at least one of the at least two power batteries;

[0110] S3. In response to a high-voltage request instruction from a vehicle controller, the control module controls the switching module to switch the power battery system to a partial discharge mode or a parallel discharge mode; in the partial discharge mode, the at least two power batteries are connected in parallel to the vehicle load end, and power batteries other than the target power battery supply power to the vehicle load; in the parallel discharge mode, the at least two power batteries are connected in parallel to the vehicle load end, and the at least two power batteries supply power to the vehicle load.

[0111] The present application also provides a method for controlling a power battery system. Based on the power battery system provided in the above embodiment, FIG9B is a flow chart of another method for controlling a power battery system provided in the present application. As shown in FIG9B , the method for controlling a power battery system includes:

[0112] S101: When the electric vehicle interacts with the charging pile, the control module identifies the charging type of the charging pile.

[0113] Exemplarily, in an embodiment of the present application, the charging categories may include fast charging (eg, a charging terminal voltage of 550V-930V) and normal charging (eg, a charging terminal voltage of 230V-450V).

[0114] S102: When the charging type is fast charging, the control module controls the switching module to switch the power battery system to the series charging mode.

[0115] In the series charging mode, at least two power batteries are connected in series to the charging terminal, and a target power battery supplies power to the vehicle load, and the target power battery is at least one of the at least two power batteries.

[0116] For example, referring to Figures 2 and 3, when the control module 140 identifies the charging pile as fast charging, it controls the closing of the fourth switch RL5 and the sixth switch RL1, the opening of the seventh switch RL2, the opening of the third switch RL8, the opening of the fifth switch RL7, the closing of the second switch RL6, and the closing of the first switch RL3, thereby entering series charging mode. In series charging mode, the first power battery 110 and the second power battery 120 are connected in series for fast charging, and the second power battery 120 supplies power to the vehicle load.

[0117] S103: When the charging type is normal charging, the control module controls the switching module to switch the power battery system to the parallel charging mode.

[0118] In parallel charging mode, at least two power batteries are connected in parallel to the charging terminal.

[0119] For example, referring to Figures 2 and 5, when the charging category is normal charging (the charging terminal voltage is 230V-450V), the control module 140 controls the closing of the fourth switch RL5 and the sixth switch RL1 first, disconnects the seventh switch RL2, and then closes the third switch RL8 and the fifth switch RL7, disconnects the second switch RL6, and then closes the first switch RL3 to enter the parallel charging mode. In the parallel charging mode, the first power battery 110 and the second power battery 120 are connected in parallel to the charging terminal to achieve 450V normal fast charging. In addition, the charging terminal can also directly supply power to the entire vehicle load by closing the first switch RL3, the third switch RL8, and the sixth switch RL1.

[0120] S104 . In response to the high voltage request instruction from the vehicle controller, the control module controls the switching module to switch the power battery system to the partial discharge mode or the parallel discharge mode.

[0121] The high-voltage request instruction indicates that power needs to be supplied to the vehicle load. The control module 140 responds to the high-voltage request instruction of the vehicle controller, controls the switching module to switch the power battery system to partial discharge mode or parallel discharge mode. In partial discharge mode, at least two power batteries are connected in parallel to the vehicle load end, and power batteries other than the target power battery supply power to the vehicle load; in parallel discharge mode, at least two power batteries are connected in parallel to the vehicle load end, and at least two power batteries supply power to the vehicle load. Step 104 can be before step S101 or after step S101. The embodiment of the present application is not limited here. For example, as shown in Figure 9, this step is described as an example after step S101.

[0122] Exemplarily, the above step S104 includes the following sub-steps:

[0123] S1041. In response to a high-voltage request instruction from a vehicle controller, obtain voltage values ​​of multiple power batteries.

[0124] The control module 140 obtains the voltage values ​​of the multiple power batteries in response to the high voltage request instruction of the vehicle controller.

[0125] S1042: Calculate the difference between the voltage value of the other power batteries and the voltage value of the target power battery.

[0126] As described above, after fast charging is completed, the voltage of the first power battery 110 is higher than the voltage of the second power battery 120 (ie, the target power battery). In this embodiment of the present application, the difference between the voltage values ​​of the first power battery 110 and the second power battery 120 is calculated.

[0127] S1043. Determine whether there is a difference greater than a preset value.

[0128] It is determined whether the difference between the voltage values ​​of the first power battery 110 and the second power battery 120 is greater than a preset value.

[0129] S1044: If the difference is greater than the preset value, the control module controls the switching module to switch the power battery system to the partial discharge mode.

[0130] If the difference between the voltage values ​​of the first power battery 110 and the second power battery 120 is greater than a preset value, the control module 140 controls the switching module 130 to switch the power battery system to a partial discharge mode. In the partial discharge mode, at least two power batteries are connected in parallel to the vehicle load end, and power batteries other than the target power battery supply power to the vehicle load until the voltage value of the power batteries other than the target power battery drops to the voltage value of the target power battery.

[0131] For example, referring to Figures 2 and 4 , after the series charging mode fast charging ends, the voltage difference between the first power battery 110 and the second power battery 120 is greater than a preset value. If a high voltage command is received at this time, the control module 140 controls the opening of the first switch RL3, the opening of the second switch RL6, the closing of the third switch RL8, the opening of the fourth switch RL5, the closing of the fifth switch RL7, the closing of the sixth switch RL1, and the opening of the seventh switch RL2, thereby entering a partial discharge mode. In the partial discharge mode, the first power battery 110 and the second power battery 120 are connected in parallel to the vehicle load. Because the cathode voltage of the one-way diode D1 is higher than the anode voltage, the one-way diode D1 is non-conductive, and only the first power battery 110 supplies power to the vehicle load until the voltage of the first power battery 110 drops to within a preset range of the voltage of the second power battery 120 (for example, the voltage difference between the first power battery 110 and the second power battery 120 is less than 3V), thereby aligning the voltages of the first power battery 110 and the second power battery 120. In the embodiment of the present invention, after the voltage of the first power battery 110 drops to a preset range of the voltage of the second power battery 120 , the unidirectional diode D1 is turned on, the discharge circuit where the second power battery 120 is located is turned on, and the first power battery 110 and the second power battery 120 are discharged in parallel.

[0132] S1045: If there is no difference greater than the preset value, the control module controls the switching module to switch the power battery system to the parallel discharge mode.

[0133] If the voltage difference between the first power battery 110 and the second power battery 120 is less than or equal to a preset value, the control module 140 controls the switching module 130 to switch the power battery system to a parallel discharge mode. In the parallel discharge mode, at least two power batteries are connected in parallel to the vehicle load, and at least two power batteries supply power to the vehicle load.

[0134] Exemplarily, referring to Figures 2 and 6, when a command for high voltage on the vehicle load is received and the voltage difference between the first power battery 110 and the second power battery 120 is less than or equal to a preset value, the control module 140 controls the opening of the first switch RL3, the opening of the second switch RL6, the closing of the third switch RL8, the closing of the fourth switch RL5, the closing of the fifth switch RL7, the closing of the sixth switch RL1, and the opening of the seventh switch RL2, thereby entering the parallel discharge mode. In the parallel discharge mode, the first power battery 110 and the second power battery 120 are connected in parallel to the vehicle load end, and the first power battery 110 and the second power battery 120 supply power to the vehicle load, thereby ensuring battery consistency of the first power battery 110 and the second power battery 120.

[0135] The above embodiment is described by taking the discharge process after the charging process as an example. In other embodiments of the present application, the discharge process may also be before the charging process, and the discharge process and the charging process may also be independent, and there is no order relationship between them. The embodiments of the present application are not limited here.

[0136] In some embodiments of the present application, when powering the entire vehicle load, the load capacitor in the entire vehicle load is pre-charged. The control method of the power battery system also includes:

[0137] During the process of supplying power to the entire vehicle load, the seventh switch RL2 is closed and the sixth switch RL1 is opened to pre-charge the load capacitor. After the voltage value of the load capacitor in the entire vehicle load reaches the preset voltage value, the seventh switch RL2 is opened and the sixth switch RL1 is closed to officially supply power to the entire vehicle load.

[0138] In the description of this document, the terms "up", "down", "left", "right", etc., and the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be understood as a limitation on this application.

[0139] Throughout this specification, references to terms such as "an embodiment" or "example" indicate that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example.

[0140] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A power battery system, comprising: At least two power batteries, a switching module and a control module; The at least two power batteries are connected to the switching module, and the switching module is connected to the control module; The switching module is configured to operate under the control of the control module so that the power battery system enters a series charging mode, a partial discharge mode or a parallel discharge mode: In the series charging mode, the at least two power batteries are arranged to be connected in series to a charging terminal, and a target power battery supplies power to a vehicle load, and the target power battery is at least one of the at least two power batteries; In the partial discharge mode, the at least two power batteries are connected in parallel to the vehicle load end, and the power batteries other than the target power battery supply power to the vehicle load; In the parallel discharge mode, the at least two power batteries are arranged to be connected in parallel to the vehicle load end, and the at least two power batteries supply power to the vehicle load.

2. The power battery system according to claim 1, wherein: The switching module is further configured to operate under the control of the control module so that the power battery system enters: A parallel charging mode, in which the at least two power batteries are connected in parallel to the charging terminal.

3. The power battery system according to claim 2, wherein: The at least two power batteries are two power batteries, namely a first power battery and a second power battery; The switching module includes a first switching switch, a second switching switch, a third switching switch, a fourth switching switch, a fifth switching switch and a unidirectional diode; The first end of the first switch is configured to be connected to the positive electrode of the charging end, and the second end of the first switch is connected to the positive electrode of the first power battery; The negative electrode of the first power battery is connected to the first end of the second switch, and the second end of the second switch is connected to the positive electrode of the second power battery; The negative electrode of the second power battery is arranged to be connected to at least one of the negative electrode of the load end of the vehicle and the negative electrode of the charging end; The first end of the third switch is connected to the second end of the first switch, the second end of the third switch is connected to the first end of the fourth switch, the second end of the fourth switch is connected to the positive electrode of the second power battery, and the first end of the fourth switch is configured to be connected to the positive electrode of the vehicle load end; The first end of the fifth switch is connected to the negative electrode of the first power battery, and the second end of the fifth switch is configured to be connected to the negative electrode of the vehicle load end; The anode of the one-way diode is connected to the positive electrode of the second power battery, and the cathode of the one-way diode is connected to the second end of the third switch.

4. The power battery system according to claim 3, wherein: The switching module also includes a sixth switching switch, a seventh switching switch and a pre-charging resistor; The first end of the sixth switch is connected to the second end of the third switch, and the second end of the sixth switch is configured to be connected to the positive electrode of the vehicle load end; The pre-charging resistor and the seventh switch are connected in series between the second end of the third switch and the positive electrode of the vehicle load end.

5. The power battery system according to claim 3 or 4, wherein: The switching module further includes an eighth switching switch, a first end of the eighth switching switch is connected to a second end of the fifth switching switch, and a second end of the eighth switching switch is configured to be connected to a negative electrode of the vehicle load end.

6. The power battery system according to any one of claims 1 to 3, further comprising a fuse, wherein the fuse is connected in series to a wire connected to the positive electrode of the power battery.

7. The power battery system according to any one of claims 1 to 3, wherein: The control module comprises: A charging category identification unit, configured to identify the charging category of the charging pile when the electric vehicle interacts with the charging pile; A voltage value acquisition unit, configured to acquire voltage values ​​of the at least two power batteries in response to an upper high voltage request instruction of the vehicle controller; a voltage difference calculation unit, configured to calculate a difference between a voltage value of another power battery among the at least two power batteries and a voltage value of a target power battery; a judgment unit, configured to judge whether a difference between the voltage value of the other power battery and the voltage value of the target power battery is greater than a preset value; The mode switching control unit is configured to control the switching module to switch the power battery system to a series charging mode in response to the charging category being fast charging, control the switching module to switch the power battery system to a parallel charging mode in response to the charging category being normal charging, control the switching module to switch the power battery system to a partial discharge mode in response to a difference greater than a preset value, and control the switching module to switch the power battery system to a parallel discharge mode in response to no difference greater than the preset value.

8. An electric vehicle comprising the power battery system according to any one of claims 1 to 7.

9. A control method for a power battery system, comprising: When the electric vehicle interacts with the charging pile, the control module in the power battery system identifies the charging category of the charging pile; In response to the charging category being fast charging, the control module controls the switching module in the power battery system to switch the power battery system to a series charging mode; in the series charging mode, at least two power batteries in the power battery system are connected in series to a charging terminal, and a target power battery supplies power to a vehicle load, and the target power battery is at least one of the at least two power batteries; In response to the upper high voltage request instruction of the vehicle controller, the control module controls the action of the switching module to switch the power battery system to a partial discharge mode or a parallel discharge mode; in the partial discharge mode, the at least two power batteries are connected in parallel to the vehicle load end, and the power batteries other than the target power battery supply power to the vehicle load; in the parallel discharge mode, the at least two power batteries are connected in parallel to the vehicle load end, and the at least two power batteries supply power to the vehicle load.

10. The control method of the power battery system according to claim 9, wherein: In response to the high voltage request instruction of the vehicle controller, the control module controls the switching module to switch the power battery system to the partial discharge mode or the parallel discharge mode, including: In response to the high voltage request instruction of the vehicle controller, obtaining the voltage values ​​of the at least two power batteries; Calculating a difference between a voltage value of another power battery among the at least two power batteries and a voltage value of a target power battery; Determining whether a difference between the voltage value of the other power battery and the voltage value of the target power battery is greater than a preset value; In response to the existence of a difference greater than a preset value, the switching module is controlled to operate to switch the power battery system to a partial discharge mode; in the partial discharge mode, the at least two power batteries are connected in parallel to the vehicle load end, and the power batteries other than the target power battery supply power to the vehicle load until the voltage value of the power batteries other than the target power battery drops to within a preset range of the voltage value of the target power battery; In response to the absence of a difference greater than a preset value, the switching module is controlled to operate and the power battery system is switched to a parallel discharge mode. In the parallel discharge mode, the at least two power batteries are connected in parallel to the vehicle load end, and the at least two power batteries supply power to the vehicle load.

11. The control method of the power battery system according to claim 9, further comprising: In response to the charging category being normal charging, the control module controls the switching module to switch the power battery system to a parallel charging mode; in the parallel charging mode, the at least two power batteries are connected in parallel to the charging end.

12. The control method of the power battery system according to any one of claims 9 to 11, wherein: Switching the power battery system to a series charging mode includes: Closing the fourth switch in the switching module, opening the third switch in the switching module, opening the fifth switch in the switching module, closing the second switch in the switching module, and closing the first switch in the switching module; Switching the power battery system to a partial discharge mode includes: Disconnecting the first switch in the switching module, disconnecting the second switch in the switching module, closing the third switch in the switching module, disconnecting the fourth switch in the switching module, and closing the fifth switch in the switching module; Switching the power battery system to a parallel charging mode includes: Close the fourth switch in the switching module, close the third switch in the switching module, close the fifth switch in the switching module, open the second switch in the switching module, and close the first switch in the switching module; Switching the power battery system to a parallel discharge mode includes: Disconnecting the first switch in the switching module, disconnecting the second switch in the switching module, closing the third switch in the switching module, closing the fourth switch in the switching module, and closing the fifth switch in the switching module; Wherein, the switching module further includes a unidirectional diode; A first end of the first switch is connected to the positive electrode of the charging end, and a second end of the first switch is connected to the positive electrode of the first power battery among the at least two power batteries; A first end of the second switch is connected to the negative electrode of the first power battery, and a second end of the second switch is connected to the positive electrode of a second power battery among the at least two power batteries; The negative electrode of the second power battery is connected to at least one of the negative electrode of the load end of the vehicle and the negative electrode of the charging end; The first end of the third switch is connected to the second end of the first switch, the second end of the third switch is connected to the first end of the fourth switch, the second end of the fourth switch is connected to the positive electrode of the second power battery, and the first end of the fourth switch is connected to the positive electrode of the vehicle load end; A first end of the fifth switch is connected to the negative electrode of the first power battery, and a second end of the fifth switch is connected to the negative electrode of the vehicle load end; The anode of the one-way diode is connected to the positive electrode of the second power battery, and the cathode of the one-way diode is connected to the second end of the third switch.

13. The control method of the power battery system according to claim 12, further comprising: In the process of supplying power to the vehicle load, the seventh switch in the switching module is closed, and the sixth switch in the switching module is opened. After the voltage value of the load capacitor in the vehicle load reaches a preset voltage value, the seventh switch is opened and the sixth switch is closed; Wherein, the switching module also includes a pre-charging resistor; The first end of the sixth switch is connected to the second end of the third switch, and the second end of the sixth switch is connected to the positive electrode of the vehicle load end; The pre-charging resistor and the seventh switch are connected in series between the second end of the third switch and the positive electrode of the vehicle load end.

Images