Heating system for heating a power battery and electric vehicle

Abstract

The present disclosure provides a heating system for heating a power battery, and an electric vehicle. The power battery includes a first battery cell group and a second battery cell group, which have unequal electromotive forces and are connected in series. The heating system includes an inverter, an AC motor, and a first controller. The intermediate points of three bridge arms of the inverter are connected to the front ends of the three-phase coils of the motor in one-to-one correspondence, and the rear ends of the motor are connected to each other to form a neutral point. The neutral point of the motor is connected to a first connection point by a connection line, and the first connection point is a connection point between the first battery cell group and the second battery cell group. The first controller is used to input a drive signal to the inverter. The first battery cell group, the second battery cell group, the inverter, the motor, and the connection line form an AC self-heating loop.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This disclosure claims priority to and the benefit of Chinese Patent Application No. 202210456060.9, entitled “HEATING SYSTEM FOR HEATING POWER BATTERY, AND ELECTRIC VEHICLE,” filed on April 28, 2022. The entire contents of the above application are incorporated herein by reference.

[0002] The present disclosure relates to the field of vehicle technology, and more specifically, to a heating system for heating a power battery and an electric vehicle. [Background technology]

[0003] The characteristics of a power battery are greatly affected by the ambient temperature. Especially in low temperature environments, the energy and power characteristics of lithium-ion power batteries are significantly attenuated. Therefore, it is necessary to heat the battery at low temperatures. How to improve the heating performance of the battery core in the heating method that makes the battery core self-heat by using excitation current has become an important issue. Summary of the Invention [Means for solving the problem]

[0004] The objective of the present disclosure is to provide a new technical solution of a heating system for heating a power battery.

[0005] Another object of the present disclosure is to provide a new technical solution for an electric vehicle. The electric vehicle includes a power battery and a heating system.

[0006] The present disclosure provides a heating system for heating a power battery so that heating performance can be improved.

[0007] According to a first aspect of the present disclosure, a heating system for heating a power battery is provided. The power battery includes a first battery core group and a second battery core group connected in series, and the electromotive force of the first battery core group is not equal to the electromotive force of the second battery core group. The heating system includes an inverter, an AC motor, and a first controller. The inverter includes three bridge arms, and a positive pole of the power battery is connected to an upper bridge arm of the inverter, and a negative pole of the power battery is connected to a lower bridge arm of the inverter. The intermediate points of the three bridge arms of the inverter are respectively connected to the front ends of the three-phase coils of the AC motor, and the rear ends of the AC motor are connected to each other to form a neutral point. The neutral point of the AC motor is connected to a first connection point by a connection line, and the first connection point is a connection point between the first battery core group and the second battery core group. The first controller is configured to input a drive signal to the inverter. The first battery core group, the second battery core group, the inverter, the AC motor, and the connection line form an AC self-heating loop. The first controller (6) is further configured to adjust the driving signal in the self-heating process to enable a ratio of the first target difference to the first difference to fall within a preset interval range. The first target difference is a difference between the first difference and the second difference, the first difference being a difference between the electromotive force of the first battery core group and the electromotive force of the second battery core group when the self-heating starts, and the second difference being a difference between the electromotive force of the first battery core group and the electromotive force of the second battery core group when the self-heating ends.

[0008] According to one embodiment of the present disclosure, the preset interval range is (-0.9, +0.9).

[0009] According to one embodiment of the present disclosure, adjusting the drive signal in the self-heating process by the first controller to enable the ratio of the first target difference to the first difference to fall within a preset interval range includes adjusting, by the first controller, a duty cycle of the drive signal and / or a time series status of the drive signal in the self-heating process to enable the ratio of the first target difference to the first difference to fall within a preset interval range.

[0010] According to one embodiment of the present disclosure, adjusting the drive signal in the self-heating process by the first controller to enable a ratio of the first target difference to the first difference to fall within a preset interval range includes adjusting the drive signal by the first controller to enable a ratio of the second target difference to the fifth intensity integrated value to fall within a preset interval range.

[0011] According to an embodiment of the present disclosure, the second target difference is a difference between the fifth intensity integral value and the sixth intensity integral value, where the fifth intensity integral value is an intensity integral value of a current flowing through the first battery core group in a self-heating process, and the sixth intensity integral value is an intensity integral value of a current flowing through the second battery core group in a self-heating process. The intensity integral value of the current is an integral value of a current intensity of the current over time.

[0012] According to an embodiment of the present disclosure, the first controller adjusts the drive signal in the self-heating process to enable the ratio of the first target difference to the first difference to fall within a preset interval range, the first controller calculates a first theoretical current and a second theoretical current in the self-heating process, corrects the first theoretical current and the second theoretical current based on the first preset ratio, and sets the drive signal based on the corrected first theoretical current and the corrected second theoretical current. The first theoretical current is a theoretical current flowing through the first battery core group, and the second theoretical current is a theoretical current flowing through the second battery core group.

[0013] According to one embodiment of the present disclosure, the first preset ratio is determined in advance by using a heating test experiment, and determining the first preset ratio includes obtaining a ratio of a first intensity integrated value of the first experimental current to a first intensity integrated value of the second experimental current as a second ratio, and determining the first preset ratio, the first preset ratio being the reciprocal of the second ratio. The first experimental current is an actual current flowing through the first battery core group in the heating test experiment, and the second experimental current is an actual current flowing through the second battery core group in the heating test experiment. The first intensity integrated value of the first experimental current is an intensity integrated value of the first experimental current from the start of the heating test experiment to the end of the heating test experiment, and the first intensity integrated value of the second experimental current is an intensity integrated value of the second experimental current from the start of the heating test experiment to the end of the heating test experiment.

[0014] According to an embodiment of the present disclosure, the first controller adjusts the driving signal in the self-heating process to enable the ratio of the first target difference to the first difference to fall within a preset interval range, the adjustment includes obtaining a second intensity integrated value of the first measured current and a second intensity integrated value of the second measured current, and setting the driving signal for a next adjustment period based on the second intensity integrated value of the first measured current and the second intensity integrated value of the second measured current. The first measured current is the measured current flowing through the first battery core group, and the second measured current is the measured current flowing through the second battery core group.

[0015] The second intensity integrated value of the first measured current is the intensity integrated value of the first measured current from the start of self-heating to the end of the current adjustment period, and the second intensity integrated value of the second measured current is the intensity integrated value of the second measured current from the start of self-heating to the end of the current adjustment period.

[0016] According to one embodiment of the present disclosure, adjusting the drive signal in the self-heating process by the first controller to enable a ratio of the first target difference to the first difference to fall within a preset interval range includes obtaining a second intensity integrated value of the first measured current and a second intensity integrated value of the second measured current, obtaining a third intensity integrated value of the first measured current and a third intensity integrated value of the second measured current, and setting the drive signal for a next adjustment period based on the second intensity integrated value of the first measured current, the second intensity integrated value of the second measured current, the third intensity integrated value of the first measured current, and the third intensity integrated value of the second measured current.

[0017] The first measured current is the measured current flowing through the first battery core group, and the second measured current is the measured current flowing through the second battery core group.

[0018] The second intensity integrated value of the first measured current is the intensity integrated value of the first measured current from the start of self-heating to the end of the current adjustment period, and the second intensity integrated value of the second measured current is the intensity integrated value of the second measured current from the start of self-heating to the end of the current adjustment period.

[0019] The third intensity integrated value of the first measured current is the intensity integrated value of the first measured current within the current adjustment period, and the third intensity integrated value of the second measured current is the intensity integrated value of the second measured current within the current adjustment period.

[0020] According to an embodiment of the present disclosure, setting the drive signal for the next adjustment period includes setting a duty cycle and / or a time series status of the drive signal for the next adjustment period such that a second absolute value is smaller than the first absolute value, the first absolute value being an absolute value of a difference between a second intensity integrated value of the first measured current and a second intensity integrated value of the second measured current.

[0021] The second absolute value is the absolute value of the difference between the fourth intensity integrated value of the first measured current and the fourth intensity integrated value of the second measured current.

[0022] The fourth intensity integrated value of the first measured current is the intensity integrated value of the first measured current from the start of self-heating to the end of the next adjustment period, and the fourth intensity integrated value of the second measured current is the intensity integrated value of the second measured current from the start of self-heating to the end of the next adjustment period.

[0023] According to one embodiment of the present disclosure, adjusting the drive signal in the self-heating process by the first controller to enable a ratio of the first target difference to the first difference to be within a preset interval range includes obtaining a first effective value of the first measured current and a first effective value of the second measured current, and setting the drive signal for a next adjustment period based on the first effective value of the first measured current and the first effective value of the second measured current.

[0024] The first measured current is the measured current flowing through the first battery core group, and the second measured current is the measured current flowing through the second battery core group.

[0025] The first effective value of the first measured current is the effective value of the first measured current from the start of self-heating to the end of the current adjustment period, and the first effective value of the second measured current is the effective value of the second measured current from the start of self-heating to the end of the current adjustment period.

[0026] According to one embodiment of the present disclosure, adjusting the drive signal in the self-heating process by the first controller to enable a ratio of the first target difference to the first difference to fall within a preset interval range includes obtaining a first effective value of the first measured current and a first effective value of the second measured current, obtaining a second effective value of the first measured current and a second effective value of the second measured current, and setting the drive signal for a next adjustment period based on the first effective value of the first measured current, the first effective value of the second measured current, the second effective value of the first measured current, and the second effective value of the second measured current.

[0027] The first measured current is the measured current flowing through the first battery core group, and the second measured current is the measured current flowing through the second battery core group.

[0028] The first effective value of the first measured current is the effective value of the first measured current from the start of self-heating to the end of the current adjustment period, and the first effective value of the second measured current is the effective value of the second measured current from the start of self-heating to the end of the current adjustment period.

[0029] The second effective value of the first measured current is the effective value of the first measured current within a current adjustment period, and the second effective value of the second measured current is the effective value of the second measured current within a current adjustment period.

[0030] According to one embodiment of the present disclosure, setting the drive signal for the next adjustment period includes setting a duty cycle and / or a time series status of the drive signal for the next adjustment period such that the fourth absolute value is less than the third absolute value.

[0031] The third absolute value is the absolute value of the difference between the first effective value of the first measured current and the first effective value of the second measured current.

[0032] The fourth absolute value is the absolute value of the difference between the third effective value of the first measured current and the third effective value of the second measured current.

[0033] The third effective value of the first measured current is the effective value of the first measured current from the start of self-heating to the end of the next adjustment period, and the third effective value of the second measured current is the effective value of the second measured current from the start of self-heating to the end of the next adjustment period.

[0034] According to one embodiment of the present disclosure, the tuning strategy of the first controller is a PID tuning strategy.

[0035] According to an embodiment of the present disclosure, the first controller is further configured to perform synchronous control over the on / off states of the three upper bridge arms and perform synchronous control over the on / off states of the three lower bridge arms in a self-heating process.

[0036] According to one embodiment of the present disclosure, the first controller is further configured to adjust the drive signal during the self-heating process so that the average value of the effective value of the current flowing through the first battery core group is between 0.5C and 5C within the entire self-heating period, and the average value of the effective value of the current flowing through the second battery core group is between 0.5C and 5C within the entire self-heating period.

[0037] According to one embodiment of the present disclosure, the first controller is further configured to adjust the driving signal in the self-heating process such that an average value of the effective value of the current flowing through the neutral point of the AC motor is between 1 C and 10 C within the entire self-heating period.

[0038] According to one embodiment of the present disclosure, the central segment is a curved structure including one or more arc structures, or the central segment is a curved structure formed by one or more arc structures and one or more linear structures.

[0039] According to a second aspect of the present disclosure, there is provided an electric vehicle including a power battery and a heating system according to any one of the preceding embodiments.

[0040] According to an embodiment of the present disclosure, a loop is added to the original circuit topology of the electric vehicle, and the loop is from the neutral point of the AC motor to the connection point between the first battery core group and the second battery core group. The heating system can improve the heating performance as a whole. Based on the heating system for heating the power battery and the electric vehicle in the present disclosure, the first controller adjusts the driving signal in the self-heating process to enable the ratio of the first target difference to the first difference to fall within a preset interval range, so that it can be ensured that the difference between the charge loss of the first battery core group and the charge loss of the second battery core group is not excessively large at the end of self-heating, thereby ensuring the balance between the first battery core group and the second battery core group, and reducing the adverse effect caused by self-heating on the amount of available charge and the endurance driving distance of the electric vehicle.

[0041] Other features and advantages of the present disclosure will become apparent based on the following detailed description of exemplary embodiments thereof, which proceeds with reference to the accompanying drawings.

[0042] The accompanying drawings are incorporated in and constitute a part of this disclosure, illustrate embodiments consistent with the present disclosure, and are used in conjunction with the present disclosure to explain the principles of the present disclosure. [Brief description of the drawings]

[0043] [Figure 1] FIG. 1 is a block diagram of a heating system for heating a power battery according to one embodiment of the present disclosure. [Diagram 2] FIG. 2 is an exemplary circuit diagram of a heating system for heating a power battery according to one embodiment of the present disclosure. [Explanation of symbols]

[0044] 1 First battery core group 2 Second battery core group P Connection Point 3 Inverter 4 AC motor N neutral point 5. Switch 6 First Controller 7 Protection circuit 8 Second Controller S1 connection line DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings.

[0046] The following description of at least one example embodiment is merely exemplary in nature and is in no way intended to serve as a limitation on the present disclosure and its application or uses.

[0047] It should be noted that in the following attached drawings, like numbers and letters refer to like items, and thus, once an item is defined in a drawing, no further description of that item is required in subsequent attached drawings.

[0048] In an electric vehicle, an inverter is connected between a power battery and an AC motor. One of the main functions of the inverter is to convert the DC current output by the power battery into AC current to drive the AC motor to rotate, thereby driving the wheel end to rotate. In the power battery heating solution in the embodiment of the present disclosure, a circuit topology between the power battery, the inverter, and the AC motor is used to heat the power battery for temperature increase.

[0049] In an embodiment of the present disclosure, the power battery includes a first battery core group and a second battery core group connected in series, and the heating system for heating the power battery includes an inverter, an AC motor, and a first controller. The inverter includes three bridge arms, and a positive pole of the power battery is connected to an upper bridge arm of the inverter, and a negative pole of the power battery is connected to a lower bridge arm of the inverter. The intermediate points of the three bridge arms of the inverter are respectively connected to the front ends of the three-phase coils of the AC motor, and the rear ends of the AC motor are connected to each other to form a neutral point. The neutral point of the AC motor is connected to a first connection point by a connection line, and the first connection point is a connection point between the first battery core group and the second battery core group. The first controller is configured to input a driving signal to the inverter. The first battery core group, the second battery core group, the inverter, the AC motor, and the connection line form an AC self-heating loop. The first controller is configured to input a driving signal to the inverter. Under the operation of the drive signal, the inverter is controlled to alternately turn on the first battery core group and the AC motor and the second battery core group and the AC motor so that the first battery core group and the second battery core group alternately charge each other.

[0050] Based on the heating system for heating the power battery and the electric vehicle in the embodiment of the present disclosure, a loop is added to the original circuit topology of the electric vehicle, and the loop is from the neutral point of the AC motor to the connection point between the first battery core group and the second battery core group. The heating system can improve the heating performance as a whole. The following description is provided with respect to the embodiment.

[0051] As shown in FIG. 1 and FIG. 2, a heating system for heating a power battery provided in an embodiment of the present disclosure is described.

[0052] As shown in Figures 1 and 2, the power battery includes a first battery core group 1 and a second battery core group 2 connected in series, and the heating system includes an inverter 3, an AC motor 4, and a first controller 6.

[0053] The AC motor 4 is star-connected, with the rear ends of the three phase coils (coil A, coil B, and coil C) connected to each other as a common end, which is the neutral point N of the AC motor 4.

[0054] The inverter 3 includes three bridge arms, and the positive pole of the power battery is connected to the upper bridge arm of the inverter 3, and the negative pole of the power battery is connected to the lower bridge arm of the inverter 3. The midpoints of the three bridge arms of the inverter 3 are respectively connected to the front ends of the three-phase coils of the AC motor 4. In one example, as shown in FIG. 1 and FIG. 2, the inverter 3 includes IGBT T1, IGBT T2, IGBT T3, IGBT T4, IGBT T5, and IGBT T6. The IGBTs T1 to T6 form three bridge arms. The IGBT (Insulated Gate Bipolar Transistor) is a composite voltage-driven power semiconductor device that includes a BJT (Bipolar Junction Transistor) and a MOS transistor (Metal-Oxide-Semiconductor Field Effect Transistor), and has the advantages of the high input impedance of a MOSFET and the low turn-on voltage drop of a GTR (Giant Transistor). As shown in FIG. 2, in the inverter 3, each IGBT is further connected in parallel to a diode, and the diode may play a role of circuit protection. In another embodiment, each of the IGBTs T1 to T6 may be alternatively replaced with a MOS transistor. In another embodiment, each of the IGBTs T1 to T6 may be alternatively replaced with a silicon carbide (SiC) power tube. The neutral point N of the AC motor is connected to a first connection point P by a connection line S1, and the first connection point P is a connection point between the first battery core group and the second battery core group.

[0055] In one example, the first battery core group and the second battery core group belong to the same battery pack, and the battery pack provides to the outside all positive pole ports, all negative pole ports, and a third port leading from the first connection point P. The third port is connected to the neutral point N of the AC motor by a connection line S1.

[0056] The first controller 6 is configured to input a drive signal to the inverter 3 to control the inverter 3 to alternately turn on the first battery core group 1 and the AC motor 4 and the second battery core group 2 and the AC motor 4 so that the first battery core group 1 and the second battery core group 2 alternately charge each other. In one example, as shown in FIG. 2, the first controller 6 outputs six drive signals Q1 to Q6. The drive signal Q1 is applied to the IGBT T1, the drive signal Q2 is applied to the IGBT T2, the drive signal Q3 is applied to the IGBT T3, the drive signal Q4 is applied to the IGBT T4, the drive signal Q5 is applied to the IGBT T5, and the drive signal Q6 is applied to the IGBT T6. The first controller 6 alternately turns on the loop of the first battery core group 1 and the AC motor 4 and the loop of the second battery core group 2 and the AC motor 4 by applying the driving signals Q1 to Q6 to the IGBTs T1 to T6 so that the first battery core group 1 and the second battery core group 2 alternately charge each other. In one example, the first battery core group 1 discharges, the inverter 3 converts the DC current output by the first battery core group 1 into an AC current, inputs the AC current to the AC motor 4, and the AC motor 4 stores the electric energy in the coil to charge the second battery core group 2. Then, the second battery core group 2 discharges, the inverter 3 converts the DC current output by the second battery core group 2 into an AC current, inputs the AC current to the AC motor 4, and the AC motor 4 stores the electric energy in the coil to charge the first battery core group 1. Periodically, the first battery core group 1 and the second battery core group 2 alternately charge each other by using an AC motor 4 to self-heat the battery cores.

[0057] As shown in Figures 1 and 2, a switch 5 is disposed on the connection line S1. The heating system further includes a second controller 8. The second controller 8 is configured to control the on / off state of the switch 5, so that the heating line is turned on when the power battery needs to be heated and turned off when the power battery does not need to be heated, in order to ensure the safety of the vehicle and the power battery. For example, the second controller 8 controls the switch 5 to be turned off when the electric vehicle is in a running state, in order to ensure the safety of the vehicle during running.

[0058] As shown in Figures 1 and 2, in order to improve safety in the battery heating process, a protection circuit 7, such as a fuse and a relay, is arranged on the connecting line S1.

[0059] 1 further illustrates a power distribution box of the electric vehicle. The power distribution box mainly distributes power based on the power load of the electric vehicle.

[0060] Based on the heating system for heating a power battery provided in the embodiment of the present disclosure, a connection line is added based on the original circuit topology of the electric vehicle. The connection line is from the neutral point of the AC motor to the connection point between the first battery core group and the second battery core group. The change to the original circuit of the electric vehicle is small, and the solution is simple and easy to implement.

[0061] Based on the heating system for heating a power battery provided in this embodiment of the present disclosure, the upper and lower bridge arms of the inverter are used in a time-sharing manner, which makes great use of the three inductance coils of the motor to generate an AC pulse current, thereby rapidly heating the two battery core groups.

[0062] In the self-heating process of a power battery, the frequency and magnitude of the charge and discharge current, i.e., the excitation current, are limited by the associated components. The heating system provided in this embodiment of the present disclosure can reduce the degree of the limitation of the excitation current, allowing the battery to be heated by using a relatively large excitation current. In the self-heating operating condition of a conventional battery pack, the maximum current of the inverter is limited by the minimum current among the withstand currents of the IGBTs T1 to T6. However, in this embodiment of the present disclosure, the maximum current of the inverter is limited by the sum of the withstand currents of the IGBTs T1, T2, and T3 and the sum of the withstand currents of the IGBTs T4, T5, and T6, thereby greatly increasing the range of available current.

[0063] The self-heating system in this embodiment of the present disclosure may further include a measurement system and a battery management system (BMS). In the self-heating process, the relevant data monitored by the measurement system and the battery management system are output and fed back to the first controller in real time, and the first controller dynamically adjusts the frequency or amplitude of the excitation current output by the self-heating system according to a preset policy.

[0064] In this embodiment of the present disclosure, the start of self-heating means that the connection line S1 changes from an off state to an on state, and the first battery core group and the second battery core group start to alternately charge each other. The end of self-heating means that the connection line S1 changes from an on state to an off state, and the first battery core group and the second battery core group no longer alternately charge each other.

[0065] In this embodiment of the present disclosure, the electromotive force of the first battery core group is not equal to the electromotive force of the second battery core group, which means that at the start of self-heating, the voltage difference between the two ends of the first battery core group is not equal to the voltage difference between the two ends of the second battery core group.

[0066] In one example, the electromotive force of the first battery core group is not equal to the electromotive force of the second battery core group due to a difference between the status of the battery core units in the first battery core group and the status of the battery core units in the second battery core group. Such a difference may be a difference between the quantity of the battery core units, a difference between the materials of the battery core units, or a difference between the models of the battery core units. In one example, the electromotive force of the first battery core group is not equal to the electromotive force of the second battery core group may be a rated electromotive force of the first battery core group is not equal to the rated electromotive force of the second battery core group.

[0067] In one example, the initial design of the first battery core group is the same as the initial design of the second battery core group, that is, the initial electromotive force of the first battery core group is equal to the initial electromotive force of the second battery core group. However, due to the daily use of the electric vehicle, the first battery core group and the second battery core group have different degrees of loss, so that the electromotive force of the first battery core group is not equal to the electromotive force of the second battery core group.

[0068] In one example, the first battery core group and the second battery core group belong to the same battery pack, the electromotive force of the first battery core group is not equal to the electromotive force of the second battery core group, the first connection point is a non-equipotential point, and the connection line is connected to the non-equipotential point of the battery pack. The non-equipotential point means that the absolute value of the voltage difference from that point to all the positive pole ports of the battery pack is not equal to the absolute value of the voltage difference from that point to all the negative pole ports of the battery pack. As shown in FIG. 2, the battery core units included in the first battery core group 1 and the battery core units included in the second battery core group 2 are of the same model but different in quantity. Therefore, the electromotive force of the first battery core group 1 is different from the electromotive force of the second battery core group 2, and the connection point P is a non-equipotential point.

[0069] In the conventional solution, the power electronic switch in the inverter has an error during switching, the coil of the AC motor has a loss during high current oscillation, and the Hall element used for measurement has an error during measurement. Therefore, the power consumption of the current flowing through the first battery core group 1 and the power consumption flowing through the second battery core group 2 cannot be maintained, and there is an error between the two. As a result, in a long-term self-heating operating condition, the charge loss of the first battery core group 1 does not match the charge loss of the second battery core group 2 (resulting in a charge loss error), which causes a difference between the SOC (State of Charge) of the battery core units in the first battery core group 1 and the SOC of the battery core units in the second battery core group 2.

[0070] The battery core units in the power battery are connected in series, and the amount of available charge of the integrated vehicle is limited to the lowest SOC of the battery core units. Therefore, the mismatch between the charge loss of the first battery core group 1 and the charge loss of the second battery core group 2 under the self-heating operating condition will have a negative impact on the amount of available charge and the endurance driving distance of the electric vehicle.

[0071] In this embodiment of the present disclosure, to solve this problem, the first controller 6 is further configured to adjust the driving signal in the self-heating process to enable the ratio of the first target difference to the first difference to fall within a preset interval range. The first target difference is the difference between the first difference and the second difference, the first difference is the difference between the electromotive force of the first battery core group 1 and the electromotive force of the second battery core group 2 when the self-heating starts, and the second difference is the difference between the electromotive force of the first battery core group 1 and the electromotive force of the second battery core group 2 when the self-heating ends. The ratio of the first target difference to the first difference falls within a preset interval range, which means that when self-heating is completed, the difference between the total charge loss of the first battery core group 1 in the entire heating process and the total charge loss of the second battery core group 2 in the entire heating process falls within the range, thereby ensuring the balance between the first battery core group 1 and the second battery core group 2, and controlling to a certain extent the adverse effects caused by self-heating on the amount of available charge and the durable mileage of the electric vehicle.

[0072] In one example, adjusting the drive signal in the self-heating process by the first controller 6 to enable the ratio of the first target difference to the first difference to fall within a preset interval range includes adjusting the drive signal by the first controller 6 to enable the ratio of the second target difference to the fifth intensity integrated value to fall within a preset interval range. The second target difference is the difference between the fifth intensity integrated value and the sixth intensity integrated value, the fifth intensity integrated value being the intensity integrated value of the current flowing through the first battery core group 1 in the self-heating process, and the sixth intensity integrated value being the intensity integrated value of the current flowing through the second battery core group 2 in the self-heating process. The intensity integrated value of the current is the integrated value of the current intensity of the current over time. In this example, both the current flowing through the first battery core group 1 and the current flowing through the second battery core group 2 refer to theoretical current or actual measured current.

[0073] In one example, the preset interval range is (-0.9, +0.9).

[0074] In one example, the preset interval range is (-0.5, +0.5).

[0075] In one example, the preset interval range is (-0.1, +0.1).

[0076] In one example, the preset interval range is (-0.05, +0.05).

[0077] In one example, the preset interval range is (-0.005, +0.005).

[0078] In one example, different first differences correspond to different preset interval ranges, i.e., the difference between the electromotive force of the first battery core group 1 and the electromotive force of the second battery core group 2 at the start of self-heating affects the preset interval range. In one example, the smaller the difference between the electromotive force of the first battery core group 1 and the electromotive force of the second battery core group 2 at the start of self-heating, the wider the preset interval range (e.g., the preset interval range is (-0.9, +0.9)). The larger the difference between the electromotive force of the first battery core group 1 and the electromotive force of the second battery core group 2 at the start of self-heating, the narrower the preset interval range (e.g., the preset interval range is (-0.05, +0.05)). In one example, a mapping relationship between the first difference and the preset interval range is pre-stored in the electric vehicle. When self-heating needs to be performed, the difference between the electromotive force of the first battery core group 1 and the electromotive force of the second battery core group 2 is detected, and the corresponding preset interval range is searched for based on the pre-stored mapping relationship.

[0079] In this embodiment of the disclosure, the current intensity integral is the integral of the current intensity of a current over time. Current intensity is the value of the current and is a positive value. Current intensity may represent the amount of charge passing through a conductor per unit time.

[0080] In this embodiment of the present disclosure, the theoretical current is a theoretical current determined by non-actual measurement and may be calculated based on the drive signal. The actual current refers to a current determined by actual measurement.

[0081] In one example, adjusting the drive signal in the self-heating process by the first controller to enable the ratio of the first target difference to the first difference to fall within a preset interval range includes adjusting, by the first controller, a duty cycle of the drive signal and / or a time series status of the drive signal in the self-heating process to enable the ratio of the first target difference to the first difference to fall within a preset interval range.

[0082] In this embodiment of the present disclosure, the time series status of the drive signals is the time series status of the drive signals Q1-Q3 of the three upper bridge arms, or the time series status of the drive signals Q4-Q6 of the three lower bridge arms. "1" shall indicate that the upper bridge arm is turned on. When the upper bridge arm is turned on, the lower bridge arm corresponding to the upper bridge arm is turned off. "0" shall indicate that the upper bridge arm is turned off. When the upper bridge arm is turned off, the lower bridge arm corresponding to the upper bridge arm is turned on. In this case, there are eight time series of the three-phase bridge arms of the inverter, that is, there are eight time series statuses of the drive signals, namely U0(000), U1(001), U2(010), U3(011), U4(100), U5(101), U6(110), and U7(111). U1(001), U2(010), U3(011), U4(100), U5(101), and U6(110) are non-zero vectors, and U0(000) and U7(111) are zero vectors.

[0083] In one example, the first controller adjusting the drive signal in the self-heating process includes adjusting the drive signal in the self-heating process in a dynamic and real-time manner by the first controller, i.e., the first controller adjusts the drive signal in real time so that the difference between the charge loss of the first battery core group 1 and the charge loss of the second battery core group 2 is compensated in time, thereby avoiding abrupt fluctuations in the excitation current.

[0084] The following describes a first method for adjusting the drive signal. EXAMPLES

[0085] Example 1: First, a first preset ratio is predetermined by using a heating test experiment. The heating test experiment can be a heating test performed on an electric vehicle before the integrated vehicle leaves the factory. The excitation current can be accurately measured by using a high-precision Hall element or the like.

[0086] In one example, the process of determining the first preset ratio includes steps S102 and S104.

[0087] Step S102: A ratio of the first intensity integrated value of the first experimental current to the first intensity integrated value of the second experimental current is obtained as a second ratio.

[0088] At the start of the heating test experiment, the drive signal is set to allow the ratio of the first intensity integral value of the first theoretical current to the first intensity integral value of the second theoretical current to be 1. In this case, a first experimental current and a second experimental current are obtained. The first theoretical current is a theoretical current flowing through the first battery core group 1, and the second theoretical current is a theoretical current flowing through the second battery core group 2. The first theoretical current and the second theoretical current are currents determined by non-actual measurement and can be calculated based on the drive signal. The first intensity integral value of the first theoretical current is an intensity integral value of the first theoretical current from the start of the heating test experiment to the end of the heating test experiment, and the first intensity integral value of the second theoretical current is an intensity integral value of the second theoretical current from the start of the heating test experiment to the end of the heating test experiment.

[0089] The first experimental current is an actual measured current flowing through the first battery core group 1 in the heating test experiment, and the second experimental current is an actual measured current flowing through the second battery core group 2 in the heating test experiment. During the heating test experiment, the first experimental current and the second experimental current are obtained by actual measurement. The first intensity integrated value of the first experimental current is an intensity integrated value of the first experimental current from the start of the heating test experiment to the end of the heating test experiment, and the first intensity integrated value of the second experimental current is an intensity integrated value of the second experimental current from the start of the heating test experiment to the end of the heating test experiment.

[0090] Step S104: A first preset ratio is determined, where the first preset ratio is the reciprocal of the second ratio.

[0091] The first experimental current and the second experimental current include effects caused by electronic control errors and motor coil losses. The first intensity integrated value of the first experimental current may reflect the actual charge loss of the first battery core group 1 in the heating test experiment when the first theoretical current is used, and the first intensity integrated value of the second experimental current may reflect the actual charge loss of the second battery core group 2 in the heating test experiment when the second theoretical current is used.

[0092] For example, if the ratio of the first intensity integral of the first experimental current to the first intensity integral of the second experimental current is 99 / 100, the first preset ratio is 100 / 99.

[0093] For different types of battery packs, the first preset ratio corresponding to each type of battery pack needs to be determined by using the heating test experiment of each battery pack. For the same type of multiple battery packs, when the first battery core group 1 and the second battery core group 2 are grouped differently in each battery pack, the first preset ratio corresponding to each battery pack also needs to be determined by using the heating test experiment of each battery pack.

[0094] The first controller adjusting the driving signal in the self-heating process to enable the ratio of the first target difference to the first difference to fall within a preset interval range may include steps S202 to S206.

[0095] Step S202: A first theoretical current and a second theoretical current in the self-heating process are calculated.

[0096] Step S204: The first theoretical current and the second theoretical current are corrected based on a first preset ratio.

[0097] In one example, after the first theoretical current and the second theoretical current are corrected based on the first preset ratio, the ratio of the second intensity integral value of the first theoretical current to the second intensity integral value of the second theoretical current is the first preset ratio. The second intensity integral value of the first theoretical current is the intensity integral value of the first theoretical current from the start of self-heating to the end of self-heating, and the second intensity integral value of the second theoretical current is the intensity integral value of the second theoretical current from the start of self-heating to the end of self-heating.

[0098] Step S206: The driving signal is set based on the corrected first theoretical current and the corrected second theoretical current.

[0099] After the drive signal is set based on the corrected first theoretical current and the corrected second theoretical current, the first theoretical current calculated based on the drive signal is the aforementioned corrected first theoretical current, and the second theoretical current calculated based on the drive signal is the aforementioned corrected second theoretical current.

[0100] In such an adjustment method, although the charge loss error caused by the electric control error and the motor coil loss still exists, the driving signal is set based on the corrected first theoretical current and the corrected second theoretical current, so that the charge loss error caused by the electric control error and the motor coil loss is compensated, thereby ensuring that the intensity integrated value of the first actual current from the start of self-heating to the end of self-heating is basically the same as the intensity integrated value of the second actual current from the start of self-heating to the end of self-heating. The first adjustment method ensures that the difference between the total charge loss of the first battery core group 1 and the total charge loss of the second battery core group 2 caused by self-heating falls within a range, thereby ensuring the balance between the first battery core group 1 and the second battery core group 2, and to a certain extent controlling the adverse effect caused by self-heating on the amount of available charge and the endurance driving distance of the electric vehicle.

[0101] Example 2: First, a first preset ratio is predetermined by using a heating test experiment. The heating test experiment can be a heating test performed on an electric vehicle before the integrated vehicle leaves the factory. The excitation current can be accurately measured by using a high-precision Hall element or the like.

[0102] In one example, the process of determining the first preset ratio includes steps P102 and P104.

[0103] Step P102: A ratio of the fourth effective value of the first measured current to the fourth effective value of the second measured current is obtained as a second ratio.

[0104] In this embodiment of the disclosure, the effective value of the current is the root mean square value known in the industry and is defined as follows: the heat generated by a current passing through a resistor in a given period of time is equal to the heat generated by a direct current passing through the resistor in the same period of time. The value of the direct current is the effective value of the current.

[0105] At the start of the heating test experiment, the drive signal is set to allow a ratio of the first effective value of the first theoretical current to the first effective value of the second theoretical current to be 1. In this case, a first measured current and a second measured current are obtained. The first theoretical current is a theoretical current flowing through the first battery core group 1, and the second theoretical current is a theoretical current flowing through the second battery core group 2. The first theoretical current and the second theoretical current are currents determined by non-actual measurement and can be calculated based on the drive signal. The first effective value of the first theoretical current is an effective value of the first theoretical current from the start of the heating test experiment to the end of the heating test experiment, and the first effective value of the second theoretical current is an effective value of the second theoretical current from the start of the heating test experiment to the end of the heating test experiment.

[0106] The first measured current is a measured current flowing through the first battery core group 1, and the second measured current is a measured current flowing through the second battery core group 2. During the heating test experiment, the first measured current and the second measured current are obtained by actual measurement. The fourth measured current is an effective value of the first measured current from the start of the heating test experiment to the end of the heating test experiment, and the fourth measured current is an effective value of the second measured current from the start of the heating test experiment to the end of the heating test experiment.

[0107] Step P104: A first preset ratio is determined, where the first preset ratio is the reciprocal of the second ratio.

[0108] The first measured current and the second measured current include effects caused by electronic control errors and motor coil losses. The fourth effective value of the first measured current may reflect the actual charge loss of the first battery core group 1 in the heating test experiment when the first theoretical current is used, and the fourth effective value of the second measured current may reflect the actual charge loss of the second battery core group 2 in the heating test experiment when the second theoretical current is used.

[0109] For example, if the ratio of the fourth effective value of the first measured current to the fourth effective value of the second measured current is 99 / 100, the first preset ratio is 100 / 99.

[0110] For different types of battery packs, the first preset ratio corresponding to each type of battery pack needs to be determined by using the heating test experiment of each battery pack. For the same type of multiple battery packs, when the first battery core group 1 and the second battery core group 2 are grouped differently in each battery pack, the first preset ratio corresponding to each battery pack also needs to be determined by using the heating test experiment of each battery pack.

[0111] The first controller adjusting the driving signal in the self-heating process to enable the ratio of the first target difference to the first difference to fall within a preset interval range may include steps P202 to P206.

[0112] Step P202: A first theoretical current and a second theoretical current in the self-heating process are calculated.

[0113] Step P204: The first theoretical current and the second theoretical current are corrected based on a first preset ratio.

[0114] In one example, after the first theoretical current and the second theoretical current are corrected based on the first preset ratio, a ratio of the second effective value of the first theoretical current to the second effective value of the second theoretical current is the first preset ratio. The second effective value of the first theoretical current is the effective value of the first theoretical current from the start of self-heating to the end of self-heating, and the second effective value of the second theoretical current is the effective value of the second theoretical current from the start of self-heating to the end of self-heating.

[0115] Step P206: The drive signal is set based on the corrected first theoretical current and the corrected second theoretical current.

[0116] After the drive signal is set based on the corrected first theoretical current and the corrected second theoretical current, the first theoretical current calculated based on the drive signal is the aforementioned corrected first theoretical current, and the second theoretical current calculated based on the drive signal is the aforementioned corrected second theoretical current.

[0117] In such an adjustment scheme, although the charge loss error caused by the electric control error and the motor coil loss still exists, the driving signal is set based on the corrected first theoretical current and the corrected second theoretical current, so that the charge loss error caused by the electric control error and the motor coil loss is compensated, thereby ensuring that the effective value of the first measured current from the start of self-heating to the end of self-heating is basically the same as the effective value of the second measured current from the start of self-heating to the end of self-heating. The first adjustment scheme ensures that the difference between the total charge loss of the first battery core group 1 and the total charge loss of the second battery core group 2 caused by self-heating falls within a range, thereby ensuring the balance between the first battery core group 1 and the second battery core group 2, and to some extent controlling the adverse effect caused by self-heating on the amount of available charge and the endurance driving distance of the electric vehicle.

[0118] The following describes a second method for adjusting the drive signal.

[0119] Example 1: The first controller adjusting the drive signal in the self-heating process to enable the ratio of the first target difference to the first difference to fall within a preset interval range includes steps S302 and S304.

[0120] Step S302: A second intensity integrated value of the first measured current and a second intensity integrated value of the second measured current are obtained.

[0121] The first measured current is the measured current flowing through the first battery core group 1, and the second measured current is the measured current flowing through the second battery core group 2.

[0122] The second intensity integrated value of the first measured current is the intensity integrated value of the first measured current from the start of self-heating to the end of the current adjustment period, and the second intensity integrated value of the second measured current is the intensity integrated value of the second measured current from the start of self-heating to the end of the current adjustment period.

[0123] Step S304: The driving signal is set for a next adjustment period based on the second intensity integrated value of the first measured current and the second intensity integrated value of the second measured current.

[0124] In one example, setting the drive signal for the next adjustment period includes setting a duty cycle and / or a time series status of the drive signal for the next adjustment period such that a second absolute value is less than the first absolute value. The first absolute value is an absolute value of a difference between a second intensity integrated value of the first measured current and a second intensity integrated value of the second measured current. The second absolute value is an absolute value of a difference between a fourth intensity integrated value of the first measured current and a fourth intensity integrated value of the second measured current. The fourth intensity integrated value of the first measured current is an intensity integrated value of the first measured current from a start of self-heating to an end of the next adjustment period, and the fourth intensity integrated value of the second measured current is an intensity integrated value of the second measured current from a start of self-heating to an end of the next adjustment period.

[0125] For example, if the second intensity integrated value of the first measured current is 90 and the second intensity integrated value of the second measured current is 100, the first absolute value is 10. The driving signal is set for the next adjustment period such that the fourth intensity integrated value of the first measured current is 95 and the fourth intensity integrated value of the second measured current is 102. In this case, the second absolute value is 7. The second absolute value is smaller than the first absolute value, which indicates that when the next period ends, the difference between the total charge loss of the first battery core group 1 and the total charge loss of the second battery core group 2 decreases.

[0126] In one example, if the ratio of the second intensity integrated value of the first measured current to the second intensity integrated value of the second measured current falls within a preset interval range, the drive signal may not be adjusted. The drive signal for the next adjustment period is the same as the drive signal for the current adjustment period. If the second intensity integrated value of the first measured current and the second intensity integrated value of the second measured current fall outside the preset interval range, the duty cycle and / or time series status of the drive signal for the next adjustment period are set such that the second absolute value is smaller than the first absolute value.

[0127] In this example, the first controller adjusts the drive signal in real time so that the difference between the charge loss of the first battery core group 1 and the charge loss of the second battery core group 2 is compensated in time, thereby avoiding sudden fluctuations in the excitation current and improving the stability of the self-heating process.

[0128] Example 2: The first controller adjusts the driving signal in the self-heating process to enable the ratio of the first target difference to the first difference to fall within a preset interval range, including steps S402 to S406.

[0129] Step S402: A second intensity integrated value of the first measured current and a second intensity integrated value of the second measured current are obtained.

[0130] The first measured current is the measured current flowing through the first battery core group 1, and the second measured current is the measured current flowing through the second battery core group.

[0131] The second intensity integrated value of the first measured current is the intensity integrated value of the first measured current from the start of self-heating to the end of the current adjustment period, and the second intensity integrated value of the second measured current is the intensity integrated value of the second measured current from the start of self-heating to the end of the current adjustment period.

[0132] Step S404: A third intensity integrated value of the first measured current and a third intensity integrated value of the second measured current are obtained.

[0133] The third intensity integrated value of the first measured current is the intensity integrated value of the first measured current within the current adjustment period, and the third intensity integrated value of the second measured current is the intensity integrated value of the second measured current within the current adjustment period.

[0134] Step S406: The drive signal is set for the next adjustment period based on the second intensity integrated value of the first measured current, the second intensity integrated value of the second measured current, the third intensity integrated value of the first measured current, and the third intensity integrated value of the second measured current.

[0135] In one example, setting the drive signal for the next adjustment period includes setting a duty cycle and / or a time series status of the drive signal for the next adjustment period such that a second absolute value is less than the first absolute value. The first absolute value is an absolute value of a difference between a second intensity integrated value of the first measured current and a second intensity integrated value of the second measured current. The second absolute value is an absolute value of a difference between a fourth intensity integrated value of the first measured current and a fourth intensity integrated value of the second measured current. The fourth intensity integrated value of the first measured current is an intensity integrated value of the first measured current from a start of self-heating to an end of the next adjustment period, and the fourth intensity integrated value of the second measured current is an intensity integrated value of the second measured current from a start of self-heating to an end of the next adjustment period.

[0136] In one example, if the ratio of the second intensity integral value of the first measured current to the second intensity integral value of the second measured current falls within a preset interval range and the ratio of the third intensity integral value of the first measured current to the third intensity integral value of the second measured current also falls within a preset interval range, the drive signal may not be adjusted. The drive signal for the next adjustment period is the same as the drive signal for the current adjustment period. If the ratio of the second intensity integral value of the first measured current to the second intensity integral value of the second measured current falls outside the preset interval range, the duty cycle and / or time series status of the drive signal for the next adjustment period is set such that the second absolute value is smaller than the first absolute value. If the ratio of the third intensity integral value of the first measured current to the third intensity integral value of the second measured current falls outside the preset interval range, the duty cycle and / or time series status of the drive signal in the next adjustment period is set such that the second absolute value is smaller than the first absolute value.

[0137] In this example, the first controller adjusts the driving signal in real time, so that the difference between the charge loss of the first battery core group 1 and the charge loss of the second battery core group 2 is corrected in time, thereby avoiding the sudden fluctuation of the excitation current and improving the stability of the self-heating process. Furthermore, during the adjustment of the driving signal, the driving signal can be determined for the next adjustment period in an elaborated manner, taking into account all of the second intensity integrated value of the first actual measured current, the second intensity integrated value of the second actual measured current, the third intensity integrated value of the first actual measured current, and the third intensity integrated value of the second actual measured current.

[0138] Example 3: The first controller adjusting the drive signal in the self-heating process to enable the ratio of the first target difference to the first difference to fall within a preset interval range includes steps P302 and P304.

[0139] Step P302: A first effective value of the first measured current and a first effective value of the second measured current are obtained.

[0140] The first measured current is the measured current flowing through the first battery core group 1, and the second measured current is the measured current flowing through the second battery core group 2.

[0141] The first effective value of the first measured current is the effective value of the first measured current from the start of self-heating to the end of the current adjustment period, and the first effective value of the second measured current is the effective value of the second measured current from the start of self-heating to the end of the current adjustment period.

[0142] Step P304: The drive signal is set for the next adjustment period based on the first effective value of the first measured current and the first effective value of the second measured current.

[0143] In one example, setting the drive signal for the next adjustment period includes setting a duty cycle and / or a time series status of the drive signal for the next adjustment period such that a fourth absolute value is less than the third absolute value. The third absolute value is an absolute value of a difference between a first effective value of the first measured current and a first effective value of the second measured current. The fourth absolute value is an absolute value of a difference between a third effective value of the first measured current and a third effective value of the second measured current. The third effective value of the first measured current is an effective value of the first measured current from a start of self-heating to an end of the next adjustment period, and the third effective value of the second measured current is an effective value of the second measured current from a start of self-heating to an end of the next adjustment period.

[0144] For example, if the first effective value of the first measured current is 90 and the first effective value of the second measured current is 100, the third absolute value is 10. The drive signal is adjusted for the next adjustment period so that the third effective value of the first measured current is 95 and the third effective value of the second measured current is 102. In this case, the fourth absolute value is 7. The fourth absolute value is smaller than the third absolute value, which indicates that when the next period ends, the difference between the total charge loss of the first battery core group 1 and the total charge loss of the second battery core group 2 decreases.

[0145] In one example, if the ratio of the first effective value of the first measured current to the first effective value of the second measured current falls within a preset interval range, the drive signal is not adjusted for the next adjustment period. If the first effective value of the first measured current and the first effective value of the second measured current fall outside the preset interval range, the duty cycle of the drive signal and / or the time series status of the drive signal in the next adjustment period is adjusted such that the fourth absolute value is smaller than the third absolute value.

[0146] In this example, the first controller adjusts the drive signal in real time so that the difference between the charge loss of the first battery core group 1 and the charge loss of the second battery core group 2 is compensated in time, thereby avoiding sudden fluctuations in the excitation current and improving the stability of the self-heating process.

[0147] Example 4: The first controller adjusts the driving signal in the self-heating process to enable the ratio of the first target difference to the first difference to fall within a preset interval range, including steps P402 to P406.

[0148] Step P402: A first effective value of the first measured current and a first effective value of the second measured current are obtained.

[0149] The first measured current is the measured current flowing through the first battery core group 1, and the second measured current is the measured current flowing through the second battery core group 2.

[0150] The first effective value of the first measured current is the effective value of the first measured current from the start of self-heating to the end of the current adjustment period, and the first effective value of the second measured current is the effective value of the second measured current from the start of self-heating to the end of the current adjustment period.

[0151] Step P404: A second effective value of the first measured current and a second effective value of the second measured current are obtained.

[0152] The second effective value of the first measured current is the effective value of the first measured current within a current adjustment period, and the second effective value of the second measured current is the effective value of the second measured current within a current adjustment period.

[0153] Step P406: The drive signal is set for the next adjustment period based on the first effective value of the first measured current, the first effective value of the second measured current, the second effective value of the first measured current, and the second effective value of the second measured current.

[0154] In one example, setting the drive signal for the next adjustment period includes setting a duty cycle and / or a time series status of the drive signal for the next adjustment period such that a fourth absolute value is less than the third absolute value. The third absolute value is an absolute value of a difference between a first effective value of the first measured current and a first effective value of the second measured current. The fourth absolute value is an absolute value of a difference between a third effective value of the first measured current and a third effective value of the second measured current. The third effective value of the first measured current is an effective value of the first measured current from a start of self-heating to an end of the next adjustment period, and the third effective value of the second measured current is an effective value of the second measured current from a start of self-heating to an end of the next adjustment period.

[0155] In one example, if the ratio of the first effective value of the first measured current to the first effective value of the second measured current falls within a preset interval range and the ratio of the second effective value of the first measured current to the second effective value of the second measured current also falls within a preset interval range, the drive signal is not adjusted for the next adjustment period. If the ratio of the first effective value of the first measured current to the first effective value of the second measured current falls outside the preset interval range, the duty cycle of the drive signal and / or the time series status of the drive signal is adjusted for the next adjustment period such that the fourth absolute value is smaller than the third absolute value. If the ratio of the second effective value of the first measured current to the second effective value of the second measured current falls outside the preset interval range, the duty cycle of the drive signal and / or the time series status of the drive signal is adjusted for the next adjustment period such that the fourth absolute value is smaller than the third absolute value.

[0156] In this example, the first controller adjusts the driving signal in real time, so that the difference between the charge loss of the first battery core group 1 and the charge loss of the second battery core group 2 is corrected in time, thereby avoiding the sudden fluctuation of the excitation current and improving the stability of the self-heating process. Furthermore, during the adjustment of the driving signal, the driving signal can be determined for the next adjustment period in an elaborated manner, taking into account all of the first effective value of the first measured current, the first effective value of the second measured current, the second effective value of the first measured current, and the second effective value of the second measured current.

[0157] In the second adjustment method, the control method of the first controller is feedback closed-loop control. In one example, the adjustment method of the first controller is PI (Proportion Integration) control. In one example, the adjustment method of the first controller is PID (Proportion Integration Differentiation) control, that is, a combination control of three functions of proportional, integral and differential. Proportional control is a simple proportional control method. When only proportional control is used, steady-state errors exist in the system, and constant disturbances added from the outside cannot be completely eliminated. The main purpose of integral control is to eliminate steady-state errors. The purpose of differential control is to eliminate sudden fluctuations.

[0158] In the second adjustment manner, although there still exists a charge loss error caused by the electric control error and the motor coil loss, the error is corrected and compensated in time based on the adjustment period, thereby ensuring that the intensity integral value or effective value of the first measured current from the start of self-heating to the end of self-heating is essentially the same as the intensity integral value or effective value of the second measured current from the start of self-heating to the end of self-heating. In the second adjustment manner, it is ensured that the difference between the total charge loss of the first battery core group 1 and the total charge loss of the second battery core group 2 caused by self-heating falls within a range, thereby ensuring the balance between the first battery core group 1 and the second battery core group 2, and the adverse effect caused by self-heating on the amount of available charge and the endurance driving distance of the electric vehicle can be controlled to a certain extent.

[0159] In the self-heating process of the power battery, it is very important to control the excitation current. The inventor has found through research that under the operation of a relatively large excitation current, the temperature of the power battery rises relatively quickly. However, as the excitation current increases, the adverse effect caused to the battery capacity in the heating process also increases. Therefore, in the self-heating process, both factors need to be taken into account.

[0160] In this embodiment of the present disclosure, the battery core unit in the battery core group is a lithium iron phosphate battery core unit, a ternary lithium battery core unit, or another chemical battery. After the capacity retention rate of the two batteries during self-heating is obtained in advance by using a large amount of testing, the following control policy is formulated.

[0161] In one example, the first controller is further configured to adjust the driving signal in the self-heating process so that the average value of the effective value of the current flowing through the first battery core group 1 is between 0.5C and 5C within the entire self-heating period, and the average value of the effective value of the current flowing through the second battery core group 2 is between 0.5C and 5C within the entire self-heating period. In one example, the requirement can be implemented by adjusting the duty cycle and / or the time series status of the driving signal. In this example, both the current flowing through the first battery core group 1 and the current flowing through the second battery core group 2 refer to theoretical current or actual current.

[0162] In one example, the first controller is further configured to adjust the driving signal in the self-heating process so that the average value of the effective value of the current flowing through the neutral point of the AC motor is between 1C and 10C within the entire self-heating period. In one example, the requirement can be implemented by adjusting the duty cycle and / or the time series status of the driving signal. In this example, both the current flowing through the first battery core group 1 and the current flowing through the second battery core group 2 refer to theoretical current or actual measured current.

[0163] In one example, the driving signal output by the first controller is a PWM (Pulse width modulation wave) driving signal. In one example, the first controller outputs the driving signal in a SVPWM (Space Vector Pulse Width Modulation) modulation manner. By adjusting the duty cycle, time series, etc. of the driving signal, the IGBT can output current signals with different frequencies and amplitudes in real time.

[0164] By using the above-mentioned control policy, the battery core can be prevented from being overcharged or over-discharged at low temperature, thereby ensuring the safety of the battery core. In this embodiment of the present disclosure, by using the above-mentioned self-heating policy, the heating efficiency and safety in the self-heating process are taken into account, the power battery can be efficiently heated, excessively large damage to the battery life is avoided, and the battery safety is guaranteed. In this embodiment of the present disclosure, the above-mentioned policies can be overlapped to achieve better effect.

[0165] In one example, the first controller is further configured to perform synchronous control on the on / off states of three upper bridge arms and perform synchronous control on the on / off states of three lower bridge arms in the self-heating process. That is, the three upper bridge arms are all turned on / off. Correspondingly, the three lower bridge arms are all turned off / on. In this way, the performance of the power electronic switch can be fully utilized, and the self-heating effect is improved.

[0166] The first controller in this embodiment of the present disclosure may include a processor, a memory, and a program or instructions stored in the memory and executable on the processor, which when executed by the processor, implements any heating control policy according to the above-mentioned embodiments.

[0167] An embodiment of the present disclosure provides an electric vehicle, including a power battery and a heating system for heating the power battery according to any one of the preceding embodiments.

[0168] The embodiments of the present disclosure are all described step by step, and for the same or similar parts in the embodiments, refer to these embodiments, and the description of each embodiment focuses on the differences from other embodiments. For the relevant details of the electric vehicle embodiment, please refer to the partial description of the heating system embodiment.

[0169] The embodiments of the present disclosure have been described above. Other embodiments fall within the scope of the appended claims. In some embodiments, the operations or steps recited in the claims may be performed in a different order than the operations or steps in the embodiments and the expected results may still be achieved. Furthermore, the processes depicted in the appended drawings are not necessarily performed in a particular order or sequence to achieve the expected results. In some implementations, multitasking and parallel processing may be feasible or beneficial.

[0170] The embodiments of the present disclosure may be a system, a method, and / or a computer program product that may include a computer-readable storage medium carrying computer instructions used to enable a processor to implement aspects of the embodiments of the present disclosure.

[0171] A computer-readable storage medium may be a tangible device that can hold and store computer instructions used by a computer instruction execution device. For example, a computer-readable storage medium may be, but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination thereof. More specific examples (non-exhaustive list) of computer-readable media include portable computer disks, hard disks, random access memories (RAMs), read-only memories (ROMs), erasable programmable read-only memories (EPROMs or flash memories), static random access memories (SRAMs), portable compressed disk read-only memories (CD-ROMs), digital versatile disks (DVDs), memory sticks, floppy disks, mechanically encoded devices such as punch cards or protruding structures in grooves on which computer instructions are stored, and any suitable combinations described above. A computer-readable storage medium as used herein is not to be interpreted as a momentary signal, such as an electric wave or other freely propagating electromagnetic wave, an electromagnetic wave propagated by using a waveguide or other transmission medium (e.g., by using light pulses in a fiber optic cable), or an electrical signal transmitted by using a wire.

[0172] The computer instructions described herein may be downloaded from a computer-readable storage medium into each computing / processing device or may be downloaded to an external computer or storage device by using a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network may include copper transmission cables, fiber optic transmissions, wireless transmissions, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter or network interface in each computing / processing device receives the computer instructions from the network and transfers the computer instructions so that the computer instructions are stored in a computer-readable storage medium in each computing / processing device.

[0173] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to embodiments of the present disclosure. In this regard, each box in the flowchart or block diagram may represent a module, a program segment, or a portion of computer instructions. A module, a program segment, or a portion of computer instructions includes one or more executable computer instructions used to implement a specified logical function. In some alternative implementations, the functions annotated in the boxes may alternatively be performed in a different order than that annotated in the accompanying drawings. For example, two boxes that are actually shown in succession may essentially be performed in parallel, and in some cases the two boxes may be performed in a reverse order. This is determined by the related functionality. It should also be noted that each box in the block diagrams and / or flowcharts, as well as combinations of boxes in the block diagrams and / or flowcharts, may be implemented by using a dedicated hardware-based system configured to perform the specified function or operation, or by using a combination of dedicated hardware and computer instructions. Those skilled in the art will appreciate that the equivalents of hardware-based implementations, software-based implementations, and combinations of software and hardware implementations are readily apparent.

[0174] The embodiments of the present disclosure have been described above, and the foregoing description is illustrative, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are apparent to those skilled in the art without departing from the scope of the described embodiments. The selection of terms used herein is intended to best describe the embodiments, practical applications, or principles of improvements of technology in the market, or to enable those skilled in the art to understand the embodiments disclosed herein.

Claims

1. A heating system for heating a power battery, the power battery comprising a first battery core group (1) and a second battery core group (2) connected in series, the electromotive force of the first battery core group (1) not being equal to the electromotive force of the second battery core group (2), The heating system includes an inverter (3), an AC motor (4), and a first controller (5); the inverter (3) has three bridge arms, a positive electrode of the power battery is connected to an upper bridge arm of the inverter (3), a negative electrode of the power battery is connected to a lower bridge arm of the inverter (3), intermediate points of the three bridge arms of the inverter (3) are respectively connected to front ends of the three-phase coils of the AC motor, and rear ends of the AC motor are connected to each other to form a neutral point (N); the neutral point (N) of the AC motor is connected to a first connection point by a connection line (S1), the first connection point being a connection point (P) between the first battery core group (1) and the second battery core group (2); the first controller (6) is configured to input a drive signal to the inverter (3), and the first battery core group (1), the second battery core group (2), the inverter (3), the AC motor (4), and the connection line (S1) form an AC self-heating loop; The first controller (6) is further configured to adjust the drive signal in a self-heating process to enable a ratio of a first target difference to a first difference to fall within a preset interval range; A heating system, wherein the first target difference is the difference between the first difference and the second difference, the first difference being the difference between the electromotive force of the first battery core group (1) and the electromotive force of the second battery core group (2) when self-heating begins, and the second difference being the difference between the electromotive force of the first battery core group (1) and the electromotive force of the second battery core group (2) when the self-heating ends.

2. The heating system of claim 1 , wherein the preset interval range is (−0.9, +0.9).

3. The first controller (6) adjusts the drive signal in a self-heating process to enable a ratio of a first target difference to a first difference to fall within a preset interval range. adjusting, by the first controller (6), a duty cycle of the driving signal and / or a time series status of the driving signal in the self-heating process so as to enable the ratio of the first target difference to the first difference to fall within the preset interval range. The heating system of claim 1 , comprising:

4. The first controller (6) adjusts the drive signal in a self-heating process to enable a ratio of a first target difference to a first difference to fall within a preset interval range. adjusting, by the first controller (6), the drive signal to enable a ratio of a second target difference to a fifth intensity integral value to fall within the preset interval range.

2. The heating system of claim 1, further comprising: a first intensity integral value of a current flowing through the first battery core group (1) in the self-heating process; a sixth intensity integral value of a current flowing through the second battery core group (2) in the self-heating process; and a current intensity integral value of a current intensity of the current over time.

5. The first controller (6) adjusts the drive signal in a self-heating process to enable a ratio of a first target difference to a first difference to fall within a preset interval range. calculating a first theoretical current and a second theoretical current in the self-heating process; correcting the first theoretical current and the second theoretical current based on a first preset ratio; setting the drive signal based on a corrected first theoretical current and a corrected second theoretical current; 5. The heating system of claim 1, wherein the first theoretical current is a theoretical current flowing through the first battery core group (1) and the second theoretical current is a theoretical current flowing through the second battery core group (2).

6. the first predetermined ratio is predetermined by using heating test experiments; Determining the first predetermined ratio comprises: obtaining a ratio of the first intensity integrated value of the first experimental current to the first intensity integrated value of the second experimental current as a second ratio; determining the first predetermined ratio, the first predetermined ratio being the reciprocal of the second ratio; the first experimental current is an actual current flowing through the first battery core group (1) in the heating test experiment, and the second experimental current is an actual current flowing through the second battery core group (2) in the heating test experiment; 6. The heating system of claim 5, wherein the first intensity integral value of the first experimental current is an intensity integral value of the first experimental current from the start of the heating test experiment to the end of the heating test experiment, and the first intensity integral value of the second experimental current is an intensity integral value of the second experimental current from the start of the heating test experiment to the end of the heating test experiment.

7. The first controller (6) adjusts the drive signal in a self-heating process to enable a ratio of a first target difference to a first difference to fall within a preset interval range. obtaining a second intensity integrated value of the first measured current and a second intensity integrated value of the second measured current; setting a drive signal for a next adjustment period based on the second intensity integrated value of the first measured current and the second intensity integrated value of the second measured current; the first measured current is an actual current flowing through the first battery core group, and the second measured current is an actual current flowing through the second battery core group; 2. The heating system of claim 1, wherein the second intensity integral value of the first measured current is an intensity integral value of the first measured current from a start of the self-heating to an end of a current adjustment period, and the second intensity integral value of the second measured current is an intensity integral value of the second measured current from the start of the self-heating to the end of the current adjustment period.

8. The first controller (6) adjusts the drive signal in a self-heating process to enable a ratio of a first target difference to a first difference to fall within a preset interval range. obtaining a second intensity integrated value of the first measured current and a second intensity integrated value of the second measured current; obtaining a third intensity integrated value of the first measured current and a third intensity integrated value of the second measured current; setting a drive signal for a next adjustment period based on the second intensity integrated value of the first measured current, the second intensity integrated value of the second measured current, the third intensity integrated value of the first measured current, and the third intensity integrated value of the second measured current; the first measured current is an actual measured current flowing through the first battery core group (1), and the second measured current is an actual measured current flowing through the second battery core group (2); the second intensity integrated value of the first measured current is an intensity integrated value of the first measured current from a start of the self-heating to an end of a current adjustment period, and the second intensity integrated value of the second measured current is an intensity integrated value of the second measured current from the start of the self-heating to the end of the current adjustment period, 2. The heating system of claim 1, wherein the third intensity integral of the first measured current is an intensity integral of the first measured current within the current adjustment period, and the third intensity integral of the second measured current is an intensity integral of the second measured current within the current adjustment period.

9. setting the drive signal for a next adjustment period setting a duty cycle and / or a time sequence status of the drive signal for the next adjustment period such that the second absolute value is less than the first absolute value. the first absolute value being an absolute value of a difference between the second intensity integrated value of the first measured current and the second intensity integrated value of the second measured current; the second absolute value is an absolute value of a difference between a fourth intensity integrated value of the first measured current and a fourth intensity integrated value of the second measured current; 9. The heating system of claim 7 or 8, wherein the fourth intensity integral value of the first measured current is an intensity integral value of the first measured current from the start of the self-heating to the end of the next adjustment period, and the fourth intensity integral value of the second measured current is an intensity integral value of the second measured current from the start of the self-heating to the end of the next adjustment period.

10. The first controller (6) adjusts the drive signal in a self-heating process to enable a ratio of a first target difference to a first difference to fall within a preset interval range. obtaining a first effective value of a first measured current and a first effective value of a second measured current; setting a drive signal for a next adjustment period based on the first effective value of the first measured current and the first effective value of the second measured current; the first measured current is an actual measured current flowing through the first battery core group (1), and the second measured current is an actual measured current flowing through the second battery core group (2); 2. The heating system of claim 1, wherein the first effective value of the first measured current is an effective value of the first measured current from the start of the self-heating to the end of a current regulation period, and the first effective value of the second measured current is an effective value of the second measured current from the start of the self-heating to the end of the current regulation period.

11. The first controller (6) adjusts the drive signal in a self-heating process to enable a ratio of a first target difference to a first difference to fall within a preset interval range. obtaining a first effective value of a first measured current and a first effective value of a second measured current; obtaining a second effective value of the first measured current and a second effective value of the second measured current; setting a drive signal for a next adjustment period based on the first effective value of the first measured current, the first effective value of the second measured current, the second effective value of the first measured current, and the second effective value of the second measured current; the first measured current is an actual measured current flowing through the first battery core group (1), and the second measured current is an actual measured current flowing through the second battery core group (2); the first effective value of the first measured current is an effective value of the first measured current from the start of the self-heating to the end of a current adjustment period, and the first effective value of the second measured current is an effective value of the second measured current from the start of the self-heating to the end of the current adjustment period; 2. The heating system of claim 1, wherein the second effective value of the first measured current is an effective value of the first measured current within the current regulation period, and the second effective value of the second measured current is an effective value of the second measured current within the current regulation period.

12. setting the drive signal for a next adjustment period setting a duty cycle and / or a time series status of the drive signal for the next adjustment period such that a fourth absolute value is less than the third absolute value. the third absolute value being an absolute value of a difference between the first effective value of the first measured current and the first effective value of the second measured current; the fourth absolute value being an absolute value of a difference between a third effective value of the first measured current and a third effective value of the second measured current; 12. The heating system of claim 10 or 11, wherein the third effective value of the first measured current is an effective value of the first measured current from the start of the self-heating to the end of the next adjustment period, and the third effective value of the second measured current is an effective value of the second measured current from the start of the self-heating to the end of the next adjustment period.

13. 12. The heating system according to claim 7, 8, 10 or 11, wherein the regulation strategy of the first controller (6) is a PID regulation strategy.

14. 2. The heating system of claim 1, wherein the first controller (6) is further configured to perform synchronous control over on / off states of three upper bridge arms and to perform synchronous control over on / off states of three lower bridge arms in the self-heating process.

15. The heating system of claim 1, wherein the first controller (6) is further configured to adjust the drive signal during the self-heating process so that an average value of the effective value of the current flowing through the first battery core group (1) is between 0.5 C and 5 C within the entire self-heating period, and an average value of the effective value of the current flowing through the second battery core group (2) is between 0.5 C and 5 C within the entire self-heating period.

16. 2. The heating system of claim 1, wherein the first controller (6) is further configured to adjust the drive signal during the self-heating process such that an average value of the effective value of the current flowing through the neutral point (N) of the AC motor is between 1 C and 10 C within a whole self-heating period.

17. 17. An electric vehicle comprising a power battery and a heating system according to any one of claims 1 to 16.

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