Heating system for heating power batteries, and electric vehicles

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 the priority and benefit of Chinese Patent Application No. 202210456060.9, titled "HEATING SYSTEM FOR HEATING POWER BATTERY, AND ELECTRIC VEHICLE", filed on April 28, 2022. The entire content of the above application is incorporated herein by reference.

[0002] This 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 Art

[0003] The characteristics of a power battery are greatly affected by the ambient temperature. Especially in a low - temperature environment, the energy and power characteristics of a lithium - ion power battery significantly decay. Therefore, it is necessary to heat the battery at low temperatures. How to improve the heating performance of the battery core in a heating method that self - generates heat of the battery core by using an exciting current has become an important issue.

Summary of the Invention

Means for Solving the Problems

[0004] An object of this disclosure is to provide a new technical solution for a heating system for heating a power battery.

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

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

[0007] According to a first aspect of this disclosure, a heating system for heating a power battery is provided. The power battery includes a first group of battery cores and a second group of battery cores connected in series, the electromotive force of the first group of battery cores being not equal to the electromotive force of the second group of battery cores. The heating system includes an inverter, an AC motor, and a first controller. The inverter includes three bridge arms, the positive terminal of the power battery is connected to the upper bridge arm of the inverter, and the negative terminal of the power battery is connected to the lower bridge arm of the inverter. The midpoints of the three bridge arms of the inverter are each 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 by a connecting wire to a first connection point, which is the connection point between the first group of battery cores and the second group of battery cores. The first controller is configured to input a drive signal to the inverter. The first group of battery cores, the second group of battery cores, the inverter, the AC motor, and the connecting wire form an AC self-heating loop. The first controller (6) is further configured to adjust 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 target difference is the difference between the first difference and the second difference, where the first difference is the difference between the electromotive force of the first battery core group and the electromotive force of the second battery core group when self-heating begins, and the second difference is the difference between the electromotive force of the first battery core group and the electromotive force of the second battery core group when 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, the adjustment of a drive signal in a self-heating process by a first controller to enable the ratio of a first target difference to a first difference to fall within a preset interval range includes the adjustment of the duty cycle and / or time-series status of the drive signal in a self-heating process by the first controller to enable the ratio of a first target difference to a first difference to fall within a preset interval range.

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

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

[0012] According to one embodiment of the present disclosure, the adjustment of a drive signal in a self-heating process to enable the ratio of a first target difference to a first difference to fall within a preset interval range by a first controller includes 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, and setting a drive signal based on the corrected first theoretical current and the corrected second theoretical current. The first theoretical current is the theoretical current flowing through a first group of battery cores, and the second theoretical current is the theoretical current flowing through a second group of battery cores.

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

[0014] According to one embodiment of the present disclosure, the adjustment of a drive signal in a self-heating process to enable the ratio of a first target difference to a first difference to fall within a preset interval range by a first controller includes obtaining a second intensity integrated value of a first measured current and a second intensity integrated value of a second measured current, and setting a drive signal for the 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 a first group of battery cores, and the second measured current is the measured current flowing through a second group of battery cores.

[0015] The second integrated intensity value of the first measured current is the integrated intensity value of the first measured current from the start of self-heating to the end of the current adjustment period, and the second integrated intensity value of the second measured current is the integrated intensity 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, the adjustment of a drive signal in a self-heating process to enable the ratio of a first target difference to a first difference to fall within a preset interval range includes obtaining a second integrated intensity value of a first measured current and a second integrated intensity value of a second measured current, obtaining a third integrated intensity value of a first measured current and a third integrated intensity value of a second measured current, and setting a drive signal for the next adjustment period based on the second integrated intensity value of the first measured current, the second integrated intensity value of the second measured current, the third integrated intensity value of the first measured current, and the third integrated intensity 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 integrated intensity value of the first measured current is the integrated intensity value of the first measured current from the start of self-heating to the end of the current adjustment period, and the second integrated intensity value of the second measured current is the integrated intensity value of the second measured current from the start of self-heating to the end of the current adjustment period.

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

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

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

[0022] The fourth integrated intensity value of the first measured current is the integrated intensity value of the first measured current from the start of self-heating to the end of the next adjustment period, and the fourth integrated intensity value of the second measured current is the integrated intensity 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, the adjustment of a drive signal in a self-heating process to enable the ratio of a first target difference to a first difference to fall within a preset interval range includes obtaining a first RMS value of a first measured current and a first RMS value of a second measured current, and setting a drive signal for the next adjustment period based on the first RMS value of the first measured current and the first RMS 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, the adjustment of a drive signal in a self-heating process to enable the ratio of a first target difference to a first difference to fall within a preset interval range includes: obtaining a first RMS value of a first measured current and a first RMS value of a second measured current; obtaining a second RMS value of a first measured current and a second RMS value of a second measured current; and setting a drive signal for the next adjustment period based on the first RMS value of the first measured current, the first RMS value of the second measured current, the second RMS value of the first measured current, and the second RMS 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 the current adjustment period, and the second effective value of the second measured current is the effective value of the second measured current within the current adjustment period.

[0030] According to an embodiment of the present disclosure, setting the drive signal for the next adjustment period includes setting the duty cycle and / or the time-series status of the drive signal for the next adjustment period such that the fourth absolute value is smaller 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 an embodiment of the present disclosure, the adjustment method of the first controller is a PID adjustment method.

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

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

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

[0038] According to one embodiment of the present disclosure, the central segment is a curved structure comprising 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, an electric vehicle is provided which includes a power battery and a heating system according to any one of the embodiments described above.

[0040] According to one embodiment of the present disclosure, a loop is added to the original circuit topology of the electric vehicle, the loop extending from the neutral point of the AC motor to the connection point between a first battery core group and a 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, a first controller adjusts the drive signal in the self-heating process to enable the ratio of a first target difference to a first difference to fall within a preset interval range, thereby ensuring that the difference between the charge loss of the first battery core group and the charge loss of the second battery core group does not become excessively large at the end of self-heating, thereby ensuring a balance between the first and second battery core groups and reducing the adverse effects of self-heating on the amount of available charge and the endurance range of the electric vehicle.

[0041] Other features and advantages of this disclosure will become apparent from the following detailed description of exemplary embodiments of this disclosure with reference to the accompanying drawings.

[0042] The accompanying drawings are incorporated into this disclosure, constitute part of this disclosure, illustrate embodiments conforming to this disclosure, and are used in conjunction with this disclosure to illustrate the principles of this disclosure. [Brief explanation of the drawing]

[0043] [Figure 1] This is a block diagram of a heating system for heating a power battery according to one embodiment of the present disclosure. [Figure 2] This is a specific 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 switches 6. First Controller 7 Protection circuit 8. Second controller S1 connecting wire [Modes for carrying out the invention]

[0045] Next, various exemplary embodiments of this disclosure will be described in detail with reference to the accompanying drawings.

[0046] The following description of at least one example of an embodiment is merely illustrative and is not in any way intended to serve as a limitation on the present disclosure or its use or application.

[0047] Please note that in the following attached drawings, similar numbers and letters refer to the same items, and therefore, once an item is defined in a drawing, no further explanation of that item is required in subsequent attached drawings.

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

[0049] In embodiments of this disclosure, the power battery includes a first group of battery cores and a second group of battery cores 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, the positive terminal of the power battery is connected to the upper bridge arm of the inverter, and the negative terminal of the power battery is connected to the lower bridge arm of the inverter. The midpoints of the three bridge arms of the inverter are each 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 by a connecting wire to a first connection point, which is the connection point between the first group of battery cores and the second group of battery cores. The first controller is configured to input a drive signal to the inverter. The first group of battery cores, the second group of battery cores, the inverter, the AC motor, and the connecting wire form an AC self-heating loop. The first controller is configured to input a drive 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 embodiments of the present disclosure, a heating system for heating a power battery and an electric vehicle, a loop is added to the original circuit topology of the electric vehicle, the loop extending 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 embodiments.

[0051] As shown in Figures 1 and 2, a heating system for heating a power battery provided in an embodiment of this 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 connected in a star configuration, with the three 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] Inverter 3 includes three bridge arms, with the positive terminal of the power battery connected to the upper bridge arm of inverter 3 and the negative terminal of the power battery connected to the lower bridge arm of inverter 3. The midpoints of the three bridge arms of inverter 3 are each connected to the front ends of the three-phase coils of the AC motor 4. In one example, as shown in Figures 1 and 2, inverter 3 includes IGBTs T1, T2, T3, T4, T5, and T6. IGBTs T1-T6 form the three bridge arms. IGBTs (Insulated Gate Bipolar Transistors) are composite voltage-driven power semiconductor devices that include BJTs (Bipolar Junction Transistors) and MOS transistors (Metal-Oxide-Semiconductor Field-Effect Transistors), and have the advantages of high input impedance of MOSFETs and low turn-on voltage drop of GTRs (Giant Transistors). As shown in Figure 2, in inverter 3, each IGBT is further connected in parallel to a diode, which may serve as circuit protection. In another embodiment, IGBTs T1 to T6 can each be replaced by MOS transistors. In another embodiment, IGBTs T1 to T6 can each be replaced by silicon carbide (SiC) power tubes. The neutral point N of the AC motor is connected to a first connection point P by a connecting line S1, and the first connection point P is the connection point between the first battery core group and the second battery core group.

[0055] In one example, the first and second battery core groups belong to the same battery pack, which provides externally all positive terminal ports, all negative terminal ports, and a third port led from the first connection point P. The third port is connected to the neutral point N of the AC motor by a connecting wire S1.

[0056] The first controller 6 is configured to input drive signals to the inverter 3 in order 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 charge each other alternately. In one example, as shown in Figure 2, the first controller 6 outputs six drive signals Q1 to Q6. Drive signal Q1 is applied to IGBT T1, drive signal Q2 is applied to IGBT T2, drive signal Q3 is applied to IGBT T3, drive signal Q4 is applied to IGBT T4, drive signal Q5 is applied to IGBT T5, and drive signal Q6 is applied to 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 drive signals Q1 to Q6 to IGBTs T1 to T6 so that the first battery core group 1 and the second battery core group 2 charge each other alternately. 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 AC current, inputs the AC current to the AC motor 4, and the AC motor 4 stores electrical energy in its coil to charge the second battery core group 2. Next, the second battery core group 2 discharges, the inverter 3 converts the DC current output by the second battery core group 2 into AC current, inputs the AC current to the AC motor 4, and the AC motor 4 stores electrical energy in its 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 generate self-heating of the battery cores.

[0057] As shown in Figures 1 and 2, switch 5 is located on 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 switch 5 so that the heating element is turned on when it is necessary to heat the power battery and turned off when it is not necessary to heat the power battery, in order to ensure the safety of the vehicle and the power battery. For example, the second controller 8 controls switch 5 so that it is turned off when the electric vehicle is running, in order to ensure the safety of the vehicle while it is running.

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

[0059] Figure 1 further illustrates the power distribution box of an electric vehicle. The power distribution box primarily distributes power based on the power load of the electric vehicle.

[0060] Based on the heating system for heating the power battery provided in the embodiments of this disclosure, the connecting wires are added based on the original circuit topology of the electric vehicle. The connecting wires extend 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 modifications to the original circuit of the electric vehicle are minor, 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-division manner, thereby generating an AC pulsed current by making full use of the three inductance coils of the motor, which in turn allows for rapid heating of the two battery core groups.

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

[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, relevant data monitored by the measurement system and the battery management system are output and fed back in real time to a first controller, which dynamically adjusts the frequency or amplitude of the excitation current output by the self-heating system based on 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 begin to charge each other alternately. 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 charge each other alternately.

[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 onset 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] For example, a difference in the condition of the battery core units within the first battery core group and the condition of the battery core units within the second battery core group can result in the electromotive force of the first battery core group not being equal to that of the second battery core group. Such a difference could be a difference in the number of battery core units, a difference in the materials of the battery core units, or a difference in the models of the battery core units. For example, the fact that the electromotive force of the first battery core group is not equal to that of the second battery core group could be due to the rated electromotive force of the first battery core group not being 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 different degrees of losses experienced by the first and second battery core groups during the daily use of an electric vehicle, the electromotive force of the first battery core group is not equal to that 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-equal potential point, and the connection line is connected to a non-equal potential point of the battery pack. A non-equal potential point means that the absolute value of the voltage difference from that point to all the positive terminal ports of the battery pack is not equal to the absolute value of the voltage difference from that point to all the negative terminal ports of the battery pack. As shown in Figure 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 differ 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-equal potential point.

[0069] In conventional solutions, the power electronic switches in the inverter have errors during switching, the coils of the AC motor have losses during high-current oscillations, and the Hall elements used for measurement have errors 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, under long-term self-heating operating conditions, the charge loss of the first battery core group 1 does not match the charge loss of the second battery core group 2 (a charge loss error occurs), which creates a difference between the State of Charge (SOC) 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 within the power battery are connected in series, and the amount of charge available to the integrated vehicle is limited to the lowest SOC among the battery core units. Therefore, a mismatch between the charge loss of the first battery core group 1 and the charge loss of the second battery core group 2 under self-heating operating conditions adversely affects the amount of charge available to the electric vehicle and its endurance range.

[0071] In this embodiment of the present disclosure, to solve this problem, the first controller 6 is further configured to adjust 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 target difference is the difference between the first difference and the second difference, where 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 self-heating begins, 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 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 complete, 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 in the entire heating process falls within this range, thereby ensuring a balance between the first battery core group 1 and the second battery core group 2 and controlling, to some extent, the adverse effects of self-heating on the amount of available charge and the driving range of the electric vehicle.

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

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

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

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

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

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

[0078] In one example, different first differences correspond to different preset interval ranges; that 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 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 may be (for example, 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 becomes (for example, the preset interval range is (-0.05, +0.05)). In one example, the mapping relationship between the first difference and the preset interval range is stored in the electric vehicle beforehand. When self-heating is required, 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 a corresponding pre-set interval range is searched based on a pre-stored mapping relationship.

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

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

[0081] In one example, 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 the first controller adjusting the duty cycle and / or 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 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" indicates 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" indicates 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 for the three-phase bridge arms of the inverter, i.e., eight time-series statuses of the drive signals, i.e., 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, while U0(000) and U7(111) are zero vectors.

[0083] In one example, the adjustment of the drive signal in the self-heating process by the first controller includes the adjustment of the drive signal in the self-heating process in a dynamic and real-time manner by the first controller. That is, 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 corrected over time, thereby avoiding abrupt fluctuations in the excitation current.

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

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

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

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

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

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

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

[0091] The first experimental current and the second experimental current include the effects caused by electronic control errors and motor coil losses. The first integrated intensity 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 integrated intensity 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 integrated intensity value of the first experimental current to the first integrated intensity value of the second experimental current is 99 / 100, then the first preset ratio is 100 / 99.

[0093] For battery packs of different models, a first preset ratio corresponding to each battery pack must be determined by using heating test experiments for each battery pack. For multiple battery packs of the same model, if 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 must also be determined by using heating test experiments for each battery pack.

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

[0095] Step S202: The first theoretical current and the 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 the first preset ratio.

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

[0098] Step S206: The drive 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 corrected first theoretical current described above, and the second theoretical current calculated based on the drive signal is the corrected second theoretical current described above.

[0100] In such an adjustment method, charge loss errors caused by electrical control errors and motor coil losses still exist, but since the drive signal is set based on a corrected first theoretical current and a corrected second theoretical current, charge loss errors caused by electrical control errors and motor coil losses are compensated for, thereby ensuring that the integrated intensity value of the first measured current from the start to the end of self-heating is essentially the same as the integrated intensity value of the second measured current from the start to the end of self-heating. In the first adjustment method, 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 certain range, thereby ensuring a balance between the first battery core group 1 and the second battery core group 2, and allowing for some control over the adverse effects of self-heating on the amount of available charge and the endurance range of the electric vehicle.

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

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

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

[0104] In this embodiment of the present 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 the current passing through the resistor over a given period of time is equal to the heat generated by the DC current passing through the resistor over the same period of time. The value of the DC current is the effective value of the current.

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

[0106] 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. During the heating test experiment, the first measured current and the second measured current are obtained by measurement. The fourth RMS value of the first measured current is the RMS value of the first measured current from the start to the end of the heating test experiment, and the fourth RMS value of the second measured current is the RMS value of the second measured current from the start to the end of the heating test experiment.

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

[0108] The first and second measured currents include the effects caused by electronic control errors and motor coil losses. The fourth RMS 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 RMS 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 RMS value of the first measured current to the fourth RMS value of the second measured current is 99 / 100, then the first preset ratio is 100 / 99.

[0110] For battery packs of different models, a first preset ratio corresponding to each battery pack must be determined by using heating test experiments for each battery pack. For multiple battery packs of the same model, if 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 must also be determined by using heating test experiments for each battery pack.

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

[0112] Step P202: The first theoretical current and the 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 the first preset ratio.

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

[0117] In such an adjustment method, charge loss errors caused by electrical control errors and motor coil losses still exist, but since the drive signal is set based on a corrected first theoretical current and a corrected second theoretical current, charge loss errors caused by electrical control errors and motor coil losses are compensated for, thereby ensuring that the effective value of the first measured current from the start to the end of self-heating is essentially the same as the effective value of the second measured current from the start to the end of self-heating. In the first adjustment method, 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 certain range, thereby ensuring a balance between the first battery core group 1 and the second battery core group 2, and allowing for some control over the adverse effects of self-heating on the amount of available charge and the endurance range of the electric vehicle.

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

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

[0120] Step S302: The second integrated intensity value of the first measured current and the second integrated intensity 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 integrated intensity value of the first measured current is the integrated intensity value of the first measured current from the start of self-heating to the end of the current adjustment period, and the second integrated intensity value of the second measured current is the integrated intensity value of the second measured current from the start of self-heating to the end of the current adjustment period.

[0123] Step S304: The drive signal is set for the 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 the duty cycle and / or time-series status of the drive signal for the next adjustment period such that the second absolute value is smaller than the first absolute value. The first absolute value is the absolute difference between the second integrated intensity of the first measured current and the second integrated intensity of the second measured current. The second absolute value is the absolute difference between the fourth integrated intensity of the first measured current and the fourth integrated intensity of the second measured current. The fourth integrated intensity of the first measured current is the integrated intensity of the first measured current from the start of self-heating to the end of the next adjustment period, and the fourth integrated intensity of the second measured current is the integrated intensity of the second measured current from the start of self-heating to the end of the next adjustment period.

[0125] For example, if the second integrated intensity value of the first measured current is 90 and the second integrated intensity value of the second measured current is 100, then the first absolute value is 10. The drive signal is set for the next adjustment period such that the fourth integrated intensity value of the first measured current is 95 and the fourth integrated intensity 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 will decrease.

[0126] For example, if the ratio of the second integrated intensity value of the first measured current to the second integrated intensity 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 integrated intensity value of the first measured current and the second integrated intensity 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 is set such that the absolute value of the second is smaller than the absolute value of the first.

[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 corrected over time, thereby avoiding abrupt fluctuations in the excitation current and improving the stability of the self-heating process.

[0128] Example 2: The first controller adjusts the drive signal in a 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: The second integrated intensity value of the first measured current and the second integrated intensity 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 integrated intensity value of the first measured current is the integrated intensity value of the first measured current from the start of self-heating to the end of the current adjustment period, and the second integrated intensity value of the second measured current is the integrated intensity value of the second measured current from the start of self-heating to the end of the current adjustment period.

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

[0133] The third integrated intensity value of the first measured current is the integrated intensity value of the first measured current during the current adjustment period, and the third integrated intensity value of the second measured current is the integrated intensity value of the second measured current during 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 the duty cycle and / or time-series status of the drive signal for the next adjustment period such that the second absolute value is smaller than the first absolute value. The first absolute value is the absolute difference between the second integrated intensity of the first measured current and the second integrated intensity of the second measured current. The second absolute value is the absolute difference between the fourth integrated intensity of the first measured current and the fourth integrated intensity of the second measured current. The fourth integrated intensity of the first measured current is the integrated intensity of the first measured current from the start of self-heating to the end of the next adjustment period, and the fourth integrated intensity of the second measured current is the integrated intensity of the second measured current from the start of self-heating to the end of the next adjustment period.

[0136] For example, if the ratio of the second integrated intensity value of the first measured current to the second integrated intensity value of the second measured current falls within a preset interval range, and the ratio of the third integrated intensity value of the first measured current to the third integrated intensity 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 integrated intensity value of the first measured current to the second integrated intensity 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 so that the absolute value of the second is smaller than the absolute value of the first. If the ratio of the third integrated intensity value of the first measured current to the third integrated intensity 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 so that the absolute value of the second is smaller than the absolute value of the first.

[0137] 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 corrected over time, thereby avoiding abrupt fluctuations in the excitation current and improving the stability of the self-heating process. Furthermore, during the adjustment of the drive signal, the drive signal may be determined for the next adjustment period in a refined manner, taking into account all of 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.

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

[0139] Step P302: The first RMS value of the first measured current and the first RMS 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 RMS value of the first measured current and the first RMS value of the second measured current.

[0143] In one example, setting the drive signal for the next adjustment period includes setting the duty cycle and / or 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. The third absolute value is the absolute difference between the first RMS value of the first measured current and the first RMS value of the second measured current. The fourth absolute value is the absolute difference between the third RMS value of the first measured current and the third RMS value of the second measured current. The third RMS value of the first measured current is the RMS value of the first measured current from the start of self-heating to the end of the next adjustment period, and the third RMS value of the second measured current is the RMS value of the second measured current from the start of self-heating to the end of the next adjustment period.

[0144] For example, if the first RMS value of the first measured current is 90 and the first RMS value of the second measured current is 100, then the third absolute value is 10. The drive signal is adjusted for the next adjustment period so that the third RMS value of the first measured current is 95 and the third RMS 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 will decrease.

[0145] For 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 and / or time-series status of the drive signal in the next adjustment period are adjusted so that the fourth absolute value is less 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 corrected over time, thereby avoiding abrupt fluctuations in the excitation current and improving the stability of the self-heating process.

[0147] Example 4: The first controller adjusts the drive signal in a 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: The first RMS value of the first measured current and the first RMS 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: The second RMS value of the first measured current and the second RMS 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 during the current adjustment period, and the second effective value of the second measured current is the effective value of the second measured current during the current adjustment period.

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

[0154] In one example, setting the drive signal for the next adjustment period includes setting the duty cycle and / or 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. The third absolute value is the absolute difference between the first RMS value of the first measured current and the first RMS value of the second measured current. The fourth absolute value is the absolute difference between the third RMS value of the first measured current and the third RMS value of the second measured current. The third RMS value of the first measured current is the RMS value of the first measured current from the start of self-heating to the end of the next adjustment period, and the third RMS value of the second measured current is the RMS value of the second measured current from the start of self-heating to the end of the next adjustment period.

[0155] For example, if the ratio of the first RMS value of the first measured current to the first RMS value of the second measured current falls within a preset interval range, and the ratio of the second RMS value of the first measured current to the second RMS 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 RMS value of the first measured current to the first RMS value of the second measured current falls outside the preset interval range, the duty cycle and / or time-series status of the drive signal are adjusted for the next adjustment period so that the fourth absolute value is smaller than the third absolute value. If the ratio of the second RMS value of the first measured current to the second RMS value of the second measured current falls outside the preset interval range, the duty cycle and / or time-series status of the drive signal are adjusted for the next adjustment period so that the fourth absolute value is smaller than the third absolute value.

[0156] 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 corrected over time, thereby avoiding abrupt fluctuations in the excitation current and improving the stability of the self-heating process. Furthermore, during the adjustment of the drive signal, the drive signal may be determined for the next adjustment period in a refined manner, taking into account all of the first RMS value of the first measured current, the first RMS value of the second measured current, the second RMS value of the first measured current, and the second RMS value of the second measured current.

[0157] In the second tuning method, the control method of the first controller is feedback closed-loop control. In one example, the tuning method of the first controller is PI (Proportion Integration) control. In another example, the tuning method of the first controller is PID (Proportion Integration Differentiation) control, that is, a combination of the three functions of proportionality, integration, and differentiation. Proportional control is a simple proportional control method. When only proportional control is used, steady-state errors exist in the system, and constant disturbances applied 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 abrupt fluctuations.

[0158] In the second adjustment method, charge loss errors caused by electrical control errors and motor coil losses still exist, but these errors are corrected and compensated over time based on the adjustment period, thereby ensuring that the integrated or effective value of the first measured current from the start to the end of self-heating is essentially the same as the integrated or effective value of the second measured current from the start to the end of self-heating. In the second adjustment method, 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 certain range, thereby ensuring a balance between the first battery core group 1 and the second battery core group 2, and allowing for some control over the adverse effects of self-heating on the amount of charge available to the electric vehicle and its mileage.

[0159] In the self-heating process of a power battery, controlling the excitation current is crucial. The inventors have found through research that the temperature of the power battery rises relatively rapidly under relatively high excitation currents. However, as the excitation current increases, so do the adverse effects on battery capacity during the heating process. Therefore, both factors must be considered in the self-heating process.

[0160] In this embodiment of the present disclosure, the battery core units within the battery core group are lithium iron phosphate battery core units, ternary lithium battery core units, or batteries of another chemical system. After the capacity retention rates of the two batteries during self-heating have been obtained in advance by using a large number of tests, the following control policy is formulated.

[0161] In one example, the first controller is further configured to adjust the drive signal during the self-heating process such that the average RMS value of the current flowing through the first battery core group 1 is between 0.5C and 5C over the entire self-heating period, and the average RMS value of the current flowing through the second battery core group 2 is between 0.5C and 5C over the entire self-heating period. In one example, the requirement may be met by adjusting the duty cycle and / or time-series status of the drive 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 or measured currents.

[0162] In one example, the first controller is further configured to adjust the drive signal during the self-heating process such that the average value of the RMS current flowing through the neutral point of the AC motor is between 1C and 10C throughout the entire self-heating period. In one example, the requirement may be met by adjusting the duty cycle and / or time-series status of the drive 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 or measured currents.

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

[0164] By using the aforementioned control policy, the battery core can be prevented from being overcharged or over-discharged at low temperatures, thereby ensuring the safety of the battery core. In this embodiment of the disclosure, by using the aforementioned self-heating policy, heating efficiency and safety in the self-heating process are taken into consideration, the power battery can be heated efficiently, excessive damage to battery life is avoided, and battery safety is ensured. In this embodiment of the disclosure, the aforementioned policies can be superimposed to obtain better effects.

[0165] In one example, the first controller is further configured to perform synchronous control over the on / off states of the three upper bridge arms and the on / off states of the three lower bridge arms during the self-heating process. That is, all three upper bridge arms are turned on / off. Correspondingly, all three lower bridge arms are 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 Disclosure may include a processor, memory, and a program or instruction stored in the memory and executable on the processor. When executed by the processor, the program or instruction implements any heating control policy according to the embodiments described above.

[0167] One embodiment of the present disclosure provides an electric vehicle comprising a power battery and a heating system for heating the power battery, according to any one of the embodiments described above.

[0168] All embodiments of this disclosure are described progressively, with reference to those embodiments for any similar or identical parts in the embodiments, and the description of each embodiment focuses on the differences from the other embodiments. For relevant details of the electric vehicle embodiments, see the partial description of the heating system embodiments.

[0169] 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 recorded in the claims may be performed in a different order than those in the embodiments, and the expected results may still be achieved. Furthermore, to achieve the expected results, the processes shown in the appended drawings do not necessarily have to be performed in a specific order or sequentially. In some implementations, multitasking and parallel processing may be feasible or beneficial.

[0170] Embodiments of the present disclosure may be systems, methods, and / or computer program products. A computer program product may include a computer-readable storage medium that carries computer instructions used to enable a processor to carry out embodiments of the present disclosure.

[0171] A computer-readable storage medium can be a tangible device capable of maintaining and storing computer instructions used by a computer instruction execution device. For example, a computer-readable storage medium can 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 (a non-exhaustive list) of computer-readable media include portable computer disks, hard disks, random-access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random-access memory (SRAM), portable compressed disk read-only memory (CD-ROM), digital multipurpose disks (DVDs), memory sticks, floppy disks, mechanical encoding devices, such as punch cards or grooved projection structures on which computer instructions are stored, and any suitable combination of those described above. The computer-readable storage media used herein are not interpreted as instantaneous signals, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagated by using waveguides or other transmission media (for example, by using optical pulses in fiber optic cables), or electrical signals transmitted by using wires.

[0172] The computer instructions described herein may be downloaded from a computer-readable storage medium to each computing / processing device, or to an external computer or external 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, optical fiber transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter or network interface within each computing / processing device receives computer instructions from the network and transfers those instructions so that they are stored in a computer-readable storage medium within each computing / processing device.

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

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

Claims

1. A heating system for heating a power battery, wherein the power battery comprises a first battery core group (1) and a second battery core group (2) connected in series, and the electromotive force of the first battery core group (1) is not equal to the electromotive force of the second battery core group (2). The heating system comprises an inverter (3), an AC motor (4), and a first controller (5). The inverter (3) comprises three bridge arms, the positive terminal of the power battery is connected to the upper bridge arm of the inverter (3), the negative terminal 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 each connected to the front end of the three-phase coil of the AC motor, and the 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 connecting wire (S1), and the first connection point is the 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 connecting 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 so that the ratio of the first target difference to the first difference falls within a preset interval range. A heating system in which 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 self-heating begins, 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 self-heating ends.

2. The heating system according to 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 the ratio of the first target difference to the first difference to fall within a preset interval range. To enable the ratio of the first target difference to the first difference to fall within the preset interval range, the first controller (6) adjusts the duty cycle and / or time-series status of the drive signal in the self-heating process. The heating system according to claim 1, including the heating system described in claim 1.

4. The first controller (6) adjusts the drive signal in a 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 (6) adjusts the drive signal so that the ratio of the second target difference to the fifth cumulative intensity value falls within the preset interval range. The heating system according to claim 1, wherein the second target difference is the difference between the fifth integrated intensity value and the sixth integrated intensity value, the fifth integrated intensity value is the integrated intensity value of the current flowing through the first battery core group (1) in the self-heating process, the sixth integrated intensity value is the integrated intensity value of the current flowing through the second battery core group (2) in the self-heating process, and the integrated intensity value of the current is the integrated value of the current intensity over time.

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

6. The first predetermined ratio is determined in advance by using a heating test experiment. The determination of the first predetermined ratio is As a second ratio, we obtain the ratio of the first integrated intensity value of the first experimental current to the first integrated intensity value of the second experimental current, Determining the first predetermined ratio, wherein the first predetermined ratio is the reciprocal of the second ratio. The first experimental current is the measured current flowing through the first battery core group (1) in the heating test experiment, and the second experimental current is the measured current flowing through the second battery core group (2) in the heating test experiment. The heating system according to claim 5, wherein the first integrated intensity value of the first experimental current is the integrated intensity 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 integrated intensity value of the second experimental current is the integrated intensity 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 the ratio of the first target difference to the first difference to fall within a preset interval range. To obtain the second integrated intensity value of the first measured current and the second integrated intensity value of the second measured current, Based on the second integrated intensity value of the first measured current and the second integrated intensity value of the second measured current, a drive signal for the next adjustment period is set. 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. The heating system according to claim 1, wherein 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.

8. The first controller (6) adjusts the drive signal in a self-heating process to enable the ratio of the first target difference to the first difference to fall within a preset interval range. To obtain the second integrated intensity value of the first measured current and the second integrated intensity value of the second measured current, To obtain the third integrated intensity value of the first measured current and the third integrated intensity value of the second measured current, Based on the second integrated intensity value of the first measured current, the second integrated intensity value of the second measured current, the third integrated intensity value of the first measured current, and the third integrated intensity value of the second measured current, a drive signal for the next adjustment period is set. 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). The second integrated intensity value of the first measured current is the integrated intensity value of the first measured current from the start of self-heating to the end of the current adjustment period, and the second integrated intensity value of the second measured current is the integrated intensity value of the second measured current from the start of self-heating to the end of the current adjustment period. The heating system according to claim 1, wherein the third intensity integrated value of the first measured current is the intensity integrated value of the first measured current during 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 during the current adjustment period.

9. Setting the drive signal for the next adjustment period is, Setting the duty cycle and / or time-series status of the drive signal for the next adjustment period such that the second absolute value is smaller than the first absolute value. The absolute value of the first is the absolute value of the difference between the second integrated intensity value of the first measured current and the second integrated intensity value of the second measured current. The absolute value of the second is the absolute value of the difference between the fourth integrated intensity value of the first measured current and the fourth integrated intensity value of the second measured current. The heating system according to claim 7, wherein the fourth intensity integrated value of the first measured current is the intensity integrated 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 integrated value of the second measured current is the intensity integrated 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 the ratio of the first target difference to the first difference to fall within a preset interval range. Obtain the first effective value of the first measured current and the first effective value of the second measured current, Based on the first effective value of the first measured current and the first effective value of the second measured current, a drive signal for the next adjustment period is set. 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). The heating system according to claim 1, wherein 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.

11. The first controller (6) adjusts the drive signal in a self-heating process to enable the ratio of the first target difference to the first difference to fall within a preset interval range. Obtain the first effective value of the first measured current and the first effective value of the second measured current, Obtaining the second effective value of the first measured current and the second effective value of the second measured current, 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, a drive signal for the next adjustment period is set. 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). 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. The heating system according to claim 1, wherein the second effective value of the first measured current is the effective value of the first measured current during the current adjustment period, and the second effective value of the second measured current is the effective value of the second measured current during the current adjustment period.

12. Setting the drive signal for the next adjustment period is, Setting the duty cycle and / or time-series status of the drive signal for the next adjustment period such that the fourth absolute value is smaller than the third absolute value. 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. 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. The heating system according to claim 10, wherein the third effective value of the first measured current is the 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 the effective value of the second measured current from the start of the self-heating to the end of the next adjustment period.

13. The heating system according to claim 7, wherein the adjustment method of the first controller (6) is a PID adjustment method.

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

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

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

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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