Battery self-heating system and vehicle

Abstract

The present disclosure relates to a battery self-heating system and a vehicle to improve the self-heating efficiency of a power battery pack during the battery self-heating process. The system includes: a power battery pack, a first heating module, a second heating module, and a controller, wherein the power battery pack includes a first battery pack and a second battery pack connected in series; the first connection end and the second connection end of the first heating module are respectively connected to the positive and negative electrodes of the power battery pack; the first connection end and the second connection end of the second heating module are respectively connected to the positive and negative electrodes of the second battery pack, and the third connection end of the second heating module is connected to the third connection end of the first heating module; the controller is connected to the first heating module and the second heating module, and the controller is configured to: control the alternating charge and discharge between the first battery pack and the second battery pack through the first heating module and the second heating module.

Description

Technical Field

[0001] The present disclosure relates to electric vehicle technology, and in particular, to a battery self-heating system and a vehicle. Background Art

[0002] In response to energy conservation and emission reduction, more and more electric vehicles are entering the public eye. When electric vehicles are in a low temperature environment, the low temperature reduces the activity of the positive and negative electrode materials of the battery and the electrolyte in the battery, and its charging and discharging performance will be greatly reduced. In order to ensure the power of electric vehicles in low temperature environments, the battery of the electric vehicle can be heated to increase the temperature of the battery body to ensure the battery charging and discharging performance. In the related technology, battery heating is achieved by alternating charging and discharging between the battery pack and the energy storage capacitor. However, due to the limitations of the topology itself, the current flowing through the motor winding at the same time must be in and out, that is, the heating current can only be the current limiting value of one phase winding, resulting in limited heating power. In addition, the energy storage capacitor has a large internal resistance at low frequencies, which also leads to low battery heating efficiency. Summary of the invention

[0003] The purpose of the present disclosure is to provide a battery self-heating system and a vehicle, aiming to solve the above-mentioned technical problems.

[0004] In order to achieve the above-mentioned object, a first aspect of the present disclosure provides a battery self-heating system, which is applied to a vehicle, and the system comprises:

[0005] A power battery pack, the power battery pack comprising a first battery pack and a second battery pack connected in series;

[0006] A first heating module, wherein a first connection end and a second connection end of the first heating module are respectively connected to the positive and negative electrodes of the power battery pack;

[0007] a second heating module, wherein a first connection end and a second connection end of the second heating module are respectively connected to the positive and negative electrodes of the second battery pack, and a third connection end of the second heating module is connected to the third connection end of the first heating module;

[0008] A controller is connected to the first heating module and the second heating module, and the controller is configured to control the alternating charging and discharging between the first battery group and the second battery group through the first heating module and the second heating module.

[0009] Optionally, the first heating module includes a first bridge arm and a first winding, the first end of the first bridge arm is connected to the positive electrode of the first battery group, the second end of the first bridge arm is connected to the negative electrode of the second battery group, and the first end of the first winding is connected to the midpoint of the first bridge arm;

[0010] The second heating module includes a second bridge arm and a second winding, the first end of the second bridge arm is connected to the negative electrode of the first battery group, the second end of the second bridge arm is connected to the negative electrode of the second battery group, the first end of the second winding is connected to the midpoint of the second bridge arm, and the second end of the second winding is connected to the second end of the first winding.

[0011] Optionally, a bridge arm of a first motor controller is reused as the first bridge arm, and a coil of a first motor connected to the first motor controller is reused as the first winding;

[0012] The bridge arm of the second motor controller is reused as the second bridge arm, and the coil of the second motor connected to the second motor controller is reused as the second winding.

[0013] Optionally, the controller is configured to:

[0014] In a first half cycle, the first battery pack is controlled to discharge through the first heating module and the second heating module, and the second battery pack is charged through the first heating module and the second heating module;

[0015] In the second half cycle, the second battery pack is controlled to discharge through the first heating module and the second heating module, and the first battery pack is charged through the first heating module and the second heating module.

[0016] Optionally, the first bridge arm includes a first upper bridge arm and a first lower bridge arm, and the second bridge arm includes a second upper bridge arm and a second lower bridge arm;

[0017] In a first time period of the first half cycle, the first upper bridge arm and the second upper bridge arm are controlled to be turned on, and the first lower bridge arm and the second lower bridge arm are turned off, and the first battery pack is controlled to discharge through the first heating module and the second heating module;

[0018] In a second time period of the first half cycle, the first lower bridge arm and the second upper bridge arm are controlled to be turned on, and the first upper bridge arm and the second lower bridge arm are turned off, and the second battery pack is charged through the first heating module and the second heating module.

[0019] Optionally, in a first time period of the second half cycle, the first lower bridge arm and the second upper bridge arm are controlled to be turned on, and the first upper bridge arm and the second lower bridge arm are turned off, and the second battery pack is controlled to discharge through the first heating module and the second heating module;

[0020] In a second time period of the second half cycle, the first upper bridge arm and the second upper bridge arm are controlled to be turned on, and the first lower bridge arm and the second lower bridge arm are turned off, and the first battery pack is charged through the first heating module and the second heating module.

[0021] Optionally, the controller is configured to:

[0022] In the first half cycle, a first voltage variation amount for controlling the discharge of the first battery pack is the same as a second voltage variation amount for charging the second battery pack;

[0023] In the second half cycle, the third voltage variation amount for controlling the discharge of the second battery pack is the same as the fourth voltage variation amount for charging the first battery pack.

[0024] Optionally, the controller is further configured to:

[0025] In the first half cycle, controlling the ratio between the current value flowing through the first battery group and the current value flowing through the second battery group to be equal to the ratio between the resistance value of the second battery group and the resistance value of the first battery group;

[0026] In the second half cycle, a ratio between a current value flowing through the first battery group and a current value flowing through the second battery group is controlled to be equal to a ratio between a resistance value of the second battery group and a resistance value of the first battery group.

[0027] Optionally, the system further comprises:

[0028] a third motor controller, wherein a first end of the third motor controller is connected to the positive electrode of the power battery pack, and a second end of the third motor controller is connected to the negative electrode of the power battery pack;

[0029] a third motor, the third motor being connected to the third motor controller;

[0030] The controller is connected to the third motor controller, and the controller is further configured to: drive the third motor through the third motor controller, and control the alternating charging and discharging between the first battery group and the second battery group through the first heating module and the second heating module.

[0031] Optionally, the system further comprises:

[0032] A DC charging port, wherein the positive electrode of the DC charging port is connected to the positive electrode of the power battery pack, and the negative electrode of the DC charging port is connected to the negative electrode of the power battery pack;

[0033] The controller is further configured to: receive electric energy through the DC charging port to charge the power battery pack, and control alternating charging and discharging between the first battery pack and the second battery pack through the first heating module and the second heating module.

[0034] Optionally, the system further comprises:

[0035] A first charging switch and a second charging switch, wherein the first charging switch is a two-position switch;

[0036] The static contact of the first charging switch is connected to the positive electrode of the DC charging port, the first moving contact of the first charging switch is connected to the positive electrode of the first battery pack, and the second moving contact of the first charging switch is connected to the second end of the first winding and the second end of the second winding respectively;

[0037] The second charging switch is arranged on a connection line between the negative electrode of the DC charging port and the negative electrode of the second battery pack;

[0038] The controller is further configured to: control the static contact of the first charging switch to be connected to the first moving contact of the first charging switch, and control the second charging switch to be closed, so as to receive electric energy through the DC charging port to charge the power battery pack;

[0039] The controller is also configured to: control the static contact of the first charging switch to be connected to the second moving contact of the first charging switch, control the second charging switch to be closed, and control the first upper bridge arm and the second upper bridge arm to be turned on, receive electrical energy through the DC charging port, so as to boost and charge the power battery pack.

[0040] A second aspect of the present disclosure further provides a vehicle, comprising the battery self-heating system as described in any one of the first aspects above.

[0041] The battery self-heating system provided by the present disclosure is applied to a vehicle, and the system includes a power battery pack, a first heating module, a second heating module, and a controller, and the first heating module and the second heating module are used to control the alternating charging and discharging between the first battery pack and the second battery pack. Since the first battery pack and the second battery pack are alternately charged and discharged, the voltage fluctuations cancel each other out, so that the terminal voltage fluctuation of the power battery pack is small, and multiple heating modules participate in battery heating, and the heating modules are used to store electrical energy, which can increase the stored energy value and the current value flowing through the battery pack, thereby improving the self-heating efficiency of the power battery pack.

[0042] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0044] Figure 1 It is a schematic diagram of a battery self-heating circuit of the related art;

[0045] Figure 2 is a schematic diagram of another battery self-heating circuit of the related art;

[0046] Figure 3 is a schematic diagram of a battery self-heating system provided by an embodiment of the present disclosure;

[0047] Figure 4 is a schematic diagram of another battery self-heating system provided by an embodiment of the present disclosure;

[0048] Figure 5 is a schematic diagram of another battery self-heating system provided by an embodiment of the present disclosure;

[0049] Figure 6 is a circuit diagram of a battery self-heating system provided by an embodiment of the present disclosure;

[0050] Figure 7 is a schematic diagram of the current direction of a battery self-heating system when it is working, provided by an embodiment of the present disclosure;

[0051] Figure 8 is a schematic diagram of the current direction of another battery self-heating system provided by an embodiment of the present disclosure when it is working;

[0052] Fig. 9 is a schematic diagram of the current direction of another battery self-heating system provided by an embodiment of the present disclosure when it is working;

[0053] Fig.10 is a schematic diagram of the current direction of another battery self-heating system provided by an embodiment of the present disclosure when it is working;

[0054] Fig.11 is a schematic diagram of another battery self-heating system provided by an embodiment of the present disclosure;

[0055] Fig.12 is a schematic diagram of the charging current direction of another battery self-heating system provided by an embodiment of the present disclosure when charging;

[0056] Fig.13 It is a schematic diagram of the current direction during boost charging of another battery self-heating system provided by an embodiment of the present disclosure.

[0057] Description of Reference Numerals

[0058] 11-first battery; 12-bus capacitor; 13-energy storage capacitor; 14-first inverter; 15-first motor winding; 21-second battery; 22-second capacitor; 23-second inverter; 24-second motor winding; E1-first battery pack; E2-second battery pack; K1-first conversion switch; K2-second conversion switch; K3-first charging switch; K4-second charging switch; 1-first motor; 2-first motor controller; 3-second motor; 4-second motor controller; 5-third motor; 6-third motor controller; 7-DC charging port; a-first static contact; b-first moving contact; c-second moving contact. DETAILED DESCRIPTION

[0059] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0060] It should be understood that the various steps described in the method implementation of the present disclosure may be performed in different orders and / or in parallel. In addition, the method implementation may include additional steps and / or omit the steps shown. The scope of the present disclosure is not limited in this respect. The term "including" and its variations used herein are open inclusions, i.e., "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one other embodiment"; the term "some embodiments" means "at least some embodiments". The relevant definitions of other terms will be given in the description below.

[0061] It should be noted that the concepts of "first", "second", etc. mentioned in the present disclosure are only used to distinguish different devices, modules or units, and are not used to limit the order or interdependence of the functions performed by these devices, modules or units. It should be noted that the modifications of "one" and "multiple" mentioned in the present disclosure are illustrative rather than restrictive, and those skilled in the art should understand that unless otherwise clearly indicated in the context, they should be understood as "one or more".

[0062] In response to energy conservation and emission reduction, more and more electric vehicles are being chosen by more users. In order to improve the driving performance of electric vehicles, multi-motor electric vehicles known for their strong power are gradually entering the public's field of vision. Strong power requires good battery charging and discharging performance, but when electric vehicles are in a low temperature environment, especially below -10°C, the low temperature reduces the activity of the positive and negative electrode materials and the electrolyte in the battery, and its charging and discharging performance will be greatly reduced. In order to ensure the power of electric vehicles in low temperature environments, the battery of the electric vehicle can be heated to increase the temperature of the battery body to ensure the battery charging and discharging performance.

[0063] At present, batteries can be heated by external heating and internal heating. Among them, external heating heats the battery by adding additional heating equipment. This heating method adds additional heating equipment, which leads to high costs. In addition, the external heat dissipation is fast and there is a certain distance between the external temperature and the internal battery, resulting in low heating efficiency. The principle of the other internal heating method is mainly to use the battery cycle charge and discharge, relying on the battery's own internal resistance to generate heat. For example, Figure 1 As shown, the battery self-heating circuit includes a first battery 11, a bus capacitor 12, an energy storage capacitor 13, a first inverter 14 and a first motor winding 15, wherein the first battery 11, the bus capacitor 12 and the first inverter 14 are connected in parallel, and the first battery 11 is oscillated and heated by the first inverter 14, the first motor winding 15 and the energy storage capacitor 13, and during the oscillation heating process, the first battery 11 is in an alternating charge and discharge state, so the battery voltage fluctuates greatly. Or, as Figure 2 As shown, the battery self-heating circuit includes a second battery 21, a second capacitor 22, a second inverter 23 and a second motor winding 24, wherein the second battery 21, the second capacitor 22 and the second inverter 23 are connected in parallel, and the second battery 21 is oscillated and heated by the second inverter 23 and the second motor winding 24, and during the oscillation heating process, the second battery 21 is in an alternating charge and discharge state, so the battery voltage fluctuates greatly. This fluctuation may damage the battery and reduce the battery life.

[0064] In addition, the heating principle of battery self-heating is that when a large current flows through the battery, the internal resistance of the battery generates heat, thereby heating the battery. In other words, in order to generate a larger amount of heating, a larger self-heating current is required when the internal resistance of the battery and the heating time remain unchanged. The battery voltage fluctuation ∆U=I*Rcell, when the total internal resistance Rcell of the battery remains unchanged, the larger the battery current I, the larger the fluctuation ∆U of the battery voltage. If the battery pack is connected to the charging pile for charging during the battery self-heating process, the fluctuation may cause charging failure. Alternatively, the battery pack is connected to the motor controller and the motor drives the vehicle, and the fluctuation may cause delays or abnormalities in the control of the motor controller, and at the same time, the torque control of the motor may also be abnormal. In addition, due to the limitations of the topology itself, the current flowing through the motor winding at the same time must be in and out, that is, the heating current can only be the current limit value of one phase winding, resulting in limited heating power. In addition, the circuit of the battery self-heating system in the related art uses capacitors for alternating charging and discharging. The capacitor has a large internal resistance at low frequency, which also leads to low battery heating efficiency.

[0065] The technical solution of the present disclosure is described in detail below with reference to embodiments.

[0066] The present disclosure provides a battery self-heating system for a vehicle. Figure 3 The battery self-heating system includes: a power battery pack 31, a first heating module 32, a second heating module 33 and a controller 34.

[0067] The power battery pack 31 includes a first battery pack E1 and a second battery pack E2 connected in series, a first connection end and a second connection end of the first heating module 32 are respectively connected to the positive and negative electrodes of the power battery pack 31, a first connection end and a second connection end of the second heating module 33 are respectively connected to the positive and negative electrodes of the second battery pack E2, and a third connection end of the second heating module 33 is connected to a third connection end of the first heating module 32. The controller 34 is configured to control the alternating charge and discharge between the first battery pack E1 and the second battery pack E2 through the first heating module 32 and the second heating module 33.

[0068] When the above-mentioned battery self-heating system is used for battery self-heating, the first battery group and the second battery group are charged and discharged alternately, and the voltage fluctuations cancel each other out, so that the terminal voltage fluctuation of the power battery pack is smaller, and multiple heating modules are involved in battery heating. By storing electrical energy using the heating modules, the stored energy value and the current value flowing through the battery pack can be increased, thereby improving the self-heating efficiency of the power battery pack.

[0069] In order to enable those skilled in the art to better understand the battery self-heating system provided by the present disclosure, the above steps are described in detail with examples below.

[0070] In possible ways, refer to Figure 4 The first heating module 32 includes a first bridge arm 42 and a first winding 41. The first end of the first bridge arm 42 is connected to the positive electrode of the first battery group E1, the second end of the first bridge arm 42 is connected to the negative electrode of the second battery group E2, and the first end of the first winding 41 is connected to the midpoint of the first bridge arm 42. The second heating module 33 includes a second bridge arm 44 and a second winding 43. The first end of the second bridge arm 44 is connected to the negative electrode of the first battery group E1, the second end of the second bridge arm 44 is connected to the negative electrode of the second battery group E2, the first end of the second winding 43 is connected to the midpoint of the second bridge arm 44, and the second end of the second winding 43 is connected to the second end of the first winding 41.

[0071] In a possible manner, the bridge arm of the first motor controller is reused as the first bridge arm, the coil of the first motor connected to the first motor controller is reused as the first winding, the bridge arm of the second motor controller is reused as the second bridge arm, and the coil of the second motor connected to the second motor controller is reused as the second winding.

[0072] For example, for a vehicle with multiple motors, multiple motor controllers and multiple motors on the vehicle can be used to self-heat the power battery pack. Figure 5Taking a vehicle with multiple three-phase motors as an example, the power battery pack is divided into two battery groups, the first motor controller and the first motor serve as the first heating module, and the second motor controller and the second motor serve as the second heating module.

[0073] Among them, refer to Figure 6 The first winding is a coil in the first motor 1, and the first bridge arm is a bridge arm in the first motor controller 2 corresponding to the first motor 1. The second winding is a coil in the second motor 3, and the second bridge arm is a bridge arm in the second motor controller 4 corresponding to the second motor 3.

[0074] In a possible manner, the controller is configured to: in a first half cycle, control the first battery pack to discharge through the first heating module and the second heating module, and charge the second battery pack through the first heating module and the second heating module. In a second half cycle, control the second battery pack to discharge through the first heating module and the second heating module, and charge the first battery pack through the first heating module and the second heating module.

[0075] In possible ways, refer to Figure 4 The first bridge arm 42 includes a first upper bridge arm 421 and a first lower bridge arm 422 , and the second bridge arm 44 includes a second upper bridge arm 441 and a second lower bridge arm 442 .

[0076] Wherein, the controller is configured to: in the first time period of the first half cycle, control the first upper bridge arm and the second upper bridge arm to be turned on, and the first lower bridge arm and the second lower bridge arm to be turned off, and control the first battery pack to discharge through the first heating module and the second heating module. In the second time period of the first half cycle, control the first lower bridge arm and the second upper bridge arm to be turned on, and the first upper bridge arm and the second lower bridge arm to be turned off, and charge the second battery pack through the first heating module and the second heating module. In the first time period of the second half cycle, control the first lower bridge arm and the second upper bridge arm to be turned on, and the first upper bridge arm and the second lower bridge arm to be turned off, and control the second battery pack to discharge through the first heating module and the second heating module. In the second time period of the second half cycle, control the first upper bridge arm and the second upper bridge arm to be turned on, and the first lower bridge arm and the second lower bridge arm to be turned off, and charge the first battery pack through the first heating module and the second heating module.

[0077] For example, in the first time period of the first half cycle, referring to Figure 7, the upper bridge arm of the first motor controller 2 is turned on, the lower bridge arm is turned off, the upper bridge arm of the second motor controller 4 is turned on or off (according to the unidirectional conduction characteristics of the diode, the current passes through the parasitic diode of the upper bridge arm when it is turned off, the same below), the lower bridge arm is turned off, and the first battery pack E1 and the upper bridge arm of the first motor controller 2, the coil in the first motor 1, the coil in the second motor 3, and the upper bridge arm of the second motor controller 4 form a closed loop. At this time, the first battery pack E1 charges the coil in the first motor 1 and the coil in the second motor 3, the voltage of the first battery pack E1 drops, the internal resistance of the battery heats up, and the battery temperature rises.

[0078] For example, in the second time period of the first half cycle, referring to Figure 8 , the upper bridge arm of the first motor controller 2 is turned off, the lower bridge arm is turned on or off, the upper bridge arm of the second motor controller 4 is turned on or off, the lower bridge arm is turned off, and the second battery pack E2, the lower bridge arm of the first motor controller 2, the coil in the first motor 1, the coil in the second motor 3, and the upper bridge arm of the second motor controller 4 form a closed loop. At this time, the coil in the first motor 1 and the coil in the second motor 3 release the energy stored in the first time period of the first half cycle to charge the second battery pack E2, the voltage of the second battery pack E2 rises, the internal resistance of the battery heats up, and the battery temperature rises.

[0079] For example, in the first time period of the second half cycle, referring to Fig. 9 , the upper bridge arm of the second motor controller 4 is turned on, the lower bridge arm is turned off, the lower bridge arm of the first motor controller 2 is turned on, the upper bridge arm is turned off, and the second battery pack E2, the upper bridge arm of the second motor controller 4, the coil in the second motor 3, the coil in the first motor 1, and the lower bridge arm of the first motor controller 2 form a closed loop. At this time, the second battery pack E2 charges the coil in the second motor 3 and the coil in the first motor 1, the voltage of the second battery pack E2 drops, the internal resistance of the battery heats up, and the battery temperature rises.

[0080] For example, in the second time period of the second half cycle, referring to Fig.10 , the upper bridge arm of the second motor controller 4 is turned on, the lower bridge arm is turned off, the lower bridge arm of the first motor controller 2 is turned off, the upper bridge arm is turned on or off, and the first battery pack E1 and the upper bridge arm of the second motor controller 4, the coil in the second motor 3, the coil in the first motor 1, and the upper bridge arm of the first motor controller 2 form a closed loop. At this time, the coil in the first motor 1 and the coil in the second motor 3 release the energy stored in the first time period of the second half cycle to charge the first battery pack E1, the voltage of the first battery pack E1 rises, the internal resistance of the battery heats up, and the battery temperature rises.

[0081] It is worth noting that in the first time period of the first half cycle, the voltage of the first battery pack E1 continues to decrease, and the decrease amplitude ∆U1=I1*Rcell1, and in the second time period of the first half cycle, the voltage of the second battery pack E2 continues to increase, and the increase amplitude ∆U2=I2*Rcell2. In the first time period of the second half cycle, the voltage of the first battery pack E1 continues to increase, and the increase amplitude ∆U1=I1*Rcell1, and in the second time period of the second half cycle, the voltage of the second battery pack E2 continues to decrease, and the decrease amplitude ∆U2=I2*Rcell2. Therefore, by controlling the current I1 and the resistance Rcell1 of the first battery pack and the current I2 and the resistance Rcell2 of the second battery pack, the total fluctuation of the voltage of the power battery pack in a unit time can be within a preset voltage fluctuation range, such as -0.5V to 0.5V. The specific preset voltage fluctuation range can be determined according to demand, and the present disclosure does not limit this. Of course, under the premise of Rcell1=Rcell2, as long as I1=I2 is guaranteed, the total fluctuation of the voltage of the power battery pack in a unit time can be 0.

[0082] It should be noted that the energy is cyclically charged and discharged between the power battery pack and the motor windings through the reciprocating cycle of the first half cycle and the second half cycle, thereby realizing battery self-heating. In addition, by controlling the duration of each half cycle and time period, the total fluctuation of the power battery pack voltage per unit time can be within the preset voltage fluctuation range, thereby ensuring that the terminal voltage fluctuation of the power battery pack is small, thereby avoiding vehicle charging failure or abnormalities in the motor controller and the motor when driving the vehicle.

[0083] In a possible manner, the controller is configured such that, in a first half cycle, a first voltage change controlling the discharge of the first battery pack is the same as a second voltage change controlling the charging of the second battery pack, and in a second half cycle, a third voltage change controlling the discharge of the second battery pack is the same as a fourth voltage change controlling the charging of the first battery pack.

[0084] Further, in a possible manner, the controller is also configured to: in the first half cycle, control the ratio of the current value flowing through the first battery group to the current value flowing through the second battery group to be equal to the ratio of the resistance value of the second battery group to the resistance value of the first battery group; in the second half cycle, control the ratio of the current value flowing through the first battery group to the current value flowing through the second battery group to be equal to the ratio of the resistance value of the second battery group to the resistance value of the first battery group.

[0085] For example, through the charging and discharging process between the first battery pack and the second battery pack during the above-mentioned battery self-heating process, it can be known that the voltage fluctuation is related to the current and resistance of the battery. Since the resistance value of the battery pack has been determined when the battery pack is divided, the total fluctuation of the voltage of the power battery pack in a unit time can be controlled within a preset voltage fluctuation range by adjusting the current of the battery pack. For example, if the power battery pack is divided into two battery packs with an equal number of cells, that is, Rcell1=Rcell2, I1=I2 can be controlled. For another example, if the power battery pack is divided into two battery packs with unequal numbers of cells, if the total fluctuation of the voltage of the power battery pack in a unit time needs to be controlled to 0, I1 / I2=Rcell2 / Rcell1 can be controlled. That is, when the ratio between the current value of the first battery pack and the current value flowing through the second battery pack is equal to the ratio between the resistance value of the second battery pack and the resistance value of the first battery pack, the total fluctuation of the voltage of the power battery pack in a unit time is equal to 0. Accordingly, if it is only necessary to control the total fluctuation of the voltage of the power battery pack within a unit time within a preset voltage fluctuation range, the current of the battery packs divided into the power battery pack can be controlled according to the control relationship that the larger the resistance of the battery pack, the smaller the current. The specific current can be determined according to demand and experiments, and the present disclosure does not impose any restrictions on this.

[0086] It is worth noting that, compared with the related art in which the heating current can only be the current limiting value of one phase winding, the battery self-heating system provided by the embodiment of the present disclosure has a motor and a motor controller, and the maximum value of the heating current can be the current limiting value of the N-phase winding, for example Figure 6 For a three-phase motor, the maximum value of the heating current is the current limit of the three-phase winding, which is three times that of the related art, thereby improving the efficiency of battery self-heating. In addition, since the battery self-heating system provided by the embodiment of the present disclosure does not use a capacitor as an energy storage element, the battery heating efficiency at low frequency is improved.

[0087] In a possible way, a switch can be added to the circuit to control the on and off of the circuit, refer to Figure 6 The system further includes: a first conversion switch K1 and a second conversion switch K2, wherein the second conversion switch K2 is a two-position switch.

[0088] The first conversion switch K1 is arranged on the connection line between the first winding (the coil in the first motor 1) and the second winding (the coil in the second motor 3). The first moving contact b of the second conversion switch K2 is connected to the positive terminal of the first battery pack E1, and the second moving contact c of the second conversion switch K2 is connected to the negative terminal of the first battery pack E1 and the positive terminal of the second battery pack E2 respectively.

[0089] Furthermore, the first conversion switch K1 and the second conversion switch K2 are both connected to the controller, and the controller is configured to: control the first conversion switch K1 to close, control the static contact a of the second conversion switch K2 to connect with the second moving contact c of the second conversion switch K2, so as to realize the self-heating of the first battery pack E1 and the second battery pack E2. Figures 7 to 10 .

[0090] In a possible manner, the controller is also configured to control the first conversion switch K1 to be disconnected, control the static contact a of the second conversion switch K2 and the first moving contact b of the second conversion switch K2 to be connected, drive the first motor through the first motor controller and drive the second motor through the second motor controller to drive the vehicle.

[0091] For example, the first conversion switch K1 is controlled to be disconnected, and the static contact a of the second conversion switch K2 is controlled to be connected to the first moving contact b of the second conversion switch K2. At this time, the first motor and the first motor controller, the second motor and the second motor controller all constitute a drive module and are respectively connected in parallel with the power battery pack. The working process of the motor and the motor controller in the drive mode can refer to the relevant technology, and the present disclosure will not repeat it here. In addition, a two-position switch can be set for the first heating module with reference to the second conversion switch K2, so that when the first heating module and the second heating module self-heat the battery pack, the first connection end and the second connection end of the first heating module are respectively connected to the positive and negative poles of the first battery pack, and the first connection end and the second connection end of the second heating module are respectively connected to the positive and negative poles of the power battery pack. The present disclosure does not limit this.

[0092] In possible ways, refer to Figure 5 The system further includes a third motor controller and a third motor, wherein a first end of the third motor controller is connected to the positive electrode of the power battery pack, a second end of the third motor controller is connected to the negative electrode of the power battery pack, and the third motor is connected to the third motor controller. The controller is connected to the third motor controller, and the controller is further configured to: drive the third motor through the third motor controller, and control the alternating charge and discharge between the first battery pack and the second battery pack through the first heating module and the second heating module.

[0093] For example, when the battery self-heating system performs battery self-heating, the first battery pack and the second battery pack are charged and discharged alternately, and the voltage fluctuations cancel each other out, so that the terminal voltage fluctuation of the power battery pack is small, thereby avoiding abnormalities in the motor controller and the motor when driving the vehicle. The self-heating process of the first battery pack and the second battery pack can refer to Figures 7 to 10 The working process of the third motor 5 and the third motor controller 6 can refer to the relevant technology, and the present disclosure will not repeat them here.

[0094] In possible ways, refer to Fig.11The system further includes a DC charging port 7, the positive electrode of the DC charging port 7 is connected to the positive electrode of the power battery pack, and the negative electrode of the DC charging port 7 is connected to the negative electrode of the power battery pack. The controller is further configured to: receive electric energy through the DC charging port 7 to charge the power battery pack, and control the alternating charging and discharging between the first battery group E1 and the second battery group E2 through the first heating module and the second heating module.

[0095] Further, in a possible manner, the system further includes: a first charging switch K3 and a second charging switch K4, wherein the first charging switch K3 is a two-position switch. The static contact a of the first charging switch K3 is connected to the positive pole of the DC charging port 7, the first moving contact b of the first charging switch K3 is connected to the positive pole of the first battery pack E1, and the second moving contact c of the first charging switch K3 is respectively connected to the second end of the first winding (first motor 1) and the second end of the second winding (second motor 3). The second charging switch K4 is arranged on the connection line between the negative pole of the DC charging port 7 and the negative pole of the second battery pack E2. The controller is further configured to: control the static contact a of the first charging switch K3 to be connected to the first moving contact b of the first charging switch K3, and control the second charging switch K4 to be closed, and receive electric energy through the DC charging port 7 to charge the power battery pack. The controller is also configured to: control the static contact a of the first charging switch K3 to be connected to the second moving contact c of the first charging switch K3, control the second charging switch K4 to be closed, and control the first upper bridge arm and the second upper bridge arm to be turned on, receive electrical energy through the DC charging port 7, and boost and charge the power battery pack.

[0096] For example, refer to Fig.12 When the vehicle needs direct charging and battery self-heating, the static contact a of the first charging switch K3 is controlled to be connected to the first moving contact b of the first charging switch K3, the second charging switch K4 and the first conversion switch K1 are controlled to be closed, and the static contact a of the second conversion switch K2 is controlled to be connected to the second moving contact c of the second conversion switch K2. The power battery pack is connected to the DC charging port through the first charging switch K3 and the second charging switch K4, and then directly charged through the external charging pile. The current direction is as follows: Fig.12 At the same time, the first battery pack E1 and the second battery pack E2 are self-heated. The bridge arm states and current directions of the first heating module and the second heating module in the first half cycle and the second half cycle can be referred to Figure 7-10 , which will not be described in detail in this disclosure. Thus, the first battery pack E1 and the second battery pack E2 are self-heated while charging the power battery pack. Since the voltage fluctuations of the first battery pack and the second battery pack offset each other, the terminal voltage fluctuation of the power battery pack is small, thereby avoiding vehicle charging failure.

[0097] For example, refer to Fig.13When the vehicle needs to boost and charge the power battery pack, the static contact a of the first charging switch K3 is controlled to be connected to the second moving contact c of the first charging switch K3, the second charging switch K4 and the first conversion switch K1 are controlled to be closed, and the static contact a of the second conversion switch K2 is controlled to be connected to the first moving contact b of the second conversion switch K2. On the one hand, the DC voltage is boosted and charged to the power battery pack through the first heating module. On the other hand, the DC voltage is boosted and charged to the power battery pack through the second heating module after being boosted by the first conversion switch K1, that is, the first heating module and the second heating module boost and charge the power battery pack at the same time, and the current direction is as shown in FIG. Fig.13 . This enables high-power boost charging and improves the charging efficiency of the power battery pack.

[0098] For example, some heating modules can be controlled to participate in boost charging according to demand. For example, the first conversion switch K1 can be disconnected, and only the first heating module boosts the DC voltage and then charges the power battery pack. A switch can also be set between the first winding and the first charging switch, and the switch is disconnected, and the first conversion switch K1 is closed. At this time, only the second heating module boosts the DC voltage and then charges the power battery pack.

[0099] It is worth noting that by using some motor controllers and motors in a multi-motor vehicle as heating modules to self-heat the power battery pack, that is, the motor controller and the motor can be used to drive the vehicle, and can also be used to self-heat the power battery pack, without the need to add other components or heating devices, which meets the demand for heating the power battery pack while saving costs. However, for other single-motor vehicles or dual-motor vehicles, the self-heating function of the power battery pack can be achieved by adding bridge arms and windings as heating modules. Of course, for multi-motor vehicles, bridge arms and windings can also be added as heating modules, and the present disclosure does not limit this.

[0100] For example, when the first bridge arm and the second bridge arm are used to self-heat the power battery pack, the first bridge arm and the second bridge arm can be composed of a single-phase bridge arm or a multi-phase bridge arm. The winding can be a separate single-phase winding or a multi-phase winding, or a coil in a single-phase motor or a multi-phase motor, which is not limited in the present disclosure.

[0101] It should be noted that the controller can be a control unit in a motor controller or an electronic device installed in a vehicle, and the present disclosure does not limit this. A temperature sensor can also be set near the power battery pack to transmit the collected battery temperature to the controller in real time. When the battery temperature is lower than a preset threshold, the controller automatically controls the power battery pack to self-heat. A heating button can also be set on the vehicle, for example, to remind the driver on the vehicle display that the power battery pack is in a low temperature state. The driver can send a signal to the controller to start self-heating through the heating button set on the vehicle display. After receiving the signal, the controller controls the power battery pack to self-heat, etc., and the present disclosure does not limit this.

[0102] In addition, in the process of controlling the battery pack to alternately charge and discharge, one or more of the multiple bridge arms can be controlled to be turned on, thereby controlling the number of windings participating in self-heating, for example Figure 6 In the embodiment, one of the three upper bridge arms of the first motor controller 2 can be selected to be turned on, and the first battery pack E1 discharges to a winding connected thereto in the first motor 1. Generally speaking, the more windings participate in self-heating, the higher the efficiency of self-heating. In other possible implementations, the number of windings participating in self-heating can be controlled according to the battery temperature, for example, the lower the battery temperature, the more windings, and so on, which is not limited in the present disclosure.

[0103] Based on the same inventive concept, the disclosed embodiment also provides a vehicle, including the above-mentioned battery self-heating system, through which the battery in the vehicle is heated and heated to ensure the performance of the battery in a low temperature environment and improve the battery self-heating efficiency. In addition, the power battery pack can also be self-heated when the power battery pack is DC charged or driving the vehicle.

[0104] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0105] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0106] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A battery self-heating system, applied to a vehicle, comprising: A power battery pack, the power battery pack comprising a first battery pack and a second battery pack connected in series; A first heating module, wherein a first connection end and a second connection end of the first heating module are respectively connected to the positive and negative electrodes of the power battery pack; a second heating module, wherein a first connection end and a second connection end of the second heating module are respectively connected to the positive and negative electrodes of the second battery pack; Characterized in that the third connection end of the second heating module is connected to the third connection end of the first heating module; the system further comprises: A controller is connected to the first heating module and the second heating module, and the controller is configured to control the alternating charging and discharging between the first battery group and the second battery group through the first heating module and the second heating module.

2. The system according to claim 1, characterized in that The first heating module includes a first bridge arm and a first winding, wherein a first end of the first bridge arm is connected to the positive electrode of the first battery pack, a second end of the first bridge arm is connected to the negative electrode of the second battery pack, and a first end of the first winding is connected to the midpoint of the first bridge arm; The second heating module includes a second bridge arm and a second winding, the first end of the second bridge arm is connected to the negative electrode of the first battery group, the second end of the second bridge arm is connected to the negative electrode of the second battery group, the first end of the second winding is connected to the midpoint of the second bridge arm, and the second end of the second winding is connected to the second end of the first winding.

3. The system according to claim 2, characterized in that Reusing a bridge arm of a first motor controller as the first bridge arm, and reusing a coil of a first motor connected to the first motor controller as the first winding; The bridge arm of the second motor controller is reused as the second bridge arm, and the coil of the second motor connected to the second motor controller is reused as the second winding.

4. The system according to claim 3, characterized in that The controller is configured to: In a first half cycle, the first battery pack is controlled to discharge through the first heating module and the second heating module, and the second battery pack is charged through the first heating module and the second heating module; In the second half cycle, the second battery pack is controlled to discharge through the first heating module and the second heating module, and the first battery pack is charged through the first heating module and the second heating module.

5. The system according to claim 4, characterized in that The first bridge arm includes a first upper bridge arm and a first lower bridge arm, and the second bridge arm includes a second upper bridge arm and a second lower bridge arm; In a first time period of the first half cycle, the first upper bridge arm and the second upper bridge arm are controlled to be turned on, and the first lower bridge arm and the second lower bridge arm are turned off, and the first battery pack is controlled to discharge through the first heating module and the second heating module; In a second time period of the first half cycle, the first lower bridge arm and the second upper bridge arm are controlled to be turned on, and the first upper bridge arm and the second lower bridge arm are turned off, and the second battery pack is charged through the first heating module and the second heating module.

6. The system according to claim 5, characterized in that In a first time period of the second half cycle, the first lower bridge arm and the second upper bridge arm are controlled to be turned on, and the first upper bridge arm and the second lower bridge arm are turned off, and the second battery pack is controlled to discharge through the first heating module and the second heating module; In a second time period of the second half cycle, the first upper bridge arm and the second upper bridge arm are controlled to be turned on, and the first lower bridge arm and the second lower bridge arm are turned off, and the first battery pack is charged through the first heating module and the second heating module.

7. The system according to claim 5, characterized in that The controller is configured to: In the first half cycle, a first voltage variation amount for controlling the discharge of the first battery pack is the same as a second voltage variation amount for charging the second battery pack; In the second half cycle, the third voltage variation amount for controlling the discharge of the second battery pack is the same as the fourth voltage variation amount for charging the first battery pack.

8. The system according to claim 7, characterized in that The controller is also configured to: In the first half cycle, controlling the ratio between the current value flowing through the first battery group and the current value flowing through the second battery group to be equal to the ratio between the resistance value of the second battery group and the resistance value of the first battery group; In the second half cycle, a ratio between a current value flowing through the first battery group and a current value flowing through the second battery group is controlled to be equal to a ratio between a resistance value of the second battery group and a resistance value of the first battery group.

9. The system according to claim 1, characterized in that The system further comprises: a third motor controller, wherein a first end of the third motor controller is connected to the positive electrode of the power battery pack, and a second end of the third motor controller is connected to the negative electrode of the power battery pack; a third motor, the third motor being connected to the third motor controller; The controller is connected to the third motor controller, and the controller is further configured to: drive the third motor through the third motor controller, and control the alternating charging and discharging between the first battery group and the second battery group through the first heating module and the second heating module.

10. The system according to claim 5, characterized in that The system further comprises: A DC charging port, wherein the positive electrode of the DC charging port is connected to the positive electrode of the power battery pack, and the negative electrode of the DC charging port is connected to the negative electrode of the power battery pack; The controller is further configured to: receive electric energy through the DC charging port to charge the power battery pack, and control alternating charging and discharging between the first battery pack and the second battery pack through the first heating module and the second heating module.

11. The system according to claim 10, characterized in that The system further comprises: A first charging switch and a second charging switch, wherein the first charging switch is a two-position switch; The static contact of the first charging switch is connected to the positive electrode of the DC charging port, the first moving contact of the first charging switch is connected to the positive electrode of the first battery pack, and the second moving contact of the first charging switch is connected to the second end of the first winding and the second end of the second winding respectively; The second charging switch is arranged on a connection line between the negative electrode of the DC charging port and the negative electrode of the second battery pack; The controller is further configured to: control the static contact of the first charging switch to be connected to the first moving contact of the first charging switch, and control the second charging switch to be closed, so as to receive electric energy through the DC charging port to charge the power battery pack; The controller is also configured to: control the static contact of the first charging switch to be connected to the second moving contact of the first charging switch, control the second charging switch to be closed, and control the first upper bridge arm and the second upper bridge arm to be turned on, receive electrical energy through the DC charging port, so as to boost and charge the power battery pack.

12. A vehicle, characterized in that: A battery self-heating system comprising any one of claims 1 to 11.

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