Electric vehicle, battery system and heating device thereof

Abstract

According to the electric vehicle, the battery system and the heating device of the electric vehicle, the first capacitor and the charging and discharging circuit form the first loop used for charging the battery, the second capacitor and the charging and discharging circuit form the second loop used for discharging the battery, and the battery can be heated within continuous time; the charging state and the discharging state can be alternately switched at the preset frequency through the first loop and the second loop, so that the battery generates alternating current to heat the battery in the alternate charging and discharging process, the heat generated in unit time when the heating device heats the battery is increased, the time required for heating the battery is shortened, and the battery heating efficiency is improved. And the heating efficiency of the heating device is further improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to an electric vehicle, a battery system and a heating device thereof. BACKGROUND

[0002] A battery is an important component of an electric vehicle, which can store energy when charging and provide energy required for the operation of the load of the electric vehicle when discharging. When the temperature of the environment where the electric vehicle is located is low, the activity of the electrolyte inside the battery is low, which reduces the energy storage efficiency of the battery and further affects the performance of the battery.

[0003] Some electric vehicles are provided with a heating device inside the battery, which is used to heat the power battery when the ambient temperature is low to improve the activity of the electrolyte inside the battery. Among them, the heating device of the battery can control the battery to charge and discharge when the ambient temperature is low, so that the battery generates an alternating current in its own charging and discharging process, thereby generating heat from the inside of the battery based on the internal resistance of the battery to heat the battery.

[0004] In the prior art, the heating device controls the battery to charge and discharge through the charging and discharging circuit according to a certain frequency through a pulse signal, but the battery only charges or discharges in half of the pulse period, and does not charge or discharge in the other half of the pulse period without receiving the pulse signal, resulting in less heat generated by the battery per unit time. The heating time required for the heating device to heat the battery is longer, so the heating efficiency of the heating device is lower. UTILITY MODEL CONTENT

[0005] The present application provides an electric vehicle, a battery system and a self-heating device thereof to improve the heat generated by the heating device per unit time when heating the battery, thereby reducing the time required for heating the battery and further improving the heating efficiency of the heating device.

[0006] The first aspect of the present application provides a heating device of a battery, comprising: a first capacitor and a second capacitor, which are connected in series and connected in parallel between the positive electrode and the negative electrode of the battery; a charging and discharging circuit, which is connected to the positive electrode and the negative electrode of the battery respectively and connected between the first capacitor and the second capacitor connected in series, the battery being used to charge through a first loop of the charging and discharging circuit and the first capacitor and discharge through a second loop of the charging and discharging circuit and the second capacitor; and a control circuit, which is used to control the charging and discharging circuit according to a preset frequency, so that the battery generates an alternating current by alternately charging and discharging at the preset frequency to heat the battery.

[0007] The second aspect of the present application provides a battery system comprising the heating device provided in the first aspect of the present application.

[0008] The third aspect of the present application provides an electric vehicle comprising the battery system provided in the second aspect of the present application.

[0009] The electric vehicle, the battery system and the heating device thereof provided by the present application can make the battery alternately switch between the charging and discharging states at a preset frequency through the first loop and the second loop respectively in a continuous time period, so that the battery generates an alternating current to heat the battery in the alternating charging and discharging process, thereby avoiding the problem that the battery cannot be charged or discharged in a pulse period, and the battery can continuously perform the alternating charging and discharging in the whole time period, thus improving the heat generated by the heating device per unit time when heating the battery, reducing the time required for heating the battery, and further improving the heating efficiency of the heating device. BRIEF DESCRIPTION OF DRAWINGS

[0010] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0011] Figure 1 The schematic diagram of the application scenario of the present application;

[0012] Figure 2 The structural schematic diagram of the heating device of the battery provided by the present application;

[0013] Figure 3 The structural schematic diagram of the heating device of the battery provided by the present application;

[0014] Figure 4 The circuit structural schematic diagram of the heating device of the battery provided by the present application;

[0015] Figure 5 The schematic diagram of the first control signal of the control circuit provided by the present application;

[0016] Figure 6 The schematic diagram of the second control signal of the control circuit provided by the present application;

[0017] Figure 7 The charging and discharging current schematic diagram of the battery provided by the present application;

[0018] Figure 8 The circuit structural schematic diagram of the heating device provided by the present application in the electric vehicle. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0020] The terms "first", "second", "third", "fourth" and the like (if any) in the specification and claims of the present application and the above drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0021] Figure 1 For the application scenario of the present application, as shown in Figure 1 The present application can be applied to an electric vehicle. The electric vehicle includes a battery 2, a power supply circuit 3, a load 4 and a heating device 1. The battery 2 is connected to the load 4 through the power supply circuit 3. The battery 2 is used to store energy and provide energy to the load 4 through the power supply circuit 3 to drive the load 4 to operate normally.

[0022] When the temperature of the environment where the electric vehicle is located is low, the activity of the electrolyte inside the battery 2 is low, which reduces the energy storage efficiency of the battery 2, and further affects the performance of the battery 2, causing a serious impact on the normal use and popularization of the electric vehicle. Therefore, some electric vehicles also have a heating device 1 for the battery 2. The heating device 1 can be used to heat the battery 2 when the ambient temperature is low to improve the activity of the electrolyte inside the battery 2.

[0023] Specifically, the heating device 2 of the battery 1 can control the battery 1 to charge and discharge through the charging and discharging circuit at a certain frequency through a pulse signal when the ambient temperature is low, so that the battery 1 generates an alternating current in its own charging and discharging process, thereby generating heat from the inside of the battery 2 based on the internal resistance of the battery 1 to heat the battery 1. Ultimately, the battery 2 can quickly heat up when the ambient temperature is low and work in a more suitable temperature range.

[0024] However, the battery 2 in the prior art can only be charged or discharged by the charge-discharge circuit in the half cycle of the received pulse cycle, and the battery 2 cannot be charged or discharged by the charge-discharge circuit in the other half cycle of the received pulse signal, resulting in that the heating device 1 generates less heat per unit time when heating the battery 2, and the heating device 1 needs more heating time to heat the battery 2, so the heating efficiency of the heating device 1 of the battery 2 in the prior art is low.

[0025] Based on the above technical problems, the present application provides a heating device for a battery to improve the heat generated per unit time when the heating device heats the battery, thereby reducing the time required for heating the battery, and further improving the heating efficiency of the heating device. The technical solutions of the present application will be described in detail below with specific examples. The following specific examples can be combined with each other, and the same or similar concepts or processes may not be described in detail in some examples.

[0026] Figure 2 The structure diagram of an embodiment of the heating device for a battery provided by the present application is shown in Figure 2 The heating device 1 shown in Figure 1 may be applied to an electric vehicle as shown in Figure 2 The heating device 1 of the battery 2 shown in includes a control circuit 11, a charge-discharge circuit 12, a first capacitor 13 and a second capacitor 14. The first capacitor 13 and the second capacitor 14 are connected in series and connected in parallel between the positive and negative electrodes of the battery 2, and the charge-discharge circuit 12 is connected between the positive and negative electrodes of the battery 2 and connected between the first capacitor 13 and the second capacitor 14 connected in series.

[0027] Therefore, in the heating device provided by the present embodiment, the battery 2 can be charged by the first loop formed by the charge-discharge circuit 12 and the first capacitor 13, and discharged by the second loop formed by the charge-discharge circuit 12 and the second capacitor 14.

[0028] More specifically, the control circuit 11 can be used to control the charge-discharge circuit 12 at a predetermined frequency, so that the battery 2 alternately charges by the first loop and discharges by the second loop at the predetermined frequency, so that the battery 2 can generate alternating current to heat the battery 2.

[0029] In summary, the heating device 2 of the battery 1 provided in the embodiment can make the battery 2 generate alternating current to heat the battery 2 in the alternating charging and discharging process, thereby avoiding the problem that the battery 2 cannot be charged or discharged in the pulse period, and the battery 2 can continuously perform the alternating charging and discharging in the whole time period, thereby improving the heat generated by the heating device 1 per unit time when heating the battery 2, reducing the time required for heating the battery 2, and further improving the heating efficiency of the heating device 1.

[0030] Figure 3 The structure schematic diagram of another embodiment of the heating device of the battery provided in the application is shown in Figure 3 The heating device 1 shown in the embodiment further includes a switching circuit 15 on the basis of the embodiment shown in Figure 2 The charging and discharging circuit 12 is connected between the first capacitor 13 and the second capacitor 14 in series through the switching circuit 15.

[0031] When the switching circuit 15 is in the conductive state, the charging and discharging circuit 12 can form the first loop and the second loop with the first capacitor 13 and the second capacitor 14 respectively, so that the battery 2 can be charged and discharged through the first loop and the second loop. When the switching circuit 15 is in the open state, the charging and discharging circuit 12 cannot form the first loop and the second loop with the first capacitor 13 and the second capacitor 14, and the battery 2 cannot be charged and discharged.

[0032] In an embodiment, the control circuit 11 can be used to send a control signal gk to the switching circuit, so that the switching circuit gk is switched to the conductive state or the open state according to the control signal. For example, before the control circuit 11 controls the charging and discharging circuit 12 to make the battery 1 alternately charge and discharge at a preset frequency, the control circuit 11 can send a control signal gk to the switching circuit 15, so that the switching circuit 15 is switched to the conductive state according to the control signal gk, to ensure the effective implementation of the self-heating function of the battery 1. For another example, before the control circuit 11 controls the battery 1 to supply power to the load 4, the control circuit 11 can send a control signal gk to the switching circuit 15, so that the switching circuit 15 is switched to the closed state according to the control signal gk, to avoid affecting the normal power supply of the battery 1 to the load 4. The setting of the switching circuit 15 can improve the safety performance of the heating device 1, and make the whole heating process of the battery 2 more safe and stable.

[0033] In an embodiment, the control circuit 11 can be used to control the charge-discharge circuit 12 and the switching circuit 15, or in another embodiment, the heating device 1 can also be provided with different control circuits to control the charge-discharge circuit 12 and the switching circuit 15 respectively. The specific manner can be determined according to the implementation scenario, which improves the flexibility of the heating device 1 provided by the present application.

[0034] In an embodiment, the charge-discharge circuit 12 provided by the embodiment of the present application specifically comprises: at least one bridge arm 123 and at least one inductor 121. Wherein, the at least one bridge arm 123 corresponds to the at least one inductor 21 one by one. Each bridge arm 123 is respectively connected in parallel between the positive and negative electrodes of the battery 2, the midpoint of the bridge arm 123 is connected to one end of the corresponding inductor 121, and the other end of the inductor 121 is connected to the switching circuit 15.

[0035] The specific number of bridge arms 123 and inductors 121 in the charge-discharge circuit 12 provided by the embodiment is not limited, wherein the number of bridge arms 123 and inductors 121 included in the charge-discharge circuit 12 is proportional to the maximum current value that can be reached when the battery 2 is alternately charged and discharged. That is, when the number of bridge arms 123 and inductors 121 provided in the charge-discharge circuit 12 is greater, the maximum current value when the battery 2 is charged and discharged through the first loop and the second loop of the charge-discharge circuit 12 is greater. Wherein, when the number of bridge arms 123 and inductors 121 provided in the charge-discharge circuit 12 is greater, the total inductance value obtained by the inductors 121 connected in parallel in the heating device 1 is smaller, the current is less limited, and the heating device 1 can provide greater current, thereby further improving the heating effect of the heating device 1 on the power battery 2.

[0036] Figure 4 The circuit structure schematic diagram of the heating device for the battery provided by an embodiment of the present application is shown in Figure 4 It is shown that Figure 3 The heating device 1 shown is a specific circuit implementation. Wherein, taking the charge-discharge circuit 12 including three bridge arms 123 as an example, which are respectively denoted as the first bridge arm 123a, the second bridge arm 123b, and the third bridge arm 123c, the charge-discharge circuit 12 further includes three corresponding inductors, which are respectively denoted as the first inductor 121a, the second inductor 121b, and the third inductor 121c. As shown in Figure 4 The charge-discharge circuit 12 further includes a first resistor 122a, a second resistor 122b, and a third resistor 122c.

[0037] The midpoint za of the first bridge arm 123a is connected to one end of the first resistor 122a, the other end of the first resistor 122a is connected to one end of the first inductor 121a, and the other end of the first inductor 121a is connected to the switch circuit 15; the midpoint zb of the second bridge arm 123b is connected to one end of the second resistor 122b, the other end of the second resistor 122b is connected to one end of the second inductor 121b, and the other end of the second inductor 121b is connected to the switch circuit 15; the midpoint zc of the third bridge arm 123c is connected to one end of the third resistor 122c, the other end of the third resistor 122c is connected to one end of the third inductor 121c, and the other end of the third inductor 121c is connected to the switch circuit 15.

[0038] The control circuit 11 can be used to send control signals to each switch tube in the first bridge arm 123a, the second bridge arm 123b, and the third bridge arm 123c to control each switch tube to switch to a conducting state or a closed state. For example, the control circuit 11 sends a control signal to the control end ga1 of the upper bridge arm 123a1 of the first bridge arm 123a, sends a control signal to the control end ga2 of the lower bridge arm 123a2 of the first bridge arm 123a, sends a control signal to the control end gb1 of the upper bridge arm 123b1 of the second bridge arm 123b, sends a control signal to the control end gb2 of the lower bridge arm 123b2 of the second bridge arm 123b, sends a control signal to the control end gc1 of the upper bridge arm 123c1 of the third bridge arm 123c, and sends a control signal to the control end gc2 of the lower bridge arm 123c2 of the third bridge arm 123c.

[0039] Then, when the control circuit 11 controls the charge-discharge circuit 12 according to the preset frequency, the upper bridge arms and the lower bridge arms of the first bridge arm 123a, the second bridge arm 123b, and the third bridge arm 123c are controlled according to the preset frequency, wherein the upper bridge arms of the first bridge arm 123a, the second bridge arm 123b, and the third bridge arm 123c are simultaneously turned on or turned off, and the lower bridge arms of the first bridge arm 123a, the second bridge arm 123b, and the third bridge arm 123c are simultaneously turned off or turned on. Then, when the upper bridge arms and the lower bridge arms of the first bridge arm 123a, the second bridge arm 123b, and the third bridge arm 123c are alternately turned on and turned off at a target duty ratio, the working state of the charge-discharge circuit 12 is alternately switched.

[0040] Figure 5 The first control signal of the control circuit provided in the present application is shown in the schematic diagram Figure 4 The control circuit 11 sends a control signal G1 to the upper bridge arms of the first bridge arm 123a, the second bridge arm 123b, and the third bridge arm 123c.

[0041] Figure 6 The second control signal of the control circuit provided in the present application is shown in the schematic diagram Figure 4The control circuit 11 sends the control signal G2 to the upper bridge arm of the first bridge arm 123a, the second bridge arm 123b and the third bridge arm 123c.

[0042] In combination Figure 5 And Figure 6 Between t1 and t2, the control circuit 11 sends the control signal G1 to the control end ga1 of the upper bridge arm 123a1 of the first bridge arm 123a, the control end gb1 of the upper bridge arm 123b1 of the second bridge arm 123b and the control end gc1 of the upper bridge arm 123c1 of the third bridge arm 123c, respectively, so that the upper bridge arm 123a1 of the first bridge arm 123a, the upper bridge arm 123b1 of the second bridge arm 123b and the upper bridge arm 123c1 of the third bridge arm 123c are all turned on, and the lower bridge arm 123a2 of the first bridge arm 123a, the lower bridge arm 123b2 of the second bridge arm 123b and the lower bridge arm 123c2 of the third bridge arm 123c are all turned off.

[0043] Then between t1 and t2, the positive electrode of the battery 2, the upper bridge arm 123a1 of the first bridge arm 123a, the upper bridge arm 123b1 of the second bridge arm 123b and the upper bridge arm 123c1 of the third bridge arm 123c, the first inductor 121a, the second inductor 121b and the third inductor 121c, the second capacitor C2, the negative electrode of the battery 2 form a second loop that discharges the battery 2, and the second loop is a CLC half-bridge resonant circuit, and the resonant frequency is determined by all inductors, the first capacitor C1 and the second capacitor C2, and the first inductor 121a, the second inductor 121b and the third inductor 121c are charged and achieve energy storage.

[0044] Between t2 and t3, the control circuit 11 sends the control signal G2 to the control end ga2 of the lower bridge arm 123a2 of the first bridge arm 123a, the control end gb2 of the lower bridge arm 123b2 of the second bridge arm 123b and the control end gc2 of the lower bridge arm 123c2 of the third bridge arm 123c, respectively, so that the lower bridge arm 123a2 of the first bridge arm 123a, the lower bridge arm 123b2 of the second bridge arm 123b and the lower bridge arm 123c2 of the third bridge arm 123c are all turned on, and the upper bridge arm 123a1 of the first bridge arm 123a, the upper bridge arm 123b1 of the second bridge arm 123b and the upper bridge arm 123c1 of the third bridge arm 123c are all turned off.

[0045] The first inductor 121a, the second inductor 121b and the third inductor 121c, the first capacitor C1, the positive electrode of the battery 2, the negative electrode of the battery 2, the lower bridge arm 123a2 of the first bridge arm 123a, the lower bridge arm 123b2 of the second bridge arm 123b and the lower bridge arm 123c2 of the third bridge arm 123c form a first loop between the time t2 and the time t3, and the first loop is specifically a CLC half-bridge resonant circuit, and the resonant frequency is determined by all the inductors, the first capacitor C1 and the second capacitor C2. The first inductor 121a, the second inductor 121b and the third inductor 121c discharge and charge the battery 2.

[0046] The total time length T from the time t1 to the time t3 is recorded as a preset period, and the reciprocal of the preset period T is a preset frequency f. The control circuit 11 controls the upper bridge arms of all the bridge arms 123 to be turned on and the lower bridge arms to be turned off in the first part of each preset period T, and controls the upper bridge arms of all the bridge arms 123 to be turned off and the lower bridge arms to be turned on in the second part of each preset period T.

[0047] The target duty ratio is the ratio of the time during which the control circuit 11 controls the upper bridge arms of all the bridge arms 123 to be turned on and the lower bridge arms to be turned off in the preset period T to the whole time of the preset period T. The target duty ratio is Figure 5 and Figure 6 Taking the first preset period T in the first preset period T as an example, the target duty ratio is the ratio of the time length between the time t1 and the time t2 to the total time length between the time t1 and the time t3. It can be seen that in each preset period, the upper bridge arms and the lower bridge arms of all the bridge arms 123 are turned on and turned off alternately once, so that the working state of the charging and discharging circuit 12 is switched once, and the battery 2 is alternately switched between charging and discharging states at the same preset frequency, and the battery 2 generates an alternating current to heat the battery 2.

[0048] In an embodiment, the control circuit 11 controls all the upper bridge arms of the bridge arms 123 to be turned on and the lower bridge arms to be turned off at a preset frequency in each preset period. The target duty ratio can be first set to 50%. Then, the control circuit 11 can adjust the target duty ratio according to the current value flowing through the battery 2, so as to adjust the current value flowing through the battery 2, and further adjust the heating power of the battery 2, so as to make the heating of the battery 2 more uniform and controllable. For example, when the current value of the battery 2 is less than a preset current value, the duty ratio can be increased to increase the discharging time of the battery 2, so as to increase the current value flowing through the battery 2, and further increase the heating power of the battery 2. When the current value of the battery 2 is greater than the preset current value, the duty ratio can be reduced to reduce the discharging time of the battery 2, so as to reduce the current value flowing through the battery 2, and further reduce the heating power of the battery 2. The embodiment can increase the flexibility and real-time performance of the control circuit 11 in controlling the charging and discharging circuit 12, so as to make the battery 2 heat at a certain power value, and ensure the stability and reliability of the heating of the battery 2.

[0049] The heating device provided in the embodiment can control the battery 2 to be alternately charged and discharged by controlling the upper bridge arms and the lower bridge arms of the bridge arms 123 to be alternately turned on and turned off. The control logic of the control circuit 11 is relatively simple, which is conducive to the promotion and application of the heating device 1.

[0050] Figure 7 The charging and discharging current diagram of the battery provided in the present application is shown in the figure. The control circuit 11 controls the charging and discharging circuit 12 to make the battery 2 alternately switch between charging and discharging in the manner shown in Figure 5 and Figure 6 The current value change curve of the battery 2 can be seen. It can be seen that the battery 2 generates an alternating current which periodically changes between positive current and negative current. Therefore, the battery 2 generates heat under the action of the alternating current, and finally realizes the heating of the battery 2.

[0051] In an embodiment, the charging and discharging circuit 12 shown in Figure 4 may be realized based on the conversion circuit of the three-phase alternating current provided in the electric vehicle.

[0052] Specifically, the three bridge arms 123 of the charging and discharging circuit 12 shown in Figure 4 may be the inverter 32 of the electric vehicle. The inverter is a three-phase six-arm full-bridge structure, including three bridge arms and six switching tubes, which is used to convert direct current voltage into three-phase alternating current voltage. The switching tube can be an IGBT or silicon carbide.

[0053] The three inductors 121 and the corresponding resistors 122 can be the three-phase windings 31 of the motor of the electric vehicle. One phase winding in the three-phase coil winding can be used to realize one inductor 121.

[0054] The connection line from the junction point of one end of the three-phase winding is connected with the switch circuit 15. The connection line from the junction point of the three-phase motor can also be referred to as an N line, and thus the switch circuit 15 can also be referred to as an N line switch.

[0055] Therefore, the embodiment can achieve the above-mentioned functions without adding new bridge arms and inductors in the electric vehicle. Figure 4 The heating device 1 shown in the battery 2 reduces the structural complexity and manufacturing cost of the heating device 1 and the electric vehicle in which the heating device 1 is located.

[0056] Further, in the embodiment, the heating device 1 further comprises a first heat dissipation device 130 and a second heat dissipation device 140. The first heat dissipation device 130 is arranged in contact with the first capacitor 13 and is used to reduce the temperature of the first capacitor 13. The second heat dissipation device 140 is arranged in contact with the second capacitor 14 and is used to reduce the temperature of the second capacitor 14. For example, the first heat dissipation device 130 and the second heat dissipation device 140 can be heat sinks.

[0057] Specifically, when the battery 2 is discharged through the charging and discharging circuit 12 and the second capacitor 14, the second capacitor 14 generates heat, and the second heat dissipation device 140 can reduce the temperature of the second capacitor 14. When the battery 2 is charged through the charging and discharging circuit 12 and the first capacitor 13, the first capacitor 13 generates heat, and the first heat dissipation device 130 can reduce the temperature of the first capacitor 13. This avoids damage to the electric motor when the temperature is too high, which causes the capacitor to be unable to resonate and the battery 2 to be unable to generate alternating current, thereby ensuring the safety and stability of the first capacitor 13, the second capacitor 14, and the heating device 1 as a whole.

[0058] In an embodiment, the heating device 1 can further comprise heat dissipation devices for the bridge arm 123 and the inductor 121 in the charging and discharging circuit 12. When the charging and discharging circuit 12 is implemented by the inverter 32 and the three-phase winding 31 of the motor in the multipurpose electric vehicle, the bridge arm 123 and the inductor 121 can be cooled by the heat dissipation devices of the inverter 32 and the three-phase winding 31 of the motor. This maximizes the use of the existing structure of the electric vehicle, reduces the circuit complexity of the heating device 1, and reduces the cost.

[0059] Figure 8 The circuit structure of the heating device provided in the electric vehicle is shown in FIG. 1. The heating device 1 shown in FIG. 1 is based on the embodiment shown in FIG. 2. Figure 8 The heating device 1 shown in FIG. 1 is based on the embodiment shown in FIG. 2. Figure 4 The battery 2 is further connected to the load 4 of the electric vehicle through the first capacitor 13 and the second capacitor 14 in series. The heating device 1 shown in FIG. 1 is based on the embodiment shown in FIG. 2. Figure 8The heating device 1 shown in the figure can heat the battery 2 in the working state, and when the battery 2 supplies power to the load 4 through the first capacitor 13 and the second capacitor 14 in the non-working state, the first capacitor 13 and the second capacitor 14 in series are equivalent to a filter capacitor connected between the positive and negative electrodes of the battery 2, which does not affect the normal power supply of the battery 2 to the load 4, and can also be used to filter the voltage ripple of the voltage output by the battery 2 to the load 4, so that the voltage ripple of the discharge voltage of the battery 1 is smaller, thereby ensuring the stability and reliability of the voltage provided by the battery 2 to the load 4.

[0060] In an embodiment, when the electric vehicle is in the driving state, the control circuit 11 first sends a control signal gk to the switching circuit 15 to make the switching circuit 15 off according to the control signal gk, and then the control circuit 11 controls the battery 2 to supply power to the load 4. When the electric vehicle is in the parking state, the control circuit 11 can first send a control signal gk to the switching circuit 15 to make the switching circuit 15 on according to the control signal gk, and then control the charge-discharge circuit 12 to alternately charge and discharge the battery 2 to achieve self-heating.

[0061] In an embodiment, when the battery 2 of the electric vehicle is charging, the control device of the electric vehicle also needs to detect the charging current of the battery 2 to control the charging current and other charging parameters. The self-heating current generated by the battery 2 in the heating device 1 provided in the embodiment may affect the detection result of the charging current of the battery 2. Therefore, in the electric vehicle using the heating device 1 provided in the embodiment, the charging current detection point can be set at a position where the charging loop and the first loop and the second loop of the heating device 1 are not shared, to avoid mutual influence between them.

[0062] In an embodiment, when the electric vehicle stops self-heating the battery 2, the control circuit 10 does not immediately control the switching circuit 15 to be off, but controls all the upper bridge arms of the bridge arms 123 to be off and the lower bridge arms to be on, and lasts for a period of time, so as to release the energy in the inductance 121 of the motor, preventing the energy stored in the inductance 121 from damaging other devices. After a period of time, when the current on the N line of the motor is 0, the control circuit 11 controls the switching circuit 15 to be off.

[0063] More specifically, the application also provides a control method of the heating device 1, which can be used to control the heating device 1 shown in the figure. Figure 4 Or Figure 8 More specifically, the control method includes:

[0064] S01: When the electric vehicle is in the parking state, the control device of the electric vehicle judges whether the current environment temperature of the electric vehicle and the temperature of the battery 2 are lower than a certain preset temperature value, which can be 0 degrees, for example.

[0065] S02: When the ambient temperature and the temperature of the battery 2 are lower than the preset temperature value, the control device of the electric vehicle turns on the self-heating function of the battery 2 through the heating device 1, sends a self-heating command to the control circuit 11, and controls the switching circuit 15 to switch to the on state.

[0066] S03: After the control circuit 11 of the heating device 1 receives the self-heating command sent by the control device of the electric vehicle, the bridge arm in the charge-discharge circuit 12 is periodically switched according to the preset frequency, so that the battery 2 is alternately charged and discharged at the preset frequency to generate an alternating current, thereby heating the battery 2. For specific implementation and principles, refer to Figures 5-7 , which will not be repeated here.

[0067] S04: The control device of the electric vehicle detects the temperature of the battery 2 by multiplexing the original temperature detection system of the electric vehicle. When the temperature of the battery 2 rises to a threshold value that can be charged or driven, a stop self-heating command is sent to the control circuit 11, and the control circuit 11 stops controlling the charge-discharge circuit 12.

[0068] The application also provides a battery system comprising the heating device provided in any of the preceding embodiments.

[0069] The application also provides an electric vehicle comprising the battery system provided in the above embodiments.

[0070] Those skilled in the art can understand that all or part of the steps of the above-mentioned method embodiments can be completed by program instruction-related hardware. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, the steps of the above-mentioned method embodiments are executed; and the aforementioned storage medium includes ROM, RAM, magnetic disc or optical disc and various storage medium that can store program codes.

[0071] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the application, and not to limit them; although the application has been described in detail with reference to the above embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the above embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the application.

Claims

1. A heating device for a battery, characterized in that, include: The first capacitor (13) and the second capacitor (14) are connected in series and then connected in parallel between the positive and negative terminals of the battery (2). A charging and discharging circuit (12) is connected to the positive and negative terminals of the battery (2) respectively, and is connected between the first capacitor (13) and the second capacitor (14) connected in series. The battery (2) is used to charge through the first circuit of the charging and discharging circuit (12) and the first capacitor (13), and to discharge through the second circuit of the charging and discharging circuit (12) and the second capacitor (14). The control circuit (11) is used to control the charging and discharging circuit (12) according to a preset frequency, so that the battery (2) alternately charges and discharges at the preset frequency to generate an alternating current to heat the battery (2).

2. The heating device according to claim 1, characterized in that, Also includes: The switching circuit (15) connects the charging and discharging circuit (12) to the first capacitor (13) and the second capacitor (14) connected in series via the switching circuit (15).

3. The heating device according to claim 2, characterized in that, The charging and discharging circuit (12) includes: At least one bridge arm (123) is connected in parallel between the positive and negative terminals of the battery (2), and the midpoint of the bridge arm (123) is connected to the corresponding inductor (121). At least one inductor (121) corresponds one-to-one with the at least one bridge arm (123), one end of the inductor (121) is connected to the midpoint of the corresponding bridge arm (123), and the other end of the inductor (121) is connected to the switching circuit (15).

4. The heating device according to claim 3, characterized in that, The number of the bridge arms (123) and the inductors (121) included in the charging and discharging circuit (12) is proportional to the maximum current value when the battery (2) is alternately charged and discharged.

5. The heating device according to claim 4, characterized in that, The at least one inductor (121) is the first inductor (121a), the second inductor (121b), and the third inductor (121c) of the three-phase winding of the motor. After one end of the first inductor (121a), the second inductor (121b), and the third inductor (121c) are connected together, they are connected to the first capacitor (13) and the second capacitor (14) connected in series through the switching circuit (15).

6. The heating device according to claim 5, characterized in that, The three-phase winding further includes a first resistor (122a), a second resistor (122b), and a third resistor (122c). One end of the first resistor (122a), the second resistor (122b), and the third resistor (122c) is connected to the corresponding first inductor (121a), the second inductor (121b), and the third inductor (121c). The other end of the first resistor (122a), the second resistor (122b), and the third resistor (122c) is connected to the midpoint of the corresponding first bridge arm (123a), the second bridge arm (123b), and the third bridge arm (123c), respectively.

7. The heating device according to any one of claims 1-6, characterized in that, Also includes: The first heat dissipation device (130) is attached to the first capacitor (13) and is used to reduce the temperature of the first capacitor (13); The second heat dissipation device (140) is attached to the second capacitor (14) to reduce the temperature of the second capacitor (14).

8. A battery system, characterized in that, Includes a battery and a heating device as described in any one of claims 1-7.

9. An electric vehicle, characterized in that, Includes the battery system as described in claim 8.

10. The electric vehicle according to claim 9, characterized in that, The battery (2) is also connected to the load (4) of the electric vehicle through the first capacitor (13) and the second capacitor (14). The first capacitor (13) and the second capacitor (14) are used to filter out the ripple of the voltage output by the battery (2) to the load (4).

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