Electric vehicle, heating device of power battery and control method of heating device

Abstract

The invention provides an electric vehicle, a power battery heating device and a control method thereof.The power battery heating device comprises a control circuit, a first resonance circuit and a second resonance circuit, and the control circuit controls the second resonance circuit to alternately switch working states according to a preset frequency; the power battery is charged and discharged alternately through the first resonance circuit and the second resonance circuit, the resonance inductance of the first resonance circuit is the parasitic inductance of the power battery, the power battery is charged and discharged at a larger preset frequency through the two resonance circuits, and the charging and discharging current of the power battery is improved; therefore, the heat generated by the power battery in unit time is increased, the heating time required by the heating device for heating the power battery is shortened, and the heating efficiency of the heating device is further improved.

Description

[0001] This application claims the priority of the Chinese patent application filed with the China Patent Office on September 5, 2024, with application number 202411247947.2 and application name “Heating device for electric vehicle and power battery and control method thereof”, all contents of which are incorporated by reference in this application. Technical Field

[0002] The present application relates to the field of battery technology, and in particular to a heating device for an electric vehicle and a power battery and a control method thereof. Background Art

[0003] Power batteries are an important part of electric vehicles. They can store energy when charged and provide the energy required for the operation of electric vehicle loads when discharged. When the temperature of the electric vehicle's environment is low, the activity of the electrolyte inside the power battery is low, resulting in a decrease in the energy storage efficiency of the power battery, which in turn affects the performance of the power battery.

[0004] Some electric vehicles are equipped with a heating device inside the power battery to heat the power battery when the ambient temperature is low so as to increase the activity of the electrolyte inside the power battery. The power battery heating device can control the power battery to charge and discharge when the ambient temperature is low, so that the power battery generates heat from the inside of the power battery based on the internal resistance of the power battery during its own charging and discharging process.

[0005] In the prior art, the current of the heating device controlling the charging and discharging of the power battery is relatively small, so the heat generated per unit time is relatively small, and the heating device needs more time to heat the power battery, resulting in a lower heating efficiency of the power battery heating device. Summary of the invention

[0006] The present application provides an electric vehicle, a heating device for a power battery and a control method thereof, so as to solve the technical problems in the prior art that a heating device takes a long time to heat a power battery and has a low heating efficiency.

[0007] In a first aspect, the present application provides a control method for a heating device of a power battery, the heating device comprising: a first resonant circuit and a second resonant circuit, the resonant inductance of the first resonant circuit being the parasitic inductance of the power battery, the control method comprising: obtaining a preset frequency, the preset frequency being determined according to the resonant capacitance value and the resonant inductance value of the first resonant circuit, and the resonant capacitance value and the resonant inductance value of the second resonant circuit; and controlling the second resonant circuit to alternately switch working states according to the preset frequency, so that the power battery is alternately charged and discharged at the preset frequency through the first resonant circuit and the second resonant circuit.

[0008] The second aspect of the present application provides a method comprising: a control circuit, a first resonant circuit and a second resonant circuit, the resonant inductance of the first resonant circuit is the parasitic inductance of the power battery, the control circuit is connected to the second resonant circuit, and the control circuit is configured to execute the method of the first aspect of the present application.

[0009] A third aspect of the present application provides a battery system, comprising a power battery and a heating device for the power battery of the second aspect of the present application.

[0010] A fourth aspect of the present application provides an electric vehicle, comprising a battery system as described in the third aspect of the present application.

[0011] In summary, the present application provides an electric vehicle, a heating device for a power battery and a control method thereof, wherein the heating device for the power battery includes a control circuit, a first resonant circuit and a second resonant circuit. The control circuit controls the second resonant circuit to alternately switch working states according to a preset frequency, so that the power battery is alternately charged and discharged through the first resonant circuit and the second resonant circuit. The resonant inductance of the first resonant circuit is the parasitic inductance of the power battery, so that the power battery is charged and discharged at a larger preset frequency through the two resonant circuits, thereby increasing the charging and discharging current of the power battery, thereby increasing the heat generated by the power battery per unit time, reducing the heating time required for the heating device to heat the power battery, and thereby improving the heating efficiency of the heating device. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0013] Figure 1 A schematic diagram of the application scenario of this application;

[0014] Figure 2 It is a structural schematic diagram of a heating device for an electric vehicle in the related art;

[0015] Figure 3 A schematic structural diagram of an embodiment of a heating device for a power battery provided in the present application;

[0016] Figure 4 A schematic flow chart of an embodiment of a control method for a heating device of a power battery provided in the present application;

[0017] Figure 5 A schematic structural diagram of an embodiment of a heating device for a power battery provided in the present application;

[0018] Figure 6 A schematic diagram of a first control signal of a control circuit provided by the present application;

[0019] Figure 7 A schematic diagram of a second control signal of the control circuit provided in the present application;

[0020] Figure 8 A schematic diagram of the current through which the power battery provided in this application is charged and discharged;

[0021] Fig. 9 A schematic diagram of the current value of the power battery of the heating device provided in this application;

[0022] Fig.10 A schematic diagram of the structure of the parasitic inductance detection circuit provided in this application;

[0023] Fig.11 A schematic flow chart of an embodiment of a control method for a heating device of a power battery provided in the present application;

[0024] Fig.12 A schematic diagram of a specific application of the heating device provided in this application;

[0025] Fig.13 A schematic diagram of another specific application of the heating device provided in this application;

[0026] Fig.14 A schematic diagram of another specific application of the heating device provided in the present application;

[0027] Fig.15 It is a current schematic diagram of a power battery during charging and discharging;

[0028] Fig.16 Another current diagram of a power battery during charging and discharging;

[0029] Fig.17 This is another current diagram of the power battery during charging and discharging. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0031] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can, for example, be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0032] Figure 1 This is a schematic diagram of the application scenario of this application, such as Figure 1 As shown, the present application can be applied to an electric vehicle. The electric vehicle includes: a power battery 2, a power circuit 3, a load 4 and a heating circuit 1. The power battery 2 is connected to the load 4 through the power circuit 3. The power battery 2 is used to store energy and provide energy to the load 4 through the power circuit 3 to drive the load 4 to operate normally.

[0033] When the temperature of the environment in which the electric vehicle is located is low, the activity of the electrolyte inside the power battery 2 is low, resulting in a decrease in the energy storage efficiency of the power battery 2, which in turn affects the performance of the power battery 2, causing a relatively serious impact on the normal use and popularization of electric vehicles. Therefore, some electric vehicles are equipped with a heating device to enable the power battery 2 to quickly heat up when the ambient temperature is low and operate within a more suitable temperature range.

[0034] In the related art, the heating device of electric vehicles can be divided into external heating devices and internal heating devices. The external heating device heats the power battery 2 by heat conduction through a heating device such as a heater set outside the power battery 2. However, the heating rate of the external heating device is slow and the heat loss is large. Therefore, more electric vehicles are equipped with internal heating devices to heat the power battery 2. For example, Figure 1 The heating device 1 provided in the electric vehicle shown is an internal heating device. The heating device 1 can control the charging and discharging of the power battery 2 when the ambient temperature is low, so that the internal resistance of the power battery 2 generates heat during the charging and discharging process, and generates heat from the inside of the power battery 2. Compared with an external heating device, the heating device 1 has a faster heating speed and lower heat loss.

[0035] Figure 2 FIG. 1 is a schematic diagram of a heating device for an electric vehicle in the related art. Figure 2The heating device 1 shown includes a control circuit 10, a resonant circuit 100 and an energy storage element 110. The power battery 2 is connected to the energy storage element 110 via the resonant circuit 100. The resonant circuit 100 includes a resonant capacitor L and a resonant inductor C. The resonant capacitor L and the resonant inductor C can determine the resonant frequency corresponding to the resonant circuit 100. The control circuit 10 is connected to the resonant circuit 100. The control circuit 10 can be used to control the resonant circuit 100 to alternately turn on and off in each cycle according to the resonant frequency f, so that the power battery 2 is alternately charged and discharged through the resonant circuit 100, and the internal heating of the power battery 2 is achieved during the charging and discharging process of the power battery 2.

[0036] However, in Figure 2 In the technology shown, the control circuit 10 can only control the power battery 2 through the resonant circuit 100 according to the resonant frequency f. Since the resonant frequency f is low, the current of the power battery 2 for charging and discharging is small, and the heat that the power battery 2 can generate per unit time is small. The heating time required for heating the power battery 2 is also longer, resulting in a low heating efficiency of the power battery heating device. At the same time, the volume of the resonant inductor C in the resonant circuit 100 is large, resulting in more devices being required to be added when the heating device 1 is added to the electric vehicle, and a large amount of space inside the electric vehicle is occupied, which affects the installation and setting of the internal circuit of the electric vehicle. In order to increase the resonant frequency f, the inductance value of the resonant inductor C needs to be further increased. The higher the inductance value of the resonant inductor C, the larger its volume. Therefore, Figure 2 In the related art shown, it is impossible to directly increase the resonant inductance C to increase the resonant frequency f and thus improve the heating efficiency of the power battery 2 .

[0037] Based on the above technical problems, the present application provides a heating device for an electric vehicle and a control method thereof. The first resonant circuit and the second resonant circuit in the heating device are used to charge and discharge the power battery. Therefore, the control circuit can determine a larger resonant frequency based on the resonant inductance and resonant capacitance of the first resonant circuit and the second resonant circuit. The larger resonant frequency can increase the current of the power battery for charging and discharging, thereby improving the heating efficiency of the power battery by the heating device. The technical solution of the present application is described in detail with specific embodiments below. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments.

[0038] Figure 3 This is a structural schematic diagram of an embodiment of a heating device for a power battery provided in the present application, as shown in FIG. Figure 3The heating device 1 of the power battery 2 shown includes: a first resonant circuit 101, a second resonant circuit 102, an energy storage element 110 and a control circuit 10. The first resonant circuit 101, the second resonant circuit 102 and the energy storage element 110 are sequentially connected in parallel between the positive and negative electrodes of the power battery 2.

[0039] The first resonant circuit 101 and the second resonant circuit 102 can specifically be LC resonant circuits, each of which includes a respective resonant capacitor and a resonant inductor, which can be used to store the energy generated by the oscillation when the current flowing through the circuit resonates. The resonant capacitor and the resonant inductor in the first resonant circuit 101, and the resonant capacitor and the resonant inductor in the second resonant circuit 102 resonate respectively, which is equivalent to two parallel resonant circuits generating resonance in the circuit at the same time. In particular, the resonant inductor of the first resonant circuit 101 provided in this embodiment is provided by the parasitic inductance of the power battery 2. Among them, the power battery 2 can be equivalent to a power supply 21, a parasitic inductor 20 and an internal resistance 22, and the power supply 21 is used to provide a rated voltage.

[0040] The control circuit 10 is connected to the second resonant circuit 102 and can be used to control the working state of the second resonant circuit 102 to switch. For example, Figure 4 This is a flow chart of an embodiment of a control method for a heating device of a power battery provided in the present application, such as Figure 4 The method shown can be used as Figure 3 The control circuit 10 shown in FIG. Figure 4 The control method of the heating device of the power battery shown includes:

[0041] S101: the control circuit 10 obtains a preset frequency, wherein the preset frequency is calculated based on the resonant capacitance value of the first resonant circuit 101, the resonant inductance value of the first resonant circuit 101, the resonant capacitance value of the second resonant circuit 102, and the resonant inductance value of the second resonant circuit 102.

[0042] In one embodiment, the preset frequency may be specified and pre-configured; or, the control circuit 10 may receive a preset frequency sent by other circuits or devices; or, the control circuit 10 may also calculate the preset frequency based on the resonant capacitance value of the first resonant circuit 101, the resonant inductance value of the first resonant circuit 101, the resonant capacitance value of the second resonant circuit 102, and the resonant inductance value of the second resonant circuit 102.

[0043] S102: The control circuit 10 controls the second resonant circuit 102 to alternately switch the working state in each preset period corresponding to the preset frequency according to the preset frequency, so that the power battery 2 is alternately charged and discharged at the preset frequency. Each time the power battery 2 is charged, it passes through the first resonant circuit 101 and the second resonant circuit 102 at the same time, and each time it is discharged, it passes through the first resonant circuit 101 and the second resonant circuit 102 at the same time.

[0044] In one embodiment, the second resonant circuit 102 includes at least two working states, which are recorded as a first working state and a second working state. When the second resonant circuit 102 is in the first working state, the power battery 2 can be charged through the first resonant circuit 101 and the second resonant circuit 102 at the same time, or the power battery 2 can be discharged through the first resonant circuit 101 and the second resonant circuit 102 at the same time. When the second resonant circuit 102 is in the second working state, the energy storage element 110 can be charged through the first resonant circuit 101 and the second resonant circuit 102 at the same time, or the energy storage element 110 can be discharged through the first resonant circuit 101 and the second resonant circuit 102 at the same time.

[0045] Combination Figure 3 and Figure 4 It can be seen that in the heating device 1 of the power battery 2 and the control method thereof provided in this embodiment, the control circuit 10 controls the working state of the second resonant circuit 102 at a preset frequency, so that the power battery 2 is alternately charged and discharged through the first resonant circuit 101 and the second resonant circuit 102 at the same time. Since the preset frequency is obtained by the inductance and capacitance in the first resonant circuit 101 and the second resonant circuit 102 connected in parallel, the preset frequency is such as Figure 2 The resonant frequency obtained by a resonant circuit in the related technology shown is larger, so the heating device 1 of the power battery 2 and the control method thereof provided in this embodiment can provide improved charging and discharging of the power battery 2 through higher frequency control, thereby increasing the charging and discharging current of the power battery 2, thereby increasing the heat generated by the power battery per unit time, reducing the heating time required for the heating device 1 to heat the power battery 2, and thereby improving the heating efficiency of the heating device 1 for the power battery 2.

[0046] Figure 5 This is a structural schematic diagram of an embodiment of a heating device for a power battery provided in the present application, as shown in FIG. Figure 5 Shows Figure 3 A specific circuit implementation of the heating device 1 is shown.

[0047] like Figure 5The first resonant circuit 101 shown includes a resonant capacitor 111 and a parasitic inductor 20 of a power battery 2. The second resonant circuit 102 includes a resonant capacitor 111, at least one resonant inductor 112, and at least one half-bridge circuit 113 corresponding to the at least one resonant inductor. Figure 5 In the example shown, it is taken that the second resonant circuit 102 includes two resonant inductors 112a and 112b, and two half-bridge circuits 113a and 113b.

[0048] Specifically, the resonant capacitor 111 is connected in parallel between the positive electrode and the negative electrode of the power battery 2, the first end of the resonant inductor 112a is connected to the positive electrode + of the power battery 2, the second end of the resonant inductor 112a is connected to the common point za of the corresponding half-bridge circuit 113a, the bus end on the side of the upper bridge arm 113a1 of the half-bridge circuit 113a is connected to the first end of the energy storage element 110, and the bus end on the side of the lower bridge arm 113a2 of the half-bridge circuit 113a is connected to the second end of the energy storage element 110. The first end of the resonant inductor 112b is connected to the positive electrode + of the power battery 2, the second end of the resonant inductor 112b is connected to the common point zb of the corresponding half-bridge circuit 113b, the bus end on the side of the upper bridge arm 113b1 of the half-bridge circuit 113b is connected to the first end of the energy storage element 110, and the bus end on the side of the lower bridge arm 113b2 of the half-bridge circuit 113b is connected to the second end of the energy storage element 110.

[0049] The control circuit 10 is respectively connected to the control terminal ga1 of the upper bridge arm 113a1 of the half-bridge circuit 113a, the control terminal g2a of the lower bridge arm 113a2 of the half-bridge circuit 113a, the control terminal ab1 of the upper bridge arm 113b1 of the half-bridge circuit 113b and the control terminal gb2 of the lower bridge arm 113b2 of the half-bridge circuit 113b.

[0050] Then the control circuit 10 controls the working state of the second resonant circuit 102 specifically including: controlling the upper bridge arm and the lower bridge arm in the half-bridge circuit 113a and the half-bridge circuit 113b according to the preset frequency, so that the upper bridge arm and the lower bridge arm of the two half-bridge circuits are alternately turned on and off at the first target duty cycle, thereby realizing the alternating switching of the working state of the second resonant circuit 102. Among them, the upper bridge arms of all the half-bridge circuits 113 are turned on or off at the same time, and the lower bridge arms of all the half-bridge circuits 113 are turned on or off at the same time.

[0051] Figure 6 A schematic diagram of a first control signal of a control circuit provided in the present application, showing Figure 5 The diagram shown is a schematic diagram of a control signal G1 sent by the control circuit 10 to the upper bridge arm 113a1 of the half-bridge circuit 113a and the upper bridge arm 113b1 of the half-bridge circuit 113b.

[0052] Figure 7A schematic diagram of a second control signal of a control circuit provided in the present application, showing Figure 5 The shown diagram is a schematic diagram of a control signal G2 sent by the control circuit 10 to the lower bridge arm 113a2 of the half-bridge circuit 113a and the lower bridge arm 113b2 of the half-bridge circuit 113b.

[0053] Combination Figure 6 and Figure 7 Between time t1 and time t2, the control circuit 10 sends a control signal G1 to the control end ga1 of the upper bridge arm 113a1 of the half-bridge circuit 113a and the control end gb1 of the upper bridge arm 113b1 of the half-bridge circuit 113b, respectively, so that the upper bridge arm 113a1 of the half-bridge circuit 113a and the upper bridge arm 113b1 of the half-bridge circuit 113b are both turned on, and at the same time, the lower bridge arm 113a2 of the half-bridge circuit 113a and the lower bridge arm 113b2 of the half-bridge circuit 113b are both turned off.

[0054] Between time t2 and time t3, the control end ga2 of the lower bridge arm 113a2 of the half-bridge circuit 113a of the control circuit 10 and the control end gb2 of the lower bridge arm 113b2 of the half-bridge circuit 113b respectively send a control signal G2, so that the lower bridge arm 113a2 of the half-bridge circuit 113a and the lower bridge arm 113b2 of the half-bridge circuit 113b are both turned on, and at the same time, the upper bridge arm 113a1 of the half-bridge circuit 113a and the upper bridge arm 113b1 of the half-bridge circuit 113b are both turned off.

[0055] The total time length T from time t1 to time t3 is recorded as a preset period, and the reciprocal of the preset period T is the preset frequency f. In each preset period T, the first part of the time is the time when the control circuit 10 controls the upper bridge arms of all half-bridge circuits 113 to be turned on and the lower bridge arms to be turned off, and this part of the time is recorded as the second resonant circuit 102 being in the second working state. The second part of the time of each preset period T is the time when the control circuit 10 controls the upper bridge arms of all half-bridge circuits 113 to be turned off and the lower bridge arms to be turned on, and this part of the time is recorded as the second resonant circuit 102 being in the first working state.

[0056] In one embodiment, the first target duty cycle is the ratio of the time during which the control circuit 10 controls the upper bridge arms of all half-bridge circuits 113 to be turned on and the lower bridge arms to be turned off within the preset period T to the time of the entire preset period T. Figure 6 and Figure 7 Taking the first preset period T in the example, the first target duty cycle is the ratio of the time length between time t1 and time t2 to the total time length between time t1 and time t3. It can be seen that in each preset period, the upper bridge arm and the lower bridge arm of all the half-bridge circuits 113 are alternately turned on and off once, so that the working state of the second resonant circuit 102 completes the alternating switching between the second working state and the first working state once.

[0057] Figure 8 The current diagram of the power battery provided in this application through charging and discharging is shown below in combination with Figures 5 to 7 ,right Figure 8 When the second resonant circuit 102 is in different working states, the power battery 2 is specifically described by the process of alternately charging and discharging through the first resonant circuit 101 and the second resonant circuit 102.

[0058] At time t1, the upper bridge arm 113a1 of the half-bridge circuit 113a and the upper bridge arm 113b1 of the half-bridge circuit 113b are both turned on, and the lower bridge arm 113a2 of the half-bridge circuit 113a and the lower bridge arm 113b2 of the half-bridge circuit 113b are both turned off. At this time, the power battery 2, the resonant inductor 112a, the resonant inductor 112b, the upper bridge arm 113a1 of the half-bridge circuit 113a, the upper bridge arm 113b1 of the half-bridge circuit 113b and the energy storage element 110 form a loop.

[0059] Between time t1 and time t11, the current flowing through the power battery 2 is positive, and the energy storage element 110 discharges through the resonant inductor 112a, the resonant inductor 112b, the upper bridge arm 113a1 of the half-bridge circuit 113a, and the upper bridge arm 113b1 of the half-bridge circuit 113b, thereby charging the power battery 2, and at the same time charging the resonant inductor 112a, the resonant inductor 112b, and the parasitic inductor 20 inside the power battery 2. During the process a in the entire time interval, the current flowing through the power battery 2 gradually decreases from the maximum positive value Imax.

[0060] At time t1, the charge stored in the energy storage element 110 is consumed, the energy storage element 110 stops discharging, and the power battery 2, the resonant inductor 112a, the resonant inductor 112b and the parasitic inductor 20 inside the power battery 2 stop charging.

[0061] Between time t11 and time t2, the current flowing through the power battery 2 is negative, and the power battery 2 discharges through the resonant inductor 112a, the resonant inductor 112b, the upper bridge arm 113a1 of the half-bridge circuit 113a, and the upper bridge arm 113b1 of the half-bridge circuit 113b, thereby charging the energy storage element 110, and at the same time charging the resonant inductor 112a, the resonant inductor 112b, and the parasitic inductor 20 inside the power battery 2. During the process b in the entire time interval, the current flowing through the power battery 2 gradually decreases from 0 to the minimum value -Imax.

[0062] At time t2, the upper bridge arm 113a1 of the half-bridge circuit 113a and the upper bridge arm 113b1 of the half-bridge circuit 113b are both disconnected, and at the same time, the lower bridge arm 113a2 of the half-bridge circuit 113a and the lower bridge arm 113b2 of the half-bridge circuit 113b are both turned on. At this time, the power battery 2, the resonant inductor 112a, the resonant inductor 112b, the lower bridge arm 113a2 of the half-bridge circuit 113a and the lower bridge arm 113b2 of the half-bridge circuit 113b form a loop, which is equivalent to short-circuiting the power battery 2.

[0063] Between time t2 and time t21, the current flowing through the power battery 2 is negative, and the power battery 2 is discharged, thereby charging the resonant inductor 112a, the resonant inductor 112b and the parasitic inductor 20. During the entire time interval c, the current flowing through the power battery 2 gradually increases from the minimum value -Imax to 0.

[0064] Between time t21 and time t3, the current flowing through the power battery 2 is positive, and the resonant inductor 112a, the resonant inductor 112b and the parasitic inductor 20 are discharged, thereby charging the power battery 2. During the entire time interval d, the current flowing through the power battery 2 gradually increases from 0 to Imax.

[0065] In summary, it can be seen that the upper bridge arm and the lower bridge arm of the half-bridge circuit 113 are alternately turned on and off once, so that the working state of the second resonant circuit 102 completes the alternating switching between the second working state and the first working state once, and at the same time, the power battery 2 is alternately charged and discharged once. Therefore, the heating device 1 and the control method thereof provided in this embodiment can control the alternating turning on and off of the upper bridge arm and the lower bridge arm in the half-bridge circuit 113 by the control circuit, so as to realize the control of the alternating charging and discharging of the power battery 2. The control logic of the control circuit is relatively simple, which is conducive to the promotion and application of the heating device 2 and the control method thereof.

[0066] In one embodiment, a switch structure is further included between the power battery 2 and the heating device 1, and the switch structure may be a relay or the like. When the control circuit 10 determines that the heating device 1 needs to be controlled to heat the power battery 2, the switch structure may be first controlled to be turned on so that the power battery 2 is connected to the heating device 1, and then the heating device 1 is controlled. When the power battery 2 is no longer required to be heated, the control circuit 10 may control the switch structure to be turned off. Setting the switch structure may improve the safety performance of the heating device 1 and make the heating process of the entire power battery 2 more controllable and stable.

[0067] Furthermore, the present application also provides a method for calculating the current of a power battery, wherein, referring to Figure 5As shown in the circuit structure diagram. Since the first resonant circuit 101 and the second resonant circuit 102 are connected in parallel, the resonant inductance of the first resonant circuit 101 and the resonant inductance of the second resonant circuit 102 are also connected in parallel. The resonant inductance of the first resonant circuit 101 is the parasitic inductance 20, and the resonant inductance of the second resonant circuit 102 is the parallel resonant inductance 112a and the resonant inductance 112b.

[0068] Taking the control circuit 10 calculating the preset frequency as an example, the control circuit 10 first obtains the inductance value L1 of the parasitic inductance 20, the inductance value L2 of the resonant inductance 112a, the inductance value L3 of the resonant inductance 112b, and the capacitance value C of the resonant capacitor 111. Then, the inductance value of the total inductance is calculated based on the parasitic inductance 20 and the parallel resonant inductance 112a and the resonant inductance 112b. Finally, the preset frequency is obtained by calculating the square root of the product of the total inductance and the capacitance C of the resonant capacitor 111 and multiplying it by the inverse of 2π.

[0069] Fig. 9 A schematic diagram of the current value of the power battery of the heating device provided in this application, such as Fig. 9 It shows that Figure 5 In the heating device shown, when the control circuit 10 controls the second resonant circuit 102 to switch working states according to different frequencies to make the power battery 2 alternately charge and discharge, the current of the power battery 2 changes within one cycle.

[0070] like Fig. 9 As shown, when the control circuit 10 controls the second resonant circuit 102 to switch the working state according to the preset frequency f3 to make the power battery 2 alternately charge and discharge, the maximum current of the power battery 2 in one cycle can reach If3.

[0071] In contrast, when the control circuit 10 follows the resonant frequency corresponding to the first resonant circuit 101 When the second resonant circuit 102 is controlled to switch the working state so that the power battery 2 is alternately charged and discharged, the maximum current of the power battery 2 in one cycle can reach If1.

[0072] When the control circuit 10 follows the resonant frequency corresponding to the second resonant circuit 102 When the second resonant circuit 102 is controlled to switch the working state so that the power battery 2 is alternately charged and discharged, the maximum current of the power battery 2 in one cycle can reach If2.

[0073] Obviously, when the control circuit 10 controls the second resonant circuit 102 to switch the working state according to the preset frequency f3 to make the power battery 2 alternately charge and discharge, the current value of the power battery 2 in each cycle is the largest, and If3>If2>If1.

[0074] Assuming that the current value required to reach the target power value when the power battery 2 is heated is Imin, if the second resonant circuit 102 is controlled to switch the working state based on the resonant frequency of the first resonant circuit 101 or the second resonant circuit 102 so that the power battery 2 is alternately charged and discharged, in order to achieve the current value of Imin, a resonant capacitor 111 with a larger capacitance value C needs to be set in the heating device 2. Based on the same capacitance value C, a higher current value can be achieved by controlling the second resonant circuit 102 to switch the working state based on the preset frequency f3 so that the power battery 2 is alternately charged and discharged. Therefore, when the second resonant circuit 102 is controlled to switch the working state based on the preset frequency f3 so that the power battery 2 is alternately charged and discharged, the capacitance value C of the resonant capacitor 111 that needs to be set in the heating device can be smaller, and the resonant capacitor 111 with a smaller capacitance value C can reach the current value of Imin. In summary, in the heating device 2 and the control method thereof provided in the present embodiment, the current of charging and discharging the power battery 2 is maximized by calculating the preset frequency. Based on the higher current of charging and discharging the power battery 2, the heat generated per unit time by the power battery 2 is increased, thereby reducing the heating time required for the heating device 1 to heat the power battery 2, thereby improving the heating efficiency of the heating device 1 to the power battery 2. At the same time, by setting the preset frequency, the current value required for the target power value can be achieved through the resonant capacitor 111 with a smaller capacitance value C. The smaller the capacitance value, the smaller the volume of the resonant capacitor 111, and even in some cases, the setting of the external resonant inductor 112 can be omitted. Therefore, when the heating device 1 is added to the electric vehicle, the resonant inductor 111 does not need to occupy a large volume in the electric vehicle, so that the heating device 1 provided in the present embodiment also has the technical effects of smaller volume, lower cost, and easy to accommodate and install.

[0075] Furthermore, in the above embodiment, in order to determine the preset frequency f3 , the control circuit 10 first needs to obtain the inductance value of the parasitic inductance 20 of the power battery 2 .

[0076] In one embodiment, the control circuit 10 may obtain the inductance value of the parasitic inductance 20 set in advance, or the control circuit 10 receives the inductance value of the parasitic inductance sent by other devices.

[0077] In another embodiment, the control circuit 10 can detect the power battery 2 through the detection circuit 21 of the parasitic inductance 20, so as to obtain the inductance value of the parasitic inductance 20. The detection circuit 21 can be a circuit specially provided in the heating device 1; or the detection circuit 21 can also be a circuit used by the manufacturer or supplier of the power battery 2 to detect the power battery 2. In the subsequent actual operation of the power battery 2, the detection circuit 21 is not provided in the vehicle where the power battery 2 is located.

[0078] Fig.10 The schematic diagram of the structure of the parasitic inductance detection circuit provided in this application is as follows: Fig.10 The detection circuit 21 shown includes: a detection capacitor 211, a detection resistor 212, a detection switch 213, a detection control unit 214 and a circuit parameter detection unit 215. Among them, the detection capacitor 211 is connected in parallel between the positive and negative electrodes of the power battery 2, and the detection capacitor 211 has the same capacitance value and the same type as the resonant capacitor 111. The first end of the detection switch 213 is connected to the positive electrode of the power battery 2, the second end of the detection switch 213 is connected to the first end of the detection resistor 212, and the second end of the detection resistor 212 is connected to the negative electrode of the power battery 2. The type of the detection resistor 212 is a high-power type to prevent the resistor from being damaged by excessive current.

[0079] Specifically, the detection unit 214 is used to control the detection switch 213 to be alternately turned on and off, so that the power battery 2 is alternately charged and discharged through the detection resistor 212. At the same time, the circuit parameter detection unit 215 is used to detect the maximum value of the current value of the power battery 2 when the power battery 2 is alternately charged and discharged. According to the known capacitance C of the detection capacitor 211 and the resonant frequency f corresponding to the period T of the current value detected by the circuit parameter detection unit 215 , the inductance value of the parasitic inductance 20 of the power battery 2 is calculated.

[0080] In summary, in the heating device 2 and the control method thereof provided in this embodiment, a special parasitic inductance 20 detection circuit is provided for the heating device 2, so as to detect the parasitic inductance 20 of the power battery 2 with inductive characteristics, and the inductance value of the parasitic inductance 20 can be more accurately determined in a simpler and more effective way, which is beneficial to improving the accuracy of the control performed by the subsequent control circuit 10.

[0081] Fig.11 This is a flow chart of an embodiment of a control method for a heating device of a power battery provided in the present application, such as Fig.11 A method for controlling the control circuit 10 to adjust the duty cycle of the upper bridge arm and the lower bridge arm of the half-bridge circuit to be alternately turned on is shown. Figures 5 to 7 When the control circuit 10 starts to control the upper bridge arm and the lower bridge arm of the two half-bridge circuits 113 to be alternately turned on and off at the first target duty cycle, the first target duty cycle can be first set to 50%, that is, the ratio of the time length from time t1 to time t2 to the time length from time t1 to time t3 is 50%. Subsequently, the control circuit 10 can adjust the first target duty cycle according to the current value flowing through the power battery 2, thereby adjusting the magnitude of the current value flowing through the power battery 2, and then adjusting the heating power of the power battery 2, so that the heating of the power battery 2 is more uniform and controllable.

[0082] Specifically, Fig.11 The control methods shown include:

[0083] S201: The control circuit 10 determines the maximum current value of the power battery 2. The control circuit 10 may specifically determine the maximum current value of the power battery 2 according to the following example: Figure 8 The current variation curve of the power battery 2 within a period T shown is used to obtain the maximum current value Imax of the power battery.

[0084] S202: The control circuit 10 determines the heating power value of the power battery 2 according to the maximum current value determined in S201, and compares the heating power value with the target power value. The power can be calculated by the maximum current value Imax, and the target power value is the power value required to heat the power battery 2 to the target temperature.

[0085] In one embodiment, the target power value may be set in advance, or may be determined by the control circuit 10 according to the current temperature, or the control circuit 10 may receive the target power value sent by other devices.

[0086] S203: If the current heating power of the power battery 2 is less than the target power, it means that the current current value of the power battery 2 is small, so the duty cycle can be reduced, and the first target duty cycle is adjusted to a smaller second target duty cycle, and the second target duty cycle is less than 50%. Subsequently, the control circuit 10 continues to control the upper bridge arm and the lower bridge arm of the half-bridge circuit 113 to be alternately turned on and off at the second target duty cycle according to the preset frequency. Among them, the second target duty cycle is the ratio of the time during which the control circuit 10 controls the upper bridge arm of all half-bridge circuits 113 to be turned on and the lower bridge arm to be turned off within the preset period T, to the time of the entire preset period T. Since the adjusted second target duty cycle is less than Figure 6 and Figure 7 As shown in the first target duty cycle, the conduction time of the lower bridge arm of the half-bridge circuit 113 is greater than the conduction time of the upper bridge arm, thereby increasing the discharge time of the power battery 2 and reducing the discharge time of the energy storage element 110. When the power battery 2 discharges for a longer time, the current value flowing through the power battery 2 is greater, thereby increasing the maximum current value Imax flowing through the power battery 2, thereby increasing the heating power of the power battery 2, and preventing the heating device 1 from heating the power battery 2 slowly due to insufficient heating power.

[0087] S204: If the current heating power of the power battery 2 is greater than the target power, it means that the current current value of the power battery 2 is large, so the duty cycle can be increased, and the first target duty cycle is adjusted to a larger third target duty cycle, and the third target duty cycle is greater than 50%. Subsequently, the control circuit 10 continues to control the upper bridge arm and the lower bridge arm of the half-bridge circuit 113 to be alternately turned on and off at the third target duty cycle according to the preset frequency. Among them, the third target duty cycle is the ratio of the time during which the control circuit 10 controls the upper bridge arm of all half-bridge circuits 113 to be turned on and the lower bridge arm to be turned off within the preset period T, to the time of the entire preset period T. Since the adjusted third target duty cycle is greater than Figure 6 and Figure 7 As shown in the first target duty cycle, the conduction time of the upper bridge arm of the half-bridge circuit 113 is greater than the conduction time of the lower bridge arm, thereby increasing the discharge time of the energy storage element 110 and reducing the discharge time of the power battery 2. When the discharge time of the power battery 2 is shorter, the current value flowing through the power battery 2 is smaller, thereby reducing the maximum current value Imax flowing through the power battery 2, thereby increasing the heating power of the power battery 2, and preventing the heating power of the heating device 1 from being too large for the power battery 2, causing overcurrent and overheating of the equipment.

[0088] It is understandable that if the current heating power of the power battery 2 is equal to the target power, the first target duty cycle can be maintained without adjusting the first target duty cycle. In one embodiment, when the control circuit 10 controls the upper bridge arm and the lower bridge arm of the half-bridge circuit for the first time, it can be based on the first target duty cycle. Subsequently, the control circuit 10 can Fig.11 The method shown adjusts the duty cycle on which it is based at regular intervals, thereby increasing the real-time performance of the control method executed by the control circuit 10, enabling the power battery 2 to maintain the target power value for heating, thereby ensuring the stability and reliability of the heating of the power battery 2.

[0089] In one embodiment, the control circuit 10 can obtain the current temperature value of the power battery through a sensor or the like. When the temperature value is lower than the target temperature value, the control circuit 10 starts to control the heating device 1 to heat the power battery 2; when the temperature value is greater than the target temperature value, the control circuit 10 stops controlling the heating device 1 to heat the power battery 2.

[0090] In an embodiment of the present application, the heating device 1 for the power battery 2 can be used in an electric vehicle to heat the power battery 2 of the electric vehicle. At this time, the heating device 1 can be a newly added device to the electric vehicle, or the heating device 1 can also be implemented based on an existing structure in the electric vehicle.

[0091] For example, Fig.12 A schematic diagram of a specific application of the heating device provided in this application, such as Fig.12It is shown that when the heating device 1 is applied to an electric vehicle, the power circuit of the electric vehicle includes a power battery 2, a power circuit 3 and a load 4, and the power battery 2 provides energy to the load 4 through the power circuit 3. Among them, the power circuit 3 includes a direct current to direct current (DC-DC) conversion circuit 31 and other circuits 32, and the first resonant circuit 101 and the second resonant circuit 102 in the heating device 2 provided in the present application can be implemented based on the DC-DC conversion circuit 31 of the electric vehicle. Fig.12 As shown, the power battery 2 is connected to the load 4 through the first resonant circuit 101 and the second resonant circuit 102 implemented by the DC-DC conversion circuit 31 .

[0092] When the DC-DC conversion circuit 31 is used for voltage conversion, the control circuit 10 can control the DC-DC conversion circuit 31 to convert the output voltage Vin of the power battery 2 into the output voltage Vout, and provide it to other subsequent circuits for processing.

[0093] When the DC-DC conversion circuit 31 is used as the heating device 2 to heat the power battery 2, the control circuit 10 can be used according to the present application. Figure 4 The DC-DC conversion circuit 31 is controlled in a manner to charge and discharge the power battery 2 to achieve self-heating. It can be understood that at this time, the control circuit 10 controls other circuits 32 to be in a non-working state, and only controls the DC-DC conversion circuit 31 as the heating device 2 to be in a working state.

[0094] In summary, the heating device 1 for the power battery 2 provided in this embodiment can be implemented based on the existing circuit structure in the electric vehicle. Figure 1 Compared with the electric vehicle shown in the figure, there is no need to set up a special heating device 1 in the electric vehicle, and the power battery 2 can be heated by the power circuit 3. Therefore, the structure of the heating device 1 provided in this embodiment is simpler, more conducive to promotion and application, and reduces the structural complexity and manufacturing cost of the heating device 1 and the electric vehicle in which it is located.

[0095] Fig.13 A schematic diagram of another specific application of the heating device provided in this application, such as Fig.13 The number of the half-bridge circuit 113 in the heating device 1 shown is one, and the control circuit 10 controls the half-bridge circuit 113 in the same manner as described above. Figure 4 The method shown is the same and will not be described again. This embodiment can be implemented by using the simplest circuit structure as much as possible when a heating device 1 is specially provided in an electric vehicle, thereby reducing the structural complexity of the heating device 1 to a certain extent.

[0096] Fig.14 A schematic diagram of another specific application of the heating device provided in this application, such as Fig.14The number of the half-bridge circuits 113 in the heating device 1 shown is 3, and the control circuit 10 controls the three half-bridge circuits 113. Figure 4 The method shown is the same and will not be repeated here.

[0097] In other possible implementations, the number of half-bridge circuits 113 and corresponding resonant inductors 112 in the heating device 1 provided in the present application can also be set to 4, 5 or more, wherein when the number of half-bridge circuits 113 provided in the heating device 1 is greater, the total inductance of the second resonant circuit 102 is smaller, and the second resonant circuit 102 has less restriction on the current, so that the heating device 1 can provide a larger current, thereby further improving the heating effect of the heating device 1 on the power battery 2. Therefore, in some embodiments, the heating device 1 can increase the output current by providing more half-bridge circuits 113, which is relatively simple to change the overall circuit structure of the heating device 1 and is easy to achieve the purpose of increasing the output current.

[0098] In one embodiment, the present embodiment provides Fig.14 The heating device 1 shown can be implemented based on the conversion circuit of the three-phase alternating current provided in the electric vehicle. Specifically, the three half-bridge circuits and the three resonant inductors 112 in the second resonant circuit 102 of the heating device 1 can be three-phase coil windings of the motor of the electric vehicle, respectively, and each half-bridge circuit 113 and the corresponding resonant inductor 112 are implemented by one phase coil winding in the three-phase coil winding. This embodiment also does not need to add a new structure in the electric vehicle to realize the heating device 1 of the power battery 2, reducing the structural complexity and manufacturing cost of the heating device 1 and the electric vehicle in which it is located.

[0099] It is understandable that if Fig.14 The equivalent inductance of the resonant inductors 112a, 112b and 112c in the three half-bridge circuits 113 shown in FIG. 1 is connected in parallel with the parasitic inductance 20 to obtain a total inductance value L. The total inductance value L and the capacitance value C of the resonant capacitor 111 can then be substituted into the formula: The preset frequency f when the current control circuit 10 performs control is obtained. Similarly, when the heating device 2 includes N half-bridge circuits 113, based on the above calculation method, the equivalent inductance of the resonant inductors corresponding to the N half-bridge circuits 113 connected in parallel is first calculated, and then the total inductance value L of the equivalent inductance and the parasitic inductance 20 connected in parallel is calculated, and finally substituted into the formula Get the preset frequency f.

[0100] In addition, the present application also provides an experiment to verify the current of the power battery 2 when the control circuit 10 controls the second resonant circuit 102 to switch the working state according to the preset frequency f3, the resonant frequency f1 corresponding to the first resonant circuit 101 and the resonant frequency f2 corresponding to the second resonant circuit 102 to make the power battery 2 alternately charge and discharge. Among them, the current expression of the power battery 2 can be calculated by the KVL law and the KCL law. In the experiment, the inductance value L1 of the parasitic inductance 20 is 20μH, the inductance value L2 of the resonant inductor 112a is 200μH, the inductance value L3 of the resonant inductor 112b is 200μH, the capacitance value C of the resonant capacitor 111 is 40μF, the energy storage element 110 is a capacitor with a capacitance value C1=50μF, the voltage U provided by the power battery is 550V, and the resistance value Rin of the internal resistance 22 of the power battery is 0.1Ω

[0101] When the control circuit 10 controls the upper bridge arm of the half-bridge circuit 113 to be disconnected and the lower bridge arm to be turned on, the current values ​​on the resonant inductor 112a and the resonant inductor 112b can be calculated by the following formula 1.

[0102] i1=C1·e -835.27t +e -2082.4t (C2·cos(38629t)+C3·sin(38629t))

[0103] Wherein, C1, C2, C3 are constants, and t is time. Assuming that the initial current of the parasitic inductance 20 at the moment when the upper bridge arm is disconnected and the lower bridge arm is turned on is a, the initial voltage on the resonant capacitor 111 is b, and the current value on the resonant inductor 112a and the resonant inductor 112b is c, a, b and c can be used as C1, C2, C3, and then substituted into Formula 1 to obtain the change of the current in the entire half cycle from time t to time t+0.5T.

[0104] When the control circuit 10 controls the upper bridge arm of the half-bridge circuit 113 to be turned on and the lower bridge arm to be turned off, the current values ​​on the resonant inductor 112a and the resonant inductor 112b can be calculated by the following formula 2.

[0105]

[0106] Among them, C1*, C2*, C3*, C4* are constants, and t is time. Assuming that the initial current of the parasitic inductance 20 at the moment when the upper bridge arm is turned on and the lower bridge arm is turned off is a, the initial voltage on the resonant capacitor 111 is b, and the current value on the resonant inductor 112a and the resonant inductor 112b is c, a, b and c can be used as C1*, C2*, C3*, and then substituted into Formula 2 to obtain the change of the current in the half cycle from the moment t+0.5T to the moment t+T, and combined with Formula 1, the current change from the moment t to the moment t+T is obtained.

[0107] Fig.15 It is a current diagram of a power battery during charging and discharging, where: Fig.15 It shows a curve diagram of the current value variation of the power battery 2 detected when the control circuit 10 controls the second resonant circuit 102 to switch the working state according to the preset frequency f3 to make the power battery 2 alternately charge and discharge, and the maximum value can reach more than 1500A.

[0108] Fig.16 This is another current diagram of the power battery during charging and discharging, where: Fig.16 The graph shows a curve of the current value variation of the power battery 2 detected when the control circuit 10 controls the second resonant circuit 102 to switch the working state according to the resonant frequency f2 corresponding to the second resonant circuit 102 so that the power battery 2 is alternately charged and discharged, and the maximum value is about 800A.

[0109] Fig.17 This is another current diagram of the power battery during charging and discharging, where: Fig.16 It shows a curve diagram of the current value variation of the power battery 2 detected when the control circuit 10 controls the second resonant circuit 102 to switch the working state according to the resonant frequency f1 corresponding to the first resonant circuit 101 to make the power battery 2 alternately charge and discharge, and the maximum value is about 600A.

[0110] Combined with the above Figures 15 to 17 It can be seen that when the control circuit 10 controls the second resonant circuit 102 to switch the working state according to the preset frequency f3 to make the power battery 2 alternately charge and discharge, the current value that the power battery 2 can reach is the maximum, and the accuracy and authenticity of the above experimental results can be verified by calculation of Formula 1 and Formula 2.

[0111] An embodiment of the present application also provides a vehicle, which may be an electric vehicle. The vehicle includes a battery system, which includes a power battery and a heating device for the power battery as in any of the foregoing embodiments of the present application, and the heating device can be used to heat the power battery.

[0112] Furthermore, the control circuit 10 provided in the embodiment of the present application may include a hardware structure and / or a software module, and implements the above functions in the form of a hardware structure, a software module, or a hardware structure plus a software module. Whether one of the above functions is executed in the form of a hardware structure, a software module, or a hardware structure plus a software module depends on the specific application and design constraints of the technical solution.

[0113] For example, the control circuit 10 may be one or more integrated circuits configured to implement the above method or steps, such as one or more application specific integrated circuits (ASIC), or one or more microprocessors (digital signal processors, DSP), or one or more field programmable gate arrays (FPGA), etc. For another example, when the control circuit 10 is implemented in the form of a processing element scheduling program code, the processing element may be a general-purpose processor, such as a central processing unit (CPU) or other processor that can call program code. For another example, the control circuit 10 may also be implemented in the form of a system-on-a-chip (SOC).

[0114] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions may be transmitted from a website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated. The available medium may be a magnetic medium, (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid state disk, (SSD)), etc.

[0115] For example, an embodiment of the present application further provides an electronic device, including a processor and a memory; wherein the memory is used to store computer executable instructions, and the processor can execute the computer executable instructions stored in the memory. When the computer executable instructions are executed by the processor, the processor implements any method or any step in the method executed by the control circuit 10 in the aforementioned embodiment of the present application.

[0116] The present application also provides a computer-readable storage medium, which stores computer-executable instructions. When the computer-executable instructions are executed, they can be used to implement any method or any step in the method performed by the control circuit 10 in any of the aforementioned embodiments of the present application.

[0117] An embodiment of the present application also provides a chip for executing instructions, wherein the chip is used to execute any method executed by the control circuit 10 as described above in the present application or any step in the method.

[0118] An embodiment of the present application also provides a computer program product, including a computer program, which, when executed, implements any of the methods performed by the control circuit 10 as described above in the present application or any step in the method.

[0119] Those skilled in the art can understand that all or part of the steps of implementing the above-mentioned method embodiments can be completed by hardware related to program instructions. 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, disk or optical disk and other media that can store program codes.

[0120] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A control method for a heating device of a power battery, characterized in that: The heating device (1) comprises: a first resonant circuit (101) and a second resonant circuit (102), the resonant inductance of the first resonant circuit (101) being the parasitic inductance (20) of the power battery (2), and the control method comprising: Obtaining a preset frequency, wherein the preset frequency is determined according to the resonant capacitance value and the resonant inductance value of the first resonant circuit (101), and the resonant capacitance value and the resonant inductance value of the second resonant circuit (102); The second resonant circuit (102) is controlled to alternately switch working states according to the preset frequency, so that the power battery (2) is alternately charged and discharged at the preset frequency through the first resonant circuit (101) and the second resonant circuit (102).

2. The method according to claim 1, characterized in that: The first resonant circuit (101) comprises: a resonant capacitor (111) and a parasitic inductance (20) of the power battery (2); the second resonant circuit (102) comprises: the resonant capacitor (111), at least one resonant inductor (112), and at least one half-bridge circuit (113) corresponding one-to-one to the at least one resonant inductor; the heating device (1) further comprises an energy storage element (110); the resonant capacitor (111) is connected in parallel between the positive electrode and the negative electrode of the power battery (2); the first end of the resonant inductor (112) is connected to the positive electrode of the power battery (2); the second end of the resonant inductor (112) is connected to a common point of the corresponding half-bridge circuit (113); the bus terminal on the upper bridge arm side of the half-bridge circuit (113) is connected to the first end of the energy storage element (110); and the second bus terminal on the lower bridge arm side of the half-bridge circuit (113) is connected to the second end of the energy storage element (110); The step of controlling the second resonant circuit (102) to alternately switch working states according to the preset frequency comprises: According to the preset frequency, the upper bridge arm and the lower bridge arm of the at least one half-bridge circuit (113) are controlled to be alternately turned on and off at a first target duty cycle, so that the second resonant circuit (102) alternately switches its working state.

3. The method according to claim 2, characterized in that The obtaining of the preset frequency comprises: Receiving the preset frequency; Alternatively, the resonant frequency is determined according to the inductance value of the parasitic inductance (20) of the power battery (2), the inductance value of the at least one resonant inductor (112), and the capacitance value of the resonant capacitor (111).

4. The method according to claim 3, characterized in that The step of determining the resonant frequency according to the inductance value of the parasitic inductance (20) of the power battery (2), the inductance value of the at least one resonant inductor (112), and the capacitance value of the resonant capacitor (111) comprises: Obtaining the inductance value of the parasitic inductance (20), the capacitance value of the resonant capacitor (111), and the inductance value of the at least one resonant inductor (112); Obtaining an inductance value of a total inductance according to an inductance value of the parasitic inductance (20) and an inductance value of the at least one resonant inductance (112); The preset frequency is obtained by multiplying a square root of the product of the inductance value of the total inductance and the capacitance value by a constant 2π.

5. The method according to claim 4, characterized in that The obtaining of the inductance value of the parasitic inductance (20) comprises: receiving an inductance value of the parasitic inductance (20); Alternatively, the inductance value of the parasitic inductance (20) is detected by a detection circuit (21) of the parasitic inductance (20).

6. The method according to claim 5, characterized in that The detection circuit (21) comprises: A detection capacitor (211), a detection resistor (212), a detection switch (213), a detection control unit (214) and a circuit parameter detection unit (215), wherein the detection capacitor (211) is connected in parallel between the positive electrode and the negative electrode of the power battery (2), a first end of the detection switch (213) is connected to the positive electrode of the power battery (2), and a second end is connected to the first end of the detection resistor (212), and a second end of the detection resistor (212) is connected to the negative electrode of the power battery (2), the detection control unit (214) is used to control the detection switch (213) to be alternately turned on and off, so that the power battery (2) is alternately charged and discharged through the detection resistor (212), and the circuit parameter detection unit (215) is used to detect the current value of the charge and discharge of the power battery (2).

7. The method according to any one of claims 2 to 6, characterized in that: After the upper bridge arm and the lower bridge arm of the at least one half-bridge circuit (113) are controlled to be alternately turned on and off at a first target duty cycle according to the preset frequency, the method further comprises: Determining the maximum current value of the power battery (2) during charging and discharging; determining a heating power value of the power battery (2) according to the maximum current value; When the heating power value is less than the target power value for heating the power battery (2), the upper bridge arm and the lower bridge arm of the at least one half-bridge circuit (113) are controlled to be alternately turned on and off at a second target duty cycle according to the preset frequency, and the second target duty cycle is less than the first target duty cycle; When the heating power value is greater than the target power value, the upper bridge arm and the lower bridge arm of the at least one half-bridge circuit (113) are controlled to be alternately turned on and off at a third target duty cycle according to the preset frequency, and the third target duty cycle is greater than the first target duty cycle.

8. The method according to claim 7, characterized in that The number of the resonant inductor (112) and the half-bridge circuit (113) included in the first resonant circuit (101) is proportional to the maximum current value of the power battery (2) during charging and discharging.

9. A heating device for a power battery, characterized in that: include: A control circuit (10), a first resonant circuit (101) and a second resonant circuit (102), wherein the resonant inductance of the first resonant circuit (101) is the parasitic inductance (20) of the power battery (2), the control circuit (10) is connected to the second resonant circuit (102), and the control circuit (10) is configured to execute the method according to any one of claims 1 to 8.

10. A battery system, characterized in that: The invention comprises a power battery (2) and a heating device for the power battery as claimed in claim 9.

11. An electric vehicle, characterized in that: Comprising the battery system as claimed in claim 9.

12. The electric vehicle according to claim 11, characterized in that: The power battery (2) is also connected to the load (4) of the electric vehicle via a first resonant circuit (101) and a second resonant circuit (102).

13. The electric vehicle according to claim 11, characterized in that: The second resonant circuit (102) is a circuit in the load (4) of the electric vehicle.

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