Battery self-heating device and vehicle

Abstract

A battery self-heating device and a vehicle. The device includes a battery self-heating circuit and a controller. The battery self-heating circuit includes a first battery group, a second battery group, a bridge arm, and a winding corresponding to the bridge arm. The negative electrode of the first battery group is connected to the positive electrode of the second battery group, and the negative electrode of the first battery group and the positive electrode of the second battery group are connected to an output terminal of the winding. The input terminal of the winding is connected to a midpoint of the bridge arm. The positive electrode of the first battery group is connected to a first bus terminal of the bridge arm. The negative electrode of the second battery group is connected to a second bus terminal of the bridge arm. The controller is configured to adjust the duty ratio of the bridge arm according to a target duty ratio range.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and the benefit of Chinese Patent Application No. 202211204372.7, filed on September 29, 2022. The entire contents of the above-referenced application are incorporated herein by reference.

[0002] The present disclosure relates to the field of battery technology, and in particular to battery self-heating devices and vehicles. [Background technology]

[0003] In the related art, new energy vehicles can undergo battery self-heating. However, the fundamental frequency during battery self-heating generates high-amplitude electromagnetic interference. Therefore, how to reduce the electromagnetic interference generated during battery self-heating is an urgent technical problem that needs to be solved. Summary of the Invention

[0004] The Summary section is provided to briefly introduce concepts of the present disclosure that are described in detail below in the Detailed Description section. The Summary section is not intended to identify key or required features of the claimed technical solution, nor is it intended to limit the scope of the claimed technical solution.

[0005] According to a first aspect, the present disclosure provides a battery self-heating device including a battery self-heating circuit and a controller, the battery self-heating circuit including a first group of batteries, a second group of batteries, a bridge arm, and a winding corresponding to the bridge arm.

[0006] The negative terminal of the first group of batteries is connected to the positive terminal of the second group of batteries. The negative terminal of the first group of batteries and the positive terminal of the second group of batteries are connected to the output terminal of the winding. The input terminal of the winding is connected to the midpoint of the bridge arm.

[0007] The positive electrodes of the first group of batteries are connected to a first busbar end of the bridge arm, and the negative electrodes of the second group of batteries are connected to a second busbar end of the bridge arm.

[0008] The controller changes the fundamental frequency of the heating current of the battery self-heating circuit within the target fundamental frequency range. Configure it to and a target duty ratio range for adjusting the duty ratio of the bridge arm in response to detecting that the battery self-heating circuit is in an operating state, the target duty ratio range being obtained according to a mapping relationship between the fundamental frequency and the duty ratio.

[0009] Optionally, the controller: Vary the fundamental frequency of the heating current within the target fundamental frequency range Configure it to For , period Within the target duty ratio range, Select and adjust the bridge arm duty cycle according to the target duty cycle. It is configured as follows.

[0010] Optionally, the controller: The fundamental frequency of the heating current is sequentially set to the second lower limit, the second upper limit, and the second lower limit. Configure and sequentially adjusting the duty ratio of the bridge arm to a first lower limit value, a first upper limit value, and a first lower limit value within a preset period according to a target duty ratio range. It is configured as follows.

[0011] The first lower limit value and the first upper limit value are obtained according to a target duty ratio range, and the second lower limit value and the second upper limit value are obtained according to a target fundamental frequency range.

[0012] Optionally, the controller: Obtaining a time domain waveform of a heating current, the time domain waveform comprising: in the time domain Change in heating current show , and obtaining performing a Fourier transform on the time domain waveform to obtain a frequency domain waveform, the frequency domain waveform reflecting changes in the heating current in the frequency domain; The duty ratio of the bridge arm is adjusted according to the noise amplitude of the frequency domain waveform. , Canada Adjusting the fundamental frequency of the thermal current It is configured to:

[0013] Optionally, the bridge arm Equipped with multiple phase bridge arms It is a multiphase bridge arm, and the windings are Multiple phase windings It is a multiphase winding ,phase Winding Each of these corresponds to one of the phase bridge arms. Each of the multiple phase windings is connected to the midpoint of a corresponding bridge arm.

[0014] Optionally, the battery self-heating circuit further comprises a first capacitor and a second capacitor; The first end of the second capacitor is connected to the second end of the first capacitor, the first end of the second capacitor and the second end of the first capacitor are connected to the output end of the winding, the second end of the second capacitor is connected to the negative electrode of the second battery group, and the first end of the first capacitor is connected to the positive electrode of the first battery group.

[0015] Optionally, the battery self-heating circuit further includes a first switch, and the first end of the second capacitor and the second end of the first capacitor are connected to the output end of the winding via the first switch.

[0016] Optionally, the battery self-heating circuit further includes a second switch, and the negative electrode of the first group of batteries and the positive electrode of the second group of batteries are connected to the output end of the winding via the second switch.

[0017] Optionally, the winding is a winding in a motor of a vehicle and the bridge arm is a bridge arm switch configured to control the motor in the vehicle.

[0018] Optionally, the battery self-heating circuit further includes a direct current (DC) charging port, wherein the output end of the winding is connected to a positive electrode of the DC charging port and the second bus end of the bridge arm is connected to a negative electrode of the DC charging port.

[0019] Optionally, the battery self-heating circuit further includes a third switch, wherein a first busbar end of the bridge arm is connected to a first end of the third switch, and a second end of the third switch is connected to a positive electrode of the DC charging port.

[0020] According to a second aspect, the present disclosure provides a vehicle including a battery self-heating device according to any of the embodiments of the first aspect.

[0021] With the above technical solution, the duty ratio of the bridge arm can change the fundamental frequency of the heating current of the battery self-heating circuit within the target fundamental frequency range. Configure it to Therefore, there is a sinusoidal heating current that changes continuously within the target fundamental frequency range. Because the current waveform of the heating current is sinusoidal, the waveform of the heating current has the same amplitude, and therefore the strength of the electromagnetic interference is distributed to other frequencies to achieve electromagnetic compatibility (EMC). composition In addition, the amplitude of electromagnetic interference within the target fundamental frequency range can also be effectively reduced.

[0022] Other features and advantages of the present disclosure are described in detail below in the Detailed Description section.

[0023] The above-described embodiments and other features, advantages, and aspects of the embodiments of the present disclosure will become more apparent with reference to the accompanying drawings and the detailed description section below. The same or similar reference numerals represent the same or similar elements throughout the accompanying drawings. It should be understood that the accompanying drawings are schematic and that components and elements are not necessarily drawn to scale. [Brief explanation of the drawings]

[0024] [Figure 1]FIG. 1 is a structural block diagram of a battery self-heating device according to an exemplary embodiment of the present disclosure. [Figure 2] FIG. 1 is a circuit diagram of a battery self-heating circuit according to an exemplary embodiment of the present disclosure. [Figure 3] FIG. 1 is a schematic diagram of current direction for timing sequence 1 according to an exemplary embodiment of the present disclosure. [Figure 4] FIG. 10 is a schematic diagram of current direction for timing sequence 2 according to an exemplary embodiment of the present disclosure. [Figure 5] FIG. 10 is a schematic diagram of current direction for timing sequence 3 according to an exemplary embodiment of the present disclosure. [Figure 6] FIG. 10 is a schematic diagram of current direction for timing sequence 4 according to an exemplary embodiment of the present disclosure. [Figure 7] FIG. 10 is a schematic diagram of a waveform of a heating current at a fixed fundamental frequency according to an exemplary embodiment of the present disclosure. [Figure 8] FIG. 10 is a schematic diagram of the variation of low frequency magnetic field amplitude at a fixed fundamental frequency of a battery self-heating circuit according to an exemplary embodiment of the present disclosure. [Figure 9] FIG. 10 is a schematic diagram of a waveform of a heating current at a fundamental frequency according to an exemplary embodiment of the present disclosure. [Figure 10] FIG. 10 is a schematic diagram of the variation of low frequency magnetic field amplitude of a battery self-heating circuit with varying fundamental frequency according to an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0025] The following will describe in more detail the embodiments of the present disclosure with reference to the accompanying drawings. Although some embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure may be implemented in various forms and should not be construed as being limited to the embodiments shown herein. On the contrary, these embodiments are provided for a more complete and complete understanding of the present disclosure. It should be understood that the accompanying drawings and embodiments of the present disclosure are merely used as examples, but do not limit the protection scope of the present disclosure.

[0026] As used herein, terms such as "include," "comprise," and variations thereof mean open-ended inclusion, i.e., "including but not limited to." The term "based on" means "based at least in part on." The terms "one embodiment" and "an embodiment" mean "at least one embodiment." The term "another embodiment" means "at least one other embodiment." The term "some embodiments" means "at least some embodiments." Relevant definitions of other terms are set forth below.

[0027] It should be noted that terms such as "first" and "second" used in this disclosure are used only to distinguish between different devices, modules, or units, and do not indicate any ordering or interdependence of the functions performed by these devices, modules, or units.

[0028] It should be noted that the terms "one" and "plurality of," as used as modifiers in this disclosure, are illustrative and not limiting. Those skilled in the art should understand such terms as "one or more," unless the context clearly dictates otherwise.

[0029] The names of messages or information exchanged between devices in embodiments of the present disclosure are for illustrative purposes only and are not intended to limit the scope of such messages or information.

[0030] With the development of technologies such as intelligent networking, electrification, and advanced driver assistance systems (ADAS), the electronic and electrical control devices of vehicles can be a source of interference for electromagnetic compatibility (EMC) problems. New energy vehicles face a more complex electromagnetic environment because they directly use electric drive systems to provide driving force. For example, by switching on and off high-power semiconductor switching devices in the electric drive system, composition The high transient voltages or currents generated emit powerful radiation and electromagnetic interference. Additionally, in self-heating solutions for electric drive systems, the fixed fundamental frequency used for battery self-heating generates high amplitude electromagnetic interference.

[0031] However, new energy vehicles have high EMC requirements due to their sensitive electronic components. In addition, high-amplitude electromagnetic interference will have a long-term adverse effect on human health. In related technologies, the amplitude of electromagnetic interference can be reduced by using the following solutions: High-quality packaging materials are used to encase interference sources inside the vehicle. Materials with strong anti-interference capabilities can effectively reduce the strength of electromagnetic interference signals during propagation and reduce the amplitude of electromagnetic interference. Filters are used to filter electromagnetic interference signals using resistors and inductors in a resistance-capacitance (RC) circuit to reduce the electromagnetic interference signals and reduce the electromagnetic interference amplitude of the electromagnetic interference signals. However, regardless of whether packaging materials or filters are used, the application costs are increased, and the electromagnetic interference amplitude within the fundamental frequency band cannot be effectively reduced.

[0032] In view of this, the present disclosure provides a method for detecting the fundamental frequency during battery self-heating. composition The present disclosure provides a battery self-heating device that can effectively reduce the amplitude of electromagnetic interference that is received by the battery. The battery heating device of the present disclosure is described in detail below.

[0033] FIG. 1 is a structural block diagram of a battery self-heating device according to an exemplary embodiment of the present disclosure. As shown in FIG. 1, the device includes a battery self-heating circuit S1 and a controller (not shown in FIG. 1). The battery self-heating circuit S1 includes a first battery group E1, a second battery group E2, a bridge arm 1, and a winding 2 corresponding to the bridge arm 1. The negative electrode of the first battery group E1 is connected to the positive electrode of the second battery group E2. The negative electrode of the first battery group E1 and the positive electrode of the second battery group E2 are connected to the output terminal of the winding 2. The input terminal of the winding 2 is connected to the midpoint of the bridge arm 1. The positive electrode of the first battery group E1 is connected to a first bus terminal of the bridge arm 1. The negative electrode of the second battery group E2 is connected to a second bus terminal of the bridge arm 1. The controller varies the fundamental frequency of the heating current of the battery self-heating circuit S1 within a target fundamental frequency range. Configure it to In order to achieve this, the battery self-heating circuit S1 is configured to adjust the duty ratio of the bridge arm 1 according to a target duty ratio range in response to detecting that the battery self-heating circuit S1 is in an operating state, and the target duty ratio range is obtained according to a mapping relationship between the fundamental frequency and the duty ratio.

[0034] In some embodiments, the controller may be further configured to control the battery self-heating circuit S1 to enter an operating state, for example, by controlling the upper bridge arm and the lower bridge arm included in the bridge arm 1 to alternately turn on or off to charge and discharge the first battery group E1 and the second battery group E2 via the winding 2, respectively. Configure it to , which may be further configured to trigger the battery self-heating circuit S1 to enter an operating state. It can be seen that the battery self-heating circuit S1 performs self-heating by interleaved oscillation of the battery current.

[0035] In some embodiments, the bridge arms may be multi-phase bridge arms, and the windings may be multi-phase windings. The multiple phase bridge arms of the multi-phase bridge arms correspond one-to-one to the multiple phase windings of the multi-phase winding, and each of the multiple phase windings is connected to the midpoint of the corresponding bridge arm, i.e., the input end of each phase wire of the winding is connected to the midpoint of the corresponding bridge arm. In the case of a multi-phase winding, the output end of the winding may be the midpoint of the output end of the phase wire of the multi-phase winding. As shown in FIG. 1, the multiple phase bridge arms may be three-phase bridge arms, and the multiple phase windings may be three-phase windings.

[0036] It should be noted that the battery self-heating circuit in this disclosure may be any self-heating circuit that charges or discharges the first and second battery groups using an oscillating current generated by the bridge arms and windings to achieve battery self-heating. The number of phases of the bridge arms and the number of phases of the windings are not limited by this disclosure. For example, the bridge arms may also be single-phase bridge arms, and the windings may be single-phase windings corresponding to the single-phase bridge arms.

[0037] In order to more clearly explain the self-heating principle of the battery self-heating circuit of the present disclosure, the battery self-heating circuit shown in FIG. 1 will be used for explanation below.

[0038] For example, the battery self-heating circuit can undergo the following four timing sequences:

[0039] Timing sequence 1: The upper bridge arm 11 of bridge arm 1 is connected and the lower bridge arm 12 of bridge arm 1 is disconnected. Current flows out from the positive electrode of the first battery group E1 and passes through the upper bridge arm 11 to charge winding 2. The charging current then flows back through the output end of the winding to the negative electrode of the first battery group E1. At this stage, the first battery group E1 discharges and charges winding 2. See Figure 3 for the current direction corresponding to timing sequence 1.

[0040] Timing sequence 2: The upper bridge arm 11 of bridge arm 1 is disconnected and the lower bridge arm 12 of bridge arm 1 is connected. Current flows out of the output end of winding 2 to charge the second battery E2 and returns to the input end of winding 2 through the lower bridge arm 12 of bridge arm 1. At this stage, winding 2 discharges and charges the second battery E2. See Figure 4 for the current direction corresponding to timing sequence 2.

[0041] By switching between timing sequence 1 and timing sequence 2, discharging of the first battery group E1 and charging of the second battery group E2 can be realized.

[0042] Timing sequence 3: The upper bridge arm 11 of bridge arm 1 is disconnected and the lower bridge arm 12 of bridge arm 1 is connected. Current flows out from the positive electrode of the second battery group E2 to charge winding 2 and back through the lower bridge arm 12 of bridge arm 1 to the negative electrode of the second battery group E2. At this stage, the second battery group E2 discharges and charges winding 2. See Figure 5 for the current direction corresponding to timing sequence 3.

[0043] Timing sequence 4: The upper bridge arm 11 of bridge arm 1 is connected and the lower bridge arm 12 of bridge arm 1 is disconnected. Current flows out from the input end of winding 2, passes through the upper bridge arm 11 of bridge arm 1, charges the first battery group E1, and returns to the output end of winding 2. At this stage, winding 2 discharges and charges the first battery group E1. See Figure 6 for the current direction corresponding to timing sequence 4.

[0044] By switching between timing sequence 3 and timing sequence 4, charging of the first battery group E1 and discharging of the second battery group E2 can be realized.

[0045] It can be seen that by switching between timing sequences 1 and 2 and between timing sequences 3 and 4, charging and discharging of the first battery group E1 and charging and discharging of the second battery group E2 can be realized. In some embodiments, the first battery group E1 and the second battery group E2 can jointly form a high-voltage power battery. The charging and discharging currents of the first battery group E1 and the second battery group E2 are interleaved, thereby further reducing battery ripple during heating due to battery current oscillation.

[0046] As shown in FIG. 2 , in some embodiments, the battery self-heating circuit may further include a first capacitor C1 and a second capacitor C2. A first end of the second capacitor C2 is connected to a second end of the first capacitor C1. A first end of the second capacitor C2 and a second end of the first capacitor C1 are connected to an output end of the winding 2. A second end of the second capacitor C2 is connected to a negative electrode of the second battery group E2. A first end of the first capacitor C1 is connected to a positive electrode of the first battery group E1. In some embodiments, the first capacitor C1 and the second capacitor C2 may each be an X capacitor, which is a capacitor for suppressing electromagnetic interference of the power supply.

[0047] By connecting two capacitors in parallel between the first battery group E1 and the second battery group E2, i.e., by connecting the first capacitor C1 and the second capacitor C2 in parallel, the carrier frequency of the self-heating circuit can be suppressed, which can further reduce EMC interference.

[0048] As shown in FIG. 2 , in some embodiments, the battery self-heating circuit may further include a first switch K1. The first end of the second capacitor C2 and the second end of the first capacitor C1 are connected to the output end of the winding 2 via the first switch K1. The arrangement of the first switch K1 may facilitate enabling and disabling of a carrier frequency suppression function of the battery self-heating circuit, and the effect of reducing electromagnetic interference in the battery self-heating circuit may be further enhanced by enabling the carrier frequency suppression function. In some embodiments, the controller may be further configured to control the first switch K1 to turn on in response to detecting that the battery self-heating circuit is in an operating state, thereby enabling the carrier frequency suppression of the battery self-heating circuit.

[0049] As shown in FIG. 2 , in some embodiments, the battery self-heating circuit may further include a second switch K2. The negative electrode of the first battery group E1 and the positive electrode of the second battery group E2 are connected to the output end of the winding 2 via the second switch K2. The arrangement of the second switch K2 may facilitate enabling or disabling the self-heating function of the battery self-heating circuit, i.e., facilitating control of the battery self-heating circuit to enter an operating state. In some embodiments, the controller may be further configured to control and turn on the second switch K2 to enable the self-heating function of the battery self-heating circuit and trigger the battery self-heating circuit to enter an operating state.

[0050] In some embodiments, winding 2 is a winding in a motor of a vehicle and bridge arm 1 is a bridge arm switch configured to control the motor in the vehicle.

[0051] As shown in FIG. 2, in some embodiments, the battery self-heating circuit further includes a direct current (DC) charging port. The output end of winding 2 is connected to the positive terminal of the DC charging port. The second bus end of bridge arm 1 is connected to the negative terminal of the DC charging port. The DC charging port arrangement allows for direct connection charging of the vehicle.

[0052] As shown in FIG. 2 , in some embodiments, the battery self-heating circuit may further include a third switch K3. The first busbar end of the bridge arm 1 is connected to a first end of the third switch K3, and the second end of the third switch K3 is connected to the positive electrode of the DC charging port. The arrangement of the third switch K3 may facilitate control of direct connection charging of the vehicle. In some embodiments, the controller may be further configured to control the first switch K1 to be off, the second switch K2 to be off, and the third switch K3 to be on to realize direct connection charging of the vehicle. When the controller detects that the vehicle requires direct connection charging, the controller may control the first switch K1 to be off, the second switch K2 to be off, and the third switch K3 to be on.

[0053] As shown in FIG. 2 , in some embodiments, the battery self-heating circuit may further include a fourth switch K4 and a fifth switch K5. The output end of winding 2 is connected to the positive electrode of the DC charging port via the fourth switch K4. The second bus end of bridge arm 1 is connected to the negative electrode of the DC charging port via the fifth switch K5. The controller may be configured to control the first switch K1 to be off, the second switch K2 to be off, the third switch K3 to be on, the fourth switch K4 to be off, and the fifth switch K5 to be on to realize direct connection charging of the vehicle.

[0054] In some embodiments, the controller may be further configured to control the first switch K1 to be off, the second switch K2 to be off, the third switch K3 to be off, the fourth switch K4 to be on, and the fifth switch K5 to be on to achieve fast charging of the vehicle. When the controller detects that the vehicle requires fast charging, the controller may control the first switch K1 to be off, the second switch K2 to be off, the third switch K3 to be off, the fourth switch K4 to be on, and the fifth switch K5 to be on.

[0055] In some embodiments, the controller may be further configured to control the first switch K1 to be off, the second switch K2 to be off, the third switch K3 to be off, the fourth switch K4 to be off, and the fifth switch K5 to be off, so that the vehicle drives normally.

[0056] As described above, the controller varies the fundamental frequency of the heating current of the battery self-heating circuit within the target fundamental frequency range. Configure it to In order to achieve this, the duty ratio of the bridge arm is adjusted according to a target duty ratio range in response to detecting that the battery self-heating circuit is in an operating state, where the target duty ratio range is obtained according to a mapping relationship between the fundamental frequency and the duty ratio. For example, the aforementioned timing sequences 1 to 4 are used as an example. If the total period of timing sequence 1 and timing sequence 2 is t1, and the total period of timing sequence 3 and timing sequence 4 is t2, the duty ratio of the bridge arm can be t1 / (t1+t2).

[0057] Because the battery self-heating circuit heats by oscillating the battery current, the oscillating current waveform during self-heating is a pulse-width modulated (PWM) waveform. The PWM waveform is the carrier wave, and the frequency of the carrier wave is the carrier frequency. Sinusoidal pulse-width modulation may be performed on the PWM wave to obtain a sinusoidal pulse sequence, where the sine wave is the base wave and the frequency of the base wave is the fundamental frequency. The pulse width may be modulated by modulating the frequency of the carrier wave, thus varying the fundamental frequency.

[0058] Frequency (e.g., carrier frequency or fundamental frequency) is related to the period, and frequency and period are inverse quantities. Pulse width and duty ratio are related to the period. Pulse width is the time occupied by the high level in one period, and duty ratio is the proportion of the high level in one period. For example, if the frequency is F and the duty ratio is P, then the pulse width is equal to (1 / F) × P. Therefore, the duty ratio is proportional to the fundamental frequency.

[0059] The target duty ratio range may be a duty ratio range required to achieve a target fundamental frequency range, and the target duty ratio range may be preset according to a mapping relationship between the fundamental frequency and the duty ratio.

[0060] In this disclosure, the duty ratio of the bridge arm is set to vary the fundamental frequency of the heating current of the battery self-heating circuit within the target fundamental frequency range. Configure it to Therefore, there is a sinusoidal heating current that changes continuously within the target frequency range. Compared with the related art solution using a fixed fundamental frequency, the current waveform in the present disclosure is sinusoidal, and the waveform of the heating current has the same amplitude, so the strength of the electromagnetic interference is distributed to other frequencies and can be reduced by electromagnetic compatibility (EMC). composition In addition, the amplitude of electromagnetic interference within the target fundamental frequency range can also be effectively reduced.

[0061] In some embodiments, the controller varies the fundamental frequency of the heating current within a target fundamental frequency range. Configure it to In some embodiments, the controller varies the fundamental frequency of the heating current within a target fundamental frequency range. Configure it to In order to achieve this, a target duty ratio may be randomly selected from a target duty ratio range within a preset period, and the duty ratios of the bridge arms may be adjusted according to the target duty ratio. The fundamental frequency of the heating current may be randomly varied by randomly selecting the target duty ratio.

[0062] In some embodiments, the controller sequentially varies the fundamental frequency of the heating current to a second lower limit, a second upper limit, and a second lower limit. Configure it to To achieve this, the bridge arm duty cycle is sequentially adjusted to a first lower limit, a first upper limit, and a first lower limit within a preset period according to a target duty ratio range, where the first lower limit and the first upper limit are obtained according to the target duty ratio range, and the second lower limit and the second upper limit are obtained according to the target fundamental frequency range. By sequentially changing the fundamental frequency to the second lower limit, the second upper limit, and the second lower limit, the fundamental frequency can be varied within one period. Accordingly, the preset period may be the period of the fundamental frequency variation.

[0063] In some embodiments, the preset period may be specifically determined according to the actual situation. For example, the preset period may be randomly selected from (0, 1) seconds. The preset period may be as short as possible to enhance the EMC suppression effect.

[0064] In some embodiments, the target fundamental frequency range may be specifically determined according to actual conditions. For example, the target fundamental frequency range may be 40 Hz to 60 Hz, the second lower limit may be 40 Hz, and the second upper limit may be 60 Hz. Accordingly, the first upper limit may be a duty ratio corresponding to a fundamental frequency of 60 Hz, and the first lower limit may be a duty ratio corresponding to a fundamental frequency of 40 Hz. For example, in the present disclosure, the fundamental frequency is changed from 40 Hz to 60 Hz and then returned to 40 Hz by adjusting the duty ratio, thereby achieving frequency variation of the fundamental wave within one period. Accordingly, the period may be a preset period.

[0065] For example, see FIG. 7. FIG. 7 is a schematic diagram of a heating current waveform at a fixed fundamental frequency. In FIG. 7, waveform 7a is a time-domain waveform of the heating current, where the X-axis of waveform 7a represents time and the Y-axis of waveform 7a represents the current magnitude. Waveform 7b is a frequency-domain waveform of the self-heating current, i.e., a frequency-discrete signal obtained by performing a Fourier transform on the time-domain waveform. According to FIG. 7, a frequency of 50 Hz corresponds to a noise amplitude of 51.5 dB. FIG. 8 is a schematic diagram of the change in low-frequency magnetic field amplitude at a fixed fundamental frequency of a battery self-heating circuit. The X-axis of the waveform represents frequency, and the Y-axis represents low-frequency magnetic field amplitude. From FIG. 4, it can be seen that when the frequency is 50 Hz, the low-frequency magnetic field amplitude is 1251.1 μT.

[0066] Figure 9 is a schematic diagram of the waveform of a heating current with a varying fundamental frequency. In Figure 9, waveform 9a is a time-domain waveform of the self-heating current, where the X-axis of waveform 9a represents time and the Y-axis of waveform 9a represents the current magnitude. Waveform 9b is a frequency-domain waveform of the self-heating current, i.e., a frequency-discrete signal obtained by performing a Fourier transform on the time-domain waveform. According to Figure 9, a frequency of 50 Hz corresponds to a noise amplitude of 21 dB. Compared to Figure 7, the varying fundamental frequency weakens the peak value corresponding to 50 Hz, making the waveform smoother and reducing the noise amplitude. Referring to Figure 10, Figure 10 is a schematic diagram of the change in low-frequency magnetic field amplitude with a varying fundamental frequency of a battery self-heating circuit. The X-axis of the waveform represents frequency, and the Y-axis represents low-frequency magnetic field amplitude. According to Figure 10, when the frequency is 50 Hz, the low-frequency magnetic field amplitude is 1120 μT. Compared to Figure 8, the fluctuating fundamental frequency weakened the low-frequency magnetic field amplitude corresponding to 50 Hz.

[0067] From Figures 7 to 10, it can be seen that by changing the fundamental frequency of the heating current of the battery self-heating circuit, the noise amplitude and low-frequency magnetic field amplitude can be significantly reduced, that is, the electromagnetic interference intensity is reduced.

[0068] In some embodiments, the controller may be configured to: obtain a time-domain waveform of the heating current, the time-domain waveform being configured to reflect changes in the heating current in the time domain; perform a Fourier transform on the time-domain waveform to obtain a frequency-domain waveform, the frequency-domain waveform being configured to reflect changes in the heating current in the frequency domain; adjust the duty ratio of the bridge arm according to the noise amplitude of the frequency-domain waveform, and adjust the fundamental frequency of the heating current accordingly. For the shapes of the time-domain waveform and the frequency-domain waveform, reference may be made to Figure 7 or Figure 9, and the details will not be described again in this specification.

[0069] For example, after acquiring the frequency-domain waveform, the controller can increase the duty cycle in response to the noise amplitude exceeding a preset threshold, thereby increasing the fundamental frequency and thereby reducing the noise amplitude. Since the controller adjusts the fundamental frequency of the heating current according to the noise amplitude of the frequency-domain waveform and adjusts the fundamental frequency based on the frequency-domain waveform, the fundamental frequency can be adjusted more accurately, thereby better suppressing EMC interference.

[0070] The present disclosure further provides a vehicle including a battery self-heating device according to any one of the above embodiments. Specific details of the vehicle in this embodiment have been described in detail in the related battery self-heating device embodiments, and will not be described in detail again herein.

[0071] Although the preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, the present disclosure is not limited to the specific details in the above embodiments. Various simple modifications can be made to the technical solutions of the present disclosure without departing from the scope of the technical concept of the present disclosure, and all such simple modifications are within the protection scope of the present disclosure.

[0072] It should also be noted that specific technical features described in specific embodiments may be combined in any suitable manner unless a contradiction arises. The various possible combinations in this disclosure are not described to avoid unnecessary repetition.

[0073] In addition, the various embodiments provided by the present disclosure may be arbitrarily combined without departing from the concept of the present disclosure, and such combinations should also be construed as being disclosed in the present disclosure. [Explanation of symbols]

[0074] S1 battery self-heating circuit 1 Bridge Arm 11 Upper Bridge Arm 12 Lower Bridge Arm 2 windings E1 First battery group E2 Second battery group C1 First capacitor C2 Second capacitor K1 First switch K2 Second switch K3 Third Switch K4 4th switch K5 5th Switch

Claims

1. A battery self-heating device comprising a battery self-heating circuit (S1) and a controller, wherein the battery self-heating circuit (S1) comprises a first group of batteries (E1), a second group of batteries (E2), a bridge arm (1), and a winding (2) corresponding to the bridge arm (1); a negative electrode of the first battery group (E1) is connected to a positive electrode of the second battery group (E2), the negative electrode of the first battery group (E1) and the positive electrode of the second battery group (E2) are connected to an output end of the winding (2), and an input end of the winding (2) is connected to a midpoint of the bridge arm (1); The positive electrode of the first battery group (E1) is connected to a first busbar end of the bridge arm (1), and the negative electrode of the second battery group (E2) is connected to a second busbar end of the bridge arm (1); the controller is configured to adjust the duty ratio of the bridge arm (1) according to a target duty ratio range in response to detecting that the battery self-heating circuit (S1) is in an operating state, in order to change the fundamental frequency of the heating current of the battery self-heating circuit (S1) within a target fundamental frequency range, and the target duty ratio range is obtained according to a mapping relationship between the fundamental frequency and the duty ratio.

2. The controller:

2. The battery self-heating device according to claim 1, wherein the battery self-heating device is configured to randomly select a target duty ratio from the target duty ratio range within a preset period of time to vary the fundamental frequency of the heating current within the target fundamental frequency range, and adjust the duty ratio of the bridge arm (1) according to the target duty ratio.

3. The controller: and sequentially adjusting the duty ratio of the bridge arm (1) to a first lower limit value, a first upper limit value, and the first lower limit value within a preset period according to the target duty ratio range, in order to sequentially change the fundamental frequency of the heating current to a second lower limit value, a second upper limit value, and the second lower limit value. It is configured as follows: The battery self-heating device according to claim 1 , wherein the first lower limit value and the first upper limit value are obtained according to the target duty ratio range, and the second lower limit value and the second upper limit value are obtained according to the target fundamental frequency range.

4. The controller: acquiring a time domain waveform of the heating current, the time domain waveform reflecting changes in the heating current in the time domain; performing a Fourier transform on the time domain waveform to obtain a frequency domain waveform, the frequency domain waveform reflecting changes in the heating current in the frequency domain; adjusting the duty ratio of the bridge arm (1) according to the noise amplitude of the frequency domain waveform, and adjusting the fundamental frequency of the heating current accordingly; The battery self-heating device according to claim 1 , configured to:

5. 5. The battery self-heating device according to claim 1, wherein the bridge arm (1) is a multi-phase bridge arm, the winding (2) is a multi-phase winding, a plurality of phase bridge arms of the multi-phase bridge arm have a one-to-one correspondence with a plurality of phase windings of the multi-phase winding, and each of the plurality of phase windings is connected to a midpoint of the corresponding bridge arm.

6. the battery self-heating circuit (S1) further comprises a first capacitor (C1) and a second capacitor (C2); 6. The battery self-heating device according to claim 1, wherein a first end of the second capacitor (C2) is connected to a second end of the first capacitor (C1), the first end of the second capacitor (C2) and the second end of the first capacitor (C1) are connected to the output end of the winding (2), the second end of the second capacitor (C2) is connected to the negative electrode of the second battery group (E2), and the first end of the first capacitor (C1) is connected to the positive electrode of the first battery group (E1).

7. 7. The battery self-heating device of claim 6, wherein the battery self-heating circuit (S1) further comprises a first switch (K1), and the first end of the second capacitor (C2) and the second end of the first capacitor (C1) are connected to the output end of the winding (2) via the first switch (K1).

8. 8. The battery self-heating device according to claim 1, wherein the battery self-heating circuit (S1) further comprises a second switch (K2), and the negative electrode of the first battery group (E1) and the positive electrode of the second battery group (E2) are connected to the output end of the winding (2) via the second switch (K2).

9. 9. The battery self-heating device according to any one of claims 1 to 8, wherein the winding (2) is a winding in a motor of a vehicle and the bridge arm (1) is a bridge arm switch configured to control the motor in the vehicle.

10. 10. The battery self-heating device according to claim 1, wherein the battery self-heating circuit (S1) further comprises a direct current (DC) charging port, the output end of the winding (2) is connected to a positive electrode of the DC charging port, and the second bus end of the bridge arm (1) is connected to a negative electrode of the DC charging port.

11. 11. The battery self-heating device according to claim 10, wherein the battery self-heating circuit (S1) further comprises a third switch (K3), the first busbar end of the bridge arm (1) is connected to a first end of the third switch (K3), and the second end of the third switch (K3) is connected to the positive electrode of the DC charging port.

12. A vehicle comprising the battery self-heating device according to any one of claims 1 to 11.

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