Battery self-heating circuit and control method thereof

Abstract

The invention relates to a battery self-heating circuit and a control method thereof, and the battery self-heating circuit controls the on-off of a bidirectional Buck-Boost converter at different time sequence nodes through a controller, so that the electric energy stored in a battery is alternately charged and discharged between the battery and an energy storage capacitor C through the bidirectional Buck-Boost converter. Therefore, sine wave heating current with controllable amplitude and frequency is generated in the battery, rapid and uniform self-heating is realized by utilizing the internal resistance of the battery, and the problems that in the prior art, the waveform of the heating current is square wave pulse and contains a large number of high-frequency harmonic waves and sudden current change, so that the heating in the battery is not uniform, local overheating is easily caused, and the aging of the battery is accelerated are solved. The current with high sine degree, low ripple wave and low harmonic wave avoids sudden current change and high-frequency harmonic wave caused by square wave pulse, so that the internal heating of the battery is more uniform, the damage risk caused by local overheating is effectively reduced, and the service life of the battery is prolonged.

Description

Technical Field

[0001] This invention relates to the field of battery heating technology, specifically to a battery self-heating circuit and its control method. Background Technology

[0002] Battery self-heating technology is a key aspect of battery thermal management, especially in low-temperature environments where battery internal resistance increases and charging / discharging performance decreases, requiring heating methods to raise its operating temperature.

[0003] Traditional battery self-heating circuits often employ simple pulsed square wave heating methods. For example, they control the energy exchange between the battery and an external resistor or inductor through a switching component, generating a pulsed current that utilizes the battery's internal resistance to generate heat. While these conventional circuits are simple in structure, they have significant limitations: the heating current waveform is a square wave pulse, containing numerous high-frequency harmonics and current abrupt changes, leading to uneven heating within the battery, easily causing localized overheating, and accelerating battery aging; simultaneously, the current ripple is large, and electromagnetic interference (EMI) is strong, making it difficult to meet the stringent electromagnetic compatibility (EMC) requirements of automotive electrical systems. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a battery self-heating circuit and its control method to solve the problem that the heating current waveform in the prior art is a square wave pulse, which contains a large number of high-frequency harmonics and current abrupt changes, resulting in uneven heating inside the battery, easy to cause local overheating, and accelerated battery aging.

[0005] According to a first aspect of the present invention, a battery self-heating circuit is provided, comprising: Energy storage capacitor C, a bidirectional Buck-Boost converter connected between energy storage capacitor C and battery, and a low-pass filter connected between bidirectional Buck-Boost converter and battery; The control terminal of the bidirectional Buck-Boost converter is connected to a controller via a drive circuit. The controller is used to control the bidirectional Buck-Boost converter to turn on and off at different timing nodes, so that the electrical energy stored in the battery is alternately charged and discharged between the battery and the energy storage capacitor C through the bidirectional Buck-Boost converter, thereby generating a sinusoidal heating current with controllable amplitude and frequency in the battery, and realizing rapid and uniform self-heating by utilizing the battery's internal resistance.

[0006] Preferably, the bidirectional Buck-Boost converter includes: The first bridge arm has a series connection of switches S1 and S2. The control terminals of switches S1 and S2 are connected to the controller. The output terminal of switch S1 and the input terminal of switch S2 are connected to form the first connection point. The second bridge arm has switches S3 and S4 connected in series. The control terminals of switches S3 and S4 are connected to the controller. The output terminal of switch S3 and the input terminal of switch S4 are connected to form a second connection point. The third bridge arm has switches S5 and S6 connected in series. The control terminals of switches S5 and S6 are connected to the controller. The output terminal of switch S5 and the input terminal of switch S6 are connected to form the third connection point.

[0007] Preferably, the low-pass filter comprises: The first inductor L1, the second inductor L2, the third inductor L3, and the filter capacitor C connected in parallel across the battery terminals. f ;in, One end of the first inductor L1 is connected to the first connection point, and the other end is connected to the filter capacitor C. f Connected; one end of the second inductor L2 is connected to the second connection point, and the other end is connected to the filter capacitor C. f Connected; one end of the third inductor L3 is connected to the third connection point, and the other end is connected to the filter capacitor C. f Connected.

[0008] According to a second aspect of the present invention, a control method for a battery self-heating circuit is provided, comprising: Generate multiple SPWM signals with different phases; The bidirectional Buck-Boost converter is controlled by the SPWM signal to switch on and off at different timing nodes, so that the electrical energy stored in the battery is alternately charged and discharged between the battery and the energy storage capacitor C through the bidirectional Buck-Boost converter, thereby generating a sinusoidal heating current with controllable amplitude and frequency in the battery, and realizing rapid and uniform self-heating by utilizing the battery's internal resistance.

[0009] Preferably, generating multiple SPWM signals with different phases includes: The high-frequency triangular carrier wave is compared with the first low-frequency sinusoidal modulation wave. If the amplitude of the first low-frequency sinusoidal modulation wave is greater than or equal to the amplitude of the high-frequency triangular carrier wave, a high level is output. If the amplitude of the first low-frequency sinusoidal modulation wave is less than the amplitude of the high-frequency triangular carrier wave, a low level is output, thereby generating a series of pulse signals with widths varying according to a sinusoidal law, which is the first SPWM signal. A high-frequency triangular carrier wave is compared with a second low-frequency sinusoidal modulated wave. If the amplitude of the second low-frequency sinusoidal modulated wave is greater than or equal to the amplitude of the high-frequency triangular carrier wave, a high level is output. If the amplitude of the second low-frequency sinusoidal modulated wave is less than the amplitude of the high-frequency triangular carrier wave, a low level is output, thereby generating a series of pulse signals with widths varying sinusoidally, which are the second SPWM signals. The second low-frequency sinusoidal modulated wave is 120° out of phase with the first low-frequency sinusoidal modulated wave. The high-frequency triangular carrier wave is compared with the third low-frequency sinusoidal modulation wave. If the amplitude of the third low-frequency sinusoidal modulation wave is greater than or equal to the amplitude of the high-frequency triangular carrier wave, a high level is output. If the amplitude of the third low-frequency sinusoidal modulation wave is less than the amplitude of the high-frequency triangular carrier wave, a low level is output, thereby generating a series of pulse signals with widths varying sinusoidally, which are the third SPWM signals. The third low-frequency sinusoidal modulation wave is 120° out of phase with the second low-frequency sinusoidal modulation wave.

[0010] Preferably, controlling the bidirectional Buck-Boost converter to turn on and off at different timing nodes via the SPWM signal includes: After inverting the polarity of the first SPWM signal, the first SPWM signal and the signal after inverting the polarity of the first SPWM signal are respectively input to the control terminals of the switching transistor S1 and the switching transistor S2. After inverting the polarity of the second SPWM signal, the inverted signals are input to the control terminals of switching transistors S3 and S4, respectively. After inverting the polarity of the third SPWM signal, the third SPWM signal and the signal after inverting the polarity of the third SPWM signal are input to the control terminals of switching transistors S5 and S6, respectively.

[0011] Preferably, the step of controlling the bidirectional Buck-Boost converter to switch on and off at different timing nodes via the SPWM signal, so that the electrical energy stored in the battery is alternately charged and discharged between the battery and the energy storage capacitor C through the bidirectional Buck-Boost converter, includes: In Buck mode, the control switch S2 is normally off; When the switch S1 is turned on, the energy storage capacitor C charges the first inductor L1 and the battery; when the switch S1 is turned off, in order to maintain the current, the induced electromotive force of the first inductor L1 reverses, forming a freewheeling circuit through the body diode of the switch S2, and continues to supply power to the battery; the controller controls the voltage transmitted to the battery side per unit time by controlling the duty cycle of the SPWM signal input to the switch S1. In Boost mode, the control switch S1 is normally off; When the switch S2 is turned on, the electrical energy stored in the battery charges the first inductor L1 and the energy storage capacitor C; when the switch S2 is turned off, in order to maintain the current, the induced electromotive force of the first inductor L1 is superimposed with the battery voltage, and charges the energy storage capacitor C through the body diode of the switch S2; the controller adjusts the output voltage by controlling the duty cycle of the SPWM signal input to the switch S2.

[0012] Preferably, the control method further includes: The controller generates three sets of complementary SPWM signals with a phase difference of 120 degrees for S1-S6. When the switches S1 and S2 on the first bridge arm of the bidirectional Buck-Boost converter are working, the switches S3 and S4 on the second bridge arm and the switches S5 and S6 on the third bridge arm also switch with the same switching frequency but different phases of the SPWM signals.

[0013] Preferably, the control method further includes: The three arms of the bidirectional Buck-Boost converter work collaboratively, with the upper and lower transistors of each arm switching complementaryly. Controlled by SPWM signals, high-frequency PWM waves are generated at the first, second, and third connection points, respectively. However, the duty cycles of these three PWM waves vary sinusoidally. After low-pass filtering, at C... f The three-phase sinusoidal voltage was thus obtained.

[0014] According to a third aspect of the present invention, an electronic device is provided, comprising: processor; Memory used to store processor-executable instructions; The processor is configured to execute the control method described above.

[0015] The technical solutions provided by the embodiments of the present invention may include the following beneficial effects: By controlling the bidirectional Buck-Boost converter to switch on and off at different timing nodes, the electrical energy stored in the battery is alternately charged and discharged between the battery and the energy storage capacitor C through the bidirectional Buck-Boost converter. This generates a sinusoidal heating current with controllable amplitude and frequency within the battery. The battery's internal resistance is used to achieve rapid and uniform self-heating, solving the problem in the prior art where the heating current waveform is a square wave pulse containing a large number of high-frequency harmonics and current abrupt changes, which leads to uneven heating inside the battery, easy local overheating, and accelerated battery aging.

[0016] The core advantage of this invention lies in achieving a technological leap from "pulse square wave heating" to "high sinusoidal heating" in self-heating mode. Through the coordinated design of a three-phase interleaved parallel structure and SPWM control, the output current waveform approximates an ideal sine wave. This high sinusoidal, low-ripple, and low-harmonic current avoids the current abrupt changes and high-frequency harmonics caused by square wave pulses, resulting in more uniform heating inside the battery. This effectively reduces the risk of damage caused by localized overheating and helps extend battery life.

[0017] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0019] Figure 1 This is a schematic diagram of a battery self-heating circuit according to an exemplary embodiment; Figure 2 This is a schematic diagram illustrating the basic principle of sinusoidal pulse width modulation (SPWM) according to an exemplary embodiment; Figure 3 This is a schematic diagram of the output waveform of sinusoidal pulse width modulation (SPWM) according to another exemplary embodiment; Figure 4 This is a schematic diagram of a sinusoidal heating signal flowing through a battery, according to an exemplary embodiment. Figure 5 This is a flowchart illustrating a control method for a battery self-heating circuit according to an exemplary embodiment. Detailed Implementation

[0020] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the invention as detailed in the appended claims. Example 1

[0021] Figure 1 This is a schematic diagram of a battery self-heating circuit according to an exemplary embodiment, such as... Figure 1 As shown, the circuit includes: Energy storage capacitor C, a bidirectional Buck-Boost converter connected between energy storage capacitor C and battery, and a low-pass filter connected between bidirectional Buck-Boost converter and battery; The control terminal of the bidirectional Buck-Boost converter is connected to a controller (not shown in the figure) via a drive circuit (not shown in the figure). The controller is used to control the bidirectional Buck-Boost converter to turn on and off at different timing nodes, so that the electrical energy stored in the battery is alternately charged and discharged between the battery and the energy storage capacitor C through the bidirectional Buck-Boost converter, thereby generating a sinusoidal heating current with controllable amplitude and frequency in the battery, and realizing rapid and uniform self-heating by utilizing the battery's internal resistance.

[0022] Preferably, the bidirectional Buck-Boost converter includes: The first bridge arm has a series connection of switches S1 and S2. The control terminals of switches S1 and S2 are connected to the controller. The output terminal of switch S1 and the input terminal of switch S2 are connected to form the first connection point. The second bridge arm has switches S3 and S4 connected in series. The control terminals of switches S3 and S4 are connected to the controller. The output terminal of switch S3 and the input terminal of switch S4 are connected to form a second connection point. The third bridge arm has switches S5 and S6 connected in series. The control terminals of switches S5 and S6 are connected to the controller. The output terminal of switch S5 and the input terminal of switch S6 are connected to form the third connection point.

[0023] Preferably, the low-pass filter comprises: The first inductor L1, the second inductor L2, the third inductor L3, and the filter capacitor C connected in parallel across the battery terminals. f ;in, One end of the first inductor L1 is connected to the first connection point, and the other end is connected to the filter capacitor C. f Connected; one end of the second inductor L2 is connected to the second connection point, and the other end is connected to the filter capacitor C. f Connected; one end of the third inductor L3 is connected to the third connection point, and the other end is connected to the filter capacitor C. f Connected.

[0024] In practice, the controller can be one or more combinations of the following: Microcontrollers, ARM processors, PLC controllers, DSP processors, FPGA controllers, CPLD controllers, etc.

[0025] In practice, the types of switching transistors include, but are not limited to: Power MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors), IGBTs (Insulated Gate Bipolar Transistors), and wide bandgap semiconductor devices (SiC MOSFETs and GaN HEMTs).

[0026] Understandably, for ripple current at switching frequencies (typically thousands to tens of kilohertz), the capacitor C... f The impedance presented is much lower than the battery's internal resistance. Therefore, the vast majority of the high-frequency pulsating current generated by the switching action occurs between S1-S6 → L1-L3 → C. f This circuit circulates within the battery without flowing into it.

[0027] Filter capacitor C f This design provides a low-impedance path for the high-frequency ripple current generated by the switching transistors S1 to S6, preventing most of the high-frequency stress from being directly applied to the battery. This design significantly reduces the battery's current and thermal stress, structurally improving the safety and reliability of the heating process.

[0028] Filter capacitor C f The presence of this ensures that the main component of the heating current is a controlled low-frequency component, while uncontrolled high-frequency switching ripple is effectively filtered out. This structurally achieves the separation and improvement of the controllability of heating power and the safety and reliability of the process.

[0029] Understandably, the purpose of battery self-heating is to provide self-heating energy solely through the battery itself, without relying on external power sources, and to raise the temperature to the target temperature using the battery self-heating device.

[0030] In this embodiment, the function of the energy storage capacitor C includes: The energy storage capacitor C actually handles the majority of the AC energy oscillations, while the battery only handles the low-ripple sinusoidal current component. The energy storage capacitor C is equivalent to a "controllable virtual load" or "energy oscillation load," and its presence significantly improves the safety and lifespan of the battery's self-heating.

[0031] The energy storage capacitor C can also absorb high-frequency harmonics: the battery terminal current ripple is small, the heating current is close to the ideal sine wave, and the harmonics and peak currents are extremely low, which improves the sinusoidal nature and waveform quality of the heating current.

[0032] Modulation ratio (m) is defined as the peak value of the modulated wave (V). m ) and carrier peak value (V c The ratio of m to V, i.e., m = V m / V c Sinusoidal pulse width modulation (SPWM) under (see [link to SPWM modulation working principle]) Figure 2As shown), the bidirectional Buck-Boost converter operates at an input voltage V dc Under fixed conditions, the amplitude of the fundamental voltage of the output voltage is completely linearly controlled by the modulation ratio m.

[0033] In this embodiment, the two switches on each bridge arm of the bidirectional Buck-Boost converter are complementary and conduct, and the fundamental voltage amplitude of the output voltage is +(m+1) / 2*V. dc and –(m+1) / 2*V dc Switching between them, at input voltage V dc When the value is fixed, the amplitude of the output voltage of the bidirectional Buck-Boost converter can be linearly adjusted by changing the modulation ratio m.

[0034] Taking the first bridge arm of the bidirectional Buck-Boost converter as an example, the working principle is explained as follows: In Buck mode, the control switch S2 is normally off; When the switch S1 is turned on, the energy storage capacitor C charges the first inductor L1 and the battery; when the switch S1 is turned off, in order to maintain the current, the induced electromotive force of the first inductor L1 reverses, forming a freewheeling circuit through the body diode of the switch S2, and continues to supply power to the battery; the controller controls the voltage transmitted to the battery side per unit time by controlling the duty cycle of the SPWM signal input to the switch S1. In Boost mode, the control switch S1 is normally off; When the switch S2 is turned on, the electrical energy stored in the battery charges the first inductor L1 and the energy storage capacitor C; when the switch S2 is turned off, in order to maintain the current, the induced electromotive force of the first inductor L1 is superimposed with the battery voltage, and charges the energy storage capacitor C through the body diode of the switch S2; the controller adjusts the output voltage by controlling the duty cycle of the SPWM signal input to the switch S2.

[0035] The controller generates three sets of complementary SPWM signals with a phase difference of 120 degrees for S1-S6. When the switches S1 and S2 on the first bridge arm of the bidirectional Buck-Boost converter are working, the switches S3 and S4 on the second bridge arm and the switches S5 and S6 on the third bridge arm also switch with the same switching frequency but different phases of the SPWM signals.

[0036] The three arms of the bidirectional Buck-Boost converter work collaboratively, with the upper and lower transistors of each arm switching complementaryly. Controlled by SPWM signals, high-frequency PWM waves are generated at the first, second, and third connection points, respectively. However, the duty cycles of these three PWM waves vary sinusoidally. After low-pass filtering, at C... f The three-phase sinusoidal voltage is thus obtained. The filtered sine wave has very high quality, such as... Figure 4 As shown.

[0037] It should be noted that the technical solution provided in this embodiment is primarily applied to electric vehicles, especially those used in cold regions. In extremely cold environments, battery activity drops drastically. This embodiment can precisely increase heating power by adjusting the SPWM modulation ratio, achieving rapid temperature rise and enabling the battery to quickly reach its optimal operating temperature range, thus ensuring the vehicle's starting performance and driving range.

[0038] In addition, battery heat is lost when driving in low-temperature environments. This system can switch to a low-power heating mode for precise temperature control, preventing the battery from affecting output power and charging efficiency due to temperature drops.

[0039] Furthermore, the internal electrical environment of electric vehicles is complex and subject to strict limitations on electromagnetic interference. The smooth output current, concentrated spectrum, and low electromagnetic interference noise of this embodiment, along with its excellent electromagnetic compatibility, make it easy to pass stringent automotive-grade standards, which is one of its core competitive advantages in in-vehicle systems.

[0040] It is understood that the technical solution provided in this embodiment controls the bidirectional Buck-Boost converter to switch on and off at different timing nodes through the controller, so that the electrical energy stored in the battery is alternately charged and discharged between the battery and the energy storage capacitor C through the bidirectional Buck-Boost converter. This generates a sinusoidal heating current with controllable amplitude and frequency in the battery, and achieves rapid and uniform self-heating by utilizing the battery's internal resistance. This solves the problem in the prior art where the heating current waveform is a square wave pulse containing a large number of high-frequency harmonics and current abrupt changes, which leads to uneven heating inside the battery, easy local overheating, and accelerated battery aging.

[0041] The core advantage of this embodiment lies in achieving a technological leap from "pulse square wave heating" to "high sine wave heating" in the self-heating mode. Through the coordinated design of a three-phase interleaved parallel structure and SPWM control, the output current waveform approximates an ideal sine wave. This high sine wave, low ripple, and low harmonic current avoids the current abrupt changes and high-frequency harmonics caused by square wave pulses, resulting in more uniform heating inside the battery. This effectively reduces the risk of damage caused by localized overheating and helps extend battery life.

[0042] Furthermore, the three-phase interleaved parallel technology cancels out the three-phase current ripples, effectively reducing the ripple amplitude of the total input and output current. This not only reduces the current stress on individual devices but also allows for the use of smaller magnetic components such as inductors and capacitors, thereby significantly improving the overall power density and conversion efficiency of the system. The smooth output current and concentrated spectrum make the system easy to filter, resulting in extremely low electromagnetic interference (EMI) noise. This advantage enables the self-heating system to easily meet the stringent electromagnetic compatibility standards of applications such as automotive electrical systems, giving it the potential for direct application in high-end electric vehicles. Example 2

[0043] Figure 5 This is a flowchart illustrating a control method for a battery self-heating circuit according to an exemplary embodiment, such as... Figure 5 As shown, the method includes: Step S11: Generate multiple SPWM signals with different phases; Step S12: Control the bidirectional Buck-Boost converter to turn on and off at different timing nodes through the SPWM signal, so that the electrical energy stored in the battery is alternately charged and discharged between the battery and the energy storage capacitor C through the bidirectional Buck-Boost converter, thereby generating a sinusoidal heating current with controllable amplitude and frequency in the battery, and realizing rapid and uniform self-heating by utilizing the battery's internal resistance.

[0044] It should be noted that the technical solution provided in this embodiment is applicable to the battery self-heating circuit shown in Embodiment 1, specifically, it is loaded into the controller of the battery self-heating circuit shown in Embodiment 1.

[0045] In practical application, see Figure 3 The generation of multiple SPWM signals with different phases includes: The high-frequency triangular carrier wave is modulated by the first low-frequency sine wave (see...). Figure 3 The signal is compared with a black sine wave signal. If the amplitude of the first low-frequency sine modulated wave is greater than or equal to the amplitude of the high-frequency triangular carrier wave, a high level is output. If the amplitude of the first low-frequency sine modulated wave is less than the amplitude of the high-frequency triangular carrier wave, a low level is output, thereby generating a series of pulse signals with widths varying according to a sine law, which is the first SPWM signal. The high-frequency triangular carrier wave is modulated with a second low-frequency sine wave (see...). Figure 3The signal is compared with the red sine wave signal. If the amplitude of the second low-frequency sine modulated wave is greater than or equal to the amplitude of the high-frequency triangular carrier wave, a high level is output. If the amplitude of the second low-frequency sine modulated wave is less than the amplitude of the high-frequency triangular carrier wave, a low level is output. This generates a series of pulse signals with widths varying sinusoidally, which are the second SPWM signals. The second low-frequency sine modulated wave is 120° out of phase with the first low-frequency sine modulated wave. The high-frequency triangular carrier wave is modulated with a third low-frequency sine wave (see...). Figure 3 The signal is compared with the blue sine wave signal. If the amplitude of the third low-frequency sine modulated wave is greater than or equal to the amplitude of the high-frequency triangular carrier wave, a high level is output. If the amplitude of the third low-frequency sine modulated wave is less than the amplitude of the high-frequency triangular carrier wave, a low level is output. This generates a series of pulse signals with widths varying sinusoidally, which are the third SPWM signals. The third low-frequency sine modulated wave is 120° out of phase with the second low-frequency sine modulated wave.

[0046] In practical application, controlling the on / off state of the bidirectional Buck-Boost converter at different timing nodes via the SPWM signal includes: After inverting the polarity of the first SPWM signal, the first SPWM signal and the signal after inverting the polarity of the first SPWM signal are respectively input to the control terminals of the switching transistor S1 and the switching transistor S2. After inverting the polarity of the second SPWM signal, the inverted signals are input to the control terminals of switching transistors S3 and S4, respectively. After inverting the polarity of the third SPWM signal, the third SPWM signal and the signal after inverting the polarity of the third SPWM signal are input to the control terminals of switching transistors S5 and S6, respectively.

[0047] In practical application, controlling the bidirectional Buck-Boost converter to switch on and off at different timing nodes via the SPWM signal, so that the electrical energy stored in the battery is alternately charged and discharged between the battery and the energy storage capacitor C through the bidirectional Buck-Boost converter, includes: In Buck mode, the control switch S2 is normally off; When the switch S1 is turned on, the energy storage capacitor C charges the first inductor L1 and the battery; when the switch S1 is turned off, in order to maintain the current, the induced electromotive force of the first inductor L1 reverses, forming a freewheeling circuit through the body diode of the switch S2, and continues to supply power to the battery; the controller controls the voltage transmitted to the battery side per unit time by controlling the duty cycle of the SPWM signal input to the switch S1. In Boost mode, the control switch S1 is normally off; When the switch S2 is turned on, the electrical energy stored in the battery charges the first inductor L1 and the energy storage capacitor C; when the switch S2 is turned off, in order to maintain the current, the induced electromotive force of the first inductor L1 is superimposed with the battery voltage, and charges the energy storage capacitor C through the body diode of the switch S2; the controller adjusts the output voltage by controlling the duty cycle of the SPWM signal input to the switch S2.

[0048] In practice, the control method further includes: The controller generates three sets of complementary SPWM signals with a phase difference of 120 degrees for S1-S6. When the switches S1 and S2 on the first bridge arm of the bidirectional Buck-Boost converter are working, the switches S3 and S4 on the second bridge arm and the switches S5 and S6 on the third bridge arm also switch with the same switching frequency but different phases of the SPWM signals.

[0049] In practice, the control method further includes: The three arms of the bidirectional Buck-Boost converter work collaboratively, with the upper and lower transistors of each arm switching complementaryly. Controlled by SPWM signals, high-frequency PWM waves are generated at the first, second, and third connection points, respectively. However, the duty cycles of these three PWM waves vary sinusoidally. After low-pass filtering, at C... f The three-phase sinusoidal voltage is thus obtained. The filtered sine wave has very high quality, such as... Figure 4 As shown.

[0050] It is understood that the technical solution provided in this embodiment controls the bidirectional Buck-Boost converter to switch on and off at different timing nodes through the controller, so that the electrical energy stored in the battery is alternately charged and discharged between the battery and the energy storage capacitor C through the bidirectional Buck-Boost converter. This generates a sinusoidal heating current with controllable amplitude and frequency in the battery, and achieves rapid and uniform self-heating by utilizing the battery's internal resistance. This solves the problem in the prior art where the heating current waveform is a square wave pulse containing a large number of high-frequency harmonics and current abrupt changes, which leads to uneven heating inside the battery, easy local overheating, and accelerated battery aging.

[0051] The core advantage of this embodiment lies in achieving a technological leap from "pulse square wave heating" to "high sine wave heating" in the self-heating mode. Through the coordinated design of a three-phase interleaved parallel structure and SPWM control, the output current waveform approximates an ideal sine wave. This high sine wave, low ripple, and low harmonic current avoids the current abrupt changes and high-frequency harmonics caused by square wave pulses, resulting in more uniform heating inside the battery. This effectively reduces the risk of damage caused by localized overheating and helps extend battery life.

[0052] Furthermore, the three-phase interleaved parallel technology cancels out the three-phase current ripples, effectively reducing the ripple amplitude of the total input and output current. This not only reduces the current stress on individual devices but also allows for the use of smaller magnetic components such as inductors and capacitors, thereby significantly improving the overall power density and conversion efficiency of the system. The smooth output current and concentrated spectrum make the system easy to filter, resulting in extremely low electromagnetic interference (EMI) noise. This advantage enables the self-heating system to easily meet the stringent electromagnetic compatibility standards of applications such as automotive electrical systems, giving it the potential for direct application in high-end electric vehicles. Example 3

[0053] An electronic device according to an exemplary embodiment includes: processor; Memory used to store processor-executable instructions; The processor is configured to execute the control method described above.

[0054] It is understood that the technical solution provided in this embodiment controls the bidirectional Buck-Boost converter to switch on and off at different timing nodes through the controller, so that the electrical energy stored in the battery is alternately charged and discharged between the battery and the energy storage capacitor C through the bidirectional Buck-Boost converter. This generates a sinusoidal heating current with controllable amplitude and frequency in the battery, and achieves rapid and uniform self-heating by utilizing the battery's internal resistance. This solves the problem in the prior art where the heating current waveform is a square wave pulse containing a large number of high-frequency harmonics and current abrupt changes, which leads to uneven heating inside the battery, easy local overheating, and accelerated battery aging.

[0055] It is understood that the same or similar parts in the above embodiments can be referred to each other, and the contents not described in detail in some embodiments can be referred to the same or similar contents in other embodiments.

[0056] It should be noted that in the description of this invention, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means at least two.

[0057] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of the invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as will be understood by those skilled in the art to which embodiments of the invention pertain.

[0058] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0059] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0060] Furthermore, the functional units in the various embodiments of the present invention can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0061] The storage media mentioned above can be read-only memory, disk, or optical disk, etc.

[0062] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0063] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A battery self-heating circuit, characterized in that, include: Energy storage capacitor C, a bidirectional Buck-Boost converter connected between energy storage capacitor C and battery, and a low-pass filter connected between bidirectional Buck-Boost converter and battery; The control terminal of the bidirectional Buck-Boost converter is connected to a controller via a drive circuit. The controller is used to control the bidirectional Buck-Boost converter to turn on and off at different timing nodes, so that the electrical energy stored in the battery is alternately charged and discharged between the battery and the energy storage capacitor C through the bidirectional Buck-Boost converter, thereby generating a sinusoidal heating current with controllable amplitude and frequency in the battery, and realizing rapid and uniform self-heating by utilizing the battery's internal resistance.

2. The battery self-heating circuit according to claim 1, characterized in that, The bidirectional Buck-Boost converter includes: The first bridge arm has a series connection of switches S1 and S2. The control terminals of switches S1 and S2 are connected to the controller. The output terminal of switch S1 and the input terminal of switch S2 are connected to form the first connection point. The second bridge arm has switches S3 and S4 connected in series. The control terminals of switches S3 and S4 are connected to the controller. The output terminal of switch S3 and the input terminal of switch S4 are connected to form a second connection point. The third bridge arm has switches S5 and S6 connected in series. The control terminals of switches S5 and S6 are connected to the controller. The output terminal of switch S5 and the input terminal of switch S6 are connected to form the third connection point.

3. The battery self-heating circuit according to claim 2, characterized in that, The low-pass filter includes: The first inductor L1, the second inductor L2, the third inductor L3, and the filter capacitor C connected in parallel across the battery terminals. f ;in, One end of the first inductor L1 is connected to the first connection point, and the other end is connected to the filter capacitor C. f Connected; one end of the second inductor L2 is connected to the second connection point, and the other end is connected to the filter capacitor C. f Connected; one end of the third inductor L3 is connected to the third connection point, and the other end is connected to the filter capacitor C. f Connected.

4. A control method for a battery self-heating circuit, characterized in that, include: Generate multiple SPWM signals with different phases; The bidirectional Buck-Boost converter is controlled by the SPWM signal to switch on and off at different timing nodes, so that the electrical energy stored in the battery is alternately charged and discharged between the battery and the energy storage capacitor C through the bidirectional Buck-Boost converter, thereby generating a sinusoidal heating current with controllable amplitude and frequency in the battery, and realizing rapid and uniform self-heating by utilizing the battery's internal resistance.

5. The control method according to claim 4, characterized in that, The generation of multiple SPWM signals with different phases includes: The high-frequency triangular carrier wave is compared with the first low-frequency sinusoidal modulation wave. If the amplitude of the first low-frequency sinusoidal modulation wave is greater than or equal to the amplitude of the high-frequency triangular carrier wave, a high level is output. If the amplitude of the first low-frequency sinusoidal modulation wave is less than the amplitude of the high-frequency triangular carrier wave, a low level is output, thereby generating a series of pulse signals with widths varying according to a sinusoidal law, which is the first SPWM signal. A high-frequency triangular carrier wave is compared with a second low-frequency sinusoidal modulated wave. If the amplitude of the second low-frequency sinusoidal modulated wave is greater than or equal to the amplitude of the high-frequency triangular carrier wave, a high level is output. If the amplitude of the second low-frequency sinusoidal modulated wave is less than the amplitude of the high-frequency triangular carrier wave, a low level is output, thereby generating a series of pulse signals with widths varying sinusoidally, which are the second SPWM signals. The second low-frequency sinusoidal modulated wave is 120° out of phase with the first low-frequency sinusoidal modulated wave. The high-frequency triangular carrier wave is compared with the third low-frequency sinusoidal modulation wave. If the amplitude of the third low-frequency sinusoidal modulation wave is greater than or equal to the amplitude of the high-frequency triangular carrier wave, a high level is output. If the amplitude of the third low-frequency sinusoidal modulation wave is less than the amplitude of the high-frequency triangular carrier wave, a low level is output, thereby generating a series of pulse signals with widths varying sinusoidally, which are the third SPWM signals. The third low-frequency sinusoidal modulation wave is 120° out of phase with the second low-frequency sinusoidal modulation wave.

6. The control method according to claim 5, characterized in that, The control of the bidirectional Buck-Boost converter on / off at different timing nodes via the SPWM signal includes: After inverting the polarity of the first SPWM signal, the first SPWM signal and the signal after inverting the polarity of the first SPWM signal are respectively input to the control terminals of the switching transistor S1 and the switching transistor S2. After inverting the polarity of the second SPWM signal, the inverted signals are input to the control terminals of switching transistors S3 and S4, respectively. After inverting the polarity of the third SPWM signal, the third SPWM signal and the signal after inverting the polarity of the third SPWM signal are input to the control terminals of switching transistors S5 and S6, respectively.

7. The control method according to claim 6, characterized in that, The step of controlling the bidirectional Buck-Boost converter to switch on and off at different timing nodes via the SPWM signal, so that the electrical energy stored in the battery is alternately charged and discharged between the battery and the energy storage capacitor C through the bidirectional Buck-Boost converter, includes: In Buck mode, the control switch S2 is normally off; When the switch S1 is turned on, the energy storage capacitor C charges the first inductor L1 and the battery; when the switch S1 is turned off, in order to maintain the current, the induced electromotive force of the first inductor L1 reverses, forming a freewheeling circuit through the body diode of the switch S2, and continues to supply power to the battery; the controller controls the voltage transmitted to the battery side per unit time by controlling the duty cycle of the SPWM signal input to the switch S1. In Boost mode, the control switch S1 is normally off; When the switch S2 is turned on, the electrical energy stored in the battery charges the first inductor L1 and the energy storage capacitor C; when the switch S2 is turned off, in order to maintain the current, the induced electromotive force of the first inductor L1 is superimposed with the battery voltage, and charges the energy storage capacitor C through the body diode of the switch S2; the controller adjusts the output voltage by controlling the duty cycle of the SPWM signal input to the switch S2.

8. The control method according to claim 7, characterized in that, Also includes: The controller generates three sets of complementary SPWM signals with a phase difference of 120 degrees for S1-S6. When the switches S1 and S2 on the first bridge arm of the bidirectional Buck-Boost converter are working, the switches S3 and S4 on the second bridge arm and the switches S5 and S6 on the third bridge arm also switch with the same switching frequency but different phases of the SPWM signals.

9. The control method according to claim 8, characterized in that, Also includes: The three arms of the bidirectional Buck-Boost converter work collaboratively, with the upper and lower transistors of each arm switching complementaryly. Controlled by SPWM signals, high-frequency PWM waves are generated at the first, second, and third connection points, respectively. However, the duty cycles of these three PWM waves vary sinusoidally. After low-pass filtering, at C... f The three-phase sinusoidal voltage was thus obtained.

10. An electronic device characterized in that, include: processor; Memory used to store processor-executable instructions; The processor is configured to execute the control method according to any one of claims 4 to 9.

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