Negative square wave power battery heating method and device based on driving system and vehicle

Abstract

The invention discloses a negative square wave power battery heating method and device based on a driving system and a vehicle. The method comprises the steps of receiving a heating instruction and judging whether to enter a pulse heating mode; acquiring motor rotating speed and temperature information to judge heating conditions; when the motor is static, a pulse modulation signal containing q-axis zero voltage and d-axis negative square wave voltage is generated; and the motor controller is controlled to output pulse voltage, so that the bus generates pulse current for heating the battery. A d-axis voltage waveform is formed by alternating negative square wave bands and zero level bands, and through the negative square wave type d-axis voltage, zero torque output in the heating process can be ensured, burdens of a driving system and a braking system are eliminated, and the safety of a vehicle is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electric vehicles, in particular to a negative square wave power battery heating method and device based on a driving system and a vehicle. BACKGROUND

[0002] With the popularization of new energy vehicles, people's demand for vehicle charging and discharging efficiency and endurance has promoted the wide application of power batteries. Such batteries, with shorter charging time, stronger instantaneous discharge power, and higher energy storage density and durability, have gradually become the core components in the new energy field, and their performance advantages are continuously optimizing the user's travel experience. However, in actual application scenarios, power batteries still face key technical challenges. When the ambient temperature drops below freezing point, the internal electrochemical reaction efficiency of the power battery will be significantly reduced, resulting in a sharp decrease in the release of electrical energy and affecting the endurance of the whole vehicle, which restricts the promotion of new energy vehicles in cold regions. Therefore, the industry is actively exploring power battery temperature control solutions to maintain an appropriate working temperature to ensure the stable output of the power battery system.

[0003] To solve this problem, one of the current technical solutions is to apply a high-frequency pulse current to the power battery through the driving system, thereby generating Joule heat on the internal resistance of the power battery to heat the power battery. However, this heating method also has a problem, that is, the high-frequency pulse current, even if the instruction output by the motor controller is q-axis voltage of 0, q-axis voltage is often generated during heating, which results in the generation of motor torque Te during heating, causing a burden on the driving system and brake system, and poor safety. SUMMARY

[0004] In order to overcome the above technical defects, the purpose of the present application is to provide a negative square wave power battery heating method based on a driving system, comprising the following steps: Receiving a battery heating instruction, and determining whether to enter a pulse heating mode according to the instruction.

[0005] After entering the pulse heating mode, obtaining judgment information including motor speed, motor three-phase current information, power battery temperature information and motor temperature information, and determining whether it meets the pulse heating requirements.

[0006] When the motor is in a stationary state, generating pulse modulation information, the pulse modulation information including q-axis voltage instruction and d-axis voltage instruction.

[0007] Based on the pulse modulation information, the motor controller and the motor are controlled, the pulse voltage is generated by controlling the bridge arm switch through the motor controller, the pulse voltage including the d-axis voltage of the negative square wave type and the q-axis voltage of 0, so that the pulse current is generated on the bus, and the pulse current is used to heat the power battery.

[0008] Preferably, the d-axis voltage in a wavelength cycle includes a negative square wave segment and a 0 segment.

[0009] The negative square wave segment has a beat of N1, and a switching frequency cycle of Tsw, and a length of N1*Tsw.

[0010] The 0 segment has a beat of N2, and a switching frequency cycle of Tsw, and a length of N2*Tsw.

[0011] Wherein, 1≤N1≤N2, N1 and N2 are positive integers.

[0012] Preferably, the d-axis voltage in a wavelength cycle includes a negative square wave segment and a 0 segment.

[0013] The negative square wave segment has a beat of N1, and a switching frequency cycle of Tsw2n+1, Tsw2n+1=Tsw*K2n+1. Tsw is a standard switching frequency cycle, and K2n+1 is a random factor. The negative square wave segment has a length of N1*Tsw2n+1.

[0014] The 0 segment has a beat of N2, and a switching frequency cycle of Tsw2n+2, Tsw2n+2=Tsw*K2n+2. K2n+2 is a random factor. The 0 segment has a length of N2*Tsw2n+2.

[0015] Wherein, 1≤N1≤N2, N1 and N2 are positive integers.

[0016] Preferably, the random factor K1∈[0.1, 1.9], and the random factor K2∈[0.1, 1.9].

[0017] Preferably, the product of the d-axis voltage amplitude Udn in n wavelengths and the length N1*Tsw2n+1 of the negative square wave segment is equal.

[0018] Preferably, when the pulse current on the bus is generated, the power battery heating method further includes: According to the three-phase current sampling results and the resolver angle calculation results, the bus current Idfbk is obtained through park transformation, the peak value Idp of the bus current Idfbk is monitored, and the Idp is adjusted.

[0019] Preferably, the adjustment specifically includes: An integral controller is provided, when the bus current peak value Idp is greater than the set current threshold IdpN, the integral controller is reversely integrated, the peak value of Ud is reduced to reduce Idp.

[0020] When the bus current peak value Idp is less than the set current threshold IdpN, the integral controller is positively integrated, the peak value of Ud is increased to increase Idp.

[0021] The application discloses a power battery heating device of a negative square wave of a driving system, and the device comprises: An instruction receiving module is used for receiving a battery heating instruction and judging whether to enter a pulse heating mode. A parameter obtaining module is used for obtaining judgment information including motor speed, three-phase current information of the motor, power battery temperature, motor temperature and bus current.

[0022] A control module is used for issuing an instruction to a motor controller and generating and adjusting a pulse voltage and / or a pulse current by controlling all bridge arm switches of the motor controller.

[0023] A pulse modulation module is used for generating pulse modulation information.

[0024] The application further discloses a vehicle, which comprises a motor controller, a motor and a power battery. The motor and the motor controller jointly constitute a driving system. The power battery is electrically connected with the motor controller and the motor in sequence through a bus.

[0025] The motor controller heats the power battery by adopting the pulse heating method for the power battery of the vehicle based on the driving system according to any one of the preceding embodiments.

[0026] After the above technical scheme is adopted, compared with the prior art, the following beneficial effects are obtained: 1. The d-axis voltage waveform of the negative square wave section and the 0 section are alternated. On the one hand, the power battery heating is realized by reusing the driving system of the new energy vehicle. In the motor static state, the pulse voltage is generated by the driving system composed of the motor controller and the motor, the pulse current is generated in the bus, and the Joule heat is converted by the internal resistance of the power battery. That is, an external heat source heating system does not need to be additionally arranged, the space performance of the vehicle is optimized, and the power battery can be heated by the efficient pulse voltage. On the other hand, compared with the positive and negative waveform alternation scheme in the ordinary scheme, the d-axis voltage keeps a minimum value in the whole heating process, which leads to that the motor torque is not generated or only a small motor torque is generated during the heating, the zero torque requirement of the battery heating scene is met, the burden of the driving system and the brake system is effectively reduced or even eliminated, and the safety of the whole vehicle is improved. 2. By introducing a random factor, the switch cycle is dynamically adjusted, the pulse harmonic energy can be diffused from a fixed frequency point to a wide frequency band, the high-voltage network resonance is effectively avoided, the noise is also diffused from a fixed frequency point to a wide frequency band, and the problem of large high-frequency fixed-frequency noise is effectively reduced, and the use experience of the user is improved. 3. Further, by limiting the product of the amplitude and the pulse width to be constant, the bus current can be effectively stabilized, so that the heating power can also be maintained stable on the basis of the randomized frequency. The dynamic change of the battery internal resistance is effectively adapted, and the safety problem caused by unstable heating power is prevented, so as to improve the safety performance of the whole vehicle; 4. Based on the real-time sampling of the bus current through the Park transformation, the bus current size can be controlled in real time through the integral controller, and the heating efficiency can be flexibly adjusted. Therefore, when heating, the temperature rise rate, motor temperature, power battery temperature and other parameters can be comprehensively considered to safely, effectively and stably heat the power battery, thereby effectively improving the service life of the power battery and the safety performance of the whole vehicle. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1a A circuit structure schematic diagram of an automobile is provided for the present application; Figure 1b A flowchart of a negative square wave power battery heating method is provided for the present application; Figure 2 A voltage waveform diagram of the negative square wave power battery heating method is provided for the present application; Figure 3 A pulse voltage, pulse current, bus current and torque waveform diagram of the negative square wave power battery heating method is provided for the present application; Figure 4 A voltage waveform diagram of another embodiment of the negative square wave power battery heating method is provided for the present application; Figure 5 A regulation and control block diagram of the negative square wave power battery heating method is provided for the present application; Figure 6 A regulation and control block diagram of another embodiment of the negative square wave power battery heating method is provided for the present application.

[0028] Reference signs: 100, power battery; 200, motor controller; 300, motor. DETAILED DESCRIPTION

[0029] The advantages of the present application will be further described below in combination with the drawings and specific embodiments.

[0030] The exemplary embodiments will be described in detail hereinbelow with reference to the drawings. In the following description, the same numbers in different drawings represent the same or similar elements unless otherwise represented. The embodiments described in the following exemplary embodiments do not represent all the embodiments consistent with the present disclosure. Rather, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0031] The terminology used in the disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used in the description of the disclosure and the appended claims, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0032] It should be understood that, although the terms first, second, third, etc. can be used herein to describe various information, these terms are not intended to denote a particular order or relationship between the information. These terms are used only to distinguish one from another. For example, a first information can be termed a second information, and similarly, a second information can also be termed a first information, without departing from the scope of the present disclosure. Depending on the context, the word "if' as used herein can be interpreted to mean "when" or "in response to determining" that a certain condition exists In the description of the present application, it should be understood that the terms "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0033] In the description of the present application, unless otherwise specified and limited, it should be explained that the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be mechanical connection or electrical connection, it can be the communication between the two elements, it can be direct connection or indirect connection through intermediate medium, and the specific meaning of the above terms can be understood by the person skilled in the art according to the specific circumstances.

[0034] In the subsequent description, the suffix such as "module", "component" or "unit" used to represent elements is only for the convenience of description of the present application, and has no specific meaning in itself. Therefore, "module" and "component" can be used interchangeably.

[0035] Please refer to Figure 1a , Figure 1a The circuit structure schematic diagram of the automobile provided in the present application is shown in the following figure.

[0036] To explain the scheme of the present application, the structure of the electric automobile needs to be explained first. As shown in the following figure, Figure 1aAs shown, the three-electric system of the electric vehicle mainly includes a motor controller 200, a motor 300 and a power battery 100; the motor 300 and the motor controller 200 jointly constitute a driving system; wherein the power battery 100 is electrically connected with the motor controller 200 and the motor 300 in sequence through a bus.

[0037] It should be noted that the types and specific structures of the aforementioned motor controller 200, motor 300 and power battery 100 are not limited. Exemplarily, the motor 300 can be a driving motor, a generator and a compressor, etc. The power battery 100 can be a ternary lithium battery, a lithium iron phosphate battery, etc., which are not limited in the present application.

[0038] As understood by those skilled in the art, the main execution subject of the present application is the motor controller 200. The motor controller 200 has three-phase bridge arms A, B and C, and by turning on and off the three-phase bridge arms, a high-frequency pulse current can be formed on the bus, so as to generate Joule heat through the power battery 100 and the internal resistance of the bus, and then heat the power battery 100.

[0039] The above is a principle description of the basic scheme of the present application, and the power battery pulse heating method and device provided by the present application will be specifically described below in combination with the drawings.

[0040] Obviously, to realize the aforementioned power battery pulse heating method, a control device is also needed to realize data collection and specific adjustment, etc.

[0041] Therefore, the present application also provides an automobile power battery pulse heating device based on a driving system, comprising: An instruction receiving module is configured to receive a battery heating instruction and determine whether to enter a pulse heating mode; A parameter acquisition module is configured to acquire determination information including motor speed, three-phase current information of the motor, power battery temperature, motor temperature and bus current; A control module is configured to issue an instruction to the motor controller and generate and adjust pulse voltage and / or pulse current by controlling all bridge arm switches of the motor controller; A pulse modulation module is configured to generate pulse modulation information.

[0042] The specific setting positions of the modules are not limited. For example, one or more of the above modules can be integrated in a vehicle control unit (VCU), such as a control module and a pulse modulation module. The instruction receiving module can be arranged in a motor controller. The parameter acquisition module can be arranged in a VCU, a bus, a motor controller, and a motor. The specific parameters acquired are also not limited. For example, the parameter acquisition module can be a current sensor, a voltage sensor, and a temperature sensor. Those skilled in the art can freely design according to the scheme, and the present application also does not limit this.

[0043] The above is a description of the structure of an electric vehicle and a pulse heating device for a power battery of the electric vehicle based on a driving system. Next, a pulse heating method for a power battery of the electric vehicle based on the driving system provided by the present application will be described.

[0044] Please refer to Figure 1b , Figure 1b The flowchart of the negative square wave power battery heating method provided by the present application is shown.

[0045] The present application provides a negative square wave power battery heating method based on a driving system, which comprises the following steps: Receiving a battery heating instruction, and determining whether to enter a pulse heating mode according to the instruction.

[0046] After entering the pulse heating mode, acquiring judgment information including motor speed, motor three-phase current information, power battery temperature information, and motor temperature information, and determining whether the pulse heating requirements are met.

[0047] When the motor is in a stationary state, generating pulse modulation information, the pulse modulation information including q-axis voltage instructions and d-axis voltage instructions.

[0048] Based on the pulse modulation information, the motor controller and the motor are controlled, the pulse voltage is generated by controlling the bridge arm switch through the motor controller, the pulse voltage including a d-axis voltage of a negative square wave type and a q-axis voltage of 0, so that a pulse current is generated on the bus, and the pulse current is used to heat the power battery.

[0049] Firstly, the knowledge related to q-axis and d-axis needs to be explained here. The q-axis and d-axis are based on the dq coordinate system. The dq coordinate system is a two-dimensional orthogonal coordinate system that rotates with the rotor permanent magnet. The d-axis (Direct Axis): aligns with the N pole of the permanent magnet, responsible for excitation and flux regulation (or can be understood as, the d-axis current is directly coupled with the permanent magnet flux, determines the magnetic field strength). And the q-axis (Quadrature Axis): leads the d-axis by 90° electrical angle, responsible for "torque output" (or can be understood as, the stator q-axis current directly determines the motor torque size). The rotational speed of the coordinate system is synchronized with the rotor electrical angular speed. Through the dq coordinate system, the three-electric system can be controlled more simply and intuitively.

[0050] And the application mainly aims at heating in the whole vehicle static scene, so during the heating process, we hope that the motor cannot generate torque. When the speed is 0, the voltage equation and torque equation of the dq axis can be written as follows: .

[0051] As can be understood by those skilled in the art, the equation is based on the aforementioned dq coordinate system. Wherein, Te is the electromagnetic torque, Ud is the voltage of the stator on the d-axis, Uq is the voltage of the stator on the q-axis, ω is the motor speed, unit rad / s, expected to be 0; Rs is the stator resistance, id is the current of the stator on the d-axis, iq is the current of the stator on the q-axis, Ld is the inductance of the stator winding on the d-axis, Lq is the inductance of the stator winding on the q-axis, and Ψ is the stator flux linkage (the magnetic flux linked by the current loop).

[0052] Therefore, from the above equation, when Uq=0, Iq=0 can be obtained, so that the torque Te=0. Thus, the heating of the power battery in the static state is realized. By setting the gain coefficient, the size of the pulse voltage can also be adjusted flexibly through the harmonic voltage, so that the heating speed can be adjusted.

[0053] Therefore, as described above, by using the d-axis voltage waveform of the negative square wave section and the 0 section alternately, on the one hand, the new energy vehicle driving system can realize the heating of the power battery. In the static state of the motor, the driving system composed of the motor controller and the motor generates a pulse voltage, so that the bus generates a pulse current and converts it into Joule heat by using the internal resistance of the power battery. That is, without adding an external heat source heating system, the space performance of the vehicle is optimized, and the power battery can be heated through the efficient pulse voltage. On the other hand, compared with the positive and negative waveform alternation scheme in the ordinary scheme, this waveform will make the d-axis voltage maintain a minimum value throughout the heating process, which will result in no or only a very small motor torque being generated during heating, meeting the zero torque requirement of the battery heating scene, effectively reducing or even eliminating the burden on the driving system and the brake system, and improving the safety of the whole vehicle.

[0054] The above is an explanation of the basic concept of the present application. The following will explain the specific embodiments provided by the present application based on the basic concept.

[0055] See also Figure 2-Figure 3 , Figure 2 This is the voltage waveform diagram of the negative square wave power battery heating method provided in this application; Figure 3 This is a waveform diagram of the pulse voltage, pulse current, bus current and torque of the negative square wave power battery heating method provided in this application.

[0056] like Figure 2 As shown, in a possible implementation, the d-axis voltage includes a negative square wave segment and a 0 segment within one wavelength period.

[0057] The beat of the negative square wave band is N1, the switching frequency period is Tsw, and the duration is N1×Tsw.

[0058] The beat of segment 0 is N2, the switching frequency period is Tsw, and the duration is N2×Tsw.

[0059] Wherein, 1≤N1≤N2, N1 and N2 are positive integers.

[0060] Please refer to here Figure 3 Understand. Figure 3 As shown, in a complete cycle, it can be roughly divided into 4 stages: ①: Ud ​​is negative voltage Ud1, at this time the dual inductors are charged; ②: Ud is 0, and the dual inductor starts to discharge; ③: Ud continues to remain at 0, and only one of the two inductors still has charge, and this inductor continues to discharge; ④: Ud is still 0, charging and discharging are completely completed, the current drops to 0, and waits to enter the next cycle.

[0061] Only the first stage is a negative square wave; the remaining stages 2, 3, and 4 are all zero. It should be noted that the "inductance" mentioned above refers to the three-phase motor, with phases A, B, and C, each of which has an inductor. When Ud is a negative voltage (Ud1), two inductors are charged (for example, the inductor of phases A and B, the inductor of phases A and C, or the inductor of phases B and C). Taking the inductor of phases AB as an example, when Ud is 0, the inductor of phases A and B discharges simultaneously in stage 2. Then, in stage 3, one of the inductors of phases A and B will discharge first, while the other continues to discharge. By stage 4, both inductors have discharged completely, the current drops to zero, and the next cycle begins.

[0062] like Figure 3As shown, in this way, the d-axis current Id on the bus can be effectively reduced, and Id is reduced to almost 0 throughout the process, thereby meeting the zero torque requirement of the battery heating scene.

[0063] The above is a scheme in which Ud is a fixed negative square wave. Further, the present application also provides a scheme in which Ud is a random negative square wave, thereby optimizing the high-frequency harsh noise during the heating process and further improving the user experience.

[0064] Please refer to Figure 4 , Figure 4 the voltage waveform diagram of another embodiment of the negative square wave power battery heating method provided by the present application.

[0065] As Figure 4 shown, in another possible implementation, the d-axis voltage includes a negative square wave segment and a 0 segment within one wavelength period.

[0066] The beat of the negative square wave segment is N1, the switching frequency period is Tsw2n+1, and Tsw2n+1=Tsw×K2n+1. Tsw is a standard switching frequency period, and K2n+1 is a random factor. The length of the negative square wave segment is N1×Tsw2n+1.

[0067] The beat of the 0 segment is N2, the switching frequency period is Tsw2n+2, and Tsw2n+2=Tsw×K2n+2. K2n+2 is a random factor. The length of the 0 segment is N2×Tsw2n+2.

[0068] wherein 1≤N1≤N2, and N1 and N2 are positive integers.

[0069] Further, by introducing a random factor and dynamically adjusting the switching period, the pulse harmonic energy can be spread from a fixed frequency point to a wider frequency band, effectively avoiding high-voltage network resonance, so that the noise is also spread from a fixed frequency point to a wider frequency band, thereby effectively reducing the problem of large high-frequency fixed-frequency noise and improving the user experience.

[0070] As can be understood by those skilled in the art, the random factors K1 and K2 affect the length of the negative square wave segment and the 0 segment. When the negative square wave segment is too short, the time for generating a pulse current is extremely short, which will result in poor heating effect. When the negative square wave segment is too long, the time for generating a pulse current is relatively long, and the heating current is too large. Such a drastic pulse current fluctuation will have an adverse effect on the bus, reducing its service life and heating stability.

[0071] Therefore, those skilled in the art can understand that the random factor K1 is in [0.1, 1.9], and the random factor K2 is in [0.1, 1.9]. By setting the random factors K1 and K2 to 0.1 to 1.9, the problem that the waveform has a minimum or maximum heating current in a certain period can be avoided.

[0072] Further, the product of the d-axis voltage amplitude Udn in the n wavelengths and the negative square wave segment time length N1*Tsw2n+1 is equal.

[0073] Here or can be understood that the product of the d-axis voltage amplitude Udn and the negative square wave segment time length N1*Tsw2n+1 is directly linearly related to the bus current effective value Ibat generated on the bus. The greater the product per unit time, the greater the bus current effective value Ibat. Therefore, by limiting the constant product of the amplitude and the pulse width, the heating current on the bus can be effectively maintained stable, so that on the basis of randomization frequency, the heating power can also be maintained stable. The dynamic change of the battery internal resistance is effectively adapted, and the safety problem caused by unstable heating power is prevented, so the safety performance of the whole vehicle is improved.

[0074] The above is another implementation of the d-axis voltage waveform provided by the present application. Those skilled in the art can understand that after generating the bus current to heat the power battery, a feedback control module can also be designed to adjust the heating power in real time.

[0075] Exemplarily, please refer to Figure 5 , Figure 5 The adjustment control block diagram of the negative square wave power battery heating method provided by the present application is shown.

[0076] As Figure 5 shown, in a possible implementation, after generating the pulse current on the bus, the method further includes: According to the three-phase current sampling result and the rotation angle calculation result, the feedback value idfbk of the d-axis current is obtained by park transformation, and the peak value Idp of the feedback value idfbk of the d-axis current is monitored, and Idp is adjusted.

[0077] Further, please refer to Figure 6 , Figure 6 The adjustment control block diagram of another embodiment of the negative square wave power battery heating method provided by the present application is shown.

[0078] As Figure 6 shown, in a possible implementation, the adjustment specifically includes: An integral controller is provided, and when the bus current peak value Idp is greater than the set current threshold IdpN, the integral controller is reversely integrated, so as to reduce Idp by reducing the peak value of Ud.

[0079] When the bus current peak value Idp is less than the set current threshold value IdpN, the integral controller integrates in a positive direction, thereby increasing Idp by increasing the peak value of Ud.

[0080] By acquiring real-time bus current samples based on the Park transform, the bus current can be controlled in real time through an integral controller, flexibly adjusting heating efficiency. This allows for safe, effective, and stable heating of the power battery, taking into account parameters such as the temperature rise rate, motor temperature, and power battery temperature. This ensures that the bus current peak value, Idp, is less than the set current threshold, IdpN, effectively extending the power battery life and overall vehicle safety.

[0081] It should be noted that the embodiments of the present invention have better practicability and do not impose any form of limitation on the present invention. Any technician familiar with the field may use the technical content disclosed above to change or modify it into an equivalent effective embodiment. However, any modification or equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A negative square wave power battery heating method based on a drive system, characterized in that: The following steps are involved: Receive battery heating instructions and determine whether to enter pulse heating mode according to the instructions; After entering the pulse heating mode, the system obtains information including motor speed, motor three-phase current information, power battery temperature information, and motor temperature information to determine whether the pulse heating requirements are met. When the motor is in a stationary state, pulse modulation information is generated, wherein the pulse modulation information includes a q-axis voltage command and a d-axis voltage command; The motor controller and the motor are controlled based on the pulse modulation information, and the motor controller controls the bridge arm switch to generate a pulse voltage. The pulse voltage includes a negative square wave d-axis voltage and a q-axis voltage with a value of 0, thereby generating a pulse current on the bus. The pulse current is used to heat the power battery.

2. The power battery heating method according to claim 1, characterized in that: The d-axis voltage includes a negative square wave segment and a 0 segment within one wavelength period; The negative square wave band has a beat of N1, a switching frequency period of Tsw, and a duration of N1×Tsw; The beat of segment 0 is N2, the switching frequency period is Tsw, and the duration is N2×Tsw; Wherein, 1≤N1≤N2, N1 and N2 are positive integers.

3. The power battery heating method according to claim 1, characterized in that: The d-axis voltage includes a negative square wave segment and a 0 segment within one wavelength period; The beat of the negative square wave band is N1, the switching frequency period is Tsw2n+1, and Tsw2n+1=Tsw×K2n+1; Tsw is the standard switching frequency period, and K2n+1 is a random factor; the duration of the negative square wave band is N1×Tsw2n+1; The beat of the segment 0 is N2, the switching frequency period is Tsw2n+2, Tsw2n+2=Tsw×K2n+2; K2n+2 is a random factor; the duration of the segment 0 is N2×Tsw2n+2; Wherein, 1≤N1≤N2, N1 and N2 are positive integers.

4. The power battery heating method according to claim 3, characterized in that: The random factor K1∈[0.1,1.9], and the random factor K2∈[0.1,1.9].

5. The power battery heating method according to claim 4, characterized in that: The product of the d-axis voltage amplitude Udn in the n wavelengths and the negative square wave band duration N1×Tsw2n+1 is equal.

6. The power battery heating method according to claim 1, characterized in that: After the pulse current is generated on the bus bar, the power battery heating method further includes: According to the three-phase current sampling results and the resolver angle calculation results, the bus current Idfbk is obtained through park transformation, and the peak value Idp of the bus current Idfbk is monitored and adjusted.

7. The power battery heating method according to claim 6, characterized in that: The adjustments specifically include: An integral controller is provided, and when the bus current peak value Idp is greater than a set current threshold value IdpN, the integral controller performs reverse integration to reduce the Idp by lowering the peak value of Ud; When the bus current peak value Idp is less than the set current threshold value IdpN, the integral controller performs positive integration to increase the Idp by increasing the peak value of Ud.

8. A power battery heating device based on a negative square wave of a driving system, characterized in that: The device comprises: The command receiving module is used to receive the battery heating command and determine whether to enter the pulse heating mode; The parameter acquisition module is used to obtain judgment information including motor speed, motor three-phase current information, power battery temperature, motor temperature and bus current; A control module, configured to issue instructions to the motor controller and generate and adjust a pulse voltage and / or a pulse current by controlling all bridge arm switches of the motor controller; The pulse modulation module is used to generate the pulse modulation information.

9. A vehicle, characterized in that: The vehicle includes a motor controller, a motor and a power battery; the motor and the motor controller together constitute a drive system; wherein the power battery is electrically connected to the motor controller and the motor in sequence through a busbar; The motor controller heats the power battery by adopting the automobile power battery pulse heating method based on the drive system according to any one of claims 1 to 7.

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