Motor controller and powertrain

Abstract

Provided in the present application are a motor controller and a powertrain. The motor controller comprises an inverter circuit, the inverter circuit comprising three-phase switching transistor bridge arms; the bridge arm midpoint of each switching transistor bridge arm is used for connecting to a winding of a phase of a driving motor, and the bridge arm midpoints of the three-phase switching transistor bridge arms of the inverter circuit are used for outputting a three-phase current to the windings of the driving motor, the frequencies of the current of each phase of the three-phase current being different from each other in any two adjacent periods. Since the frequencies of the current of each phase are different from each other in any two adjacent periods, the frequencies of the current of each phase flowing through the windings of the driving motor are different from each other, such that vibration frequencies generated by each winding under the action of the phase current are different from each other. Thus, noise energy generated by vibration can be dispersed within a relatively wide frequency range, thus reducing noise generated by heating a power battery so as to provide better user experience.

Description

Motor controller and powertrain

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on July 31, 2023, with application number 202310957910.8 and invention name “A motor controller, powertrain and electric vehicle”; this application claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on November 8, 2023, with application number 202311487424.0 and invention name “Motor controller, powertrain and electric vehicle”, all contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of battery heating, and in particular to a motor controller and a powertrain. Background Art

[0004] Electric vehicles experience a sharp drop in their battery's charge and discharge capacity in low-temperature environments, necessitating heating to maintain proper operation. Currently, common heating methods include positive temperature coefficient ceramic heating (PTC) and active motor heating. These methods all heat the battery through a water heating circuit, resulting in slow heating rates and a negative impact on the user experience.

[0005] Alternatively, high-frequency pulse heating can be used to heat the power battery. This involves the powertrain performing high-frequency AC charging and discharging of the power battery, thereby utilizing the heat generated by the battery's internal resistance to heat the battery. Pulsed AC power is achieved by injecting a high-frequency voltage. This high-frequency voltage, acting on the motor windings, generates a high-frequency magnetic field consistent with the injected frequency. At this point, the motor acts like an acoustic device, and the motor windings vibrate under the influence of the high-frequency signal, generating noise. Because the injected signal has a single, fixed frequency, the generated noise is sharp and piercing. Therefore, it is necessary to reduce noise during the heating process to optimize the user experience.

[0006] Summary of the Invention

[0007] High-frequency pulse heating as a heating method for power batteries is gaining increasing attention. The specific process of high-frequency pulse heating of power batteries includes: the motor controller bridge arm circuit generates high-frequency pulse alternating current, and when the high-frequency pulse alternating current passes through the power battery, it generates heat on the internal resistance of the power battery and thus heats the power battery. The high-frequency pulse alternating current generated by the winding of the drive motor will change rapidly in a very short period of time. This rapidly changing current will generate a changing electromagnetic field on the winding, which will cause high-frequency vibrations in the winding itself. The high-frequency vibration will cause various parts of the winding to vibrate with a small amplitude. At this time, the drive motor generates noise similar to an acoustic device, and since the frequency of the high-frequency voltage signal is fixed, the noise finally generated also has a fixed frequency. If this frequency is within the frequency range that can be heard by the human ear, it will be perceived as a sharp and harsh sound, resulting in a poor user experience. In order to solve this problem, the present application provides a motor controller and a powertrain.

[0008] In a first aspect, the present application provides a motor controller, which includes an inverter circuit, which includes a three-phase switch tube bridge arm. The midpoint of each switch tube bridge arm is used to connect a phase winding of a drive motor, and the midpoint of the three-phase switch tube bridge arm of the inverter circuit is used to output a three-phase current to the winding of the drive motor. The frequency of each phase of the three-phase current is different in any two adjacent cycles.

[0009] Because the frequency of each phase current is different in any two adjacent cycles, the frequency of each phase current flowing through the drive motor windings is also different. Consequently, the vibration frequency generated by each winding under the influence of the rapidly changing current is also different. Therefore, if the frequency in any two adjacent cycles is different, the noise generated by the drive motor windings in the two adjacent cycles will also have at least two different frequencies. Since each cycle is very short, the noise energy generated by the vibration can be dispersed over a wider frequency range, thereby reducing the noise perception at specific frequencies and providing a better user experience.

[0010] As one possible implementation, the motor controller is configured to control the amplitude of each phase of the three-phase current to be the same within any two adjacent cycles. If the bus current can maintain the same amplitude within any two adjacent cycles, the heating power of the power battery under the influence of the bus current will also be more stable, thereby optimizing the power battery heating process.

[0011] To further reduce noise, as one possible implementation, the motor controller controls the three-phase current so that the positive and negative half-cycles of each phase have different frequencies within the same cycle. This approach can more evenly distribute the noise energy generated by vibration over a wider frequency range, further reducing the perception of noise at specific frequencies.

[0012] As a possible implementation, the waveform of each phase current of the three-phase current is a unilateral waveform.

[0013] As a possible implementation manner, the waveform of each phase current of the three-phase current is a unilateral triangle wave.

[0014] As a possible implementation, the inverter circuit is used to connect the power battery via a DC bus, and the inverter circuit is used to generate pulsed AC power on the DC bus, wherein the frequency of the pulsed AC power is different in any two adjacent cycles.

[0015] As a possible implementation, in response to the temperature of the power battery being less than a preset value, the motor controller is configured to output three-phase current, which is used to generate pulsed alternating current on the DC bus, and the pulsed alternating current is used to heat the power battery.

[0016] The motor controller provided in this application outputs three-phase current when the temperature of the power battery is low. The three-phase current can generate pulsed alternating current on the DC bus to repeatedly charge and discharge the power battery. The pulsed alternating current generates heat on the internal resistance of the power battery, thereby heating the battery from the inside of the power battery.

[0017] As a possible implementation, the amplitudes of different bus currents in any two adjacent cycles are the same.

[0018] As a possible implementation, the direct-axis current components of the three-phase currents have different frequencies in any two adjacent cycles.

[0019] As one possible implementation, the direct-axis current component of the three-phase current has a DC bias, where the DC bias is either positive or negative. The DC-biased direct-axis voltage signal can increase the effective value of the three-phase current driving the motor, thereby improving the heating efficiency of the power battery.

[0020] As a possible implementation, the volt-second products of the direct-axis current signals of different frequencies are the same. If the volt-second products of the direct-axis current signals are the same, the stability of the heating power of the power battery can be ensured.

[0021] As a possible implementation manner, types of the direct-axis current signals with different frequencies include at least one of the following: a sine wave, a triangle wave, and a square wave.

[0022] To further reduce noise, as one possible implementation, the direct-axis current signals with different frequencies include a first direct-axis current signal and a second direct-axis current signal, where the first and second direct-axis current signals have different frequencies and the same volt-second product. This approach can more evenly distribute the noise energy generated by vibration over a wider frequency range, further reducing the perceived noise at specific frequencies.

[0023] As a possible implementation manner, the current signal of the direct-axis current component of the three-phase current in any cycle is any one of a first type signal, a second type signal, a third type signal, and a fourth type signal, wherein:

[0024] The first type of signal is the first direct-axis current signal; the second type of signal is the second direct-axis current signal; the third type of signal is a signal composed of the positive half-cycle of the first direct-axis current signal and the negative half-cycle of the second direct-axis current signal; the fourth type of signal is a signal composed of the negative half-cycle of the first direct-axis current signal and the positive half-cycle of the second direct-axis current signal.

[0025] As a possible implementation manner, the current signals of the direct-axis current of the three-phase current in any two adjacent cycles are any two of the first type signal, the second type signal, the third type signal and the fourth type signal.

[0026] As one possible implementation, the quadrature-axis current component of the three-phase current is less than a preset value, and the three-phase current causes the torque output by the drive motor to be less than a preset torque value. The quadrature-axis current component of the three-phase current provided in the embodiment of the present application is less than a preset value, thereby preventing unintended torque from being transmitted to the wheels, generating vibration and noise that could affect the riding experience of the electric vehicle.

[0027] As a possible embodiment, the motor controller includes a control circuit, which is used to output a control signal to the inverter circuit, and the control signal is used to control the inverter circuit to output a three-phase current, wherein: the control signal is used to indicate the frequency and amplitude of the direct-axis current component of the three-phase current and indicate that the quadrature-axis current component of the three-phase current is zero.

[0028] In a second aspect, the present application provides a powertrain, which includes a heat transfer circuit, wherein a three-phase current is used to heat the windings of a drive motor, and the heat transfer circuit is used to transfer the heat of the windings of the drive motor to a power battery.

[0029] In a third aspect, the present application provides an electric vehicle. The electric vehicle includes a power battery, wheels, and a power unit. The power unit includes a three-phase motor and a motor controller as described in any one of the first aspects. The motor controller is configured to receive power from the power battery to drive the three-phase motor to drive the wheels or output three-phase current to heat the power battery. Alternatively, the power unit includes a powertrain as described in any one of the second aspects, configured to receive power from the power battery to drive the wheels or heat the power battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG1 is a schematic structural diagram of an electric vehicle provided in an embodiment of the present application;

[0031] FIG2 is a schematic diagram of a powertrain provided in an embodiment of the present application;

[0032] FIG3 is a schematic diagram of a motor controller provided in an embodiment of the present application;

[0033] FIG4 is a schematic diagram of the operation of a motor controller provided in an embodiment of the present application;

[0034] FIG5 is a schematic diagram of a voltage setting signal provided in an embodiment of the present application;

[0035] FIG6 is a waveform diagram of the first and second direct-axis current signals and the first to fourth type signals;

[0036] FIG7 is a waveform diagram of a unilateral triangle wave;

[0037] FIG8 is a schematic diagram of another powertrain provided in an embodiment of the present application;

[0038] FIG9 is a schematic diagram of another powertrain provided in an embodiment of the present application. DETAILED DESCRIPTION

[0039] The following describes the technical solutions involved in the specific implementation of this application in conjunction with the accompanying drawings. Before describing the specific content of the technical solutions, the terms used in this application are briefly explained.

[0040] The words "first, second, third, etc." or module A, module B, module C and other similar terms in the specification and claims are only used to distinguish similar objects and do not represent a specific ordering of the objects. It is understandable that the specific order or sequence can be interchanged where permitted so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0041] The term "comprising" as used in the specification and claims should not be construed as limiting to what is listed thereafter; it does not exclude other elements or steps. Thus, it should be interpreted as specifying the presence of the features, integers, steps, or components mentioned, but not excluding the presence or addition of one or more other features, integers, steps, or components, or groups thereof. Thus, the expression "a device comprising means A and B" should not be limited to a device consisting solely of components A and B.

[0042] References in this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present application. Therefore, the phrases "in one embodiment" or "in an embodiment" appearing throughout this specification do not necessarily refer to the same embodiment, but may refer to the same embodiment. Furthermore, in one or more embodiments, the particular features, structures, or characteristics can be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art in the art of this application. In the event of any inconsistency, the meaning described in this specification or the meaning derived from the contents recorded in this specification shall prevail. In addition, the terms used herein are only for the purpose of describing the embodiments of the present application and are not intended to limit this application.

[0044] The electric motor of an electric vehicle is typically an AC motor, while the power battery is a DC source. Therefore, an inverter circuit converts the DC power output from the power battery into three-phase AC power for the motor. The coordinate axes of the three-phase AC power are the U-axis, V-axis, and W-axis. The three phases of AC power can also be referred to as the U-phase, V-phase, and W-phase, respectively. To simplify motor analysis, the stationary three-phase coordinates are often transformed into rotating dq coordinates. This transformation is called a Park transformation. In the dq coordinate system, the three coordinate axes are called the direct axis, quadrature axis, and zero axis.

[0045] The direct axis, also known as the D-axis or d-axis, is a time-varying DC coordinate axis obtained by Park transforming the stationary U / V / W three-phase coordinate axes.

[0046] The quadrature axis, also known as the Q axis or q-axis, is a time-varying AC coordinate axis obtained by performing a Park transformation on the stationary U / V / W three-phase coordinate axes.

[0047] The zero axis, also known as the 0 axis or 0-axis, is the coordinate axis perpendicular to the dq plane where the direct axis and the quadrature axis are located.

[0048] Specifically, the formula for Parker's transformation can be shown as follows:

[0049] Where θ is the angle between the d-axis and the U-axis; I_d is called the direct-axis current, which is mainly used to adjust the magnetic field; I_q is called the quadrature-axis current, which is mainly used to adjust the torque; I_0 is called the zero-sequence current; I_u, I_v, and I_w are the currents on the U-axis, V-axis, and W-axis, respectively, that is, the three-phase current.

[0050] The above matrix is ​​the expression for transforming the three-phase current into I_d, I_q, and I_0. Performing an inverse transformation on the matrix transformation can obtain the expression for transforming I_d, I_q, and I_0 into the three-phase current, which will not be repeated here.

[0051] Because three-phase current corresponds to the motor's windings, when outputting current to the motor's direct axis, the motor controller converts I_d into three-phase currents I_u, I_v, and I_w through the inverse of the Park transform, and then feeds I_u, I_v, and I_w into the motor windings. When outputting current to the motor's zero axis, the motor controller converts I_0 into three-phase currents I_u, I_v, and I_w through the inverse of the Park transform, and then feeds I_u, I_v, and I_w into the motor windings. The quadrature-axis voltage / current controls the torque output by the drive motor, while the direct-axis voltage / current controls the direction and magnitude of the magnetic field generated by the drive motor.

[0052] An electric vehicle consists of a drive motor, a motor controller, and a power battery. The motor controller receives power from the power battery and supplies power to the drive motor, which drives the wheels of the electric vehicle to enable it to travel.

[0053] Temperature significantly impacts power batteries. Charging and discharging power batteries at low temperatures can cause lithium deposition, leading to capacity degradation and even safety hazards. Therefore, the power battery must be heated to a certain temperature before electric vehicles can be driven.

[0054] There are three main methods of heating power batteries at present, including:

[0055] One way to heat a power battery is to use an external heating system to heat the power battery. For example, a power battery heat circuit is provided outside the power battery, and a heat-carrying fluid that carries heat is contained in the power battery heat circuit. A positive temperature coefficient resistor (PTC) heats the heat-carrying fluid in the power battery heat circuit, and the heat-carrying fluid in the power battery heat circuit transfers heat to the power battery to heat the power battery. Because the above method requires first heating the heat-carrying fluid in the power battery heat circuit and then heating the power battery through the heat-carrying fluid in the power battery heat circuit, the heat transfer path is long and the heating efficiency is low.

[0056] One way to heat the power battery is active electric drive heating. The active electric drive heating method uses the motor excitation current to generate heat on the drive motor to heat the power battery. The motor controller outputs three-phase alternating current to the drive motor, and the three-phase alternating current makes the torque of the drive motor zero. The excitation current generates heat on the drive motor windings, and the heat generated on the drive motor is transferred to the power battery through the heat conduction device between the drive motor and the power battery for heating. Since the heat of the drive motor needs to be transferred to the power battery through the heat conduction device in the above method, the above heating method has the disadvantages of a long heat transfer path, a low power battery heating rate, and low heating efficiency.

[0057] One method of heating power batteries is high-frequency pulse heating. This method utilizes high-frequency pulsed alternating current (AC) generated by a motor controller. The motor controller's bridge circuit generates high-frequency pulsed AC. When this high-frequency pulsed AC passes through the power battery, it generates heat across the battery's internal resistance, thereby heating the battery. High-frequency heating has gained widespread attention due to its rapid heating rate.

[0058] Since the pulsed AC power generated by the motor controller is formed by superimposing three phase currents, high-frequency pulsed AC can be achieved by injecting a high-frequency voltage signal into the control circuit of the motor controller to control the three bridge circuits. First, the high-frequency voltage signal is converted into a control signal, which controls the three bridge circuits of the motor controller. When the windings of the drive motor are acted upon by the control signal converted from the high-frequency voltage signal, the current flowing through the windings of the drive motor changes rapidly due to the very short cycle of the control signal. This rapidly changing current generates a changing electromagnetic field in the windings, which induces high-frequency vibrations in the windings themselves. This high-frequency vibration causes various parts of the windings to vibrate with small amplitudes. These small amplitude vibrations are converted into sound waves through material resonance, friction, and air conduction. In this case, the drive motor behaves like an acoustic device, generating noise. Furthermore, since the high-frequency voltage signal has a fixed frequency, the resulting noise also has a fixed frequency. If this frequency is within the audible range of the human ear, it will be perceived as a sharp and piercing sound, resulting in a poor user experience.

[0059] In view of this, embodiments of the present application provide a motor controller, a powertrain, and an electric vehicle. The motor controller provided in embodiments of the present application optimizes high-frequency noise during the power battery heating process by controlling the frequency of each phase of the three-phase current, thereby improving the user experience.

[0060] FIG1 is a schematic diagram of an electric vehicle 10 according to an embodiment of the present application. Referring to FIG1 , the electric vehicle 10 includes wheels 12, a power battery 13, and a powertrain 14. The powertrain 14 is configured to receive power from the power battery 13 to drive the wheels 12 or to heat the power battery 13.

[0061] FIG2 is a schematic diagram of a powertrain 14 provided in an embodiment of the present application. Referring to FIG2 , the powertrain 14 includes a drive motor 11 and a motor controller 12. The motor controller 12 receives direct current (DC) from a power battery and converts the DC power into three-phase AC power to power the drive motor 11. The drive motor 11 and wheels 12 are connected via a speed reducer or transmission. During travel of the electric vehicle 10, the torque of the drive motor 11 is transmitted to the wheels 12 to power the electric vehicle 10.

[0062] Figure 3 is a schematic diagram of the motor controller 12 provided in an embodiment of the present application. Referring to Figure 3, the motor controller 12 includes a control circuit 121, an inverter circuit 122 and a bus capacitor C. One end of the bus capacitor C is used to connect to the positive electrode of the power battery 13, and the other end of the bus capacitor C is used to connect to the negative electrode of the power battery 13. The inverter circuit 122 includes a three-phase switch tube bridge arm, and the two ends of each switch tube bridge arm are respectively connected to the two ends of the bus capacitor C, and the midpoint of each switch tube bridge arm is respectively used to connect to a phase winding of the drive motor 11. The rotor position signal output end of the drive motor 11 is connected to the signal acquisition end of the control circuit 121, and the two ends of the inverter circuit 122 are respectively connected to the positive and negative poles of the power battery 13 to form a power battery pulse heating circuit.

[0063] Exemplarily, the control circuit 121 may include, but is not limited to, a central processing unit (CPU), other general-purpose processors, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The control circuit 121 may control the on or off of the switches in each bridge arm by outputting a control signal to each bridge arm of the inverter circuit 122. The control signal may be a pulse width modulation (PWM) signal. Exemplarily, the control circuit 121 may be connected to the gate of each switch tube in the three bridge arms of the inverter circuit 122 to control the on or off of each switch tube in the inverter circuit 122. In some application scenarios, the control circuit 121 may combine space vector pulse width modulation (SVPWM) technology to generate control signals for each switch in the three bridge arms.

[0064] The specific process of high-frequency pulse heating of the motor controller 12 is described below in conjunction with specific embodiments.

[0065] When the motor controller 12 responds to the temperature of the power battery 13 being greater than a set temperature threshold, the motor controller 12 can start the drive motor 11 normally. The three bridge arms in the inverter circuit 122 can convert the DC current provided by the power battery 13 into AC current, and then provide the AC current to the drive motor 11, so that the drive motor 11 outputs torque to drive the wheels of the electric vehicle 10.

[0066] In response to the temperature of the power battery 13 being no greater than a set temperature threshold, the motor controller 12 sends control signals to the three bridge arms, causing the midpoints of the three-phase switching tube bridge arms to output three-phase current to the windings of the drive motor, thereby generating heat from the internal resistance of the power battery and thereby heating the power battery. Furthermore, in this application, the frequency of each phase of the three-phase current is different within any two adjacent cycles.

[0067] Because the frequency of each phase current is different in any two adjacent cycles, the frequency of each phase current flowing through the windings of the drive motor 11 is also different. Consequently, the vibration frequency generated by each winding under the action of the rapidly changing current is also different. Therefore, if the frequencies in any two adjacent cycles are different, the noise generated by the windings of the drive motor 11 in the two adjacent cycles will also have at least two different frequencies. Since each cycle is very short, the noise energy generated by the vibration can be dispersed over a wider frequency range, thereby reducing the noise perception at specific frequencies and providing a better user experience.

[0068] The bus current is formed by the superposition of the three phase currents. Therefore, the amplitude of each phase current determines the amplitude of the bus current. If the amplitude of each phase current of the three-phase current can be maintained constant between any two adjacent cycles, then the bus current formed by the superposition of the three phase currents can also be maintained constant between any two adjacent cycles. If the bus current can maintain constant amplitude between any two adjacent cycles, the heating power of the power battery 13 under the action of the bus current will also be relatively stable, thereby optimizing the heating process of the power battery 13.

[0069] In order to further reduce noise, the frequency of the positive half-cycle and the frequency of the negative half-cycle of each phase current of the three-phase current in the same cycle may also be different. Among them, if the frequency of the positive half-cycle and the negative half-cycle of each phase current of the three-phase current in the same cycle are different, it means that the frequency of each phase current in one cycle may be different. Furthermore, the vibration frequency of the winding of the drive motor 11 is also different in one cycle. The present application adopts this method to more evenly disperse the noise energy generated by the vibration into a wider frequency range, thereby further reducing the noise perception at a specific frequency.

[0070] Among them, the control circuit 121 in the motor controller 12 is used to: drive the operation of the upper arm switch tube and the lower arm switch tube of each switch tube bridge arm, and control the midpoint of the three-phase switch tube bridge arm to output three-phase current respectively, and the frequency of each phase current of the three-phase current is different in any two adjacent cycles.

[0071] Because the frequency of each phase current is different in any two adjacent cycles, the frequency of the phase current signal flowing through the winding is also different. Consequently, the vibration frequency generated by each winding under the influence of the rapidly changing current is also different. Therefore, this application can disperse the noise energy generated by vibration over a wider frequency range, thereby reducing the noise perception at specific frequencies and providing a better user experience.

[0072] The control circuit 121 is used to output a control signal to the inverter circuit 122, and the control signal is used to control the inverter circuit 122 to output the three-phase current, wherein: the control signal is used to indicate the frequency and amplitude of the direct-axis current component of the three-phase current and indicate that the quadrature-axis current component of the three-phase current is zero.

[0073] The control circuit 121 controls the three-phase switching tube bridge arms via control signals. The three bridge arms included in the inverter circuit 122 can be respectively designated as the U-phase bridge arm, the V-phase bridge arm, and the W-phase bridge arm. Continuing with FIG3 , the upper bridge switch in the U-phase bridge arm is switch Q1, and the lower bridge switch is switch Q2. The upper bridge switch in the V-phase bridge arm is switch Q3, and the lower bridge switch is switch Q4. The upper bridge switch in the W-phase bridge arm is switch Q5, and the lower bridge switch is switch Q6. One end of each bridge arm is connected to one end of the power battery 13, i.e., the collector of switch Q1, the collector of switch Q3, and the collector of switch Q5 are connected to one end of the power battery 13. The other end of each bridge arm is connected to the other end of the power battery 13, i.e., the emitter of switch Q2, the emitter of switch Q4, and the emitter of switch Q6 are connected to the other end of the power battery 13. Optionally, one end of the power battery 13 may be the positive terminal of the power battery 13 , and the other end of the power battery 13 may be the negative terminal of the power battery 13 . Alternatively, one end of the power battery 13 may be the negative terminal of the power battery 13 , and the other end of the power battery 13 may be the positive terminal of the power battery 13 .

[0074] Optionally, the upper bridge switch tube can be an insulated gate bipolar transistor (IGBT) and its anti-parallel diode, or a metal oxide semiconductor field effect transistor (MOSFET). This application does not impose too many restrictions on the specific structure inside the upper bridge switch tube. Optionally, the lower bridge switch tube can be an IGBT and its anti-parallel diode, or a MOSFET. This application does not impose too many restrictions on the specific structure inside the lower bridge switch tube.

[0075] The control circuit 121 is configured to control, via control signals, the upper bridge switching tube of one of the three bridge arms and the lower bridge switching tubes in the other two bridge arms to periodically conduct, such that the power battery 13, the one upper bridge switching tube that is conducted, the two-phase windings of the drive motor, and the two lower bridge switching tubes that are conducted form a discharge circuit. The internal resistance of the power battery 13 generates heat under the action of the current in the discharge circuit, thereby heating the power battery 13. Alternatively, the lower bridge switching tube of one of the three bridge arms and the upper bridge switching tubes in the other two bridge arms are periodically conducted, such that the power battery 13, the one lower bridge switching tube that is conducted, the two-phase windings of the drive motor, and the two upper bridge switching tubes that are conducted form a discharge circuit. The internal resistance of the power battery 13 generates heat under the action of the current in the discharge circuit, thereby heating the power battery 13.

[0076] The control signal indicates the direct-axis current component and the quadrature-axis current component of the three-phase current. The direct-axis current component controls the direction and magnitude of the magnetic field generated by the drive motor 11, while the quadrature-axis current component controls the torque output by the drive motor 11. To control the output of the three-phase current at the midpoint of each bridge arm of the three-phase switching tube, and to ensure that the frequency of each phase of the three-phase current is different within any two adjacent cycles, it is necessary to specifically control the frequency of the direct-axis current component.

[0077] As shown in Figure 4, the control circuit 121 of the motor controller 12 includes a quadrature-axis current controller 401, a direct-axis current controller 402, and a drive circuit 403. In the embodiment of the present application, the motor controller 12 is used to receive a heating instruction and determine the quadrature-axis current component determined by the quadrature-axis current controller 401 and the direct-axis current component determined by the direct-axis current controller 402 according to the heating power of the power battery 13 indicated by the heating instruction. The drive circuit 403 may include a Park's transmission module and a Clarke's transmission module. The Parke's transmission module is used to convert two components in the αβ coordinate system into an orthogonal rotating coordinate system (dq), and the Clarke's transmission module converts the time domain components of the three-phase system (in the abc coordinate system) into two components in the orthogonal stationary coordinate system (αβ). In an embodiment of the present application, the Park transformation module receives the quadrature-axis voltage signal Uq and the direct-axis voltage signal Ud, and performs an inverse Park transformation on the signals Uq and Ud in the direct-quadrature coordinate system to obtain voltage signals Uα and Uβ in the αβ coordinate system, and generates a control signal based on the Uα and Uβ signals. The control signal is used to control the conduction frequency and duty cycle of the switching tube of the inverter circuit 122.

[0078] Among them, the quadrature-axis current component is used to control the torque output by the drive motor 11. During the high-frequency pulse heating process of the power battery 13, if the quadrature-axis current component of the drive motor 11 is not less than a preset value, the drive motor 11 will generate unexpected torque output. The unexpected torque of the drive motor 11 is transmitted to the wheel 12, which will cause the electric vehicle 10 to generate vibration and noise, affecting the riding experience of the electric vehicle 10. Therefore, the quadrature-axis current component of the three-phase current provided in the embodiment of the present application is less than the preset value, thereby avoiding the unexpected torque being transmitted to the wheel to generate vibration and noise, affecting the riding experience of the electric vehicle. Optionally, the caliper in the electronic parking brake system (EPB) of the electric vehicle 10 can be in a locked state to ensure that the wheels of the electric vehicle 10 do not move.

[0079] The direct-axis current component is used to control the direction and magnitude of the magnetic field generated by the drive motor 11. By controlling the direction and magnitude of the magnetic field generated by the drive motor 11, the magnitude and direction of the bus current can be adjusted, thereby adjusting the heating power of the power battery 13 and eliminating noise during the heating process. Specifically, the direct-axis current component can be determined based on the heating power of the power battery 13 indicated by the heating instruction. The direct-axis current component includes two parameters: the frequency and amplitude of the direct-axis voltage, and the offset of the direct-axis voltage. Optionally, the direct-axis current component may include a voltage reference signal and a direct-axis offset signal. The voltage reference signal indicates the frequency and amplitude of the voltage, and the direct-axis offset signal is used to apply a DC bias to the voltage. In other words, the motor controller ultimately inputs the direct-axis voltage signal with a DC bias into the drive circuit 403, causing the drive circuit 403 to generate a control signal based on the direct-axis voltage signal, which is then used to drive the drive motor 11. The direct-axis voltage signal with a DC bias can increase the effective value of the three-phase current of the drive motor 11, thereby improving the heating efficiency of the power battery. It should be noted that the DC bias of the direct-axis voltage signal can be a positive DC bias or a negative DC bias, and those skilled in the art can set it individually according to the demand for heating power.

[0080] As shown in FIG5 , FIG5(a) is a waveform diagram of the voltage indicated by the voltage setting signal, taking the waveform of the voltage setting signal as a square wave as an example. FIG5(b) is a waveform diagram of the bias voltage indicated by the direct-axis bias signal, and FIG5(c) is a waveform diagram of the voltage setting signal with a DC bias. That is, the waveform diagram of FIG5(c) is formed by superimposing the voltage signal of FIG5(a) and FIG5(b).

[0081] To ensure that the frequency of each phase current varies between any two adjacent cycles, the voltage reference signal in the direct-axis current component of the three-phase current must be set to different frequencies within any two adjacent cycles. Since the direct-axis current component of the three-phase current is related to the voltage reference signal input by the drive circuit, if the voltage reference signal includes at least two different frequencies within any two adjacent cycles, the frequencies of the direct-axis current component of the three-phase current can vary within any two adjacent cycles.

[0082] The given voltage signal may include signals of multiple frequencies. As one possible embodiment, the given voltage signal includes a first direct-axis current signal and a second direct-axis current signal, wherein the first and second direct-axis current signals have different frequencies. Furthermore, the given voltage signal may be of at least one of the following types: a sine wave, a triangular wave, and a square wave. Those skilled in the art may determine the type of given voltage signal based on the ripple current of the pulsed alternating current and the heating efficiency, and this is not specifically limited here.

[0083] Optionally, the signal type of the voltage given signal in the first cycle of two adjacent cycles can be a first direct-axis current signal, and the signal type of the voltage given signal in the second cycle of two adjacent cycles can be a second direct-axis current signal, or the signal type of the voltage given signal in the first cycle of two adjacent cycles can be a second direct-axis current signal, and the signal type of the voltage given signal in the second cycle of two adjacent cycles can be the first direct-axis current signal. In this way, the voltage given signal includes two different frequencies in any two adjacent cycles, thereby making the frequency of each phase of the three-phase current different in any two adjacent cycles.

[0084] It should be noted that, in order to ensure heating efficiency, even if the frequencies of the first direct-axis current signal and the second direct-axis current signal are different, the volt-second product of the first direct-axis current signal and the second direct-axis current signal needs to be the same. Among them, the volt-second product of the signal refers to the integral of the signal, which represents the accumulation of the signal on the time axis. The volt-second product can also be called the voltage-time integral, which is used to describe the cumulative value of the energy or amplitude of the signal over a period of time. The volt-second product of the signal can be expressed as the following integral form: volt-second product = ∫ (signal amplitude) × (time) dt, where the integration is performed from the start time to the end time. The volt-second product can be used to measure the energy consumption or accumulation of the signal over a period of time. For periodic signals, the calculation of the volt-second product can be used to analyze the average energy of the signal. In this way, it can be understood that if the frequencies of the first direct-axis current signal and the second direct-axis current signal are different, and the amplitudes of the first direct-axis current signal and the second direct-axis current signal are also different, the volt-second products of the first direct-axis current signal and the second direct-axis current signal can be made the same, thereby optimizing the heating process of the power battery 13 and ensuring the stability of the heating power of the power battery 13.

[0085] Furthermore, to reduce noise perception at specific frequencies, the current signal within any cycle of the voltage reference signal is any one of a first type signal, a second type signal, a third type signal, and a fourth type signal. The first type signal is the first direct-axis current signal; the second type signal is the second direct-axis current signal; the third type signal is a signal consisting of the positive half-cycle of the first direct-axis current signal and the negative half-cycle of the second direct-axis current signal; and the fourth type signal is a signal consisting of the negative half-cycle of the first direct-axis current signal and the positive half-cycle of the second direct-axis current signal.

[0086] As shown in Figure 6 , (a) is a waveform diagram of the first direct-axis current signal, (b) is a waveform diagram of the second direct-axis current signal, and (c) is a waveform diagram of the first through fourth type signals, using a sinusoidal voltage waveform as an example. Specifically, the first through fourth type signals in Figure 6 (c) are a combination of the first and second direct-axis current signals.

[0087] The direct-axis current signals of the three-phase current in any two adjacent cycles are any two of the first type signal, the second type signal, the third type signal, and the fourth type signal. Thus, after the four types of signals are preset, random splicing can be performed in any two adjacent cycles. Optionally, a random function RAND can be used to select two of the four types of signals for combined splicing, thereby making the frequency of each phase of the three-phase current different in any two adjacent cycles.

[0088] It should be noted that the given voltage signal may further include more direct-axis current signals of different frequencies. For example, if the given voltage signal includes N direct-axis current signals of different frequencies, then the N direct-axis current signals of different frequencies may be combined into 2N different types of signals, and the current signals in any adjacent cycles of the given voltage signal may include any two of the 2N types of signals.

[0089] In the embodiment of the present application, the waveform of each phase current of the three-phase current driving the motor 11 is a unilateral waveform. A unilateral waveform refers to a current in which the direction of each phase current of the driving motor remains unchanged. Taking the unilateral waveform as a triangular wave as an example, Figure 7 is a schematic diagram of a unilateral waveform. As shown in Figure 7, the current in (a) of Figure 7 is always greater than zero, and the current in (b) of Figure 7 is always less than zero.

[0090] During a positive and negative cycle of alternating current, the unilateral triangular wave can maximize the energy stored and released by the motor's three-phase winding inductance during this cycle, effectively increasing the effective value of the pulse heating current and improving the heating power.

[0091] As shown in FIG8 , the powertrain provided in the embodiment of the present application includes a heat exchange circuit 15. Due to the thermal effect of current, the three-phase current on the drive motor 11 will cause the three-phase winding of the drive motor 11 to heat up. The powertrain 14 provided in the embodiment of the present application includes a heat exchange circuit 15, which is used to transfer the heat generated in the three-phase winding of the drive motor 11 to the power battery 13 to heat the power battery 13. By providing a heat exchange circuit, the powertrain provided in the embodiment of the present application can transfer the heat generated in the drive motor winding during the pulse heating process of the power battery to the power battery, thereby improving energy utilization efficiency, saving energy, and improving the heating efficiency of the power battery.

[0092] In one embodiment, as shown in FIG9 , the heat exchange circuit 15 includes a heat transfer medium, a heat transfer medium flow circuit, a liquid pump 901, and a heat exchanger 902. The heat transfer medium is used to absorb heat generated by the windings of the drive motor 11. The heat transfer medium flows in the heat transfer medium flow circuit. The liquid pump 901 is used to provide power for the flow of the heat transfer medium. The heat exchanger 902 is used to absorb heat from the heat transfer medium and transfer the absorbed heat from the heat transfer medium to the power battery 13 to heat the power battery 13.

[0093] Those skilled in the art will understand that the various numerical numbers such as first and second involved in this application are only for the convenience of description and are not used to limit the scope of the embodiments of this application. The sequence and execution order of each process should be determined by its function and internal logic.

[0094] Those skilled in the art will appreciate that the modules of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art may use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0095] Obviously, those skilled in the art may make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application is intended to include these modifications and variations.

Claims

1. A motor controller for pulse heating of a power battery of an electric vehicle, characterized in that: The motor controller includes an inverter circuit, which includes a three-phase switch tube bridge arm, and the midpoint of the bridge arm of each phase of the switch tube bridge arm is used to connect a phase winding of the drive motor. The inverter circuit is used to connect the power battery through a DC bus. The motor controller is used to: The midpoint of the bridge arm of the three-phase switch tube bridge arm of the inverter circuit is controlled to output a three-phase current to the winding of the drive motor, the three-phase current is used to generate pulse alternating current on the DC bus, and the pulse alternating current is used to heat the power battery; The frequency of each phase current of the three-phase current is controlled to be different in any two adjacent cycles.

2. The motor controller according to claim 1, characterized in that: The motor controller is used to control the amplitude of each phase current of the three-phase current to be the same in any two adjacent cycles.

3. The motor controller according to claim 1 or 2, characterized in that: The motor controller is used to control the positive half cycle and the negative half cycle of each phase current of the three-phase current to have different frequencies in the same cycle.

4. The motor controller according to any one of claims 1 to 3, characterized in that: The motor controller is used to control the waveform of each phase current of the three-phase current to be a unilateral waveform.

5. The motor controller according to claim 1, characterized in that: The frequencies of the pulse alternating current in any two adjacent cycles are different.

6. The motor controller according to claim 5, characterized in that: The different bus currents have the same amplitude in any two adjacent cycles.

7. The motor controller according to any one of claims 1 to 6, characterized in that: The direct-axis current components of the three-phase currents have different frequencies in any two adjacent cycles.

8. The motor controller according to claim 7, characterized in that: The direct-axis current component of the three-phase current has a DC bias, and the DC bias is a positive DC bias or a negative DC bias.

9. The motor controller according to claim 7 or 8, characterized in that: The volt-second products of the direct-axis current signals with different frequencies are the same.

10. The motor controller according to any one of claims 7 to 9, characterized in that: The types of the direct-axis current signals with different frequencies include at least one of the following: a sine wave, a triangle wave, and a square wave.

11. The motor controller according to any one of claims 7 to 10, characterized in that: The direct-axis current signals with different frequencies include a first direct-axis current signal and a second direct-axis current signal. The frequencies of the first direct-axis current signal and the second direct-axis current signal are different, and the volt-second products of the first direct-axis current signal and the second direct-axis current signal are the same.

12. The motor controller according to claim 11, characterized in that: The current signal of the direct-axis current component of the three-phase current in any period is any one of a first type signal, a second type signal, a third type signal and a fourth type signal, wherein: The first type of signal is a first straight-axis current signal; The second type of signal is a second direct-axis current signal; The third type of signal is a signal composed of a positive half cycle of the first direct-axis current signal and a negative half cycle of the second direct-axis current signal; The fourth type of signal is a signal composed of a negative half cycle of the first direct-axis current signal and a positive half cycle of the second direct-axis current signal.

13. The motor controller according to claim 12, characterized in that: The current signals of the direct-axis current of the three-phase current in any two adjacent periods are any two of the first type of signal, the second type of signal, the third type of signal and the fourth type of signal.

14. The motor controller according to any one of claims 1 to 13, characterized in that: The quadrature-axis current component of the three-phase current is smaller than a preset value and the three-phase current causes the torque output by the drive motor to be smaller than a preset torque value.

15. The motor controller according to any one of claims 1 to 14, characterized in that: The motor controller comprises a control circuit, the control circuit is used to output a control signal to the inverter circuit, the control signal is used to control the inverter circuit to output the three-phase current, wherein: The control signal is used to indicate the frequency and amplitude of the direct-axis current component of the three-phase current and to indicate that the quadrature-axis current component of the three-phase current is zero.

16. The motor controller according to any one of claims 1 to 15, characterized in that: The motor controller is used to: In response to the temperature of the power battery being less than a preset value, the motor controller is used to output the three-phase current, the three-phase current is used to generate the pulse alternating current on the DC bus, and the pulse alternating current is used to heat the power battery.

17. A powertrain, characterized in that: The powertrain includes a motor controller and a heat conduction device as described in any one of claims 1 to 16, the three-phase current is used to heat the windings of the drive motor, and the heat conduction device is used to conduct the heat generated by the windings of the drive motor to the power battery.

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