Motor controller and control method thereof, new energy vehicle

Abstract

The application provides a motor controller and a control method thereof, and a new energy vehicle. The motor controller comprises a bridge arm conversion module, a bus capacitor, a motor module, a control module and a switching module. The control method comprises the following steps: after the motor controller enters an alternating current heating mode, it is determined whether the voltage across the bus capacitor exceeds a threshold value. If yes, the frequency of the charging and discharging current is increased. If not, the amplitude of the charging and discharging current is increased. The frequency or amplitude of the charging and discharging current is gradually adjusted until the frequency of the charging and discharging current exceeds a target frequency or the amplitude of the charging and discharging current exceeds a target amplitude. The control module can control the amplitude of the charging and discharging current to be the target amplitude or the frequency to be the target frequency. According to the application, only the first switch and the second switch need to be added to heat the power battery, the structure of the motor module does not need to be changed, the improvement is small, the cost is lower, and the charging and discharging can be performed with the optimal charging and discharging current without damaging the bus capacitor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor technology, in particular to a motor controller and a control method thereof, and a new energy vehicle. BACKGROUND

[0002] With the wide use of new energy, power batteries can be used as power sources in various fields. The use environment of power batteries is different, and their performance will also be affected. For example, in a low temperature environment, the power battery has problems such as charging difficulty, low discharging efficiency and cycle life attenuation. In order to use the power battery in a low temperature environment, the power battery needs to be heated before use, but the existing heating scheme for the power battery is relatively complex and has a high cost. SUMMARY

[0003] Therefore, the embodiments of the present application aim to provide a motor controller and a control method thereof, and a new energy vehicle, to solve the problem of the existing heating scheme for the power battery being relatively complex and having a high cost.

[0004] In one aspect, the present application provides a control method of a motor controller, the motor controller comprising a bridge arm conversion module, a bus capacitor, a motor module, a control module and a switching module, the switching module comprising at least a first switch and a second switch; the bridge arm conversion module, the bus capacitor and a first end of a power battery are connected to each other, the bridge arm conversion module, the bus capacitor and a second end of the power battery are connected to each other, and each phase winding of the motor module is connected to a neutral point of a corresponding bridge arm of the bridge arm conversion module; the first switch is connected between any phase winding of the motor module and the neutral point of the corresponding bridge arm of the bridge arm conversion module, and the second switch is connected between the first switch and the first end of the power battery; the control method comprises:

[0005] Step S100: the control module controls the state of all switches in the switching module to control the motor controller to enter an alternating current heating mode, and step S200 is executed;

[0006] Step S200: at least one charge-discharge cycle is performed between the power battery and the bus capacitor, and step S300 is executed;

[0007] Step S300: it is judged whether the voltage across the bus capacitor exceeds a threshold value, if yes, the frequency of the charge-discharge current is increased, and step S400 is executed, if not, the amplitude of the charge-discharge current is increased, and step S500 is executed;

[0008] Step S400: determining whether the frequency of the charging / discharging current exceeds a target frequency, if yes, the control module controls the frequency of the charging / discharging current to be the target frequency and the amplitude to be the current amplitude, if not, increasing the frequency of the charging / discharging current, and returning to step S200;

[0009] Step S500: determining whether the amplitude of the charging / discharging current exceeds a target amplitude, if yes, the control module controls the amplitude of the charging / discharging current to be the target amplitude and the frequency to be the current frequency, if not, increasing the amplitude of the charging / discharging current, and returning to step S200.

[0010] In some embodiments, the switching module further comprises a third switch and a fourth switch, the motor controller further comprises a pre-charging load, the third switch is connected between the first end of the power battery and the first end of the bus capacitor, and the fourth switch is connected in parallel to the third switch in series with the pre-charging load; the control module controls the state of all switches in the switching module to control the motor controller to enter the alternating current heating mode, and the step comprises:

[0011] the control module controls the second switch to be closed, the first switch to be opened, the motor controller to enter the alternating current heating mode, the third switch to be opened, and the fourth switch to be closed, the power battery pre-charges the bus capacitor, after the pre-charging is completed, the control module controls the third switch and the fourth switch to be both opened, and the power battery and the bus capacitor start to cyclically charge and discharge.

[0012] In some embodiments, the control method further comprises:

[0013] the control module controls the first switch to be closed, the second switch to be opened, the motor controller to enter the power output mode, after the motor controller enters the power output mode, the control module controls the third switch to be opened and the fourth switch to be closed, the power battery pre-charges the bus capacitor, after the pre-charging is completed, the control module controls the third switch to be closed and the fourth switch to be opened.

[0014] In some embodiments, after the motor controller enters the alternating current heating mode, the control module controls the power tube of the upper bridge arm of the bridge arm conversion module to be always on, the power battery discharges to the bus capacitor, and the control module further adjusts the duty cycle of the power tube of the lower bridge arm of the bridge arm conversion module to adjust the amplitude and frequency of the charging / discharging current; and,

[0015] The control module controls the power tube of the lower bridge arm of the bridge arm conversion module to be always off, and the bus capacitor discharges the power battery, and the control module further adjusts the duty cycle of the power tube of the upper bridge arm of the bridge arm conversion module to adjust the amplitude and frequency of the charge-discharge current.

[0016] In some embodiments, after determining that the frequency of the charge-discharge current exceeds the target frequency, the control module fits the target charge-discharge current according to the target frequency and the current amplitude, and obtains a deviation value by subtracting the sum of all phase currents without the first switch from the target charge-discharge current, and performs PID adjustment on the deviation value to obtain a target duty cycle of the power tube corresponding to the phase without the first switch. The control module controls the duty cycle of the power tube corresponding to the phase without the first switch to be the target duty cycle, so that the frequency of the charge-discharge current is the target frequency and the amplitude is the current amplitude.

[0017] In some embodiments, after determining that the amplitude of the charge-discharge current exceeds the target amplitude, the control module fits the target charge-discharge current according to the target amplitude and the current frequency, and obtains a deviation value by subtracting the sum of all phase currents without the first switch from the target charge-discharge current, and performs PID adjustment on the deviation value to obtain a target duty cycle of the power tube corresponding to the phase without the first switch. The control module controls the duty cycle of the power tube corresponding to the phase without the first switch to be the target duty cycle, so that the amplitude of the charge-discharge current is the target amplitude and the frequency is the current frequency.

[0018] In some embodiments, when the control module receives a heating instruction, the control module controls the state of all switches in the switch module to control the motor controller to enter the alternating current heating mode, the heating instruction at least contains the target amplitude, and the target amplitude is 90% to 100% of the maximum amplitude of the charge-discharge current; and / or, the target frequency is built into the control module, and the target frequency is 90% to 100% of the maximum frequency of the charge-discharge current.

[0019] In some embodiments, when the power battery and the bus capacitor start to cycle charge and discharge, the initial amplitude of the charge-discharge current is 25% to 50% of the target amplitude, and the initial frequency of the charge-discharge current is the minimum frequency of the charge-discharge current.

[0020] An embodiment of the present application further provides a motor controller, which comprises a bridge arm conversion module, a bus capacitor, a motor module, a control module and a switch module, the switch module at least comprising a first switch and a second switch.

[0021] The bridge arm conversion module, the bus capacitor and the first end of the power battery are connected with each other, the second end of the bridge arm conversion module, the bus capacitor and the power battery are connected with each other, and each phase winding of the motor module is connected with a neutral point of a corresponding bridge arm of the bridge arm conversion module.

[0022] The first switch is connected between any winding of the motor module and the neutral point of the corresponding bridge arm of the bridge arm conversion module, and the second switch is connected between the first switch and the first end of the power battery.

[0023] The control module is configured to control the states of all switches in the switch module, so as to control the motor controller to enter a power output mode or an alternating current heating mode, in the alternating current heating mode, the power battery and the bus capacitor are cyclically charged and discharged, the control module also controls the frequency of the charging and discharging current to be a target frequency, or the amplitude to be a target amplitude, and makes the voltage across the bus capacitor not exceed a threshold value.

[0024] An embodiment of the present application also provides a new energy vehicle comprising the motor controller.

[0025] The application provides a motor controller and a control method thereof, and a new energy vehicle. The motor controller comprises a bridge arm conversion module, a bus capacitor, a motor module, a control module and a switching module. The switching module comprises at least a first switch and a second switch. The bridge arm conversion module, the bus capacitor and a first end of a power battery are connected with each other, the bridge arm conversion module, the bus capacitor and a second end of the power battery are connected with each other, and each phase winding of the motor module is connected with a neutral point of a corresponding bridge arm of the bridge arm conversion module. The first switch is connected between any phase winding of the motor module and the neutral point of the corresponding bridge arm of the bridge arm conversion module, and the second switch is connected between the first switch and the first end of the power battery. The control method comprises the following steps: S100, the control module controls the state of all switches in the switching module to control the motor controller to enter an alternating current heating mode, and step S200 is executed; S200, at least one charging and discharging cycle is performed between the power battery and the bus capacitor, and step S300 is executed; S300, it is judged whether the voltage between the bus capacitor exceeds a threshold value, if yes, the frequency of the charging and discharging current is increased, and step S400 is executed, if not, the amplitude of the charging and discharging current is increased, and step S500 is executed; S400, it is judged whether the frequency of the charging and discharging current exceeds a target frequency, if yes, the control module controls the frequency of the charging and discharging current to be the target frequency and the amplitude to be a current amplitude, if not, the frequency of the charging and discharging current is increased, and step S200 is returned; S500, it is judged whether the amplitude of the charging and discharging current exceeds a target amplitude, if yes, the control module controls the amplitude of the charging and discharging current to be the target amplitude and the frequency to be a current frequency, if not, the amplitude of the charging and discharging current is increased, and step S200 is returned. The first switch and the second switch are only needed to be added to heat the power battery, the structure of the motor module does not need to be changed, the improvement is small, the cost is lower, and the charging and discharging can be performed with the optimal charging and discharging current without damaging the bus capacitor, so that the heating efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 A circuit diagram of the motor controller provided by an embodiment of the application.

[0027] Figure 2 An equivalent circuit diagram of the motor controller provided by an embodiment of the application in a power output mode.

[0028] Figure 3 An equivalent circuit diagram of the motor controller provided by an embodiment of the application in an alternating current heating mode.

[0029] Figure 4 An equivalent circuit diagram of the power battery discharging to the bus capacitor provided by an embodiment of the application.

[0030] Figure 5 An equivalent circuit diagram for discharging the bus capacitor to the power battery is provided for an embodiment of the present application.

[0031] Figure 6 A flowchart of a control method of the motor controller is provided for an embodiment of the present application.

[0032] Figure 7 A specific flowchart of a control method of the motor controller is provided for an embodiment of the present application.

[0033] Figure 8 A control logic diagram of the control module is provided for an embodiment of the present application.

[0034] In the drawings, reference numerals are used to indicate the components of the embodiments of the present application.

[0035] 10 - bridge arm conversion module; 20 - motor module; E - power battery; C - bus capacitor; K1 - first switch; K2 - second switch; K3 - third switch; K4 - fourth switch; R - pre-charge load; L1 - first phase winding; L2 - second phase winding; L3 - third phase winding; A1 - first current detector; A2 - second current detector; S1 - first power tube; S2 - second power tube; S3 - third power tube; S4 - fourth power tube; S5 - fifth power tube; S6 - sixth power tube. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0037] As described above, the power battery has problems such as charging difficulty, low discharging efficiency, and cycle life attenuation at low temperature, and usually needs to be heated before working. In the prior art, the battery needs to be connected to the neutral point of the motor to achieve heating of the power battery, which greatly changes the motor and has high cost.

[0038] The technical solutions in the embodiments of the present application are suitable for the application scenario of heating and discharging the power battery in a new energy vehicle. The present application provides a motor controller and a control method thereof. Figure 1 A circuit diagram of the motor controller provided for an embodiment of the present application is shown in Figure 1 As shown in the figure, the motor controller includes a bridge arm conversion module 10, a bus capacitor C, a motor module 20, a control module, and a switching module. The control module is not shown in Figure 1are shown in FIG. 1.

[0039] Specifically, the bridge arm conversion module 10 has three phase bridge arms, i.e. a first phase bridge arm, a second phase bridge arm and a third phase bridge arm, each of which has an upper bridge arm and a lower bridge arm, and each of which is provided with a power tube. Specifically, the upper bridge arm of the first phase bridge arm includes a first power tube S1 and a diode connected in parallel with the first power tube S1, the upper bridge arm of the second phase bridge arm includes a second power tube S2 and a diode connected in parallel with the second power tube S2, and the upper bridge arm of the third phase bridge arm includes a third power tube S3 and a diode connected in parallel with the third power tube S3; the lower bridge arm of the first phase bridge arm includes a fourth power tube S4 and a diode connected in parallel with the fourth power tube S4, the lower bridge arm of the second phase bridge arm includes a fifth power tube S5 and a diode connected in parallel with the fifth power tube S5, and the lower bridge arm of the third phase bridge arm includes a sixth power tube S6 and a diode connected in parallel with the sixth power tube S6; the neutral point of the first phase bridge arm is the neutral point connecting the first power tube S1 and the fourth power tube S4, the neutral point of the second phase bridge arm is the neutral point connecting the second power tube S2 and the fifth power tube S5, and the neutral point of the third phase bridge arm is the neutral point connecting the third power tube S3 and the sixth power tube S6; the upper bridge arms of the first phase bridge arm, the second phase bridge arm and the third phase bridge arm are connected to serve as the first end of the bridge arm conversion module 10, and the lower bridge arms of the first phase bridge arm, the second phase bridge arm and the third phase bridge arm are connected to serve as the second end of the bridge arm conversion module 10.

[0040] Further, the bus capacitor C and the power battery E also have a first end and a second end, and the first end of the power battery E can be the positive electrode thereof, and the second end of the power battery E can be the negative electrode thereof. The first ends of the bridge arm conversion module 10, the bus capacitor C and the power battery E are connected to each other, and the second ends of the bridge arm conversion module 10, the bus capacitor C and the power battery E are connected to each other.

[0041] Please continue to refer to Figure 1 , the motor module 20 is a three-phase motor, which has three phase windings, and each phase winding of the motor module 20 is connected to the neutral point of the corresponding bridge arm of the bridge arm conversion module 10. Specifically, the three phase windings of the motor module 20 are respectively a first phase winding L1 (U phase winding), a second phase winding L2 (V phase winding) and a third phase winding L3 (W phase winding), the first phase winding L1 is connected to the neutral point of the first phase bridge arm of the bridge arm conversion module 10, the second phase winding L2 is connected to the neutral point of the second phase bridge arm of the bridge arm conversion module 10, and the third phase winding L3 is connected to the neutral point of the third phase bridge arm of the bridge arm conversion module 10.

[0042] Further, the switch module includes at least a first switch K1 and a second switch K2. The first switch K1 is connected between any phase winding of the motor module 20 and the neutral point of the corresponding bridge arm of the bridge arm conversion module 10. Figure 1The first switch K1 is connected between the second phase winding L2 of the motor module 20 and the neutral point of the second phase bridge arm of the bridge arm conversion module 10, i.e., the first end of the first switch K1 is connected to the second phase winding L2 of the motor module 20, and the second end of the first switch K1 is connected to the neutral point of the second phase bridge arm of the bridge arm conversion module 10, but the first switch K1 can also be connected between the first phase winding L1 of the motor module 20 and the neutral point of the first phase bridge arm of the bridge arm conversion module 10, or connected between the third phase winding L3 of the motor module 20 and the neutral point of the third phase bridge arm of the bridge arm conversion module 10. The second switch K2 is connected between the first switch K1 and the first end of the power battery E, i.e., the first end of the second switch K2 is connected to the second end of the first switch K1, and the second end of the second switch K2 is connected to the first end of the power battery E.

[0043] In some embodiments, the switch module can further include a third switch K3 and a fourth switch K4, and the motor controller can further include a pre-charge load R. The third switch K3 is connected between the first end of the power battery E and the first end of the bus capacitor C, i.e., the first end of the third switch K3 is connected to the first end of the power battery E, and the second end of the third switch K3 is connected to the first end of the bus capacitor C; the fourth switch K4 is connected in parallel with the pre-charge load R in series, i.e., the first end of the fourth switch K4 is connected to the first end of the third switch K3, the second end of the fourth switch K4 is connected to the first end of the pre-charge load R, and the second end of the pre-charge load R is connected to the second end of the third switch K3.

[0044] In some embodiments, the motor controller further includes a first current detector A1 and a second current detector A2. The first current detector A1 is connected between the first phase winding L1 of the motor module 20 and the neutral point of the first phase bridge arm of the bridge arm conversion module 10, and is used to detect the U-phase current; the second current detector A2 is connected between the third phase winding L3 of the motor module 20 and the neutral point of the third phase bridge arm of the bridge arm conversion module 10, and is used to detect the W-phase current. Of course, if the position of the first switch K1 changes, the positions of the first current detector A1 and the second current detector A2 can also change accordingly, as long as the first current detector A1 and the second current detector A2 can detect the currents of the other two phases except the phase where the first switch K1 is located.

[0045] Further, the control module is configured to control the states of all switches in the switch module, i.e., to control the closing and opening of the first switch K1, the second switch K2, the third switch K3, and the fourth switch K4, so as to adjust the working mode of the motor controller and control the motor controller to enter the power output mode or the AC heating mode. When the motor controller enters the power output mode, power can be normally output, and when the motor controller enters the AC heating mode, the power battery E and the bus capacitor C can be cyclically charged and discharged, so as to heat by using the impedance of the power battery E itself. The first switch K1 and the second switch K2 only need to be added to the existing motor controller to realize the heating of the power battery E, and the motor module 20 does not need to be changed, so the cost is lower.

[0046] It can be understood that, since the application needs to cyclically charge and discharge between the power battery E and the bus capacitor C, the voltage across the bus capacitor C will increase during the charging of the bus capacitor C, and there is a risk of overvoltage, which may cause damage such as breakdown of the bus capacitor C. Therefore, the frequency and amplitude of the charging and discharging current need to be controlled to ensure that the voltage across the bus capacitor C does not exceed a threshold value; and the charging and discharging current is preferably the optimal charging and discharging current under the premise of not damaging the bus capacitor C, so as to improve the charging and discharging efficiency.

[0047] Therefore, the control module can also control the states of all power tubes in the bridge arm conversion module 10, i.e., to control the conduction and turn-off of the first power tube S1, the second power tube S2, the third power tube S3, the fourth power tube S4, the fifth power tube S5, and the sixth power tube S6, so as to adjust the state of the bridge arm conversion module 10 and match the working mode of the motor controller; at the same time, the control module can also control the duty cycles of the power tubes in the bridge arm conversion module 10, so as to adjust the frequency and amplitude of the charging and discharging current and make the charging and discharging current charge and discharge at a corresponding frequency and amplitude. Specifically, the control module can control the frequency of the charging and discharging current to be a target frequency, or the amplitude to be a target amplitude, and make the voltage across the bus capacitor C not exceed a threshold value, which will be described below.

[0048] Specifically, when the control module controls the first switch K1 to be closed and the second switch K2 to be opened, the motor controller can enter the power output mode. Figure 2 The equivalent circuit diagram of the motor controller in the power output mode provided by an embodiment of the application is shown in FIG. 2, which is combined with Figure 1 and Figure 2As shown, after the motor controller enters the power output mode, the control module controls the third switch K3 to open and the fourth switch K4 to close. The power battery E can pre-charge the bus capacitor C until the voltage across the bus capacitor C is equal to that of the power battery E, at which point the pre-charging is complete. After pre-charging is complete, the control module can control the third switch K3 to close and the fourth switch K4 to open, allowing the power battery E to output power to the motor module 20 normally through the bridge arm conversion module 10. It should be noted that in the power output mode, the first switch K1 is always closed and the second switch K2 is always open. After pre-charging is complete, the third switch K3 is always closed and the fourth switch K4 is always open.

[0049] Furthermore, when the control module controls the second switch K2 to close and the first switch K1 to open, the motor controller can enter the AC heating mode. Figure 3 An equivalent circuit diagram of a motor controller in AC heating mode provided in an embodiment of this application, combined with... Figure 1 and Figure 3 As shown, after the motor controller enters the AC heating mode, the control module controls the third switch K3 to open and the fourth switch K4 to close. The power battery E can then pre-charge the bus capacitor C until the voltage across the bus capacitor C is equal to that of the power battery E. Once pre-charging is complete, the control module can control both the third switch K3 and the fourth switch K4 to open, and the power battery E and the bus capacitor C begin a cyclic charging and discharging process. It should be noted that in the AC heating mode, the first switch K1 is always open, and the second switch K2 is always closed. After pre-charging is complete, the third switch K3 and the fourth switch K4 remain open.

[0050] The cyclic charging and discharging between the power battery E and the bus capacitor C includes the process of the power battery E discharging to the bus capacitor C (while the bus capacitor C is charging) and the process of the bus capacitor C discharging to the power battery E (while the power battery E is charging). These two processes are carried out alternately in the cycle, and the directions of the charging and discharging currents are opposite in the two processes.

[0051] Figure 4 This is an equivalent circuit diagram showing the discharge of a power battery E to a bus capacitor C according to an embodiment of this application. Figure 4 As shown, after the motor controller enters the AC heating mode and pre-charging is completed, the control module can control the power transistors of the upper arm of the bridge arm conversion module 10 (only the power transistors on the upper arms of the two bridge arms other than the phase where the first switch K1 is located need to be adjusted, namely the first power transistor S1 and the third power transistor S3) to be normally open. At this time, the motor module 20 and the bridge arm conversion module 10 form a boost circuit, and the power battery E discharges to the bus capacitor C. The direction of the charging and discharging current is as follows: Figure 4At this time, the control module can also adjust the duty cycles of the power tubes of the lower bridge arms of the bridge arm conversion module 10 (only the power tubes of the lower bridge arms of the two bridge arms other than the phase in which the first switch K1 is located, i.e., the fourth power tube S4 and the sixth power tube S6), so as to adjust the amplitude and frequency of the charging and discharging current.

[0052] Figure 5 An equivalent circuit diagram in which the bus capacitor C discharges the power battery E is provided for an embodiment of the present application. As shown in Figure 5 After the motor controller enters the AC heating mode and the pre-charging is completed, the control module can control the power tubes of the lower bridge arms of the bridge arm conversion module 10 (only the power tubes of the lower bridge arms of the two bridge arms other than the phase in which the first switch K1 is located, i.e., the fourth power tube S4 and the sixth power tube S6) to be always off. At this time, the motor module 20 and the bridge arm conversion module 10 form a buck circuit, the bus capacitor C discharges the power battery E, and the direction of the charging and discharging current is as shown by the arrow in Figure 5 At this time, the control module can also adjust the duty cycles of the power tubes of the lower bridge arms of the bridge arm conversion module 10 (only the power tubes of the lower bridge arms of the two bridge arms other than the phase in which the first switch K1 is located, i.e., the fourth power tube S4 and the sixth power tube S6), so as to adjust the amplitude and frequency of the charging and discharging current.

[0053] Based on this, the control method of the motor controller is also provided for an embodiment of the present application. Figure 6 A flowchart of the control method of the motor controller provided for an embodiment of the present application is shown in Figure 6 The control method of the motor controller includes the following steps.

[0054] Step S100: The control module controls the states of all the switches in the switch module to control the motor controller to enter the AC heating mode, and step S200 is performed.

[0055] Step S200: The power battery E and the bus capacitor C circulate at least once of charging and discharging, and step S300 is performed.

[0056] Step S300: It is judged whether the voltage across the bus capacitor C exceeds a threshold value. If yes, the frequency of the charging and discharging current is increased, and step S400 is performed. If no, the amplitude of the charging and discharging current is increased, and step S500 is performed.

[0057] Step S400: It is judged whether the frequency of the charging and discharging current exceeds a target frequency. If yes, the control module controls the frequency of the charging and discharging current to be the target frequency and the amplitude to be the current amplitude. If no, the frequency of the charging and discharging current is increased, and step S200 is returned.

[0058] Step S500: judging whether the amplitude of the charging and discharging current exceeds the target amplitude, if yes, the control module controls the amplitude of the charging and discharging current to be the target amplitude and the frequency to be the current frequency, if not, increasing the amplitude of the charging and discharging current, returning to step S200.

[0059] Figure 7 The specific flow chart of the control method of the motor controller provided by an embodiment of the present application is shown in combination with FIG. 1 and FIG. 2. Figure 6 and Figure 7 As shown in FIG. 1 and FIG. 2, first, step S100 is executed, when the control module receives a heating instruction, it indicates that the power battery E needs to be heated, at this time, the control module controls the state of all switches in the switch module to control the motor controller to enter the AC heating mode. Specifically, the control module first controls the second switch K2 to be closed and the first switch K1 to be opened, so that the motor controller can enter the AC heating mode, then the control module controls the third switch K3 to be opened and the fourth switch K4 to be closed, so that the power battery E can pre-charge the bus capacitor C, until the voltage across the bus capacitor C is equal to that of the power battery E, the pre-charge is completed, when the pre-charge is completed, the control module can control the third switch K3 and the fourth switch K4 to be opened, and the power battery E and the bus capacitor C start to cyclically charge and discharge.

[0060] Specifically, the heating instruction can be a heating instruction sent by the VCU (Vehicle Control Unit, vehicle controller) or the BMS (Battery Management System, battery management system), and can be determined according to the temperature of the power battery E. The heating instruction at least contains a target amplitude A cmd , wherein the target amplitude A cmd may be 90% to 100% of the maximum amplitude of the charging and discharging current.

[0061] Further, the charging and discharging current is a sine wave, when the power battery E and the bus capacitor C start to cyclically charge and discharge, the control module gives an initial amplitude A0 and an initial frequency f0 of the charging and discharging current, so as to control the initial waveform of the charging and discharging current to be I=A0sin(2*π*f0*t), at this time, the initial amplitude A0 can be an empirical value, for example, it can be 25% to 50% of the target amplitude A cmd , and the initial frequency f0 can be the minimum frequency of the charging and discharging current. That is, the amplitude and the frequency of the charging and discharging current are gradually adjusted from a smaller value upwards until the optimal amplitude and frequency combination is found.

[0062] Figure 8 The control logic diagram of the control module provided by an embodiment of the present application is shown in FIG. 3. Figure 8As shown, after the initial amplitude A0 and the initial frequency f0 are given, the control module can fit the target charge-discharge current I=A0sin(2*pi*f0*t) according to the initial amplitude A0 and the initial frequency f0, and subtract the target charge-discharge current I=A0sin(2*pi*f0*t) from the sum of all phase currents without the first switch K1 to obtain a deviation value, and perform PID (Proportional-Integral-Derivative) adjustment on the deviation value to obtain the target duty ratio of the corresponding power tube without the first switch K1. The control module controls the duty ratio of the corresponding power tube of the U phase and the W phase without the first switch K1 to be the target duty ratio, so that the frequency of the charge-discharge current is the initial frequency f0 and the amplitude is the initial amplitude A0. For example, the U phase and the W phase do not have the first switch K1, and the U phase current and the W phase current can be obtained through the first current detector A1 and the second current detector A2. The U phase current and the W phase current are input into the adder to obtain the sum of the U phase current and the W phase current. The target charge-discharge current I=A0sin(2*pi*f0*t) and the sum of the U phase current and the W phase current are input into the subtractor to obtain a deviation value. The deviation value is subjected to PID adjustment to obtain the target duty ratio of the corresponding power tube of the U phase and the W phase. Figure 4 The target duty ratio of the fourth power tube S4 and the sixth power tube S6 is obtained, Figure 5 The target duty ratio of the first power tube S1 and the third power tube S3 is obtained), and the control module controls the duty ratio of the corresponding power tube of the U phase and the W phase to be the target duty ratio, so that the frequency of the charge-discharge current is the initial frequency f0 and the amplitude is the initial amplitude A0. At this time, the charge-discharge current is the target charge-discharge current I=A0sin(2*pi*f0*t).

[0063] Next, step S200 is performed, and the power battery E and the bus capacitor C can be charged and discharged once in a cycle. The power battery E charges the bus capacitor C once, and the bus capacitor C charges the power battery E once, which is one cycle.

[0064] Step S300 is performed to determine whether the voltage Uc across the bus capacitor C exceeds the threshold value U Hi (Uc>U Hi )? If yes, it indicates that the voltage Uc across the bus capacitor C is too large, and the risk of damage to the bus capacitor C is great. At this time, the amplitude of the charge-discharge current cannot be increased, and only the frequency of the charge-discharge current can be increased (f ∆ ), and step S400 is performed; if not, it indicates that the voltage Uc across the bus capacitor C can be increased, and the risk of damage to the bus capacitor C is small. At this time, the amplitude of the charge-discharge current can be increased (A ∆ ), and step S500 is performed.

[0065] It should be noted that the threshold value U Hi may be an empirical value, for example, it can be 80%~90% of the maximum voltage that the bus capacitor C can withstand.

[0066] Step S400 is performed to determine whether the frequency of the charge-discharge current exceeds the target frequency f max The target frequency f max may be built into the control module, and the target frequency f max may be 90%~100% of the maximum frequency of the charge-discharge current. If yes, it indicates that the frequency of the charge-discharge current has approached the maximum value and cannot be increased any more. At this time, the control module can control the frequency of the charge-discharge current to be the target frequency f max , and the amplitude is the current amplitude. If no, it indicates that the frequency of the charge-discharge current has not approached the maximum value and can be increased. At this time, the frequency of the charge-discharge current can be increased (f ∆ ) and returned to step S200.

[0067] As shown in FIG. Figure 8 When it is determined that the frequency of the charge-discharge current exceeds the target frequency, the control module fits the target charge-discharge current I=Asin(2*π*f max *t) according to the target frequency f max and the current amplitude, and obtains a deviation value by subtracting the target charge-discharge current from the sum of all phase currents without the first switch K1. The deviation value is then PID adjusted to obtain the target duty cycle of the power tube corresponding to the phase without the first switch K1. The control module controls the duty cycle of the power tube corresponding to the phase without the first switch K1 to be the target duty cycle, so that the frequency of the charge-discharge current is the target frequency f max , and the amplitude is the current amplitude. For example, the phases without the first switch K1 are the U phase and the W phase. The U phase current and the W phase current can be obtained through the first current detector A1 and the second current detector A2, and input into an adder to obtain the sum of the U phase current and the W phase current. The target charge-discharge current I=Asin(2*π*f max *t) and the sum of the U phase current and the W phase current are input into a subtractor to obtain a deviation value. The deviation value is PID adjusted to obtain the target duty cycle of the power tube corresponding to the U phase and the W phase. In Figure 4 , the target duty cycles of the fourth power tube S4 and the sixth power tube S6 are obtained, and in Figure 5 , the target duty cycles of the first power tube S1 and the third power tube S3 are obtained. The control module controls the duty cycles of the power tubes corresponding to the U phase and the W phase to be the target duty cycles, so that the frequency of the charge-discharge current is the target frequency f max , and the amplitude is the current amplitude. At this time, the charge-discharge current is the target charge-discharge current I=Asin(2*π*f max *t).

[0068] Step S500 is performed to determine whether the amplitude of the charging / discharging current exceeds the target amplitude A cmd . If yes, it indicates that the amplitude of the charging / discharging current has reached the ideal value, and the control module controls the amplitude of the charging / discharging current to be the target amplitude A cmd and the frequency to be the current frequency. If no, it indicates that the amplitude of the charging / discharging current has not reached the ideal value, and the amplitude of the charging / discharging current can be increased, and the process returns to step S200.

[0069] As shown in FIG. 5, Figure 8 , when it is determined that the amplitude of the charging / discharging current exceeds the target amplitude, the control module fits the target charging / discharging current I=A cmd sin(2*π*f*t) according to the target amplitude A cmd and the current frequency, and obtains a deviation value by subtracting the target charging / discharging current I=A cmd sin(2*π*f*t) from the sum of all phase currents without the first switch K1, and performs PID adjustment on the deviation value to obtain the target duty ratio of the power tube corresponding to the phase without the first switch K1. The control module controls the duty ratio of the power tube corresponding to the phase without the first switch K1 to be the target duty ratio, so that the amplitude of the charging / discharging current is the target amplitude A cmd and the frequency is the current frequency. For example, the phases without the first switch K1 are the U phase and the W phase. The U phase current and the W phase current can be obtained through the first current detector A1 and the second current detector A2, and input into the adder to obtain the sum of the U phase current and the W phase current. The target charging / discharging current I=A cmd sin(2*π*f*t) and the sum of the U phase current and the W phase current are input into the subtractor to obtain the deviation value, and the deviation value is subjected to PID adjustment to obtain the target duty ratio of the power tube corresponding to the U phase and the W phase. In Figure 4 , the target duty ratios of the fourth power tube S4 and the sixth power tube S6 are obtained, and in Figure 5 , the target duty ratios of the first power tube S1 and the third power tube S3 are obtained. The control module controls the duty ratio of the power tube corresponding to the U phase and the W phase to be the target duty ratio, so that the amplitude of the charging / discharging current is the target amplitude A cmd and the frequency is the current frequency. At this time, the charging / discharging current is the target charging / discharging current I=A cmd sin(2*π*f*t).

[0070] It should be noted that when the bus capacitor C is charging, the voltage across it increases; when it is discharging, the voltage decreases. A higher amplitude of the charging / discharging current results in a higher maximum voltage across the bus capacitor C, and vice versa. Therefore, the amplitude of the charging / discharging current is positively correlated with the maximum voltage across the bus capacitor C. While increasing the amplitude of the charging / discharging current increases charging / discharging efficiency, it also leads to a higher maximum voltage across the bus capacitor C, increasing the risk of damage. Furthermore, a higher frequency of the charging / discharging current and a shorter charging / discharging time result in a lower maximum voltage across the bus capacitor C, while a lower frequency and a longer charging / discharging time result in a higher maximum voltage. However, the frequency of the charging / discharging current should not be increased indefinitely (typically 1kHz~10kHz). Considering the carrier ratio, a lower frequency is actually better. A lower frequency results in a better sinusoidal waveform of the charging / discharging current and a lower motor temperature rise. In other words, charging and discharging current at low frequency and with large amplitude is most beneficial for the temperature rise of the power battery E. However, large amplitude current can easily burn out the bus capacitor C, while low frequency can easily charge the voltage of the bus capacitor C to a very high level. In this application, the voltage Uc across the bus capacitor C is always less than the threshold U. Hi This can prevent damage to the bus capacitor C. Furthermore, after adjustment, the amplitude of the charging and discharging current can reach the target amplitude A. cmd Alternatively, the frequency of the charging and discharging current can be the target frequency fmax. At least one of the two conditions must be met for it to be the optimal combination. Therefore, the charging and discharging current can be used for charging and discharging, thereby improving the heating efficiency of the power battery E by ensuring that the bus capacitor C is not damaged.

[0071] Of course, the control method can also include the control module controlling the first switch K1 to close and the second switch K2 to open, so that the motor controller enters the power output mode. For example... Figure 2 As shown, after the motor controller enters the power output mode, the control module controls the third switch K3 to open and the fourth switch K4 to close. The power battery E can precharge the bus capacitor C until the voltage across the bus capacitor C is equal to that of the power battery E. When the precharging is complete, the control module can control the third switch K3 to close and the fourth switch K4 to open. The power battery E can then output power to the motor module 20 through the bridge arm conversion module 10.

[0072] One embodiment of this application also provides a new energy vehicle, including the aforementioned motor controller. The new energy vehicle can be a vehicle, ship, or aircraft, etc., which will not be listed here.

[0073] In summary, this embodiment provides a motor controller and its control method, and a new energy vehicle. The motor controller includes a bridge arm switching module 10, a bus capacitor C, a motor module 20, a control module, and a switch module. The switch module includes at least a first switch K1 and a second switch K2. The bridge arm switching module 10, the bus capacitor C, and the first terminal of the power battery E are connected to each other, and the second terminals of the bridge arm switching module 10, the bus capacitor C, and the power battery E are connected to each other. Each phase winding of the motor module 20 is connected to the neutral point of the corresponding bridge arm of the bridge arm switching module 10. The first switch K1 is connected between any phase winding of the motor module 20 and the neutral point of the corresponding bridge arm of the bridge arm switching module 10, and the second switch K2 is connected between the first switch K1 and the first terminal of the power battery E. The control method includes: Step S100: The control module controls the state of all switches in the switch module to control the motor arm switching module. The controller enters AC heating mode and executes step S200; Step S200: The power battery E and the bus capacitor C cycle through charging and discharging at least once, and then executes step S300; Step S300: Determine whether the voltage across the bus capacitor C exceeds the threshold. If yes, increase the frequency of the charging and discharging current and execute step S400. If no, increase the amplitude of the charging and discharging current and execute step S500; Step S400: Determine whether the frequency of the charging and discharging current exceeds the target frequency. If yes, the control module controls the frequency of the charging and discharging current to the target frequency and the amplitude to the current amplitude. If no, increase the frequency of the charging and discharging current and return to step S200; Step S500: Determine whether the amplitude of the charging and discharging current exceeds the target amplitude. If yes, the control module controls the amplitude of the charging and discharging current to the target amplitude and the frequency to the current frequency. If no, increase the amplitude of the charging and discharging current and return to step S200. This application only requires adding a first switch K1 and a second switch K2 to heat the power battery E without changing the structure of the motor module 20. The improvement is small and the cost is lower. Furthermore, it can ensure that the charging and discharging is carried out with the optimal charging and discharging current without damaging the bus capacitor C, thus improving the heating efficiency.

[0074] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0075] It should also be noted that although preferred embodiments have been disclosed above, these embodiments are not intended to limit this application. Any person skilled in the art can make many possible variations and modifications to the technical solutions of this application, or modify them into equivalent embodiments, without departing from the scope of the technical solutions of this application. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this application, without departing from the content of the technical solutions of this application, shall still fall within the scope of protection of the technical solutions of this application.

[0076] It should also be understood that, unless otherwise specified or indicated, the terms “first,” “second,” “third,” etc., in the specification are used only to distinguish the various components, elements, and steps in the specification, and not to indicate the logical or sequential relationships between the various components, elements, and steps.

[0077] Furthermore, it should be recognized that the terminology described herein is used only to describe particular embodiments and is not intended to limit the scope of this application. It must be noted that the singular forms “a” and “an” as used herein include plural bases unless the context clearly indicates the opposite. For example, a reference to “a step” or “an apparatus” means a reference to one or more steps or apparatuses, and may include secondary steps and secondary apparatuses. All conjunctions used should be understood in the broadest sense. Also, the word “or” should be understood as having the definition of logical “or”, not logical “exclusive OR”, unless the context clearly indicates the opposite. Furthermore, implementations of the methods and / or devices in the embodiments of this application may include performing selected tasks manually, automatically, or in combination.

Claims

1. A control method for a motor controller, characterized in that, The motor controller includes a bridge arm conversion module, a bus capacitor, a motor module, a control module, and a switch module. The switch module includes at least a first switch and a second switch. The bridge arm conversion module, the bus capacitor, and the first terminal of the power battery are connected to each other. The second terminal of the bridge arm conversion module, the bus capacitor, and the power battery are connected to each other. Each phase winding of the motor module is connected to the neutral point of the corresponding bridge arm of the bridge arm conversion module. The first switch is connected between any phase winding of the motor module and the neutral point of the corresponding bridge arm of the bridge arm conversion module. The second switch is connected between the first switch and the first terminal of the power battery. The control method includes: Step S100: The control module controls the state of all switches in the switch module to control the motor controller to enter the AC heating mode, and executes step S200; Step S200: The power battery and the bus capacitor are charged and discharged at least once, and then step S300 is executed; Step S300: Determine whether the voltage across the bus capacitor exceeds the threshold. If yes, increase the frequency of the charging and discharging current and proceed to step S400. If no, increase the amplitude of the charging and discharging current and proceed to step S500. Step S400: Determine whether the frequency of the charging and discharging current exceeds the target frequency. If yes, the control module controls the frequency of the charging and discharging current to the target frequency and the amplitude to the current amplitude. If no, increase the frequency of the charging and discharging current and return to step S200. Step S500: Determine whether the amplitude of the charging and discharging current exceeds the target amplitude. If yes, the control module controls the amplitude of the charging and discharging current to be the target amplitude and the frequency to be the current frequency. If no, increase the amplitude of the charging and discharging current and return to step S200.

2. The control method of the motor controller as described in claim 1, characterized in that, The switch module further includes a third switch and a fourth switch, and the motor controller further includes a pre-charge load. The third switch is connected between the first terminal of the power battery and the first terminal of the bus capacitor. The fourth switch is connected in series with the pre-charge load and then in parallel with the third switch. The step of the control module controlling the state of all switches in the switch module to control the motor controller to enter the AC heating mode includes: The control module controls the second switch to close and the first switch to open, the motor controller enters the AC heating mode, the control module controls the third switch to open and the fourth switch to close, the power battery pre-charges the bus capacitor, after the pre-charging is completed, the control module controls both the third and fourth switches to open, and the power battery and the bus capacitor begin to cycle through charging and discharging.

3. The control method of the motor controller as described in claim 2, characterized in that, The control method further includes: The control module controls the first switch to close and the second switch to open, the motor controller enters the power output mode. After the motor controller enters the power output mode, the control module controls the third switch to open and the fourth switch to close, the power battery pre-charges the bus capacitor. After the pre-charging is completed, the control module controls the third switch to close and the fourth switch to open.

4. The control method of the motor controller as described in claim 1, characterized in that, After the motor controller enters the AC heating mode, the control module controls the power transistor of the upper arm of the bridge arm conversion module to be normally open, and the power battery discharges to the bus capacitor. The control module also adjusts the duty cycle of the power transistor of the lower arm of the bridge arm conversion module to adjust the amplitude and frequency of the charging and discharging current; and, The control module controls the power transistor of the lower arm of the bridge arm conversion module to be normally off, and the bus capacitor discharges to the power battery. The control module also adjusts the duty cycle of the power transistor of the upper arm of the bridge arm conversion module to adjust the amplitude and frequency of the charging and discharging current.

5. The control method of the motor controller as described in claim 4, characterized in that, After determining that the frequency of the charging and discharging current exceeds the target frequency, the control module fits the target charging and discharging current according to the target frequency and the current amplitude, and calculates the difference between the target charging and discharging current and the sum of the currents of all phases without the first switch to obtain the deviation value. The deviation value is then adjusted by PID control to obtain the target duty cycle of the corresponding power transistor without the first switch. The control module controls the duty cycle of the corresponding power transistor without the first switch to be the target duty cycle, so that the frequency of the charging and discharging current is the target frequency and the amplitude is the current amplitude.

6. The control method of the motor controller as described in claim 4, characterized in that, After determining that the amplitude of the charging and discharging current exceeds the target amplitude, the control module fits the target charging and discharging current based on the target amplitude and the current frequency, and calculates the difference between the target charging and discharging current and the sum of the currents of all phases without the first switch to obtain a deviation value. The deviation value is then adjusted using PID control to obtain the target duty cycle of the corresponding power transistor without the first switch. The control module controls the duty cycle of the corresponding power transistor without the first switch to be the target duty cycle, so that the amplitude of the charging and discharging current is the target amplitude and the frequency is the current frequency.

7. The control method for the motor controller as described in any one of claims 1 to 6, characterized in that, When the control module receives a heating command, the control module controls the state of all switches in the switch module to control the motor controller to enter the AC heating mode. The heating command includes at least the target amplitude, which is 90% to 100% of the maximum amplitude of the charging and discharging current; and / or, the target frequency is built into the control module, which is 90% to 100% of the maximum frequency of the charging and discharging current.

8. The control method of the motor controller as described in any one of claims 1 to 6, characterized in that, When the power battery and the bus capacitor begin to cycle through charging and discharging, the initial amplitude of the charging and discharging current is 25% to 50% of the target amplitude, and the initial frequency of the charging and discharging current is the minimum frequency of the charging and discharging current.

9. A motor controller, characterized in that, It includes a bridge arm conversion module, a bus capacitor, a motor module, a control module, and a switch module, wherein the switch module includes at least a first switch and a second switch; The first end of the bridge arm conversion module, the bus capacitor, and the power battery are connected to each other, the second end of the bridge arm conversion module, the bus capacitor, and the power battery are connected to each other, and each phase winding of the motor module is connected to the neutral point of the corresponding bridge arm of the bridge arm conversion module. The first switch is connected between any winding of the motor module and the neutral point of the corresponding arm of the arm conversion module; the second switch is connected between the first switch and the first terminal of the power battery; and, The control module is used to control the state of all switches in the switch module to control the motor controller to enter the power output mode or AC heating mode. In the AC heating mode, the power battery and the bus capacitor cycle through charging and discharging. The control module also controls the frequency of the charging and discharging current to the target frequency or the amplitude to the target amplitude, and ensures that the voltage across the bus capacitor does not exceed the threshold.

10. A new energy transportation vehicle, characterized in that, Includes the motor controller as described in claim 9.

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