Motor controller, control method thereof and new energy vehicle

Abstract

The invention provides a motor controller, 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 switch module, the control method comprises the following steps: after the motor controller enters an alternating current heating mode, judging whether the voltage at two ends of the bus capacitor exceeds a threshold value, if yes, starting the motor module; 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 till the frequency of the charging and discharging current exceeds the target frequency or whether the amplitude exceeds the target amplitude or not, and 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. The power battery can be heated only by adding the first switch and the second switch, the structure of the motor module does not need to be changed, improvement is small, cost is lower, and it can be guaranteed that charging and discharging are conducted with the optimal charging and discharging current on the basis that the bus capacitor is not damaged.

Description

Technical Field

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

[0002] With the widespread use of new energy sources, power batteries are finding applications as power sources in various fields. However, the performance of power batteries can be affected by the environment in which they are used. For example, in low-temperature environments, power batteries face problems such as difficulty charging, low discharge efficiency, and decreased cycle life. To ensure their use in low-temperature environments, power batteries must be heated before use. However, existing heating methods are complex and costly. Summary of the Invention

[0003] In view of this, the embodiments of the present application are dedicated to providing a motor controller and a control method thereof, and a new energy vehicle, so as to solve the problem that the solutions for heating power batteries in the prior art are relatively complex and costly.

[0004] On one hand, the present application provides a control method for a motor controller, the motor controller including a bridge arm conversion module, a bus capacitor, a motor module, a control module, and a switch module, the switch module including 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, 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 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 includes: Step S100: the control module controls the states of all switches in the switch module to control the motor controller to enter the AC heating mode, and then executes step S200; Step S200: The power battery and the bus capacitor are charged and discharged in a cycle at least once, and then step S300 is executed; Step S300: determining whether the voltage across the bus capacitor exceeds a threshold; if so, increasing the frequency of the charge / discharge current and executing step S400; if not, increasing the amplitude of the charge / discharge current and executing step S500; Step S400: determining whether the frequency of the charge and discharge current exceeds the target frequency; if so, the control module controls the frequency of the charge and discharge current to be the target frequency and the amplitude to be the current amplitude; if not, increasing the frequency of the charge and discharge current, and returning to step S200; Step S500: Determine whether the amplitude of the charge and discharge current exceeds the target amplitude. If so, the control module controls the amplitude of the charge and discharge current to be the target amplitude and the frequency to be the current frequency. If not, increase the amplitude of the charge and discharge current and return to step S200.

[0005] In some embodiments, the switch module further includes a third switch and a fourth switch, the motor controller further includes a pre-charge 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 series with the pre-charge load and then in parallel with the third switch; the control module controls the states of all switches in the switch module to control the motor controller to enter the AC heating mode, including the following steps: The control module controls the second switch to be closed and the first switch to be opened, and the motor controller enters the AC heating mode. The control module controls the third switch to be opened and the fourth switch to be closed, and the power battery pre-charges the bus capacitor. After the pre-charging is completed, the control module controls both the third switch and the fourth switch to be opened, and the power battery and the bus capacitor begin to cycle charge and discharge.

[0006] In some embodiments, the control method further includes: The control module controls the first switch to be closed and the second switch to be opened, and 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 be opened and the fourth switch to be closed, and 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.

[0007] In some embodiments, after the motor controller enters the AC heating mode, the control module controls the power tube of the upper bridge 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 tube of the lower bridge 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 tube of the lower bridge arm of the bridge arm conversion module to be normally closed, and the bus capacitor discharges to the power battery. The control module also 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 charging and discharging current.

[0008] In some embodiments, after determining that the frequency of the charge and discharge current exceeds the target frequency, the control module fits the target charge and discharge current according to the target frequency and the current amplitude, and subtracts the target charge and discharge current from the sum of all phase currents without the first switch to obtain a deviation value, and performs PID adjustment on the deviation value to obtain a target duty cycle of the power tube corresponding to the first switch not being set. The control module controls the duty cycle of the power tube corresponding to the first switch not being set to the target duty cycle, so that the frequency of the charge and discharge current is the target frequency and the amplitude is the current amplitude.

[0009] In some embodiments, after determining that the amplitude of the charge and discharge current exceeds the target amplitude, the control module fits the target charge and discharge current according to the target amplitude and the current frequency, and subtracts the target charge and discharge current from the sum of all phase currents without the first switch to obtain a deviation value, and performs PID adjustment on the deviation value to obtain a target duty cycle of the power tube corresponding to the first switch not being set. The control module controls the duty cycle of the power tube corresponding to the first switch not being set to the target duty cycle, so that the amplitude of the charge and discharge current is the target amplitude and the frequency is the current frequency.

[0010] In some embodiments, when the control module receives a heating instruction, the control module controls the states of all switches in the switch module to control the motor controller to enter the AC heating mode, and the heating instruction includes at least the target amplitude, and the target amplitude is 90%~100% of the maximum amplitude of the charge and discharge current; and / or, the target frequency is built into the control module, and the target frequency is 90%~100% of the maximum frequency of the charge and discharge current.

[0011] In some embodiments, when the power battery and the bus capacitor begin to cycle charge and discharge, the initial amplitude of the charge and discharge current is 25% to 50% of the target amplitude, and the initial frequency of the charge and discharge current is the minimum frequency of the charge and discharge current.

[0012] An embodiment of the present application further provides a motor controller, comprising a bridge arm conversion module, a bus capacitor, a motor module, a control module, and a switch module, wherein the switch module comprises at least a first switch and a second switch; The bridge arm conversion module, the bus capacitor and the first end of the power battery are connected to each other, the bridge arm conversion module, the bus capacitor and the second end of 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 one 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; and The control module is used to control the states of all switches in the switch module to control the motor controller to enter the power output mode or the AC heating mode. In the AC heating mode, the power battery and the bus capacitor are cyclically charged and discharged. The control module also controls the frequency of the charge and discharge current to be a target frequency, or the amplitude to be a target amplitude, and ensures that the voltage across the bus capacitor does not exceed a threshold.

[0013] An embodiment of the present application further provides a new energy vehicle, including the motor controller.

[0014] The present application provides a motor controller and a control method thereof, and a new energy vehicle, 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 end of the power battery are connected to each other, the bridge arm conversion module, the bus capacitor and the second end of 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 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 includes: step S100: the control module controls the states of all switches in the switch module to control the motor controller to enter the AC heating mode, and executes Perform step S200; Step S200: The power battery and the bus capacitor are charged and discharged in a cycle at least once, and step S300 is executed; Step S300: Determine whether the voltage across the bus capacitor exceeds the threshold value, if so, increase the frequency of the charge and discharge current, and execute step S400; if not, increase the amplitude of the charge and discharge current, and execute step S500; Step S400: Determine whether the frequency of the charge and discharge current exceeds the target frequency, if so, the control module controls the frequency of the charge and discharge current to be the target frequency, and the amplitude to be the current amplitude, if not, increase the frequency of the charge and discharge current, and return to step S200; Step S500: Determine whether the amplitude of the charge and discharge current exceeds the target amplitude, if so, the control module controls the amplitude of the charge and discharge current to be the target amplitude, and the frequency to be the current frequency, if not, increase the amplitude of the charge and discharge current, and return to step S200. The present application only needs to add the first switch and the second switch to achieve heating of the power battery, without changing the structure of the motor module. The improvement is small and the cost is lower. It can also ensure that the charging and discharging is performed with the optimal charging and discharging current without damaging the bus capacitor, thereby improving the heating efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A circuit diagram of a motor controller provided in accordance with an embodiment of the present application.

[0016] Figure 2 This is an equivalent circuit diagram of a motor controller provided in an embodiment of the present application in power output mode.

[0017] Figure 3 This is an equivalent circuit diagram of a motor controller provided in an embodiment of the present application in AC heating mode.

[0018] Figure 4 This is an equivalent circuit diagram of a power battery discharging to a bus capacitor according to an embodiment of the present application.

[0019] Figure 5 This is an equivalent circuit diagram of the bus capacitor discharging to the power battery provided in one embodiment of the present application.

[0020] Figure 6 This is a flowchart of a control method for a motor controller provided in one embodiment of the present application.

[0021] Figure 7 This is a specific flow chart of a control method for a motor controller provided in one embodiment of the present application.

[0022] Figure 8 This is a control logic diagram of a control module provided in one embodiment of the present application.

[0023] Wherein, the accompanying drawings are marked as follows: 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-precharge 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

[0024] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0025] As previously mentioned, power batteries experience difficulty charging, low discharge efficiency, and reduced cycle life at low temperatures. Therefore, they typically need to be heated before operation. Existing technologies require connecting a battery to the neutral point of the motor to achieve heating, which requires significant modifications to the motor and is costly.

[0026] The technical solution of the embodiment of the present application is applicable to the application scenario of heating and discharging the power battery in the new energy vehicle. The present application provides a motor controller and a control method thereof. Figure 1 A circuit diagram of a motor controller provided in one embodiment of the present application is shown in FIG. Figure 1 As shown, the motor controller includes a bridge arm conversion module 10, a bus capacitor C, a motor module 20, a control module and a switch module, wherein the control module is not in Figure 1 Shown in.

[0027] Specifically, the bridge arm conversion module 10 has three-phase bridge arms, namely the first phase bridge arm, the second phase bridge arm and the third phase bridge arm. Each phase bridge arm has an upper bridge arm and a lower bridge arm, and a power tube is respectively provided on the upper and lower bridge arms. 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 S5 and a diode connected in parallel with the sixth power tube S5. power tube S6 and a diode connected in parallel with the sixth power tube S6; the midpoint of the first phase bridge arm is the neutral point connecting the first power tube S1 and the fourth power tube S4, the midpoint of the second phase bridge arm is the neutral point connecting the second power tube S2 and the fifth power tube S5, and the midpoint 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 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 as the second end of the bridge arm conversion module 10.

[0028] Furthermore, the bus capacitor C and the power battery E also have a first end and a second end. The first end of the power battery E can be its positive electrode, and the second end of the power battery E can be its negative electrode. The bridge arm conversion module 10, the bus capacitor C, and the first end of the power battery E are connected to each other, and the bridge arm conversion module 10, the bus capacitor C, and the second end of the power battery E are connected to each other.

[0029] Please continue reading Figure 1 The motor module 20 is a three-phase motor having three-phase windings. 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 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.

[0030] Furthermore, the switch module includes at least a first switch K1 and a second switch K2 . The first switch K1 is connected between any winding of the motor module 20 and the neutral point of the corresponding bridge arm of the bridge arm conversion module 10 . Figure 1The figure shows that the 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. That is, 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. However, this should not be limiting. The first switch K1 may 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 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. That is, 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.

[0031] In some embodiments, the switch module may further include a third switch K3 and a fourth switch K4, and the motor controller may 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, that is, 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 series with the pre-charge load R and then connected in parallel to the third switch K3, that is, 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.

[0032] 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 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 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 be changed accordingly. The first current detector A1 and the second current detector A2 only need to be able to detect the currents of the other two phases besides the phase in which the first switch K1 is located.

[0033] 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.

[0034] 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, under the premise of not damaging the bus capacitor C, the charging and discharging current is preferably optimized to improve the charging and discharging efficiency.

[0035] 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 cycle of each power tube 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.

[0036] 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. 4. 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, and 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, and the pre-charging is completed. When the pre-charging is completed, the control module can control the third switch K3 to close and the fourth switch K4 to open, and the power battery E can normally output power to the motor module 20 through the bridge arm conversion module 10. It should be noted that in the power output mode of the motor controller, the first switch K1 is always closed and the second switch K2 is always open. After the pre-charging is completed, the third switch K3 is always closed and the fourth switch K4 is always open.

[0037] Furthermore, when the control module controls the second switch K2 to be closed and the first switch K1 to be open, the motor controller may enter the AC heating mode. Figure 3 The equivalent circuit diagram of the motor controller provided in an embodiment of the present application in the AC heating mode is 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 be disconnected and the fourth switch K4 to be closed. 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, and the pre-charging is completed. After the pre-charging is completed, the control module can control both the third switch K3 and the fourth switch K4 to be disconnected, and the power battery E and the bus capacitor C begin to cycle charge and discharge. It should be noted that in the AC heating mode, the first switch K1 of the motor controller is always disconnected, and the second switch K2 is always closed. After the pre-charging is completed, the third switch K3 is always disconnected, and the fourth switch K4 is always disconnected.

[0038] The cyclic charge and discharge between the power battery E and the bus capacitor C includes the process of the power battery E discharging to the bus capacitor C (at this time the bus capacitor C is charging) and the process of the bus capacitor C discharging to the power battery E (at this time the power battery E is charging). These two processes are carried out alternately, and the directions of the charge and discharge currents in the two processes are opposite.

[0039] Figure 4 This is an equivalent circuit diagram of a power battery E discharging to a bus capacitor C according to an embodiment of the present application. Figure 4 As shown, the motor controller enters the AC heating mode and after pre-charging is completed, the control module can control the power tubes of the upper bridge arm of the bridge arm conversion module 10 (only the power tubes on the upper bridge arms of the two bridge arms other than the phase where the first switch K1 is located need to be adjusted, that is, the first power tube S1 and the third power tube S3) to be normally open. At this time, the motor module 20 and the bridge arm conversion module 10 form a boost circuit (boost circuit), and the power battery E discharges to the bus capacitor C. The direction of the charge and discharge current is as follows Figure 4At this time, the control module can also adjust the duty cycle of the power tube of the lower bridge arm of the bridge arm conversion module 10 (only the power tubes on the lower bridge arms of the two bridge arms other than the phase where the first switch K1 is located need to be adjusted, namely, the fourth power tube S4 and the sixth power tube S6), so as to adjust the amplitude and frequency of the charge and discharge current.

[0040] Figure 5 This is an equivalent circuit diagram of the bus capacitor C discharging to the power battery E provided in one embodiment of the present application. Figure 5 As shown, the motor controller enters the AC heating mode and after pre-charging is completed, the control module can control the power tube of the lower bridge arm of the bridge arm conversion module 10 (only the power tubes on the lower bridge arms of the two bridge arms other than the phase where the first switch K1 is located need to be adjusted, that is, the fourth power tube S4 and the sixth power tube S6) to be normally closed. At this time, the motor module 20 and the bridge arm conversion module 10 form a step-down circuit (buck circuit), and the bus capacitor C discharges to the power battery E. The direction of the charge and discharge current is as follows Figure 5 At this time, the control module can also adjust the duty cycle of the power transistors of the upper bridge arm of the bridge arm conversion module 10 (only the power transistors on the upper bridge 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), thereby adjusting the amplitude and frequency of the charge and discharge current.

[0041] Based on this, an embodiment of the present application further provides a control method for the above-mentioned motor controller. Figure 6 This is a flow chart of a control method for a motor controller provided in one embodiment of the present application, such as Figure 6 As shown, the control method of the motor controller includes: Step S100: The control module controls the states of all switches in the switch module to control the motor controller to enter the AC heating mode, and then executes step S200; Step S200: The power battery E and the bus capacitor C are charged and discharged in a cycle at least once, and then step S300 is executed; Step S300: Determine whether the voltage across the bus capacitor C exceeds a threshold value. If so, increase the frequency of the charge and discharge current and execute step S400. If not, increase the amplitude of the charge and discharge current and execute step S500. Step S400: determining whether the frequency of the charge and discharge current exceeds the target frequency. If so, the control module controls the frequency of the charge and discharge current to be the target frequency and the amplitude to be the current amplitude. If not, the frequency of the charge and discharge current is increased, and the process returns to step S200. Step S500: Determine whether the amplitude of the charge and discharge current exceeds the target amplitude. If so, the control module controls the amplitude of the charge and discharge current to be the target amplitude and the frequency to be the current frequency. If not, increase the amplitude of the charge and discharge current and return to step S200.

[0042] Figure 7 A specific flow chart of the control method of the motor controller provided in one embodiment of the present application, combined with Figure 6 and Figure 7 As shown, 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 status 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 close and the first switch K1 to open, and the motor controller can enter the AC heating mode. After that, the control module controls the third switch K3 to open and the fourth switch K4 to close, and 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. When the pre-charging is completed, the control module can control the third switch K3 and the fourth switch K4 to open, and the power battery E and the bus capacitor C begin to circulate charge and discharge.

[0043] Specifically, the heating instruction can be a heating instruction issued by the VCU (Vehicle Control Unit) or BMS (Battery Management System), which can follow the temperature of the power battery E to determine whether to heat it. The heating instruction at least includes the target amplitude A cmd , where the target amplitude A cmd It can be 90% to 100% of the maximum amplitude of the charge and discharge current.

[0044] Furthermore, the charge and discharge current is a sine wave. When the power battery E and the bus capacitor C start to cycle charge and discharge, the control module will give the initial amplitude A0 and initial frequency f0 of the charge and discharge current, thereby controlling the initial waveform of the charge and discharge current to be I=A0sin(2*π*f0*t). At this time, the initial amplitude A0 can be an empirical value, for example, the target amplitude A cmd The initial frequency f0 can be 25% to 50% of the charge and discharge current. In other words, the amplitude and frequency of the charge and discharge current are gradually adjusted upward from a small value until the optimal amplitude and frequency combination is found.

[0045] Figure 8 This is a control logic diagram of a control module provided in one embodiment of the present application. Figure 8As shown, after the initial amplitude A0 and the initial frequency f0 are given, the control module can fit the target charge and discharge current I=A0sin(2*π*f0*t) based on the initial amplitude A0 and the initial frequency f0, and subtract the target charge and discharge current I=A0sin(2*π*f0*t) from the sum of all phase currents without the first switch K1 to obtain a deviation value. The deviation value is then PID (Proportional-Integral-Derivative) adjusted to obtain a target duty cycle of the power transistor corresponding to the power transistor without the first switch K1. The control module controls the duty cycle of the power transistor corresponding to the power transistor without the first switch K1 to the target duty cycle, so that the frequency of the charge and discharge current is the initial frequency f0 and the amplitude is the initial amplitude A0. For example, the phases where the first switch K1 is not set are U phase and W phase. The U phase current and 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 and discharge current I=A0sin(2*π*f0*t) and the sum of the U phase current and the W phase current are input into the subtractor to obtain the 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 ( Figure 4 The target duty cycle of the fourth power tube S4 and the sixth power tube S6 is obtained. Figure 5 In the figure, the target duty cycle of the first power tube S1 and the third power tube S3 is obtained). The control module controls the duty cycle of the power tubes corresponding to the U phase and the W phase to be the target duty cycle, so that the frequency of the charge and discharge current is the initial frequency f0, and the amplitude is the initial amplitude A0. At this time, the charge and discharge current is the target charge and discharge current I=A0sin(2*π*f0*t).

[0046] Next, step S200 is executed, and the power battery E and the bus capacitor C can be charged and discharged once. The power battery E charges the bus capacitor C once + the bus capacitor C charges the power battery E once, which is one cycle.

[0047] Execute step S300 to determine whether the voltage Uc across the bus capacitor C exceeds the threshold U Hi (Uc>U Hi ? ), if so, it indicates that the voltage Uc across the bus capacitor C is too large, and the bus capacitor C is at great risk of damage. At this time, the amplitude of the charge and discharge current cannot be increased any further, and the only option is to increase the frequency of the charge and discharge current (increase f ∆ ), and execute step S400; 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 and discharge current can be increased (increase A ∆ ), and execute step S500.

[0048] It should be noted that the threshold U Hi It can be an empirical value, for example, 80% to 90% of the maximum voltage that the bus capacitor C can withstand.

[0049] Execute step S400 to determine whether the frequency of the charge and discharge current exceeds the target frequency f max , target frequency f max Can be built into the control module, the target frequency f max It can be 90%~100% of the maximum frequency of the charge and discharge current. If so, it means that the frequency of the charge and discharge current has approached the maximum value and cannot be increased any further. At this time, the control module can control the frequency of the charge and discharge current to be the target frequency f max , the amplitude is the current amplitude; if not, it means that the frequency of the charge and discharge current has not yet approached the maximum value and can be increased. At this time, the frequency of the charge and discharge current can be increased (increase f ∆ ) and returns to step S200.

[0050] Combine Figure 8 As shown, when it is determined that the frequency of the charge and discharge current exceeds the target frequency, the control module max And the current amplitude is fitted to the target charge and discharge current I=Asin(2*π*f max *t), and the target charge and discharge current is subtracted from the sum of all phase currents without the first switch K1 to obtain a deviation value, and the deviation value is PID-adjusted to obtain the target duty cycle of the power tube corresponding to the first switch K1. The control module controls the duty cycle of the power tube corresponding to the first switch K1 to be the target duty cycle, so that the frequency of the charge and discharge current is the target frequency f max , the amplitude is the current amplitude. For example, if the phases where the first switch K1 is not set are U phase and W phase, the U phase current and W phase current can be obtained through the first current detector A1 and the second current detector A2. The U phase current and 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 and 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 the subtractor to obtain the deviation value, and the deviation value is adjusted by PID to obtain the target duty cycle of the power tube corresponding to the U-phase and W-phase ( Figure 4 The target duty cycle of the fourth power tube S4 and the sixth power tube S6 is obtained. Figure 5 The target duty cycle of the first power tube S1 and the third power tube S3 is obtained), and the control module controls the duty cycle of the power tubes corresponding to the U phase and the W phase to be the target duty cycle, so that the frequency of the charge and discharge current is the target frequency f max , the amplitude is the current amplitude. At this time, the charge and discharge current is the target charge and discharge current I=Asin(2*π*f max *t).

[0051] Execute step S500 to determine whether the amplitude of the charge and discharge current exceeds the target amplitude A. cmd If so, it indicates that the amplitude of the charge and discharge current has reached the ideal value, and the control module controls the amplitude of the charge and discharge current to the target amplitude A cmd , the frequency is the current frequency. If not, it indicates that the amplitude of the charge and discharge current has not reached the ideal value. The amplitude of the charge and discharge current can be increased, and the process returns to step S200.

[0052] Combine Figure 8 As shown, when it is determined that the charge and discharge current amplitude exceeds the target amplitude, the control module adjusts the charge and discharge current according to the target amplitude A. cmd And the current frequency is fitted to the target charge and discharge current I=A cmd sin(2*π*f*t), and the target charge and discharge current I=A cmd The difference between sin(2*π*f*t) and the sum of all phase currents without the first switch K1 is obtained to obtain a deviation value, and the deviation value is 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 amplitude of the charge and discharge current is the target amplitude A. cmd , the frequency is the current frequency. For example, if the phases of the first switch K1 are not set to U phase and 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. 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 and discharge current I=A cmd The sum of sin(2*π*f*t) and the U-phase current and the W-phase current is input into the subtractor to obtain the deviation value, and the PID adjustment is performed on the deviation value to obtain the target duty cycle of the power tube corresponding to the U-phase and W-phase ( Figure 4 The target duty cycle of the fourth power tube S4 and the sixth power tube S6 is obtained. Figure 5 The target duty cycle of the first power tube S1 and the third power tube S3 is obtained in the control module. The duty cycle of the power tubes corresponding to the U phase and the W phase is controlled to be the target duty cycle, so that the amplitude of the charge and discharge current is the target amplitude A. cmd , the frequency is the current frequency, at this time, the charge and discharge current is the target charge and discharge current I=A cmd sin(2*π*f*t).

[0053] It should be noted that when charging the bus capacitor C, the voltage across it increases, and when discharging, the voltage across it decreases. The higher the charge / discharge current amplitude, the higher the maximum voltage across the bus capacitor C, and the lower the charge / discharge current amplitude, the lower the maximum voltage across the bus capacitor C. Therefore, the charge / discharge current amplitude is positively correlated with the maximum voltage across the bus capacitor C. While increasing the charge / discharge current amplitude increases the charge / discharge efficiency, it also increases the maximum voltage across the bus capacitor C, increasing the risk of damage to the bus capacitor C. Furthermore, the higher the charge / discharge current frequency and the shorter the charge / discharge time, the lower the maximum voltage across the bus capacitor C. The lower the charge / discharge current frequency and the longer the charge / discharge time, the higher the maximum voltage across the bus capacitor C. The charge / discharge current frequency cannot be increased indefinitely (typically 1kHz to 10kHz). Considering the carrier ratio, a lower charge / discharge current frequency is actually better. The lower the charge / discharge current frequency, the more sinusoidal the charge / discharge current waveform and the lower the motor temperature rise. That is to say, the charge and discharge current is most beneficial to the temperature rise of the power battery E under the condition of low frequency and large value, but the large value is easy to burn the bus capacitor C, and the low frequency is easy to charge the voltage of the bus capacitor C to a high level. In this application, the voltage Uc across the bus capacitor C is always less than the threshold value U Hi , which can avoid the bus capacitor C from being damaged. At the same time, after adjustment, the amplitude of the charge and discharge current can be the target amplitude A cmd Alternatively, the frequency of the charge and discharge current can be the target frequency fmax. At least one of the two is satisfied, which is the optimal combination. Therefore, charging and discharging can be performed with the optimal charge and discharge current, thereby ensuring that charging and discharging are performed with the optimal charge and discharge current without damaging the bus capacitor C, thereby improving the heating efficiency of the power battery E.

[0054] Of course, the control method may also include the control module controlling the first switch K1 to be closed and the second switch K2 to be opened, so that the motor controller enters the power output mode. Figure 2 As shown, after the motor controller enters the power output mode, the control module controls the third switch K3 to be disconnected and the fourth switch K4 to be closed, and 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, and the pre-charging is completed. When the pre-charging is completed, the control module can control the third switch K3 to be closed and the fourth switch K4 to be disconnected, and the power battery E can normally output power to the motor module 20 through the bridge arm conversion module 10.

[0055] An embodiment of the present application further provides a new energy vehicle, including the motor controller described above. The new energy vehicle may be a vehicle, a ship, an aircraft, etc., and examples thereof are not given here one by one.

[0056] In summary, the embodiment provides a motor controller and a control method thereof, and a new energy vehicle. The motor controller comprises a bridge arm conversion module 10, a bus capacitor C, a motor module 20, a control module and a switching module. The switching module comprises at least a first switch K1 and a second switch K2. The bridge arm conversion module 10, the bus capacitor C and a first end of a power battery E are connected to each other. The bridge arm conversion module 10, the bus capacitor C and a second end of the power battery E are connected to each other. Each phase winding of the motor module 20 is connected to a neutral point of a corresponding bridge arm of the bridge arm conversion 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 conversion module 10. The second switch K2 is connected between the first switch K1 and the first end of the power battery E. The control method comprises the following steps. In 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. In step S200, at least one charge-discharge cycle is performed between the power battery E and the bus capacitor C, and step S300 is executed. In step S300, it is determined whether the voltage across the bus capacitor C exceeds a threshold value. If yes, the frequency of the charge-discharge current is increased, and step S400 is executed. If no, the amplitude of the charge-discharge current is increased, and step S500 is executed. In step S400, it is determined whether the frequency of the charge-discharge current exceeds a target frequency. If yes, the control module controls the frequency of the charge-discharge current to be the target frequency and the amplitude to be a current amplitude. If no, the frequency of the charge-discharge current is increased, and step S200 is returned to. In step S500, it is determined whether the amplitude of the charge-discharge current exceeds a target amplitude. If yes, the control module controls the amplitude of the charge-discharge current to be the target amplitude and the frequency to be a current frequency. If no, the amplitude of the charge-discharge current is increased, and step S200 is returned to. The first switch K1 and the second switch K2 are only needed to heat the power battery E, the structure of the motor module 20 does not need to be changed, the improvement is small, the cost is lower, and the charge-discharge current can be optimally charged and discharged without damaging the bus capacitor C, thereby improving the heating efficiency.

[0057] It should be noted that the embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts of each embodiment can be referred to each other.

[0058] It should also be noted that although the present application has been disclosed above with preferred embodiments, the above embodiments are not intended to limit the present application. For any person skilled in the art, without departing from the scope of the technical solution of the present application, the technical content disclosed above can be used to make many possible changes and modifications to the technical solution of the present application, or to modify it into an equivalent embodiment with equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application still falls within the scope of protection of the technical solution of the present application.

[0059] It should also be understood that, unless otherwise specified or indicated, the terms "first", "second", "third", etc. in the specification are only used to distinguish the various components, elements, steps, etc. in the specification, and are not used to indicate the logical relationship or sequential relationship between the various components, elements, steps, etc.

[0060] It should also be recognized that the terms described herein are used only to describe specific embodiments and are not intended to limit the scope of the present application. It should be noted that the singular forms "a" and "an" used herein include plural references unless the context clearly indicates otherwise. For example, a reference to "a step" or "a device" means a reference to one or more steps or devices and may include secondary steps and secondary devices. All conjunctions used should be understood in the broadest sense. Also, the word "or" should be understood to have the definition of a logical "or" rather than a logical "exclusive or" unless the context clearly indicates otherwise. In addition, the implementation of the methods and / or devices in the embodiments of the present application may include performing the 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, wherein the switch module includes 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 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 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 includes: Step S100: the control module controls the states of all switches in the switch module to control the motor controller to enter the AC heating mode, and then executes step S200; Step S200: The power battery and the bus capacitor are charged and discharged in a cycle at least once, and then step S300 is executed; Step S300: determining whether the voltage across the bus capacitor exceeds a threshold; if so, increasing the frequency of the charge / discharge current and executing step S400; if not, increasing the amplitude of the charge / discharge current and executing step S500; Step S400: determining whether the frequency of the charge and discharge current exceeds the target frequency; if so, the control module controls the frequency of the charge and discharge current to be the target frequency and the amplitude to be the current amplitude; if not, increasing the frequency of the charge and discharge current, and returning to step S200; Step S500: Determine whether the amplitude of the charge and discharge current exceeds the target amplitude. If so, the control module controls the amplitude of the charge and discharge current to be the target amplitude and the frequency to be the current frequency. If not, increase the amplitude of the charge and discharge current and return to step S200.

2. The control method of the motor controller according to claim 1, wherein: 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 end of the power battery and the first end of the bus capacitor, and 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 states 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 be closed and the first switch to be opened, and the motor controller enters the AC heating mode. The control module controls the third switch to be opened and the fourth switch to be closed, and the power battery pre-charges the bus capacitor. After the pre-charging is completed, the control module controls both the third switch and the fourth switch to be opened, and the power battery and the bus capacitor begin to cycle charge and discharge.

3. The control method of the motor controller according to claim 2, wherein: The control method further includes: The control module controls the first switch to be closed and the second switch to be opened, and 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 be opened and the fourth switch to be closed, and 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.

4. The control method of the motor controller according to claim 1, wherein: After the motor controller enters the AC heating mode, the control module controls the power tube of the upper bridge 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 tube of the lower bridge 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 tube of the lower bridge arm of the bridge arm conversion module to be normally closed, and the bus capacitor discharges to the power battery. The control module also 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 charging and discharging current.

5. The control method of the motor controller according to claim 4, characterized in that: After determining that the frequency of the charge and discharge current exceeds the target frequency, the control module fits the target charge and discharge current according to the target frequency and the current amplitude, and subtracts the target charge and discharge current from the sum of all phase currents without the first switch to obtain a deviation value, and performs PID adjustment on the deviation value to obtain a target duty cycle of the power tube corresponding to the first switch not being set. The control module controls the duty cycle of the power tube corresponding to the first switch not being set to the target duty cycle, so that the frequency of the charge and discharge current is the target frequency and the amplitude is the current amplitude.

6. The control method of the motor controller according to claim 4, characterized in that: After determining that the amplitude of the charge and discharge current exceeds the target amplitude, the control module fits the target charge and discharge current according to the target amplitude and the current frequency, and subtracts the target charge and discharge current from the sum of all phase currents without the first switch to obtain a deviation value, and performs PID adjustment on the deviation value to obtain a target duty cycle of the power tube corresponding to the first switch not being set. The control module controls the duty cycle of the power tube corresponding to the first switch not being set to the target duty cycle, so that the amplitude of the charge and discharge current is the target amplitude and the frequency is the current frequency.

7. The control method of the motor controller according to any one of claims 1 to 6, characterized in that: When the control module receives a heating instruction, the control module controls the states of all switches in the switch module to control the motor controller to enter the AC heating mode, the heating instruction includes at least the target amplitude, and the target amplitude is 90% to 100% of the maximum amplitude of the charge and 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 and discharge current.

8. The control method of a motor controller according to any one of claims 1 to 6, wherein: When the power battery and the bus capacitor begin to cycle charge and discharge, the initial amplitude of the charge and discharge current is 25% to 50% of the target amplitude, and the initial frequency of the charge and discharge current is the minimum frequency of the charge and discharge 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 bridge arm conversion module, the bus capacitor and the first end of the power battery are connected to each other, the bridge arm conversion module, the bus capacitor and the second end of 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 one 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; and The control module is used to control the states of all switches in the switch module to control the motor controller to enter the power output mode or the AC heating mode. In the AC 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 ensures that the voltage across the bus capacitor does not exceed a threshold.

10. A new energy vehicle, characterized in that: Comprising the motor controller as claimed in claim 9.

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