A motor controller, electric vehicle and powertrain

Abstract

The application provides a motor controller, an electric vehicle and a power assembly, and applies to the technical field of motor control. The motor controller comprises a control circuit and an inverter circuit. The control circuit is used for controlling the upper bridge arm switch tube and the lower bridge arm switch tube of each phase bridge arm to periodically conduct so that the bridge arm midpoint outputs alternating current to the motor to drive the rotation of the rotor of the motor. The electric angle of the motor periodically changes in the process of the rotation of the rotor of the motor. In the process of the periodic change of the electric angle of the motor, the control circuit controls the switching frequency of the upper bridge arm switch tube and the lower bridge arm switch tube of each phase bridge arm to change with the change of the electric angle of the motor, so that the switching frequency of the upper bridge arm switch tube and the lower bridge arm switch tube and the amplitude of the direct current bus ripple are synchronously increased and decreased, the direct current bus ripple is effectively inhibited while the system operation efficiency is ensured, and the system performance and stability are ensured.

Description

Technical Field

[0001] This application relates to the field of motor control technology, and more particularly to a motor controller, electric vehicle, and powertrain. Background Technology

[0002] In motor control systems, fluctuations in the DC bus voltage of the motor controller can lead to increased heat generation in key components and reduced system efficiency. It can also cause torque fluctuations and noise on the motor side, thereby affecting system performance and stability. Summary of the Invention

[0003] This application provides a motor controller, an electric vehicle, and a powertrain. The control circuit in the motor controller controls the switching frequency of the switching transistors of each phase bridge arm to change with the electrical angle, thereby effectively suppressing DC bus ripple while ensuring system operating efficiency and guaranteeing system performance and stability.

[0004] In a first aspect, embodiments of this application provide a motor controller, which includes a control circuit and an inverter circuit. The inverter circuit includes a multi-phase bridge arm, and each phase bridge arm includes an upper bridge arm switch and a lower bridge arm switch. The midpoint of each phase bridge arm is used to connect to one phase winding of the motor. The control circuit is used to control the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to periodically conduct so that the midpoint of the bridge arm outputs AC power to the motor to drive the rotor of the motor to rotate. During the rotation of the rotor of the motor, the electrical angle of the motor changes periodically.

[0005] The control circuit is used to control the switching frequency of the upper and lower bridge arm switches of each phase bridge arm to change with the change of the electrical angle of the motor during the periodic change of the motor's electrical angle.

[0006] Among them, the electrical angle refers to the angular quantity that describes the internal electromagnetic relationship of the motor, and one electrical angle cycle is 360 degrees.

[0007] In this embodiment, during the periodic change of the motor's electrical angle, the amplitude of the DC bus ripple changes with the electrical angle. The control circuit controls the switching frequencies of the upper and lower bridge arm switches in each phase arm to vary with the motor's electrical angle. This causes the switching frequencies of the upper and lower bridge arm switches and the amplitude of the DC bus ripple to increase and decrease synchronously. When the amplitude of the bus ripple increases, the switching frequency is increased, shortening the duration of a single charge-discharge cycle of the bus capacitor, thereby reducing the total charge input or output of the bus capacitor in a single charge-discharge cycle, further reducing the amplitude of the DC bus ripple. Conversely, when the amplitude of the bus ripple decreases, the switching frequency is decreased, reducing switching losses. Thus, the average switching frequency of the switches does not increase significantly within one electrical angle cycle of the motor, and the switching losses also do not increase significantly. This achieves effective suppression of DC bus ripple while ensuring system operating efficiency, guaranteeing system performance and stability. Furthermore, no hardware modifications are required, achieving zero-cost suppression of DC bus ripple.

[0008] In one embodiment of the first aspect, the control circuit is specifically used to: control the switching frequency of the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm within a preset frequency range.

[0009] In this embodiment, the control circuit controls the switching frequency of the upper and lower bridge arm switches of each phase bridge arm within a preset frequency range. This limits the switching frequency of the switches to a certain range, preventing the switching frequency from being too high, which would cause the switching frequency to be too high and affect the service life of the switches. It also prevents the switching frequency from being too low, which would generate large noise and current ripple, thereby improving the reliability and stability of the system.

[0010] In one embodiment of the first aspect, the motor comprises a plurality of continuously distributed time periods within one electrical angle cycle, and the control circuit is specifically configured to: control the switching frequency of the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to remain constant in any time period; and control the switching frequency of the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to be different in any two adjacent time periods.

[0011] The duration of each of the multiple time periods can be the same or different. The duration of each time period refers to the time required for the motor rotor to rotate through at least one complete electrical angle.

[0012] In this embodiment, the amplitude of the DC bus ripple remains unchanged or changes only slightly during any time period within one electrical angle cycle of the motor. In this case, the control circuit maintains a constant switching frequency for the upper and lower bridge arm switches of each phase arm to prevent frequency changes from affecting the suppression of DC bus ripple or the reduction of switching losses during that time period.

[0013] Furthermore, the amplitude of the DC bus ripple differs between any two adjacent time periods within one electrical angle cycle of the motor. In this case, the control circuit adaptively adjusts the switching frequency of the upper and lower bridge arm switches of each phase arm by controlling their switching frequencies differently. This ensures that the effect of suppressing DC bus ripple or reducing switching losses achieved by controlling the switching frequency matches the amplitude of the DC bus ripple in any two adjacent time periods, thus achieving precise control of the switching frequency.

[0014] In one embodiment of the first aspect, the control circuit is specifically configured to: the greater the speed of the motor, the shorter the duration for which the switching frequency of the upper and lower bridge arm switches of each phase bridge arm remains unchanged.

[0015] In this embodiment, the higher the motor speed, the shorter the time required for the motor rotor to rotate through a complete electrical angle. The control circuit controls the switching frequency of the upper and lower bridge arm switches of each phase bridge arm to remain constant for a shorter period of time, so that the duration of the constant switching frequency of the switches is synchronized with the time required for the motor rotor to rotate through a complete electrical angle, thereby achieving precise control of the switching frequency of the switches.

[0016] In one embodiment of the first aspect, the control circuit is specifically used to: control the switching frequency of the upper and lower bridge arm switches of each phase bridge arm to change periodically with the change of electrical angle.

[0017] In this embodiment, the amplitude of the DC bus ripple changes periodically with the electrical angle within one electrical angle cycle. In this case, the control circuit controls the switching frequencies of the upper and lower bridge arm switches of each phase arm to change periodically with the electrical angle, synchronizing the change in switching frequency with the periodic change in the DC bus ripple amplitude. This achieves the corresponding effect of suppressing DC bus ripple or reducing switching losses in each electrical angle. Furthermore, after obtaining the switching frequencies corresponding to each electrical angle within the first switching frequency change cycle, the results from the first cycle can be reused for control in subsequent cycles, reducing computational complexity.

[0018] In one embodiment of the first aspect, the control circuit is specifically used to: control the switching frequency variation period of the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to be the ratio of 180 degrees to the number of phases of the motor.

[0019] In this embodiment, the length of the period in which the amplitude of the DC bus ripple changes is inversely proportional to the number of phases of the motor. In this case, the control circuit controls the switching frequency of the upper and lower bridge arm switches of each phase arm to be the ratio of 180 degrees to the number of phases of the motor, i.e., the switching frequency change period is inversely proportional to the number of phases of the motor. This ensures that the length of the switching frequency change period of the switches is the same as the length of the period in which the amplitude of the DC bus ripple changes, achieving precise control of the switching frequency of the switches and thus effectively suppressing DC bus ripple or reducing switching losses.

[0020] In one embodiment of the first aspect, when the multi-phase bridge arm is a three-phase bridge arm and the motor is a three-phase motor, the electrical angle range of the motor from 0 degrees to 60 degrees includes three continuously distributed angle intervals. The control circuit is specifically used to: in the first angle interval of the three angle intervals, control the switching frequency of the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to increase as the electrical angle of the motor increases; in the second angle interval of the three angle intervals, control the switching frequency of the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to decrease as the electrical angle of the motor increases; and in the third angle interval of the three angle intervals, control the switching frequency of the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to increase as the electrical angle of the motor increases.

[0021] In this embodiment, the amplitude of the DC bus ripple first increases, then decreases, and then increases again within the 0-60 degree electrical angle range of the motor. Based on this, the 0-60 degree electrical angle range is divided into three continuously distributed angle intervals. The control circuit controls the switching frequency of the switching transistors to change according to the corresponding trend within each of the three angle intervals, thereby achieving precise control of the switching frequency. In the first angle interval, the control circuit controls the switching frequency of the upper and lower bridge arm switching transistors of each phase bridge arm to increase as the electrical angle of the motor increases. In the second angle interval, the control circuit controls the switching frequency of the upper and lower bridge arm switching transistors of each phase bridge arm to decrease as the electrical angle of the motor increases. In the third angle interval, the control circuit controls the switching frequency of the upper and lower bridge arm switching transistors of each phase bridge arm to increase as the electrical angle of the motor increases. This ensures that the switching frequency of the switching transistors and the amplitude of the DC bus ripple increase and decrease synchronously, effectively suppressing the DC bus ripple and reducing switching losses.

[0022] In the embodiments of this application, the trend of the switching frequency variation in each subsequent 60-degree angle range, such as the electrical angle range of 60 to 120 degrees and the electrical angle range of 180 to 240 degrees, is similar to the trend of the switching frequency variation in the electrical angle range of 0 to 60 degrees.

[0023] In one embodiment of the first aspect, the control circuit is specifically configured to: control the upper and lower bridge arm switches of each phase bridge arm to have a switching frequency that increases with electrical angle at a rate greater than the rate that increases with electrical angle at a rate greater than the switching frequency in a rate greater than the rate that increases with electrical angle ...

[0024] In this embodiment, the rate at which the amplitude of the DC bus ripple increases with increasing electrical angle differs between the first and third angle intervals. The control circuit precisely controls the switching frequency of the upper and lower bridge arm switches of each phase bridge arm to increase at a greater rate with increasing electrical angle in the first angle interval than in the third angle interval, thereby improving the accuracy of DC bus ripple suppression.

[0025] In one embodiment of the first aspect, when the multi-phase bridge arm is a three-phase bridge arm and the motor is a three-phase motor, the electrical angle range of the motor from 0 degrees to 60 degrees includes two continuously distributed angle intervals. The control circuit is specifically used to: in the first angle interval of the two angle intervals, control the switching frequency of the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to decrease as the electrical angle of the motor increases; and in the second angle interval of the two angle intervals, control the switching frequency of the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to increase as the electrical angle of the motor increases.

[0026] In this embodiment, the amplitude of the DC bus ripple first decreases and then increases within the 0-60 degree electrical angle range of the motor. Based on this, the 0-60 degree electrical angle range is divided into two continuously distributed angle intervals. The control circuit controls the switching frequency of the switching transistors to change with corresponding trends within the two angle intervals, thereby achieving precise control of the switching frequency. In the first angle interval, the control circuit controls the switching frequency of the upper and lower bridge arm switching transistors of each phase bridge arm to decrease as the electrical angle of the motor increases. In the second angle interval, the control circuit controls the switching frequency of the upper and lower bridge arm switching transistors of each phase bridge arm to increase as the electrical angle of the motor increases. This ensures that the switching frequency of the switching transistors and the amplitude of the DC bus ripple increase and decrease synchronously, effectively suppressing the DC bus ripple and reducing switching losses.

[0027] In one embodiment of the first aspect, the control circuit is specifically used to: during the periodic change of the electrical angle of the motor, when the torque of the motor is less than or equal to a preset torque, control the switching frequency of the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to remain unchanged; during the periodic change of the electrical angle of the motor, when the torque of the motor is greater than the preset torque, control the switching frequency of the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to change with the change of the electrical angle of the motor.

[0028] In this embodiment, during the periodic change of the motor's electrical angle, the system automatically identifies the motor as operating in a low-torque range by detecting when the motor torque is less than or equal to a preset torque; and automatically identifies the motor as operating in a high-torque range by detecting when the motor torque is greater than the preset torque. When the motor operates in the low-torque range, the amplitude of the DC bus ripple is generally small. The control circuit maintains a constant switching frequency for the upper and lower bridge arm switches of each phase arm to ensure system efficiency. Conversely, when the motor operates in the high-torque range, the amplitude of the DC bus ripple is generally large. The control circuit controls the switching frequency of the upper and lower bridge arm switches of each phase arm to vary with the motor's electrical angle, causing the switching frequency of the upper and lower bridge arm switches and the amplitude of the DC bus ripple to increase and decrease synchronously. This effectively suppresses DC bus ripple while ensuring system efficiency, thus guaranteeing system performance and stability.

[0029] In one embodiment of the first aspect, the control circuit is specifically configured to: during the periodic change of the electrical angle of the motor, when the power of the motor is less than or equal to a preset power, control the switching frequency of the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to remain unchanged; during the periodic change of the electrical angle of the motor, when the power of the motor is greater than the preset power, control the switching frequency of the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to change with the change of the electrical angle of the motor.

[0030] In this embodiment, during the periodic change of the motor's electrical angle, the system automatically identifies the motor as operating in the low-power range by detecting when the motor's power is less than or equal to a preset power, and automatically identifies the motor as operating in the high-power range by detecting when the motor's power is greater than the preset power. When the motor operates in the low-power range, the amplitude of the DC bus ripple is generally small. The control circuit maintains a constant switching frequency for the upper and lower bridge arm switches of each phase arm to ensure system efficiency. Conversely, when the motor operates in the high-power range, the amplitude of the DC bus ripple is generally large. The control circuit controls the switching frequency of the upper and lower bridge arm switches of each phase arm to change with the motor's electrical angle, causing the switching frequency of the upper and lower bridge arm switches and the amplitude of the DC bus ripple to increase and decrease synchronously. This effectively suppresses DC bus ripple while ensuring system efficiency, thus guaranteeing system performance and stability.

[0031] In this embodiment, the frequency conversion control of the motor is performed by partitioning the motor's torque or power, which can suppress DC bus ripple while ensuring system operating efficiency.

[0032] In one embodiment of the first aspect, the control circuit is specifically configured to: when the temperature of the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm is less than a preset temperature and the difference between the temperature and the preset temperature is greater than or equal to a preset difference, control the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to conduct at a first frequency during the electrical angle change process; when the temperature of the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm is less than a preset temperature and the difference between the temperature and the preset temperature is less than a preset difference, control the switching frequency of the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to be less than the first frequency during the electrical angle change process.

[0033] In this embodiment, by detecting that the temperature of the upper and lower bridge arm switches of each phase arm is lower than a preset temperature and the difference between the temperature and the preset temperature is greater than or equal to a preset difference, the power module junction temperature is automatically detected to be far below the safety threshold. In this case, during electrical angle changes, the control circuit controls the upper and lower bridge arm switches of each phase arm to conduct at a first frequency to suppress DC bus ripple. Furthermore, by detecting that the temperature of the upper and lower bridge arm switches of each phase arm is lower than a preset temperature and the difference between the temperature and the preset temperature is less than a preset difference, the power module junction temperature is automatically detected to be close to the safety threshold. In this case, the control circuit controls the switching frequency of the upper and lower bridge arm switches of each phase arm to be lower than the first frequency to reduce the power module junction temperature and ensure the reliability of system operation.

[0034] Secondly, embodiments of this application provide an electric vehicle, which includes a motor controller and a motor. The motor controller includes a control circuit and an inverter circuit. The inverter circuit includes a multi-phase bridge arm, and each phase bridge arm includes an upper bridge arm switch and a lower bridge arm switch. The midpoint of each phase bridge arm is used to connect to one phase winding of the motor. The control circuit is used to control the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to periodically conduct so that the midpoint of the bridge arm outputs AC power to the motor to drive the rotor of the motor to rotate. During the rotation of the motor rotor, the electrical angle of the motor changes periodically.

[0035] The control circuit is used to control the switching frequency of the upper and lower bridge arm switches of each phase bridge arm to change with the change of the motor's electrical angle during the periodic change of the motor's electrical angle. This ensures the efficiency of the motor controller while effectively suppressing DC bus ripple, thus guaranteeing system performance and stability in electric vehicles.

[0036] Thirdly, embodiments of this application provide a powertrain, which includes a motor controller and a motor. The motor controller includes a control circuit and an inverter circuit. The inverter circuit includes a multi-phase bridge arm, and each phase bridge arm includes an upper bridge arm switch and a lower bridge arm switch. The midpoint of each phase bridge arm is used to connect to one phase winding of the motor. The control circuit is used to control the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to periodically conduct so that the midpoint of the bridge arm outputs AC power to the motor to drive the rotor of the motor to rotate. During the rotation of the motor rotor, the electrical angle of the motor changes periodically.

[0037] A control circuit is used to control the switching frequency of the upper and lower bridge arm switches of each phase bridge arm to change with the electrical angle of a motor during the periodic change of the motor's electrical angle. This ensures the efficiency of the motor controller in the powertrain while effectively suppressing DC bus ripple, guaranteeing system performance and stability.

[0038] Fourthly, embodiments of this application provide a power electronic device, which includes an inverter and a load. The inverter includes a control circuit and an inverter circuit. The inverter circuit includes a multi-phase bridge arm. Each phase bridge arm includes an upper bridge arm switch and a lower bridge arm switch. The midpoint of each phase bridge arm is used to connect the load. The control circuit is used to control the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to periodically conduct so that the midpoint of the bridge arm outputs AC power to the load to drive the load to run. During the operation of the load, the electrical angle changes periodically.

[0039] The control circuit is used to control the switching frequency of the upper and lower bridge arm switches of each phase bridge arm to change with the electrical angle during the periodic change of the electrical angle. This ensures inverter operating efficiency while effectively suppressing DC bus ripple, guaranteeing system performance and stability in power electronic equipment.

[0040] The supplements and technical effects of the solutions provided in the second, third, and fourth aspects above can be found in the corresponding descriptions in the first aspect, and will not be repeated here. Attached Figure Description

[0041] Figure 1 A schematic diagram of a motor control system is shown; Figure 2 A schematic diagram of an electric vehicle provided in an embodiment of this application is shown; Figure 3 A schematic diagram of a motor controller provided in an embodiment of this application is shown; Figure 4 A schematic diagram of a powertrain provided in an embodiment of this application is shown; Figure 5The diagram shows a waveform of the winding voltage of a rotary transformer according to an embodiment of this application. Figure 6 The diagram shows a waveform of a three-phase modulated wave provided in an embodiment of this application; Figure 7 The diagram shows waveforms of mechanical angle, electrical angle, and switching frequency of a switching transistor according to an embodiment of this application. Figure 8 A schematic diagram of the internal operating logic of a motor controller provided in an embodiment of this application is shown; Figure 9 A timing diagram showing the switching frequency and electrical angle of a switching transistor according to an embodiment of this application is shown; Figure 10 A timing diagram showing the switching frequency and electrical angle of another switching transistor provided in an embodiment of this application is shown; Figure 11 A timing diagram showing the torque of a motor and the switching frequency of a switching transistor according to an embodiment of this application is shown; Figure 12 A timing diagram showing the power of a motor and the switching frequency of a switching transistor according to an embodiment of this application is shown; Figure 13 A flowchart illustrating the control process of the switching frequency of a switching transistor according to an embodiment of this application is shown; Figure 14 A flowchart illustrating the switching frequency control process of another switching transistor provided in an embodiment of this application is shown. Detailed Implementation

[0042] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0043] The use of prefixes such as "first" and "second" in this application embodiment is solely for distinguishing different descriptive objects and does not limit the position, order, priority, quantity, or content of the described objects. The use of ordinal numbers and other prefixes to distinguish descriptive objects in this application embodiment does not constitute a limitation on the described objects. The description of the described objects is found in the claims or the context of the embodiments, and the use of such prefixes should not constitute unnecessary restrictions.

[0044] In motor control systems, DC bus ripple is a key factor affecting system performance and stability.

[0045] In one implementation, the capacitance of the bus capacitor on the DC bus is increased, and the rapid charging and discharging of the bus capacitor absorbs or releases charge to maintain the stability of the bus voltage. See also Figure 1 , Figure 1 A schematic diagram of a motor control system is shown. (For example...) Figure 1As shown, during operation, the DC power output from the DC power supply is regulated and filtered by a large-capacity bus capacitor before being input to the three-phase bridge arm. The three-phase bridge arm converts the DC power into three-phase AC power and outputs it to the motor side to drive the motor.

[0046] However, the above implementation relies on hardware expansion, which increases hardware cost, size and weight. At the same time, the performance of capacitors will degrade with temperature and usage time, and they also have problems with lifespan and reliability, thus limiting their effectiveness in maintaining stable bus voltage.

[0047] In view of this, embodiments of this application provide a motor controller, an electric vehicle, and a powertrain. During the periodic change of the electrical angle of the motor, the amplitude of the DC bus ripple changes with the change of electrical angle. The control circuit in the motor controller controls the switching frequency of the upper and lower bridge arm switches of each phase bridge arm to change with the change of the electrical angle of the motor, so that the switching frequency of the upper and lower bridge arm switches and the amplitude of the DC bus ripple increase and decrease synchronously, thereby effectively suppressing the DC bus ripple while ensuring system operating efficiency, and ensuring system performance and stability.

[0048] See Figure 2 , Figure 2 A schematic diagram of an electric vehicle provided in an embodiment of this application is shown. (As shown) Figure 2 As shown, the electric vehicle 100 includes a motor 110, a motor controller 120, and a power battery 130. The motor 110 can be a drive motor, a generator, a compressor, etc., and the motor controller 120 is used to receive power from the power battery 130 and control the operation of the corresponding motor 110.

[0049] The motor controller 120 corresponding to the drive motor is used to receive power from the power battery 130 to drive the wheels or to heat the power battery 130. The motor controller 120 corresponding to the generator is used to convert the kinetic energy of the electric vehicle 100 into electrical energy, which is then used to power the drive motor to drive the wheels, charge the power battery 130, or heat the power battery 130. The motor controller 120 corresponding to the compressor is used to receive power from the power battery 130 to drive the vehicle's cooling system or to heat the power battery 130. It should be noted that this application does not specifically limit the type of motor 110.

[0050] See Figure 3 , Figure 3 A schematic diagram of a motor controller provided in an embodiment of this application is shown. Figure 3 The motor controller 120 shown is used to control two motors 110. For example... Figure 3 As shown, the motor controller 120 includes a control circuit 121 and an inverter circuit.

[0051] The control circuit 121 is used to receive control commands sent by the upper controller, calculate the target torque that the motor 120 needs to output based on the control commands, and control the operation of the inverter circuit.

[0052] The inverter circuit includes three-phase bridge arms 122. Each phase bridge arm in the three-phase bridge arm 122 includes an upper bridge arm switch and a lower bridge arm switch. The two ends of each switch arm are connected to the two ends of the bus capacitor C, respectively. The midpoint of each phase bridge arm is used to connect to one phase winding of the motor 110. Each phase bridge arm is used to invert the DC power from the power battery 130 into three-phase AC power with adjustable frequency and voltage, which is then output to the motor 120.

[0053] Specifically, the control circuit 121 controls the upper and lower bridge arm switches of each phase bridge arm to periodically turn on so that the midpoint of the three bridge arms outputs three-phase AC power to the motor to drive the rotor of the motor 110 to rotate and output the target torque.

[0054] It should be noted that, Figure 3 This is merely an example and does not specifically limit the number of motors 110 that the motor controller 120 can control or the number of phases of the multiphase bridge arm included in the motor controller.

[0055] See Figure 4 , Figure 4 A schematic diagram of a powertrain according to an embodiment of this application is shown. The powertrain 200 includes a motor 110 and a motor controller 120. The structure of the motor controller 120 and the connection method between the motor controller 120 and the motor 110 can be found in [reference needed]. Figure 3 .

[0056] The architecture of the embodiments of this application has been described above. The motor controller 120 provided in this application will be described below with reference to specific embodiments.

[0057] based on Figure 3 Analysis reveals that when the switching transistor in the three-phase bridge arm 122 switches, it causes the bus capacitor C to charge and discharge. Combined with the dynamic changes in the load current, this results in DC bus ripple. This DC bus ripple, transmitted to the motor 110 side, causes torque pulsation, increases vibration and noise during operation, and reduces control accuracy and stability. Furthermore, the generated ripple current exacerbates the heating of the bus capacitor C and the switching transistor, reducing system efficiency. These problems also exist when the switching transistors in the multi-phase bridge arms switch. The magnitude of the DC bus ripple primarily depends on the total amount of charge charged or discharged during a single charge-discharge cycle of the bus capacitor C.

[0058] To suppress DC bus ripple, an embodiment of this application provides a control circuit 121 that controls the periodic switching of the switching transistors of each phase bridge arm to drive the rotor rotation of the motor 110, causing the electrical angle of the motor 110 to change periodically. The control circuit 121 is used to control the switching frequency of the upper and lower bridge arm switching transistors of each phase bridge arm to change with the change of the electrical angle of the motor 110 during the periodic change of the electrical angle of the motor 110.

[0059] Among them, the electrical angle refers to the angular quantity that describes the internal electromagnetic relationship of the motor 110, and one electrical angle cycle is 360 degrees.

[0060] In one embodiment, the electrical angle is calculated by mechanical angle × number of pole pairs + zero offset. The mechanical angle can be read from the resolver signal from the rotary transformer, and the zero offset can be obtained through calibration.

[0061] For ease of understanding, see Figure 5 , Figure 5 The diagram shows a waveform of the winding voltage of a rotary transformer provided in an embodiment of this application.

[0062] The rotary transformer comprises an excitation winding, a sine winding, and a cosine winding. The excitation winding has a constant-amplitude, high-frequency sine wave waveform, providing a reference magnetic field. The sine and cosine windings have sine waves with varying amplitudes; the sine winding carries the sinusoidal information of the mechanical angle, and the cosine winding carries the cosine information of the mechanical angle. Their outer envelopes are as follows: Figure 5 As shown in the image.

[0063] When the sine winding envelope waveform crosses zero from negative to positive, and the cosine winding envelope is at its amplitude, the mechanical angle of the motor is 0. The number of pole pairs can be obtained by dividing the frequency of the motor output current by the frequency of the sine or cosine winding envelope of the rotary transformer.

[0064] In cases where the resolver signal of the resolver cannot be obtained or the electrical angle cannot be obtained through other sensors, in one embodiment, taking the three-phase bridge arm 122 as an example, the moment when the minimum value of the A-phase modulation wave during the high-level time period is obtained is taken as the moment when the electrical angle is 0 degrees. At this time, the change in electrical angle can be obtained by the phase change of the output current.

[0065] For ease of understanding, see Figure 6 , Figure 6 The diagram shows a waveform of a three-phase modulated wave provided in an embodiment of this application. Figure 6 The thicker line indicates the waveform of the A-phase modulated wave, and the point indicated by the arrow is the minimum point within the high-level time period, which corresponds to the moment when the electrical angle is 0 degrees.

[0066] Within one electrical angle cycle of motor 110, the amplitude of the DC bus ripple will increase or decrease with the change of electrical angle. Here, one electrical angle corresponds to one DC bus ripple amplitude, which is the difference between the maximum and minimum values ​​of the DC bus ripple within the time required for the rotor of motor 110 to rotate through one electrical angle.

[0067] In this case, by controlling the switching frequency of the upper and lower bridge arm switches (hereinafter referred to as switches for ease of description) of each phase bridge arm to change with the electrical angle of motor 110, the switching frequency of the upper and lower bridge arm switches and the amplitude of the DC bus ripple are increased and decreased synchronously. When the amplitude of the bus ripple increases, the switching frequency is increased, the duration of a single charge and discharge of the bus capacitor C is shortened, thereby reducing the total charge charged into or discharged by the bus capacitor C in a single charge and discharge, and reducing the amplitude of the DC bus ripple; when the amplitude of the bus ripple decreases, the switching frequency is decreased, the switching loss is reduced, and the system efficiency is guaranteed.

[0068] In this way, the average switching frequency of the switching transistor does not increase significantly within one electrical angle cycle of the motor 110, and the switching loss does not increase significantly either.

[0069] In one embodiment, the amplitude of the DC bus ripple at the current electrical angle can be calculated in real time during the rotation of the rotor of the motor 110, and then the switching frequency of the switch corresponding to the amplitude of the DC bus ripple can be calculated to control the upper and lower bridge arm switches of each phase bridge arm to conduct at that frequency.

[0070] In one embodiment, the amplitude of the DC bus ripple can be calculated based on the voltage modulation ratio, output current, and capacitance of the bus capacitor output by the inverter circuit.

[0071] In another embodiment, a mapping relationship between the amplitude of the DC bus ripple and the electrical angle can be established in advance. The current electrical angle is obtained in real time during the rotation of the rotor of the motor 110. Then, the amplitude of the DC bus ripple at the current electrical angle is obtained based on the mapping relationship. Finally, the switching frequency of the switching transistor corresponding to the amplitude of the DC bus ripple is calculated and the relevant control is executed.

[0072] For ease of understanding, see Figure 7 , Figure 7 The diagram shows waveforms of mechanical angle, electrical angle, and switching frequency of a switching transistor according to an embodiment of this application. Figure 7 Take a 3-pole logarithmic motor as an example.

[0073] like Figure 7 As shown, the period of the mechanical angle is 3 times the period of the electrical angle, and the switching frequency of the switching transistor changes with the change of the electrical angle.

[0074] In this embodiment, during the periodic change of the electrical angle of the motor 110, the amplitude of the DC bus ripple changes with the electrical angle. The control circuit 121 controls the switching frequency of the upper and lower bridge arm switches of each phase bridge arm to change with the electrical angle of the motor 110. This causes the switching frequency of the upper and lower bridge arm switches and the amplitude of the DC bus ripple to increase and decrease synchronously. When the amplitude of the bus ripple increases, the switching frequency is increased, shortening the duration of a single charge and discharge cycle of the bus capacitor, thereby reducing the total charge charged or discharged by the bus capacitor in a single charge and discharge cycle, and further reducing the amplitude of the DC bus ripple. Conversely, when the amplitude of the bus ripple decreases, the switching frequency is decreased, reducing switching losses. In this way, the average switching frequency of the switches does not increase significantly within one electrical angle cycle of the motor 110, and the switching losses also do not increase significantly. This achieves effective suppression of DC bus ripple while ensuring system operating efficiency, thus guaranteeing system performance and stability. At the same time, without any hardware modifications, DC bus ripple suppression was achieved at zero cost.

[0075] See Figure 8 , Figure 8 The diagram shows a schematic of the internal operating logic of a motor controller provided in an embodiment of this application, taking the three-phase bridge arm 122 as an example.

[0076] like Figure 8 As shown, in the motor controller 120, the signal sampling and processing module collects the resolver signal and sends the calculated real-time electrical angle to the ripple amplitude determination module.

[0077] The ripple amplitude determination module queries the amplitude of the corresponding DC bus ripple based on the current electrical angle, or calculates the amplitude of the corresponding DC bus ripple in real time based on the relevant parameters collected at the current electrical angle, and sends the obtained DC bus ripple amplitude to the dynamic frequency calculation module.

[0078] The dynamic frequency calculation module calculates the switching frequency of the switching transistor based on the amplitude of the DC bus ripple and sends it to the PWM (Pulse Width Modulation) waveform generation module. The PWM waveform generation module generates a PWM signal to control the conduction of the switching transistor in the inverter circuit.

[0079] During this process, the inverter circuit continuously receives the DC power output from the DC bus and converts it into three-phase AC power to control the operation of the motor 110. The sampling and processing module also receives the resolver feedback signal sent by the motor 110 to achieve closed-loop control.

[0080] In one embodiment, the control circuit 121 is specifically used to control the switching frequency of the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm within a preset frequency range.

[0081] The preset frequency range includes the maximum frequency value and the minimum frequency value.

[0082] When the switching frequency of the switching transistor exceeds the maximum frequency value, the temperature of the switching transistor will be too high, affecting the service life of the switching transistor; when the switching frequency is lower than the minimum frequency value, it will generate greater noise and current ripple.

[0083] In one embodiment, the maximum and minimum frequency values ​​can be the maximum and minimum values ​​allowed for safe operation of the switching transistor, or they can be slightly less than the maximum and slightly greater than the minimum values ​​allowed for safe operation.

[0084] In another embodiment, the maximum and minimum frequency values ​​can be determined based on the maximum and minimum amplitude of the DC bus ripple within the electrical angle period. For example, a frequency coefficient can be calculated based on the maximum and minimum amplitude of the DC bus ripple, and the maximum and minimum frequency values ​​are obtained by the center frequency × (1 ± frequency coefficient).

[0085] The center frequency can be the average value of the switching frequency within one electrical angle period, the average value of the maximum and minimum frequency values, or a fixed frequency before the function of the control circuit 121 provided in this application embodiment is enabled.

[0086] In this embodiment, the control circuit 121 controls the switching frequency of the upper and lower bridge arm switches of each phase bridge arm within a preset frequency range, thereby limiting the switching frequency of the switches to a certain range. This prevents the switching frequency of the switches from being too high, which would cause the temperature of the switches to be too high and affect their service life; and also prevents the switching frequency of the switches from being too low, which would generate large noise and current ripple, thereby improving the reliability and stability of the system.

[0087] After knowing the preset frequency range of the switching transistor and the maximum and minimum values ​​of the DC bus ripple amplitude within the electrical angle period, the switching frequency of the switching transistor can be obtained by interpolation, neural network models, etc., after obtaining the amplitude of the DC bus ripple at the real-time electrical angle.

[0088] In one embodiment, the motor 110 includes a series of consecutively distributed time periods within one electrical angle cycle, and the control circuit 121 is specifically used to control the switching frequency of the upper and lower bridge arm switches of each phase arm to remain constant within any given time period.

[0089] The duration of each of the multiple time periods can be the same or different. The duration of each time period refers to the time required for the rotor of motor 110 to rotate through at least one complete electrical angle. For example, any time period is the time required for the rotor to rotate through one complete electrical angle, and its corresponding electrical angle is 5 degrees. Or, for example, any time period is the time required for the rotor to rotate through two complete electrical angles, and its corresponding electrical angles are 5 degrees and 6 degrees.

[0090] In one embodiment, the number of electrical angles corresponding to any time period can be determined based on the amplitude of the DC bus ripple. For example, multiple electrical angles whose difference between the amplitudes of the DC bus ripple is less than a preset difference belong to one time period.

[0091] In this case, if the switching frequency of the switching transistor fluctuates within a preset value range during a certain period, it can be considered as the switching frequency remaining constant during that period.

[0092] In this embodiment, the amplitude of the DC bus ripple remains unchanged or changes only slightly during any period within one electrical angle cycle of the motor 110. In this case, the control circuit 121 controls the switching frequencies of the upper and lower bridge arm switches of each phase arm to remain constant, thus preventing changes in the switching frequency from affecting the effect of suppressing DC bus ripple or reducing switching losses during that period.

[0093] In one embodiment, the control circuit 121 is specifically configured to: the greater the rotational speed of the motor 110, the shorter the duration for which the switching frequency of the upper and lower bridge arm switches of each phase bridge arm remains unchanged.

[0094] The higher the rotational speed of motor 110, the shorter the time required for the rotor of motor 110 to rotate through a complete electrical angle.

[0095] In this embodiment, the control circuit 121 controls the switching frequency of the upper and lower bridge arm switches of each phase bridge arm to remain constant for a shorter period of time, so that the duration of the constant switching frequency of the switches is synchronized with the duration required for the rotor of the motor 110 to rotate through a complete electrical angle, thereby achieving precise control of the switching frequency of the switches.

[0096] In one embodiment, the control circuit 121 is further configured to: control the switching frequencies of the upper and lower bridge arm switches of each phase bridge arm to be different in any two adjacent time periods.

[0097] The difference in the amplitude of DC bus ripple in any two adjacent time periods of one electrical angle cycle of motor 110.

[0098] In this case, by controlling the switching frequencies of the upper and lower bridge arm switches of each phase bridge arm to be different, the effect of suppressing DC bus ripple or reducing switching losses achieved by controlling the switching frequency of the switches is matched with the amplitude of DC bus ripple in any two adjacent time periods.

[0099] The duration of two adjacent time periods can be the same, for example, the time required for the rotor to rotate through one complete electrical angle. The electrical angle corresponding to the first time period in the two adjacent time periods is 5 degrees, and the electrical angle corresponding to the second time period in the two adjacent time periods is 6 degrees. In this case, the switching frequency of the switching transistor changes once every time the rotor of motor 110 rotates through one electrical angle. For another example, the duration required for the rotor to rotate through two complete electrical angles can be the same, with the electrical angles corresponding to the first time period being 5 degrees and 6 degrees, and the electrical angles corresponding to the second time period being 7 degrees and 8 degrees. In this case, the switching frequency of the switching transistor changes once every time the rotor of motor 110 rotates through two electrical angles.

[0100] Two adjacent time periods can be different. For example, the duration of the first time period is the time required for the rotor to rotate through one complete electrical angle, and the duration of the second time period is the time required for the rotor to rotate through two complete electrical angles. The electrical angle corresponding to the first time period is 6 degrees, and the electrical angles corresponding to the second time period are 7 degrees and 8 degrees.

[0101] In this embodiment, the control circuit 121 controls the switching frequencies of the upper and lower bridge arm switches of each phase bridge arm to be different, thereby enabling the control circuit 121 to adaptively adjust the switching frequency of the switches. This ensures that the effect of suppressing DC bus ripple or reducing switching losses achieved by controlling the switching frequency of the switches matches the amplitude of DC bus ripple in any two adjacent time periods, thus achieving precise control of the switching frequency of the switches.

[0102] In one embodiment, the control circuit 121 is specifically used to control the switching frequency of the upper and lower bridge arm switches of each phase bridge arm to change periodically with the change of electrical angle.

[0103] Within one electrical angle cycle, the amplitude of the DC bus ripple changes periodically with the change of electrical angle.

[0104] In this case, by periodically changing the switching frequency of the switching transistor with the change of electrical angle, the change of the switching frequency of the switching transistor and the periodic change of the amplitude of the DC bus ripple are synchronized, so as to achieve the corresponding effect of suppressing DC bus ripple or reducing switching losses at each electrical angle.

[0105] For better understanding, please continue reading. Figure 7 The switching frequency waveform of the switching transistor exhibits periodic changes.

[0106] In one embodiment, the starting electrical angle of the switching frequency variation period of the switching transistor is not limited. For example, a variation period may start from 0 degrees or from 30 degrees. That is, regardless of the specific starting electrical angle of the variation period, the switching frequency of the switching transistor exhibits a periodic variation within one electrical angle period.

[0107] In one embodiment, the switching frequency of the switching transistor corresponding to each electrical angle within the first change cycle can be calculated only within the first change cycle, and the corresponding switching frequency can be reused to perform relevant control for the electrical angles in subsequent multiple change cycles.

[0108] In this embodiment, the control circuit 121 controls the switching frequencies of the upper and lower bridge arm switches of each phase bridge arm to change periodically with the electrical angle. This synchronizes the change in the switching frequency of the switches with the periodic change in the amplitude of the DC bus ripple, achieving the corresponding effect of suppressing DC bus ripple or reducing switching losses at each electrical angle. Furthermore, after obtaining the switching frequencies corresponding to each electrical angle within the first switching frequency change cycle, the results from the first change cycle can be reused for control in subsequent change cycles, reducing computational complexity.

[0109] In one embodiment, the control circuit 121 is specifically used to: control the switching frequency variation period of the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to be the ratio of 180 degrees to the number of phases of the motor 110.

[0110] That is, the length of the switching frequency change period = 180 degrees / number of phases. For example, for a three-phase bridge arm 122, the length of the change period is 60 degrees, and for a four-phase bridge arm, the length of the change period is 45 degrees.

[0111] In this embodiment, the length of the variation period of the DC bus ripple amplitude is inversely proportional to the number of phases of the motor 110. In this case, the control circuit 121 controls the switching frequency variation period of the upper and lower bridge arm switches of each phase arm to be the ratio of 180 degrees to the number of phases of the motor 110. That is, the switching frequency variation period is inversely proportional to the number of phases of the motor 110, ensuring that the length of the switching frequency variation period of the switches is the same as the length of the variation period of the DC bus ripple amplitude. This achieves precise control of the switching frequency of the switches, resulting in effective suppression of DC bus ripple or reduction of switching losses.

[0112] The following describes in detail the switching frequency variation period and the specific control process of the switching frequency within one variation period, taking the three-phase bridge arm 122 and motor 110 as examples.

[0113] When the multiphase bridge arm is a three-phase bridge arm 122 and the motor 110 is a motor 110, the amplitude of the DC bus ripple changes in a period of 60 degrees, which corresponds to the period of the switching frequency change in a period of 60 degrees.

[0114] Taking the 0-60 degree electrical angle range of motor 110 as an example, the trend of switching frequency change in subsequent electrical angle ranges such as 60-120 degree and 180-240 degree is similar to that in the 0-60 degree electrical angle range, and will not be elaborated here.

[0115] The specific control method for the switching frequency of the switching transistor within the electrical angle range of 0 to 60 degrees of motor 110 also needs to consider the power factor of motor 110. When the power factor of motor 110 is greater than the preset power factor, such as 0.92 or 0.95, it indicates that motor 110 is operating under heavy load; when the power factor of motor 110 is less than or equal to the preset power factor, such as 0.75 or 0.8, it indicates that motor 110 is operating normally.

[0116] When the motor 110 is operating normally, the electrical angle range of the motor 110 from 0 degrees to 60 degrees includes three continuously distributed angle intervals. In one embodiment, the control circuit 121 is specifically used to: in the first angle interval of the three angle intervals, control the switching frequency of the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to increase as the electrical angle of the motor 110 increases; in the second angle interval of the three angle intervals, control the switching frequency of the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to decrease as the electrical angle of the motor 110 increases; and in the third angle interval of the three angle intervals, control the switching frequency of the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to increase as the electrical angle of the motor 110 increases.

[0117] Within the electrical angle range of 0 to 60 degrees, the division into three angle intervals is related to the changing trend of the DC bus ripple amplitude. In the first angle interval, the DC bus ripple amplitude increases; in the second angle interval, the DC bus ripple amplitude decreases; and in the third angle interval, the DC bus ripple amplitude increases.

[0118] In this case, within the first angle range, the switching frequency of the control transistor increases as the electrical angle of the motor 110 increases; within the second angle range, the switching frequency of the control transistor decreases as the electrical angle of the motor 110 increases; and within the third angle range, the switching frequency of the control transistor increases as the electrical angle of the motor 110 increases. This allows the switching frequency of the control transistor and the amplitude of the DC bus ripple to increase and decrease synchronously, effectively reducing the amplitude of the DC bus ripple and effectively reducing switching losses.

[0119] For ease of understanding, see Figure 9 , Figure 9 The diagram shows a timing diagram of the switching frequency and electrical angle of a switching transistor provided in an embodiment of this application.

[0120] like Figure 9 As shown, the first angular interval is between 0 degrees and θ1, during which the switching frequency of the switching transistor increases; the second angular interval is between θ1 and θ2, during which the switching frequency of the switching transistor decreases; and the third angular interval is between θ2 and 60 degrees, during which the switching frequency of the switching transistor increases.

[0121] Between 60 and 120 degrees, the trend of the switching frequency is similar to that between 0 and 60 degrees of electrical angle, with the switching frequency first increasing, then decreasing, and then increasing again.

[0122] Among them, if the switching frequency curve of the switching transistor exhibits local fluctuations or abrupt changes within a switching frequency variation cycle, it can be regarded as the curve still maintaining the trend of first increasing, then decreasing, and then increasing again.

[0123] When any two adjacent time periods correspond to electrical angles within the first angular interval, the switching frequency of the preceding time period is less than that of the following time period; when any two adjacent time periods correspond to electrical angles within the second angular interval, the switching frequency of the preceding time period is greater than that of the following time period; when any two adjacent time periods correspond to electrical angles within the third angular interval, the switching frequency of the preceding time period is less than that of the following time period.

[0124] In this embodiment, the amplitude of the DC bus ripple in the electrical angle range of 0 to 60 degrees of motor 110 will first increase, then decrease, and then increase again. Based on this, the electrical angle range of 0 to 60 degrees is divided into three continuously distributed angle intervals. The control circuit 121 controls the switching frequency of the switching transistor to change with the corresponding trend in the three angle intervals, so as to achieve precise control of the switching frequency of the switching transistor. In the first angle interval of the three angle intervals, the control circuit 121 controls the switching frequency of the upper and lower bridge arm switches of each phase bridge arm to increase as the electrical angle of the motor 110 increases; in the second angle interval, the control circuit 121 controls the switching frequency of the upper and lower bridge arm switches of each phase bridge arm to decrease as the electrical angle of the motor 110 increases; in the third angle interval, the control circuit 121 controls the switching frequency of the upper and lower bridge arm switches of each phase bridge arm to increase as the electrical angle of the motor 110 increases, so that the switching frequency of the switches and the amplitude of the DC bus ripple increase and decrease synchronously, thereby effectively suppressing the DC bus ripple and reducing switching losses.

[0125] In one embodiment, the control circuit 121 is specifically configured to: control the upper and lower bridge arm switches of each phase bridge arm to have a higher rate of increase in switching frequency with electrical angle in the first angle interval than in the third angle interval.

[0126] Within the first and third angle intervals, the rate at which the amplitude of the DC bus ripple increases with increasing electrical angle differs.

[0127] In this case, by controlling the switching frequency of the switching transistor to increase at a rate greater than the rate of increase of the switching frequency with respect to the electrical angle in the first angle interval than in the third angle interval, the switching frequency of the switching transistor and the amplitude of the DC bus ripple increase synchronously, thereby achieving precise control of the switching frequency as the electrical angle increases.

[0128] See also Figure 9 The slope of the curve between 0 degrees and θ1 is greater than the slope of the curve between θ2 and 60 degrees.

[0129] In this embodiment, the rate at which the amplitude of the DC bus ripple increases with increasing electrical angle differs between the first and third angle intervals. The control circuit 121 controls the upper and lower bridge arm switches of each phase bridge arm to increase their switching frequency with increasing electrical angle at a greater rate in the first angle interval than in the third angle interval, thereby achieving precise control of the switching frequency as the electrical angle increases and improving the accuracy of DC bus ripple suppression.

[0130] When the motor 110 is operating under heavy load, the electrical angle range of the motor 110 from 0 degrees to 60 degrees includes two continuously distributed angle intervals. In one embodiment, the control circuit 121 is specifically used to: in the first angle interval of the two angle intervals, control the switching frequency of the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to decrease as the electrical angle of the motor 110 increases; in the second angle interval of the two angle intervals, control the switching frequency of the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to increase as the electrical angle of the motor 110 increases.

[0131] Within the electrical angle range of 0 to 60 degrees, the division of the first and second angle intervals is related to the changing trend of the DC bus ripple amplitude. In the first angle interval, the DC bus ripple amplitude decreases; in the second angle interval, the DC bus ripple amplitude increases.

[0132] In this case, within the first angle range, the switching frequency of the control transistor decreases as the electrical angle of the motor 110 increases; within the second angle range, the switching frequency of the control transistor increases as the electrical angle of the motor 110 increases, so that the switching frequency of the control transistor and the amplitude of the DC bus ripple increase and decrease synchronously, effectively reducing the amplitude of the DC bus ripple and effectively reducing switching losses.

[0133] For ease of understanding, see Figure 10 , Figure 10 A timing diagram showing the switching frequency and electrical angle of another switching transistor provided in an embodiment of this application is shown.

[0134] like Figure 10 As shown, the first angular interval is between 0 degrees and θ3, during which the switching frequency of the switching transistor decreases; the second angular interval is between θ3 and 60 degrees, during which the switching frequency of the switching transistor increases.

[0135] Between 60 and 120 degrees, the trend of the switching frequency is similar to that between 0 and 60 degrees of electrical angle, with the switching frequency first decreasing and then increasing.

[0136] Similarly, if the switching frequency curve of the switching transistor experiences local fluctuations or abrupt changes within a switching frequency variation cycle, it can be considered that the curve still maintains the trend of first decreasing and then increasing.

[0137] When any two adjacent time periods correspond to electrical angles within the first angular interval, the switching frequency of the preceding time period is greater than that of the following time period; when any two adjacent time periods correspond to electrical angles within the second angular interval, the switching frequency of the preceding time period is less than that of the following time period.

[0138] In this embodiment, the amplitude of the DC bus ripple first decreases and then increases within the electrical angle range of 0 to 60 degrees of the motor 110. Based on this, the electrical angle range of 0 to 60 degrees is divided into two continuously distributed angle intervals. The control circuit 121 controls the switching frequency of the switching transistors to change with corresponding trends within the two angle intervals, thereby achieving precise control of the switching frequency of the switching transistors. In the first angle interval, the control circuit 121 controls the switching frequency of the upper and lower bridge arm switching transistors of each phase bridge arm to decrease as the electrical angle of the motor 110 increases. In the second angle interval, the control circuit 121 controls the switching frequency of the upper and lower bridge arm switching transistors of each phase bridge arm to increase as the electrical angle of the motor 110 increases, so that the switching frequency of the switching transistors and the amplitude of the DC bus ripple increase and decrease synchronously, thereby effectively suppressing the DC bus ripple and reducing switching losses.

[0139] In some motor drive applications, differentiated frequency conversion strategies can be adopted according to the different torque, power, modulation amplitude command values ​​or instantaneous values ​​of motor 110, so as to achieve a balance between efficiency and DC bus ripple amplitude suppression.

[0140] The following example uses a differentiated frequency conversion strategy for different torques and power. The same applies to parameters such as the command value or instantaneous value of the modulation wave amplitude. The following control methods can be used when the command value or instantaneous value of the modulation wave amplitude is greater than the parameter threshold and when it is less than or equal to the parameter threshold, respectively. These will not be elaborated here.

[0141] In one embodiment, the control circuit 121 is specifically configured to: during the periodic change of the electrical angle of the motor 110, when the torque of the motor 110 is less than or equal to a preset torque, control the switching frequency of the upper and lower bridge arm switches of each phase bridge arm to remain unchanged; during the periodic change of the electrical angle of the motor 110, when the torque of the motor 110 is greater than the preset torque, control the switching frequency of the upper and lower bridge arm switches of each phase bridge arm to change with the change of the electrical angle of the motor 110.

[0142] When the torque of motor 110 is greater than the preset torque, it means that motor 110 is operating at high torque and the amplitude of DC bus ripple is large; when the torque of motor 110 is less than or equal to the preset torque, it means that motor 110 is operating at low torque and the amplitude of DC bus ripple is small.

[0143] When the motor 110 is running at low torque, there is no need to suppress the amplitude of the DC bus ripple. By keeping the switching frequency of the upper and lower bridge arm switches of each phase bridge arm constant, the operating efficiency of the motor 110 can be guaranteed.

[0144] When the motor 110 is running at high torque, the amplitude of DC bus ripple is effectively reduced by controlling the switching frequency of the upper and lower bridge arm switches of each phase bridge arm to change with the electrical angle of the motor 110.

[0145] For ease of understanding, see Figure 11 , Figure 11 A timing diagram showing the torque of a motor and the switching frequency of a switching transistor according to an embodiment of this application is shown.

[0146] like Figure 11 As shown, before time t, the torque of motor 110 is less than the preset torque, and the switching frequency of the switching transistor remains unchanged. After time t, the torque of motor 110 is greater than the preset torque, and the switching frequency of the switching transistor changes with the electrical angle of the motor. For a detailed trend, please refer to [reference needed]. Figure 9 and Figure 10 .

[0147] The fluctuation of the switching frequency of the switching transistor within the preset range can be regarded as its constant.

[0148] Other related controls when the torque of motor 110 is greater than the preset torque can be referred to the relevant descriptions in the foregoing embodiments, and will not be repeated here.

[0149] In this embodiment, during the periodic change of the electrical angle of the motor 110, the system automatically identifies the motor 110 as operating in a low torque range by detecting that the torque of the motor 110 is less than or equal to a preset torque; and automatically identifies the motor 110 as operating in a high torque range by detecting that the torque of the motor 110 is greater than the preset torque. When the motor 110 is operating in the low torque range, the amplitude of the DC bus ripple is generally small. The control circuit 121 maintains a constant switching frequency for the upper and lower bridge arm switches of each phase arm to ensure system operating efficiency. Conversely, when the motor 110 is operating in the high torque range, the amplitude of the DC bus ripple is generally large. The control circuit 121 controls the switching frequency of the upper and lower bridge arm switches of each phase arm to change with the electrical angle of the motor 110, so that the switching frequency of the upper and lower bridge arm switches and the amplitude of the DC bus ripple increase and decrease synchronously. This effectively suppresses the DC bus ripple while ensuring system operating efficiency, thus guaranteeing system performance and stability.

[0150] In one embodiment, the control circuit 121 is specifically configured to: during the periodic change of the electrical angle of the motor 110, when the power of the motor 110 is less than or equal to a preset power, control the switching frequency of the upper and lower bridge arm switches of each phase bridge arm to remain unchanged; during the periodic change of the electrical angle of the motor 110, when the power of the motor 110 is greater than the preset power, control the switching frequency of the upper and lower bridge arm switches of each phase bridge arm to change with the change of the electrical angle of the motor 110.

[0151] When the power of motor 110 is greater than the preset power, it means that motor 110 is operating at high power and the amplitude of DC bus ripple is large; when the power of motor 110 is less than or equal to the preset power, it means that motor 110 is operating at low power and the amplitude of DC bus ripple is small.

[0152] When the motor 110 is running at low power, there is no need to suppress the amplitude of the DC bus ripple. By keeping the switching frequency of the upper and lower bridge arm switches of each phase bridge arm constant, the operating efficiency of the motor 110 can be guaranteed.

[0153] When the motor 110 is running at high power, the amplitude of DC bus ripple is effectively reduced by controlling the switching frequency of the upper and lower bridge arm switches of each phase bridge arm to change with the electrical angle of the motor 110.

[0154] For ease of understanding, see Figure 12 , Figure 12 A timing diagram showing the power of a motor and the switching frequency of a switching transistor according to an embodiment of this application is shown.

[0155] like Figure 12 As shown, before time t, the power of motor 110 is less than the preset power, and the switching frequency of the switching transistor remains unchanged. After time t, the power of motor 110 is greater than the preset power, and the switching frequency of the switching transistor changes with the electrical angle of the motor. For a detailed trend, please refer to [reference needed]. Figure 9 and Figure 10 .

[0156] The fluctuation of the switching frequency of the switching transistor within the preset range can be regarded as its constant.

[0157] For other related controls when the power of motor 110 is greater than the preset power, please refer to the relevant descriptions in the foregoing embodiments, which will not be repeated here.

[0158] In this embodiment, during the periodic change of the electrical angle of motor 110, the system automatically identifies motor 110 as operating in the low-power range by detecting that the power of motor 110 is less than or equal to a preset power; and automatically identifies motor 110 as operating in the high-power range by detecting that the power of motor 110 is greater than the preset power. When motor 110 operates in the low-power range, the amplitude of DC bus ripple is generally small. The control circuit 121 maintains a constant switching frequency for the upper and lower bridge arm switches of each phase arm to ensure system operating efficiency. Conversely, when motor 110 operates in the high-power range, the amplitude of DC bus ripple is generally large. The control circuit 121 controls the switching frequency of the upper and lower bridge arm switches of each phase arm to change with the electrical angle of motor 110, causing the switching frequency of the upper and lower bridge arm switches and the amplitude of DC bus ripple to increase and decrease synchronously. This effectively suppresses DC bus ripple while ensuring system operating efficiency, thus guaranteeing system performance and stability.

[0159] In this embodiment, the torque or power of the motor 110 is used for zoned frequency conversion control, which can suppress DC bus ripple while ensuring system operating efficiency.

[0160] In addition, during system operation, the junction temperature of the power module (including the temperature of the upper and lower bridge arm switches in each phase of the multi-phase bridge arm) also needs to be considered. When the junction temperature of the power module is too high, it will affect the safe operation of the system.

[0161] Thus, in one embodiment, the control circuit 121 is specifically configured to: when the temperature of the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm is less than a preset temperature and the difference between the temperature and the preset temperature is greater than or equal to a preset difference, control the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to conduct at a first frequency during the electrical angle change process; when the temperature of the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm is less than a preset temperature and the difference between the temperature and the preset temperature is less than a preset difference, control the switching frequency of the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to be less than the first frequency during the electrical angle change process.

[0162] When the temperature of the upper and lower bridge arm switches of each phase bridge arm is lower than the preset temperature and the difference between the temperature and the preset temperature is greater than or equal to the preset difference, it indicates that the junction temperature of the power module is far below the safety threshold and there is no operational risk. When the temperature of the upper and lower bridge arm switches of each phase bridge arm is lower than the preset temperature and the difference between the temperature and the preset temperature is less than the preset difference, it indicates that the junction temperature of the power module is close to the safety threshold and there is an operational risk.

[0163] When the junction temperature of the power module is much lower than the safety threshold, the control circuit 121 can directly calculate the switching frequency of the switching transistor, i.e. the first frequency, and execute the relevant control in the manner mentioned in the foregoing embodiments.

[0164] When the junction temperature of the power module is close to the safety threshold, the control circuit 121 reduces the junction temperature of the power module by controlling the switching frequency of the upper and lower bridge arm switches of each phase bridge arm to be lower than the first frequency.

[0165] In this embodiment, by detecting that the temperature of the upper and lower bridge arm switches of each phase bridge arm is lower than a preset temperature and the difference between the temperature and the preset temperature is greater than or equal to a preset difference, the power module junction temperature is automatically detected to be far below the safety threshold. In this case, during electrical angle changes, the control circuit 121 controls the upper and lower bridge arm switches of each phase bridge arm to conduct at a first frequency to suppress DC bus ripple. Furthermore, by detecting that the temperature of the upper and lower bridge arm switches of each phase bridge arm is lower than a preset temperature and the difference between the temperature and the preset temperature is less than a preset difference, the power module junction temperature is automatically detected to be close to the safety threshold. In this case, the control circuit 121 controls the switching frequency of the upper and lower bridge arm switches of each phase bridge arm to be lower than the first frequency to reduce the power module junction temperature and ensure the reliability of system operation.

[0166] In summary, the frequency conversion control of the switching transistor includes full-range frequency conversion control, which means that the switching frequency of the switching transistor is controlled by frequency conversion for all torque or power ranges in which the motor 110 operates; and zoned frequency conversion control, which means that the switching frequency of the switching transistor is controlled by frequency conversion for specific torque or power ranges in which the motor 110 operates. During the full-range and zoned frequency conversion control of the switching transistor, the junction temperature of the power module can also be considered to prevent excessively high junction temperatures from affecting the safe operation of the system.

[0167] See Figure 13 , Figure 13 This application provides a flowchart illustrating a control process for the switching frequency of a switching transistor according to an embodiment of the present application. Figure 13 This is illustrated as a full-area frequency conversion control process. An example is given where a pre-established mapping relationship between the amplitude and electrical angle of the DC bus ripple is presented in a table.

[0168] like Figure 13 As shown, firstly, the control circuit 121 obtains the real-time electrical angle from the rotary transformer. Then, the control circuit 121 looks up the amplitude of the DC bus ripple of the electrical angle from a table and calculates the switching frequency of the switching transistor based on the amplitude of the DC bus ripple. Subsequently, the switching frequency of the switching transistor is set to the PWM waveform generation module, which generates a PWM signal to control the switching transistor of the inverter circuit to turn on.

[0169] During this process, the inverter circuit also feeds back the operating status to the control circuit 121, and the control circuit 121 dynamically adjusts the control parameters according to the operating status.

[0170] In one embodiment, the mapping relationship between the amplitude and electrical angle of the DC bus ripple can be stored inside the motor controller or in other storage space accessible by the control circuit 121.

[0171] See Figure 14 , Figure 14 A flowchart illustrating another control process for the switching frequency of a switching transistor provided in an embodiment of this application is shown. Figure 14 This is illustrated as a zoned frequency conversion control process. Again, we take the example of a pre-established mapping relationship between the amplitude and electrical angle of the DC bus ripple, presented as a table.

[0172] like Figure 14 As shown, firstly, the status monitoring module monitors the motor's operating status parameters (such as the command value or instantaneous value of torque, power, and modulation amplitude) in real time and sends them to the strategy decision module. The strategy decision module determines the motor's operating range based on the motor's operating status parameters.

[0173] When the status parameter is not higher than the parameter threshold, the fixed frequency mode (i.e., the mode with a fixed switching frequency) is enabled, and the fixed frequency control module sends a fixed frequency to the PWM waveform generation module.

[0174] When the status parameter is higher than the parameter threshold, the frequency conversion mode (i.e., the mode in which the switching frequency changes dynamically) is activated. The frequency conversion control module calculates the dynamic frequency (the switching frequency that changes with the electrical angle) and sends the dynamic frequency to the PWM waveform generation module.

[0175] Finally, the PWM waveform generation module generates a PWM signal based on the received switching frequency to control the switching transistors of the inverter circuit to turn on.

[0176] This application provides an electric vehicle 100, which includes a motor controller 120 and a motor 110. The motor controller 120 includes a control circuit 121 and an inverter circuit. The inverter circuit includes a multi-phase bridge arm, and each phase bridge arm includes an upper bridge arm switch and a lower bridge arm switch. The midpoint of each phase bridge arm is used to connect to one phase winding of the motor 110. The control circuit 121 is used to control the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to periodically conduct so that the midpoint of the bridge arm outputs AC power to the motor 110 to drive the rotor of the motor 110 to rotate. During the rotation of the rotor of the motor 110, the electrical angle of the motor 110 changes periodically.

[0177] The control circuit 121 is used to control the switching frequency of the upper and lower bridge arm switches of each phase bridge arm to change with the change of the electrical angle of the motor 110 during the periodic change of the electrical angle of the motor 110. In this way, the operating efficiency of the motor controller 120 in the electric vehicle is guaranteed while the DC bus ripple is effectively suppressed, ensuring system performance and stability.

[0178] In one embodiment, the control circuit 121 is specifically used to control the switching frequency of the upper and lower bridge arm switches of each phase bridge arm to change periodically with the change of electrical angle. This synchronizes the change in the switching frequency of the switches with the periodic change in the amplitude of the DC bus ripple, achieving the effect of suppressing DC bus ripple or reducing switching losses at each electrical angle.

[0179] This application embodiment also provides a powertrain 200, which includes a motor controller 120 and a motor 110. The motor controller 120 includes a control circuit 121 and an inverter circuit. The inverter circuit includes a multi-phase bridge arm. Each phase bridge arm includes an upper bridge arm switch and a lower bridge arm switch. The midpoint of each phase bridge arm is used to connect to one phase winding of the motor 110. The control circuit 121 is used to control the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to periodically conduct so that the midpoint of the bridge arm outputs AC power to the motor 110 to drive the rotor of the motor 110 to rotate. During the rotation of the rotor of the motor 110, the electrical angle of the motor 110 changes periodically.

[0180] A control circuit 121 is used to control the switching frequency of the upper and lower bridge arm switches of each phase bridge arm to change with the change of the electrical angle of a motor 110 during the periodic change of the electrical angle of the motor 110. In this way, the operating efficiency of the motor controller 120 in the powertrain is guaranteed while the DC bus ripple is effectively suppressed, ensuring system performance and stability.

[0181] This application provides a power electronic device, which includes an inverter and a load. The inverter includes a control circuit 121 and an inverter circuit 122. The inverter circuit includes multi-phase bridge arms. Each phase of the multi-phase bridge arm includes an upper bridge arm switch and a lower bridge arm switch. The midpoint of each phase bridge arm is used to connect to the load. The control circuit 121 is used to control the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm to periodically conduct so that the midpoint of the bridge arm outputs AC power to the load to drive the load to run. During the operation of the load, the electrical angle changes periodically.

[0182] Control circuit 121 is used to: control the switching frequency of the upper and lower bridge arm switches of each phase bridge arm to change with the electrical angle during the periodic change of the electrical angle. This ensures inverter operating efficiency while effectively suppressing DC bus ripple, guaranteeing system performance and stability in power electronic equipment. In this case, the electrical angle can be controlled by... Figure 6 It is obtained in the manner described in the relevant description.

[0183] The power electronic equipment can be variable frequency air conditioners, variable frequency refrigerators, washing machines, industrial frequency converters, servo drives, and control units in renewable energy power generation systems, etc. It should be noted that this application does not specifically limit the type of power electronic equipment.

[0184] It is understood that all relevant content of each step involved in the above motor controller embodiment can be referenced in the embodiments of the electric vehicle, the powertrain, and the power electronic equipment, and will not be repeated here.

[0185] Finally, it should be noted that the above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A motor controller, characterized in that, The motor controller includes a control circuit and an inverter circuit. The inverter circuit includes multi-phase bridge arms, each phase of which includes an upper bridge arm switch and a lower bridge arm switch. The midpoint of each phase bridge arm is used to connect to one phase winding of the motor. The control circuit is used to control the upper and lower bridge arm switches of each phase bridge arm to periodically conduct so that the midpoint of the bridge arm outputs AC power to the motor to drive the rotor of the motor to rotate. During the rotation of the motor rotor, the electrical angle of the motor changes periodically. The control circuit is used for: During the periodic change of the electrical angle of the motor, the switching frequency of the upper and lower bridge arm switches of each phase bridge arm changes with the change of the electrical angle of the motor.

2. The motor controller according to claim 1, characterized in that, The control circuit is used to: Within one electrical angle cycle of the motor, which includes multiple consecutively distributed time periods, the control circuit is configured to: The switching frequency of the upper and lower bridge arm switches of each phase bridge arm is kept constant during any given time period. The switching frequencies of the upper and lower bridge arm switches of each phase bridge arm are controlled to be different in any two adjacent time periods.

3. The motor controller according to claim 1 or 2, characterized in that, The control circuit is specifically used for: The switching frequency of the upper and lower bridge arm switches of each phase bridge arm is controlled to change periodically with the change of electrical angle.

4. The motor controller according to claim 3, characterized in that, The control circuit is specifically used for: The switching frequency variation period of the upper and lower bridge arm switches of each phase bridge arm is controlled to be the ratio of 180 degrees to the number of phases of the motor.

5. The motor controller according to claim 1, characterized in that, When the multiphase bridge arm is a three-phase bridge arm, and the motor is a three-phase motor, the electrical angle range of the motor from 0 degrees to 60 degrees includes three continuously distributed angle intervals, and the control circuit is specifically used for: Within the first of the three angle intervals, the switching frequency of the upper and lower bridge arm switches of each phase bridge arm increases as the electrical angle of the motor increases. Within the second of the three angle intervals, the switching frequency of the upper and lower bridge arm switches of each phase bridge arm decreases as the electrical angle of the motor increases. Within the third of the three angle intervals, the switching frequency of the upper and lower bridge arm switches of each phase bridge arm increases as the electrical angle of the motor increases.

6. The motor controller according to claim 1, characterized in that, When the multiphase bridge arm is a three-phase bridge arm, and the motor is a three-phase motor, the electrical angle range of the motor from 0 degrees to 60 degrees includes two continuously distributed angle intervals, and the control circuit is specifically used for: Within the first angle interval of the two angle intervals, the switching frequency of the upper and lower bridge arm switches of each phase bridge arm decreases as the electrical angle of the motor increases. Within the second angle interval of the two angle intervals, the switching frequency of the upper and lower bridge arm switches of each phase bridge arm increases as the electrical angle of the motor increases.

7. The motor controller according to claim 5, characterized in that, The control circuit is specifically used for: The switching frequency of the upper and lower bridge arm switches of each phase bridge arm increases at a rate greater than the rate of increase of the electrical angle in the first angle interval than in the third angle interval.

8. The motor controller according to claim 2, characterized in that, The control circuit is specifically used for: The higher the speed of the motor, the shorter the duration for which the switching frequency of the upper and lower bridge arm switches of each phase bridge arm remains constant.

9. The motor controller according to claim 1, characterized in that, The control circuit is specifically used for: During the periodic change of the electrical angle of the motor, when the torque of the motor is less than or equal to the preset torque, the switching frequency of the upper and lower bridge arm switching transistors of each phase bridge arm is kept constant. During the periodic change of the electrical angle of the motor, when the torque of the motor is greater than the preset torque, the switching frequency of the upper and lower bridge arm switches of each phase bridge arm is controlled to change with the change of the electrical angle of the motor.

10. The motor controller according to claim 1, characterized in that, The control circuit is also used for: During the periodic change of the electrical angle of the motor, when the power of the motor is less than or equal to the preset power, the switching frequency of the upper and lower bridge arm switches of each phase bridge arm is kept constant. During the periodic change of the electrical angle of the motor, when the power of the motor is greater than the preset power, the switching frequency of the upper and lower bridge arm switches of each phase bridge arm is controlled to change with the change of the electrical angle of the motor.

11. The motor controller according to claim 1, characterized in that, The control circuit is also used for: When the temperature of the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm is less than the preset temperature and the difference between the temperature and the preset temperature is greater than or equal to the preset difference, the upper bridge arm switch and the lower bridge arm switch of each phase bridge arm are controlled to conduct at a first frequency during the electrical angle change process. When the temperature of the upper and lower bridge arm switching transistors of each phase bridge arm is lower than a preset temperature and the difference between the temperature and the preset temperature is less than a preset difference value, the switching frequency of the upper and lower bridge arm switching transistors of each phase bridge arm is controlled to be lower than the first frequency during the electrical angle change process.

12. The motor controller according to any one of claims 1-11, characterized in that, The control circuit is specifically used for: The switching frequency of the upper and lower bridge arm switches of each phase bridge arm is controlled within a preset frequency range.

13. An electric vehicle, characterized in that, The electric vehicle includes a motor controller and a motor. The motor controller includes a control circuit and an inverter circuit. The inverter circuit includes multi-phase bridge arms. Each phase bridge arm includes an upper bridge arm switch and a lower bridge arm switch. The midpoint of each phase bridge arm is used to connect to one phase winding of the motor. The control circuit is used to control the upper and lower bridge arm switches of each phase bridge arm to periodically conduct so that the midpoint of the bridge arm outputs AC power to the motor to drive the rotor of the motor to rotate. During the rotation of the motor rotor, the electrical angle of the motor changes periodically. The control circuit is used for: During the periodic change of the electrical angle of the motor, the switching frequency of the upper and lower bridge arm switches of each phase bridge arm changes with the change of the electrical angle of the motor.

14. The electric vehicle according to claim 13, characterized in that, The control circuit is specifically used for: The switching frequency of the upper and lower bridge arm switches of each phase bridge arm is controlled to change periodically with the change of electrical angle.

15. A powertrain, characterized in that, The powertrain includes a motor controller and a motor. The motor controller includes a control circuit and an inverter circuit. The inverter circuit includes multi-phase bridge arms. Each phase bridge arm includes an upper bridge arm switch and a lower bridge arm switch. The midpoint of each phase bridge arm is used to connect to one phase winding of the motor. The control circuit is used to control the upper and lower bridge arm switches of each phase bridge arm to periodically conduct so that the midpoint of the bridge arm outputs AC power to the motor to drive the rotor of the motor to rotate. During the rotation of the motor rotor, the electrical angle of the motor changes periodically. The control circuit is used for: During the periodic change of the electrical angle of the motor, the switching frequency of the upper and lower bridge arm switches of each phase bridge arm changes with the change of the electrical angle of the motor.

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