Locked-rotor protection control method, motor controller, driving motor and generator

Abstract

The invention provides a locked-rotor protection control method, a motor controller, a driving motor and a generator, and the method comprises the steps: obtaining a target switching frequency and a first switching frequency of the motor controller when the motor is in a locked-rotor state; determining an intermediate switching frequency based on the first switching frequency and a target switching frequency; wherein the target switching frequency is smaller than the first switching frequency, and the intermediate switching frequency is located between the target switching frequency and the first switching frequency; the motor controller is controlled to be switched from the first switching frequency to the intermediate switching frequency, and the motor controller is controlled to continue for a set duration at the intermediate switching frequency; and controlling the motor controller to switch from the intermediate switching frequency to the target switching frequency. According to the mode, the motor phase current impact is reduced, and the reliability of a motor driving system is improved.

Description

Technical Field

[0001] This invention relates to the field of motor control technology, and in particular to a stall protection control method, a motor controller, a drive motor, and a generator. Background Technology

[0002] In a motor drive system, when the motor enters a stalled state, the temperature of the switching power devices in the motor controller rises. Related technologies adjust the switching frequency of the switching power devices in the motor controller from a higher frequency to a lower frequency when the motor enters a stalled state, thereby reducing the rate of temperature rise. However, this method can cause current surges in the motor phases, reducing the reliability of the motor drive system. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a stall protection control method, a motor controller, a drive motor and a generator, so as to improve the reliability of the motor drive system.

[0004] In a first aspect, embodiments of the present invention provide a stall protection control method, the method comprising: acquiring a target switching frequency and a first switching frequency of a motor controller when the motor is in a stall state; determining an intermediate switching frequency based on the first switching frequency and the target switching frequency; wherein the target switching frequency is less than the first switching frequency, and the intermediate switching frequency is located between the target switching frequency and the first switching frequency; controlling the motor controller to switch from the first switching frequency to the intermediate switching frequency, and controlling the motor controller to continuously switch at the intermediate switching frequency for a set duration; and controlling the motor controller to switch from the intermediate switching frequency to the target switching frequency.

[0005] Before the step of obtaining the first switching frequency and target switching frequency of the motor controller in response to the motor entering a stall state, the method further includes: switching the switching frequency of the motor controller to the first switching frequency in response to the motor speed being less than a first speed threshold; and determining that the motor has entered a stall state in response to the motor speed being less than a second speed threshold and the motor torque being greater than a first torque threshold.

[0006] The aforementioned first switching frequency is the minimum switching frequency at which the motor meets the specified performance indicators under the current bus voltage.

[0007] The steps for obtaining the target switching frequency of the motor controller include: obtaining the motor output torque after the motor enters a stall state; if the motor output torque is greater than a second torque threshold, determining the target switching frequency of the motor controller as a preset first frequency value; if the motor output torque is less than or equal to the second torque threshold, determining the target switching frequency of the motor controller as a preset second frequency value; wherein the second frequency value is greater than the first frequency value.

[0008] The above method also includes: continuously monitoring the motor output torque under stall conditions; if the motor output torque is less than a third torque threshold, determining the target switching frequency of the motor controller to a preset second frequency value; wherein the third torque threshold is less than the second torque threshold; if the motor output torque is greater than the second torque threshold, determining the target switching frequency of the motor controller to a preset first frequency value.

[0009] The above method further includes: triggering a preset stall flag in response to the motor entering a stall state; wherein the stall flag is used to: indicate that the motor has entered a stall state; and to obtain the target switching frequency of the motor controller in response to the stall flag being triggered.

[0010] The above-mentioned step of determining the intermediate switching frequency based on the first switching frequency and the target switching frequency includes: determining the intermediate switching frequency and setting the duration based on preset frequency setting conditions; wherein, the frequency setting conditions include: the instantaneous peak value of the motor phase current is minimized when the motor controller switches from the first switching frequency to the target switching frequency.

[0011] The steps for controlling the motor controller to switch from the first switching frequency to the intermediate switching frequency include: when the motor enters a stall state, triggering the switching frequency switching flag; wherein, the switching frequency switching flag is used to: instruct the motor controller to switch the switching frequency; and in response to the triggering of the switching frequency switching flag, controlling the motor controller to switch from the first switching frequency to the intermediate switching frequency.

[0012] After the step of controlling the motor controller to continuously set the intermediate switching frequency for a set duration, the method further includes: canceling the trigger switching frequency switching flag.

[0013] The above method also includes: in response to the motor exiting the stall state, controlling the motor controller to switch from the target switching frequency to the first switching frequency.

[0014] The above method also includes: canceling the stall flag in response to the motor exiting the stall state.

[0015] In a second aspect, embodiments of the present invention provide a motor controller, which includes a processor and a memory. The memory stores computer-executable instructions that can be executed by the processor, and the processor executes the computer-executable instructions to implement the stall protection control method of any of the first aspects.

[0016] Thirdly, embodiments of the present invention provide a drive motor, which includes a motor controller as described in the second aspect.

[0017] Fourthly, embodiments of the present invention provide a generator, which includes a motor controller as described in the second aspect.

[0018] The embodiments of the present invention bring the following beneficial effects:

[0019] The aforementioned stall protection control method, motor controller, drive motor, and generator, wherein the method includes: acquiring a target switching frequency and a first switching frequency of the motor controller when the motor is in a stall state; determining an intermediate switching frequency based on the first switching frequency and the target switching frequency; wherein the target switching frequency is less than the first switching frequency, and the intermediate switching frequency is located between the target switching frequency and the first switching frequency; controlling the motor controller to switch from the first switching frequency to the intermediate switching frequency, and controlling the motor controller to continuously switch at the intermediate switching frequency for a set duration; and controlling the motor controller to switch from the intermediate switching frequency to the target switching frequency.

[0020] In this method, an intermediate switching frequency between the first switching frequency and the target switching frequency is determined, and the motor controller is controlled to switch from the first switching frequency to the intermediate switching frequency for a set duration, and then switch to the target switching frequency. By setting an intermediate switching frequency between the first switching frequency and the target switching frequency, the amplitude of each switching frequency can be reduced, the motor phase current impact when the switching frequency is adjusted from a higher frequency to a lower frequency can be reduced, and the reliability of the motor drive system can be improved.

[0021] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained in accordance with the structures particularly pointed out in the description, claims and drawings.

[0022] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 A flowchart of a stall protection control method provided in an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram illustrating the switching frequency when a motor enters a stalled state, as provided in an embodiment of the present invention.

[0026] Figure 3This is a schematic diagram illustrating the determination of a target switching frequency in a stalled state, as provided in an embodiment of the present invention.

[0027] Figure 4 A stall protection control flowchart for a motor controller is provided in an embodiment of the present invention;

[0028] Figure 5 This is a schematic diagram of the structure of a motor controller provided in an embodiment of the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Currently, permanent magnet synchronous motor drive systems are increasingly widely used in new energy vehicles. As the power source for the entire vehicle, the motor drive system needs to operate safely and reliably under various operating conditions. The motor controller uses IGBTs (Insulated Gate Bipolar Transistors) as switching power devices, and a three-phase bridge inverter circuit converts the DC power from the battery to the three-phase AC power from the motor. During the operation of the motor controller, the current flowing through it in the on-state generates conduction losses, while turn-off losses occur during both on and off processes. Both conduction and turn-off losses cause the IGBT to heat up. Since IGBTs have limited temperature tolerance, IGBT temperature rise is one of the factors to consider in the motor controller.

[0031] On the one hand, when stalled conditions such as parking on a slope or starting with high torque occur, the current will be concentrated on the IGBT of the fixed bridge arm, which will cause the IGBT temperature to rise rapidly.

[0032] On the other hand, the IGBT's turn-on and turn-off rates are related to the switching frequency during stall conditions; the higher the switching frequency, the more severe the IGBT heating. However, due to factors such as heat transfer and the placement of external temperature sensors, the temperature collected by the motor controller cannot accurately reflect the current heating state of the IGBT in real time. Therefore, the motor controller needs a dedicated stall protection strategy to ensure the safety of the vehicle during stall conditions.

[0033] Under ideal stall conditions, the motor rotor is stationary, and the current cannot be reversed, thus concentrating on the fixed IGBT arm. However, the motor phase current determines the magnitude of the motor's output torque; reducing the current to decrease IGBT heating will lead to a decrease in output torque.

[0034] Furthermore, the switching frequency during stalled operation determines the IGBT's turn-on and turn-off rates; reducing the switching frequency also reduces IGBT heat generation. However, in non-stalled operation, considering the sinusoidal nature of the motor phase current and the motor's NVH performance, the switching frequency at low speeds often needs to be set higher than the stalled switching frequency. When the motor enters a stalled state, the instantaneous switch from a higher to a lower stalled switching frequency can cause a current surge in the motor phase current due to the dead-zone effect, which can lead to overcurrent faults in severe cases.

[0035] Based on the above problems, this embodiment provides a stall protection control method, a motor controller, a drive motor, and a generator, which can be applied to a motor controller or a device containing a motor controller.

[0036] To facilitate understanding of this embodiment, a stall protection control method disclosed in this embodiment of the invention will first be described in detail. Figure 1 This is a flowchart of a stall protection control method according to an embodiment of the present invention. The method includes:

[0037] Step S101: Obtain the target switching frequency and the first switching frequency of the motor controller when the motor is in a stalled state;

[0038] The aforementioned stalled state typically refers to a situation where the motor continues to output torque even when its speed is zero. Torque is a special force that causes an object to rotate; under fixed power conditions, torque is inversely proportional to motor speed. The target switching frequency is usually determined based on the motor's output torque. The target switching frequency is the final switching frequency that the motor controller adjusts to.

[0039] In actual implementation, before the motor enters the stall state, if the motor speed is less than the first speed threshold, the switching frequency of the motor controller is switched to the first switching frequency; if the motor speed is less than the second speed threshold and the motor torque is greater than the first torque threshold, then the motor is determined to enter the stall state.

[0040] Specifically, after the motor enters a stall state, the first switching frequency currently being used by the motor controller is obtained. Furthermore, the motor's output torque is obtained, and the target switching frequency of the motor controller is determined based on this output torque.

[0041] Optionally, a second torque threshold is preset for the motor's output torque. When the motor's output torque is greater than the second torque threshold, the target switching frequency of the motor controller is determined to be a first preset frequency value; when the motor's output torque is less than or equal to the second torque threshold, the target switching frequency of the motor controller is determined to be a second preset frequency value that is greater than the first preset frequency value.

[0042] Additionally, in stalled mode, a third torque threshold, less than the second torque threshold, can be preset for the motor. When the motor's output torque is less than the third torque threshold, the target switching frequency of the motor controller is set to the second preset frequency value.

[0043] Optionally, a stall flag is preset. When the motor enters a stall state, the stall flag is triggered, and then the target switching frequency of the motor controller is obtained.

[0044] Step S102: Determine an intermediate switching frequency based on the first switching frequency and the target switching frequency; wherein the target switching frequency is less than the first switching frequency, and the intermediate switching frequency is located between the target switching frequency and the first switching frequency.

[0045] The aforementioned intermediate switching frequency is usually determined based on pre-set frequency conditions.

[0046] Optionally, under frequency conditions, the instantaneous peak value of the motor phase current is minimized when the motor controller switches from the first switching frequency to the target switching frequency.

[0047] In actual implementation, after obtaining the first switching frequency and the target switching frequency, the intermediate switching frequency between the target switching frequency and the first switching frequency is determined when the motor controller switches from the first switching frequency to the smaller target switching frequency.

[0048] Step S103: Control the motor controller to switch from the first switching frequency to the intermediate switching frequency, and control the motor controller to continuously set the duration at the intermediate switching frequency.

[0049] The above-mentioned duration is usually determined based on the preset frequency conditions.

[0050] Optionally, a switching frequency switching flag is preset. When the motor enters a stall state, the switching frequency switching flag is triggered to instruct the motor controller to switch the switching frequency.

[0051] In actual implementation, when the motor enters a stall state, the switching frequency switching flag is triggered, and then the motor controller is controlled to switch from the first switching frequency currently in use to an intermediate switching frequency.

[0052] Furthermore, the motor controller is controlled to maintain the intermediate switching frequency for a set duration. After the motor controller has maintained the intermediate switching frequency for the set duration, the trigger switching frequency switching flag is deactivated.

[0053] Step S104: Control the motor controller to switch from the intermediate switching frequency to the target switching frequency.

[0054] In other words, after the motor controller has been continuously operating at the intermediate switching frequency for a set duration, the motor controller is switched from the intermediate switching frequency to a smaller target switching frequency.

[0055] Optionally, when the motor exits the stall state, the motor controller is switched from the target switching frequency to the first switching frequency. At the same time, the stall flag is deactivated.

[0056] The above-mentioned stall protection control method obtains the target switching frequency and the first switching frequency of the motor controller when the motor is in a stall state; determines the intermediate switching frequency based on the first switching frequency and the target switching frequency; wherein the target switching frequency is less than the first switching frequency, and the intermediate switching frequency is located between the target switching frequency and the first switching frequency; controls the motor controller to switch from the first switching frequency to the intermediate switching frequency, and controls the motor controller to continuously switch at the intermediate switching frequency for a set duration; controls the motor controller to switch from the intermediate switching frequency to the target switching frequency.

[0057] In this method, an intermediate switching frequency between the first switching frequency and the target switching frequency is determined, and the motor controller is controlled to switch from the first switching frequency to the intermediate switching frequency for a set duration, and then switch to the target switching frequency. By setting an intermediate switching frequency between the first switching frequency and the target switching frequency, the amplitude of each switching frequency can be reduced, the motor phase current impact when the switching frequency is adjusted from a higher frequency to a lower frequency can be reduced, and the reliability of the motor drive system can be improved.

[0058] In one embodiment, see Figure 2 The diagram shows the switching frequency when the motor enters a stall state. Figure 2 In this process, before the motor enters a stalled state, the switching frequency of the motor controller is the first switching frequency. When the motor enters a stalled state, the switching frequency of the motor controller switches from the first switching frequency to an intermediate switching frequency.

[0059] After the switching frequency is continuously set to the intermediate switching frequency for a set period of time, and the time reaches the first time threshold, the motor controller switches from the intermediate switching frequency to the target switching frequency, i.e., the stall switching frequency.

[0060] In one alternative approach, in response to the motor speed being less than a first speed threshold, the switching frequency of the motor controller is switched to the first switching frequency.

[0061] The aforementioned first speed threshold is usually preset. Specifically, the current motor speed is compared with the first speed threshold, and the switching frequency of the motor controller is controlled based on the comparison result.

[0062] In actual implementation, the motor speed is monitored in real time; after the motor enters a stall state, if the motor speed is less than the first speed threshold, the switching frequency of the motor controller is switched to the first switching frequency, which conforms to the calibration principle.

[0063] Furthermore, the aforementioned first switching frequency is: the minimum switching frequency at which the motor meets the specified performance indicators under the current bus voltage.

[0064] Bus voltage refers to the DC voltage output from the motor controller to the motor, which is usually supplied by a power source, capacitor, or charger.

[0065] The performance indicators specified above are usually NVH performance indicators, where NVH is an abbreviation for Noise, Vibration, and Harshness.

[0066] In one example, the motor's bus voltage is monitored in real time; under the current bus voltage, the minimum switching frequency required for the motor to meet NVH performance indicators is set as the first switching frequency.

[0067] In the above method, the switching frequency of the motor controller is adjusted according to the motor speed before the motor enters the stall state, which can further reduce the amplitude of the motor switching frequency, thereby reducing the current surge of the phase current caused by the motor switching frequency.

[0068] In one alternative approach, the motor is determined to be in a stall state in response to the motor speed being less than a second speed threshold and the motor torque being greater than a first torque threshold.

[0069] The aforementioned second speed threshold and first torque threshold are usually preset.

[0070] In actual implementation, the motor speed and torque are monitored in real time. When the motor speed is less than the second speed threshold and the motor torque is greater than the first torque threshold, the motor is determined to be in a stall state.

[0071] The following provides a specific implementation method for obtaining the target switching frequency of the motor controller.

[0072] In one alternative approach, the motor output torque is obtained after the motor enters a stall state; based on the motor output torque, the target switching frequency of the motor controller is determined.

[0073] First, after the motor enters a stall state, the motor output torque is obtained. This motor output torque is usually related to the motor's output power and speed.

[0074] Next, to reduce the heat generated by the motor controller during stall, the target switching frequency of the motor controller is determined based on the motor output torque. When the motor output torque is greater than the second torque threshold, or when the motor output torque is less than or equal to the second torque threshold, the target switching frequency of the motor controller is set to different preset frequency values.

[0075] Furthermore, if the motor output torque is greater than the second torque threshold, the target switching frequency of the motor controller is determined to be a preset first frequency value; if the motor output torque is less than or equal to the second torque threshold, the target switching frequency of the motor controller is determined to be a preset second frequency value; wherein, the second frequency value is greater than the first frequency value.

[0076] The first and second frequency values ​​mentioned above are usually preset.

[0077] It should be noted that the first and second frequency values ​​can be obtained experimentally. If the motor output torque is low, the target switching frequency is set higher to reduce the heat generated by the motor controller; if the motor output torque is high, the target switching frequency is set lower to reduce the heat and noise of the motor controller. By balancing these two performance aspects, the first and second frequency values ​​are determined.

[0078] like Figure 3 In the example shown, when the motor output torque is greater than the second torque threshold, the target switching frequency of the motor controller is determined to be a lower first frequency value. When the motor output torque is less than or equal to the second torque threshold, the target switching frequency of the motor controller is determined to be a higher second frequency value.

[0079] Furthermore, under stall conditions, the motor output torque is continuously monitored; if the motor output torque is less than the third torque threshold, the target switching frequency of the motor controller is determined to be a preset second frequency value; wherein, the third torque threshold is less than the second torque threshold; if the motor output torque is greater than the second torque threshold, the target switching frequency of the motor controller is determined to be a preset first frequency value.

[0080] In practice, the output torque of the motor is continuously monitored when the motor is in a stalled state.

[0081] like Figure 3 In the example shown, the preset third torque threshold is less than the second torque threshold; when the motor output torque is less than the third torque threshold, the target switching frequency of the motor controller is determined to be the second frequency value. When the motor output torque is greater than the second torque threshold, the target switching frequency of the motor controller is determined to be the first frequency value.

[0082] It should be noted that when the motor output torque is between the third torque threshold and the second torque threshold, the target switching frequency of the motor controller is determined based on the original frequency value.

[0083] For example, in Figure 3In the process, when the motor first enters the stall state, the target switching frequency is the second frequency value of 1000 Hz. After the torque exceeds the second torque threshold of 100 Nm, the target switching frequency is switched to the first frequency value of 500 Hz. Then, after the torque falls below the third torque threshold of 50 Nm, the target switching frequency switches back to the second frequency value of 1000 Hz.

[0084] It should be noted that after the motor enters a stall state, the target switching frequency can be adjusted in real time according to the motor output torque.

[0085] In one alternative approach, a preset stall flag is triggered in response to the motor entering a stall state; wherein the stall flag is used to: indicate that the motor has entered a stall state; and to obtain the target switching frequency of the motor controller in response to the stall flag being triggered.

[0086] In other words, when the motor enters a stall state, a preset stall flag is triggered, indicating that the motor has entered the stall state. For example, initially, the stall flag is 0, and when the stall flag is 1, it means that the stall flag has been triggered.

[0087] If the stall flag is triggered, the target switching frequency of the motor controller is obtained.

[0088] In one optional approach, an intermediate switching frequency and a set duration are determined based on preset frequency setting conditions; wherein the frequency setting conditions include: the instantaneous peak value of the motor phase current is minimized when the motor controller switches from the first switching frequency to the target switching frequency.

[0089] Motor phase current refers to the current in each phase of the motor windings. For example, in a three-phase power supply, the current flowing through each phase load is called phase current.

[0090] In actual implementation, based on the frequency setting condition that minimizes the instantaneous peak value of the motor phase current during the switching frequency of the motor controller switching from the first switching frequency to the target switching frequency, an intermediate switching frequency between the target switching frequency and the first switching frequency was determined through experiments. Simultaneously, the set duration for maintaining the motor controller's switching frequency at the intermediate switching frequency was determined.

[0091] In one alternative approach, when the motor enters a stall state, a switching frequency switching flag is triggered; wherein the switching frequency switching flag is used to: instruct the motor controller to switch the switching frequency; and in response to the triggering of the switching frequency switching flag, control the motor controller to switch from a first switching frequency to an intermediate switching frequency.

[0092] In other words, when the motor enters a stall state, the switching frequency switching flag is triggered, instructing the motor controller to switch the switching frequency. For example, initially, the switching frequency switching flag is 0; when it becomes 1, it indicates that the switching frequency switching flag has been triggered.

[0093] If the switching frequency switching flag is triggered, the motor controller is controlled to switch from the first switching frequency to a smaller intermediate switching frequency.

[0094] In one alternative approach, the motor controller cancels the trigger switching frequency switching flag after the intermediate switching frequency has been continuously set for a set duration.

[0095] In other words, the switching frequency of the motor controller is maintained at the intermediate switching frequency, and after a set duration, the switching frequency switching flag is deactivated. For example, the switching frequency switching flag is reset to 0.

[0096] In one alternative approach, in response to the motor exiting the stall state, the motor controller is controlled to switch from the target switching frequency to the first switching frequency.

[0097] In practice, if the motor exits the stall state, the motor controller is controlled to switch the switching frequency from the target switching frequency to the first switching frequency.

[0098] It should be noted that when the motor controller switches from the target switching frequency to the first switching frequency, the motor phase current will only decrease momentarily and will not increase momentarily, so the motor controller switching frequency can be switched directly.

[0099] In one alternative approach, the stall flag is deactivated in response to the motor exiting the stall state. That is, when the motor exits the stall state, the stall flag is deactivated. For example, the stall flag is reset to 0.

[0100] In one embodiment, see Figure 4 The diagram shows the stall protection control logic flowchart for the motor controller. The following describes the steps after the stall protection control of the motor controller begins.

[0101] Step S401: Determine whether the motor speed is less than the first speed threshold; if yes, proceed to step S402; otherwise, proceed to step S403.

[0102] Step S402: Set the switching frequency of the motor controller to the first switching frequency;

[0103] Step S403: Maintain the current switching frequency and proceed to step S411;

[0104] Step S404: Determine whether the motor speed is less than the second speed threshold and whether the motor output torque is greater than the first torque threshold; if yes, proceed to step S405; otherwise, proceed to step S406.

[0105] Step S405: Trigger the stall flag and the switching frequency switching flag, determine the value of the target switching frequency based on the current motor output torque, and execute step S407.

[0106] Step S406: Maintain the current switching frequency and proceed to step S411;

[0107] Step S407: Switch the switching frequency of the motor controller to the intermediate switching frequency, and trigger the time count by switching frequency switching flag bit;

[0108] Step S408: Determine whether the time count is greater than the first time threshold; if yes, proceed to step S409; otherwise, proceed to step S410.

[0109] Step S409: Switch the switching frequency of the motor controller to the target switching frequency, cancel the trigger of the switching frequency switching flag, and execute step S411.

[0110] Step S410: Maintain the current switching frequency and proceed to step S411;

[0111] Step S411, step complete.

[0112] This embodiment has the following advantages:

[0113] This embodiment proposes a motor controller stall control method that triggers a stall flag and a switching frequency switching flag when the motor enters a stall state. When the stall flag is triggered, the target switching frequency of the motor controller is set to the target switching frequency, i.e., the stall switching frequency. When the switching frequency switching flag is triggered, the motor controller's switching frequency first switches from a first switching frequency to an intermediate switching frequency. After the duration reaches a set first time threshold, the switching frequency switching flag is deactivated, and simultaneously, the motor controller's switching frequency switches from the intermediate switching frequency to a second switching frequency. This switching frequency switching method can effectively reduce the current surge of the motor phase current.

[0114] This embodiment also provides a motor controller, which includes a processor and a memory. The memory stores machine-executable instructions that can be executed by the processor, and the processor executes the machine-executable instructions to implement the above-mentioned stall protection control method.

[0115] This embodiment comprehensively considers the control performance under both low-speed and stalled motor conditions. By real-time monitoring of motor speed and bus voltage, a first switching frequency is calibrated to ensure the sinusoidal nature of motor phase current and NVH performance under low-speed conditions. By real-time monitoring of motor speed and torque, a target switching frequency is calibrated to achieve the goal of ensuring the accuracy of motor output torque while reducing IGBT heating under stalled conditions.

[0116] Furthermore, this embodiment solves the current surge problem in the motor phase current when the motor controller switches from the first switching frequency to the target switching frequency by switching the switching frequency, thus effectively improving the reliability of the system.

[0117] See Figure 5 As shown, the electronic device includes a processor 100 and a memory 101. The memory 101 stores computer-executable instructions that can be executed by the processor 100. The processor 100 executes the computer-executable instructions to implement the above-described stall protection control method.

[0118] Furthermore, Figure 5 The electronic device shown also includes a bus 102 and a communication interface 103, with the processor 100, the communication interface 103 and the memory 101 connected via the bus 102.

[0119] The memory 101 may include high-speed random access memory (RAM) or non-volatile memory, such as at least one disk storage device. Communication between this system network element and at least one other network element is achieved through at least one communication interface 103 (which can be wired or wireless), such as the Internet, wide area network, local area network, or metropolitan area network. The bus 102 may be an ISA bus, PCI bus, or EISA bus, etc. The bus can be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 5 The symbol is represented by a single double-headed arrow, but this does not mean that there is only one bus or one type of bus.

[0120] Processor 100 may be an integrated circuit chip with signal processing capabilities. In implementation, each step of the above method can be completed by the integrated logic circuitry in the hardware of processor 100 or by instructions in software form. Processor 100 may be a general-purpose processor, including a Central Processing Unit (CPU), a Network Processor (NP), etc.; it may also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this invention. The general-purpose processor may be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this invention can be directly manifested as execution by a hardware decoding processor, or execution by a combination of hardware and software modules in the decoding processor. The software module can reside in a readily available storage medium in the art, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, or registers. This storage medium is located in memory 101, and the processor 100 reads the information from memory 101 and, in conjunction with its hardware, completes the steps of the method described in the foregoing embodiments.

[0121] This embodiment provides a drive motor, which includes a motor controller.

[0122] This embodiment provides a generator, which includes a motor controller.

[0123] The stall protection control method proposed in this embodiment is applicable not only to motor controllers using IGBTs as switching power devices, but also to motor controllers containing other types of power devices such as SiC and MOSFETs. This embodiment uses a new energy vehicle drive motor as an application scenario for explanation, but the method can also be applied to generators.

[0124] Furthermore, in the description of the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances.

[0125] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0126] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0127] Finally, it should be noted that the above embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A stall protection control method characterized by, The method comprises: obtaining a target switching frequency and a first switching frequency of a motor controller when the motor is in a locked-rotor state; determining an intermediate switching frequency based on the first switching frequency and the target switching frequency; wherein the target switching frequency is less than the first switching frequency, and the intermediate switching frequency is between the target switching frequency and the first switching frequency; controlling the motor controller to switch from the first switching frequency to the intermediate switching frequency, and controlling the motor controller to maintain the intermediate switching frequency for a set time period; controlling the motor controller to switch from the intermediate switching frequency to the target switching frequency.

2. The method of claim 1, wherein, Before the steps of obtaining a target switching frequency and a first switching frequency of a motor controller when the motor is in a locked-rotor state, the method further comprises: in response to the motor speed of the motor being less than a first speed threshold, switching the switching frequency of the motor controller to the first switching frequency; in response to the motor speed of the motor being less than a second speed threshold and the motor torque of the motor being greater than a first torque threshold, determining that the motor enters a locked-rotor state.

3. The method according to claim 1 or 2, characterized in that, The first switching frequency is the minimum switching frequency at which the motor meets a specified performance indicator under the current bus voltage.

4. The method of claim 1, wherein, The step of obtaining a target switching frequency comprises: obtaining the motor output torque of the motor after the motor enters the locked-rotor state; if the motor output torque is greater than a second torque threshold, determining the target switching frequency of the motor controller as a preset first frequency value; if the motor output torque is less than or equal to the second torque threshold, determining the target switching frequency of the motor controller as a preset second frequency value; wherein the second frequency value is greater than the first frequency value.

5. The method of claim 4, wherein, The method further comprises: continuously monitoring the motor output torque in the locked-rotor state; if the motor output torque is less than a third torque threshold, determining the target switching frequency of the motor controller as the preset second frequency value; wherein the third torque threshold is less than the second torque threshold; if the motor output torque is greater than the second torque threshold, determining the target switching frequency of the motor controller as the preset first frequency value.

6. The method of claim 1, wherein, The method further comprises: in response to the motor entering the locked-rotor state, triggering a preset locked-rotor flag; wherein the locked-rotor flag is used to indicate that the motor enters the locked-rotor state; in response to the locked-rotor flag being triggered, obtaining the target switching frequency of the motor controller.

7. The method of claim 1, wherein, The step of determining an intermediate switching frequency based on the first switching frequency and the target switching frequency comprises: determining the intermediate switching frequency and the set time period based on a preset frequency setting condition; wherein the frequency setting condition comprises that the instantaneous peak value of the motor phase current is the smallest when the motor controller switches from the first switching frequency to the target switching frequency.

8. The method of claim 1, wherein, The step of controlling the motor controller to switch from the first switching frequency to the intermediate switching frequency comprises: triggering a switching frequency switching flag when the motor enters the locked-rotor state; wherein the switching frequency switching flag is used to indicate that the motor controller switches the switching frequency; in response to the switch frequency switching flag being triggered, controlling the motor controller to switch from the first switch frequency to the intermediate switch frequency.

9. The method of claim 1, wherein, after the step of controlling the motor controller to keep the intermediate switch frequency for a set time length, the method further comprises: canceling triggering the switch frequency switching flag.

10. The method of claim 1, wherein, The method further comprises: in response to the motor exiting the stall state, controlling the motor controller to switch from the target switch frequency to the first switch frequency.

11. The method of claim 10, wherein, The method further comprises: in response to the motor exiting the stall state, canceling triggering the stall flag.

12. An electric machine controller characterized by The motor controller comprises a processor and a memory, the memory stores computer executable instructions capable of being executed by the processor, and the processor executes the computer executable instructions to implement the stall protection control method in any one of claims 1-11.

13. A drive motor characterized by The driving motor comprises the motor controller in claim 12.

14. An electrical generator characterized by The generator comprises the motor controller in claim 12.

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