Motor overload protection method, motor controller, automobile, and storage medium

Abstract

A motor overload protection method, a motor controller, a vehicle, and a storage medium are disclosed, the method including the steps of: collecting an effective value of a present phase current of a motor (S101); integrating the effective value of the present phase current over time to obtain a first integral value (S102); obtaining a first threshold value (S103); performing overload detection based on the first threshold value and the first integral value (S104); and, if an overload exists, determining a target limit current for operation of the motor and controlling the operation of the motor based on the target limit current (S105).

Description

Technical Field

[0001] (Cross - reference to related applications) This disclosure is based on and claims priority to a Chinese patent application with application number 202111152401.5 and filing date September 29, 2021, and all of its contents are incorporated herein by reference.

[0002] This disclosure relates to a motor overload protection method, a motor controller, a vehicle, and a storage medium.

Background Art

[0003] The motor overload protection means of the current motor drive system of vehicles generally includes a first type of means for detecting whether the actual temperature of the motor drive system reaches the temperature limit to determine whether overload protection is required, and a second type of means for monitoring the power flowing through the motor and realizing overload protection based on the power.

Summary of the Invention

Problems to be Solved by the Invention

[0004] This disclosure provides a motor overload protection method, a motor controller, a vehicle, and a storage medium.

[0005] The motor overload protection method includes collecting the effective value of the current phase current of the motor; time - integrating the effective value of the current phase current to obtain a first integral value; obtaining a first threshold value; performing overload detection based on the first threshold value and the first integral value; when overload exists, determining a target limit current for the operation of the motor and controlling the operation of the motor based on the target limit current.

[0006] In one embodiment of this disclosure, the step of obtaining the first threshold value is Obtaining a second threshold by looking up a current-time integral threshold table based on the effective value of the current phase current; Obtaining the current current frequency and comparing the current current frequency with a current frequency threshold; When the current current frequency is less than the current frequency threshold, correcting the second threshold based on a target correction coefficient to obtain the first threshold; When the current current frequency is greater than or equal to the current frequency threshold, determining the second threshold as the first threshold.

[0007] In an embodiment of the present disclosure, the step of correcting the second threshold based on a target correction coefficient to obtain the first threshold includes: Processing the second threshold based on the target correction coefficient using a threshold correction formula to obtain the first threshold; The threshold correction formula is V1 = K * V2, where V1 is the first threshold, V2 is the second threshold, and K is the target correction coefficient.

[0008] In an embodiment of the present disclosure, the step of obtaining the first threshold includes: Obtaining a second threshold by looking up a current-time integral threshold table based on the effective value of the current phase current; Obtaining the current motor rotation speed and comparing the current motor rotation speed with an overload rotation speed threshold; When the current motor rotation speed is less than the overload rotation speed threshold, obtaining an overload integral gain threshold and obtaining the first threshold based on the second threshold and the overload integral gain threshold; When the current motor rotation speed is less than or equal to the overload rotation speed threshold, determining the second threshold as the first threshold.

[0009] In an embodiment of the present disclosure, before the step of obtaining a second threshold by looking up a current-time integral threshold table based on the effective value of the current phase current, the motor overload protection method further includes: Obtaining the test output current and the target operating time corresponding to the test output current; Determining the rated parameters corresponding to the test output current based on a predetermined constant and the target operating time; Time-integrating the rated parameters to obtain the rated threshold corresponding to the test output current; Further including forming a current-time integration threshold table based on the test output current, the target operating time, the rated parameters, and the rated threshold.

[0010] In an embodiment of the present disclosure, the step of performing overload detection based on the first threshold and the first integration value includes: Comparing the first integration value with the first threshold; When the first integration value is greater than the first threshold, determining that an overload exists; When the first integration value is less than or equal to the first threshold, determining that no overload exists.

[0011] In an embodiment of the present disclosure, the step of determining the target limiting current for the operation of the motor includes: Obtaining the current overload factor; Limiting the effective value of the current phase current using the current overload factor to obtain the target limiting current.

[0012] In an embodiment of the present disclosure, the step of limiting the effective value of the current phase current using the current overload factor to obtain the target limiting current includes: Using a limiting current calculation formula to calculate based on the current overload factor and the effective value of the current phase current to obtain the target limiting current, where the limiting current calculation formula is It = (Ic * Kco) / R, where It is the target limiting current, Ic is the effective value of the current phase current, Kco is the current overload factor, and R is a constant.

[0013] In one embodiment of the present disclosure, after the step of performing overload detection based on the first threshold value and the first integration value, the motor overload protection method includes: obtaining a current overload coefficient; when overload exists, obtaining a step width for decreasing the overload coefficient, and for each overload protection period, decreasing the current overload coefficient using the step width for decreasing the overload coefficient to obtain an updated overload coefficient; when overload does not exist, obtaining a step width for increasing the overload coefficient, and for each overload recovery period, increasing the current overload coefficient using the step width for increasing the overload coefficient to obtain an updated overload coefficient; and further including the step of performing a limit process on the updated overload coefficient to obtain an updated current overload coefficient.

[0014] In one embodiment of the present disclosure, the step of obtaining a step width for decreasing the overload coefficient includes: processing the effective value of the current phase current using a step width calculation formula for decrease to obtain a step width for decreasing the overload coefficient. The step width calculation formula for decrease is Kmin = A*(Ic / Ip)+B, where Kmin is the step width for decreasing the overload coefficient, Ic is the effective value of the current phase current, Ip is the rated output current, and A and B are constants.

[0015] In one embodiment of the present disclosure, the step of performing a limit process on the updated overload coefficient to obtain an updated current overload coefficient includes: obtaining a lower limit value and an upper limit value of the overload coefficient; when the updated overload coefficient is smaller than the lower limit value of the overload coefficient, determining the lower limit value of the overload coefficient as the updated current overload coefficient; when the updated overload coefficient is larger than the upper limit value of the overload coefficient, determining the upper limit value of the overload coefficient as the updated current overload coefficient; When the updated overload coefficient is greater than or equal to the lower limit value of the overload coefficient and the updated overload coefficient is less than or equal to the upper limit value of the overload coefficient, determining the updated overload coefficient as the current overload coefficient that has been updated.

[0016] The motor controller includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the above motor overload protection method is realized.

[0017] The automobile includes a motor and the above motor controller.

[0018] The computer-readable storage medium stores a computer program that realizes the above motor overload protection method when executed by a processor.

[0019] Details of one or more embodiments of the present application are shown in the following drawings and description. Other features and advantages of the present application will become apparent from the specification, drawings, and claims.

Brief Description of the Drawings

[0020] To more clearly explain the technical means of the embodiments of the present disclosure, the drawings necessary for the description of the embodiments of the present disclosure are briefly described below. Obviously, the drawings described below are only some embodiments of the present disclosure. Those skilled in the art can obtain other drawings based on these drawings without creative labor.

[0021]

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DETAILED DESCRIPTION OF THE INVENTION

[0022] In the first type of means in the background art, when performing overload protection, only the temperature limit is considered without considering factors such as the current or power of the motor controller. Therefore, the motor drive system is likely to operate with high power for a long time, or operate in an operating situation where the current is unstable or the current increases due to abnormalities in other hardware, which may cause damage to the IGBT module or other modules inside the motor controller. In the second type of means, when performing overload protection, only power is considered. Therefore, in the acceleration or rotation stage of the vehicle, due to the drastic change in the rotation speed, deviation occurs in the power calculation, resulting in misjudgment, triggering overload protection and causing power interruption, which poses a great risk to driving safety and ultimately threatens the driver's life.

[0023] Hereinafter, with reference to the drawings in the embodiments of the present disclosure, the technical means in the embodiments of the present disclosure will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, not all of them. Based on the embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without creative labor shall fall within the protection scope of the present disclosure.

[0024] The motor overload protection method according to an embodiment of the present disclosure is applicable to a motor controller of an automobile, and performs overload protection based on the actual current collected during the operation process of the motor, so as to realize effective protection of the motor drive system, not only avoid damage to internal devices of the motor controller, but also effectively prevent triggering overload protection due to misjudgment of overload and affecting the normal driving of the automobile.

[0025] Taking the application to a motor controller as an example, the motor overload protection method according to an embodiment will be described as follows with reference to FIG. 1. Step S101 of collecting the effective value of the current phase current of the motor; Step S102 of integrating the effective value of the current phase current over time to obtain a first integration value; Step S103 of obtaining a first threshold value; Step S104 of performing overload detection based on the first threshold value and the first integration value; When overload exists, determining the target limit current of the operation of the above motor, and step S105 of controlling the operation of the motor based on the target limit current.

[0026] The effective value of the current phase current is the effective value of the phase current collected and calculated in real time.

[0027] As an example, in step S101, the motor controller may collect three motor three-phase currents corresponding to the motor in real time, calculate the average value of the three motor three-phase currents, and obtain the effective value of the current phase current. The three-phase motor current is a current that flows through three conductors, and each conductor is used as the other two circuits, and the phase difference of the three components is made 1 / 3 of the period or the phase angle is 120° in sequence. The motor controller may collect the peak value of the motor current in real time and calculate and determine the effective value of the current phase current based on the peak value of the motor current. For example, divide the peak value of the motor current by

Number

[0028] As an example, in step S102, after the motor controller obtains the effective value of the current phase current corresponding to the current time of the system, it may integrate the effective values of all the current phase currents in a specific time range before the current time of the system over time to obtain a first integration value. The first integration value is the current time integration value calculated in real time at the current time of the system. For example, when the current time of the system is T1 and the specific time range is ΔT, the effective values of all the current phase currents collected within the specific time range [T1 - ΔT, T1] are integrated over time for processing, and the first integration value is calculated in real time. The first integration value can effectively reflect the degree of overload of the motor within a specific time range.

[0029] The first threshold value is a threshold value set in advance for evaluating whether a preset value that meets the overload determination condition is reached.

[0030] As an example, in step S103, after the motor controller obtains the first integration value, based on the effective value of the current phase current, it looks up the current time integration threshold table, and obtains a second threshold value that matches the effective value of the current phase current from the current time integration threshold table. The second threshold value may be directly determined as the first threshold value for overload detection, or according to the actual driving situation of the vehicle, the second threshold value may be corrected to obtain the first threshold value.

[0031] The current time integration threshold table is a data table stored in advance that reflects the correspondence between different output currents and specific threshold values. The second threshold value is directly determined by looking up the current time integration threshold table based on the effective value of the current phase current. The first threshold value is directly determined based on the second threshold value or determined after correction. As can be understood, since the current time integration threshold table is a data table stored in advance in the vehicle-mounted memory, based on the effective value of the current phase current, a table look-up operation can be performed to quickly determine the first threshold value.

[0032] As an example, in step S104, after the motor controller obtains the first integral value and the first threshold value, it calls an overload detection program formed based on the overload determination condition, uses the first integral value and the first threshold value as input parameters of the overload detection program, executes the overload detection program, determines whether the first integral value and the first threshold value satisfy the overload determination condition, and realizes overload detection based on the first integral value and the first threshold value. The overload determination condition is a preset determination condition for evaluating whether the motor is overloaded. The overload detection program is a computer program created based on the overload determination condition. The overload detection result is a detection result for detecting whether the first integral value and the first threshold value satisfy the overload determination condition. In this example, there are two types of overload detection results: the presence of overload and the absence of overload. Here, the presence of overload is a detection result indicating that there is an overload phenomenon in the motor, derived based on the first integral value and the first threshold value. Correspondingly, the absence of overload is a detection result indicating that there is no overload phenomenon in the motor, derived based on the first integral value and the first threshold value.

[0033] As can be understood, by looking up and calculating the current-time integral threshold value table determined by the bench test, the first threshold value can be determined quickly and accurately. The first threshold value is a value determined based on the overload capacity of the motor determined by the bench test. When using the first threshold value to perform overload detection on the first integral value, it helps to ensure the accuracy of overload detection, effectively prevent misjudgment of overload detection, and avoid the risk to operation safety caused by power cut-off due to misjudgment.

[0034] The target limit current is smaller than the effective value of the current phase current but is a current that can maintain the normal operation of the motor.

[0035] As an example, in step S105, when the overload detection result indicates that there is an overload, the motor controller needs to determine the target limit current for the operation of the motor and control the operation of the motor based on the target limit current. Since the target limit current is smaller than the effective value of the current in the current phase but can maintain the normal operation of the motor, the motor controller can control the motor to operate with reduced power based on the target limit current, achieving the purpose of overload protection. On the other hand, it can provide the current to maintain the normal rotation of the motor, enabling the vehicle to operate normally, avoiding power interruption of the vehicle or other abnormal operating conditions caused by the trigger of overload protection, and ensuring the safety of vehicle operation.

[0036] In this example, the motor controller needs to determine at least two overload protection cycles in the process of executing the overload protection policy. Each overload protection cycle corresponds to one target limit current, and the target limit currents corresponding to at least two overload protection cycles gradually decrease. By doing so, within each overload protection cycle, the motor is driven to operate based on the target limit current, and when there is an overload in the motor, its target limit current is gradually decreased, avoiding instantaneous power interruption of the vehicle or other abnormal operating conditions on the premise of realizing overload protection, further guaranteeing the safety of vehicle operation, and gradually decreasing its target limit current within at least two overload protection cycles to realize the reduction of the dead zone power of the motor during overload, which is helpful for improving the driving experience of the vehicle. The overload protection cycle is a cycle set in advance for realizing overload protection.

[0037] As an example, after step S104, that is, after the step of performing overload detection on the first integration value using the first threshold value to obtain the overload detection result, the motor overload protection method further includes a step of controlling the operation of the motor based on the effective value of the current in the current phase when the overload detection result indicates that there is no overload.

[0038] In this example, when the overload detection result indicates that there is no overload, the motor controller continues to control the operation of the motor based on the effective value of the current phase current, ensuring that the vehicle can run normally and preventing damage to the internal devices of the motor controller caused by overload.

[0039] In this embodiment, based on the effective value of the current phase current, a first integral value is quickly and accurately determined. The first integral value can accurately reflect the current overload level of the motor. Then, using a first threshold value to perform overload detection on the first integral value, it is possible to determine whether there is an overload from the current overload level of the motor, which helps to ensure the accuracy and determination efficiency of overload detection. When it is determined that there is an overload through overload detection, the motor controller needs to operate based on a target limit current to reduce the power and drive the operation of the motor. This can avoid damage to the device caused by overload, extend the service life of the motor controller, and at the same time provide a current to maintain the normal rotation of the motor, ensuring that the vehicle runs normally and guaranteeing driving safety.

[0040] In one embodiment, as shown in FIG. 2, step S103, that is, the step of obtaining the first threshold value, includes: step S201 of looking up a current-time integration threshold table based on the effective value of the current phase current to obtain a second threshold value; step S202 of obtaining the current current frequency and comparing the current current frequency with a current frequency threshold; step S203 of correcting the second threshold value based on a target correction coefficient to obtain the first threshold value when the current current frequency is smaller than the current frequency threshold; step S204 of determining the second threshold value as the first threshold value when the current current frequency is greater than or equal to the current frequency threshold.

[0041] As an example, in step S201, after the motor controller obtains the effective value of the current phase current, based on the effective value of the current phase current, it may look up a current-time integral threshold table, and obtain a second threshold that matches the effective value of the current phase current from the current-time integral threshold table. The second threshold is a current-time integral value directly determined by table lookup. When determined by table lookup, it helps to ensure the acquisition efficiency of the second threshold.

[0042] The current current frequency is the current frequency of the system at the current time, that is, the conversion frequency of the electromagnetic field of the system at the current time, that is, the number of conversions of the alternating current within 1 s. The current frequency threshold is a threshold set in advance for evaluating whether the current frequency meets the correction requirements. Generally, the current frequency threshold is a threshold related to the current frequency set in advance. Specifically, it is a threshold related to the current frequency when the motor is likely to be in a constrained state determined by tests in advance, so that it is easier to evaluate whether the motor is in a constrained state based on the current current frequency later.

[0043] As an example, in step S202, the motor controller obtains the current current frequency collected at the current time of the system, looks up the in-vehicle memory, obtains the pre-stored current frequency threshold, compares the current current frequency with the current frequency threshold, and determines whether it is necessary to correct the second threshold based on the comparison result.

[0044] The target correction coefficient is a correction coefficient set in advance.

[0045] As an example, in step S203, the motor controller compares the current current frequency with the current frequency threshold. When the current current frequency is smaller than the current frequency threshold, it indicates that the probability of the motor being in a constrained state is high. At this time, the load capacity of the motor is the maximum load capacity in the constrained state of the motor, which is much higher than the normal load capacity in the unconstrained state of the motor. Therefore, it is necessary to correct the second threshold, so as to avoid the situation that overload detection is performed based on the low second threshold and the maximum load capacity of the motor cannot be fully utilized.

[0046] In one embodiment, step S203, that is, the step of correcting the second threshold based on the target correction coefficient to obtain the first threshold, includes the step of processing the second threshold based on the target correction coefficient using a threshold correction formula to obtain the first threshold. The threshold correction formula is V1 = K * V2, where V1 is the first threshold, V2 is the second threshold, and K is the target correction coefficient, and K > 1.

[0047] In this example, the motor controller corrects the second threshold using a target correction coefficient greater than 1 set in advance, that is, determines the product of the second threshold and the target correction coefficient as the first threshold. Therefore, the first threshold is larger than the second threshold directly obtained by table lookup, and overload protection is performed by more fully utilizing the maximum load capacity of the motor, so that when the motor is in a constrained state, the overload capacity of the motor can be fully utilized.

[0048] As an example, in step S204, the motor controller compares the current current frequency with the current frequency threshold. When the current current frequency is greater than or equal to the current frequency threshold, it indicates that the probability of the motor being in a constrained state is low. At this time, the load capacity of the motor is the normal load capacity in the unconstrained state, and since there is no need to correct the second threshold, the second threshold can be directly determined as the first threshold.

[0049] In this embodiment, when the collected current frequency is smaller than the current frequency threshold, the second threshold is corrected using a target correction factor greater than 1 to obtain the first threshold, reducing the case where an overload is determined to exist, fully utilizing the overload capacity when the motor current frequency is low, realizing overload protection for the constrained situation where the current frequency is smaller than the current frequency threshold, and avoiding the risk of motor damage. When the collected current frequency is greater than or equal to the current frequency threshold, directly determining the second threshold as the first threshold helps improve the acquisition efficiency of the first threshold.

[0050] In one embodiment, before step S101, that is, before the step of looking up the current time integral threshold table based on the effective value of the current phase current to obtain the second threshold, the motor overload protection method is as follows: Step S001 of obtaining the test output current and the target operating time corresponding to the test output current; Step S002 of determining the rated parameter corresponding to the test output current based on a predetermined constant and the target operating time; Step S003 of obtaining the rated threshold corresponding to the test output current by time integrating the rated parameter; Step S004 of forming a current time integral threshold table based on the test output current, the target operating time, the rated parameter, and the rated threshold is further included.

[0051] As an example, in step S001, before the motor controller executes overload protection control, a bench test or a simulation test is performed in advance by hardware based on the vehicle's thermal management cooling means, and it is necessary to determine the test output current represented by Is for each bench test or simulation test. The test output current here is the output current determined in the bench test or simulation test process. For example, in the bench test or simulation test process, when the motor is in a normal operating state, the test output current = rated output current, that is, Is = Ip. The rated output current is the current when the motor operates at the rated power under the rated voltage and is represented by Ip. Also, for example, in the bench test or simulation test process, when the motor is in an overload recovery state, the test output current = rated output current - first change threshold, that is, Is = Ip - ΔI1. Here, the first change threshold ΔI1 is a threshold set in advance and applicable during overload recovery. Further, for example, in the bench test or simulation test process, when the motor is in an overload protection state, the test output current = rated output current + second change threshold, that is, Is = Ip + ΔI2. Here, the second change threshold ΔI2 is a threshold set in advance and applicable during overload protection.

[0052] In this example, after determining different test output currents, it is necessary to determine, through bench testing or simulation testing, the target operating time represented by T_Run corresponding to the above test output current based on the operating state of the motor in the bench testing or simulation testing process. For example, in the bench testing or simulation testing process, when the motor is in the overload recovery state, the target operating time corresponding to the above test output current is the operating time of the motor from the test output current to the rated output current. Also for example, in the bench testing or simulation testing process, when the motor is in the normal operating state or the overload recovery state, the target operating time corresponding to the above test output current is the operating time of the motor from the rated output current to the maximum overload current. The maximum overload current is the maximum current that the motor can bear. Specifically, a bench test can be performed on the hardware of the motor, and the maximum overload current represented by Imax can be calculated using hardware parameters such as the three-phase lines of the motor and the power module.

[0053] The predetermined constant is a preset constant and may be represented by, for example, K_OverCoef.

[0054] As an example, in step 002, after determining the target operating time corresponding to each test output current, the rated parameter corresponding to the test output current may be determined based on the predetermined constant K_OverCoef and the target operating time T_Run. Specifically, it includes calculating the division value of the predetermined constant K_OverCoef and the target operating time T_Run, setting the rated parameter corresponding to the test output current to 0 when the division value is 0 or less, and setting the division value as the rated parameter corresponding to the test output current when the division value is greater than 0.

[0055] As an example, in step S003, after determining the rated parameters corresponding to each test output current, a time integration process may be performed on the rated parameters corresponding to the test output current to determine the rated threshold corresponding to the test output current. The rated threshold may be understood as a threshold for evaluating whether the test output current reaches a value recognized as satisfying the overload determination condition.

[0056] As an example, in step S004, based on the test output current, the target operation time, and the rated parameters, a current-time integration threshold table is formed, and the current-time integration threshold table is encoded into the motor controller using software. In the process of the motor controller executing overload protection, by performing a table lookup based on the current-time integration threshold table, it is determined that the corresponding second threshold can be quickly obtained by looking up the current-time integration threshold table based on the effective value of the current phase current.

[0057] For example, the current-time integration threshold table is shown in Table 1. When the motor is in the overload recovery state, its test output current Is is smaller than the rated output current Ip, and its target operation time is a negative value. When the motor is in the normal operation state or the overload protection state, its test output current Is is greater than or equal to the rated output current Ip, and its target operation time is a positive value. The rated parameter Kp corresponding to the test output current Is is the rated output current Ip, and the rated threshold is the integral of the rated parameter Kp, which may be determined using an integral calculation formula.

Table 1

[0058] In one embodiment, as shown in FIG. 3, step S103 of obtaining the first threshold is step S301 of looking up the current-time integration threshold table based on the effective value of the current phase current to obtain the second threshold, and step S302 of obtaining the current motor rotation speed and comparing the current motor rotation speed with the overload rotation speed threshold. When the current motor rotation speed is less than the overload rotation speed threshold, obtain the overload integration gain threshold, and based on the second threshold and the overload integration gain threshold, obtain the first threshold in step S303; When the current motor rotation speed is less than or equal to the overload rotation speed threshold, determine the second threshold as the first threshold in step S304.

[0059] As an example, in step S301, after obtaining the effective value of the current phase current, the motor controller may look up the current-time integration threshold table based on the effective value of the current phase current, and obtain from the current-time integration threshold table a second threshold that matches the effective value of the current phase current. The second threshold is the current-time integration value directly determined by table lookup. Determining by table lookup helps to ensure the acquisition efficiency of the second threshold.

[0060] The current motor rotation speed is the motor rotation speed at the current time of the system. The overload rotation speed threshold is a preset rotation speed threshold for evaluating whether the motor rotation speed reaches the rotation speed recognized as being in a constrained state. Generally, the overload rotation speed threshold is a threshold determined based on the motor rotation speed of the motor in a constrained state determined by pre-tests, thereby making it easier to evaluate whether the motor is in a constrained state based on the current motor rotation speed later.

[0061] As an example, in step S302, the motor controller obtains the current motor rotation speed collected at the current time of the system, looks up the in-vehicle memory to obtain the preset overload rotation speed threshold, compares the current motor rotation speed with the overload rotation speed threshold, and based on the comparison result, determines whether to directly determine the second threshold as the first threshold.

[0062] The overload integration gain threshold is a preset threshold for the integration gain.

[0063] As an example, in step S303, the motor controller compares the current motor rotation speed with the overload rotation speed threshold. When the current motor rotation speed is lower than the overload rotation speed threshold, it indicates that the motor rotation speed is low and the probability of being in a constrained state is high. At this time, the load capacity of the motor is the maximum load capacity in the constrained state, which is much higher than the normal load capacity of the motor in the unconstrained state. If the second threshold obtained by table lookup from the current-time integral threshold table is directly determined as the first threshold, there may be a possibility that the maximum load capacity of the motor cannot be fully utilized when performing overload detection based on the low first threshold. Therefore, when the current motor rotation speed is lower than the overload rotation speed threshold, the motor controller looks up the in-vehicle memory, reads the second threshold and the overload integral gain threshold from the in-vehicle memory, and then determines the product of the second threshold and the overload integral gain threshold as the first threshold, so as to more fully utilize the maximum load capacity of the motor to perform overload protection, enabling the motor to operate at the maximum overload capacity when the motor is in a constrained state. As can be understood, the second threshold and the overload integral gain threshold are thresholds that can operate at the maximum load capacity of the motor, which are determined in advance by tests when the motor is likely to be in a constrained state.

[0064] As an example, in step S304, the motor controller compares the current motor rotation speed with the overload rotation speed threshold. When the current motor rotation speed is equal to or higher than the overload rotation speed threshold, it indicates that the motor rotation speed is high and the probability of the motor being in a constrained state is low. At this time, the load capacity of the motor is the normal load capacity in the unconstrained state. Based on the effective value of the current phase current, the current-time integral threshold table can be looked up, and a second threshold matching the effective value of the current phase current can be obtained from the current-time integral threshold table, and the second threshold can be directly determined as the first threshold without correction.

[0065] In this embodiment, when the current motor rotation speed is lower than the overload rotation speed threshold, by determining the first threshold based on the second threshold and the overload integral gain threshold, overload protection for a constraint situation where the current current frequency is lower than the current frequency threshold is realized, and overload protection can be performed by making more full use of the maximum load capacity of the motor. When the current motor rotation speed is lower than the overload rotation speed threshold, directly determining the second threshold as the first threshold helps improve the acquisition efficiency of the first threshold.

[0066] In one embodiment, as shown in FIG. 4, step S103, that is, the step of performing overload detection on the first integral value using the first threshold to obtain an overload detection result is step S401 of comparing the first integral value with the first threshold, and step S402 of determining that there is an overload when the first integral value is greater than the first threshold, and step S403 of determining that there is no overload when the first integral value is less than or equal to the first threshold.

[0067] As an example, in step S401, after obtaining the first integral value and the first threshold, the motor controller compares the first integral value with the first threshold to determine whether the overload determination condition is satisfied, and obtains an overload detection result.

[0068] As an example, in step S402, the motor controller compares the first integral value with the first threshold. When the first integral value is greater than the first threshold, it is determined that the motor load at the current time of the system is high and exceeds the operable normal load capacity of the motor controller, so it is determined that there is an overload.

[0069] As an example, in step S403, the motor controller compares the first integral value with the first threshold. When the first integral value is less than or equal to the first threshold, it is determined that the motor load at the current time of the system is low and does not reach the standard determined to satisfy the overload determination condition, that is, it is determined that it does not exceed the operable normal load capacity of the motor controller, so it is determined that there is no overload.

[0070] In this embodiment, by comparing the first integration value obtained through table look-up with a pre-stored first threshold value to determine whether the first integration value reaches a standard where it is recognized that the overload determination condition is satisfied, and by determining whether there is an overload, the overload detection process can be realized only through simple table look-up and comparison. The operation is simple and convenient, which is helpful for improving the processing efficiency.

[0071] In one embodiment, as shown in FIG. 5, step S105, that is, the step of determining the target limit current of the operation of the motor, includes step S501 of obtaining the current overload coefficient, and step S502 of using the current overload coefficient to limit the effective value of the current phase current to obtain the target limit current.

[0072] The current overload coefficient is a coefficient determined at the current time of the system for limiting the effective value of the current phase current.

[0073] As an example, in step S501, in order to ensure the acquisition efficiency of the current overload coefficient, the motor controller may obtain the current overload coefficient preset in the vehicle-mounted memory. Alternatively, in order to ensure the acquisition efficiency of the current overload coefficient, the motor controller may calculate and determine the current overload coefficient in real time according to the actual situation of the vehicle. For example, the current overload coefficient may be calculated and determined based on the effective value of the current phase current.

[0074] As an example, in step S502, when the motor controller determines that there is an overload, by using the current overload coefficient to limit the effective value of the current phase current, the obtained target limit current is smaller than the effective value of the current phase current. When controlling the operation of the motor based on the target limit current, overload protection can be realized.

[0075] In one embodiment, step S502, that is, the step of obtaining a target limiting current by limiting the effective value of the current phase current using the current overload factor, includes the step of calculating based on the current overload factor and the effective value of the current phase current using a limiting current calculation formula to obtain a target limiting current. The limiting current calculation formula is It = (Ic * Kco) / R, where It is the target limiting current, Ic is the effective value of the current phase current, Kco is the current overload factor, and R is a constant. In this example, the constant R may specifically be an overload factor upper limit value, for example, 1000.

[0076] In this example, in step S501, when the motor controller executes the overload protection policy, it may determine at least two overload protection periods, and obtain the effective value of the current phase current and the current overload factor corresponding to each overload protection period. The current overload factors corresponding to at least two overload protection periods gradually decrease. The fact that the current overload factors corresponding to at least two overload protection periods gradually decrease means that the current overload factor corresponding to the next overload protection period is smaller than the current overload factor corresponding to the previous overload protection period. The target limit current corresponding to each overload protection period may be the default operating current of the system, or may be the target limit current corresponding to the previous overload protection period. Therefore, the effective value of the current phase current corresponding to the next overload protection period is less than or equal to the effective value of the current phase current corresponding to the overload protection period. From the above, when the current overload factor corresponding to the next overload protection period is smaller than the current overload factor corresponding to the previous overload protection period, and the effective value of the current phase current corresponding to the next overload protection period is less than or equal to the effective value of the current phase current corresponding to the overload protection period, by determining that the target limit current corresponding to the previous overload protection period is smaller than the target limit current corresponding to the next overload protection period, it is possible to realize driving the operation of the motor based on the gradually decreasing target limit current corresponding to at least two overload protection periods. By gradually decreasing the target limit current within at least two overload protection periods, it is possible to avoid instantaneous interruption of the vehicle's power or other abnormal operating conditions under the premise of realizing overload protection, which is helpful for improving the driving experience of the vehicle.

[0077] In this embodiment, the motor controller may use the current overload factor to obtain the target limit current. Thereby, when driving the operation of the motor based on the target limit current, by realizing the linear smoothing process for the effective value of the current phase current, the power performance of the motor drive system can be maximally exerted. In some special operating conditions (such as the starting operation condition or the uphill driving condition), the motor controller can operate during overload, not only without damaging its internal devices, but also directly avoiding the risk to driving safety caused by power interruption.

[0078] In one embodiment, as shown in FIG. 6, after step S103, that is, after the step of performing overload detection based on the first threshold value and the first integral value, the motor overload protection method includes: step S601 of obtaining the current overload coefficient; if overload exists, obtaining the overload coefficient reduction step width, and for each overload protection period, using the overload coefficient reduction step width to reduce the current overload coefficient to obtain an updated overload coefficient in step S602; if no overload exists, obtaining the overload coefficient increase step width, and for each overload recovery period, using the overload coefficient increase step width to increase the current overload coefficient to obtain an updated overload coefficient in step S603; and step S604 of performing a limit process on the updated overload coefficient to obtain the updated current overload coefficient.

[0079] The current overload coefficient Kco is the overload coefficient determined at the current time of the system.

[0080] As an example, in step S601, in the in-vehicle memory corresponding to the motor controller, the current overload coefficient Kco updated in real time is stored. Therefore, when the overload detection result indicates that overload exists, the motor controller can use the current overload coefficient to limit the effective value of the current phase current to ensure the acquisition efficiency of the current overload coefficient.

[0081] The overload coefficient reduction step width is the step width for reducing the current overload coefficient. The overload protection period is a preset period for updating the current overload coefficient when overload exists, that is, it is necessary to update the current overload coefficient once for each overload protection period.

[0082] As an example, in step S602, when the overload detection result indicates that there is an overload, after obtaining the overload coefficient reduction step width Kmin, the current overload coefficient Kco may be decreased using the overload coefficient reduction step width Kmin every overload protection period T1 to obtain an updated overload coefficient Kco1. That is, every time the overload protection period T1 elapses, the difference between the current overload coefficient Kco and the overload coefficient reduction step width Kmin is determined as the updated overload coefficient Kco1, that is, Kco1 = Kco - Kmin. Thereby, when the overload detection result indicates that there is an overload, the overload coefficient is gradually decreased, and then, a smooth decrease in the target limit current is achieved, and when the overload detection result indicates that there is an overload, the risk to operation safety due to immediate power cut-off is avoided. In this example, when updating the current overload coefficient every overload protection period, based on the updated current overload coefficient, the target limit current corresponding to the corresponding overload protection period is updated, so that the target limit current is gradually decreased within at least two overload protection periods, realizing a stepwise decrease in the target limit current of the motor during overload, which is helpful for improving the driving experience of the vehicle.

[0083] In a specific embodiment, the overload coefficient reduction step width Kmin obtained by the motor controller may be a threshold value preset in the system, or a value calculated in real time based on the effective value of the current phase current. Thereby, the real-time performance of the overload coefficient reduction step width Kmin can be guaranteed, and the real-time performance and accuracy of the finally determined current overload coefficient can be ensured.

[0084] In one embodiment, step S602, that is, the step of obtaining the overload coefficient reduction step width, includes the step of processing the effective value of the current phase current using the reduction step width calculation formula to obtain the overload coefficient reduction step width Kmin. The above reduction step width calculation formula is Kmin = A * (Ic / Ip) + B, where Kmin is the overload coefficient reduction step width, Ic is the effective value of the current phase current, Ip is the rated output current, and A and B are constants. As can be understood, by calculating the overload coefficient reduction step width Kmin in real time based on the effective value of the current phase current, the real-time performance of the overload coefficient reduction step width Kmin can be guaranteed, and the real-time performance and accuracy of the finally determined current overload coefficient can be ensured.

[0085] As an example, in step S603, when the overload detection result is that there is no overload, after obtaining the overload coefficient increase step width Kadd, every overload recovery period T2, the current overload coefficient Kco is increased using the overload coefficient increase step width Kadd to obtain the updated overload coefficient Kco1. That is, every time the overload recovery period T2 elapses, the sum of the current overload coefficient Kco and the overload coefficient increase step width Kadd is determined as the updated overload coefficient Kco1, that is, Kco1 = Kco + Kadd. Thereby, when the overload detection result is that there is no overload, the overload coefficient is gradually increased to avoid a rapid increase in the current overload coefficient.

[0086] As an example, in step S604, the motor controller needs to perform a decrease process or an increase process on the current overload factor Kco to determine the updated overload factor Kco1, and then evaluate whether the updated overload factor Kco1 is within the range of a preset overload factor threshold. If the updated overload factor Kco1 is within the range of the overload factor threshold, the updated overload factor Kco1 can be directly determined as the updated current overload factor. If the updated overload factor Kco1 is not within the range of the overload factor threshold, based on the range of the overload factor threshold, the updated current overload factor is determined to ensure that the updated current overload factor is within the limit range. Then, when using the current overload factor to control the effective value of the current phase current, it is necessary to ensure that not only overload protection is realized, but also the risk of operation safety due to power cut-off in the overload protection process can be avoided.

[0087] In one embodiment, as shown in FIG. 7, step S604, that is, the step of performing a limit process on the updated overload factor to obtain the updated current overload factor, includes step S701 of obtaining the overload factor lower limit value and the overload factor upper limit value; step S702 of determining the overload factor lower limit value as the updated current overload factor when the updated overload factor is smaller than the overload factor lower limit value; step S703 of determining the overload factor upper limit value as the updated current overload factor when the updated overload factor is larger than the overload factor upper limit value; step S704 of determining the updated overload factor as the updated current overload factor when the updated overload factor is greater than or equal to the overload factor lower limit value and the updated overload factor is less than or equal to the overload factor upper limit value.

[0088] The lower limit value of the overload coefficient is the minimum value of the preset overload coefficient, and may be set to 0, for example. The upper limit value of the overload coefficient is the maximum value of the preset overload coefficient, and may be set to 1000, for example. The upper limit value of the overload coefficient can determine the current reduction value that decreases from the effective value of the current phase current to the target limit current in each overload protection cycle, and determine the threshold value of the current reduction range.

[0089] As an example, in step S701, the motor controller reads the in-vehicle memory to obtain the lower limit value and the upper limit value of the overload coefficient, and uses the lower limit value and the upper limit value of the overload coefficient to perform limit processing on the updated overload coefficient obtained in real time, ensuring that the currently obtained overload coefficient is within a reasonable range. Furthermore, when the effective value of the current phase current is limited using the current overload coefficient thereafter, not only can overload protection be realized, but it is ensured that it is possible to avoid the risk to driving safety caused by power interruption due to misjudgment in the overload protection process.

[0090] As an example, in step S702, the motor controller compares the updated overload coefficient with the lower limit value of the overload coefficient. If the updated overload coefficient is smaller than the lower limit value of the overload coefficient, it is determined that the updated overload coefficient is smaller than the allowable minimum value of the overload coefficient. At this time, the lower limit value of the overload coefficient can be determined as the updated current overload coefficient. To save the resources occupied during the process, step S602 is not executed, that is, for each overload recovery cycle, the process operation of increasing the current overload coefficient using the overload coefficient increase step width to obtain the updated overload coefficient is not executed.

[0091] As an example, in step S703, the motor controller compares the updated overload coefficient with the overload coefficient upper limit value. If the updated overload coefficient is greater than the overload coefficient upper limit value, it is determined that the updated overload coefficient is greater than the maximum allowable value of the overload coefficient. At this time, the overload coefficient upper limit value can be determined as the current overload coefficient that has been updated. In order to save the resources occupied during the processing, step S603 is not executed, that is, for each overload recovery cycle, the process operation of increasing the current overload coefficient using the overload coefficient increase step width to obtain the updated overload coefficient is not executed.

[0092] As an example, in step S704, the motor controller compares the updated overload coefficient with the overload coefficient lower limit value and the overload coefficient upper limit value. If the updated overload coefficient is between the overload coefficient lower limit value and the overload coefficient upper limit value, it is determined that the updated overload coefficient is within a preset reasonable range. Thereby, when directly determining the updated overload coefficient as the current overload coefficient that has been updated and then using the updated current overload coefficient to limit the effective value of the current phase current, it is ensured that not only overload protection is realized, but also the risk to operation safety caused by power interruption due to misjudgment in the overload protection process can be avoided. As can be understood, after determining the updated overload coefficient as the current overload coefficient that has been updated, it is still necessary to continue to execute step S602 or step S603 until the obtained updated overload coefficient reaches the overload coefficient upper limit value or the overload coefficient lower limit value.

[0093] In one embodiment, before step S101, that is, before the step of collecting the motor three-phase current, the motor overload protection method further includes detecting the current state of the IGBT module, and if the current state is in the on state, performing initialization settings and setting the overload coefficient upper limit value as the current overload coefficient.

[0094] The IGBT module is a power module set in the motor controller. The current state is a state for reflecting whether the IGBT module is turned on or not, and the current state includes the on state and the off state.

[0095] In this example, the motor controller detects the current state of the IGBT module in real time. When the current state is the on state, since initialization settings need to be performed and the overload coefficient upper limit value needs to be set as the current overload coefficient, when the IGBT module turns on, that is, when there is an overload, overload protection can be immediately performed. As can be understood, in the initialization setting process, the overload protection period and the overload recovery period are reset to avoid the information cached before the IGBT module turns on from affecting the accuracy of the overload protection control.

[0096] It should be understood that the magnitudes of the numbers of the steps in the above embodiments do not mean the order of execution before and after. The execution order of each process should be determined according to the functions and internal logics of the processes, and should not be construed as any limitation to the implementation process of the embodiments of the present disclosure.

[0097] As shown in FIG. 8, a motor controller according to an embodiment includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it realizes the motor overload protection method in the above embodiment, for example, S101 - S105 shown in FIG. 1, or the methods shown in FIGS. 2 - 7. To avoid duplication, the description is omitted here.

[0098] An automobile according to an embodiment includes a motor and the motor controller in the above embodiment. To avoid duplication, the description is omitted here.

[0099] A non - volatile computer - readable storage medium according to an embodiment stores a computer program that, when executed by a processor, realizes the motor overload protection method in the above embodiment, for example, S101 - S105 shown in FIG. 1 or the methods shown in FIGS. 2 - 7. To avoid duplication, the description is omitted here.

[0100] As can be understood by those skilled in the art, the realization of all or part of the flow in the method of the above embodiments can be completed by a computer program instructing related hardware, and the above computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it may include the flow of the embodiments of the above methods. Any reference to memory, storage, database or other media used in each embodiment according to the present disclosure may include non-volatile memory and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of example and not limitation, RAM is available in various forms such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct rambus dynamic RAM (DRDRAM) and Rambus dynamic RAM (RDRAM).

[0101] As will be clearly understood by those skilled in the art, for the sake of easy and concise description, examples have been given and described in terms of the division of the above functional units and modules. However, in actual applications, the above functions can be assigned as required and completed by different functional units and modules, that is, the internal structure of the above device can be divided into different functional units or modules to complete all or part of the functions described above.

[0102] The above embodiments are merely for explaining the technical means of the present disclosure and are not limiting. Although the present disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical means described in each of the foregoing embodiments or equivalently replace some of its technical features. These modifications or replacements do not deviate from the essence of the corresponding technical means from the spirit and scope of the technical means of each embodiment of the present disclosure and should all be included within the protection scope of the present disclosure.

Claims

1. A step of collecting the effective value of the current phase current of the motor; A step of obtaining a first integral value by time-integrating the effective value of the current phase current; A step of obtaining a first threshold value; A step of performing overload detection based on the first threshold value and the first integral value; When an overload exists, a step of determining a target limiting current for the operation of the motor and controlling the operation of the motor based on the target limiting current; including The step of obtaining the first threshold value is A step of looking up a current-time integration threshold table based on the effective value of the current phase current to obtain a second threshold value; A step of obtaining the current current frequency and comparing the current current frequency with a current frequency threshold; When the current current frequency is less than the current frequency threshold, a step of correcting the second threshold value based on a target correction coefficient to obtain the first threshold value; When the current current frequency is greater than or equal to the current frequency threshold, a step of determining the second threshold value as the first threshold value; including A motor overload protection method.

2. The step of correcting the second threshold value based on a target correction coefficient to obtain the first threshold value includes a step of processing the second threshold value based on the target correction coefficient using a threshold correction formula to obtain the first threshold value, The threshold correction formula is V1 = K * V2, where V1 is the first threshold value, V2 is the second threshold value, and K is the target correction coefficient. The motor overload protection method according to Claim 1.

3. A step of collecting the effective value of the current phase current of the motor; A step of obtaining a first integral value by time-integrating the effective value of the current phase current; A step of obtaining a first threshold value; A step of performing overload detection based on the first threshold value and the first integrated value; When overload exists, a step of determining a target limit current for the operation of the motor and controlling the operation of the motor based on the target limit current; including The step of obtaining the first threshold value includes a step of looking up a current-time integration threshold table based on the effective value of the current phase current to obtain a second threshold value; a step of obtaining the current motor rotation speed and comparing the current motor rotation speed with an overload rotation speed threshold value; When the current motor rotation speed is less than the overload rotation speed threshold value, a step of obtaining an overload integration gain threshold value and obtaining a first threshold value based on the second threshold value and the overload integration gain threshold value; When the current motor rotation speed is greater than or equal to the overload rotation speed threshold value, a step of determining the second threshold value as the first threshold value; including A motor overload protection method.

4. Before the step of looking up a current-time integration threshold table based on the effective value of the current phase current to obtain a second threshold value, a step of obtaining a test output current and a target operation time corresponding to the test output current; a step of determining a rated parameter corresponding to the test output current based on a predetermined constant and the target operation time; a step of time-integrating the rated parameter to obtain a rated threshold value corresponding to the test output current; a step of forming a current-time integration threshold table based on the test output current, the target operation time, the rated parameter, and the rated threshold value; further including The motor overload protection method according to claim 1 or 3.

5. The step of performing overload detection based on the first threshold value and the first integrated value A step of comparing the first integrated value with the first threshold value; If the first integrated value is greater than the first threshold value, a step of determining that an overload exists; If the first integrated value is less than or equal to the first threshold value, a step of determining that no overload exists; Including; The motor overload protection method according to claim 1 or 3.

6. The step of determining the target limiting current of the operation of the motor is: A step of obtaining the current overload factor; A step of using the current overload factor to limit the effective value of the current phase current to obtain a target limiting current; Including; The motor overload protection method according to claim 1 or 3.

7. The step of using the current overload factor to limit the effective value of the current phase current to obtain a target limiting current includes a step of calculating based on the current overload factor and the effective value of the current phase current using a limiting current calculation formula to obtain a target limiting current; The limiting current calculation formula is It = (Ic * Kco) / R, where It is the target limiting current, Ic is the effective value of the current phase current, Kco is the current overload factor, and R is a constant; The motor overload protection method according to claim 6.

8. After the step of performing overload detection based on the first threshold value and the first integrated value, A step of obtaining the current overload factor; If an overload exists, obtain an overload factor reduction step width, and for each overload protection period, use the overload factor reduction step width to reduce the current overload factor to obtain an updated overload factor; If no overload exists, obtain an overload factor increase step width, and for each overload recovery period, use the overload factor increase step width to increase the current overload factor to obtain an updated overload factor; Performing a limit process of comparing the updated overload factor with the overload factor lower limit value and / or the overload factor upper limit value to obtain the updated current overload factor; further comprising; The motor overload protection method according to claim 1 or 3.

9. The step of obtaining the overload factor decrease step width includes processing the effective value of the current phase current using a decrease step width calculation formula to obtain the overload factor decrease step width; The decrease step width calculation formula is Kmin = A * (Ic / Ip) + B, where Kmin is the overload factor decrease step width, Ic is the effective value of the current phase current, Ip is the rated output current, and A and B are constants; The motor overload protection method according to claim 8.

10. The step of performing a limit process of comparing the updated overload factor with the overload factor lower limit value and / or the overload factor upper limit value to obtain the updated current overload factor is: obtaining the overload factor lower limit value and the overload factor upper limit value; when the updated overload factor is smaller than the overload factor lower limit value, determining the overload factor lower limit value as the updated current overload factor; when the updated overload factor is larger than the overload factor upper limit value, determining the overload factor upper limit value as the updated current overload factor; when the updated overload factor is greater than or equal to the overload factor lower limit value and the updated overload factor is less than or equal to the overload factor upper limit value, determining the updated overload factor as the updated current overload factor; including; The motor overload protection method according to claim 8.

11. a memory; a processor; a computer program stored in the memory and executable on the processor; When the processor executes the computer program, it implements the motor overload protection method according to any one of claims 1 to 3. Motor controller. **Claim 12** A motor, The motor controller according to claim 11, comprising an automobile. **Claim 13** When executed by a processor, a computer program that implements the motor overload protection method according to any one of claims 1 to 3 is stored. Non-volatile computer-readable storage medium.

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