Electric motor overload protection method, electric motor controller, automobile and storage medium

Abstract

Disclosed are a motor overload protection method, a motor controller, a vehicle, and a storage medium. The method includes: acquiring a present phase current effective value of a motor (S101); performing time integration on the present phase current effective value, to obtain a first integral value (S102); obtaining a first threshold (S103); performing overload detection according to the first threshold and the first integral value (S104); and determining a target limiting current for operation of the motor if there is an overload and controlling the operation of the motor based on the target limiting current (S105).

Description

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

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This disclosure is based on the Chinese patent application with application number 202111152401.5 and application date September 29, 2021, and claims the priority of the Chinese patent application. The entire content of the Chinese patent application is hereby introduced into this disclosure as a reference. Technical Field

[0003] The present disclosure relates to a motor overload protection method, a motor controller, a vehicle, and a storage medium. Background Art

[0004] Current motor overload protection solutions for automotive motor drive systems generally include the following two approaches: The first detects whether the actual temperature of the motor drive system has reached the temperature limit to determine whether overload protection is necessary. The second monitors the power flowing to the motor and implements overload protection based on this power.

[0005] Public content

[0006] The present disclosure provides a motor overload protection method, a motor controller, a car, and a storage medium.

[0007] A motor overload protection method, comprising:

[0008] Collect the current effective value of the motor phase current;

[0009] Performing time integration on the current phase current effective value to obtain a first integral value;

[0010] Obtaining a first threshold;

[0011] performing overload detection according to the first threshold and the first integral value;

[0012] If there is an overload, a target limit current for the motor is determined, and the motor is controlled based on the target limit current.

[0013] According to one embodiment of the present disclosure, obtaining the first threshold includes:

[0014] According to the current phase current effective value, query the current time integral threshold value table to obtain the second threshold value;

[0015] Obtaining a current current frequency, and comparing the current current frequency with a current frequency threshold;

[0016] If the current current frequency is less than the current frequency threshold, correct the second threshold according to the target correction coefficient to obtain the first threshold;

[0017] If the current current frequency is greater than or equal to the current frequency threshold, the second threshold is determined as the first threshold.

[0018] According to one embodiment of the present disclosure, the step of correcting the second threshold according to the target correction coefficient to obtain the first threshold includes:

[0019] Using a threshold correction formula, processing the second threshold using the target correction coefficient to obtain the first threshold;

[0020] The threshold correction formula is V1=K*V2, V1 is the first threshold, V2 is the second threshold, and K is the target correction coefficient.

[0021] According to one embodiment of the present disclosure, obtaining the first threshold includes:

[0022] According to the current effective value of the phase current, a current time integral threshold value table is searched to obtain a second threshold value;

[0023] Obtaining a current motor speed, and comparing the current motor speed with an overload speed threshold;

[0024] If the current motor speed is less than the overload speed threshold, obtaining an overload integral gain threshold, and obtaining a first threshold according to the second threshold and the overload integral gain threshold;

[0025] If the current motor speed is less than or equal to the overload speed threshold, the second threshold is determined as the first threshold.

[0026] According to one embodiment of the present disclosure, before querying the current time integral threshold table according to the current phase current effective value to obtain the second threshold, the motor overload protection method further includes:

[0027] Obtaining a test output current and a target operating time corresponding to the test output current;

[0028] Determining a rated parameter corresponding to the test output current based on a preset constant and the target operating time;

[0029] Performing time integration on the rated parameter to obtain a rated threshold corresponding to the test output current;

[0030] A current-time integration threshold value table is formed based on the test output current, the target operating time, the rated parameters and the rated threshold value.

[0031] According to one embodiment of the present disclosure, performing overload detection according to the first threshold and the first integral value includes:

[0032] comparing the first integral value with a first threshold;

[0033] If the first integral value is greater than the first threshold, it is determined that an overload exists;

[0034] If the first integral value is less than or equal to the first threshold, it is determined that no overload exists.

[0035] According to one embodiment of the present disclosure, determining the target limiting current for the motor operation includes:

[0036] Get the current overload factor;

[0037] The current overload coefficient is used to limit the current effective value of the phase current to obtain a target limit current.

[0038] According to one embodiment of the present disclosure, the using the current overload coefficient to limit the current phase current effective value to obtain a target limiting current includes:

[0039] Using a current limiting current calculation formula, the current overload coefficient is calculated for the current phase current effective value to obtain a target current limiting current;

[0040] The limiting current calculation formula is It=(Ic*Kco) / R, where It is the target limiting current, Ic is the current phase current effective value, Kco is the current overload coefficient, and R is a constant.

[0041] According to one embodiment of the present disclosure, after performing overload detection according to the first threshold and the first integral value, the motor overload protection method further includes:

[0042] Get the current overload factor;

[0043] If there is an overload, obtain a decrement step length of the overload coefficient, and decrement the current overload coefficient using the decrement step length of the overload coefficient every overload protection period to obtain an updated overload coefficient;

[0044] If there is no overload, obtaining an overload coefficient increment step, and increasing the current overload coefficient by using the overload coefficient increment step every overload recovery period to obtain an updated overload coefficient;

[0045] The updated overload coefficient is subjected to a limit process to obtain an updated current overload coefficient.

[0046] According to one embodiment of the present disclosure, obtaining the overload coefficient decreasing step size includes:

[0047] Using a decreasing step calculation formula, the current phase current effective value is processed to obtain the decreasing step of the overload coefficient;

[0048] The calculation formula for the decrement step is Kmin=A*(Ic / Ip)+B, where Kmin is the decrement step of 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.

[0049] According to one embodiment of the present disclosure, performing limit processing on the updated overload coefficient to obtain the updated current overload coefficient includes:

[0050] Get the lower limit value and upper limit value of the overload coefficient;

[0051] If the updated overload coefficient is less than the overload coefficient lower limit, the overload coefficient lower limit is determined as the updated current overload coefficient;

[0052] If the updated overload coefficient is greater than the overload coefficient upper limit, the overload coefficient upper limit is determined as the updated current overload coefficient;

[0053] If the updated overload coefficient is greater than or equal to the overload coefficient lower limit value, and the updated overload coefficient is less than or equal to the overload coefficient upper limit value, the updated overload coefficient is determined as the updated current overload coefficient.

[0054] A 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 motor overload protection method is implemented.

[0055] A car comprises a motor and the motor controller.

[0056] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the motor overload protection method is implemented.

[0057] The details of one or more embodiments of the present application are set forth in the accompanying drawings and the description below. Other features and advantages of the present application will become apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the description of the embodiments of the present disclosure. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0059] FIG1 is a flow chart of a motor overload protection method according to an embodiment of the present disclosure.

[0060] FIG2 is another flow chart of a motor overload protection method according to an embodiment of the present disclosure.

[0061] FIG3 is another flow chart of a motor overload protection method according to an embodiment of the present disclosure.

[0062] FIG4 is another flow chart of a motor overload protection method according to an embodiment of the present disclosure.

[0063] FIG5 is another flow chart of a motor overload protection method according to an embodiment of the present disclosure.

[0064] FIG6 is another flow chart of a motor overload protection method according to an embodiment of the present disclosure.

[0065] FIG7 is another flow chart of a motor overload protection method according to an embodiment of the present disclosure.

[0066] FIG8 is a schematic diagram of a motor controller according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0067] The first solution in the background technology only considers temperature limits for overload protection, without considering factors such as the current or power of the motor controller. This can easily cause the motor drive system to operate at high power for a long time, or operate under high current conditions caused by current imbalance or other hardware anomalies, causing damage to the IGBT module or other modules inside the motor controller. The second solution only considers power for overload protection. During vehicle acceleration or speed phases, due to drastic speed fluctuations, it is easy for power calculations to deviate and misjudge, triggering overload protection and causing power interruption. This poses a significant driving safety risk and may even threaten the driver's life.

[0068] The following will clearly and completely describe the technical solutions in the embodiments of the present disclosure in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present disclosure without making any creative efforts shall fall within the scope of protection of the present disclosure.

[0069] The motor overload protection method provided in the embodiments of the present disclosure can be applied to the motor controller of an automobile. The motor overload protection method can be used to perform overload protection based on the actual current collected during the operation of the motor, so as to effectively protect the motor drive system. It can avoid damage to the internal components of the motor controller and effectively prevent misjudgment of overload and triggering of overload protection, which affects the normal driving of the automobile.

[0070] In one embodiment, as shown in FIG1 , a motor overload protection method is provided. The method is described by taking the application of the method to a motor controller as an example, and includes the following steps:

[0071] S101: Collect the current effective value of the motor phase current;

[0072] S102: Performing time integration on the current phase current effective value to obtain a first integral value;

[0073] S103: Obtain a first threshold;

[0074] S104: performing overload detection according to the first threshold and the first integral value;

[0075] S105: If there is an overload, determining a target limiting current for the motor, and controlling the motor operation based on the target limiting current.

[0076] The current phase current effective value refers to the phase current effective value collected and calculated in real time.

[0077] As an example, in step S101, the motor controller can collect the three-phase currents of the three motors corresponding to the motor in real time, and perform average calculation on the three-phase currents of the three motors to obtain the effective value of the current phase current. The three-phase current of the motor is a current that passes through three wires, with each wire serving as a loop for the other two wires, and the phase difference of the three components is one-third of a cycle or a 120° phase angle. The motor controller can also collect the peak value of the motor current in real time, and determine the effective value of the current phase current based on the peak value of the motor current, for example, dividing the peak value of the motor current by

[0078] As an example, in step S102, after obtaining the current phase current RMS value corresponding to the current system time, the motor controller may perform a time integration on all current phase current RMS values ​​within a specific time period prior to the current system time to obtain a first integral value. This first integral value is the current time integral value calculated in real time by the system at the current time. For example, if the current system time is T1 and the specific time period is ΔT, then all current phase current RMS values ​​collected within the specific time period [T1-ΔT, T1] are time-integrated to calculate the first integral value in real time. This first integral value can effectively reflect the degree of motor overload within the specific time period.

[0079] The first threshold is a preset threshold used to evaluate whether the threshold is reached to determine whether the overload determination condition is met.

[0080] As an example, in step S103, after obtaining the first integral value, the motor controller can query the current time integral threshold table based on the current phase current effective value, and obtain a second threshold that matches the current phase current effective value from the current time integral threshold table. The second threshold can be directly determined as the first threshold for overload detection; or the second threshold can be corrected according to the actual driving conditions of the vehicle to obtain the first threshold.

[0081] The current-time-integration threshold table is a pre-stored data table that reflects the correspondence between different output currents and specific thresholds. The second threshold is directly determined by querying the current-time-integration threshold table based on the current phase current RMS value. The first threshold is determined directly from the second threshold or after correction. As can be understood, since the current-time-integration threshold table is a pre-stored data table in the vehicle's memory, the first threshold can be quickly determined by querying the table based on the current phase current RMS value.

[0082] As an example, in step S104, after obtaining the first integral value and the first threshold value, the motor controller 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, and determines whether the first integral value and the first threshold value meet the overload determination condition, so as to implement overload detection based on the first threshold value and the first integral value. The overload determination condition is a pre-set determination condition for evaluating whether the motor is overloaded. The overload detection program is a computer program edited 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 meet the overload determination condition. In this example, the overload detection result includes two types: the presence of overload and the absence of overload. The presence of overload here refers to the detection result that the motor is overloaded based on the first integral value and the first threshold value; correspondingly, the absence of overload refers to the detection result that the motor is not overloaded based on the first integral value and the first threshold value.

[0083] It can be understood that by querying and calculating the current-time integral threshold table determined by the bench test, the first threshold can be determined quickly and accurately. The first threshold is a value determined based on the overload capacity of the motor determined by the bench test. Using the first threshold to perform overload detection on the first integral value helps to ensure the accuracy of overload detection and can effectively prevent misjudgment of overload detection, thereby avoiding driving safety risks caused by power interruption due to misjudgment.

[0084] The target limiting current is a current that is smaller than the effective value of the current phase current but can maintain normal operation of the motor.

[0085] As an example, in step S105, when the overload detection result is that there is an overload, the motor controller needs to determine the target limiting current of the motor operation, and control the motor operation based on the target limiting current. Since the target limiting current is smaller than the effective value of the current phase current but can maintain the normal operation of the motor, the motor controller can control the motor to reduce power based on the target limiting current. On the one hand, it can achieve the purpose of overload protection, and on the other hand, it can provide current to maintain normal rotation of the motor, so that the car can operate normally, avoiding vehicle power interruption or other abnormal operating conditions when the overload protection is triggered, thereby ensuring vehicle driving safety.

[0086] In this example, when executing the overload protection strategy, the motor controller must determine at least two overload protection cycles. Each overload protection cycle corresponds to a target current limit, and the target current limit corresponding to at least two overload protection cycles is gradually reduced. This allows the motor to operate based on the target current limit within each overload protection cycle. This allows the target current limit to be gradually reduced when the motor is overloaded. This prevents momentary power interruptions or other abnormal operating conditions while ensuring overload protection, thereby ensuring vehicle driving safety. Furthermore, by gradually reducing the target current limit within at least two overload protection cycles, power consumption is reduced without sensing when the motor is overloaded, helping to improve the vehicle driving experience. The overload protection cycle is a pre-set period for implementing overload protection.

[0087] As an example, after step S104, that is, after using the first threshold to perform overload detection on the first integral value and obtaining the overload detection result, the motor overload protection method also includes: if the overload detection result is that there is no overload, controlling the motor operation based on the current phase current effective value.

[0088] In this example, when the overload detection result shows that there is no overload, the motor controller can continue to control the motor operation based on the current phase current effective value to ensure the normal operation of the vehicle and prevent damage to the internal components of the motor controller due to overload.

[0089] In this embodiment, a first integral value is quickly and accurately determined based on the current phase current RMS value. This first integral value accurately reflects the current overload level of the motor. An overload detection is then performed on the first integral value using a first threshold value to determine whether an overload exists based on the current overload level of the motor, thereby ensuring the accuracy and efficiency of overload detection. When overload detection determines an overload exists, the motor controller operates according to a target current limit to reduce the power required to drive the motor. This prevents component damage caused by overload and extends the life of the motor controller. Furthermore, it provides current sufficient to maintain normal motor rotation, enabling normal vehicle operation and ensuring driving safety.

[0090] In one embodiment, as shown in FIG2 , step S103, i.e., obtaining a first threshold, includes:

[0091] S201: Query the current time integral threshold table according to the current phase current effective value to obtain a second threshold;

[0092] S202: Obtain the current current frequency and compare the current current frequency with the current frequency threshold;

[0093] S203: If the current current frequency is less than the current frequency threshold, correct the second threshold according to the target correction coefficient to obtain the first threshold;

[0094] S204: If the current frequency is greater than or equal to the current frequency threshold, the second threshold is determined as the first threshold.

[0095] As an example, in step S201, after obtaining the effective value of the current phase current, the motor controller can query the current time integral threshold table based on the current phase current effective value, and obtain a second threshold that matches the current phase current effective value from the current time integral threshold table. The second threshold is a current time integral value directly determined by looking up the table. Determining it by looking up the table helps to ensure the efficiency of obtaining the second threshold.

[0096] The current current frequency refers to the system's current frequency at the current moment, i.e., the system's electromagnetic field conversion frequency at the current moment, or the number of alternating current changes within 1 second. The current frequency threshold is a pre-set threshold used to assess whether the current frequency meets the correction requirements. Generally speaking, this current frequency threshold is based on a pre-set threshold related to current frequency, specifically a threshold related to current frequency determined during preliminary testing when the motor is prone to stalling, allowing for subsequent assessment of whether the motor is in a stalled condition based on the current current frequency.

[0097] As an example, in step S202, the motor controller may obtain the current current frequency collected by the system at the current moment, query the on-board memory to obtain the pre-stored current frequency threshold, and compare the current current frequency with the current frequency threshold to determine whether the second threshold needs to be corrected based on the comparison result.

[0098] The target correction coefficient is a preset correction coefficient.

[0099] 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 less than the current frequency threshold, it indicates that the motor is likely to be in a stalled condition. At this time, the motor's load capacity is its maximum load capacity under a stalled condition, which is much higher than the motor's normal load capacity under a non-stalled condition. The second threshold needs to be corrected to avoid overload detection based on a lower second threshold, which cannot fully utilize the motor's maximum load capacity.

[0100] In one embodiment, step S203, i.e., correcting the second threshold according to the target correction coefficient to obtain the first threshold, includes: using a threshold correction formula to process the second threshold with the target correction coefficient to obtain the first threshold; the threshold correction formula is V1=K*V2, V1 is the first threshold, V2 is the second threshold, K is the target correction coefficient, and K>1.

[0101] In this example, the motor controller can use a pre-set target correction coefficient greater than 1 to correct the second threshold, that is, the product of the second threshold and the target correction coefficient is determined as the first threshold, so that the first threshold is larger than the second threshold obtained by directly looking up the table, and the maximum load capacity of the motor can be more fully utilized for overload protection, so that the motor can fully utilize the overload capacity of the motor under stall conditions.

[0102] 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 stalled condition is small. At this time, the motor's carrying capacity is the normal carrying capacity under non-stalled conditions, and there is no need to correct the second threshold. Therefore, the second threshold can be directly determined as the first threshold.

[0103] In this embodiment, when the current current frequency collected is less than the current frequency threshold, the second threshold is corrected using a target correction factor greater than 1 to obtain the first threshold. This reduces the likelihood of overload being identified, fully utilizing the motor's overload capacity at lower current frequencies, and simultaneously providing overload protection for stalled rotor conditions where the current current frequency is less than the current frequency threshold, thereby avoiding the risk of motor damage. When the current current frequency collected is greater than or equal to the current frequency threshold, the second threshold is directly determined as the first threshold, which helps improve the efficiency of obtaining the first threshold.

[0104] In one embodiment, before step S101, that is, before querying the current time integral threshold table according to the current phase current effective value to obtain the second threshold, the motor overload protection method further includes the following steps:

[0105] S001: Obtaining a test output current and a target operating time corresponding to the test output current;

[0106] S002: Determine a rated parameter corresponding to the test output current based on a preset constant and the target operating time;

[0107] S003: Performing time integration on the rated parameter to obtain a rated threshold corresponding to the test output current;

[0108] S004: forming a current-time integral threshold table based on the test output current, the target operating time, the rated parameters and the rated threshold.

[0109] As an example, in step S001, before the motor controller executes the overload protection control, the hardware needs to perform bench testing or simulation testing in accordance with the vehicle's thermal management cooling plan in advance, and the test output current for each bench test or simulation test needs to be determined first, which can be represented by Is. The test output current here refers to the output current determined during the bench test or simulation test. For example, during the bench test or simulation test, if the motor is in a normal working state, its test output current = rated output current, that is, Is = Ip. The rated output current refers to the current when the motor works at rated power under rated voltage, and can be represented by Ip. For another example, during the bench test or simulation test, if the motor is in an overload recovery state, its test output current = rated output current - first change threshold, that is, Is = Ip - ΔI1, where the first change threshold ΔI1 is a pre-set threshold that can be applied during the overload recovery process. For another example, during a bench test or simulation test, if the motor is in an overload protection state, its test output current = rated output current + second change threshold, that is, Is = Ip + ΔI2, where the second change threshold ΔI2 is a pre-set threshold that can be applied during the overload protection process.

[0110] In this example, after determining the different test output currents, it is necessary to determine the target working time corresponding to the test output current through bench testing or simulation testing according to the working state of the motor during the bench test or simulation test, which can be represented by T_Run. For example, during the bench test or simulation test, if the motor is in an overload recovery state, the target working time corresponding to the test output current is the running time of the motor from the test output current to the rated output current. For another example, during the bench test or simulation test, if the motor is in a normal working state or an overload recovery state, the target working time corresponding to the test output current is the running time of the motor from the rated output current to the maximum overload current. The maximum overload current refers to the maximum current that the motor can carry. Specifically, the maximum overload current can be calculated by performing a bench test on the motor hardware and using hardware parameters such as the motor's three-phase line and power module. It can be represented by Imax.

[0111] The preset constant is a preset constant, and may be represented by K_OverCoef, for example.

[0112] As an example, in step 002, after determining the target operating time corresponding to each test output current, the rated parameters corresponding to the test output current can be determined based on the preset constant K_OverCoef and the target operating time T_Run, specifically including: calculating the quotient of the preset constant K_OverCoef and the target operating time T_Run; if the quotient is less than or equal to 0, setting the rated parameters corresponding to the test output current to 0; if the quotient is greater than 0, determining the quotient as the rated parameters corresponding to the test output current.

[0113] As an example, in step S003, after determining the rated parameters corresponding to each test output current, the rated parameters corresponding to the test output current can be time-integrated to determine the rated threshold corresponding to the test output current. The rated threshold can be understood as a threshold used to evaluate whether the test output current reaches the threshold for determining whether the overload judgment condition is met.

[0114] As an example, in step S004, a current time integration threshold table can be formed based on the test output current, the target working time and the rated parameters, and the current time integration threshold table can be encoded into the motor controller using software, so that when the motor controller performs overload protection, it can look up the current time integration threshold table to determine its corresponding second threshold value, so as to determine that the current time integration threshold table can be queried according to the current phase current effective value to quickly obtain the second threshold value.

[0115] For example, the current-time integral threshold table is shown in Table 1. When the motor is in the overload recovery state, its test output current Is is less than the rated output current Ip, and its target operating time is a negative value; when the motor is in the normal working state or overload protection state, its test output current Is is equal to or greater than the rated output current Ip, and its target operating time is a positive value; the rated parameter Kp corresponding to the test output current Is is the rated output current Ip; the rated threshold is the integral of the rated parameter Kp, which can be determined using the integral calculation formula.

[0116] Table 1 Current time integral threshold table

[0117] Test output current Is Target operating time T_Run Rated parameter Kp Rated threshold Ip - ΔI1 - T_Run1 Kp1 = K_OverCoef / - T_Run1 Integral of Kp1 Ip T_Run2 Kp2 = K_OverCoef / T_Run2 Integral of Kp2 Ip + ΔI2 T_Run3 Kp3 = K_OverCoef / T_Run3 Integral of Kp3 ... ... Imax T_Runx Kpx = K_OverCoef / T_Runx Kpx Integral

[0118] In one embodiment, as shown in FIG3 , in step S103 , obtaining a first threshold includes:

[0119] S301: Query the current time integral threshold table according to the current phase current effective value to obtain a second threshold;

[0120] S302: Obtain the current motor speed and compare the current motor speed with the overload speed threshold;

[0121] S303: If the current motor speed is less than the overload speed threshold, obtain the overload integral gain threshold, and obtain the first threshold based on the second threshold and the overload integral gain threshold;

[0122] S304: If the current motor speed is less than or equal to the overload speed threshold, the second threshold is determined to be the first threshold.

[0123] As an example, in step S301, after obtaining the effective value of the current phase current, the motor controller can query the current time integral threshold table based on the current phase current effective value, and obtain a second threshold that matches the current phase current effective value from the current time integral threshold table. The second threshold is a current time integral value directly determined by looking up the table. Determining it by looking up the table helps to ensure the efficiency of obtaining the second threshold.

[0124] The current motor speed refers to the system's current motor speed. The overload speed threshold is a pre-set speed threshold used to assess whether the motor speed has reached a stalled condition. Generally, this overload speed threshold is determined based on pre-tested motor speeds that indicate a stalled condition, allowing for subsequent assessments of whether the motor is in a stalled condition based on the current motor speed.

[0125] As an example, in step S302, the motor controller can obtain the current motor speed collected by the system at the current moment, and query the on-board memory to obtain the pre-stored overload speed threshold, and compare the current motor speed with the overload speed threshold to determine whether the second threshold can be directly determined as the first threshold based on the comparison result.

[0126] The overload integral gain threshold is a preset integral gain threshold.

[0127] As an example, in step S303, the motor controller compares the current motor speed with the overload speed threshold. If the current motor speed is less than the overload speed threshold, it indicates that the motor speed is low and the probability of being in a stalled condition is high. At this time, the motor load capacity is the maximum load capacity under the stalled condition, which is much higher than the normal load capacity of the motor under non-stalled conditions. If the second threshold value obtained by looking up the current time integral threshold table is directly determined as the first threshold value, it may result in subsequent overload detection based on the lower first threshold value, failing to fully utilize the maximum load capacity of the motor. Therefore, when the current motor speed is less than the overload speed threshold, the motor controller can query the onboard memory, read the second threshold value and the overload integral gain threshold value from the onboard memory, and then determine the first threshold value based on the product of the second threshold value and the overload integral gain threshold value. This can more fully utilize the maximum load capacity of the motor for overload protection, so that the motor can operate at the maximum load capacity of the motor under stalled conditions. It can be understood that the second threshold value and the overload integral gain threshold value are threshold values ​​determined based on pre-testing the motor under conditions prone to stalling, which can be used to determine the maximum load capacity of the motor.

[0128] As an example, in step S304, the motor controller compares the current motor speed with the overload speed threshold. If the current motor speed is greater than or equal to the overload speed threshold, it means that the motor speed is relatively high and the probability of being in a stalled condition is relatively low. At this time, the motor load capacity is the normal load capacity under a non-stalled condition. The current time integral threshold table can be queried based on the current phase current effective value, and a second threshold matching the current phase current effective value can be obtained from the current time integral threshold table. There is no need to correct the second threshold, and the second threshold can be directly determined as the first threshold.

[0129] In this embodiment, when the current motor speed is less than the overload speed threshold, the first threshold is determined based on the second threshold and the overload integral gain threshold. This provides overload protection for stalled rotor conditions where the current current frequency is less than the current frequency threshold. This allows for more efficient overload protection by fully utilizing the motor's maximum load capacity. When the current motor speed is less than the overload speed threshold, the second threshold is directly determined as the first threshold, which helps improve the efficiency of obtaining the first threshold.

[0130] In one embodiment, as shown in FIG4 , step S103 , i.e., performing overload detection on the first integral value using the first threshold value to obtain an overload detection result, includes:

[0131] S401: Compare the first integral value with a first threshold;

[0132] S402: If the first integral value is greater than the first threshold, it is determined that an overload exists;

[0133] S403: If the first integral value is less than or equal to the first threshold, it is determined that there is no overload.

[0134] As an example, in step S401 , after obtaining the front current time 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 met, and obtains the overload detection result.

[0135] 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 of the system is high at the current moment and exceeds the normal load-bearing capacity of the motor controller. Therefore, it is determined that there is an overload.

[0136] As an example, in step S403, the motor controller compares the first integral value with the first threshold value. When the first integral value is less than or equal to the first threshold value, it is determined that the motor load of the system at the current moment is low and does not meet the standard for satisfying the overload judgment condition, that is, it does not exceed the normal load-bearing capacity that the motor controller can operate. Therefore, it is determined that there is no overload.

[0137] In this embodiment, the first integral value obtained by table lookup is compared with a pre-stored first threshold value to determine whether the first integral value reaches the overload determination condition and whether there is an overload, so that the overload detection process can be implemented only through simple table lookup and comparison, which is simple and convenient to operate and helps to improve processing efficiency.

[0138] In one embodiment, as shown in FIG5 , step S105 , i.e., determining a target limiting current for the motor operation, includes:

[0139] S501: Obtain the current overload coefficient;

[0140] S502: Using the current overload coefficient to limit the current effective value of the phase current, and obtaining a target limit current.

[0141] The current overload coefficient is a coefficient determined by the system at the current moment and used to limit the effective value of the current phase current.

[0142] As an example, in step S501, the motor controller may obtain a current overload factor preset in the vehicle's memory to ensure efficient acquisition of the current overload factor. Alternatively, the motor controller may calculate and determine the current overload factor in real time based on the actual vehicle conditions, for example, by calculating and determining the current overload factor based on the current phase current effective value, to ensure efficient acquisition of the current overload factor.

[0143] As an example, in step S502, when the motor controller determines that there is an overload, it needs to use the current overload coefficient to limit the effective value of the current phase current so that the obtained target limiting current is less than the effective value of the current phase current, so that overload protection can be achieved when the motor is controlled to operate based on the target limiting current.

[0144] In one embodiment, step S502, i.e., limiting the current phase current effective value using the current overload coefficient to obtain a target current limit, includes: calculating the current phase current effective value using the current overload coefficient using a current limit calculation formula to obtain the target current limit; the current limit calculation formula is It = (Ic*Kco) / R, where It is the target current limit, Ic is the current phase current effective value, Kco is the current overload coefficient, and R is a constant. In this example, the constant R can specifically be an upper limit value of the overload coefficient, such as 1000.

[0145] In this example, in step S501, when executing the overload protection strategy, the motor controller can determine at least two overload protection cycles, obtain the current phase current effective value and the current overload coefficient corresponding to each overload protection cycle, and the current overload coefficient corresponding to at least two overload protection cycles gradually decreases. Among them, the current overload coefficient corresponding to at least two overload protection cycles gradually decreases, which means that the current overload coefficient corresponding to the next overload protection cycle is less than the current overload coefficient corresponding to the previous overload protection cycle. The target working time corresponding to each overload protection cycle can be the system default working current, or it can be the target limiting current corresponding to the previous overload protection cycle. It can be seen that the current phase current effective value corresponding to the next overload protection cycle is less than or equal to the current phase current effective value corresponding to the overload protection cycle. In summary, if the current overload coefficient corresponding to the next overload protection cycle is smaller than the current overload coefficient corresponding to the previous overload protection cycle, and the current phase current effective value corresponding to the next overload protection cycle is smaller than or equal to the current phase current effective value corresponding to the overload protection cycle, it can be determined that the target limiting current corresponding to the previous overload protection cycle is smaller than the target limiting current corresponding to the next overload protection cycle, so as to realize the operation of the motor based on the gradually decreasing target limiting current corresponding to at least two overload protection cycles, and gradually reduce its target limiting current within at least two overload protection cycles. On the premise of achieving overload protection, it can also avoid instantaneous power interruption or other abnormal working conditions of the vehicle, which helps to improve the vehicle driving experience.

[0146] In this embodiment, the motor controller can use the current overload coefficient to obtain the target limiting current, so that when the motor is driven to work according to the target limiting current, the current phase current effective value can be linearly smoothed, and the power performance of the motor drive system can be maximized, so that in some special working conditions (such as starting conditions or driving conditions on slopes), the motor controller can operate under overload conditions, which will not damage its internal components and can also avoid driving safety risks caused by direct power interruption.

[0147] In one embodiment, as shown in FIG6 , after step S103 , that is, after overload detection is performed according to the first threshold and the first integral value, the motor overload protection method further includes:

[0148] S601: Obtain the current overload coefficient;

[0149] S602: If an overload exists, obtain a decrement step length of the overload coefficient, and decrement the current overload coefficient using the decrement step length every overload protection period to obtain an updated overload coefficient.

[0150] S603: If there is no overload, obtain an overload coefficient increment step, and increment the current overload coefficient using the overload coefficient increment step every overload recovery period to obtain an updated overload coefficient;

[0151] S604: Perform limit processing on the updated overload coefficient to obtain the updated current overload coefficient.

[0152] The current overload coefficient Kco refers to the overload coefficient determined by the system at the current moment.

[0153] As an example, in step S601, the current overload coefficient Kco updated in real time is stored in the on-board memory corresponding to the motor controller, so that when the overload detection result of the motor controller is overloaded, the current overload coefficient can be used to limit the effective value of the current phase current to ensure the efficiency of obtaining the current overload coefficient.

[0154] The overload coefficient decrement step is the step used to decrement the current overload coefficient. The overload protection period is a preset period used to update the current overload coefficient when an overload occurs. That is, the current overload coefficient needs to be updated every other overload protection period.

[0155] As an example, in step S602, when the overload detection result is that there is an overload, the overload coefficient decreasing step Kmin can be obtained first, and the current overload coefficient Kco is decreased by the overload coefficient decreasing step Kmin every overload protection period T1 to obtain the updated overload coefficient Kco1, that is, every overload protection period T1, the difference between the current overload coefficient Kco and the overload coefficient decreasing step Kmin is determined as the updated overload coefficient Kco1, that is, Kco1 = Kco-Kmin, so as to gradually reduce the overload coefficient when the overload detection result is that there is an overload, so as to subsequently achieve a smooth reduction in the target limiting current, and avoid driving safety risks caused by immediate power interruption when the overload detection result is that there is an overload. In this example, when a current overload coefficient is updated in each overload protection cycle, the target limit current corresponding to the corresponding overload protection cycle can be updated based on the updated current overload coefficient, so as to gradually reduce its target limit current within at least two overload protection cycles, so as to achieve a step-by-step reduction in the target limit current when the motor is overloaded, which helps to improve the vehicle driving experience.

[0156] In a specific embodiment, the motor controller obtains the overload coefficient reduction step Kmin, which can be a threshold preset by the system, or a value calculated in real time based on the current effective value of the phase current, which can ensure the real-time performance of the overload coefficient reduction step Kmin and ensure the real-time and accuracy of the final determined current overload coefficient.

[0157] In one embodiment, step S602, i.e., obtaining the overload coefficient decreasing step size, includes: using a decreasing step size calculation formula to process the current phase current effective value to obtain the overload coefficient decreasing step size Kmin. The decreasing step size calculation formula is Kmin = A*(Ic / Ip) + B, where Kmin is the overload coefficient decreasing step size, Ic is the current phase current effective value, Ip is the rated output current, and A and B are constants. It can be understood that by calculating the overload coefficient decreasing step size Kmin in real time based on the current phase current effective value, the real-time performance of the overload coefficient decreasing step size Kmin can be guaranteed, thereby ensuring the real-time performance and accuracy of the final determined current overload coefficient.

[0158] As an example, in step S603, when the overload detection result is that there is no overload, the overload coefficient increasing step Kadd can be obtained first, and the current overload coefficient Kco is increased by the overload coefficient increasing step Kadd every overload recovery period T2 to obtain the updated overload coefficient Kco1, that is, every overload recovery period T2, the sum of the current overload coefficient Kco and the overload coefficient increasing step Kadd is determined as the updated overload coefficient Kco1, that is, Kco1 = Kco + Kadd, so as to achieve the goal of gradually increasing the overload coefficient when the overload detection result is that there is no overload, so as to avoid the current overload coefficient from increasing rapidly.

[0159] As an example, in step S604, after the motor controller decreases or increases the current overload coefficient Kco and determines its updated overload coefficient Kco1, it needs to evaluate whether the updated overload coefficient Kco1 is within a preset overload coefficient threshold range; if the updated overload coefficient Kco1 is within the overload coefficient threshold range, the updated overload coefficient Kco1 can be directly determined as the updated current overload coefficient; if the updated overload coefficient Kco1 is not within the overload coefficient threshold range, it is necessary to determine the updated current overload coefficient based on the overload coefficient threshold range to ensure that the updated current overload coefficient is within a limited range, so as to ensure that when the current overload coefficient is subsequently used to limit the effective value of the current phase current, it can not only achieve overload protection, but also avoid the driving safety risk of power interruption during the overload protection process.

[0160] In one embodiment, as shown in FIG7 , step S604, i.e., performing a limit process on the updated overload coefficient to obtain the updated current overload coefficient, includes:

[0161] S701: Obtaining the lower limit value and the upper limit value of the overload coefficient;

[0162] S702: If the updated overload coefficient is less than the overload coefficient lower limit, the overload coefficient lower limit is determined as the updated current overload coefficient;

[0163] S703: If the updated overload coefficient is greater than the overload coefficient upper limit, the overload coefficient upper limit is determined as the updated current overload coefficient;

[0164] S704: If the updated overload coefficient is greater than or equal to the lower limit of the overload coefficient and the updated overload coefficient is less than or equal to the upper limit of the overload coefficient, the updated overload coefficient is determined as the updated current overload coefficient.

[0165] The overload factor lower limit is the preset minimum value of the overload factor. For example, the overload factor lower limit can be set to 0. The overload factor upper limit is the preset maximum value of the overload factor. For example, the overload factor upper limit can be set to 1000. The overload factor upper limit determines the current reduction value from the current phase current RMS value to the target current limit in each overload protection cycle, thereby determining the current reduction threshold.

[0166] As an example, in step S701, the motor controller can read and obtain the lower limit value and the upper limit value of the overload coefficient from the on-board memory, so as to use the lower limit value and the upper limit value of the overload coefficient to limit the updated overload coefficient obtained in real time, so as to ensure that the current overload coefficient finally obtained is within a reasonable range, and then ensure that when the current overload coefficient is subsequently used to limit the effective value of the current phase current, it can not only achieve overload protection, but also avoid the driving safety risk of power interruption due to misjudgment in the overload protection process.

[0167] As an example, in step S702, the motor controller may compare the updated overload coefficient with the lower limit value of the overload coefficient. If the updated overload coefficient is less than the lower limit value of the overload coefficient, it is determined that the updated overload coefficient is lower than the minimum value of the allowable overload coefficient. At this time, the lower limit value of the overload coefficient may be determined as the updated current overload coefficient, and step S602 will no longer be executed, that is, the current overload coefficient will no longer be increased by the overload coefficient increment step every other overload recovery cycle to obtain the processing operation of the updated overload coefficient, so as to save the resources occupied by the processing process.

[0168] As an example, in step S703, the motor controller may compare the updated overload coefficient with the upper limit value of the overload coefficient. If the updated overload coefficient is greater than the upper limit value of the overload coefficient, it is determined that the updated overload coefficient is higher than the maximum value of the allowable overload coefficient. At this time, the upper limit value of the overload coefficient may be determined as the updated current overload coefficient, and step S603 will no longer be executed, that is, the current overload coefficient will no longer be increased by the overload coefficient increment step every other overload recovery cycle to obtain the processing operation of updating the overload coefficient, so as to save the resources occupied by the processing process.

[0169] As an example, in step S704, the motor controller may compare the updated overload coefficient with the lower and upper limits of the overload coefficient. If the updated overload coefficient is between the lower and upper limits, the updated overload coefficient is determined to be within a pre-set reasonable range. Therefore, the updated overload coefficient may be directly determined as the updated current overload coefficient. This ensures that when the updated current overload coefficient is subsequently used to limit the effective value of the current phase current, overload protection is achieved while avoiding the driving safety risk of power interruption due to misjudgment during the overload protection process. It is understood that after the updated overload coefficient is determined as the updated current overload coefficient, step S602 or step S603 must still be executed until the obtained updated overload coefficient is the upper limit of the overload coefficient or the upper limit of the overload coefficient.

[0170] In one embodiment, before step S101, that is, before collecting the three-phase current of the motor, the motor overload protection method further includes: detecting the current state of the IGBT module, performing initialization configuration when the current state is the on state, and configuring the overload coefficient upper limit value to the current overload coefficient.

[0171] The IGBT module is a power module provided in the motor controller. The current state is a state used to reflect whether the IGBT module is turned on, and the current state includes an on state and an off state.

[0172] In this example, the motor controller needs to detect the current state of its IGBT module in real time. When the current state is on, initialization configuration is required to set the overload coefficient upper limit to the current overload coefficient. This allows for immediate overload protection when an overload occurs immediately after the IGBT module is turned on. It is understood that the overload protection period and overload recovery period can also be cleared during the initialization configuration process to prevent information cached before the IGBT module is turned on from affecting the accuracy of overload protection control.

[0173] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present disclosure.

[0174] In one embodiment, a motor controller is provided, as shown in FIG8 , which 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 motor overload protection method in the above-mentioned embodiment is implemented, such as S101-S105 shown in FIG1 , or as shown in FIG2 to FIG7 . To avoid repetition, they are not described here.

[0175] In one embodiment, a car is provided, including a motor and the motor controller in the above embodiment, which will not be described in detail here to avoid repetition.

[0176] In one embodiment, a non-volatile computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the motor overload protection method in the above embodiment is implemented, such as S101-S105 shown in Figure 1, or as shown in Figures 2 to 7. To avoid repetition, it is not repeated here.

[0177] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided by the present disclosure can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0178] Those skilled in the art will clearly understand that for the sake of convenience and brevity of description, only the division of the above-mentioned functional units and modules is used as an example. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above.

[0179] The embodiments described above are only used to illustrate the technical solutions of the present disclosure, rather than to limit them. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present disclosure, and should all be included in the scope of protection of the present disclosure.

Claims

1. A motor overload protection method, include: Collect the current effective value of the motor phase current; Performing time integration on the current phase current effective value to obtain a first integral value; Obtaining a first threshold value; Performing overload detection according to the first threshold and the first integral value; as well as If there is an overload, a target limit current for the motor operation is determined, and the motor operation is controlled based on the target limit current.

2. The motor overload protection method according to claim 1, in, The obtaining of the first threshold comprises: According to the current effective value of the phase current, query the current time integral threshold table to obtain the second threshold; Acquire a current current frequency, and compare the current current frequency with a current frequency threshold; If the current current frequency is less than the current frequency threshold, correcting the second threshold according to a target correction coefficient to obtain the first threshold; and If the current current frequency is greater than or equal to the current frequency threshold, the second threshold is determined as the first threshold.

3. The motor overload protection method according to claim 2, in, The step of correcting the second threshold according to the target correction coefficient to obtain the first threshold includes: Using a threshold correction formula, the target correction coefficient is processed on the second threshold to obtain the first threshold; and The threshold correction formula is V1=K*V2, V1 is the first threshold, V2 is the second threshold, and K is the target correction coefficient.

4. The motor overload protection method according to claim 1, in, The obtaining of the first threshold comprises: According to the current effective value of the phase current, query the current time integral threshold table to obtain a second threshold; Obtaining a current motor speed, and comparing the current motor speed with an overload speed threshold; If the current motor speed is less than the overload speed threshold, an overload integral gain threshold is obtained, and a first threshold is obtained according to the second threshold and the overload integral gain threshold; and If the current motor speed is less than or equal to the overload speed threshold, the second threshold is determined as the first threshold.

5. The motor overload protection method according to claim 2 or 4, in, Before querying the current time integral threshold table according to the current phase current effective value to obtain the second threshold, the motor overload protection method further includes: Obtaining a test output current and a target operating time corresponding to the test output current; Determining a rated parameter corresponding to the test output current based on a preset constant and the target operating time; Performing time integration on the rated parameter to obtain a rated threshold value corresponding to the test output current; and A current-time integration threshold table is formed based on the test output current, the target operating time, the rated parameters and the rated threshold.

6. The motor overload protection method according to claim 1, in, The performing overload detection according to the first threshold and the first integral value includes: comparing the first integral value with a first threshold; If the first integral value is greater than the first threshold, it is determined that an overload exists; and If the first integral value is less than or equal to the first threshold, it is determined that there is no overload.

7. The motor overload protection method according to claim 1, in, The step of determining a target limiting current for the motor operation includes: Get the current overload factor; and The current overload coefficient is used to limit the current phase current effective value to obtain a target limit current.

8. The motor overload protection method according to claim 7, in, The adopting the current overload coefficient to limit the current phase current effective value to obtain a target limiting current includes: Using a limiting current calculation formula, the current overload coefficient is calculated for the current phase current effective value to obtain a target limiting current; and The limiting current calculation formula is It=(Ic*Kco) / R, wherein It is the target limiting current, Ic is the current phase current effective value, Kco is the current overload coefficient, and R is a constant.

9. The motor overload protection method according to claim 1, in, After performing overload detection according to the first threshold value and the first integral value, the motor overload protection method further includes: Get the current overload factor; If there is an overload, obtain a decreasing step length of the overload coefficient, and use the decreasing step length of the overload coefficient to decrease the current overload coefficient every other overload protection period to obtain an updated overload coefficient; and If there is no overload, the overload coefficient increment step is obtained, and the current overload coefficient is incremented by the overload coefficient increment step every overload recovery period to obtain an updated overload coefficient; The updated overload coefficient is subjected to limit processing to obtain an updated current overload coefficient.

10. The motor overload protection method according to claim 9, in, The step of obtaining the decreasing step of the overload coefficient comprises: Using a decreasing step length calculation formula, the current phase current effective value is processed to obtain an overload coefficient decreasing step length; and The calculation formula for the decrement step is Kmin=A*(Ic / Ip)+B, wherein Kmin is the decrement step of 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.

11. The motor overload protection method according to claim 9, in, The updated overload coefficient is subjected to limit processing to obtain the updated current overload coefficient, including: Get the lower limit value and upper limit value of the overload coefficient; If the updated overload coefficient is less than the overload coefficient lower limit, the overload coefficient lower limit is determined as the updated current overload coefficient; If the updated overload coefficient is greater than the overload coefficient upper limit, determining the overload coefficient upper limit as the updated current overload coefficient; and If 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, the updated overload coefficient is determined as the updated current overload coefficient.

12. A motor controller, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the motor overload protection method according to any one of claims 1 to 11 when executing the computer program.

13. A car comprising a motor and the motor controller according to claim 12.

14. A non-volatile computer-readable storage medium storing a computer program, wherein the computer program, when executed by a processor, implements the motor overload protection method according to any one of claims 1 to 11.

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