Locked-rotor torque protection method and device, vehicle and equipment

Abstract

The invention relates to the technical field of vehicle locked-rotor protection, and discloses a locked-rotor torque protection method and device, a vehicle and equipment, an electric drive system comprises a cooling system and a motor, and the method comprises the steps that in response to the fact that the motor is in a locked-rotor state, working parameters of the electric drive system are inquired; the working parameters comprise the liquid inlet temperature and the liquid inlet flow of the cooling system; determining a torque limiting coefficient based on the liquid inlet temperature and the liquid inlet flow; the torque limiting coefficient indicates the heat dissipation rate of the cooling system; a locked-rotor torque limit is determined based on the torque limit factor and a predetermined maximum allowable torque. By the adoption of the scheme, the locked-rotor torque limit value is obtained based on the current parameters of the liquid inlet temperature and the liquid inlet flow, the liquid inlet temperature and the liquid inlet flow are related to the heat dissipation efficiency of the cooling system, the locked-rotor torque limit value is related to the current running state of the cooling system, and when the cooling system runs well, the corresponding locked-rotor torque limit value is larger; therefore, the vehicle can get out of trouble more quickly.

Description

Technical Field

[0001] This invention relates to the field of vehicle stall protection technology, and in particular to a stall torque protection method, device, vehicle and equipment. Background Technology

[0002] Currently, most pure electric vehicles use three-phase motors for their electric drive systems. Precise control of the motor's output torque is achieved by adjusting the switching duty cycle of the three-phase insulated-gate bipolar transistors (IGBTs) through a controller. Under heavy load conditions such as full-load hill climbing, the motor speed approaches zero (locked state), and the three-phase current loses its sinusoidal alternating characteristic. This causes concentrated conduction of the IGBT bridge arm current, leading to a surge in chip junction temperature. Without protection, this can result in IGBT failure due to high temperature.

[0003] To prevent damage to the IGBTs in the electric drive system during stall, the stall protection torque threshold is typically set based on the worst-case scenario of the vehicle's cooling system (e.g., the inlet flow rate and inlet temperature when the coolant is 8L / 65℃). This threshold is usually set to 80%–90% of the peak torque. However, in actual vehicle operation, the coolant flow rate rarely reaches the thermal boundary. Setting the torque limit based on this boundary is overly conservative most of the time and fails to provide stall torque protection according to the actual operating environment of the vehicle, resulting in low output torque. Summary of the Invention

[0004] In order to overcome the problem that the existing technology uses the worst-case boundary to limit the torque output when the vehicle is stalled, resulting in an overly conservative torque output, the present invention provides a stall torque protection method, device, vehicle and equipment.

[0005] In a first aspect, to solve the above-mentioned technical problems, the present invention provides a stall torque protection method, wherein the electric drive system includes a cooling system and a motor, and the method includes:

[0006] In response to the motor being in a stalled state, the operating parameters of the electric drive system are queried; the operating parameters include the inlet temperature and inlet flow rate of the cooling system.

[0007] Based on the inlet temperature and the inlet flow rate, a torque limiting factor is determined; the torque limiting factor indicates the heat dissipation rate of the cooling system.

[0008] Based on the torque limitation coefficient and the predetermined maximum allowable torque, the stall torque limit is determined.

[0009] In one embodiment, the torque limiting factor includes a first torque limiting factor and / or a second torque limiting factor;

[0010] The determination of the torque limiting coefficient based on the inlet temperature and the inlet flow rate includes:

[0011] Determine whether the inlet temperature is within a preset temperature range and whether the inlet flow rate is within a preset flow rate range;

[0012] If so, then a first torque limiting coefficient is determined based on the inlet temperature and the inlet flow rate;

[0013] If not, a preset second torque limiting coefficient is obtained; wherein the second torque limiting coefficient indicates that the heat dissipation rate is 0.

[0014] In one embodiment, determining the first torque limiting coefficient based on the inlet temperature and the inlet flow rate includes:

[0015] Based on the inlet temperature and the inlet flow rate, a torque limiting coefficient mapping table is consulted to determine the corresponding first torque limiting coefficient; wherein, the torque limiting coefficient mapping table includes the first torque limiting coefficient corresponding to the inlet temperature and the inlet flow rate.

[0016] In one embodiment, the torque limiting coefficient mapping table is calibrated in the following manner:

[0017] Obtain multiple inlet temperatures and multiple inlet flow rates;

[0018] The values ​​of the inlet temperature and the inlet flow rate are combined one by one to generate multiple pairs;

[0019] Determine the maximum permissible torque;

[0020] Determine the first maximum stall torque corresponding to the pairing;

[0021] The first torque limit coefficient is obtained by using the first maximum stall torque and the maximum permissible torque;

[0022] Based on all the pairings and their corresponding first torque limiting coefficients, a mapping table is generated for the inlet temperature, the inlet flow rate, and the first torque limiting coefficient.

[0023] In one embodiment, the electric drive system includes an output shaft and a rotor, the output shaft being connected to the rotor which is rotated to a set angle, the set angle being at least two.

[0024] Determining the first maximum stall torque corresponding to the pairing includes:

[0025] For each pairing, determine the maximum stall torque corresponding to at least two of the set angles, and select the minimum value as the first maximum stall torque;

[0026] The first torque limit coefficient is obtained by using the first maximum stall torque and the maximum permissible torque.

[0027] In one embodiment, the electric drive system further includes an insulated-gate bipolar transistor.

[0028] For each pairing, determining the maximum stall torque corresponding to at least two set angles includes:

[0029] Lock the output shaft;

[0030] The output torque of the rotor is increased incrementally until the temperature of the insulated gate bipolar transistor reaches its maximum allowable temperature, and / or the output torque reaches the maximum allowable torque, and the output torque is determined to be the maximum stall torque of the electric drive system.

[0031] In one embodiment, the electric drive system includes an output shaft and a rotor, the output shaft being connected to the rotor which is rotated to a set angle, the set angle being at least two.

[0032] The steps for obtaining the second torque limiting coefficient include:

[0033] Drain the coolant from the cooling system;

[0034] Adjust the ambient temperature to the set temperature and maintain it for the set time;

[0035] Determine the maximum stall torque corresponding to at least two of the set angles, and take the minimum value as the second maximum stall torque;

[0036] The second torque limit coefficient is obtained by using the second maximum stall torque and the maximum permissible torque.

[0037] Secondly, the present invention also provides a stall torque protection device, wherein the electric drive system includes a cooling system and a motor, and the device includes:

[0038] The cooling system parameter acquisition module queries the operating parameters of the electric drive system in response to the motor being in a stalled state; the operating parameters include the inlet temperature and inlet flow rate of the cooling system.

[0039] A torque limiting coefficient acquisition module is used to determine a torque limiting coefficient based on the inlet liquid temperature and the inlet liquid flow rate; the torque limiting coefficient indicates the heat dissipation rate of the cooling system.

[0040] The stall torque acquisition module is used to determine the stall torque limit based on the torque limit coefficient and the predetermined maximum allowable torque.

[0041] Thirdly, the present invention also provides a vehicle that includes a stall torque protection device.

[0042] Fourthly, the present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor.

[0043] The processor executes the stall torque protection method.

[0044] The beneficial effects of this invention are as follows: When determining that the electric drive system is stalled, this application combines the inlet temperature and inlet flow rate of the coolant to make a judgment, determines the corresponding torque limit coefficient based on the real-time inlet temperature and inlet flow rate, calculates the maximum allowable torque with the torque limit coefficient and obtains the stalled torque limit value, thereby using the stalled torque limit value as the maximum torque value output by the electric drive system, which limits the torque output value of the electric drive system.

[0045] Compared to existing technologies that uniformly set the stall protection torque threshold based on the worst-case boundary of the vehicle's cooling system when the electric drive system stalls, this solution obtains the stall torque limit based on the current parameters of the inlet temperature and flow rate. Since the inlet temperature and flow rate are related to the cooling system's heat dissipation efficiency, the stall torque limit obtained by this solution is correlated with the current operating state of the cooling system. When the cooling system is operating well, the corresponding stall torque limit will be larger. This increases the upper limit of torque that the electric drive system can output, especially in extreme stall-related conditions such as hill climbing, prompting the electric drive system to output higher torque to the vehicle, enabling the vehicle to recover from stalling more quickly. Therefore, compared to existing technologies, this solution better releases the performance of the electric drive system when the cooling system is operating normally, which is beneficial for coping with extreme vehicle operating conditions. Attached Figure Description

[0046] Figure 1 This is a schematic flowchart of a stall torque protection method in one embodiment of the present invention;

[0047] Figure 2 This is a flowchart illustrating the step of obtaining the maximum permissible torque in one embodiment of the present invention;

[0048] Figure 3 This is a flowchart illustrating the step of determining the torque limiting coefficient based on the inlet temperature and inlet flow rate in one embodiment of the present invention.

[0049] Figure 4 This is a flowchart illustrating the steps for obtaining the torque limiting coefficient mapping table in one embodiment of the present invention;

[0050] Figure 5 This is a flowchart illustrating the step of obtaining the corresponding torque limiting coefficient based on each pairing in one embodiment of the present invention.

[0051] Figure 6 This is a schematic diagram of the process for obtaining the first maximum stall torque corresponding to at least two set angles in one embodiment of the present invention;

[0052] Figure 7 This is a schematic diagram of the process for obtaining the second torque limiting coefficient in one embodiment of the present invention;

[0053] Figure 8 This is a schematic diagram of the process for obtaining the third maximum stall torque when the output shaft is connected to a rotor rotated to at least two set angles, according to one embodiment of the present invention.

[0054] Figure 9 This is a structural block diagram of a virtual device in one embodiment of the present invention;

[0055] Figure 10 This is an internal structural diagram of a computer device according to one embodiment of the present invention. Detailed Implementation

[0056] The technical solution of this application will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments and specific features in the embodiments are detailed descriptions of the technical solution of this application, rather than limitations on the technical solution of this application. Unless otherwise specified, the embodiments and technical features in the embodiments can be combined with each other.

[0057] The terms "first" and "second" in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the term "comprising" and any variations thereof are intended to cover non-exclusive protection. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices. The term "multiple" in this application can mean at least two, for example, two, three, or more, and is not limited by the embodiments of this application.

[0058] To facilitate understanding of the technical solutions provided in the embodiments of this application, the design concept of the embodiments of this application will be introduced first below:

[0059] In existing technologies, under heavy load conditions such as full-load climbing, the motor speed approaches zero (locked state), and the three-phase current loses its sinusoidal alternating characteristic. This leads to concentrated conduction of the three-phase insulated-gate bipolar transistor (IGBT) bridge arm current and a surge in temperature. Without protection, this can cause IGBT failure due to high temperature. To protect the electric drive system from IGBT damage during stall, the stall protection torque threshold is typically set based on the worst-case scenario of the vehicle's cooling system. However, since it is difficult to reach the worst-case scenario during vehicle stall operation, limiting the torque based on the worst-case scenario is too conservative, resulting in an excessively low output torque threshold. Because the output torque threshold affects the vehicle's ability to get out of trouble, the existing limitations make it difficult or impossible for the vehicle to get out of trouble.

[0060] Therefore, this application provides a stall torque protection method that combines the current inlet temperature and inlet flow rate to obtain a corresponding torque limiting coefficient, thereby obtaining a stall torque limit. This method avoids using the torque threshold corresponding to the worst-case scenario as in the prior art, and instead obtains the stall torque limit based on the real-time condition of the vehicle. The obtained stall torque limit is closer to the actual torque threshold that the vehicle can output, thus providing torque limiting protection for the vehicle while increasing the vehicle's ability to get out of trouble.

[0061] This application provides a stall torque protection method. See [link to relevant documentation]. Figure 1 The electric drive system includes a cooling system and a motor, and the method includes the following steps:

[0062] Step 100: In response to the motor being in a stalled state, query the operating parameters of the electric drive system; the operating parameters include the inlet temperature and inlet flow rate of the cooling system.

[0063] This embodiment is applied when the motor is in a stalled state. After determining that the motor is in a stalled state, the relevant operating parameters of the electric drive system are queried to make further judgments. The relevant operating parameters include the inlet temperature and the inlet flow rate. In addition, the inlet temperature and the inlet flow rate are the inlet temperature and the inlet flow rate of the coolant.

[0064] Correspondingly, the conditions for determining whether a motor is in a stalled state are usually: the speed is lower than the set speed, and the torque is greater than the torque threshold. Since there are no uniform fixed reference values ​​for the set speed and torque threshold, and they are highly dependent on the specific motor model, vehicle design, control strategy, and safety requirements, and determining whether a motor is in a stalled state is existing technology, no specific numerical restrictions are given for the speed and torque thresholds used for stall determination here. Rated torque refers to the torque value that the motor can continuously output without exceeding the temperature rise limit; it is an indicator of continuous working capability. Peak torque refers to the maximum torque that the motor can output in a short period (a few seconds to tens of seconds), limited by inverter current, battery discharge capacity, and motor electromagnetic design, but cannot be sustained due to heat limitations. The torque threshold is much greater than the rated torque; at the same time, the torque threshold is often close to the peak torque, and the torque threshold is kept no greater than the peak torque.

[0065] Step 200: Determine the torque limiting factor based on the inlet temperature and inlet flow rate; the torque limiting factor indicates the heat dissipation rate of the cooling system.

[0066] In this embodiment, the corresponding torque limiting coefficient is determined by the inlet liquid temperature and the inlet liquid flow rate. Correspondingly, the torque limiting coefficient is related to the heat dissipation rate of the cooling system. Thus, the current cooling effect of the cooling system can be obtained based on the parameters of the inlet liquid temperature and the inlet liquid flow rate. For example, the torque limiting coefficient is positively correlated with the heat dissipation rate of the cooling system, so the heat dissipation rate of the cooling system can indicate the torque limiting coefficient.

[0067] Step 300: Determine the stall torque limit based on the torque limit coefficient and the predetermined maximum allowable torque.

[0068] The stall torque limit is determined by the torque limit coefficient and the maximum allowable torque. The obtained stall torque limit is used as the maximum output torque of the motor, thereby limiting the output torque of the motor in the stall state. This makes the stall torque limit obtained by this scheme related to the current operating state of the cooling system. When the cooling system is operating well, the corresponding stall torque limit will be larger, which makes it easier to increase the upper limit of the torque that the electric drive system can output. This allows the vehicle to get out of trouble more quickly in conditions such as climbing hills because the vehicle can output higher torque.

[0069] Specifically, the stall torque limit is the product of the torque limit factor and the maximum permissible torque. The torque limit factor is a positive value less than 1.

[0070] In the aforementioned stall torque protection method, a torque limiting coefficient is determined based on the inlet temperature and inlet flow rate. A stall torque limit is then determined based on the torque limiting coefficient and the maximum permissible torque. This stall torque limit limits the maximum output torque of the motor in stall condition, thus linking the stall torque limit to the inlet temperature and inlet flow rate in stall condition. Since the inlet temperature and inlet flow rate are related to the cooling capacity of the cooling system, the stall torque limit is set to better protect the vehicle's electric drive system. Simultaneously, a higher stall torque limit is provided when the cooling system is cooling normally. Because the vehicle's ability to get out of trouble is positively correlated with the stall torque limit, this method improves the vehicle's ability to get out of trouble.

[0071] In one embodiment, the operating parameters also include the motor speed;

[0072] See Figure 2 The maximum permissible torque is determined by the following method, including the following steps:

[0073] Step 401: Obtain the external characteristic curve of the motor.

[0074] The external characteristic curve of a motor is related to the properties of the motor itself. The external characteristic curve reflects the performance of the motor and is related to the type of motor, design parameters, power supply conditions (voltage, frequency), control strategy adopted, and operating environment (temperature, heat dissipation).

[0075] Step 402: Determine the maximum permissible torque corresponding to the rotational speed in the external characteristic curve.

[0076] In this embodiment, based on the motor's rotational speed, the corresponding maximum permissible torque can be queried from the external characteristic curve, thereby obtaining the maximum permissible torque corresponding to the current rotational speed.

[0077] In one embodiment, the torque limiting factor includes a first torque limiting factor and / or a second torque limiting factor.

[0078] In the embodiments, the torque limiting coefficient includes only the first torque limiting coefficient or the second torque limiting coefficient, or the torque limiting coefficient includes both the first torque limiting coefficient and the second torque limiting coefficient; here, the torque limiting coefficient can be understood as a set of one or more data, and the corresponding first torque limiting coefficient and second torque limiting coefficient can also be understood as a single value or a set of values.

[0079] See Figure 3 In step 200, the torque limiting coefficient is determined based on the inlet temperature and inlet flow rate, including the following steps:

[0080] Step 210: Determine whether the inlet temperature is within the preset temperature range and whether the inlet flow rate is within the preset flow rate range.

[0081] The system determines whether the inlet temperature and the inlet flow rate are within the preset range. Based on these determinations, the cooling effect of the cooling system is characterized. In other words, whether the inlet temperature and the inlet flow rate are within the preset range is related to the cooling effect of the cooling system.

[0082] Step 220: If so, determine the first torque limiting coefficient based on the inlet temperature and inlet flow rate.

[0083] In this embodiment, if the inlet temperature is within a preset temperature range and the inlet flow rate is within a preset flow rate range, the cooling system can perform normal cooling, and a first torque limiting coefficient can be obtained accordingly. Here, the first torque limiting coefficient can be a set, and the specific value of the first torque limiting coefficient can be obtained according to the corresponding inlet temperature and inlet flow rate.

[0084] Step 230: If not, a preset second torque limit coefficient is obtained; wherein, the second torque limit coefficient indicates that the heat dissipation rate is 0.

[0085] In this embodiment, if both the inlet temperature and the inlet flow rate are outside the preset temperature range and the preset flow rate is outside the preset flow rate range, a second torque limiting coefficient can be obtained. That is, in this case, since both the inlet temperature and flow rate are outside the corresponding preset ranges, the cooling system cannot perform normal cooling or the electric drive system is in a state without coolant, and the electric drive system is operating under severe conditions. The corresponding second torque limiting coefficient can be unified into a specific value to protect the electric drive system. Since this specific value encompasses both abnormal cooling system operation and cooling system non-operation, and the cooling system non-operation is more severe, to protect the electric drive system, the cooling system non-operation state is used to obtain the second torque limiting coefficient, and therefore the corresponding heat dissipation rate is 0. For example, the second torque limiting coefficient can be 0.3. Since the second torque limiting coefficient defined in this invention corresponds to a cooling system failure state, a value smaller than the worst-case boundary of the prior art is used to reduce the stall torque limit, thereby ensuring control of the electric drive system's temperature rise and avoiding overheating.

[0086] In the embodiment, it is known that the stall torque limit is the product of the torque limit coefficient and the maximum allowable torque, that is, the torque limit coefficient is proportional to the stall torque limit, and the torque limit coefficient is also proportional to the IGBT temperature; the higher the stall torque, the higher the IGBT temperature. Furthermore, since the first torque limit coefficient is under normal cooling by the coolant, while the corresponding second torque limit coefficient is under abnormal cooling, it can be known that when the first torque limit coefficient is used, the cooling capacity of the corresponding cooling system is strong, and the corresponding stall torque limit is relatively large; when the second torque limit coefficient is used, the cooling capacity of the corresponding cooling system is weak or nonexistent, and the corresponding stall torque limit is relatively small. Therefore, it can be determined that the cooling capacity corresponding to the first torque limit coefficient is strong, capable of handling greater torque and cooling down; thus, the first torque limit coefficient is not less than the second torque limit coefficient.

[0087] In one embodiment, in step 220, a first torque limiting coefficient is determined based on the inlet temperature and inlet flow rate, including the following operations:

[0088] Based on the inlet temperature and inlet flow rate, the torque limiting coefficient mapping table is consulted to determine the corresponding first torque limiting coefficient; wherein, the torque limiting coefficient mapping table includes the first torque limiting coefficient corresponding to the inlet temperature and the inlet flow rate.

[0089] In this embodiment, the torque limiting coefficient mapping table is used to characterize the relationship between the inlet temperature and the inlet flow rate and the first torque limiting coefficient. That is, when the inlet temperature and the inlet flow rate are known, the corresponding first torque limiting coefficient can be obtained by querying the torque limiting coefficient mapping table.

[0090] In one embodiment, see Figure 4 The torque limit coefficient mapping table is obtained by calibration in the following way:

[0091] Step 510: Obtain multiple inlet temperatures and multiple inlet flow rates.

[0092] Since the entire torque limit coefficient mapping table needs to be obtained, multiple sets of data are needed to refine the range covered by the torque limit coefficient mapping table, so as to facilitate obtaining the corresponding closer data when looking up the table.

[0093] Step 520: Combine the values ​​of inlet temperature and inlet flow rate one by one to generate multiple pairs.

[0094] Each pair includes the corresponding inlet temperature and inlet flow rate.

[0095] Step 530: Determine the maximum permissible torque.

[0096] For the method of obtaining the maximum permissible torque, please refer to steps 401 to 402.

[0097] Step 540: Determine the first maximum stall torque corresponding to the pairing.

[0098] When each pairing value is known, i.e. the inlet temperature and inlet flow rate are known, the corresponding first torque limit coefficient is obtained.

[0099] Step 550: Obtain the corresponding first torque limit coefficient by using the first maximum stall torque and the maximum permissible torque.

[0100] In the embodiment, when the second maximum stall torque and the maximum permissible torque are known, the ratio of the second maximum stall torque to the maximum permissible torque is the corresponding first torque limit coefficient.

[0101] Step 560: Based on all pairings and their corresponding first torque limit coefficients, generate a mapping table of inlet temperature, inlet flow rate and first torque limit coefficients.

[0102] After obtaining the corresponding first torque limit coefficient for each pairing, multiple pairs are used to obtain multiple corresponding first torque limit coefficients, which are then integrated to generate a mapping table of inlet temperature, inlet flow rate, and first torque limit coefficient. This torque limit coefficient mapping table is obtained through the above steps and is used in the stall torque protection method of this scheme. When the inlet temperature and inlet flow rate are known, the torque limit coefficient mapping table can be queried based on the inlet temperature and inlet flow rate to obtain the corresponding first torque limit coefficient and thus obtain the corresponding stall torque limit value.

[0103] For example, as shown in the table below:

[0104] Table 1 is a torque limitation coefficient mapping table.

[0105]

[0106] Table 1 shows the relationship between inlet temperature, inlet flow rate and first torque limiting coefficient. The corresponding inlet temperature values ​​are -20℃, 0℃, 20℃, 40℃ and 60℃; the corresponding inlet flow rate values ​​are 2L / min, 4L / min, 6L / min, 8L / min, 10L / min and 12L / min. When determining the inlet temperature and inlet flow rate, refer to the table to determine the corresponding first torque limiting coefficient. The table shows that when there is only one variable, such as a lower inlet temperature or a higher inlet flow rate, the corresponding first torque limiting coefficient is larger. If the inlet flow rate is in the range of 2L / min to 12L / min and the inlet temperature is in the range of -20℃ to 60℃, and the data does not fall within the range of the table, a conservative approach can be used. For example, if the inlet temperature is 10℃ and the inlet flow rate is 3L / min, the data of an inlet temperature of 20℃ and an inlet flow rate of 2L / min can be used, resulting in a first torque limiting coefficient of 0.86. It should be understood that the above is only an example of one possible value and is not intended to restrict the values ​​in the torque limiting coefficient mapping table.

[0107] In one embodiment, the electric drive system includes an output shaft and a rotor, the output shaft being connected to the rotor which is rotated to a set angle, the set angle being at least two.

[0108] In step 540, the first maximum stall torque corresponding to the pairing is determined, including the following steps, see [link to relevant documentation]. Figure 5 :

[0109] Step 541: For each pair, determine the maximum stall torque corresponding to at least two set angles, and select the minimum value as the first maximum stall torque.

[0110] In each pairing, since the output shaft and the rotor rotated to at least two set angles are connected sequentially in each pairing, the output shaft will receive a corresponding first maximum stall torque each time it is connected to the rotor rotated to a set angle; therefore, the rotor will receive the same number of first maximum stall torques as the number of set angles corresponding to multiple set angles.

[0111] Since multiple first maximum stall torques are obtained for each pair, in order to ensure the safety of vehicle stall operation, the minimum value among all first maximum stall torques is taken as the second maximum stall torque, and subsequent operations are performed using the second maximum stall torque.

[0112] Step 542: Obtain the corresponding first torque limit coefficient by using the first maximum stall torque and the maximum permissible torque.

[0113] In this embodiment, when the first maximum stall torque and the maximum permissible torque are known, the ratio of the first maximum stall torque to the maximum permissible torque is the corresponding first torque limit coefficient. The current motor speed is obtained, and the corresponding maximum permissible torque is determined by mapping the motor speed to the external characteristic curve.

[0114] In one embodiment, the electric drive system also includes an insulated gate bipolar transistor, see [link to relevant documentation]. Figure 6 In step 541, for each pair, the maximum stall torque corresponding to at least two set angles is determined, and the minimum value is selected as the first maximum stall torque, including the following steps: (that is, the following operation steps need to be performed at each corresponding set angle).

[0115] Step 5411: Lock the output shaft.

[0116] The position of the output shaft is fixed, which means that the rotor connected to the output shaft is fixed so that neither the output shaft nor the rotor can rotate.

[0117] Step 5412: Increase the output torque of the rotor until the temperature of the insulated gate bipolar transistor reaches its maximum allowable temperature, and / or the output torque reaches the maximum allowable torque, and determine the output torque as the maximum stall torque of the electric drive system.

[0118] The torque request value of the rotor is slowly increased. During this process, since the rotor cannot rotate, the temperature of the corresponding insulated gate bipolar transistor will gradually rise. Therefore, the temperature of the insulated gate bipolar transistor is detected. If at least one of the following conditions is met, the torque request value is stopped from being increased: the temperature of the insulated gate bipolar transistor reaches its maximum allowable temperature, or the output torque reaches the maximum allowable torque.

[0119] In this embodiment, the temperature of the insulated-gate bipolar transistor (IGBT) reaches its maximum allowable temperature, corresponding to six angle values ​​of the Park transformation (also known as the dq transformation, a core coordinate transformation technology in motor vector control): 0°, 60°, 120°, 180°, 240°, and 300°. Since the commutation point of the IGBT is such that the system automatically switches the conducting phase to the phase with the highest current demand at every 60° switching interval, the six angle values ​​correspond one-to-one with the IGBT commutation point. Using this angle setting method, the rotor's set angles include 0°, 60°, 120°, 180°, 240°, and 300°. In summary, through the fixed-angle Park transformation of six angles, essentially through angle discretization, the rotor position is directly bound to the optimal conducting phase of the IGBT. Each angle corresponds to the moment when the phase current reaches its peak, thus allowing the acquisition of the maximum temperature of the IGBT required by this solution.

[0120] The output torque at the point where the increase stops is taken as the maximum stall torque of the electric drive system. Since each set angle has a corresponding maximum stall torque, the minimum value among all the maximum stall torques is selected as the first maximum stall torque. The first torque limit coefficient is obtained based on the first maximum stall torque. That is, the ratio of the first maximum stall torque to the maximum allowable torque is the corresponding first torque limit coefficient.

[0121] In one embodiment, see Figure 7 The electric drive system includes an output shaft and a rotor. The output shaft is connected to the rotor, which is rotated to a set angle. There are at least two set angles.

[0122] The steps for obtaining the second torque limiting coefficient include the following:

[0123] Step 610: Drain the coolant from the cooling system.

[0124] Because it is necessary to simulate the cooling system under the worst operating conditions, the coolant is drained directly, with the condition that the cooling system cannot provide cooling effect as the basis.

[0125] In this embodiment, the operation of obtaining the second torque limiting coefficient can be performed on a simulation test bench, thereby facilitating the placement of the simulation test bench in the corresponding environment for operation.

[0126] Step 620: Adjust the ambient temperature to the set temperature and maintain it for the set time.

[0127] In simulating harsh operating conditions without coolant, the simulation test bench is placed at a set temperature and maintained for a set time to simulate the electric drive system under harsh temperature conditions.

[0128] In one embodiment, the temperature is set to 45°C and the time is set to 4 hours.

[0129] Step 630: Determine the maximum stall torque corresponding to at least two of the set angles, and take the minimum value as the second maximum stall torque.

[0130] Since the output shaft and the rotor, which rotates to at least two set angles, are connected sequentially, each time the output shaft is connected to a rotor that has rotated to a set angle, a corresponding maximum stall torque is obtained. Therefore, the rotor has multiple set angles, each corresponding to a maximum stall torque equal to the number of set angles. To ensure the safety of the vehicle during stall operation, the minimum value among all maximum stall torques is taken as the second maximum stall torque, and subsequent operations are performed using the second maximum stall torque.

[0131] Step 640: Obtain the corresponding second torque limit coefficient by using the second maximum stall torque and the maximum permissible torque.

[0132] In the embodiment, when the second maximum stall torque and the maximum permissible torque are known, the ratio of the second maximum stall torque to the maximum permissible torque is the corresponding second torque limit coefficient.

[0133] See Figure 8 In step 630, the maximum stall torque corresponding to at least two of the set angles is determined, and the minimum value is taken as the second maximum stall torque. This includes the following two steps: (that is, the following operation steps need to be performed at each corresponding set angle).

[0134] Step 631, lock the output shaft.

[0135] The position of the output shaft is fixed, which means that the rotor connected to the output shaft is fixed so that neither the output shaft nor the rotor can rotate.

[0136] Step 632: Increase the output torque of the rotor until the temperature of the insulated gate bipolar transistor reaches its maximum allowable temperature, and / or the output torque reaches the maximum allowable torque, and determine the output torque as the maximum stall torque of the electric drive system.

[0137] The torque request value of the rotor is slowly increased. During this process, since the rotor cannot rotate, the temperature of the corresponding insulated gate bipolar transistor will gradually rise. Therefore, the temperature of the insulated gate bipolar transistor is detected. If at least one of the following conditions is met, the torque request value is stopped from being increased: the temperature of the insulated gate bipolar transistor reaches its maximum allowable temperature, or the output torque reaches the maximum allowable torque.

[0138] Similarly, steps 632 and 5412 use the same principle, and the relevant Park transformation will not be described in detail here.

[0139] The torque request value at the point where the increase stops is taken as the maximum stall torque of the electric drive system. Then, based on multiple maximum stall torques, the minimum value is taken to obtain the second torque limit coefficient. That is, the ratio of the second maximum stall torque to the maximum allowable torque is the corresponding second torque limit coefficient.

[0140] The present invention also provides a stall torque protection device, see [link to relevant documentation]. Figure 9 The electric drive system includes a cooling system and a motor, and the device includes a cooling system parameter acquisition module 710, a torque limiting coefficient acquisition module 720, and a stall torque acquisition module 730.

[0141] The cooling system parameter acquisition module 710 queries the operating parameters of the electric drive system in response to the motor being in a stalled state; the operating parameters include the inlet temperature and inlet flow rate of the cooling system.

[0142] The torque limiting coefficient acquisition module 720 is used to determine the torque limiting coefficient based on the inlet liquid temperature and the inlet liquid flow rate; the torque limiting coefficient indicates the heat dissipation rate of the cooling system.

[0143] The stall torque acquisition module 730 is used to determine the stall torque limit based on the torque limit coefficient and the predetermined maximum allowable torque.

[0144] In one embodiment, the cooling system parameter acquisition module 710 is specifically used for:

[0145] Obtain the motor speed.

[0146] In one embodiment, the moment constraint coefficient acquisition module 720 is specifically used for:

[0147] Determine whether the inlet temperature is within a preset temperature range and whether the inlet flow rate is within a preset flow rate range; if yes, determine a first torque limiting coefficient based on the inlet temperature and the inlet flow rate; if no, obtain a preset second torque limiting coefficient.

[0148] In one embodiment, determining a first torque limiting coefficient based on the inlet temperature and the inlet flow rate includes the following operations: querying a torque limiting coefficient mapping table according to the inlet temperature and the inlet flow rate to determine the corresponding first torque limiting coefficient; wherein, the torque limiting coefficient mapping table includes the first torque limiting coefficient corresponding to the inlet temperature and the inlet flow rate.

[0149] In one embodiment, the moment constraint coefficient acquisition module 720 is further configured to:

[0150] Obtaining a torque limiting coefficient mapping table includes the following steps: obtaining multiple inlet temperatures and multiple inlet flow rates; combining the values ​​of the inlet temperature and the inlet flow rate one by one to generate multiple pairs; determining the maximum allowable torque; determining the first maximum stall torque corresponding to the pair; obtaining the corresponding first torque limiting coefficient through the first maximum stall torque and the maximum allowable torque; and generating a mapping table of the inlet temperature, the inlet flow rate, and the first torque limiting coefficient based on all the pairs and their corresponding first torque limiting coefficients.

[0151] In one embodiment, determining the first maximum stall torque corresponding to the pairing includes: for each pairing, determining the maximum stall torque corresponding to at least two of the set angles, and selecting the minimum value as the first maximum stall torque; obtaining the corresponding first torque limit coefficient through the first maximum stall torque and the maximum permissible torque.

[0152] In one embodiment, the step of obtaining the second torque limiting coefficient includes: draining the coolant from the cooling system; adjusting the ambient temperature to a set temperature and maintaining it for a set time; obtaining the third maximum stall torque corresponding to when the output shaft is connected to the rotor rotated to at least two set angles respectively; taking the minimum value of the third maximum stall torque as the fourth maximum stall torque; and obtaining the corresponding torque limiting coefficient through the fourth maximum stall torque and the maximum permissible torque.

[0153] In one embodiment, determining the maximum stall torque corresponding to at least two of the set angles for each pair includes: locking the output shaft; increasing the output torque of the rotor until the temperature of the insulated gate bipolar transistor reaches its maximum allowable temperature, and / or the output torque reaches the maximum allowable torque, and determining the output torque as the maximum stall torque of the electric drive system.

[0154] In one embodiment, the step of obtaining the second torque limiting coefficient includes: draining the coolant from the cooling system; adjusting the ambient temperature to a set temperature and maintaining it for a set time; determining the maximum stall torque corresponding to at least two of the set angles, and taking the minimum value as the second maximum stall torque; and obtaining the corresponding second torque limiting coefficient through the second maximum stall torque and the maximum permissible torque.

[0155] In one embodiment, determining the maximum stall torque corresponding to at least two of the set angles and taking the minimum as the second maximum stall torque includes: locking the output shaft; increasing the output torque of the rotor until the temperature of the insulated gate bipolar transistor reaches its maximum allowable temperature, and / or the output torque reaches the maximum allowable torque, and determining the output torque as the maximum stall torque of the electric drive system.

[0156] In one embodiment, the moment constraint coefficient acquisition module 730 is specifically used for:

[0157] The maximum permissible torque is obtained by the following method: obtaining the external characteristic curve of the motor; and determining the maximum permissible torque corresponding to the rotational speed in the external characteristic curve.

[0158] The present invention also provides a vehicle including a stall torque protection device.

[0159] In one embodiment, a computer device is provided, which may be a server, and its internal structure diagram may be as follows: Figure 10As shown, the computer device includes a processor, memory, network interface, and database connected via a system bus. The processor provides computing and control capabilities. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores the operating system, computer programs, and database. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The database stores data for a preset correction factor used to determine the first electrical charge required for the transitional operating condition, and a preset table used to determine the length of time required for the range extender to experience the transitional operating condition. The network interface is used for communication with external terminals via a network connection. When executed by the processor, the computer program implements a stall torque protection method.

[0160] Those skilled in the art will understand that Figure 10 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0161] In one embodiment, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to perform the following steps:

[0162] In response to the motor being in a stalled state, the operating parameters of the electric drive system are queried; the operating parameters include the inlet temperature and inlet flow rate of the cooling system.

[0163] Based on the inlet temperature and the inlet flow rate, a torque limiting factor is determined; the torque limiting factor indicates the heat dissipation rate of the cooling system.

[0164] Based on the torque limitation coefficient and the predetermined maximum allowable torque, the stall torque limit is determined.

[0165] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0166] The maximum permissible torque is determined by the following method:

[0167] Obtain the external characteristic curve of the motor;

[0168] In the external characteristic curve, the maximum permissible torque corresponding to the rotational speed is determined.

[0169] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0170] The determination of the torque limiting coefficient based on the inlet temperature and the inlet flow rate includes:

[0171] Determine whether the inlet temperature is within a preset temperature range and whether the inlet flow rate is within a preset flow rate range;

[0172] If so, then a first torque limiting coefficient is determined based on the inlet temperature and the inlet flow rate;

[0173] If not, a preset second torque limiting coefficient is obtained; wherein the second torque limiting coefficient indicates that the heat dissipation rate is 0.

[0174] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0175] Based on the inlet temperature and the inlet flow rate, a torque limiting coefficient mapping table is consulted to determine the corresponding first torque limiting coefficient; wherein, the torque limiting coefficient mapping table includes the first torque limiting coefficient corresponding to the inlet temperature and the inlet flow rate.

[0176] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0177] Obtain multiple inlet temperatures and multiple inlet flow rates;

[0178] The values ​​of the inlet temperature and the inlet flow rate are combined one by one to generate multiple pairs;

[0179] Determine the maximum permissible torque;

[0180] Determine the first maximum stall torque corresponding to the pairing;

[0181] The first torque limit coefficient is obtained by using the first maximum stall torque and the maximum permissible torque;

[0182] Based on all the pairings and their corresponding first torque limiting coefficients, a mapping table is generated for the inlet temperature, the inlet flow rate, and the first torque limiting coefficient.

[0183] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0184] For each pairing, determine the maximum stall torque corresponding to at least two of the set angles, and select the minimum value as the first maximum stall torque;

[0185] The first torque limit coefficient is obtained by using the first maximum stall torque and the maximum permissible torque.

[0186] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0187] Lock the output shaft;

[0188] The output torque of the rotor is increased incrementally until the temperature of the insulated gate bipolar transistor reaches its maximum allowable temperature, and / or the output torque reaches the maximum allowable torque, and the output torque is determined to be the maximum stall torque of the electric drive system.

[0189] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0190] Drain the coolant from the cooling system;

[0191] Adjust the ambient temperature to the set temperature and maintain it for the set time;

[0192] Determine the maximum stall torque corresponding to at least two of the set angles, and take the minimum value as the second maximum stall torque;

[0193] The second torque limit coefficient is obtained by using the second maximum stall torque and the maximum permissible torque.

[0194] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0195] Lock the output shaft;

[0196] The output torque of the rotor is increased incrementally until the temperature of the insulated gate bipolar transistor reaches its maximum allowable temperature, and / or the output torque reaches the maximum allowable torque, and the output torque is determined to be the maximum stall torque of the electric drive system.

[0197] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application 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 various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0198] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0199] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for protecting stall torque, characterized in that, The electric drive system includes a cooling system and a motor, and the method includes: In response to the motor being in a stalled state, the operating parameters of the electric drive system are queried; the operating parameters include the inlet temperature and inlet flow rate of the cooling system. Based on the inlet temperature and the inlet flow rate, a torque limiting factor is determined; the torque limiting factor indicates the heat dissipation rate of the cooling system. Based on the torque limitation coefficient and the predetermined maximum allowable torque, the stall torque limit is determined.

2. The stall torque protection method according to claim 1, characterized in that, The torque limiting factor includes a first torque limiting factor and / or a second torque limiting factor; The determination of the torque limiting coefficient based on the inlet temperature and the inlet flow rate includes: Determine whether the inlet temperature is within a preset temperature range and whether the inlet flow rate is within a preset flow rate range; If so, then a first torque limiting coefficient is determined based on the inlet temperature and the inlet flow rate; If not, a preset second torque limiting coefficient is obtained; wherein the second torque limiting coefficient indicates that the heat dissipation rate is 0.

3. The stall torque protection method according to claim 2, characterized in that, Determining the first torque limiting coefficient based on the inlet temperature and the inlet flow rate includes: Based on the inlet temperature and the inlet flow rate, a torque limiting coefficient mapping table is consulted to determine the corresponding first torque limiting coefficient; wherein, the torque limiting coefficient mapping table includes the first torque limiting coefficient corresponding to the inlet temperature and the inlet flow rate.

4. The stall torque protection method according to claim 3, characterized in that, The torque limiting coefficient mapping table is obtained by calibration in the following manner: Obtain multiple inlet temperatures and multiple inlet flow rates; The values ​​of the inlet temperature and the inlet flow rate are combined one by one to generate multiple pairs; Determine the maximum permissible torque; Determine the first maximum stall torque corresponding to the pairing; The first torque limit coefficient is obtained by using the first maximum stall torque and the maximum permissible torque; Based on all the pairings and their corresponding first torque limiting coefficients, a mapping table is generated for the inlet temperature, the inlet flow rate, and the first torque limiting coefficient.

5. The stall torque protection method according to claim 4, characterized in that, The electric drive system includes an output shaft and a rotor, the output shaft being connected to the rotor which is rotated to a set angle, and the set angle having at least two values. Determining the first maximum stall torque corresponding to the pairing includes: For each pairing, determine the maximum stall torque corresponding to at least two of the set angles, and select the minimum value as the first maximum stall torque; The first torque limit coefficient is obtained by using the first maximum stall torque and the maximum permissible torque.

6. The stall torque protection method according to claim 5, characterized in that, The electric drive system also includes an insulated gate bipolar transistor. For each pairing, determining the maximum stall torque corresponding to at least two set angles includes: Lock the output shaft; The output torque of the rotor is increased incrementally until the temperature of the insulated gate bipolar transistor reaches its maximum allowable temperature, and / or the output torque reaches the maximum allowable torque, and the output torque is determined to be the maximum stall torque of the electric drive system.

7. The stall torque protection method according to claim 2, characterized in that, The electric drive system includes an output shaft and a rotor, the output shaft being connected to the rotor which is rotated to a set angle, and the set angle having at least two values. The steps for obtaining the second torque limiting coefficient include: Drain the coolant from the cooling system; Adjust the ambient temperature to the set temperature and maintain it for the set time; Determine the maximum stall torque corresponding to at least two of the set angles, and take the minimum value as the second maximum stall torque; The second torque limit coefficient is obtained by using the second maximum stall torque and the maximum permissible torque.

8. A stall torque protection device, characterized in that, The electric drive system includes a cooling system and a motor, and the device includes: The cooling system parameter acquisition module queries the operating parameters of the electric drive system in response to the motor being in a stalled state; the operating parameters include the inlet temperature and inlet flow rate of the cooling system. A torque limiting coefficient acquisition module is used to determine a torque limiting coefficient based on the inlet liquid temperature and the inlet liquid flow rate; the torque limiting coefficient indicates the heat dissipation rate of the cooling system. The stall torque acquisition module is used to determine the stall torque limit based on the torque limit coefficient and the predetermined maximum allowable torque.

9. A vehicle, characterized in that, The vehicle includes the stall torque protection device as described in claim 8.

10. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the stall torque protection method according to any one of claims 1 to 7.

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