Method, device and equipment for acquiring rotating speed of motor and vehicle

Abstract

The invention discloses a method, device and equipment for acquiring the rotating speed of a motor and a vehicle, and relates to the technical field of motor control, and the method comprises the steps: determining the radius of a target wheel according to the actual rotating speed of the motor, a first vehicle speed and a first power assembly state parameter under the condition that a position sensor works normally; when it is detected that the position sensor breaks down, a second power assembly state parameter and a second vehicle speed are obtained, and the second power assembly state parameter and the second vehicle speed are data obtained when the position-sensorless control vehicle is switched in; on the basis of the second vehicle speed, the second power assembly state parameter and the target wheel radius, the corresponding initial motor rotating speed when the position-sensorless control is switched in is determined, and the problem that the vehicle stability is poor due to the fact that the motor rotating speed cannot be accurately obtained when the position sensor breaks down and the position-sensorless control is switched in is solved; and the operation stability of the vehicle is improved from the failure of the hardware position sensor to the switching of the position sensorless control.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of motor control, and particularly relates to a motor speed acquisition method and device, equipment and vehicle. BACKGROUND

[0002] At present, vehicle operation needs to be driven by a motor, and the motor needs to rely on a hardware position sensor to acquire a motor speed signal and the like, so as to perform vehicle control based on the motor speed signal.

[0003] In the related art, considering that the hardware position sensor may be abnormally failed in use, the motor speed cannot be accurately acquired, and the whole vehicle is stopped due to a fault, a position sensorless control strategy is proposed, rotor position identification is realized through a position observer, and then a motor speed signal is acquired. The position observer can enable the vehicle to acquire the motor speed signal without the hardware position sensor, so as to avoid the above-mentioned problem of whole vehicle fault stop due to hardware position sensor failure.

[0004] However, based on the actual application scenario, the hardware position sensor cannot be completely cancelled. When the hardware position sensor fails and the position sensorless control is switched in, the motor speed cannot be accurately acquired, and the stability of the vehicle when the position sensorless control is switched in is reduced. SUMMARY

[0005] The main purpose of the present application is to provide a motor speed acquisition method, device, equipment and vehicle, and to improve the running stability of the vehicle from the failure of the hardware position sensor to the switching in of the position sensorless control.

[0006] To achieve the above-mentioned purpose, the present application provides a motor speed acquisition method, comprising:

[0007] In the case that the position sensor for detecting the motor position of the vehicle is normally working, a target wheel radius is determined according to the actual motor speed, the first vehicle speed and the first powertrain state parameter;

[0008] In the case that the position sensor is detected to be faulty, a second powertrain state parameter and a second vehicle speed are acquired, the second powertrain state parameter and the second vehicle speed being data acquired when the vehicle is switched in the position sensorless control;

[0009] Based on the second vehicle speed, the second powertrain state parameter and the target wheel radius, a motor speed is determined, and the motor speed is an initial motor speed corresponding to the switching in of the position sensorless control of the vehicle.

[0010] In an embodiment, the target wheel radius is determined according to the actual motor speed, the first vehicle speed and the first powertrain state parameter, comprising:

[0011] If the first vehicle speed is greater than the preset vehicle speed, motor actual speed data corresponding to the adjacent two sliding periods is obtained;

[0012] The maximum motor actual speed and the minimum motor actual speed in the motor actual speed data are obtained, and a range between the maximum motor actual speed and the minimum motor actual speed is determined;

[0013] If the ranges corresponding to the adjacent two sliding periods are both less than a preset value, the wheel radii corresponding to the adjacent two sliding periods are determined based on the motor actual speeds obtained in the adjacent two sliding periods, the first vehicle speed, and the first power assembly state parameter;

[0014] The wheel radii corresponding to the adjacent two sliding periods are subjected to mean value calculation to obtain a target wheel radius.

[0015] In an embodiment, the first power assembly state parameter includes a first transmission gear ratio and a first main reducer gear ratio, and the wheel radii corresponding to the adjacent two sliding periods are determined based on the motor actual speeds obtained in the adjacent two sliding periods, the first vehicle speed, and the first power assembly state parameter, including:

[0016] In each sliding period, the motor actual speed, the first vehicle speed, the first transmission gear ratio corresponding to the gear in the preset sampling period, and the first main reducer gear ratio are obtained every preset sampling period, and a wheel radius calculation model is used for calculation to obtain the wheel radius corresponding to each preset sampling period;

[0017] The wheel radius corresponding to any preset sampling period is taken as the wheel radius corresponding to the corresponding sliding period, wherein each sliding period includes a plurality of preset sampling periods.

[0018] In an embodiment, after the position sensor for detecting the position of the vehicle motor is normal, the method further includes:

[0019] If the first vehicle speed is less than the preset vehicle speed, each pre-stored wheel radius is obtained;

[0020] The target wheel radius is obtained by performing mean value calculation on each pre-stored wheel radius.

[0021] In an embodiment, the method for obtaining the motor speed further includes:

[0022] The deviation between each pre-stored wheel radius and the target wheel radius is obtained;

[0023] The target pre-stored wheel radius corresponding to the minimum deviation is determined;

[0024] If the deviation corresponding to the target pre-stored wheel radius is less than a maximum deviation tolerance value, the target pre-stored wheel radius is used to update the target wheel radius.

[0025] In an embodiment, the obtaining the deviation between each of the pre-stored wheel radius and the target wheel radius comprises:

[0026] smoothing the target wheel radius;

[0027] obtaining the deviation between each of the pre-stored wheel radius and the smoothed target wheel radius.

[0028] In an embodiment, the second powertrain state parameter comprises a second transmission gear ratio and a second final drive gear ratio, and the determining the motor speed based on the second vehicle speed, the second powertrain state parameter and the target wheel radius comprises:

[0029] calculating the motor speed by using a motor speed calculation model based on the second vehicle speed, the target wheel radius, the second transmission gear ratio corresponding to the gear in which the vehicle is when the vehicle is switched into the sensorless control, and the second final drive gear ratio.

[0030] In addition, to achieve the above object, the present application further provides a motor speed obtaining device, comprising:

[0031] a first determining module configured to determine a target wheel radius based on an actual motor speed, a first vehicle speed and a first powertrain state parameter when a position sensor for detecting a position of a vehicle motor is in normal operation;

[0032] an obtaining module configured to obtain a second powertrain state parameter and a second vehicle speed when the position sensor is detected to be in failure, the second powertrain state parameter and the second vehicle speed being data obtained when the vehicle is switched into sensorless control;

[0033] a second determining module configured to determine a motor speed based on the second vehicle speed, the second powertrain state parameter and the target wheel radius, the motor speed being an initial motor speed corresponding to when the vehicle is switched into sensorless control.

[0034] In addition, to achieve the above object, the present application further provides a motor speed obtaining device, comprising: a memory, a processor and a computer program stored in the memory and executable on the processor, the computer program being configured to implement the steps of the motor speed obtaining method as above.

[0035] In addition, to achieve the above object, the present application further provides a vehicle, comprising a motor speed obtaining device, a motor and a position sensor for detecting a position of the motor; wherein the motor speed obtaining device is configured to determine an initial motor speed corresponding to when the motor is switched into sensorless control when the position sensor is detected to be in failure.

[0036] In the application, the target wheel radius is determined according to the actual motor speed, the first vehicle speed and the first power assembly state parameter when the position sensor of the vehicle motor position is normal; the data obtained when the vehicle is switched to the sensorless control is acquired when the position sensor is faulty; finally, the motor speed is determined based on the second vehicle speed, the second power assembly state parameter and the target wheel radius, and the motor speed is taken as the initial motor speed corresponding to the switching to the sensorless control. Considering that the hardware position sensor and the vehicle speed detection sensor are independent of each other and the probability of simultaneous failure is low, the motor speed can be converted by the vehicle speed detected by the vehicle speed detection sensor. During the conversion of the vehicle speed and the motor speed, the wheel radius and the power assembly state parameter need to be considered, the target wheel radius is determined when the position sensor is normal, which ensures that the system has an accurate wheel radius value after the sensor fails, and the wheel radius is an important parameter for the subsequent calculation of the vehicle speed and the motor speed. If the wheel radius is inaccurate, the calculated motor speed will be inaccurate. Therefore, by accurately determining the target wheel radius and calculating the subsequent motor speed based on the target wheel radius, the accuracy of the initial motor speed can be improved, and the stability of the vehicle when switched to the sensorless control can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0037] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate embodiments consistent with the present application and, together with the description, further serve to explain the principles of the application.

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, for those skilled in the art, other drawings can also be obtained based on these drawings without creative labor.

[0039] Figure 1 A flowchart is provided for the first embodiment of the motor speed acquisition method of the present application;

[0040] Figure 2 A flowchart is provided for the second embodiment of the motor speed acquisition method of the present application;

[0041] Figure 3 A flowchart is provided for the third embodiment of the motor speed acquisition method of the present application;

[0042] Figure 4 A module structure diagram of the motor speed acquisition device of the embodiment of the present application is provided;

[0043] Figure 5 A structure diagram of the motor speed acquisition device of the embodiment of the present application is provided.

[0044] The objectives, functional features and advantages of the present application will be further illustrated in conjunction with the embodiments, with reference to the accompanying drawings. DETAILED DESCRIPTION

[0045] It should be understood that the specific embodiments described herein are merely intended to explain the technical solutions of the present application, and are not intended to limit the present application.

[0046] At present, new energy vehicles are widely favored by terminal users due to their unique product charm and technical competitiveness. The design and application of motors and controllers are a typical complex system engineering. Permanent magnet synchronous motor and induction motor are common types of new energy vehicle driving motors, and field-oriented control is the mainstream control method for these two types of motors. Although the specific control implementation methods and emphases are significantly different, both types of motors rely on mechanical hardware position sensors such as rotary transformers, eddy current sensors, and optical encoders to obtain motor speed signals. Taking a permanent magnet synchronous motor as an example, the rotor position and speed signals are usually obtained by means of a rotary transformer. The stable and reliable operation of the rotary transformer is the guarantee of the accuracy of the motor closed-loop control. If the rotary transformer has a broken wire harness, loose connector, or other causes that cause abnormal or failure of the rotary transformer detection signal, it is likely to cause the vehicle to stop abnormally, which is contrary to the ultimate safety goal of zero safety accidents and zero unexpected breakdowns in all scenarios proposed by the new energy vehicle industry.

[0047] In order to avoid the phenomenon of vehicle failure caused by abnormal failure of the rotary transformer, there are mainly two types of problem solving ideas in the related art: optimization and upgrading of rotary transformer decoding scheme and application of position sensorless vector control strategy.

[0048] For example, in a related art, by extracting available information from the remaining valid rotary transformer signal, obtaining normal signals in the rotary transformer and realizing signal reconstruction, and using a phase-locked loop to calculate the rotor position angle, the problem of one-phase failure in two-phase signals is solved, and the robustness of the system and the accuracy of the rotor position angle calculation are improved. However, the scene adaptability involved in this related art is limited, that is: effective for the working condition of one-way recovered signal drop, difficult to run at very low speed. In another related art, a position sensorless control strategy is disclosed, which uses high-frequency injection method to realize position identification at low speed and static state, and uses position observer to realize rotor position identification at high speed, thereby realizing position sensorless control in full speed range. Not only that, although the software implementation methods are different, many disclose similar problem solving ideas as the related art.

[0049] And based on the application scene of new energy vehicles, in the background that hardware sensors cannot be completely canceled, how to realize the smooth switching from sensor failure to position sensorless control strategy, and improve the scheme adaptability of vehicle application and the stability of vehicle control, is a topic worth studying.

[0050] The existing technical problems and defects will be described in detail as follows:

[0051] The drive motor control system needs to install mechanical sensors such as rotary transformers and Hall sensors on the motor rotor shaft, which not only increases the cost of the control system and the volume of the motor, but also has problems such as complex installation, easy environmental interference, and concentricity. When the rotary transformer fault is set, it often cannot be self-recovered and needs to be tried to eliminate by executing the power-on and power-off actions, which is not convenient to operate on the vehicle.

[0052] In the process of rotary transformer fault diagnosis, if the judgment time is too long, the current control may diverge, triggering an overcurrent event and directly losing the opportunity to switch to position sensorless control. At zero speed or low speed, due to the small back electromotive force, low signal-to-noise ratio, and the influence of inverter nonlinearity and motor parameters, the position sensorless control strategy often performs high-frequency square wave injection at zero speed and low speed, and uses position observers and state estimation methods at medium and high speeds. Common methods include flux linkage observation and extended back electromotive force estimation. Considering the magnetic pole recognition process during high-frequency injection, additional execution time is inevitable. In order to ensure that the transition from rotary transformer detection signal anomaly to position sensorless control is as short as possible, the position observer or state estimation action can be kept running to quickly switch to position sensorless control when the rotary transformer signal is detected to be abnormal. However, this operation may continuously occupy chip running resources and increase the load.

[0053] If the vehicle is running at medium and high speeds, when the rotary transformer error accumulates to the count value beyond the limit and is ready to switch to position sensorless control, the position observer needs to be converged. The convergence efficiency of the position observer is related to the initial state value. At this time, if there is no reliable initial speed data, the position sensorless control may not be able to quickly correct the error, and the convergence process will be significantly slower. When the vehicle is running at low speed, reliable position and speed information can be obtained through high-frequency injection. However, due to the 180° symmetry of the motor rotor in electrical angle, the position signal obtained by high-frequency injection has multiple values and needs an additional magnetic pole recognition step. Although the vehicle speed is low at this time, if the position angle obtained by high-frequency injection jumps, and there is no reference speed to use at this time, it will be in a difficult situation where it cannot choose the appropriate fault action.

[0054] To solve this problem, it is conceivable to realize motor speed conversion through vehicle speed, because the resolver and the vehicle speed sensor are independent of each other, and the probability of failure is extremely low, so it is a feasible method to convert the driving motor speed through the vehicle speed. In addition, it has become a common practice in the industry for a new energy vehicle of the same model to provide multiple hub options, and the end user can choose according to aesthetic preferences, endurance needs, and use scenarios. At the same time, new energy vehicles usually use single-gear transmissions for speed regulation and torque matching, but because multi-gear transmissions perform better in terms of road adaptability, acceleration ability, and other aspects, multi-gear transmissions are not uncommon for mass production applications. Therefore, when converting the motor speed, the running state of the vehicle, the wheel radius, the transmission ratio, and the main reducer transmission ratio need to be considered. The present application will design a method for obtaining motor speed by considering the overall state of the vehicle, to ensure that the initial reference speed is accurate and reliable when cutting into position sensorless control, thereby improving the stability of the vehicle.

[0055] It should be noted that the method for obtaining motor speed of the present application is not limited to the field of vehicles such as new energy vehicles, but can also be applied to other fields, such as fields where the initial motor speed when cutting into position sensorless control cannot be obtained, such as compressor motor control of refrigeration equipment such as air conditioners or refrigerators.

[0056] It should be noted that the motor controller and the vehicle can exchange information through a hardware interface and a standardized communication protocol. The mainstream solutions are: CAN bus, Ethernet. Accordingly, the motor controller can obtain the gear state and vehicle speed of the transmission in real time. In the application of vehicle-mounted driving motors, stable and real-time speed and position signals can be obtained through the resolver for closed-loop control. It is generally believed that after testing, off-line testing, and other steps by the vehicle manufacturer, the vehicle-mounted hardware position sensor can operate normally for a certain period of time after the vehicle is delivered to the end user.

[0057] It should be noted that the execution subject of the present embodiment can be a computing service device with data processing, network communication, and program running functions, such as a tablet computer, a personal computer, a mobile phone, etc., or a motor speed acquisition device capable of realizing the above functions. The motor speed acquisition device will be used as an example to explain the present embodiment and the following embodiments.

[0058] It should be noted that the position sensor of the present application can be a resolver, an eddy current sensor, an optical encoder, etc.

[0059] In order to better understand the technical solutions of the present application, the following will be described in detail in conjunction with the drawings and specific embodiments.

[0060] Based on this, the present embodiment provides a method for obtaining motor speed, as shown inFigure 1 , Figure 1 Figure 1 is a flowchart of a first embodiment of the method for obtaining the motor speed of the application.

[0061] In this embodiment, the method for obtaining the motor speed comprises steps S10-S30:

[0062] Step S10, in the case that the position sensor for detecting the position of the motor of the vehicle is working normally, the target wheel radius is determined according to the actual motor speed, the first vehicle speed and the first powertrain state parameter.

[0063] The actual motor speed refers to the real rotation speed of the motor rotor, in units of r / min (revolutions per minute), which is usually measured in real time by a position sensor such as a Hall sensor or an encoder. In the fault-free state, this parameter is used for closed-loop control; when the sensor fails, it needs to be estimated by other parameters.

[0064] The first vehicle speed refers to the vehicle speed measured in real time and directly by a vehicle speed measuring device such as a wheel speed sensor or GPS when the position sensor is working normally, in units of km / h, which is used to determine the target wheel radius.

[0065] The first powertrain state parameter refers to the powertrain operating parameters obtained in real time when the position sensor is normal, including transmission gear ratio, main reducer gear ratio, etc., which are used for subsequent calculation of the target wheel radius.

[0066] The target wheel radius refers to the rolling radius of the vehicle tire (unit: mm), which is the distance from the contact point of the tire with the ground to the center of the wheel shaft, which needs to be pre-set or calculated in real time or corrected according to different vehicle driving states, and is used to convert the vehicle speed into the motor speed.

[0067] In a feasible implementation, the target wheel radius can be determined in real time according to the actual motor speed, the first vehicle speed and the first powertrain state parameter when the position sensor for detecting the position of the motor of the vehicle is working normally. Alternatively, the actual motor speed, the first vehicle speed and the first powertrain state parameter can be obtained every pre-set sliding period when the position sensor for detecting the position of the motor of the vehicle is working normally, the wheel radius is determined, and the wheel radius calculated in each pre-set sliding period is stored, and the target wheel radius is obtained by averaging the wheel radius calculated in each pre-set sliding period in the case that the position sensor fails. In this way, the problem of inaccurate calculation of the target wheel radius caused by fluctuation of the data in a sliding period can be avoided.

[0068] In another possible implementation, a correspondence relationship between the actual motor speed, the first vehicle speed, the first power assembly state parameter, and the target wheel radius can be pre-established. In actual application, the target wheel radius can be obtained by searching the correspondence relationship according to the actual motor speed, the first vehicle speed, and the first power assembly state parameter, thereby improving the efficiency of obtaining the target wheel radius.

[0069] In step S20, the second power assembly state parameter and the second vehicle speed are obtained in the case of detecting the position sensor fault. The second power assembly state parameter is the data obtained when the vehicle is switched to the position sensorless control mode.

[0070] The second power assembly state parameter refers to the real-time obtained power assembly parameter such as the transmission gear ratio and the main reducer gear ratio at the fault moment when the position sensor fails and the position sensorless control mode is switched. The parameter is used as the initial input to ensure the continuity of the control mode switching.

[0071] The second vehicle speed refers to the vehicle speed obtained when the position sensor fails. The parameter is used for the speed calculation in the fault state.

[0072] In a possible implementation, the detection of whether the position sensor fails can be as follows: if the position sensor is a resolver, when the resolver fails, the resolver error count value usually increases rapidly. The resolver error count value in a preset time period can be detected to determine whether the resolver fails. Specifically, if the resolver error count value in the preset time period is greater than a preset increase, it is determined that the resolver fails. The failure detection methods of other position sensors such as the eddy current sensor and the optical encoder are similar, and are not described herein.

[0073] In another possible implementation, the second vehicle speed can be estimated by integrating the accelerometer of the inertial measurement unit.

[0074] In step S30, the motor speed is determined based on the second vehicle speed, the second power assembly state parameter, and the target wheel radius. The motor speed is used as the initial motor speed corresponding to the switching to the position sensorless control vehicle.

[0075] The motor speed refers to the initial motor speed calculated based on the vehicle speed, the wheel radius, and the power assembly parameter in the position sensorless control mode, which is used to start the position sensorless control algorithm such as the high-frequency injection method or the observer model, and is used as the initial motor speed of the position sensorless control algorithm to ensure the stability of the vehicle. The obtained initial motor speed can meet the needs of the motor speed reference and the state monitoring and diagnosis when the position sensorless control is switched and the vehicle is normally operated.

[0076] In a feasible implementation, the second power assembly state parameter and the second vehicle speed can be acquired at the moment of cutting into the vehicle without the position sensor control, and the target wheel radius calculated when the position sensor is in normal operation is acquired, and the motor speed is determined according to the second vehicle speed, the second power assembly state parameter and the target wheel radius.

[0077] In another feasible implementation, a corresponding relationship between the second vehicle speed, the second power assembly state parameter, the target wheel radius and the motor speed can be constructed in advance, and in actual application, the motor speed is obtained by looking up the corresponding relationship according to the acquired second vehicle speed, second power assembly state parameter and target wheel radius, so as to improve the acquisition efficiency of the motor speed.

[0078] It should be noted that the calculated motor speed can be used as the initial motor speed corresponding to the moment of cutting into the vehicle without the position sensor control, so that the control of the position sensor can be smoothly cut in, thereby avoiding the phenomenon of vehicle instability caused by the failure to acquire the motor speed at the moment of cutting into the vehicle without the position sensor control.

[0079] In the embodiment, the target wheel radius is determined according to the actual motor speed, the first vehicle speed and the first power assembly state parameter when the position sensor of the vehicle motor position is in normal operation, the data acquired at the moment of cutting into the vehicle without the position sensor control is acquired when the position sensor fails, and finally the motor speed is determined based on the second vehicle speed, the second power assembly state parameter and the target wheel radius, and the motor speed is used as the initial motor speed corresponding to the moment of cutting into the vehicle without the position sensor control. Considering that the hardware position sensor and the vehicle speed detection sensor are independent of each other and the probability of simultaneous failure is low, the motor speed can be converted by the vehicle speed detected by the vehicle speed detection sensor. In the conversion process of the vehicle speed and the motor speed, the wheel radius and the power assembly state parameter need to be considered, and the target wheel radius is determined when the position sensor is in normal operation, which ensures that the system has an accurate target wheel radius after the sensor fails. The accurate target wheel radius is an important parameter for subsequent calculation of the vehicle speed and the motor speed. If the target wheel radius is inaccurate, the calculated motor speed will be inaccurate. Therefore, by accurately determining the target wheel radius and calculating the subsequent motor speed based on the target wheel radius, the accuracy of the initial motor speed can be improved, and the stability of the vehicle when cutting into the vehicle without the position sensor control can be improved.

[0080] Based on the first embodiment of the present application, in the second embodiment of the present application, the same or similar contents as the above embodiments can be referred to the above introduction, and the subsequent will not be described. On this basis, the effective rolling radius of the wheel under the drive of the motor is not fixed. It is closely related to the current slip ratio. The slip ratio represents the difference between the linear speed of the wheel and the actual forward speed of the vehicle. When the driver steps on the accelerator or the torque demand increases sharply, the motor speed will rise sharply. The tire will undergo significant elastic deformation in response to the huge driving torque, and will need more slip to overcome inertia to accelerate the vehicle. This will cause the instantaneous drive radius to increase significantly. When the driver quickly releases the accelerator or steps on the brake, the motor torque will decrease sharply or even become negative. The tire ground part will be deformed in the opposite direction due to the deceleration force, and the slip mode will change, which may cause the drive radius to be temporarily smaller or unstable. If the data at a single time point during the sudden acceleration / deceleration process is extracted to calculate the radius, a radius value that fluctuates sharply and cannot reflect the characteristics of the tire in a stable state will be obtained. Therefore, on the basis of the above embodiment, in view of the preset sampling period of the whole vehicle and the motor controller is usually 5ms-10ms, and the motor speed does not change greatly within a few seconds, it is considered that the target wheel radius calculated within this period of time is reliable, and the target wheel radius calculated can be used to participate in the calculation of the initial motor speed in the subsequent position sensorless. How to determine whether the target wheel radius calculated within this period of time is reliable can refer to the first embodiment of the present application. Figure 2 That is, step S10 comprises:

[0081] Step S11, if the first vehicle speed is greater than the preset vehicle speed, the actual motor speed data corresponding to the adjacent two slip periods is obtained.

[0082] Wherein, the preset vehicle speed refers to a preset vehicle speed determination threshold, which can be set to 10km / h, for example. By comparing the preset vehicle speed with the first vehicle speed, the current running state of the vehicle can be determined. For example, if the first vehicle speed is greater than the preset vehicle speed, it indicates that the vehicle is in a stable driving state. If the first vehicle speed is less than the preset vehicle speed, it indicates that the wheel is in a creeping state, and at this time the vehicle is shaking seriously, which will make the calculated target wheel radius inaccurate. Therefore, during stable driving of the vehicle, the related steps of the embodiment are executed.

[0083] Wherein, the slip period refers to a dynamically updated time window for real-time acquisition of motor speed data. The window length of the slip period can be set to 3s. In the slip period, the actual motor speed can be acquired every 5ms or 10ms, and the actual motor speed acquired each time is sorted and combined according to time, so as to obtain the actual motor speed data of the slip period. The actual motor speed corresponding to the adjacent two slip periods is obtained for subsequent analysis and determination of the target wheel radius.

[0084] In a feasible implementation, in the case that the position sensor for detecting the position of the motor of the vehicle is in normal operation, it is detected whether the first vehicle speed acquired in real time is greater than a preset vehicle speed, and if it is detected that the first vehicle speed is greater than the preset vehicle speed, a communication connection is established with the position sensor, the actual motor speed uploaded by the position sensor is acquired in real time, and the purpose of acquiring the actual motor speed data of the current sliding period is achieved, for example, the actual motor speed is acquired in a sliding period of 3s to obtain the actual motor speed data.

[0085] In another feasible implementation, the actual motor speed of the current sliding period can also be that the position sensor uploads and stores the acquired actual motor speed to the vehicle T-BOX in real time, and the acquisition device of the motor speed detects the case that the first vehicle speed is greater than the preset vehicle speed, and sends a motor speed acquisition instruction to the vehicle T-BOX, so that the vehicle T-BOX uploads the acquired actual motor speed to the acquisition device of the motor speed after receiving the instruction, thereby achieving the purpose of acquiring the actual motor speed data of the current sliding period, and storing the actual motor speed through the vehicle T-BOX, which facilitates the management of the actual motor speed data.

[0086] Step S12, the maximum actual motor speed and the minimum actual motor speed in the actual motor speed data are acquired, and the range between the maximum actual motor speed and the minimum actual motor speed is determined.

[0087] It should be noted that since the actual motor speed data of the sliding period is essentially a time sequence of the actual motor speed sorted by time, the actual motor speed acquired each time in the actual motor speed data of the sliding period can be compared, the maximum actual motor speed and the minimum actual motor speed are obtained, and the maximum actual motor speed is subtracted from the minimum actual motor speed to obtain the range between the maximum actual motor speed and the minimum actual motor speed. By determining the range between the maximum actual motor speed and the minimum actual motor speed, subsequent analysis is facilitated. The corresponding range can be determined based on the acquired actual motor speed data of each sliding period, that is, each sliding period corresponds to a range.

[0088] Step S13, if the ranges corresponding to the adjacent two sliding periods are both less than a preset value, the wheel radii corresponding to the adjacent two sliding periods are determined based on the actual motor speed, the first vehicle speed and the first powertrain state parameter acquired in the adjacent two sliding periods.

[0089] The preset value can be set according to the actual situation, for example, it can be calibrated according to the tire characteristics such as tire pressure and wear.

[0090] Each sliding period outputs a wheel radius, which can be used for subsequent determination of the target wheel radius.

[0091] It should be noted that when the range is less than the preset value, it indicates that the actual motor speed in the sliding period is small or almost no fluctuation, indicating that the motor speed changes very gently, without dramatic mutations. The change of the speed means that the change of the driving torque is also relatively gentle. The change of the driving torque means that the change of the tire force is gentle. The change of the tire force means that the elastic deformation of the tire, the stress distribution of the contact area and the slip ratio are relatively stable in a small range. Therefore, in the time window of the relatively stable slip state, the driving radius is relatively stable, or its change is regular and predictable. By setting the range less than the preset value, the most unstable data points and the dramatic transient stage at the beginning of the acceleration or deceleration process can be effectively filtered out, and the accuracy of the subsequent target wheel radius calculation result is improved.

[0092] In addition, considering that the motor speed data obtained by using one sliding period may have error risk in calculating the target wheel radius, for example, the actual motor speed obtained by using a certain sliding period is relatively stable, which may be an accidental phenomenon. Therefore, in order to improve the accuracy of the target wheel radius calculation result, the ranges corresponding to the adjacent two sliding periods can be compared with the preset value respectively. If the ranges corresponding to the adjacent two sliding periods are both less than the preset value, it can be determined that the current is a stable vehicle slip state and the stable vehicle slip state lasts at least for a period of time, avoiding the inaccuracy of the target wheel radius calculation result caused by active acceleration or deceleration, and further improving the accuracy of the target wheel radius calculation result.

[0093] In step S14, the mean value of the wheel radii corresponding to the adjacent two sliding periods is calculated to obtain the target wheel radius.

[0094] For example, assuming that there are two adjacent sliding periods, a first sliding period and a second sliding period, the wheel radius corresponding to the first sliding period is determined according to the actual motor speed, the first vehicle speed and the first powertrain state parameter obtained by the first sliding period. The wheel radius corresponding to the second sliding period is determined according to the actual motor speed, the first vehicle speed and the first powertrain state parameter obtained by the second sliding period. Finally, the wheel radii corresponding to the first sliding period and the second sliding period are summed and averaged to obtain the target wheel radius.

[0095] It should be noted that the above sliding period is not limited to 3s, but can be other sliding window length, and the window length of the sliding period can be set according to the actual situation.

[0096] It should be noted that in the case of normal operation of the position sensor for detecting the position of the vehicle motor, after the target wheel radius required is calculated in a certain slip period, the target wheel radius can be stored for subsequent use, and the repeated calculation of the target wheel radius can be stopped at this time, thereby reducing the calculation resources of the motor speed acquisition device.

[0097] In this embodiment, in the case of normal operation of the position sensor for detecting the position of the vehicle motor, it is detected that the first vehicle speed is greater than the preset vehicle speed, indicating that the vehicle is in a driving state, at this time, the actual motor speed data corresponding to the adjacent two slip periods is obtained, and the difference between the maximum motor actual speed and the minimum motor actual speed is judged to be greater than the preset value, indicating that the motor speed has a sharp mutation, and if the difference corresponding to the adjacent two slip periods is less than the preset value, it indicates that the motor speed changes very gently and has no sharp mutation, so as to judge the fluctuation of the motor speed, and the mean value of the wheel radius corresponding to each slip period is calculated to obtain the target wheel radius, thereby improving the accuracy of the calculation result of the target wheel radius.

[0098] Further, the first powertrain state parameter includes a first transmission gear ratio and a first main reducer gear ratio, wherein the transmission gear ratio is a key parameter for measuring the power transmission efficiency of the vehicle, which represents the speed ratio relationship between the input shaft and the output shaft of the transmission, if the transmission gear ratio is greater than 1, it indicates a speed reduction transmission, if it is less than 1, it indicates a speed increasing transmission, and if it is equal to 1, it indicates an equal speed transmission. The main reducer gear ratio refers to the gear ratio of the main reducer in the automobile drive axle, which is equal to the ratio of the rotational angular velocity of the transmission shaft to the rotational angular velocity of the axle half shaft, and also equal to the ratio of their rotational speeds.

[0099] Since it has become a common practice in the industry for new energy vehicles of the same model to provide multiple hub options, terminal users can choose according to their aesthetic preferences, endurance needs, and use scenarios. At the same time, new energy vehicles usually use single-gear transmissions for speed regulation and torque matching, but multi-gear transmissions perform better in terms of road adaptability and acceleration ability, and multi-gear transmissions have been widely used in vehicle production. Therefore, when calculating the motor speed, the running state of the vehicle, the wheel radius, the transmission gear ratio, and the main reducer gear ratio need to be considered. When calculating the wheel radius, the transmission gear ratio and the main reducer gear ratio need to be considered. Specifically, step S13 includes:

[0100] Step S131, in each slip period, the actual motor speed, the first vehicle speed, the first transmission gear ratio corresponding to the gear of the preset sampling period, and the first main reducer gear ratio are obtained every preset sampling period, and a wheel radius calculation model is used to calculate the wheel radius corresponding to each preset sampling period.

[0101] The preset sampling period of the whole vehicle and the motor controller is usually 5-10 ms, so the preset sampling period here can be set to 5-10 ms, for example, the actual motor speed, the first vehicle speed, the first transmission ratio corresponding to the gear at the preset sampling period, and the first main reducer transmission ratio are obtained every 5 ms.

[0102] The gears corresponding to different preset sampling periods can be different.

[0103] In the case that the position sensor for detecting the position of the vehicle motor is working normally, the actual motor speed N is obtained using the position sensor, and the data of the wheel radius R_Normal used by the whole vehicle is calculated according to the gear state of the whole vehicle, considering the time i, the wheel radius calculation model is as follows:

[0104] R_Normal(i)=V(i)*(25 / (3*pi*N(i)))*M(i)*L(i) (1)

[0105] In formula (1), V(i) is the first vehicle speed at time i, N(i) is the actual motor speed at time i, M(i) and L(i) are the transmission ratio and the main reducer transmission ratio corresponding to the gear at time i.

[0106] From the above formula (1), it can be seen that the result of formula (1) is mainly affected by the actual motor speed, the vehicle speed, and the transmission ratio. The driving motor of the new energy vehicle realizes torque increase and speed reduction or torque reduction and speed increase through gear shifting of the transmission, and transmits power to the wheel. Therefore, the motor speed and the vehicle speed have similar influence on the calculation result of formula (1). Subsequently, when the position sensorless control is cut in, the initial motor speed can be inferred according to the obtained vehicle speed.

[0107] In step S132, the wheel radius corresponding to any one preset sampling period is taken as the wheel radius corresponding to the corresponding sliding period, wherein each sliding period includes a plurality of preset sampling periods.

[0108] From the above steps, it can be seen that since each sliding period includes a plurality of preset sampling periods, the wheel radius is calculated once for each preset sampling period. For example, the wheel radius corresponding to the last preset sampling period in each sliding period can be taken as the wheel radius corresponding to the sliding period, or the wheel radii calculated by each preset sampling period in a certain sliding period can be averaged to obtain the wheel radius corresponding to the sliding period.

[0109] It should be noted that the calculation method of the wheel radius in each preset sampling period can be calculated by the above formula (1), which will not be described here.

[0110] In the embodiment, compared with the related art which uses fixed parameters for wheel radius calculation, the wheel radius calculation model is set to calculate the actual motor speed, the first vehicle speed, the first transmission ratio and the first main reducer transmission ratio obtained each time in the current sliding period, so as to realize real-time acquisition of the wheel radius.

[0111] Further, after the position sensor for detecting the position of the vehicle motor is normal, it further includes: if the first vehicle speed is less than the preset vehicle speed, obtaining each pre-stored wheel radius; performing mean calculation on each pre-stored wheel radius to obtain a target wheel radius.

[0112] It should be noted that if the position sensor is normal, if the first vehicle speed is always less than the preset vehicle speed during vehicle driving, the pre-stored and default wheel radius can be used as the target wheel radius for subsequent motor speed calculation at this time, and these default wheel radii can be set by default when the vehicle is manufactured, so as to realize the determination of the initial motor speed in this working condition. The mean calculation can be performed on each pre-stored wheel radius to obtain a target wheel radius.

[0113] In the embodiment, the mean calculation is performed on each pre-stored wheel radius to obtain a target wheel radius, so that the determination of the target wheel radius can be realized even if the first vehicle speed is less than the preset vehicle speed, and the conditions for determining the initial speed in subsequent position sensorless control are provided.

[0114] Based on the above embodiments of the application, in the third embodiment of the application, the same or similar contents as the above embodiments can be referred to the above introduction, and will not be described in detail. On this basis, since it has become an industry norm to provide multiple hub options for the same vehicle model, terminal users can choose according to aesthetic preference, endurance demand and use scenario, that is, the same vehicle model may have different sizes of wheel radius, and these wheel radii can be pre-stored when the vehicle is manufactured, that is, the pre-stored wheel radius in the following.

[0115] Since the same vehicle model may have different sizes of wheel radius, it is impossible to determine which size of wheel radius is used for motor speed calculation, so it is necessary to compare the target wheel radius calculated by the above embodiment with the pre-stored wheel radius to determine the most suitable wheel radius for motor speed calculation, so as to meet the accurate acquisition of motor speed in the multi-size wheel radius scenario. Please refer to Figure 3 After step S10, it further includes:

[0116] Step S210, obtaining the deviation between each pre-stored wheel radius and the target wheel radius.

[0117] Step S220, determining the target pre-stored wheel radius corresponding to the minimum deviation.

[0118] Step S230, if the deviation corresponding to the target pre-stored wheel radius is less than the maximum deviation allowable value, the target wheel radius is updated by using the target pre-stored wheel radius.

[0119] The maximum deviation allowable value can be set according to actual conditions, for example, it can be set to 2 cm. The closer the deviation corresponding to the target pre-stored wheel radius is to the maximum deviation allowable value, the closer the calculated target wheel radius is to the target pre-stored wheel radius, otherwise, the calculated target wheel radius is far from the target pre-stored wheel radius.

[0120] For example, assuming that the target wheel radius is 30 cm, there are three pre-stored wheel radii in the motor controller, which are 31 cm, 32 cm and 36 cm. The difference between the target wheel radius and each pre-stored wheel radius can be calculated, which is 1 cm, 2 cm and 6 cm respectively. The target wheel radius corresponding to the minimum deviation is 31 cm, which is the target pre-stored wheel radius. Since the deviation corresponding to the target pre-stored wheel radius is 1 cm, which is less than the maximum deviation allowable value of 2 cm, the target pre-stored wheel radius of 31 cm can be used as the target wheel radius.

[0121] It should be noted that if there is no target pre-stored wheel radius corresponding to the deviation less than the maximum deviation allowable value, the average value of all pre-stored wheel radii can be calculated to obtain the target pre-stored wheel radius, and the target pre-stored wheel radius is used to update the target wheel radius, so that even if the calculated wheel radius is far from the pre-stored wheel radius, the determination of the target wheel radius can be realized, and the determination of the motor speed when cutting into the position sensorless control can be ensured.

[0122] In this embodiment, the calculated target wheel radius is compared with the pre-stored wheel radius to determine the most suitable wheel radius to participate in the calculation of the motor speed, so as to determine the target wheel radius in the multi-size wheel radius scene, and further improve the accuracy of the motor speed.

[0123] Further, step S210 includes:

[0124] Step S211, smoothing the target wheel radius.

[0125] In an embodiment, the target wheel radius can be smoothed by using the following formula:

[0126] R_out=a*R_Cal+(1-a)R_out_Late.

[0127] Wherein, the smoothing processing mode is to eliminate instantaneous fluctuation by using a first-order low-pass filter, wherein the value of a determines the weight of old and new data, and the interval is usually set to 0-1, R_out_Late represents the target wheel radius after the last smoothing processing, R_out represents the target wheel radius after the current smoothing processing, and R_Cal represents the target wheel radius calculated this time.

[0128] In step S212, the deviation between each pre-stored wheel radius and the target wheel radius after smoothing processing is obtained.

[0129] It should be noted that the specific way of obtaining the deviation between each pre-stored wheel radius and the target wheel radius after smoothing processing is similar to step S210, and specific reference can be made to the above steps, which will not be repeated here.

[0130] In this embodiment, the target wheel radius is smoothed, and then the deviation between each pre-stored wheel radius and the target wheel radius after smoothing processing is obtained; the target pre-stored wheel radius corresponding to the minimum deviation is determined; if the deviation corresponding to the target pre-stored wheel radius is less than the maximum deviation tolerance, the target pre-stored wheel radius is used to update the target wheel radius. In this way, the instantaneous radius fluctuation caused by road bumps, skidding and the like can be eliminated, and the accuracy of the obtained target wheel radius can be improved.

[0131] Further, the second powertrain state parameter includes a second transmission gear ratio and a second main reducer gear ratio, and step S30 includes:

[0132] In step S31, the motor speed is calculated by using a motor speed calculation model according to the second vehicle speed, the target wheel radius, the second transmission gear ratio corresponding to the gear position when the vehicle is switched to the position sensorless control, and the second main reducer gear ratio.

[0133] When the position sensor fails, the motor speed signal obtained at this time is not available, and the motor speed data before the fault cannot be directly stored and reserved as the motor speed when the position sensorless control is switched in. After the accurate target wheel radius is obtained by the above-mentioned method, the motor speed can be calculated by using the following motor speed calculation model:

[0134] N_start = V * (25 / (3 * pi * R_Normal)) * M * L (2)

[0135] In formula (2), N_start is the initial motor speed when the position sensorless control is started, R_Normal is the target wheel radius calculated above, M is the transmission ratio at the time when the position sensorless control is started, L is the main reducer transmission ratio, V is the vehicle speed at the time when the position sensorless control is started, and pi is π.

[0136] In this embodiment, compared with the related art which uses a pre-stored and fixed wheel radius to calculate the motor speed, the target wheel radius is accurately calculated, and the motor speed calculation model mentioned in formula (2) is used to calculate the motor speed, thereby improving the accuracy of the motor speed at the time when the position sensorless control is started and ensuring the stability of the vehicle at the time when the position sensorless control is started.

[0137] It can be understood that after the initial motor speed is obtained, the initial motor speed and the motor speed obtained by the high-frequency injection or the position observer can be used for data verification during the position sensorless control in the full-speed section. If the difference between the initial motor speed obtained by the high-frequency injection or the position observer deviates beyond a certain range, corresponding fault warning or motor torque capacity limitation can be performed according to the size of the difference.

[0138] Specifically, during the low-speed driving of the vehicle, a first motor speed corresponding to the high-frequency injection is obtained, a first deviation between the first motor speed and the initial motor speed is determined, and a fault control action corresponding to the first deviation is performed. When the high-frequency injection strategy is used in the low-speed section, even if the position angle estimation deviation is too large to cause the vehicle to be unable to run, the initial motor speed can be used to select a reasonable fault action.

[0139] During the high-speed driving of the vehicle, a second motor speed observed by the position observer is obtained, a second deviation between the second motor speed and the initial motor speed is determined, a motor torque capacity corresponding to the second deviation is determined, and the motor is limited based on the motor torque capacity. When the position observer strategy is used in the high-speed section, the initial motor speed can be used to help the position observer to quickly correct errors and stabilize convergence.

[0140] It should be noted that the above examples are only used for understanding the present application and do not limit the method for obtaining the motor speed of the present application. More simple transformations based on the technical concept are within the protection scope of the present application.

[0141] Based on the same inventive concept, the present application also provides a device for obtaining a motor speed, which is described in detail in the Figure 4 , and includes:

[0142] The first determining module 10 is configured to determine a target wheel radius according to the actual motor speed, the first vehicle speed, and the first powertrain state parameter when the position sensor for detecting the motor position is normal.

[0143] The acquisition module 20 is configured to acquire a second powertrain state parameter and a second vehicle speed when the position sensor is detected to be faulty, the second powertrain state parameter and the second vehicle speed being data acquired when the vehicle is switched to the position sensorless control.

[0144] The second determining module 30 is configured to determine a motor speed based on the second vehicle speed, the second powertrain state parameter, and the target wheel radius, the motor speed being an initial motor speed corresponding to the switching to the position sensorless control.

[0145] Optionally, the first determining module 10 is further configured to: acquire actual motor speed data corresponding to adjacent two sliding periods if the first vehicle speed is greater than a preset vehicle speed; acquire a maximum actual motor speed and a minimum actual motor speed in the actual motor speed data, and determine a range between the maximum actual motor speed and the minimum actual motor speed; determine wheel radii corresponding to the adjacent two sliding periods based on the actual motor speed, the first vehicle speed, and the first powertrain state parameter acquired in the adjacent two sliding periods if the range corresponding to the adjacent two sliding periods is less than a preset value; and perform mean value calculation on the wheel radii corresponding to the adjacent two sliding periods to obtain the target wheel radius.

[0146] Optionally, the first powertrain state parameter includes a first transmission gear ratio and a first main reducer gear ratio, and the first determining module 10 is further configured to: acquire the actual motor speed, the first vehicle speed, the first transmission gear ratio corresponding to a gear in each preset sampling period, and the first main reducer gear ratio in each sliding period at every preset sampling period, and perform calculation by using a wheel radius calculation model to obtain a wheel radius corresponding to each preset sampling period; and take the wheel radius corresponding to any preset sampling period as the wheel radius corresponding to the corresponding sliding period, wherein each sliding period includes a plurality of preset sampling periods.

[0147] Optionally, the first determining module 10 is further configured to: acquire each pre-stored wheel radius if the first vehicle speed is less than the preset vehicle speed; and perform mean value calculation on the each pre-stored wheel radius to obtain the target wheel radius.

[0148] Optionally, the first determining module 10 is further configured to: acquire a deviation between each pre-stored wheel radius and the target wheel radius; determine a target pre-stored wheel radius corresponding to a minimum deviation; and update the target wheel radius by using the target pre-stored wheel radius if a deviation corresponding to the target pre-stored wheel radius is less than a maximum deviation tolerance.

[0149] Optionally, the first determining module 10 is further configured to: perform smoothing processing on the target wheel radius; and obtain a deviation between each pre-stored wheel radius and the target wheel radius after the smoothing processing.

[0150] Optionally, the second powertrain state parameter includes a second transmission gear ratio and a second main reducer gear ratio, and the second determining module 30 is further configured to: calculate the motor speed by using a motor speed calculation model according to the second vehicle speed, the target wheel radius, the second transmission gear ratio corresponding to the gear in which the vehicle is located when the vehicle is switched to the no position sensor control, and the second main reducer gear ratio.

[0151] The motor speed acquisition device provided in the application can improve the running stability of the vehicle from the occurrence of the hardware position sensor failure to the switching to the no position sensor control, by using the motor speed acquisition method in the above embodiments. Compared with the prior art, the motor speed acquisition device provided in the application has the same beneficial effects as the motor speed acquisition method provided in the above embodiments, and other technical features in the motor speed acquisition device are the same as the features disclosed in the above embodiments, which will not be repeated here.

[0152] Based on the same inventive concept, the application provides a motor speed acquisition device, which includes: at least one processor; and a memory in communication connection with the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the motor speed acquisition method in the above embodiments.

[0153] Reference will be made to the following description Figure 5 which shows a structural schematic diagram of a motor speed acquisition device suitable for being used to implement the embodiments of the application. The motor speed acquisition device in the embodiments of the application can include, but is not limited to, mobile terminals such as mobile phones, notebook computers, digital broadcast receivers, personal digital assistants (PDA), tablet computers (PAD), portable media players (PMP), vehicle-mounted terminals (for example, vehicle-mounted navigation terminals), and the like, and fixed terminals such as digital TVs, desktop computers, and the like. Figure 5 The motor speed acquisition device shown is only an example, and should not bring any limitation to the functions and use range of the embodiments of the application.

[0154] As Figure 5As shown, the motor speed acquisition device can include a processing device 1001 (e.g., a central processing unit, a graphics processing unit, etc.) that can perform various appropriate actions and processes according to programs stored in a read-only memory (ROM) 1002 or loaded from a storage device 1003 into a random access memory (RAM) 1004. Various programs and data required for operation of the motor speed acquisition device are also stored in the random access memory 1004. The processing device 1001, the read-only memory 1002, and the random access memory 1004 are connected to each other by a bus 1005. An input / output (I / O) interface 1006 is also connected to the bus. Generally, the following systems can be connected to the I / O interface 1006: input devices 1007 including, for example, a touch screen, a touch pad, a keyboard, a mouse, an image sensor, a microphone, an accelerometer, a gyroscope, etc.; output devices 1008 including, for example, a liquid crystal display (LCD), a speaker, a vibrator, etc.; the storage device 1003 including, for example, a magnetic tape, a hard disk, etc.; and a communication device 1009. The communication device 1009 can allow the motor speed acquisition device to communicate with other devices wirelessly or by wire to exchange data. Although the motor speed acquisition device with various systems is shown in the figure, it should be understood that all the shown systems are not required to be implemented or possessed. More or fewer systems can be alternatively implemented or possessed.

[0155] In particular, according to embodiments of the present disclosure, the processes described above with reference to the flowcharts can be implemented as a computer software program. For example, embodiments of the present disclosure include a computer program product comprising a computer program carried on a computer readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network by a communication device, or installed from the storage device 1003, or installed from the read-only memory 1002. When the computer program is executed by the processing device 1001, the above-mentioned functions defined in the methods of the embodiments of the present disclosure are performed.

[0156] The motor speed acquisition device provided by the present application adopts the motor speed acquisition method in the above-mentioned embodiments, which can improve the running stability of the vehicle from the occurrence of hardware position sensor failure to the cutting into the position sensorless control. Compared with the prior art, the motor speed acquisition device provided by the present application has the same beneficial effects as the motor speed acquisition method provided by the above-mentioned embodiments, and other technical features in the motor speed acquisition device are the same as the features disclosed in the previous embodiment method, which will not be repeated here.

[0157] Based on the same inventive concept, the application further provides a vehicle, comprising a motor speed acquisition device, a motor, and a position sensor for detecting the position of the motor, wherein the motor speed acquisition device is configured to determine an initial motor speed corresponding to the situation of switching in the position observerless control motor when the position sensor fails.

[0158] The position sensor described above can be a resolver, an eddy current sensor, or an optical encoder.

[0159] The vehicle provided by the application can improve the running stability of the vehicle from the failure of the hardware position sensor to the switching in of the position observerless control motor. Compared with the prior art, the vehicle provided by the application has the same beneficial effects as the motor speed acquisition method provided by the above-described embodiments, and thus will not be described herein.

[0160] The above is only some embodiments of the application, and does not limit the patent scope of the application. Any equivalent structural transformation made by using the content of the specification and drawings, or direct / indirect application in other related technical fields is included in the patent protection scope of the application.

Claims

1. A method for obtaining motor speed, characterized in that: include: When a position sensor for detecting a position of a motor of the vehicle is operating normally, determining a target wheel radius according to an actual motor speed, a first vehicle speed, and a first powertrain state parameter; When a position sensor failure is detected, obtaining a second powertrain state parameter and a second vehicle speed, wherein the second powertrain state parameter and the second vehicle speed are data obtained when the vehicle is switched into position sensorless control; Based on the second vehicle speed, the second powertrain state parameter, and the target wheel radius, a motor speed is determined, and the motor speed serves as an initial motor speed corresponding to the switching into position sensorless vehicle control.

2. The method for obtaining the motor speed according to claim 1, wherein: Determining the target wheel radius according to the actual motor speed, the first vehicle speed, and the first powertrain state parameter includes: If the first vehicle speed is greater than a preset vehicle speed, obtaining actual motor speed data corresponding to two adjacent sliding periods; Obtaining a maximum motor actual speed and a minimum motor actual speed in the motor actual speed data, and determining a range difference between the maximum motor actual speed and the minimum motor actual speed; If the ranges corresponding to two adjacent sliding periods are both smaller than a preset value, determining the wheel radii corresponding to the two adjacent sliding periods based on the actual motor speeds, the first vehicle speed, and the first powertrain state parameter obtained during the two adjacent sliding periods; The target wheel radius is obtained by calculating the average of the wheel radii corresponding to two adjacent sliding periods.

3. The method for obtaining the motor speed according to claim 2, wherein: The first powertrain state parameter includes a first transmission gear ratio and a first final reducer gear ratio. Determining the wheel radius corresponding to two adjacent sliding periods based on the actual motor speed, the first vehicle speed, and the first powertrain state parameter obtained during the two adjacent sliding periods includes: In each sliding period, the actual motor speed, the first vehicle speed, the first transmission ratio corresponding to the gear position in the preset sampling period, and the first final drive ratio are obtained at every preset sampling period, and the wheel radius corresponding to each preset sampling period is calculated using a wheel radius calculation model; The wheel radius corresponding to any preset sampling period is used as the wheel radius corresponding to the corresponding sliding period, wherein each sliding period includes a plurality of preset sampling periods.

4. The method for obtaining the motor speed according to claim 1, wherein: After the position sensor for detecting the position of the vehicle motor works normally, the method further includes: If the first vehicle speed is less than a preset vehicle speed, obtaining each pre-stored wheel radius; The target wheel radius is obtained by performing mean calculation on each of the pre-stored wheel radii.

5. The method for obtaining the motor speed according to any one of claims 1 to 4, characterized in that: The method for obtaining the motor speed further includes: Obtaining deviations between each pre-stored wheel radius and the target wheel radius; Determine the target pre-stored wheel radius corresponding to the minimum deviation; If the deviation corresponding to the target pre-stored wheel radius is less than a maximum deviation allowable value, the target pre-stored wheel radius is used to update the target wheel radius.

6. The method for obtaining the motor speed according to claim 5, wherein: The obtaining of the deviations between the respective pre-stored wheel radii and the target wheel radius comprises: performing smoothing processing on the target wheel radius; Obtain deviations between each of the pre-stored wheel radii and the target wheel radius after smoothing.

7. The method for obtaining the motor speed according to claim 5, wherein: The second powertrain state parameter includes a second transmission gear ratio and a second final reducer gear ratio. Determining the motor speed based on the second vehicle speed, the second powertrain state parameter, and the target wheel radius includes: The motor speed is obtained by calculating the motor speed using a motor speed calculation model according to the second vehicle speed, the target wheel radius, the second transmission ratio corresponding to the gear position when the vehicle is in position sensorless control, and the second final reducer ratio.

8. A device for obtaining motor speed, characterized in that: The motor speed acquisition device includes: a first determining module, configured to determine a target wheel radius based on an actual motor speed, a first vehicle speed, and a first powertrain state parameter, when a position sensor for detecting a position of a vehicle motor is functioning normally; an acquisition module, configured to acquire a second powertrain state parameter and a second vehicle speed when a fault in the position sensor is detected, wherein the second powertrain state parameter and the second vehicle speed are data acquired when the vehicle is in position sensorless control mode; The second determination module is used to determine the motor speed based on the second vehicle speed, the second powertrain state parameter and the target wheel radius, and the motor speed is used as the initial motor speed corresponding to the switching into the position sensorless control vehicle.

9. A device for obtaining motor speed, characterized in that: The motor speed acquisition device includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program is configured to implement the steps of the motor speed acquisition method according to any one of claims 1 to 7.

10. A vehicle, characterized in that: The vehicle comprises the motor speed acquisition device according to claim 9, a motor, and a position sensor for detecting the position of the motor; The motor speed acquisition device is used to determine the initial motor speed corresponding to switching to position observer-free control of the motor when a fault in the position sensor is detected.

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