CN114537160B

CN114537160B - Motor drive switching method and device

Info

Publication number: CN114537160B
Application number: CN202210243514.4A
Authority: CN
Inventors: 叶先军
Original assignee: Zhejiang Geely Holding Group Co Ltd; Weirui Electric Automobile Technology Ningbo Co Ltd; Zhejiang Zeekr Intelligent Technology Co Ltd
Current assignee: Zhejiang Geely Holding Group Co Ltd; Weirui Electric Automobile Technology Ningbo Co Ltd; Zhejiang Zeekr Intelligent Technology Co Ltd
Priority date: 2022-03-11
Filing date: 2022-03-11
Publication date: 2022-12-06
Anticipated expiration: 2042-03-11
Also published as: CN114537160A

Abstract

The application provides a motor drive switching method and device. Acquiring an original value of a torque demand according to a current vehicle speed and a current accelerator pedal opening; obtaining an equivalent torque demand through a weighted summation calculation based on the torque demand raw value and the rate of change of the torque demand raw value; if the equivalent torque requirement meets a switching condition, switching to a four-wheel drive mode; wherein the switching condition comprises the equivalent torque request exceeding a rear motor torque capacity, or a four wheel drive mode efficiency at the equivalent torque request being higher than a rear motor drive efficiency. According to the scheme, the motor drive switching time is determined based on the equivalent torque requirement, the time required by drive switching is considered by setting the calculation weight of the equivalent torque requirement, so that the switching time prediction of the two-wheel drive mode and the four-wheel drive mode is realized, the problem of power response lag of drive switching is solved, and the drivability of the whole vehicle is improved.

Description

Motor drive switching method and device

Technical Field

The application relates to the field of electric automobiles, in particular to a motor drive switching method and device.

Background

In order to improve the dynamic property of the whole electric automobile driven by the permanent magnet synchronous motor, a four-wheel drive type with independently driven front and rear shaft motors is adopted. Because the efficiency of the permanent magnet synchronous motor is too low when the weak magnetic control motor runs at high speed, a disconnecting device is usually adopted, and the problem of timely switching of two-drive four-drive exists in order to meet the dynamic requirement of a driver and the requirement of system economy optimization.

At present, when an electric automobile enters four-wheel drive from two-wheel drive, power output can be realized after a disconnecting device completes combination action, the problem of power response lag is caused, acceleration segmentation is caused, the acceleration of the whole automobile is inconsistent, and the drivability of the whole automobile is influenced.

Disclosure of Invention

The application provides a motor drive switching method and a motor drive switching device, which are used for solving the problem of power response lag.

In one aspect, the present application provides a motor driving switching method, including:

acquiring an original value of a torque demand according to the current vehicle speed and the current opening degree of an accelerator pedal;

obtaining an equivalent torque demand through weighted summation calculation based on the torque demand original value and the change rate of the torque demand original value;

if the equivalent torque requirement meets a switching condition, switching to a four-wheel drive mode; wherein the switching condition comprises the equivalent torque demand exceeding a rear motor torque capacity, or a four-wheel drive mode efficiency at the equivalent torque demand being higher than a rear motor drive efficiency.

In one embodiment, the method further comprises:

under the first filtering time constant, performing first-order low-pass filtering processing on the original value of the torque demand to obtain a first original value of the torque demand;

under the second filtering time constant, performing first-order low-pass filtering processing on the original value of the torque demand to obtain a second original value of the torque demand; wherein the first filter time constant is less than the second filter time constant;

the first and second torque demand original values are subtracted from each other, the result being the high frequency part of the torque demand original value.

In one embodiment, the obtaining an equivalent torque request by a weighted summation calculation based on the torque request raw value and a rate of change of the torque request raw value includes:

determining a first weight corresponding to the original value of the torque demand, wherein the first weight is set based on a driving state;

determining a second weight corresponding to the change rate of the original value of the torque demand according to first time required by the motor to be adjusted to match the current vehicle speed and second time required by the disengaging device to execute a combining action;

and according to the first weight and the second weight, carrying out weighted summation processing on the torque demand original value and the change rate of the torque demand original value to obtain the equivalent torque demand.

In one embodiment, determining a first weight corresponding to the torque demand raw value comprises:

and if the current state is in a driving state, setting the first weight to be 1.

In one embodiment, the determining a second weight corresponding to a rate of change of the raw torque demand value based on a first time required for the motor to adjust to match a current vehicle speed and a second time required for the disengagement device to perform the engagement action includes:

determining the motor rotating speed matched with the current vehicle speed, and calculating the time required by the motor to adjust to the motor rotating speed as the first time;

acquiring the second time required for the disengaging device to perform the engaging action;

and determining a second weight coefficient, wherein the second weight coefficient is not less than the sum of the first time and the second time.

In one embodiment, the method further comprises:

and if the equivalent torque requirement does not meet the switching condition and the efficiency of the four-wheel drive mode under the equivalent torque requirement is not higher than the driving efficiency of the rear motor, switching to a two-wheel drive mode.

In another aspect, the present application provides a motor drive switching apparatus, including:

the acquisition module is used for acquiring an original value of the torque demand according to the current vehicle speed and the current opening degree of an accelerator pedal;

the processing module is used for obtaining an equivalent torque demand through weighted summation calculation based on the torque demand original value and the change rate of the torque demand original value;

the switching module is used for switching to a four-wheel drive mode if the equivalent torque requirement meets a switching condition; wherein the switching condition comprises the equivalent torque request exceeding a rear motor torque capacity, or a four wheel drive mode efficiency at the equivalent torque request being higher than a rear motor drive efficiency.

In one embodiment, the apparatus further comprises:

the processing module is specifically used for performing first-order low-pass filtering on the original value of the torque demand to obtain a high-frequency part of the original value of the torque demand;

the processing module is specifically further configured to use the high frequency portion as a variation rate of the torque demand raw value.

In an embodiment, the processing module is further configured to perform first-order low-pass filtering on the original torque demand value under the first filtering time constant to obtain a first original torque demand value;

the processing module is specifically configured to perform first-order low-pass filtering on the original torque demand value under the second filtering time constant to obtain a second original torque demand value; wherein the first filter time constant is less than the second filter time constant;

the processing module is specifically further configured to subtract the first original torque demand value from the second original torque demand value, and an obtained result is used as a high-frequency portion of the original torque demand value.

In one embodiment, the processing module is further configured to determine a first weight corresponding to the original value of the torque demand, the first weight being set based on a driving state;

the processing module is specifically further used for determining a second weight corresponding to the change rate of the original value of the torque demand according to first time required by the motor to be adjusted to match the current vehicle speed and second time required by the disengaging device to execute a combining action;

the processing module is specifically further configured to perform weighted summation processing on the original value of the torque demand and the change rate of the original value of the torque demand according to the first weight and the second weight, so as to obtain the equivalent torque demand.

In an embodiment, the processing module is specifically further configured to set the first weight to 1 if the current driving state is reached.

In one embodiment, the processing module is further configured to determine a motor speed that matches the current vehicle speed, and calculate a time required for the motor to adjust to the motor speed as the first time;

the processing module is specifically further configured to obtain the second time required for the disengagement device to perform the engagement action;

the processing module is specifically further configured to determine a second weight coefficient, where the second weight coefficient is not less than a sum of the first time and the second time.

In an embodiment, the switching module is further configured to switch to a two-drive mode if the equivalent torque requirement does not satisfy the switching condition and efficiency of the four-drive mode under the equivalent torque requirement is not higher than driving efficiency of the rear motor.

According to the motor drive switching method and device, a torque demand original value is obtained according to a relation function between the current vehicle speed and the opening degree of an accelerator pedal, and an equivalent torque demand is obtained through weighted summation calculation based on the torque demand original value and the change rate of the torque demand original value. And if the equivalent torque requirement exceeds the torque capacity of the rear motor, or the four-wheel drive mode efficiency under the equivalent torque requirement is higher than the rear motor drive efficiency, switching the motor from the two-wheel drive mode to the four-wheel drive mode. Otherwise, the mode is switched to the two-drive mode. The scheme determines the motor drive switching time based on the equivalent torque requirement, and combines the calculation weight of the equivalent torque requirement with consideration of the time required by the drive switching, so that the switching time prediction of the two-wheel drive mode and the four-wheel drive mode is realized, the problem of power response lag of the drive switching is solved, and the drivability of the whole vehicle is improved.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and together with the description, serve to explain the principles of the application.

FIG. 1 is a schematic diagram of an exemplary overall vehicle powertrain system;

fig. 2 is a schematic flowchart of a motor driving switching method according to an embodiment of the present application;

FIG. 3 is a graphical illustration of raw torque demand as a function of accelerator pedal position and vehicle speed;

fig. 4 is a schematic structural diagram of a motor driving switching device according to an embodiment of the present application;

fig. 5 is a schematic structural diagram of an electronic device provided in an embodiment of the present application;

FIG. 6 is an apparatus block diagram of a central control unit shown in accordance with an exemplary embodiment.

With the above figures, there are shown specific embodiments of the present application, which will be described in more detail below. The drawings and written description are not intended to limit the scope of the inventive concepts in any manner, but rather to illustrate the concepts of the application by those skilled in the art with reference to specific embodiments.

Detailed Description

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the application, as detailed in the appended claims.

It should be noted that the brief descriptions of the terms in the present application are only for the convenience of understanding the embodiments described below, and are not intended to limit the embodiments of the present application. These terms should be understood in their ordinary and customary meaning unless otherwise indicated.

Fig. 1 is a structural diagram of an exemplary power transmission system of a whole vehicle, and as can be seen in the diagram, the whole vehicle adopts a mode of independently driving a front shaft motor and a rear shaft motor, and comprises a front motor, a rear motor and a release device. The two-wheel drive mode and the four-wheel drive mode are switched by the disconnecting device, and the power system of the automobile is switched to the four-wheel drive mode by the connecting action of the disconnecting device in a working state, namely, the front motor and the rear motor drive the power device of the automobile to run together. The four-wheel drive mode can be exited by stopping the operation of the disconnecting device, and the two-wheel drive mode can be switched, namely, only one motor drives the power device of the automobile. The front motor and the rear motor control the operation of the automobile power device and provide power output to ensure the normal running of the automobile.

The technical means of the present application and the technical means of the present application will be described in detail below with specific examples. These several specific embodiments may be combined with each other below, and details of the same or similar concepts or processes may not be repeated in some embodiments. In the description of the present application, unless otherwise explicitly specified and defined, each term should be understood broadly in the art. Embodiments of the present application will be described below with reference to the accompanying drawings.

Example one

Fig. 2 is a schematic flow chart of a motor driving switching method according to an embodiment of the present application, and as shown in fig. 2, the method includes:

step 101, acquiring an original value of a torque demand according to a current vehicle speed and a current accelerator pedal opening;

102, obtaining an equivalent torque demand through weighted summation calculation based on the torque demand original value and the change rate of the torque demand original value;

step 103, if the equivalent torque requirement meets a switching condition, switching to a four-wheel drive mode; wherein the switching condition comprises the equivalent torque request exceeding a rear motor torque capacity, or a four wheel drive mode efficiency at the equivalent torque request being higher than a rear motor drive efficiency.

Combining a scene example: the control system of the electric automobile controls the switching of the motor drive, and when the control system judges that the two-drive mode needs to be switched to the four-drive mode, the disconnecting device needs to execute the combination action. The release is a mechanical device and the completion of the release engagement causes the vehicle to enter the four-wheel drive mode. The mechanical system of the release device, however, performs the coupling action typically in excess of 300 milliseconds, and in the worst case, even 1 second, before the coupling is complete. The front motor drive will have a power output after the disengagement means has completed the engagement action. In order to avoid the problem of a delay in the influence of power due to a long time of the process of engaging the disengagement means, it is necessary to determine the optimum timing of the mode switching.

Alternatively, a raw value of the torque demand, which is the driver's demanded torque, may be obtained first. The original value of the torque demand can be obtained according to a functional relation between the torque demand and the vehicle speed under the current opening degree of the accelerator pedal. FIG. 3 is a schematic diagram of the original value of the torque demand as a function of vehicle speed at different accelerator pedal positions, the schematic diagram being a continuous smooth surface function fitted from the original value of the torque demand and the current vehicle speed at different accelerator pedal positions. Wherein the horizontal axis is vehicle speed, the vertical axis is the original value of torque demand, and alpha is accelerator pedal opening. The pedal opening alpha can be taken as a value in the driving process, and the range can be 0-100 degrees, so that different pedal opening values correspond to different function fitting curves. When the current original value of the torque demand needs to be obtained, a corresponding fitting curve can be determined according to the current pedal opening degree, and then the current original value of the torque demand can be obtained in the determined fitting curve correspondingly according to the current vehicle speed.

In one example, a high frequency portion of the torque demand raw value is obtained by first order low pass filtering the torque demand raw value; the high frequency portion is taken as a variation rate of the torque demand original value. Specifically, after the original value of the torque demand is calculated, it is necessary to further obtain the equivalent torque demand. As an example, the equivalent torque request is compared with a switching condition to determine a driving mode that the vehicle needs to switch. Specifically, the rate of change of the torque demand raw value needs to be calculated in a first step before the equivalent torque is calculated. As an example, the rate of change of the torque demand raw value may take a high frequency part of the torque demand raw value. In one embodiment, the calculation of the high frequency part of the torque demand raw value may subject the torque demand raw value obtained at this moment to a first order low pass filtering process, which may be expressed as:

k＝1，2，3...n

y(0)＝0

in the above expression: u (k) is input at time k; y (k) is the output at time k; t is a set filtering time constant; dT is the time slice period, e.g. 0.01 seconds, processed by the controller. And k can be taken at any time, different time values are taken through k, and the high-frequency part of the original value of the torque demand at the time k can be obtained through first-order low-pass filtering processing.

The variation rate of the original value of the torque demand is the high frequency part of the original value of the torque demand, which is based on the tool and fourier transform principle of signal analysis and processing, and it can be known that: any continuous periodic signal may be combined from a suitable set of sinusoids. Dividing the group of sinusoidal signals forming the continuous periodic signal into a high-frequency sinusoidal signal group and a low-frequency sinusoidal signal group, and superposing the two types of signals to form an original signal, wherein the low-frequency signal can be approximately regarded as that the change rate of the physical value of the signal is very small, even approximately equal to zero; thus, the rate of change of the physical value of the response signal is approximately equal to the high frequency portion of the signal. In another example, the rate of change of the original value may be calculated by dividing the amount of change of the original value over a period of time by the length of the period of time.

In the example of obtaining the change rate of the original value of the torque demand through the low-pass filtering, the calculation of the change rate is to extract a part in a high-frequency range in the demand torque, and the signal is smooth and continuous, so that the situation that the change rate signal directly calculated in a time domain has a large mutation can be avoided, thereby avoiding the mutation of the equivalent demand torque, causing misjudgment or frequent switching of the drive switching time, and improving the reliability of the drive switching.

In one example, the obtaining a high frequency portion of the torque demand raw value by first order low pass filtering the torque demand raw value includes:

under the first filtering time constant, performing first-order low-pass filtering processing on the original torque demand value to obtain a first original torque demand value;

under the second filtering time constant, performing first-order low-pass filtering processing on the original value of the torque demand to obtain an original value of the second torque demand; wherein the first filter time constant is less than the second filter time constant;

In the first-order low-pass filtering process for the original value of the torque demand, different filtering time constants T are taken to filter or attenuate different frequency components in the original value of the torque demand. Thus by selecting different time constants, torque request signals containing different frequency components are obtained. Alternatively, a smaller filter time constant T1 may be set as the first filter time constant, for example, T1=0.03, and the obtained first torque demand original value contains more high-frequency components. Setting a larger filter time constant T2 as the second filter time constant, e.g., T2=0.5, the obtained second torque demand raw value contains less high frequency components. Subtracting the first torque demand raw value from the second torque demand raw value, and taking the result of the subtraction as a high-frequency portion of the torque demand raw value, that is, the rate of change in the torque demand raw value.

In one example, the obtaining an equivalent torque request by a weighted summation calculation based on the torque request raw value and a rate of change of the torque request raw value includes:

Specifically, the equivalent torque request can be obtained by further performing weighted summation calculation on the obtained original value of the torque request and the variation rate of the original value of the torque request. Based on different states (such as different vehicle speeds), the time required by the disconnecting device to execute the combining action is different, and sufficient time needs to be reserved for the disconnecting device to execute the combining action in different states, so that the calculation of equivalent required torque can be adjusted by adjusting a weight coefficient, the calculation of the equivalent required torque determines the time for switching the two-drive and the four-drive, and the time for switching is selected timely, so that the smoothness of the two-drive and the four-drive switching is ensured. The first weighting factor can be determined according to the current state of the vehicle, and the second weighting factor is determined according to the time required by the rotation speed of the front motor to be matched with the rotation speed of the output shaft and the time required by the disengaging device to perform the combining action.

And if the current state is in a driving state, setting the first weight to be 1. The original value of the torque demand corresponds to a first weight coefficient factor1, and the automobile is roughly divided into a driving state and a non-driving state. The corresponding equivalent torque demand need not be calculated when the vehicle is in a non-driving state. When the automobile is in a driving state, it is required to determine that the original value of the torque demand corresponds to the first weight coefficient factor1. The driving state refers to that the automobile is in a running state, and at this time, the first weight coefficient factor1 is selectable to be 1 in the automobile driving state.

The determining a second weight corresponding to the change rate of the original value of the torque demand according to the time required for adjusting the matching of the current motor rotating speed and the output shaft rotating speed and the time required for the disengaging device to execute the combining action comprises the following steps:

actively adjusting the rotating speed of the motor to be matched with the rotating speed of the output shaft through a rotating speed control mode of the motor, and determining first time required to be adjusted according to the current vehicle speed and a rotating speed difference required to be adjusted between the rotating speed of the motor and the rotating speed of the output shaft;

obtaining a second time required for the disengagement means to perform the engagement action by actual measurement;

determining a second weight factor, the second weight factor selected to be no less than the sum of the first time and the second time.

The change rate of the torque demand original value corresponds to a second weight coefficient factor2, and the determination of the second weight coefficient factor2 needs to be obtained by means of the current vehicle speed. Specifically, firstly, the time Ts for the current disengagement device to perform the engagement action is determined according to the current vehicle speed v, which affects the time for the disengagement device to perform the engagement action, and the first function f.

In the actual scene, in the driving process of the automobile, the rotating speed of an output shaft of the motor reflects the current driving speed of the automobile, but before the automobile enters four-wheel drive driving, the front motor does not work, and the rotating speed of the front motor is zero. When the automobile enters four-wheel drive from two-wheel drive, a rotation speed difference needing to be adjusted exists between the rotation speed of the motor and the rotation speed of the output shaft, and the time needed for adjusting the rotation speed difference is the first time. When there is no difference between the rotational speed of the motor and the rotational speed of the output shaft, the disengagement means will engage, the time required for the engagement being said second time, which can be obtained by actual measurement.

In one example, the execution time Ts for the driving switching is composed of two parts, namely a first time and a second time, respectively, i.e. the Ts is the sum of the first time and the second time. Since the execution time Ts of the drive switch is influenced by the current vehicle speed (the current vehicle speed influences the time Ts1 required by the motor to adjust the rotational speed difference), it is possible to define that the execution time Ts of the drive switch is a function T of said current vehicle speed _s = f (v). Specifically, a first time Ts1 is obtained according to the current vehicle speed; the time Ts2 for the disengagement device to perform the engagement operation is obtained, and the time required for the disengagement device to perform the engagement operation is the time required for the mechanical actuator to operate, so that in practical applications, ts2 may be obtained in advance through actual measurement. Accordingly, in order to predict the time of drive switchingAnd the second weight coefficient factor2 is set to be not less than the engaging action execution time Ts of the disengaging device. The execution time Ts of the drive switching affects the second weight factor2, so that a functional relationship factor2= g (Ts) may be defined between the execution time Ts of the drive switching and said second weight factor 2. The two functional relations can be described in a one-dimensional table look-up manner in software of a control system by determining specific numerical values through real vehicle calibration data.

And obtaining the equivalent torque requirement of the automobile through the obtained torque requirement original value, the change rate of the torque requirement original value, the first weight coefficient and the second weight coefficient. Specifically, the torque demand original value corresponds to the first weight coefficient, and the change rate of the torque demand original value corresponds to the second weight coefficient to perform weighted summation calculation to obtain the equivalent torque demand of the automobile.

And comparing the obtained equivalent torque requirement of the automobile with the torque capacity of the rear motor, and judging whether the automobile needs to enter a four-wheel drive mode. Specifically, when the calculated equivalent torque demand exceeds the torque capacity of the rear motor, the four-wheel drive mode can be entered; in addition, when the calculated equivalent torque requirement is higher than the system efficiency of the independent driving of the rear motor by adopting the highest system efficiency of the cooperation of the front motor and the rear motor, the four-wheel drive mode can be entered. It should be noted that the above-mentioned conditions for determining handover may be implemented individually or in combination, for example, if either one of the conditions is satisfied, the handover is performed, or if both conditions are satisfied, the handover is performed.

Wherein, the calculation of the torque capacity of the front motor and the rear motor specifically comprises the following steps: (1) And (3) selecting the motor power grade based on the requirement of the whole vehicle (for example, X vehicle type, the peak power of the front motor is 100Kw, and the peak power of the rear motor is 200 Kw). (2) In the running process of the motor, derating protection can be carried out based on the following conditions, respectively: motor temperature, IGBT temperature, cooling water temperature, bus voltage, available power distributed to the front and rear motors by the high-voltage battery, derating based on motor speed, and the like. The torque capacities of the front motor and the rear motor can be calculated in real time by integrating the protection and limiting conditions.

Specifically, when the calculated equivalent torque request does not exceed the rear motor torque capacity, i.e., no dynamic demand, the four-wheel drive mode is entered. And when the highest system efficiency of the front motor and the rear motor matched in the four-wheel drive mode is lower than the system efficiency of the rear motor driven independently, the four-wheel drive mode exits and the two-wheel drive mode enters.

According to the embodiment, a torque demand original value is obtained according to a relation function between the current vehicle speed and the opening degree of an accelerator pedal, and an equivalent torque demand is obtained through weighted summation calculation based on the torque demand original value and the change rate of the torque demand original value. And if the equivalent torque requirement exceeds the torque capacity of the rear motor, or the four-wheel drive mode efficiency under the equivalent torque requirement is higher than the rear motor drive efficiency, switching the motor from the two-wheel drive mode to the four-wheel drive mode. Otherwise, the mode is switched to the two-drive mode. The scheme determines the motor drive switching time based on the equivalent torque requirement, and combines the calculation weight of the equivalent torque requirement with consideration of the time required by the drive switching, so that the switching time prediction of the two-wheel drive mode and the four-wheel drive mode is realized, the problem of power response lag of the drive switching is solved, and the drivability of the whole vehicle is improved.

Example two

Fig. 4 is a schematic structural diagram of a motor driving switching device according to an embodiment of the present application, and as shown in fig. 4, the device includes:

the acquiring module 21 is used for acquiring an original value of the torque demand according to the current vehicle speed and the current opening degree of an accelerator pedal;

a processing module 22, configured to obtain an equivalent torque request through a weighted summation calculation based on the torque request raw value and a variation rate of the torque request raw value;

and the switching module 23 is configured to obtain an equivalent torque demand through a weighted summation calculation based on the torque demand raw value and the variation rate of the torque demand raw value.

Combining a scene example: the control system of the electric automobile controls the switching of the motor drive, and when the control system judges that the two-drive mode needs to be switched to the four-drive mode, the disconnecting device needs to execute the combination action. The release is a mechanical device and the completion of the release engagement causes the vehicle to enter the four-wheel drive mode. The mechanical system of the release device, however, performs the coupling action typically in excess of 300 milliseconds, and in the worst case, even 1 second, before the coupling is complete. The front motor drive will have a power output after the disengagement means has completed the engagement action. In order to avoid the problem of the delay in the power influence due to the long process time for the disengagement means to engage, it is necessary to determine the optimum timing for the mode switching.

Alternatively, the obtaining means 21 may first obtain a raw value of the torque demand, which is the driver's demanded torque. The original value of the torque demand can be obtained according to a functional relation between the torque demand and the vehicle speed under the current opening degree of the accelerator pedal. And under different accelerator pedal positions, the original torque demand value and the current vehicle speed can be fitted to form a continuous smooth curved surface function. The available value of the pedal opening in the driving process is a range which can be 0-100 degrees, so that different pedal opening values correspond to different function fitting curves. When the current original torque demand value needs to be obtained, the processing module 22 may determine a corresponding fit curve according to the current pedal opening degree, and then obtain the current original torque demand value from the determined fit curve according to the current vehicle speed.

In one example, the processing module 22 is further configured to perform a first order low pass filtering process on the raw torque request value to obtain a high frequency portion of the raw torque request value.

The processing module 22 is further configured to use the high frequency portion as a variation rate of the original value of the torque demand.

Specifically, after the processing module 22 calculates the raw value of the torque request, it is necessary to further obtain the equivalent torque request. As an example, the equivalent torque request is compared with a switching condition to determine a driving mode that the vehicle needs to be switched to at the moment. Specifically, the rate of change of the torque demand raw value needs to be calculated in a first step before calculating the equivalent torque. As an example, the rate of change of the torque demand raw value may take a high frequency portion of the torque demand raw value. In one embodiment, the calculation of the high frequency part of the torque demand raw value can perform a first-order low-pass filtering process on the torque demand raw value obtained at this moment, and the variation rate of the torque demand raw value is the high frequency part of the torque demand raw value, which is based on the tool and fourier transform principle of signal analysis processing, and it can be known that: any continuous periodic signal may be combined from a suitable set of sinusoids. Dividing the group of sinusoidal signals forming the continuous periodic signal into a high-frequency sinusoidal signal group and a low-frequency sinusoidal signal group, and superposing the two types of signals to form an original signal, wherein the low-frequency signal can be approximately regarded as that the change rate of the physical value of the signal is very small, even approximately equal to zero; thus, the rate of change of the physical value of the response signal is approximately equal to the high frequency portion of the signal. In another example, the rate of change of the original value may be calculated by dividing the amount of change of the original value over a period of time by the length of the period of time.

In one example, the processing module 22 is further configured to perform a first-order low-pass filtering process on the original torque demand value under the first filtering time constant to obtain a first original torque demand value;

the processing module 22 is specifically configured to perform first-order low-pass filtering on the original torque demand value under the second filtering time constant to obtain a second original torque demand value; wherein the first filter time constant is less than the second filter time constant;

the processing module 22 is further configured to subtract the first torque request raw value from the second torque request raw value, and obtain the result as a high frequency portion of the torque request raw value.

The processing module 22 filters or attenuates the different frequency components of the raw torque request value by taking the different filter time constants T in the first order low pass filtering of the raw torque request value. Thus by selecting different time constants, torque request signals containing different frequency components are obtained. Alternatively, a smaller filter time constant T1 may be set as the first filter time constant, for example, T1=0.03, and the obtained first torque demand original value contains more high-frequency components. A larger filter time constant T2 is set as the second filter time constant, such as T2=0.5, and the obtained second torque demand original value contains less high frequency components. And subtracting the first torque demand original value from the second torque demand original value, and taking the result of subtraction as a high-frequency part of the torque demand original value, namely the change rate of the torque demand original value.

In one example, the processing module 22 is further configured to determine a first weight corresponding to the original value of the torque demand, the first weight being set based on a driving state;

the processing module 22 is further specifically configured to determine a second weight corresponding to a change rate of the original value of the torque demand according to a first time required for the motor to adjust to match the current vehicle speed and a second time required for the disengagement device to perform a combining action;

the processing module 22 is specifically further configured to perform a weighted summation process on the original value of the torque demand and the change rate of the original value of the torque demand according to the first weight and the second weight, so as to obtain the equivalent torque demand.

Specifically, the equivalent torque request is obtained, and the processing module 22 may further perform a weighted summation calculation according to the obtained original value of the torque request and the variation rate of the original value of the torque request. Based on different states (such as different vehicle speeds), the time required by the disconnecting device to execute the combining action is different, and in different states, sufficient time needs to be reserved for the disconnecting device to execute the combining action, so that the calculation of the equivalent required torque can be adjusted by adjusting the weight coefficient, the calculation of the equivalent required torque determines the time for switching the two-drive and the four-drive, and the time for switching is selected timely, thereby ensuring the smoothness of the switching of the two-drive and the four-drive. The first weight coefficient can be determined according to the current state of the automobile, and the second weight coefficient is determined according to the time required by the rotating speed of the front motor to be matched with the rotating speed of the output shaft and the time required by the disengaging device to perform the engaging action.

The processing module 22 is further configured to set the first weight to 1 if the current state is the driving state. The original value of the torque demand corresponds to a first weighting factor1, and the automobile is roughly divided into a driving state and a non-driving state. The corresponding equivalent torque demand need not be calculated when the vehicle is in a non-driving state. When the automobile is in a driving state, it is required to determine that the original value of the torque demand corresponds to the first weight coefficient factor1. The driving state refers to that the automobile is in a running state, and at this time, optionally, the first weight coefficient factor1 may be 1 in the driving state of the automobile.

The processing module 22 is specifically configured to determine a motor speed matched with the current vehicle speed, and calculate a time required for the motor to adjust to the motor speed as the first time;

the processing module 22 is specifically further configured to obtain the second time required for the disengagement device to perform the engagement action;

the processing module 22 is specifically further configured to determine a second weight coefficient, where the second weight coefficient is not less than a sum of the first time and the second time.

The change rate of the torque demand original value corresponds to a second weight coefficient factor2, and the determination of the second weight coefficient factor2 needs to be obtained by means of the current vehicle speed. Specifically, the processing module 22 first determines the current engaging and disengaging device engaging and actuating time Ts according to the current vehicle speed v and the first function f, where the vehicle speed affects the engaging and actuating time of the disengaging device.

In the actual scene, in the driving process of the automobile, the rotating speed of an output shaft of the motor reflects the current driving speed of the automobile, but before the automobile enters four-wheel drive driving, the front motor does not work, and the rotating speed of the front motor is zero. When the automobile enters four-wheel drive from two-wheel drive, a rotation speed difference needing to be adjusted exists between the rotation speed of the motor and the rotation speed of the output shaft, and the time required for adjusting the rotation speed difference is the first time. When there is no difference between the rotational speed of the motor and the rotational speed of the output shaft, the disengagement means will engage, the time required for the engagement being said second time, which can be obtained by actual measurement.

In one example, the execution time Ts for the driving switching is composed of two parts, namely a first time and a second time, respectively, i.e. the Ts is the sum of the first time and the second time. Since the execution time Ts of the drive switching is influenced by the current vehicle speed (the current vehicle speed influences the time Ts1 required for the motor to adjust the rotational speed difference), it is possible to define that the execution time Ts of the drive switching is in a functional relationship Ts = f (v) with said current vehicle speed. Specifically, a first time Ts1 is obtained according to the current vehicle speed; the time Ts2 for the disengagement device to perform the engagement action is obtained, and the time required for the disengagement device to perform the engagement action is the time required for the mechanical actuator to act, so that in practical applications, ts2 can be obtained in advance through actual measurement. Accordingly, in order to predict the drive switching timing, the second weight coefficient factor2 is set to be not less than the engaging action execution time Ts of the disengagement means. Therefore, the execution time Ts of the driving switch affects the second weight factor2, so that the execution time Ts of the driving switch and the second weight factor2 can be defined to form a functional relationship of factor2= g (Ts). The two functional relations can be described in a one-dimensional table look-up manner in software of a control system by determining specific numerical values through real vehicle calibration data.

And obtaining the equivalent torque requirement of the automobile through the obtained torque requirement original value, the change rate of the torque requirement original value, the first weight coefficient and the second weight coefficient. Specifically, the torque demand original value corresponds to the first weight coefficient, and the change rate of the torque demand original value corresponds to the second weight coefficient, so that the equivalent torque demand of the automobile is obtained through weighted summation calculation.

And comparing the obtained equivalent torque requirement of the automobile with the torque capacity of the rear motor, and judging whether the four-wheel drive mode needs to be entered or not. Specifically, when the calculated equivalent torque demand exceeds the torque capacity of the rear motor, the four-wheel drive mode can be entered; in addition, when the calculated equivalent torque requirement is higher than the system efficiency of the single drive of the rear motor by adopting the highest system efficiency of the cooperation of the front motor and the rear motor, the four-wheel drive mode can be entered. It should be noted that the above-mentioned handover determination conditions may be implemented individually or in combination, for example, the handover is executed when either one of the conditions is satisfied, or the handover is executed when both conditions are satisfied.

Wherein, the calculation of the torque capacity of the front motor and the rear motor specifically comprises the following steps: (1) And (3) selecting the motor power grade based on the requirement of the whole vehicle (for example, X vehicle type, the peak power of the front motor is 100Kw, and the peak power of the rear motor is 200 Kw). (2) In the running process of the motor, derating protection can be carried out based on the following conditions: motor temperature, IGBT temperature, cooling water temperature, bus voltage, available power distributed to the front and rear motors by the high-voltage battery, derating based on motor speed, and the like. The torque capacities of the front motor and the rear motor can be calculated in real time by integrating the protection and limiting conditions.

The switching module 23 is specifically configured to switch to a two-drive mode if the equivalent torque requirement does not satisfy the switching condition and the efficiency of the four-drive mode under the equivalent torque requirement is not higher than the driving efficiency of the rear motor

Specifically, when the calculated equivalent torque request does not exceed the rear motor torque capacity, i.e., no dynamic demand, the four-wheel drive mode is entered. And, when the maximum system efficiency of the front and rear motors matching in the four-wheel drive mode is lower than the system efficiency of the rear motor driving alone, the switching module 23 switches from the four-wheel drive mode to the two-wheel drive mode.

The obtaining module 21 of this embodiment obtains an original value of a torque demand according to a relation function between a current vehicle speed and an accelerator pedal opening, and the processing module 22 obtains an equivalent torque demand through weighted summation calculation based on the original value of the torque demand and a variation rate of the original value of the torque demand. If the equivalent torque requirement exceeds the torque capacity of the rear motor, or the efficiency of the four-wheel drive mode under the equivalent torque requirement is higher than the driving efficiency of the rear motor, the switching module 23 switches the motor from the two-wheel drive mode to the four-wheel drive mode. Otherwise, the mode is switched to the two-drive mode. The scheme determines the motor drive switching time based on the equivalent torque requirement, and combines the calculation weight of the equivalent torque requirement with consideration of the time required by the drive switching, so that the switching time prediction of the two-wheel drive mode and the four-wheel drive mode is realized, the problem of power response lag of the drive switching is solved, and the drivability of the whole vehicle is improved.

EXAMPLE III

Fig. 5 is a schematic structural diagram of an electronic device provided in an embodiment of the present application, and as shown in fig. 5, the electronic device includes:

a processor (processor) 291, the electronic device further including a memory (memory) 292; a Communication Interface 293 and bus 294 may also be included. The processor 291, the memory 292, and the communication interface 293 may communicate with each other via the bus 294. Communication interface 293 may be used for the transmission of information. Processor 291 may call logic instructions in memory 294 to perform the methods of the embodiments described above.

Further, the logic instructions in the memory 292 may be implemented in software functional units and stored in a computer readable storage medium when sold or used as a stand-alone product.

The memory 292 is used as a computer-readable storage medium for storing software programs, computer-executable programs, such as program instructions/modules corresponding to the methods in the embodiments of the present application. The processor 291 executes the functional application and data processing by executing the software program, instructions and modules stored in the memory 292, so as to implement the method in the above method embodiments.

The memory 292 may include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required for at least one function; the storage data area may store data created according to the use of the terminal device, and the like. Further, the memory 292 may include a high speed random access memory and may also include a non-volatile memory.

The present application provides a non-transitory computer-readable storage medium, in which computer-executable instructions are stored, and when executed by a processor, the computer-executable instructions are used to implement the method according to the foregoing embodiments.

Example four

Fig. 6 is a block diagram illustrating an apparatus of a central control unit, which may be a computer, a terminal, a messaging device, a tablet device, an operator console, etc., according to an exemplary embodiment. The apparatus may be used to perform the grid-tie control method described in the foregoing embodiments.

The apparatus 800 may include one or more of the following components: a processing component 802, a memory 804, a power component 806, a multimedia component 808, an audio component 810, an input/output (I/O) interface 812, a sensor component 814, and a communication component 816.

The processing component 802 generally controls overall operation of the device 800, such as operations associated with display, telephone calls, data communications, camera operations, and recording operations. The processing components 802 may include one or more processors 820 to execute instructions to perform all or a portion of the steps of the methods described above. Further, the processing component 802 can include one or more modules that facilitate interaction between the processing component 802 and other components. For example, the processing component 802 can include a multimedia module to facilitate interaction between the multimedia component 808 and the processing component 802.

The memory 804 is configured to store various types of data to support operations at the apparatus 800. Examples of such data include instructions for any application or method operating on device 800, contact data, phonebook data, messages, pictures, videos, and so forth. The memory 804 may be implemented by any type or combination of volatile or non-volatile memory devices, such as Static Random Access Memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic or optical disks.

A power supply component 806 provides power to the various components of the device 800. The power components 806 may include a power management system, one or more power supplies, and other components associated with generating, managing, and distributing power for the apparatus 800.

Optionally, the multimedia component 808 includes a screen providing an output interface between the device 800 and the user. In some embodiments, the screen may include a Liquid Crystal Display (LCD) and a Touch Panel (TP). If the screen includes a touch panel, the screen may be implemented as a touch screen to receive an input signal from a user. The touch panel includes one or more touch sensors to sense touch, slide, and gestures on the touch panel. The touch sensor may not only sense the boundary of a touch or slide action, but also detect the duration and pressure associated with the touch or slide operation. In some embodiments, the multimedia component 808 includes a front facing camera and/or a rear facing camera. The front camera and/or the rear camera may receive external multimedia data when the device 800 is in an operating mode, such as a shooting mode or a video mode. Each front camera and rear camera may be a fixed optical lens system or have a focal length and optical zoom capability.

Optionally, the audio component 810 is configured to output and/or input audio signals. For example, audio component 810 includes a Microphone (MIC) configured to receive external audio signals when apparatus 800 is in an operational mode, such as a call mode, a recording mode, and a voice recognition mode. The received audio signals may further be stored in the memory 804 or transmitted via the communication component 816. In some embodiments, audio component 810 also includes a speaker for outputting audio signals.

The I/O interface 812 provides an interface between the processing component 802 and peripheral interface modules, which may be keyboards, click wheels, buttons, etc. These buttons may include, but are not limited to: a home button, a volume button, a start button, and a lock button.

The sensor assembly 814 includes one or more sensors for providing various aspects of state assessment for the device 800. For example, the sensor assembly 814 may detect the open/closed state of the device 800, the relative positioning of components, such as a display and keypad of the device 800, the sensor assembly 814 may also detect a change in position of the device 800 or a component of the device 800, the presence or absence of user contact with the device 800, the orientation or acceleration/deceleration of the device 800, and a change in temperature of the device 800. Sensor assembly 814 may include a proximity sensor configured to detect the presence of a nearby object without any physical contact. The sensor assembly 814 may also include a light sensor, such as a CMOS or CCD image sensor, for use in imaging applications. In some embodiments, the sensor assembly 814 may also include an acceleration sensor, a gyroscope sensor, a magnetic sensor, a pressure sensor, or a temperature sensor.

The communication component 816 is configured to facilitate communication between the apparatus 800 and other devices in a wired or wireless manner. The device 800 may access a wireless network based on a communication standard, such as WiFi,2G or 3G, or a combination thereof. In an exemplary embodiment, the communication component 816 receives a broadcast signal or broadcast related information from an external broadcast management system via a broadcast channel. In an exemplary embodiment, the communication component 816 further includes a Near Field Communication (NFC) module to facilitate short-range communications. For example, the NFC module may be implemented based on Radio Frequency Identification (RFID) technology, infrared data association (IrDA) technology, ultra Wideband (UWB) technology, bluetooth (BT) technology, and other technologies.

In an exemplary embodiment, the apparatus 800 may be implemented by one or more Application Specific Integrated Circuits (ASICs), digital Signal Processors (DSPs), digital Signal Processing Devices (DSPDs), programmable Logic Devices (PLDs), field Programmable Gate Arrays (FPGAs), controllers, micro-controllers, microprocessors, or other electronic components for performing the above-described methods.

In an exemplary embodiment, a non-transitory computer-readable storage medium comprising instructions, such as the memory 804 comprising instructions, executable by the processor 820 of the device 800 to perform the above-described method is also provided. For example, the non-transitory computer readable storage medium may be a ROM, a Random Access Memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like.

Other embodiments of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the application and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the application being indicated by the following claims.

It will be understood that the present application is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the application is limited only by the appended claims.

Claims

1. A motor drive switching method, comprising:

if the equivalent torque requirement meets a switching condition, switching to a four-wheel drive mode; wherein the switching condition comprises that the equivalent torque demand exceeds a rear motor torque capacity, or that a four-wheel drive mode efficiency under the equivalent torque demand is higher than a rear motor drive efficiency;

obtaining an equivalent torque demand through a weighted summation calculation based on the torque demand raw value and the rate of change of the torque demand raw value, comprising:

2. The method of claim 1, further comprising:

obtaining a high frequency portion of the torque demand raw value by first order low pass filtering the torque demand raw value;

the high frequency portion is taken as a variation rate of the torque demand original value.

3. The method of claim 2, wherein said obtaining a high frequency portion of said torque demand raw value by first order low pass filtering said torque demand raw value comprises:

under a first filtering time constant, performing first-order low-pass filtering processing on the original value of the torque demand to obtain a first original value of the torque demand;

under a second filtering time constant, performing first-order low-pass filtering processing on the original value of the torque demand to obtain an original value of the second torque demand; wherein the first filter time constant is less than the second filter time constant;

4. The method of claim 1, wherein determining a first weight for the torque demand raw value comprises:

5. The method of claim 1, wherein determining a second weight corresponding to a rate of change of the torque demand origin value based on a first time required for the motor to adjust to match a current vehicle speed and a second time required for the disengagement device to perform the engagement action comprises:

6. The method according to any one of claims 1-5, further comprising:

7. A motor drive switching device, comprising:

the switching module is used for switching to a four-wheel drive mode if the equivalent torque requirement meets a switching condition; wherein the switching condition comprises that the equivalent torque demand exceeds a rear motor torque capacity, or that a four-wheel drive mode efficiency under the equivalent torque demand is higher than a rear motor drive efficiency;

the processing module is specifically further configured to determine a first weight corresponding to the original torque demand value, where the first weight is set based on a driving state;

8. The apparatus of claim 7,

9. The apparatus of claim 8,

the processing module is specifically configured to perform first-order low-pass filtering on the original torque demand value under a first filtering time constant to obtain a first original torque demand value;

the processing module is specifically configured to perform first-order low-pass filtering on the original value of the torque demand under a second filtering time constant to obtain an original value of a second torque demand; wherein the first filter time constant is less than the second filter time constant;

10. The apparatus of claim 7,

the processing module is specifically configured to set the first weight to 1 if the current driving state is reached.

11. The apparatus of claim 7,

the processing module is specifically used for determining the motor rotating speed matched with the current vehicle speed and calculating the time required by the motor to adjust to the motor rotating speed as the first time;

the processing module is specifically further configured to acquire the second time required for the disengagement device to perform the engagement action;

12. The apparatus according to any one of claims 7 to 11,

the switching module is specifically further configured to switch to a two-drive mode if the equivalent torque requirement does not meet the switching condition and efficiency of the four-drive mode under the equivalent torque requirement is not higher than driving efficiency of a rear motor.