A method and system for controlling motor speed of hybrid vehicle

Abstract

The present invention provides a motor speed control method and system for a hybrid vehicle, the method comprising the following steps: a motor controller is preset with: a preset torque, a maximum allowable motor speed, and a preset maximum motor speed; the motor controller collects the current speed of the motor and compares it with the maximum allowable motor speed or the preset maximum motor speed; when the current speed is greater than the maximum allowable motor speed, the output torque of the motor is controlled to be 0; when the current speed is less than the preset maximum motor speed, the output torque of the motor is controlled to be the preset torque; when the current speed is greater than the preset maximum motor speed and less than or equal to the maximum allowable motor speed, the output torque of the motor is controlled to be reduced step by step or instantaneously with the deviation torque as the control variable, and when the current speed drops to the preset maximum speed of the motor, the current torque is maintained as the output torque of the motor. Thus, the requirements for the speed and accuracy of the speed response are reduced, and the speed fluctuation will not occur due to the speed and accuracy of the speed response.

Description

Technical Field

[0001] The present invention relates to the field of motor control, and in particular to a motor speed control method and system for a hybrid vehicle. Background Art

[0002] With the rapid development of hybrid vehicles, motor control has become the main design direction for various manufacturers. The motor works through the torque loop, but the torque loop cannot control the speed. When performing bench testing and actual work, it is necessary to limit the speed in the torque loop control mode so that the motor can work at the limited speed. This torque loop speed limit control method can maintain the output torque under high load conditions. At the same time, combined with the original overspeed protection of the controller, the speed control and overspeed protection can be achieved under the torque loop.

[0003] Although the speed limit requirement is known, the torque control method in the previous torque loop control mode is that the motor controller directly outputs the given torque without controlling the speed. Although the motor controller has an overspeed protection function, it can limit the torque output to when the actual speed reaches the maximum speed allowed by the motor to prevent motor damage, but this protection function can only protect the motor from damage and cannot maintain the speed at the required maximum speed.

[0004] Therefore, a new motor speed control method for a hybrid vehicle is needed to meet the user's demand for rapid torque output under heavy load conditions and respond to speed control under load changes. Summary of the invention

[0005] In order to overcome the above-mentioned technical defects, the purpose of the present invention is to provide a motor speed control method and system for a hybrid vehicle. No separate calibration work is required in the control method, which can significantly improve the development progress. At the same time, the requirements for the speed and accuracy of the speed response are reduced, and the speed fluctuation will not occur due to the speed and accuracy of the speed response.

[0006] The present invention discloses a motor speed control method for a hybrid vehicle. The motor speed control method is executed in a torque loop control mode and includes the following steps:

[0007] The motor controller is preset with: preset torque, maximum allowable motor speed, and preset maximum motor speed, where the maximum allowable motor speed is greater than the preset maximum motor speed;

[0008] The motor controller controls the motor of the hybrid vehicle based on a preset torque, collects the current speed of the motor in real time, and compares the current speed with the maximum speed allowed by the motor or the preset maximum speed of the motor;

[0009] When the current speed is greater than the maximum speed allowed by the motor, the motor controller controls the output torque of the motor to 0;

[0010] When the current speed is less than the preset maximum speed of the motor, the motor controller controls the output torque of the motor to be the preset torque;

[0011] When the current speed is greater than the preset maximum speed of the motor and less than or equal to the maximum allowable speed of the motor, the motor controller calculates the deviation speed between the current speed and the preset maximum speed of the motor, and calculates a deviation torque based on the deviation speed. The motor controller uses the deviation torque as a control variable to control the output torque of the motor to decrease step by step or instantaneously, and repeatedly compares the current speed with the preset maximum speed of the motor; when the current speed drops to the preset maximum speed of the motor, the current torque is maintained as the output torque of the motor.

[0012] Preferably, a first buffer period and a second buffer period are preset in the motor controller;

[0013] When the current speed is greater than the maximum speed allowed by the motor, and the current speed is greater than the rated speed for more than the first buffer period, the motor controller controls the output torque of the motor to be 0, otherwise the motor controller maintains controlling the motor based on the preset torque;

[0014] When the current speed is less than the preset maximum speed of the motor, and the current speed is less than the preset maximum speed of the motor for a period of time exceeding the first buffer period, the motor controller controls the output torque of the motor to be the preset torque;

[0015] When the current speed is greater than the preset maximum speed of the motor and less than or equal to the maximum speed allowed by the motor, and the current speed is greater than the preset maximum speed of the motor and less than or equal to the maximum speed allowed by the motor for a period of time exceeding the first buffer period, the motor controller calculates the deviation speed between the current speed and the preset maximum speed of the motor, otherwise the motor controller maintains controlling the motor based on the preset torque;

[0016] When the current rotation speed drops to the maximum rotation speed allowed by the motor, and the period from the current rotation speed dropping to the maximum rotation speed allowed by the motor continues to exceed the second buffer period, the current torque is maintained as the output torque of the motor.

[0017] Preferably, when the current speed is greater than the preset maximum speed of the motor and less than or equal to the maximum speed allowed by the motor, the motor controller calculates the deviation speed between the current speed and the preset maximum speed of the motor, and calculates a deviation torque according to the deviation speed, and the step of the motor controller controlling the output torque of the motor to decrease step by step or instantaneously using the deviation torque as a control variable includes:

[0018] The motor controller calculates a ratio of the deviation speed to a preset maximum speed of the motor, multiplies the preset torque by the ratio to calculate the deviation torque, and subtracts the deviation torque from the preset torque as an update torque;

[0019] The motor controller controls the output torque of the motor to be the update torque.

[0020] Preferably, the step of the motor controller controlling the output torque of the motor to be the updated torque comprises:

[0021] The change of the current speed lags behind the change of the output torque by a hysteresis time;

[0022] The motor controller linearly or nonlinearly decreases the preset torque to n% of the updated torque within the hysteresis time, where 80≤n<100;

[0023] When the current speed has an inflection point, the motor controller controls the current torque of the motor to be the updated torque and maintains it, so that the current speed gradually decreases to the preset maximum speed of the motor.

[0024] Preferably, the method further comprises the following steps:

[0025] When the preset torque or the preset maximum speed of the motor is changed to the latest torque or the latest maximum speed, the motor controller compares the current speed with the latest maximum speed again;

[0026] When the current speed is less than the latest maximum speed, the motor controller controls the output torque of the motor to be the latest torque;

[0027] When the current speed is greater than the latest maximum speed and less than or equal to the maximum allowable speed of the motor, the motor controller calculates the deviation speed between the current speed and the latest maximum speed, and calculates a deviation torque based on the deviation speed. The motor controller uses the deviation torque as a control variable to control the output torque of the motor to decrease step by step or instantaneously, and repeatedly compares the current speed and the latest maximum speed; when the current speed drops to the latest maximum speed, the current torque is maintained as the output torque of the motor, and the torque is modified and updated to be the current torque.

[0028] The present invention also discloses a motor speed control system for a hybrid vehicle, wherein the motor speed control system is executed in a torque loop control mode, and comprises:

[0029] A motor controller, which has preset contents: preset torque, maximum allowable motor speed, and preset maximum motor speed, wherein the maximum allowable motor speed is greater than the preset maximum motor speed;

[0030] A motor, provided in the hybrid vehicle and controlled by a motor controller;

[0031] The motor controller controls the motor of the hybrid vehicle based on a preset torque, collects the current speed of the motor in real time, and compares the current speed with the maximum speed allowed by the motor or the preset maximum speed of the motor;

[0032] When the current speed is greater than the maximum speed allowed by the motor, the motor controller controls the output torque of the motor to 0;

[0033] When the current speed is less than the preset maximum speed of the motor, the motor controller controls the output torque of the motor to be the preset torque;

[0034] When the current speed is greater than the preset maximum speed of the motor and less than or equal to the maximum allowable speed of the motor, the motor controller calculates the deviation speed between the current speed and the preset maximum speed of the motor, and calculates a deviation torque based on the deviation speed. The motor controller uses the deviation torque as a control variable to control the output torque of the motor to decrease step by step or instantaneously, and repeatedly compares the current speed with the preset maximum speed of the motor; when the current speed drops to the preset maximum speed of the motor, the current torque is maintained as the output torque of the motor.

[0035] Preferably, a first buffer period and a second buffer period are preset in the motor controller;

[0036] When the current speed is greater than the maximum speed allowed by the motor, and the current speed is greater than the rated speed for more than the first buffer period, the motor controller controls the output torque of the motor to be 0, otherwise the motor controller maintains controlling the motor based on the preset torque;

[0037] When the current speed is less than the preset maximum speed of the motor, and the current speed is less than the preset maximum speed of the motor for a period of time exceeding the first buffer period, the motor controller controls the output torque of the motor to be the preset torque;

[0038] When the current speed is greater than the preset maximum speed of the motor and less than or equal to the maximum speed allowed by the motor, and the current speed is greater than the preset maximum speed of the motor and less than or equal to the maximum speed allowed by the motor for a period of time exceeding the first buffer period, the motor controller calculates the deviation speed between the current speed and the preset maximum speed of the motor, otherwise the motor controller maintains controlling the motor based on the preset torque;

[0039] When the current rotation speed drops to the maximum rotation speed allowed by the motor, and the period from the current rotation speed dropping to the maximum rotation speed allowed by the motor continues to exceed the second buffer period, the current torque is maintained as the output torque of the motor.

[0040] Preferably, the motor controller calculates the ratio of the deviation speed to the preset maximum speed of the motor, multiplies the preset torque by the ratio to calculate the deviation torque, and subtracts the deviation torque from the preset torque as the update torque;

[0041] The motor controller controls the output torque of the motor to be the update torque.

[0042] Preferably, the change in the current rotational speed lags behind the change in the output torque based on a hysteresis time;

[0043] The motor controller linearly or nonlinearly decreases the preset torque to n% of the updated torque within the hysteresis time, where 80≤n<100;

[0044] When the current speed has an inflection point, the motor controller controls the current torque of the motor to be the updated torque and maintains it, so that the current speed gradually decreases to the preset maximum speed of the motor.

[0045] Preferably, when the preset torque or the preset maximum speed of the motor is changed to the latest torque or the latest maximum speed, the motor controller again compares the current speed with the latest maximum speed;

[0046] When the current speed is less than the latest maximum speed, the motor controller controls the output torque of the motor to be the latest torque;

[0047] When the current speed is greater than the latest maximum speed and less than or equal to the maximum allowable speed of the motor, the motor controller calculates the deviation speed between the current speed and the latest maximum speed, and calculates a deviation torque based on the deviation speed. The motor controller uses the deviation torque as a control variable to control the output torque of the motor to decrease step by step or instantaneously, and repeatedly compares the current speed and the latest maximum speed; when the current speed drops to the latest maximum speed, the current torque is maintained as the output torque of the motor, and the torque is modified and updated to be the current torque.

[0048] Compared with the prior art, the above technical solution has the following beneficial effects:

[0049] 1. The deviation torque calculated from the deviation speed is directly output to the motor as the control torque, which reduces the steps of torque superposition and can make the torque control error smaller. When the preset torque changes, it avoids the need to continuously calculate the control torque output by the motor controller, which can reduce the calculation amount of the motor controller and make the dynamic performance of the motor controller better. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 A schematic flow chart of a method for controlling the motor speed of a hybrid vehicle in accordance with a preferred embodiment of the present invention;

[0051] Figure 2 This is a schematic diagram of motor speed control and torque control waveforms in accordance with a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0052] The advantages of the present invention are further described below in conjunction with the accompanying drawings and specific embodiments.

[0053] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same 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 disclosure. Instead, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0054] The terms used in this disclosure are for the purpose of describing specific embodiments only and are not intended to limit the disclosure. The singular forms of "a", "said" and "the" used in this disclosure and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0055] It should be understood that although the terms first, second, third, etc. may be used in the present disclosure to describe various information, such information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present disclosure, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0056] In the description of the present invention, it is necessary to understand that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0057] In the description of the present invention, unless otherwise specified and limited, it should be noted that the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a mechanical connection or an electrical connection, or it can be the internal connection between two components. It can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances.

[0058] In the following description, the suffixes such as "module", "component" or "unit" used to represent elements are only used to facilitate the description of the present invention, and have no specific meanings. Therefore, "module" and "component" can be used interchangeably.

[0059] See also Figure 1, in order to comply with the motor speed control method of a hybrid vehicle in a preferred embodiment of the present invention, in this embodiment, the motor speed control method is executed in the torque loop control mode. In the torque loop control mode, the controlled host calculates the corresponding output torque according to the given speed instruction, and controls all slaves and the host to output according to the same torque, so that the motors driven by each inverter run with the same torque, and then the belt speed of each driving point is consistent. Usually, the "torque loop" is used as the normal (main control) control, and the "speed loop" is used as the (standby control) protection. In normal operation, the "speed loop" does not work, and the "torque loop" controls the output of each motor with the same torque, ensuring that the output of each motor is consistent, and maximally ensuring the consistency of the conveyor belt speed of each driving point. When the motor is blocked or skipped, and the motor speed changes beyond the set range, the system activates the "speed loop" to adjust the speed. When the speed returns to the set range, the "speed loop" automatically exits and re-enters the "torque loop" control. This not only ensures the consistency of the conveyor belt speed, but also ensures the consistency of the torque of each motor. In order to achieve the control of the motor speed, the control method includes the following steps:

[0060] S100: The motor controller is preset with: preset torque, maximum allowable motor speed, preset maximum motor speed, where the maximum allowable motor speed is greater than the preset maximum motor speed

[0061] There are multiple thresholds in the motor control, such as preset torque, maximum allowable motor speed, and preset maximum motor speed. The preset torque indicates the expected torque of the motor controller for the motor of the hybrid vehicle, and also indicates the output that the motor should have under the preset torque. The maximum allowable motor speed indicates the maximum speed that the motor can bear. Once the maximum allowable motor speed is exceeded, it will have a fatal effect on the motor. The preset maximum motor speed is a threshold set manually, which is less than the maximum allowable motor speed. It is a protection threshold for the motor speed. Although the motor speed can theoretically exceed the protection threshold, a safety can be set manually to prevent the motor speed from changing too quickly and exceeding the maximum allowable motor speed.

[0062] S200: The motor controller controls the motor of the hybrid vehicle based on the preset torque, collects the current speed of the motor in real time, and compares the current speed with the maximum speed allowed by the motor or the preset maximum speed of the motor

[0063] With the above setting value, the motor controller will first control the motor of the hybrid vehicle according to the preset torque, that is, when the motor is started or is already working, the motor torque is gradually (or at a preset increase speed) increased until the preset torque is reached, so that the hybrid vehicle operates under the desired working condition. At the same time, the motor controller will also collect the current speed of the motor in real time (including the torque increase process and the torque maintained at the preset torque process), and compare the collected current speed with the maximum speed allowed by the motor or the preset maximum speed of the motor, and make an execution result based on the comparison result.

[0064] S310: When the current speed is greater than the maximum speed allowed by the motor, the motor controller controls the output torque of the motor to 0

[0065] In this embodiment, the motor protection mechanism is maintained, and when the current speed is greater than the maximum speed allowed by the motor, the motor controller controls the output torque of the motor to be 0. It should be understood that step S310 performs an overspeed protection mechanism, and the motor speed control method in the present invention is a speed control mechanism. Even if the speed theoretically exceeds the preset maximum speed of the motor, it is still within the normal working range of the motor. Therefore, the setting of step S310 is to protect the motor and extend its service life.

[0066] S320: When the current speed is less than the preset maximum speed of the motor, the motor controller controls the output torque of the motor to be the preset torque

[0067] When the current speed is less than the preset maximum speed of the motor, it means that the motor speed is within the expected range, and the preset speed setting will not have any irresistible impact on the motor, and the output can be sustained. Therefore, the output torque of the motor is configured as the preset torque.

[0068] S330: When the current speed is greater than the preset maximum speed of the motor and less than or equal to the maximum speed allowed by the motor, the motor controller calculates the deviation speed between the current speed and the preset maximum speed of the motor, and calculates a deviation torque based on the deviation speed. The motor controller uses the deviation torque as a control variable to control the output torque of the motor to decrease step by step or instantaneously, and repeatedly compares the current speed with the preset maximum speed of the motor; when the current speed drops to the preset maximum speed of the motor, the current torque is maintained as the output torque of the motor

[0069] When the current speed is between the preset maximum speed of the motor and the maximum speed allowed by the motor, it means that the current speed is already in the range beyond expectation, and the speed of the motor needs to be limited. Therefore, the motor controller adopts the method of calculating the deviation speed between the current speed and the preset maximum speed of the motor, for example, direct subtraction, weighted subtraction, ratio calculation, weighted ratio calculation, etc. can be used to obtain the difference between the ideal speed and the current speed, and then a deviation torque is calculated based on the deviation speed, and the deviation torque is used as the basis for adjusting the preset torque, and its purpose is that after adjustment, the current speed can be reduced until the preset maximum speed of the motor. Therefore, the motor controller uses the deviation torque as the control variable (that is, the deviation torque can be used as the basis to make different control quantities, not limited to addition and subtraction) to control the output torque of the motor to decrease step by step or instantaneously, and repeatedly compares the current speed and the preset maximum speed of the motor. After repeatedly iterating the above steps, when the current speed drops to the preset maximum speed of the motor, the current torque is maintained as the output torque of the motor, and finally the motor speed is controlled, and the maximum torque is output at the maximum speed that can be achieved.

[0070] It can be understood that the above-mentioned step-by-step or instantaneous reduction in the output torque of the motor means that when the motor controller controls the output torque of the motor, it can be reduced from the preset torque to the value after removing the deviation torque in a short time. The deviation torque can also be decomposed into multiple parts, with a gradient of one part at a time, and adjusted according to the feedback of the current speed of the motor. The difference between the two is that the former is highly efficient but may cause waste of motor speed (for example, after too much adjustment, the speed will drop to the preset maximum speed of the motor), while the latter is relatively inefficient but has better regulation effect.

[0071] With the above configuration, compared with the prior art, the torque control method is a method in which the motor controller directly outputs a given torque without controlling the speed. By introducing feedback judgment of the motor speed, the motor is controlled not to exceed the set maximum speed. Since the deviation speed calculation is a function that is triggered only when the motor feedback speed exceeds the set maximum speed, the load on the motor controller will not increase much. The above process can be specifically completed in the torque output module in the motor controller.

[0072] In a preferred embodiment, in order to avoid the ping-pong effect, that is, if the current speed repeatedly changes around the preset maximum speed of the motor, resulting in a waste of load for constantly adjusting the preset torque. The motor controller is also preset with a first buffer period and a second buffer period. When the current speed is greater than the maximum speed allowed by the motor, and the current speed is greater than the rated speed for a continuous period exceeding the first buffer period (that is, not only the current speed needs to be greater than the maximum speed allowed by the motor, but the time when it is greater than the rated speed also needs to be continuously and uninterruptedly maintained for the first buffer period), the motor controller will control the output torque of the motor to 0, otherwise the motor controller maintains the control of the motor based on the preset torque. Of course, it is understandable that as a protection mechanism for the motor, the first buffer period can be set very small in the above judgment process, or even 0, that is, once it is exceeded, the output torque of the motor is immediately controlled to 0. When the current speed is less than the preset maximum speed of the motor, and the current speed is less than the preset maximum speed of the motor for a continuous period exceeding the first buffer period (i.e., not only the current speed needs to be less than the preset maximum speed of the motor, but the time it is less than needs to be continuously and uninterruptedly maintained for the first buffer period), the motor controller will control the output torque of the motor to be the preset torque, otherwise, according to the original torque (the previous torque has been controlled to be the preset torque or the current torque). When the current speed is greater than the preset maximum speed of the motor and is less than or equal to the maximum speed allowed by the motor, and the current speed is greater than the preset maximum speed of the motor and is less than or equal to the maximum speed allowed by the motor for a continuous period exceeding the first buffer period (i.e., not only the current speed needs to be greater than the preset maximum speed of the motor and is less than or equal to the maximum speed allowed by the motor, but the time it is maintained from falling into this range needs to be continuously and uninterruptedly maintained for the first buffer period), the motor controller will calculate the deviation speed between the current speed and the preset maximum speed of the motor, otherwise the motor controller maintains the motor control based on the preset torque. When the current speed drops to the maximum speed allowed by the motor, and the current speed drops to the maximum speed allowed by the motor for a period of time exceeding the second buffer period (i.e., not only does the current speed need to drop to the maximum speed allowed by the motor, but the time maintained from falling into the range needs to be continuous and uninterrupted for the second buffer period), the current torque is maintained as the output torque of the motor. With the above configuration, repeated jumps in speed, torque, etc. can be avoided.

[0073] In another preferred embodiment, step S330 includes:

[0074] S331: The motor controller calculates the ratio of the deviation speed to the preset maximum speed of the motor, multiplies the preset torque by the ratio to calculate the deviation torque, and subtracts the deviation torque from the preset torque as the update torque;

[0075] That is, the calculation of the deviation speed can be obtained by directly subtracting the current speed (e.g., 500n / s) from the preset maximum speed of the motor (e.g., 400n / s). After having the deviation speed, the deviation speed can be made into a ratio (e.g., 25%) with the preset maximum speed of the motor to indicate the current overspeed ratio of the motor. Then, based on the ratio, multiply it by the current preset torque to obtain the amount of torque excess as the deviation torque, and then subtract the deviation torque from the preset torque as the update torque. It can be understood that weighted calculation can also be performed during calculation. For example, after obtaining the above ratio, it is multiplied by a weighted value (which can be greater than 1 or less than 1). Under the conservative mechanism, the weighted value can be greater than 1, so that the update torque becomes smaller. Even if the speed is found to drop too much in the subsequent steps, it can be adjusted again; under the active mechanism, the weighted value can be greater than 1, so that the update torque becomes larger, forming a step-by-step adjustment method.

[0076] S332: The motor controller controls the output torque of the motor to be the updated torque.

[0077] Furthermore, the weighting method may be specifically configured as follows: Step S332 includes:

[0078] S332-1: The change of the current speed lags behind the change of the output torque by a hysteresis time;

[0079] The motor's speed change response is not as good as the motor controller's control change of the output torque. For example, when the motor controller finds that the current speed is greater than the motor's preset maximum speed, after adjusting the output torque, the motor's current speed change cannot keep up with the torque control change, and the speed will still increase until it responds. The time difference between the two changes is recorded as the hysteresis time.

[0080] S332-2: The motor controller linearly or nonlinearly decreases the preset torque to n% of the updated torque within the hysteresis time, where 80≤n<100;

[0081] Due to the above response hysteresis, when the motor controller detects that the current speed has changed and needs to control the output torque, the strategy it adopts is: over-adjustment. That is, within the hysteresis time (for example, 300ms or 500ms), the motor controller controls the preset torque to be reduced to the updated torque. The reduction process can be linear (such as Figure 2 As shown in the figure, or nonlinear (such as step type, or curve type, and the down-regulation speed gradually increases or decreases). In response to the over-adjustment, the current speed of the motor will gradually decrease after the hysteresis time, and due to the execution of the over-adjustment, the down-regulation speed can be increased so that the motor responds to the torque adjustment as quickly as possible.

[0082] S332-3: When the current speed reaches an inflection point, the motor controller controls the current torque of the motor to be the updated torque and maintains it, so that the current speed gradually decreases to the preset maximum speed of the motor.

[0083] Continuing as described above, after the hysteresis time, the starting point of the current speed drop of the motor is reflected as an inflection point on the waveform. After the motor controller detects the inflection point, it can be realized that the torque control of the motor has been effective, and the motor will control the current torque of the motor to return to the updated torque and maintain it, so that the current speed gradually decreases to the preset maximum speed of the motor. In other words, the design of step S332-2 is to increase the current speed drop speed as much as possible when the adjustment of the current speed of the motor inevitably encounters the hysteresis time, so as to avoid the damage problem caused by the current speed rising too fast, resulting in the current speed of the motor rising from the preset maximum speed of the motor to the maximum speed allowed by the motor during the hysteresis time.

[0084] In another preferred embodiment, the motor speed control method further comprises the following steps:

[0085] S400: When the preset torque or the preset maximum speed of the motor is changed to the latest torque or the latest maximum speed, the motor controller compares the current speed with the latest maximum speed again;

[0086] When the factory preset torque or the motor preset maximum speed is manually modified to the latest torque or the latest maximum speed, the motor controller will compare the latest modified current speed with the latest maximum speed.

[0087] S510: When the current speed is less than the latest maximum speed, the motor controller controls the output torque of the motor to be the latest torque;

[0088] Similar to the aforementioned buffer mechanism, when the preset maximum speed of the motor is increased so that the current speed is less than the latest maximum speed, it will be considered that no torque change is required, and the motor controller controls the output torque of the motor to be the latest torque.

[0089] S520: When the current speed is greater than the latest maximum speed and less than or equal to the maximum allowable speed of the motor, the motor controller calculates the deviation speed between the current speed and the latest maximum speed, and calculates a deviation torque based on the deviation speed. The motor controller uses the deviation torque as a control variable to control the output torque of the motor to decrease step by step or instantaneously, and repeatedly compares the current speed and the latest maximum speed; when the current speed drops to the latest maximum speed, the current torque is maintained as the output torque of the motor, and the torque is modified and updated to be the current torque.

[0090] As in the aforementioned embodiment, the monitoring and comparison process will be repeatedly iterated to ensure that at any time, once the current speed is greater than the latest maximum speed and less than or equal to the maximum allowable speed of the motor, the output torque of the motor will be adjusted until the current speed falls back to within the threshold of the latest maximum speed.

[0091] The present invention also discloses a motor speed control system for a hybrid vehicle, which is executed in a torque loop control mode, and includes: a motor controller, which is preset with: a preset torque, a maximum allowable motor speed, a preset maximum motor speed, wherein the maximum allowable motor speed is greater than the preset maximum motor speed; a motor, which is arranged in the hybrid vehicle and controlled by the motor controller; the motor controller controls the motor of the hybrid vehicle based on the preset torque, and collects the current speed of the motor in real time, and compares the current speed with the maximum allowable motor speed or the preset maximum speed of the motor; when the current speed is greater than the maximum allowable motor speed, the motor controller controls the output torque of the motor to be 0; when the current speed is less than the preset maximum speed of the motor, the motor controller controls the output torque of the motor to be the preset torque; when the current speed is greater than the preset maximum speed of the motor and less than or equal to the maximum allowable motor speed, the motor controller calculates the deviation speed between the current speed and the preset maximum speed of the motor, and calculates a deviation torque according to the deviation speed, and the motor controller uses the deviation torque as a control variable to control the output torque of the motor to decrease step by step or instantaneously, and repeatedly compares the current speed with the preset maximum speed of the motor; when the current speed drops to the preset maximum speed of the motor, the current torque is maintained as the output torque of the motor.

[0092] Preferably, a first buffer period and a second buffer period are also preset in the motor controller; when the current speed is greater than the maximum allowable speed of the motor, and the current speed has been greater than the rated speed for a continuous period exceeding the first buffer period, the motor controller controls the output torque of the motor to be 0, otherwise the motor controller maintains controlling the motor based on the preset torque; when the current speed is less than the preset maximum speed of the motor, and the current speed is less than the preset maximum speed of the motor for a continuous period exceeding the first buffer period, the motor controller controls the output torque of the motor to be the preset torque; when the current speed is greater than the preset maximum speed of the motor and is less than or equal to the maximum allowable speed of the motor, and the current speed is greater than the preset maximum speed of the motor and is less than or equal to the maximum allowable speed of the motor for a continuous period exceeding the first buffer period, the motor controller calculates the deviation speed between the current speed and the preset maximum speed of the motor, otherwise the motor controller maintains controlling the motor based on the preset torque; when the current speed drops to the maximum allowable speed of the motor, and the current speed drops to the maximum allowable speed of the motor for a continuous period exceeding the second buffer period, the current torque is maintained as the output torque of the motor.

[0093] Preferably, the motor controller calculates the ratio of the deviation speed to the preset maximum speed of the motor, multiplies the preset torque by the ratio to calculate the deviation torque, and subtracts the deviation torque from the preset torque as the update torque; the motor controller controls the output torque of the motor to be the update torque.

[0094] Preferably, the change in the current speed lags behind the change in the output torque based on a hysteresis time; the motor controller linearly or nonlinearly reduces the preset torque to n% of the updated torque within the hysteresis time, where 80≤n<100; when the current speed has an inflection point, the motor controller controls the current torque of the motor to be the updated torque and maintains it, so that the current speed gradually decreases to the preset maximum speed of the motor.

[0095] Preferably, when the preset torque or the preset maximum speed of the motor is changed to the latest torque or the latest maximum speed, the motor controller compares the current speed with the latest maximum speed again; when the current speed is less than the latest maximum speed, the motor controller controls the output torque of the motor to be the latest torque; when the current speed is greater than the latest maximum speed and less than or equal to the maximum allowable speed of the motor, the motor controller calculates the deviation speed between the current speed and the latest maximum speed, and calculates a deviation torque based on the deviation speed. The motor controller uses the deviation torque as the control variable to control the output torque of the motor to decrease step by step or instantaneously, and repeatedly compares the current speed and the latest maximum speed; when the current speed drops to the latest maximum speed, the current torque is maintained as the output torque of the motor, and the torque is modified and updated to be the current torque.

[0096] It should be noted that the embodiments of the present invention have better practicability and do not impose any form of limitation on the present invention. Any technician familiar with the field may use the technical content disclosed above to change or modify it into an equivalent effective embodiment. However, any modification or equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for controlling the motor speed of a hybrid vehicle, characterized in that: The motor speed control method is executed in a torque loop control mode, comprising the following steps: The motor controller is preset with: preset torque, maximum allowable motor speed, and preset maximum motor speed, wherein the maximum allowable motor speed is greater than the preset maximum motor speed; The motor controller controls the motor of the hybrid vehicle based on the preset torque, collects the current speed of the motor in real time, and compares the current speed with the maximum speed allowed by the motor or the preset maximum speed of the motor; When the current speed is greater than the maximum allowable speed of the motor, the motor controller controls the output torque of the motor to be 0; When the current speed is less than the preset maximum speed of the motor, the motor controller controls the output torque of the motor to be the preset torque; When the current speed is greater than the preset maximum speed of the motor and less than or equal to the maximum allowable speed of the motor, the motor controller calculates the deviation speed between the current speed and the preset maximum speed of the motor, and calculates a deviation torque according to the deviation speed. The motor controller uses the deviation torque as a control variable to control the output torque of the motor to decrease step by step or instantaneously, and repeatedly compares the current speed with the preset maximum speed of the motor; when the current speed drops to the preset maximum speed of the motor, the current torque is maintained as the output torque of the motor; When the current speed is greater than the preset maximum speed of the motor and less than or equal to the maximum allowable speed of the motor, the motor controller calculates the deviation speed between the current speed and the preset maximum speed of the motor, and calculates a deviation torque according to the deviation speed. The step of the motor controller controlling the output torque of the motor to be reduced step by step or instantaneously using the deviation torque as a control variable includes: The motor controller calculates the ratio of the deviation speed to the preset maximum speed of the motor, multiplies the preset torque by the ratio to calculate the deviation torque, and subtracts the deviation torque from the preset torque as an update torque; the motor controller controls the output torque of the motor to be the update torque; The step of controlling the output torque of the motor to be the updated torque by the motor controller comprises: The change of the current rotation speed lags behind the change of the output torque based on a hysteresis time; The motor controller linearly or nonlinearly decreases the preset torque to n% of the updated torque within the hysteresis time, where 80≤n<100; When the current speed has an inflection point, the motor controller controls the current torque of the motor to be an updated torque and maintains it, so that the current speed gradually decreases to a preset maximum speed of the motor.

2. The motor speed control method according to claim 1, characterized in that: The motor controller is also preset with a first buffer period and a second buffer period; When the current speed is greater than the maximum speed allowed by the motor, and the current speed is greater than a rated speed for more than the first buffer period, the motor controller controls the output torque of the motor to be 0, otherwise the motor controller maintains controlling the motor based on the preset torque; When the current speed is less than the preset maximum speed of the motor, and the current speed has been less than the preset maximum speed of the motor for more than the first buffer period, the motor controller controls the output torque of the motor to be the preset torque; When the current speed is greater than the preset maximum speed of the motor and less than or equal to the maximum speed allowed by the motor, and the current speed is greater than the preset maximum speed of the motor and less than or equal to the maximum speed allowed by the motor for a period of time exceeding the first buffer period, the motor controller calculates the deviation speed between the current speed and the preset maximum speed of the motor, otherwise the motor controller maintains controlling the motor based on the preset torque; When the current speed drops to the maximum speed allowed by the motor, and the period from the current speed dropping to the maximum speed allowed by the motor continues to exceed the second buffer period, the current torque is maintained as the output torque of the motor.

3. The motor speed control method according to claim 1, characterized in that: The following steps are also included: When the preset torque or the preset maximum speed of the motor is changed to the latest torque or the latest maximum speed, the motor controller compares the current speed with the latest maximum speed again; When the current rotation speed is less than the latest maximum rotation speed, the motor controller controls the output torque of the motor to be the latest torque; When the current speed is greater than the latest maximum speed and less than or equal to the maximum allowable speed of the motor, the motor controller calculates the deviation speed between the current speed and the latest maximum speed, and calculates a deviation torque based on the deviation speed. The motor controller uses the deviation torque as a control variable to control the output torque of the motor to decrease step by step or instantaneously, and repeatedly compares the current speed and the latest maximum speed; when the current speed drops to the latest maximum speed, the current torque is maintained as the output torque of the motor, and the updated torque is modified to the current torque.

4. A motor speed control system for a hybrid vehicle, characterized in that: The motor speed control system is executed in a torque loop control mode, including: A motor controller, wherein the following are preset: a preset torque, a maximum allowable speed of the motor, and a preset maximum speed of the motor, wherein the maximum allowable speed of the motor is greater than the preset maximum speed of the motor; a motor, arranged in the hybrid vehicle and controlled by the motor controller; The motor controller controls the motor of the hybrid vehicle based on the preset torque, collects the current speed of the motor in real time, and compares the current speed with the maximum speed allowed by the motor or the preset maximum speed of the motor; When the current speed is greater than the maximum allowable speed of the motor, the motor controller controls the output torque of the motor to be 0; When the current speed is less than the preset maximum speed of the motor, the motor controller controls the output torque of the motor to be the preset torque; When the current speed is greater than the preset maximum speed of the motor and less than or equal to the maximum allowable speed of the motor, the motor controller calculates the deviation speed between the current speed and the preset maximum speed of the motor, and calculates a deviation torque according to the deviation speed. The motor controller uses the deviation torque as a control variable to control the output torque of the motor to decrease step by step or instantaneously, and repeatedly compares the current speed with the preset maximum speed of the motor; when the current speed drops to the preset maximum speed of the motor, the current torque is maintained as the output torque of the motor; The motor controller calculates the ratio of the deviation speed to the preset maximum speed of the motor, multiplies the preset torque by the ratio to calculate the deviation torque, and subtracts the deviation torque from the preset torque as an update torque; the motor controller controls the output torque of the motor to be the update torque; The change of the current rotation speed lags behind the change of the output torque based on a hysteresis time; The motor controller linearly or nonlinearly decreases the preset torque to n% of the updated torque within the hysteresis time, where 80≤n<100; When the current speed has an inflection point, the motor controller controls the current torque of the motor to be an updated torque and maintains it, so that the current speed gradually decreases to a preset maximum speed of the motor.

5. The motor speed control system according to claim 4, characterized in that: The motor controller is also preset with a first buffer period and a second buffer period; When the current speed is greater than the maximum speed allowed by the motor, and the current speed is greater than a rated speed for more than the first buffer period, the motor controller controls the output torque of the motor to be 0, otherwise the motor controller maintains controlling the motor based on the preset torque; When the current speed is less than the preset maximum speed of the motor, and the current speed has been less than the preset maximum speed of the motor for more than the first buffer period, the motor controller controls the output torque of the motor to be the preset torque; When the current speed is greater than the preset maximum speed of the motor and less than or equal to the maximum speed allowed by the motor, and the current speed is greater than the preset maximum speed of the motor and less than or equal to the maximum speed allowed by the motor for a period of time exceeding the first buffer period, the motor controller calculates the deviation speed between the current speed and the preset maximum speed of the motor, otherwise the motor controller maintains controlling the motor based on the preset torque; When the current speed drops to the maximum speed allowed by the motor, and the period from the current speed dropping to the maximum speed allowed by the motor continues to exceed the second buffer period, the current torque is maintained as the output torque of the motor.

6. The motor speed control system according to claim 4, characterized in that: When the preset torque or the preset maximum speed of the motor is changed to the latest torque or the latest maximum speed, the motor controller compares the current speed with the latest maximum speed again; When the current rotation speed is less than the latest maximum rotation speed, the motor controller controls the output torque of the motor to be the latest torque; When the current speed is greater than the latest maximum speed and less than or equal to the maximum allowable speed of the motor, the motor controller calculates the deviation speed between the current speed and the latest maximum speed, and calculates a deviation torque based on the deviation speed. The motor controller uses the deviation torque as a control variable to control the output torque of the motor to decrease step by step or instantaneously, and repeatedly compares the current speed and the latest maximum speed; when the current speed drops to the latest maximum speed, the current torque is maintained as the output torque of the motor, and the updated torque is modified to the current torque.

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