A method for starting a range extender

Abstract

The application discloses a starting method of a range extender, and the method comprises the following steps: an engine controller acquires the current water temperature and the current rotating speed of the engine; the engine controller acquires a first torque value corresponding to the current water temperature and the current rotating speed; the engine controller acquires a second torque value according to the difference between the current rotating speed and a target rotating speed of the engine; the engine controller acquires the sum of the first torque value and the second torque value as a current target torque value; a generator controller controls the generator to respond to the target torque value; the engine controller judges whether the rotating speed of the engine reaches the target rotating speed; if the engine controller judges that the rotating speed of the engine does not reach the target rotating speed, the above steps are re-executed; if the engine controller judges that the rotating speed of the engine reaches the target rotating speed, an engine controller controls an actuator to inject oil and ignite. The application has a torque baseline for torque adjustment in the starting process, reduces the adjustment range, and makes the starting process converge faster.

Description

Technical Field

[0001] This invention relates to the field of hybrid vehicle technology, and more specifically to a method for starting a range extender. Background Technology

[0002] A range extender generally refers to a component of an electric vehicle that provides additional electrical energy, thereby increasing the driving range of the vehicle. Traditionally, a range extender refers to a combination of an engine and a generator. A range-extended electric vehicle (REEV) is an electric vehicle that uses other energy sources (such as gasoline) to replenish its electrical power when the battery is low. The main operating characteristic (concept) of an electric vehicle is that it operates in pure electric mode most of the time (high probability), and in range-extending mode in a few cases (low probability). That is, the electrical energy generated by the range extender powers the motor through the battery and can also charge the battery.

[0003] The current starting strategy for range extenders typically involves the Vehicle Control Unit (VCU) sending a start command to the Generator Control Unit (GCU) and Engine Control System (EMS). The GCU then enters torque mode, where the VCU sends torque commands in real-time. The GCU controls the generator to respond to the VCU's torque request and rotates the engine. Once the target speed α is reached, the EMS controls the corresponding actuators to inject fuel and ignite. The GCU then switches to speed mode, completing the start-up process. Under this strategy, the torque request sent by the VCU often starts from zero and is calculated using PID control based on the difference between the actual and target speeds, resulting in a relatively slow start-up process. Summary of the Invention

[0004] In view of this, embodiments of the present invention provide a method for starting a range extender to solve the problem of slow startup process when using existing range extender startup strategies.

[0005] This invention provides a method for starting a range extender, comprising:

[0006] S101: The vehicle controller obtains the current coolant temperature and current engine speed of the engine;

[0007] S102: The vehicle controller obtains the corresponding first torque value based on the current water temperature and the current speed;

[0008] S103: The vehicle controller obtains the second torque value based on the difference between the current speed and the target speed of the engine;

[0009] S104: The vehicle controller obtains the sum of the first torque value and the second torque value as the current target torque value;

[0010] S105: The generator controller controls the generator to respond to the target torque value;

[0011] S106: The engine controller determines whether the engine speed has reached the target speed;

[0012] If the engine controller determines that the engine speed has not reached the target speed, proceed to step S101;

[0013] S107: When the engine controller determines that the engine speed has reached the target speed, the engine controller controls the actuator to inject fuel and ignite.

[0014] In some optional implementations, the vehicle controller obtains a corresponding first torque value based on the current water temperature and the current engine speed, including:

[0015] The vehicle controller acquires the correspondence between water temperature, engine speed, and the first torque value;

[0016] The vehicle controller obtains the first torque value corresponding to the current water temperature and the current speed according to the correspondence.

[0017] In some optional implementations, before the vehicle controller acquires the correspondence between the water temperature, engine speed, and the first torque value, it further includes:

[0018] Obtain multiple first preset water temperatures and multiple preset torque values;

[0019] For each of the first preset water temperatures, the engine speed and engine start-up evaluation parameters are obtained when the generator output torque is maintained at each preset torque value, during the engine start-up process.

[0020] The first correspondence between the first preset water temperature, the preset torque value, and the rotational speed is determined based on the start-up evaluation parameters as the correspondence relationship.

[0021] In some optional implementations, the startup evaluation parameters include speed overshoot, startup time, and / or stable convergence rate.

[0022] In some optional embodiments, the minimum value of the first preset water temperature is a temperature value between -50°C and -30°C; and / or,

[0023] The interval between adjacent first preset water temperatures is an interval value between 3 and 10°C.

[0024] In some alternative implementations, the difference between adjacent preset torque values ​​is a value between 3 Nm and 10 Nm.

[0025] In some optional implementations, before the vehicle controller acquires the correspondence between the water temperature, engine speed, and the first torque value, it further includes:

[0026] Obtain multiple second preset water temperatures;

[0027] For each of the second preset water temperatures, if the engine water temperature reaches the second preset water temperature during engine operation, stop driving the engine and test the engine's reverse drag torque at different speeds;

[0028] The third torque value corresponding to different engine speeds at the second preset water temperature is obtained based on the back-dragging torque, and a second correspondence between the second preset water temperature, engine speed and the third torque value is established as the correspondence.

[0029] In some optional implementations, obtaining the third torque value corresponding to different engine speeds at the second preset water temperature based on the reversing torque includes:

[0030] The third torque value is obtained by multiplying the dragging torque by a preset coefficient.

[0031] In some optional implementations, the vehicle controller obtains a second torque value based on the difference between the current engine speed and the target engine speed, including:

[0032] The vehicle controller performs PID calculations based on the difference to obtain the second torque value.

[0033] The range extender starting method provided in this invention offers a novel torque calculation method for the starting process, establishing a torque baseline (i.e., a first torque value) for torque adjustment during startup, thus narrowing the adjustment range and enabling faster convergence during startup. Furthermore, the first torque value is determined based on the engine's current coolant temperature and speed, meaning this starting process can adapt to various operating conditions, achieving a good NVH experience across all operating conditions. This invention addresses the shortcomings of slow convergence and insufficient operating condition coverage in range extender starting strategies. Attached Figure Description

[0034] The features and advantages of the invention will be more clearly understood by referring to the accompanying drawings, which are schematic and should not be construed as limiting the invention in any way. In the drawings:

[0035] Figure 1 A flowchart illustrating a method for starting a range extender according to an embodiment of the present invention;

[0036] Figure 2 A flowchart illustrating another method for starting a range extender provided in an embodiment of the present invention;

[0037] Figure 3 This is a flowchart illustrating another method for starting a range extender provided in an embodiment of the present invention. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] It should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. In the following descriptions of embodiments, "a plurality of" means two or more, unless otherwise expressly specified.

[0040] Please see Figure 1 This invention provides a method for starting a range extender, comprising:

[0041] S101: The vehicle controller obtains the current coolant temperature and current speed of the engine; before this step, the vehicle controller can send the range extender start command to the generator controller and the engine controller, and the generator controller enters torque mode (or torque mode).

[0042] Among them, the vehicle controller is the main controller of the vehicle's power system. It is responsible for managing the entire powertrain and determines the torque distribution of the engine and motor, the opening and closing of high voltage electricity, engine starting or stopping, accessory enabling, and other operations based on the driver's driving intentions, the overall vehicle driving status, and the operating status of various vehicle components (including the engine, transmission, motor, battery, etc.).

[0043] Optionally, the vehicle controller collects various switch and sensor signals related to vehicle control; it achieves coordinated control of the engine controller, transmission controller (TCU), battery management system (BMS), and motor controller through command and data interaction via the CAN bus; and it controls accessories such as the starter motor, fan, and water pump through multiple relays. Furthermore, it can achieve high energy efficiency through on-the-go charging and regenerative braking.

[0044] S102: The vehicle controller obtains the corresponding first torque value based on the current water temperature and the current speed;

[0045] S103: The vehicle controller obtains the second torque value based on the difference between the current speed and the target speed of the engine;

[0046] S104: The vehicle controller obtains the sum of the first torque value and the second torque value as the current target torque value;

[0047] Specifically, after obtaining the target torque value, the vehicle controller will send the target torque value to the generator controller;

[0048] S105: The generator controller controls the generator to respond to the target torque value;

[0049] S106: The engine controller determines whether the engine speed has reached the target speed;

[0050] If the engine controller determines that the engine speed has not reached the target speed, proceed to step S101;

[0051] S107: When the engine controller determines that the engine speed has reached the target speed, the engine controller controls the actuator to inject fuel and ignite. After successful ignition, the generator controller enters the speed mode.

[0052] The range extender starting method provided in this invention offers a novel torque calculation method for the starting process, establishing a torque baseline (i.e., a first torque value) for torque adjustment, narrowing the adjustment range, and enabling faster convergence during the starting process. In other words, compared to existing range extender starting technologies where the generator's response torque starts from zero and is calculated solely based on the difference between the actual and target engine speeds, this invention starts the required response torque from a first torque value. A second torque value, obtained based on the difference between the engine's current and target speeds, is then added as the current required generator response torque. Furthermore, the first torque value is determined based on the engine's current coolant temperature and engine speed, meaning this starting process can adapt to various operating conditions and achieves a better NVH (Noise, Vibration, and Harshness) experience across all operating conditions. This invention addresses the shortcomings of slow convergence and insufficient operating condition coverage in range extender starting strategies.

[0053] In some specific implementations, the vehicle controller obtains a corresponding first torque value based on the current water temperature and the current engine speed, including:

[0054] The vehicle controller acquires the correspondence between water temperature, engine speed, and the first torque value;

[0055] The vehicle controller obtains the first torque value corresponding to the current water temperature and the current speed according to the correspondence.

[0056] Specifically, this correspondence can be recorded in a correspondence table.

[0057] For some specific implementation methods, please refer to Figure 2 Before the vehicle controller acquires the correspondence between water temperature, engine speed, and the first torque value, it further includes:

[0058] Obtain multiple first preset water temperatures and multiple preset torque values;

[0059] For each of the first preset water temperatures, the engine speed and engine start-up evaluation parameters are obtained when the generator output torque is maintained at each preset torque value, during the engine start-up process.

[0060] The first correspondence between the first preset water temperature, the preset torque value, and the rotational speed is determined based on the start-up evaluation parameters as the correspondence relationship.

[0061] In this embodiment of the invention, the optimal torque value corresponding to water temperature and rotation speed is obtained through actual testing.

[0062] The startup evaluation parameters include speed overshoot, startup time, and / or stable convergence speed.

[0063] Specifically, for each combination of the first preset water temperature and speed, the preset torque value corresponding to the shortest start-up time is selected as the optimal preset torque value. If there are multiple preset torque values ​​corresponding to the shortest start-up time, the preset torque value corresponding to the shortest speed overshoot is selected as the optimal preset torque value. If there are still multiple preset torque values ​​corresponding to the shortest speed overshoot, the preset torque value corresponding to the fastest stable convergence speed is selected as the optimal preset torque value.

[0064] Alternatively, for each combination of the first preset water temperature and speed, calculate the weighted sum of the speed overshoot, start-up time, and / or stable convergence speed corresponding to each preset torque value, and select the preset torque value corresponding to the minimum weighted sum as the optimal torque value. The weights of start-up time, speed overshoot, and stable convergence speed decrease sequentially.

[0065] For each combination of the first preset water temperature and speed, after determining the corresponding optimal preset torque value, the first correspondence between the first preset water temperature, speed and preset torque value is established.

[0066] In some specific embodiments, the minimum value of the first preset water temperature is a temperature value between -50℃ and -30℃; and / or,

[0067] The interval between adjacent first preset water temperatures is an interval value between 3 and 10°C.

[0068] In some specific implementations, the difference between adjacent preset torque values ​​is a value between 3 Nm and 10 Nm.

[0069] For example, starting from -40℃, a set of data can be tested at 5℃ intervals. This set of data includes: the changing engine speed and engine start-up evaluation parameters during the process of starting the engine while maintaining the generator's output torque at a preset torque value; where there are multiple preset torque values, with a minimum of 0 Nm and a maximum of 100 Nm, and an interval of 5 Nm between adjacent preset torque values. Then, based on the start-up time (defined as the time from the start of startup to the speed converging and stabilizing at the target value) (the shorter the time, the better, but the speed overshoot needs to be <300 rpm), the optimal preset torque value corresponding to different temperatures and speeds can be selected, and a correspondence table can be formed. Finally, this correspondence table can be written into the vehicle controller program.

[0070] In addition, the above tests do not have to be vehicle tests, but rather tests conducted during the production phase on the engine and generator. This allows the engine coolant temperature to be controlled by the coolant temperature regulation equipment, preventing the coolant temperature from rising continuously during engine startup and affecting the accuracy of the test results.

[0071] For other specific implementation methods, please refer to Figure 3 Before the vehicle controller acquires the correspondence between water temperature, engine speed, and the first torque value, it further includes:

[0072] Obtain multiple second preset water temperatures;

[0073] For each of the second preset water temperatures, if the engine water temperature reaches the second preset water temperature during engine operation, stop driving the engine and test the engine's reverse drag torque at different speeds;

[0074] Specifically, the reverse drag torque can be measured using an electric dynamometer;

[0075] The third torque value corresponding to different engine speeds at the second preset water temperature is obtained based on the back-dragging torque, and a second correspondence between the second preset water temperature, engine speed and the third torque value is established as the correspondence.

[0076] In this embodiment of the invention, the optimal torque value corresponding to the water temperature and speed is also obtained by testing. However, unlike the above embodiment, the torque value corresponding to each water temperature and speed is obtained by testing the reverse drag torque corresponding to different speeds when the engine and motor stop at different water temperatures.

[0077] In some specific embodiments, obtaining the third torque value corresponding to different engine speeds at the second preset water temperature based on the reversing torque includes:

[0078] The third torque value is obtained by multiplying the dragging torque by a preset coefficient.

[0079] Since the main resistance during engine starting comes from the engine's mechanical resistance, the starting torque value in this embodiment of the invention is strongly related to the engine's resistance. This dragging torque reflects the engine's resistance curve. The preset coefficient can be set based on experience. Generally, a value is set based on experience, and then verified and fine-tuned. The principle of verification and fine-tuning is still that the shortest starting time is optimal within the range where the speed overshoot meets the requirements.

[0080] For example, an electric dynamometer can be used to warm up the engine from -40°C, stopping it every 5°C to test the drag torque at different speeds. The measured drag torque is then multiplied by a preset coefficient Y to obtain the third torque value. Finally, a table showing the correspondence between water temperature, speed, and torque values ​​is generated and written into the vehicle controller program. If, during testing, the water temperature exceeds a certain value after a measurement, cooling equipment is used to lower the water temperature, or the water temperature is allowed to cool naturally to a certain temperature before the next temperature stop test. This ensures that the stop temperature at the next test is the sum of the stop temperature at the current test and the temperature interval (here, 5°C). However, if the water temperature exceeds a certain value after the current measurement and no cooling is performed, the water temperature at the next test can only be greater than, but not equal to, this will result in a missing test result at that temperature.

[0081] Of course, the test in this embodiment of the invention may not be a whole vehicle test, but a test of the engine and generator during the production stage. In this way, the engine water temperature can be controlled by the water temperature regulating device, so that the shutdown temperature interval between two adjacent tests can be kept at a preset temperature interval (5°C in this case). This avoids the water temperature from rising continuously during engine start-up, requiring a cooling process before the next test can be carried out, which would affect the test progress.

[0082] In the above embodiments, the correspondence between water temperature, rotation speed and torque obtained by testing is discrete. When actually obtaining the corresponding first torque value based on the current water temperature and the current rotation speed, if the current water temperature is not equal to any water temperature in the corresponding relationship and / or the current rotation speed is not equal to any rotation speed in the corresponding relationship, then the first torque value corresponding to the current water temperature and the current rotation speed can be obtained by interpolation.

[0083] The specific interpolation method that can be used is the polynomial interpolation method. This method involves finding an nth-degree polynomial curve that passes through the discrete points of water temperature, speed, and corresponding torque, and then using this nth-degree polynomial curve to calculate the torque corresponding to other water temperatures and speeds.

[0084] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0085] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk drive (HDD), or solid-state drive (SSD), etc.; the storage medium can also include combinations of the above types of memory.

[0086] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for starting a range extender, characterized in that, include: S101: The vehicle controller obtains the current coolant temperature and current engine speed of the engine; S102: The vehicle controller obtains the corresponding first torque value based on the current water temperature and the current speed; S103: The vehicle controller obtains the second torque value based on the difference between the current speed and the target speed of the engine; S104: The vehicle controller obtains the sum of the first torque value and the second torque value as the current target torque value; S105: The generator controller controls the generator to respond to the target torque value; S106: The engine controller determines whether the engine speed has reached the target speed; If the engine controller determines that the engine speed has not reached the target speed, proceed to step S101; S107: When the engine controller determines that the engine speed has reached the target speed, the engine controller controls the actuator to inject fuel and ignite; In step S102, the vehicle controller obtains the corresponding first torque value based on the current water temperature and the current engine speed, including: The vehicle controller acquires the correspondence between water temperature, engine speed, and the first torque value; The vehicle controller obtains the first torque value corresponding to the current water temperature and the current speed according to the correspondence; Before the vehicle controller acquires the correspondence between water temperature, engine speed, and the first torque value, it also includes: Obtain multiple first preset water temperatures and multiple preset torque values; For each of the first preset water temperatures, the engine speed and engine start-up evaluation parameters are obtained when the generator output torque is maintained at each preset torque value; the start-up evaluation parameters include speed overshoot, start-up time, and stable convergence speed. The first correspondence between the first preset water temperature, the preset torque value, and the rotational speed is determined based on the startup evaluation parameters as the correspondence relationship. For each combination of the first preset water temperature and speed, the preset torque value corresponding to the shortest start-up time is selected as the optimal preset torque value. If there are multiple preset torque values ​​corresponding to the shortest start-up time, the preset torque value corresponding to the shortest speed overshoot is selected as the optimal preset torque value. If there are still multiple preset torque values ​​corresponding to the shortest speed overshoot, the preset torque value corresponding to the fastest stable convergence speed is selected as the optimal preset torque value. Alternatively, for each combination of the first preset water temperature and speed, the weighted sum of speed overshoot, start-up time, and stable convergence speed corresponding to each preset torque value is calculated, and the preset torque value corresponding to the minimum weighted sum is selected as the optimal torque value. For each combination of the first preset water temperature and rotation speed, after determining the corresponding optimal preset torque value, the first correspondence between the first preset water temperature, the rotation speed, and the preset torque value is established.

2. The method according to claim 1, characterized in that, The minimum value of the first preset water temperature is a temperature value between -50℃ and -30℃; and / or, The interval between adjacent first preset water temperatures is an interval value between 3 and 10°C.

3. The method according to claim 1, characterized in that, The difference between adjacent preset torque values ​​is a value between 3 Nm and 10 Nm.

4. The method according to claim 1, characterized in that, Before the vehicle controller acquires the correspondence between water temperature, engine speed, and the first torque value, it also includes: Obtain multiple second preset water temperatures; For each of the second preset water temperatures, if the engine water temperature reaches the second preset water temperature during engine operation, stop driving the engine and test the engine's reverse drag torque at different speeds; The third torque value corresponding to different engine speeds at the second preset water temperature is obtained based on the back-dragging torque, and a second correspondence between the second preset water temperature, engine speed and the third torque value is established as the correspondence.

5. The method according to claim 4, characterized in that, The step of obtaining the third torque value corresponding to different engine speeds at the second preset water temperature based on the reversing torque includes: The third torque value is obtained by multiplying the dragging torque by a preset coefficient.

6. The method according to claim 1, characterized in that, The vehicle controller obtains a second torque value based on the difference between the current engine speed and the target engine speed, including: The vehicle controller performs PID calculations based on the difference to obtain the second torque value.

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