A starting method for an engine of a multi - energy system

Abstract

The present invention discloses a method for starting an engine of a multi - energy system. The multi - energy system includes: a power battery module, a fuel cell module, a power generation module, and a drive motor module. The power generation module includes an engine and a generator connected to the engine. The power battery module, the fuel cell module, the power generation module, and the drive motor module are all electrically connected to each other. In the engine start - up control method: when starting is required, the type of the current energy source is judged, and an engine start - up mode corresponding to the current energy source type is selected. The method for starting an engine of the multi - energy system of the present invention can adapt to the start - up operations under different energy source types in the multi - energy system, so that the success rate of engine start - up is improved compared with the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of engine control, and particularly relates to a method for starting an engine of a multi - energy system. Background Art

[0002] The demand for energy conservation and emission reduction of commercial vehicles is increasing day by day. Commercial vehicles with multi - energy systems have particularly obvious carbon reduction effects throughout the vehicle's entire life cycle, and have become an important research direction for the development of new energy technologies for commercial vehicles. How to coordinate the operation of the multi - energy system is the key to current related technical research and engineering applications.

[0003] While the multi - energy system has a power battery module, a fuel cell module, and an engine - generator system for supplying energy to the drive motor, it is also necessary to consider the energy coordination during the start - stop control process between each system. Especially during the start - up process of the engine - generator system, how to ensure the rapid and smooth start of the engine is a difficult problem to be solved urgently in the control process of the multi - energy system.

[0004] The patent with the patent number CN104773159A discloses a method and system for controlling the start of an engine of a hybrid vehicle. When an engine start command is detected, the torque of the generator is coordinated to increase the engine speed. When the engine speed reaches the target value, the engine is controlled to work coordinately to achieve the ignition start of the engine. Although this patent can effectively solve the problems of large noise and vibration caused by over - shooting during the existing start - up process, it does not consider the coordination problem of the energy source of the generator and cannot adapt to the engine start - up process under different energy source conditions. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for starting an engine of a multi - energy system to solve one or more technical problems existing in the prior art, and at least provide a beneficial choice or create conditions.

[0006] The technical solution adopted to solve the above - mentioned technical problems:

[0007] A method for starting an engine of a multi - energy system, the multi - energy system includes: a power generation module with a generator and two power sources, and the two power sources include a power battery module and a fuel cell module;

[0008] The specific method steps are as follows:

[0009] S1: Determine the type of the current energy source. If the current energy source is only the power battery module, enter the single - power - battery start mode; if the current energy source is only the fuel cell module, enter the single - fuel - cell start mode; if the current energy source has both the power battery module and the fuel cell module, enter the hybrid - energy start mode of the power battery module and the fuel cell module;

[0010] S2: preset the minimum power threshold for the generator to start the engine and the minimum power threshold for the engine to start from idle speed in the corresponding starting mode;

[0011] S3: Determine the discharge capacity in the corresponding mode. If the discharge capacity is not lower than the minimum power threshold of the generator to start the engine, start the engine by the generator to start; if the discharge capacity is lower than the minimum power threshold of the generator to start the engine but not lower than the minimum power threshold of the engine self-idling start, start the engine by the engine self-idling start.

[0012] The multi-energy system engine starting method provided by the present invention has at least the following beneficial effects: when the engine needs to be started, according to the different energy sources, the corresponding engine starting logic under different energy source modes is formulated, so that the starting process can adapt to different energy source types, and achieve the purpose of improving the engine starting success rate under different energy source conditions. In addition, according to the different starting energy sizes, the two starting modes of generator dragging the engine and engine self-idling starting are respectively used in a targeted manner, which improves the smoothness of the whole vehicle during the engine starting process while ensuring the success rate of engine starting. The multi-energy system engine starting method of the present invention can adapt to the starting operation under different energy source types in the multi-energy system, and reasonably use the energy size to select the starting mode, so that the engine starting success rate and smoothness are improved.

[0013] If the current energy source is only provided by the power battery module, the single power battery starting mode is adopted, and the minimum power threshold for the generator to drag the engine and the minimum power threshold for the engine to start from idle speed in this mode are preset. The relationship between the discharge capacity in the single power battery starting mode and the minimum power threshold for the generator to drag the engine and the minimum power threshold for the engine to start from idle speed is judged, and then the generator drag mode or the engine self-idle starting mode is selected for starting.

[0014] If the current energy source is only provided by the fuel cell module, the single fuel cell start mode is adopted, and the minimum power threshold for the generator to drag the engine and the minimum power threshold for the engine to start from idle speed in this mode are preset. The relationship between the discharge capacity in the single fuel cell start mode and the minimum power threshold for the generator to drag the engine and the minimum power threshold for the engine to start from idle speed is judged, and then the generator drag mode or the engine self-idle start mode is selected for starting.

[0015] If the current energy source is not only provided by the power battery module or the fuel cell module, a hybrid energy start mode is adopted, and the minimum power threshold for the generator to drag the engine and the minimum power threshold for the engine to start from idling are preset in this mode. The relationship between the discharge capacity in the hybrid energy start mode and the minimum power threshold for the generator to drag the engine and the minimum power threshold for the engine to start from idling is judged, and then the start is carried out by means of the generator dragging method or the engine starting from idling method.

[0016] Through the above technical solution, in the case where the current energy source is a single power battery module, a single fuel cell module or a hybrid energy source, the single power battery start mode, the single fuel cell start mode and the hybrid energy start mode are respectively adopted.

[0017] As a further improvement of the above technical solution, in step S2 specifically: first judge whether the whole vehicle is in the energy recovery process, and then preset the minimum power threshold for the generator to drag the engine and the minimum power threshold for the engine to start from idling in the corresponding situation. Through the above technical solution, considering the influence of the recovered energy in the energy recovery process on the starting energy requirement during the engine starting process, the driving conditions of the whole vehicle can be reasonably utilized, so as to optimize the energy distribution during the starting process.

[0018] As a further improvement of the above technical solution, the multi-energy system further includes a drive motor module. Whether the whole vehicle is in the energy recovery process is judged according to whether the drive motor module recovers the braking energy to the high-voltage bus connected to the power generation system. Through the above technical solution, when the vehicle is driving normally, the power generation module, the power battery module and the fuel cell module can all work independently or in coordination with each other to provide an energy source for the drive motor. And the drive motor module can also recover electric energy to the high-voltage bus through the braking energy recovery function during the braking process for energy distribution coordination, that is, the whole vehicle is in the energy recovery process.

[0019] As a further improvement of the above technical solution, in step S3, in the single fuel cell start mode and the hybrid energy start mode, the actual output power of the fuel cell module is superimposed with the fuel cell output power pulling rate affected by the fuel cell life. Through the above technical solution, the engine start strategy is optimized considering the influence of the fuel cell life, the service life of the energy source is improved, and the discharge capacity determination of the energy source in the corresponding mode is made more accurate.

[0020] As a further improvement of the above technical solution, in step S3, if the discharge capacity is lower than the minimum power threshold for the engine to start from idling, it is determined that the energy source does not have enough energy to start the engine.

[0021] As a further improvement of the above technical solution, during the startup process by means of being towed by the generator, the generator adjusts the engine speed through a speed control mode; during the startup process by means of the engine's self-idle startup, the generator adjusts the engine speed through a torque control mode. Through the above technical solution, when starting the engine by means of the generator drag, the energy source has sufficient energy to supply the generator, and the generator adopting the speed control mode is more conducive to the speed regulation of the generator. When starting the engine by means of the engine's self-idle startup, it indicates that the energy of the energy source is limited. Compared with the speed control mode, the generator adopting the torque control mode has a higher controllability and better effect.

[0022] When starting the engine by means of the generator drag, the generator performs a pull-up control on the engine speed in the speed control mode. When the engine speed is not lower than the threshold value n1, an engine fuel injection and ignition instruction is sent to achieve the startup of the engine. When starting by means of the engine's self-idle startup, the generator performs a pull-up control on the engine speed in the torque control mode. When the engine speed is not lower than the threshold value n2, an engine self-idle startup instruction is sent to achieve the startup of the engine.

[0023] As a further improvement of the above technical solution, if the engine successfully starts after sending the engine fuel injection and ignition instruction, an engine startup success flag bit is sent. If the engine startup success flag bit is not monitored after sending the engine fuel injection and ignition instruction, the engine fuel injection and ignition instruction is sent again. As a further improvement of the above technical solution, the engine fuel injection and ignition instruction is repeatedly sent until the number of attempted starts exceeds a preset value, and it is determined as a startup failure.

[0024] Through the above technical solution, it is possible to confirm whether the engine has started successfully and avoid the situation of accidental startup failure of the engine. Brief Description of the Drawings

[0025] The following further describes the present invention in conjunction with the drawings and embodiments;

[0026] Figure 1 is a topological structure schematic diagram of one embodiment of the multi-energy system provided by the present invention;

[0027] Figure 2 is a flowchart of identifying the engine startup requirements under different energy sources in one embodiment of the engine startup method of the multi-energy system provided by the present invention;

[0028] Figure 3 is a flowchart of judging the engine startup method in the single power battery startup mode in one embodiment of the engine startup method of the multi-energy system provided by the present invention;

[0029] Figure 4It is the engine starting method of the multi - energy system provided by the present invention, and it is the flowchart for judging the engine starting method in the single - fuel - cell starting mode of one embodiment;

[0030] Figure 5 It is the engine starting method of the multi - energy system provided by the present invention, and it is the flowchart for judging the engine starting method in the hybrid - energy starting mode of one embodiment;

[0031] Figure 6 It is the engine starting method of the multi - energy system provided by the present invention, and it is the starting flowchart of the generator - driven mode of one embodiment;

[0032] Figure 7 It is the engine starting method of the multi - energy system provided by the present invention, and it is the starting flowchart of the engine self - idle - speed starting mode of one embodiment. Detailed implementation manners

[0033] This part will describe the specific embodiments of the present invention in detail. The preferred embodiments of the present invention are shown in the drawings. The function of the drawings is to supplement the description of the text part of the specification, enabling people to intuitively and vividly understand each technical feature and the overall technical solution of the present invention. However, it should not be construed as a limitation on the protection scope of the present invention.

[0034] In the description of the present invention, it should be understood that for the orientation description, such as the orientation or positional relationship indicated by up, down, front, back, left, right, etc., is based on the orientation or positional relationship shown in the drawings. It is 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. Therefore, it should not be construed as a limitation on the present invention.

[0035] In the description of the present invention, if there are words such as "several" for description, its meaning is one or more, and the meaning of multiple is more than two. Understandings such as greater than, less than, exceeding, etc. do not include the present number, and understandings such as above, below, within, etc. include the present number.

[0036] In the description of the present invention, unless otherwise clearly defined, words such as setting, installing, connecting, etc. should be understood in a broad sense. Those skilled in the art can reasonably determine the specific meaning of the above words in the present invention in combination with the specific content of the technical solution.

[0037] Refer to Figures 1 to 7 , the following embodiments are made for the engine starting method of the multi - energy system of the present invention:

[0038] The multi - energy system of the present invention includes: a power battery module, a fuel cell module, a power generation module, and a drive motor module. The power generation module includes: an engine and a generator connected to the engine. The power battery module, the fuel cell module, the power generation module, and the drive motor module are all electrically connected to each other.

[0039] The topological schematic diagram of the multi - energy system is as Figure 1 shown. When the vehicle is running normally, the power battery module, the fuel cell module, and the power generation module can all work independently to provide an energy source for the drive motor module alone, or they can work in coordination to provide an energy source for the drive motor module simultaneously.

[0040] During the engine startup process, external energy needs to be coordinated, that is, both the power battery module and the fuel cell module can provide energy for the generator alone or in coordination. In addition, during the braking process, the drive motor module can also recover electrical energy to the high - voltage bus through the braking energy recovery function as the energy source for the generator.

[0041] In the engine startup method of the multi - energy system of the present invention, when an engine startup instruction is detected:

[0042] Referring to Figure 2 , first, judge the current energy source type, and select the corresponding engine startup mode according to the current energy source type: If the current energy source is provided only through the power battery module, the single - power - battery startup mode is adopted; if the current energy source is provided only through the fuel cell module, the single - fuel - cell startup mode is adopted; if the current energy source is provided not only by the power battery module or the fuel cell module, the hybrid - energy startup mode is adopted.

[0043] As Figure 3 shown, in the single - power - battery startup mode: preset the minimum power threshold of the generator dragging the engine when the whole vehicle is in the energy recovery process as P1, and the minimum power threshold of the engine starting from idle speed as P low1 ; when the whole vehicle is not in the energy recovery process, the minimum power threshold of the generator dragging the engine is P2, and the minimum power threshold of the engine starting from idle speed is P low2 .

[0044] When the whole vehicle is not in the energy recovery process, if the discharge capacity of the power battery module is not less than P2, select to start by the generator dragging method. If the discharge capacity of the power battery module is lower than P2 but not less than P low2 , select the engine self - starting - from - idle - speed method to start. If the discharge capacity of the power battery module is lower than P low2 , it means that the single - power - battery module does not have enough energy to provide an energy source for the power generation module to start the engine.

[0045] When the whole vehicle is in the energy recovery process, if the discharge capacity of the power battery module is not less than P1, the generator drive mode is selected for starting. If the discharge capacity of the power battery module is lower than P1 but not less than P low1 , the engine self-idle start mode is selected for starting. If the discharge capacity of the power battery module is lower than P low1 , it means that even when the whole vehicle is in the energy recovery process, the power battery module does not have enough energy to provide an energy source for the power generation module to start the engine.

[0046] The discharge capacity of the power battery module is determined by the physical characteristics of its power battery itself and can be sent to the control system through CAN communication for comparison and processing. Similarly, the discharge capacity of the fuel cell module is also determined by the characteristics of its fuel cell itself, while the discharge capacity in the hybrid energy mode is jointly determined by the power battery module and the fuel cell module.

[0047] The fuel cell life is strongly correlated with the fuel cell output power loading rate. As Figure 4 shown, when starting the engine in the single fuel cell start mode, the judgment of the discharge capacity of the fuel cell module needs to combine the actual output power of the current fuel cell and the fuel cell output power loading rate restricted by the fuel cell life.

[0048] In the single fuel cell start mode: The preset minimum power threshold for the generator to tow the engine when the whole vehicle is in the energy recovery process is P3, and the minimum power threshold for the engine to start from self-idle is P low3 ; The minimum power threshold for the generator to tow the engine when the whole vehicle is not in the energy recovery process is P4, and the minimum power threshold for the engine to start from self-idle is P low4 .

[0049] When the whole vehicle is not in the energy recovery process, if the discharge capacity of the fuel cell module is not less than P4, the generator drive mode is selected for starting. If the discharge capacity of the fuel cell module is lower than P4 but not less than P low4 , the engine self-idle start mode is selected for starting. If the discharge capacity of the fuel cell module is lower than P low4 , it means that the single fuel cell module does not have enough energy to provide an energy source for the power generation module to start the engine.

[0050] When the whole vehicle is in the energy recovery process, if the discharge capacity of the fuel cell module is not less than P3, the generator drive mode is selected for starting. If the discharge capacity of the fuel cell module is lower than P3 but not less than P low3 , the engine self-idle start mode is selected for starting. If the discharge capacity of the fuel cell module is lower than P low3, it indicates that even during the energy recovery process, a single fuel cell module does not have enough energy to provide an energy source for the power generation module to start the engine.

[0051] As Figure 5 shown, when starting the engine in the hybrid energy start mode, it is necessary to combine the actual output power of the current fuel cell module, superimpose the pulling rate of the fuel cell output power restricted by the fuel cell life, and at the same time consider that the power battery module can also provide the energy demand during the engine start process, so as to obtain the discharge capacity in the hybrid energy start mode and determine whether the power battery module and the fuel cell module have enough energy to start the engine in the hybrid energy start mode.

[0052] In the hybrid energy start mode: The preset minimum power threshold for the generator to drag the engine when the whole vehicle is in the energy recovery process is P5, and the minimum power threshold for the engine to start from idle speed is P low5 ; The preset minimum power threshold for the generator to drag the engine when the whole vehicle is not in the energy recovery process is P6, and the minimum power threshold for the engine to start from idle speed is P low6 .

[0053] When the whole vehicle is not in the energy recovery process, if the discharge capacity in the hybrid energy mode is not less than P6, then choose to start by the generator dragging method. If the discharge capacity in the hybrid energy mode is lower than P6 but not less than P low6 , then choose the engine self-idle start method to start. If the total discharge capacity of the power battery module and the fuel cell module in the hybrid energy mode is lower than P low6 , it indicates that the hybrid energy mode does not have enough energy to provide an energy source for the power generation module to start the engine.

[0054] When the whole vehicle is in the energy recovery process, if the discharge capacity in the hybrid energy mode is not less than P5, then choose to start by the generator dragging method. If the discharge capacity in the hybrid energy mode is lower than P5 but not less than P low5 , then choose the engine self-idle start method to start. If the total discharge capacity of the power battery module and the fuel cell module in the hybrid energy mode is lower than P low5 , it indicates that even during the energy recovery process, the hybrid energy mode does not have enough energy to provide an energy source for the power generation module to start the engine.

[0055] The minimum power threshold for the generator to drag the engine mentioned above refers to the energy threshold required for the generator controller to control the generator to drag the engine to reach the preset speed at a preset speed. The minimum power threshold for the engine to start from idle speed refers to the energy threshold required for the generator controller to control the generator to drag the engine to reach the preset speed at a preset torque.

[0056] During the energy recovery process, the recovered energy can be used to start the process and provide energy for the generator. Therefore, in the single power battery start mode: P1 is less than P2, P low1 is less than P low2 . Similarly, in the single fuel cell start mode: P3 is less than P4, P low3 is less than P low4 . In the hybrid energy start mode: P5 is less than P6, P low5 is less than P low6 .

[0057] As Figure 6 shown, when starting by means of generator drive, the generator enters the speed control mode to adjust the engine speed. During this process, it is monitored and judged whether the engine speed is not lower than n1. If the engine speed is lower than n1, the generator continues to perform engine speed boosting control. If the engine speed is not lower than n1, an engine fuel injection and ignition command is sent. After sending the engine fuel injection and ignition command, it is monitored whether the engine issues a start success flag. If the engine issues a start success flag, it is judged that the engine starts successfully and the start process ends. If the engine does not issue a start success flag, the number of attempts to start the engine is recorded. When the number of attempts to start does not exceed n start , it is allowed to send the engine fuel injection and ignition command again until the engine issues a start success flag. If the number of attempts to start exceeds n start and the engine still fails to start successfully, it is determined that the engine start fails.

[0058] As Figure 7 shown, when starting by means of engine self-idle start, the generator enters the torque control mode to adjust the engine speed. During this process, it is monitored and judged whether the engine speed is not lower than n2. If the engine speed is lower than n2, the generator continues to perform engine speed boosting control. If the engine speed is not lower than n2, an engine fuel injection and ignition command is sent. After sending the engine fuel injection and ignition command, it is monitored whether the engine issues a start success flag. If the engine issues a start success flag, it is judged that the engine starts successfully and the start process ends. If the engine does not issue a start success flag, the number of attempts to start the engine is recorded. When the number of attempts to start does not exceed n start , it is allowed to send the engine fuel injection and ignition command again until the engine issues a start success flag. If the number of attempts to start exceeds n start and the engine still fails to start successfully, it is determined that the engine start fails.

[0059] The n1 is the lowest ignition start speed threshold of the engine in the generator drag mode, and the n2 is the lowest ignition start speed threshold of the engine in the engine self-idle start mode. It should be noted that in the generator drag mode and the engine self-idle start mode, the upper limit n of the number of attempts for the engine to start start can be preset to different values.

[0060] After the engine fails to start, an engine abnormality flag bit can be issued and displayed on the dashboard; or the engine start operation can be automatically restarted within a certain period of time.

[0061] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0062] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can still make various changes, modifications, substitutions, and variations to these embodiments without departing from the principles and purposes of the present invention. These changes, modifications, equivalent variations, or substitutions are all included within the scope defined by the claims of this application. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for starting an engine of a multi - energy system, characterized in that: The multi - energy system includes a power generation module with a generator and two power sources. The two power sources include a power battery module and a fuel cell module. The specific method steps are as follows: S1: Determine the current energy source type. If the current energy source is only the power battery module, enter the single - power - battery startup mode; if the current energy source is only the fuel cell module, enter the single - fuel - cell startup mode; if the current energy source includes both the power battery module and the fuel cell module, enter the hybrid - energy startup mode of the power battery module and the fuel cell module. S2: Preset the minimum power threshold for the generator to tow the engine and the minimum power threshold for the engine to start from idle speed in the corresponding startup mode. S3: Judge the discharge capacity in the corresponding mode. If the discharge capacity is not lower than the minimum power threshold for the generator to tow the engine, start by the generator - towing method; if the discharge capacity is lower than the minimum power threshold for the generator to tow the engine but not lower than the minimum power threshold for the engine to start from idle speed, start by the engine - self - idle - start method.

2. The method for starting an engine of a multi - energy system according to claim 1, characterized in that: In S2: First, judge whether the whole vehicle is in the energy - recovery process, and then preset the minimum power threshold for the generator to tow the engine and the minimum power threshold for the engine to start from idle speed in the corresponding situation.

3. The method for starting an engine of a multi - energy system according to claim 2, characterized in that: The multi - energy system further includes a drive motor module. Whether it is in the energy - recovery process is judged according to whether the drive motor module recovers braking energy to the high - voltage bus connected to the power generation module.

4. The method for starting an engine of a multi - energy system according to claim 1, characterized in that: In step S3, in the single - fuel - cell startup mode and the hybrid - energy startup mode, the actual output power of the fuel cell module is superimposed with the fuel - cell output - power derating rate affected by the fuel - cell life.

5. The method for starting an engine of a multi - energy system according to claim 1, characterized in that: In step S3, if the discharge capacity is lower than the minimum power threshold for the engine to start from idle speed, it is determined that the energy source does not have enough energy to start the engine.

6. The method for starting an engine of a multi - energy system according to claim 1, characterized in that: During the startup process by the generator - towing method, the generator adjusts the engine speed through the speed - control mode; during the startup process by the engine - self - idle - start method, the generator adjusts the engine speed through the torque - control mode.

7. The method for starting an engine of a multi - energy system according to claim 6, characterized in that: The generator - towing method and the engine - self - idle - start method are specifically as follows: Judge the engine speed. If the engine speed has not reached the minimum ignition - startup speed threshold, continue to adjust the engine speed upward; if the engine speed is not less than the minimum ignition - startup speed threshold, send an engine fuel - injection and ignition instruction.

8. The method for starting an engine of a multi - energy system according to claim 7, characterized in that: If the engine starts successfully after sending the engine fuel - injection and ignition instruction, send an engine - startup - success flag bit.

9. The method for starting an engine of a multi - energy system according to claim 8, characterized in that: If the engine - startup - success flag bit is not monitored after sending the engine fuel - injection and ignition instruction, send the engine fuel - injection and ignition instruction again.

10. The method for starting an engine of a multi - energy system according to claim 9, characterized in that: If the number of times of continuously sending the engine fuel - injection and ignition instruction exceeds the preset value and the engine - startup - success flag bit is still not monitored, it is determined that the startup fails.

Images