Engine starting method and system, controller, storage medium and hybrid electric vehicle

Abstract

An engine starting method, comprising: when a condition of starting an engine at a low voltage is met, controlling a low-voltage storage battery to supply power to a driving motor, so as to enable the driving motor to store energy; and when a preset condition is met, controlling the driving motor to release electric energy to a starting generator, so as to enable the starting generator to operate to start the engine. Also disclosed are an engine starting system, a controller, a computer-readable storage medium and a hybrid electric vehicle.

Description

Engine starting method and system, controller, storage medium and hybrid vehicle

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on April 3, 2024, with application number 202410407918.1 and entitled “Engine Starting Method, System, Controller and Hybrid Electric Vehicle,” the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present disclosure relates to the field of vehicle technology, and in particular to an engine starting method, system, controller and hybrid vehicle. Background Art

[0004] In the prior art, when a hybrid vehicle starts its engine, the high-voltage battery pack primarily powers the generator through a main relay, which then drives the engine to start. However, if the high-voltage battery pack fails or the main relay disconnects or malfunctions, the vehicle cannot use the high voltage to start the engine. Furthermore, the low-voltage battery in current hybrid vehicles has a relatively small capacity, typically 12V, and its output current energy is weaker than that of fuel-powered vehicles. Therefore, the engine cannot be started directly using the 12V low-voltage battery, resulting in a failure to start the engine and an inability to drive the vehicle, resulting in low reliability.

[0005] Public content

[0006] The present disclosure aims to solve at least one of the technical problems existing in the prior art.

[0007] To this end, one purpose of the present disclosure is to propose an engine starting method, which enables a hybrid vehicle to start its engine smoothly when a high-voltage battery pack fails and the energy of the high-voltage battery pack cannot be used, thereby allowing the vehicle to run normally and improving the reliability of the vehicle.

[0008] To this end, a second object of the present disclosure is to provide an engine starting system.

[0009] To this end, the third object of the present disclosure is to provide a controller.

[0010] To this end, a fourth object of the present disclosure is to provide a computer-readable storage medium.

[0011] To this end, a fifth object of the present disclosure is to provide a hybrid vehicle.

[0012] To achieve the above-mentioned objectives, an embodiment of the first aspect of the present disclosure discloses an engine starting method, comprising: when the conditions for low-voltage starting the engine are met, controlling the low-voltage battery to power the drive motor so that the drive motor stores energy; and when a preset condition is reached, controlling the drive motor to release electrical energy to the starter generator so that the starter generator runs to start the engine.

[0013] According to the engine starting method of the disclosed embodiment, it is determined whether the vehicle meets the conditions for starting the engine at low voltage. For example, when the vehicle cannot start the engine through high voltage, the low-voltage battery is controlled to power the drive motor, so that the drive motor no longer transmits energy to the wheels but can store energy, thereby providing the starter generator with the energy required to start the engine; when the preset conditions are met, the drive motor is controlled to release electrical energy to the starter generator, and the energy released by the drive motor powers the starter generator, so that there is enough energy to start the generator, and then the engine is started by the starter generator, so that when the high-voltage battery pack fails and the energy of the high-voltage battery pack cannot be used, the hybrid vehicle can still start the engine smoothly, allowing the vehicle to travel normally, thereby improving the reliability of the vehicle.

[0014] In addition, the engine starting method according to the above embodiment of the present disclosure may also have the following additional technical features:

[0015] In some embodiments, controlling the low-voltage battery to power the drive motor so that the drive motor stores energy includes: controlling the low-voltage battery to power the drive motor so that the rotor of the drive motor accelerates rotation to convert electrical energy into mechanical energy for storage.

[0016] In some embodiments, the process of controlling the low-voltage battery to supply power to the drive motor so that the drive motor stores energy further includes: limiting the output torque of the drive motor.

[0017] In some embodiments, the preset condition includes: the rotor speed of the drive motor reaches a target speed.

[0018] In some embodiments, the target speed is determined by the engine state parameters under current circumstances.

[0019] In some embodiments, after the starter generator runs to start the engine, it also includes: determining whether the engine is started successfully; if so, controlling the starter generator to charge the low-voltage battery; otherwise, increasing the target speed to update the target speed, and returning to execute the step of controlling the low-voltage battery to power the drive motor according to the updated target speed to enable the drive motor to store energy.

[0020] In some embodiments, the conditions for starting the engine at low voltage include: a high voltage battery pack failure and / or a high voltage main relay connected to the high voltage battery pack is disconnected, the engine is in an unstarted state, and a start request for the engine is received.

[0021] In some embodiments, controlling the drive motor to release electrical energy to the starter generator includes controlling the rotor speed of the drive motor to decrease to a set value within a preset time. In some embodiments, when the preset condition is met, the process further includes controlling a bidirectional DC-DC converter to convert the voltage output by the low-voltage battery, and supplying power to the starter generator using the converted voltage.

[0022] In some embodiments, when the conditions for low-voltage starting of the engine are met, the method further includes: if the drive motor is in a connected state with the wheels of the vehicle, controlling the drive motor to be disconnected from the wheels.

[0023] To achieve the above-mentioned objectives, an embodiment of the second aspect of the present disclosure proposes an engine starting system, comprising: a low-voltage battery, which is used to provide low-voltage electricity; a drive motor, which can be connected or disconnected with the wheels of a vehicle; a starter generator, which is connected to the engine of the vehicle; and a controller, which is respectively connected to the low-voltage battery, the drive motor and the starter generator, and is used to execute the engine starting method as described in the embodiment of the first aspect above.

[0024] According to the engine starting system of the embodiment of the present disclosure, it is determined whether the vehicle meets the conditions for starting the engine at low voltage. For example, when the vehicle cannot start the engine through high voltage, the low-voltage battery is controlled to power the drive motor, so that the drive motor no longer transmits energy to the wheels but can store energy, thereby providing the starter generator with the energy required to start the engine; when the preset conditions are met, the drive motor is controlled to release electrical energy to the starter generator, and the energy released by the drive motor powers the starter generator, so that there is enough energy to start the generator, and then the engine is started by the starter generator, so that when the high-voltage battery pack fails and the energy of the high-voltage battery pack cannot be used, the hybrid vehicle can still start the engine smoothly, so that the vehicle can run normally, thereby improving the reliability of the vehicle.

[0025] In addition, the engine starting system according to the above embodiment of the present disclosure may also have the following additional technical features:

[0026] In some embodiments, the engine starting system further includes: a bidirectional DCDC converter, which is connected to the low-voltage battery and is used to convert the voltage output by the low-voltage battery, or to convert the voltage output by the starter generator and transmit it to the low-voltage battery.

[0027] In some embodiments, the engine starting system further includes: a decoupling device; the decoupling device is respectively connected to the drive motor and the wheels, and the controller controls the connection or disconnection of the drive motor and the wheels by controlling the connectivity state of the decoupling device.

[0028] In some embodiments, the controller is a motor controller.

[0029] In order to achieve the above-mentioned purpose, an embodiment of the third aspect of the present disclosure proposes a controller, including: a processor; a memory, on which an engine starting program is stored, and the engine starting program can be executed by the processor. When the engine starting program is executed by the processor, the engine starting method described in the embodiment of the first aspect of the present disclosure can be implemented.

[0030] According to the controller of the embodiment of the present disclosure, it is determined whether the vehicle meets the conditions for starting the engine at low voltage. For example, when the vehicle cannot start the engine through high voltage, the low-voltage battery is controlled to power the drive motor, so that the drive motor no longer transmits energy to the wheels but can store energy, thereby providing the starter generator with the energy required to start the engine; when the preset conditions are met, the drive motor is controlled to release electrical energy to the starter generator, and the energy released by the drive motor powers the starter generator, so that there is enough energy to start the generator, and then the engine is started by the starter generator, so that when the high-voltage battery pack fails and the energy of the high-voltage battery pack cannot be used, the hybrid vehicle can still start the engine smoothly, so that the vehicle can run normally, thereby improving the reliability of the vehicle.

[0031] In order to achieve the above-mentioned purpose, an embodiment of the fourth aspect of the present disclosure proposes a computer-readable storage medium, on which an engine starting program is stored. When the engine starting program is executed by a processor, the engine starting method described in the embodiment of the first aspect of the present disclosure is implemented.

[0032] According to the computer-readable storage medium of the embodiment of the present disclosure, when the engine starting program stored thereon is executed by the processor, it is determined whether the vehicle meets the conditions for low-voltage starting of the engine. For example, when the vehicle cannot start the engine through high voltage, the low-voltage battery is controlled to power the drive motor, so that the drive motor no longer transmits energy to the wheels but can store energy, thereby providing the starter generator with the energy required to start the engine; when the preset conditions are met, the drive motor is controlled to release electrical energy to the starter generator, and the energy released by the drive motor powers the starter generator, so that there is enough energy to start the generator, and then the engine is started by the starter generator, so that when the high-voltage battery pack fails and the energy of the high-voltage battery pack cannot be used, the hybrid vehicle can still start the engine smoothly, so that the vehicle can run normally, thereby improving the reliability of the vehicle.

[0033] In order to achieve the above-mentioned objectives, an embodiment of the fifth aspect of the present disclosure provides a hybrid vehicle, comprising: an engine and the engine starting system according to the embodiment of the second aspect of the present disclosure.

[0034] According to the hybrid vehicle of the embodiment of the present disclosure, it is determined whether the vehicle meets the conditions for starting the engine at low voltage. For example, when the vehicle cannot start the engine through high voltage, the low-voltage battery is controlled to power the drive motor, so that the drive motor no longer transmits energy to the wheels but can store energy, thereby providing the starter generator with the energy required to start the engine; when the preset conditions are met, the drive motor is controlled to release electrical energy to the starter generator, and the energy released by the drive motor is used to power the starter generator, so that there is enough energy to start the generator, and then the engine is started by the starter generator, so that when the high-voltage battery pack fails and the energy of the high-voltage battery pack cannot be used, the hybrid vehicle can still start the engine smoothly, so that the vehicle can run normally, thereby improving the reliability of the vehicle.

[0035] Additional aspects and advantages of the present disclosure will be given in part in the description that follows and, in part, will be obvious from the description that follows, or will be learned through practice of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The above and / or additional aspects and advantages of the present disclosure will become apparent and readily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0037] FIG1 is a flow chart of an engine starting method according to one embodiment of the present disclosure;

[0038] FIG2 is an overall flow chart of an engine starting method according to one embodiment of the present disclosure;

[0039] FIG3 is a schematic diagram of an engine starting system with a series mode according to one embodiment of the present disclosure;

[0040] FIG4 is a schematic diagram of a low-voltage battery accelerating a drive motor rotor according to an embodiment of the present disclosure;

[0041] 5 is a schematic diagram of a low-voltage battery and the mechanical energy of a drive motor rotor jointly powering a starter generator according to one embodiment of the present disclosure;

[0042] FIG6 is a schematic diagram of the speed and torque of the driving motor and the engine during the engine starting process according to one embodiment of the present disclosure;

[0043] FIG7 is a structural block diagram of a controller according to an embodiment of the present disclosure.

[0044] Figure numerals: 2. Engine starting system; 21. High-voltage battery pack; 22. Low-voltage battery; 23. Bidirectional DCDC converter; 24. High-voltage main relay; 25. Drive motor; 26. Starter generator; 27. Controller; 271. Processor; 272. Memory; 28. Decoupling device; 4. Hybrid vehicle; 41. Engine; 42. Wheel. DETAILED DESCRIPTION

[0045] Embodiments of the present disclosure are described in detail below, and the embodiments described with reference to the accompanying drawings are exemplary.

[0046] In the related art, during the generator starting process in a hybrid vehicle, a high-power motor driven by high voltage electricity is typically used to start the engine. This starting motor and the generator motor are typically shared. Because of this, the capacity of the low-voltage battery (e.g., 12V) in a hybrid vehicle is relatively small, and its output current is weaker than that of a gasoline vehicle. The inventors have discovered that, under normal circumstances, a 12V battery can only stably output a maximum of 2 kW of power through a bidirectional DC-DC converter. However, maintaining a speed of 800-1000 rpm requires at least 5-10 kW of power to overcome engine friction and inertia. Therefore, the small 12V battery in a typical hybrid vehicle is not capable of directly starting the engine, and therefore cannot be used directly to start the engine. When the high-voltage battery pack and main relay, the components that provide voltage to the generator, are in a normal, fault-free state, the generator can easily start the engine. However, if the high-voltage battery pack or the main relay malfunction and fail to provide high voltage power to the generator, the engine cannot be started smoothly, resulting in the vehicle being unable to drive normally. If you want to start the engine directly from a 12V battery, you need to increase the battery capacity and current output capability by about 5 times, and at the same time expand the capacity of the bidirectional DCDC converter by about 5 times. However, this will significantly increase the cost in this regard and increase the size of the device, affecting the layout of the vehicle space.

[0047] Based on the above, the design concept of the present disclosure is that after a serious failure of the high-voltage battery pack, the engine can be started with a low-voltage battery, so that the vehicle can be driven to a safe place or repair station, or even temporarily without repair, and can be driven at a relatively normal medium and low speed before repair. The probability of this scenario occurring is relatively low, and the cost of directly upgrading the low-voltage battery and the bidirectional DCDC converter is high, and the applicability is not high. Without changing the hardware composition and output capacity, the embodiment of the present disclosure uses the rotor of the drive motor as an energy buffer, converts the lower-power electrical energy output by the low-voltage battery into mechanical energy and stores it in the rotor, and after storing energy of the order of 10s, the energy is then used to generate electricity and cooperate with the output power of the low-voltage battery to jointly power the generator, quickly releasing the stored energy in a short time (such as 1 to 2s) to complete the task of starting the engine.

[0048] Therefore, in the case of a high-voltage battery pack failure and the engine cannot be started at high voltage, the embodiment of the present disclosure stores energy by driving the motor rotor, and utilizes the energy of a low-voltage battery (such as 12V) with a smaller output power so that it can be released in a short time after storage to start the engine. This allows the hybrid vehicle's high-voltage battery pack to enter a serious fault state or become completely unusable, and the engine can still be started using only the electrical energy of the low-voltage battery, thereby allowing the vehicle to run normally and improving the reliability of the vehicle.

[0049] In order to solve the above problems, one purpose of the present disclosure is to propose an engine starting method, so that a hybrid vehicle can still start the engine smoothly even when the high-voltage battery pack cannot start the engine at high voltage, so that the vehicle can run normally and improve the reliability of the vehicle.

[0050] The engine starting method according to an embodiment of the present disclosure will be described below with reference to FIG. 1 and FIG. 2 .

[0051] FIG1 is a flow chart of an engine starting method according to an embodiment of the present disclosure. As shown in FIG1 , the disclosed engine starting method includes at least steps S1 to S2.

[0052] Step S1: When the conditions for starting the engine at low voltage are met, the low-voltage battery is controlled to supply power to the drive motor so that the drive motor stores energy.

[0053] In an embodiment, the conditions for starting the engine at low voltage include, for example, a high-voltage battery pack failure or a main relay disconnection, and the engine has a start request and the engine is in an unstarted state. By obtaining the high-voltage battery pack, the high-voltage main relay and the engine status, after determining that the conditions for starting the engine at low voltage are met, the low-voltage battery can be controlled to power the drive motor. The low-voltage battery is, for example, a 12V battery. When the drive motor receives electrical energy from the low-voltage battery, the drive motor can use this electrical energy to accelerate its rotor. In this process, the rotor of the drive motor can be used as an energy buffer. The lower power (for example, 2kw) electrical energy output by the low-voltage battery is converted into mechanical energy and stored in the rotor, so that the drive motor can accumulate enough mechanical energy. This can be understood as the process of storing energy in the drive motor so as to provide the required auxiliary power during the subsequent engine starting process.

[0054] Step S2: When a preset condition is met, the drive motor is controlled to release electric energy to the starter generator so that the starter generator operates to start the engine.

[0055] In an embodiment, during the starting process of the engine of a hybrid vehicle, the rotor of the drive motor has been accelerated and stored mechanical energy through the power supply of a low-voltage battery. For example, after storing energy for a time of the order of 10 seconds, the preset conditions are met, and the mechanical energy stored in the rotor is converted into electrical energy to control the drive motor to start releasing electrical energy to the starter generator. That is, the drive motor uses the mechanical energy stored in the rotor to generate electricity and power the starter generator. The starter generator can quickly release the stored energy in a short time (for example, 1 to 2 seconds) to complete the task of starting the engine.

[0056] Therefore, according to the engine starting method of the embodiment of the present disclosure, it is determined whether the vehicle meets the conditions for low-voltage engine starting. For example, when the vehicle cannot start the engine through high voltage, the low-voltage battery is controlled to power the drive motor so that the drive motor no longer transmits energy to the wheels but stores energy, thereby providing the starter generator with the energy required to start the engine; when the preset conditions are met, the drive motor is controlled to release electrical energy to the starter generator, and the energy released by the drive motor powers the starter generator, so that there is enough energy to start the generator, and then the engine is started by the starter generator, so that when the high-voltage battery pack fails and the energy of the high-voltage battery pack cannot be used, the hybrid vehicle can still start the engine smoothly, so that the vehicle can run normally, thereby improving the reliability of the vehicle.

[0057] In one embodiment of the present disclosure, controlling the low-voltage battery to power the drive motor so that the drive motor stores energy includes: controlling the low-voltage battery to power the drive motor so that the rotor of the drive motor accelerates rotation to convert electrical energy into mechanical energy for storage.

[0058] In an embodiment, during the engine start-up process of a hybrid vehicle, when it is detected that the engine needs to be started and the high-voltage battery pack is unavailable, a corresponding control instruction is issued to the bidirectional DCDC converter to control the bidirectional DCDC converter to power the motor controller. After the drive motor receives electrical energy, it outputs positive torque to drive its rotor to accelerate rotation, which can generate mechanical energy, thereby converting electrical energy into mechanical energy storage.

[0059] Specifically, the low-voltage battery is controlled to output low-voltage electricity, which is converted into high-voltage electricity through a bidirectional DCDC converter and then output to the drive motor to power the drive motor. After receiving the electric energy, the drive motor begins to output positive torque, that is, it generates a force that pushes the rotor to rotate faster. The positive torque accelerates the rotor of the drive motor, thereby converting the supplied electric energy into mechanical energy. As the drive motor rotor rotates faster, more mechanical energy is stored inside the drive motor, thereby providing the auxiliary power required for the rapid start of the engine.

[0060] In one embodiment of the present disclosure, in the process of controlling the low-voltage battery to supply power to the drive motor so that the drive motor stores energy, the process further includes: limiting the output torque of the drive motor.

[0061] In the embodiment, controlling the low-voltage battery to power the drive motor to store energy in the drive motor also includes limiting the output torque of the drive motor. If the output torque of the drive motor is not limited, it may exceed the power supply capacity of the low-voltage battery, thereby damaging the low-voltage battery. Therefore, to ensure the safety of the drive motor during energy storage and to prevent excessive load on the low-voltage battery, it is very important to limit the output torque of the drive motor.

[0062] Specifically, the output torque of the drive motor can be limited using the formula T = P / w*η, where P is the maximum sustainable output power of the bidirectional DC-DC converter connected in series with the low-voltage battery, w is the current rotor angular velocity of the drive motor, η is the system efficiency of the drive motor, and T is the output torque of the drive motor. If the output torque of the drive motor exceeds a preset threshold, the output torque of the drive motor can be limited by adjusting the control parameters of the drive motor, such as the current rotor angular velocity w and the system efficiency η of the drive motor. This prevents overcurrent from damaging the low-voltage battery and thereby improves the safety of the low-voltage battery.

[0063] In one embodiment of the present disclosure, the preset condition includes the rotor speed of the driving motor reaching a target speed.

[0064] The target speed refers to a reasonable speed threshold that can ensure sufficient accumulation of mechanical energy without causing excessive load on the drive motor.

[0065] In the embodiment, during the energy storage process of the drive motor, as the rotor speed increases, the mechanical energy stored inside the drive motor also increases accordingly. When the rotor speed of the drive motor reaches the target speed, it can be understood that the drive motor has accumulated sufficient mechanical energy. The drive motor switches from speed control to voltage stabilization control, which can provide the required auxiliary power for starting the engine.

[0066] In one embodiment of the present disclosure, the target speed is determined by state parameters of the engine under current circumstances.

[0067] In the embodiment, the target speed is not fixed, but is determined based on the engine state parameters under the current environment, where the engine state parameters include, for example, the engine oil temperature, etc. Changes in the engine state parameters will directly affect the amount of auxiliary power required for engine starting.

[0068] For example, the rotor inertia of a common hybrid vehicle drive motor is on the order of 0.02kgm^2. When the rotor is accelerated to 10,000rpm, the mechanical energy carried by the rotor is approximately: E = 1 / 2*I*w^2, where E is the rotational mechanical energy, I is the rotor moment of inertia, and w is the angular velocity. Substituting the data into the equation, we get E = 11kJ. Considering efficiency, a low-voltage battery (e.g., 12V) with an output efficiency of approximately 2kw is required to power the drive motor for about 5 to 10s. The energy required to start a small-displacement gasoline engine at room temperature is approximately 5 to 20kJ. Through pre-calibration, a relationship between the target speed of the drive motor and the engine oil temperature can be obtained. Generally, the lower the temperature, the greater the energy required, and the more mechanical energy that needs to be pre-calibrated to store in the rotor.

[0069] In one embodiment of the present disclosure, after the starter generator is run to start the engine, it also includes: judging whether the engine is started successfully; if so, controlling the starter generator to charge the low-voltage battery; otherwise, increasing the target speed to update the target speed, and returning to execute the step of controlling the low-voltage battery to power the drive motor according to the updated target speed to store energy for the drive motor.

[0070] In this embodiment, after the starter generator operates to start the engine, the engine startup status is used to determine whether the engine has successfully started. If the engine starts successfully, the starter generator begins to release electrical energy. The high-voltage electricity output by the starter generator is converted to low-voltage electricity through a bidirectional DC-DC converter, which then charges the low-voltage battery to restore the low-voltage battery's charge. If the engine fails to start successfully, the target speed can be increased to update the target speed. After updating the target speed, the process returns to the step of controlling the low-voltage battery to power the drive motor to allow the drive motor to recharge energy. Thus, according to this process, a successful engine start can be ensured, and the process can also return to readjustment if the engine fails to start, thereby improving the reliability of the engine start.

[0071] In one embodiment of the present disclosure, the conditions for low-voltage engine starting include: a high-voltage battery pack failure and / or a high-voltage main relay connected to the high-voltage battery pack is disconnected, and the engine is in an unstarted state and an engine start request is received.

[0072] In this embodiment, by detecting the status of the high-voltage battery pack and the high-voltage main relay, namely, a high-voltage battery pack failure and / or a disconnected high-voltage main relay connected to the high-voltage battery pack, and if this condition is met, the engine status is further detected. If the engine is not started and an engine start request is received, the low-voltage engine start condition is met. By setting the low-voltage engine start condition, the engine can be reliably started using a low-voltage power supply even if the high-voltage power supply is unavailable, thereby improving the vehicle's reliability and emergency response capabilities.

[0073] In one embodiment of the present disclosure, controlling the drive motor to release electrical energy to the starter generator includes: controlling the rotor of the drive motor to reduce its rotational speed to a set value within a preset time.

[0074] The preset time can be a calibrated time, which refers to the minimum time allowed from the time the drive motor begins to release energy until the rotor speed drops to the set value. This ensures that the release of electrical energy and the reduction of speed are completed in a sufficiently short time while avoiding excessive impact or damage to the system. If the set value is 0, for example, during the energy release process, the drive motor quickly reduces the rotor speed from the target speed to 0, thereby quickly releasing electrical energy in a short period of time. This is the process of the drive motor converting mechanical energy into electrical energy.

[0075] In an embodiment, in the process of controlling the drive motor to release electrical energy to the starter generator, the mechanical energy stored in the drive motor needs to be released quickly, that is, the rotor of the drive motor is controlled to drop to a set speed within a preset time to meet the power requirement when the engine is started.

[0076] Specifically, the power required for engine starting is on the order of 5 to 10 kW. The drive motor's rotor speed is controlled to decrease to a set value within a preset time (for example, 1 to 2 seconds, with a set value of 0 rpm). The drive motor's rotor releases stored mechanical energy within 1 to 2 seconds. This can be understood as the drive motor outputting negative torque to decelerate the rotor, recovering the mechanical energy as high-voltage DC power to supply to the starter generator. When the drive motor's rotor speed decreases from 10,000 rpm to 0 rpm in 1 second, the speed change rate reaches 100 rpm / 10 ms, which is similar to the speed change rate during wheel slip and still within the torque-controllable speed change range. This means that with appropriate control strategies, this rapid speed reduction is achievable without damaging the drive motor or the entire system. Furthermore, by precisely controlling the drive motor's output torque and speed change rate, the stored mechanical energy can be quickly released within a short period of time, providing stable and reliable auxiliary power for the starter generator to start the engine.

[0077] In one embodiment of the present disclosure, when a preset condition is met, the system further includes controlling a bidirectional DC-DC converter to convert the voltage output by the low-voltage battery, and using the converted voltage to supply power to the starter generator. In other words, when the preset condition is met, the drive motor is controlled to release electrical energy to the generator, while simultaneously controlling the low-voltage battery to supply power to the starter generator, thereby operating the generator to start the engine. In other words, the low-voltage battery and the drive motor jointly supply power to the starter generator, ensuring sufficient energy to more reliably meet the power requirements for engine starting.

[0078] Specifically, a bidirectional DCDC converter can perform voltage conversion, for example, between high and low voltage. The low-voltage battery outputs low voltage electricity, and the bidirectional DCDC converter can convert the low-voltage electricity from the low-voltage battery into high voltage electricity. This converted high voltage electricity is then used to power the starter generator, enabling the starter generator to operate. Conversely, after the engine is successfully started, the high voltage electricity output by the starter generator can also be converted to low voltage electricity by the bidirectional DCDC converter. This low voltage electricity is then used to power the low-voltage battery, charging it.

[0079] In one embodiment of the present disclosure, when the conditions for low-voltage starting the engine are met, the method further includes: if the drive motor is in a connected state with the wheels of the vehicle, controlling the drive motor to be disconnected from the wheels.

[0080] In an embodiment, during the engine starting process of a hybrid vehicle, when the high-voltage battery pack is not available and the conditions for low-voltage engine starting are met, it is determined whether the drive motor is in a connected state with the wheels. When the drive motor is in a connected state with the wheels, the drive motor is controlled to be disconnected from the wheels, so that the drive motor can accelerate the drive motor rotor to the target speed with a smaller power (for example, 2kw); on the contrary, if the drive motor is connected to the wheels, the drive motor not only has to overcome its own inertia and friction, but also needs to overcome the resistance of the wheels during rotation, which will undoubtedly consume the output capacity of the drive motor and will also greatly increase the difficulty of the engine starting process and the energy required.

[0081] In order to facilitate a better understanding of the embodiment of the present disclosure, the engine starting method of the embodiment of the present disclosure is described in detail below with reference to FIG2 . The specific steps are as follows.

[0082] Step S11, the vehicle is powered on in P gear.

[0083] In step S12 , the high-voltage battery pack fails and / or the high-voltage main relay connected to the high-voltage battery pack is disconnected, the engine is in an unstarted state, and an engine start request is received.

[0084] Step S13: Control the drive motor to disconnect from the wheel.

[0085] Step S14: Control the low-voltage battery to supply power to the drive motor.

[0086] Step S15: determining the target speed according to the engine state parameters under the current environment.

[0087] Step S16, determining whether the rotor speed of the drive motor reaches the target speed, if so, executing step S17; if not, executing step S14.

[0088] Step S17: Control the drive motor to release electric energy to the starter generator, and control the low-voltage battery to supply power to the starter generator.

[0089] In step S18, the driving motor outputs positive torque to drive its rotor to rotate faster, converting electrical energy into mechanical energy for storage.

[0090] Step S19: Start the generator to start the engine.

[0091] Step S20, determining whether the engine is started, if so, executing step S21; if not, executing step S22.

[0092] Step S21, controlling the starter generator to charge the low-voltage battery.

[0093] Step S22: increasing the target speed of the driving motor rotor to update the target speed.

[0094] In step S23, the vehicle enters a drivable state and can be engaged in D / R gear.

[0095] Step S24, end.

[0096] In summary, the engine starting method of the embodiment of the present disclosure determines whether the vehicle meets the conditions for low-voltage engine starting. For example, when the vehicle cannot start the engine through high voltage, the drive motor is controlled to disconnect from the wheels, and the low-voltage battery is controlled to power the drive motor so that the drive motor no longer transmits energy to the wheels but stores energy, thereby providing the energy required for the starter generator to start the engine. When the preset conditions are met, the drive motor is controlled to release electrical energy to the starter generator, causing the starter generator to run to drag the engine to start, completing the low-voltage start of the engine. At the same time, the low-voltage battery can also be controlled to power the starter generator. The energy released by the drive motor and the electrical energy of the low-voltage battery are combined to power the starter generator, thereby providing sufficient energy to start the generator, and then starting the engine through the starter generator. This allows the hybrid vehicle to start the engine smoothly when the high-voltage battery pack fails and the energy of the high-voltage battery pack cannot be used, allowing the vehicle to drive normally and improving the reliability of the vehicle.

[0097] A second embodiment of the present disclosure provides an engine starting system. As shown in FIG3 , the engine starting system 2 includes a low-voltage battery 22 , a drive motor 25 , a starter generator 26 and a controller 27 .

[0098] Among them, the low-voltage battery 22 is used to provide low-voltage electricity; the controller 27 is connected to the low-voltage battery 22, the drive motor 25 and the starter generator 26 respectively; the drive motor 25 can be connected or disconnected from the vehicle's wheels 42; the starter generator 26 is also connected to the vehicle's engine 41; the controller 27 is used to execute the engine 41 starting method described in any one of the above embodiments of the present disclosure.

[0099] In one embodiment of the present disclosure, as shown in Figure 3, the engine starting system 2 also includes a bidirectional DCDC converter 23, which is connected to the low-voltage battery 22 and is used to convert the voltage output by the low-voltage battery 22, for example, converting the low-voltage electricity output by the low-voltage battery 22 into high-voltage electricity, so as to power the drive motor 25 or the starter generator 26; or, the bidirectional DCDC converter 23 can convert the voltage output by the starter generator 26 and transmit it to the low-voltage battery 22, for example, converting the high-voltage electricity output by the starter generator 26 into low-voltage electricity, and then transmitting it to the low-voltage battery 22 to charge the low-voltage battery 22.

[0100] In one embodiment of the present disclosure, as shown in FIG3 , the engine starting system 2 further includes a high-voltage battery pack 21 and a high-voltage main relay 24 . The high-voltage battery pack 21 is connected to the high-voltage busbar via the high-voltage main relay 24 .

[0101] In a specific embodiment, as shown in Figure 3, the low-voltage battery 22 is connected to the high-voltage bus through a bidirectional DCDC converter 23. The low-voltage battery 22 can supply power to the high-voltage bus through the bidirectional DCDC converter 23, and can also receive electrical energy provided by the high-voltage bus for charging; the bidirectional DCDC converter 23 is connected to the controller 27 through the high-voltage bus; the controller 27 is connected to the starter generator 26 and the drive motor 25.

[0102] Specifically, the bidirectional DC-DC converter 23 is a power supply device with bidirectional buck-boost functionality, converting high-voltage DC power to low-voltage DC power. As shown in Figure 3, the engine starting system 2 is a series-mode hybrid system comprising an engine 41, a starter generator 26 connected to the crankshaft of the engine 41, and a drive motor 25 that can be disconnected from the drive shaft of the wheels 42. The starter generator 26 and the drive motor 25 are connected to the same high-voltage busbar via a controller 27. The high-voltage busbar is connected to the high-voltage battery pack 21 (or connected via a boost circuit). A high-voltage main relay 24 is located between the controller 27 and the high-voltage battery pack 21. The low-voltage battery 22 is connected to the high-voltage main relay 24 on the side of the controller 27 via the bidirectional DC-DC converter 23.

[0103] In a specific embodiment, as shown in FIG4 , the low-voltage battery 22 is a schematic diagram of accelerating the rotor of the drive motor 25. When the conditions for low-voltage starting the engine 41 are met, the controller 27 controls the drive motor 25 to be disconnected from the wheels 42 of the vehicle. The low-voltage battery 22 supplies power to the high-voltage bus through the bidirectional DCDC converter 23. The controller 27 performs power conversion to convert the DC power output by the high-voltage bus into AC power. The drive motor 25 is connected to the controller 27. The drive motor 25 receives the AC power converted by the controller 27 to complete the power supply process of the low-voltage battery 22 for the drive motor 25, thereby causing the drive motor 25 to output positive torque to drive its rotor to rotate faster, converting electrical energy into mechanical energy storage, so that the rotor speed of the drive motor 25 reaches the target speed.

[0104] When the rotor speed of the drive motor 25 reaches the target speed, referring to the schematic diagram shown in Figure 5 in which the low-voltage battery 22 and the rotor mechanical energy of the drive motor 25 jointly power the starter generator 26, the drive motor 25 is converted from speed control to voltage stabilization control, that is, the mechanical energy stored in the drive motor 25 is converted into electrical energy, and stabilized to the voltage at the output end of the controller 27. The voltage command value is consistent with the output voltage set by the bidirectional DCDC converter 23. At this time, the low-voltage battery 22 provides electrical energy to the controller 27. At the same time, the drive motor 25 releases electrical energy to power the controller 27. The electrical energy provided by the low-voltage battery 22 and the drive motor 25 is used to power the starter generator 26 through the controller 27, wherein the controller 27 can have a filtering function.

[0105] After the starter generator 26 receives the electric energy output by the controller 27, it outputs positive torque through the high-voltage bus to drag the engine 41 to start. During this process, the speed and torque change trends of the drive motor 25 and the starter generator 26 can be referred to Figure 6. In the initial stage, the low-voltage battery 22 accelerates the energy storage for the rotor of the drive motor 25. Through the precise control of the controller 27, the drive motor 25 reduces its speed in a short time, converts the stored mechanical energy into electrical energy, and supplies this part of the electrical energy to the capacitor of the electronic control bus. At the same time, the starter generator 26 outputs positive torque to drag the engine 41, completing the start of the engine 41.

[0106] In particular embodiments, controller 27 includes a motor controller.

[0107] According to the engine starting system 2 of the disclosed embodiment, it is determined whether the vehicle meets the conditions for low-voltage engine starting. For example, if the vehicle cannot start the engine through high voltage, the drive motor is disconnected from the wheels and the low-voltage battery 22 is controlled to power the drive motor 22, so that the drive motor 25 no longer transmits energy to the wheels but stores energy, thereby providing the energy required for the starter generator 26 to start the engine 41. When the preset conditions are met, the drive motor 25 is controlled to release electrical energy to the starter generator 26, causing the starter generator 26 to operate and drive the engine 41 to start, completing the low-voltage start of the engine 41. At the same time, the low-voltage battery 22 can also be controlled to power the starter generator 26. The energy released by the drive motor 25 and the electrical energy of the low-voltage battery 22 are combined to power the starter generator 26, thereby providing sufficient energy to start the generator 26, and then start the engine 41 through the starter generator 26. This allows the hybrid vehicle to successfully start the engine 41 even if the high-voltage battery pack fails and the energy of the high-voltage battery pack cannot be used, allowing the vehicle to drive normally and improving the reliability of the vehicle.

[0108] In one embodiment of the present disclosure, as shown in FIG3 , the engine starting system 2 further includes a decoupling device 28 ; the decoupling device 28 is respectively connected to the drive motor 25 and the wheel 42 , and the controller 27 controls the connection state of the decoupling device 28 to connect or disconnect the drive motor 25 and the wheel 42 .

[0109] In an embodiment, as shown in FIG3 , the decoupling device 28 is connected to the drive motor 25 and the wheel 42 respectively. The controller 27 can control the connection or disconnection of the drive motor 25 and the wheel 42 by controlling the connectivity state of the decoupling device 28. When the engine 41 needs to be started, the controller 27 controls the drive motor 25 to be disconnected from the wheel 42 through the decoupling device 28, so that the drive motor 25 can provide the mechanical energy required for starting the engine 41.

[0110] In one embodiment of the present disclosure, the controller 27 is a motor controller.

[0111] In the embodiment, the controller 27 is a motor controller, which can perform power conversion and convert direct current into alternating current. By designating the controller 27 as a motor controller, it can directly control the operation of the drive motor 25, and can also control the coordinated work of the entire engine starting system 2 to ensure the stable operation of the entire system.

[0112] In one embodiment of the present disclosure, the controller 27 controls the low-voltage battery 22 to power the drive motor 25 so that the drive motor 25 stores energy, including: controlling the low-voltage battery 22 to power the drive motor 25 so that the rotor of the drive motor 25 accelerates rotation and converts electrical energy into mechanical energy for storage.

[0113] In one embodiment of the present disclosure, the controller 27 is used to limit the output torque of the drive motor 25 while controlling the low-voltage battery 22 to supply power to the drive motor 25 so that the drive motor 25 stores energy.

[0114] In one embodiment of the present disclosure, the preset condition includes the rotor speed of the driving motor 25 reaching a target speed.

[0115] In one embodiment of the present disclosure, the target speed is determined by state parameters of the engine 41 under current circumstances.

[0116] In one embodiment of the present disclosure, after the starter generator 26 runs to start the engine 41, the controller 27 is also used to: determine whether the engine 41 is started successfully; if so, control the starter generator 26 to charge the low-voltage battery 22; otherwise, increase the target speed to update the target speed, and return to execute the step of controlling the low-voltage battery 22 to power the drive motor 25 according to the updated target speed to store energy for the drive motor 25.

[0117] In one embodiment of the present disclosure, the conditions for low-voltage starting of the engine 41 include: the high-voltage battery pack 21 fails and / or the high-voltage main relay 24 connected to the high-voltage battery pack 21 is disconnected, and the engine 41 is in an unstarted state and a start request for the engine 41 is received.

[0118] In one embodiment of the present disclosure, the controller 27 controls the drive motor 25 to release electrical energy to the starter generator 26 , including: controlling the rotor of the drive motor 25 to reduce its speed to a set value within a preset time.

[0119] In one embodiment of the present disclosure, when a preset condition is met, the controller 27 is further configured to control the bidirectional DCDC converter 23 to convert the voltage output by the low-voltage battery 22 and supply power to the starter generator 26 through the converted voltage.

[0120] In one embodiment of the present disclosure, when the conditions for low-voltage starting the engine 41 are met, the controller 27 is further configured to control the drive motor 25 to be disconnected from the vehicle wheels 42 when the drive motor 25 is in a connected state.

[0121] In summary, the present disclosure provides a method in which a low-voltage battery 22 first supplies power to a high-voltage bus through a bidirectional DCDC converter 23. After the drive motor 25 is disconnected from the wheel 42, the low-voltage battery 22 accelerates the rotor of the drive motor 25 to a target speed with a relatively small power (such as 2 kW), and the drive motor 25 enters a voltage stabilization state. At the same time, the generator 26 is started to output positive torque to drag the engine 41, so that the engine 41 starts the system.

[0122] Thus, the engine starting system 2 of the disclosed embodiment determines whether the conditions for low-voltage starting the engine 41 are met. For example, if the vehicle cannot start the engine 41 using high voltage, the system controls the drive motor 25 to disconnect from the wheels 42 and controls the low-voltage battery 22 to power the drive motor 25, so that the drive motor 25 no longer transmits energy to the wheels 42 but stores energy, thereby providing the energy required for the starter generator 26 to start the engine 41. When the preset conditions are met, the system controls the drive motor 25 to release energy to the starter generator 26, causing the starter generator 26 to operate and drive the engine 41 to start, completing the low-voltage starting of the engine 41. At the same time, the system controls the low-voltage battery 22 to power the starter generator 26. The energy released by the drive motor 25 and the energy from the low-voltage battery 22 are combined to power the starter generator 26, thereby providing sufficient energy to start the generator 26, and then start the engine 41 through the starter generator 26. This allows the hybrid vehicle to successfully start the engine 41 even if the high-voltage battery pack fails and cannot use the energy of the high-voltage battery pack, thereby ensuring normal vehicle driving and improving vehicle reliability.

[0123] A further embodiment of the present disclosure also discloses a controller 27, as shown in Figure 7, the controller 27 includes a processor 271 and a memory 272, the memory 272 stores an engine starting program, and the engine starting program can be executed by the processor 271. When the engine starting program is executed by the processor 271, the engine starting method described in any one of the above embodiments of the present disclosure is implemented.

[0124] According to the controller 27 of the disclosed embodiment, the controller 27 determines whether the vehicle meets the conditions for low-voltage starting of the engine 41. For example, if the vehicle cannot start the engine 41 using high voltage, the controller 27 controls the drive motor 25 to disconnect from the wheels 42 and controls the low-voltage battery 22 to supply power to the drive motor 25, so that the drive motor 25 no longer transmits energy to the wheels 42 but stores energy, thereby providing the starter generator 26 with the mechanical energy required to start the engine 41. When the preset conditions are met, the controller 27 controls the drive motor 25 to release electrical energy to the starter generator 26, causing the starter generator 26 to operate and drive the engine 41 to start, completing the low-voltage starting of the engine 41. At the same time, the controller 27 can also control the low-voltage battery 22 to supply power to the starter generator 26. The energy released by the drive motor 25 and the electrical energy of the low-voltage battery 22 are combined to supply power to the starter generator 26, thereby providing sufficient energy to start the generator 26, and then start the engine 41 through the starter generator 26. This allows the hybrid vehicle to successfully start the engine 41 even if the high-voltage battery pack fails and cannot use the energy of the high-voltage battery pack, thereby ensuring normal vehicle operation and improving vehicle reliability.

[0125] A further embodiment of the present disclosure also discloses a computer-readable storage medium.

[0126] An engine starting program is stored on the computer-readable storage medium of the embodiment of the present disclosure. When the engine starting program is executed by the processor 271, the engine starting method described in any one of the above embodiments of the present disclosure is implemented.

[0127] According to the computer-readable storage medium of the embodiment of the present disclosure, when the engine starting program stored thereon is executed by the processor, it is determined whether the vehicle meets the conditions for low-voltage engine starting. For example, if the vehicle cannot start the engine through high voltage, the drive motor is controlled to disconnect from the wheels and the low-voltage battery is controlled to power the drive motor so that the drive motor no longer transmits energy to the wheels but stores energy, thereby providing the energy required for the starter generator to start the engine. When the preset conditions are met, the drive motor is controlled to release electrical energy to the starter generator, causing the starter generator to operate to drive the engine to start, completing the low-voltage start of the engine. At the same time, the low-voltage battery can also be controlled to power the starter generator. The energy released by the drive motor and the electrical energy of the low-voltage battery are combined to power the starter generator, thereby providing sufficient energy to start the generator, and then starting the engine through the starter generator. This allows the hybrid vehicle to successfully start the engine even when the high-voltage battery pack fails and the energy of the high-voltage battery pack cannot be used, allowing the vehicle to drive normally and improving the reliability of the vehicle.

[0128] Based on the engine starting system 2 of the above embodiment, a further embodiment of the present disclosure also discloses a hybrid vehicle 4. As shown in FIG3 , the hybrid vehicle 4 includes an engine 41 and the engine starting system 2 described in any one of the above embodiments of the present disclosure.

[0129] According to the hybrid vehicle 4 of the present disclosure, it is determined whether the vehicle meets the conditions for low-voltage starting of the engine 41. For example, if the vehicle cannot start the engine 41 using high voltage, the drive motor 25 is disconnected from the wheels 42 and the low-voltage battery 22 is controlled to supply power to the drive motor 25. This causes the drive motor 25 to no longer transmit energy to the wheels 42 but to store energy, thereby enabling the starter generator 26 to provide the mechanical energy required to start the engine 41. When a preset condition is met, the drive motor 25 is controlled to release electrical energy to the starter generator 26, causing the starter generator 26 to operate and drive the engine 41 to start, completing the low-voltage starting of the engine 41. At the same time, the low-voltage battery 22 can also be controlled to supply power to the starter generator 26. The energy released by the drive motor 25 and the electrical energy of the low-voltage battery 22 are combined to supply power to the starter generator 26, thereby providing sufficient energy to start the generator 26, and then starting the engine 41 through the starter generator 26. This allows the hybrid vehicle to successfully start the engine 41 even if the high-voltage battery pack fails and cannot use the energy of the high-voltage battery pack, thereby ensuring normal vehicle operation and improving vehicle reliability.

[0130] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "example," "specific example," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0131] Although the embodiments of the present disclosure have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and alterations may be made to the embodiments without departing from the principles and spirit of the present disclosure, the scope of which is defined by the claims and their equivalents.

Claims

1. An engine starting method, characterized in that: include: When the conditions for starting the engine at low voltage are met, controlling the low-voltage battery to supply power to the drive motor so that the drive motor stores energy; and When a preset condition is met, the drive motor is controlled to release electric energy to the starter generator, so that the starter generator operates to start the engine.

2. The engine starting method according to claim 1, characterized in that: The controlling the low-voltage battery to supply power to the drive motor so that the drive motor stores energy includes: The low-voltage battery is controlled to supply power to the drive motor so that the rotor of the drive motor rotates faster, thereby converting electrical energy into mechanical energy for storage.

3. The engine starting method according to claim 1 or 2, characterized in that: The process of controlling the low-voltage battery to supply power to the drive motor so that the drive motor stores energy further includes: The output torque of the driving motor is limited.

4. The engine starting method according to any one of claims 1 to 3, characterized in that: The preset condition includes: the rotor speed of the drive motor reaches the target speed.

5. The engine starting method according to claim 4, characterized in that: The target speed is determined by the state parameters of the engine under the current environment.

6. The engine starting method according to claim 4 or 5, characterized in that: After the starter generator is operated to start the engine, the method further comprises: Determining whether the engine is started successfully; If so, control the starter generator to charge the low-voltage battery; otherwise, increase the target speed to update the target speed, and return to the step of controlling the low-voltage battery to power the drive motor according to the updated target speed to store energy in the drive motor.

7. The engine starting method according to any one of claims 1 to 6, characterized in that: The conditions for starting the engine at low pressure include: The high-voltage battery pack fails and / or the high-voltage main relay connected to the high-voltage battery pack is disconnected, the engine is in an unstarted state, and a start request for the engine is received.

8. The engine starting method according to any one of claims 1 to 7, characterized in that: The controlling the drive motor to release electric energy to the starter generator includes: The rotor of the driving motor is controlled to reduce its speed to a set value within a preset time.

9. The engine starting method according to any one of claims 1 to 8, characterized in that: When the preset conditions are met, the following steps are also included: The bidirectional DCDC converter is controlled to convert the voltage output by the low-voltage battery, and the converted voltage is used to supply power to the starter generator.

10. The engine starting method according to any one of claims 1 to 9, characterized in that: When the conditions for starting the engine at low pressure are met, the method further includes: If the drive motor is in a connected state with the wheel of the vehicle, the drive motor is controlled to be disconnected from the wheel.

11. An engine starting system (2), characterized in that: include: A low-voltage battery (22), wherein the low-voltage battery (22) is used to provide low-voltage electricity; a drive motor (25) capable of being connected to or disconnected from the wheels (42) of the vehicle; a starter generator (26) connected to an engine (41) of the vehicle; and A controller (27), wherein the controller (27) is connected to the low-voltage battery (22), the drive motor (25) and the starter generator (26) respectively, and the controller (27) is used to execute the engine starting method according to any one of claims 1 to 10.

12. The engine starting system (2) according to claim 11, characterized in that Also includes: A bidirectional DCDC converter (23) is connected to the low-voltage battery (22) and is used to convert the voltage output by the low-voltage battery (22), or to convert the voltage output by the starter generator (26) and transmit it to the low-voltage battery (22).

13. The engine starting system (2) according to claim 11 or 12, characterized in that Also includes: Decoupling device (28); The decoupling device (28) is respectively connected to the drive motor (25) and the wheel (42), and the controller (27) controls the connection state of the decoupling device to control the connection or disconnection between the drive motor (25) and the wheel (42).

14. The engine starting system (2) according to any one of claims 11 to 13, characterized in that: The controller (27) is a motor controller.

15. A controller (27), characterized in that include: Processor (271); Memory (272), wherein the memory (272) stores An engine starting program, wherein the engine starting program can be executed by the processor (271), and when the engine starting program is executed by the processor (271), the engine starting method according to any one of claims 1 to 10 is implemented.

16. A computer-readable storage medium, characterized in that An engine starting program is stored on the computer-readable storage medium, and when the engine starting program is executed by the processor (271), the engine starting method according to any one of claims 1 to 10 is implemented.

17. A hybrid electric vehicle (4), characterized in that: include: Engine (41); and An engine starting system (2) according to any one of claims 11 to 14.

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