A control method for engine series power generation of a hybrid vehicle in a low temperature environment

Abstract

The application discloses a control method for engine series power generation of a hybrid vehicle in a low-temperature environment, and the method comprises the following steps: when the environmental temperature is lower than a preset temperature threshold, the engine is controlled to operate in a rotating speed control mode to maintain the power generation rotating speed; the generator is controlled to operate in a torque control mode to maintain the power generation torque; the target rotating speed of the engine is calculated based on the total power demand; and the target charging torque of the generator is calculated based on the actual power of the battery to avoid overcharging or overdischarging of the battery. According to the scheme, the available power of the battery or the battery current is subjected to closed-loop control, the risk of overcharging or overdischarging of the battery is reduced, and the safety and service life of the battery are improved.

Description

Technical Field

[0001] This invention relates to the field of engine technology, and in particular to a control method for generating electricity in series between engines in hybrid vehicles under low-temperature conditions. Background Technology

[0002] Hybrid electric vehicles (HEVs) can be mainly classified into series, parallel, and series-parallel types based on their structural configuration. Their powertrain typically includes both an internal combustion engine and a battery system. Compared to pure electric vehicles, HEVs, with their multiple operating modes, are better able to adapt to various complex and harsh operating conditions. However, in harsh environments such as low temperatures, the precision of vehicle control faces more severe challenges, placing higher demands on energy management strategies.

[0003] In low-temperature environments, the chemical activity of power batteries decreases significantly, leading to a substantial reduction in their charge and discharge capabilities. For example, in ultra-low temperatures of -40°C, the usable battery capacity is severely degraded, and lithium metal precipitation is highly likely to occur during charging, posing a risk of puncturing the separator and causing an internal short circuit, seriously threatening battery safety and lifespan. Simultaneously, low temperatures also adversely affect engine operation: the viscosity of the engine lubrication system oil increases, and frictional torque increases, resulting in a significant deviation between the actual engine output torque and the target torque requested by the controller, thus affecting the power generation control accuracy of the entire range extender system. Summary of the Invention

[0004] In view of the above, the present invention aims to provide a control method for engine series power generation in hybrid vehicles under low temperature conditions, so as to solve the aforementioned technical problems.

[0005] The technical solution adopted in this invention is as follows:

[0006] This invention provides a control method for series-connected generator generation in hybrid vehicles under low-temperature conditions, including:

[0007] When the ambient temperature is lower than the preset temperature threshold, the engine is controlled to operate in speed control mode to maintain the power generation speed;

[0008] Control the generator to operate in torque control mode to maintain the generating torque;

[0009] Calculate the engine's target speed based on the total power requirement;

[0010] Closed-loop control is performed based on the actual power of the battery to calculate the target charging torque of the generator in order to avoid overcharging or over-discharging of the battery.

[0011] Optionally, the target engine speed is determined by a calibration table, which is calibrated based on the total power requirement and the current vehicle speed.

[0012] Optionally, the target charging torque of the generator is calculated in the following way:

[0013] Calculate the feedforward torque based on the total charging power and the current generator speed;

[0014] The proportional term torque is obtained by multiplying the difference between the target charging power and the actual charging power by a proportionality factor.

[0015] The power difference is integrated and multiplied by the integration coefficient to obtain the integral term torque;

[0016] The total charging torque is obtained by summing the feedforward torque, the proportional torque, and the integral torque.

[0017] Optionally, the target charging power is the minimum charging power of the battery multiplied by a preset coefficient.

[0018] Optionally, the preset temperature threshold is determined through calibration.

[0019] The present invention also provides a vehicle controller for implementing the above-described control method, comprising:

[0020] The engine control module is used to output engine speed control commands;

[0021] The generator control module is used to output generator torque control commands;

[0022] The power calculation module is used to calculate the total power demand and the actual battery power.

[0023] The closed-loop control module is used to adjust the generator torque request based on the difference between the actual battery power and the target power.

[0024] The above-described solution of the present invention has at least the following beneficial effects:

[0025] The above-mentioned solution of the present invention includes: when the ambient temperature is lower than a preset temperature threshold, controlling the engine to operate in a speed control mode to maintain the power generation speed; controlling the generator to operate in a torque control mode to maintain the power generation torque; calculating the target speed of the engine based on the total power demand; and performing closed-loop control based on the actual power of the battery to calculate the target charging torque of the generator to avoid overcharging or over-discharging of the battery. The solution of the present invention performs closed-loop control on the available power or current of the battery, reducing the risk of overcharging and over-discharging, and improving the safety and lifespan of the battery. Attached Figure Description

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described below with reference to the accompanying drawings, wherein:

[0027] Figure 1A flowchart illustrating the control method for engine series power generation in a hybrid vehicle under low-temperature conditions, provided in an embodiment of the present invention. Detailed Implementation

[0028] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0029] This invention proposes an embodiment of a control method for series-connected power generation of an engine in a hybrid vehicle under low-temperature conditions. Specifically, as follows: Figure 1 As shown, it includes:

[0030] Step 11: When the ambient temperature is lower than the preset temperature threshold, control the engine to operate in speed control mode to maintain the power generation speed;

[0031] Step 12: Control the generator to operate in torque control mode to maintain the generating torque;

[0032] Step 13: Calculate the target engine speed based on the total power requirement;

[0033] Step 14: Perform closed-loop control based on the actual power of the battery and calculate the target charging torque of the generator to avoid overcharging or over-discharging of the battery.

[0034] In this embodiment, the calculation of the series power generation mode differs between low-temperature and normal operating conditions. At low temperatures, the battery's charging and discharging capacity is limited, and overcharging can damage the battery. Therefore, a more precise control strategy is required. Target torque for the motor and target speed for the engine are requested in motor torque mode and engine speed mode, respectively. The target torque for the motor is determined by closed-loop control of the actual battery power, aiming to prevent overcharging, and thus requesting the target charging torque for the motor.

[0035] Furthermore, the target speed of the engine is determined by a calibration table, which is calibrated based on the total power requirement and the current vehicle speed.

[0036] Furthermore, the target charging torque of the generator is calculated in the following manner:

[0037] Calculate the feedforward torque based on the total charging power and the current generator speed;

[0038] The proportional term torque is obtained by multiplying the difference between the target charging power and the actual charging power by a proportionality factor.

[0039] The power difference is integrated and multiplied by the integration coefficient to obtain the integral term torque;

[0040] The total charging torque is obtained by summing the feedforward torque, the proportional torque, and the integral torque.

[0041] Furthermore, the target charging power is the battery's minimum charging power multiplied by a preset coefficient.

[0042] Furthermore, the preset temperature threshold is determined through calibration.

[0043] In practice, the engine uses speed control to maintain the generator speed, while the generator uses torque to maintain the generator torque. At low temperatures, engine speed control maintains the speed better than torque control, and torque fluctuations are less noticeable. However, both motor torque control and speed control offer relatively high precision. Therefore, in low-temperature series power generation mode, engine speed control, compared to engine torque control, can better control the target power output.

[0044] Low-temperature series power generation aims to meet the driver's driving needs, keeping the battery in a zero-current state as much as possible at extremely low temperatures, meaning the battery pack neither needs charging nor discharging. At low temperatures, the required battery charging and discharging power must be within the battery's allowable charging power range. Therefore, calculating the generating torque requires closed-loop control of the actual battery power. The engine speed request, as described above, is obtained by referring to a table based on the total power demand and the current vehicle speed.

[0045] The motor torque request is PI closed-loop control. Feedforward torque: The proportional term (P term) of the charging torque is calculated based on the total charging power and speed. Torque: The target charging power is obtained by multiplying the minimum charging power of the battery by a coefficient. The actual power is calculated based on the voltage and current fed back by the battery. The P term torque is obtained by looking up the power difference between the target charging power and the actual power and multiplying the power difference by the P term coefficient.

[0046] Integral term (I-term) torque: Find the I-term coefficient based on the calculated power difference, then integrate the power difference * I-term coefficient over time to obtain the I-term torque. Total charging demand torque = feedforward torque + P-term torque + I-term torque.

[0047] This embodiment also provides a vehicle controller for implementing the above control method, including:

[0048] The engine control module is used to output engine speed control commands;

[0049] The generator control module is used to output generator torque control commands;

[0050] The power calculation module is used to calculate the total power demand and the actual battery power.

[0051] The closed-loop control module is used to adjust the generator torque request based on the difference between the actual battery power and the target power.

[0052] The control method for engine series power generation in hybrid vehicles in this embodiment performs closed-loop control on the available power or current of the battery, reducing the risk of overcharging and over-discharging the battery and improving the safety and lifespan of the battery.

[0053] It should be noted that this device is the same as the method described above. All implementations in the above method embodiments are applicable to the embodiments of this device and can achieve the same technical effect.

[0054] An embodiment of the present invention also provides a computing device, including: a processor and a memory storing a computer program, wherein the computer program, when executed by the processor, performs the method described in the above embodiments. All implementations in the above method embodiments are applicable to this embodiment and can achieve the same technical effect.

[0055] In this embodiment of the invention, a computer-readable storage medium is also provided, storing instructions that, when executed on a computer, cause the computer to perform the method described in the above embodiments. All implementations of the methods described in the above embodiments are applicable to this embodiment and can achieve the same technical effect.

[0056] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0057] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0058] In the embodiments provided by this invention, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0059] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0060] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0061] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, essentially, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, ROM, RAM, magnetic disks, or optical disks.

[0062] Furthermore, it should be noted that in the apparatus and method of the present invention, it is obvious that the components or steps can be decomposed and / or recombined. These decompositions and / or recombinations should be considered equivalent solutions of the present invention. Moreover, the steps performing the above series of processes can naturally be executed in the order described, but are not necessarily required to be executed in chronological order; some steps can be executed in parallel or independently of each other. Those skilled in the art will understand that all or any step or component of the method and apparatus of the present invention can be implemented in any computing device (including processors, storage media, etc.) or network of computing devices, in hardware, firmware, software, or a combination thereof. This is something that those skilled in the art can achieve by using their basic programming skills after reading the description of the present invention.

[0063] Therefore, the object of the present invention can also be achieved by running a program or a set of programs on any computing device. The computing device can be a known general-purpose device. Therefore, the object of the present invention can also be achieved simply by providing a program product containing program code implementing the method or apparatus. That is, such a program product also constitutes the present invention, and the storage medium storing such a program product also constitutes the present invention. Obviously, the storage medium can be any known storage medium or any storage medium developed in the future. It should also be noted that in the apparatus and method of the present invention, it is obvious that the components or steps can be decomposed and / or recombined. These decompositions and / or recombinations should be considered equivalent to the present invention. Furthermore, the steps performing the above series of processes can naturally be performed in the order described, but are not necessarily required to be performed in chronological order. Some steps can be performed in parallel or independently of each other.

[0064] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A control method for series-connected generator generation in a hybrid vehicle under low-temperature conditions, characterized in that, include: When the ambient temperature is lower than the preset temperature threshold, the engine is controlled to operate in speed control mode to maintain the power generation speed; Control the generator to operate in torque control mode to maintain the generating torque; Calculate the engine's target speed based on the total power requirement; Closed-loop control is performed based on the actual power of the battery to calculate the target charging torque of the generator in order to avoid overcharging or over-discharging of the battery. The target charging torque of the generator is calculated in the following way: Calculate the feedforward torque based on the total charging power and the current generator speed; The proportional term torque is obtained by multiplying the difference between the target charging power and the actual charging power by a proportionality factor. The difference between the target charging power and the actual charging power is integrated and multiplied by the integration coefficient to obtain the integral term torque. The total charging torque is obtained by summing the feedforward torque, the proportional torque, and the integral torque.

2. The control method for engine series power generation in a hybrid vehicle under low-temperature conditions according to claim 1, characterized in that, The target speed of the engine is determined by a calibration table, which is calibrated based on the total power requirement and the current vehicle speed.

3. The control method for engine series power generation in a hybrid vehicle under low-temperature conditions according to claim 1, characterized in that, The target charging power is the battery's minimum charging power multiplied by a preset coefficient.

4. The control method for engine series power generation in a hybrid vehicle under low-temperature conditions according to claim 1, characterized in that, The preset temperature threshold is determined through calibration.

5. A vehicle controller for implementing the control method according to any one of claims 1 to 4, characterized in that, include: The engine control module is used to output engine speed control commands; The generator control module is used to output generator torque control commands; The power calculation module is used to calculate the total power demand and the actual battery power. The closed-loop control module is used to adjust the generator torque request based on the difference between the actual battery power and the target power.

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