CN109915298B - Control method for quick start of engine of hybrid electric vehicle - Google Patents
Control method for quick start of engine of hybrid electric vehicle Download PDFInfo
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Abstract
A control method for quickly starting the engine of mixed power car features that the driving mode is chosen as ECO mode or SPORT mode, and the engine starting command is sent out to start the engine. The design can not only realize the quick start of the engine and adapt to the limit power requirement on the basis of effectively identifying the driving intention of a driver and the real-time working condition of the vehicle, but also avoid the failure faults of a high-voltage electric system and a mechanical power component.
Description
Technical Field
The invention relates to a starting method of an engine, belongs to the technical field of hybrid electric vehicle control, and particularly relates to a control method for quickly starting the engine of a hybrid electric vehicle.
Background
The existing pure electric vehicles and plug-in hybrid electric vehicles are limited by low perfection of charging facilities, so that the whole vehicle energy management system cannot effectively control the electric quantity of a high-voltage battery, and the problems of anxiety driving range, obvious attenuation of vehicle dynamic performance in a power-loss state of the high-voltage battery and the like are caused. The hybrid electric vehicle with the engine as the range extending equipment can solve the anxiety problem of the driving range of the pure electric vehicle by taking petroleum fuel as the energy source of the whole vehicle, and can control the working state of the engine according to the real-time running working condition of the vehicle so as to realize the effective control of the energy management system of the whole vehicle on the electric quantity of the high-voltage battery, thereby avoiding the power loss of the high-voltage power battery on the premise of ensuring the dynamic property of the vehicle.
In order to realize an efficient overall energy management strategy, the starting time and the expected working interval of the engine need to be determined according to real-time information such as vehicle running conditions, driver intentions, the charge state of a high-voltage power battery and the like. Therefore, the hybrid electric vehicle must realize active control of engine starting, and the starting method is divided into two methods, namely, the low-voltage starter system is used for realizing the automatic starting function of the engine, and the ISG high-voltage generator mechanically connected with the engine is converted into a motor to reversely drag the engine to complete starting in the starting process.
The energy sources of the starting devices in the two methods are respectively from an 12/24V low-voltage battery and a high-voltage power battery, wherein the starting method using the high-voltage power battery as the energy source benefits from larger starter power, the starting time of the engine can be obviously shortened, but for the scene that a driver outputs a high-power instruction or hurts a driving mode and other extreme power requirements, the transient response of the engine starting in the prior art is less concerned, and the optimization of the engine starting process according to the transient instruction or the driving intention of the driver is not considered.
The information disclosed in this background section is only for enhancement of understanding of the general background of the patent application and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
Disclosure of Invention
The invention aims to overcome the defects and problems that the engine can not be quickly started and the limit power requirement can not be met on the basis of effectively identifying the driving intention of a driver and the real-time working condition of a vehicle in the prior art, and provides a control method for quickly starting the engine of a hybrid electric vehicle, which can realize the quick start of the engine and the limit power requirement on the basis of effectively identifying the driving intention of the driver and the real-time working condition of the vehicle.
In order to achieve the above purpose, the technical solution of the invention is as follows: a control method for the quick start of the engine of a hybrid electric vehicle;
the hybrid electric vehicle comprises a vehicle control unit, a driving motor controller, a driving motor system, a high-voltage power battery, a high-voltage generator, an engine, a driving mode selection unit and an ECU (electronic control unit), wherein the vehicle control unit is in signal connection with the driving motor controller, the high-voltage power battery, the high-voltage generator and the driving mode selection unit, the driving motor controller is electrically connected with the driving motor system, the driving motor system is in mechanical transmission connection with a driving wheel 31, the high-voltage power battery is electrically connected with the driving motor controller and the high-voltage generator, and the high-voltage generator is in mechanical transmission connection with the engine;
the control method comprises the following steps: firstly, a driver selects a driving mode as an ECO mode or a SPORT mode through a driving mode selection unit, the engine rotating speeds corresponding to the ECO mode and the SPORT mode are an economic rotating speed interval and a peak power rotating speed interval respectively, then a vehicle controller sends an engine starting instruction to start, in the starting process, the starting torque of a high-voltage generator is adjusted firstly until the rotating speed of the engine reaches the economic rotating speed interval or the peak power rotating speed interval, and when the engine injects oil normally, the high-voltage generator is switched from an electric mode to a power generation mode, an electric energy compensation mechanism is triggered at the same time, the high-voltage generator increases the power generation torque according to the real-time power demand, a high-voltage power battery under the discharging working condition is adjusted to the charging working condition to compensate the electric energy consumed by the high-voltage generator in the quick starting process, the over-discharge fault of the battery is avoided, and, at this point the fast boot is complete.
The drive motor system comprises a distributed electric drive system or a centralized electric drive system.
When the driving mode is an ECO mode, adjusting the starting torque of the high-voltage generator through power closed-loop control and maximum starting torque limitation;
and when the driving mode is the SPORT mode, the starting torque of the high-voltage generator is adjusted through a power closed-loop control and maximum starting torque limitation and an engine runaway prevention protection mechanism.
The normal oil injection of the engine refers to the successful activation of the engine, and whether the engine is successfully activated is determined by an engine oil injection system working state judgment module, wherein the state variables of the engine oil injection system working state judgment module comprise the real-time rotating speed of the engine, the actual output torque of the high-voltage generator and the real-time output torque of the engine.
Under the electric energy compensation mechanism, in the action stage of the electric energy compensation mechanism, the ECU increases the circulating oil injection quantity to stabilize the rotating speed of the engine, and the oil injection system completes the construction work of high oil injection pressure until the high-voltage generator enters a normal power generation working state.
When the vehicle control unit sends an engine starting instruction to start, if the engine is judged to be in a cold state, a cold start control strategy is triggered to warm the engine, otherwise, if the engine is in a warm state, the engine continues to be started downwards according to the steps; wherein, the engine is in a cold machine state or a hot machine state and is judged according to the following formula:
in the formula TCoolantRepresenting the engine coolant temperature value monitored by the ECU in real time; pMachine-oilRepresenting the engine oil pressure monitored by the ECU in real time; t isThrThe minimum engine coolant temperature threshold value represents a triggering starting command set by the vehicle control unit; pThrThe minimum engine oil pressure threshold value represents a trigger starting instruction set by the whole vehicle controller;
state1 indicates that the engine is judged to be in a cold State when the temperature of the engine coolant is low or the pressure of the engine oil is low; state2 indicates that the engine is warm when the engine coolant temperature is high and the engine oil pressure is high.
The step of adjusting the starting torque of the high-voltage generator is as follows: selecting a torque instruction and a control mode sent by the whole vehicle controller to the high-voltage generator controller as control variables; selecting the real-time rotating speed of the engine, the actual output torque of the high-voltage generator, the maximum allowable discharge power of the high-voltage power battery and the real-time output power of the high-voltage power battery as state variables of a power closed-loop control, the maximum starting torque limitation and a protection mechanism for preventing the engine from galloping.
The engine fuel injection system working state judgment module operates according to the following formula:
in the above formula FrRepresenting engine starting resistance, nEngineWhich is indicative of the real-time rotational speed of the engine,
discrete differential value, T, representing engine speedEngineIndicating the engine output torque, T, calculated by the ECU from the fuel injection quantity and other informationminThe minimum output torque of the engine is indicated,
representing a theoretical internal resistance change rate peak value influenced only by mechanical inertia in the non-ignition state of the engine;
state1 in the above formula indicates that if the engine starting resistance does not drop suddenly or the engine output torque fed back by the ECU is not greater than 0 all the time, the engine is judged not to be activated; state2 shows that if the engine starting resistance is suddenly reduced and the engine output torque fed back by the ECU fluctuates at the minimum engine output torque, the engine is judged to be activated and the ignition is successful.
If n isEngineWhen the rotating speed of the engine is lower than the lowest oil injection rotating speed of an ECU (electronic control unit), the vehicle control unit regulates the starting torque instruction of the high-voltage generator in real time through power closed-loop control and maximum starting torque limitation again, improves the rotating speed of the engine and activates an oil injection ignition system of the engine;if the vehicle control unit still judges that the engine is failed to start in the secondary ignition process of the engine, the vehicle control unit does not send an engine starting instruction any more and outputs an engine starting fault signal.
Under the electric energy compensation mechanism, selecting the real-time rotating speed of an engine, the actual output torque of a high-voltage generator, the real-time output torque of the engine, the maximum allowable charging power of a high-voltage power battery and the real-time output power of the high-voltage power battery as state variables of the electric energy compensation mechanism; the electric energy compensation mechanism operates according to the following formula:
in the above formula, nECOIniRepresenting the initial generating speed of the high-voltage generator in the ECO mode; n isMinECORepresenting the lowest working speed of the high-voltage generator in the ECO mode; n isoffsetRepresenting the fluctuation deviation of the engine speed in the electric energy compensation process; n isVibIndicating an allowable deviation of the engine speed in a steady state; pBMSAllowMaxCRepresenting the maximum allowable charging power of the high-voltage power battery; kp、Ki、KdIs a characteristic parameter;
in the above formula, nEngineCMDIndicating the engine expected rotating speed command sent by the vehicle control unit to the ECU when the engine rotating speed exceeds nMinECO/SPORTAnd after ten message periods continue, the vehicle control unit determines that the rotating speed of the engine has the power generation condition, immediately sends a rotating speed instruction to the ECU and converts the control mode of the high-voltage generator from driving to power generation, and the ECU converts the control mode of the high-voltage generator into power generation according to nEngineCMDThe fuel injection frequency is actively adjusted with the real-time rotating speed of the engine influenced by the power generation load to realize energy output;
in the above formula, TCompDesThe expected generating torque in the electric energy compensation process is shown, the set target of the expected torque is to improve the charging power as much as possible on the premise of ensuring that the battery is not overcharged, and meanwhile, the whole vehicle controller passes through TStartMaxLimiting the target torque;
in the above formula, TComCMDWhole vehicle control in process of representing electric energy compensationThe generator torque command is sent by the controller and is T when the fluctuation size of the engine speed is in a reasonable rangeCompDesIf the fluctuation range of the rotating speed of the engine exceeds a reasonable range, the fact that the power generation torque of the high-voltage generator is large and the real-time oil injection pressure of the engine cannot bear a load is indicated, and at the moment, a PID (proportion integration differentiation) regulator is introduced into the whole vehicle controller to use noffsetFor control target, for TComCMDPerforming feedback regulation to prevent the rotating speed of the engine from further reducing and enable the rotating speed of the engine to reach a stable state;
final State in the above formula indicates the completion State of the whole starting work, which indicates that the construction work of the high oil injection pressure of the engine is completed and the high-voltage generator enters the normal power generation working State.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention relates to a control method for quickly starting an engine of a hybrid electric vehicle, which divides a starting mode into an ECO mode and a SPORT mode according to the driving intention of a driver, and each mode is provided with a corresponding rotating speed interval (an economic rotating speed interval and a peak power rotating speed interval) and a corresponding quick starting method so as to meet different starting requirements. Therefore, the invention can realize the quick start of the engine on the basis of effectively identifying the driving intention of the driver and the real-time working condition of the vehicle and can adapt to the limit power requirement.
2. The invention relates to a control method for quickly starting an engine of a hybrid electric vehicle, which is characterized in that in the starting process, the starting torque of a high-voltage generator is adjusted to enable the rotating speed of the engine to reach an economic rotating speed interval or a peak power rotating speed interval, and the specific step of adjustment comprises a protection mechanism for preventing the engine from galloping through power closed-loop control and maximum starting torque limitation. Therefore, the invention can not only start smoothly, but also reduce the fault.
3. According to the control method for the quick start of the engine of the hybrid electric vehicle, once the rotating speed of the engine reaches an economic rotating speed interval or a peak power rotating speed interval and the engine normally injects oil, the high-voltage generator is switched from an electric mode to a power generation mode, and meanwhile, an electric energy compensation mechanism is triggered, so that the electric energy consumed by the high-voltage generator in the quick start process can be compensated, and the over-discharge fault of a battery can be avoided. Therefore, the invention has high performance-price ratio and less faults.
4. In the control method for the quick start of the engine of the hybrid electric vehicle, corresponding control strategies are designed aiming at the unexpected conditions during the start, such as the engine is a cold machine or a heat machine, the first start fails and the like, so that the effectiveness and the comprehensiveness of the implementation of the method are improved. Therefore, the invention has wider application range and higher effectiveness.
Drawings
Fig. 1 is a hardware architecture diagram of the present invention.
FIG. 2 is a flow chart of the operation of the present invention when it encounters a cold engine or a hot engine during start-up.
FIG. 3 is a schematic diagram of a flow of an engine activation state determination and secondary ignition control module according to the present invention.
FIG. 4 is a schematic diagram of a high voltage generator start power limiting and closed loop control module according to the present invention.
FIG. 5 is a schematic flow chart of a protection mechanism for preventing engine runaway under the SPORT mode.
FIG. 6 is a schematic flow chart of the electric energy compensation-engine fuel injection pressure stabilization control module according to the present invention.
Fig. 7 is a graph showing the variation of the engine speed and the torque of the high voltage generator in the ECO mode in embodiment 1 of the present invention.
Fig. 8 is a graph showing the variation of the current of the high-voltage power battery and the torque of the high-voltage generator in the ECO mode in embodiment 1 of the present invention.
Fig. 9 is a graph showing the variation of the engine speed and the torque of the high voltage generator in the SPORT mode in embodiment 1 of the present invention.
Fig. 10 is a graph showing the variation of the current of the high-voltage power battery and the torque of the high-voltage generator in the SPORT mode in embodiment 1 of the present invention.
In the figure: the system comprises a vehicle control unit 1, a driving motor controller 2, a driving motor system 3, driving wheels 31, a high-voltage power battery 4, a high-voltage generator 5, an engine 6 and a driving mode selection unit 7.
Detailed Description
The present invention will be described in further detail with reference to the following description and embodiments in conjunction with the accompanying drawings.
Referring to fig. 1, the hybrid electric vehicle applied in the invention includes a vehicle control unit 1, a driving motor controller 2, a driving motor system 3, a high-voltage power battery 4, a high-voltage generator 5, an engine 6, a driving mode selection unit 7 and an ECU, wherein the vehicle control unit 1 is in signal connection with the driving motor controller 2, the high-voltage power battery 4, the high-voltage generator 5 and the driving mode selection unit 7, the driving motor controller 2 is electrically connected with the driving motor system 3, the driving motor system 3 is in mechanical transmission connection with a driving wheel 31, the high-voltage power battery 4 is electrically connected with the driving motor controller 2 and the high-voltage generator 5, and the high-voltage generator 5 is in mechanical transmission connection with the engine 6.
The overall control method of the invention comprises the following steps: firstly, a driver selects a driving mode as an ECO mode or a SPORT mode through a driving mode selection unit 7, the engine rotating speeds corresponding to the ECO mode and the SPORT mode are an economic rotating speed interval and a peak power rotating speed interval respectively, then the vehicle control unit 1 sends an engine starting instruction to start, in the starting process, the starting torque of the high-voltage generator 5 is adjusted firstly until the engine rotating speed reaches the economic rotating speed interval or the peak power rotating speed interval, and when the engine 6 injects oil normally, the high-voltage generator 5 is switched from an electric mode to a power generation mode, and simultaneously an electric energy compensation mechanism is triggered, the high-voltage generator 5 increases the power generation torque according to the real-time power demand, the high-voltage power battery 4 under the discharging working condition is adjusted to the charging working condition to compensate the electric energy consumed by the high-voltage generator 5 in the quick starting process, and the battery over-discharge, and the high-voltage generator 5 is started quickly until the high-voltage generator enters a normal power generation working state.
Firstly, referring to fig. 2, according to real-time engine 6 state monitoring information, whether the engine 6 is in a cold machine state is judged, when the vehicle controller 1 sends an engine starting instruction, if the engine 6 is judged to be in the cold machine state, a cold machine starting control strategy is triggered to heat the engine, otherwise, if the engine 6 is in the hot machine state, a hot machine starting control strategy is triggered, and the high-voltage generator 5 and the engine 6 are controlled to work according to the steps of starting, an economic rotation speed interval or a peak power rotation speed interval and normal power generation, and the specific steps are as follows:
(1) and the cold machine and heat machine treatment steps:
when the vehicle control unit 1 sends an engine starting instruction to start, if the engine 6 is judged to be in a cold state, a cold start control strategy is triggered to heat the engine, otherwise, if the engine 6 is in a hot state, the engine continues to be started downwards according to the steps; wherein, the engine 6 is in a cold or hot state according to the following formula:
in the formula TCoolantRepresents the engine 6 coolant temperature value monitored by the ECU in real time; pMachine-oilThe engine oil pressure of the engine 6 monitored by the ECU in real time is represented; t isThrThe minimum engine 6 coolant temperature threshold value is used for triggering a starting instruction and is set by the vehicle control unit 1; pThrThe minimum engine 6 oil pressure threshold value represents the lowest engine 6 engine oil pressure threshold value which is set by the vehicle control unit 1 and triggers a starting instruction;
state1 indicates that the engine 6 is determined to be cold when the temperature of the coolant of the engine 6 is low or the oil pressure of the engine 6 is low; state2 indicates that the engine 6 is in a warm State when the coolant temperature of the engine 6 is high and the oil pressure of the engine 6 is high.
(2) And selecting an economic rotating speed interval or a peak power rotating speed interval:
in the formula nEngineRepresents the actual rotational speed of the engine 6; n isECOIndicating an economically optimized speed interval of the engine 6 selected based on the fuel economy optimization, the high-voltage generator 5 requiring a rapid reverse towing when the driver selects the economy mode to driveThe engine 6 reaches the economy optimization rotating speed interval; n isPowerMaxRepresents a dynamic optimization speed interval of the engine 6 selected based on the maximization of the output power of the engine 6, to which the high-voltage generator 5 needs to rapidly tow the engine 6 when the driver selects the sport mode for running.
Second, referring to fig. 3, during start-up, when the ECU detects that the engine speed exceeds the injection/ignition minimum speed, the electronic fuel injection system starts to operate, i.e. the engine 6 is successfully activated. The engine fuel injection system working state judgment module is mainly used for quickly judging whether the engine 6 is successfully activated:
in the above formula FrIndicating the starting resistance, n, of the engine 6EngineRepresenting the real-time rotational speed of the engine 6,
discrete differential value, T, representing engine speedEngineIndicating the output torque, T, of the engine 6 calculated by the ECU from the fuel injection amount and the likeminWhich represents the minimum output torque of the engine 6,
representing a theoretical internal resistance change rate peak value influenced only by mechanical inertia in the non-ignition state of the engine 6;
the State1 in the above equation indicates that if the starting resistance of the engine 6 does not drop suddenly or the output torque of the engine 6 fed back by the ECU is not greater than 0 all the time, it is determined that the engine 6 is not activated; the State2 indicates that if the engine 6 start resistance drops suddenly and the output torque of the engine 6 fed back by the ECU fluctuates at the minimum output torque of the engine 6, it is determined that the engine 6 is activated and the ignition is successful.
If n isEngineHas already exceededWhen the rotating speed of the engine 6 is in an idle rotating speed, and the vehicle control unit 1 judges that the engine 6 is still in a State1 State, the engine 6 is judged to be failed to start, the vehicle control unit 1 immediately sets a starting torque instruction of the high-voltage generator 5 to zero to reduce the speed of the engine 6 for secondary ignition, and when the rotating speed of the engine is lower than the lowest oil injection rotating speed of an ECU (electronic control Unit), the vehicle control unit 1 regulates the starting torque instruction of the high-voltage generator 5 in real time through power closed-loop control and maximum starting torque limitation again, improves the rotating speed of the engine; if the vehicle control unit 1 still judges that the engine 6 fails to start in the secondary ignition process of the engine 6, the vehicle control unit 1 does not send an engine starting instruction any more and outputs a starting fault signal of the engine 6.
Referring to fig. 4, the specific implementation of the power closed-loop control and the maximum starting torque limit is shown in fig. 4:
as shown in fig. 4, the main functions of the power closed-loop control and the maximum starting torque limitation are to shorten the starting time as much as possible and perform closed-loop control on the power of the high-voltage generator 5 to avoid the over-discharge fault of the high-voltage power battery 4 in the process that the high-voltage generator 5 is used as a motor to activate the engine 6 and increase the rotating speed thereof:
in the above formula, nGCURepresenting the real-time rotational speed of the high voltage generator 5; pGCUECORepresents the peak starting power of the high-voltage generator 5 in the ECO mode; pGCUSPORTRepresents the peak starting power of the high-voltage generator 5 in the SPORT mode; t isStartMaxRepresents a starting torque peak value calculated from the peak starting torque of the high-voltage generator 5 and the maximum allowable starting torque of the engine 6; pBMSRepresents the real-time charge and discharge power of the high-voltage power battery 4; pBMSAllowMaxDCRepresents the maximum allowable discharge power of the high-voltage power battery 4; t isGCUThe real-time torque of the high-voltage generator 5 fed back by the controller of the high-voltage generator 5 is represented; t isStartCMDThe starting torque command value sent by the VCU is represented; a. b is a characteristic constant.
In the above formula, TStartDesShowing the high-voltage generator 5 asThe target output torque during the motor raising engine speed is determined by two control equations, one of which is f (expressed by P)GCUECO/SPORT、TStartMaxThe other control equation is g () whose main function is according to PBMSAnd PBMSAllowMaxDCThe starting power of the high-voltage generator 5 is limited to avoid the over-discharge fault of the high-voltage power battery 4.
In the above formula, TerrorIndicating an error between the actual starting torque of the high-voltage generator 5 and the starting torque command; the VCU adopts a second-order sliding mode controller to build a feedback loop and takes the starting moment error as a control target to TStartcMDAnd carrying out closed-loop adjustment.
Fourthly, referring to fig. 5, a specific embodiment of the protection mechanism for preventing the engine 6 from flying in the SPORT mode is shown in fig. 5:
as shown in fig. 5, since the expected speed range of the engine 6 is high and the starting power of the high voltage generator 5 is high in the SPORT mode, if the starting torque cannot be accurately controlled during the rapid start process, the problem of engine 6 runaway is likely to occur. Therefore, the VCU introduces a protection mechanism against runaway during the ramp up of the engine speed in the SPORT mode as follows:
in the above formula, nSPORTIniRepresents the initial generation rotation speed of the high-voltage generator 5 in the SPORT mode; n isMinSPORTRepresents the lowest operating speed of the high-voltage generator 5 in the SPORT mode; wherein n isSPORTIni＞nMinSPORT。
State1 in the above equation indicates that the engine speed has been raised to nSPORTIn the rotating speed interval, the rotating speed overshoot of the power closed-loop control is below 5%; state2 indicates excessive engine speed and closed-loop power controlThe rotational speed overshoot is already over 5%.
When the engine speed is in State1, the VCU reduces the peak starting power of the high-voltage generator 5 by half, rapidly reducing the starting torque; if the attenuation amplitude of the change rate of the engine speed is small, when the engine speed is rapidly increased from the State1 to the State2, the starting torque is immediately cleared and lasts for ten message periods, so that the engine speed is reduced.
The protection mechanism for preventing the engine 6 from runaway adopts two-stage sliding mode control, the starting torque of the high-voltage generator 5 is reduced in a grading manner by arranging two groups of sliding mode surfaces, and the characteristics of quick response of the sliding mode control are utilized to effectively control the rotating speed overshoot of the engine and avoid the runaway fault. It should be noted that the protection mechanism automatically exits when the control mode of the high voltage generator 5 is switched to the power generation mode.
With reference to fig. 6, a specific embodiment of the electric energy compensation and fuel injection pressure stabilization control of the engine 6 is shown in fig. 6:
as shown in fig. 6, when the engine 6 is successfully activated and the rotation speed has been increased to the desired rotation speed interval, the electric energy compensation mechanism starts to work, and its main function is to compensate the electric energy consumed by the high voltage generator 5 during the fast start and make the fuel injection system of the engine 6 complete the construction work of high fuel injection pressure by applying the appropriate power generation load:
in the above formula, nECOIniRepresents the initial generation rotation speed of the high-voltage generator 5 in the ECO mode; n isMinECORepresents the minimum operating speed of the high-voltage generator 5 in the ECO mode; n isoffsetRepresenting the fluctuation deviation of the engine speed in the electric energy compensation process; n isVibIndicates the allowable deviation of the rotation speed of the engine 6 in the steady state; pBMSAllowMaxCRepresents the maximum allowable charging power of the high-voltage power battery 4; kp、Ki、KdIs a characteristic parameter;
in the above formula, nEngineCMDIndicating the desired speed command of the engine 6 sent by the vehicle control unit 1 to the ECU when the engineThe rotational speed exceeds nMinECO/SPORTAfter ten message periods continue, the vehicle control unit 1 determines that the rotating speed of the engine has the power generation condition, immediately sends a rotating speed instruction to the ECU and converts the control mode of the high-voltage generator 5 from driving to power generation, and the ECU converts the control mode of the high-voltage generator 5 into power generation according to nEngineCMDThe real-time rotating speed of the engine 6 influenced by the power generation load actively adjusts the oil injection frequency to realize energy output;
in the above formula, TCompDesThe expected generating torque in the electric energy compensation process is shown, the expected torque is set to improve the charging power as much as possible on the premise of ensuring that the battery is not overcharged, and meanwhile, the vehicle control unit 1 passes through TStartMaxLimiting the target torque;
in the above formula, TComCMDThe power generation torque instruction sent by the vehicle control unit 1 in the electric energy compensation process is represented, and the instruction is T when the fluctuation size of the engine rotating speed is within a reasonable rangeCompDesFor the sake of accuracy, if the fluctuation range of the engine speed exceeds the reasonable range, it indicates that the power generation torque of the high-voltage generator 5 is large, and the real-time oil injection pressure of the engine 6 cannot bear the load, at this time, the vehicle controller 1 introduces the PID regulator to noffsetFor control target, for TComCMDPerforming feedback regulation to prevent the rotating speed of the engine from further reducing and enable the rotating speed of the engine to reach a stable state;
the Final State in the above formula indicates the completion State of the whole starting operation, which indicates that the construction operation of the high fuel injection pressure of the engine 6 is completed and the high voltage generator 5 enters the normal power generation operation State.
The principle of the invention is illustrated as follows:
in order to improve the adaptability of the engine to the scene of the limit power demand, the invention optimizes the responsiveness of mechanical parts by using electric driving parts to realize the transient response performance of a vehicle power system under the working conditions of extreme power request, large energy consumption of a high-voltage power battery and the like, and belongs to the field of electromechanical coupling control.
In transient control of electric drive, quick transition of electric drive into mechanical drive and the like, strong responsiveness of electric energy is fully exerted to adapt to power request of a driver and real-time state of a vehicle, and a mechanical system and a high-voltage system are required to have larger safety margin, so that real-time fault prediction and effective control on failure faults of overcharge and over-discharge of a high-voltage power battery, engine runaway, overlarge engine load rate and the like are realized. Therefore, it is a necessary condition for realizing quick start to formulate a quick start protection mechanism with high fault tolerance and wide application range.
Furthermore, by formulating a reasonable and efficient energy management strategy and monitoring the real-time state of the engine, the starting time and the working interval of the engine can be flexibly adjusted, the coupling control of engine starting, driver driving intention identification and high-voltage power battery power shortage avoidance is realized, the application scene coverage rate of the ISG starting engine is improved, and the response performance and output power control method of the engine under the condition of extreme power demand is particularly optimized for the responsiveness and the safety.
In the invention, in the action stage of the electric energy compensation mechanism, the rotating speed has certain fluctuation due to the increase of the load of the engine, the ECU stabilizes the rotating speed of the engine by increasing the circulating fuel injection quantity, and the fuel injection system completes the construction work of high fuel injection pressure.
Example 1:
referring to fig. 1-10, the present invention is implemented on a hybrid vehicle equipped with a diesel engine 6 having a peak speed of 3000rpm, according to the above-described method steps. It should be noted that it takes about 6.2 seconds to start the engine to an idle speed of 800rpm by using an automatic start-stop system (20 KW at peak start power) measured in an engine bench test. According to the invention, the startup is successful in the ECO mode and the SPORT mode, the quick startup is realized, and the control effects of a plurality of protection mechanisms are verified as follows (see the following figures 7-10):
during the starting process of the ECO mode, the maximum discharge power of the high-voltage power battery 4 is 28.8KW and is lower than PBMSAllowMaxDC(153.6KW), the power closed-loop control effectively limits the starting power of the high-voltage generator 5; the maximum starting torque of the high-voltage generator 5 does not exceed TstartMax(400N × m), the maximum starting torque limits the effectiveness of the work; the engine speed exceeds n for the first timeECOIni(1550rpm) takes 1.72 seconds, and compared with an automatic start-stop system, the starting time of the engine 6 is greatly reduced; stable engine speedIn the fixed process, the maximum charging power of the high-voltage power battery 4 is 23.2KW and is lower than PBMSAllowMaxC(102.4KW), the electric energy compensation-the oil injection pressure of the engine 6 is stable, and the control module works effectively;
during starting in the SPORT mode, the maximum discharge power of the high-voltage power battery 4 is 65.8KW and is lower than PBMSAllowMaxDC(153.6KW), the power closed-loop control effectively limits the starting power of the high-voltage generator 5; the maximum starting torque of the high-voltage generator 5 does not exceed TstartMax(400N × m), the maximum starting torque limits the effectiveness of the work; the engine speed exceeds n for the first timeSPORTIniThe time consumed by (2500rpm) is 2.42 seconds, and compared with an automatic start-stop system, the starting time of the engine 6 is greatly reduced; the maximum rotating speed and the rotating speed overshoot of the engine 6 are 2652rpm and 6% respectively, although the overshoot exceeds the threshold value of the secondary sliding mode controller by 5%, the overshoot does not have the trend of being continuously improved, and the protection mechanism for preventing the engine 6 from galloping is effective; in the process of stabilizing the rotating speed of the engine, the maximum charging power of the high-voltage power battery 4 is 52.7KW and is lower than PBMSAllowMaxC(102.4KW), the electric energy compensation-the oil injection pressure of the engine 6 is stable, and the control module works effectively.
The above description is only a preferred embodiment of the present invention, and the scope of the present invention is not limited to the above embodiment, but equivalent modifications or changes made by those skilled in the art according to the present disclosure should be included in the scope of the present invention as set forth in the appended claims.
Claims (10)
1. A control method for the quick start of an engine of a hybrid electric vehicle is characterized in that:
the hybrid electric vehicle comprises a vehicle control unit (1), a driving motor controller (2), a driving motor system (3), a high-voltage power battery (4), a high-voltage generator (5), an engine (6), a driving mode selection unit (7) and an ECU, the vehicle control unit (1) is in signal connection with the driving motor controller (2), the high-voltage power battery (4), the high-voltage generator (5) and the driving mode selection unit (7), the driving motor controller (2) is electrically connected with the driving motor system (3), the driving motor system (3) is in mechanical transmission connection with the driving wheel (31), the high-voltage power battery (4) is electrically connected with the driving motor controller (2) and the high-voltage generator (5), the high-voltage generator (5) is in mechanical transmission connection with the engine (6);
the control method comprises the following steps: firstly, a driver selects a driving mode as an ECO mode or a SPORT mode through a driving mode selection unit (7), the engine rotating speeds corresponding to the ECO mode and the SPORT mode are an economic rotating speed interval and a peak power rotating speed interval respectively, then a vehicle controller (1) sends an engine starting instruction to start, during the starting process, the starting torque of a high-voltage generator (5) is adjusted firstly until the engine rotating speed reaches the economic rotating speed interval or the peak power rotating speed interval, and when an engine (6) injects oil normally, the high-voltage generator (5) is switched from an electric mode to a power generation mode, an electric energy compensation mechanism is triggered simultaneously, the high-voltage generator (5) increases the power generation torque according to the real-time power demand, and adjusts a high-voltage power battery (4) under the discharging working condition to the charging working condition to compensate the electric energy consumed by the high-voltage generator (5) during the quick starting process, and the over-discharge fault of the battery is avoided until the high-voltage generator (5) enters a normal power generation working state, and the quick start is finished at the moment.
2. The control method for the quick start of the engine of the hybrid electric vehicle according to claim 1, characterized in that: the drive motor system (3) comprises a distributed electric drive system or a centralized electric drive system.
3. The control method for the quick start of the engine of the hybrid vehicle according to claim 1 or 2, characterized in that: when the driving mode is an ECO mode, adjusting the starting torque of the high-voltage generator (5) through power closed-loop control and maximum starting torque limitation;
when the driving mode is the SPORT mode, the starting torque of the high-voltage generator (5) is adjusted through a power closed-loop control and maximum starting torque limitation and an engine runaway prevention protection mechanism.
4. The control method for the quick start of the engine of the hybrid vehicle according to claim 1 or 2, characterized in that: the normal oil injection of the engine refers to the fact that the engine (6) is successfully activated, whether the engine (6) is successfully activated or not is determined by an engine oil injection system working state judgment module, and state variables of the engine oil injection system working state judgment module comprise the real-time rotating speed of the engine, the actual output torque of the high-voltage generator and the real-time output torque of the engine.
5. The control method for the quick start of the engine of the hybrid vehicle according to claim 1 or 2, characterized in that: under the electric energy compensation mechanism, in the action stage of the electric energy compensation mechanism, the ECU increases the circulating oil injection quantity to stabilize the rotating speed of the engine, and the oil injection system completes the construction work of high oil injection pressure until the high-voltage generator (5) enters a normal power generation working state.
6. The control method for the quick start of the engine of the hybrid vehicle according to claim 1 or 2, characterized in that: when the vehicle control unit (1) sends an engine starting instruction to start, if the engine is judged to be in a cold state, a cold start control strategy is triggered to heat the engine, otherwise, if the engine is in a hot state, the engine continues to be carried out downwards according to the steps; wherein, the engine is in a cold machine state or a hot machine state and is judged according to the following formula:
in the formula TCoolantRepresenting the engine coolant temperature value monitored by the ECU in real time; pMachine-oilRepresenting the engine oil pressure monitored by the ECU in real time; t isThrThe temperature control method comprises the steps that a minimum engine coolant temperature threshold value which is used for triggering a starting instruction and is set by the whole vehicle controller (1) is represented; pThrThe engine oil pressure threshold value represents the lowest engine oil pressure threshold value of a trigger starting instruction set by the whole vehicle controller (1);
state1 indicates that the engine is judged to be in a cold State when the temperature of the engine coolant is low or the pressure of the engine oil is low; state2 indicates that the engine is warm when the engine coolant temperature is high and the engine oil pressure is high.
7. The control method for the quick start of the engine of the hybrid electric vehicle as claimed in claim 3, characterized in that: the adjustment of the starting torque of the high-voltage generator (5) is as follows: selecting a torque instruction and a control mode sent by the vehicle control unit (1) to a controller of the high-voltage generator (5) as control variables; the real-time rotating speed of the engine, the actual output torque of the high-voltage generator (5), the maximum allowable discharge power of the high-voltage power battery (4) and the real-time output power of the high-voltage power battery (4) are selected as state variables of power closed-loop control, maximum starting torque limitation and engine runaway prevention protection mechanism.
8. The control method for the quick start of the engine of the hybrid electric vehicle as claimed in claim 4, wherein: the engine fuel injection system working state judgment module operates according to the following formula:
in the above formula FrRepresenting engine starting resistance, nEngineWhich is indicative of the real-time rotational speed of the engine,
discrete differential value, T, representing engine speedEngineRepresenting the engine output torque, T, calculated by the ECU from the injected fuel quantityminThe minimum output torque of the engine is indicated,
characterizing the theoretical internal resistance of an engine under non-ignited conditions, which is influenced only by mechanical inertiaA peak rate of change; t isGCUThe real-time torque of the high-voltage generator (5) fed back by a controller of the high-voltage generator (5) is represented;
state1 in the above formula indicates that if the engine starting resistance does not drop suddenly or the engine output torque fed back by the ECU is not greater than 0 all the time, the engine is judged not to be activated; state2 shows that if the engine starting resistance is suddenly reduced and the engine output torque fed back by the ECU fluctuates at the minimum engine output torque, the engine is judged to be activated and the ignition is successful.
9. The control method for the quick start of the engine of the hybrid electric vehicle according to claim 8, characterized in that: if n isEngineWhen the idling speed of the engine is exceeded, and the vehicle control unit (1) judges that the engine is still in a State1 State, the engine (6) is judged to be failed to start, the vehicle control unit (1) immediately sets a starting torque instruction of the high-voltage generator (5) to zero to reduce the speed of the engine (6) for secondary ignition, and when the rotating speed of the engine is lower than the lowest oil injection rotating speed of an ECU (electronic control unit), the vehicle control unit (1) regulates the starting torque instruction of the high-voltage generator (5) in real time through power closed-loop control and maximum starting torque limitation, improves the rotating speed of the engine and activates an oil injection ignition system; if the vehicle control unit (1) still judges that the engine (6) fails to start in the secondary ignition process of the engine, the vehicle control unit (1) does not send an engine starting instruction any more and outputs an engine starting fault signal.
10. The control method for the quick start of the engine of the hybrid electric vehicle as claimed in claim 5, wherein: under the electric energy compensation mechanism, selecting the real-time rotating speed of an engine, the actual output torque of a high-voltage generator (5), the real-time output torque of the engine, the maximum allowable charging power of a high-voltage power battery (4) and the real-time output power of the high-voltage power battery (4) as state variables of the electric energy compensation mechanism; the electric energy compensation mechanism operates according to the following formula:
nEngineCMD＝nECO/SPORTIni
noffset＝nECO/SPORTIni-nEngine
in the above formula, nECOIniRepresents the initial generation rotation speed of the high-voltage generator (5) in the ECO mode; n isMinECORepresents the lowest operating speed of the high-voltage generator (5) in the ECO mode; n isoffsetRepresenting the fluctuation deviation of the engine speed in the electric energy compensation process; n isVibIndicating an allowable deviation of the engine speed in a steady state; pBMSAllowMaxCRepresents the maximum allowable charging power of the high-voltage power battery (4); kp、Ki、KdIs a characteristic parameter; n isGCURepresenting the real-time rotational speed of the high-voltage generator (5); pGCUECO/SPORTRepresents the peak starting power of the high-voltage generator (5) in the ECO or SPORT mode; pGCUSPORTRepresents the peak starting power of the high-voltage generator (5) in the SPORT mode; t isStartMaxRepresenting a starting torque peak value calculated by a peak starting torque of the high-voltage generator (5) and a maximum allowable starting torque of the engine (6); pBMSThe real-time charge and discharge power of the high-voltage power battery (4) is represented; n isECO/SPORTIniRepresents the initial generating speed of the high-voltage generator (5) in an ECO or SPORT mode; n isMinECo/SPORTRepresenting the lowest operating speed of the high-voltage generator (5) in an ECO or SPORT mode;
in the above formula, nEngineCMDIndicates the engine expected rotating speed command sent by the vehicle control unit (1) to the ECU when the engine rotating speed exceeds nMinECO/SPORTAfter ten message periods continue, the vehicle control unit (1) determines that the rotating speed of the engine has the power generation condition, immediately sends a rotating speed instruction to the ECU and converts the control mode of the high-voltage generator (5) from driving to power generation, and the ECU generates power according to nEngineCMDThe fuel injection frequency is actively adjusted with the real-time rotating speed of the engine influenced by the power generation load to realize energy output;
in the above formula, TCompDesIndicating power compensationThe expected power generation torque in the process is set to improve the charging power as much as possible on the premise of ensuring that the battery is not overcharged, and meanwhile, the whole vehicle controller (1) passes through TStartMaxLimiting the target torque;
in the above formula, TComCMDThe method is used for representing a power generation torque instruction sent by the vehicle control unit (1) in the electric energy compensation process, and the instruction is T when the fluctuation size of the rotating speed of the engine is within a reasonable rangeCompDesIf the fluctuation range of the rotating speed of the engine exceeds a reasonable range, the fact that the power generation torque of the high-voltage generator (5) is large and the real-time oil injection pressure of the engine cannot bear the load is indicated, and at the moment, the whole vehicle controller (1) introduces a PID (proportion integration differentiation) regulator by noffsetFor control target, for TComCMDPerforming feedback regulation to prevent the rotating speed of the engine from further reducing and enable the rotating speed of the engine to reach a stable state;
FinalState in the above formula represents the completion state of the whole starting work, which indicates that the construction work of the high oil injection pressure of the engine is completed and the high-voltage generator (5) enters the normal power generation working state;
nEnginewhich is indicative of the real-time rotational speed of the engine,
a discrete differential value representing the engine speed.
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| CN110277806B (en) * | 2019-07-15 | 2020-10-30 | 潍柴西港新能源动力有限公司 | Method for realizing stable grid-connected load of unit based on power signal |
| CN111024410B (en) * | 2019-12-30 | 2021-08-03 | 华人运通(江苏)技术有限公司 | Power overrun fault detection method and device for vehicle, vehicle and storage medium |
| CN113715801B (en) * | 2020-05-22 | 2024-05-10 | 广州汽车集团股份有限公司 | Controller of vehicle with hybrid power coupling system, control method and vehicle |
| CN113715804B (en) * | 2020-05-22 | 2024-04-12 | 广汽埃安新能源汽车有限公司 | Controller of vehicle with hybrid power coupling system, control method and vehicle |
| CN111852670A (en) * | 2020-07-22 | 2020-10-30 | 上海元城汽车技术有限公司 | Vehicle starting method, equipment and medium |
| CN112895902B (en) * | 2021-02-07 | 2022-08-19 | 中国第一汽车股份有限公司 | Power distribution system, control method of power distribution system and new energy automobile |
| CN112977391B (en) * | 2021-03-05 | 2022-04-12 | 奇瑞新能源汽车股份有限公司 | Control method of range extender system |
| CN113715823B (en) * | 2021-09-26 | 2024-04-26 | 一汽解放汽车有限公司 | Engine start control method for light-weight commercial vehicle |
| CN115370499B (en) * | 2022-09-29 | 2023-09-01 | 重庆长安汽车股份有限公司 | Method and system for controlling starting of engine of hybrid electric vehicle, electronic equipment and vehicle |
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