Low-pressure EGR system VVT phase control method and device

Abstract

The low-pressure EGR system VVT phase control method and device provided by the embodiment of the present invention are applied to the field of information technology, and can obtain the current phase of VVT; calculate the difference between the current phase and the preset target phase to obtain the current phase difference information; calculate the corresponding target duty cycle according to the current phase difference information through a preset fuzzy control algorithm; drive the OCV action according to the target duty cycle to achieve phase following. Thus, by obtaining the current phase of VVT and calculating the current phase difference information according to the current phase, the corresponding target duty cycle is calculated through the phase difference information through the preset fuzzy control algorithm, and the duty cycle is used to drive the OCV action to achieve phase following, thereby improving the control accuracy of the VVT ​​system.

Description

Technical Field

[0001] The present invention relates to the field of information technology, and in particular to a VVT phase control method and device for a low-pressure EGR system. Background Art

[0002] The low-pressure EGR (Exhaust Gas Re-circulation) system, by returning part of the exhaust gas discharged by the engine to the intake manifold and re-entering the cylinder together with the fresh mixture, can reduce the maximum combustion temperature of the mixture in the cylinder, thereby reducing the amount of NOx generated. It has now become a research hotspot.

[0003] However, although the current VVT (Variable Valve Timing) system has made great progress, in the low-pressure EGR system, the exhaust gas flow and fresh air are mixed into the cylinder, and the exhaust gas flow has serious hysteresis characteristics, which has a great impact on the intake system, thereby affecting the control accuracy of VVT. Summary of the invention

[0004] The purpose of the embodiment of the present invention is to provide a low-pressure EGR system VVT phase control method and device to improve the control accuracy of VVT. The specific technical solution is as follows:

[0005] In a first aspect of an embodiment of the present application, a low-pressure EGR system VVT phase control method is provided, comprising:

[0006] Get the current phase of VVT;

[0007] Calculating the difference between the current phase and the preset target phase to obtain current phase difference information;

[0008] According to the current phase difference information, a corresponding target duty cycle is calculated by a preset fuzzy control algorithm;

[0009] The OCV action is driven according to the target duty cycle to achieve phase following.

[0010] In a possible implementation manner, the current phase difference information includes the current phase difference and the current phase difference change rate, and the calculating the difference between the current phase and the preset target phase to obtain the current phase difference information includes:

[0011] Calculating the difference between the current phase and the preset target phase to obtain the current phase difference;

[0012] According to the current phase difference, a current phase difference change rate is calculated.

[0013] In a possible implementation manner, calculating the current phase difference change rate according to the current phase difference includes:

[0014] Calculate the target difference between the current phase difference and the sum of the phase difference of the previous cycle and the phase difference change rate of the previous cycle;

[0015] The rate of change of the target difference over time is calculated to obtain the current rate of change of the phase difference.

[0016] In a possible implementation manner, calculating the current phase difference change rate according to the current phase difference includes:

[0017] According to the current phase difference, by the preset formula:

[0018] ,

[0019] Calculate the current phase difference change rate, where the is the current phase difference, Current phase difference change rate, is the time constant for the rate of change calculation, is the time interval of the sampling period, for The value of the previous sampling period, for The value of the previous sampling period.

[0020] In a possible implementation manner, the calculating the corresponding target duty cycle by using a preset fuzzy control algorithm according to the current phase difference information includes:

[0021] Performing fuzzy processing on the current phase difference and the current phase difference change rate to obtain a first fuzzy amount and a second fuzzy amount;

[0022] According to the first fuzzy quantity and the second fuzzy quantity, a fuzzy control quantity is calculated by using a preset fuzzy control rule;

[0023] The fuzzy control amount is defuzzified to obtain the target duty cycle.

[0024] In a possible implementation manner, before calculating the fuzzy control amount according to the first fuzzy amount and the second fuzzy amount by using a preset fuzzy control rule, the method further includes:

[0025] Creating a fuzzy set, wherein the fuzzy set includes fuzzy control quantities corresponding to fuzzy quantities of multiple phases;

[0026] The step of calculating the fuzzy control amount according to the first fuzzy amount and the second fuzzy amount by using a preset fuzzy control rule comprises:

[0027] The fuzzy control amount corresponding to the first fuzzy amount and the second fuzzy amount is searched in the fuzzy set.

[0028] A second aspect of an embodiment of the present application provides a low-pressure EGR system VVT phase control device, comprising:

[0029] Phase acquisition module, used to obtain the current phase of VVT;

[0030] A phase difference calculation module, used to calculate the difference between the current phase and the preset target phase to obtain current phase difference information;

[0031] A duty cycle calculation module, used to calculate the corresponding target duty cycle through a preset fuzzy control algorithm according to the current phase difference information;

[0032] The phase following module is used to drive the OCV action according to the target duty cycle to achieve phase following.

[0033] In a possible implementation manner, the current phase difference information includes the current phase difference and the current phase difference change rate, and the phase difference calculation module includes:

[0034] The phase difference calculation submodule is used to calculate the difference between the current phase and the preset target phase to obtain the current phase difference;

[0035] The change rate calculation submodule is used to calculate the current phase difference change rate according to the current phase difference.

[0036] In a possible implementation manner, the change rate calculation submodule includes:

[0037] A difference calculation unit, used to calculate a target difference between a current phase difference and the sum of the phase difference of the previous cycle and the phase difference change rate of the previous cycle;

[0038] The change rate calculation unit is used to calculate the change rate of the target difference over time to obtain the current phase difference change rate.

[0039] In a possible implementation manner, the change rate calculation submodule is specifically configured to calculate, according to the current phase difference, a preset formula:

[0040] ,

[0041] Calculate the current phase difference change rate, where the is the current phase difference, Current phase difference change rate, is the time constant for the rate of change calculation, is the time interval of the sampling period, for The value of the previous sampling period, for The value of the previous sampling period.

[0042] In a possible implementation manner, the duty cycle calculation module includes:

[0043] A fuzzy processing submodule, used for performing fuzzy processing on the current phase difference and the current phase difference change rate to obtain a first fuzzy amount and a second fuzzy amount;

[0044] A control amount calculation submodule, used for calculating a fuzzy control amount according to the first fuzzy amount and the second fuzzy amount by using a preset fuzzy control rule;

[0045] The defuzzification submodule is used to perform defuzzification on the fuzzy control amount to obtain the target duty cycle.

[0046] In a possible implementation, the device further includes:

[0047] A fuzzy set creation module, used for creating a fuzzy set, wherein the fuzzy set includes fuzzy control quantities corresponding to fuzzy quantities of multiple phases;

[0048] The control amount calculation submodule is specifically used to find the fuzzy control amount corresponding to the first fuzzy amount and the second fuzzy amount in the fuzzy set.

[0049] Another aspect of an embodiment of the present application provides an electronic device, including a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other via the communication bus;

[0050] Memory, used to store computer programs;

[0051] The processor is used to implement any of the above-mentioned low-pressure EGR system VVT phase control methods when executing the program stored in the memory.

[0052] In another aspect of an embodiment of the present application, a computer-readable storage medium is provided, wherein a computer program is stored in the computer-readable storage medium, and when the computer program is executed by a processor, any of the above-mentioned low-pressure EGR system VVT phase control methods is implemented.

[0053] An embodiment of the present invention further provides a computer program product comprising instructions, which, when executed on a computer, enables the computer to execute any of the above-mentioned low-pressure EGR system VVT phase control methods.

[0054] Beneficial effects of the embodiments of the present invention:

[0055] The embodiment of the present invention provides a VVT phase control method and device for a low-pressure EGR system, which can obtain the current phase of VVT; calculate the difference between the current phase and the preset target phase to obtain the current phase difference information; calculate the corresponding target duty cycle according to the current phase difference information through a preset fuzzy control algorithm; drive the OCV action according to the target duty cycle to achieve phase following. Thus, by obtaining the current phase of VVT and calculating the current phase difference information according to the current phase, the corresponding target duty cycle is calculated through the phase difference information through the preset fuzzy control algorithm, and the duty cycle is used to drive the OCV action to achieve phase following, thereby improving the control accuracy of the VVT ​​system.

[0056] Of course, it is not necessary to achieve all of the advantages described above at the same time to implement any product or method of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention, and for ordinary technicians in this field, other embodiments can also be obtained based on these drawings.

[0058] Figure 1 A schematic flow chart of a VVT phase control method for a low-pressure EGR system provided in an embodiment of the present application;

[0059] Figure 2 An example diagram of a low-pressure EGR system VVT phase control method provided in an embodiment of the present application;

[0060] Figure 3 A schematic diagram of a flow chart for calculating the current phase difference change rate provided in an embodiment of the present application;

[0061] Figure 4 An example diagram of a membership function provided in an embodiment of the present application;

[0062] Figure 5 Another example diagram of the membership function provided in the embodiment of the present application;

[0063] Figure 6 A diagram showing another example of a membership function provided in an embodiment of the present application;

[0064] Figure 7 A schematic diagram showing a corresponding relationship between the fuzzy control quantity output and the phase difference and the phase difference change rate provided in an embodiment of the present application;

[0065] Figure 8 A schematic diagram of a structure of a VVT phase control device for a low-pressure EGR system provided in an embodiment of the present application;

[0066] Fig. 9 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0067] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field based on this application belong to the scope of protection of the present invention.

[0068] In a first aspect of the embodiment of the present application, a low-pressure EGR system VVT phase control method is provided. Figure 1 ,include:

[0069] Step S11, obtaining the current phase of VVT.

[0070] The VVT ​​in the embodiment of the present application is a VVT in a low-pressure EGR system. Specifically, in the low-pressure EGR system, the camshaft phase control system is mainly composed of a cam phaser, a camshaft position sensor, a water temperature sensor, a camshaft timing hydraulic control valve (Oil Control Valve, OCV), a crankshaft position sensor and an electronic control unit ECU. The cam phaser is mainly composed of a rotor blade, a stator and a return spring. The rotor blade is fixed on the intake camshaft, and the stator is integrated with the driven timing sprocket. When the oil in the system oil circuit is controlled by the timing hydraulic control valve to generate pressure, the oil squeezes the rotor and drives the intake camshaft to rotate, so that the camshaft phase is advanced, delayed or maintained, thereby changing the opening and closing time of the intake valve. During the movement of the rotor, the phaser forms two hydraulic chambers, the valve timing advance chamber and the valve timing delay chamber. In addition, in the embodiment of the present application, an oil pressure sensor and (or) a variable displacement oil pump can be added, wherein the oil pressure sensor reads the oil pressure of the main oil channel of the oil, and the variable displacement oil pump can adjust the oil pressure.

[0071] The method of the embodiment of the present application is applied to an intelligent terminal, which may be a control terminal in an EGR system.

[0072] Step S12, calculating the difference between the current phase and the preset target phase to obtain current phase difference information.

[0073] In one possible implementation, the current phase difference information includes the current phase difference and the current phase difference change rate. The difference between the current phase and the preset target phase is calculated to obtain the current phase difference information, including: calculating the difference between the current phase and the preset target phase to obtain the current phase difference; and calculating the current phase difference change rate based on the current phase difference.

[0074] Step S13, calculating the corresponding target duty cycle through a preset fuzzy control algorithm according to the current phase difference information.

[0075] In a possible implementation, based on the current phase difference information, a corresponding target duty cycle is calculated by a preset fuzzy control algorithm, including: fuzzifying the current phase difference and the current phase difference change rate to obtain a first fuzzy quantity and a second fuzzy quantity; based on the first fuzzy quantity and the second fuzzy quantity, a fuzzy control quantity is calculated by a preset fuzzy control rule; and defuzzifying the fuzzy control quantity to obtain the target duty cycle.

[0076] Step S14, driving the OCV according to the target duty cycle to achieve phase following.

[0077] In the embodiment of the present application, the VVT ​​phase control is to control the actual phase according to the VVT ​​target phase so that the actual phase follows the target phase.

[0078] See also Figure 2 The present invention uses a fuzzy control method to control the dynamic change process of the phase according to the target phase and the actual phase difference, and the phase difference change rate, and outputs a control duty ratio (the larger the duty ratio, the faster the control response) to drive the OCV action to achieve phase following. It is applicable to the control method of intake VVT ​​and exhaust VVT.

[0079] It can be seen that through the method of the embodiment of the present application, the current phase of the VVT ​​can be obtained, and the current phase difference information can be calculated based on the current phase, so that the corresponding target duty cycle can be calculated through the phase difference information through the preset fuzzy control algorithm, and the duty cycle can be used to drive the OCV action to achieve phase following, thereby improving the control accuracy of the VVT ​​system.

[0080] In one possible implementation, see Figure 3 , according to the current phase difference, calculate the current phase difference change rate, including:

[0081] Step S31, calculating the target difference between the current phase difference, and the sum of the phase difference of the previous cycle and the phase difference change rate of the previous cycle;

[0082] Step S32, calculating the rate of change of the target difference over time to obtain the current rate of change of the phase difference.

[0083] In a possible implementation manner, calculating the current phase difference change rate according to the current phase difference includes:

[0084] According to the current phase difference, through the preset formula:

[0085] ,

[0086] Calculate the current phase difference change rate, where: is the current phase difference, Current phase difference change rate, is the time constant for the rate of change calculation, is the time interval of the sampling period, for The value of the previous sampling period, for The value of the previous sampling period.

[0087] Specifically, the phase difference and Determined as the corrected phase difference change rate The fuzzy control method is used to control the dynamic change process of the phase and the output control duty cycle.

[0088] for The value of the previous sampling period (especially the first sampling value Take 0), for The value of the previous sampling period (especially the first sampling value Take 0), The time constant for the rate of change calculation (20ms in this example).

[0089] above The reason for using it as a control parameter is that it is equivalent to adopting a "feedforward" function in order to better improve the control response accuracy.

[0090] In actual use, the reasons for setting specific parameters are: mainly when the EGR system control fluctuates greatly, and the VVT ​​phase control itself fluctuates greatly, or even when the oil pressure changes greatly, the dynamic response accuracy of VVT can be provided by adjusting the closed-loop control parameters. Among them, EGR exhaust gas and fresh air are controlled together by VVT to ensure that the entire mixture enters the cylinder. Due to the hysteresis and nonlinearity of the EGR system, its phase fluctuation will aggravate the dynamic response accuracy of VVT; if the actual intake pressure fluctuates violently, it will aggravate the dynamic response accuracy of VVT; the oil is the medium for VVT to execute the drive, and its pressure change will affect the accuracy of VVT in the closed-loop dynamic control process, which may cause the control to be too aggressive or even integral saturation in the closed-loop control process. The phase difference and the phase difference change rate are used as direct control parameters for phase control, which are realized through fuzzy control algorithms.

[0091] In order to illustrate the above embodiment, a specific example is described below:

[0092] First, determine the parameters The design of this parameter is that due to the hysteresis and nonlinearity of the EGR system, its phase fluctuation will aggravate the dynamic response accuracy of VVT. Based on this consideration, the optimization design is carried out. The method for determining this parameter is that the actual intake pressure fluctuation is small (±2kPa in this example); the oil pressure fluctuation is small, 5kPa in this example; the absolute value of the difference between the target VVT and the actual VVT phase is within the preset phi1~phi2 range (phi2 in this example takes a phase angle of 5°), that is, the absolute value of the difference between the target VVT and the actual VVT phase fluctuates within the range of phi1~phi2, and the parameters are adjusted under different engine speeds, different target phases, and different phase deviations. To ensure the target VVT angle and actual VVT phase The absolute value of the difference is within phi2. Based on this, the specific calibration parameters of this example are shown in Table 1 below;

[0093] Table 1. Comparison table of a phase pressure difference and target phase

[0094]

[0095] Next, determine the parameters The design of this parameter is due to the fact that the actual intake pressure fluctuates violently, and the closed-loop control parameters are appropriately adjusted to realize the phase fluctuation. Based on this consideration, the optimization design is carried out. The parameter determination method is the ratio of the phase pressure difference to the target phase. Small (±0.02 in this example); small oil pressure fluctuation, 5kPa in this example; the absolute value of the difference between the target VVT and the actual VVT phase is within the preset phi1~phi2 range (phi2 in this example takes a phase angle of 5°), that is, the absolute value of the difference between the target VVT and the actual VVT phase fluctuates within the range of phi1~phi2 at different engine speeds and different intake pressure change rates By adjusting the parameters To ensure the target VVT angle and actual VVT phase The absolute value of the difference is within phi2.

[0096] Table 2. Data table of actual intake pressure change rate

[0097]

[0098] Again, determine the parameters The design of this parameter is that the oil is used as the medium for VVT to execute the drive. The change of its pressure will affect the accuracy of VVT in the closed-loop dynamic control process, which may cause the control to be too aggressive or even integral saturation in the closed-loop control process. Based on this, the target phase is dynamically adjusted. The parameter is determined by the ratio of the phase pressure difference to the target phase. The absolute value of the phase difference between the target VVT and the actual VVT is within the preset range of phi1~phi2 (in this example, phi2 takes a phase angle of 5°), that is, the absolute value of the phase difference between the target VVT and the actual VVT fluctuates within the range of phi1~phi2. Under different phase differences between the target VVT and the actual VVT and different oil pressure change rates, the parameters are adjusted. To ensure the target VVT angle and actual VVT phase The absolute value of the difference is within phi1.

[0099] Table 3. Data table of oil pressure change rate

[0100]

[0101] In a possible implementation, before calculating the fuzzy control quantity according to the first fuzzy quantity and the second fuzzy quantity by preset fuzzy control rules, the method further includes: creating a fuzzy set, wherein the fuzzy set includes fuzzy control quantities corresponding to fuzzy quantities of multiple phases; calculating the fuzzy control quantity according to the first fuzzy quantity and the second fuzzy quantity by preset fuzzy control rules, including: searching the fuzzy set for the fuzzy control quantity corresponding to the first fuzzy quantity and the second fuzzy quantity.

[0102] In the embodiment of the present application, it is necessary to establish a membership function to realize fuzzy control. There are certain principles for establishing a membership function. Since the fuzzy control process is not sensitive to the shape of the membership function of the language variable value, but is sensitive to the range of the membership degree, in this embodiment, a triangular or trapezoidal membership function can be used, which is conducive to calculating the membership degree.

[0103] In the specific implementation process, it is necessary to build a fuzzy controller whose input is: phase difference And the phase difference change rate The output of the fuzzy controller is: OCV solenoid valve control duty cycle According to the phase difference , Phase difference change rate And the preset fuzzy control rules determine the fuzzy OCV solenoid valve control duty cycle The process may include: respectively dividing the phase difference , and the phase difference change rate Perform fuzzification processing to obtain a first fuzzy quantity and a second fuzzy quantity; obtain a fuzzy control quantity according to the first fuzzy quantity, the second fuzzy quantity and a preset fuzzy control rule; perform defuzzification processing on the fuzzy control quantity to obtain a fuzzy OCV solenoid valve control duty ratio .

[0104] Before executing the above steps, the preset fuzzy control rules can be preliminarily organized into a fuzzy control rule table and stored. The construction process of the fuzzy control rule table is described below with a specific example. Of course, in the specific implementation process, the number of fuzzy sets divided and the setting range of the domain can be set according to actual needs and multiple experiments.

[0105] See also Figure 4 , the phase difference Divided into 5 fuzzy sets, the domain can be set to [-4, 4], and in the phase difference When the phase difference is lower than -3, the module control rule belongs to negative large (NB). When it is higher than 3, the module control rule belongs to positive (PB). It should be noted that the reason why the domain is selected as [-4, 4] is to indicate the phase difference The control rules are adjusted only when the phase difference is between -4° and 4°, thereby improving the control accuracy (phase difference The use of "big steps" improves the control response time and phase difference Small adopts "small steps" to control response accuracy), and its fuzzy set membership function is as follows Figure 4 As shown. Among them, negative big (NB) indicates that the actual phase is about 3° larger than the target phase; negative small (NS) indicates that the actual phase is about 1° larger than the target phase; zero (ZO) indicates that the actual phase is close to the target phase; positive small (PS) indicates that the actual phase is about 1° smaller than the target phase; positive big (PB) indicates that the actual phase is about 3° smaller than the target phase.

[0106] See also Figure 5 , the phase difference change rate It is also divided into 5 fuzzy sets, and the domain can be set to [-50, 50]. When the phase difference change rate is lower than -35° / s, the module control rule belongs to negative large (NB). When the phase difference is higher than 40° / s, the module control rule belongs to positive (PB). The reason why the domain is selected as [-50, 50] is to indicate the rate of change of the phase difference. Between -50° / s and 50° / s (Phase difference change rate The control rules are adjusted only when the phase difference is not large, so as to improve the control accuracy (phase difference change rate The "big step" is adopted to improve the control response time and the phase difference change rate. Small adopts "small steps" to control the response accuracy). Among them, negative big (NB) indicates the phase difference change rate It is about -35° / s; negative small (NS) indicates the phase difference change rate It is about -8° / s; zero (ZO) indicates the rate of change of phase difference About 0° / s; positive small (PS) indicates the rate of change of phase difference About 10° / s; positive (PB) indicates the rate of change of phase difference It is about 40° / s.

[0107] The asymmetric membership function is designed in this way because it is found based on experimental test research that the faster the phase difference change rate decreases, the faster the phase changes. The following design is more reasonable.

[0108] The output of the fuzzy controller is the fuzzy control quantity. The domain can be set to [0, 70], which means that the final fuzzy control quantity is limited to the range of 0 to 70. Its membership function can be as follows: Figure 6 When the target phase is close to the actual phase, the duty cycle is finally controlled to be stable near ZO.

[0109] In one example, the standard for designing fuzzy control rules is: "The more the target phase is higher than the actual phase and the faster the phase rises, the greater the increase in the fuzzy control amount"; "The target phase is close to the actual phase and the phase changes little, and the fuzzy control amount remains basically unchanged"; "The more the target phase is lower than the actual phase and the faster the phase decreases, the greater the decrease in the fuzzy control amount".

[0110] To illustrate the solution of the embodiment of the present application, 25 fuzzy control rules are listed below:

[0111] Rule 1: If the target phase is much smaller than the actual phase and the phase drops rapidly, then the fuzzy control amount is greatly reduced;

[0112] Rule 2: If the target phase is much smaller than the actual phase and the phase decreases slowly, then greatly reduce the fuzzy control amount;

[0113] Rule 3: If the target phase is much smaller than the actual phase and the phase is basically unchanged, then greatly reduce the fuzzy control amount;

[0114] Rule 4: if the target phase is much lower than the actual phase and the phase rises slowly, then moderately reduce the fuzzy control amount;

[0115] Rule 5: if the target phase is much lower than the actual phase and the phase rises rapidly, then slightly reduce the fuzzy control amount;

[0116] Rule 6: If the target phase is slightly lower than the actual phase and the phase drops rapidly, then greatly reduce the fuzzy control amount;

[0117] Rule 7: if the target phase is slightly lower than the actual phase and the phase decreases slowly, then moderately reduce the fuzzy control amount;

[0118] Rule 8: If the target phase is slightly lower than the actual phase and the phase is basically unchanged, then slightly reduce the fuzzy control amount;

[0119] Rule 9: If the target phase is slightly lower than the actual phase and the phase rises slowly, then the fuzzy control amount is basically maintained;

[0120] Rule 10: If the target phase is slightly lower than the actual phase and the phase rises quickly, then slightly increase the fuzzy control amount;

[0121] Rule 11: If the target phase is basically equal to the actual phase and the phase decreases rapidly, then the fuzzy control amount is greatly reduced;

[0122] Rule 12: If the target phase is basically equal to the actual phase and the phase decreases slowly, then slightly reduce the fuzzy control amount;

[0123] Rule 13: If the target phase is basically equal to the actual phase and the phase is basically unchanged, then the fuzzy control amount is basically maintained;

[0124] Rule 14: If the target phase is basically equal to the actual phase and the phase rises slowly, then slightly increase the fuzzy control amount;

[0125] Rule 15: If the target phase is basically equal to the actual phase and the phase rises quickly, then increase the fuzzy control amount moderately;

[0126] Rule 16: If the target phase is slightly higher than the actual phase and the phase drops rapidly, then moderately reduce the fuzzy control amount;

[0127] Rule 17: If the target phase is slightly higher than the actual phase and the phase decreases slowly, then the fuzzy control amount is basically maintained;

[0128] Rule 18: If the target phase is slightly higher than the actual phase and the phase is basically unchanged, then slightly increase the fuzzy control amount;

[0129] Rule 19: If the target phase is slightly higher than the actual phase and the phase rises slowly, then increase the fuzzy control amount moderately;

[0130] Rule 20: If the target phase is slightly higher than the actual phase and the phase rises quickly, then increase the fuzzy control amount moderately;

[0131] Rule 21: If the target phase is much higher than the actual phase and the phase drops rapidly, then slightly reduce the fuzzy control amount;

[0132] Rule 22: If the target phase is much higher than the actual phase and the phase decreases slowly, then slightly increase the fuzzy control amount;

[0133] Rule 23: If the target phase is much higher than the actual phase and the phase is basically unchanged, then increase the fuzzy control amount moderately;

[0134] Rule 24: If the target phase is much higher than the actual phase and the phase rises slowly, then increase the fuzzy control amount moderately;

[0135] Rule 25: if the target phase is much higher than the actual phase and the phase rises rapidly, then greatly increase the fuzzy control amount.

[0136] At this time, the above fuzzy control rules can be organized into a fuzzy control rule table as shown in the following table. In the fuzzy control rules of this application, the output of the fuzzy control quantity is in a corresponding relationship with the phase difference and the phase difference change rate. Figure 7 As shown. After the currently detected phase difference and the phase difference change rate are fuzzified to the corresponding fuzzy sets respectively, and the first fuzzy quantity and the second fuzzy quantity are determined, the fuzzy control quantity can be obtained according to the above fuzzy control rule table. Furthermore, it is necessary to defuzzify the obtained fuzzy control quantity to obtain an accurate control quantity. In a possible implementation, there are many defuzzification methods, for example, the most commonly used ones are the maximum membership method, the centroid method and the weighted average method.

[0137] In an example, the centroid method can be used for defuzzification, and the fuzzy control output u corresponding to the phase difference and the phase difference change rate can be obtained using the following formula. The fuzzy control output u is the fuzzy control correction coefficient .

[0138] ,

[0139] in, for The membership degree of It should be noted that the centroid method is an existing defuzzification method, and the specific calculation method can refer to the relevant description in the prior art, which will not be described in detail here.

[0140] Since the VVT ​​system structure of the engine design is complex and the control is carried out by sampling hydraulic oil, it has the characteristics of nonlinearity, time-varying and large delay. It is difficult to control the phase by conventional PID control. The embodiment of this specification adopts a fuzzy control strategy to achieve closed-loop control, which can imitate human control to a certain extent. It does not require an accurate control object model and can identify and model the knowledge and thinking, learning and reasoning, association and decision-making process of relevant experts by computers, and control and realize self-tuning, thereby further improving the control accuracy of the phase.

[0141] In the above fuzzy control process, since the VVT ​​phase is a parameter in the fuzzy control strategy, it has a certain flexibility. In actual application, the VVT ​​phase can be set to a variable value to adapt to the phase requirements of the internal combustion engine under different working conditions.

[0142] The knowledge and thinking, learning and reasoning, association and decision-making processes of relevant experts can be identified and modeled by computers, and controlled to achieve self-tuning. This can further upgrade the intelligent control of the phase and compensate for the deviation between the actual phase and the target phase, which is conducive to achieving accurate control of the phase. It can control the OCV solenoid valve based on the actual phase under various working conditions, and achieve the technical effect of the actual phase quickly and stably following the target phase.

[0143] In a second aspect of the embodiment of the present application, a low-pressure EGR system VVT phase control device is provided. Figure 8 ,include:

[0144] Phase acquisition module 801, used to obtain the current phase of VVT;

[0145] The phase difference calculation module 802 is used to calculate the difference between the current phase and the preset target phase to obtain the current phase difference information;

[0146] The duty cycle calculation module 803 is used to calculate the corresponding target duty cycle through a preset fuzzy control algorithm according to the current phase difference information;

[0147] The phase following module 804 is used to drive the OCV action according to the target duty cycle to achieve phase following.

[0148] In a possible implementation manner, the current phase difference information includes the current phase difference and the current phase difference change rate, and the phase difference calculation module includes:

[0149] The phase difference calculation submodule is used to calculate the difference between the current phase and the preset target phase to obtain the current phase difference;

[0150] The change rate calculation submodule is used to calculate the current phase difference change rate based on the current phase difference.

[0151] In a possible implementation, the change rate calculation submodule includes:

[0152] A difference calculation unit, used to calculate a target difference between a current phase difference and the sum of the phase difference of the previous cycle and the phase difference change rate of the previous cycle;

[0153] The change rate calculation unit is used to calculate the change rate of the target difference over time to obtain the current phase difference change rate.

[0154] In a possible implementation manner, the change rate calculation submodule is specifically configured to calculate the current phase difference using a preset formula:

[0155] ,

[0156] Calculate the current phase difference change rate, where: is the current phase difference, Current phase difference change rate, is the time constant for the rate of change calculation, is the time interval of the sampling period, for The value of the previous sampling period, for The value of the previous sampling period.

[0157] In a possible implementation, the duty cycle calculation module includes:

[0158] A fuzzy processing submodule, used for performing fuzzy processing on the current phase difference and the current phase difference change rate to obtain a first fuzzy amount and a second fuzzy amount;

[0159] A control quantity calculation submodule, used for calculating the fuzzy control quantity according to the first fuzzy quantity and the second fuzzy quantity by using a preset fuzzy control rule;

[0160] The defuzzification submodule is used to perform defuzzification on the fuzzy control quantity to obtain the target duty cycle.

[0161] In a possible implementation, the device further includes:

[0162] A fuzzy set creation module, used for creating a fuzzy set, wherein the fuzzy set includes fuzzy control quantities corresponding to fuzzy quantities of multiple phases;

[0163] The control quantity calculation submodule is specifically used to find the fuzzy control quantity corresponding to the first fuzzy quantity and the second fuzzy quantity in the fuzzy set.

[0164] It can be seen that through the device of the embodiment of the present application, the current phase of the VVT ​​can be obtained, and the current phase difference information can be calculated based on the current phase, so that the corresponding target duty cycle can be calculated through the phase difference information through the preset fuzzy control algorithm, and the duty cycle can be used to drive the OCV action to achieve phase following, thereby improving the control accuracy of the VVT ​​system.

[0165] The embodiment of the present invention further provides an electronic device, such as Fig. 9 As shown, it includes a processor 901, a communication interface 902, a memory 903 and a communication bus 904, wherein the processor 901, the communication interface 902, and the memory 903 communicate with each other through the communication bus 904.

[0166] Memory 903, used for storing computer programs;

[0167] The processor 901 is used to implement the following steps when executing the program stored in the memory xx3:

[0168] Get the current phase of VVT;

[0169] Calculate the difference between the current phase and the preset target phase to obtain the current phase difference information;

[0170] According to the current phase difference information, the corresponding target duty cycle is calculated by a preset fuzzy control algorithm;

[0171] Drive OCV action according to the target duty cycle to achieve phase following.

[0172] The communication bus mentioned in the above electronic device can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The communication bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, only one thick line is used in the figure, but it does not mean that there is only one bus or one type of bus.

[0173] The communication interface is used for communication between the above electronic device and other devices.

[0174] The memory may include a random access memory (RAM) or a non-volatile memory (NVM), such as at least one disk memory. Optionally, the memory may also be at least one storage device located away from the aforementioned processor.

[0175] The above-mentioned processor can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0176] In another embodiment provided by the present invention, a computer-readable storage medium is also provided, in which a computer program is stored. When the computer program is executed by a processor, the steps of any of the above-mentioned low-pressure EGR system VVT phase control methods are implemented.

[0177] In another embodiment provided by the present invention, a computer program product including instructions is also provided, which, when executed on a computer, enables the computer to execute any of the low-pressure EGR system VVT phase control methods in the above embodiments.

[0178] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented by software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present invention is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from one website site, computer, server or data center to another website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive Solid State Disk (SSD)), etc.

[0179] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0180] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device, electronic device, storage medium, or computer program product embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0181] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A low-pressure EGR system VVT phase control method, characterized in that: include: Get the current phase of VVT; Calculating the difference between the current phase and the preset target phase to obtain current phase difference information; According to the current phase difference information, a corresponding target duty cycle is calculated by a preset fuzzy control algorithm; Driving the OCV action according to the target duty cycle to achieve phase following; The current phase difference information includes the current phase difference and the current phase difference change rate, and the difference between the current phase and the preset target phase is calculated to obtain the current phase difference information, including: Calculating the difference between the current phase and the preset target phase to obtain the current phase difference; The step of calculating the current phase difference change rate according to the current phase difference comprises: According to the current phase difference, by the preset formula: ， Calculate the current phase difference change rate, where the is the current phase difference, Current phase difference change rate, is the time constant for the rate of change calculation, is the time interval of the sampling period, for The value of the previous sampling period, for The value of the previous sampling period.

2. The method according to claim 1, characterized in that The step of calculating the corresponding target duty cycle by using a preset fuzzy control algorithm according to the current phase difference information includes: Performing fuzzy processing on the current phase difference and the current phase difference change rate to obtain a first fuzzy amount and a second fuzzy amount; According to the first fuzzy quantity and the second fuzzy quantity, a fuzzy control quantity is calculated by using a preset fuzzy control rule; The fuzzy control amount is defuzzified to obtain the target duty cycle.

3. The method according to claim 2, characterized in that Before calculating the fuzzy control amount according to the first fuzzy amount and the second fuzzy amount by using a preset fuzzy control rule, the method further includes: Creating a fuzzy set, wherein the fuzzy set includes fuzzy control quantities corresponding to fuzzy quantities of multiple phases; The step of calculating the fuzzy control amount according to the first fuzzy amount and the second fuzzy amount by using a preset fuzzy control rule comprises: The fuzzy control amount corresponding to the first fuzzy amount and the second fuzzy amount is searched in the fuzzy set.

4. A low-pressure EGR system VVT phase control device, using the method according to any one of claims 1 to 3, characterized in that: include: Phase acquisition module, used to obtain the current phase of VVT; A phase difference calculation module, used to calculate the difference between the current phase and the preset target phase to obtain current phase difference information; A duty cycle calculation module, used to calculate the corresponding target duty cycle through a preset fuzzy control algorithm according to the current phase difference information; The phase following module is used to drive the OCV action according to the target duty cycle to achieve phase following.

5. The device according to claim 4, characterized in that The current phase difference information includes the current phase difference and the current phase difference change rate, and the phase difference calculation module includes: The phase difference calculation submodule is used to calculate the difference between the current phase and the preset target phase to obtain the current phase difference; The change rate calculation submodule is used to calculate the current phase difference change rate according to the current phase difference.

6. The device according to claim 5, characterized in that The change rate calculation submodule includes: A difference calculation unit, used to calculate a target difference between a current phase difference and the sum of the phase difference of the previous cycle and the phase difference change rate of the previous cycle; The change rate calculation unit is used to calculate the change rate of the target difference over time to obtain the current phase difference change rate.

7. The device according to claim 5, characterized in that The change rate calculation submodule is specifically used to calculate the current phase difference through a preset formula: ， Calculate the current phase difference change rate, where the is the current phase difference, Current phase difference change rate, is the time constant for the rate of change calculation, is the time interval of the sampling period, for The value of the previous sampling period, for The value of the previous sampling period.

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