Control system and method for an electric oil pump

Abstract

The application discloses a control system and method of an electronic oil pump, and relates to the technical field of electronic oil pump control; the system comprises a database, a positioning module, a damping control module, a double-pipe coordination module and a shock monitoring module; through the synergistic effect, the application identifies and avoids the cross unstable interval, dynamically adjusts the damping and flow path switching, and realizes real-time monitoring and graded early warning, so that the electronic oil pump can effectively avoid problems such as pressure shock, oil film thickness discontinuity and uneven hydraulic execution caused by the imbalance of the pump characteristic curve and the pipe impedance matching when the electronic oil pump is in a low-flow working condition or an engine pre-lubrication boundary state; therefore, the application completely solves the technical problem that the electronic oil pump in the prior art is prone to oscillation in a boundary working condition, and greatly improves the stability and reliability of the system.

Description

Technical Field

[0001] This invention relates to the field of electronic oil pump control technology, and more specifically, to a control system and method for an electronic oil pump. Background Technology

[0002] An electronic oil pump is an oil pump directly driven by an electric motor and regulated by an electronic control unit (ECU). It breaks through the traditional method of mechanical transmission by the engine crankshaft or camshaft. It can deliver lubricating oil or hydraulic oil under different engine operating conditions, and even after the engine is turned off, to meet the lubrication needs after pre-lubrication or cold start. However, under low flow conditions or boundary conditions (such as the pre-lubrication stage before the engine starts), the characteristic curve (flow-pressure relationship) of the electronic oil pump and the impedance characteristic curve of the entire oil circuit system often cross into an unstable range. That is, the output characteristics of the electronic oil pump are mismatched with the impedance of the pipeline system, which leads to pressure oscillation, discontinuity in the thickness of the lubricating oil film, or uneven operation of hydraulic actuators. Summary of the Invention

[0003] The main objective of this invention is to provide a control system and method for an electronic oil pump to overcome the problems mentioned in the background art.

[0004] To achieve the above objectives, according to one aspect of the present invention, a control system for an electronic oil pump is provided, the system comprising: a database, a positioning module, a damping control module, a dual-pipe coordination module, and an oscillation monitoring module;

[0005] The database stores the pump characteristic curves of the oil pump: ,in The speed coefficient describes the flow contribution per unit speed. The linear pressure coefficient indicates that the flow rate decreases linearly with increasing pressure. The coefficient of the nonlinear quadratic term reflects the nonlinear loss of fluid under high pressure or low speed, which is usually caused by oil viscosity or leakage in gaps. At the same time, the pressure P(t) and flow rate Q(t) of the oil pump are monitored and collected in real time and stored.

[0006] The positioning module is based on the pump characteristic curve and the system impedance curve derived by combining the Darcy-Weisbach formula and the energy storage cavity effect: ,in The system absorbs flow, representing the flow rate consumed by the system under pressure P. For the oil tank pressure, The constant laminar flow impedance represents the constant flow resistance within the pipe caused by viscous resistance. For pressure-related turbulent impedance, α reflects the nonlinear drag-in characteristics of turbulence under high pressure, and is a turbulence drag coefficient related to pipeline structure and fluid characteristics; C is the cavity compressibility coefficient, which characterizes the system pipeline's ability to accommodate pressure fluctuations (similar to a capacitor). The pressure change rate represents the rate at which pressure changes with time, corresponding to the transient response. The curves of the two are plotted in the same pressure-flow coordinate system and their intersection is numerically solved. The intersection instability interval is located based on the intersection point. When the pump operating point enters this interval, a damping adjustment command is sent to the damping control module, and a valve adjustment command is sent to the dual-pipe coordination module.

[0007] When the damping control module receives a damping adjustment command, it sends adjustment commands to the damping orifice and adjustable throttle valve connected in parallel to the main road, and adjusts the valve opening through a proportional or PI algorithm to suppress oscillations in the cross-instability range.

[0008] When the dual-pipe coordination module receives the valve control command, it uses the three-way proportional valve to smoothly and without impact switch the flow distribution from the buffer pipeline to the regular pipeline within the given switching time window according to the designed cosine buffer function. At the same time, it combines the feedforward compensation term and the damping coupling term, and is supplemented by PID feedback regulation to achieve accurate tracking and oscillation suppression of the oil pressure trajectory.

[0009] After each adjustment is completed, the oscillation monitoring module maintains the set duration and then opens the observation window to continuously sample the difference between the actual pressure and the expected pressure, plots the real-time error curve and compares it with the threshold, calculates the over-limit error integral, i.e., the oscillation value, and executes the corresponding strategy based on the oscillation value.

[0010] Furthermore, the intersection point is used to locate the unstable region of the intersection:

[0011] Will and inverse function Plot the equations on the same pressure-flow axis and solve them in function space. Solve for all real solutions, and each real solution corresponds to a crossover point. For each crossover point, calculate the local slope of the two curves at the crossover point, and subtract the two to obtain the net slope. In the pressure-flow plane, starting from the first crossover point where the net slope is less than zero, follow the pump characteristic curve to the next crossover point until the first crossover point that satisfies the condition of a net slope greater than or equal to zero is encountered. These two crossover points are the crossover instability intervals. Between the two points, the net slope is less than zero, which means divergence and oscillation instability. Thus, the crossover instability intervals of the oil pump can be identified.

[0012] Further, adjust the valve opening:

[0013] After identifying the entry into the cross-instability region, the damping orifice and adjustable throttle valve connected in parallel in the main road are activated. The orifice diameter d0, the corresponding damping coefficient c0, and the electronically controlled opening X(t) ∈ [0,1] of the throttle valve are obtained, and the dynamic damping coefficient after the damping orifice and adjustable throttle valve are connected in parallel are calculated accordingly. : ;

[0014] The pump-pipeline system can be approximated as a first- or second-order inertial-spring-damped system, with an equivalent damping ratio of The calculation formula is: Where m is the equivalent mass, representing the inertial parameter of the oil column and related structures in response to dynamic response; k is the equivalent stiffness, representing the elastic properties of pipelines and oil tanks, and the restoring force parameter to pressure-volume changes; a minimum damping ratio threshold is set. If the equivalent damping ratio <Minimum damping ratio threshold This indicates a tendency to oscillate;

[0015] To adjust the valve opening using proportional or PI control, the damping ratio error must first be calculated. The calculation formula is: It represents the difference between the current equivalent damping ratio and the design minimum damping ratio, and the throttle valve opening at the next moment. The update formula is: ,in K1 represents the current damping valve opening, and K1 is the proportional gain, representing the instantaneous damping ratio error. The response strength of K2 can be increased to speed up the error elimination speed. K2 is the integral gain, which is the response strength to the accumulation of error and is mainly used to eliminate steady-state error. The integral of the error, the cumulative amount of the error over the entire past time window, is used to compensate for the steady-state deviation of the system; the throttle valve opening is controlled such that the throttle valve opening X(t) changes with the damping ratio error. Adjust in real time according to changes, thereby maintaining the system's equivalent damping ratio. Close to or slightly above the design minimum damping ratio threshold This is to suppress oscillations in the cross-instability region.

[0016] Furthermore, dual-path smooth switching and feedforward-feedback composite control:

[0017] Two parallel pipelines are installed at the pump outlet: the left is a buffer pipeline, and the right is a regular pipeline. The three-way proportional valve mixes the two flow rates proportionally according to the electronic control signal β(t)∈[0,1]. The switching process is designed using a cosine buffer function as follows: t is the current system runtime, t∈[ , +T]; where The switching start time is the initial time of the buffer function switching, and T is the switching duration, i.e., the buffer transition time of the entire switching process; let the normalized time variable τ be: ∈[0,1], and substituting this into the buffer function, the buffer function becomes: The first derivative of the buffer function is calculated as follows: and the second derivative is For a first-order function, the endpoint velocity is zero, resulting in a smooth and shock-free process; for a second-order derivative, the endpoint acceleration is zero, avoiding transient oscillations. The design and derivation of this function make reasonable use of the advantages of the cosine function, namely, smooth endpoints, gentle transition, and controllable time width.

[0018] Furthermore, calculate the integral of the out-of-limit error:

[0019] The errors at each time point within the observation window are plotted sequentially on a two-dimensional coordinate system. Then, a smooth curve is used to connect the discrete points in chronological order to obtain the real-time error curve U(t) for the observation window. An error threshold Emax is set, and a straight line is plotted on the two-dimensional coordinate system with the ordinate = Emax. The integral formula is then used... The degree of error is calculated to obtain the oscillation value UE, where U(t) ≤ Emax. =0, when U(t) > Emax, =U(t)-Emax.

[0020] Furthermore, execute the corresponding strategy based on the oscillation value:

[0021] An oscillation range is set. If the oscillation value is within the oscillation range, the current switching duration T is retrieved and increased by an increment of ΔT to obtain the latest switching duration, which is then updated to the dual-tube coordination module. If the oscillation value exceeds the upper limit of the oscillation range, a conservative mode is triggered. The specific conservative mode is as follows: Lock the flow rate at an intermediate value, maintaining 50% flow from both the buffer line and the regular line to avoid greater disturbances caused by frequent switching. Stop using feedforward compensation and simplify the system to pure feedback control to avoid greater oscillations caused by model bias or prediction errors. Then reduce the PID gain to a conservative level. In conservative mode, automatically interlock the safety valve or mechanical relief valve. In conservative mode, control the direct return of some oil to the tank to quickly decouple the high-pressure coupling and protect the pipeline and components.

[0022] To achieve the above objectives, according to another aspect of the present invention, a method for controlling an electronic oil pump is provided, the method comprising the following steps:

[0023] Step 1: Store the pump characteristic curve of the oil pump, and simultaneously monitor and collect the pressure and flow rate of the oil pump in real time and store them; Based on the pump characteristic curve and the system impedance curve derived by combining the Darcy-Weisbach formula and the energy storage chamber effect, plot the two curves in the same pressure-flow coordinate system and numerically solve their intersection point, locate the cross-instability interval according to the intersection point, and send a damping adjustment command to Step 3 when the pump operating point enters this interval, and send a valve adjustment command to Step 4 at the same time;

[0024] Step 2: Upon receiving the damping adjustment command, the adjustment command is sent to the damping orifice and adjustable throttle valve connected in parallel to the main road, and the valve opening is adjusted by proportional or PI algorithm to suppress oscillations in the cross-instability range.

[0025] Step 3: Upon receiving the valve control command, the three-way proportional valve smoothly and without impact switches the flow distribution from the buffer pipeline to the regular pipeline within the given switching time window according to the designed cosine buffer function. At the same time, combined with the feedforward compensation term and the damping coupling term, and supplemented by PID feedback regulation, the oil pressure trajectory is accurately tracked and oscillation is suppressed.

[0026] Step 4: After each adjustment is completed, maintain the set duration and then open the observation window to continuously sample the difference between the actual pressure and the expected pressure, plot the real-time error curve and compare it with the threshold, calculate the over-limit error integral, i.e. the oscillation value, and execute the corresponding strategy based on the oscillation value.

[0027] The beneficial effects of this invention are:

[0028] This invention utilizes pre-stored pump characteristic curves and establishes a system impedance model combining the Darcy-Weisbach formula and the energy storage chamber effect. This allows for the precise identification of all intersections between the pump characteristic curve and the pipeline impedance curve during the system design phase, and quantitative assessment of the net slope change trend at each intersection. When the sum of the slopes of the pump and system impedances is less than zero, it can be identified as a cross-instability region. This amplification effect causes small disturbances to be magnified into significant oscillations. By accurately locating the start and end pressure values ​​of the unstable region in the pressure-flow plane, clear flow and pressure boundaries can be provided for subsequent damping adjustments and flow path switching. This avoids blind control due to mismatch under low flow or boundary conditions, effectively reducing the risk of pressure oscillations and insufficient lubrication caused by unstable regions from the source.

[0029] This invention, when the pump's operating point enters an unstable region, utilizes parallel small-diameter damping orifices and adjustable throttle valves to dynamically calculate the damping coefficient based on real-time pressure and valve opening. It simplifies the pump-pipeline model into an inertial-spring-damping system to estimate the equivalent damping ratio in real time. When the equivalent damping ratio falls below a set minimum threshold, the valve opening is rapidly adjusted using a proportional or PI control algorithm to achieve precise tracking of the damping ratio. This not only rapidly suppresses oscillations within the cross-instability region but also automatically eliminates steady-state errors, keeping the system in a critically stable or slightly higher damping state. This ensures timely attenuation of oil pressure fluctuations under various operating conditions, effectively improving the anti-oscillation capability and safety robustness of the electronic oil pump under varying operating conditions.

[0030] This invention achieves a shock-free transition from a low-impedance buffer path to a high-impedance conventional path by connecting a buffer pipe and a conventional pipe in parallel at the outlet when the pump enters the oscillation zone, and smoothly switching the flow path using a three-way proportional valve according to a cosine buffer function. The designed smooth function with first and second derivatives at zero endpoints avoids sudden changes in speed and acceleration during the switching process and suppresses transient oscillations. At the same time, combined with feedforward compensation and dynamic adjustment of damping coupling terms, and supplemented by PID feedback control, it can pre-compensate and close-loop correct the system's internal resistance and inertial disturbances while ensuring smooth switching. Thus, during the entire switching process, it avoids oil film discontinuity caused by sudden pressure changes and maximizes the system's energy efficiency and response speed.

[0031] This invention quantifies the degree of oscillation by real-time monitoring of the error curve between oil pressure and the desired pressure after each adjustment, calculating the integral of the over-limit error, and automatically adjusting the switching duration or triggering a conservative mode based on a preset oscillation range. In the medium oscillation range, the switching duration is appropriately extended to further smooth the transition. When the oscillation value exceeds the upper limit, it automatically switches to a conservative mode of mixed flow locking and pure feedback control, reducing the PID gain and triggering a safety valve or mechanical relief valve to offset excessive disturbances. This graded response strategy can flexibly cope with minor disturbances and quickly protect pipelines and components during severe oscillations, greatly improving the online adaptive stability and safety of the system.

[0032] In summary, this invention, through synergistic action, identifies and avoids cross-instability regions, dynamically adjusts damping and flow path switching, and provides real-time monitoring and graded early warning. This enables the electronic oil pump to effectively avoid problems such as pressure oscillations, discontinuous oil film thickness, and uneven hydraulic execution caused by mismatches between the pump characteristic curve and pipeline impedance, especially under low-flow conditions or engine pre-lubrication boundary conditions. Therefore, this invention completely solves the technical problem of oscillations in existing electronic oil pumps under boundary conditions, significantly improving the stability and reliability of the system. Attached Figure Description

[0033] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0034] Figure 1 This is a schematic diagram of the system module connections of the present invention;

[0035] Figure 2 This is a schematic diagram of the method flow of the present invention. Detailed Implementation

[0036] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0037] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0038] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of the invention described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0039] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0040] According to embodiments of the present invention, such as Figure 1 As shown, a control system for an electronic oil pump is provided. The system includes: a database, a positioning module, a damping control module, a dual-pipe coordination module, and an oscillation monitoring module.

[0041] The database stores the pump characteristic curves of the oil pump, and simultaneously monitors and collects the oil pump's pressure P and flow rate Q in real time, and stores them.

[0042] The positioning module, based on the pump characteristic curve and the system impedance curve derived from the Darcy-Weisbach formula and the energy storage cavity effect (including constant laminar impedance, pressure-related turbulent impedance, and cavity compression effect), plots the two curves in the same pressure-flow coordinate system and numerically solves their intersection point. It calculates the sum of the local slopes at each real solution and determines that the region where the slope sum is less than zero is the cross-instability interval. Starting from the first intersection point where the slope sum is less than zero, it extends along the pump characteristic curve to the next intersection point where the slope sum is greater than or equal to zero, defining this interval as the unstable interval. When the pump operating point enters this interval, it sends a damping adjustment command to the damping control module and a valve adjustment command to the dual-pipe coordination module.

[0043] When the damping control module receives a damping adjustment command, the controller sends adjustment commands to the small-diameter damping orifice and adjustable throttle valve connected in parallel on the main line. At this time, based on the dynamic damping coefficient determined by the real-time pressure and the opening of the solenoid valve, as well as the pre-given minimum damping ratio threshold, the system converts the pump-pipeline system into an inertia-spring-damping model, calculates the difference between the current equivalent damping ratio and the threshold in real time, and adjusts the valve opening through a proportional or PI algorithm. The combination of proportional gain and integral gain ensures that the damping ratio error is quickly eliminated and the steady-state deviation is eliminated, thereby maintaining the equivalent damping ratio at a level slightly higher than the design minimum value to suppress oscillations in the cross-instability range.

[0044] When the dual-pipe coordination module receives a valve control command, it uses a three-way proportional valve to smoothly and without impact switch the flow distribution from the buffer pipeline to the regular pipeline within a given switching time window, according to the designed cosine buffer function. The first and second derivatives of the buffer function are both zero at the endpoints, effectively avoiding sudden changes in transient velocity or acceleration. At the same time, it combines a feedforward compensation term (dynamic compensation for system internal resistance and inertia) and a damping coupling term, and is further supplemented by PID feedback regulation to achieve accurate tracking of the oil pressure trajectory and oscillation suppression.

[0045] After each adjustment, the oscillation monitoring module maintains the set duration and then opens the observation window to continuously sample the difference between the actual pressure and the expected pressure, plots the real-time error curve, compares it with the threshold, and calculates the over-limit error integral (i.e., the oscillation value). When the oscillation value is lower than the lower limit of the oscillation range, no further operation is required. If it is within the oscillation range, the switching duration is appropriately extended and the system returns to step three to recalculate the feedforward and feedback parameters. If it exceeds the upper limit of the oscillation range, a conservative mode is activated: the dual-path flow is fixed at 50% each, the mixed weight is locked, feedforward compensation is disabled, and only conservative feedback PID control (proportional and integral gains are halved, derivative gain is maintained) is used to reduce the system response speed. A bypass safety valve or mechanical relief valve is activated to return some oil to the tank to ensure the safety of pipelines and components and maximize the robustness of the system.

[0046] According to embodiments of the present invention, such as Figure 2 As shown, a control method for an electronic oil pump is also provided, the method comprising the following steps:

[0047] Step 1: Stability analysis to locate the cross-instability region (i.e., the region where the slope of the characteristic curves is negative after crossing), and to clarify the flow and pressure ranges within this region, providing a basis for subsequent control and damping design; specifically:

[0048] The system pre-stores the pump characteristic curves for each oil pump. The specific process for obtaining the pump characteristic curves is as follows: On an industrial oil pump test bench, the electronic oil pump speed is fixed at the target value w1. The throttle valve control circuit impedance is connected, and a high-precision pressure sensor and flow meter are installed. The throttle valve opening is gradually adjusted to achieve different pipeline impedances. At each setting, after the system pressure stabilizes, the pump outlet pressure P and the corresponding flow rate are recorded. The pump characteristic curve was fitted using the least squares method to obtain the continuous function. ,in The speed coefficient describes the flow contribution per unit speed. The linear pressure coefficient indicates that the flow rate decreases linearly with increasing pressure. The coefficient of the nonlinear quadratic term reflects the nonlinear loss of fluid under high pressure or low speed, which is usually caused by oil viscosity or leakage in gaps.

[0049] Combining the Darcy-Weisbach formula and the energy storage cavity effect, the system consumption flow model is established as follows: ,in The system absorbs flow, representing the flow rate consumed by the system under pressure P. For the oil tank pressure, The constant laminar flow impedance represents the constant flow resistance within the pipe caused by viscous resistance. For pressure-related turbulent impedance, α reflects the nonlinear drag-in characteristics of turbulence under high pressure, and is a turbulence drag coefficient related to pipeline structure and fluid characteristics; C is the cavity compressibility coefficient, which characterizes the system pipeline's ability to accommodate pressure fluctuations (similar to a capacitor). The pressure change rate represents the rate at which pressure changes with time, corresponding to the transient response;

[0050] Will and inverse function Plotting the two curves on the same pressure-flow axis visually shows their intersection and slope changes; solving the equations in function space. Solve for all real solutions, and each real solution corresponds to an intersection point. Mark all intersection points on the graph, where P* is the pressure value at the intersection point, which is the pump characteristic curve. With system impedance curve (Right now The pressure value corresponding to the point of intersection is the point where the flow rates of the two curves are equal; calculate the local slope of the two curves at the equilibrium point using the following formula: and , here It is a notation that refers to the flow rate required by a pipeline or the pipeline's response to flow rate; that is, the equivalent flow rate expression of a pipeline system. = According to the formula Calculate the net slope of the two curves. If the net slope <0 indicates that the system has an "amplification" effect on small disturbances. After deviating from this value, the system will diverge further, causing oscillations or instability. This crossover point and its neighborhood are called the unstable region.

[0051] In the PQ plane, from the first net slope Starting from the intersection point where <0, follow the pump characteristic curve to the next intersection point until the first point that satisfies the net slope is encountered. The two intersection points with a slope ≥ 0 are called the unstable intersection intervals, where the net slope is satisfied between the two points. <0 indicates divergence, oscillation, and instability; this can identify the cross-instability range of the oil pump. If the oil pump is found to have entered the cross-instability range, a damping adjustment command is sent to step two, and a valve adjustment command is sent to step three at the same time.

[0052] By using pre-stored pump characteristic curves and establishing a system impedance model combining the Darcy-Weisbach formula and the energy storage chamber effect, all intersections between the pump characteristic curve and the pipeline impedance curve can be accurately identified during the system design phase, and the net slope change trend at each intersection point can be quantitatively evaluated. When the sum of the slopes of the pump and system impedances is less than zero, it can be determined as a cross-instability region. This amplification effect will cause small disturbances to be amplified into significant oscillations. Based on the precise location of the start and end pressure values ​​of the unstable region in the pressure-flow plane, clear flow and pressure boundaries can be provided for subsequent damping adjustment and flow path switching, avoiding blind control due to mismatch under low flow or boundary conditions, and effectively reducing the risk of pressure oscillations and insufficient lubrication caused by unstable regions in the system from the source.

[0053] Step two involves connecting a small-diameter damping orifice and installing an adjustable throttle valve in parallel within the pipeline. Upon receiving a valve adjustment command, the damping parameters are adjusted in real time to achieve the equivalent damping ratio; specifically:

[0054] The damping element should be installed on the main line between the pump outlet and the bifurcation point of the two pipes. The diameter of the damping orifice is d0, and the corresponding damping coefficient is c0. They are connected in parallel on the same path. The valve core opening is represented by the electronically controlled variable X(t) ∈ [0,1]. The larger the opening, the larger the flow area and the smaller the damping. Its dynamic damping coefficient is denoted as... The final equivalent damping coefficient is usually determined by both pressure and opening degree; The calculation formula is: The pump-pipeline system is approximated as a first- or second-order inertial-spring-damped system, and its equivalent damping ratio is... The calculation formula is: Where m is the equivalent mass, representing the inertial parameter of the oil column and related structures in response to dynamic response; k is the equivalent stiffness, representing the elastic properties of pipelines and oil tanks, and the restoring force parameter to pressure-volume changes; a minimum damping ratio threshold is set. If the equivalent damping ratio <Minimum damping ratio threshold This indicates a tendency to oscillate;

[0055] To adjust the valve opening using proportional or PI control, the damping ratio error must first be calculated. The calculation formula is: It represents the difference between the current equivalent damping ratio and the design minimum damping ratio, and the throttle valve opening at the next moment. The update formula is: ,in K1 represents the current damping valve opening, and K1 is the proportional gain, representing the instantaneous damping ratio error. The response strength of K2 can be increased to speed up the error elimination speed. K2 is the integral gain, which is the response strength to the accumulation of error and is mainly used to eliminate steady-state error. The integral of the error, the cumulative amount of the error over the entire past time window, is used to compensate for the steady-state deviation of the system; the throttle valve opening is controlled such that the throttle valve opening X(t) changes with the damping ratio error. Adjust in real time according to changes, thereby maintaining the system's equivalent damping ratio. Close to or slightly above the design minimum damping ratio threshold To suppress oscillations in the cross-instability region;

[0056] When the pump's operating point enters the unstable region, the damping coefficient is dynamically calculated based on real-time pressure and valve opening using parallel small-diameter damping orifices and adjustable throttle valves. The pump-pipeline model is simplified to an inertial-spring-damping system to estimate the equivalent damping ratio in real time. When the equivalent damping ratio is lower than the set minimum threshold, the valve opening is quickly adjusted using a proportional or PI control algorithm to achieve accurate tracking of the damping ratio. This not only quickly suppresses oscillations in the cross-instability region but also automatically eliminates steady-state errors, keeping the system in a critically stable or slightly higher damping state. This ensures timely attenuation of oil pressure fluctuations under various operating conditions, effectively improving the anti-oscillation capability and safety robustness of the electronic oil pump under varying operating conditions.

[0057] Step three, in the pre-lubrication stage, involves setting up parallel dual pipelines and using a three-way proportional valve for mixing and flow distribution to achieve a smooth switch from the buffer pipeline to the conventional pipeline, suppressing oscillations and maintaining system efficiency; specifically:

[0058] The system is equipped with dual pipelines: a buffer pipeline on the left and a regular pipeline on the right. It should be noted that the pipeline parameters and related calculations in step one are based on the regular pipeline on the right. The buffer pipeline features low resistance, a large diameter, fewer bends, and a smoother characteristic curve at low flow rates. The regular pipeline features high resistance, a standard diameter, and more bends, conforming to the flow-resistance design under normal operating conditions. A three-way proportional valve is installed between the pump outlet and the two branches.

[0059] Upon receiving a valve adjustment command, design and derive a smoothing function, where t is the current time, i.e., the current system running time, and t∈[ , +T]; where The switching start time is the start time of the buffer function switching; T is the switching duration, which is the buffer transition time of the entire switching process. The larger T is, the smoother the switching; the buffer function is: Let the normalized time variable be τ: ∈[0,1], and substituting this into the buffer function, the buffer function becomes: The first derivative of the buffer function is calculated as follows: and the second derivative is For a first-order function, the endpoint velocity is zero, resulting in a smooth and shock-free process; for a second-order derivative, the endpoint acceleration is zero, avoiding transient oscillations. The design and derivation of this function make reasonable use of the advantages of the cosine function, namely, smooth endpoints, gentle transition, and controllable time width.

[0060] Set the desired trajectory under system pressure. The approximate dynamic behavior of the oil circuit is represented by a second-order differential equation: P is the current oil pressure. This refers to hydraulic acceleration, which describes the steepness of the pressure change trend. is the rate of change of oil pressure (the speed of pressure), which describes the speed at which the pressure rises or falls; c is the equivalent damping, i.e., the resistance coefficient of the pipeline valve, which is similar to friction. The channel control gain is the effectiveness of the β control pressure (opening-pressure mapping coefficient). To control the input (obtained from the switching function above); based on the current desired trajectory The feedforward control variable is designed to compensate for the system's internal resistance and inertia. It can quickly compensate for upcoming dynamic disturbances and act in advance on the oil pump control system; For damping coupling terms, θ is the coupling gain, used to adjust the influence of the coupling term to ensure that the system is not over- or under-excited; feedforward control considers both the target trajectory and the current damping state, further improving the system's vibration suppression capability in the unstable region;

[0061] Then, set the PID feedback adaptive adjustment to obtain the feedback controller output. : Where K3 is the differential gain, and the PID controller is based on the actual error. Closed-loop adjustments are performed to compensate for model biases and external disturbances in real time; it should be noted that the total control input... : and constraints ∈[0,1], adjust the flow rate proportionally between the two channels: ;

[0062] By connecting a buffer pipe and a regular pipe in parallel at the outlet when the pump enters the oscillation zone, and smoothly switching the flow path using a three-way proportional valve according to a cosine buffer function, a shock-free transition from the low-impedance buffer path to the high-impedance regular path is achieved. The designed smooth function with first and second derivatives at zero endpoints avoids sudden changes in speed and acceleration during the switching process and suppresses transient oscillations. At the same time, combined with feedforward compensation and dynamic adjustment of damping coupling terms, and supplemented by PID feedback control, the system can pre-compensate and close-loop correct internal resistance and inertial disturbances while ensuring smooth switching. Thus, during the entire switching process, the discontinuity of the oil film caused by sudden pressure changes is avoided, and the system's energy efficiency and response speed are maintained to the maximum extent.

[0063] Step 4: Real-time online oscillation monitoring and early warning;

[0064] After each adjustment using the above steps, maintain the pressure for a fixed duration (1 or 2 minutes), monitor the pressure in real time, and compare it with the desired pressure. The real-time error U(t) is obtained by difference calculation. A fixed time period is used as an observation window (30s, 1min, or 2min, etc.). The errors at each time point within the observation window are plotted sequentially on a two-dimensional coordinate system. Then, a smooth curve is used to connect the discrete points in chronological order to obtain the real-time error curve for the observation window. An error threshold Emax is set. If the real-time error U(t) is greater than the error threshold Emax, it indicates that the error is significant. A straight line is plotted on the two-dimensional coordinate system with the ordinate = Emax. The integral formula is then used... The degree of error is calculated to obtain the oscillation value UE, where U(t) ≤ Emax. =0, when U(t) > Emax, =U(t) - Emax;

[0065] An oscillation range is set. If the oscillation value is less than the lower limit of the oscillation range, it indicates that the system pressure error is very small and can be ignored, requiring no adjustment. If the oscillation value is within the oscillation range, the current switching duration T is retrieved and increased by ΔT to obtain the latest switching duration, which is then updated in step three to reassess the feedforward and feedback components. If the oscillation value is greater than the upper limit of the oscillation range, it indicates that the adjustment effect is poor and the error is serious, triggering the conservative mode. The specific conservative mode is: the mixed weights are adjusted... Locking the flow rate at an intermediate value (0.5), maintaining 50% flow from both the buffer and regular pipelines, avoids greater disturbances caused by frequent switching. Discontinue feedforward compensation, simplifying the system to pure feedback control to prevent larger oscillations caused by model bias or prediction errors. Then, reduce the PID gain to a conservative level (K1 and K2 reduced by 50%, K3 maintained) to slow the response speed, sacrificing some performance for greater robustness. It should be noted that in conservative mode, the automatic interlock bypass safety valve or mechanical relief valve controls the direct return of some oil to the tank, quickly contacting the high-pressure coupling and protecting the pipeline and components.

[0066] After each adjustment, the error curve between the oil pressure and the desired pressure is monitored in real time. The integral of the over-limit error is calculated to quantify the degree of oscillation. The switching duration is automatically adjusted or a conservative mode is triggered according to the preset oscillation range. In the medium oscillation range, the switching time is appropriately extended to further smooth the transition. When the oscillation value exceeds the upper limit, the system automatically switches to a conservative mode of mixed flow locking and pure feedback control, reduces the PID gain, and links the safety valve or mechanical relief valve to offset excessive disturbances. This graded response strategy can flexibly deal with minor disturbances and quickly protect pipelines and components in the event of severe oscillations, greatly improving the online adaptive stability and safety of the system.

[0067] The above are merely embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A control system for an electronic oil pump, comprising a database storing pump characteristic curves of the oil pump, and simultaneously monitoring and acquiring the pressure and flow rate of the oil pump in real time, and storing the data. characterized in that Also includes: The positioning module, based on the pump characteristic curve and the system impedance curve derived from the Darcy-Weisbach formula and the energy storage chamber effect, plots the two curves in the same pressure-flow coordinate system and numerically solves for their intersection points. It then locates the cross-instability interval based on these intersection points. When the pump's operating point enters this interval, it sends a damping adjustment command to the damping control module and a valve adjustment command to the dual-pipe coordination module. The method for locating the cross-instability interval based on the intersection points involves: placing the pump characteristic curve and the system impedance curve in the same pressure-flow coordinate system; numerically solving for the real solutions of the two curves; each real solution being the intersection point of the two curves; calculating the local slope of each curve at the intersection point; and subtracting the two slopes to obtain the net slope. In the pressure-flow plane, starting from the first intersection point where the net slope is less than zero, the module follows the pump characteristic curve to the next intersection point until it encounters the first intersection point where the net slope is greater than or equal to zero. These two intersection points are the cross-instability intervals. Between these two points, the net slope is less than zero, indicating divergent or oscillating instability. This method can thus identify the cross-instability intervals of the oil pump. When the damping control module receives a damping adjustment command, it sends adjustment commands to the damping orifice and adjustable throttle valve connected in parallel to the main road, and adjusts the valve opening through a proportional or PI algorithm to suppress oscillations in the cross-instability range. When the dual-pipe coordination module receives the valve control command, it uses the three-way proportional valve to smoothly and without impact switch the flow distribution from the buffer pipeline to the regular pipeline within the given switching time window according to the designed cosine buffer function. At the same time, it combines the feedforward compensation term and the damping coupling term, and is supplemented by PID feedback regulation to achieve accurate tracking and oscillation suppression of the oil pressure trajectory. After each adjustment is completed, the oscillation monitoring module maintains the set duration and then opens the observation window to continuously sample the difference between the actual pressure and the expected pressure, plots the real-time error curve and compares it with the threshold, calculates the over-limit error integral, i.e. the oscillation value, and executes the corresponding strategy based on the oscillation value.

2. The control system of an electric oil pump according to claim 1, wherein Adjust the valve opening: After identifying the entry into the cross-instability region, the damping orifice and adjustable throttle valve connected in parallel in the main road are activated to obtain the orifice diameter, corresponding damping coefficient and the electronic control opening of the throttle valve, and the dynamic damping coefficient after the damping orifice and adjustable throttle valve are connected in parallel are calculated accordingly. The pump-pipeline system is approximated as a first- or second-order inertial-spring-damped model. The equivalent damping ratio is calculated, and a minimum damping ratio threshold is preset. The damping ratio error is obtained by subtracting the equivalent damping ratio from the minimum damping ratio threshold. The valve opening is then updated through proportional-integral control until the latest equivalent damping ratio is greater than or equal to the minimum damping ratio threshold.

3. The control system of an electric oil pump according to claim 2, wherein Dual-path smooth switching and feedforward-feedback composite control: Two parallel pipelines are installed at the pump outlet: the left is a buffer pipeline, and the right is a regular pipeline. The three-way proportional valve mixes the two flow rates proportionally according to the electronic control signal β(t)∈[0,1]. The switching process is designed using a cosine buffer function as follows: t is the current system runtime, t∈[ , +T]; where The switching start time is the start time of the buffer function switching, and T is the switching duration, which is the buffer transition time of the entire switching process. The function has zero first and second derivatives at the endpoints. The system constructs a second-order differential model based on the current target pressure trajectory and designs a feedforward compensation term to pre-counteract the system's internal resistance and inertial disturbances. At the same time, a damping coupling term is added to enhance the suppression of transient fluctuations. The final control quantity is the sum of the feedforward and PID feedback, which drives the three-way valve. The damping coupling term is composed of the damping ratio error.

4. The control system of an electric oil pump according to claim 3, wherein Calculate the integral of the out-of-limit error: The errors at each time point within the observation window are plotted sequentially on a two-dimensional coordinate system. Then, a smooth curve is used to connect the discrete points in chronological order to obtain the real-time error curve U(t) for the observation window. An error threshold Emax is set, and a straight line is plotted on the two-dimensional coordinate system with the ordinate = Emax. The integral formula is then used... The degree of error is calculated to obtain the oscillation value UE, where U(t) ≤ Emax. =0, when U(t) > Emax, =U(t)-Emax.

5. The control system of an electric oil pump according to claim 4, wherein Execute the corresponding strategy based on the oscillation value: An oscillation range is set. If the oscillation value is within the oscillation range, the current switching duration T is retrieved and increased by an increment of ΔT to obtain the latest switching duration, which is then updated to the dual-tube coordination module. If the oscillation value exceeds the upper limit of the oscillation range, a conservative mode is triggered. The specific conservative mode is as follows: Lock the flow rate at an intermediate value, ensuring that the buffer line and the regular line each provide 50% of the flow to avoid greater disturbances caused by frequent switching. Stop using feedforward compensation and simplify the system to pure feedback control to avoid greater oscillations caused by model bias or prediction errors. Then reduce the PID gain to a conservative level. In conservative mode, automatically interlock the safety valve or mechanical relief valve. In conservative mode, control the direct return of some oil to the oil tank to quickly decouple the high pressure and protect the pipeline and components.

6. A control method for an electronic oil pump, characterized in that... A control system for an electronic oil pump as described in any one of claims 1-5, comprising: Step 1: Store the pump characteristic curve of the oil pump, and simultaneously monitor and collect the pressure and flow rate of the oil pump in real time and store them; Based on the pump characteristic curve and the system impedance curve derived by combining the Darcy-Weisbach formula and the energy storage chamber effect, plot the two curves in the same pressure-flow coordinate system and numerically solve their intersection point, locate the cross-instability interval according to the intersection point, and send a damping adjustment command to Step 2 when the pump operating point enters this interval, and send a valve adjustment command to Step 3 at the same time; Step 2: Upon receiving the damping adjustment command, the adjustment command is sent to the damping orifice and adjustable throttle valve connected in parallel to the main road, and the valve opening is adjusted by proportional or PI algorithm to suppress oscillations in the cross-instability range. Step 3: Upon receiving the valve control command, the three-way proportional valve smoothly and without impact switches the flow distribution from the buffer pipeline to the regular pipeline within the given switching time window according to the designed cosine buffer function. At the same time, combined with the feedforward compensation term and the damping coupling term, and supplemented by PID feedback regulation, the oil pressure trajectory is accurately tracked and oscillation is suppressed. Step 4: After each adjustment is completed, maintain the set duration and then open the observation window to continuously sample the difference between the actual pressure and the expected pressure, plot the real-time error curve and compare it with the threshold, calculate the over-limit error integral, i.e. the oscillation value, and execute the corresponding strategy based on the oscillation value.

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