Multi-mode dynamic regulation and control motor control method for urea supply of diesel vehicle SCR (Selective Catalytic Reduction) system

Abstract

The invention provides a multi-mode dynamic regulation and control motor control method for urea supply of a diesel vehicle SCR (Selective Catalytic Reduction) system, which comprises the following steps: after the SCR system enters an initialized starting mode, driving a urea supply motor to operate according to a preset initial rotating speed to realize soft start; the urea pressure in the urea supply pipeline is obtained in real time, and the urea pressure deviation delta p is calculated according to the time base unit; in each time base unit, according to the urea pressure deviation and the partition thereof, the rotating speed of a urea supply motor is dynamically adjusted to carry out closed-loop correction on the urea pressure, and the rotating speed is limited through dynamic amplitude limiting in the correction process to prevent integral saturation; and in response to the situation that the urea pressure deviation of continuous N time base units exceeds a preset value, the urea supply motor is controlled and driven to be shut down in a gradient mode, and after the rotating speed of the urea supply motor is reduced to the safety threshold range, the urea supply motor is shut down and enters the standby state. According to the invention, high-precision, fast-response and low-impact urea pump motor control can be realized, and reliable operation of an SCR system and a diesel engine vehicle is ensured.

Description

Technical Field

[0001] This invention relates to the field of diesel engine exhaust gas treatment technology, and in particular to urea supply control of SCR systems. Specifically, it relates to a multi-mode dynamic regulation motor control method for urea supply in diesel vehicle SCR systems. Background Technology

[0002] In diesel engine exhaust treatment systems, the urea injection system is the core component for reducing nitrogen oxide emissions. By precisely controlling the urea pump motor speed to adjust the injection pressure and urea injection quantity, the reducing agent reacts fully with the exhaust gas.

[0003] Traditional urea pump motor control strategies rely entirely on mechanical structures to ensure urea supply, driven by a preset fixed PWM duty cycle. This results in relatively low control accuracy, with a pressure error of ±1.5 bar, only meeting early emission regulations such as Euro III. To address this, an improved urea pump motor control strategy was developed based on Euro IV / V standards. This strategy employs single-loop PID control, using pressure sensor feedback for dynamic adjustment. While relying on fixed parameters for full-condition pressure control, the error is reduced to ±0.5 bar. Although it supports Euro IV / V standards, the fixed parameters and 10-20ms polling cycle lead to significant response lag under complex operating conditions. With a 10-20ms polling control cycle, the adjustment delay exceeds 50ms when facing sudden pressure changes (ΔP ≥ 1.0 bar) such as rapid acceleration, causing NOx conversion rate fluctuations of ±15%. Furthermore, the mechanical shock during urea pump motor start-up and shutdown is severe. The instantaneous torque at startup is 12.5 N·m, and the sudden pressure drop during shutdown triggers water hammer, shortening the pump bearing life.

[0004] Meanwhile, the linear regulation control algorithm under traditional single closed-loop PID control cannot take into account both response speed and overshoot. For example, under a target pressure of 3.0 bar, the actual pressure fluctuation range reaches ±0.2 bar, which exceeds the upper limit of ±0.1 bar required by the China VI emission standard. The steady-state accuracy is insufficient, the system failure rate is high, and it is difficult to meet the increasingly stringent emission regulations and vehicle reliability requirements. Summary of the Invention

[0005] To address the technical problems existing in the control of the brushless motor (DLBC, Digital Linear Braking Control) for urea supply in diesel vehicle exhaust gas treatment SCR systems, this invention proposes a multi-mode dynamic adjustment motor control method, which is applicable to the DLBC motor for urea supply in diesel vehicle exhaust gas treatment SCR systems. This method achieves high-precision, fast-response, and low-impact control, ensuring the reliable operation of the SCR system and diesel engine vehicles.

[0006] A first aspect of the present invention provides a multi-mode dynamic regulation motor control method for urea supply in a diesel vehicle SCR system, comprising the following steps: Step 1: After receiving the start command from the vehicle ECU, the SCR system enters the initialization start mode and drives the urea supply motor to run according to the preset initial speed to achieve a soft start. Step 2: After soft start, acquire the urea pressure in the urea supply pipeline in real time, and calculate the urea pressure deviation Δp according to the time base unit; Step 3: Within each time base unit, dynamically adjust the urea supply motor speed based on the urea pressure deviation and its zone to perform closed-loop correction of the urea pressure. During the correction process, dynamically limit the speed to prevent integral saturation; and Step 4: In response to the urea pressure deviation exceeding the preset value for N consecutive time base units, control the urea supply motor to stop gradually. After the urea supply motor speed drops to the safe threshold range, it stops and enters standby mode.

[0007] As an optional embodiment, in step 1, the preset initial speed is set to the soft-start motor speed BeginSpeed ​​based on the steady-state speed RatedSpeed ​​of the target pressure TargetPres under standard diesel vehicle operating conditions: BeginSpeed=(50%~65%)*RatedSpeed*η+150PWM Where η represents the working condition correction factor: under standard working conditions, η=1; when the ambient temperature T<0℃, η increases by 5% for every 10℃ decrease; and when the ambient temperature T>25℃, η decreases by 1% to 5% for every 10℃ increase.

[0008] As an optional embodiment, in step 3, a time-varying gain adjustment strategy is adopted, using the soft-start motor speed BeginSpeed ​​as a reference, to dynamically adjust the urea supply motor speed and perform closed-loop correction of the urea pressure, specifically including: When Δp < -1 bar, it is in the low-pressure zone, and step compensation dynamic correction is adopted, with speed +6PWM / time base; When -1bar≤Δp<-0.05bar, it is in the low steady-state region, and a fine-tuning compensation dynamic correction is adopted, with the speed +1PWM / time base; When 0.05bar < Δp ≤ 1bar, it is in the overshoot warning zone, and a fine-tuning step size dynamic correction is adopted, with the speed being -1PWM / time base; When Δp > 1 bar, it is in the high-voltage region, and a high-gain fast correction is adopted, with the speed + 6PWM / time base. When -0.05bar≤Δp≤0.05bar, it is in the steady-state lockout region and adjustment is prohibited.

[0009] As an optional embodiment, in step 3, for the dynamically corrected urea supply motor speed PumpSpdSet, the speed is dynamically limited based on the clamp function to prevent integral saturation. clamp(PumpSpdSet,PmpPWMlowC,PmpPWMuppC); Wherein, PmpPWMlowC and PmpPWMuppC represent the minimum threshold and the maximum threshold of the PWM output for the urea supply motor speed, respectively.

[0010] As an optional embodiment, in step 4, in response to the urea pressure deviation exceeding a preset value for N consecutive time base units, the urea supply motor is controlled to gradually stop. After the urea supply motor speed drops to a safe threshold range, it stops and enters a standby state, including: When the urea pressure deviation Δp exceeds a preset value for N consecutive time base units, the urea supply motor speed PumpSpdSet is determined to be within a certain range, and ramp speed reduction control is performed, where: When PumpSpdSet is above 300PWM, control PumpSpdSet to decrease by -10PWM / timebase; when PumpSpdSet is above 100PWM and below 300PWM, control PumpSpdSet to decrease by -5PWM / timebase. Stop adjusting and shut down when the PumpSpdSet value is less than 100PWM, which is a safe condition.

[0011] As an optional embodiment, during closed-loop correction and gradient stop control, an acceleration limit for motor speed adjustment is embedded through pre-compensation filter control to suppress maximum instantaneous torque and mechanical shock load.

[0012] As an optional embodiment, the motor speed adjustment is controlled by a pre-compensation filter, incorporating an acceleration limit. If the difference between the adjusted motor speed new_speed and the current motor speed current_speed is greater than or equal to the maximum acceleration threshold MAX_ACCEL*Δt, then the current motor speed is used as the basis, and the adjusted motor speed is obtained by adjusting it by ± the maximum acceleration threshold MAX_ACCEL*Δt. Among them, the adjusted motor speed new_speed refers to the motor speed after adjustment through step 3 or step 4 during the closed-loop correction and gradient stop control process, and current_speed refers to the current speed before the adjustment.

[0013] The multi-mode dynamic control method for motors proposed in this invention is applicable to the high-precision, fast-response, and low-impact control of the brushless motor (urea pump motor) supplying urea in the SCR system of diesel vehicle exhaust gas treatment. Through soft start, closed-loop dynamic adjustment under stability constraints, and slope deceleration gradient stop control, a three-level dynamic control is achieved, covering the entire cycle control from start to stop, realizing high-precision and high-stability urea supply, and ensuring the reliable operation of the SCR system and diesel engine vehicles.

[0014] It should be understood that all combinations of the foregoing concepts and the additional concepts described in more detail below may be considered part of the inventive subject matter of this disclosure, provided that such concepts do not contradict each other. Furthermore, all combinations of the claimed subject matter are considered part of the inventive subject matter of this disclosure.

[0015] The foregoing and other aspects, embodiments, and features of the teachings of the present invention will be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the invention, such as features and / or beneficial effects of exemplary embodiments, will become apparent from the following description or may be learned through practice of specific embodiments according to the teachings of the present invention. Attached Figure Description

[0016] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in the various figures may be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the invention will now be described by way of example and with reference to the accompanying drawings.

[0017] Figure 1 This is a flowchart illustrating a multi-mode dynamic control method for motors according to an embodiment of the present invention.

[0018] Figure 2 This is a MAP diagram of urea injection under actual vehicle conditions, based on the multi-mode dynamic control method of the present invention. Detailed Implementation

[0019] To better understand the technical content of the present invention, specific embodiments are described below in conjunction with the accompanying drawings.

[0020] Various aspects of the invention are described in this disclosure with reference to the accompanying drawings, which illustrate numerous illustrative embodiments. The embodiments of this disclosure are not necessarily intended to encompass all aspects of the invention. It should be understood that the various concepts and embodiments described above, as well as those described in more detail below, can be implemented in any of many ways, because the concepts and embodiments disclosed herein are not limited to any particular implementation. Furthermore, some aspects of the invention disclosed may be used alone or in any suitable combination with other aspects of the invention disclosed.

[0021] {Example 1} As shown in the accompanying drawings, the multi-mode dynamic control method for motors according to embodiments of the present invention is applicable to the control of the DLBC motor (i.e., urea pump motor) supplying urea in a diesel vehicle SCR system, and includes: Step 1: After receiving the start command from the vehicle ECU, the SCR system enters the initialization start mode and drives the urea supply motor to run according to the preset initial speed to achieve a soft start. Step 2: After soft start, acquire the urea pressure in the urea supply pipeline in real time, and calculate the urea pressure deviation Δp according to the time base unit; Step 3: Within each time base unit, dynamically adjust the urea supply motor speed based on the urea pressure deviation and its zone to perform closed-loop correction of the urea pressure. During the correction process, dynamically limit the speed to prevent integral saturation; and Step 4: In response to the urea pressure deviation exceeding the preset value for N consecutive time base units, control the urea supply motor to stop gradually. After the urea supply motor speed drops to the safe threshold range, it stops and enters standby mode.

[0022] As an optional embodiment, in step 1, the preset initial speed is set to the soft-start motor speed BeginSpeed ​​based on the steady-state speed RatedSpeed ​​of the target pressure TargetPres under standard diesel vehicle operating conditions: BeginSpeed=(50%~65%)*RatedSpeed*η+150PWM Where η represents the working condition correction factor: under standard working conditions, η=1; when the ambient temperature T<0℃, η increases by 5% for every 10℃ decrease; and when the ambient temperature T>25℃, η decreases by 1% to 5% for every 10℃ increase.

[0023] In the embodiments of the present invention, the steady-state speed of the diesel engine under target pressure and standard operating conditions is used as the benchmark value. Dynamic adaptive correction is made for low temperature and high temperature environments: when the temperature is low, the fluidity is poor, and the speed is appropriately increased to avoid the pump body from getting stuck due to the viscosity of the medium; when the temperature is high, the speed is appropriately reduced to prevent overheating and overshoot risks during the start-up phase due to the influence of fluidity and motor heat dissipation.

[0024] It should be understood that, in the embodiments of the present invention, based on the principles of minimizing mechanical shock and matching the system pressure target, a soft-start strategy is adopted for the DLBC control of the SCR system. Instead of starting at full speed directly, a step-by-step acceleration method of BeginSpeed ​​+ 150PWM is used to avoid the step-like shock from zero speed to high speed (target pressure corresponds to speed) in traditional control. If BeginSpeed ​​is too high, the pressure will quickly exceed the target value after startup, requiring a significant pullback in the closed-loop control, increasing the risk of overshoot and response time. If BeginSpeed ​​is too low, the pressure will rise too slowly after startup, prolonging the time to reach the target pressure, making it difficult to meet the requirement of a transition time of ≤300ms from startup to steady-state pressure.

[0025] In embodiments of the present invention, the steady-state speed RatedSpeed ​​can be determined through bench tests under standard operating conditions: Under standard operating conditions (temperature 25℃, target pressure 3.0 bar), the motor speed at steady state was tested, with 2000 RPM as an example. Take 60% of it as the BeginSpeed ​​baseline: 2400 × 65% = 1440 RPM; Convert the rotational speed unit RPM into a PWM signal value.

[0026] Furthermore, in practical applications, dynamic adjustments are made based on the actual environment.

[0027] After the revision, in the optional embodiments, further verification and optimization can be achieved through rack testing: (For example, setting initial candidate values: 140PWM, 145PWM, 155PWM) Test the starting impact (measured by torque sensor) and pressure response time (recorded by pressure sensor) corresponding to each value. The optimal value with the minimum impact and a response time ≤300ms is selected as the final BeginSpeed.

[0028] Therefore, by configuring BeginSpeed, it is possible to minimize mechanical shock while ensuring startup speed, which serves as the basis for closed-loop adjustment of subsequent modes.

[0029] As an optional implementation, in step 2, the urea pressure deviation Δp is calculated based on the real-time urea pressure UreaPressBar in the urea supply pipeline: Δp=UreaPressBar–TargetPres; TargetPres represents the target pressure, as mentioned above, taking 3 bar as an example.

[0030] In an optional embodiment, in step 3, a time-varying gain adjustment strategy is adopted, using the soft-start motor speed BeginSpeed ​​as a reference, to dynamically adjust the urea supply motor speed and perform closed-loop correction of the urea pressure, specifically including: When Δp < -1 bar, it is in the low pressure zone. Step compensation dynamic correction is adopted, with speed +6PWM / time base, to deal with drastic pressure fluctuations, such as rapid acceleration conditions, and quickly recover to the quasi-steady state range. When -1bar≤Δp<-0.05bar, it is in the low steady-state region. Fine-tuning compensation and dynamic correction are adopted, with the speed +1PWM / time base, so that when approaching the target pressure, it can make gradual fine-tuning in small steps to avoid overshoot. When 0.05bar < Δp ≤ 1bar, it is in the overshoot warning zone. Fine-tuning step size dynamic correction is adopted to offset the positive overshoot trend in advance. The speed is -1PWM / time base. When Δp > 1 bar, it is in the high-voltage region, and a high-gain fast correction is adopted, with the speed + 6PWM / time base. When -0.05bar≤Δp≤0.05bar, it is in the steady-state lockout region, and adjustment is prohibited to prevent high-frequency oscillation and maintain steady state.

[0031] Therefore, by using multi-interval segmented nonlinear correction to achieve segmented compensation, the pressure control accuracy is improved to ±0.05 bar. Compared with the traditional PID control which fluctuates at ±0.2 bar, this invention reduces the steady-state error by 75% through segmented nonlinear compensation control. At the same time, it combines a dynamic PWM limiter (clamp function constraint) for boundary constraint protection, suppresses integral saturation, and avoids overshoot caused by accumulated error.

[0032] As an optional embodiment, in step 3, for the dynamically corrected urea supply motor speed PumpSpdSet, the speed is dynamically limited based on the clamp function to prevent integral saturation. clamp(PumpSpdSet,PmpPWMlowC,PmpPWMuppC); Wherein, PmpPWMlowC and PmpPWMuppC represent the minimum threshold and the maximum threshold of the PWM output for the urea supply motor speed, respectively.

[0033] In a specific embodiment, after the SCR system is initialized and started, it enters mode 0, uses the configured BeginSpeed+150PWM as the initial starting speed to complete the start-up and avoid zero-speed step impact, and initializes the status flag bit: begin=0, thereby providing a unified initial condition for the subsequent mode 1 (dynamic closed-loop adjustment).

[0034] As an optional embodiment, after starting with BeginSpeed+150PWM and delaying by one time base period, it is further accelerated to BeginSpeed+200PWM, and then jumps to the subsequent mode 1 (dynamic closed-loop adjustment) to correct the pressure deviation and maintain steady-state accuracy. The flag begin=1.

[0035] As mentioned above, in the dynamic closed-loop adjustment mode of Mode 1, dynamic adjustment is achieved through the aforementioned multi-interval piecewise nonlinear correction, specifically as follows: Emergency compensation zone (|ΔP|≥1.0 bar): High gain regulation (±6 PWM / cycle) is used. Fine-tuning range (0.05 bar ≤ |ΔP| < 1.0 bar): Employs progressive fine-tuning (±1 PWM / cycle). Stable lockout zone (|ΔP|<0.05bar): Adjustment is prohibited to avoid overshoot and overshoot.

[0036] As an optional implementation, when the SCR system receives a shutdown command or detects a system malfunction (such as abnormal pressure or signal loss), it switches to mode 2 and enters the gradient shutdown control mode.

[0037] In Mode 2, ramp speed reduction control is performed based on the range of the urea supply motor speed PumpSpdSet: When PumpSpdSet is above 300PWM, control PumpSpdSet to decrease by -10PWM / timebase; when PumpSpdSet is above 100PWM and below 300PWM, control PumpSpdSet to decrease by -5PWM / timebase. Once the PumpSpdSet reaches a safety threshold of less than 100PWM, stop adjusting (to avoid low-speed resonance) and shut down the motor.

[0038] In an optional embodiment, in step 4, in response to the urea pressure deviation exceeding a preset value for N consecutive time base units, a prediction mechanism is triggered to automatically adjust to mode 2. In mode 2, the urea supply motor is controlled to stop gradually. After the speed of the urea supply motor drops to a safe threshold range, it stops and enters standby mode.

[0039] That is: when the urea pressure deviation Δp exceeds the preset value for N consecutive time base units, ramp speed reduction control is performed based on the range of the urea supply motor speed PumpSpdSet. When PumpSpdSet is above 300PWM, control PumpSpdSet to decrease by -10PWM / timebase; when PumpSpdSet is above 100PWM and below 300PWM, control PumpSpdSet to decrease by -5PWM / timebase. Stop adjusting and shut down when the PumpSpdSet value is less than 100PWM, which is a safe condition.

[0040] As an optional implementation, the aforementioned time base unit is configured as 1ms.

[0041] As an optional implementation, during closed-loop correction and gradient stop control, a pre-compensation filter is used to embed an acceleration limit on the motor speed adjustment in order to suppress the maximum instantaneous torque and mechanical impact load.

[0042] Among them, the acceleration limit for motor speed adjustment is embedded through pre-compensation filter control, including: If the difference between the adjusted motor speed new_speed and the current motor speed current_speed is greater than or equal to the maximum acceleration threshold MAX_ACCEL*Δt, then the current motor speed is used as the basis, and the adjusted motor speed is obtained by adjusting it by ± the maximum acceleration threshold MAX_ACCEL*Δt. Among them, the adjusted motor speed new_speed refers to the motor speed after adjustment through step 3 or step 4 during the closed-loop correction and gradient stop control process, and current_speed refers to the current speed before the adjustment.

[0043] In an embodiment of the present invention, the aforementioned maximum acceleration threshold MAX_ACCEL is set to 50PWM / ms.

[0044] Combining the multi-mode dynamic motor control method of the above embodiments, this invention changes the 15-20ms delay of traditional polling control. It constructs a 1ms time-base interrupt based on a hardware timer g_timer0Count, with a minimum response unit of 1ms for mode 1 adjustment cycle, achieving real-time dynamic response. Simultaneously, it achieves "atomic operation" (requiring only one instruction cycle) through the begin flag, avoiding parameter conflicts during switching and enabling zero-delay switching from mode 0 to 1. It also monitors ΔP in real time; if it exceeds the limit for 5 consecutive cycles, it triggers mode migration 1→2 in advance, rather than waiting for a fault to occur before responding, thus achieving dynamic and rapid response.

[0045] The DLBC motor control of the urea pump motor based on this invention, tested with a Fluke 729 calibrator, shows that within the 1.5~4.5 bar range, 95% of the test points meet |Pactual-Ptarget|≤0.05 bar, reducing the steady-state error by 75% compared to traditional PID control (±0.2 bar fluctuation), improving pressure control accuracy to ±0.05 bar, and shortening the transition time by 40%; at the same time, it improves the dynamic response speed to 1 time base period (1 ms), reducing the delay by 90% compared to traditional polling.

[0046] In summary, the DLBC motor control method for urea pump motors proposed in this invention has the following significant advantages: 1. By adopting time-based interrupt driving and an interrupt service flow based on a hardware timer (1ms cycle), the deterministic response of control instructions is ensured, the dynamic adjustment delay is less than 1ms, the response speed is improved by 80% compared with the traditional polling control method, and the dynamic response speed and real-time performance are improved. At the same time, the event triggering mechanism is set to trigger compensation calculation only when the deviation exceeds the dead zone (ΔP≥0.05 bar), thereby reducing CPU load; 2. Based on the aforementioned nonlinear segmented compensation strategy: Emergency compensation zone (|ΔP|≥1.0 bar): High-gain compensation (±6 PWM / cycle) quickly eliminates deviations, reducing transition time by 40%; Fine adjustment zone (0.05 bar≤|ΔP|<1.0 bar): Small-step fine adjustment (±1 PWM / cycle), stabilizing steady-state error within ±0.05 bar; Dead zone locking (|ΔP|<0.05 bar): Suppresses high-frequency oscillations; Further combined with multiple limiting protections: hardware limiting (Pmp_PWMlow_C / Pmp_PWMupp_C) and soft acceleration limiting (MAX_ACCEL) to prevent speed overshoot and pressure runaway, achieving high-precision pressure control. 3. In Mode 2, by setting a gradient shutdown algorithm, the mechanical shock load is reduced by smoothly transitioning through step-by-step deceleration. At the same time, it locks at low speed (stops adjustment when <100 PWM) to avoid operation in the resonance zone, improve the life of the system bearing, and achieve mechanical shock suppression and system life improvement. Brushless motor optimization: Combined with dynamic speed compensation, carbon brush wear problems are completely eliminated, and the overall lifespan reaches more than 50,000 hours.

[0047] 4. Based on an atomic state transition design, conflict-free mode switching is achieved through flag bits (such as begin) and interrupt protection, reducing switching jitter: Mode 0→1 forces initialization (begin=0) to ensure the consistency of initial conditions for closed-loop regulation; under fault tolerance and recovery mechanisms, such as in the event of abnormal pressure or signal loss, it automatically jumps to mode 2 for safe shutdown, shortening the fault recovery time to 10ms, thus improving the stability and reliability of mode switching. It should be understood that, although the embodiments of the present invention are described using the urea supply drive motor (urea pump DLBC motor) of the diesel vehicle exhaust gas treatment SCR system as an example, it can be seen from the above embodiments of the present invention that the multi-mode dynamic control motor control method proposed in the present invention can also be applied to the DLBC motor control of industrial servo drives, electric vehicle cooling pumps, and smart home appliances (such as variable frequency washing machines).

[0048] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A multi-mode dynamic regulation motor control method for urea supply in a diesel vehicle SCR system, characterized in that, include: Step 1: After receiving the start command from the vehicle ECU, the SCR system enters the initialization start mode and drives the urea supply motor to run according to the preset initial speed to achieve a soft start. Step 2: After soft start, acquire the urea pressure in the urea supply pipeline in real time, and calculate the urea pressure deviation Δp according to the time base unit; Step 3: Within each time base unit, dynamically adjust the speed of the urea supply motor to perform closed-loop correction of the urea pressure based on the urea pressure deviation and its zone, and prevent integral saturation by dynamically limiting the speed during the correction process. as well as Step 4: In response to the urea pressure deviation exceeding the preset value for N consecutive time base units, control the urea supply motor to stop gradually. After the urea supply motor speed drops to the safe threshold range, it stops and enters standby mode.

2. The multi-mode dynamic regulation motor control method for urea supply in a diesel vehicle SCR system according to claim 1, characterized in that, In step 1, the preset initial speed is set to the soft-start motor speed BeginSpeed, which is based on the steady-state speed RatedSpeed ​​under standard diesel vehicle operating conditions at the target pressure TargetPres. BeginSpeed=(50%~65%)*RatedSpeed*η+150PWM Where η represents the working condition correction factor: η=1 under standard working conditions; when the ambient temperature T<0℃, η increases by 5% for every 10℃ decrease; and when the ambient temperature T>25℃, η decreases by 1% to 5% for every 10℃ increase.

3. The multi-mode dynamic regulation motor control method for urea supply in a diesel vehicle SCR system according to claim 1, characterized in that, In step 2, the urea pressure deviation Δp is calculated based on the real-time urea pressure UreaPressBar in the urea supply pipeline: Δp=UreaPressBar–TargetPres; TargetPres represents the target pressure.

4. The multi-mode dynamic regulation motor control method for urea supply in a diesel vehicle SCR system according to claim 1, characterized in that, In step 3, a time-varying gain adjustment strategy is adopted, using the soft-start motor speed BeginSpeed ​​as a reference, to dynamically adjust the urea supply motor speed and perform closed-loop correction of the urea pressure. Specifically, this includes: When Δp < -1 bar, it is in the low-pressure zone, and step compensation dynamic correction is adopted, with speed +6PWM / time base; When -1bar≤Δp<-0.05bar, it is in the low steady-state region, and a fine-tuning compensation dynamic correction is adopted, with the speed +1PWM / time base; When 0.05bar < Δp ≤ 1bar, it is in the overshoot warning zone, and a fine-tuning step size dynamic correction is adopted, with the speed being -1PWM / time base; When Δp > 1 bar, it is in the high-voltage region, and a high-gain fast correction is adopted, with the speed + 6PWM / time base. When -0.05bar≤Δp≤0.05bar, it is in the steady-state lockout region and adjustment is prohibited.

5. The multi-mode dynamic regulation motor control method for urea supply in a diesel vehicle SCR system according to claim 5, characterized in that, In step 3, for the dynamically corrected urea supply motor speed PumpSpdSet, the speed is dynamically limited based on the clamp function to prevent integral saturation. clamp(PumpSpdSet,PmpPWMlowC,PmpPWMuppC); Wherein, PmpPWMlowC and PmpPWMuppC represent the minimum threshold and the maximum threshold of the PWM output for the urea supply motor speed, respectively.

6. The multi-mode dynamic regulation motor control method for urea supply in a diesel vehicle SCR system according to claim 5, characterized in that, In step 4, in response to the urea pressure deviation exceeding a preset value for N consecutive time base units, the urea supply motor is controlled to gradually stop. After the urea supply motor speed drops to a safe threshold range, it stops and enters a standby state, including: When the urea pressure deviation Δp exceeds a preset value for N consecutive time base units, the urea supply motor speed PumpSpdSet is determined to be within a certain range, and ramp speed reduction control is performed, where: When PumpSpdSet is above 300PWM, control PumpSpdSet to decrease by -10PWM / timebase; when PumpSpdSet is above 100PWM and below 300PWM, control PumpSpdSet to decrease by -5PWM / timebase. Stop adjusting and shut down when the PumpSpdSet value is less than 100PWM, which is a safe condition.

7. The multi-mode dynamic regulation motor control method for urea supply in a diesel vehicle SCR system according to claim 1, characterized in that, The time base unit is configured as 1ms.

8. The multi-mode dynamic regulation motor control method for urea supply in a diesel vehicle SCR system according to claim 1, characterized in that, During closed-loop correction and gradient stop control, a pre-compensation filter is used to control and an acceleration limit for motor speed adjustment is embedded to suppress maximum instantaneous torque and mechanical impact load.

9. The multi-mode dynamic regulation motor control method for urea supply in a diesel vehicle SCR system according to claim 1, characterized in that, Controlled by a pre-compensation filter, the acceleration limit for motor speed adjustment is embedded, including: If the difference between the adjusted motor speed new_speed and the current motor speed current_speed is greater than or equal to the maximum acceleration threshold MAX_ACCEL*Δt, then the current motor speed is used as the basis, and the adjusted motor speed is obtained by adjusting it by ± the maximum acceleration threshold MAX_ACCEL*Δt. Among them, the adjusted motor speed new_speed refers to the motor speed after adjustment through step 3 or step 4 during the closed-loop correction and gradient stop control process, and current_speed refers to the current speed before the adjustment.

10. The multi-mode dynamic regulation motor control method for urea supply in a diesel vehicle SCR system according to claim 9, characterized in that, The maximum acceleration threshold MAX_ACCEL is set to 50PWM / ms.

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