Method for inhibiting rotating speed fluctuation of water pump controller

Abstract

The invention discloses a method for inhibiting rotating speed fluctuation of a water pump controller, which can accurately identify core fluctuation sources such as crankshaft excitation and transmission errors, adopts a layered inhibition strategy, performs differential control on different fluctuation factors, and compared with a traditional single control method, the method has the advantages that the rotating speed fluctuation inhibition rate is greatly improved, and the rotating speed fluctuation amplitude of a water pump can be controlled to be extremely small.

Description

Technical Field

[0001] This invention belongs to the field of water pump drive control technology, and relates to a method for suppressing speed fluctuations in a water pump controller. Background Technology

[0002] Pumps are the core components of cooling systems in power equipment, and their operational stability directly determines the reliability of the equipment. In heavy-duty equipment such as large-bore diesel engines, water pumps are often connected to the crankshaft via gears or belts. During operation, their speed is easily affected by various factors, causing fluctuations: on the one hand, the forced excitation of the crankshaft is the main energy source for speed fluctuations, and crankshaft torsional vibration is directly transmitted to the water pump through the transmission mechanism; on the other hand, transmission errors in gear drives (including static errors caused by manufacturing and installation and dynamic errors caused by changes in operating conditions) and differences in transmission loads further exacerbate speed fluctuations.

[0003] Existing methods for suppressing pump speed fluctuations have significant shortcomings: First, traditional control methods mostly focus on optimizing the internal flow field of the pump, ignoring key influencing factors such as external transmission excitation and load disturbances, resulting in limited suppression effectiveness; Second, existing suppression strategies are mostly fixed parameter controls, which cannot adaptively adjust according to the dynamic characteristics of speed fluctuations, have poor adaptability to different transmission methods (gear / belt) and different operating conditions, and have low portability; Third, some solutions achieve fluctuation suppression through mechanical structure modification (such as replacing gears with belts), but the modification cost is high and cannot solve the problem of real-time suppression of dynamic fluctuations during operation.

[0004] Therefore, there is an urgent need for a controller-based active suppression method that can accurately suppress pump speed fluctuations by identifying the source of fluctuations in real time and dynamically adjusting the control strategy, while improving the versatility and portability of the control scheme. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention provides a method for suppressing speed fluctuations in a water pump controller.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for suppressing speed fluctuations in a water pump controller includes the following steps: Step 1: Collect multi-source signals, including instantaneous pump speed, crankshaft speed, drive end current, bus voltage and transmission mechanism load pressure signal, preprocess the multiple signals using a differentiated filtering strategy, and calculate the speed fluctuation value; Step 2: Calibrate the reference threshold for speed fluctuation and dynamically correct it according to the working conditions. Combine the proportion of specific order fluctuation components of the crankshaft to make a dual-condition judgment and output the result of normal operation mode or fluctuation suppression mode. Step 3: Execute differentiated control based on the mode determination result. In normal operation mode, conventional PID regulation and disturbance warning are used. In fluctuation suppression mode, crankshaft excitation compensation, transmission error adaptive compensation, and power balance optimization are used in sequence to suppress fluctuations in layers, and compensation signals are output. Step 4: Synthesize the compensation signal to drive the water pump actuator, collect feedback speed in real time to calculate the new speed fluctuation value, and switch the mode or iteratively optimize the control parameters according to whether the new speed fluctuation value meets the standard.

[0007] Furthermore, the multi-source signal acquisition in step 1 satisfies the following requirements: synchronous acquisition of instantaneous pump speed, crankshaft speed, drive end current, bus voltage, and transmission mechanism load pressure signals.

[0008] Furthermore, the preprocessing in step 1 includes: applying Kalman filtering to the instantaneous pump speed and crankshaft speed, applying first-order low-pass filtering to the load pressure signal and drive end current, and applying mean filtering to the bus voltage signal.

[0009] Furthermore, the threshold dynamic correction in step 2 includes: real-time acquisition of bus voltage stability and load pressure stability; if bus voltage or load pressure is detected to be unstable, the speed fluctuation reference threshold is automatically increased.

[0010] Furthermore, in step 2, the crankshaft specific order fluctuation component is the crankshaft 5th order fluctuation component, which is extracted from the preprocessed speed fluctuation value and crankshaft speed signal through FFT transformation.

[0011] Furthermore, crankshaft excitation compensation includes: extracting the amplitude and phase characteristics of specific order fluctuation components of the crankshaft, calculating the reverse compensation amount based on these characteristics, and ensuring that the compensation current is in the opposite phase to the crankshaft torsional vibration.

[0012] Furthermore, in the adaptive compensation of transmission error, the current transmission type is identified by pre-stored water pump configuration parameters or transmission mechanism characteristic signals.

[0013] Furthermore, power balance optimization includes: calculating the actual output power of the water pump based on the collected drive end current and bus voltage signals, comparing it with the preset ideal power to obtain the power difference; converting the power difference into speed compensation amount to correct the target speed of PID regulation.

[0014] In summary, the advantages of this invention are: This invention can accurately identify core fluctuation sources such as crankshaft excitation and transmission error, and adopts a layered suppression strategy to implement differentiated control for different fluctuation factors. Compared with the traditional single control method, the speed fluctuation suppression rate is greatly improved, and the pump speed fluctuation amplitude can be controlled to a minimum.

[0015] It is compatible with both gear and belt transmission methods and features adaptive mode adjustment, eliminating the need to redesign control logic based on transmission type. Control parameters are obtained through theoretical tuning, without relying on specific water pump model parameters, greatly improving portability and making it suitable for water pumps with different cylinder diameters and power levels.

[0016] Simultaneously, the introduction of multi-stage signal preprocessing and real-time feedback adjustment can effectively cope with dynamic operating conditions such as sudden load changes and aging of transmission mechanisms, and avoid secondary fluctuations caused by the lag of suppression strategies. Attached Figure Description

[0017] Figure 1 This is a flowchart of the method for suppressing speed fluctuations in a water pump controller according to the present invention. Detailed Implementation

[0018] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0019] This invention provides a method for suppressing speed fluctuations in a water pump controller, comprising the following steps: Step 1: Multi-source signal acquisition and hierarchical preprocessing.

[0020] Step 1.1, Sensor deployment and signal acquisition.

[0021] An electromagnetic speed sensor is installed at the output shaft end of the water pump to collect the instantaneous speed of the water pump. A speed sensor is installed at the crankshaft end of the diesel engine to collect the crankshaft speed. A current sensor is connected in series and a voltage sensor is connected in parallel in the water pump drive circuit to collect the drive end current and bus voltage. A pressure sensor is installed at the load stress point of the water pump transmission mechanism (e.g., at the gearbox or pulley) to collect the load pressure. All sensor signals are collected synchronously and transmitted to the signal acquisition module of the controller to ensure that the data timestamps are consistent.

[0022] Step 1.2: Signal layering preprocessing.

[0023] Differentiated filtering strategies are adopted for different types of signals based on their noise characteristics.

[0024] Kalman filtering is used to process speed signals (such as instantaneous pump speed and crankshaft speed), with initial filter parameters Q=0.01 and R=0.1 to eliminate high-frequency noise caused by electromagnetic interference and mechanical vibration. The load pressure signal and drive current signal are processed by a first-order low-pass filter with a cutoff frequency of 10Hz to smooth out instantaneous spikes in the signal. The bus voltage signal is processed by mean filtering, and the mean of 5 consecutive sampling points is taken as the effective voltage value.

[0025] Step 1.3: Calculation of basic fluctuation parameters.

[0026] Based on the preprocessed instantaneous pump speed signal, the average speed is calculated using the sliding window method, where the window size is set to 100ms and is updated in real time as the window slides. Speed ​​fluctuation values ​​are also calculated. , =|Instantaneous speed - Average speed|.

[0027] Step 2: Fluctuation pattern recognition and dynamic threshold determination.

[0028] Step 2.1, benchmark threshold calibration.

[0029] The speed fluctuation benchmark threshold was determined through offline testing. The initial calibration range is 5-20 r / min, based on the rated speed of the water pump and the accuracy requirements of the operating conditions. At the same time, the threshold for the proportion of crankshaft order fluctuation component is preset to 30%, which serves as an auxiliary judgment basis.

[0030] Step 2.2, Dynamic threshold correction.

[0031] The controller collects real-time data on bus voltage stability and load pressure stability. If it detects instability in either the bus voltage or load pressure, it automatically adjusts the settings accordingly. Increase by 10%-20% to avoid misjudgment of the mode due to sudden changes in external operating conditions.

[0032] Step 2.3: Fluctuation pattern determination.

[0033] Based on the output of step 1 First, the crankshaft speed signal is used to extract the fifth-order crankshaft oscillation component through FFT transformation, and its proportion is calculated; then, it is combined with the corrected signal. Perform a two-condition judgment: Condition one is < Condition 2 is that the proportion of the fifth-order oscillation component of the crankshaft is less than 30%; when both conditions are met, it is determined to be in normal operation mode; when either condition is not met, it is determined to be in oscillation suppression mode; the determination result is transmitted to the control strategy execution module in real time.

[0034] The method for determining the normal operating mode is as follows: only when both "speed fluctuation value does not exceed the threshold" and "crankshaft fluctuation ratio is low" are met, it indicates that the water pump is operating stably and there is no need to start the enhanced suppression strategy. Stability can be maintained by using conventional control.

[0035] Fluctuation suppression mode judgment logic: If either "speed fluctuation exceeds the threshold" or "crankshaft excitation ratio is high" exists, it means that the pump speed stability no longer meets the requirements, and a layered enhanced suppression strategy needs to be activated to specifically offset the impact of the fluctuation source.

[0036] Step 3: Execute the hierarchical suppression strategy.

[0037] Based on the mode determination result in step 2, differentiated control strategies are implemented in two modes. The two modes share the same set of actuator interfaces to ensure smooth and shock-free switching.

[0038] Step 3.1, Normal Operation Mode Control Flow.

[0039] Initialization using conventional PID parameters: Load the preset conventional PID parameters, and use the average speed calculated in step 1 as the temporary target speed to construct a speed-current closed-loop regulation.

[0040] Real-time fine-tuning and disturbance warning: The pump maintains stable speed by adjusting the PWM duty cycle of the pump drive current; at the same time, the load pressure signal of the transmission mechanism is monitored in real time, and the pressure change warning threshold is set to 10% of the rated pressure. When a pressure change is detected, the temporary filter enhancement module is activated, the low-pass filter cutoff frequency is lowered to 5Hz, and the PID proportional coefficient is temporarily reduced by 20% to avoid instantaneous speed fluctuations caused by load disturbances; if the pressure recovers and the duration is ≥1s, the temporary filter enhancement mode is automatically exited and the initial PID parameters are restored.

[0041] Step 3.2, Fluctuation Suppression Mode Control Process.

[0042] Control parameter switching: Automatically load the PID basic parameters exclusive to the fluctuation suppression mode. Compared with the normal mode, the proportional constant Kp is increased by 30%, the integral constant Ki is decreased by 20%, and the derivative constant Kd is increased by 50%. At the same time, three parallel suppression sub-modules are started, and the compensation signals are output in priority order.

[0043] The first priority is crankshaft excitation compensation to counteract the main vibration source. The compensation amount is calculated based on the crankshaft speed signal preprocessed in step 1. The amplitude and phase of the fifth-order crankshaft vibration component are extracted and input into the PI control unit to calculate the torsional vibration compensation current ΔI1. The PI control unit parameters are theoretically tuned to obtain reference values, where the proportional coefficient k1 = 0.002-0.003, the integral coefficient k2 = 3-5, and k1 is dynamically adjusted according to the magnitude of Δn. The larger Δn is, the more k1 is adjusted, with a maximum adjustment of 50%. Compensation is then performed by superimposing ΔI1 onto the water pump drive current reference value. The superposition method of "reference current + ΔI1 × phase correction coefficient" is used to achieve reverse cancellation of the crankshaft excitation. The phase correction coefficient is calculated based on the transmission ratio between the crankshaft and the water pump to ensure that the compensation current is out of phase with the crankshaft torsional vibration.

[0044] The second priority is adaptive compensation for transmission errors to counteract secondary fluctuation sources. The controller automatically identifies the current transmission type as gear or belt based on pre-stored pump configuration parameters or real-time monitored transmission mechanism characteristic signals, such as the periodic tooth frequency signal present in gear drives. If it is a gear drive, the three-phase drive current is decomposed into d / q-axis components using Clark-Park transformation, with the d-axis representing the excitation component and the q-axis representing the torque component. A PR controller is used to fine-tune the q-axis current component, and the PR controller's resonant frequency... Track the gear tooth frequency signal. =2π × tooth frequency, cutoff frequency =5Hz, the gear transmission error is offset by accurately compensating the torque component; if it is a belt drive, the belt tension-related voltage signal is monitored in real time. When the belt tension decreases, the driving voltage of the tensioning mechanism increases. The voltage compensation amount ΔU = ideal voltage - actual monitored voltage is calculated. By adjusting the bus voltage stability value of the drive circuit, ΔU is compensated to the drive circuit to suppress the speed fluctuation caused by the elastic deformation of the belt.

[0045] The third priority is power balance optimization to further stabilize the speed. Based on the PIR control logic, the actual output power P of the pump is calculated using the drive end current and bus voltage signals acquired in step 1. Where cosφ is the power factor, preset to 0.85 based on the pump motor parameters; ideal power Based on the preset rated speed and head requirements of the water pump, the power difference is calculated. The power-speed mapping relationship (based on offline calibration of the pump characteristic curve) is used to convert ΔP into a speed compensation value. (When ΔP is positive, When ΔP is negative, the target speed is reduced; when ΔP is negative, If the target speed is positive, the target speed is increased. Δn1 is then superimposed on the initial target speed, and the corrected target speed is used as a new benchmark for PID control, achieving dynamic balance between power and speed and reducing residual fluctuations.

[0046] Step 4: Perform iterative adjustment of output and feedback.

[0047] Step 4.1: Adjust signal synthesis and execution.

[0048] The compensation signals output by each suppression submodule in step 3 are combined. The signals include the drive current reference value, ΔI1, voltage compensation amount ΔU, and corrected target speed. The analog control signal is output through the DA conversion module of the controller, or the digital control signal is output through the PWM module to the water pump drive module. The drive module adjusts the power output according to the control signal and controls the water pump actuator to operate.

[0049] Step 4.2: Feedback signal acquisition and effect judgment.

[0050] The instantaneous speed signal of the adjusted water pump is collected in real time with a period of 10ms. The collection path is the same as in step 1 to ensure data consistency. The calculation method in step 1.3 is repeated to obtain the new speed fluctuation value Δn'.

[0051] Step 4.3: Mode switching and parameter iteration.

[0052] If Δn' < the corrected If the duration of this state is ≥2s, it indicates that the fluctuation suppression effect meets the standard, and the controller automatically switches back to the normal operation mode and loads the normal mode PID parameters. If Δn' ≥ the corrected This indicates that the current suppression parameters have not reached the optimal level, and the fluctuation suppression mode should be maintained.

[0053] To maintain the fluctuation suppression mode, adjust the PI / PR controller parameters proportionally.

[0054] If Δn' > Δn, it means that the fluctuation is greater after adjustment, so the parameter should be adjusted in the opposite direction; If Δn' < Δn but does not meet the standard, continue fine-tuning in the same direction; repeat the hierarchical suppression in step 3.2 and the feedback judgment process in this step until Δn' meets the requirements; Parameter adjustment records are stored in real time to form a working condition parameter library, which can be directly called when encountering the same working condition in the future, thus improving adjustment efficiency.

[0055] Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

Claims

1. A method for suppressing speed fluctuations in a water pump controller, characterized in that, Includes the following steps: Step 1: Collect multi-source signals, including instantaneous pump speed, crankshaft speed, drive end current, bus voltage and transmission mechanism load pressure signal, preprocess the multiple signals using a differentiated filtering strategy, and calculate the speed fluctuation value; Step 2: Calibrate the reference threshold for speed fluctuation and dynamically correct it according to the working conditions. Combine the proportion of specific order fluctuation components of the crankshaft to make a dual-condition judgment and output the result of normal operation mode or fluctuation suppression mode. Step 3: Execute differentiated control based on the mode determination result. In normal operation mode, conventional PID regulation and disturbance warning are used. In fluctuation suppression mode, crankshaft excitation compensation, transmission error adaptive compensation, and power balance optimization are used in sequence to suppress fluctuations in layers, and compensation signals are output. Step 4: Synthesize the compensation signal to drive the water pump actuator, collect feedback speed in real time to calculate the new speed fluctuation value, and switch the mode or iteratively optimize the control parameters according to whether the new speed fluctuation value meets the standard.

2. The method for suppressing speed fluctuations in a water pump controller according to claim 1, characterized in that, The multi-source signal acquisition in step 1 satisfies the following requirements: synchronous acquisition of instantaneous pump speed, crankshaft speed, drive end current, bus voltage, and transmission mechanism load pressure signals.

3. The method for suppressing speed fluctuations in a water pump controller according to claim 2, characterized in that, The preprocessing in step 1 includes: using Kalman filtering to process the instantaneous speed of the water pump and the crankshaft speed, using first-order low-pass filtering to process the load pressure signal and the drive end current, and using mean filtering to process the bus voltage signal.

4. The method for suppressing speed fluctuations in a water pump controller according to claim 1, characterized in that, Step 2, the dynamic threshold correction, includes: real-time acquisition of bus voltage stability and load pressure stability; if bus voltage or load pressure is detected to be unstable, the speed fluctuation reference threshold is automatically increased.

5. A method for suppressing speed fluctuations in a water pump controller according to claim 1, characterized in that, In step 2, the crankshaft specific order fluctuation component is the crankshaft 5th order fluctuation component, which is extracted from the preprocessed speed fluctuation value and crankshaft speed signal through FFT transformation.

6. A method for suppressing speed fluctuations in a water pump controller according to claim 1, characterized in that, Crankshaft excitation compensation includes: extracting the amplitude and phase characteristics of specific order fluctuation components of the crankshaft, calculating the reverse compensation amount based on these characteristics, and ensuring that the compensation current is in the opposite phase to the crankshaft torsional vibration.

7. A method for suppressing speed fluctuations in a water pump controller according to claim 1, characterized in that, In the adaptive compensation of transmission error, the current transmission type is identified by pre-stored water pump configuration parameters or transmission mechanism characteristic signals.

8. A method for suppressing speed fluctuations in a water pump controller according to claim 1, characterized in that, Power balance optimization includes: calculating the actual output power of the water pump based on the collected drive end current and bus voltage signals, comparing it with the preset ideal power to obtain the power difference; converting the power difference into speed compensation amount to correct the target speed of PID regulation.

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