A constant pressure water supply control method for a water pump

Abstract

The present invention belongs to the technical field of water pumps, and particularly refers to a method for controlling constant pressure water supply of a water pump, comprising the following steps: S1, initializing a single chip microcomputer, setting a constant D, a sampling frequency f s , rated water pressure value p0; S2, handle other tasks of water pump control; S3, detect current water pressure value p c ; S4, remove the oldest data from the cache and set the current water pressure value p c Fill in; S5, calculate the window size n according to the formula; S6, calculate the weighted cumulative sum p of the water pressure difference between the water pressure value in the window and the rated water pressure value p0 according to the formula; S7, calculate the speed adjustment Δv according to the formula; S8, calculate and output the current speed value v according to the formula i , return to step S2. The present invention does not require tuning, that is, it does not require experienced personnel to complete the tuning.

Description

Technical Field

[0001] The invention belongs to the technical field of water pumps, and in particular relates to a constant-pressure water supply control method for a water pump. Background Art

[0002] A Chinese invention patent (publication number CN106438311B, application date 2016.08.31, publication date 2018.09.21) discloses an intelligent controller for a variable frequency constant pressure water supply pump, which includes an MCU module, an A / D converter, a D / A converter, a real-time clock module, an operation monitoring module, a fault alarm module, a power supply module, a parameter setting module, a data storage module, a relay output module, and a PI regulator. The A / D converter receives the pressure value of the water supply outlet, compares the received pressure value with the set value in the parameter setting module, and performs calculations through the PI regulator. The calculation results are output through the D / A converter. A 0-10V voltage signal is output to control the speed of the water pump. The intelligent controller of the variable frequency constant pressure water supply pump determines the operating status of each water pump through the relay output module according to the speed of the water pump, the collected outlet pressure and the real-time clock module to achieve the purpose of constant pressure water supply. When low liquid level, underpressure, overpressure or inverter failure occurs in the municipal pipe network, the intelligent controller of the variable frequency constant pressure water supply pump outputs an alarm signal through the fault alarm module through the relay output module. The parameter setting module sets a series of parameters required for system operation and saves the set parameters to the non-volatile memory EEPROM of the MCU module through the data storage module.

[0003] The above-mentioned intelligent controller for variable frequency constant pressure water supply pump has the following shortcomings: constant pressure control is performed using PI regulator, and PI parameters need to be adjusted according to different water pump systems. After the system changes, the parameters need to be readjusted, which is difficult for inexperienced people to complete. Summary of the Invention

[0004] The object of the present invention is to provide a method for controlling constant-pressure water supply of a water pump, which does not require any setting, ie, does not require experienced personnel to complete the setting.

[0005] The present invention is achieved in that:

[0006] A method for controlling constant pressure water supply of a water pump comprises the following steps:

[0007] S1. Initialize the microcontroller and set the constant D and sampling frequency f. s , rated water pressure value p0;

[0008] S2, handle other tasks of water pump control;

[0009] S3, detect the current water pressure value p c ;

[0010] S4, remove the oldest data in the cache and set the current water pressure value p c Fill in;

[0011] S5. According to the formula , calculate the window size n;

[0012] S6. According to the formula and formula , calculate the weighted cumulative sum p of the water pressure difference between the water pressure value in the window and the rated water pressure value p0;

[0013] S7, according to the formula , calculate the speed adjustment Δv;

[0014] S8, according to the formula , calculate and output the current speed value v i , return to step S2.

[0015] In the above-mentioned constant-pressure water supply control method for a water pump, in step S1, the rated speed v0 and the percentage α are set; in step S7, the speed adjustment amount Δv is limited. When the calculated speed adjustment amount Δv is less than the product of the rated speed v0 and the percentage α, the speed adjustment amount Δv is a value calculated according to the formula of step S7; when the calculated speed adjustment amount Δv is greater than or equal to the product of the rated speed v0 and the percentage α, the product of the rated speed v0 and the percentage α is assigned to the speed adjustment amount Δv.

[0016] In the above-mentioned constant-pressure water supply control method for a water pump, in step S5, the value calculated according to the formula needs to be an integer.

[0017] In the above-mentioned water pump constant pressure water supply control method, the window size n can be taken as an integer by rounding the calculated value to five, discarding the decimal places of the calculated value, or discarding the decimal places of the calculated value and adding 1 to the integer value of the calculated value.

[0018] In the above-mentioned constant pressure water supply control method of a water pump, in step S3, the current water pressure value p is detected by the pressure sensor. c The ADC module inside the microcontroller detects the current water pressure value p c The signal is converted to obtain the current water pressure value p c The corresponding ADC value.

[0019] In the above-mentioned constant pressure water supply control method of a water pump, in step S4, at the beginning, there is no valid data in the buffer area, and the first current water pressure value p to be detected is required. c Fill the buffer.

[0020] In the above-mentioned constant-pressure water supply control method for a water pump, in step S6, the data in the window are weighted according to the order of precedence, and the newer the data, the greater the weight.

[0021] The advantages of the present invention compared to the prior art are:

[0022] The present invention uses a sliding window for sampling, adaptively adjusting the window size based on current water pressure changes. The data within the window is weighted according to precedence, and the calculated result is directly used to adjust the current speed. This eliminates the need for complex PI tuning and provides a simple calculation process suitable for single-chip microcomputer calculations. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a control flow chart of the present invention. DETAILED DESCRIPTION

[0024] The present invention will be further described below with reference to specific embodiments. Figure 1 :

[0025] A method for controlling constant pressure water supply of a water pump comprises the following steps:

[0026] S1. Initialize the microcontroller and set the constant D and sampling frequency f. s , rated water pressure value p0;

[0027] S2, handle other tasks of water pump control;

[0028] S3, detect the current water pressure value p c ;

[0029] S4, remove the oldest data in the cache and set the current water pressure value p c Fill in;

[0030] S5. According to the formula , calculate the window size n;

[0031] S6. According to the formula and formula , calculate the weighted cumulative sum p of the water pressure difference between the water pressure value in the window and the rated water pressure value p0;

[0032] S7, according to the formula , calculate the speed adjustment Δv;

[0033] S8, according to the formula , calculate and output the current speed value v i , return to step S2.

[0034] The present invention uses a sliding window for sampling, adaptively adjusting the window size based on current water pressure changes. The data within the window is weighted according to precedence, and the calculated result is directly used to adjust the current speed. This eliminates the need for complex PI tuning and provides a simple calculation process suitable for single-chip microcomputer calculations.

[0035] The method provided by the present invention does not require setting and operates adaptively, and is suitable for occasions where the requirements for constant water pressure control are not too high.

[0036] In the present invention, the sampling frequency f s To detect the current water pressure value p c The frequency, usually the sampling frequency f s is 25-50Hz.

[0037] The rated water pressure value p0 is the set water pressure value, that is, the water pressure value to be controlled and maintained.

[0038] The appropriate value of constant D is determined through experiments. The constant D of water pumps of the same model is the same and is generally less than 1. The value of constant D can be adjusted so that the water pump does not have obvious speed oscillation.

[0039] The window size n is the number of data involved in the calculation. The window size n is determined by the most recently obtained current water pressure value p c The water pressure difference with the rated water pressure value p0 is determined. The larger the water pressure difference, the smaller the window is, so as to respond quickly to large deviations.

[0040] p i is the water pressure value in the window, i is the sequence number of the data, and the numbering starts from the oldest data.

[0041] K i is the weighting coefficient, which is calculated in order from old to new. The newer the data, the larger the weighting coefficient.

[0042] In step S8, v i is the current speed value, v i-1 The speed value output last time.

[0043] To prevent significant pump speed oscillation caused by excessive speed adjustment Δv, the rated speed v0 and percentage α are set in step S1. In step S7, the speed adjustment Δv is limited. When the calculated speed adjustment Δv is less than the product of the rated speed v0 and percentage α, the speed adjustment Δv is the value calculated according to the formula in step S7. When the calculated speed adjustment Δv is greater than or equal to the product of the rated speed v0 and percentage α, the product of the rated speed v0 and percentage α is assigned to the speed adjustment Δv. In this embodiment, percentage α is 10%.

[0044] Furthermore, in step S5, the value calculated according to the formula needs to be an integer.

[0045] The window size n may be rounded up to an integer by rounding the calculated value, discarding the decimal places of the calculated value, or discarding the decimal places of the calculated value and then adding 1 to the integer value of the calculated value. In this embodiment, the window size n is rounded up to an integer by discarding the decimal places of the calculated value.

[0046] Current water pressure value p c Detection method: In step S3, the current water pressure value p is detected by the pressure sensor. c The ADC module inside the microcontroller detects the current water pressure value p c The signal is converted to obtain the current water pressure value p c The corresponding ADC value.

[0047] Each time the ADC value is stored in a buffer, after obtaining a new ADC value, the data in the buffer is shifted one position toward the old data, the oldest data is removed, and the current ADC value is filled in. In this way, the buffer always saves the ADC values ​​of the most recent period (corresponding to the pressure value) in order.

[0048] Furthermore, the buffer size must exceed the maximum window size n.

[0049] Furthermore, in step S4, there is no valid data in the buffer at the beginning, and the first current water pressure value p c Fill the buffer.

[0050] Furthermore, in step S6, the data in the window are weighted according to the order of precedence, and the newer the data, the greater the weight.

[0051] The above embodiment is only one of the preferred embodiments of the present invention and is not intended to limit the scope of implementation of the present invention. Therefore, any equivalent changes made based on the shape, structure, and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for controlling constant pressure water supply of a water pump, characterized by: The following steps are involved: S1. Initialize the microcontroller and set the constant D and sampling frequency f. s , rated water pressure value p0; S2, handle other tasks of water pump control; S3, detect the current water pressure value p c ; S4, remove the oldest data in the cache and set the current water pressure value p c Fill in; S5. According to the formula Calculate the window size n; S6. According to the formula and formula Calculate the weighted cumulative sum p of the water pressure difference between the water pressure value in the window and the rated water pressure value p0; S7, according to the formula Calculate the speed adjustment Δv; S8, according to formula v i =v i-1 +Δv, calculate and output the current speed value v i , return to step S2; In step S1, the rated speed v0 and the percentage α are set; in step S7, the speed adjustment Δv is limited. When the calculated speed adjustment Δv is less than the product of the rated speed v0 and the percentage α, the speed adjustment Δv is the value calculated according to the formula in step S7; when the calculated speed adjustment Δv is greater than or equal to the product of the rated speed v0 and the percentage α, the product of the rated speed v0 and the percentage α is assigned to the speed adjustment Δv. In step S6, the data in the window are weighted according to the order of precedence, and the newer the data, the greater the weight.

2. A water pump constant pressure water supply control method according to claim 1, characterized in that: In step S5, the value calculated according to the formula needs to be an integer.

3. A water pump constant pressure water supply control method according to claim 1, characterized in that: In step S3, the current water pressure value p is detected by the pressure sensor. c The ADC module inside the microcontroller detects the current water pressure value p c The signal is converted to obtain the current water pressure value p c The corresponding ADC value.

4. A water pump constant pressure water supply control method according to claim 1, characterized in that: In step S4, there is no valid data in the buffer at the beginning, and the first current water pressure value p is needed to be detected. c Fill the buffer.

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