Variable frequency water pump control method and system, terminal equipment and storage medium

Abstract

The invention relates to the technical field of variable frequency water pump control, and provides a variable frequency water pump control method and system, terminal equipment and a storage medium, the control method comprises the following steps: obtaining current of a water pump motor and reconstructing to obtain three-phase current; sequentially carrying out first conversion and second conversion on the three-phase current to obtain a second two-phase current, and calculating the real-time operation power of the water pump motor according to the second two-phase current; setting given power, obtaining given current of the water pump motor according to the given power and the real-time operation power, and enabling the water pump motor to operate according to the given current to enable the operation power of the water pump motor to be equal to the given power. A traditional speed ring is replaced with the power ring, output of the power ring serves as current ring input given, constant flow can be achieved without an additional pressure sensor, and the circulation requirement of a water pump system is met.

Description

Technical Field

[0001] The present invention relates to the technical field of variable frequency water pump control, and in particular to a control method, system, terminal equipment and storage medium for a variable frequency water pump. Background Art

[0002] Traditional variable frequency water pump systems usually adopt several constant speed operation modes, that is, once the set speed is determined, the water pump will run at a fixed speed. Although this design is simple, it has significant limitations in practical applications. When the pipeline pressure changes, the fixed speed water pump cannot respond quickly, resulting in unstable flow, which in turn affects the efficiency of water circulation. In addition, in the existing variable frequency water pump technology, the pipeline pressure is detected in real time through an external pressure sensor device, and the water pump speed is adjusted by the detected pipeline pressure change to achieve a constant flow, but it will increase costs.

[0003] Therefore, there is an urgent need for a water pump control method to achieve a constant flow rate without the need for an external pressure sensor to meet the circulation requirements of the water pump system. Summary of the invention

[0004] In view of the above-mentioned defects, the purpose of the present invention is to propose a control method, system, terminal device and storage medium for a variable frequency water pump, aiming to replace the traditional speed loop with a power loop, and the power loop output is given as the current loop input. Without an external pressure sensor, a constant flow rate can be achieved to meet the circulation requirements of the water pump system.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] A control method for a variable frequency water pump, the control method comprising:

[0007] Obtain the current of the water pump motor and reconstruct it to obtain the three-phase current;

[0008] The three-phase current is subjected to a first transformation and a second transformation in sequence to obtain a second two-phase current, and the real-time operating power of the water pump motor is calculated according to the second two-phase current;

[0009] The given power is set, and the given current of the water pump motor is obtained according to the given power and the real-time operating power. The water pump motor operates at the given current so that the operating power of the water pump motor is equal to the given power.

[0010] Preferably, the first transformation comprises: performing a CLARK transformation on the three-phase current values ​​to obtain a first two-phase current, wherein the first two-phase current comprises a current of an α-phase and a current of a β-phase.

[0011] Furthermore, the second transformation includes: performing PARK transformation on the first two-phase current to obtain the second two-phase current, and the second two-phase current includes Id and Iq in dq coordinates.

[0012] Preferably, the real-time operating power of the water pump motor calculated according to the second two-phase current satisfies the relationship:

[0013] P=(U d *I d +U q *I q )*K

[0014] Among them, U d and U q Represents the voltage value of the direct axis and the quadrature axis respectively, I d and I q They represent the two-phase currents in dq coordinates respectively, and K represents the calibration conversion coefficient.

[0015] Preferably, obtaining a given current of the water pump motor according to the given power and the real-time operating power includes:

[0016] Calculate the difference between the given power and the real-time operating power;

[0017] The difference is adjusted by PI to obtain a given current of the water pump motor.

[0018] A control system for a variable frequency water pump, wherein the control system applies the control method as described above, and is characterized in that it includes:

[0019] A current acquisition module is used to acquire the current of the water pump motor and reconstruct it to obtain the three-phase current;

[0020] A power calculation module, used for sequentially performing a first transformation and a second transformation on the three-phase current to obtain a second two-phase current, and calculating the real-time operating power of the water pump motor according to the second two-phase current;

[0021] The control module is used to set a given power, and obtain a given current of the water pump motor according to the given power and the real-time operating power. The water pump motor operates at the given current so that the operating power of the water pump motor is equal to the given power.

[0022] A terminal device, characterized in that the terminal device includes: a memory, a processor, and a program stored in the memory and executable on the processor, wherein the program is configured to implement the steps of the control method of the variable frequency water pump as described above.

[0023] A storage medium, characterized in that a control program for a variable frequency water pump is stored on the storage medium, and when the control program for the variable frequency water pump is executed by a processor, the steps of the control method for the variable frequency water pump as described above are implemented.

[0024] One of the above technical solutions has the following advantages or beneficial effects:

[0025] The present invention can achieve efficient operation of the water pump motor, avoid energy waste due to fixed speed, and maximize energy efficiency by automatically adjusting the current according to the actual load; the solution based on constant power control can respond to load changes more quickly, maintain stable water pump flow, and improve the adaptability of the water pump system in a dynamically changing water pump working environment; the power loop is used to replace the traditional speed loop, and the power loop output is given as the current loop input, and there is no need to rely on an external pressure sensor, which helps to reduce the complexity of the control process, reduce maintenance workload and cost, and improve the reliability of the control process. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0027] Figure 1 is a flow chart of a control method for a variable frequency water pump provided by an embodiment of the present invention;

[0028] Figure 2 It is a structural schematic diagram of a control system of a variable frequency water pump provided by an embodiment of the present invention;

[0029] Figure 3 is a specific control block diagram of the control method of the variable frequency water pump provided by an embodiment of the present invention;

[0030] Figure 4 is a relationship diagram between input power and flow rate of a variable frequency water pump control method provided by an embodiment of the present invention;

[0031] Figure 5 It is a relationship diagram between the water pump flow rate and the given power of the variable frequency water pump control method provided in the embodiment of the present invention. DETAILED DESCRIPTION

[0032] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0033] In the present invention, the terms "comprises", "comprising" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0034] Traditional variable frequency water pump systems usually adopt several constant speed operation modes, that is, once the set speed is determined, the water pump will run at a fixed speed. Although this design is simple, it has significant limitations in practical applications. When the pipeline pressure changes, the fixed speed water pump cannot respond quickly, resulting in unstable flow, which in turn affects the efficiency of water circulation. In addition, in the existing variable frequency water pump technology, the pipeline pressure is detected in real time through an external pressure sensor device, and the water pump speed is adjusted by the detected pipeline pressure change to achieve a constant flow, but it will increase costs.

[0035] Therefore, there is an urgent need for a water pump control method to achieve a constant flow rate without the need for an external pressure sensor to meet the circulation requirements of the water pump system.

[0036] The present invention proposes a control method for a variable frequency water pump, such as Figure 1 As shown, the control method comprises the steps of:

[0037] S1: Obtain the current of the water pump motor and reconstruct it to obtain the three-phase current;

[0038] S2: performing the first transformation and the second transformation on the three-phase current in sequence to obtain the second two-phase current, and calculating the real-time operating power of the water pump motor according to the second two-phase current;

[0039] S3: Set a given power, and obtain a given current of the water pump motor according to the given power and the real-time operating power. The water pump motor operates at the given current so that the operating power of the water pump motor is equal to the given power.

[0040] Specifically, Figure 5 As shown, before using this method, it is necessary to calibrate the relationship between flow and given power. When the user sets a certain flow, such as 20m 3 / h, the present invention automatically converts it into the corresponding power setting. After power closed-loop control, the operating power of the water pump motor can finally reach the given power. At the same time, the water pump flow rate can also reach the preset flow rate. The variable frequency water pump motor is a permanent magnet synchronous motor, such as Figure 3As shown in the figure, the driver board circuit samples the current of the water pump motor and inputs it into the MCU. The MCU reconstructs the current. The reconstruction process mainly filters and analyzes the current signal to obtain clear and accurate three-phase current data. It is worth noting that the reconstruction can be achieved through signal filtering (such as low-pass filter) and time domain analysis to remove high-frequency noise in the current signal. The three-phase current I u , I v and I w The characteristics of the three-phase current (such as phase difference and amplitude) have a direct impact on the power output and torque of the motor. After two transformations, a two-phase current value is obtained. The real-time operating power of the pump motor is obtained using the two-phase current value for subsequent control.

[0041] The user sets the target power (given power) according to demand. This value is usually calculated based on the workload and flow demand of the pump. The current required for the pump motor to run is calculated by combining the given power and the real-time operating power so that its output power reaches the given power.

[0042] like Figure 4 As shown, since the power and flow rate of the water pump are proportional under the same outlet pressure, in practical applications, the main goal is flow control. When the user fixes the flow rate, the controller software will automatically adjust the speed according to the change of pipeline resistance to maintain a constant flow rate.

[0043] The present invention can achieve efficient operation of the water pump motor, avoid energy waste due to fixed speed, and maximize energy efficiency by automatically adjusting the current according to the actual load; the solution based on constant power control can respond to load changes more quickly, maintain stable water pump flow, and improve the adaptability of the water pump system in a dynamically changing water pump working environment; the power loop is used to replace the traditional speed loop, and the power loop output is given as the current loop input, and there is no need to rely on an external pressure sensor, which helps to reduce the complexity of the control process, reduce maintenance workload and cost, and improve the reliability of the control process.

[0044] Preferably, the first transformation comprises: performing a CLARK transformation on the three-phase current values ​​to obtain a first two-phase current, wherein the first two-phase current comprises a current of an α-phase and a current of a β-phase.

[0045] Specifically, the purpose of Clark transformation is to convert the three-phase current I u , I v and I w, converted into the current in a two-phase stationary coordinate system (the first two-phase current). After the Clark transform converts the three-phase current into a two-phase form, current control, speed control and position control can be realized more simply, making the algorithm more efficient in implementation. In digital signal processing and control algorithms, processing two-phase signals is simpler than processing three-phase signals, and the amount of calculation is also smaller, thereby improving the response speed and processing capability of the system. In the control system, the use of two-phase current feedback can make it easier to perform state estimation and system monitoring, thereby improving the stability and control accuracy of the system.

[0046] Preferably, the second transformation comprises: performing PARK transformation on the first two-phase current to obtain the second two-phase current, wherein the second two-phase current comprises Id and Iq in dq coordinates.

[0047] Specifically, the Park transform converts the current in the stationary coordinate system (alpha phase and beta coordinate system) into the rotating coordinate system (dq coordinate system), which can make the motor control more intuitive and effective. The d-axis is aligned with the magnetic field of the motor, and the q-axis is perpendicular to the rotation direction of the motor. In the dq coordinate system, the control model of the motor becomes more linear, and the control algorithm (such as PI controller) can be more easily designed and implemented. Id and Iq correspond to the flux and torque current components of the motor, respectively, allowing direct control of the torque output and magnetic field strength of the motor, thereby improving the dynamic performance of the motor. By controlling the current in the dq coordinate system, the motor operation state can be optimized, the overall efficiency can be improved, and the system response time can be reduced.

[0048] Preferably, the real-time operating power of the water pump motor calculated according to the second two-phase current satisfies the relationship:

[0049] P=(U d *I d +U q *I q )*K

[0050] Among them, U d and U q Represents the voltage value of the direct axis and the quadrature axis respectively, I d and I q They represent the two-phase currents in dq coordinates respectively, and K represents the calibration conversion coefficient.

[0051] Specifically, U d and U q They represent the direct-axis voltage value (aligned with the motor magnetic field) and the quadrature-axis voltage value (perpendicular to the motor rotation direction), respectively. d and U q All are obtained by the current loop PI calculation, I d is the direct axis current in dq coordinates, I qis the quadrature-axis current in the dq coordinate system, K is the calibration conversion coefficient, and the calibration is performed according to the actual instrument detection power.

[0052] Preferably, obtaining a given current of the water pump motor according to the given power and the real-time operating power includes:

[0053] Calculate the difference between the given power and the real-time operating power;

[0054] The difference is adjusted by PI to obtain a given current of the water pump motor.

[0055] Specifically, the real-time operating power is subtracted from the given power to obtain a difference, which represents the deviation between the actual motor power and the target power. The PI regulation includes a proportional part and an integral part. The proportional part multiplies the difference by the proportional gain (an adjustment parameter) to obtain a part of the adjustment amount. The integral part calculates the integral of the difference over time, which represents the cumulative effect of the difference over a period of time, and then multiplies it by the integral gain (another adjustment parameter). The proportional part and the integral part are added together to obtain a new given current value. The new given current value will be used to adjust the motor to ensure that its operating power is close to the given power.

[0056] A control system for a variable frequency water pump, such as Figure 2 As shown, the control system applies the control method as described above, including:

[0057] The current acquisition module 1 is used to acquire the current of the water pump motor and reconstruct it to obtain the three-phase current;

[0058] A power calculation module 2 is used to perform a first transformation and a second transformation on the three-phase current in sequence to obtain a second two-phase current, and calculate the real-time operating power of the water pump motor according to the second two-phase current;

[0059] The control module 3 is used to set a given power, and obtain a given current of the water pump motor according to the given power and the real-time operating power. The water pump motor operates at the given current so that the operating power of the water pump motor is equal to the given power.

[0060] This embodiment realizes a control method and implementation process of a variable frequency water pump. Please refer to the above embodiments and will not be described in detail here.

[0061] In addition, an embodiment of the present invention further proposes a terminal device, which includes a memory, a processor, and a program stored in the memory and executable on the processor, wherein the program is configured to implement the steps of the variable frequency water pump control method as described above.

[0062] Since the program is configured to implement the steps of the control method of the variable frequency water pump as described above, the program at least has all the beneficial effects brought about by all the technical solutions of all the aforementioned embodiments, which will not be described one by one here.

[0063] In addition, an embodiment of the present application also proposes a computer-readable storage medium, on which a control program for a variable frequency water pump is stored. When the control program for the variable frequency water pump is executed by a processor, the steps of the control method for the variable frequency water pump as described above are implemented.

[0064] Since all the technical solutions of all the aforementioned embodiments are adopted when the control program of the variable frequency water pump is executed by the processor, it has at least all the beneficial effects brought by all the technical solutions of all the aforementioned embodiments, which will not be described one by one here.

[0065] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0066] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A control method for a variable frequency water pump, characterized in that: The control method comprises: Obtain the current of the water pump motor and reconstruct it to obtain the three-phase current; The three-phase current is subjected to a first transformation and a second transformation in sequence to obtain a second two-phase current, and the real-time operating power of the water pump motor is calculated according to the second two-phase current; The given power is set, and the given current of the water pump motor is obtained according to the given power and the real-time operating power. The water pump motor operates at the given current so that the operating power of the water pump motor is equal to the given power.

2. The control method according to claim 1, characterized in that: The first transformation includes: performing a CLARK transformation on the three-phase current values ​​to obtain a first two-phase current, wherein the first two-phase current includes currents of the α phase and the β phase.

3. The control method according to claim 2, characterized in that: The second transformation includes: performing PARK transformation on the first two-phase current to obtain the second two-phase current, where the second two-phase current includes Id and Iq in dq coordinates.

4. The control method according to claim 1, characterized in that: The real-time operating power of the water pump motor calculated based on the second two-phase current satisfies the relationship: P=(U d *AND d +U q *AND q )*K Among them, U d and U q Represents the voltage value of the direct axis and the quadrature axis respectively, I d and I q They represent the two-phase currents in dq coordinates respectively, and K represents the calibration conversion coefficient.

5. The control method according to claim 1, characterized in that: The given current of the water pump motor obtained based on the given power and real-time operating power includes: Calculate the difference between the given power and the real-time operating power; The difference is adjusted by PI to obtain a given current of the water pump motor.

6. A control system for a variable frequency water pump, the control system applying the control method according to any one of claims 1 to 5, characterized in that: include: A current acquisition module is used to acquire the current of the water pump motor and reconstruct it to obtain the three-phase current; A power calculation module, used for sequentially performing a first transformation and a second transformation on the three-phase current to obtain a second two-phase current, and calculating the real-time operating power of the water pump motor according to the second two-phase current; The control module is used to set a given power, and obtain a given current of the water pump motor according to the given power and the real-time operating power. The water pump motor operates at the given current so that the operating power of the water pump motor is equal to the given power.

7. A terminal device, characterized in that: The terminal device comprises: a memory, a processor, and a program stored in the memory and executable on the processor, wherein the program is configured to implement the steps of the control method of the variable frequency water pump according to any one of claims 1 to 5.

8. A storage medium, characterized in that: The storage medium stores a control program for a variable frequency water pump, and when the control program for the variable frequency water pump is executed by a processor, the steps of the control method for a variable frequency water pump as described in any one of claims 1 to 5 are implemented.

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