Variable frequency controller for water pump

Abstract

The invention discloses a water pump frequency conversion controller, and belongs to the technical field of electrical variable or magnetic variable regulation, the water pump frequency conversion controller is configured with a water pump motor state control model, and a control method of the water pump frequency conversion controller comprises the following steps: step 1, receiving a water pump operation mode and a lift target value set by a user, and controlling a water pump motor to start, the water pump motor reaches the set rotating speed; 2, the water pump motor state control model calculates corresponding lift and flow velocity according to the current rotating speed, and the lift and the flow velocity are a lift calculated value and a flow velocity calculated value respectively; and thirdly, the lift calculated value is compared with the lift target value, and the rotating speed of a water pump motor is adjusted according to the comparison result and the water pump operation mode. According to the water pump frequency conversion controller, the configured water pump motor state control model can calculate the corresponding lift calculated value according to the rotating speed of the water pump motor, a flow sensor and a pressure sensor do not need to be arranged, and then a series of problems caused by arrangement of the sensor can be avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrical variable or magnetic variable regulation, and specifically relates to a variable frequency controller for a water pump. Background Art

[0002] In the prior art, in the application of water pumps, asynchronous motors are mostly used to fix the flow rate, or asynchronous motors are combined with general variable frequency drives and sensors to control the head and flow rate. As Figure 1 shown, it is necessary to add a flow sensor, an inlet pressure sensor, and an outlet pressure sensor in the pipeline. By collecting the data in the sensors, the head and flow rate data are calculated. In the application of water pumps, this will bring complex system installation work, and it is necessary to cut off the original pipeline to add sensor devices. In the case of different pipeline diameters and pump head models, it is necessary to evaluate different sensor ranges and installation specifications. This brings complex system installation work to the application of water pumps, and also brings huge installation construction and maintenance costs.

[0003] The above information disclosed in this background art is only used to increase the understanding of the background art of the present application. Therefore, it may include prior art that is not known to those of ordinary skill in the art. Summary of the Invention

[0004] In the prior art, for the variable frequency control of water pumps, it is necessary to set a flow sensor, a pressure sensor, etc. in the pipeline, and calculate and control the head, flow rate, etc. according to the data collected by the sensors. The hardware cost is high, and due to factors such as the sensor model, there are huge installation construction and maintenance costs.

[0005] To achieve the above invention / design purpose, the present invention adopts the following technical solutions: A variable frequency controller for a water pump, the variable frequency controller for a water pump is used to be connected to a water pump, the variable frequency controller for a water pump is configured with a water pump motor state control model, and the control method of the variable frequency controller for a water pump includes: Step 1, receiving the water pump operation mode and the head target value set by the user, controlling the start of the water pump motor until the water pump motor reaches the set speed; Step 2, the water pump motor state control model calculates the corresponding head and flow rate according to the current speed, which are the head calculation value and the flow rate calculation value respectively; Step 3, comparing the head calculation value with the head target value, and adjusting the speed of the water pump motor according to the comparison result and the water pump operation mode.

[0006] In some embodiments, the water pump operation mode includes a constant head mode. When the water pump operation mode set by the user is the constant head mode, in step three, it further includes calculating the difference between the calculated head value and the target head value, calculating and outputting the target speed of the water pump motor according to the difference, adjusting the water pump motor according to the target speed, and returning to step two until the calculated head value reaches the target head value.

[0007] In some embodiments, the water pump operation mode includes a proportional pressure boosting mode. When the water pump operation mode set by the user is the proportional pressure boosting mode, in step three, it further includes calculating the difference between the calculated head value and the target head value, calculating and outputting the target speed of the water pump motor according to the difference, adjusting the water pump motor according to the pressure boosting ratio and the target speed, and returning to step two until the calculated head value reaches the target head value.

[0008] In some embodiments, the water pump operation mode includes an energy-saving mode. When the water pump operation mode set by the user is the energy-saving mode, in step two, calculate the difference between the calculated head value and the target head value, calculate and output the target speed of the water pump motor according to the difference, adjust the water pump motor according to the target speed, and make the water pump operate in the best efficiency area.

[0009] In some embodiments, in step one, it further includes the step of displaying the calculated head and / or flow rate through a display screen.

[0010] In some embodiments, the training method of the water pump motor state control model includes: A water pump motor state data acquisition step, where the water pump motor state data includes acquiring the power and speed of the water pump motor, sampling the phase current and bus voltage of the water pump motor, and calculating the water pump operation power according to the phase current and bus voltage; Acquire the flow rate and head of the water pump; Input the water pump motor state data, flow rate and head into a neural network model, and train to obtain a water pump motor state control model regarding head, flow rate and speed.

[0011] In some embodiments, a maximum head value and a maximum flow value constraint are also set in the water pump motor state control model. When the calculated head value exceeds the maximum head value, output control according to the maximum head value.

[0012] In some embodiments, the water pump frequency converter controller includes: A control module; A power factor correction circuit, which is connected to the control module through a power factor correction drive circuit; A power module, one path of which is used to receive the control signal sent by the control module, and the other path is used to receive the power factor correction signal sent by the power factor correction circuit, generate a water pump motor drive signal and send it to the water pump motor; A display screen, which is connected to the control module; An input module, which is used to receive the water pump operation mode and the head target value set by the user and send them to the control module.

[0013] In some embodiments, the water pump frequency converter controller further includes: A current acquisition circuit, which is used to acquire the output current of the power module and send it to the control module.

[0014] In some embodiments, the water pump frequency converter controller is integrally installed with the water pump.

[0015] Compared with the prior art, the advantages and positive effects of the present invention are: For the water pump frequency converter controller of the present invention, the water pump frequency converter controller is configured with a water pump motor state control model. This model can calculate the corresponding head calculation value according to the speed of the water pump motor, compare the head calculation value with the head target value set by the user, and adjust the speed of the water pump motor according to the comparison result until the head target value is reached. This solution does not require the setting of a flow sensor and a pressure sensor, thereby avoiding a series of problems caused by the setting of sensors. By controlling the water pump motor to reach the set speed after startup, on the one hand, an initial speed is provided for the water pump motor, and the initial speed is used to provide an initial input value for the water pump motor state control model. This solution takes the adjustment of the speed of the water pump motor as a means, calculates the head calculation value according to the speed, and uses the difference between the head calculation value and the head target value as the basis for adjusting the speed, and finally realizes the invention purpose that the head calculation value reaches the head target value.

[0016] After reading the specific embodiments of the present invention in conjunction with the accompanying drawings, other features and advantages of the present invention will become clearer. Description of the Drawings

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required in the embodiments. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0018] Figure 1 is a schematic diagram of the wire connection of an existing water pump connected in a pipeline; Figure 2 is a characteristic curve diagram of an existing control method in the constant head mode; Figure 3 is the characteristic curve diagram in the proportional pressure boosting mode of the existing control method; Figure 4 is the flowchart of an embodiment of the water pump variable frequency controller proposed by the present invention; Figure 5 is the schematic diagram of the training of the water pump motor state control model in an embodiment of the water pump variable frequency controller proposed by the present invention; Figure 6 is the characteristic curve diagram of the water pump variable frequency controller proposed by the present invention in the constant head mode; Figure 7 is the characteristic curve diagram of the water pump variable frequency controller proposed by the present invention in the proportional pressure boosting mode. Detailed implementation manners

[0019] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0020] In the description of the present invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0021] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations. In the description of the implementation manner, specific features, structures, materials, or characteristics can be combined in a suitable manner in any one or more embodiments or examples.

[0022] The terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features.

[0023] In the description of the present invention, unless otherwise specified, "a plurality of" means two or more.

[0024] This embodiment provides a variable-frequency controller for a water pump. The variable-frequency controller for the water pump is used to connect to the water pump, and the water pump is connected in a pipeline. In practical applications, it is often necessary to control the water pump to reach a set head or flow rate. The variable-frequency controller for the water pump in this embodiment is used to implement the control of the water pump. Among them, the variable-frequency controller for the water pump is configured with a control model for the state of the water pump motor, and the control method of the variable-frequency controller for the water pump includes: Step 1: Receive the water pump operation mode and the head target value set by the user, and control the water pump motor to start until the water pump motor reaches the set speed.

[0025] Step 2: The control model for the state of the water pump motor calculates the corresponding head and flow velocity according to the current speed, which are the calculated head value and the calculated flow velocity value respectively.

[0026] Step 3: Compare the calculated head value with the head target value, and adjust the speed of the water pump motor according to the comparison result and the water pump operation mode.

[0027] The variable-frequency controller for the water pump in this embodiment is configured with a control model for the state of the water pump motor. This model can calculate the corresponding calculated head value according to the speed of the water pump motor, compare the calculated head value with the head target value set by the user, and adjust the speed of the water pump motor according to the comparison result until the head target value is reached.

[0028] This solution does not require the setting of a flow sensor and a pressure sensor, and thus a series of problems caused by the setting of sensors can be avoided. By controlling the water pump motor to reach the set speed after starting, on the one hand, an initial speed is provided for the water pump motor, and the initial speed is used to provide an initial input value for the control model for the state of the water pump motor.

[0029] This solution takes the adjustment of the speed of the water pump motor as a means, calculates the calculated head value according to the speed, and uses the difference between the calculated head value and the head target value as the basis for adjusting the speed, and finally realizes the invention purpose of making the calculated head value reach the head target value.

[0030] In some embodiments, as Figure 4 shown, the water pump operation mode includes a constant-head mode. Due to the real-time change in the number of water usage points, different pipe diameters in different pipelines, or pipeline blockages and other various situations, the pressure in the pipeline changes in real time. Therefore, when the factors in the pipeline change, if the speed of the water pump motor is not changed accordingly, the head, flow velocity, etc. will change, and the constant head cannot be achieved, which will cause the operation performance of the water pump to be seriously affected by external factors.

[0031] To solve the above problems, when the pump operation mode set by the user is the constant head mode, step three further includes calculating the difference between the calculated head value and the target head value, calculating and outputting the target speed of the pump motor according to the difference, adjusting the pump motor according to the target speed, and returning to step two until the calculated head value reaches the target head value.

[0032] The adjustment of the pump motor speed is based on FOC control. The FOC algorithm will adjust the switches of the power module according to the current rotor angle to output an adjustable voltage and frequency sine voltage to control the pump motor to change its speed.

[0033] As Figure 6 shown, it is the test characteristic curve in the constant head mode using the control method of this embodiment. It can be seen from the figure that it is basically consistent with the data collected by the sensor. Compared with the test characteristic curve of the traditional control method in Figure 2 , the characteristic curve of this solution is smoother and closer to the pump characteristic curve.

[0034] In some embodiments, the pump operation mode includes the proportional pressure boost mode. When the pump operation mode set by the user is the proportional pressure boost mode, step three further includes calculating the difference between the calculated head value and the target head value, calculating and outputting the target speed of the pump motor according to the difference, adjusting the pump motor according to the pressure boost ratio and the target speed, and returning to step two until the calculated head value reaches the target head value.

[0035] As Figure 7 shown, it is the test characteristic curve in the proportional pressure boost mode using the control method of this embodiment. It can be seen from the figure that the flow rate and the head can change synchronously, and compared with the test characteristic curve of the traditional proportional pressure boost mode control method in Figure 3 , the characteristic curve of this solution is smoother and closer to the pump characteristic curve.

[0036] In some embodiments, the pump operation mode includes the energy-saving mode. When the pump operation mode set by the user is the energy-saving mode, in step two, calculate the difference between the calculated head value and the target head value, calculate and output the target speed of the pump motor according to the difference, adjust the pump motor according to the target speed, and make the pump operate in the best efficiency area. The adjustment method of adjusting the pump motor to make the pump operate in the best efficiency area can be achieved by using existing motor adjustment methods.

[0037] In some embodiments, in step one, there is also a step of displaying the calculated head and / or flow rate on the display screen. The flow rate is directly displayed on the display screen, and the head value is used for the PI control of the controller, which inversely affects the motor speed to achieve closed-loop control.

[0038] By using AI technology, the controller can autonomously fit the control curve, accurately estimate the fluid head and flow rate values of the pipeline pump through software algorithms, and control the head and flow rate by controlling the speed of the permanent magnet synchronous motor. The frequency conversion control also improves the energy-saving effect of the product, with a comprehensive energy saving of 20%.

[0039] In some embodiments, such as Figure 5 shown, the training method of the water pump motor state control model includes: The step of obtaining the water pump motor state data, where the water pump motor state data includes obtaining the power and speed of the water pump motor. By sampling the phase current and bus voltage of the water pump motor, the operating power of the water pump is calculated based on the phase current and bus voltage.

[0040] Obtain the flow rate and head of the water pump.

[0041] Input the water pump motor state data, flow rate, and head into the neural network model to train the water pump motor state control model regarding head, flow rate, and speed.

[0042] By sampling the motor phase current and bus voltage, obtain the operating power and speed information of the water pump for model training.

[0043] Similarly, to ensure the stability of data application, it also includes filtering algorithms such as low-pass filtering for key parameters such as phase current, bus voltage, and power to ensure data smoothness, and finally ensure the stability of flow rate and head data.

[0044] In some embodiments, the training of the water pump motor state control model can adopt a two-layer feedforward network with sigmoid hidden neurons and linear output neurons. It can well adapt to any multi-dimensional mapping problem. This network is trained using the Levenberg-Marquardt backpropagation algorithm. On the premise that the data is consistent and the hidden layer is equipped with a sufficient number of neurons, through fine design and configuration, this two-layer feedforward neural network can accurately estimate the head and flow rate values of the pipeline pump fluid and effectively control these parameters.

[0045] Use the measured data of the water intake pump to train the model to make it more in line with the actual operating conditions, thereby improving the fitting accuracy of the water pump characteristic curve; then, set constraint conditions according to the measured data of the water intake pump and the actual operating conditions to ensure that the optimized scheduling model conforms to the actual operating situation of the water intake pump station.

[0046] The network contains a hidden layer, which is composed of 10 neurons. Such a design choice aims to balance the complexity of the model and computational efficiency, ensuring that the network can capture the key features in the data without increasing the training difficulty or reducing the generalization ability due to excessive complexity. Each of these 10 neurons has a Sigmoid activation function, which can non-linearly transform the input data. With such a configuration, the network can demonstrate high flexibility and accuracy when processing multi-dimensional data, especially in tasks such as estimating the fluid head of a pipeline pump and controlling process values.

[0047] In some embodiments, the water pump motor state control model is also provided with constraints on the maximum head value and the maximum flow value. When the calculated head value exceeds the maximum head value, the control is output according to the maximum head value.

[0048] In the training of the water pump motor state control model in this embodiment, by adding constraint conditions, the constraint conditions can clarify the maximum head, flow rate constrained by the design of the water pump head itself, and the maximum power constrained by the design of the motor itself. The addition of this constraint condition can make the "motor state - head, flow model" closer to the real ability model of the water pump combined with the controlled motor and pump head, avoiding over-specification use, better protecting the pump head and motor, and extending the service life of the water pump.

[0049] In some embodiments, as shown in the figure, the variable frequency controller of the water pump includes: a control module; a power factor correction circuit, which is connected to the control module through a power factor correction drive circuit; a power module, one path of the power module is used to receive the control signal sent by the control module, and the other path is used to receive the power factor correction signal sent by the power factor correction circuit, generate a water pump motor drive signal and send it to the water pump motor; a display screen, which is connected to the control module. An input module, which is used to receive the water pump operation mode and the head target value set by the user and send them to the control module.

[0050] Among them, the power factor correction circuit (PFC circuit) is composed of a BOOST boost circuit, a PFC chip and peripheral circuits. The PFC chip controls the switching frequency of the MOS tube in the BOOST circuit, actively adjusts the current waveform, and reduces the VBUS output ripple. The chip integrates overcurrent protection, overvoltage protection and undervoltage protection inside. The current is sampled through a sampling resistor and sent to the chip pin. If the current is higher than the set value, the chip protection is triggered and the drive output is turned off in time. The output voltage is sampled through a resistor and sent to the chip pin. When the voltage is higher than the overvoltage set value, the overvoltage protection is triggered and the chip turns off the drive output. When the voltage is lower than the undervoltage set value, the undervoltage protection is triggered and the chip enters the low-power shutdown mode.

[0051] In some embodiments, the water pump variable frequency controller further includes a rectifier circuit. The rectifier and filter circuit consists of three parts: an EMI filter, a protection circuit, and a rectifier circuit. The alternating current input enters the EMI filter after passing through the protection circuit. The EMI filter mainly consists of an X capacitor, a common mode inductor, and a Y capacitor. This circuit mainly eliminates the common mode and differential mode signal interference in the alternating current. After passing through the EMI filter, it enters the rectifier circuit for rectification, rectifying the alternating current into direct current and then inputting it to the subsequent circuit.

[0052] In some embodiments, the water pump variable frequency controller further includes a power supply circuit. The power supply circuit uses an isolated flyback power supply, which consists of a power supply chip, a transformer, and peripheral circuits. The power input is applied to the primary coil of the transformer. The on / off of the primary coil is controlled by the MOS tube integrated inside the power supply chip, thereby controlling the output of the secondary coil of the transformer. When the MOS tube is turned on, the current in the primary coil increases. Since the secondary coil is opposite to the primary coil, the output voltage is cut off by the rectifier diode. When the MOS tube is turned off, the voltage of the primary coil reverses, and the voltage of the secondary coil also reverses. The rectifier diode of the secondary conducts, and the normal output voltage is obtained. The secondary coil of this transformer has two outputs. One output provides an unisolated 15V voltage to the subsequent LDO to step down to 5V for powering the main control MCU. The other output provides an isolated 13V voltage to the subsequent LDO to step down to 5V for powering the auxiliary MCU.

[0053] In some embodiments, the water pump variable frequency controller further includes an inverter circuit. The inverter circuit is mainly implemented through an Intelligent Power Module (IPM). The IPM integrates 6 IGBTs, overcurrent protection, temperature detection, and alarm signal output. Six drive signals are output by the MCU to control the on / off of the IGBTs, thereby converting the DC signal into a three-phase signal to drive the motor to rotate. At the same time, the motor phase current is collected through a sampling resistor and input to the MCU pin after passing through an operational amplifier. The motor bus current enters the overcurrent protection detection pin of the IPM through an RC filter circuit. If the bus current is higher than the threshold set for overcurrent detection, the IPM will automatically turn off the output for protection. At the same time, the IPM also outputs real-time temperature data to the control module, thereby helping the control module control the output of the drive signals.

[0054] In some embodiments, the water pump variable frequency controller further includes: a current acquisition circuit, which is used to acquire the output current of the power module and send it to the control module.

[0055] In some embodiments, the water pump variable frequency controller is integrally installed with the water pump. By integrally installing the water pump variable frequency controller with the water pump, this solution also greatly saves on-site wiring and is convenient for installation.

[0056] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions required to be protected by the present invention.

Claims

1. A water pump frequency conversion controller, characterized in that: The water pump frequency conversion controller is used to connect to the water pump. The water pump frequency conversion controller is configured with a water pump motor state control model. The control method of the water pump frequency conversion controller includes: Step 1: receiving the water pump operation mode and lift target value set by the user, and controlling the water pump motor to start until the water pump motor reaches the set speed; Step 2: the water pump motor state control model calculates the corresponding head and flow rate according to the current speed, which are the head calculation value and the flow rate calculation value respectively; Step three, comparing the calculated lift value with the target lift value, and adjusting the speed of the water pump motor according to the comparison result and the water pump operation mode.

2. The water pump frequency conversion controller according to claim 1, characterized in that: The water pump operation mode includes a constant head mode. When the water pump operation mode set by the user is the constant head mode, step three also includes calculating the difference between the head calculation value and the head target value, calculating and outputting the target speed of the water pump motor according to the difference, adjusting the water pump motor according to the target speed, and returning to step two until the head calculation value reaches the head target value.

3. The water pump frequency conversion controller according to claim 1, characterized in that: The water pump operation mode includes a proportional boost mode. When the water pump operation mode set by the user is the proportional boost mode, step three also includes calculating the difference between the head calculation value and the head target value, calculating and outputting the target speed of the water pump motor based on the difference, adjusting the water pump motor according to the boost ratio and the target speed, and returning to step two until the head calculation value reaches the head target value.

4. The water pump frequency conversion controller according to claim 1, characterized in that: The water pump operation mode includes an energy-saving mode. When the water pump operation mode set by the user is the energy-saving mode, in step 2, the difference between the head calculation value and the head target value is calculated, and the target speed of the water pump motor is calculated and output according to the difference. The water pump motor is adjusted according to the target speed, and the water pump operates in the optimal efficiency zone.

5. The water pump frequency conversion controller according to claim 1, characterized in that: Step one also includes the step of displaying the calculated head and / or flow rate on a display screen.

6. The water pump frequency conversion controller according to any one of claims 1 to 5, characterized in that: The training method of the water pump motor state control model includes: A step of acquiring water pump motor status data, wherein the water pump motor status data includes acquiring the power and speed of the water pump motor, sampling the phase current and bus voltage of the water pump motor, and calculating the water pump operating power according to the phase current and bus voltage; Get the flow rate and head of the water pump; The water pump motor state data, flow rate and head are input into a neural network model, and a water pump motor state control model with respect to head, flow rate and rotation speed is obtained through training.

7. The water pump frequency conversion controller according to claim 6, characterized in that: The water pump motor state control model is also provided with maximum head value and maximum flow value constraints. When the head calculation value exceeds the maximum head value, the output control is performed according to the maximum head value.

8. The water pump frequency conversion controller according to any one of claims 1 to 5, characterized in that: The water pump frequency conversion controller comprises: Control module; A power factor correction circuit connected to the control module via a power factor correction drive circuit; A power module, wherein one path of the power module is used to receive the control signal sent by the control module, and the other path of the power module is used to receive the power factor correction signal sent by the power factor correction circuit, generate a water pump motor drive signal and send it to the water pump motor; A display screen connected to the control module; The input module is used to receive the water pump operation mode and the head target value set by the user, and send them to the control module.

9. The water pump frequency conversion controller according to claim 8, characterized in that: The water pump frequency conversion controller also includes: The current collection circuit is used to collect the output current of the power module and send it to the control module.

10. The water pump frequency conversion controller according to any one of claims 1 to 5, characterized in that: The water pump frequency conversion controller is installed integrally with the water pump.

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