Motor step-down power-saving device and intelligent AC induction motor system

Abstract

The invention provides a motor step-down power-saving device and an intelligent AC induction motor system, line voltage real-time monitoring data, line current real-time monitoring data and motor environment real-time monitoring data of a target AC induction motor are monitored and collected through a motor monitoring module, and a motor control module, such as a microcontroller, is used for controlling the voltage of the target AC induction motor. When it is judged that the target AC induction motor meets the voltage reduction and power saving conditions, a target line voltage effective value of the target AC induction motor is calculated based on a pre-trained motor voltage regulation parameter prediction model, and a voltage regulation control signal is generated according to the target line voltage effective value so as to control a motor voltage regulation module to adjust the terminal voltage of the target AC induction motor to the target line voltage effective value; therefore, the terminal voltage and the stator current input into the target alternating-current induction motor are adjusted in time by applying the optimal control principle, so that the target alternating-current induction motor is always in the optimal working state, the motor energy consumption is reduced, and the motor efficiency and the power saving rate are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of alternating current induction motor, and particularly relates to a motor voltage reduction and power saving device and an intelligent alternating current induction motor system. BACKGROUND

[0002] The alternating current induction motor, also known as an asynchronous motor, is an electric motor that converts electric energy into mechanical energy by electromagnetic induction. The working principle is as follows: when three-phase alternating current is input into the stator winding of the alternating current induction motor, a rotating magnetic field is generated, and the rotating magnetic field rotates and then moves relative to the rotor winding of the alternating current induction motor, so that each rotor conductor in the rotor winding moves relative to the rotating magnetic field to cut the magnetic induction lines, thereby generating an induced electromotive force and an induced current in each rotor conductor; the induced current in each rotor conductor interacts with the rotating magnetic field to generate an electromagnetic torque, thereby driving each rotor conductor to rotate, and in turn driving the rotating shaft and the load to rotate.

[0003] At present, the working states of the alternating current induction motor mainly include: load transient change with constant speed, and speed transient change with constant terminal voltage. When the alternating current induction motor is lightly loaded, the load decreases, the rotor speed starts to increase, the slip of the rotor and the rotating magnetic field of the stator decreases, and according to the law of electromagnetic induction, the induced electromotive force and the induced current in the rotor conductor significantly decrease, and the stator side current also decreases accordingly, and the motor output power decreases. However, if the terminal voltage supplied to the alternating current induction motor is constant, the motor input power is constant, therefore, the motor efficiency of the alternating current induction motor decreases with the decrease of the load, and the loss increases. SUMMARY

[0004] In view of the above-mentioned defects of the prior art, the purpose of the present application is to provide a motor voltage reduction and power saving device and an intelligent alternating current induction motor system, which are used to solve the technical problem of the decrease of the motor efficiency of the existing alternating current induction motor when the motor is lightly loaded.

[0005] To achieve the above object and other related objects, the first aspect of the present application provides a motor voltage reduction and power saving device, which comprises: a motor monitoring module connected to a target AC induction motor, comprising: an end voltage monitoring circuit, a current monitoring circuit, and an environment monitoring circuit, which are respectively used to collect line voltage real-time monitoring data, line current real-time monitoring data, and motor environment real-time monitoring data of the target AC induction motor in real time based on a preset sampling frequency; a motor control module connected to the motor monitoring module, which is used to calculate a target line voltage effective value of the target AC induction motor based on a pre-trained motor voltage regulation parameter prediction model when it is determined that the target AC induction motor meets a voltage reduction and power saving condition according to the line voltage real-time monitoring data, the line current real-time monitoring data, and the motor environment real-time monitoring data, and generate a voltage regulation control signal accordingly; and a motor voltage regulation module connected to the motor control module and the target AC induction motor, which is used to adjust an end voltage of the target AC induction motor to the target line voltage effective value according to the voltage regulation control signal.

[0006] In some embodiments of the first aspect of the present application, the way of determining that the target AC induction motor meets the voltage reduction and power saving condition comprises: calculating a line voltage effective value, an active power, and an apparent power of the target AC induction motor in a current power frequency cycle in real time according to the line voltage real-time monitoring data and the line current real-time monitoring data; calculating a power factor of the target AC induction motor in the current power frequency cycle in real time according to the active power and the apparent power; calculating a load rate of the target AC induction motor in the current power frequency cycle in real time according to the active power and a rated active power of the target AC induction motor; calculating a current unbalance degree of the target AC induction motor in the current power frequency cycle in real time according to the line voltage real-time monitoring data and the line current real-time monitoring data; and determining that the target AC induction motor is in a light load state and meets a preset voltage reduction and power saving condition when the line voltage effective value exceeds a preset line voltage threshold value, the power factor is less than a preset power factor threshold value, the load rate is less than a preset load rate threshold value, and the current unbalance degree is less than a preset current unbalance threshold value.

[0007] In some embodiments of the first aspect of the present application, the motor voltage regulation parameter prediction model comprises: an input layer configured to receive the line voltage real-time monitoring data, the line current real-time monitoring data, and the motor environment real-time monitoring data, and perform data preprocessing operations on the time series feature data; a multi-branch hybrid network layer connected to the input layer, configured to perform feature extraction and feature learning on each time series feature data respectively, and generate fusion time series feature data; a long short-term memory network layer connected to the multi-branch hybrid network layer, configured to effectively learn the long-term dependence relationship in the fusion time series feature data, and embed motor parameters and working condition parameters of the target AC induction motor for multi-scale processing to generate multi-scale feature data; an attention layer connected to the long short-term memory network layer, configured to identify one or more key features in the multi-scale time series feature data and perform focused learning to generate key feature data; and a fully connected layer connected to the attention layer, configured to predict and output the target line voltage effective value of the target AC induction motor under the current working condition according to the key feature data.

[0008] In some embodiments of the first aspect of the present application, the multi-branch hybrid network layer comprises: a first branch network connected to the input layer, configured to perform feature extraction and feature learning on the standardized line voltage real-time monitoring data and the line current real-time monitoring data, and generate first time series feature data; a second branch network connected to the input layer, configured to calculate the average power, power factor, load rate, motor loss, motor efficiency change, and power saving rate of a preset time series window in real time according to the standardized line voltage real-time monitoring data and the line current real-time monitoring data, and perform feature extraction and feature learning to generate second time series feature data; a third branch network connected to the input layer, configured to perform feature extraction and feature learning on the standardized motor environment real-time monitoring data to generate third time series feature data; and a fusion layer connected to the first branch network, the second branch network, and the third branch network respectively, configured to perform feature fusion on the first time series feature data, the second time series feature data, and the third time series feature data to generate fusion time series feature data.

[0009] In some embodiments of the first aspect of the application, the training method of the motor voltage regulation parameter prediction model comprises: obtaining motor line voltage time series data, motor line current time series data and motor environment time series data under a plurality of historical working conditions, and labeling the optimized motor line voltage effective value and the optimized motor power saving rate of each historical working condition to construct a supervised learning training data set; according to the training sample data set, based on the pre-defined network structure of the motor voltage regulation parameter prediction model, a converged motor voltage regulation parameter basic prediction model is trained and obtained; the motor voltage regulation parameter basic prediction model is migrated to the target alternating current induction motor, target line voltage time series data, target line current time series data and target motor environment time series data of the target alternating current induction motor under a plurality of historical working conditions are obtained to continue training the motor voltage regulation parameter basic prediction model, and a transfer learning training data set is constructed to train and obtain a converged motor voltage regulation parameter prediction model; the motor voltage regulation parameter prediction model is deployed to the real environment of the target alternating current induction motor, according to the input line voltage real-time monitoring data, line current real-time monitoring data and motor environment real-time monitoring data, the target line voltage effective value of the target alternating current induction motor is predicted, and the motor voltage regulation parameter prediction model is dynamically optimized according to the power saving rate after voltage reduction of the target alternating current induction motor.

[0010] In some embodiments of the first aspect of the application, the motor voltage regulation module comprises: a three-phase thyristor including three groups of anti-parallel thyristor valves connected to the input end of the target alternating current induction motor, for obtaining the target line voltage effective value of the target alternating current induction motor according to the received voltage regulation control signal, and adjusting the conduction time of each thyristor valve to adjust the output current and adjust the terminal voltage applied to the target alternating current induction motor.

[0011] In some embodiments of the first aspect of the application, the terminal voltage monitoring circuit comprises a voltage transformer connected in parallel to the input of the target AC induction motor and connected to the motor control module, for monitoring the three-phase terminal voltage variation of the input of the target AC induction motor in real time and collecting the line voltage real-time monitoring data and sending it to the motor control module in real time; the current monitoring circuit comprises a current transformer connected in series to the input of the target AC induction motor and connected to the motor control module, for monitoring the three-phase AC current variation flowing into the stator winding of the target AC induction motor in real time and collecting the line current real-time monitoring data and sending it to the motor control module in real time; the environment monitoring unit comprises one or more temperature sensors and one or more humidity sensors connected to the target AC induction motor and the motor control module respectively, for monitoring the temperature variation and humidity variation of the environment around the target AC induction motor in real time respectively, and generating motor temperature real-time monitoring data and motor humidity real-time monitoring data to generate the motor environment real-time monitoring data and send it to the motor control module.

[0012] In some embodiments of the first aspect of the application, the motor voltage reduction and power saving device further comprises a start-stop control module comprising a frequency converter connected to the input of the target AC induction motor, for smoothly raising the terminal voltage and frequency of the target induction motor to a preset value when the target AC induction motor starts, and smoothly lowering the terminal voltage and frequency of the target induction motor to zero when the target AC induction motor stops.

[0013] In some embodiments of the first aspect of the application, the motor voltage reduction and power saving device further comprises an energy storage module connected to the output of the target AC induction motor, for storing the electrical energy generated when the rotor speed exceeds the synchronous speed of the stator rotating magnetic field when the target AC induction motor is braked under the drive of the frequency converter, for recycling.

[0014] To achieve the above object and other related objects, the second aspect of the present application provides an intelligent AC induction motor system, which comprises an AC induction motor and a motor voltage reduction and power saving device connected to the AC induction motor; wherein the motor voltage reduction and power saving device comprises a motor monitoring module connected to the AC induction motor, which comprises an end voltage monitoring circuit, a current monitoring circuit and an environment monitoring circuit, and is configured to collect line voltage real-time monitoring data, line current real-time monitoring data and motor environment real-time monitoring data of the AC induction motor based on a preset sampling frequency; a motor control module connected to the motor monitoring module, which is configured to calculate a target line voltage effective value of the AC induction motor based on a pre-trained motor voltage regulation parameter prediction model when it is determined that the AC induction motor meets a voltage reduction and power saving condition according to the line voltage real-time monitoring data, the line current real-time monitoring data and the motor environment real-time monitoring data, and generate a voltage regulation control signal accordingly; and a motor voltage regulation module connected to the motor control module and the AC induction motor, which is configured to adjust an end voltage of the AC induction motor to the target line voltage effective value according to the voltage regulation control signal.

[0015] As described above, the present application provides a motor voltage reduction and power saving device and an intelligent AC induction motor system, which collects line voltage real-time monitoring data, line current real-time monitoring data and motor environment real-time monitoring data of a target AC induction motor through a motor monitoring module, and calculates a target line voltage effective value of the target AC induction motor based on a pre-trained motor voltage regulation parameter prediction model when it is determined that the target AC induction motor meets a voltage reduction and power saving condition through a motor control module such as a microcontroller, and generates a voltage regulation control signal to control a motor voltage regulation module to adjust an end voltage of the target AC induction motor to the target line voltage effective value. The present application has the following beneficial effects: applying optimal control principle, timely adjusting an end voltage and a stator current input to a target AC induction motor, keeping the target AC induction motor in an optimal working state, reducing motor energy consumption, improving motor efficiency and power saving rate, and solving the technical problem of reduced motor efficiency of an existing AC induction motor under light load. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 A structure schematic diagram of a motor voltage reduction and power saving device in an embodiment of the present application is shown.

[0017] Figure 2 A structure schematic diagram of a motor voltage reduction and power saving device in an embodiment of the present application is shown.

[0018] Figure 3 A flow schematic diagram of a motor voltage reduction and power saving method in an embodiment of the present application is shown.

[0019] Figure 4A structure diagram of a motor voltage regulation parameter prediction model in an embodiment of the present application is shown.

[0020] Figure 5 A structure diagram of an intelligent AC induction motor system in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0021] The advantages and effects of the present application can be easily understood by those skilled in the art from the description of the specific embodiments. The present application can also be implemented or applied in other different specific embodiments, and various modifications or changes can be made to the details in the description based on different views and applications without departing from the spirit of the present application. It should be noted that the embodiments below and the features in the embodiments can be combined with each other without conflict.

[0022] In the embodiments of the present application, the same items or similar items with basically the same functions and effects are distinguished by using "first", "second", etc. For example, the first analog-to-digital converter and the second analog-to-digital converter are only used to distinguish different analog-to-digital converters, and do not limit the order. Those skilled in the art can understand that "first", "second", etc. do not limit the number and execution order, and "first", "second", etc. do not necessarily mean different.

[0023] To solve the technical problems in the background art, the present application provides a motor voltage reduction and power saving device and an intelligent AC induction motor system, which aims to monitor and collect line voltage real-time monitoring data, line current real-time monitoring data and motor environment real-time monitoring data of a target AC induction motor, and through a motor control module such as a microcontroller, when it is determined that the target AC induction motor meets the voltage reduction and power saving condition, the target line voltage effective value of the target AC induction motor is calculated based on a pre-trained motor voltage regulation parameter prediction model, and a voltage regulation control signal is generated to control the motor voltage regulation module to adjust the terminal voltage of the target AC induction motor to the target line voltage effective value, thereby solving the technical problem of reduced motor efficiency of the existing AC induction motor under light load.

[0024] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the embodiments of the present application is further described in detail in conjunction with the following embodiments and the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0025] As shown in Figure 1 A structure diagram of a motor voltage reduction and power saving device in an embodiment of the present application is shown. The motor voltage reduction and power saving device in the embodiment includes a motor monitoring module, a motor control module and a motor voltage regulation module.

[0026] The motor monitoring module comprises an end voltage monitoring circuit, a current monitoring circuit and an environment monitoring circuit.

[0027] Specifically, as shown in Figure 1 The end voltage monitoring circuit is connected to the input end of the target AC induction motor and the motor control module, respectively, for monitoring the three-phase end voltage variation of the input end of the target AC induction motor in real time, and sending the line voltage real-time monitoring data of the target AC induction motor to the motor control module in real time based on a preset sampling frequency. The line voltage real-time monitoring data comprises three-phase line voltage instantaneous values of the target AC induction motor at multiple sampling time points, i.e. AB-phase line voltage instantaneous values, BC-phase line voltage instantaneous values and CA-phase line voltage instantaneous values of the target AC induction motor at multiple sampling time points.

[0028] In an embodiment, the end voltage monitoring circuit can adopt a voltage transformer. As shown in Figure 2 The voltage transformer is connected in parallel to the input end of the target AC induction motor, and can convert a high voltage signal into a low voltage signal output in proportion, so as to complete the measurement of the high voltage signal by measuring the low voltage signal, and obtain the AB-phase line voltage instantaneous values, BC-phase line voltage instantaneous values and CA-phase line voltage instantaneous values of the target AC induction motor at each sampling time point. Preferably, the end voltage monitoring circuit further comprises a first three-phase filter and a first analog-to-digital converter. The input end of the first three-phase filter is connected to the output end of the voltage transformer, and the output end is connected to the input end of the first analog-to-digital converter, for filtering out high-frequency switching noise and electromagnetic interference in the low voltage signal output by the voltage transformer, so as to obtain a purified voltage signal and ensure the measurement accuracy; the output end of the first analog-to-digital converter is connected to the motor control module, for converting the voltage signal into a digital signal, generating the line voltage real-time monitoring data, and transmitting the line voltage real-time monitoring data to the motor control module.

[0029] As shown in Figure 1 The current monitoring circuit is connected to the input end of the target AC induction motor and the motor control module, respectively, for monitoring the three-phase AC current variation flowing into the stator winding of the target AC induction motor in real time, and sending the line current real-time monitoring data of the target AC induction motor to the motor control module in real time based on a preset sampling frequency. The line current real-time monitoring data comprises three-phase line current instantaneous values flowing into the stator winding at multiple sampling time points, i.e. A-phase line current instantaneous values, B-phase line current instantaneous values and C-phase line current instantaneous values flowing into the stator winding at multiple sampling time points.

[0030] In an embodiment, the current monitoring circuit can adopt a current transformer. As shown in Figure 2As shown, the current transformer is connected in series to the input end of the target AC induction motor, and according to the principle of electromagnetic induction, a small current signal proportional to the large current at the input end is output, so that the measurement of the large current signal is completed by measuring the small current signal, and the A-phase line current instantaneous value, the B-phase line current instantaneous value and the C-phase line current instantaneous value flowing into the stator winding at multiple sampling time instants are obtained. Preferably, the current monitoring circuit further comprises a sampling resistor, a second three-phase filter and a second analog-to-digital converter. The sampling resistor is connected in parallel to the output end of the current transformer, for converting the current signal output by the current transformer into a voltage signal; the input end of the second three-phase filter is connected to one end of the sampling resistor, and the output end is connected to the input end of the second analog-to-digital converter, for filtering out high-frequency switching noise and electromagnetic interference of the converted voltage signal, so as to obtain a purified voltage signal and ensure the measurement accuracy; and the output end of the second analog-to-digital converter is connected to the motor control module, for converting the voltage signal into a digital signal, generating the line current real-time monitoring data and transmitting the line current real-time monitoring data to the motor control module.

[0031] It should be understood that when the load of the target AC induction motor changes, the stator current (i.e. the three-phase line current flowing into the stator winding) also changes. For example, when the load of the target AC induction motor decreases, the load torque increases, the rotor speed begins to increase, resulting in a decrease in the slip rate of the rotor and the stator rotating magnetic field speed, so according to the law of electromagnetic induction, the induced electromotive force and induced current in the rotor conductor are significantly reduced, and the stator side current also decreases accordingly, i.e. the three-phase line current instantaneous value decreases, and the three-phase line voltage instantaneous value decreases. Therefore, by monitoring the line voltage real-time monitoring data and the line current real-time monitoring data of the target AC induction motor in real time, the load of the target AC induction motor is monitored in real time.

[0032] The environmental monitoring circuit comprises one or more temperature sensors and one or more humidity sensors. As shown, Figure 2 Each temperature sensor and each humidity sensor is installed at different parts of the target AC induction motor and connected to the motor control module, respectively, for monitoring the temperature change and the humidity change of the environment around the target AC induction motor in real time, and generating motor temperature real-time monitoring data and motor humidity real-time monitoring data to generate the motor environment real-time monitoring data and transmit the motor environment real-time monitoring data to the motor control module. The motor environment real-time monitoring data comprises the motor temperature real-time monitoring data and the motor humidity real-time monitoring data.

[0033] As shown, Figure 1As shown, the motor control module is connected to the motor monitoring module, specifically, connected to the terminal voltage monitoring circuit, the current monitoring circuit and the environment monitoring circuit. The motor control module is used to monitor the line voltage real-time monitoring data, the line current real-time monitoring data and the motor environment real-time monitoring data, and when the target AC induction motor meets the voltage reduction and power saving condition, the target line voltage effective value of the target AC induction motor is calculated based on the pre-trained motor voltage regulation parameter prediction model, and the voltage regulation control signal is generated accordingly.

[0034] In an embodiment, the motor control module comprises a microcontroller. The microcontroller can be built-in algorithm, configured to implement the voltage reduction and power saving method of the target AC induction motor, and the specific steps are as follows Figure 3

[0035] Step S1: receiving the line voltage real-time monitoring data, the line current real-time monitoring data and the motor environment real-time monitoring data.

[0036] Step S2: according to the line voltage real-time monitoring data and the line current real-time monitoring data, judge whether the target AC induction motor meets the voltage reduction and power saving condition.

[0037] In an embodiment, the step S2 comprises the following steps.

[0038] ① According to the line voltage real-time monitoring data and the line current real-time monitoring data, the line voltage effective value, the active power and the apparent power of the target AC induction motor in the current frequency period are calculated in real time.

[0039] Specifically, the AB phase line voltage instantaneous value, BC phase line voltage instantaneous value and CA phase line voltage instantaneous value in the current frequency period in the line voltage real-time monitoring data are obtained, and the A phase line current instantaneous value, B phase line current instantaneous value and C phase line current instantaneous value in the current frequency period in the line current real-time monitoring data are obtained, so as to calculate the line voltage effective value, the active power and the apparent power of the target AC induction motor in the current frequency period.

[0040] It should be noted that the frequency period refers to the time required for the completion of a complete waveform change of the frequency AC, which is the inverse of the frequency, and is related to the frequency of the AC input to the target AC induction motor.

[0041] The line voltage effective value is a core parameter for measuring the power supply voltage level of three-phase AC power system, evaluating power quality and ensuring normal operation of motor and other loads. In this embodiment, the calculation formula of the line voltage effective value is:

[0042] ​;Formula (1)

[0043] in, The effective value of the line voltage of the target AC induction motor in the current power frequency cycle; The effective value of the AB phase line voltage of the target AC induction motor in the current power frequency cycle; The effective value of the BC phase line voltage of the target AC induction motor in the current power frequency cycle; The effective value of the CA phase line voltage of the target AC induction motor in the current power frequency cycle; For the target AC induction motor in the current power frequency cycle, the [number]th ... The instantaneous values ​​of the AB phase line voltage at each sampling time; For the target AC induction motor in the current power frequency cycle, the [number]th ... The instantaneous values ​​of the BC phase line voltage at each sampling time; For the target AC induction motor in the current power frequency cycle, the [number]th ... The instantaneous value of the CA phase line voltage at each sampling time; The number of samples taken from the target AC induction motor during the current power frequency cycle.

[0044] Active power characterizes the power actually consumed or used for work by the load. It directly reflects the mechanical power output by the target AC induction motor plus internal losses (including stator copper losses, rotor copper losses, iron losses, mechanical losses, and stray losses). It is crucial for evaluating the load condition of the target AC induction motor. In this embodiment, the formula for calculating active power is:

[0045] ;Formula (2)

[0046] in, The active power of the target AC induction motor in the current power frequency cycle; For the target AC induction motor in the current power frequency cycle, the [number]th ... The instantaneous values ​​of the AB phase line voltages at each sampling time. For the target AC induction motor in the current power frequency cycle, the [number]th ... The instantaneous value of the A-phase line current at each sampling moment; For the target AC induction motor in the current power frequency cycle, the [number]th ... The instantaneous values ​​of the BC phase line voltage at each sampling time. For the target AC induction motor in the current power frequency cycle, the [number]th ... The instantaneous value of the B-phase line current at each sampling moment; For the target AC induction motor in the current power frequency cycle, the [number]th ... The instantaneous value of the CA phase line voltage at each sampling time. For the target AC induction motor in the current power frequency cycle, the [number]th ... The instantaneous value of the C-phase line current at each sampling moment; The number of samples taken from the target AC induction motor during the current power frequency cycle.

[0047] Apparent power is used to characterize the total power capacity required by the target AC induction motor, including active power and reactive power. In this embodiment, the formula for calculating the apparent power is:

[0048] ;Formula (3)

[0049] ;Formula (4)

[0050] in, The apparent power of the target AC induction motor in the current power frequency cycle; The effective value of the line voltage of the target AC induction motor in the current power frequency cycle; The effective value of the line current of the target AC induction motor in the current power frequency cycle; The effective value of the A-phase line current of the target AC induction motor in the current power frequency cycle; The effective value of the B-phase line current of the target AC induction motor in the current power frequency cycle; The effective value of the C-phase line current of the target AC induction motor in the current power frequency cycle; For the target AC induction motor in the current power frequency cycle, the [number]th ... The instantaneous value of the A-phase line current at each sampling moment; For the target AC induction motor in the current power frequency cycle, the [number]th ... The instantaneous value of the B-phase line current at each sampling moment; For the target AC induction motor in the current power frequency cycle, the [number]th ... The instantaneous value of the C-phase line current at each sampling moment; The number of samples taken from the target AC induction motor during the current power frequency cycle.

[0051] ②Calculate the power factor of the target AC induction motor in the current power frequency cycle in real time based on the active power and the apparent power.

[0052] Specifically, the power factor is a key indicator for measuring the energy utilization efficiency and power quality of a three-phase AC power system. A decrease in the power factor indicates that the target AC induction motor is currently operating in a state of high reactive power and low efficiency. Together with a low debt ratio, this suggests that there is room and necessity to reduce the excitation current and improve efficiency by stepping down the voltage. In this embodiment, the formula for calculating the power factor is:

[0053] Equation (5)

[0054] wherein, is the power factor of the target AC induction motor in the current power frequency cycle; is the active power of the target AC induction motor in the current power frequency cycle; is the apparent power of the target AC induction motor in the current power frequency cycle.

[0055] ③According to the active power and the rated active power of the target AC induction motor, the load rate of the target AC induction motor in the current power frequency cycle is calculated in real time.

[0056] Specifically, the load rate refers to the ratio of the actual output power of the target AC induction motor to its rated output power, and is used to measure whether the target AC induction motor is running at "full load", "light load" or "overload". In this embodiment, the calculation formula of the load rate is:

[0057] Equation (6)

[0058] wherein, is the load rate of the target AC induction motor in the current power frequency cycle; is the rated active power of the target AC induction motor, , is the rated voltage value of the target AC induction motor, is the rated current value of the target AC induction motor, is the rated power factor of the target AC induction motor.

[0059] ④According to the line voltage real-time monitoring data and the line current real-time monitoring data, the current unbalance degree of the target AC induction motor in the current power frequency cycle is calculated in real time.

[0060] The current unbalance degree refers to the degree of inconsistency between the effective values of three-phase currents. When the three-phase currents of the target AC induction motor are unbalanced, it indicates that there is an asymmetric heat and stress inside the motor. At this time, if the voltage is further reduced, the overall electromagnetic torque and overload capacity of the motor will be further weakened, which may further deteriorate the working condition of the overheated winding and greatly increase the risk of burning the motor. Therefore, if the current unbalance degree exceeds the standard, the voltage cannot be reduced for power saving. In this embodiment, the calculation formula of the current unbalance degree is:

[0061] Equation (7)

[0062] wherein, the line voltage effective value of the target AC induction motor in the current power frequency cycle; the A-phase line current effective value of the target AC induction motor in the current power frequency cycle; the B-phase line current effective value of the target AC induction motor in the current power frequency cycle; the C-phase line current effective value of the target AC induction motor in the current power frequency cycle.

[0063] When the line voltage effective value exceeds the preset line voltage threshold value, the power factor is less than the preset power factor threshold value, the load rate is less than the preset load rate threshold value, and the current imbalance degree is less than the preset current imbalance threshold value, it is determined that the target AC induction motor is in a light load state, and the preset voltage reduction and power saving condition is met.

[0064] It should be understood that the loss of the target AC induction motor mainly consists of stator copper loss, rotor copper loss, iron loss, mechanical loss, and stray loss, etc. When the target AC induction motor is in a light load state, its output power is reduced, and at the same time, the rotor copper loss is also reduced but not much. At this time, the iron loss, mechanical loss, and stray loss are basically unchanged, resulting in a great reduction of the motor efficiency and power factor of the target AC induction motor. If the terminal voltage of the target AC induction motor is appropriately reduced when it is in a light load state, the stator copper loss, iron loss, mechanical loss, and stray loss, etc. can be effectively reduced, thereby effectively reducing the overall loss of the target AC induction motor and improving the motor efficiency and power factor. Therefore, the present application realizes timely determination of the target AC induction motor meeting the voltage reduction and power saving condition by real-time monitoring of the load change and power factor change of the target AC induction motor when it is in a light load state.

[0065] In the present embodiment, when the line voltage effective value of the target AC induction motor in the current power frequency cycle obtained by real-time calculation exceeds the preset line voltage threshold value, and the power factor is less than the preset power factor threshold value, and the load rate is less than the preset load rate threshold value, and the current imbalance degree is less than the preset current imbalance threshold value, it is determined that the target AC induction motor is in a light load state, i.e. the preset voltage reduction and power saving condition is met. The terminal voltage of the target AC induction motor can be reduced to reduce the overall loss of the target AC induction motor and improve the motor efficiency and power saving rate of the target AC induction motor.

[0066] Preferably, the line voltage threshold value can be preset as The power factor threshold value can be preset as 0.75, the load rate threshold value can be preset as 50%, and the current imbalance threshold value can be preset as 5%. It should be noted that each threshold value can be set according to user requirements and experimental data, and the present application does not make specific limitations.

[0067] Step S3: If the target AC induction motor meets the voltage reduction and power saving condition, the target line voltage effective value of the target AC induction motor is calculated based on the pre-trained motor voltage regulation parameter prediction model according to the line voltage real-time monitoring data, the line current real-time monitoring data and the motor environment real-time monitoring data, and a voltage regulation control signal is generated accordingly.

[0068] In an embodiment, as shown in FIG. 1, the motor voltage regulation parameter prediction model comprises an input layer, a multi-branch hybrid network layer, a long short-term memory network layer, an attention layer, a full connection layer and an output layer connected in sequence. Figure 4

[0069] The input layer is used to receive time series feature data of the input model and perform data standardization and other preprocessing operations before passing to the subsequent long short-term memory network layer. The input time series feature data includes but is not limited to the line voltage real-time monitoring data, the line current real-time monitoring data and the motor environment real-time monitoring data.

[0070] The multi-branch hybrid network layer is used to extract and learn features of each time series feature data respectively and generate fused time series feature data.

[0071] Specifically, the multi-branch hybrid network layer comprises a first branch network, a second branch network, a third branch network and a fusion layer. The first branch network is connected to the input layer and is used to extract features of the standardized line voltage real-time monitoring data and line current real-time monitoring data, learn the correlation between the features, and generate first time series feature data; the second branch network is connected to the input layer and is used to calculate the average power, power factor, load rate, motor loss, motor efficiency change and power saving rate of a preset time series window in real time according to the standardized line voltage real-time monitoring data and line current real-time monitoring data, and extract and learn features to generate second time series feature data; the third branch network is connected to the input layer and is used to extract and learn features of the standardized motor environment real-time monitoring data to generate third time series feature data; and the fusion layer is connected to the first branch network, the second branch network and the third branch network respectively, and is used to fuse the first time series feature data, the second time series feature data and the third time series feature data, learn the fused features, and generate fused time series feature data.

[0072] ​The long short-term memory network layer is connected to the fusion layer, is used for effectively learning long-term dependence in the fusion time sequence feature data, and embeds motor parameters and working condition parameters of the target alternating current induction motor for multi-scale processing to generate multi-scale feature data.

[0073] The attention layer is used for identifying one or more key features in the multi-scale time sequence feature data and performing focused learning to generate key feature data.

[0074] The full connection layer is used for predicting and outputting the target line voltage effective value of the target alternating current induction motor under the current working condition according to the key feature data.

[0075] In an embodiment, the motor voltage regulation parameter prediction model can be obtained based on deep learning model training, and the specific training method includes the following steps.

[0076] ①Obtain motor line voltage time sequence data, motor line current time sequence data and motor environment time sequence data under a plurality of historical working conditions, and label optimized motor line voltage effective value and optimized motor power saving rate of each historical working condition to construct a supervised learning training data set.

[0077] ②According to the training sample data set, a converged motor voltage regulation parameter basic prediction model is trained based on the defined network structure of the motor voltage regulation parameter prediction model.

[0078] ③The motor voltage regulation parameter basic prediction model is migrated to the target alternating current induction motor, target line voltage time sequence data, target line current time sequence data and target motor environment time sequence data of the target alternating current induction motor under a plurality of historical working conditions are obtained to continue training the motor voltage regulation parameter basic prediction model, and a transfer learning training data set is constructed to train a converged motor voltage regulation parameter prediction model.

[0079] ④The motor voltage regulation parameter prediction model is deployed to the real environment of the target alternating current induction motor, the target line voltage effective value of the target alternating current induction motor is predicted according to the input line voltage real-time monitoring data, line current real-time monitoring data and motor environment real-time monitoring data, and the motor voltage regulation parameter prediction model is dynamically optimized according to the power saving rate of the target alternating current induction motor after voltage reduction.

[0080] After the motor control module calculates the target line voltage effective value of the target alternating current induction motor based on the motor voltage regulation parameter prediction model, the corresponding voltage regulation control signal can be generated according to the target line voltage effective value and sent to the motor voltage regulation module.

[0081] As Figure 1As shown, the motor voltage regulating module is connected to the motor control module. In an embodiment, the motor voltage regulating module can employ a three-phase thyristor. The three-phase thyristor includes three groups of anti-parallel thyristors, each group of which can be used to control one phase of alternating current. A thyristor is a semi-controlled power electronic device that includes a plurality of silicon-controlled devices that can be turned on after a trigger pulse is applied to the gate of the thyristor and turned off when the anode-cathode current approaches zero. The three-phase thyristor is connected to the input of the target AC induction motor, i.e., connected to the input circuit of the target AC induction motor, and in a specific embodiment, the three-phase thyristor can be connected to the target AC induction motor through a current transformer in the current monitoring circuit, as shown. Figure 2 The three-phase thyristor is used to obtain the target line voltage effective value of the target AC induction motor according to the received voltage regulating control signal and adjust the conduction time of each thyristor to adjust the output current and the terminal voltage applied to the target AC induction motor.

[0082] The present application determines the terminal voltage and stator current of the target AC induction motor in real time through the motor monitoring module, tracks the load change of the target AC induction motor, and calculates and outputs the target line voltage effective value based on the motor voltage regulating parameter prediction model through the motor control module to apply the optimization control principle and adjust the terminal voltage and stator current input to the target AC induction motor in time, so that the target AC induction motor is always in the best working state, reduces the energy consumption of the target AC induction motor, and improves the motor efficiency and power saving rate. Experiments have shown that the power saving rate of the target AC induction motor can reach 15-40%, which is suitable for power saving control of various AC induction motors with rated line voltages of 220V, 380V, and 630V, and can be widely used in various power equipment and machining equipment, such as fans, water pumps, air compressors, air conditioning compressors, punching machines, machine tools, lathes, milling machines, grinding machines, metal crushing machines, granulators, injection molding machines, extruders, bobbin machines, weaving machines, rotary machines, elevators, etc.

[0083] In an embodiment, the motor voltage regulating and power saving device further comprises a motor start-stop control module.

[0084] Specifically, the motor start-stop control module comprises a frequency converter. The frequency converter is connected to the input end of the target AC induction motor, such as being connected to the target AC induction motor through the three-phase thyristor and the current transformer. The frequency converter is used to smoothly increase the terminal voltage and frequency of the target induction motor to a preset value when the target AC induction motor starts, and to smoothly decrease the terminal voltage and frequency of the target induction motor to zero when the target AC induction motor stops, so as to eliminate the starting impact current, realize motor soft start and soft stop, avoid the impact of large current on the motor, prolong the service life of the motor, and improve the automation level of the motor.

[0085] In an embodiment, the motor voltage reduction and power saving device further comprises an energy storage module. The energy storage module is connected to the output end of the target AC induction motor, and is used to store the electric energy generated due to the rotor speed exceeding the synchronous speed of the stator rotating magnetic field when the target AC induction motor is braked at a reduced speed under the drive of the frequency converter, for recycling. Specifically, the energy storage module comprises a capacitor and a lithium battery pack.

[0086] In this embodiment, the energy storage module can store the electric energy converted from mechanical energy when the target AC induction motor is decelerated, especially when it is braked, for recycling, thereby effectively preventing the waste of electric energy and further improving the energy saving effect of the target AC induction motor.

[0087] It should be understood that the division of modules or units in the embodiments of the present application is illustrative, and is only a logical function division. When actually implemented, another division mode can be used. In addition, each functional module / unit in each embodiment of the present application can be integrated in one processor, or can be physically separated, or two or more modules, units can be integrated in one module or unit. The integrated module or unit can be realized in the form of hardware or in the form of a software functional module.

[0088] As shown in Figure 5 , a structure schematic diagram of an intelligent AC induction motor system in an embodiment of the present application is shown. The intelligent AC induction motor system in this embodiment comprises an AC induction motor and a motor voltage reduction and power saving device connected to the AC induction motor.

[0089] In an embodiment, the AC induction motor can be built-in with a compensator, which is used to compensate for the reactive power generated by the motor, thereby improving the power factor of the AC induction motor.

[0090] In this embodiment, the motor voltage reduction and power saving device is consistent with the motor voltage reduction and power saving device provided in each embodiment of the above device. For brevity, it will not be described here.

[0091] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

[0092] In summary, the present application provides a motor voltage reduction and power saving device and an intelligent alternating current induction motor system. The motor monitoring module monitors and collects the line voltage real-time monitoring data, the line current real-time monitoring data and the motor environment real-time monitoring data of the target alternating current induction motor, and the motor control module, such as a microcontroller, calculates the target line voltage effective value of the target alternating current induction motor based on the pre-trained motor voltage regulation parameter prediction model when the target alternating current induction motor meets the voltage reduction and power saving condition, and generates a voltage regulation control signal to control the motor voltage regulation module to adjust the terminal voltage of the target alternating current induction motor to the target line voltage effective value. The present application has the following beneficial effects: applying the optimal control principle, timely adjusting the terminal voltage and stator current of the input target alternating current induction motor, keeping the target alternating current induction motor in the best working state, reducing the motor energy consumption, improving the motor efficiency and power saving rate, and solving the technical problem of the existing alternating current induction motor with reduced efficiency under light load.

[0093] The above embodiments only exemplarily illustrate the principles and effects of the present application, and are not used to limit the present application. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes completed by those skilled in the art without departing from the spirit and technical idea disclosed by the present application should be covered by the claims of the present application.

Claims

1. A motor voltage reduction and power saving device, characterized by comprising: The method comprises the steps of: a motor monitoring module connected to a target AC induction motor, comprising: an end voltage monitoring circuit, a current monitoring circuit, and an environment monitoring circuit, respectively used for real-time acquisition of line voltage real-time monitoring data, line current real-time monitoring data, and motor environment real-time monitoring data of the target AC induction motor based on a preset sampling frequency; a motor control module connected to the motor monitoring module, used for calculating a target line voltage effective value of the target AC induction motor based on a pre-trained motor voltage regulation parameter prediction model when it is determined that the target AC induction motor meets a voltage reduction and power saving condition according to the line voltage real-time monitoring data, the line current real-time monitoring data, and the motor environment real-time monitoring data, and generating a voltage regulation control signal accordingly; a motor voltage regulation module connected to the motor control module and the target AC induction motor, used for adjusting the end voltage of the target AC induction motor to the target line voltage effective value according to the voltage regulation control signal.

2. The motor voltage reducing and power saving device according to claim 1, wherein The method for determining that the target AC induction motor meets the voltage reduction and power saving condition comprises the steps of: real-time calculation of line voltage effective value, active power, and apparent power of the target AC induction motor in a current power frequency cycle according to the line voltage real-time monitoring data and the line current real-time monitoring data; real-time calculation of power factor of the target AC induction motor in the current power frequency cycle according to the active power and the apparent power; real-time calculation of load rate of the target AC induction motor in the current power frequency cycle according to the active power and a rated active power of the target AC induction motor; real-time calculation of current unbalance degree of the target AC induction motor in the current power frequency cycle according to the line voltage real-time monitoring data and the line current real-time monitoring data; determination that the target AC induction motor is in a light load state and meets a preset voltage reduction and power saving condition when the line voltage effective value exceeds a preset line voltage threshold value, the power factor is less than a preset power factor threshold value, the load rate is less than a preset load rate threshold value, and the current unbalance degree is less than a preset current unbalance threshold value.

3. The motor voltage reducing and power saving device according to claim 1, wherein The motor voltage regulation parameter prediction model comprises: an input layer used for receiving the line voltage real-time monitoring data, the line current real-time monitoring data, and the motor environment real-time monitoring data, and performing data preprocessing operations on each time series feature data; a multi-branch hybrid network layer connected to the input layer, used for performing feature extraction and feature learning on each time series feature data respectively, and generating fused time series feature data; a long short-term memory network layer connected to the multi-branch hybrid network layer, used for effectively learning long-term dependencies in the fused time series feature data, and embedding motor parameters and working condition parameters of the target AC induction motor for multi-scale processing to generate multi-scale feature data; an attention layer connected to the long short-term memory network layer, used for identifying one or more key features in the multi-scale time series feature data and performing focused learning to generate key feature data; A full connection layer connected to the attention layer is configured to predict and output a target line voltage effective value of the target AC induction motor under a current working condition according to the key feature data.

4. The motor voltage reducing and power saving device according to claim 3, wherein The multi-branch hybrid network layer includes: A first branch network connected to the input layer is configured to extract and learn features from the normalized line voltage real-time monitoring data and the line current real-time monitoring data, and generate first time-series feature data; A second branch network connected to the input layer is configured to extract and learn features from the normalized line voltage real-time monitoring data and the line current real-time monitoring data, and generate second time-series feature data, including average power, power factor, load rate, motor loss, motor efficiency change, and power saving rate of a preset time-series window; A third branch network connected to the input layer is configured to extract and learn features from the normalized motor environment real-time monitoring data, and generate third time-series feature data; A fusion layer connected to the first branch network, the second branch network, and the third branch network is configured to fuse the first time-series feature data, the second time-series feature data, and the third time-series feature data, and generate fused time-series feature data.

5. The motor voltage reducing and power saving device according to claim 4, wherein The training method of the motor voltage regulation parameter prediction model includes: Obtaining motor line voltage time-series data, motor line current time-series data, and motor environment time-series data under multiple historical working conditions, and labeling optimized motor line voltage effective value and optimized motor power saving rate of each historical working condition to construct a supervised learning training data set; Training a converged motor voltage regulation parameter basic prediction model based on a predefined network structure of the motor voltage regulation parameter prediction model according to the training sample data set; Migrating the motor voltage regulation parameter basic prediction model to the target AC induction motor, obtaining target line voltage time-series data, target line current time-series data, and target motor environment time-series data of the target AC induction motor under multiple historical working conditions to continue training the motor voltage regulation parameter basic prediction model, and constructing a transfer learning training data set to train a converged motor voltage regulation parameter prediction model; Deploying the motor voltage regulation parameter prediction model to a real environment of the target AC induction motor, predicting a target line voltage effective value of the target AC induction motor according to input line voltage real-time monitoring data, line current real-time monitoring data, and motor environment real-time monitoring data, and dynamically optimizing the motor voltage regulation parameter prediction model according to the power saving rate of the target AC induction motor after voltage reduction.

6. The motor voltage reducing and power saving device according to claim 1, wherein The motor voltage regulation module includes: A three-phase thyristor including three groups of anti-parallel thyristors connected to an input end of the target AC induction motor, configured to obtain a target line voltage effective value of the target AC induction motor according to the received voltage regulation control signal, and adjust the conduction time of each thyristor to adjust the output current and the terminal voltage applied to the target AC induction motor.

7. The motor voltage reduction and power saving device of claim 1, wherein The terminal voltage monitoring circuit comprises a voltage transformer; the voltage transformer is connected in parallel to the input end of the target AC induction motor and connected to the motor control module, for monitoring the three-phase terminal voltage variation of the input end of the target AC induction motor in real time, and collecting the line voltage real-time monitoring data and sending to the motor control module in real time; The current monitoring circuit comprises a current transformer; the current transformer is connected in series to the input end of the target AC induction motor and connected to the motor control module, for monitoring the three-phase AC current flowing into the stator winding of the target AC induction motor in real time, and collecting the line current real-time monitoring data and sending to the motor control module in real time; The environment monitoring unit comprises one or more temperature sensors and one or more humidity sensors, which are connected to the target AC induction motor and the motor control module respectively, for monitoring the temperature variation and humidity variation of the environment around the target AC induction motor in real time, and generating motor temperature real-time monitoring data and motor humidity real-time monitoring data to generate the motor environment real-time monitoring data and send to the motor control module.

8. The motor voltage reducing and power saving device according to claim 1, wherein The motor voltage reduction and power saving device further comprises: A start-stop control module comprising a frequency converter connected to the input end of the target AC induction motor, for smoothly rising the terminal voltage and frequency of the target induction motor to a preset value when the target AC induction motor starts, and smoothly falling the terminal voltage and frequency of the target induction motor to zero when the target AC induction motor stops.

9. The motor voltage reducing and power saving device according to claim 8, wherein The motor voltage reduction and power saving device further comprises: An energy storage module connected to the output end of the target AC induction motor, for storing the electric energy generated when the rotor speed exceeds the synchronous speed of the stator rotating magnetic field when the target AC induction motor is braked under the drive of the frequency converter, for recycling.

10. An intelligent AC induction motor system characterized by, It comprises: An AC induction motor and a motor voltage reduction and power saving device connected to the AC induction motor; wherein the motor voltage reduction and power saving device comprises: A motor monitoring module connected to the AC induction motor, comprising a terminal voltage monitoring circuit, a current monitoring circuit and an environment monitoring circuit, for collecting line voltage real-time monitoring data, line current real-time monitoring data and motor environment real-time monitoring data of the AC induction motor in real time based on a preset sampling frequency; A motor control module connected to the motor monitoring module, for calculating the target line voltage effective value of the AC induction motor based on a pre-trained motor voltage regulation parameter prediction model when determining that the AC induction motor meets the voltage reduction and power saving condition according to the line voltage real-time monitoring data, the line current real-time monitoring data and the motor environment real-time monitoring data, and generating a voltage regulation control signal accordingly; A motor voltage regulation module connected to the motor control module and the AC induction motor, for adjusting the terminal voltage of the AC induction motor to the target line voltage effective value according to the voltage regulation control signal.

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