Single-frequency-converter multi-motor control method and system

Abstract

The invention discloses a single-frequency-converter multi-motor control method and system, relates to the technical field of frequency converters, and discloses the single-frequency-converter multi-motor control method which is applied to the single-frequency-converter multi-motor control system connected with a power grid. The power supply end of the frequency converter is connected with a power grid, the control end of the frequency converter is connected with the variable frequency motor, the power frequency motor is connected with the power grid, and the method comprises the steps that parameter information of the single-frequency-converter multi-motor control system is obtained, and the parameter information comprises the output frequency of the frequency converter and the pressure set value and the pressure feedback value of the single-frequency-converter multi-motor control system; a motor control instruction is determined according to the output frequency, the pressure given value and the pressure feedback value, motor control is carried out on target motors according to the motor control instruction, and the target motors comprise a variable frequency motor and a power frequency motor. According to the invention, the cost of multi-motor control is reduced.

Description

Technical Field

[0001] This application relates to the field of frequency converter technology, and in particular to a single frequency converter multi-motor control method and system. Background Technology

[0002] As frequency converters are used more and more widely in motors, users are also putting forward higher requirements for frequency converters to control multiple motors.

[0003] Traditional multi-motor control (i.e., controlling multiple motors via frequency converters) involves configuring a separate frequency converter for each motor. This method results in high costs for multi-motor control because each motor requires its own frequency converter.

[0004] The above content is only used to help understand the technical solution of this application and does not represent an admission that the above content is prior art. Summary of the Invention

[0005] The main purpose of this application is to provide a single frequency converter multi-motor control method and system, which aims to solve the technical problem of high cost in multi-motor control.

[0006] To achieve the above objectives, this application provides a single-frequency converter multi-motor control method. This method is applied to a single-frequency converter multi-motor control system connected to a power grid. The single-frequency converter multi-motor control system includes a single frequency converter, a variable-frequency motor, and at least one power-frequency motor. The power supply terminal of the frequency converter is connected to the power grid, the control terminal of the frequency converter is connected to the variable-frequency motor, and the power-frequency motor is connected to the power grid. The single-frequency converter multi-motor control method includes:

[0007] Obtain the parameter information of the single frequency converter multi-motor control system, wherein the parameter information includes the output frequency of the frequency converter, the pressure setpoint and pressure feedback value of the single frequency converter multi-motor control system;

[0008] The motor control command is determined based on the output frequency, the pressure setpoint, and the pressure feedback value, and the target motor is controlled according to the motor control command. The target motor includes the variable frequency motor and the fixed frequency motor.

[0009] In one embodiment, the step of determining the motor control command based on the output frequency, the pressure setpoint, and the pressure feedback value includes:

[0010] Determine a first numerical difference between the pressure setpoint and the pressure feedback value;

[0011] If the output frequency is greater than or equal to the preset motor frequency, and the first numerical difference is greater than the preset motor pressure tolerance, then a preset timing command is triggered to determine the first duration.

[0012] If the first duration is greater than the preset motor delay time, then the motor control command is determined to be a motor addition command.

[0013] In one embodiment, the target motor further includes a new motor located near the serial number position of the variable frequency motor, a new variable frequency contactor for connecting the new motor to the variable frequency drive, a first variable frequency contactor for connecting the variable frequency motor to the variable frequency drive, and a first grid contactor for connecting the variable frequency motor to the power grid. The step of controlling the target motor according to the motor control command includes:

[0014] After controlling the variable frequency motor to operate at high speed based on the motor control command, the first variable frequency contactor is controlled to disconnect the variable frequency motor from the frequency converter, and after a preset opening delay time, the new variable frequency contactor is controlled to connect the new motor and the frequency converter.

[0015] After a preset closing delay time, the first grid contactor is controlled to connect the variable frequency motor and the grid.

[0016] In one embodiment, the step of determining the motor control command based on the output frequency, the pressure setpoint, and the pressure feedback value further includes:

[0017] Determine a second numerical difference between the pressure feedback value and the pressure setpoint;

[0018] If the output frequency is less than the preset motor frequency and the second numerical difference is greater than the preset motor pressure tolerance, then a preset timing command is triggered to determine the second duration.

[0019] If the second duration is greater than the preset motor reduction delay time, then the motor control command is determined to be a motor reduction command.

[0020] In one embodiment, the step of controlling the target motor according to the motor control command includes:

[0021] The power frequency motor that is furthest from the serial number of the variable frequency motor is identified as the motor to be reduced, wherein the motor to be reduced is connected to the power grid through a contactor for the power grid to be reduced;

[0022] Based on the motor control command, the contactor of the power grid to be reduced is controlled to disconnect the connection between the power grid and the motor to be reduced.

[0023] In one embodiment, the single-frequency converter multi-motor control system further includes a second grid contactor for connecting the power frequency motor to the power grid. After the step of performing motor control on the target motor according to the motor control command, the system includes:

[0024] If a shutdown command is received, the first frequency converter contactor corresponding to the frequency converter motor is determined, and the second power grid contactor is controlled to disconnect the power frequency motor from the power grid based on the shutdown command. After the frequency converter stops outputting, the first frequency converter contactor is controlled to disconnect the frequency converter motor from the frequency converter.

[0025] In one embodiment, before the step of obtaining the parameter information of the single-frequency converter multi-motor control system, the following steps are included:

[0026] If a power-on command is received, the first variable frequency contactor corresponding to the variable frequency motor is determined, and the first variable frequency contactor is controlled to connect the variable frequency motor and the variable frequency drive based on the power-on command. After a preset closing delay time, the step of obtaining the parameter information of the single variable frequency drive multi-motor control system is executed.

[0027] In one embodiment, the step of determining the motor control command based on the output frequency, the pressure setpoint, and the pressure feedback value further includes:

[0028] The absolute value of the difference between the pressure setpoint and the pressure feedback value is determined as the third numerical difference;

[0029] If the output frequency is less than the preset motor-increasing frequency and greater than the preset motor-decreasing frequency, then a motor control command is determined based on the third numerical difference, wherein the preset motor-increasing frequency is greater than the preset motor-decreasing frequency.

[0030] Furthermore, to achieve the above objectives, this application also provides a single-frequency converter multi-motor control system, which includes a single frequency converter, a variable-frequency motor, at least one power-frequency motor, and a controller. The power supply terminal of the frequency converter is connected to the power grid, the control terminal of the frequency converter is connected to the variable-frequency motor, the power-frequency motor is connected to the power grid, and the controller is connected to the frequency converter, the variable-frequency motor, and the power-frequency motor. The controller includes:

[0031] The information acquisition module is used to acquire parameter information of the single frequency converter multi-motor control system, wherein the parameter information includes the output frequency of the frequency converter, the pressure setpoint and pressure feedback value of the single frequency converter multi-motor control system;

[0032] The motor control module is used to determine motor control commands based on the output frequency, the pressure setpoint, and the pressure feedback value, and to control the target motor according to the motor control commands, wherein the target motor includes the variable frequency motor and the fixed frequency motor.

[0033] In one embodiment, the frequency converter includes multiple relay output terminals and relays corresponding to the relay output terminals. Each relay output terminal is connected to a motor via the relay control as the frequency converter motor.

[0034] This application provides a single-frequency converter multi-motor control method. This method is applied to a single-frequency converter multi-motor control system connected to a power grid. The single-frequency converter multi-motor control system includes a single frequency converter, a variable-frequency motor, and at least one power-frequency motor. The power supply terminal of the frequency converter is connected to the power grid, the control terminal of the frequency converter is connected to the variable-frequency motor, and the power-frequency motor is also connected to the power grid. The method involves acquiring parameter information of the single-frequency converter multi-motor control system, including the output frequency of the frequency converter, the pressure setpoint of the single-frequency converter multi-motor control system, and the pressure feedback value. Motor control commands are then determined based on the output frequency, the pressure setpoint, and the pressure feedback value. The system controls the target motor according to the motor control command. The target motor includes the variable frequency motor and the fixed frequency motor. Multiple motors are controlled by the variable frequency drive. One motor connected to the variable frequency drive is designated as the variable frequency motor, and the motor connected to the power grid is designated as the fixed frequency motor (not controlled by the variable frequency drive, but can be switched to be controlled by the variable frequency drive). The motor control command is determined based on the obtained output frequency of the variable frequency drive, pressure setpoint, and voltage feedback value. The target motor can be controlled based on the motor control command. The target motor includes both fixed frequency motors and variable frequency motors. In other words, one variable frequency drive can control both fixed frequency motors and variable frequency motors at the same time, thereby avoiding the phenomenon of each motor being controlled by a separate variable frequency drive. This single-frequency converter multi-motor control method can control both variable frequency and fixed frequency motors based on motor control commands, without continuously using the same motor as the frequency converter, thus improving motor lifespan (avoiding wear and tear from continuous frequency converter control). On the other hand, it can directly control multiple motors based on a single frequency converter (different motors can be selected to be connected to the frequency converter for control at the same time), allowing different motors to be controlled as variable frequency motors without the need for multiple frequency converters, thereby reducing the cost of multi-motor control. Attached Figure Description

[0035] Figure 1 This is a flowchart illustrating the first embodiment of the single-frequency converter multi-motor control method of this application;

[0036] Figure 2 This is a schematic diagram of a scenario for the single-frequency converter multi-motor control system of this application;

[0037] Figure 3 This is another scenario diagram of the single-frequency converter multi-motor control system of this application;

[0038] Figure 4 This is a schematic diagram of the controller module in the single-frequency converter multi-motor control system of this application;

[0039] Figure 5 This is a schematic diagram of the hardware operating environment involved in the device in this application;

[0040] Figure 6 This is a schematic diagram of the motor number arrangement in the single-frequency converter multi-motor control method of this application;

[0041] Figure 7 This is another schematic diagram of the motor serial number arrangement for the single-frequency converter multi-motor control method of this application.

[0042] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings.

[0043] Explanation of icon numbers:

[0044] AC, power grid; Q (Q1-Q4), low-voltage circuit breaker; RLY (RLY1-RLY4), relay output terminal; KP (KP1-KP4), relay; M1-Mn, motor; KM2n-1 (KM1, KM3, KM5, KM7), power grid contactor; KM2n (KM2, KM4, KM6, KM8), frequency converter contactor; 10, frequency converter. Detailed Implementation

[0045] It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0046] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0047] In multi-motor control scenarios, each motor requires its own frequency converter for control, as seen in scenarios controlling water pump motors (this can also apply to scenarios where other frequency converters control motors, such as air pumps). In constant pressure water supply systems, while controlling a single water pump (primarily through frequency converter control of the pump motor) is relatively simple, it often cannot meet the demands of large-scale water pressure or flow control in some scenarios. In such cases, increasing the number of pumps can solve this problem. Theoretically, to achieve more precise and stable control of water pressure or flow, the number of frequency converters should increase along with the number of pumps, resulting in a multi-frequency converter, multi-pump control system. However, frequency converters are quite expensive. If each pump is equipped with a separate frequency converter, the cost of the entire water supply system will increase significantly, as will the system complexity and maintenance costs. Therefore, a solution has been developed where multiple pumps share a single frequency converter, controlling the start and stop of multiple pumps with a single converter. This system is called a single-frequency converter, multi-pump control system, which can greatly simplify the system and reduce costs. However, commonly used single-frequency converter multi-pump control systems often adopt a fixed frequency converter pump scheme, that is, the pump controlled by the frequency converter (i.e., the frequency converter pump) is always fixed. Over time, this will cause the frequency converter pump to wear out more severely than other pumps, affecting the control performance of the system and the service life of the frequency converter pump.

[0048] Therefore, based on the shortcomings of the above multi-motor control schemes, this application proposes a single-frequency converter multi-motor control. The main solution of this application embodiment is: to control multiple motors through a frequency converter, and to designate one motor connected to the frequency converter as a variable frequency motor, and the motor connected to the power grid as a power frequency motor (not controlled by the frequency converter, but can be switched to frequency converter control). The motor control command is determined based on the obtained output frequency of the frequency converter, the pressure setpoint, and the voltage feedback value. The target motor can be controlled based on the motor control command. The target motor includes a power frequency motor and a variable frequency motor. That is, at this time, one frequency converter can control both the power frequency motor and the variable frequency motor at the same time, thereby avoiding the phenomenon of each motor being configured with a frequency converter for control. This single-frequency converter multi-motor control method can control both variable frequency and fixed frequency motors based on motor control commands, without continuously using the same motor as the frequency converter, thus improving motor lifespan (avoiding wear and tear from continuous frequency converter control). On the other hand, it can directly control multiple motors based on a single frequency converter (different motors can be selected to be connected to the frequency converter for control at the same time), allowing different motors to be controlled as variable frequency motors without the need for multiple frequency converters, thereby reducing the cost of multi-motor control.

[0049] It should be noted that the executing entity in this embodiment can be a computing service device with data processing, network communication, and program execution functions, such as a tablet computer, personal computer, or mobile phone, or a device capable of performing the above functions, such as a single-frequency converter multi-motor control device. The following description uses a single-frequency converter multi-motor control device as an example to illustrate this embodiment and the subsequent embodiments.

[0050] Based on this, this application provides a single-frequency converter multi-motor control method. This method is applied to a single-frequency converter multi-motor control system connected to the power grid. The single-frequency converter multi-motor control system includes a single frequency converter, a variable-frequency motor, and at least one power-frequency motor. The power supply terminal of the frequency converter is connected to the power grid, the control terminal of the frequency converter is connected to the variable-frequency motor, and the power-frequency motor is connected to the power grid. (Refer to...) Figure 1 , Figure 1 This is a flowchart illustrating the first embodiment of the single-frequency converter multi-motor control method of this application.

[0051] Reference Figure 1 This application provides a single-frequency converter multi-motor control method. In the first embodiment of the single-frequency converter multi-motor control method, the single-frequency converter multi-motor control method includes:

[0052] Step S10: Obtain parameter information of the single frequency converter multi-motor control system, wherein the parameter information includes the output frequency of the frequency converter, the pressure setpoint and pressure feedback value of the single frequency converter multi-motor control system;

[0053] In this embodiment, when the entire single-frequency converter multi-motor control system is in operation, it can include two motors. One motor is directly connected to the frequency converter as a variable frequency motor, meaning the frequency converter controls the variable frequency motor. The other motor is directly connected to the power grid as a power frequency motor, meaning the frequency converter does not control the power frequency motor. It is worth noting that in the most extreme case, there can be only one variable frequency motor, allowing for individual control of that motor using a single frequency converter. In other words, when the entire system is working, on the one hand, only one frequency converter can be used to reduce the cost of multi-motor control. On the other hand, the parameter information of the single frequency converter multi-motor control system can be obtained during operation, so as to control the connection status of the power frequency motors or variable frequency motors in the entire system based on the parameter information. The output frequency of the frequency converter refers to the output frequency of the frequency converter when controlling the variable frequency motor. For example, when the frequency is A, the controlled motor speed is A1, and when the frequency is A, the controlled motor efficiency is A2. That is, the operating parameters of the variable frequency motor can be understood, so as to clearly know whether it meets the user's needs. The parameters of the frequency converter include speed setpoint, speed feedback value, current setpoint, current feedback value, etc., which can understand the working status of the variable frequency motor. The parameter information here refers to the pressure setpoint and pressure feedback value, that is, the given pressure value and the actual feedback pressure value of the variable frequency motor. The control can be configured to connect the variable frequency motor to the power grid and turn it into a fixed frequency motor, connect the fixed frequency motor to the frequency converter and turn it into a variable frequency motor, and disconnect the fixed frequency motor from the power grid, thus exiting the working state. Since there is at least one control for the variable frequency motor to turn into a fixed frequency motor, the phenomenon of always using a single variable frequency motor can be avoided, thus ensuring the service life of the variable frequency motor.

[0054] Step S20: Determine the motor control command based on the output frequency, the pressure setpoint, and the pressure feedback value, and perform motor control on the target motor according to the motor control command, wherein the target motor includes the variable frequency motor and the fixed frequency motor.

[0055] In this embodiment, after determining the pressure setpoint, pressure feedback value, and output frequency, a motor control command is determined based on these parameters. This command is then used to control the target motor. The motor control command refers to the instruction to add or remove motors or control motor parameters in a single-frequency converter multi-motor control system, such as controlling the speed of a variable frequency motor, adding a motor, or removing a power frequency motor. During the execution of the motor control command, there may be a process of switching from a power frequency motor to a variable frequency motor or vice versa (i.e., the motor is connected to the frequency converter as a variable frequency motor and connected to the power grid as a power frequency motor). The power frequency to variable frequency switching process uses the frequency converter's start-up speed tracking function to search for and obtain the speed of the motor to be switched. Based on this speed, the motor is controlled to run to the setpoint frequency output by the PID (proportional integration differentiation) controller. Taking water pump motor switching as an example, this switching method can avoid excessive water pressure changes and reduce the impact on the water pipes (it is not directly controlled by the frequency converter from the start-up speed). During the switching process from variable frequency to mains frequency, the frequency converter will drive the motor to be switched to a higher speed before switching back to the power grid. Taking water pump motor switching as an example, this switching method can prevent excessive water pressure changes and reduce the impact on water pipes. It is worth noting that in certain situations (such as when the mains frequency motor needs to be controlled due to a fault or other factors), it is possible to stop the current variable frequency motor, switch the mains frequency motor to be switched to a variable frequency motor, and then switch the current variable frequency motor back to a mains frequency motor. In this case, the process of adding and removing motors can be executed sequentially to use the motor to be switched as a variable frequency motor by adding motors, so as to ensure the accuracy of multi-motor control.

[0056] In one embodiment, to ensure the accuracy of motor connection status control, a fixed sequence can be set for adding motors. For example, all motors can be arranged clockwise according to their serial numbers. When the conditions for adding a motor are met, the frequency converter will perform a motor addition operation. After the motor addition is completed, the serial number of the frequency converter motor changes by one position clockwise, and the original frequency converter motor becomes a power frequency motor, i.e., 1, 2, 3, where 3 is the frequency converter motor. Therefore, when adding a motor (the added motor is the motor clockwise from frequency converter motor 3, i.e., the motor serial number is 4), the sequence becomes 1, 2, 3, 4, where 4 is the frequency converter motor. When the conditions for removing a motor are met, the frequency converter will perform a motor removal operation. The motor removal operation will stop the last power frequency motor counting counterclockwise from the frequency converter motors, while the frequency converter motor serial number remains unchanged, i.e., 1, 2, 3, where 3 is the frequency converter motor. Therefore, when removing a motor (the removed motor is the motor counterclockwise, i.e., the motor serial number is 1), the sequence becomes 2, 3, where 3 is the frequency converter motor. It is worth noting that at this time, you can also add the motor in a counterclockwise direction and subtract the motor in a clockwise direction to ensure the accuracy of adding or subtracting the motor.

[0057] In this embodiment, a single-frequency converter multi-motor control method is provided. This method is applied to a single-frequency converter multi-motor control system connected to the power grid. The single-frequency converter multi-motor control system includes a single frequency converter, a variable frequency motor, and at least one power frequency motor. The power supply terminal of the frequency converter is connected to the power grid, the control terminal of the frequency converter is connected to the variable frequency motor, and the power frequency motor is connected to the power grid. The method involves acquiring parameter information of the single-frequency converter multi-motor control system, including the output frequency of the frequency converter, the pressure setpoint of the single-frequency converter multi-motor control system, and the pressure feedback value. Motor control commands are determined based on the output frequency, the pressure setpoint, and the pressure feedback value. The system controls the target motor according to the motor control command. The target motor includes the variable frequency motor and the fixed frequency motor. Multiple motors are controlled by the variable frequency drive. One motor connected to the variable frequency drive is designated as the variable frequency motor, and the motor connected to the power grid is designated as the fixed frequency motor (not controlled by the variable frequency drive, but can be switched to be controlled by the variable frequency drive). The motor control command is determined based on the obtained output frequency of the variable frequency drive, pressure setpoint, and voltage feedback value. The target motor can be controlled based on the motor control command. The target motor includes both fixed frequency motors and variable frequency motors. In other words, one variable frequency drive can control both fixed frequency motors and variable frequency motors at the same time, thereby avoiding the phenomenon of each motor being controlled by a separate variable frequency drive. This single-frequency converter multi-motor control method can control both variable frequency and fixed frequency motors based on motor control commands, without continuously using the same motor as the frequency converter, thus improving motor lifespan (avoiding wear and tear from continuous frequency converter control). On the other hand, it can directly control multiple motors based on a single frequency converter (different motors can be selected to be connected to the frequency converter for control at the same time), allowing different motors to be controlled as variable frequency motors without the need for multiple frequency converters, thereby reducing the cost of multi-motor control.

[0058] Furthermore, based on the first embodiment of this application described above, a second embodiment of the single-frequency converter multi-motor control method of this application is proposed. In this embodiment, step S20, the step of determining the motor control command based on the output frequency, the pressure setpoint, and the pressure feedback value, includes:

[0059] Step S201: Determine the first numerical difference between the pressure setpoint and the pressure feedback value;

[0060] Step S202: If the output frequency is greater than or equal to the preset motor frequency and the first numerical difference is greater than the preset motor pressure tolerance, then a preset timing command is triggered to determine the first duration.

[0061] Step S203: If the first duration is greater than the preset motor delay time, then the motor control command is determined to be the motor addition command.

[0062] In this embodiment, when determining the motor control command (motor addition command), the main step is to determine whether the current variable frequency motor has reached its maximum operating state. For example, for a water pump, this could be checking whether it has reached its maximum water delivery state. At this point, a first numerical difference between the pressure setpoint and the pressure feedback value can be determined. If the output frequency is greater than or equal to a preset motor addition frequency, and the first numerical difference is greater than a preset motor addition pressure tolerance, a preset timing command is triggered to determine a first duration. If the first duration is greater than a preset motor addition delay time, then the motor control command is determined to be a motor addition command. In other words, it is determined that an additional motor is needed to meet user needs. For example, if a wider range of water pressure or flow control is required, it will be determined that a new motor needs to be added to the system to meet the wider range of water pressure or flow control requirements. The pressure setpoint refers to the setpoint value used to control the output of the variable frequency motor, which can be a given current or voltage (motor current and voltage can indirectly represent parameters such as speed). The pressure feedback value refers to the actual feedback value of the variable frequency motor, which can be the feedback current or voltage. The preset motor frequency is the output power value set by the user. The preset motor pressure tolerance is a value set by the user, such as A3. If the first numerical difference between the pressure setpoint and the pressure feedback value is greater than A3, it is determined that the variable frequency motor cannot meet the user's demand for a wider range of water pressure or flow control (because when the variable frequency switches to the mains frequency, other mains frequency motors are already at a higher speed, i.e., a more efficient working state), and an additional motor is needed. The first duration refers to the duration for which the output frequency is greater than or equal to the preset motor frequency, and the first numerical difference is greater than the preset motor pressure tolerance. By setting the duration, misjudgment of commands caused by a short-term increase in demand can be avoided, thus ensuring the accuracy of command determination and subsequent motor control.

[0063] In one embodiment, if any of the above conditions are not met, it will not be determined that an additional motor is needed. In this case, other conditions can also be used for judgment, such as whether the motor in the current system cannot meet the requirements for a wider range of water pressure or flow control (or other requirements, such as speed or air pressure requirements). For example, if the user finds that the air pressure is insufficient when using the air pump, an additional motor corresponding to the air pump will be needed to ensure that the user's needs are met. Other judgment methods are also possible and are not limited here.

[0064] Furthermore, the target motor also includes a new motor near the variable frequency motor serial number position, a new variable frequency contactor for connecting the new motor and the variable frequency drive, a first variable frequency contactor for connecting the variable frequency motor and the variable frequency drive, and a first grid contactor for connecting the variable frequency motor and the power grid. The steps for controlling the target motor according to the motor control command include:

[0065] Step S211: After controlling the variable frequency motor to run at high speed based on the motor control command, control the first variable frequency contactor to disconnect the variable frequency motor from the frequency converter, and control the new variable frequency contactor to connect the new motor and the frequency converter after the preset opening delay time.

[0066] Step S212: After a preset closing delay time, control the first grid contactor to connect the frequency converter motor and the grid.

[0067] In this embodiment, refer to Figure 2 , Figure 2 This is a schematic diagram of a single-frequency converter multi-motor control system according to this application. The frequency converter 10 includes multiple relay output terminals RLY and corresponding relays KP (four in total, where Q is a low-voltage circuit breaker). Each relay output terminal RLY is connected to a motor M1 to Mn via relay KP as a variable frequency motor. Specifically, the frequency converter contactor KM2n on motors M1 to Mn is activated and connected to the frequency converter 10, making this motor a variable frequency motor. Similarly, the power grid contactor KM2n-1 on motors M1 to Mn is activated and connected to the AC power grid, making this motor a power frequency motor. Theoretically, as long as the frequency converter 10 has a sufficient number of relay output terminals RLY, relays KP, and contactors, one frequency converter 10 can control an infinite number of motors. At any given time, at most one motor is connected to the frequency converter 10 via the frequency converter contactor KM2n and directly driven by the frequency converter 10; this is called a variable frequency motor. When the demand (i.e., the setpoint of the process PID output) exceeds the maximum output capacity of the variable frequency motor (user-defined speed / frequency limit), and this continues for a certain period, a motor addition operation will be triggered. This involves adding a power frequency motor connected to the grid to increase the system's total output, and this power frequency motor will be used as a new variable frequency motor. The inverter 10 will adjust the speed of the variable frequency motor according to the demand to balance the output (e.g., water pressure or flow rate of a water pump). When the demand decreases, the inverter 10 will first reduce the output of the variable frequency motor. When the output of the variable frequency motor drops below the minimum output limit and this continues for a certain period, a motor removal operation will be triggered. This involves removing a power frequency motor to reduce the system's total output. The inverter 10 will adjust the speed of the variable frequency motor according to the demand to balance the water pressure or flow rate. It is important to note that all motors must have the same rated power, and all motors are connected to or disconnected from the system based on actual conditions to achieve motor addition / removal control. Further, refer to... Figure 3 , Figure 3This is another schematic diagram of the single-frequency converter multi-motor control system of this application. To ensure that only one frequency converter motor is running at any given time, an interlocking circuit is designed for each set of power frequency and frequency converter contactors. This ensures that at any given time, only one motor is directly driven by the frequency converter. Based on the above circuit design, the relay control circuit design requires that motors be added or removed in a preset order; otherwise, the motor addition or removal operation will fail. It is worth noting that the interlocking circuit can use components such as electromagnetic relays, sensors, and switches, or other circuit designs, to ensure that certain parts of the circuit cannot operate simultaneously under certain conditions, thereby guaranteeing the safety and stability of the equipment.

[0068] In one embodiment, reference is made to Figure 6 , Figure 6 This is a schematic diagram of the motor numbering arrangement in the single-frequency converter multi-motor control method of this application. That is, adding motors involves clockwise increases, and removing motors involves counter-clockwise decreases. (See reference...) Figure 7 , Figure 7 This is another schematic diagram of the motor numbering arrangement in the single-frequency converter multi-motor control method of this application. Specifically, adding motors involves counter-clockwise increments, while removing motors involves clockwise decrements. When adding a new motor, after controlling the frequency converter motor to operate at high speed based on motor control commands, the first frequency converter contactor is controlled to disconnect the frequency converter motor from the frequency converter. That is, after the motor operates at high speed, its connection to the frequency converter is disconnected. After a preset opening delay time, the new frequency converter contactor is controlled to connect the new motor and the frequency converter. Simultaneously, after a preset closing delay time, the first grid contactor is controlled to connect the frequency converter motor and the power grid, thus switching the current frequency converter motor to a power frequency motor and the new motor to a frequency converter motor, thereby realizing the addition of a new motor. It is worth noting that the delay time setting ensures accurate switching, and switching at high speed ensures the accuracy of subsequent switching condition judgments. (Refer to...) Figure 2 Assuming motor 1 is a mains frequency motor and motor 2 is a variable frequency motor, the motor addition operation involves the inverter 10 stopping automatically. After stopping, KP2 (the relay corresponding to the variable frequency motor) is de-energized, controlling KM4 (the contactor corresponding to the variable frequency motor) to open. After a set opening delay time, KP3 (the relay corresponding to the newly added motor) is energized, controlling KM6 (the contactor corresponding to the newly added motor) to close. After another set closing delay time, KP2 is energized, controlling KM3 to close. The inverter 10 then sends a start command, completing the motor addition operation. After the motor addition operation, motors 1 and 2 operate at mains frequency, while motor 3 operates at variable frequency.

[0069] Furthermore, based on the first and / or second embodiments of this application described above, a third embodiment of the single-frequency converter multi-motor control method of this application is proposed. In this embodiment, step S20, the step of determining the motor control command based on the output frequency, the pressure setpoint, and the pressure feedback value, further includes:

[0070] Step S221: Determine the second numerical difference between the pressure feedback value and the pressure setpoint;

[0071] Step S222: If the output frequency is less than the preset motor frequency and the second numerical difference is greater than the preset motor pressure tolerance, then a preset timing command is triggered to determine the second duration.

[0072] Step S223: If the second duration is greater than the preset motor reduction delay time, then the motor control command is determined to be a motor reduction command.

[0073] In this embodiment, when determining the motor control command (motor reduction command), the main step is to determine whether the current variable frequency motor has reached its minimum operating state. For example, for a water pump, this could be checking whether it has reached its minimum water delivery state. At this point, a second numerical difference between the pressure feedback value and the pressure setpoint can be determined. If the output frequency is less than the preset motor reduction frequency and the second numerical difference is greater than the preset motor reduction pressure tolerance, a preset timing command is triggered to determine a second duration. If the second duration is greater than the preset motor reduction delay time, then the motor control command is determined to be a motor reduction command. In other words, it is determined that the motor needs to be reduced. For example, if a smaller range of water pressure or flow control is required, it will be determined that the motor needs to be reduced in the system to match the smaller range of water pressure or flow control requirements. The pressure setpoint refers to the set value used to control the output of the variable frequency motor, which can be a given current or voltage (motor current and voltage can indirectly represent parameters such as speed). The pressure feedback value refers to the actual feedback value of the variable frequency motor, which can be the feedback current or voltage. The preset motor reduction frequency refers to the output power value set by the user. The preset motor reduction pressure tolerance refers to a value set by the user, such as A4. If the second numerical difference between the pressure feedback value and the pressure setpoint is greater than A4, it is determined that the variable frequency motor can meet the user's water pressure or flow control requirements, and the motor can be reduced (because when the variable frequency switches to the mains frequency, other mains frequency motors are already at a higher speed, i.e., a more efficient working state), meaning the motor needs to be reduced. The second duration refers to the duration for which the output frequency is less than the preset motor reduction frequency, and the second numerical difference is greater than the preset motor reduction pressure tolerance. By setting the duration, misjudgment of commands caused by a short-term reduction in demand can be avoided, ensuring the accuracy of command determination and subsequent motor control.

[0074] In one embodiment, if any of the above conditions is not met, it will not be determined whether the motor needs to be reduced. In this case, other conditions can also be used for judgment, such as whether the motor in the current system can meet the requirements of a wider range of water pressure or flow control, or whether the efficiency of the variable frequency motor is low (or other requirements, such as speed requirements, air pressure requirements, etc.). For example, if the user finds that the displayed air pressure is too high when using the air pump, the motor corresponding to the air pump needs to be reduced to ensure that the user's needs are met. Other judgment methods can also be used, which are not limited here.

[0075] Furthermore, the steps of controlling the target motor according to the motor control command include:

[0076] Step S231: Determine the power frequency motor that is furthest from the variable frequency motor serial number as the motor to be reduced, wherein the motor to be reduced is connected to the power grid through the contactor to be reduced power grid;

[0077] Step S232: Based on the motor control command, control the contactor of the power grid to be reduced to disconnect the connection between the power grid and the motor to be reduced.

[0078] In this embodiment, when it is determined that a motor needs to be reduced, the mains frequency motor with the furthest serial number from the variable frequency motor is selected as the motor to be reduced. The motor to be reduced is connected to the power grid via a contactor connected to the power grid. The motor to be reduced refers to the mains frequency motor that needs to be stopped, and the contactor is the contactor connecting the motor to be reduced and the power grid. For example, if the serial number of the running motor is 2-3-4, where 4 is the variable frequency motor, then the serial number of the motor to be reduced is 2, and the motor to be reduced is stopped from the system. The final system has motor serial numbers 3-4, where 4 is the variable frequency motor. Reducing the number of motors ensures the effective utilization of the motors within the system.

[0079] In one embodiment, reference is made to Figure 2 Assuming motors 1 and 2 are current frequency motors and motor 3 is a variable frequency motor, the motor reduction operation (motor to be reduced is 1) is as follows: De-energize KP1 (the relay corresponding to the motor to be reduced) to control KM1 (the contactor of the power grid corresponding to the motor to be reduced), thus completing the motor reduction operation. After the motor reduction operation, motor 2 runs at current frequency, and motor 3 runs at variable frequency. For the motor reduction operation, the last current frequency motor running, counting counterclockwise or clockwise from the variable frequency motor, is removed, while the variable frequency motor's serial number remains unchanged.

[0080] Furthermore, based on the first, second, and / or third embodiments of this application described above, a fourth embodiment of the single-frequency converter multi-motor control method of this application is proposed. In this embodiment, the single-frequency converter multi-motor control system further includes a second grid contactor for connecting the power frequency motor to the power grid. After the step of controlling the target motor according to the motor control command:

[0081] Step S30: If a shutdown command is received, the first frequency converter contactor corresponding to the frequency converter motor is determined, and the second grid contactor is controlled to disconnect the power frequency motor from the grid based on the shutdown command. After the frequency converter stops outputting, the first frequency converter contactor is controlled to disconnect the frequency converter motor from the frequency converter.

[0082] In this embodiment, single-frequency converter multi-motor control can be a shutdown control process. The shutdown command refers to a user-defined command to stop the motors and bring them into a shutdown state. This is achieved by disconnecting the variable frequency motors from the frequency converter via the first frequency converter contactor and disconnecting the power frequency motors from the power grid via the second grid contactor. The frequency converter (controlled by its internal controller) provides two shutdown modes: rapid shutdown and sequential shutdown. Rapid shutdown occurs when, upon receiving the shutdown command, all power frequency motor contactors simultaneously disconnect, and the variable frequency motors driven by the frequency converter also stop under the frequency converter's control. After the frequency converter stops outputting power, the first frequency converter contactor disconnects the variable frequency motors from the frequency converter. Rapid shutdown can be used in emergency situations (such as a burst or leaking water pipe) to quickly stop all water pumps, and can also be used in other emergency scenarios. The sequential shutdown process involves all fixed-frequency motors stopping one by one according to a pre-defined shutdown sequence. Each fixed-frequency motor will have a delay period before stopping. The shutdown sequence is the same as the motor reduction sequence: starting from the last fixed-frequency motor counted counter-clockwise, the motors will stop sequentially in a clockwise direction, or vice versa. Only after the last fixed-frequency motor has stopped will the variable-frequency motor driven by the inverter stop under the inverter's control. This sequential shutdown aims to reduce the impact on water pipes, especially for systems with a large power range.

[0083] Furthermore, based on the first, second, third, and / or fourth embodiments of this application described above, a fifth embodiment of the single-frequency converter multi-motor control method of this application is proposed. In this embodiment, before the step of obtaining the parameter information of the single-frequency converter multi-motor control system, the method includes:

[0084] Step S40: If a power-on command is received, the first frequency converter corresponding to the frequency converter motor is determined, and the first frequency converter contactor is controlled to connect the frequency converter motor and the frequency converter based on the power-on command. After a preset closing delay time, the step of obtaining parameter information of the single frequency converter multi-motor control system is executed.

[0085] In this embodiment, the motors in the system are started before acquiring the parameter information of the single-frequency converter multi-motor control system. The starting method involves triggering a process to determine the first frequency converter contactor corresponding to the frequency converter motor after receiving the start-up command. Based on the start-up command, the first frequency converter contactor is controlled to connect the frequency converter motor and the frequency converter, thus enabling the frequency converter motor to enter the working state. After a preset closing delay time, the step of acquiring the parameter information of the single-frequency converter multi-motor control system is executed, which avoids control errors caused by the closing delay. Here, the frequency converter motor refers to the motor connected to the frequency converter. At startup, the user can define a single motor as the frequency converter motor, or use motors in a fixed sequence as frequency converter motors. The start-up command is a user-defined command to start the motor into the working state, connecting the frequency converter motor to the frequency converter via the first frequency converter contactor. At this point, only one motor can be identified as the frequency converter motor. Subsequent startups can follow a process of adding motors, ensuring the accuracy of multi-motor control through the control process of adding motors.

[0086] In one embodiment, reference is made to Figure 2 In inverter 10, all relay output terminals RLY are low, and all inverter contactors KM2n are also in the open state due to the control of relay KP, so all motors M1 to Mn stop. If inverter 10 receives a start command (assuming the selected inverter motor is M1), it will immediately give the relay output terminal RLY1 a high level and clear the start command. After relay KP1 is energized, the inverter contactor (i.e., the first inverter contactor corresponding to inverter motor M1) KM2 closes. After waiting for the closing delay time (ensuring that inverter motor M1 is connected to inverter 10), the start command is released, and inverter motor M1 is driven by inverter 10. If the motor needs to be started again, the operation of adding a motor will continue to be executed to ensure the accuracy of the entire motor start control.

[0087] Furthermore, based on the first, second, third, fourth, and / or fifth embodiments of this application described above, a sixth embodiment of the single-frequency converter multi-motor control method of this application is proposed. In this embodiment, the step of determining the motor control command based on the output frequency, the pressure setpoint, and the pressure feedback value further includes:

[0088] Step S241: Determine the absolute value of the difference between the pressure setpoint and the pressure feedback value as the third numerical difference;

[0089] Step S242: If the output frequency is less than the preset motor increase frequency and greater than the preset motor decrease frequency, then the motor control command is determined based on the third numerical difference, wherein the preset motor increase frequency is greater than the preset motor decrease frequency.

[0090] In this embodiment, in addition to adding and removing motors for the entire system, there is also operation to control the existing variable frequency motor. The absolute value of the difference between the pressure setpoint and the pressure feedback value is used as a third numerical difference. When the output frequency is less than the preset motor-adding frequency but greater than the preset motor-removing frequency (meaning no motor-adding or removing operation is needed), the motor control command can be determined using this third numerical difference. Specifically, the preset motor-adding frequency is greater than the preset motor-removing frequency. If the pressure setpoint is found to be too low, the pressure setpoint of the variable frequency motor will be increased; if it is found to be too high, the pressure setpoint of the variable frequency motor will be decreased. Other control methods can also be used, such as controlling parameters like the speed of the variable frequency motor, to ensure the accuracy of the variable frequency motor control.

[0091] It should be noted that the above examples are only for understanding this application and do not constitute a limitation on the single-frequency converter multi-motor control method of this application. Any simple modifications based on this technical concept are within the protection scope of this application.

[0092] This application also provides a single-frequency converter multi-motor control system, which includes a single frequency converter, a variable-frequency motor, at least one power-frequency motor, and a controller. The power supply terminal of the frequency converter is connected to the power grid, the control terminal of the frequency converter is connected to the variable-frequency motor, the power-frequency motor is connected to the power grid, and the controller is connected to the frequency converter, the variable-frequency motor, and the power-frequency motor. (Please refer to...) Figure 4 The controller includes:

[0093] The information acquisition module A10 is used to acquire parameter information of the single frequency converter multi-motor control system, wherein the parameter information includes the output frequency of the frequency converter, the pressure setpoint and pressure feedback value of the single frequency converter multi-motor control system;

[0094] The motor control module A20 is used to determine motor control commands based on the output frequency, the pressure setpoint, and the pressure feedback value, and to control the target motor according to the motor control commands, wherein the target motor includes the variable frequency motor and the fixed frequency motor.

[0095] The single-frequency converter multi-motor control system provided in this application, employing the single-frequency converter multi-motor control method in the above embodiments, can solve the technical problem of high cost in multi-motor control. Compared with the prior art, the beneficial effects of the single-frequency converter multi-motor control system provided in this application are the same as those of the single-frequency converter multi-motor control method provided in the above embodiments, and other technical features in the single-frequency converter multi-motor control system are the same as those disclosed in the methods of the above embodiments, and will not be repeated here.

[0096] In one embodiment, the frequency converter includes multiple relay output terminals and relays corresponding to the relay output terminals. Each relay output terminal is connected to a motor via the relay control as the frequency converter motor.

[0097] In this embodiment, refer to Figure 2 The inverter's power supply terminal is connected to the power grid, and its control terminal is connected to the variable frequency motor. The mains frequency motor is also connected to the power grid. Multiple relay output terminals control corresponding relays to allow the motor to connect to the inverter's control terminal, the power grid, or neither. Taking motor M1 as an example, when relay output terminal RLY1 outputs a control signal causing relay KP1 to close the inverter contactor KM2, motor M1 is connected to the inverter's control terminal and directly controlled by the inverter, functioning as a variable frequency motor. When relay output terminal RLY1 outputs a control signal causing relay KP1 to close the power grid contactor KM1, motor M1 is connected to the power grid, functioning as a mains frequency motor. When relay output terminal RLY1 outputs a control signal causing relay KP1 to open both the power grid contactor KM1 and the inverter contactor KM2, motor M1 is not connected to the system and is considered a new motor to be added. The low-voltage circuit breaker Q can select whether to connect the motor or the power grid, or provide high-voltage protection for the motor. The controller is connected to the frequency converter, variable frequency motor and mains frequency motor to control the entire system based on the various information collected from the motor or frequency converter. It can also be used to control the output control signal of the frequency converter to control the turn-off of the power grid contactor KM2n-1 and the frequency converter contactor KM2n. The control can also be set directly in the frequency converter and controlled by the frequency converter, which is not limited here.

[0098] This application provides a single frequency converter multi-motor control device, which includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the single frequency converter multi-motor control method in the above embodiment 1.

[0099] The following is for reference. Figure 5This document illustrates a structural schematic diagram suitable for implementing a single-frequency converter multi-motor control device according to embodiments of this application. The single-frequency converter multi-motor control device in embodiments of this application may include, but is not limited to, mobile terminals such as mobile phones, laptops, digital radio receivers, PDAs (Personal Digital Assistants), PADs (Portable Application Description), PMPs (Portable Media Players), and vehicle terminals (e.g., vehicle navigation terminals), as well as fixed terminals such as digital TVs and desktop computers. Figure 5 The single-frequency converter multi-motor control device shown is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of this application.

[0100] like Figure 5 As shown, a single-frequency converter multi-motor control device may include a processing unit 1001 (e.g., a central processing unit, a graphics processor, etc.), which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 1002 or a program loaded from a storage device 1003 into a random access memory (RAM) 1004. The RAM 1004 also stores various programs and data required for the operation of the single-frequency converter multi-motor control device. The processing unit 1001, ROM 1002, and RAM 1004 are interconnected via a bus 1005. An input / output (I / O) interface 1006 is also connected to the bus. Typically, the following systems can be connected to I / O interface 1006: input systems 1007 including, for example, touchscreens, touchpads, keyboards, mice, image sensors, microphones, accelerometers, gyroscopes, etc.; output devices 1008 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; storage devices 1003 including, for example, magnetic tapes, hard disks, etc.; and communication devices 1009. Communication device 1009 allows the single-inverter multi-motor control device to exchange data wirelessly or via wired communication with other devices. Although a single-inverter multi-motor control device with various systems is shown in the figure, it should be understood that it is not required to implement or possess all the systems shown. More or fewer systems may be implemented alternatively.

[0101] Specifically, according to the embodiments disclosed in this application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments disclosed in this application include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device, or installed from storage device 1003, or installed from ROM 1002. When the computer program is executed by processing device 1001, it performs the functions defined in the methods of the embodiments disclosed in this application.

[0102] The single-frequency converter multi-motor control device provided in this application, employing the single-frequency converter multi-motor control method in the above embodiments, can solve the technical problem of high cost in multi-motor control. Compared with the prior art, the beneficial effects of the single-frequency converter multi-motor control device provided in this application are the same as those of the single-frequency converter multi-motor control method provided in the above embodiments, and other technical features in this single-frequency converter multi-motor control device are the same as those disclosed in the previous embodiment method, and will not be repeated here.

[0103] It should be understood that the various parts disclosed in this application can be implemented using hardware, software, firmware, or a combination thereof. In the description of the above embodiments, specific features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0104] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0105] This application provides a computer-readable storage medium having computer-readable program instructions (i.e., a computer program) stored thereon, the computer-readable program instructions being used to execute the single-frequency converter multi-motor control method in the above embodiments.

[0106] The computer-readable storage medium provided in this application may be, for example, a USB flash drive, but is not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to: electrical connections having one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this embodiment, the computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, system, or device. The program code contained on the computer-readable storage medium may be transmitted using any suitable medium, including but not limited to: wires, optical cables, RF (Radio Frequency), etc., or any suitable combination thereof.

[0107] The aforementioned computer-readable storage medium may be included in a single-frequency converter multi-motor control device; or it may exist independently and not be assembled into a single-frequency converter multi-motor control device.

[0108] The aforementioned computer-readable storage medium carries one or more programs that, when executed by a single-frequency converter multi-motor control device, cause the single-frequency converter multi-motor control device to:

[0109] Obtain the parameter information of the single frequency converter multi-motor control system, wherein the parameter information includes the output frequency of the frequency converter, the pressure setpoint and pressure feedback value of the single frequency converter multi-motor control system;

[0110] The motor control command is determined based on the output frequency, the pressure setpoint, and the pressure feedback value, and the target motor is controlled according to the motor control command. The target motor includes the variable frequency motor and the fixed frequency motor.

[0111] Computer program code for performing the operations of this application can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a Local Area Network (LAN) or a Wide Area Network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0112] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0113] The modules described in the embodiments of this application can be implemented in software or hardware. The names of the modules do not necessarily limit the functionality of the unit itself.

[0114] The readable storage medium provided in this application is a computer-readable storage medium that stores computer-readable program instructions (i.e., a computer program) for executing the above-described single-frequency converter multi-motor control method, thereby solving the technical problem of high cost in multi-motor control. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided in this application are the same as those of the single-frequency converter multi-motor control method provided in the above embodiments, and will not be repeated here.

[0115] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the single-frequency converter multi-motor control method described above.

[0116] The computer program product provided in this application can solve the technical problem of high cost in multi-motor control. Compared with the prior art, the beneficial effects of the computer program product provided in this application are the same as those of the single-frequency converter multi-motor control method provided in the above embodiments, and will not be repeated here.

[0117] The above description is only a part of the embodiments of this application and does not limit the patent scope of this application. All equivalent structural transformations made under the technical concept of this application and using the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included in the patent protection scope of this application.

Claims

1. A single inverter multi-motor control method, characterized by, The single-frequency converter multi-motor control method is applied to a single-frequency converter multi-motor control system connected to a power grid, and the single-frequency converter multi-motor control system comprises a single-frequency converter, a variable-frequency motor and at least one power-frequency motor, wherein a power supply end of the single-frequency converter is connected to the power grid, a control end of the single-frequency converter is connected to the variable-frequency motor, and the power-frequency motor is connected to the power grid. Parameter information of the single-frequency converter multi-motor control system is acquired, wherein the parameter information comprises an output frequency of the single-frequency converter, a pressure given value and a pressure feedback value of the single-frequency converter multi-motor control system. A motor control instruction is determined according to the output frequency, the pressure given value and the pressure feedback value, and a target motor is controlled according to the motor control instruction, wherein the target motor comprises the variable-frequency motor and the power-frequency motor.

2. The single inverter multi-motor control method of claim 1, wherein, The step of determining the motor control instruction according to the output frequency, the pressure given value and the pressure feedback value comprises: A first numerical difference between the pressure given value and the pressure feedback value is determined. If the output frequency is greater than or equal to a preset motor adding frequency, and the first numerical difference is greater than a preset motor adding pressure tolerance, a preset time instruction is triggered to determine a first duration. If the first duration is greater than a preset motor adding delay time, the motor control instruction is determined as a motor adding instruction.

3. The single inverter multi-motor control method of claim 2, wherein, The target motor further comprises a newly-added motor close to a serial number bit of the variable-frequency motor, a newly-added variable-frequency contactor for connecting the newly-added motor and the single-frequency converter, a first variable-frequency contactor for connecting the variable-frequency motor and the single-frequency converter, and a first power grid contactor for connecting the variable-frequency motor and the power grid. After the variable-frequency motor is controlled to be in a high-speed running state based on the motor control instruction, the first variable-frequency contactor is controlled to disconnect the variable-frequency motor and the single-frequency converter, and the newly-added variable-frequency contactor is controlled to connect the newly-added motor and the single-frequency converter after a preset opening delay time. The first power grid contactor is controlled to connect the variable-frequency motor and the power grid after a preset closing delay time.

4. The single inverter multi-motor control method of claim 1, wherein, The step of determining the motor control instruction according to the output frequency, the pressure given value and the pressure feedback value further comprises: A second numerical difference between the pressure feedback value and the pressure given value is determined. If the output frequency is less than a preset motor reducing frequency, and the second numerical difference is greater than a preset motor reducing pressure tolerance, a preset time instruction is triggered to determine a second duration. If the second duration is greater than a preset motor reducing delay time, the motor control instruction is determined as a motor reducing instruction.

5. The single inverter multi-motor control method of claim 4, wherein, The step of controlling the target motor according to the motor control instruction comprises: A power-frequency motor farthest from the serial number bit of the variable-frequency motor is determined as a motor to be reduced, wherein the motor to be reduced is connected to the power grid through a power grid contactor to be reduced. The power grid contactor to be reduced is controlled to disconnect the power grid and the motor to be reduced based on the motor control instruction.

6. The single inverter multi-motor control method according to any one of claims 1 to 5, characterized in that, The single-frequency converter multi-motor control system further comprises a second power grid contactor for connecting the power frequency motor and the power grid, and after the step of controlling the target motor according to the motor control instruction, the method further comprises: If a shutdown instruction is received, a first frequency converter contactor corresponding to the frequency converter motor is determined, the second power grid contactor is controlled to disconnect the power frequency motor and the power grid based on the shutdown instruction, and after the frequency converter stops outputting, the first frequency converter contactor is controlled to disconnect the frequency converter motor and the frequency converter.

7. The single inverter multi-motor control method according to any one of claims 1 to 5, characterized in that, Before the step of acquiring the parameter information of the single-frequency converter multi-motor control system, the method further comprises: If a startup instruction is received, a first frequency converter contactor corresponding to the frequency converter motor is determined, and the first frequency converter contactor is controlled to connect the frequency converter motor and the frequency converter based on the startup instruction, and after a preset closing delay time, the step of acquiring the parameter information of the single-frequency converter multi-motor control system is performed.

8. The single inverter multi-motor control method according to any one of claims 1 to 5, characterized in that, The step of determining the motor control instruction according to the output frequency, the pressure given value and the pressure feedback value further comprises: determining the absolute value of the difference between the pressure given value and the pressure feedback value as a third numerical difference; If the output frequency is less than a preset motor increasing frequency and greater than a preset motor decreasing frequency, a motor control instruction is determined based on the third numerical difference, wherein the preset motor increasing frequency is greater than the preset motor decreasing frequency.

9. A single inverter multi-motor control system, characterized by, The single-frequency converter multi-motor control system comprises a single frequency converter, one frequency converter motor, at least one power frequency motor and a controller, wherein the power supply end of the frequency converter is connected with the power grid, the control end of the frequency converter is connected with the frequency converter motor, the power frequency motor is connected with the power grid, and the controller is connected with the frequency converter, the frequency converter motor and the power frequency motor, and the controller comprises: an information acquisition module for acquiring parameter information of the single-frequency converter multi-motor control system, wherein the parameter information comprises an output frequency of the frequency converter, a pressure given value and a pressure feedback value of the single-frequency converter multi-motor control system; a motor control module for determining a motor control instruction according to the output frequency and the pressure given value and the pressure feedback value, and controlling a target motor according to the motor control instruction, wherein the target motor comprises the frequency converter motor and the power frequency motor.

10. The single inverter multi-motor control system of claim 9, wherein, The frequency converter comprises a plurality of relay output terminals and corresponding relays of the relay output terminals, and each relay output terminal is connected with one motor as the frequency converter motor through the relay control.

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