Storage medium, frequency converter runaway start control method, device and equipment

Abstract

The application discloses a storage medium, a frequency converter runaway starting control method, device and equipment, wherein the method comprises the following steps: monitoring the voltage amplitude and phase of a stator port in real time when a motor is running, then calculating the voltage amplitude and phase adaptation values which are required to be output by the frequency converter when the runaway starting is performed by using the monitoring data, and further calculating the corresponding motor speed and the adaptation frequency which is output by the frequency converter when the runaway starting is performed by using the linear fitting method. The application calculates the voltage amplitude, voltage phase value and frequency which are required to be output by the frequency converter after a set time delay when the runaway starting is performed, so that the error between the calculation result and the real-time monitoring value can be reduced or even avoided due to the time delay of the frequency converter detection, calculation, control output and other links; the zero impact of the voltage, current and torque when the frequency converter and the motor are connected to the grid is realized, the safety and reliability of the runaway starting are ensured, and the damage of the frequency converter or the motor is avoided.

Description

Technical Field

[0001] This invention relates to the field of motor control, and in particular to storage media, methods, devices and equipment for controlling the overspeed start of frequency converters. Background Technology

[0002] Inverter flystart typically refers to the process of rapidly bringing a motor to a set speed using an inverter without an external power source.

[0003] When the inverter receives the start command, the motor rotor is rotating and a back electromotive force is induced in the stator winding. If the voltage amplitude and phase of the inverter output are not completely consistent with the amplitude and phase of the back electromotive force, an inrush voltage and inrush current will be generated. When the inrush voltage and inrush current exceed the tolerance limit of the inverter's IGBT and other power electronic devices, it will cause accidents such as inverter device burnout.

[0004] Furthermore, the matching of the inverter's output frequency and the motor's speed is crucial at the moment of vehicle start-up. Specifically, when the inverter's output frequency is higher than the motor's actual speed, the motor will accelerate rapidly, and the stator current will reach several times its rated value. Normally, the inverter capacity is not selected based on a multiple of the motor's rated current, which can cause overcurrent tripping or inverter burnout. Conversely, when the inverter's output frequency is lower than the motor's actual speed, the motor operates in a generator state, charging the inverter's DC bus capacitor. This causes the capacitor voltage to rise excessively, leading to inverter tripping.

[0005] In existing technologies, inverter overspeed start is generally achieved by hardware detection of voltage or software frequency search to reduce the occurrence of the above-mentioned problems.

[0006] The inventors discovered through research that the existing methods for achieving inverter fly-start have at least the following drawbacks:

[0007] Hardware-based voltage detection refers to the inverter detecting the phase angle and amplitude of the motor stator voltage and controlling the inverter to output corresponding voltage amplitude and phase angle to reduce voltage surges. However, the frequency output by the inverter is calculated based on the Uf curve when the inverter is running normally with the motor. When the motor loses power, the stator terminal voltage and the actual frequency of the motor may not fall on the Uf curve. Therefore, this overrunning start method can still cause the inverter's DC bus or power electronic devices to be impacted.

[0008] Frequency search via software refers to the software searching for the motor rotor frequency when there is no speed sensor. After finding the motor rotor frequency, the software outputs the corresponding voltage amplitude and phase angle according to the Uf curve set by the frequency converter. This method has a long search time, cannot guarantee the accuracy of the rotor frequency, and has a low success rate. In addition, it also has the problem that the stator terminal voltage and the actual frequency of the motor may not fall on the Uf curve when the motor loses power. Therefore, this overspeed start method can still cause the DC bus or power electronic devices of the frequency converter to be impacted.

[0009] The information disclosed in the background section is intended only to enhance the understanding of the overall background of the present invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0010] The purpose of this invention is to prevent the DC bus or power electronic devices of the frequency converter from being impacted.

[0011] This invention provides a method for controlling the overspeed start of a frequency converter, comprising the following steps:

[0012] S11. Real-time acquisition of monitoring data of the stator port of the motor during operation according to a preset sampling step size; the monitoring data includes the three-phase voltage amplitude and phase at the same moment;

[0013] S12. Using the time when the motor loses power as the reference time, calculate the first and second derivatives of the three-phase voltage amplitude and the phase based on the three sets of monitoring data collected after the reference time.

[0014] S13. Calculate the time delay t based on the first derivative and the second derivative. d The voltage amplitude adaptation value and voltage phase adaptation value output by the frequency converter are required when the car starts up; the t d This refers to the time from the detection of the three sets of voltage monitoring data (i.e., t3 or t+2Δt) to the inverter output voltage U. m , and frequency f m During the period, t d =t m -t3.

[0015] S14. Based on the multiple sets of monitoring data collected after the reference time, generate a two-dimensional array with elements of three-phase voltage amplitude and corresponding collection time points; determine the corresponding preset speed-time curve according to the two-dimensional array, solve for the actual speed of the motor after the time delay is td, and calculate the adaptive frequency output by the inverter required when performing a fly-start operation.

[0016] S15. Based on the voltage amplitude adaptation value, the voltage phase adaptation value, and the adaptation frequency, control the frequency converter to execute the overspeed start command.

[0017] Preferably, in this invention, when the voltage amplitude matching value and matching frequency output by the frequency converter do not conform to the Uf curve output by the frequency converter, the method further includes:

[0018] S16. Control the voltage amplitude of the frequency converter to change at a set rate to the P value on the frequency converter Uf curve with f as the reference. n point;

[0019] S17, The voltage amplitude and frequency of the frequency converter are controlled by P. n The point changes at a set rate to the operating point P set by the frequency converter and motor. set .

[0020] In another aspect of the present invention, a variable frequency drive (VFD) overspeed start control device is also provided, comprising:

[0021] The monitoring data acquisition unit is used to acquire monitoring data of the stator port of the motor in real time at a preset sampling step size; the monitoring data includes the three-phase voltage amplitude and phase at the same moment;

[0022] The derivative calculation unit is used to calculate the first and second derivatives of the three-phase voltage amplitude and the phase, respectively, based on the time point when the motor loses power and two sets of monitoring data collected after the reference time.

[0023] The adaptation value calculation unit is used to calculate the time delay t based on the first derivative and the second derivative. d When the car starts up, the voltage amplitude and voltage phase adaptation values ​​output by the frequency converter are required.

[0024] The frequency calculation unit is used to generate a two-dimensional array with elements of three-phase voltage amplitude and corresponding acquisition time points based on multiple sets of monitoring data collected after the reference time; and to find the corresponding preset speed-time curve based on the two-dimensional array to solve for the time delay t. d The actual speed of the motor is then calculated, and the appropriate frequency output from the inverter is required when performing a fly start.

[0025] The start command generation unit is used to control the frequency converter to execute the overspeed start command based on the voltage amplitude adaptation value, the voltage phase adaptation value and the adaptation frequency.

[0026] Preferably, in this invention, it further includes:

[0027] The control command generation unit is used to control the voltage amplitude of the frequency converter to change at a set rate to P on the frequency converter's Uf curve (based on f) when the voltage amplitude and frequency matching value and frequency matching value of the frequency converter output do not conform to the frequency converter's output Uf curve. n point;

[0028] The voltage amplitude and frequency of the frequency converter are controlled by P. n The point changes at a set rate to the operating point P set by the frequency converter and motor. set .

[0029] In another aspect of the present invention, a variable frequency drive (VFD) overspeed start control device is also provided, comprising:

[0030] Memory, used to store computer programs;

[0031] A processor is used to call and execute the computer program to implement the various steps of the inverter fly-start control method as described in any of the preceding claims.

[0032] In another aspect of the present invention, a storage medium is also provided, on which a computer program is stored, which, when executed by a processor, implements the various steps of the inverter overspeed start control method as described in any of the preceding claims.

[0033] The inverter overspeed start control device includes a computer program stored on a medium. The computer program includes program instructions. When the program instructions are executed by the computer, the computer performs the methods described in the above aspects and achieves the same technical effect.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] This invention monitors the voltage amplitude and phase at the stator port of the motor in real time during operation. Then, using the monitoring data, it calculates the voltage amplitude and phase adaptation values ​​required by the inverter output when performing a fly-start operation. In addition, it uses a linear fitting method to calculate the corresponding motor speed and the adaptation frequency output by the inverter when performing a fly-start operation.

[0036] This invention calculates the voltage amplitude, voltage phase, and frequency that the inverter needs to output when the vehicle starts after a set time delay. Therefore, it can reduce or even avoid the error between the calculated result and the real-time monitoring value caused by the time delay in the inverter's detection, calculation, and control output. In this way, the voltage amplitude, phase, output frequency, and motor speed between the inverter and the motor can be precisely matched at the moment of vehicle start-up, thereby achieving zero impact on voltage, current, and torque when the inverter and motor are connected to the grid, ensuring the safety and reliability of vehicle start-up, and avoiding damage to the inverter or motor.

[0037] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it according to the contents of the specification, and to make the above and other objects, technical features and advantages of the present invention easier to understand, one or more preferred embodiments are listed below and described in detail with reference to the accompanying drawings. Attached Figure Description

[0038] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a flowchart illustrating the steps of the inverter overspeed start control method described in this invention;

[0040] Figure 2 This is the decay curve of the stator voltage U and speed n of the motor at the moment of power failure, as described in this invention;

[0041] Figure 3 This is the specific control process for the inverter's fly-start as described in this invention;

[0042] Figure 4 This is a schematic diagram of the structure of the inverter overspeed start control device described in this invention;

[0043] Figure 5 This is a schematic diagram of the structure of the inverter overspeed start control device described in this invention. Detailed Implementation

[0044] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0045] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprising" shall be understood to include the stated elements or components without excluding other elements or other components.

[0046] In this document, the terms "first," "second," etc., are used to distinguish two different elements or parts, and are not used to define specific positions or relative relationships. In other words, in some embodiments, the terms "first," "second," etc., can also be used interchangeably.

[0047] Example 1

[0048] To prevent the inverter's DC bus or power electronic components from being impacted during engine start-up, such as Figure 1 As shown, an embodiment of the present invention provides a method for controlling the overspeed start of a frequency converter, including the following steps:

[0049] S11. Real-time acquisition of monitoring data of the stator port of the motor during operation according to a preset sampling step size; the monitoring data includes the three-phase voltage amplitude and phase at the same moment;

[0050] In this embodiment of the invention, a real-time monitoring method is used to continuously acquire the three-phase voltage amplitude and phase at the stator port of the motor during operation; according to the set sampling step size (i.e., Δt), the three-phase voltage amplitude and phase at the same moment are obtained as a set of data each time, and multiple samplings constitute a monitoring data set.

[0051] S12. Using the time when the motor loses power as the reference time, calculate the first and second derivatives of the three-phase voltage amplitude and the phase based on the three sets of monitoring data collected after the reference time.

[0052] Upon receiving the vehicle start command, the derivative is calculated using three consecutive sets of monitoring data after the reference time as the basis for calculation. The specific process is as follows:

[0053] Let t0 be the time when the motor loses power;

[0054] Let t be the time interval between the frequency converter detecting motor power failure and issuing the overrun start command. m ;

[0055] Let the acquisition times for the three sets of monitoring data be t1, t2, and t3, respectively, with a fixed sampling interval of Δt; let the phase voltage amplitude and phase at time t1 be U1, U2, and U3, respectively. At time t1+Δt (i.e., time t2), the phase voltage amplitude and phase are U2 and U2, respectively. At time t1+2Δt (i.e., time t3), the phase voltage amplitude and phase are U3 and U4, respectively. Then the first derivative U′ and second derivative U″ of the phase voltage amplitude, and the first derivative of the phase voltage phase. and second derivative The calculation formulas are as follows:

[0056]

[0057] S13. Calculate the time delay t based on the first derivative and the second derivative. d When the car starts up, the voltage amplitude and voltage phase adaptation values ​​output by the frequency converter are required.

[0058] The formulas used include:

[0059]

[0060] In the formula, the time delay t d This refers to the time from the moment voltage U3 is detected (i.e., t3 or t+2Δt) to the inverter output voltage U. m , and frequency f m During the period, t d =t m -t3 should be greater than the inverter's data processing time and command output time.

[0061] The inverter can detect the phase angle and amplitude of the motor stator voltage in real time. Since the stator voltage amplitude and phase angle decay relatively slowly, and the inverter has a small data processing volume and short processing time, it can immediately output the corresponding voltage amplitude and phase angle. The error between the inverter's output voltage amplitude and phase angle and the motor's stator voltage amplitude and phase angle is relatively small and negligible. However, in this embodiment, a certain amount of time is needed to continuously detect and record the two-dimensional array of voltage amplitude and time multiple times (at least three times). Then, linear fitting is performed using multiple three-phase voltage amplitudes and times to determine the matching U = f(t, T) curve, further determining the corresponding load torque T, and determining the corresponding speed and time n = f(t, T) curve based on preset data for subsequent calculations. Therefore, the inverter has a large data processing volume and a long processing time. The above steps calculate the time delay t by calculating the first and second derivatives of the voltage amplitude and phase angle. d The stator voltage amplitude and phase angle of the motor can be adjusted to avoid voltage amplitude and phase angle errors caused by delays in inverter data processing and output command transmission, further reducing the voltage amplitude and phase angle errors of the inverter output and the motor stator.

[0062] S14. Based on the multiple sets of monitoring data collected after the reference time, generate a two-dimensional array whose elements are the three-phase voltage amplitude and the corresponding acquisition time point; find the corresponding preset speed-time curve based on the voltage-time two-dimensional array, and solve for the time delay t. d The actual speed of the motor is then calculated, and the appropriate frequency output from the inverter is required when performing a fly start.

[0063] In practical applications, this step may specifically include the following sub-steps:

[0064] S21. A list of data corresponding to the changes in three-phase voltage amplitude and speed over time of the motor connected to the frequency converter under different load torques and when the stator port is de-energized is obtained in advance. The list may be as shown in Table 1.

[0065] Table 1

[0066]

[0067] The list of embodiments of the present invention includes various load torques (e.g., load torque T1, load torque T2, load torque T3, etc.), the number of which can be determined by those skilled in the art based on actual working conditions, and no specific limitation is made here.

[0068] In practical applications, the data on the changes in three-phase voltage amplitude and rotational speed over time in the above list can be obtained by consulting motor manufacturers, conducting on-site tests, and performing computer modeling and simulation analysis.

[0069] Each load torque corresponds to a record of the data relationship between the three-phase voltage amplitude and the speed change over time when the stator port loses power.

[0070] S22. Generate continuous functions U = f(t, T) and n = f(t, T) of the motor terminal voltage and speed as a function of time and load torque based on the list of the corresponding data.

[0071] In this step, based on the data in the list above, continuous functions U = f(t, T) and n = f(t, T) of the motor terminal voltage and speed as a function of time and load torque are generated by interpolating the discrete data. In practical applications, interpolation methods such as polynomial interpolation, Hermite interpolation, piecewise interpolation, and spline interpolation can be used.

[0072] In this way, we can obtain continuous functions U = f(t, T) and n = f(t, T) corresponding to various load torques.

[0073] like Figure 2 As shown, at the instant the motor loses power, due to the different load torque T, the stator voltage U and speed n of the motor will have different attenuation curves.

[0074] S23. Based on the three-phase voltage amplitudes from multiple sets of real-time acquired monitoring data, generate a two-dimensional array including multiple elements; the elements include the three-phase voltage amplitudes and their corresponding acquisition times;

[0075] In this embodiment of the invention, monitoring data is continuously acquired through real-time monitoring. Based on the three-phase voltage amplitude and the acquisition time of each three-phase voltage amplitude in the monitoring data, a two-dimensional array with elements of three-phase voltage amplitude and acquisition time can be constructed. S24. Linear fitting is performed on multiple three-phase voltage amplitudes and times in the two-dimensional array to determine the matching U=f(t,T) curve, so as to determine the load torque T connected to the motor. Then, based on the corresponding load torque T, the corresponding speed and time n=f(t,T) curve is determined.

[0076] S25. Based on the preset time interval t between the frequency converter detecting motor power failure and issuing the overrun start command, m Calculate t based on the matched n = f(t, T) curve. m Time (or time delay t) d The speed n of the motor (after) m ;

[0077] When calculating the required frequency output from the inverter for a flyback start, the specific steps are as follows:

[0078] S26. Based on the motor speed n m Calculate the frequency f output by the frequency converter m The required formulas include:

[0079]

[0080] In the formula, n m is the rotational speed of the motor, r / min; P is the number of pole pairs of the motor.

[0081] S15. Based on the voltage amplitude adaptation value, the voltage phase adaptation value, and the adaptation frequency, control the frequency converter to execute the overspeed start command.

[0082] Furthermore, in this embodiment of the invention, if the voltage amplitude and frequency adaptation values ​​calculated by the inverter control output when the vehicle starts match the Uf curve output by the inverter, no further adjustment is required; the voltage amplitude and frequency of the inverter are directly controlled to change from point Pn at a set rate to the operating point P set by the inverter and the motor. set That's all.

[0083] Preferably, when the voltage amplitude matching value and matching frequency output by the frequency converter do not conform to the Uf curve output by the frequency converter, the following steps may also be included:

[0084] S16. Control the voltage amplitude of the frequency converter to change at a set rate to the P value on the frequency converter Uf curve with f as the reference. n point;

[0085] Specifically, during engine start-up, the inverter output voltage amplitude adaptation value U m Voltage phase adaptation value and the matching frequency f m Following the command, to reduce the impact on power electronic devices and torque, the frequency converter maintains the adaptation frequency f. m The control voltage amplitude U remains unchanged. m The rate changes according to the set rate ΔU to f m P on the Uf curve of the frequency converter as a reference n point.

[0086] S17, The voltage amplitude and frequency of the frequency converter are controlled by P. n The point changes at a set rate to the operating point P set by the frequency converter and motor. set .

[0087] In a specific example, the control process for inverter fly-start in this embodiment of the invention can be as follows: Figure 3 As shown.

[0088] In summary, this embodiment of the invention monitors the voltage amplitude and phase of the stator port of the motor in real time during operation. Using the monitoring data, the voltage amplitude and phase adaptation values ​​required by the inverter output for the start-up are calculated. In addition, the motor speed and the adaptation frequency output by the inverter corresponding to the start-up are calculated using a linear fitting method.

[0089] This embodiment of the invention calculates the voltage amplitude U that the inverter needs to output when the car starts after a set time delay. m Voltage phase value and frequency f m Therefore, it can reduce or even avoid the error between the calculation result and the real-time monitoring value caused by the time delay of the inverter's detection, calculation and control output. In this way, the voltage amplitude, phase, output frequency and motor speed between the inverter and the motor can be accurately matched at the moment of the inverter's overspeed start-up, thereby achieving zero impact on voltage, current and torque when the inverter and motor are connected to the grid, ensuring the safety and reliability of overspeed start-up and avoiding damage to the inverter or motor.

[0090] Example 2

[0091] Corresponding to the method embodiment, another aspect of the present invention also provides a frequency converter overspeed start control device. Figure 4 This diagram illustrates the structure of a frequency converter overspeed start control device provided in an embodiment of the present invention. The frequency converter overspeed start control device is... Figure 1 The device corresponding to the inverter overspeed start control method in the corresponding embodiment is implemented through a virtual device. Figure 1 In the corresponding embodiment, the inverter fly-start control method, each virtual module constituting the inverter fly-start control device can be executed by electronic devices, such as network devices, terminal devices or servers.

[0092] Specifically, the inverter overspeed start control device in this embodiment of the invention includes:

[0093] The monitoring data acquisition unit 01 is used to acquire monitoring data of the stator port of the motor in real time according to a preset sampling step size; the monitoring data includes the three-phase voltage amplitude and phase at the same moment;

[0094] The derivative calculation unit 02 is used to calculate the first and second derivatives of the three-phase voltage amplitude and the phase based on the time when the motor loses power and two sets of monitoring data collected after the reference time, respectively.

[0095] The adaptation value calculation unit 03 is used to calculate the time delay t based on the first derivative and the second derivative. d The voltage amplitude and voltage phase adaptation values ​​output by the frequency converter are required when the car is started.

[0096] The frequency calculation unit 04 is used to generate a two-dimensional array with elements of three-phase voltage amplitude and corresponding acquisition time points based on multiple sets of monitoring data collected after the reference time; and to find the corresponding preset speed-time curve based on the voltage-time two-dimensional array (voltage-time two-dimensional array) to solve for the time delay t. d The actual speed of the motor is then calculated, and the appropriate frequency output from the inverter is required when performing a fly start.

[0097] The start command generation unit 05 is used to control the frequency converter to execute the overspeed start command according to the voltage amplitude adaptation value, the voltage phase adaptation value and the adaptation frequency.

[0098] Preferably, the present invention may further include:

[0099] The control command generation unit (not shown in the figure) is used to control the voltage amplitude of the frequency converter to change to P on the frequency converter Uf curve with f as the reference when the voltage amplitude and frequency matching value and frequency matching value of the frequency converter output do not conform to the Uf curve of the frequency converter output. n point;

[0100] The voltage amplitude and frequency of the control inverter are changed from point Pn at a set rate to the operating point P set by the inverter and the motor. set .

[0101] It should be noted that the inverter overspeed start control device in the embodiments of the present invention can be an industrial control device with data processing capabilities (such as a computer, processor or PLC, etc.), which controls the execution of inverter commands through data communication.

[0102] It should be noted that the specific implementation method and technical effects of the inverter overspeed start control device in the embodiments of the present invention can be found by referring to... Figure 1 The corresponding inverter overspeed start control method will not be elaborated here.

[0103] Example 3

[0104] Corresponding to the method embodiments, this invention also provides a variable frequency drive (VFD) fly-start control device, such as a terminal or server. The server can be a standalone physical server, a server cluster or distributed system composed of multiple physical servers, or a cloud server providing basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communication, middleware services, domain name services, security services, CDN, and big data and artificial intelligence platforms. The terminal can be a smartphone, tablet, laptop, desktop computer, etc., but is not limited to these.

[0105] An example diagram of the hardware structure block diagram of the inverter fly-start control device provided in this application embodiment is shown below. Figure 5 As shown, it may include:

[0106] Processor 1, communication interface 2, memory 3, and communication bus 4;

[0107] The processor 1, communication interface 2, and memory 3 communicate with each other via communication bus 4.

[0108] Optionally, communication interface 2 can be an interface of a communication module, such as the interface of a GSM module;

[0109] Processor 1 may be a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of this application.

[0110] Memory 3 may include high-speed RAM memory, and may also include non-volatile memory, such as at least one disk storage device.

[0111] Specifically, processor 1 is used to execute the computer program stored in memory 3 to perform the following steps:

[0112] S11. Real-time acquisition of monitoring data of the stator port of the motor during operation according to a preset sampling step size; the monitoring data includes the three-phase voltage amplitude and phase at the same moment;

[0113] S12. Using the time when the motor loses power as the reference time, calculate the first and second derivatives of the three-phase voltage amplitude and the phase based on the three sets of monitoring data collected after the reference time.

[0114] S13. Calculate the time delay t based on the first derivative and the second derivative. d The voltage amplitude and voltage phase adaptation values ​​output by the frequency converter are required when the car is started.

[0115] S14. Based on the multiple sets of monitoring data collected after the reference time, generate a two-dimensional array whose elements are the three-phase voltage amplitude and the corresponding collection time point; determine the corresponding preset speed-time curve based on the two-dimensional array, and solve for the time delay t. d The actual speed of the motor is then calculated, and the appropriate frequency output from the inverter is required when performing a fly start.

[0116] S15. Based on the voltage amplitude adaptation value, the voltage phase adaptation value, and the adaptation frequency, control the frequency converter to execute the overspeed start command.

[0117] Preferably, in this invention, when the voltage amplitude matching value and matching frequency output by the frequency converter do not conform to the Uf curve output by the frequency converter, the method further includes:

[0118] S16. Control the voltage amplitude of the frequency converter to change at a set rate to the P value on the frequency converter Uf curve with f as the reference. n point;

[0119] S17. The voltage amplitude and frequency of the control inverter are changed from point Pn at a set rate to the operating point P set by the inverter and the motor. set .

[0120] The above-described product can execute the method provided in the embodiments of the present invention, and has the corresponding functional modules and beneficial effects for executing the method. Technical details not described in detail in this embodiment can be found in the inverter overspeed start control method provided in the embodiments of the present invention.

[0121] Example 4

[0122] In this embodiment of the invention, a storage medium is also provided, which can store a program suitable for execution by a processor, the program being used for:

[0123] S11. Real-time acquisition of monitoring data of the stator port of the motor during operation according to a preset sampling step size; the monitoring data includes the three-phase voltage amplitude and phase at the same moment;

[0124] S12. Using the time when the motor loses power as the reference time, calculate the first and second derivatives of the three-phase voltage amplitude and the phase based on the three sets of monitoring data collected after the reference time.

[0125] S13. Calculate the time delay t based on the first derivative and the second derivative. d The voltage amplitude and voltage phase adaptation values ​​output by the frequency converter are required when the car is started.

[0126] S14. Based on the multiple sets of monitoring data collected after the reference time, generate a two-dimensional array whose elements are the three-phase voltage amplitude and the corresponding collection time point; determine the corresponding preset speed-time curve based on the two-dimensional array, and solve for the time delay t. d The actual speed of the motor is then calculated, and the appropriate frequency output from the inverter is required when performing a fly start.

[0127] S15. Based on the voltage amplitude adaptation value, the voltage phase adaptation value, and the adaptation frequency, control the frequency converter to execute the overspeed start command.

[0128] Preferably, in this invention, when the voltage amplitude matching value and matching frequency output by the frequency converter do not conform to the Uf curve output by the frequency converter, the method further includes:

[0129] S16. Control the voltage amplitude of the frequency converter to change at a set rate to the P value on the frequency converter Uf curve with f as the reference. n point;

[0130] S17. The voltage amplitude and frequency of the control inverter are changed from point Pn at a set rate to the operating point P set by the inverter and the motor. set .

[0131] Optionally, the refined and extended functions of the program can be found in the description above.

[0132] The above-described product can execute the methods provided in the embodiments of the present invention, and has the corresponding functional modules and beneficial effects for executing the methods. Technical details not described in detail in this embodiment can be found in the methods provided in other embodiments of the present invention.

[0133] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0134] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. Furthermore, the couplings or direct couplings or communication connections shown or discussed may be indirect couplings or communication connections through interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0135] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0136] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0137] It should be understood that in the embodiments of this application, the claims, various embodiments, and features can be combined with each other to solve the aforementioned technical problems.

[0138] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0139] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for controlling the overspeed start of a frequency converter, characterized in that, Including the following steps: S11. Real-time acquisition of monitoring data of the stator port of the motor during operation according to a preset sampling step size; the monitoring data includes the three-phase voltage amplitude and phase at the same moment; S12. Using the time when the motor loses power as the reference time, calculate the first and second derivatives of the three-phase voltage amplitude and the phase based on the three sets of monitoring data collected after the reference time. S13. Calculate the time delay t based on the first derivative and the second derivative. d The voltage amplitude and voltage phase adaptation values ​​output by the frequency converter are required when the car is started. S14. Based on the multiple sets of monitoring data collected after the reference time, generate a two-dimensional array whose elements are the three-phase voltage amplitude and the corresponding collection time point; determine the corresponding preset speed-time curve based on the two-dimensional array, and solve for the time delay t. d The actual speed of the motor is then calculated, and the appropriate frequency output from the inverter is required when performing a fly start. S15. Based on the voltage amplitude adaptation value, the voltage phase adaptation value, and the adaptation frequency, control the frequency converter to execute the overspeed start command.

2. The inverter overspeed start control method according to claim 1, characterized in that, When the voltage amplitude and frequency of the inverter output do not match the Uf curve of the inverter output, the following also applies: S16. Control the voltage amplitude of the frequency converter to change at a set rate to the P value on the frequency converter Uf curve with f as the reference. n point; S17. The voltage amplitude and frequency of the control inverter are changed from point Pn at a set rate to the operating point P set by the inverter and the motor. set .

3. The inverter overspeed start control method according to claim 1 or 2, characterized in that, The calculation of the first and second derivatives of the three-phase voltage amplitude and the phase based on the three sets of monitoring data collected after the reference time includes: Let t0 be the time when the motor loses power; Let t be the time interval between the frequency converter detecting motor power failure and issuing the overrun start command. m ; Let the collection times for the three sets of monitoring data be t1, t2 and t3, respectively, and the sampling time be kept at a fixed interval of Δt; Let the phase voltage amplitude and phase at time t1 be U1, U2, U3, U4, U5, U6, U7, U8, U9, U10, U11, U12, U13, U14, U15, U16, U17, U18, U19, U10, U113, U10, U113, U103, U1 ... At time t2, the phase voltage amplitude and phase are U2 and U2, respectively. At time t3, the phase voltage amplitude and phase are U3, Then the first derivative U′ and second derivative U″ of the phase voltage amplitude, and the first derivative of the phase voltage phase. and second derivative The calculation formulas are as follows:

4. The inverter overspeed start control method according to claim 3, characterized in that, The time delay t is calculated based on the first derivative and the second derivative. d When performing a flyback start, the inverter outputs voltage amplitude and voltage phase adaptation values, and the formulas used include: Delay t d This refers to the time from the moment voltage U3 is detected (i.e., t3 or t+2Δt) to the inverter output voltage U m , and frequency f m During the period, t d =t m -t3.

5. The inverter overspeed start control method according to claim 4, characterized in that, The multiple sets of monitoring data collected based on the reference time are used to generate a two-dimensional array whose elements are the three-phase voltage amplitude and the corresponding collection time point; the corresponding preset speed-time curve is found based on the two-dimensional array, and the time delay t is calculated. d The actual speed of the motor mentioned later includes: S21. Pre-obtain a list of data corresponding to the changes in three-phase voltage amplitude and speed over time of the motor connected to the frequency converter under different load torques and when the stator port is de-energized; S22. Generate continuous functions U = f(t, T) and n = f(t, T) of the motor terminal voltage and speed as a function of time and load torque based on the list of the corresponding data. S23. Based on the three-phase voltage amplitudes from multiple sets of real-time acquired monitoring data, generate a two-dimensional array including multiple elements; the elements include the three-phase voltage amplitudes and their corresponding acquisition times; S24. Based on the multiple three-phase voltage amplitudes and times in the two-dimensional array, perform linear fitting to determine the matching U=f(t,T) curve, and then based on the corresponding load torque T, determine the corresponding speed and time n=f(t,T) curve. S25. Based on the preset time interval t between the frequency converter detecting motor power failure and issuing the overrun start command, m Calculate t based on the matched n = f(t, T) curve. m The time or delay is t d The speed n of the rear motor m。 6. The inverter overspeed start control method according to claim 5, characterized in that, The calculation of the required inverter output frequency for the start-up of the flying car includes: S26. Based on the motor speed n m Calculate the frequency f output by the frequency converter m (Hz), the required formula includes: In the formula, n m is the rotational speed of the motor, r / min; P is the number of pole pairs of the motor.

7. A variable frequency drive overspeed start control device, characterized in that, include: The monitoring data acquisition unit is used to acquire monitoring data of the stator port of the motor in real time at a preset sampling step size; the monitoring data includes the three-phase voltage amplitude and phase at the same moment; The derivative calculation unit is used to calculate the first and second derivatives of the three-phase voltage amplitude and the phase, respectively, based on the time point when the motor loses power and two sets of monitoring data collected after the reference time. The adaptation value calculation unit is used to calculate the time delay t based on the first derivative and the second derivative. d The voltage amplitude and voltage phase adaptation values ​​output by the frequency converter are required when the car is started. The frequency calculation unit is used to generate a two-dimensional array with elements of three-phase voltage amplitude and corresponding acquisition time points based on multiple sets of monitoring data collected after the reference time; and to find the corresponding preset speed-time curve based on the two-dimensional array to solve for the time delay t. d The actual speed of the motor is then calculated, and the appropriate frequency output from the inverter is required when performing a fly start. The start command generation unit is used to control the frequency converter to execute the overspeed start command based on the voltage amplitude adaptation value, the voltage phase adaptation value and the adaptation frequency.

8. The inverter overspeed start control device according to claim 7, characterized in that, Also includes: The control command generation unit is used to control the voltage amplitude of the frequency converter to change at a set rate to P on the frequency converter's Uf curve (based on f) when the voltage amplitude and frequency matching value and frequency matching value of the frequency converter output do not conform to the frequency converter's output Uf curve. n point; The voltage amplitude and frequency of the frequency converter are controlled by P. n The point changes at a set rate to the operating point P set by the frequency converter and motor. set .

9. A variable frequency drive overspeed start control device, characterized in that, include: Memory, used to store computer programs; A processor is configured to invoke and execute the computer program to implement the steps of the inverter overspeed start control method as described in any one of claims 1-6.

10. A storage medium, characterized in that, Includes a software program adapted for execution by a processor of the steps of the inverter overspeed start control method as described in any one of claims 1-6.

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