VF control mode based on adaptive step frequency converter control method, device and medium

Abstract

The application discloses a variable frequency converter control method and device based on an adaptive step length in a VF control mode, and a medium, relates to the technical field of variable frequency converter control, and the method comprises the following steps: obtaining to-be-processed parameters corresponding to a variable frequency converter; resetting an inhibition parameter; comparing a current overcurrent gain with a plurality of preset overcurrent gains respectively, determining a step length parameter, and determining an overcurrent reference point unit value, a low current threshold and a high current threshold based on a current overcurrent reference point; determining a frequency adjustment step length based on a second comparison result and the step length parameter; and obtaining a new adjustment frequency by using the frequency adjustment step length and a current frequency value. The application is used to solve the system oscillation, response lag or integral saturation problem and the frequency overshoot problem caused by the problem of solving the variable frequency converter fault caused by current rise in the prior art, accurately inhibits the problem caused by overcurrent, and improves the stability and safety of the VF control mode variable frequency converter operation.

Description

Technical Field

[0001] This application relates to the field of frequency converter control technology, and in particular to a frequency converter control method, device and medium based on adaptive step size in VF control mode. Background Technology

[0002] In VF control mode for inverter-driven asynchronous motors, the motor current may rise sharply during sudden load changes or excessive acceleration, exceeding the inverter's hardware protection threshold and causing an overcurrent fault and shutdown. Existing technologies address this issue by using simple current limiting or PI regulators for closed-loop current control; however, this approach is prone to system oscillation, response lag, or frequency overshoot due to integral saturation. Summary of the Invention

[0003] In response to the aforementioned problems and technical requirements, the applicant proposes a frequency converter control method, device, and medium based on adaptive step size under VF control mode. This method aims to solve the problems of system oscillation, response lag, or integral saturation, as well as frequency overshoot, that occur in the prior art when dealing with frequency converter failures caused by current rise. It also aims to accurately suppress problems caused by overcurrent and improve the stability and safety of frequency converter operation under VF control mode.

[0004] This application provides a frequency converter control method based on adaptive step size in VF control mode, which divides the operating current value of the frequency converter into a safe zone, a warning zone, and an overcurrent zone. The method includes: Obtain the parameters to be processed corresponding to the frequency converter, including: current frequency value, current speed status indicator, previous speed status indicator, current operating current value, current overcurrent gain, current overcurrent reference point, current overcurrent zone step gain value, and current low frequency threshold. If it is determined that the current speed status indicator has changed compared to the previous speed status indicator, the suppression parameters are reset. The suppression parameters include: overcurrent flag, safe area step size limit, safe area step size, and overcurrent step size. The current overcurrent gain is compared with multiple preset overcurrent gains. Based on the first comparison result, the step size parameter is determined, and the per-unit value of the overcurrent reference point, the low current threshold, and the high current threshold are determined based on the current overcurrent reference point. The step size parameter includes: step size increment, step size decrement, maximum step size limit of the safe zone, maximum step size limit of the warning zone, and maximum step size limit of the overcurrent zone. The low current threshold and the high current threshold are calculated based on the per-unit value of the overcurrent reference point. The current operating current value is compared with the low current threshold and the high current threshold respectively, and the frequency adjustment step size is determined based on the obtained second comparison result and the step size parameter. The new adjustment frequency is obtained by using the frequency adjustment step size and the current frequency value, and then the new adjustment frequency is filtered and output.

[0005] According to the inverter control method based on adaptive step size in VF control mode provided in the embodiments of this application, resetting the suppression parameter includes: Reset the overcurrent flag to zero, and set the overcurrent zone step size to 0. Determine whether the current overcurrent gain is less than the first preset overcurrent gain and whether the frequency converter is in the acceleration / deceleration process; If so, the safe zone step size limit is determined based on the first calculation formula, and the safe zone step size is equal to the safe zone step size limit. Otherwise, the safe zone step size limit and the safe zone step size value are both 1; The first calculation formula includes: LowStepLim = (g2 - ocGain) * 8; Where LowStepLim represents the safe zone step size limit, g2 represents the second preset overcurrent gain, g2 is greater than the first preset overcurrent gain, and ocGain represents the current overcurrent gain.

[0006] According to the inverter control method based on adaptive step size under VF control mode provided in the embodiments of this application, the step size increment and step size decrement are determined based on the first comparison result, including: If the first comparison result indicates that the current overcurrent gain is less than the second preset overcurrent gain, the step size increment is determined to be the difference between the second preset overcurrent gain and the current overcurrent gain, and the step size decrement is 1; if the first comparison result indicates that the current overcurrent gain is greater than or equal to the second preset overcurrent gain, the step size increment is determined to be 1, and the step size decrement is 2. Based on the first comparison result, the maximum step size limit values ​​for the safe zone, the warning zone, and the overcurrent zone are determined, including: If the first comparison result is determined to be that the current overcurrent gain is less than the third preset overcurrent gain, the maximum step size limit of the safe zone is determined based on the second calculation formula, and the maximum step size limit of the warning zone and the maximum step size limit of the overcurrent zone are determined to be preset values, wherein the second preset overcurrent gain is less than the third preset overcurrent gain; If the first comparison result is determined to be that the current overcurrent gain is greater than or equal to the third preset overcurrent gain, the maximum step size limit of the safe zone is determined based on the third calculation formula, and the maximum step size limit of the warning zone and the maximum step size limit of the overcurrent zone are determined based on the fourth calculation formula. The second calculation formula includes: LowMaxStep=cnstMaxStep / (6*ocGain); Where LowMaxStep represents the maximum step size limit of the safe zone, cnstMaxStep represents the preset value, and ocGain represents the current overcurrent gain; The third calculation formula includes: LowMaxStep = MidValue / (6*ocGain)+10; Where, MidValue = cnstHGMaxStep - ocMaxGain * ocGain; Wherein, cnstHGMaxStep represents a preset constant value, and ocMaxGain represents a preset maximum overcurrent gain value; The fourth calculation formula includes: HighMaxStep = MidValue / 16; HighMaxStep includes HighMaxStep1 and HighMaxStep2. HighMaxStep1 represents the maximum step size limit value of the warning zone, and HighMaxStep2 represents the maximum step size limit value of the overcurrent zone.

[0007] According to the inverter control method based on adaptive step size in VF control mode provided in the embodiments of this application, the method determines the per-unit value of the overcurrent reference point, the low current threshold, and the high current threshold based on the current overcurrent reference point, including: The per-unit value of the overcurrent reference point is calculated based on the fifth calculation formula, and the low current threshold and high current threshold are determined based on the per-unit value of the overcurrent reference point. The fifth calculation formula includes: CurLim = (ocPoint<<12) / ocMaxGain; Where CurLim represents the per-unit value of the overcurrent reference point, ocPoint represents the current overcurrent reference point, and the symbol << is the C++ operator, equivalent to multiplying by 2 to the power of 12.

[0008] According to the inverter control method based on adaptive step size under VF control mode provided in the embodiments of this application, the current operating current value is compared with a low current threshold and a high current threshold respectively, and the frequency adjustment step size is determined based on the obtained second comparison result and the step size parameter, including: If the second comparison result indicates that the current operating current value is less than the low current threshold, set the warning zone step value and the overcurrent zone step value to zero. With the overcurrent flag set to zero, the safe zone step size and safe zone step size limit are increased based on the step size increment. Compare the current frequency value with the current low-frequency threshold. If the third comparison result indicates that the current frequency value is less than the current low-frequency threshold, determine the maximum step size limit as the maximum step size limit for the safe zone. If the third comparison result indicates that the current frequency value is greater than or equal to the current low-frequency threshold, determine the maximum step size limit as the maximum step size limit for the warning zone. Adjust the safe zone step size limit so that the safe zone step size limit is less than or equal to the maximum step size limit; Extract the smaller value between the safe zone step size and the adjusted safe zone step size limit, and determine the extracted value as the frequency adjustment step size.

[0009] According to the inverter control method based on adaptive step size under VF control mode provided in the embodiments of this application, the current operating current value is compared with a low current threshold and a high current threshold respectively, and the frequency adjustment step size is determined based on the obtained second comparison result and the step size parameter, including: If the second comparison result is determined to be that the current operating current value is greater than or equal to the low current threshold and less than the high current threshold, the current difference between the current operating current and the previous operating current is calculated. When the current difference is determined to be less than zero, the warning zone step size is reduced, and the larger of the reduced warning zone step size and the preset minimum warning zone step size limit is determined as the new warning zone step size. If the new warning zone step size is determined to be greater than or equal to zero, the safety zone step size is reduced based on the step size reduction, and the reduced safety zone step size must be greater than or equal to zero; if the new overcurrent zone step size is determined to be less than zero, the larger of the safety zone step size and the negative of the warning zone step size is determined as the new safety zone step size. The negative value of the new warning zone step size is determined as the frequency adjustment step size.

[0010] According to the inverter control method based on adaptive step size under VF control mode provided in the embodiments of this application, the current operating current value is compared with a low current threshold and a high current threshold respectively, and the frequency adjustment step size is determined based on the obtained second comparison result and the step size parameter, including: If the second comparison result is determined to be that the current operating current value is greater than or equal to the high current threshold, the safe zone step size value is reduced based on the step size reduction, and the reduced safe zone step size value must be greater than or equal to zero. Calculate the current difference between the current and the previous operating current; if the current difference is less than zero, determine the overcurrent zone step size to be zero; if the current difference is greater than or equal to zero, determine the overcurrent zone step size based on the sixth calculation formula. The sixth calculation formula includes: HighStep2 += ((4 + (ocGain>>4))*gCoff); Where HighStep2 represents the overcurrent step size, ocGain represents the current overcurrent gain, gCoff represents the overcurrent step gain, and the symbol >> is a C++ operation signal, equivalent to dividing by 2 to the power of 4. The negative value of the determined overcurrent step size is used as the frequency adjustment step size.

[0011] According to the inverter control method based on adaptive step size in VF control mode provided in the embodiments of this application, a new adjustment frequency is obtained by using the frequency adjustment step size and the current frequency value, including: If the current speed status indicates a deceleration state, extract the larger value between the frequency adjustment step size and 1, and calculate the negative of the extracted value; sum the adjusted frequency with the negative of the extracted value, calculate the frequency difference between the first summation result and the current frequency value, and calculate the negative of the frequency difference; if the negative of the frequency difference is greater than or equal to zero, determine the new adjusted frequency as the current frequency value, and set the overcurrent flag to 1; if the negative of the frequency difference is less than zero, determine the new adjusted frequency as the first summation result. When the current speed status is identified as an acceleration state, the adjustment frequency and the frequency adjustment step size are summed, and the frequency difference between the second summation result and the current frequency value is calculated. If the frequency difference is greater than or equal to zero, the new adjustment frequency is determined to be the current frequency value, and the overcurrent flag is set to 1; if the frequency difference is less than zero, the new adjustment frequency is determined to be the second summation result.

[0012] This application also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the steps of the inverter control method based on adaptive step size in the VF control mode as described above.

[0013] This application also provides a non-transitory computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the inverter control method based on adaptive step size in the VF control mode as described above.

[0014] The VF control mode provided in this application provides an inverter control method, device, and medium based on adaptive step size. The inverter's operating current value is divided into a safe zone, a warning zone, and an overcurrent zone. The method acquires the parameters to be processed corresponding to the inverter. When the current speed status indicator changes compared to the previous speed status indicator, the suppression parameters are reset. The current overcurrent gain is compared with multiple preset overcurrent gains, and the step size parameter is determined based on the first comparison result. Furthermore, the per-unit value of the overcurrent reference point, the low current threshold, and the high current threshold are determined based on the current overcurrent reference point. This application detects the inverter's operating current value in real time and uses the operating current value, low current threshold, and high current threshold... The system divides the inverter into a safe zone, a warning zone, and an overcurrent zone. The current operating current value is compared with low and high current thresholds, respectively. Based on the second comparison result and step size parameters, the frequency adjustment step size is determined. This application dynamically adjusts the frequency adjustment step size for each zone based on the inverter's current change trend. Furthermore, a new adjustment frequency is obtained using the frequency adjustment step size and the current frequency value. This new adjustment frequency is then filtered and output. This application enables the current in the warning zone or safe zone to quickly and smoothly return to normal after returning to the safe zone, avoiding excessive frequency adjustment and accurately suppressing speed runaway caused by overcurrent, thus improving the stability and safety of the VF control mode inverter operation. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is one of the flowcharts illustrating the inverter control method based on adaptive step size under VF control mode provided in the embodiments of this application; Figure 2 This is the second flowchart of the inverter control method based on adaptive step size under VF control mode provided in the embodiments of this application; Figure 3 This is the third flowchart of the inverter control method based on adaptive step size under VF control mode provided in the embodiments of this application; Figure 4 This is the fourth flowchart of the inverter control method based on adaptive step size under VF control mode provided in the embodiments of this application; Figure 5 This is the fifth flowchart of the inverter control method based on adaptive step size under VF control mode provided in the embodiments of this application; Figure 6This is the sixth flowchart of the inverter control method based on adaptive step size under VF control mode provided in the embodiments of this application; Figure 7 This is the seventh flowchart of the inverter control method based on adaptive step size under VF control mode provided in the embodiments of this application; Figure 8 This is the eighth flowchart of the inverter control method based on adaptive step size under VF control mode provided in the embodiments of this application; Figure 9 This is a schematic diagram of the structure of the electronic device provided in the embodiments of this application. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0018] This application provides a frequency converter control method based on adaptive step size in VF control mode. This method can be applied to smart terminals and servers. This application uses the application of this method in a server as an example for illustration, and some other descriptions in the embodiments are for illustrative purposes only and are not intended to limit the scope of protection of this application, and will not be described in detail thereafter. The specific implementation of the method is as follows... Figure 1 As shown: Step 101: Obtain the parameters to be processed corresponding to the frequency converter.

[0019] The parameters to be processed include: current frequency value, current speed status indicator, previous speed status indicator, current operating current value, current overcurrent gain ocGain, current overcurrent reference point ocPoint, current overcurrent zone step gain value gCoff, and current low-frequency threshold LowFreqLvl. It also includes the current adjustment frequency.

[0020] Step 102: If it is determined that the current speed status indicator has changed compared to the previous speed status indicator, reset the suppression parameter.

[0021] The suppression parameters include: overcurrent flag, safe area step size limit, safe area step size, and overcurrent area step size.

[0022] Specifically, if it is determined that the current speed status indicator has not changed compared to the previous speed status indicator, step 103 is executed directly.

[0023] Step 103: Compare the current overcurrent gain with multiple preset overcurrent gains, determine the step size parameter based on the first comparison result, and determine the per-unit value of the overcurrent reference point, the low current threshold, and the high current threshold based on the current overcurrent reference point.

[0024] The step size parameters include: step size increment, step size decrement, maximum step size limit for the safe zone, maximum step size limit for the warning zone, and maximum step size limit for the overcurrent zone. The low current threshold and high current threshold are calculated based on the per-unit value of the overcurrent reference point.

[0025] Step 104: Compare the current operating current value with the low current threshold and the high current threshold respectively, and determine the frequency adjustment step size based on the obtained second comparison result and the step size parameter.

[0026] Step 105: Use the frequency adjustment step size and the current frequency value to obtain a new adjustment frequency, and then filter the new adjustment frequency before outputting it.

[0027] The VF control mode provided in this application provides an inverter control method, device, and medium based on adaptive step size. The inverter's operating current value is divided into a safe zone, a warning zone, and an overcurrent zone. The method acquires the parameters to be processed corresponding to the inverter. When the current speed status indicator changes compared to the previous speed status indicator, the suppression parameters are reset. The current overcurrent gain is compared with multiple preset overcurrent gains, and the step size parameter is determined based on the first comparison result. Furthermore, the per-unit value of the overcurrent reference point, the low current threshold, and the high current threshold are determined based on the current overcurrent reference point. This application detects the inverter's operating current value in real time and uses the operating current value, low current threshold, and high current threshold... The system divides the inverter into a safe zone, a warning zone, and an overcurrent zone. The current operating current value is compared with low and high current thresholds, respectively. Based on the second comparison result and step size parameters, the frequency adjustment step size is determined. This application dynamically adjusts the frequency adjustment step size for each zone based on the inverter's current change trend. Furthermore, a new adjustment frequency is obtained using the frequency adjustment step size and the current frequency value. This new adjustment frequency is then filtered and output. This application enables the current in the warning zone or safe zone to quickly and smoothly return to normal after returning to the safe zone, avoiding excessive frequency adjustment and accurately suppressing speed runaway caused by overcurrent, thus improving the stability and safety of the VF control mode inverter operation.

[0028] In one specific embodiment, the current operating status signal SpdFlag of the frequency converter is obtained, and the current operating status is identified as constant speed, acceleration or deceleration. If it is determined that the current operating status has changed compared with the previous operating status, the speed status flag spdChange is updated.

[0029] In one specific embodiment, the real-time operating current value of the frequency converter is collected (this current is the three-phase composite current, which is obtained during a 4ms interrupt).

[0030] Specifically, the current overcurrent gain ocGain, the current overcurrent reference point ocPoint, and the current overcurrent zone step gain value gCoff are set by the user based on actual needs, and the user can dynamically set them according to the actual situation.

[0031] In one specific embodiment, the current low-frequency threshold is calculated based on the current overcurrent gain.

[0032] Specifically, LowFreqLvl=((long)(ocGain+50)*30000) / wFmax.

[0033] Where LowFreqLvl represents the current low-frequency threshold, long represents the C language keyword, indicating a long integer data type, ocGain represents the current overcurrent gain, wFmax represents the preset maximum frequency, 30000 is the per-unit value, corresponding to the rated frequency, and 50 is the baseline value to prevent LowFreqLvl from dropping to 0 even when ocGain is too small.

[0034] In one specific embodiment, the detailed implementation of resetting the suppression parameter is described in [reference needed]. Figure 2 : Reset the suppression parameters based on the current overcurrent gain and current speed status flag.

[0035] Specifically, in step 201, the overcurrent flag ocFlag is reset to zero, and the overcurrent step value HighStep is set to 0.

[0036] Step 202: Determine whether the current overcurrent gain is less than the first preset overcurrent gain and whether the frequency converter is in the acceleration / deceleration process. If yes, proceed to step 203; otherwise, proceed to step 204.

[0037] Step 203: Determine the safe zone step size limit value LowStepLim based on the first calculation formula. The safe zone step size value LowStep is equal to the safe zone step size limit value.

[0038] Step 204: The safe zone step size limit value LowStepLim and the safe zone step size value LowStep are both set to 1.

[0039] The first calculation formula is shown in formula (1): LowStepLim=(g2- ocGain)*8…………(1) Where LowStepLim represents the safe zone step size limit, g2 represents the second preset overcurrent gain, which is greater than the first preset overcurrent gain g1, and ocGain represents the current overcurrent gain.

[0040] Specifically, when it is determined that the current rotation speed state identifier has not changed compared with the previous rotation speed state identifier, processing is continued based on the previous suppression parameter.

[0041] Wherein, the suppression parameter is not a parameter corresponding to each interval (safe area, early warning area and overcurrent area) in the present application, and for other parameters that are not reset, processing can be continued based on the parameter value in the previous iteration.

[0042] In a specific embodiment, for the specific implementation of determining the step increment and step decrement based on the first comparison result, refer to Figure 3 : Step 301: Compare the current overcurrent gain with a second preset overcurrent gain.

[0043] Step 302: When it is determined that the first comparison result is that the current overcurrent gain is less than the second preset overcurrent gain, determine that the step increment is the difference between the second preset overcurrent gain and the current overcurrent gain, and the step decrement is 1.

[0044] Specifically, if ocGain<g2, step decrement subStep=1 and step increment addStep=g2-ocGain.

[0045] Step 303: When it is determined that the first comparison result is that the current overcurrent gain is greater than or equal to the second preset overcurrent gain, determine that the step increment is 1 and the step decrement is 2.

[0046] Specifically, if ocGain>=g2, step decrement subStep=2 and step increment addStep=1.

[0047] In a specific embodiment, for the specific implementation of determining the maximum step limit value of the safe area, the maximum step limit value of the early warning area and the maximum step limit value of the overcurrent area based on the first comparison result, refer to Figure 4 : Step 401: Compare the current overcurrent gain with a third preset overcurrent gain.

[0048] Wherein, the second preset overcurrent gain is smaller than the third preset overcurrent gain.

[0049] Step 402: When it is determined that the first comparison result is that the current overcurrent gain is less than the third preset overcurrent gain, determine the maximum step limit value of the safe area based on a second calculation formula, and determine that the maximum step limit value of the early warning area and the maximum step limit value of the overcurrent area are the preset value cnstMaxStep.

[0050] Wherein, the second calculation formula is shown in formula (2): LowMaxStep=cnstMaxStep / (6*ocGain)……(2) wherein, LowMaxStep represents the maximum step limit value in the safety zone, cnstMaxStep represents a preset value, and ocGain represents the current overcurrent gain.

[0051] Specifically, if ocGain < g3, LowMaxStep is obtained based on formula (2), and HighMaxStep1 and HighMaxStep2 are equal to cnstMaxStep.

[0052] Step 403: when it is determined that the first comparison result indicates that the current overcurrent gain is greater than or equal to a third preset overcurrent gain, determine the maximum step limit value of the safety zone based on a third calculation formula, and determine the maximum step limit value of the early warning zone and the maximum step limit value of the overcurrent zone based on a fourth calculation formula.

[0053] wherein, the third calculation formula is shown as formula (3): LowMaxStep = MidValue / (6*ocGain)+10……(3) wherein, MidValue= cnstHGMaxStep-ocMaxGain*ocGain.

[0054] wherein, cnstHGMaxStep represents a preset constant value, and ocMaxGain represents a preset maximum overcurrent gain.

[0055] wherein, the fourth calculation formula is shown as formula (4): HighMaxStep = MidValue / 16; wherein, HighMaxStep includes HighMaxStep1 and HighMaxStep2, HighMaxStep1 represents the maximum step limit value of the early warning zone, and HighMaxStep2 represents the maximum step limit value of the overcurrent zone.

[0056] Specifically, if ocGain >= g3, LowMaxStep is obtained based on formula (3), and HighMaxStep1 and HighMaxStep2 are obtained based on formula (4).

[0057] In a specific embodiment, the specific implementation of determining the per-unit value of the overcurrent reference point, the low current threshold and the high current threshold based on the current overcurrent reference point comprises: calculating the per-unit value of the overcurrent reference point based on a fifth calculation formula, and determining the low current threshold and the high current threshold based on the per-unit value of the overcurrent reference point.

[0058] The fifth calculation formula is shown in formula (5): CurLim = (ocPoint<<12) / ocMaxGain......(5) Where CurLim represents the per-unit value of the overcurrent reference point, ocPoint represents the current overcurrent reference point, and the symbol << is the C++ operator, equivalent to multiplying by 2 to the power of 12.

[0059] Specifically, the low current threshold ILowLim = k1 * CurLim, and the high current threshold IHighLim = CurLim * k2.

[0060] Where k1 and k2 are constants between 0 and 1, and k1 is less than k2.

[0061] In one specific embodiment, the current operating current value is compared with a low current threshold and a high current threshold, respectively. The frequency adjustment step size is determined based on the obtained second comparison result and the step size parameter. For details on this implementation, please refer to [link to relevant documentation]. Figure 5 : Step 501: If the second comparison result is determined to be that the current operating current value is less than the low current threshold, set the warning zone step value and the overcurrent zone step value to zero.

[0062] Step 502: If the overcurrent flag is determined to be zero, increase the safety zone step size and safety zone step size limit value based on the step size increment.

[0063] Step 503: Compare the current frequency value with the current low-frequency threshold. If the third comparison result indicates that the current frequency value is less than the current low-frequency threshold, determine the maximum step size limit as the maximum step size limit for the safe zone. If the third comparison result indicates that the current frequency value is greater than or equal to the current low-frequency threshold, determine the maximum step size limit as the maximum step size limit for the warning zone.

[0064] Step 504: Adjust the safe zone step size limit value so that the safe zone step size limit value is less than or equal to the maximum step size limit value.

[0065] Step 505: Extract the smaller value between the safe zone step size value and the adjusted safe zone step size limit value, and determine the extracted value as the frequency adjustment step size.

[0066] Specifically, if the current operating current value is less than the low current threshold, the inverter is operating in the safe zone. The safe zone step size and limit value can be increased to allow acceleration.

[0067] In one specific embodiment, the current operating current value is compared with a low current threshold and a high current threshold, respectively. The frequency adjustment step size is determined based on the obtained second comparison result and the step size parameter. For details on this implementation, please refer to [link to relevant documentation]. Figure 6 : Step 601: If the second comparison result is determined to be that the current operating current value is greater than or equal to the low current threshold and less than the high current threshold, calculate the current difference between the current operating current and the previous operating current.

[0068] Step 602: When it is determined that the current difference is less than zero, the warning zone step size is reduced, and the larger of the reduced warning zone step size and the preset minimum warning zone step size limit is determined as the new warning zone step size.

[0069] Step 603: If the new warning zone step size is determined to be greater than or equal to zero, the safe zone step size is reduced synchronously based on the step size reduction, and the reduced safe zone step size must be greater than or equal to zero; if the new warning zone step size is determined to be less than zero, the larger of the safe zone step size and the negative of the warning zone step size is determined as the new safe zone step size.

[0070] Step 604: Determine the negative value of the new warning zone step size as the frequency adjustment step size.

[0071] Specifically, the inverter is considered to be operating in the warning zone when the current value is greater than or equal to the low current threshold, but less than the high current threshold. During this process, the safety zone step size is adjusted synchronously to ensure stable operation as the current falls back from the warning zone to the safety zone.

[0072] In one specific embodiment, the current operating current value is compared with a low current threshold and a high current threshold, respectively. The frequency adjustment step size is determined based on the obtained second comparison result and the step size parameter. For details on this implementation, please refer to [link to relevant documentation]. Figure 7 : Step 701: If the second comparison result is determined to be that the current operating current value is greater than or equal to the high current threshold, the safe zone step size value is reduced based on the step size reduction, and the reduced safe zone step size value needs to be greater than or equal to zero.

[0073] Step 702: Calculate the current difference between the current and the previous operating current; if the current difference is less than zero, determine the overcurrent zone step size to be zero; if the current difference is greater than or equal to zero, determine the overcurrent zone step size based on the sixth calculation formula.

[0074] The sixth calculation formula is shown in formula (6): HighStep2 += ((4 + (ocGain>>4))*gCoff)......(6) Where HighStep2 represents the overcurrent step size, ocGain represents the current overcurrent gain, gCoff represents the overcurrent step gain, and the symbol >> is a C++ operation signal, equivalent to dividing by 2 to the power of 4.

[0075] Step 703: The negative value of the determined overcurrent zone step size is determined as the frequency adjustment step size.

[0076] In one specific embodiment, the detailed implementation of obtaining the new adjustment frequency using the frequency adjustment step size and the current frequency value can be found in [link to relevant documentation]. Figure 8 : Step 801: Determine whether the current speed state represents a deceleration state or an acceleration state. If it is a deceleration state, proceed to step 802; if it is an acceleration state, proceed to step 804.

[0077] Step 802: Extract the larger value between the frequency adjustment step size and 1, and calculate the negative of the extracted value; sum the adjusted frequency and the negative of the extracted value, calculate the frequency difference between the first summation result and the current frequency value, and calculate the negative of the frequency difference.

[0078] The first summation result is greater than or equal to zero.

[0079] Step 803: If the negative value of the frequency difference is greater than or equal to zero, determine the new adjustment frequency value as the current frequency value and set the overcurrent flag to 1; if the negative value of the frequency difference is less than zero, determine the new adjustment frequency as the first summation result.

[0080] Step 804: Summing the adjusted frequency and the frequency adjustment step size, and calculating the frequency difference between the second summation result and the current frequency value.

[0081] Step 805: If the frequency difference is greater than or equal to zero, determine the new adjustment frequency as the current frequency value and set the overcurrent flag to 1; if the frequency difference is less than zero, determine the new adjustment frequency as the second summation result.

[0082] Specifically, the real-time frequency value and the adjusted frequency can be understood as two parallel curves, with the real-time frequency changing according to its own fixed curve trend. When no overcurrent occurs, the adjusted frequency curve can be understood as being equivalent to the real-time frequency curve; when an overcurrent occurs, the adjusted frequency is adjusted, that is, the adjusted frequency curve is changed, and the adjusted frequency is filtered and output.

[0083] At this point, it can be understood that the output frequency curve always follows the adjustment frequency curve, and the output frequency is the frequency after the adjustment frequency filter.

[0084] Specifically, this application uses a frequency converter with an output voltage of 380V, a rated power of 3.7KW, and a rated current of 9.2A; and a three-phase asynchronous motor with a voltage of 380V, a power of 7.5KW, a rated power of 15A, a speed of 1445rpm, 4 poles, and a frequency of 50HZ. Testing showed that it effectively suppressed overcurrent during instantaneous loading and unloading.

[0085] For example, the parameters are set to an overcurrent zone step gain of 8, a safe zone step of 1, an overcurrent gain of 20, and an overcurrent reference point of 100% (percentage of the inverter's rated current), where the step is a per-unit value and 30000 corresponds to the rated frequency.

[0086] This application implements three levels of current judgment: safe zone, warning zone, and overcurrent zone. It compares the dynamically obtained current value with the calculated current threshold and dynamically determines the frequency adjustment step size for each zone based on the current change trend.

[0087] In the safe zone, the frequency adjustment step size is gradually increased, allowing the frequency to rise / fall normally. In the warning zone, the frequency adjustment step size in the safe zone is decreased based on the current change trend, while the frequency adjustment step size in the warning zone is increased, slightly limiting frequency changes and preventing overcurrent. In the overcurrent zone, the frequency adjustment step size in the safe zone is rapidly decreased, while the frequency adjustment step size in the warning zone is drastically increased, rapidly reducing the frequency and preventing overcurrent dripping.

[0088] This application utilizes a dynamic frequency adjustment step size. When the current approaches the overcurrent threshold, the frequency rise / fall step size is reduced, and the normal step size is quickly and smoothly restored after the current returns to the safe region. Simultaneously, the suppression strength is adjusted according to the current change trend. This adaptive adjustment helps avoid over-regulation of the frequency.

[0089] This application controls the output frequency by dynamically adjusting the step size in stages, accurately suppressing speed runaway caused by overcurrent, and improving the stability and safety of VF mode frequency converter operation.

[0090] Figure 9 An example is a schematic diagram of the physical structure of an electronic device, such as... Figure 9 As shown, the electronic device may include a processor 901, a communication interface 902, a memory 903, and a communication bus 904. The processor 901, communication interface 902, and memory 903 communicate with each other via the communication bus 904. The processor 901 can call logic instructions from the memory 903 to execute a frequency converter control method based on adaptive step size in VF control mode.

[0091] Furthermore, the logical instructions in the aforementioned memory 903 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part 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 the present invention. 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.

[0092] On the other hand, the present invention also provides a computer program product, the computer program product including a computer program stored on a non-transitory computer-readable storage medium, the computer program including program instructions, and when the program instructions are executed by a computer, the computer is able to execute the inverter control method based on adaptive step size in VF control mode provided by the above methods.

[0093] In another aspect, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to perform the inverter control method based on adaptive step size in the VF control mode provided in the above embodiments.

[0094] The device embodiments described above are merely illustrative. 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 modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0095] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0096] Finally, it should be noted that the above descriptions are merely preferred embodiments of this application, and this application is not limited to the above embodiments. It is understood that other improvements and variations directly derived or conceived by those skilled in the art without departing from the spirit and concept of this application should be considered to be included within the protection scope of this application.

Claims

1. A frequency converter control method based on adaptive step size in VF control mode, characterized in that, The method categorizes the operating current value of the frequency converter into a safe zone, a warning zone, and an overcurrent zone, and includes: Obtain the parameters to be processed corresponding to the frequency converter, including: current frequency value, current speed status indicator, previous speed status indicator, current operating current value, current overcurrent gain, current overcurrent reference point, current overcurrent zone step gain value, and current low frequency threshold. If it is determined that the current speed status indicator has changed compared to the previous speed status indicator, the suppression parameters are reset. The suppression parameters include: overcurrent flag, safe area step size limit, safe area step size, and overcurrent step size. The current overcurrent gain is compared with multiple preset overcurrent gains. Based on the first comparison result, the step size parameter is determined, and the per-unit value of the overcurrent reference point, the low current threshold, and the high current threshold are determined based on the current overcurrent reference point. The step size parameter includes: step size increment, step size decrement, maximum step size limit of the safe zone, maximum step size limit of the warning zone, and maximum step size limit of the overcurrent zone. The low current threshold and the high current threshold are calculated based on the per-unit value of the overcurrent reference point. The current operating current value is compared with the low current threshold and the high current threshold respectively, and the frequency adjustment step size is determined based on the obtained second comparison result and the step size parameter. The new adjustment frequency is obtained by using the frequency adjustment step size and the current frequency value, and then the new adjustment frequency is filtered and output.

2. The inverter control method based on adaptive step size under VF control mode according to claim 1, characterized in that, Reset suppression parameters, including: Reset the overcurrent flag to zero, and set the overcurrent zone step size to 0. Determine whether the current overcurrent gain is less than the first preset overcurrent gain and whether the frequency converter is in the acceleration / deceleration process; If so, the safe zone step size limit is determined based on the first calculation formula, and the safe zone step size is equal to the safe zone step size limit. Otherwise, the safe zone step size limit and the safe zone step size value are both 1; The first calculation formula includes: LowStepLim = (g2 - ocGain) * 8; Where LowStepLim represents the safe zone step size limit, g2 represents the second preset overcurrent gain, g2 is greater than the first preset overcurrent gain, and ocGain represents the current overcurrent gain.

3. The inverter control method based on adaptive step size under VF control mode according to claim 1, characterized in that, Based on the first comparison result, the step size increment and step size decrement are determined, including: If the first comparison result indicates that the current overcurrent gain is less than the second preset overcurrent gain, the step size increment is determined to be the difference between the second preset overcurrent gain and the current overcurrent gain, and the step size decrement is 1; if the first comparison result indicates that the current overcurrent gain is greater than or equal to the second preset overcurrent gain, the step size increment is determined to be 1, and the step size decrement is 2. Based on the first comparison result, the maximum step size limit values ​​for the safe zone, the warning zone, and the overcurrent zone are determined, including: If the first comparison result is determined to be that the current overcurrent gain is less than the third preset overcurrent gain, the maximum step size limit of the safe zone is determined based on the second calculation formula, and the maximum step size limit of the warning zone and the maximum step size limit of the overcurrent zone are determined to be preset values, wherein the second preset overcurrent gain is less than the third preset overcurrent gain; If the first comparison result is determined to be that the current overcurrent gain is greater than or equal to the third preset overcurrent gain, the maximum step size limit of the safe zone is determined based on the third calculation formula, and the maximum step size limit of the warning zone and the maximum step size limit of the overcurrent zone are determined based on the fourth calculation formula. The second calculation formula includes: LowMaxStep=cnstMaxStep / (6*ocGain); Where LowMaxStep represents the maximum step size limit of the safe zone, cnstMaxStep represents the preset value, and ocGain represents the current overcurrent gain; The third calculation formula includes: LowMaxStep = MidValue / (6*ocGain)+10; Where MidValue = cnstHGMaxStep - ocMaxGain * ocGain; Wherein, cnstHGMaxStep represents a preset constant value, and ocMaxGain represents a preset maximum overcurrent gain value; The fourth calculation formula includes: HighMaxStep = MidValue / 16; HighMaxStep includes HighMaxStep1 and HighMaxStep2. HighMaxStep1 represents the maximum step size limit value of the warning zone, and HighMaxStep2 represents the maximum step size limit value of the overcurrent zone.

4. The inverter control method based on adaptive step size under VF control mode according to claim 1, characterized in that, Based on the current overcurrent reference point, determine the per-unit value of the overcurrent reference point, the low current threshold, and the high current threshold, including: The per-unit value of the overcurrent reference point is calculated based on the fifth calculation formula, and the low current threshold and high current threshold are determined based on the per-unit value of the overcurrent reference point. The fifth calculation formula includes: CurLim = (ocPoint<<12) / ocMaxGain; Where CurLim represents the per-unit value of the overcurrent reference point, ocPoint represents the current overcurrent reference point, and the symbol << is the C++ operator, equivalent to multiplying by 2 to the power of 12.

5. The inverter control method based on adaptive step size under VF control mode according to any one of claims 1-4, characterized in that, The current operating current value is compared with the low current threshold and the high current threshold, respectively. Based on the obtained second comparison result and the step size parameter, the frequency adjustment step size is determined, including: If the second comparison result indicates that the current operating current value is less than the low current threshold, set the warning zone step value and the overcurrent zone step value to zero. With the overcurrent flag set to zero, the safe zone step size and safe zone step size limit are increased based on the step size increment. Compare the current frequency value with the current low-frequency threshold. If the third comparison result indicates that the current frequency value is less than the current low-frequency threshold, determine the maximum step size limit as the maximum step size limit for the safe zone. If the third comparison result indicates that the current frequency value is greater than or equal to the current low-frequency threshold, determine the maximum step size limit as the maximum step size limit for the warning zone. Adjust the safe zone step size limit so that the safe zone step size limit is less than or equal to the maximum step size limit; Extract the smaller value between the safe zone step size and the adjusted safe zone step size limit, and determine the extracted value as the frequency adjustment step size.

6. The inverter control method based on adaptive step size under VF control mode according to any one of claims 1-4, characterized in that, The current operating current value is compared with the low current threshold and the high current threshold, respectively. Based on the obtained second comparison result and the step size parameter, the frequency adjustment step size is determined, including: If the second comparison result is determined to be that the current operating current value is greater than or equal to the low current threshold and less than the high current threshold, the current difference between the current operating current and the previous operating current is calculated. When the current difference is determined to be less than zero, the warning zone step size is reduced, and the larger of the reduced warning zone step size and the preset minimum warning zone step size limit is determined as the new warning zone step size. If the new warning zone step size is determined to be greater than or equal to zero, the safety zone step size is reduced based on the step size reduction, and the reduced safety zone step size must be greater than or equal to zero; if the new overcurrent zone step size is determined to be less than zero, the larger of the safety zone step size and the negative of the warning zone step size is determined as the new safety zone step size. The negative value of the new warning zone step size is determined as the frequency adjustment step size.

7. The inverter control method based on adaptive step size under VF control mode according to any one of claims 1-4, characterized in that, The current operating current value is compared with the low current threshold and the high current threshold, respectively. Based on the obtained second comparison result and the step size parameter, the frequency adjustment step size is determined, including: If the second comparison result is determined to be that the current operating current value is greater than or equal to the high current threshold, the safe zone step size value is reduced based on the step size reduction, and the reduced safe zone step size value must be greater than or equal to zero. Calculate the current difference between the current and the previous operating current; if the current difference is less than zero, determine the overcurrent zone step size to be zero; if the current difference is greater than or equal to zero, determine the overcurrent zone step size based on the sixth calculation formula. The sixth calculation formula includes: HighStep2 += ((4 + (ocGain>>4))*gCoff); Where HighStep2 represents the overcurrent step size, ocGain represents the current overcurrent gain, gCoff represents the overcurrent step gain, and the symbol >> is a C++ operation signal, equivalent to dividing by 2 to the power of 4. The negative value of the determined overcurrent step size is used as the frequency adjustment step size.

8. The inverter control method based on adaptive step size under VF control mode according to any one of claims 1-4, characterized in that, The new adjustment frequency is obtained using the frequency adjustment step size and the current frequency value, including: If the current speed status indicates a deceleration state, extract the larger value between the frequency adjustment step size and 1, and calculate the negative of the extracted value; sum the adjusted frequency with the negative of the extracted value, calculate the frequency difference between the first summation result and the current frequency value, and calculate the negative of the frequency difference; if the negative of the frequency difference is greater than or equal to zero, determine the new adjusted frequency as the current frequency value, and set the overcurrent flag to 1; if the negative of the frequency difference is less than zero, determine the new adjusted frequency as the first summation result. When the current speed status is indicated as an acceleration state, the adjustment frequency and the frequency adjustment step size are summed, and the frequency difference between the second summation result and the current frequency value is calculated. If the frequency difference is greater than or equal to zero, the new adjustment frequency is determined as the current frequency value, and the overcurrent flag is set to 1. If the frequency difference is less than zero, the new adjustment frequency is determined as the second summation result.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the inverter control method based on adaptive step size in VF control mode as described in any one of claims 1 to 8.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the steps of the inverter control method based on adaptive step size in VF control mode as described in any one of claims 1 to 8.

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