Motor power monitoring method based on three-phase split-phase acquisition and related equipment

Abstract

The invention provides a motor power monitoring method based on three-phase split-phase acquisition and related equipment. In the method, a power monitoring device firstly obtains operating parameters such as a three-phase current change rate and a rotating speed change rate of a motor so as to judge whether the power of the motor is in a stable state or not; when the motor is in a stable state, the low first sampling frequency and the high first filtering intensity are adopted, the monitoring precision requirement can be met, and the data processing amount can be reduced; when the motor is in an unstable state, a higher second sampling frequency and a lower second filtering intensity are adopted, the higher sampling frequency avoids missing a key voltage drop moment in a dynamic process, and the lower filtering intensity reduces the smoothing effect of filtering on an instantaneous value. And finally, the power monitoring equipment combines the three-phase pulse width modulation duty ratio to calculate three-phase instantaneous power and sums the three-phase instantaneous power to obtain total power. According to the method, the sampled data better fits the actual running state of the motor, and the accuracy of motor power monitoring is improved.

Description

Technical Field

[0001] This application relates to the field of motor control, and in particular to a motor power monitoring method and related equipment based on three-phase phase-by-phase acquisition. Background Technology

[0002] With the continuous improvement of industrial automation, motors are being used more and more widely in industrial production. Motor power monitoring, as an important component of motor control systems, is of great significance for ensuring safe motor operation and achieving energy consumption management.

[0003] In related technologies, a common approach is to use three-phase phase-by-phase data acquisition technology, integrating it into the power monitoring device inside the motor. Specifically, the monitoring device uses three independent current sensors to collect the three-phase current of the motor, and simultaneously collects the DC bus voltage. The system periodically collects these signals at a fixed sampling frequency, and after acquiring the sampled data, calculates the total power of the motor.

[0004] However, during rapid acceleration, deceleration, or sudden load changes in a motor, the phase current of the motor undergoes instantaneous changes, causing rapid discharge of the DC bus capacitor and resulting in a momentary drop in bus voltage. If the bus voltage value is collected at a specific frequency at this time, the exact moment the voltage drops to its lowest value may be missed, leading to an overestimation of the collected voltage value and inaccurate calculations of the motor's instantaneous power during the entire dynamic impact period. Summary of the Invention

[0005] This application provides a motor power monitoring method and related equipment based on three-phase phase-by-phase acquisition, which can alleviate the technical problem of insufficient sampling timeliness in the motor power monitoring process and improve the accuracy of motor power monitoring.

[0006] In a first aspect, this application provides a motor power monitoring method based on three-phase phase-by-phase acquisition, applied to a power monitoring device installed inside a motor. The method includes: acquiring the motor's operating parameters, including the rate of change of three-phase current and the rate of change of motor speed; comparing the operating parameters with a rate of change threshold to determine whether the motor power is in a stable state; if the motor power is in a stable state, sampling the measured values ​​of the motor's three-phase current and DC bus voltage using a first sampling frequency to obtain first sampling data, and filtering the first sampling data using a first filtering intensity to obtain a first sampling value; if the motor power is not in a stable state, sampling the measured values ​​of the motor's three-phase current and DC bus voltage using a second sampling frequency to obtain second sampling data, and filtering the second sampling data using a second filtering intensity to obtain a second sampling value, wherein the second sampling frequency is higher than the first sampling frequency and the second filtering intensity is lower than the first filtering intensity; acquiring the motor's three-phase pulse width modulation duty cycle, and calculating the motor's three-phase instantaneous power by combining the first sampling value or the second sampling value; summing the three-phase instantaneous power to obtain the total motor power.

[0007] By adopting the above technical solution, the power monitoring equipment first acquires operating parameters such as the three-phase current change rate and speed change rate of the motor to determine whether the motor power is in a stable state. When the motor is in a stable state, a lower first sampling frequency and a higher first filter strength are used, which meets the monitoring accuracy requirements while reducing the amount of data processing. When the motor is in an unstable state, a higher second sampling frequency and a lower second filter strength are used. The higher sampling frequency allows the power monitoring equipment to capture signal changes more intensively, avoiding missing critical voltage drop moments during dynamic processes and alleviating the problem of insufficient sampling timeliness that may occur under a fixed sampling frequency. The lower filter strength allows the power monitoring equipment to retain more instantaneous change information and reduces the smoothing effect of filtering on instantaneous values. Finally, the power monitoring equipment calculates the three-phase instantaneous power by combining the three-phase pulse width modulation duty cycle and sums them to obtain the total power. This method, by dynamically adjusting the sampling frequency and filter strength, makes the sampled data more closely match the actual operating state of the motor, thus improving the accuracy of motor power monitoring.

[0008] In conjunction with some embodiments of the first aspect, in some embodiments, the operating parameters are compared with a rate of change threshold to determine whether the motor power is in a stable state. Specifically, this includes: comparing the rate of change of the three-phase current with a first rate of change threshold, and comparing the rate of change of the motor speed with a second rate of change threshold; if the rate of change of the three-phase current does not exceed the first rate of change threshold, and the rate of change of the motor speed does not exceed the second rate of change threshold, then the motor power is determined to be in a stable state; if the rate of change of the three-phase current exceeds the first rate of change threshold, or the rate of change of the motor speed exceeds the second rate of change threshold, then the motor power is determined to be in an unstable state.

[0009] By employing the above technical solution, the power monitoring equipment compares the three-phase current change rate with a first change rate threshold and the motor speed change rate with a second change rate threshold to determine whether the motor power is stable. The change in three-phase current directly reflects the fluctuation of the motor's input energy, while the speed change rate reflects changes in the motor's load and operating state. When neither exceeds its corresponding threshold, it indicates that the motor is operating smoothly and the power is stable. If either exceeds its threshold, it indicates that the motor may be undergoing a dynamic process such as rapid acceleration, deceleration, or sudden load changes, resulting in unstable power. This method uses dual judgment, integrating two key indicators—current and speed—to more comprehensively and accurately identify the motor's operating state, ensuring that appropriate monitoring strategies are adopted for the motor under different conditions, and further improving the accuracy of power monitoring.

[0010] In conjunction with some embodiments of the first aspect, in some embodiments, after determining that the motor power is not in a stable state, the method further includes: summing the absolute values ​​of the change rates of the three-phase currents to obtain an overall impact change value, which is used to represent the degree of current impact experienced by the motor due to external commands or load changes; comparing the overall impact change value with an impact threshold to determine the degree of instability of the motor, which includes a normal fluctuation state and a high current impact state; if the overall impact change value reaches the impact threshold, it is determined that the motor is in a high current impact state; if the overall impact change value does not reach the impact threshold, it is determined that the motor is in a normal fluctuation state.

[0011] By adopting the above technical solution, after determining that the motor power is unstable, the power monitoring equipment sums the absolute values ​​of the three-phase current change rates to obtain the overall impact change value. Based on this overall impact change value, the degree of current impact is measured, and the overall impact change value is compared with an impact threshold to determine the degree of motor power instability. When the overall impact change value reaches the impact threshold, the motor is determined to be in a high-current impact state, at which point the motor faces more drastic dynamic changes. When the overall impact change value does not reach the impact threshold, the motor is in a normal fluctuation state. The power monitoring equipment's finer classification of instability levels makes subsequent monitoring more targeted. For example, more refined sampling and processing methods can be adopted under high-current impact conditions, while strategies can be appropriately adjusted under normal fluctuation conditions to avoid resource waste. This ensures monitoring accuracy while improving the adaptability and efficiency of the monitoring method.

[0012] In conjunction with some embodiments of the first aspect, in some embodiments, after determining that the motor is in a high-current impact state, the method further includes: continuously calculating the sum of the absolute values ​​of the three-phase current change rates to obtain an overall impact change value sequence; based on the overall impact change value sequence, determining the impact inflection point moment when the overall impact change value changes from increasing to decreasing, the impact inflection point moment being used to indicate the moment when the severity of the current impact reaches its peak; determining the first DC bus voltage sample value obtained after the impact inflection point moment and at a second sampling frequency as the valley value of the voltage drop during the high-current impact state; obtaining the measured three-phase current values ​​at the same moment as the valley value, and combining the valley value to obtain third sampling data; filtering the third sampling data using a second filtering intensity to obtain a third sampling value, and using the third sampling value as the second sampling value.

[0013] By adopting the above technical solution, after determining that the motor is under a high-current impact, the power monitoring equipment continuously calculates the overall impact change value sequence to find the impact inflection point, i.e., the moment when the overall impact change value changes from increasing to decreasing, which corresponds to the peak value of the most severe current impact. Then, the power monitoring equipment takes the first DC bus voltage sample value at the second sampling frequency after the impact inflection point as the voltage drop trough value, and obtains the measured three-phase current values ​​at the same moment, which are then filtered and used as the sample values ​​at that moment. This method, by determining the key sampling data at the impact inflection point, avoids the problem of inaccurate voltage and current value acquisition caused by improper sampling timing during violent dynamic processes, thereby significantly improving the accuracy of instantaneous power calculation of the motor under high-current impact conditions.

[0014] In some embodiments of the first aspect, the method of obtaining the three-phase pulse width modulation duty cycle of the motor and calculating the three-phase instantaneous power of the motor by combining the first sample value or the second sample value specifically includes: obtaining the three-phase pulse width modulation duty cycle of the motor and calculating the equivalent voltage of the three phases by combining the DC bus voltage value of the first sample value or the second sample value; determining the midpoint voltage of the three-phase voltage by the average value of the three-phase equivalent voltage; calculating the difference between the three-phase equivalent voltage and the midpoint voltage, and obtaining the three-phase instantaneous power of the motor by combining the measured value of the three-phase current of the first sample value or the second sample value.

[0015] By adopting the above technical solution, the power monitoring equipment obtains the three-phase pulse width modulation duty cycle, calculates the three-phase equivalent voltage by combining it with the sampled DC bus voltage value, determines the neutral point voltage by the average value of the equivalent voltage, and finally calculates the difference between the equivalent voltage and the neutral point voltage and combines it with the measured three-phase current value to obtain the three-phase instantaneous power. The three-phase pulse width modulation duty cycle reflects the voltage regulation of each phase of the motor, and combined with the DC bus voltage, it accurately obtains the equivalent operating voltage of each phase. The determination of the neutral point voltage provides a benchmark for calculating the actual voltage of each phase relative to the neutral point, making the difference between the equivalent voltage and the neutral point voltage more closely match the true voltage state of each phase of the motor. Combining this difference with the measured current value of the corresponding phase to calculate the instantaneous power makes the calculation of the three-phase instantaneous power more consistent with the actual electrical characteristics of the motor operation, thereby improving the accuracy of the total motor power calculation.

[0016] In conjunction with some embodiments of the first aspect, in some embodiments, the setting of the second sampling frequency and the second filtering intensity specifically includes: summing the rate of change of the three-phase current to obtain the overall impact change value; normalizing the overall impact change value to obtain a dynamic intensity factor used to represent the severity of motor fluctuations; and adjusting the dynamic intensity factor within a preset frequency change range and a preset filtering intensity change range, wherein the dynamic intensity factor is positively correlated with the second sampling frequency and negatively correlated with the second filtering intensity.

[0017] By adopting the above technical solution, the power monitoring equipment sums the three-phase current change rates to obtain the overall impact change value, which is then normalized to obtain the dynamic intensity factor. Based on the dynamic intensity factor, the second sampling frequency and the second filter intensity are adjusted within a preset range. The dynamic intensity factor is positively correlated with the second sampling frequency and negatively correlated with the second filter intensity. The dynamic intensity factor quantifies the severity of motor fluctuations. More severe fluctuations result in a larger dynamic intensity factor, requiring a higher sampling frequency to capture more details, while the filter intensity is reduced to preserve instantaneous changes. Conversely, when fluctuations are smaller, the sampling frequency can be appropriately reduced, and the filter intensity can be increased to smooth noise. This method dynamically adjusts parameters based on the actual fluctuations of the motor, enabling the sampling frequency and filter intensity to adaptively match the motor's operating state. This avoids the problems of insufficient sampling or over-smoothing that may occur with fixed parameters under different fluctuation levels, further optimizing the accuracy and efficiency of power monitoring.

[0018] In conjunction with some embodiments of the first aspect, in some embodiments, adjustments are made within a preset frequency variation range and a preset filter intensity variation range based on a dynamic intensity factor. Specifically, this includes: calculating the difference between the upper and lower limits of the preset frequency variation range and calculating the difference between the upper and lower limits of the preset filter intensity variation range; multiplying the difference between the upper and lower limits of the frequency and the difference between the upper and lower limits of the filter intensity by the dynamic intensity factor to obtain the frequency increment and the filter intensity adjustment amount; adding the frequency increment to the lower limit of the preset frequency variation range to obtain the second sampling frequency; and subtracting the filter intensity adjustment amount from the upper limit of the preset filter intensity variation range to obtain the second filter intensity.

[0019] By adopting the above technical solution, the power monitoring equipment calculates the difference between the upper and lower limits of the preset frequency range and the difference between the upper and lower limits of the preset filter intensity range. These differences are then multiplied by the dynamic intensity factor to obtain the frequency increment and filter intensity adjustment, respectively. Finally, the second sampling frequency and the second filter intensity are obtained by calculating the difference between these values ​​and the upper and lower limits of the range (preset frequency range or preset filter intensity range). This calculation method combines the dynamic intensity factor with the specific values ​​of the parameter range, making parameter adjustment more quantitative. Specifically, the frequency increment is proportional to the dynamic intensity factor, ensuring that the more severe the fluctuation, the more significant the increase in sampling frequency. Similarly, the filter intensity adjustment is also proportional to the dynamic intensity factor, resulting in a greater decrease in filter intensity for more severe fluctuations. Through quantitative adjustment, the second sampling frequency and the second filter intensity can change linearly and reasonably according to the degree of motor fluctuation, thereby better adapting to the dynamic changes of the motor and improving the accuracy of power monitoring.

[0020] In a second aspect, this application provides a power monitoring device, which includes: one or more processors and a memory; the memory is coupled to the one or more processors, and the memory is used to store computer program code, the computer program code including computer instructions, and the one or more processors call the computer instructions to cause the power monitoring device to perform the method described in the first aspect and any possible implementation thereof.

[0021] Thirdly, this application provides a computer-readable storage medium including instructions that, when executed on a power monitoring device, cause the power monitoring device to perform the method described in the first aspect and any possible implementation thereof.

[0022] Fourthly, this application provides a computer program product that, when run on a power monitoring device, causes the power monitoring device to perform the method described in the first aspect and any possible implementation thereof.

[0023] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages: 1. By employing a technique that determines the power status based on motor operating parameters (three-phase current change rate and speed change rate), using a low sampling frequency and high filtering intensity in a stable state, and a high sampling frequency and low filtering intensity in an unstable state, and combining this with the three-phase pulse width modulation duty cycle to calculate power, the technical problem of inaccurate power calculation caused by missing key voltage values ​​during motor dynamic processes with a fixed sampling frequency is effectively solved, thereby achieving the technical effect of improving the accuracy of motor power monitoring.

[0024] 2. By adopting a technical approach that, after determining that the motor power is unstable, obtains the overall impact change value by summing the absolute values ​​of the three-phase current change rates, and then compares it with the impact threshold to subdivide the unstable state into ordinary fluctuations and high-current impact states, the technical problem of insufficient monitoring targeting due to the lack of subdivision of the motor's unstable state is effectively alleviated, thereby achieving the technical effect of improving the adaptability and efficiency of the power monitoring method.

[0025] 3. By adopting a technical approach that determines the inflection point of the impact by continuously calculating the overall impact change value sequence under high current impact conditions, and capturing the voltage valley value and corresponding current value after that moment as key sampling data, the technical problem of inaccurate voltage and current acquisition caused by improper sampling timing during violent dynamic processes is effectively solved, thereby achieving the technical effect of improving the accuracy of instantaneous power calculation of motor under high current impact conditions. Attached Figure Description

[0026] Figure 1 This is a flowchart illustrating a motor power monitoring method based on three-phase phase-by-phase data acquisition in an embodiment of this application. Figure 2 This is another flowchart illustrating the motor power monitoring method based on three-phase phase-by-phase data acquisition in this application embodiment; Figure 3 This is a schematic diagram of the hardware structure of a power monitoring device in an embodiment of this application. Detailed Implementation

[0027] The terminology used in the following embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. As used in the specification and appended claims of this application, the singular expressions “a,” “an,” “the,” “the,” “the,” and “this” are intended to include the plural expressions as well, unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used in this application refers to any or all possible combinations including one or more of the listed items.

[0028] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature, and in the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more.

[0029] For ease of understanding, the method provided in this implementation is described in process below. Please refer to [link / reference]. Figure 1 This is a flowchart illustrating a motor power monitoring method based on three-phase phase-by-phase data acquisition in an embodiment of this application.

[0030] 101. Obtain the operating parameters of the motor, including the rate of change of the three-phase current and the rate of change of the motor speed.

[0031] Operating parameters represent various indicators reflecting the current operating status of the motor; the rate of change of three-phase current refers to the amount of change in the magnitude of the three-phase current per unit time, used to characterize the drastic degree of change in motor load; the rate of change of motor speed refers to the amount of change in motor speed per unit time, used to characterize the drastic degree of acceleration and deceleration of the motor.

[0032] Specifically, during motor operation, the power monitoring equipment collects three-phase current values ​​in real time through current sensors and motor speed values ​​in real time through encoders or Hall sensors. Based on the real-time collected three-phase current values ​​and motor speed values, it calculates the three-phase current change rate and speed change rate between two adjacent sampling times. The three-phase current change rate and speed change rate reflect the dynamic characteristics of motor operation.

[0033] 102. Compare the operating parameters with the rate of change threshold to determine whether the motor power is in a stable state.

[0034] The rate of change threshold represents a pre-set reference standard for judging the stable state of motor power; a stable state refers to an operating state in which the motor power fluctuates relatively little.

[0035] Specifically, the power monitoring device compares the obtained three-phase current change rate and speed change rate with the corresponding preset thresholds. When both change rates are less than their respective thresholds, the motor power is determined to be in a stable state; when either change rate exceeds the corresponding threshold, the motor power is determined to be in an unstable state.

[0036] 103. If the motor power is in a stable state, the measured values ​​of the three-phase current and the DC bus voltage of the motor are sampled using the first sampling frequency to obtain the first sampling data, and the first sampling data is filtered using the first filtering strength to obtain the first sampling value.

[0037] The first sampling frequency represents the time interval for sampling motor parameters under steady-state conditions; the measured three-phase current value refers to the actual current value measured by the current sensor; the DC bus voltage value refers to the voltage value on the DC bus in the motor drive system; and the first filter strength represents the filter parameter strength when digitally filtering the sampled data.

[0038] Specifically, when the power monitoring equipment determines that the motor is in a stable state, it uses a relatively low first sampling frequency for data acquisition. The power monitoring equipment acquires the measured values ​​of the three-phase current through three independent current sensors, and simultaneously acquires the DC bus voltage value through a voltage sensor. The acquired measured values ​​of the three-phase current and DC bus voltage may contain various interferences and noises, therefore a stronger first filter intensity is required for filtering to obtain smoother data. Here, the filter intensity can be understood as the smoothness of the signal by the digital filtering algorithm. For example, a higher filter intensity can be achieved by reducing the cutoff frequency of the low-pass filter or increasing the window length of the moving average filter; conversely, a lower filter intensity corresponds to a higher cutoff frequency or a smaller window length.

[0039] 104. If the motor power is not in a stable state, the measured values ​​of the three-phase current and the DC bus voltage of the motor are sampled using the second sampling frequency to obtain the second sampling data. The second sampling data is then filtered using the second filtering strength to obtain the second sampling value. The second sampling frequency is higher than the first sampling frequency, and the second filtering strength is lower than the first filtering strength.

[0040] The second sampling frequency represents the time interval for sampling motor parameters under unstable conditions; the second filter strength represents the filter parameter strength when digitally filtering the sampled data during dynamic processes; the second sampled data refers to the original data acquired using the second sampling frequency; and the second sampled value refers to the data processed by the second filter strength.

[0041] Specifically, when the power monitoring device determines that the motor is in an unstable state, a higher second sampling frequency is used for data acquisition in order to accurately capture the rapid changes in motor parameters. At the same time, to ensure that the sampled data can reflect the true trend of motor parameter changes, the power monitoring device uses a lower second filter intensity for filtering to avoid excessive smoothing that could lead to the loss of important dynamic characteristics.

[0042] The setting of the second sampling frequency and the second filter strength includes steps 1041 to 1046: 1041. The overall impact change value is obtained by summing the rates of change of the three-phase currents.

[0043] The rate of change of three-phase current indicates the speed at which the magnitude of each phase current changes over time; the overall impact change value is a comprehensive index reflecting the overall degree of change of the three-phase current.

[0044] Specifically, the power monitoring equipment sums the absolute values ​​of the rates of change of the three-phase currents to obtain a value that can characterize the overall dynamic characteristics of the motor (i.e., the overall impact change value). The larger this value is, the more severe the electrical impact on the motor.

[0045] In some embodiments, the overall impact change value can be calculated in several ways: Optionally, the power monitoring device can first process the absolute values ​​of the three-phase current change rates, and then add the three absolute values ​​to obtain the overall impact change value, including steps such as calculating the absolute values ​​of the current change rates of each phase, performing addition operations, and outputting the results; Optionally, the power monitoring device can use the root mean square method to obtain the overall impact change value by taking the square root of the sum of the squares of the three-phase current change rates. It is understood that other mathematical methods can also be used to synthesize the change characteristics of the three-phase currents, which are not limited here.

[0046] 1042. Normalize the overall impact change value to obtain the dynamic intensity factor used to represent the severity of motor fluctuations.

[0047] Normalization refers to the mathematical process of mapping the overall impact change value to a specific range; dynamic intensity factor refers to the dimensionless parameter used to characterize the dynamic characteristics of the motor after standardization.

[0048] Specifically, the power monitoring equipment maps the overall impact change value to a range of 0 to 1 through a specific mathematical transformation, and determines the mapped value as a dynamic intensity factor representing the severity of motor fluctuations. This process makes the dynamic characteristics under different operating conditions comparable, which facilitates subsequent parameter adjustments.

[0049] 1043. Calculate the difference between the upper and lower limits of the preset frequency variation range, and calculate the difference between the upper and lower limits of the preset filter intensity variation range.

[0050] The preset frequency variation range indicates the range within which the sampling frequency can be adjusted; the preset filter intensity variation range indicates the range within which the filter intensity can be adjusted; the difference between the upper and lower limits of the frequency and the difference between the upper and lower limits of the filter intensity respectively indicate the adjustable range of these two parameters.

[0051] Specifically, the power monitoring equipment calculates the difference between the maximum and minimum values ​​within the preset frequency variation range to obtain the upper and lower frequency limit differences, and also calculates the difference between the maximum and minimum values ​​within the preset filter intensity variation range to obtain the upper and lower filter intensity limit differences. These frequency and filter intensity limit differences will be used to determine the specific parameter adjustment amounts based on the dynamic intensity factor.

[0052] 1044. Multiply the difference between the upper and lower limits of frequency and the difference between the upper and lower limits of filter intensity by the dynamic intensity factor to obtain the frequency increment and the filter intensity adjustment amount.

[0053] Frequency increment represents the frequency value that needs to be added based on the reference sampling frequency; filter strength adjustment represents the strength value that needs to be adjusted based on the reference filter strength.

[0054] Specifically, the power monitoring equipment multiplies the dynamic intensity factor by the difference between the upper and lower limits of frequency and the difference between the upper and lower limits of filter intensity, respectively, to obtain the actual values ​​that need to be adjusted (i.e., the frequency increment and the filter intensity adjustment amount). This calculation method ensures that the magnitude of the parameter adjustment is proportional to the severity of the motor's dynamic characteristics.

[0055] 1045. Add the frequency increment to the lower limit of the preset frequency change range to obtain the second sampling frequency.

[0056] The lower limit of the preset frequency variation range represents the lowest sampling frequency allowed by the system.

[0057] Specifically, the power monitoring equipment adds the calculated frequency increment to the preset minimum sampling frequency to obtain a sampling frequency suitable for the current dynamic state, i.e., the second sampling frequency. This calculation method ensures that the final sampling frequency will not be lower than the required minimum value, while also being able to adaptively adjust to a suitable level based on the motor's dynamic characteristics.

[0058] 1046. Subtract the filter intensity adjustment amount from the upper limit of the preset filter intensity variation range to obtain the second filter intensity.

[0059] The upper limit of the preset filter intensity variation range represents the maximum filter intensity allowed by the system.

[0060] Specifically, the power monitoring equipment subtracts the calculated filter strength adjustment from the preset maximum filter strength to obtain the filter strength suitable for the current dynamic state, i.e., the second filter strength. This calculation method ensures that the filter strength will be appropriately reduced during dynamic processes, thereby preserving the dynamic characteristics of the signal and avoiding information loss due to excessive smoothing.

[0061] 105. Obtain the three-phase pulse width modulation duty cycle of the motor, and calculate the three-phase instantaneous power of the motor by combining the first or second sampled value.

[0062] The duty cycle of three-phase pulse width modulation refers to the ratio of the energizing time of the three-phase windings of the motor to the switching cycle, which is used to represent the magnitude of the voltage of each phase of the motor; the instantaneous power of three-phase refers to the instantaneous power value of the three-phase windings of the motor at a certain moment.

[0063] Specifically, the power monitoring equipment first acquires the current three-phase PWM duty cycle signals, which reflect the voltage applied to each phase winding of the motor. Then, the power monitoring equipment combines the collected three-phase current sampling values ​​and DC bus voltage sampling values ​​to calculate the instantaneous power of each phase winding of the motor.

[0064] In some embodiments, the calculation of three-phase instantaneous power can be achieved in several ways: Optionally, the power monitoring device can first multiply the three-phase PWM duty cycle by the DC bus voltage to obtain the voltage value of each phase, and then multiply the voltage value of each phase by the corresponding phase current value to obtain the instantaneous power of each phase; Optionally, the power monitoring device can, based on the mathematical model of the motor, consider parameters such as the back electromotive force and stator resistance of the motor, and combine the PWM duty cycle and sampling data to obtain a more accurate instantaneous power value through more complex mathematical calculations. It is understood that other mathematical models or calculation methods can also be used to calculate the three-phase instantaneous power, which is not limited here.

[0065] 106. Sum the instantaneous power of the three phases to obtain the total power of the motor.

[0066] Total motor power represents the total power consumption of the motor at a certain moment.

[0067] Specifically, the power monitoring equipment algebraically sums the instantaneous power of the three-phase windings to obtain the total power value reflecting the overall power consumption of the motor. The total motor power can be used for subsequent motor energy consumption analysis, overload protection, and other control functions.

[0068] The motor power monitoring method based on three-phase phase-by-phase acquisition in this embodiment of the application determines the power stability by comparing the motor's three-phase current change rate, speed change rate, and other operating parameters with corresponding change rate thresholds. Different sampling frequencies and filtering intensities are then applied selectively. In a stable state, a low first sampling frequency and a high first filtering intensity are used to balance accuracy and data processing volume. In an unstable state, a high second sampling frequency is used to capture dynamic signals to avoid missing critical moments of voltage dips, while a low second filtering intensity is used to retain instantaneous change information. Finally, the instantaneous power of the three phases is calculated by combining the three-phase pulse width modulation duty cycle, and the total power is obtained by summing. This method alleviates the technical problem of inaccurate power calculation caused by missing voltage troughs during periods of severe motor dynamics when using a fixed sampling frequency, thus improving the accuracy of motor power monitoring. Following the above, a more detailed description of the method provided in this embodiment is provided below. Please refer to [link to relevant documentation]. Figure 2 This is another flowchart illustrating the motor power monitoring method based on three-phase phase-by-phase acquisition in this application embodiment.

[0069] 201. Obtain the motor's operating parameters, including the rate of change of the three-phase current and the rate of change of the motor speed. (This step has been explained in 101 and will not be repeated here.) 202. Compare the operating parameters with the rate of change threshold to determine whether the motor power is in a stable state.

[0070] The method specifically includes steps 2021 to 2023, which are not shown in the figure.

[0071] 2021. Compare the rate of change of the three-phase current with the first rate of change threshold, and compare the rate of change of the motor speed with the second rate of change threshold.

[0072] The first rate of change threshold refers to the preset current rate of change judgment standard, which is used to judge whether the current change is drastic; the second rate of change threshold refers to the preset speed rate of change judgment standard, which is used to judge whether the speed change is drastic.

[0073] Specifically, the power monitoring device first calculates the change in three-phase current between the current sampling period and the previous sampling period, and divides it by the sampling time interval to obtain the rate of change of the three-phase current. Simultaneously, the power monitoring device calculates the change in motor speed between the current sampling period and the previous sampling period, and divides it by the sampling time interval to obtain the rate of change of motor speed. Then, the power monitoring device compares the calculated rate of change of three-phase current with a pre-set first rate of change threshold, and compares the rate of change of motor speed with a pre-set second rate of change threshold, providing a basis for subsequent judgment of the motor power status.

[0074] 2022. If the rate of change of the three-phase current does not exceed the first rate of change threshold and the rate of change of the motor speed does not exceed the second rate of change threshold, then the motor power is determined to be in a stable state.

[0075] A stable state refers to a working state in which the motor power changes little and the motor runs smoothly, indicating that the motor is not in a violent dynamic process such as rapid acceleration, rapid deceleration or sudden load change.

[0076] Specifically, based on the comparison results of step 2021, when the rate of change of the three-phase current is less than or equal to the first rate of change threshold and the rate of change of the motor speed is less than or equal to the second rate of change threshold, the power monitoring device determines that the motor is currently in a stable operating state.

[0077] In some embodiments, the determination of a stable state can be achieved in several ways: Optionally, a determination duration requirement can be set, i.e., a stable state is only determined when the rate of change has not exceeded a threshold for multiple consecutive sampling periods; Optionally, a hysteresis comparison mechanism can be introduced, i.e., the threshold for entering a stable state and the threshold for exiting a stable state are set differently to avoid frequent switching in critical states; Optionally, other operating parameters of the motor, such as temperature and vibration, can be combined to comprehensively determine the stable state. It is understood that other judgment logic can also be used to determine the stable state, such as fuzzy logic or machine learning methods, which are not limited here.

[0078] 2023. If the rate of change of the three-phase current exceeds the first rate of change threshold, or the rate of change of the motor speed exceeds the second rate of change threshold, then the motor power is determined to be in an unstable state.

[0079] An unstable state refers to a working state in which the motor power changes significantly and the motor is in a dynamic process. This indicates that the motor may be experiencing a violent dynamic process such as rapid acceleration, rapid deceleration, or sudden load changes.

[0080] Specifically, based on the comparison results of step 2021, when the rate of change of the three-phase current is greater than the first rate of change threshold, or the rate of change of the motor speed is greater than the second rate of change threshold, the power monitoring device determines that the motor is currently in an unstable operating state.

[0081] 203. If the motor power is in a stable state, the measured values ​​of the three-phase current and the DC bus voltage of the motor are sampled using the first sampling frequency to obtain the first sampled data. The first sampled data is then filtered using the first filtering strength to obtain the first sampled value. (This step has been explained in 103 and will not be repeated here.) 204. If the motor power is not in a stable state, take the absolute values ​​of the three-phase current change rates and sum them to obtain the overall impact change value. The overall impact change value is used to represent the degree of current impact that the motor experiences due to external commands or load changes.

[0082] The overall impact change value refers to the sum of the absolute values ​​of the three-phase current change rates, used to quantify the overall degree of current impact borne by the motor; external commands represent control commands such as acceleration and deceleration issued by the control system; load changes represent sudden changes in the mechanical load driven by the motor.

[0083] Specifically, the power monitoring equipment first acquires the calculated three-phase current change rates, taking the absolute values ​​of the current change rates for phases A, B, and C respectively to eliminate the influence of the direction of change and focus only on the magnitude of the change. Then, the power monitoring equipment sums the absolute values ​​of the three-phase current change rates to obtain a comprehensive value reflecting the overall change in the three-phase current, i.e., the overall impact change value. The overall impact change value can comprehensively reflect the degree of current impact the motor experiences at the current moment, regardless of whether this impact comes from acceleration / deceleration commands from the control system or from sudden changes in the external load.

[0084] 205. Compare the overall impact change value with the impact threshold to determine the degree of instability of the motor. The degree of instability includes ordinary fluctuation state and high current impact state.

[0085] The impact threshold refers to the preset standard value for judging the degree of impact of motor current; the normal fluctuation state indicates an unstable state with a small change in motor current; the high current impact state indicates an unstable state with a large change in motor current.

[0086] Specifically, the power monitoring device compares the overall impact change value calculated in step 204 with a pre-set impact threshold. Through this comparison, the power monitoring device can further subdivide the degree of motor instability, classifying it into two types: ordinary fluctuation state and high current impact state. This subdivision helps the power monitoring device to adopt corresponding power calculation strategies for different degrees of instability, thereby improving the accuracy of power monitoring.

[0087] 206. If the overall impact change value reaches the impact threshold, the motor is determined to be in a high current impact state.

[0088] A high-current surge indicates that the motor is undergoing a drastic change in current, which may be caused by rapid acceleration, rapid deceleration, or sudden heavy load changes.

[0089] Specifically, based on the comparison results of step 205, when the overall impact change value is greater than or equal to the preset impact threshold, the power monitoring device determines that the motor is currently in a high-current impact state. Under high-current impact conditions, the motor current changes drastically, and the DC bus voltage may fluctuate significantly. Conventional power calculation methods may produce large errors. In this case, the power monitoring device needs to employ a special power calculation method to accurately capture the actual power consumption of the motor during the impact process.

[0090] 207. Continuously calculate the sum of the absolute values ​​of the three-phase current change rates to obtain the overall impact change value sequence.

[0091] The overall impact change value sequence represents a time series composed of the overall impact change values ​​calculated over multiple consecutive sampling periods, used to track the dynamic change process of motor current impact.

[0092] Specifically, the power monitoring device repeats the calculation process of step 204 in each sampling cycle, continuously acquiring the sum of the absolute values ​​of the three-phase current change rates, and storing these values ​​in chronological order to form an overall impact change value sequence. Through the overall impact change value sequence, the power monitoring device can track the entire process of the motor current impact, including its initiation, development, peak value, and attenuation, providing complete dynamic information for subsequent power calculations and motor condition analysis.

[0093] In some embodiments, the processing and utilization of the overall impact change value sequence can be achieved in various ways: Optionally, the overall impact change value sequence can be filtered to reduce noise influence and extract the main changing trend; Optionally, characteristic parameters of the overall impact change value sequence, such as peak value, rise time, and duration, can be analyzed for motor impact characteristic analysis; Optionally, based on the changing trend of the overall impact change value sequence, the development and end time of the impact process can be predicted to optimize the switching timing of the power calculation strategy. It is understood that other data processing methods, such as time-frequency analysis or pattern recognition techniques, can also be used to analyze and utilize the overall impact change value sequence, which is not limited here.

[0094] 208. Based on the overall impact change value sequence, determine the impact inflection point when the overall impact change value changes from increasing to decreasing. The impact inflection point is used to indicate the moment when the intensity of the current impact reaches its peak.

[0095] The impact inflection point refers to the time when the overall impact change value changes from an upward trend to a downward trend, indicating the moment when the motor current change rate reaches its maximum value; the severity of the current impact indicates the intensity of the motor current change.

[0096] Specifically, the power monitoring equipment analyzes the overall impact change value sequence. By comparing the overall impact change values ​​at adjacent moments, it identifies the point in time when the overall impact change value changes from increasing to decreasing. This point in time is defined as the impact inflection point, which marks the point where the motor current change rate reaches its maximum value and the intensity of the current impact reaches its peak. The impact inflection point is a critical turning point for the motor to transition from an accelerated impact state to a stable state, and it is of great significance for accurately capturing the power changes of the motor during the impact process.

[0097] In some embodiments, the determination of the impact inflection point can be achieved in several ways: Optionally, the power monitoring device can determine the impact inflection point by simple differential calculation when the value at a certain moment in the overall impact change value sequence is greater than the previous moment and less than the next moment; Optionally, the power monitoring device can first smooth the overall impact change value sequence to reduce the influence of noise, and then identify the inflection point to improve the accuracy of inflection point identification; Optionally, a curve fitting method can be used to mathematically model the overall impact change value sequence, and the inflection point position can be accurately determined by mathematical methods such as differentiation. It is understood that other mathematical processing methods, such as wavelet analysis or adaptive thresholding techniques, can also be used to determine the impact inflection point, which is not limited here.

[0098] 209. The first DC bus voltage sample value obtained after the impact inflection point and at the second sampling frequency is determined as the valley value of the voltage drop during the high current impact state.

[0099] The DC bus voltage sample value refers to the voltage value collected from the DC bus of the motor drive system; the voltage trough represents the lowest point to which the DC bus voltage drops during a high-current surge. The severe current surge of the motor is mainly powered by the DC bus capacitor. After the peak current consumption, the cumulative voltage drop effect of the capacitor reaches its maximum, resulting in a voltage trough. Therefore, by locating the peak moment of the current change rate (i.e., the inflection point of the surge), the subsequent voltage trough can be effectively predicted and captured. Specifically, the power monitoring equipment focuses on the DC bus voltage change after the inflection point. Because the DC bus capacitor discharges rapidly under high-current surge conditions, the bus voltage experiences a momentary drop. The power monitoring equipment samples the DC bus voltage at a second sampling frequency (usually higher than the conventional sampling frequency) and determines the first DC bus voltage sample value acquired after the inflection point as the voltage trough. This trough reflects the maximum impact of the motor on the power supply system under high-current surge conditions and is a key parameter for calculating the motor power under surge conditions.

[0100] 210. Obtain the measured three-phase current values ​​at the same time as the valley value, and combine them with the valley value to obtain the third sampling data.

[0101] The valley value refers to the lowest voltage drop point determined in step 209; the measured three-phase current value represents the actual current value collected from the three-phase windings of the motor at the moment the valley value occurs; the third sampling data represents a complete sampling dataset containing the valley value and the measured three-phase current value at the corresponding moment.

[0102] Specifically, the power monitoring equipment acquires the measured three-phase current values ​​at the same time as the voltage trough. Since the voltage trough is a critical moment in the motor's high-current surge, the three-phase current values ​​at this time are crucial for accurately calculating the motor's power. The power monitoring equipment combines the voltage trough value with the corresponding measured three-phase current values ​​to form third-phase sampling data. This third-phase sampling data contains the voltage and current information at the most critical moment of the motor's surge, providing an important basis for subsequent power calculations.

[0103] In some embodiments, the acquisition of third-sampled data can be achieved in several ways: Optionally, the power monitoring device can trigger current sampling simultaneously with voltage sampling to ensure the time synchronization of voltage valley values ​​and measured current values; Optionally, the power monitoring device can use interpolation calculation methods to calculate the current value at the precise moment of the valley value based on the current sampling values ​​before and after the valley value; Optionally, the power monitoring device can combine the electrical model of the motor and, based on the known voltage valley value and other parameters, back-calculate the theoretical current value at the valley value and compare it with the measured value for verification. It is understood that other data processing methods can also be used to acquire and organize third-sampled data, such as multi-sensor data fusion or time series analysis, which are not limited here.

[0104] 211. The third sampled data is filtered using the second filtering strength to obtain the third sampled value, and the third sampled value is used as the second sampled value. The third sampled value is used to represent the peak characteristics of the high current impact state.

[0105] Filtering refers to reducing noise and interference in the sampled data through mathematical algorithms; the third sampled value represents the third sampled data after filtering; the second sampled value at the moment of impact inflection point represents the key data used to calculate the motor power at the moment of impact inflection point.

[0106] Specifically, the power monitoring equipment filters the third sampled data to reduce measurement noise and interference. Since the sampled data under high-current impact conditions may contain significant high-frequency interference, the power monitoring equipment uses a second filtering strength (usually different from the filtering strength used under normal conditions) to obtain smoother and more accurate sampled values. The processed third sampled value is determined as the second sampled value at the impact inflection point and used for subsequent calculation of the motor power at that point.

[0107] In some embodiments, the filtering of the third sampled data can be implemented in various ways: Optionally, the power monitoring device can use a low-pass filter to process the third sampled data to remove high-frequency noise components; Optionally, the power monitoring device can use nonlinear filtering methods such as median filtering or mean filtering to suppress outliers; Optionally, the power monitoring device can adaptively adjust the filtering parameters according to the operating state of the motor to minimize the impact of noise while retaining useful signals. It is understood that other filtering algorithms, such as Kalman filtering or wavelet transform, can also be used to process the third sampled data, and are not limited here.

[0108] 212. If the overall impact change value does not reach the impact threshold, the motor is determined to be in a normal fluctuation state.

[0109] The impact threshold refers to the preset standard value for judging the degree of impact of motor current; the normal fluctuation state indicates an unstable state with a small change in motor current, which is an intermediate state between the stable state and the high current impact state.

[0110] Specifically, based on the comparison results, when the overall impact change value is less than the preset impact threshold, the power monitoring equipment determines that the motor is currently in a normal fluctuation state. In this state, although the motor current change exceeds the range of the steady state, it has not yet reached the level of a large current impact, and the fluctuations in the motor's operating parameters are relatively mild. At this time, the motor power calculation needs to adopt a more refined approach than in the steady state but simpler than in the large current impact state, to balance calculation accuracy and system resource consumption.

[0111] 213. The measured values ​​of the three-phase current and the DC bus voltage of the motor are sampled using the second sampling frequency to obtain the second sampling data. The second sampling data is then filtered using the second filtering strength to obtain the second sampling value. The second sampling frequency is higher than the first sampling frequency, and the second filtering strength is lower than the first filtering strength.

[0112] Specifically, the power monitoring equipment switches to a second sampling frequency mode to sample the motor's three-phase current and DC bus voltage at high frequency. This second sampling frequency is higher than the conventionally used first sampling frequency, enabling it to capture the rapid changes in the motor under unstable conditions. After acquiring the raw sampled data, the power monitoring equipment uses a second filtering strength to filter the data. This second filtering strength is lower than the conventionally used first filtering strength, meaning the filter has a weaker smoothing effect on the signal and can retain more dynamic change information. Through this combination of high sampling frequency and low filtering strength, the power monitoring equipment can appropriately suppress noise interference while preserving the signal's dynamic characteristics, obtaining more accurate second sampled values.

[0113] In some embodiments, the power monitoring device can implement high-frequency sampling and weak filtering in various ways: Optionally, the second sampling frequency can be adaptively adjusted according to the dynamic characteristics and electrical parameters of the motor to match the electrical time constant of the motor; Optionally, the power monitoring device can use different second filtering intensities for the three-phase current and DC bus voltage, and optimize the processing according to their respective signal characteristics; Optionally, the power monitoring device can dynamically adjust the second filtering intensity at different stages of the unstable state, for example, using the weakest filtering in the most drastic stage and gradually increasing the filtering in the stage of gradual stabilization. It is understood that other sampling and filtering strategies can also be used to obtain the second sampled value, such as adaptive sampling rate control or hybrid filtering algorithms, which are not limited here.

[0114] 214. Obtain the three-phase pulse width modulation duty cycle of the motor, and calculate the three-phase instantaneous power of the motor by combining the first or second sampled value.

[0115] The method specifically includes steps 2141 to 2143, which are not shown in the figure.

[0116] 2141. Obtain the three-phase pulse width modulation duty cycle of the motor, and calculate the equivalent voltage of the three phases by combining the DC bus voltage value of the first or second sampled value.

[0117] The three-phase pulse width modulation duty cycle represents the ratio of the energizing time of the three-phase windings of the control motor to the switching cycle, and is used to represent the magnitude of the voltage of each phase of the motor; the first sampled value represents the sampled data collected under the steady state of the motor; the second sampled value represents the sampled data collected under the unstable state of the motor; the DC bus voltage value represents the voltage value collected from the DC bus of the motor drive system; the three-phase equivalent voltage represents the equivalent voltage value applied to the three-phase windings of the motor.

[0118] Specifically, the power monitoring equipment first obtains the current three-phase PWM duty cycle signals from the motor control system, namely the duty cycle values ​​of phases A, B, and C. Then, based on the motor's operating state, it selects the DC bus voltage value from either the first sample value (steady state) or the second sample value (unstable state). Finally, the power monitoring equipment calculates the equivalent voltage of the three phases according to the formula: Ua = Da × Udc; Ub = Db × Udc; Uc = Dc × Udc; Where Ua, Ub, and Uc represent the equivalent voltages of phases A, B, and C, respectively; Da, Db, and Dc represent the PWM duty cycles of phases A, B, and C, respectively; and Udc represents the DC bus voltage. These equivalent voltage values ​​reflect the actual voltage applied to each phase winding of the motor and are the basis for calculating motor power.

[0119] 2142. Determine the midpoint voltage of the three-phase voltage by using the average value of the three-phase equivalent voltages.

[0120] The midpoint voltage represents the reference point voltage of a three-phase voltage system and is used to calculate the voltage of each phase to ground.

[0121] Specifically, the power monitoring equipment calculates the average value of the three-phase equivalent voltages and uses it as the midpoint voltage of the three-phase voltages. The calculation is based on the formula: Uo = (Ua + Ub + Uc) ÷ 3 Where Uo represents the neutral point voltage; Ua, Ub, and Uc represent the equivalent voltages of phases A, B, and C, respectively. The neutral point voltage is an important reference value in a three-phase system, reflecting the average level of the three-phase voltages and used for subsequent calculations of the voltage difference between each phase and the neutral point. In a balanced three-phase system, the neutral point voltage provides a virtual neutral point reference, making power calculations more accurate.

[0122] In some embodiments, the neutral point voltage can be calculated in several ways: Optionally, the power monitoring device can directly use the arithmetic mean of the three-phase equivalent voltages as the neutral point voltage, which is suitable for most cases; Optionally, the three-phase imbalance factor can be considered to modify the neutral point voltage calculation formula, which is suitable for cases of severe three-phase imbalance; Optionally, the power monitoring device can combine the star or delta connection characteristics of the motor and adopt different neutral point voltage calculation methods. It is understood that other mathematical methods can also be used to determine the neutral point voltage, such as the neutral point voltage calculation based on space vector theory, which is not limited here.

[0123] 2143. Calculate the difference between the equivalent voltage of the three phases and the midpoint voltage, and combine it with the measured value of the three-phase current of the first or second sampled value to obtain the instantaneous three-phase power of the motor.

[0124] The measured three-phase current represents the actual current value collected from the three-phase windings of the motor; the instantaneous three-phase power represents the instantaneous power value of the three-phase windings of the motor at a certain moment.

[0125] Specifically, the power monitoring equipment first calculates the difference between the three-phase equivalent voltage and the neutral point voltage to obtain the actual voltage of each phase relative to the neutral point. Then, based on the motor's operating state, it selects either the first sampling value (steady state) or the second sampling value (unsteady state) of the measured three-phase current. Finally, the power monitoring equipment multiplies the actual voltage of each phase relative to the neutral point by the corresponding phase current to calculate the three-phase instantaneous power. The calculation is based on the formula: Pa = (Ua - Uo) × Ia; Pb = (Ub - Uo) × Ib; Pc = (Uc - Uo) × Ic; Where Pa, Pb, and Pc represent the instantaneous power of phases A, B, and C, respectively; Ua, Ub, and Uc represent the equivalent voltages of phases A, B, and C, respectively; Uo represents the neutral point voltage; and Ia, Ib, and Ic represent the measured current values ​​of phases A, B, and C, respectively. This calculation method takes into account the mutual influence in the three-phase system and can more accurately reflect the actual power consumption of the motor.

[0126] In some embodiments, the calculation of three-phase instantaneous power can be achieved in several ways: Optionally, the power monitoring device can directly use the above formula to calculate the three-phase instantaneous power, which is applicable to most cases; Optionally, the power monitoring device can consider loss factors such as iron loss and copper loss of the motor to compensate for the power calculation and improve the calculation accuracy; Optionally, the power monitoring device can combine the dynamic model of the motor to consider the energy storage and release process and perform more complex instantaneous power calculations. It is understood that other power calculation methods can also be used, such as power calculation based on dq axis transformation or advanced power analysis considering harmonic components, which are not limited here.

[0127] 215. Sum the instantaneous power of the three phases to obtain the total power of the motor.

[0128] Specifically, the power monitoring equipment algebraically sums the three-phase instantaneous power calculated in step 2143 to obtain the total power value reflecting the power consumption of the entire motor. The calculation is based on the formula: P = Pa + Pb + Pc; Where P represents the total power of the motor; Pa, Pb, and Pc represent the instantaneous power of phases A, B, and C, respectively. This total power value comprehensively reflects the energy consumption of the motor at the current moment and is the final result of motor power monitoring. It can be used for subsequent motor energy consumption analysis, overload protection, efficiency evaluation, and other control functions.

[0129] In some embodiments, the total power of the motor can be calculated and processed in several ways: Optionally, the power monitoring device can directly perform a simple algebraic summation of the three-phase instantaneous power to obtain the total power of the motor, which is applicable to most cases; Optionally, the power monitoring device can consider a power loss correction coefficient during the summation process to compensate for the calculation result and obtain a more accurate total power value; Optionally, the power monitoring device can perform time-domain filtering or averaging on the calculated total power value to reduce the impact of instantaneous fluctuations and obtain a more stable power indication. It is understood that other mathematical processing methods can also be used to calculate the total power of the motor, such as complex power analysis considering active and reactive power components, or power balance calculation based on the principle of energy conservation; these are not limited here.

[0130] The motor power monitoring method based on three-phase phase acquisition in this application embodiment first acquires the motor's three-phase current change rate, speed change rate and other operating parameters, and compares them with the first and second change rate thresholds to accurately determine the power stability. If it is unstable, the overall impact change value is obtained by summing the absolute values ​​of the three-phase current change rates, and compared with the impact threshold to distinguish between two degrees of instability: ordinary fluctuation and large current impact. Under normal fluctuation conditions, the power monitoring device captures dynamic signals using a high second sampling frequency and a low second filter strength. Under high current impact conditions, it continuously tracks the overall impact change value sequence to determine the impact inflection point, captures the first DC bus voltage valley value after the inflection point and the corresponding current value, and filters it. Finally, it calculates the three-phase equivalent voltage by combining the three-phase pulse width modulation duty cycle, determines the midpoint voltage by the average value of the equivalent voltage, and then calculates the three-phase instantaneous power by combining the difference between the equivalent voltage and the midpoint voltage with the measured current value and sums them to obtain the total power. This achieves motor power monitoring under different operating conditions, alleviating the problem of inaccurate power calculation caused by improper sampling timing and single state judgment during drastic dynamic processes due to fixed sampling. Furthermore, by subdividing the degree of instability and targeted data processing, it avoids resource waste while ensuring monitoring accuracy, thus balancing the accuracy and efficiency of power monitoring. The method provided in the above embodiments can be executed by the power monitoring device. The following describes the power monitoring device in the embodiments of this invention from the perspective of hardware processing. Please refer to [link to relevant documentation]. Figure 3 This is a schematic diagram of the physical structure of a power monitoring device in an embodiment of this application.

[0131] It should be noted that, Figure 3 The structure of the power monitoring device shown is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of the present invention.

[0132] like Figure 3 As shown, the power monitoring device includes a Central Processing Unit (CPU) 301, which can perform various appropriate actions and processes based on a program stored in Read-Only Memory (ROM) 302 or a program loaded from storage section 308 into Random Access Memory (RAM) 303, such as performing the methods described in the above embodiments. The RAM 303 also stores various programs and data required for system operation. The CPU 301, ROM 302, and RAM 303 are interconnected via a bus 304. An Input / Output (I / O) interface 305 is also connected to the bus 304.

[0133] The following components are connected to I / O interface 305: input section 306 including audio input devices, push-button switches, etc.; output section 307 including a liquid crystal display (LCD) and audio output devices, indicator lights, etc.; storage section 308 including a hard disk, etc.; and communication section 309 including a network interface card such as a LAN (Local Area Network) card, modem, etc. Communication section 309 performs communication processing via a network such as the Internet. Drive 310 is also connected to I / O interface 305 as needed. Removable media 311, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., are installed on drive 310 as needed so that computer programs read from them can be installed into storage section 308 as needed.

[0134] In particular, according to embodiments of the present invention, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of the present invention include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing computer programs for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via communication section 309, and / or installed from removable medium 311. When the computer program is executed by central processing unit (CPU) 301, it performs the various functions defined in the present invention.

[0135] It should be noted that specific examples of computer-readable storage media may include, but are not limited to: electrical connections having one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), flash memory, optical fiber, portable compact disc read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this invention, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0136] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. Each block in a flowchart or block diagram may represent a module, program segment, or portion of code, which contains one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those shown in the drawings.

[0137] Specifically, the power monitoring device in this embodiment includes a processor and a memory. The memory stores a computer program, and when the computer program is executed by the processor, it implements the power monitoring device provided in the above embodiment.

[0138] In another aspect, the present invention also provides a computer-readable storage medium, which may be included in the power monitoring device described in the above embodiments; or it may exist independently and not assembled into the power monitoring device. The storage medium carries one or more computer programs that, when executed by a processor of the power monitoring device, cause the power monitoring device to implement the power monitoring device provided in the above embodiments.

[0139] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0140] As used in the above embodiments, depending on the context, the term "when..." can be interpreted as meaning "if...", "after...", "in response to determining...", or "in response to detecting...". Similarly, depending on the context, the phrase "when determining..." or "if (the stated condition or event) is interpreted as meaning "if determining...", "in response to determining...", "when (the stated condition or event) is detected", or "in response to detecting (the stated condition or event)".

[0141] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid-state drive), etc.

[0142] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. This program can be stored in a computer-readable storage medium, and when executed, it can include the processes described in the above method embodiments. The aforementioned storage medium includes various media capable of storing program code, such as ROM or random access memory (RAM), magnetic disks, or optical disks.

Claims

1. A method for monitoring motor power based on three-phase phase-by-phase data acquisition, characterized in that, The method, applied to a power monitoring device installed inside a motor, includes: Obtain the operating parameters of the motor, including the rate of change of the three-phase current and the rate of change of the motor speed; The operating parameters are compared with the rate of change threshold to determine whether the motor power is in a stable state. If the motor power is in a stable state, the measured values ​​of the three-phase current and the DC bus voltage of the motor are sampled using the first sampling frequency to obtain the first sampling data, and the first sampling data is filtered using the first filtering strength to obtain the first sampling value. If the motor power is not in a stable state, the measured value of the three-phase current and the DC bus voltage value of the motor are sampled using the second sampling frequency to obtain the second sampling data, and the second sampling data is filtered using the second filtering strength to obtain the second sampling value. The second sampling frequency is higher than the first sampling frequency, and the second filtering strength is lower than the first filtering strength. The three-phase pulse width modulation duty cycle of the motor is obtained, and the three-phase instantaneous power of the motor is calculated by combining the first sample value or the second sample value. The total power of the motor is obtained by summing the instantaneous power of the three phases.

2. The method according to claim 1, characterized in that, The operating parameters are compared with a rate of change threshold to determine whether the motor power is in a stable state, specifically including: The rate of change of the three-phase current is compared with a first rate of change threshold, and the rate of change of the motor speed is compared with a second rate of change threshold; If the rate of change of the three-phase current does not exceed the first rate of change threshold and the rate of change of the motor speed does not exceed the second rate of change threshold, then the motor power is determined to be in a stable state. If the rate of change of the three-phase current exceeds the first rate of change threshold, or the rate of change of the motor speed exceeds the second rate of change threshold, then the motor power is determined to be in an unstable state.

3. The method according to claim 1, characterized in that, After determining that the motor power is not in a stable state, the method further includes: The absolute values ​​of the change rates of the three phase currents are taken and summed to obtain the overall impact change value, which is used to represent the degree of current impact that the motor experiences due to external commands or load changes. The overall impact change value is compared with the impact threshold to determine the degree of instability of the motor. The degree of instability includes normal fluctuation state and high current impact state. If the overall impact change value reaches the impact threshold, then the motor is determined to be in a high current impact state. If the overall impact change value does not reach the impact threshold, then the motor is determined to be in a normal fluctuation state.

4. The method according to claim 3, characterized in that, After determining that the motor is in a high-current surge state, the method further includes: The sum of the absolute values ​​of the three-phase current change rates is continuously calculated to obtain the overall impact change value sequence; Based on the overall impact change value sequence, the impact inflection point moment when the overall impact change value changes from increasing to decreasing is determined. The impact inflection point moment is used to indicate the moment when the intensity of the current impact reaches its peak. The first DC bus voltage sample value obtained after the impact inflection point and at the second sampling frequency is determined as the valley value of the voltage drop during the high current impact state. Obtain the measured three-phase current values ​​at the same time as the valley value, and combine them with the valley value to obtain the third sampling data; The third sampled data is filtered using the second filtering intensity to obtain the third sampled value, and the third sampled value is used as the second sampled value. The third sampled value is used to represent the peak characteristics of the high current impact state.

5. The method according to claim 1, characterized in that, Obtain the three-phase pulse width modulation duty cycle of the motor, and calculate the three-phase instantaneous power of the motor by combining the first sampled value or the second sampled value, specifically including: Obtain the three-phase pulse width modulation duty cycle of the motor, and calculate the equivalent voltage of the three phases by combining the DC bus voltage value of the first sampled value or the second sampled value. The midpoint voltage of the three-phase voltage is determined by the average value of the equivalent voltages of the three phases. The difference between the equivalent voltage of the three phases and the midpoint voltage is calculated, and the measured value of the three-phase current is combined with the first sample value or the second sample value to obtain the instantaneous three-phase power of the motor.

6. The method according to claim 1, characterized in that, The settings for the second sampling frequency and the second filter strength specifically include: The overall impact change value is obtained by summing the rates of change of the three-phase currents; The overall impact change value is normalized to obtain a dynamic intensity factor that represents the severity of the motor fluctuation. The dynamic intensity factor is adjusted within a preset frequency variation range and a preset filter intensity variation range. The dynamic intensity factor is positively correlated with the second sampling frequency and negatively correlated with the second filter intensity.

7. The method according to claim 6, characterized in that, Based on the dynamic intensity factor, adjustments are made within a preset frequency variation range and a preset filter intensity variation range, specifically including: Calculate the difference between the upper and lower limits of the preset frequency variation range, and calculate the difference between the upper and lower limits of the preset filter intensity variation range; Multiply the frequency upper and lower limit difference, the filter intensity upper and lower limit difference, and the dynamic intensity factor respectively to obtain the frequency increment and the filter intensity adjustment amount; The second sampling frequency is obtained by adding the frequency increment to the lower limit of the preset frequency change range; The second filter intensity is obtained by subtracting the filter intensity adjustment amount from the upper limit of the preset filter intensity variation range.

8. A power monitoring device, characterized in that, The power monitoring device includes: one or more processors and a memory; the memory is coupled to the one or more processors, the memory is used to store computer program code, the computer program code including computer instructions, and the one or more processors call the computer instructions to cause the power monitoring device to perform the method as described in any one of claims 1-7.

9. A computer-readable storage medium comprising instructions, characterized in that, When the instruction is executed on the power monitoring device, the power monitoring device performs the method as described in any one of claims 1-7.

10. A computer program product, characterized in that, When the computer program product is run on the power monitoring device, it causes the power monitoring device to perform the method as described in any one of claims 1-7.

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