A method and system for managing the operation of a three-phase asynchronous motor

Abstract

The present application relates to motor control technology field, disclose a kind of three-phase asynchronous motor operation control management method and system, comprising the following steps: step 1, the number of encoder per revolution pulse, motor nameplate rated speed, acceleration time, coasting stop time, hot permission threshold, load shedding threshold, tripping threshold, start-stop token upper limit and expected spin direction are determined Maximum allowable acceleration time and minimum cooling lock time;Step 2, according to three-phase existence state, under-voltage state and time condition are judged to start admission;Step 3, execute pulse accumulation and spin direction comparison to generate start determination result, and deduct start-stop token number;Step 4, during operation, based on temperature detection calculation heat index, compared with each threshold, output continue to run, load shedding or shutdown instruction;Step 5, update heat index, when meeting unlocking condition, output unlocking result.The present application realizes the whole process safety management of three-phase asynchronous motor from start determination, operation regulation to shutdown unlocking.

Description

Technical Field

[0001] This invention belongs to the field of motor control technology, specifically relating to a method and system for controlling and managing the operation of a three-phase asynchronous motor. Background Technology

[0002] Three-phase asynchronous motors are widely used in industrial automated production lines, mechanical transmission equipment, and energy transmission systems due to their simple structure, reliable operation, convenient maintenance, and low manufacturing cost. As the level of automation in industrial production continues to increase, the frequency of motor starts and stops and the operating modes under complex load conditions are increasing, placing higher demands on the safety and refined management of motor control systems.

[0003] Existing motor control systems generally employ fixed thresholds or single temperature monitoring for start-stop control, failing to comprehensively reflect the motor's heat accumulation characteristics, acceleration process, and cooling behavior during dynamic operation. Under conditions of frequent start-stop cycles, high loads, or poor heat dissipation, this control method can easily lead to excessively rapid motor temperature rise, resulting in winding insulation aging, efficiency reduction, or even burnout, making it difficult to meet the requirements for long-term stable operation. Furthermore, existing three-phase motor start-up control technologies mostly rely on phase sequence detection or voltage detection methods, which have low accuracy in determining power supply stability and cooling recovery time. When the motor is in a state of undervoltage, phase loss, or insufficient cooling, it may still be misjudged as startable, leading to overload operation or protection failure. Summary of the Invention

[0004] This invention provides a three-phase asynchronous motor operation control and management method and system, which solves the technical problems in related technologies where motor start-stop control relies on a single parameter, cannot take into account dynamic changes in thermal state, and causes overheating, false start-up, and system impact due to multi-machine operation scheduling.

[0005] This invention provides a method for controlling and managing the operation of a three-phase asynchronous motor, comprising the following steps:

[0006] Step 1: Obtain the number of encoder pulses per revolution of the motor, the rated speed on the motor nameplate, the acceleration time, the coasting stop time, the thermal allowance threshold, the load reduction threshold, the trip threshold, the start / stop token upper limit and the desired rotation direction, and determine the maximum allowable acceleration time and the minimum cooling lock-in time.

[0007] Step 2: Based on the three-phase state, undervoltage state, maximum allowable acceleration time and minimum cooling lock-up time, make an admission judgment and output the start admission result, which includes allowing start and prohibiting start;

[0008] Step 3: With the start-up permitted, close the main contactor and start timing and pulse accumulation. Determine the minimum cumulative pulse count for acceleration based on the number of pulses per encoder revolution, the rated speed on the motor nameplate, and the maximum allowable acceleration time. Within the acceleration window, generate the start-up judgment result by comparing the pulse accumulation with the minimum cumulative pulse count for acceleration and comparing the actual rotation direction with the expected rotation direction. After closing the circuit breaker, deduct the number of start / stop tokens.

[0009] Step 4: During operation, calculate the current heat index based on temperature monitoring, compare the current heat index with the heat permit threshold, load reduction threshold and trip threshold respectively, and output control commands to continue operation, reduce load or stop the machine.

[0010] Step 5: Record the motor fault event and disconnect the power. During the shutdown, keep track of the time and update the current thermal index. Output the unlocking result when the unlocking conditions are met.

[0011] Furthermore, the maximum allowable acceleration time is obtained by multiplying the measured acceleration time by a preset margin coefficient, and the minimum cooling lock-up time is obtained by adding the measured coasting stop time to a preset cooling compensation time constant.

[0012] Furthermore, the three-phase existence state includes effective and invalid, and the undervoltage state includes normal and abnormal;

[0013] When the three-phase state is valid, the undervoltage state is normal, the actual cooling time is not less than the minimum cooling lock-in time, and the cumulative running time does not exceed the maximum allowable acceleration time, an enable start signal is output; otherwise, an disable start signal is output.

[0014] Furthermore, the minimum cumulative number of pulses required to accelerate achievement of the target is determined, including:

[0015] Step 11: Set the cumulative pulse value to 0, and during the acceleration process, use the pulse signal output by the encoder as the input source. Perform a counting accumulation once for each complete pulse cycle detected to obtain the real-time cumulative pulse count.

[0016] Step 12: Calculate the product of the motor nameplate rated speed, the number of encoder pulses per revolution, and the maximum allowable acceleration time, and divide the product by sixty to obtain the minimum cumulative number of pulses required to achieve acceleration.

[0017] Step 13: Monitor the cumulative pulse count within the time window of the maximum allowable acceleration time. When the real-time cumulative pulse count is greater than or equal to the minimum cumulative pulse count for acceleration and the cumulative time does not exceed the maximum allowable acceleration time, the acceleration is determined to be successful and an acceleration success signal is output. When the cumulative time reaches the maximum allowable acceleration time and the real-time cumulative pulse count is less than the minimum cumulative pulse count for acceleration, the acceleration is determined to be unsuccessful and a power-off shutdown command is output.

[0018] Furthermore, the generation of the judgment result includes:

[0019] Step 21: Read the real-time cumulative pulse count within the acceleration time window under the allowed start-up condition, and compare it with the minimum cumulative pulse count for acceleration to reach the target, and generate an acceleration determination signal; at the same time, determine the actual rotation direction according to the order of the two encoder signals, and compare it with the expected rotation direction to generate a rotation direction determination signal.

[0020] Step 22: The logic and result of the speed-up determination signal and the rotation direction determination signal are used as the start-up voting criteria. When both the speed-up determination signal and the rotation direction determination signal are valid, the start-up success result is output. When either determination signal is invalid, a power-off shutdown command is output, and the corresponding blocking reason is recorded according to the preset fault code rules.

[0021] Step 23: When the main contactor is closed, perform a deterministic deduction on the number of start / stop tokens, update the number of start / stop tokens to the current number of start / stop tokens minus one, and limit the number of start / stop tokens to zero when the updated number of start / stop tokens is less than zero.

[0022] Furthermore, step 4 specifically includes:

[0023] Step 31: Periodically collect motor temperature data and perform moving average processing to obtain the average temperature. Calculate the temperature rise rate by the ratio of the change in average temperature within adjacent sampling periods to the sampling interval. Obtain the temperature deviation based on the preset reference temperature. Obtain the current thermal index by weighted combination of the temperature deviation and the temperature rise rate.

[0024] Step 32: When the current heat index is less than or equal to the heat permit threshold, it is determined to be in the continuous operation state; when the current heat index is greater than the heat permit threshold and less than or equal to the load reduction threshold, it is determined to be in the load reduction warning state; when the current heat index is greater than the load reduction threshold and less than or equal to the trip threshold, it is determined to be in the load reduction operation state; when the current heat index is greater than the trip threshold, it is determined to be in the shutdown protection state.

[0025] Step 33: Output the corresponding control command based on the determined state.

[0026] Furthermore, the value ranges of the heat permit threshold and the load reduction threshold are adjusted based on a Bayesian optimization method, including:

[0027] Step 41: After each operation control cycle, obtain the motor's operating temperature, current thermal index, threshold trigger time, ambient temperature, and operating load rate. Calculate the reciprocal of the square of the difference between the motor's operating temperature at the load reduction trigger and the thermal allowable threshold to obtain the thermal safety margin. Calculate the output power reduction rate per unit time after the load reduction trigger as the energy efficiency loss. Weight the normalized value of the thermal safety margin and the normalized value of the energy efficiency loss to obtain the threshold performance index function.

[0028] Step 42: Using the combination of the thermal permit threshold and the load reduction threshold as optimization parameters, and the threshold performance index function as the objective function, establish a Gaussian process model, calculate the predicted mean and predicted covariance of each threshold combination, and form the predicted distribution of the objective function.

[0029] Step 43: Construct the desired improved acquisition function based on the distribution predicted by the objective function, calculate the acquisition value with the predicted mean and predicted covariance as input, and determine a new threshold combination by maximizing the acquisition value;

[0030] Step 44: Set a safety constraint range for the new threshold combination. When the increment of the objective function value after multiple consecutive optimizations is less than the preset increment threshold, the threshold combination is rolled back to the threshold combination with the largest objective function value in the most recent time.

[0031] Furthermore, step 5 specifically includes:

[0032] Step 51: After the motor stops, record the current time as the start of the stop and calculate the cumulative stop cooling time. When the cumulative cooling time reaches the minimum cooling lock time, output a cooling completion flag.

[0033] Step 52: During the shutdown cooling process, calculate the ratio of the cumulative cooling time to the cooling time constant, multiply it by the attenuation coefficient and take the opposite number, and then perform exponential calculation to obtain the cooling attenuation index. Multiply the cooling attenuation index by the thermal index of the previous operating control cycle to obtain the updated thermal index.

[0034] Step 53: When the updated thermal index is less than or equal to the thermal allowance threshold and the cumulative downtime cooling time is greater than or equal to the minimum cooling lock time, output the unlock result signal to allow the motor to re-enter the start-up determination process.

[0035] Furthermore, when multiple motors coexist, they are sorted based on the updated thermal index, number of start / stop tokens, and cumulative running time; within each operating control cycle, only the motor ranked first is given a start permission command to start, while other motors are prohibited from starting.

[0036] This invention provides a three-phase asynchronous motor operation control and management system, comprising:

[0037] The parameter acquisition module is used to acquire the number of encoder pulses per revolution of the motor, the rated speed on the motor nameplate, the acceleration time, the coasting and stopping time, the thermal allowance threshold, the load reduction threshold, the tripping threshold, the start / stop token upper limit and the desired rotation direction, and to determine the maximum allowable acceleration time and the minimum cooling lock-in time.

[0038] The startup admission judgment module is used to make admission judgments based on the three-phase status, undervoltage status, maximum allowable acceleration time and minimum cooling lock-up time, and output the startup admission result, which includes startup allowed and startup prohibited.

[0039] The start execution and voting module is used to close the main contactor and start timing and pulse accumulation when start is allowed. It determines the minimum cumulative pulse count for acceleration based on the number of pulses per encoder revolution, the rated speed on the motor nameplate, and the maximum allowable acceleration time. Within the acceleration window, it generates a start judgment result based on the comparison between the pulse accumulation and the minimum cumulative pulse count for acceleration, as well as the comparison between the actual rotation direction and the expected rotation direction. After closing the circuit, the number of start / stop tokens is deducted.

[0040] The operation control module is used to calculate the current heat index based on temperature monitoring during operation, compare the current heat index with the heat permit threshold, load reduction threshold and trip threshold respectively, and output control commands to continue operation, reduce load or stop the machine.

[0041] The shutdown cooling and unlocking module is used to record motor fault events and cut off power. During shutdown, it keeps track of time and updates the current thermal index. When the unlocking conditions are met, it outputs the unlocking result.

[0042] The beneficial effects of this invention are as follows: By comprehensively managing the motor encoder signal, power supply status, temperature parameters, and start / stop tokens, this invention achieves dynamic judgment and precise control of the entire start-stop process of a three-phase asynchronous motor. By introducing an access judgment mechanism, it avoids false starts under conditions of undervoltage, phase loss, or insufficient cooling. During the start-up process, dual verification through pulse accumulation and rotation direction comparison ensures the safety and consistency of the acceleration process and rotation direction. During the operation phase, a thermal index model is used to continuously evaluate the motor's temperature rise status, and multi-level threshold hierarchical control enables intelligent switching between continuous operation, load reduction, and shutdown. During shutdown, a cooling attenuation model is introduced to dynamically update the thermal status and automatically determine the unlocking timing, preventing heat accumulation caused by frequent start-stops. Overall, this invention effectively improves the motor's operational safety and thermal management accuracy, reduces equipment failure rate, extends motor lifespan, and achieves orderly scheduling and load balancing in scenarios with multiple motors operating in parallel, improving the overall system operating efficiency and reliability. Attached Figure Description

[0043] Figure 1 This is a flowchart of a three-phase asynchronous motor operation control and management method according to the present invention. Detailed Implementation

[0044] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the examples. Furthermore, features described in some examples may be combined in other examples.

[0045] like Figure 1 As shown, a method for controlling and managing the operation of a three-phase asynchronous motor includes the following steps:

[0046] Step 1: Obtain the number of encoder pulses per revolution of the motor, the rated speed on the motor nameplate, the acceleration time, the coasting stop time, the thermal allowance threshold, the load reduction threshold, the trip threshold, the start / stop token upper limit and the desired rotation direction, and determine the maximum allowable acceleration time and the minimum cooling lock-in time.

[0047] Step 2: Based on the three-phase state, undervoltage state, maximum allowable acceleration time and minimum cooling lock-up time, make an admission judgment and output the start admission result, which includes allowing start and prohibiting start;

[0048] Step 3: With the start-up permitted, close the main contactor and start timing and pulse accumulation. Determine the minimum cumulative pulse count for acceleration based on the number of pulses per encoder revolution, the rated speed on the motor nameplate, and the maximum allowable acceleration time. Within the acceleration window, generate the start-up judgment result by comparing the pulse accumulation with the minimum cumulative pulse count for acceleration and comparing the actual rotation direction with the expected rotation direction. After closing the circuit breaker, deduct the number of start / stop tokens.

[0049] Step 4: During operation, calculate the current heat index based on temperature monitoring, compare the current heat index with the heat permit threshold, load reduction threshold and trip threshold respectively, and output control commands to continue operation, reduce load or stop the machine.

[0050] Step 5: Record the motor fault event and disconnect the power. During the shutdown, keep track of the time and update the current thermal index. Output the unlocking result when the unlocking conditions are met.

[0051] In one embodiment of the present invention, the number of pulses per encoder revolution refers to the total number of pulses output by the encoder when the motor rotates one revolution, which is used to characterize the encoder resolution, and the unit is pulses / revolution; the rated speed on the motor nameplate is the rated operating speed marked by the manufacturer on the motor nameplate, and the unit is revolutions per minute; the acceleration time refers to the time required for the motor to start from a standstill and reach the rated speed, and the unit is seconds; the coasting stop time refers to the time it takes for the motor to coast by inertia until the speed drops to zero after the power is cut off, which is used to characterize the mechanical inertia and residual heat release rate of the system.

[0052] The maximum permissible acceleration time is obtained by multiplying the measured acceleration time by a preset margin coefficient, and the minimum cooling lock-in time is obtained by adding the measured coasting stop time to a preset cooling compensation time constant. The maximum permissible acceleration time is the longest allowed acceleration duration from a standstill to stable operation, used to limit the acceleration phase of the motor to be completed within a reasonable time to prevent overheating of the windings or overload of the power supply system due to prolonged high-current operation. The preset margin coefficient is a correction factor determined empirically based on the motor power rating and load inertia, used to introduce a safety margin in acceleration control, with a value ranging from 1.1 to 1.3. This correction ensures that the motor acceleration process under different load conditions does not exceed the thermal safety limit. The minimum cooling lock-in time limits the shortest interval between motor restarts after shutdown, thereby ensuring that the temperature of the motor windings and core recovers to a safe level and preventing heat accumulation caused by premature repeated starts. The preset cooling compensation time constant is a constant determined based on the motor structure, heat dissipation method and ambient temperature. It is used to compensate for the delay in the natural cooling stage and has a value range of 30 to 120 seconds. This constant can more accurately reflect the thermal decay characteristics of the motor and effectively constrain the thermal balance process.

[0053] In one embodiment of the present invention, to ensure that the motor starts under safe operating conditions, a comprehensive access judgment is made on the motor's power supply status and cooling status. This judgment process generates a start-up access result by detecting the presence of three-phase power supply, the undervoltage status of the bus voltage, the actual cooling time, and the cumulative running time, thereby achieving safe management of the motor's start-up behavior.

[0054] The three-phase presence status reflects whether the three-phase power supply to the motor power supply circuit is properly connected, including whether it is valid or invalid. When the amplitude and phase sequence of the three-phase power supply meet the preset standards, the three-phase presence status is determined to be valid. When any phase is missing, the phase sequence is incorrect, or the voltage is severely unbalanced, the three-phase presence status is determined to be invalid. The undervoltage status indicates whether the motor bus voltage is within the rated operating range, including whether it is normal or abnormal. When the detected voltage is within 90% to 110% of the rated voltage, the undervoltage status is determined to be normal. When the detected voltage is lower than 90% of the rated voltage or higher than 110% of the rated voltage, the undervoltage status is determined to be abnormal.

[0055] The actual cooling time is the cumulative cooling duration from the time the motor stops to the current moment; the cumulative running time is the continuous energization time of the motor in the current running control cycle; when the three-phase status is valid, the undervoltage status is normal, the actual cooling time is not less than the minimum cooling lock-in time and the cumulative running time does not exceed the maximum allowable acceleration time, an allow start signal is output and the motor enters the start process; otherwise, an prohibit start signal is output and the motor remains de-energized.

[0056] Through the above process, this invention not only constrains the power supply quality during the motor startup phase, but also comprehensively verifies the motor's own thermal recovery state and running time, thereby improving the safety and reliability of motor startup and ensuring that the motor starts and runs in a safe electrical and thermal environment.

[0057] In one embodiment of the present invention, determining the minimum cumulative number of pulses required to achieve the acceleration target includes:

[0058] Step 11: Set the cumulative pulse value to 0, and during acceleration, use the pulse signal output by the encoder as the input source. Perform a count accumulation once for each complete pulse cycle detected to obtain the real-time cumulative pulse count. The cumulative pulse count is the accumulated value of the pulse count during the acceleration phase, representing the total rotation angle of the motor from startup to the current moment. In this way, real-time angular displacement information of the motor rotor can be obtained during the acceleration phase, and its acceleration trend can be calculated.

[0059] Step 12: Calculate the product of the motor's rated speed (as indicated on the nameplate), the number of encoder pulses per revolution, and the maximum allowable acceleration time. Divide this product by sixty to obtain the minimum cumulative pulse count required for acceleration. The formula for calculating the minimum cumulative pulse count is as follows: , This indicates the minimum cumulative number of pulses required to accelerate the achievement of the target. Indicates the rated speed on the motor nameplate. This indicates the number of pulses per encoder revolution. This indicates the maximum permissible acceleration time in seconds. 60 is a unit conversion constant used to convert the rated speed on the motor nameplate from revolutions per minute to revolutions per second to ensure that the time units in the calculation results are consistent.

[0060] Step 13: Monitor the cumulative pulse count within the time window of the maximum allowable acceleration time. When the real-time cumulative pulse count is greater than or equal to the minimum cumulative pulse count for acceleration and the cumulative time does not exceed the maximum allowable acceleration time, the acceleration is determined to be successful and an acceleration success signal is output. When the cumulative time reaches the maximum allowable acceleration time and the real-time cumulative pulse count is less than the minimum cumulative pulse count for acceleration, the acceleration is determined to be unsuccessful and a power-off shutdown command is output.

[0061] Through the above process, the acceleration target determination method of this embodiment can improve the safety and reliability of the motor starting process and provide accurate dynamic basic data for subsequent operation status control.

[0062] In one embodiment of the present invention, the generation of the activation determination result includes:

[0063] Step 21: Within the acceleration time window allowed for startup, read the real-time cumulative pulse count and compare it with the minimum cumulative pulse count for acceleration. When the real-time cumulative pulse count is greater than or equal to the minimum cumulative pulse count for acceleration, generate a speed-up judgment signal, indicating that the motor has reached the expected speed-up requirement within the specified time. Simultaneously, determine the actual rotation direction based on the sequence of the two encoder signals and compare it with the desired rotation direction to generate a rotation direction judgment signal. Specifically, the two encoder output signals are typically two-phase signals, A and B, with a 90° electrical angle difference. When the A-phase signal leads the B-phase signal, the motor rotates in the forward direction; when the A-phase signal lags the B-phase signal, the motor rotates in the reverse direction. The system determines the actual rotation direction based on the sequence of the two signals and compares it with the system-set desired rotation direction to generate a rotation direction judgment signal. If the actual rotation direction matches the desired rotation direction, the rotation direction judgment signal is valid; otherwise, it is invalid.

[0064] Step 22: The logic and result of the speed-up determination signal and the rotation direction determination signal are used as the start-up voting criteria. When both the speed-up determination signal and the rotation direction determination signal are valid, a start-up success result is output, indicating that the motor has successfully accelerated and run in the correct rotation direction within the specified time. When either determination signal is invalid, a power-off shutdown command is output to prevent abnormal situations such as motor reversal, stalling, or insufficient speed-up. The corresponding blocking reason is recorded according to the preset fault code rules. Fault codes include, but are not limited to: acceleration not meeting the standard, incorrect rotation direction, overload shutdown, etc.

[0065] Step 23: When the main contactor is closed, in order to prevent the accumulation of thermal stress and system impact caused by frequent start-stop, the number of start-stop tokens is deducted once and the number of start-stop tokens is updated to the current number of start-stop tokens minus one. When the updated number of start-stop tokens is less than zero, the number of start-stop tokens is limited to zero. The number of start-stop tokens is an integer variable used to limit the number of times the motor can start within a certain period of time.

[0066] Through the above process, this embodiment achieves dual safety verification during the motor startup phase. The acceleration status and rotation direction are simultaneously detected within the acceleration time window; a successful startup result is output only when both judgment signals are valid. If either is abnormal, the power is immediately cut off, the machine is stopped, and the cause of the fault is recorded. By introducing start / stop token management, the number of motor starts is limited, effectively preventing heat accumulation and mechanical shock caused by frequent starts and stops, thereby improving the safety of the motor startup process and the overall stability of the operating system.

[0067] In one embodiment of the present invention, when the cumulative number of pulses in multiple consecutive operating control cycles is lower than a preset steady-state threshold, it is determined that the motor has a low-speed fault and a power-off shutdown command is output. The low-speed fault is usually caused by overload, undervoltage, mechanical jamming or partial winding fault, which will cause the motor to be unable to maintain normal speed and increase the risk of overheating. The preset steady-state threshold represents the minimum cumulative number of pulses that the motor should reach when running stably under rated load conditions.

[0068] In one embodiment of the present invention, during operation, the current thermal index is calculated based on temperature detection, and the current thermal index is compared with the thermal allowable threshold, the load reduction threshold, and the trip threshold, respectively, and control commands for continuing operation, load reduction, or shutdown are output, including:

[0069] Step 31: Periodically collect motor temperature data and perform moving average processing to obtain the average temperature. Calculate the temperature rise rate by the ratio of the change in average temperature within adjacent sampling periods to the sampling interval. Obtain the temperature deviation based on the preset reference temperature. Obtain the current thermal index by weighted combination of the temperature deviation and the temperature rise rate.

[0070] Step 32: When the current thermal index is less than or equal to the thermal permissible threshold, the system is determined to continue operating; when the current thermal index is greater than the thermal permissible threshold and less than or equal to the load reduction threshold, the system is determined to be in a load reduction warning state; when the current thermal index is greater than the load reduction threshold and less than or equal to the trip threshold, the system is determined to be in a load reduction operating state, and the control system reduces the output power or speed to alleviate the thermal load; when the current thermal index is greater than the trip threshold, the system is determined to be in a shutdown protection state, and the system immediately outputs a power-off shutdown command to execute forced protection. Specifically, the thermal permissible threshold is used to define the safe temperature rise range of the motor, the load reduction threshold is used to indicate that the motor is in an overheating trend state, and the trip threshold is used to indicate that the motor temperature has approached or reached the insulation safety limit.

[0071] Step 33: Output the corresponding control command according to the determined state to realize closed-loop thermal management control of the motor operating state.

[0072] Through the above process, this embodiment can reflect the trend of motor temperature change in real time, realize dynamic early warning and graded response to thermal risks, and improve the accuracy of thermal management and operational safety.

[0073] In one embodiment of the present invention, the value ranges of the heat permit threshold and the load reduction threshold are adjusted based on a Bayesian optimization method, including:

[0074] Step 41: After each operation control cycle, acquire the motor's operating temperature, thermal index, threshold trigger time, ambient temperature, and operating load rate. Calculate the reciprocal of the square of the difference between the motor's operating temperature at the load reduction trigger and the thermal allowable threshold to obtain the thermal safety margin. Calculate the output power reduction rate per unit time after the load reduction trigger as the energy efficiency loss. Weight the normalized value of the thermal safety margin and the normalized value of the energy efficiency loss to obtain the threshold performance index function. The calculation formula for the threshold performance index function is as follows:

[0075] ;

[0076] F represents the value of the threshold performance index function, which is used to measure the overall performance of the current threshold combination in balancing thermal safety and energy efficiency. The larger the value, the better the threshold setting. This indicates the operating temperature at which load shearing is triggered. Indicates the thermal permission threshold. and These represent the minimum and maximum values ​​of the thermal safety margin in each operating control cycle, respectively. Indicates thermal safety margin, This represents the average output power before load reduction. This indicates the average output power after load reduction. Indicates the sampling time interval. and These represent the minimum and maximum energy efficiency losses in each operating control cycle, respectively. Indicates energy efficiency loss. and These represent the first weighting coefficient and the second weighting coefficient, respectively.

[0077] Step 42: Using the combination of the heat permit threshold and the load reduction threshold as optimization parameters, and the threshold performance index function as the objective function, a Gaussian process model is established to calculate the predicted mean and predicted covariance of each threshold combination, thus forming the predicted distribution of the objective function. The Gaussian process model is a non-parametric probabilistic model that predicts the distribution characteristics of the objective function under new parameters through training samples. Through Gaussian process inference, the system can simultaneously obtain the predicted mean and predicted covariance of each threshold combination, thereby forming the predicted distribution of the threshold performance index function.

[0078] Step 43: Construct the desired improved acquisition function based on the distribution predicted by the objective function, calculate the acquisition value with the predicted mean and predicted covariance as input, and determine a new threshold combination by maximizing the acquisition value;

[0079] Step 44: Set a safety constraint range for the new threshold combination. When the increment of the objective function value after multiple consecutive optimizations is less than the preset increment threshold, the threshold combination will be rolled back to the threshold combination with the largest objective function value in the most recent time. The safety constraint range is determined based on the insulation class of the motor, the maximum allowable temperature rise and the design margin coefficient to ensure that the threshold value is always within the thermal safety operating range.

[0080] Through the above process, this embodiment achieves adaptive dynamic updating of motor thermal protection parameters. This method combines Gaussian process modeling with an expected improvement strategy, enabling iterative optimization of the threshold without requiring large-sample training, thus balancing thermal safety and operational efficiency. By introducing a safety constraint interval and a backoff mechanism, the system achieves threshold self-convergence control while ensuring insulation safety, thereby significantly improving the intelligence and stability of the motor thermal management system.

[0081] In one embodiment of the present invention, step 5 specifically includes:

[0082] Step 51: After the motor stops, record the current time as the start of the stop and calculate the cumulative stop cooling time. When the cumulative cooling time reaches the minimum cooling lock time, output a cooling completion flag.

[0083] Step 52: During the shutdown cooling process, calculate the ratio of the cumulative cooling time to the cooling time constant, multiply it by the attenuation coefficient and take the opposite value, then perform exponential calculation to obtain the cooling attenuation index. Multiply the cooling attenuation index by the thermal index of the previous operating control cycle to obtain the updated thermal index; wherein, the updated formula for the thermal index is: , This represents the cooling attenuation coefficient, ranging from 0 to 1, and indicates the proportion of heat energy attenuated over time. This indicates the heat index of the previous operating control cycle. This represents the attenuation coefficient, used to correct for cooling rates under different heat dissipation conditions, with a value ranging from 0.8 to 1.2. Indicates the total downtime and cooling time. This represents the cooling time constant, with a value ranging from 500 seconds to 700 seconds.

[0084] Step 53: When the updated thermal index is less than or equal to the thermal permissible threshold and the cumulative downtime cooling time is greater than or equal to the minimum cooling lock time, output an unlock result signal to allow the motor to re-enter the start-up judgment process; otherwise, continue to maintain the locked state until the thermal index drops to a safe range.

[0085] Through the above process, this embodiment can adaptively calculate the thermal decay rate under different ambient temperatures and heat dissipation conditions, ensuring the accuracy of unlocking condition judgment and improving the availability of the motor and the operating efficiency of the system.

[0086] In one embodiment of the present invention, when multiple motors coexist, they are sorted based on the updated thermal index, the number of start / stop tokens, and the cumulative running time. Within each operating control cycle, only the motor with the highest priority in the ranking is given a start permission command, while other motors are prohibited from starting. Specifically, the ranking priority of each motor is obtained by weighted summing of the reciprocal of the updated thermal index, the number of start / stop tokens, and the cumulative running time. Only the motor with the highest priority is given a start permission command, while the remaining motors receive a prohibition signal and enter a standby state until re-evaluation in the next operating control cycle. This mechanism ensures that only one motor is in the start permission state within each operating control cycle, effectively preventing current surges or power fluctuations caused by simultaneous startup of multiple motors, and guaranteeing the stability and safety of the system under high load conditions.

[0087] The present invention also provides a three-phase asynchronous motor operation control and management system, comprising:

[0088] The parameter acquisition module is used to acquire the number of encoder pulses per revolution of the motor, the rated speed on the motor nameplate, the acceleration time, the coasting and stopping time, the thermal allowance threshold, the load reduction threshold, the tripping threshold, the start / stop token upper limit and the desired rotation direction, and to determine the maximum allowable acceleration time and the minimum cooling lock-in time.

[0089] The startup admission judgment module is used to make admission judgments based on the three-phase status, undervoltage status, maximum allowable acceleration time and minimum cooling lock-up time, and output the startup admission result, which includes startup allowed and startup prohibited.

[0090] The start execution and voting module is used to close the main contactor and start timing and pulse accumulation when start is allowed. It determines the minimum cumulative pulse count for acceleration based on the number of pulses per encoder revolution, the rated speed on the motor nameplate, and the maximum allowable acceleration time. Within the acceleration window, it generates a start judgment result based on the comparison between the pulse accumulation and the minimum cumulative pulse count for acceleration, as well as the comparison between the actual rotation direction and the expected rotation direction. After closing the circuit, the number of start / stop tokens is deducted.

[0091] The operation control module is used to calculate the current heat index based on temperature monitoring during operation, compare the current heat index with the heat permit threshold, load reduction threshold and trip threshold respectively, and output control commands to continue operation, reduce load or stop the machine.

[0092] The shutdown cooling and unlocking module is used to record motor fault events and cut off power. During shutdown, it keeps track of time and updates the current thermal index. When the unlocking conditions are met, it outputs the unlocking result.

[0093] It should be noted that the interval and threshold sizes are set for ease of comparison. The size of the threshold depends on the amount of sample data and the base number set by those skilled in the art for each set of sample data, as long as it does not affect the proportional relationship between the parameter and the quantized value. Furthermore, the above formulas are all dimensionless calculations, and the formulas are derived from software simulations using a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0094] The embodiments of the present invention have been described above, but the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms based on the guidance of the present embodiments, all of which are within the protection scope of the present embodiments.

Claims

1. A method of managing the operation of a three-phase asynchronous motor, characterized in that, The method comprises the following steps: Step 1, obtaining the number of encoder pulses per revolution of the motor, the rated speed of the motor nameplate, the acceleration time, the coasting stop time, the thermal permission threshold, the load reduction threshold, the tripping threshold, the upper limit of the start-stop token and the expected rotation direction, and determining the maximum allowed acceleration time and the minimum cooling locking time; Step 2, judging the access according to the three-phase existence state, the under-voltage state, the maximum allowed acceleration time and the minimum cooling locking time, and outputting a start access result, wherein the start access result comprises allowing starting and prohibiting starting; Step 3, closing the main contactor under the condition of allowing starting and starting timing and pulse accumulation, determining the minimum cumulative pulse number of acceleration reaching the standard according to the number of encoder pulses per revolution, the rated speed of the motor nameplate and the maximum allowed acceleration time, comparing the pulse accumulation and the minimum cumulative pulse number of acceleration reaching the standard within the acceleration window, generating a start determination result according to the comparison and the comparison between the actual rotation direction and the expected rotation direction, and deducting the start-stop token number after closing; wherein generating the start determination result comprises: Step 21, reading the real-time cumulative pulse number within the acceleration time window under the condition of allowing starting, comparing the real-time cumulative pulse number with the minimum cumulative pulse number of acceleration reaching the standard, generating a speed-up determination signal, and comparing the actual rotation direction determined according to the sequence of the two encoder signals with the expected rotation direction to generate a rotation direction determination signal; Step 22, taking the logical AND result of the speed-up determination signal and the rotation direction determination signal as the start voting criterion, outputting a start success result when the speed-up determination signal and the rotation direction determination signal are both valid, outputting a power-off shutdown instruction when any determination signal is invalid, and recording the corresponding blocking reason according to the preset fault code rule; Step 23, performing a deterministic deduction on the start-stop token number when the main contactor is closed, updating the start-stop token number to the current start-stop token number minus one, and limiting the start-stop token number to zero when the updated start-stop token number is less than zero; Step 4, calculating the current thermal index based on temperature monitoring during operation, comparing the current thermal index with the thermal permission threshold, the load reduction threshold and the tripping threshold respectively, and outputting a control instruction of continuing operation, load reduction or shutdown; Step 5, recording the fault events of the motor and powering off, timing and updating the current thermal index during shutdown, and outputting an unlocking result when the unlocking condition is met, comprising: Step 51, recording the current time as the shutdown starting point and calculating the cumulative shutdown cooling time after the motor is shutdown, and outputting a cooling completion flag when the cumulative cooling time reaches the minimum cooling locking time; Step 52, calculating the ratio of the cumulative cooling time to the cooling time constant during the shutdown cooling process, multiplying the ratio by the decay coefficient and taking the opposite number, and then performing exponential operation to obtain a cooling decay index, and multiplying the cooling decay index by the thermal index of the previous operation control period to obtain an updated thermal index; Step 53, outputting an unlocking result signal when the updated thermal index is less than or equal to the thermal permission threshold and the cumulative shutdown cooling time is greater than or equal to the minimum cooling locking time, allowing the motor to re-enter the start determination process.

2. A method of operating control management of a three-phase asynchronous motor according to claim 1, characterized in that, The maximum allowed acceleration time is obtained by multiplying the measured acceleration time by a preset margin coefficient, and the minimum cooling locking time is obtained by adding the measured coasting stop time to a preset cooling compensation time constant.

3. A method of operating control management of a three-phase asynchronous motor according to claim 1, characterized in that, The three-phase presence state includes valid and invalid, and the under-voltage state includes normal and abnormal; When the three-phase presence state is valid, the under-voltage state is normal, the actual cooling time is not less than the minimum cooling locking time, and the cumulative running time is not more than the maximum allowed acceleration time, an allowed start signal is output, otherwise a prohibited start signal is output.

4. A method of operating control management of a three-phase asynchronous motor according to claim 1, characterized in that, The minimum cumulative pulse number for acceleration compliance is determined, including: Step 11, setting the cumulative pulse value to 0, and taking the pulse signal output by the encoder as the input source during the acceleration process, performing counting and accumulation once for each complete pulse period detected to obtain the real-time cumulative pulse number; Step 12, calculating the product of the motor nameplate rated speed, the number of pulses per revolution of the encoder and the maximum allowed acceleration time, and dividing the product by sixty to obtain the minimum cumulative pulse number for acceleration compliance; Step 13, monitoring the cumulative pulse number within the time window of the maximum allowed acceleration time, when the real-time cumulative pulse number is greater than or equal to the minimum cumulative pulse number for acceleration compliance and the cumulative time does not exceed the maximum allowed acceleration time, it is determined that the acceleration is up to standard and an acceleration success signal is output; when the cumulative time reaches the maximum allowed acceleration time and the real-time cumulative pulse number is less than the minimum cumulative pulse number for acceleration compliance, it is determined that the acceleration is not up to standard and a power-off shutdown instruction is output.

5. A method of operating control management of a three-phase asynchronous motor according to claim 1, characterized in that, The step 4 specifically includes: Step 31, periodically collecting motor temperature data and performing sliding average processing to obtain average temperature, calculating the temperature rise change rate through the ratio of the change amount of the average temperature in adjacent sampling periods to the sampling interval, obtaining the temperature deviation according to the preset reference temperature, and obtaining the current thermal index through the weighted combination of the temperature deviation and the temperature rise change rate; Step 32, when the current thermal index is less than or equal to the thermal permission threshold, it is determined to be a continuous running state; when the current thermal index is greater than the thermal permission threshold and less than or equal to the load shedding threshold, it is determined to be a load shedding early warning state; when the current thermal index is greater than the load shedding threshold and less than or equal to the tripping threshold, it is determined to be a load shedding running state; when the current thermal index is greater than the tripping threshold, it is determined to be a shutdown protection state; Step 33, outputting the corresponding control instruction according to the determined state.

6. A method of operating control management of a three-phase asynchronous motor according to claim 5, characterized in that, The value range of the thermal permission threshold and the load shedding threshold is adjusted based on the Bayesian optimization method, including: Step 41, at the end of each running control period, obtaining the running temperature of the motor, the current thermal index, the threshold triggering time, the ambient temperature and the running load rate, calculating the reciprocal of the square of the difference between the running temperature of the motor at the load shedding triggering time and the thermal permission threshold to obtain the thermal safety margin, calculating the output power decline rate per unit time after the load shedding triggering as the energy efficiency loss, and weighting the normalized value of the thermal safety margin and the normalized value of the energy efficiency loss to combine to obtain the threshold performance index function; Step 42, taking the threshold combination of the thermal permission threshold and the load shedding threshold as the optimization parameter, and taking the threshold performance index function as the objective function, a Gaussian process model is established, the prediction mean and prediction covariance of each threshold combination are calculated to form the prediction distribution of the objective function; Step 43, constructing an expected improvement acquisition function based on the target function prediction distribution to predict the mean and the prediction covariance as inputs to calculate the acquisition value, and determining a new threshold combination by maximizing the acquisition value; Step 44, setting a safety constraint interval for the new threshold combination, and when the increment of the target function value after continuous optimization is less than a preset increment threshold, the threshold combination is rolled back to the threshold combination with the maximum target function value in the last time.

7. A method of operating control management of a three-phase asynchronous motor according to claim 1, characterized in that, When multiple motors coexist, the updated thermal index, the number of start-stop tokens, and the cumulative running time are used for sorting; in each running control cycle, only the first motor in the sorting is output with a start permission instruction allowing startup, and other motors are prohibited from starting.

8. A three-phase asynchronous motor operation control management system, characterized by, The method comprises the following steps: The parameter acquisition module is configured to acquire the number of encoder pulses per revolution, the motor nameplate rated speed, the acceleration time, the coasting stop time, the thermal permission threshold, the load reduction threshold, the trip threshold, the start-stop token upper limit, and the desired rotation direction of the motor, and determine the maximum allowed acceleration time and the minimum cooling lock time. The start admission determination module is configured to determine admission according to the three-phase presence state, the under-voltage state, the maximum allowed acceleration time, and the minimum cooling lock time, and output a start admission result, wherein the start admission result includes permission to start and prohibition to start. The start execution and voting module is configured to close the main contactor and start timing and pulse accumulation when permission to start is given, determine the minimum acceleration compliance cumulative pulse number according to the number of encoder pulses per revolution, the motor nameplate rated speed, and the maximum allowed acceleration time, generate a start determination result according to the comparison of pulse accumulation and the minimum acceleration compliance cumulative pulse number and the comparison of actual rotation direction and desired rotation direction within the acceleration window, and deduct the number of start-stop tokens after closing. The running control module is configured to calculate the current thermal index based on temperature monitoring during running, compare the current thermal index with the thermal permission threshold, the load reduction threshold, and the trip threshold, and output a control instruction for continuous running, load reduction, or shutdown. The shutdown cooling and unlocking module is configured to record the motor fault event and disconnect the power supply, time and update the current thermal index during shutdown, and output an unlocking result when the unlocking condition is met.

Images