Multi-motor stalling early warning method and system

Abstract

The invention relates to the technical field of engineering machinery, in particular to a multi-motor stalling early warning method and system. The method is realized based on a control unit of each motor, the motors are arranged on a suspension wire at intervals, and the method comprises the following steps: obtaining actual working current and preset working current of the motor where the control unit is located; wherein the preset working current is the working current which is predicted to flow through when the motor runs on the suspension wire; and judging whether the ratio of the actual working current to the preset working current is within a first normal ratio range or not, and if not, carrying out locked-rotor early warning and error detection processes. The system comprises a plurality of motors, and each motor is provided with a control unit and a detection unit. The detection unit is used for detecting various working parameters of the motor where the detection unit is located and sending the working parameters to the control unit of the motor, and the control unit is used for conducting locked-rotor early warning on the motor based on the method. According to the method and the system, locked-rotor early warning under a multi-motor scene is realized, the locked-rotor early warning accuracy is higher, and the applicability is higher.

Description

Technical Field

[0001] The embodiments of this specification relate to the technical field of engineering machinery, and in particular to a multi-motor stall warning method and system. Background Art

[0002] In the hanging line system for continuously conveying items, several motors spaced apart on the line are usually used to fix and drive the line. With the diversification of transportation needs, the layout of the line is becoming more and more complex, and the stability requirements for the hanging line are becoming higher and higher. Since the line has multiple turns, uphill and downhill, uneven load weight and other situations during transportation, the motors at individual positions on the line are prone to stalling during long-term use, and cannot meet the driving requirements of the position. The motor itself is also prone to damage due to stalling, affecting the normal production and transportation process. Therefore, timely detection of motor stalling and timely alarm processing are of great significance to ensure the stability of the hanging line system.

[0003] Motor stalling refers to the phenomenon that the motor cannot continue to rotate normally during operation due to excessive load, mechanical failure, bearing damage, etc. At this time, the motor speed is 0, and the motor needs to generate a large torque to overcome this static state. Therefore, a large current will be generated inside the motor, which will generate excess heat and damage the motor. Existing motor stall detection and early warning methods mainly compare the motor's operating parameters with the standard operating parameters, and determine whether the motor is stalled based on the comparison results; or determine whether the motor is stalled by determining whether the motor's operating parameters match its speed; the standard operating parameters and the expected values ​​of the matching process are relatively fixed and cannot be adaptively adjusted according to different application scenarios. The accuracy and flexibility of motor stall early warning are low. Summary of the invention

[0004] The embodiments of this specification provide a multi-motor stall warning method and system, aiming to solve one or more of the above-mentioned problems and other potential problems.

[0005] In order to achieve the above objectives, the following technical solutions are provided: According to a first aspect of the present specification, a multi-motor stall warning method is provided, the method is implemented based on the control unit of each motor, and each motor is arranged on a suspension line at intervals, including: Obtaining the actual working current and the preset working current of the motor where the control unit is located; wherein the preset working current is the working current expected to flow through the motor when it runs on the suspension wire; It is determined whether the ratio of the working current to the preset current is within a first normal ratio range; if not, a stall warning and error detection process is performed.

[0006] In the multi-motor stall warning method and system of the embodiments of this specification, both the actual working current and the preset working current are acquired and calculated in real time, are not easily affected by differences in motor application scenarios, and the stall judgment is more accurate; the stall judgment is performed based on the ratio of the actual working current to the preset working current, that is, the power efficiency of the motor reflects the true output efficiency of the motor, and the judgment standard is easier to determine, further increasing the accuracy of the stall judgment; at the same time, multiple motors perform their own stall judgment and control processes respectively, which is not prone to misjudgment and control failures, thereby ensuring the stability of the entire system.

[0007] In some embodiments, obtaining a preset working current of a motor where the control unit is located includes: Obtain the stress condition of the suspension wire and the basic performance of the motor when the motor where the control unit is located is arranged on the suspension wire; The preset working current is obtained by calculation based on the stress condition of the suspension wire and the basic performance of the motor.

[0008] In some embodiments, the step of obtaining the stress condition of the suspension line and the basic performance of the motor when the motor where the control unit is located is arranged on the suspension line includes: obtaining the tension applied to the suspension line when the motor where the control unit is located is arranged on the suspension line, the linear speed of the suspension line, and the basic current, basic voltage, gear radius, and motor reduction box speed ratio of the motor; The step of calculating and obtaining the preset working current based on the stress condition of the suspension wire and the basic performance of the motor includes: Calculating the torque value output by the motor based on the pulling force and the gear radius; and calculating the basic power of the motor based on the basic current and basic voltage; Calculating a preset output power of the motor based on the torque value, the motor reduction box speed ratio, the motor base power, the linear speed and the gear radius; The preset operating current is calculated based on the preset output power and the basic voltage.

[0009] In some embodiments, the error detection process includes: obtaining the power supply voltage of the motor where the control unit is located, determining whether the power supply voltage is within a voltage threshold range, and if not, reducing the power supply voltage of the motor through a voltage regulator until the ratio of the actual working current of the motor to the preset working current is within a first normal ratio range.

[0010] In some embodiments, it also includes: when it is determined that the time for the motor to perform a stall warning is greater than a preset stall threshold, controlling the motor to cut off power.

[0011] In some embodiments, the error detection process includes: obtaining a vibration spectrum of the motor, and issuing a motor fault warning when it is determined that the vibration spectrum is inconsistent with a standard motor vibration spectrum.

[0012] In some embodiments, after a motor issues a stall warning, it sends a stall signal to an adjacent motor of the motor. Based on the stall signal, the adjacent motor adjusts a first normal ratio range preset in its control unit to a second normal ratio range, where the second normal ratio range is larger than the first normal ratio range. The adjacent motor makes a stall judgment based on the adjusted first normal ratio range.

[0013] According to the second aspect of the present specification, a multi-motor stall warning system is provided, comprising a plurality of motors, each of which is provided with a control unit and a detection unit; the detection unit is used to detect various working parameters of the motor in which it is located, and send the working parameters to the control unit of the motor, and the control unit is used to perform a stall warning on the motor based on the above-mentioned multi-motor stall warning method.

[0014] In some embodiments, one of the motors is used as a master motor, and the master motor establishes communication connections with other motors respectively. The master motor is used to determine whether the number of motors for stall warning exceeds a threshold value, and if so, controls all the motors to be powered off synchronously.

[0015] In some embodiments, the detection unit includes a tension sensor, a line speed sensor, a vibration sensor, and a temperature sensor.

[0016] In some embodiments, a voltage regulator connected to the control unit is provided between the motor and the power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] By reading the following detailed description with reference to the accompanying drawings, the above and other objects, features and advantages of the embodiments of the present specification will become readily understood. In the accompanying drawings, several embodiments of the present specification are shown by way of example and not limitation.

[0018] Figure 1 A flow chart of a multi-motor stall warning method according to an embodiment of this specification is shown.

[0019] In the various drawings, the same or corresponding reference numerals represent the same or corresponding parts. DETAILED DESCRIPTION

[0020] The preferred embodiments of the present specification will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present specification are shown in the accompanying drawings, it should be understood that the present specification can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present specification more thorough and complete, and to fully convey the scope of the present specification to those skilled in the art.

[0021] The term "including" and its variations used in this document represent open inclusion, that is, "including but not limited to". Unless otherwise stated, the term "or" means "and / or". The term "based on" means "based at least in part on". The terms "an example embodiment" and "an embodiment" mean "at least one example embodiment". The term "another embodiment" means "at least one other embodiment". Terms such as "upper", "lower", "front", and "rear" indicating placement or positional relationships are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the principles of this specification, and do not indicate or imply that the referred elements must have a specific orientation, be constructed or operate in a specific orientation, and therefore should not be understood as limitations on this specification.

[0022] When the motor is running normally, the rotating magnetic field formed by the motor stator winding drags the rotor to rotate, and the magnetic field generated by the induced current in the rotor also induces a back electromotive force in the stator winding, which plays a role in preventing the increase of the current in the motor stator winding. When the motor is stalled, the rotor stops rotating, the friction and resistance of the internal mechanical parts increase, and the motor needs a larger current to try to overcome these resistances. At this time, the back electromotive force generated by the rotor disappears, and the current in the motor stator winding cannot be prevented from increasing, so that the stall current may reach 5-12 times the rated current, which not only increases the motor loss, but also causes the motor to overheat and damage and deform. There are many factors that cause the motor to stall. Factors such as abnormal power supply voltage of the motor, failure of the internal structure of the motor, excessive load, and failure of the control system may all cause the motor to stall. It is necessary to timely and efficiently warn the motor of the stall situation according to the specific application scenario. The following is a detailed description of a multi-motor stall warning method in accordance with the embodiments of this specification in conjunction with the accompanying drawings.

[0023] Figure 1 A flowchart of a multi-motor stall warning method according to an embodiment of the present specification is shown. The multi-motor stall warning method according to the embodiment of the present specification is implemented based on the control unit of each motor, and each motor is arranged on the suspension wire at intervals. The method includes the following steps: S102, obtaining the actual working current and the preset working current of the motor where the control unit is located; wherein the preset working current is the working current expected to flow through the motor when it runs on the suspension wire; S104, determining whether the ratio of the working current to the preset current is within a first normal ratio range, and if not, performing a stall warning and error detection process.

[0024] In step S102, obtaining the real-time preset current of the motor where the control unit is located includes the following steps: Step 1021, obtaining the stress condition of the suspension wire and the basic performance of the motor when the motor where the control unit is located is arranged on the suspension wire; Step 1023, obtaining the preset working current by calculation based on the stress condition of the suspension wire and the basic performance of the motor.

[0025] In some embodiments, step 1021 includes: obtaining the tension applied to the suspension line by the motor where the control unit is located when the motor is arranged on the suspension line, the linear speed of the suspension line, and the basic current, basic voltage, gear radius and motor reducer speed ratio of the motor.

[0026] In some embodiments, step 1023 includes: Calculating the torque value output by the motor based on the pulling force and the gear radius, and calculating the basic power of the motor based on the basic current and basic voltage; The preset output power of the motor is calculated based on the torque value, the speed ratio of the motor reduction box, the basic power of the motor, the linear speed and the gear radius, and the preset current is calculated based on the preset output power and the basic voltage.

[0027] Specifically, the torque value = the pulling force * the gear radius, and the motor basic power = the basic current * the basic voltage. For example, when the pulling force applied by the motor to the suspension line is 332.5N, and the gear radius at the output end of the motor is 0.072m, the motor should output a torque of about 24N·m to the suspension line. In step S15, the angular velocity is first calculated based on the linear velocity and the gear radius, and the angular velocity = the linear velocity / the gear radius; the preset output power = the torque value * the motor reducer speed ratio * the angular velocity + the motor basic power; the preset current = the preset output power / the basic voltage. For example, the linear velocity is 0.225m / s, the gear radius at the output end of the motor is 0.072m, and the angular velocity is calculated to be 3.125rad / s. The basic voltage is generally 220V. Table 1 shows the preset currents of the motors in various suspension line scenarios.

[0028] Table 1: Preset current values ​​of the motor in various hanging wire scenarios The actual working current and the preset working current in the embodiments of this specification are both acquired and calculated in real time, which can flexibly adapt to different application scenarios, are not easily affected by external environmental factors, and the judgment of whether the motor is blocked is more accurate and not easy to misjudge. At the same time, in step S104, the ratio of the actual working current and the preset working current is used to judge whether the motor is blocked. The preset working current is calculated based on the preset output power that the motor should output. The actual working current is the actual output current detected. When the ratio of the actual working current and the preset working current is lower than a certain threshold, that is, the power efficiency of the motor is lower than a certain threshold, it means that the motor is blocked. Specifically, the first normal ratio range can be 70%-100%. When the power efficiency is lower than 70%, a blocking warning can be performed. This method using the motor power efficiency as the judgment standard is easier to determine the judgment standard than the difference judgment, has higher judgment accuracy, and can more accurately reflect the real output efficiency of the motor.

[0029] After the stall warning is issued, in order to facilitate the staff to carry out targeted maintenance on the stalled motor, an error detection process is also performed in step S104. When the motor is used in the suspension line transportation system, there are many motors sharing the load. When the motor is reasonably arranged, the stall caused by load problems is rare. Therefore, the two factors of abnormal power supply voltage and motor structure failure are mainly detected.

[0030] Specifically, the error detection process for power supply voltage abnormality includes: Obtain the power supply voltage of the motor where the control unit is located, and determine whether the power supply voltage is within the voltage threshold range. If not, reduce the power supply voltage of the motor through a voltage regulator until the ratio of the actual working current of the motor to the preset working current is within the first normal ratio range. Among them, the voltage regulator is a device for adjusting the input voltage of the motor to ensure that the motor can work normally under different voltage conditions and improve the operating efficiency and stability of the motor. The voltage regulator adjusts the supply voltage to achieve automatic recovery of the motor in the stalled state. Furthermore, after adjusting the supply voltage for a period of time, the ratio of the actual working current to the preset working current has not returned to the first normal ratio range, and the motor is still stalled. At this time, the motor should be promptly controlled to be powered off. Specifically, when it is determined that the time for the motor to perform a stall warning is greater than the preset stall threshold, the motor is controlled to be powered off.

[0031] The error detection process for motor structural faults includes: obtaining the vibration spectrum of the motor, and issuing a motor fault warning when it is determined that the vibration spectrum is inconsistent with the standard motor vibration spectrum. Specifically, a vibration sensor is used to detect the vibration of the motor, and the vibration spectrum is analyzed to determine whether the motor has problems such as imbalance and bearing damage. In addition, a temperature sensor can be used to monitor the temperature distribution of the motor, and temperature anomaly analysis can be used to determine whether the motor has problems such as overheating and cooling system failure.

[0032] When a motor is stalled due to structural failure or other problems and a stall warning is issued, the power will be automatically cut off. At this time, the fixed driving function of the motor on the suspension line is mainly shared by its adjacent motors. When the adjacent motors judge whether they are stalled, the actual working current or the preset working current may suddenly change, resulting in the ratio of the two not being within the first normal ratio range, resulting in a misjudgment of the motor stall. Therefore, after the stall warning is issued in step S104, a stall signal is sent to the adjacent motors of the motor. Based on the stall signal, the adjacent motors adjust the first normal ratio range preset in their control units to the second normal ratio range. The second normal ratio range is larger than the first normal ratio range, and the adjacent motors make stall judgments based on the adjusted first normal ratio range.

[0033] The embodiment of this specification also discloses a multi-motor stall warning system, the system includes several motors, each of which is provided with a control unit and a detection unit. The detection unit is used to detect the various working parameters of the motor in which it is located, and send the working parameters to the control unit of the motor, and the control unit is used for the above-mentioned multi-motor stall warning method to perform stall warning on the motor. The multiple motors in the embodiment of this specification each judge their own stall situation. Compared with the unified collection of the working parameters of each motor for unified judgment and control, the stall warning process is more flexible and simple, and is not easy to affect other motors, avoiding misjudgment caused by redundant data, and the motor control efficiency is not easily affected by the instability of the signal transmission process. Specifically, the detection unit includes a tension sensor, a linear speed sensor, a vibration sensor and a temperature sensor, respectively, for the various working parameters of each motor; a voltage regulator connected to the control unit is provided between the motor and the power supply, and the motor power supply voltage is adjusted in time to avoid stall caused by abnormal motor power supply voltage.

[0034] In addition, in a multi-motor application scenario such as a hanging wire transportation system, when a small number of motors are blocked, other motors can share the work of the blocked motors. However, when a certain number of motors are blocked, the operation of the entire motor system needs to be suspended to avoid interference with normal motors. Therefore, one of the motors is used as the main control motor, and the main control motor establishes communication connections with other motors respectively. The main control motor is used to determine whether the number of motors for blocking warning exceeds the number threshold. When it exceeds the threshold, all the motors are controlled to be powered off synchronously. At the same time, a main control motor controls the remaining motors to be powered off synchronously to prevent pulling of the line during the power-off process. Among them, the main control motor gives priority to motors that are not in the blocking warning state to avoid abnormal power-off signals.

[0035] Although several specific implementation details are included in the above discussion, these should not be interpreted as limiting the scope of this specification. Certain features described in the context of separate embodiments may also be implemented in a single implementation in combination. Conversely, various features described in the context of a single implementation may also be implemented in multiple implementations individually or in any suitable sub-combination.

[0036] Although the subject matter has been described in language specific to structural features and / or methodological logical actions, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. On the contrary, the specific features and actions described above are merely example forms of implementing the claims.

[0037] The embodiments of the present specification have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A multi-motor stall warning method, the method is implemented based on the control unit of each motor, and each motor is arranged on a suspension line at intervals, characterized in that: include: Obtaining the actual working current and the preset working current of the motor where the control unit is located; wherein the preset working current is the working current expected to flow through the motor when it runs on the suspension wire; It is determined whether the ratio of the working current to the preset current is within a first normal ratio range; if not, a stall warning and error detection process is performed.

2. The method according to claim 1, characterized in that Obtaining the preset working current of the motor where the control unit is located includes: Obtain the stress condition of the suspension wire and the basic performance of the motor when the motor where the control unit is located is arranged on the suspension wire; The preset working current is obtained by calculation based on the stress condition of the suspension wire and the basic performance of the motor.

3. The method according to claim 2, characterized in that The obtaining of the stress condition of the suspension line and the basic performance of the motor when the motor where the control unit is located is arranged on the suspension line includes: obtaining the tension applied to the suspension line when the motor where the control unit is located is arranged on the suspension line, the linear speed of the suspension line, and the basic current, basic voltage, gear radius and motor reduction box speed ratio of the motor; The step of calculating and obtaining the preset working current based on the stress condition of the suspension wire and the basic performance of the motor includes: Calculating the torque value output by the motor based on the pulling force and the gear radius; and calculating the basic power of the motor based on the basic current and basic voltage; Calculating a preset output power of the motor based on the torque value, the motor reduction box speed ratio, the motor base power, the linear speed and the gear radius; The preset operating current is calculated based on the preset output power and the basic voltage.

4. The method according to claim 1, characterized in that: The error detection process includes: obtaining the power supply voltage of the motor where the control unit is located, determining whether the power supply voltage is within a voltage threshold range, and if not, reducing the power supply voltage of the motor through a voltage regulator until the ratio of the actual working current of the motor to the preset working current is within a first normal ratio range.

5. The method according to claim 4, characterized in that Also includes: When it is determined that the motor stall warning time is greater than a preset stall threshold, the motor is controlled to be powered off.

6. The method according to claim 1, characterized in that The error detection process includes: obtaining the vibration spectrum of the motor, and issuing a motor fault warning when it is determined that the vibration spectrum is inconsistent with a standard motor vibration spectrum.

7. The method according to claim 1, characterized in that After a motor issues a stall warning, it sends a stall signal to an adjacent motor of the motor. Based on the stall signal, the adjacent motor adjusts a first normal ratio range preset in its control unit to a second normal ratio range, where the second normal ratio range is larger than the first normal ratio range. The adjacent motor makes a stall judgment based on the adjusted first normal ratio range.

8. A multi-motor stall warning system, characterized in that: It comprises a plurality of motors, each of which is provided with a control unit and a detection unit; the detection unit is used to detect various working parameters of the motor in which it is located, and send the working parameters to the control unit of the motor, and the control unit is used to provide a stall warning for the motor based on the method described in claim 1.

9. The system according to claim 8, characterized in that One of the motors is used as the main control motor, and the main control motor establishes communication connections with other motors respectively. The main control motor is used to determine whether the number of motors for stall warning exceeds a number threshold. If exceeded, all the motors are controlled to be powered off synchronously.

10. The system according to claim 8, characterized in that The detection unit includes a tension sensor, a line speed sensor, a vibration sensor and a temperature sensor.

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