Control method for protecting high-temperature excitation loss and motor overcurrent of permanent magnet motor
By setting multiple current intervals for DC permanent magnet motor current and recording duration, triggering a fault alarm when the threshold is reached and powered off and restarting, the problems of high-temperature demagnetization and overcurrent protection of DC permanent magnet motor are solved, and the safety protection and service life of the motor are achieved.
Patent Information
- Application Number
- CN202411924408.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-25
- Publication Date
- 2025-03-25
AI Technical Summary
DC permanent magnet motors are prone to demagnetization under high temperature conditions, and overcurrent of the motor will lead to high temperatures. The prior art is difficult to effectively protect the motor, resulting in safety risks and equipment damage.
By setting multiple current intervals for the motor current and recording the duration within each interval, when the duration of a certain interval reaches the threshold, a fault alarm is triggered and powered off and restarted to avoid overheating of the motor.
Effectively judge and deal with the high temperature risks of the motor, extend the service life of the motor, avoid frequent fault alarms, and ensure the normal use of the motor.
Smart Images
Figure CN119695790A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a control method for protecting a permanent magnet motor from high-temperature demagnetization and motor overcurrent, and belongs to the technical field of permanent magnet motors. Background Art
[0002] The application of DC permanent magnet motors is becoming more and more widespread on today's scissor-type aerial work platforms. Compared with series-excited DC motors and three-phase asynchronous motors, DC permanent magnet motors have the advantages of simple structure, durability, reliable operation, high efficiency and easy maintenance.
[0003] The magnetic circuit design of a DC permanent magnet motor must solve problems such as the size of the electrical air gap, the shape of the stator and rotor slots, and the layout of the permanent magnet structure. It is required to obtain a larger air gap magnetic field fundamental wave and reduce the influence of harmonics on the motor torque and the heating and demagnetization of the permanent magnet. However, due to the influence of the assembly space of the whole machine, the motor cannot be designed to be too large, which also leads to a greatly reduced heat dissipation effect of the motor. The biggest disadvantage of a DC permanent magnet motor is that it is easy to demagnetize after high temperature. Once demagnetized, the damage to the motor is irreversible and can only be replaced. If the vehicle suddenly loses magnetism during use, it will also bring great safety risks to the user. The reason for the high temperature of the motor is that the motor current is too large. Therefore, the existing technology is in urgent need of a control method that can protect the DC permanent magnet motor from high temperature demagnetization and motor overcurrent. Summary of the invention
[0004] The purpose of the present invention is to provide a control method for protecting permanent magnet motors from high-temperature demagnetization and motor overcurrent. By dynamically recording the duration of each current interval in which the motor current is above the dangerous current, the power can be cut off and restarted in time when the motor is at high temperature risk, so as to avoid the motor continuing to work under extreme working conditions and burning out.
[0005] To achieve the above object, the present invention is implemented by adopting the following technical solutions.
[0006] On the one hand, the present invention provides a control method for protecting a permanent magnet motor from high temperature demagnetization and motor overcurrent, which comprises: Set multiple current intervals for motor currents above dangerous currents; The duration of the motor current in each current interval is recorded according to the recording rules, and the duration of each current interval corresponds to a time threshold; If the duration of one of the multiple current intervals reaches a corresponding time threshold, a fault alarm is triggered and the motor is powered off and restarted.
[0007] Optionally, the multiple current intervals are arranged in order from low to high; and the recording duration corresponding to each current interval according to the recording rule includes: Get the current motor current; If it is in the power-off restart stage or the motor current is below the dangerous current, the duration recorded in each current interval decreases with time, and stops decreasing if it decreases to 0; If the motor current is in one of the multiple current intervals; the duration corresponding to the current interval in which the motor current is located increases with timing; the duration corresponding to the current interval below the current interval in which the motor current is located remains unchanged; the duration corresponding to the current interval above the current interval in which the motor current is located decreases with timing until it decreases to 0, and stops decreasing if it decreases to 0.
[0008] Optionally, the time thresholds of the durations corresponding to the multiple current intervals set from low to high gradually decrease.
[0009] Optionally, after powering off and restarting the motor, the method further includes: The current interval whose duration reaches the corresponding time threshold is recorded as the alarm interval; The time when the fault alarm is triggered is recorded as the first time, and timing is started from the first time to obtain the timing time; If the motor has been restarted and powered on before the timing time reaches the time threshold corresponding to the alarm interval, current limiting is performed on the restarted motor until the timing time reaches the time threshold corresponding to the alarm interval and current limiting is released; If the timing time has reached the time threshold corresponding to the alarm interval when the motor is restarted and powered on, the motor will continue to work in the original state after restart.
[0010] Optionally, limiting the current of the restarted motor includes: lowering the lower limit value of each current interval to a preset proportion of the original lower limit value.
[0011] Optionally, the preset ratio is 80%.
[0012] Optionally, after setting a plurality of current intervals for the motor current to be above the dangerous current, the method further includes: determining a brake delay time according to the current interval in which the motor current is located.
[0013] Optionally, the higher the lower limit value of the current interval in which the motor current is located, the longer the delayed braking time of the brake.
[0014] In a second aspect, the present invention provides a control device for protecting a permanent magnet motor from high temperature demagnetization and motor overcurrent, comprising: A setting module, used for setting a plurality of current intervals for the motor current above the dangerous current; A recording module, used to record the duration of the motor current in each current interval according to a recording rule, and the duration of each current interval corresponds to a time threshold; The alarm module is used to trigger a fault alarm and power off and restart the motor if the duration of one of the multiple current intervals reaches a corresponding time threshold.
[0015] In a third aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, characterized in that when the computer program is executed by a processor, the control method for protecting a permanent magnet motor from high-temperature demagnetization and motor overcurrent is implemented.
[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention records the duration of the motor current in multiple current intervals, so as to promptly determine whether the motor has a high temperature risk, and accordingly adopts a power-off and restart method to effectively deal with the high temperature risk, thereby extending the service life of the motor.
[0017] 2. The recording rule of the duration in multiple current intervals of the present invention is dynamic recording, which can not only timely handle the high temperature of the motor to extend the service life, but also avoid frequent fault reporting to maintain the normal use of the motor. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 The figure is a flow chart of a control method for protecting a permanent magnet motor from high temperature demagnetization and motor overcurrent in Example 1. DETAILED DESCRIPTION
[0019] It should be noted that: The technical solution of the present invention is described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solution of the present invention, rather than limitations on the technical solution of the present invention. The embodiments of the present invention and the technical features in the embodiments may be combined with each other unless there is a conflict.
[0020] The term "and / or" is only a description of the association relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " generally indicates that the related objects are in an "or" relationship.
[0021] In the prior art known to the inventors of the present application, AC motors can capture the terminal state of the motor through sensors and the like for control, but DC motors are different from AC motors. DC motors do not have temperature sensors or speed sensors. In actual use, DC motors are equivalent to being in an open-loop state all the time, and the ECU controller cannot accurately capture the terminal state of the motor. When the motor is in abnormal states such as high temperature and stall, the ECU and the driver cannot perform closed-loop control through effective means such as sensors. In addition, for permanent magnet motors, the main reason for the demagnetization of the motor is high temperature. When the temperature of the magnetic steel exceeds its own limit value, the magnetic field force will weaken. Once the motor is demagnetized, the damage caused is irreversible and can only be replaced. In order to avoid the above phenomenon, from the aspect of the motor itself manufacturing, it cannot be effectively solved in a short time, but it can be achieved by soft protection at the software level to protect the motor from high temperature demagnetization. In the same principle, the main reason for the damage of the brake and the burning of the motor is also because the high temperature of the motor causes the melting of components, and the reason for the high temperature of the motor is that the motor current is too large. In order to completely solve the safety risks brought about by the above problems, the present application proposes a strategic protection method for protecting the high temperature demagnetization and overcurrent of the DC permanent magnet motor.
[0022] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention. Example 1
[0023] This embodiment introduces a control method for protecting a permanent magnet motor from high temperature demagnetization and motor overcurrent, including: Step S1: setting multiple current intervals for motor currents above dangerous currents; The dangerous current can be understood as an artificially set current value dividing line for motor demagnetization caused by high temperature. Once the motor current exceeds the dangerous current, high temperature demagnetization may occur. However, if the dangerous current is directly set as an interval, the overcurrent protection strategy may be difficult to meet actual needs. It is easy to understand that a motor current that just exceeds the dangerous current and a motor current that exceeds the dangerous current by a lot have completely different effects on motor heating. Therefore, in this embodiment, multiple current intervals are set above the dangerous current to achieve refined control.
[0024] Step S2: recording the duration of the motor current in each current interval according to the recording rule, and the duration of each current interval corresponds to a time threshold; Specifically, if the motor current remains above the dangerous current for a certain period of time, a large amount of heat will be generated accordingly, thereby posing a risk of motor overheating. Therefore, in this embodiment, based on the set multiple intervals, the duration of the motor current in each current interval is recorded according to the recording rules. This duration can accurately characterize the risk of motor overheating.
[0025] Step S3: If the duration of one of the multiple current intervals reaches a corresponding time threshold, a fault alarm is triggered and the motor is powered off and restarted.
[0026] It can be understood that if the motor current is continuously above the dangerous current, it can be understood that the limit working condition of the component has been reached. If effective protective measures are not taken in time, it may cause the machine to burn out. Therefore, the method adopted in this embodiment is that if the duration of one of the multiple current intervals reaches the corresponding time threshold, a fault alarm will be triggered and the motor will be powered off and restarted to prevent the motor from continuing to heat up.
[0027] In a specific embodiment, the recording rule for recording the duration of the motor current in each current interval according to the recording rule may be: Take one of the current intervals as an example. When the motor current is in this interval, the duration corresponding to the current interval keeps counting. When the motor current leaves this interval, the duration stops counting and remains the same. When the duration of the current interval reaches the preset threshold to trigger an alarm and restart the motor, the duration of the current interval is reset to zero and the recording starts again. This recording rule can also protect the motor in time under extreme working conditions.
[0028] However, during use, there may be a problem of multiple fault alarms being triggered. For example, the multiple current intervals include the first interval, the second interval, the third interval, and the fourth interval. If the duration corresponding to the first interval triggers the fault alarm, the duration corresponding to the second interval may be only a few seconds away from triggering the fault alarm. Once the motor current enters the second interval, the fault alarm will be triggered again. However, in fact, the risk of high temperature of the motor is not very high at this time. This may not only cause the motor to be frequently opened and closed and damaged, but also may cause a certain degree of false fault alarms.
[0029] Based on the above problem, therefore, in another specific embodiment, the multiple current intervals are arranged in sequence from low to high; The recording rule for recording the duration of the motor current in each current interval is: The recording duration corresponding to each current interval according to the recording rule includes: Step S21: obtaining motor current; Step S22: If it is in the power-off restart stage or the motor current is below the dangerous current, the duration recorded in each current interval decreases with time, and if it decreases to 0, it stops decreasing; this means that under the recording rules of this embodiment, when a fault alarm is triggered, the duration will not be directly cleared to zero, but will still decrease with the timing.
[0030] Step S23: If the motor current is above the dangerous current and is in one of the multiple current intervals; the duration of the current interval in which the motor current is located increases with timing; the duration corresponding to the current interval below the current interval in which the motor current is located remains unchanged; the duration corresponding to the current interval above the current interval in which the motor current is located decreases with timing until it is reduced to 0, and if it is reduced to 0, the reduction stops.
[0031] Specifically, a dynamic recording method is adopted in this embodiment, and the duration corresponding to each current interval is not continuously accumulated, but is dynamically recorded in accordance with the dangerous trend. It can be understood that the higher the lower limit value of the current interval in which the motor current is located, the higher the high temperature risk is, and correspondingly, the lower the lower limit value of the current interval in which the motor current is located, the lower the high temperature risk is. Therefore, in this embodiment, the time threshold of the duration corresponding to the multiple current intervals set from low to high is also gradually reduced. If the motor current stays in the current interval with a higher lower limit value, even if the stay time is short, it will trigger an alarm in time to avoid damaging the motor.
[0032] Furthermore, under the recording rule, when the motor current is in one of the intervals, the duration of the interval increases with the timing, the duration of the current intervals above the interval decreases with the timing, and the duration of the current intervals below the interval remains unchanged. In a specific embodiment, the "increase with timing" and "decrease with timing" here are both linear relationships, for example, every 1s of timing, increase or decrease 1s, of course, in order to further optimize the control relationship between each current interval, the "increase with timing" and "decrease with timing" here can also increase or decrease according to a preset ratio, for example, every 1s of timing, increase or decrease 0.5s-2s. This embodiment is not specifically limited.
[0033] Because from the perspective of the size of the high temperature risk, the high temperature risk in this interval is lower than that in the current interval above this interval. Therefore, the duration of the current interval above this interval will decrease over time, which means that the high temperature risk is decreasing and the high temperature situation is easing. However, the high temperature risk in this interval is higher than that in the current interval below this interval, so the duration of the current interval below this interval will remain unchanged, which means that the high temperature risk may still have an upward trend, in case the motor current continues to stay in other current intervals above the dangerous current, so as to trigger a fault warning in time. This embodiment adopts such a recording method, which can not only handle the high temperature of the motor in time to extend the service life, but also avoid frequent fault reporting to maintain the normal use of the motor.
[0034] This is explained with examples, for example: the dangerous current is M4, and the multiple current intervals are set from low to high as the fourth interval, the third interval, the second interval and the first interval, the fourth interval is [M4, M3), the third interval is [M3, M2), the second interval is [M2, M1), and the first interval is (M1, +∞). When the motor current is in the first interval, the second interval, the third interval and the fourth interval, they are respectively the first stage, the second stage, the third stage and the fourth stage; the corresponding time thresholds are S1, S2, S3 and S4 respectively. S1, S2, S3 and S4 gradually increase. The current value M in each stage mainly serves the purpose of limitation, reducing the heat generated by the motor to extend the operating time of the motor.
[0035] When the motor current is in the second interval, the duration corresponding to the first interval will decrease with the timing, the duration corresponding to the second interval itself will increase with the timing, and the durations of the third and fourth intervals remain unchanged.
[0036] In another specific embodiment, in order to match the large current operation, reduce the brake wear or motor friction heating, the brake delay time is effectively matched according to the current size. The same principle, the main reason for the damage to the brake and the burning of the motor is also because the high temperature of the motor causes the components to melt, and the reason for the high temperature of the motor is that the motor current is too large. In this embodiment, the brake delay time is determined according to the current interval in which the motor current is located; the higher the lower limit value of the current interval in which the motor current is located, the longer the brake delay time.
[0037] For example, the multiple current intervals are set from low to high as the fourth interval, the third interval, the second interval and the first interval, and correspond to the first stage, the second stage, the third stage and the fourth stage. When in the first stage, the brake is applied after N1 seconds, and the brake is released immediately when the emergency stop is taken; when in the second stage, the brake is applied after N2 seconds (N2<N1), and the brake is released immediately when the emergency stop is taken; when in the third stage, the brake is applied after N3 seconds (N3<N2), and the brake is released immediately when the emergency stop is taken. Example 2
[0038] The present embodiment is the same as the first embodiment, but is different from the first embodiment in that: after the motor is powered off and restarted, the present embodiment further includes: Step S4: Record the current interval whose duration reaches the corresponding time threshold as the alarm interval; record the moment when the fault alarm is triggered as the first moment, and start timing from the first moment; Step S5: If the motor has been restarted and powered on before the timing time reaches the time threshold corresponding to the alarm interval, the current of the restarted motor is limited until the timing time reaches the time threshold corresponding to the alarm interval and the current limiting is lifted; if the timing time has reached the time threshold corresponding to the alarm interval when the motor is restarted and powered on, the restarted motor maintains the original working state.
[0039] Specifically, after the motor is powered off and restarted, the temperature of the motor may still be high due to the general heat dissipation function of the motor, so it is necessary to avoid the motor from working in extreme conditions again as much as possible. To solve this problem, in this embodiment, if the timing time has not reached the time threshold corresponding to the alarm interval when the motor is restarted and powered on, the motor is current limited, and the current limiting includes lowering the lower limit value of each current interval to a preset ratio of the original lower limit value. If a large current appears again after the motor is restarted due to a large load or other circumstances, the alarm can be triggered more promptly to avoid further aggravation of the high temperature situation due to the heat generated by the large current when the motor temperature has not dropped again, thereby extending the use time of the motor. In a specific embodiment, the preset ratio is 80%. Example 3
[0040] Based on the same inventive concept as that of Embodiment 1, this embodiment introduces a control device for protecting a permanent magnet motor from high temperature demagnetization and motor overcurrent, which includes: A setting module, used for setting a plurality of current intervals for the motor current above the dangerous current; A recording module, used to record the duration of the motor current in each current interval according to a recording rule, and the duration of each current interval corresponds to a time threshold; The alarm module is used to trigger a fault alarm and power off and restart the motor if the duration of one of the multiple current intervals reaches a corresponding time threshold. Example 4
[0041] This embodiment provides a computer-readable storage medium on which a computer program is stored, characterized in that when the computer program is executed by a processor, a control method for protecting a permanent magnet motor from high-temperature demagnetization and motor overcurrent as described in Embodiment 1 is implemented.
[0042] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.
[0043] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.
[0044] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.
[0045] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1The steps for the functions specified in one or more boxes.
[0046] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the enlightenment of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, which all fall within the protection of the present invention.
Claims
1. A control method for protecting a permanent magnet motor from high temperature demagnetization and motor overcurrent, characterized in that: include: Set multiple current intervals for motor currents above dangerous currents; The duration of the motor current in each current interval is recorded according to the recording rules, and the duration of each current interval corresponds to a time threshold; If the duration of one of the multiple current intervals reaches a corresponding time threshold, a fault alarm is triggered and the motor is powered off and restarted.
2. A control method for protecting a permanent magnet motor from high temperature demagnetization and motor overcurrent according to claim 1, characterized in that: The multiple current intervals are arranged in order from low to high; and the recording duration corresponding to each current interval according to the recording rule includes: Get the current motor current; If it is in the power-off restart stage or the motor current is below the dangerous current, the duration recorded in each current interval decreases with time, and stops decreasing if it decreases to 0; If the motor current is in one of the multiple current intervals; the duration corresponding to the current interval in which the motor current is located increases with timing; the duration corresponding to the current interval below the current interval in which the motor current is located remains unchanged; the duration corresponding to the current interval above the current interval in which the motor current is located decreases with timing until it decreases to 0, and stops decreasing if it decreases to 0.
3. A control method for protecting a permanent magnet motor from high temperature demagnetization and motor overcurrent according to claim 2, characterized in that: The time thresholds of the durations corresponding to the multiple current intervals set from low to high gradually decrease.
4. A control method for protecting a permanent magnet motor from high temperature demagnetization and motor overcurrent according to claim 1, characterized in that: After the motor is powered off and restarted, the following steps are further included: The current interval whose duration reaches the corresponding time threshold is recorded as the alarm interval; The time when the fault alarm is triggered is recorded as the first time, and timing is started from the first time to obtain the timing time; If the motor has been restarted and powered on before the timing time reaches the time threshold corresponding to the alarm interval, current limiting is performed on the restarted motor until the timing time reaches the time threshold corresponding to the alarm interval and current limiting is released; If the timing time has reached the time threshold corresponding to the alarm interval when the motor is restarted and powered on, the motor will continue to work in the original state after restart.
5. A control method for protecting a permanent magnet motor from high temperature demagnetization and motor overcurrent according to claim 4, characterized in that: The current limiting of the restarted motor includes: adjusting the lower limit value of each current interval down to a preset ratio of the original lower limit value.
6. A control method for protecting a permanent magnet motor from high temperature demagnetization and motor overcurrent according to claim 5, characterized in that: The preset ratio is 80%.
7. A control method for protecting a permanent magnet motor from high temperature demagnetization and motor overcurrent according to claim 1, characterized in that: After setting a plurality of current intervals for the motor current to be above the dangerous current, the method further includes: determining a brake delay holding time according to the current interval in which the motor current is located.
8. A control method for protecting a permanent magnet motor from high temperature demagnetization and motor overcurrent according to claim 7, characterized in that: The higher the lower limit value of the current interval in which the motor current is located, the longer the delayed braking time of the brake.
9. A control device for protecting a permanent magnet motor from high temperature demagnetization and motor overcurrent, characterized in that: include: A setting module, used for setting a plurality of current intervals for the motor current above the dangerous current; A recording module, used to record the duration of the motor current in each current interval according to a recording rule, and the duration of each current interval corresponds to a time threshold; The alarm module is used to trigger a fault alarm and power off and restart the motor if the duration of one of the multiple current intervals reaches a corresponding time threshold.
10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, a control method for protecting a permanent magnet motor from high temperature demagnetization and motor overcurrent as described in any one of claims 1 to 8 is implemented.