Motor control circuit and protection device

Abstract

The invention relates to a motor control circuit and a protection device, the motor control circuit comprises a driving module, a first control circuit and a second control circuit, one end of the first control circuit is used for being connected with a power supply, the other end of the first control circuit is connected with the driving module, and the second control circuit is connected with the first control circuit in parallel; the control module is used for controlling the first control circuit to be switched on under the condition that the power supply fault is determined and the power supply fault time is less than a preset time threshold value so as to form a path among the power supply, the first control circuit, the driving module and the motor; and the first control circuit is used for recording the conduction time of the first control circuit, and is switched off under the condition that the conduction time is greater than or equal to a time threshold value. Thus, even if the power supply breaks down, the motor can be controlled to be automatically started through the second control circuit and the first control circuit within the preset time threshold value, production delay is avoided, and therefore the production stability and the production efficiency can be effectively improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of electrical equipment, and in particular, to a motor control circuit and a protection device. Background Art

[0002] In industrial production processes, when the instantaneous voltage of the power system drops or is interrupted (power slosh), the motor may suddenly stop running, causing production line interruptions, damage to product quality, and even safety accidents.

[0003] In the prior art, a memory loop is designed inside the motor control circuit to restore the motor's initial operating state after power is restored. However, the reliability of these memory loops is not high. After many simulation tests, it was found that the motor still cannot start automatically, which usually requires manual intervention, which not only increases the workload of operators, but also may cause production delays, seriously affecting the stability and efficiency of industrial production. Summary of the invention

[0004] In order to overcome the problems existing in the related art, the purpose of the present disclosure is to provide a motor control circuit and a protection device.

[0005] According to a first aspect of an embodiment of the present disclosure, a motor control circuit is provided, the motor control circuit comprising a drive module, a first control circuit and a second control circuit, one end of the first control circuit is used to connect to a power supply, the other end of the first control circuit is connected to the drive module, the drive module is also connected to the motor, and the second control circuit is connected in parallel with the first control circuit. The second control circuit is used to control the first control circuit to conduct when it is determined that the power supply fails and the power supply failure time is less than a preset time threshold, so as to form a path between the power supply, the first control circuit, the drive module and the motor; The first control circuit is used to record the on-time of the first control circuit, and to disconnect when the on-time is greater than or equal to the time threshold.

[0006] Optionally, the first control circuit includes a coil of a contactor, a first normally open contact of the contactor, a coil of a first relay, a second normally open contact of the first relay, a coil of a second relay, and a third normally open contact of the second relay. One end of the coil of the contactor is connected to the power supply, the other end of the coil of the contactor is connected to one end of the first normally open contact, the coil of the first relay is connected in parallel with the coil of the contactor, the other end of the first normally open contact is connected to one end of the second normally open contact, the other end of the second normally open contact is connected to one end of the coil of the second relay, the other end of the coil of the second relay is connected to the power supply and the coil of the contactor, and the third normally open contact is connected in parallel with the first normally open contact; The first control circuit is used to control the coil of the contactor, the coil of the first relay and the coil of the second relay to be energized, and the first normally open contact, the second normally open contact and the third normally open contact to be closed when it is determined that the second control circuit is turned on.

[0007] Optionally, the second control circuit includes a fourth normally open contact of the first relay and a first normally closed contact of the second relay, One end of the fourth normally open contact is connected to the coil of the contactor, the other end of the fourth normally open contact is connected to one end of the first normally closed contact, and the other end of the first normally closed contact is connected to the coil of the first relay and the coil of the contactor; The second control circuit is used to control the fourth normally open contact to close so that the coil of the contactor and the coil of the first relay are energized when it is determined that the power supply fails and the power supply failure time is less than the time threshold.

[0008] Optionally, the first control circuit is also used to, when it is determined that the power failure has occurred and the power failure time is less than the time threshold, if it is determined that the coil of the contactor and the coil of the first relay are energized, control the first normally open contact and the second normally open contact to close, and energize the coil of the second relay to open the first normally closed contact.

[0009] Optionally, the first control circuit further includes a fifth normally open contact of the third relay and a second normally closed contact of the fourth relay, one end of the fifth normally open contact is connected to the first normally open contact, the other end of the fifth normally open contact is connected to one end of the second normally closed contact, and the other end of the second normally closed contact is connected to the coil of the contactor. The first control circuit is used to control the fifth normally open contact to be disconnected and the second normally closed contact to be disconnected when receiving a motor stop instruction, so as to stop the motor; The first control circuit is further configured to control the fourth normally open contact to close when receiving a motor operation instruction, so as to enable the motor to operate.

[0010] Optionally, the first control circuit further includes a sixth normally open contact of the contactor, wherein the sixth normally open contact is connected in parallel with the fifth normally open contact. The first control circuit is used to control the sixth normally open contact to close and the second normally closed contact to open when receiving a motor stop instruction, so as to stop the motor; The first control circuit is further configured to control the sixth normally open contact to close when receiving a motor operation instruction, so as to enable the motor to operate.

[0011] Optionally, the second control circuit further includes a seventh normally open contact of a fifth relay and a coil of the fifth relay, the seventh normally open contact is connected in parallel with the fifth normally open contact, one end of the coil of the fifth relay is connected to the first normally closed contact, and one end of the coil of the fifth relay is connected to the coil of the first relay, the coil of the second relay and the coil of the contactor, The second control circuit is used to control the third normally open contact to close and the coil of the fifth relay to be energized when it is determined that the power supply fails and the power supply failure time is less than the time threshold, so that the seventh normally open contact is closed and the coil of the contactor and the coil of the first relay are energized.

[0012] Optionally, the first control circuit further includes a coil of a third relay and a coil of a fourth relay, the coil of the third relay is connected to the power supply, the coil of the second relay, the coil of the first relay and the coil of the contactor, and the coil of the fourth relay is connected in parallel with the coil of the third relay. The first control circuit is used for, when receiving a motor working instruction, energizing the coil of the third relay and closing the fifth normally open contact to start the motor running; The first control circuit is also used for, when receiving a motor stop command, de-energizing the coil of the third relay, energizing the coil of the fourth relay, disconnecting the fifth normally open contact, and disconnecting the second normally closed contact, so as to stop the motor.

[0013] Optionally, the first relay is a time delay relay, and the third relay and the fourth relay are extension relays.

[0014] According to a second aspect of an embodiment of the present disclosure, a protection device is provided, comprising the motor control circuit described in the first aspect.

[0015] Through the above technical scheme, the motor control circuit and protection device provided by the present disclosure, the motor control circuit includes a drive module, a first control circuit and a second control circuit, one end of the first control circuit is used to connect to a power supply, the other end of the first control circuit is connected to the drive module, the drive module is also connected to the motor, the second control circuit is connected in parallel with the first control circuit, the second control circuit is used to control the first control circuit to be turned on when it is determined that the power supply fails and the power supply failure time is less than a preset time threshold, so as to form a path between the power supply, the first control circuit, the drive module and the motor; the first control circuit is used to record the conduction time of the first control circuit, and disconnect when the conduction time is greater than or equal to the time threshold. In this way, when a power failure is determined and the power failure time is less than a preset time threshold, the first control circuit is controlled to be turned on through the second control circuit to form a path between the power supply, the first control circuit, the drive module and the motor, and when the on-time of the first control circuit is greater than or equal to the time threshold, the first control circuit is controlled to be disconnected, which can ensure that even if the power failure occurs, the motor can be controlled to self-start within the preset time threshold through the second control circuit and the first control circuit, thereby avoiding production delays, thereby effectively improving production stability and production efficiency, and further effectively improving user experience and satisfaction.

[0016] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure.

[0017] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings: Figure 1 is a block diagram of a motor control circuit according to an exemplary embodiment; Figure 2 is based on Figure 1 The illustrated embodiment shows a circuit diagram of a motor control circuit.

[0019] Description of Reference Numerals 101 first control circuit 102 second control circuit 103 drive module 104 motor 105 power supply SJ1 first relay KA second relay K1 third relay K2 4th relay SJ 5th relay C contactor DETAILED DESCRIPTION Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. Instead, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0020] It should be understood that, unless otherwise specifically noted, the features of some embodiments of the various present disclosures described herein may be combined with each other. As used herein, the term "and / or" includes any one of the related listed items and any combination of any two or more; similarly, "at least one of . . . " includes any one of the related listed items and any combination of any two or more.

[0021] Before introducing the specific implementation methods of the present disclosure in detail, the application scenarios of the present disclosure are first described as follows. The present disclosure can be applied to the application scenarios of motor control circuits for controlling motors. In the industrial production process, when the instantaneous voltage of the power system drops or is interrupted (power shake), the motor may suddenly stop running, resulting in production line interruption, product quality damage, and even safety accidents. In the prior art, a memory circuit is designed inside the motor control circuit to restore the initial operating state of the motor after power is restored. However, the reliability of these memory circuits is not high. After many simulation tests, it was found that there is still a problem that the motor cannot start by itself, which usually requires manual intervention, which not only increases the workload of the operator, but also may cause production delays, seriously affecting the stability and production efficiency of industrial production.

[0022] In order to solve the above technical problems, the present disclosure provides a motor control circuit and a protection device, wherein the motor control circuit includes a drive module, a first control circuit and a second control circuit, wherein one end of the first control circuit is used to connect a power supply, and the other end of the first control circuit is connected to the drive module, and the drive module is also connected to the motor, and the second control circuit is connected in parallel with the first control circuit, and the second control circuit is used to control the first control circuit to be turned on when it is determined that the power supply fails and the power supply failure time is less than a preset time threshold, so as to form a path between the power supply, the first control circuit, the drive module and the motor; the first control circuit is used to record the conduction time of the first control circuit, and disconnect when the conduction time is greater than or equal to the time threshold. In this way, when a power failure is determined and the power failure time is less than a preset time threshold, the first control circuit is controlled to be turned on through the second control circuit to form a path between the power supply, the first control circuit, the drive module and the motor, and when the on-time of the first control circuit is greater than or equal to the time threshold, the first control circuit is controlled to be disconnected, which can ensure that even if the power failure occurs, the motor can be controlled to self-start within the preset time threshold through the second control circuit and the first control circuit, thereby avoiding production delays, thereby effectively improving production stability and production efficiency, and further effectively improving user experience and satisfaction.

[0023] The embodiments described in some embodiments of the present disclosure below do not represent all embodiments consistent with the present disclosure. Instead, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0024] Figure 1 is a block diagram of a motor control circuit according to an exemplary embodiment. Figure 1 As shown, the motor 104 control circuit includes a driving module 103, a first control circuit 101 and a second control circuit 102, one end of the first control circuit 101 is used to connect to a power supply 105, the other end of the first control circuit 101 is connected to the driving module 103, the driving module 103 is also connected to the motor 104, and the second control circuit 102 is connected in parallel with the first control circuit 101. The second control circuit 102 is used to control the first control circuit 101 to be turned on to form a path between the power supply 105, the first control circuit 101, the driving module 103 and the motor 104 when it is determined that the power supply 105 fails and the failure time of the power supply 105 is less than a preset time threshold; The first control circuit 101 is used to record the on-time of the first control circuit 101, and disconnect when the on-time is greater than or equal to the time threshold.

[0025] Among them, the motor 104 control circuit is applied to the low-voltage motor 104 to realize the protection, monitoring and control functions of the low-voltage motor 104, and realize the remote monitoring of the low-voltage motor 104 circuit through the field bus technology. The drive module 103 is used to convert the control signal into the drive signal required by the motor 104, and directly control the start, stop and running state of the motor 104. The first control circuit 101 is used to receive the input voltage from the power supply 105 to provide the necessary power for the entire first control circuit 101. And the processed control signal is passed to the drive module 103, so that the drive module 103 controls the operation of the motor 104 according to these signals. The second control circuit 102 is connected in parallel with the first control circuit 101 to provide additional control and protection functions. For example, the second control circuit 102 can be used to realize automatic restart and protection of the motor 104 after power is restored.

[0026] In the above technical scheme, when a power failure is determined and the power failure time is less than a preset time threshold, the first control circuit is controlled to be turned on through the second control circuit to form a path between the power supply, the first control circuit, the drive module and the motor, and when the conduction time of the first control circuit is greater than or equal to the time threshold, the first control circuit is controlled to be disconnected, which can ensure that even if the power failure occurs, the motor can be controlled to self-start within the preset time threshold through the second control circuit and the first control circuit, thereby avoiding production delays, thereby effectively improving production stability and production efficiency, and further effectively improving user experience and satisfaction.

[0027] Figure 2 is based on Figure 1 The circuit diagram of a motor control circuit shown in the embodiment shown in FIG. Figure 2 As shown, the first control circuit 101 includes a coil C of a contactor, a first normally open contact C of the contactor, a coil of a first relay SJ1, a second normally open contact SJ1 of the first relay, a coil of a second relay KA, and a third normally open contact KA of the second relay KA. One end of the coil C of the contactor is connected to the power supply 105, the other end of the coil C of the contactor is connected to one end of the first normally open contact C, the coil SJ1 of the first relay is connected in parallel with the coil C of the contactor, the other end of the first normally open contact C is connected to one end of the second normally open contact SJ1, the other end of the second normally open contact SJ1 is connected to one end of the coil KA of the second relay, the other end of the coil KA of the second relay is connected to the power supply 105 and the coil C of the contactor, and the third normally open contact KA is connected in parallel with the first normally open contact C; The first control circuit 101 is used to control the coil C of the contactor, the coil SJ1 of the first relay and the coil KA of the second relay to be energized, and the first normally open contact C, the second normally open contact SJ1 and the third normally open contact KA to be closed when it is determined that the second control circuit 102 is turned on.

[0028] Wherein, the contactor may be an AC contactor or other contactor used to control the on and off of an AC circuit. The first relay is a time delay relay, and the delay type of the first relay is a delayed disconnection. When the on time is longer than a preset time threshold, the first control circuit 101 is disconnected. When it is determined that the second control circuit 102 is turned on, the coil C of the contactor, the coil SJ1 of the first relay, and the coil KA of the second relay are energized, and the first normally open contact C, the second normally open contact SJ1, and the third normally open contact KA are closed to form a path between the power supply 105, the drive module 103, the first normally open contact C, the second normally open contact SJ1, the third normally open contact KA, the coil KA of the second relay, the coil C of the contactor, and the coil SJ1 of the first relay.

[0029] The above technical scheme, when it is determined that the second control circuit is turned on, turns on the first control circuit, and forms a path between the power supply, the first control circuit, the drive module and the motor through the first control circuit, which can ensure that even if the power supply fails, the motor can be controlled to self-start through the second control circuit and the first control circuit within a preset time threshold, thereby avoiding production delays.

[0030] Optionally, Figure 2 For example, the second control circuit 102 includes a fourth normally open contact SJ1 of the first relay and a first normally closed contact KA of the second relay. One end of the fourth normally open contact SJ1 is connected to the coil C of the contactor, the other end of the fourth normally open contact is connected to one end of the first normally closed contact KA, and the other end of the first normally closed contact KA is connected to the coil SJ1 of the first relay and the coil C of the contactor; The second control circuit 102 is used to control the fourth normally open contact SJ1 to close so that the coil C of the contactor and the coil SJ1 of the first relay are energized when it is determined that the power supply 105 fails and the failure time of the power supply 105 is less than the time threshold.

[0031] Among them, the first normally closed contact KA means that the contact is in a closed (conducting) state when it is not affected by an external control signal. When an external control signal (such as electromagnet attraction) acts, the contact will be disconnected (non-conducting), which can be used in electrical equipment such as relays and contactors. When the coil KA of the second relay is not energized, the first normally closed contact KA is closed; when the coil KA of the second relay is energized, the first normally closed contact KA will be disconnected. When it is determined that the power supply 105 fails and the power supply 105 failure time is less than the time threshold, the fourth normally open contact SJ1 is controlled to close so that the coil C of the contactor and the coil SJ1 of the first relay are energized, forming a path between the fourth normally open contact SJ1, the first normally closed contact KA, the coil C of the contactor and the coil SJ1 of the first relay.

[0032] The above technical solution monitors the power supply status and controls the closing of the fourth normally open contact under specific conditions to ensure that the coil of the contactor and the coil of the first relay are energized, thereby enabling the first control circuit to be turned on to achieve rapid resumption of operation of the motor. It can effectively solve the problem that the motor cannot start automatically after power is restored, thereby improving the stability of the system and production efficiency.

[0033] Optionally, the first control circuit 101 is also used to control the first normally open contact C and the second normally open contact SJ1 to close, and the coil KA of the second relay to be energized, so that the first normally closed contact KA is opened, when it is determined that the power supply 105 fails and the failure time of the power supply 105 is less than the time threshold, if it is determined that the coil C of the contactor and the coil SJ1 of the first relay are energized.

[0034] In the above technical solution, when it is determined that the power supply fault occurs and the power supply fault time is less than the time threshold, if it is determined that the second control circuit is turned on, the first control circuit energizes the coil of the second relay to disconnect the first normally closed contact, thereby disconnecting the second control circuit.

[0035] Optionally, Figure 2 For example, the first control circuit 101 further includes the 45th normally open contact of the third relay K1 and the second normally closed contact K2 of the fourth relay K2, one end of the 54th normally open contact is connected to the first normally open contact C, the other end of the 54th normally open contact is connected to one end of the second normally closed contact K2, and the other end of the second normally closed contact K2 is connected to the coil C of the contactor, The first control circuit 101 is further used to control the fifth and fourth normally open contacts to be disconnected and the second normally closed contact K2 to be disconnected when receiving a stop command of the motor 104, so that the motor 104 stops working; The first control circuit 101 is further configured to control the fourth normally open contact SJ1 to close when receiving a working instruction of the motor 104 so as to enable the motor 104 to work.

[0036] Among them, the first control circuit 101 is used to receive the motor 104 stop command and the motor 104 work command, and the contact voltage of the motor 104 stop command and the motor 104 work command is between DC 280 and 320 volts (the voltage value varies in different environments, the coal transportation and chemical system voltage value is about 280 volts, and the main plant system voltage value is about 310 volts).

[0037] The above technical solution, when receiving the motor stop command, controls the fourth normally open contact and the second normally closed contact to be disconnected, so that the motor stops working. When receiving the motor working command, controls the fourth normally open contact to be closed, so that the motor starts working. It can ensure the stable operation of the motor under various circumstances and improve the continuity and efficiency of production.

[0038] Optionally, Figure 2 For example, the first control circuit 101 further includes a sixth normally open contact C of the contactor, and the sixth normally open contact C is connected in parallel with the fifth normally open contact K1. The first control circuit 101 is used to control the sixth normally open contact C to close and the second normally closed contact K2 to open when receiving a stop instruction of the motor 104, so as to stop the motor 104; The first control circuit 101 is further configured to control the sixth normally open contact C to close when receiving a working instruction of the motor 104 so as to enable the motor 104 to work.

[0039] The contactor may be an AC contactor or other contactor used to control the on and off of an AC circuit. The first relay is a time delay relay, and the delay type of the first relay is a delayed disconnection. When the on time is longer than a preset time threshold, the first control circuit 101 is disconnected. When the coil K2 of the fourth relay is not energized, the second normally closed contact K2 is closed; when the coil K2 of the fourth relay is energized, the second normally closed contact K2 is disconnected.

[0040] The above technical solution, by connecting the sixth normally open contact in parallel with the fifth normally open contact, makes the motor stop command controlled only by the second normally closed contact, which can avoid the motor false tripping caused by jitter or interference of the fifth normally open contact, thereby further effectively improving the stability and reliability of production.

[0041] Optionally, Figure 2 For example, the second control circuit 102 also includes a seventh normally open contact SJ of a fifth relay SJ and a coil SJ of the fifth relay, the seventh normally open contact SJ is connected in parallel with the fifth normally open contact K1, one end of the coil SJ of the fifth relay is connected to the first normally closed contact KA, one end of the coil SJ of the fifth relay is connected to the coil SJ1 of the first relay, the coil KA of the second relay and the coil C of the contactor, The second control circuit 102 is used to control the third normally open contact KA to close and the coil SJ of the fifth relay to be energized when it is determined that the power supply 105 is faulty and the fault time of the power supply 105 is less than the time threshold, so that the seventh normally open contact SJ is closed and the coil C of the contactor and the coil SJ1 of the first relay are energized.

[0042] Among them, the fifth relay is a time delay relay, and the delay type of the fifth relay is delayed start. When the conduction time is longer than a preset time threshold, the seventh normally open contact SJ is closed.

[0043] In the above technical scheme, the second control circuit introduces the fifth relay and the seventh normally open contact. When the power supply fails and the fault time is less than the set time threshold, the third normally open contact is controlled to close, so that the coil of the fifth relay is energized, the seventh normally open contact is closed, the coil of the contactor and the coil of the first relay are energized, and the motor operation is restored, thereby ensuring the stable operation of the motor and improving the continuity and efficiency of production.

[0044] Optionally, Figure 2For example, the first control circuit 101 further includes a coil of a third relay K1 and a coil of a fourth relay K2, one end of the coil K1 of the third relay is connected to the power supply 105, the coil KA of the second relay, the coil SJ1 of the first relay and the coil C of the contactor, and the coil of the fourth relay KT3 is connected in parallel with the coil of the third relay KT1. The first control circuit 101 is used for, when receiving a working instruction of the motor 104, energizing the coil of the third relay KT1 and closing the fifth normally open contact K1, so that the motor 104 starts to run; The first control circuit 101 is also used for, when receiving a stop command of the motor 104, de-energizing the coil of the third relay KT1, energizing the coil of the fourth relay KT3, disconnecting the fifth normally open contact K1, and disconnecting the second normally closed contact K2, so as to stop the motor 104.

[0045] Among them, the first relay SJ1 is a time delay relay, and the third relay K1 and the fourth relay K2 are extension relays. The extension relay can be an AC 220V extension relay. The first control circuit 101 is used to receive the motor 104 stop command and the motor 104 work command. The contact voltage of the motor 104 stop command and the motor 104 work command is between DC 280 and 320 volts (the voltage value varies in different environments, the coal transportation and chemical system voltage value is about 280 volts, and the main plant system voltage value is about 310 volts). The AC 220V extension relay is used to isolate the motor 104 stop command and the motor 104 work command to ensure that the switch input voltage value is DC110V to prevent the voltage from being too high and misclosing or misjudging. The third relay and the fourth relay are extended intermediate relays for remote control closing and opening commands, and their respective contacts send UNT programmable input contacts as input instructions for the motor 104 to stop and the motor 104 to work.

[0046] The above technical scheme, by isolating the contact voltage of the motor stop command and the motor working command through the third relay and the fourth relay, can enhance the anti-interference ability, thereby avoiding malfunction of the device caused by excessive input contact voltage, and further effectively improving the stability and reliability of the motor control circuit.

[0047] In another exemplary embodiment of the present disclosure, a protection device is shown, which includes the above Figure 1-Figure 2 Any motor control circuit described above.

[0048] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0049] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0050] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A motor control circuit, characterized in that: The motor control circuit includes a drive module, a first control circuit and a second control circuit, one end of the first control circuit is used to connect to a power supply, the other end of the first control circuit is connected to the drive module, the drive module is also connected to the motor, and the second control circuit is connected in parallel with the first control circuit. The second control circuit is used to control the first control circuit to conduct when it is determined that the power supply fails and the power supply failure time is less than a preset time threshold, so as to form a path between the power supply, the first control circuit, the drive module and the motor; The first control circuit is used to record the on-time of the first control circuit, and to disconnect when the on-time is greater than or equal to the time threshold.

2. The motor control circuit according to claim 1, characterized in that: The first control circuit includes a coil of a contactor, a first normally open contact of the contactor, a coil of a first relay, a second normally open contact of the first relay, a coil of a second relay, and a third normally open contact of the second relay. One end of the coil of the contactor is connected to the power supply, the other end of the coil of the contactor is connected to one end of the first normally open contact, the coil of the first relay is connected in parallel with the coil of the contactor, the other end of the first normally open contact is connected to one end of the second normally open contact, the other end of the second normally open contact is connected to one end of the coil of the second relay, the other end of the coil of the second relay is connected to the power supply and the coil of the contactor, and the third normally open contact is connected in parallel with the first normally open contact; The first control circuit is used to control the coil of the contactor, the coil of the first relay and the coil of the second relay to be energized, and the first normally open contact, the second normally open contact and the third normally open contact to be closed when it is determined that the second control circuit is turned on.

3. The motor control circuit according to claim 2, characterized in that: The second control circuit includes a fourth normally open contact of the first relay and a first normally closed contact of the second relay, One end of the fourth normally open contact is connected to the coil of the contactor, the other end of the fourth normally open contact is connected to one end of the first normally closed contact, and the other end of the first normally closed contact is connected to the coil of the first relay and the coil of the contactor; The second control circuit is used to control the fourth normally open contact to close so that the coil of the contactor and the coil of the first relay are energized when it is determined that the power supply fails and the power supply failure time is less than the time threshold.

4. The motor control circuit according to claim 3, characterized in that: The first control circuit is also used to, when it is determined that the power failure occurs and the power failure time is less than the time threshold, if it is determined that the coil of the contactor and the coil of the first relay are energized, control the first normally open contact and the second normally open contact to close, and energize the coil of the second relay to open the first normally closed contact.

5. The motor control circuit according to claim 3, characterized in that: The first control circuit also includes a fifth normally open contact of the third relay and a second normally closed contact of the fourth relay, one end of the fifth normally open contact is connected to the first normally open contact, the other end of the fifth normally open contact is connected to one end of the second normally closed contact, and the other end of the second normally closed contact is connected to the coil of the contactor. The first control circuit is used to control the fifth normally open contact to be disconnected and the second normally closed contact to be disconnected when receiving a motor stop instruction, so as to stop the motor; The first control circuit is further configured to control the fourth normally open contact to close when receiving a motor operation instruction, so as to enable the motor to operate.

6. The motor control circuit according to claim 5, characterized in that: The first control circuit further includes a sixth normally open contact of the contactor, wherein the sixth normally open contact is connected in parallel with the fifth normally open contact. The first control circuit is used to control the sixth normally open contact to close and the second normally closed contact to open when receiving a motor stop instruction, so as to stop the motor; The first control circuit is further configured to control the sixth normally open contact to close when receiving a motor operation instruction, so as to enable the motor to operate.

7. The motor control circuit according to claim 5, characterized in that: The second control circuit also includes a seventh normally open contact of a fifth relay and a coil of the fifth relay, the seventh normally open contact is connected in parallel with the fifth normally open contact, one end of the coil of the fifth relay is connected to the first normally closed contact, and one end of the coil of the fifth relay is connected to the coil of the first relay, the coil of the second relay and the coil of the contactor, The second control circuit is used to control the third normally open contact to close and the coil of the fifth relay to be energized when it is determined that the power supply fails and the power supply failure time is less than the time threshold, so that the seventh normally open contact is closed and the coil of the contactor and the coil of the first relay are energized.

8. The motor control circuit according to claim 5, characterized in that: The first control circuit further includes a coil of a third relay and a coil of a fourth relay, the coil of the third relay is connected to the power supply, the coil of the second relay, the coil of the first relay and the coil of the contactor, and the coil of the fourth relay is connected in parallel with the coil of the third relay. The first control circuit is used for, when receiving a motor working instruction, energizing the coil of the third relay and closing the fifth normally open contact to start the motor running; The first control circuit is also used for, when receiving a motor stop command, de-energizing the coil of the third relay, energizing the coil of the fourth relay, disconnecting the fifth normally open contact, and disconnecting the second normally closed contact, so as to stop the motor.

9. The motor control circuit according to claim 8, characterized in that: The first relay is a time delay relay, and the third relay and the fourth relay are extension relays.

10. A protection device, characterized in that: The protection device comprises: a motor control circuit as described in any one of claims 1-9.

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