Elevator and control method thereof

Abstract

The application provides an elevator and a control method thereof, comprising a car; a traction machine connected to the car; a driving system comprising an electric motor driving rotation of the traction machine through a transmission shaft; a monitoring system for monitoring a rotation speed of the transmission shaft and an alternating current power supply current of the electric motor; and a speed control system for controlling the driving system to reduce the rotation speed when the alternating current power supply current is lower than a predetermined first current threshold and the rotation speed is higher than a predetermined speed threshold. When the driving system is out of control, the monitoring system, the driving system and the speed control system of the elevator can cooperate with each other to monitor and control the driving system to reduce the rotation speed of the transmission shaft, so that the traction machine drives the car to ascend or descend at a low speed, thereby preventing passengers in the car from being injured.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of elevators, and in particular to an elevator and a control method thereof. BACKGROUND

[0002] With the construction of high-rise buildings in China, elevators have been widely used. Among them, the application of traction elevators is the most widespread.

[0003] The traction elevator mainly sets the steel wire rope on the traction machine, one end of the steel wire rope is used to suspend the car carrying passengers, and the other end of the steel wire rope is used to suspend the counterweight. When the traction machine starts, the friction between the traction machine and the steel wire rope will generate traction force, so as to make the car and the counterweight move relatively. That is, the car rises and the counterweight descends; the counterweight rises and the car descends.

[0004] However, when the drive system of the elevator loses control (for example, when the elevator loses power), the drive shaft of the drive system will rotate at a high speed out of control, thereby driving the traction machine to rotate at a high speed out of control, and the high-speed rotation of the traction machine will drive the car to rise or descend at a high speed until the car runs to the terminal of the shaft and collides, causing the passengers in the car to be injured.

[0005] Therefore, it is urgent to provide an improved elevator and a control method thereof to overcome the problem that when the drive system of the elevator loses control, the drive shaft rotates at a high speed out of control. SUMMARY

[0006] The present application aims to provide an elevator and a control method thereof, which can solve the above technical problems.

[0007] According to one aspect of the present application, an elevator is provided, comprising: a car 1; a traction machine 2 connected to the car 1; a drive system comprising an electric motor driving rotation of the traction machine 2 through a drive shaft 3; a monitoring system for monitoring a rotation speed of the drive shaft 3 and an alternating current power supply to the electric motor by an elevator control system; and a speed control system controlling the drive system to reduce the rotation speed in a case where the alternating current power supply current is lower than a predetermined first current threshold and the rotation speed is higher than a predetermined speed threshold.

[0008] Preferably, the speed control system comprises: a direct current power supply 5 connected in series with the electric motor 4; an Insulated Gate Bipolar Transistor (IGBT) 6 connected in series with the direct current power supply 5; and a controller 7 controlling a direct current power supply of the direct current power supply 5 in a case where the alternating current power supply current is lower than the predetermined first current threshold and the rotation speed is higher than the predetermined speed threshold.

[0009] Preferably,

[0010] wherein I is the DC supply current, T is the torque required to drive the elevator and its load, R is the equivalent resistance of the impedance of the motor at a certain rotational speed, η is the efficiency of the gearbox of the elevator, and i is the gear ratio of the gearbox.

[0011] Preferably,

[0012] wherein I is the DC supply current, η is the efficiency of the gearbox of the elevator, i is the gear ratio of the gearbox, K e is the torque constant of the motor, is the magnetic flux, is the power factor of the rotor winding, D1 is the diameter of the traction sheave, m j is the mass of the car, m d is the mass of the counterweight of the elevator, g is the gravitational constant, m is the mass of the vertical moving parts of the elevator, a is the deceleration of the elevator, r1 is the stator resistance, r2 is the rotor resistance, s is the slip, f is the rotational speed, x1 is the stator reactance, and x2 is the rotor reactance.

[0013] Preferably, the speed control system further comprises a battery 8 connected in series with the motor 4 and in parallel with the DC power supply 5, the monitoring system is further configured to monitor the DC supply of the DC power supply 5, and the controller 7 is further configured to control the DC supply of the battery 8 if the DC supply current is below a predetermined second current threshold.

[0014] Preferably, the speed control system further comprises an AC contactor 9 connected in series with the motor 4, the controller 7 is further configured to control the operation of the AC contactor 9 according to the magnitude of the AC supply current in the following manner: if the AC supply current reaches 70% of a first current threshold, the connection of the AC contactor 9 is maintained; if the AC supply current is between 30% and 70% of the first current threshold for a predetermined time threshold, the connection of the AC contactor 9 is disconnected after a certain time and the DC supply of the DC power supply 5 is controlled; and if the AC supply current does not reach 30% of the predetermined first current threshold, the connection of the AC contactor 9 is immediately disconnected and the DC supply of the battery 8 is controlled.

[0015] Preferably, the monitoring system comprises a first current sensor 10 connected in parallel with the motor 4 for monitoring the AC supply current, a second current sensor 11 connected in series with the DC power supply 5 for monitoring the DC supply current, and a rotational speed sensor 12 provided on the drive shaft 3 or the motor for monitoring the displacement and running speed of the elevator car.

[0016] According to another aspect of the present application, there is provided a control method of an elevator, comprising: driving a motor in a driving system to drive a rotation of a hoisting machine 2 through a transmission shaft 3; monitoring a rotation speed of the transmission shaft 3 and an alternating current supply current of the motor by a monitoring system; controlling the driving system to reduce the rotation speed by a speed control system in case that the alternating current supply current is lower than a predetermined first current threshold and the rotation speed is higher than a set speed threshold.

[0017] Preferably, the speed control system controls the driving system to reduce the rotation speed in case that the alternating current supply current is lower than a predetermined first current threshold and the rotation speed is higher than a predetermined speed threshold, comprising: the controller 7 controls the IGBT 6 to be controlled to be turned on, thereby controlling the direct current power supply 5 to provide a controllable direct current supply to the motor 4.

[0018] Preferably, the speed control system controls the driving system to reduce the rotation speed in case that the alternating current supply current is lower than a predetermined first current threshold and the rotation speed is higher than a predetermined speed threshold, further comprising: the monitoring system monitors a direct current supply current of the direct current power supply 5; the controller 7 controls the battery 8 to provide a direct current supply to the motor 4 in case that the direct current supply current is lower than a predetermined second current threshold.

[0019] Preferably, the speed control system controls the driving system to reduce the rotation speed in case that the alternating current supply current is lower than a predetermined first current threshold and the rotation speed is higher than a predetermined speed threshold, further comprising: the controller 7 further controls the alternating current contactor 9 to be operated according to the alternating current supply current in the following manner: the connection of the alternating current contactor 9 is maintained in case that the alternating current supply current reaches 70% of the predetermined first current threshold; the connection of the alternating current contactor 9 is disconnected after a certain time and the direct current supply of the direct current power supply 5 is controlled in case that the alternating current supply current is between 30%-70% of the predetermined first current threshold for a predetermined time threshold; the connection of the alternating current contactor 9 is immediately disconnected and the direct current supply of the battery 8 is controlled in case that the alternating current supply current does not reach 30% of the predetermined first current threshold.

[0020] In a conventional elevator, when the driving system is out of control, the transmission shaft will rotate at a high speed, thereby causing the hoisting machine to drive the car to ascend or descend at a high speed until the car hits the end of the shaft and the passengers in the car are injured. The present application provides an elevator and a control method thereof, the monitoring system, the driving system and the speed control system of the elevator can cooperate with each other to monitor and control the driving system to reduce the rotation speed of the transmission shaft, thereby causing the hoisting machine to drive the car to ascend or descend at a low speed and preventing the passengers in the car from being injured. BRIEF DESCRIPTION OF DRAWINGS

[0021] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the application. In the drawings:

[0022] Figure 1 A structural diagram of an elevator according to an embodiment of the present application is shown; and

[0023] Figure 2 A flow chart of a control method of an elevator according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0024] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0025] Reference will now be made in detail to various embodiments of the application, examples of which are illustrated in the accompanying drawings and described below. For the purpose of explanation and definition of the claimed application, the terms "upper", "lower", "inner" and "outer" are used to describe the features of the example embodiments shown in the figures with reference to their positions.

[0026] Figure 1 A structural diagram of an elevator according to an embodiment of the present application is shown.

[0027] As Figure 1 shown, according to an embodiment of the present application, the elevator comprises: a car 1; a hoisting machine 2 connected to the car 1; a drive system driving rotation of the hoisting machine 2 through a transmission shaft 3; a monitoring system monitoring rotational speed of the transmission shaft 3 and alternating current supply current of the motor; and a speed control system controlling the drive system to reduce the rotational speed in a case where the alternating current supply current is lower than a predetermined first current threshold and the rotational speed is higher than a predetermined speed threshold.

[0028] In a conventional elevator, when the drive system is out of control, the transmission shaft 3 thereof rotates at a high speed out of control, so that the hoisting machine 2 drives the car 1 to ascend or descend at a high speed until a collision occurs when the car 1 runs to the end of the shaft, causing passengers in the car 1 to be injured. The present application provides an elevator which is provided with a speed control system for controlling the drive system to reduce the rotational speed of the transmission shaft 3 in a case where the drive system is out of control, so that the hoisting machine 2 drives the car 1 to ascend or descend at a low speed. This has the advantage that passengers in the car 1 are prevented from being injured in a case where the drive system of the elevator is out of control.

[0029] According to an embodiment of the present application, the speed control system comprises: a direct current power supply 5 connected in series with the motor 4; an IGBT 6 connected in series with the direct current power supply 5; and a controller 7, which controls the direct current power supply of the direct current power supply 5 when the alternating current power supply current is lower than a predetermined first current threshold and the rotating speed is higher than a predetermined speed threshold.

[0030] When the drive system of a conventional elevator is out of control, the elevator system cannot make the drive shaft 3 of the drive system rotate at a low speed through self-regulation. The present application provides an elevator, whose speed control system comprises: a direct current power supply 5, which is used to provide direct current power supply to the motor 4 when the drive system is out of control. Specifically, the direct current power supply is transmitted to the stator coil of the motor 4 to generate a constant magnetic field, and at the same time, the magnetic lines of the constant magnetic field are cut by the rotor coil to generate eddy current, which further drives the drive shaft 3 of the motor 4 to rotate at a low speed, so that the hoisting machine 2 drives the car 1 to rise or descend at a low speed. Furthermore, the speed control system comprises an IGBT 6, which is used to instantaneously turn on the direct current power supply 5 to provide direct current power supply to the motor 4 when the drive system is out of control; and a controller 7, which controls the turning on of the IGBT 6 and the direct current power supply and power of the direct current power supply 5 when it judges that the drive system is out of control, and further controls the drive shaft 3 to rotate at a low speed. The advantage of this is that when the drive system is out of control, only the alternating current power supply of the motor 4 needs to be changed to direct current power supply, and the drive shaft 3 of the motor 4 can rotate at a low speed, which prevents the passengers in the car 1 from being injured in the case that the drive system of the elevator is out of control.

[0031] According to an embodiment of the present application,

[0032] wherein I is the direct current power supply current, T is the torque required for driving the elevator and its load, R is the equivalent resistance of the impedance of the motor at a certain rotating speed, η is the efficiency of the gearbox of the elevator, and i is the gear ratio of the gearbox.

[0033] According to an embodiment of the present application,

[0034] wherein I is the direct current power supply current, η is the efficiency of the gearbox of the elevator, i is the gear ratio of the gearbox, K e is the torque constant of the motor, is the magnetic flux, is the power factor of the rotor winding, D1 is the diameter of the traction sheave, m j is the mass of the car, m d is the mass of the counterweight of the elevator, g is the gravitational constant, m is the mass of the vertically moving parts of the elevator, a is the deceleration of the elevator, r1 is the stator resistance, r2 is the rotor resistance, s is the slip, f is the rotating speed, x1 is the stator reactance, and x2 is the rotor reactance.

[0035] The above embodiments describe in detail how the DC power supply 5 provides the DC supply current. The advantage of doing so is that in the event of a runaway drive system, the proper size of DC supply current is provided to prevent injury to passengers in the car 1.

[0036] According to embodiments of the present application, the speed control system of the elevator further comprises a battery 8 connected in series with the motor 4 and in parallel with the DC power supply 5; the monitoring system is further configured to monitor the DC supply current of the DC power supply 5; and the controller 7 is further configured to control the DC supply of the battery 8 in the event that the DC supply current is below a predetermined second current threshold.

[0037] In the event of a runaway drive system of the elevator (e.g. power outage of the elevator), the DC power supply 5 of the speed control system can also fail, and the drive shaft 3 of the drive system can still rotate at a high speed. Therefore, in embodiments of the present application, the monitoring system of the elevator is configured to monitor whether the DC supply of the DC power supply 5 is normal; further, the speed control system comprises a battery 8, which, in the event that the DC supply is abnormal, replaces the DC power supply 5 to provide the DC supply, thereby ensuring the stability of the speed control system and the safety of the elevator; further, when the controller 7 determines that the drive system of the elevator is runaway and the DC supply is abnormal, it can control the conduction of the IGBT 6 and the DC supply and power of the battery 8, thereby controlling the drive shaft 3 to rotate at a low speed. The advantage of doing so is that a backup power supply is provided for the DC power supply 5 of the speed control system, which on the one hand ensures the stability of the speed control system, and on the other hand reduces the probability of failure of the speed control system.

[0038] Of course, those skilled in the art should know that using the battery 8 as a backup DC supply is only an example of the present application, and any DC power source can replace the battery 8 to become a backup DC supply for the DC power supply 5.

[0039] According to embodiments of the present application, the speed control system further comprises an AC contactor 9 connected in series with the motor 4; the controller 7 is further configured to control the operation of the AC contactor 9 according to the size of the AC supply current in the following manner: in the event that the AC supply current reaches 70% of the predetermined first current threshold, the connection of the AC contactor 9 is maintained; in the event that the AC supply current reaches 30%-70% of the predetermined first current threshold for a predetermined time threshold, the connection of the AC contactor 9 is disconnected after a certain time and the DC supply of the DC power supply 5 is controlled; in the event that the AC supply current does not reach 30% of the predetermined first current threshold, the connection of the AC contactor 9 is immediately disconnected and the DC supply of the battery 8 is controlled.

[0040] When the drive system of the elevator is out of control, if the speed of cutting off the AC power supply is not controlled (i.e. the timing of the DC power supply of the DC power supply 5 is not controlled), the controller 7 will directly control the DC power supply 5 to provide the DC power supply to the motor 4 in the case of unstable AC power supply current, and the frequent connection of the DC power supply 5 will cause the circuit of the speed control system to age. The present application provides an elevator, and the speed control system of the elevator includes an AC contactor 9, and the controller 7 can select whether the AC contactor 9 is disconnected and the disconnection speed according to the size of the AC power supply current. For example, in the case of transient low voltage of the AC power supply, the timing of the constant speed disconnection of the AC contactor 9 can be between the generation and recovery of the transient low voltage of the AC power supply, and the connection of the AC contactor 9 is maintained, and the advantage of this is that, in the case of unstable voltage, the DC power supply 5 is prevented from being frequently connected to the drive system, which causes the circuit of the speed control system to age, and further improves the stability of the speed control system. On the other hand, if the AC power supply current is too low than the predetermined first current threshold, the power supply system including the AC power supply and the DC power supply is likely to be paralyzed, and therefore, in the case that the AC power supply current is 30% lower than the predetermined first current threshold, the controller 8 controls the DC power supply of the battery 8 to the motor 4, which ensures the safety of the passengers in the car 1.

[0041] Of course, those skilled in the art should know that the above-mentioned selection of whether the AC contactor 9 is disconnected and the disconnection speed according to the proportion between the AC power supply current and the predetermined first current threshold is only an example of the present application, and in actual application, those skilled in the art can flexibly adjust the above-mentioned proportion to select whether the AC contactor 9 is disconnected and the disconnection speed according to different types, different sizes, and different energy consumption of the elevator.

[0042] According to the embodiment of the present application, the monitoring system includes: a first current sensor 10 connected in parallel with the motor 4 for monitoring the AC power supply current; a second current sensor 11 connected in series with the DC power supply 5 for monitoring the DC power supply current; and a rotational speed sensor 12 arranged on the transmission shaft 3 for monitoring the rotational speed of the transmission shaft 3.

[0043] Before the drive system of the elevator loses control, a device for monitoring the drive system losing control and the abnormality of the DC power supply 5 needs to be set, otherwise the controller 7 cannot determine whether to control the drive system. The present application provides a monitoring system for an elevator, which comprises: a first current sensor 10 for monitoring whether the AC power supply current of the motor 4 is abnormal and sending a monitoring signal to the controller 7; a second current sensor 11 for monitoring whether the DC power supply current of the DC power supply 5 is abnormal and sending a monitoring signal to the controller 7; and a rotational speed sensor 12 for monitoring whether the rotational speed of the transmission shaft 3 is abnormal and sending a monitoring signal to the controller 7. The rotational speed sensor 12 can be replaced by a photoelectric sensor. Specifically, the monitoring system continuously monitors the rotational speed of the transmission shaft 3 and the AC power supply current for 24 hours, and sends monitoring signals of the drive system to the controller 7 uninterruptedly. At the same time, the monitoring system continuously monitors the DC power supply current of the DC power supply 5 for 24 hours, and sends monitoring signals of the speed control system to the controller 7 uninterruptedly. The setting of the monitoring system helps the controller 7 to discover the loss of control of the drive system and the abnormality of the DC power supply 5 in time, preventing the passengers in the car from being injured. According to the requirements of GB / T 7588.1-2020 on the safety components such as the safety gear of the elevator, the braking deceleration should not be greater than 1.0g.

[0044] Of course, those skilled in the art should know that the above-mentioned first current sensor, second current sensor and rotational speed sensor are only an example of the present application, and those skilled in the art can choose devices with the same function to replace them in actual application.

[0045] When the drive system of the elevator loses control, if the speed of cutting off the AC power supply is not controlled (i.e. the timing of the DC power supply 5 is controlled), it will cause the controller 7 to directly control the DC power supply 5 to provide DC power supply to the motor 4 when the rotational speed of the transmission shaft 3 is temporarily increased, and the direct connection of the DC power supply 5 may cause the circuit of the control system to be damaged or aged. The present application provides an elevator, and the speed control system of the elevator comprises an AC contactor 9, and the controller 7 can select whether to disconnect the AC contactor 9 and the timing of disconnection according to the rotational speed of the transmission shaft 3. For example, in the case of temporary high rotational speed, the timing of the constant speed disconnection of the AC contactor 9 can be between the moment when the temporary high rotational speed is generated and the moment when it is restored, and the connection of the AC contactor 9 is maintained. The advantage of this is that in the case of unstable rotational speed, the frequent connection of the DC power supply 5 to the drive system is prevented, which can cause the circuit of the speed control system to be damaged or aged, and further improves the stability of the speed control system. On the other hand, if the rotational speed deviates too much from the predetermined speed threshold, whether it is a temporary high rotational speed or not, the AC contactor 9 should be disconnected quickly, and the DC power supply 5 should be connected, to ensure the safety of the passengers in the car 1.

[0046] Of course, those skilled in the art should know that the above selection of whether the AC contactor 9 is disconnected and the disconnection speed according to the ratio between the rotation speed of the transmission shaft 3 and the predetermined speed threshold value is only an example of the present scheme, and in actual applications, those skilled in the art can flexibly adjust the above ratio to select whether the AC contactor 9 is disconnected and the disconnection speed according to different types, different sizes, and different energy consumption of elevators.

[0047] The main workflow of the embodiment is as follows:

[0048] When the motor 4 is out of control, the transmission shaft 3 rotates at a high speed, and then the hoisting machine 2 drives the car 1 to rise or descend at a high speed, causing the passengers in the car to be injured. The present application can control the AC contactor 9 to cut off the AC power supply of the motor 4 when the monitoring system detects that the drive system is out of control, and rapidly control the DC power supply 5 to provide DC power supply to the motor 4, so that the DC power supply is transmitted to the stator coil of the motor 4 to generate a constant magnetic field. At the same time, the magnetic lines of the constant magnetic field are cut by the rotor coil to generate eddy current, and the eddy current further drives the transmission shaft 3 of the motor 4 to rotate at a low speed, so that the hoisting machine 2 drives the car 1 to rise or descend at a low speed.

[0049] The present application also provides a control method of an elevator. Figure 2 The flow chart of the control method of the elevator according to the embodiment of the present application is shown, referring to Figure 2 The implementation steps of the specific implementation of the control method of the elevator are as follows:

[0050] Step S202: The motor in the drive system drives the rotation of the hoisting machine 2 through the transmission shaft 3;

[0051] Step S204: The monitoring system monitors the rotation speed of the transmission shaft 3 and the AC power supply current of the motor;

[0052] Step S206: In the case that the AC power supply current is lower than a predetermined first current threshold value and the rotation speed is higher than a predetermined speed threshold value, the speed control system controls the drive system to reduce the rotation speed.

[0053] In the conventional elevator, when the drive system is out of control, the transmission shaft 3 will rotate at a high speed, and then the hoisting machine 2 drives the car 1 to rise or descend rapidly, causing the passengers in the car 1 to be injured. The present application provides a control method of an elevator, which can control the drive system to reduce the rotation speed of the transmission shaft 3 when the monitoring system detects that the AC power supply current is lower than a predetermined first current threshold value and the rotation speed of the transmission shaft 3 is higher than a predetermined speed threshold value, so that the hoisting machine drives the car to rise or descend at a low speed. The advantage of this is that in the case that the drive system of the elevator is out of control, the passengers in the car 1 are prevented from being injured.

[0054] According to the embodiment of the present application, when the AC power supply current is lower than a predetermined first current threshold and the rotating speed is higher than a predetermined speed threshold, the speed control system controls the drive system to reduce the rotating speed, including: the controller 7 controls the IGBT 6 to be turned on, so as to control the DC power supply 5 to provide DC power supply to the motor 4.

[0055] When the drive system of the conventional elevator is out of control, the elevator system cannot make the drive shaft 3 of the drive system rotate at a low speed through self-regulation. The present application provides a control method of an elevator, when the AC power supply current is lower than a predetermined first current threshold and the rotating speed is higher than a predetermined speed threshold, the controller 7 controls the DC power supply 5 to provide DC power supply to the motor 4. Specifically, the DC power supply is transmitted to the stator coil of the motor 4 to generate a constant magnetic field, at the same time, the magnetic lines of the constant magnetic field are cut by the rotor coil to generate eddy current, which further drives the drive shaft 3 of the motor 4 to rotate at a low speed, so as to make the traction machine drive the car to rise or descend at a low speed. Furthermore, the speed control system includes the IGBT 6, which is used to turn on the DC power supply 5 instantaneously to provide DC power supply to the motor 4 when the drive system is out of control; furthermore, the controller 7 can further control the DC power supply and power of the DC power supply 5 to make the drive shaft 3 rotate at a low speed. The advantage of this is that when the drive system is out of control, only the AC power supply of the motor 4 needs to be changed to DC power supply, and the drive shaft 3 of the motor 4 can rotate at a low speed, which prevents the passengers in the car from being injured when the drive system of the elevator is out of control.

[0056] Of course, those skilled in the art should know that the present application does not limit the connection mode, and all connection modes that can achieve the above power supply function and the same function substitutes of the above device are within the protection scope of the present application.

[0057] According to the embodiment of the present application, when the AC power supply current is lower than a predetermined first current threshold and the rotating speed is higher than a predetermined speed threshold, the speed control system controls the drive system to reduce the rotating speed, including: the controller 7 controls the IGBT 6 to be turned on, so as to control the DC power supply 5 to provide DC power supply to the motor 4.

[0058] When the drive system of the elevator is out of control (for example, when the elevator is powered off), the DC power supply 5 of the speed control system can also fail, and the drive shaft 3 of the drive system can still rotate at a high speed. Therefore, the present application provides a control method for an elevator, wherein a monitoring system of the elevator is used to monitor whether the DC power supply 5 is normal; further, when the DC power supply 5 is abnormal, the battery 8 is used to replace the DC power supply 5 to provide DC power supply, so as to ensure the stability of the speed control system and the safety of the elevator; further, the controller 7 can further control the DC power supply and power of the battery 8, and control the drive shaft 3 to rotate at a low speed. The advantage of this is that the DC power supply 5 of the speed control system is provided with a backup DC power supply, which can ensure the stability of the speed control system and reduce the probability of failure of the speed control system.

[0059] Of course, those skilled in the art should know that the present application does not limit the connection mode, and all connection modes that can realize the above-mentioned backup power supply function are within the protection scope of the present application. In addition, the battery 8 is only an example of the present application, and all DC power sources can replace the battery 8 to become the backup DC power supply of the DC power supply 5.

[0060] According to the embodiment of the present application, when the AC power supply current is lower than the predetermined first current threshold and the rotation speed is higher than the predetermined speed threshold, the speed control system controls the drive system to reduce the rotation speed, and further comprising: the controller 7 further controls the action of the AC contactor 9 according to the size of the AC power supply current in the following manner: when the AC power supply current reaches 70% of the predetermined first current threshold, the connection of the AC contactor 9 is maintained; when the AC power supply current is between 30%-70% of the predetermined first current threshold for a predetermined time threshold, the connection of the AC contactor 9 is disconnected after a certain time and the DC power supply of the DC power supply 5 is controlled; when the AC power supply current does not reach 30% of the predetermined first current threshold, the connection of the AC contactor 9 is immediately disconnected and the DC power supply of the battery 8 is controlled.

[0061] When the drive system of the elevator is out of control, if the speed of cutting off the AC power supply is not controlled (i.e. the timing of the DC power supply of the DC power supply 5 is not controlled), the controller 7 will control the DC power supply 5 to provide the DC power supply to the motor 4 in the case of unstable AC power supply current, and the frequent connection of the DC power supply 5 will cause the circuit of the speed control system to be damaged or aged. The present application provides a control method of an elevator, the speed control system of the elevator includes an AC contactor 9, and the controller 7 can select whether the AC contactor 9 is disconnected and the disconnection speed according to the size of the AC power supply current. For example, in the case of transient low voltage of AC power supply, the timing of the constant speed disconnection of the AC contactor 9 can be between the generation and recovery of the transient low voltage of AC power supply, and the connection of the AC contactor 9 is maintained, which has the advantage that in the case of unstable voltage, the DC power supply 5 is prevented from being frequently connected to the drive system, which causes the circuit of the speed control system to be aged, and further improves the stability of the speed control system. On the other hand, if the AC power supply current is too low below the predetermined first current threshold, the power supply system including the AC power supply and the DC power supply is likely to be paralyzed, so in the case that the AC power supply current is 30% lower than the predetermined first current threshold, the controller 8 controls the DC power supply to provide the DC power supply to the motor 4, which ensures the safety of the passengers in the car 1.

[0062] Of course, those skilled in the art should know that the above selection of whether the AC contactor 9 is disconnected and the disconnection speed according to the ratio between the AC power supply current and the predetermined first current threshold is only an example of the present scheme, and in actual application, those skilled in the art can flexibly adjust the above ratio to select whether the AC contactor 9 is disconnected and the disconnection speed according to different types, different sizes, and different energy consumption of elevators.

[0063] In a conventional elevator, when the drive system is out of control, the transmission shaft will rotate at a high speed, so that the traction machine drives the car to rise or descend rapidly until the car collides with the terminal of the shaft, causing the passengers in the car to be injured. The present application provides an elevator and a control method thereof, the monitoring system, the drive system, and the speed control system of the elevator can cooperate with each other to monitor and control the transmission shaft of the drive system to rotate at a low speed, so that the traction machine drives the car to rise or descend at a low speed, preventing the passengers in the car from being injured.

[0064] It has to be noted that, in the present document, the terms "first", "second", etc. merely serve the purpose of differentiation and do not require or imply any kind of ordering or sequence of the entities or actions associated therewith. Furthermore, the terms "comprising", "containing", or any other similar term are intended to encompass non-exclusive inclusions, such that processes, methods, articles, or apparatuses that comprise a list of elements are not limited to those elements, but can include other elements not expressly listed or inherent to such processes, methods, articles, or apparatuses.

[0065] The above description is merely that of preferred embodiments of the application, and is not intended to limit the application. The application can be modified and varied greatly without departing from the spirit of the application. Accordingly, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application shall be included in the scope of the application.

Claims

1. An elevator, characterized in that, include: Car (1); Traction machine (2), connected to the car (1); The drive system includes an electric motor (4) that drives the rotation of the traction machine (2) via a transmission shaft (3); A monitoring system is used to monitor the rotational speed of the drive shaft (3) and the AC power supply current of the motor; as well as The speed control system controls the drive system to reduce the rotational speed when the AC power supply current is lower than a predetermined first current threshold and the rotational speed is higher than a predetermined speed threshold. The speed control system includes: A DC power supply (5) is connected in series with the motor (4); An insulated-gate bipolar transistor (IGBT) (6) is connected in series with the DC power supply (5); and The controller (7) controls the DC power supply current of the DC power supply (5) when the AC power supply current is lower than a predetermined first current threshold and the rotation speed is higher than a predetermined speed threshold. in, ， Wherein, I is the DC power supply current, T is the torque required to drive the elevator and its load, R is the equivalent resistance of the motor impedance at a specific speed, η is the efficiency of the elevator gearbox, and i is the gear ratio of the gearbox.

2. The elevator according to claim 1, characterized in that, ， Where I is the DC power supply current, Let be the efficiency of the elevator's gearbox, and i be the gear ratio of the gearbox. Let be the torque constant of the motor. For magnetic flux, The power factor of the rotor winding. The diameter of the traction sheave is [missing information]. The mass of the car, Let be the mass of the elevator's counterweight. It is the gravitational constant. Let the mass be the mass of the vertical moving component of the elevator. Let deceleration be the speed at which the elevator decelerates. For stator resistance, Where is the rotor resistance and s is the slip. The rotational speed, For stator resistance, This is the rotor inductive reactance.

3. The elevator according to claim 1, characterized in that, The speed control system also includes: The storage battery (8) is connected in series with the motor (4) and in parallel with the DC power supply (5); The monitoring system is also used to monitor the DC power supply current of the DC power supply (5); and The controller (7) also controls the DC power supply of the battery (8) when the DC power supply current is lower than a predetermined second current threshold.

4. The elevator according to claim 3, characterized in that, The speed control system also includes: An AC contactor (9) is connected in series with the motor (4); The controller (7) also controls the operation of the AC contactor (9) according to the magnitude of the AC power supply current in the following manner: If the AC power supply current reaches 70% of the predetermined first current threshold, the AC contactor (9) remains connected; When the AC power supply current is between 30% and 70% of the predetermined first current threshold and reaches a predetermined time threshold, the AC contactor (9) is disconnected after a specific time and the DC power supply (5) is controlled. If the AC power supply current does not reach the predetermined first current threshold of 30%, the AC contactor (9) is immediately disconnected and the DC power supply of the battery (8) is controlled.

5. The elevator according to any one of claims 1 to 4, characterized in that, The monitoring system includes: The first current sensor (10) is connected in parallel with the motor (4) and is used to monitor the AC power supply current; A second current sensor (11), connected in series with the DC power supply (5), is used to monitor the DC power supply current; and A speed sensor (12) is installed on the drive shaft (3) or the motor to monitor the rotational speed of the drive shaft (3).

6. A control method for an elevator applied to any one of claims 1 to 5, characterized in that, include: The electric motor (4) in the drive system drives the rotation of the traction machine (2) through the transmission shaft (3); The monitoring system monitors the rotational speed of the drive shaft (3) and the AC power supply current of the motor; When the AC power supply current is lower than a predetermined first current threshold and the rotational speed is higher than a predetermined speed threshold, the speed control system controls the drive system to reduce the rotational speed, which includes: the controller (7) controls the diode to turn on, thereby controlling the DC power supply (5) to provide DC power to the motor (4).

7. The elevator control method according to claim 6, characterized in that, When the AC power supply current is lower than a predetermined first current threshold and the rotational speed is higher than a predetermined speed threshold, the speed control system controls the drive system to reduce the rotational speed, and further includes: The monitoring system monitors the DC power supply current of the DC power supply (5); When the DC power supply current is lower than a predetermined second current threshold, the controller (7) controls the battery (8) to provide DC power to the motor (4).

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