Elevator system based on permanent magnet synchronous motor

Abstract

This solution relates to the field of motor control, specifically disclosing a lifting elevator system based on a permanent magnet synchronous motor, including a car and an elevator drive system. The elevator drive system includes a mounting beam, which is fixedly installed on the inner wall of the elevator shaft. A permanent magnet synchronous motor is fixedly connected to the upper end of the mounting beam. The car is placed inside the elevator shaft, where a magnetic suspension track is installed. Magnetic columns that cooperate with the magnetic suspension track are installed on the outer wall of the elevator. Electromagnetic units are installed inside the magnetic suspension track, and these electromagnetic units are arranged in segments within the track. The electromagnetic units are positioned at the elevator's stopping point on each floor of the building. When used in an elevator upgrade system, this design makes the elevator operation smoother and safer.

Description

Technical Field

[0001] This invention belongs to the field of motor control, specifically relating to an elevator system based on a permanent magnet synchronous motor. Background Technology

[0002] Elevators are widely used for vertical transportation in high-rise buildings. After a long period of development, elevators are now mainly divided into those with machine rooms and those without. Generally, elevators with machine rooms use three-phase asynchronous motors as their driving force. Due to the high speed and high load capacity of three-phase asynchronous motors, they were once the mainstream choice for elevators. However, speed control of three-phase asynchronous motors is a major challenge. Current solutions use a combination of reduction gearboxes and frequency converters. However, this method requires a separate machine room at the top of the building, housing the motor, reduction gearbox, and control cabinet. When using an elevator system with a machine room, the space for the machine room needs to be reserved during building construction. The presence of the machine room causes the top floor of the building to protrude from the elevator shaft. For buildings with pre-reserved space, this extra portion increases construction costs and hinders the usability of the top floor. For super high-rise buildings, multi-section elevator systems are needed. The machine room in the middle section will temporarily occupy indoor space and require special protective measures.

[0003] A machine-room-less elevator system has emerged, such as the authorization announcement dated July 8, 2015, publication number CN204454181U, "An Elevator Without a Machine Room," which discloses that the traction machine is installed at the top of the elevator shaft, and a machine support beam is installed below the traction machine and fixed horizontally in the elevator shaft wall. The machine support beam is used to support the traction machine, and a bracket is installed at the top of the car guide rail, with a speed limiter fixed on the bracket.

[0004] According to the patent description, by installing a machine support beam inside the shaft wall and placing the traction machine on it, the machine room can be eliminated. However, this application does not specify the type of motor used for the traction machine. Based on the design, it is assumed that the motor eliminates the need for a reduction gearbox and control cabinet. Currently, the most commonly used type of motor is the permanent magnet synchronous motor (PMSM). PMSMs are widely used in elevator drive systems due to their simple control, high efficiency, good torque characteristics, and low losses. However, PMSMs are nonlinear, multivariable, and strongly coupled systems, susceptible to uncertain external disturbances. The application environment for PMSMs is often complex, frequently encountering various interferences. Especially at low speeds, PMSMs exhibit vibration. If this vibration is excessive, it can cause irregular motor speed or even loss of control, posing a serious safety hazard if it occurs during elevator operation. Summary of the Invention

[0005] The problem this application aims to solve is to provide a lifting elevator system based on a permanent magnet synchronous motor, in order to address the high risk of safety accidents associated with current elevators driven by permanent magnet synchronous motors.

[0006] To address the aforementioned problems, this invention provides a lifting elevator system based on a permanent magnet synchronous motor, comprising: a car and an elevator traction system. The elevator traction system includes a mounting beam fixedly installed on the inner wall of the elevator shaft. A permanent magnet synchronous motor is fixedly connected to the upper end of the mounting beam. A cable reel is coaxially connected to the output shaft of the permanent magnet synchronous motor, and a steel rope is wound on the cable reel. The car is suspended on the steel rope via a pulley system, and the car moves by being dragged by the steel rope. The car is placed inside the elevator shaft, and a magnetic suspension track is installed inside the elevator shaft. Magnetic columns that cooperate with the magnetic suspension track are installed on the outer wall of the elevator. Electromagnetic units are installed inside the magnetic suspension track, and the electromagnetic units are arranged in segments within the magnetic suspension track, positioned at the location where the elevator stops on each floor of the building.

[0007] The working principle of the above scheme is as follows: The permanent magnet synchronous motor uses a single permanent electromagnet to provide excitation, which makes the motor structure relatively simple. It can still be installed in a narrow elevator shaft without the need for a separate machine room. An installation beam is set on the side wall of the elevator shaft, and the motor is placed on the top of the installation beam. The elevator movement is first powered by the permanent magnet synchronous motor, and the steel cable is used as the medium for power transmission. The elevator can rise by contracting the length of the steel cable and descend by releasing the steel cable.

[0008] A magnetic levitation track is installed in the elevator shaft, and magnetic columns are mounted on the outer wall of the elevator. These magnetic columns are fitted with gaps within the magnetic levitation track, and individual electromagnets are installed within the track in segments. These electromagnets are positioned at the elevator's stopping point on each floor of the building. This structure has the following advantages:

[0009] First, when there is no stop in the middle of the elevator, the elevator rises and falls at the set speed driven by the permanent magnet motor. If the speed does not exceed the set speed, the individual electromagnets are not energized, the electromagnets have no magnetic force, and the elevator rises and falls normally.

[0010] Secondly, in extreme cases where the ascent and descent speeds reach abnormal speeds and the permanent magnet synchronous motor also malfunctions, this solution will immediately energize the individual electromagnets that have not yet reached the floor. When the elevator reaches the floor with the energized electromagnet, the electromagnet on that floor and the magnetic column on the outer wall of the elevator attract each other, which can help the elevator slow down and eventually stop at the door of a certain floor to facilitate rescue work.

[0011] Third, when the elevator is about to stop at or depart from a certain floor, the permanent magnet synchronous motor experiences vibration at low speeds. If it gradually stops at a certain floor, the electromagnet of that floor is energized. At this time, the electromagnet of that floor attracts the magnetic column, and together with the decrease in speed of the permanent magnet synchronous motor, it slows down the elevator's movement. At the same time, due to the magnetic attraction, the magnetic force will counteract part of the elevator's gravity, reducing the load driven by the permanent magnet synchronous motor and effectively alleviating the low-speed vibration of the permanent magnet synchronous motor.

[0012] Fourth, when the elevator starts at a certain floor, the electromagnet located near the top of the magnetic column on that floor can be energized first, so that the electromagnet exerts an upward pulling force on the magnetic column. When the magnetic column is directly facing the electromagnet, the electromagnet at that point will be immediately disconnected, and the next electromagnet will be energized, thus maintaining the pulling force. The whole process is similar to the operation of a maglev train. However, since the electromagnet is not used as a power source, but only to counteract the weight of the elevator, the permanent magnet synchronous motor can operate under low load or no load conditions, which can avoid the vibration problem that occurs in the permanent magnet synchronous motor at low speed.

[0013] As a preferred embodiment, the magnetic levitation track is a C-shaped track, and the magnetic columns are cylindrical, with gaps fitting within the C-shaped track. By setting the magnetic levitation track as a C-shaped track, the magnetic lines of force of the electromagnets attached to the C-shaped track are more concentrated at the geometric center of the track. The magnetic column body can be accommodated inside the track cavity, and the magnetic column is connected to the car through an opening in the C-shaped track using a strong and resilient material.

[0014] As a preferred embodiment, the magnetic columns are fixedly connected to the outer wall of the elevator car via a frame assembly, which is composed of multiple steel trusses. The magnetic columns are vertically installed at the four corners of the elevator's outer wall. The steel trusses have tensile and compressive strength characteristics. Through the truss connection, even if the magnetic columns act as fulcrums, they can fully support the car and meet the stress requirements for sudden stops during car operation.

[0015] As a preferred solution, the individual electromagnets installed in the magnetic levitation track from the first floor to the bottom and from the top floor to the top of the elevator shaft are arranged continuously and extend to both ends of the magnetic levitation track. To cope with situations where the elevator falls to the bottom or overshoots the top, normally the elevator will fall a maximum of two floors before stopping at the corresponding floor door. However, for subsequent safety, the individual electromagnets from the first floor to the bottom of the elevator shaft are arranged continuously. When each floor above the second floor is decelerated accordingly, the deceleration is continued at the bottom floor until it stops. This way, the elevator will not contact the bottom and will not stop too quickly, causing a sudden impact that could injure trapped personnel.

[0016] Furthermore, a magnetizer is installed on the side wall of the elevator shaft for magnetizing the individual electromagnets and the magnetic column. The magnetizer is connected to the individual electromagnets separately by a cable. The magnetizer mainly magnetizes the magnetic column to make it a permanent magnet, while the individual electromagnets generate magnetic force by directly energizing the magnetizer.

[0017] Furthermore, a magnetizing contact is installed on the inner wall of the magnetic levitation track corresponding to the first floor where the magnetic column is suspended. The magnetic column is equipped with a magnetizing contact point. When the magnetic column is suspended on the first floor, the magnetizing contact connects with the magnetizing contact point, and the magnetizing contact is connected to the magnetizer via a cable. The purpose of this design is to ensure that the magnetic column is magnetized only on the first floor. This allows the magnetizer to be located on the bottom floor for easy maintenance, and since the elevator spends the most time on the first floor, the magnetic column can be replenished with magnetization in a timely manner.

[0018] Furthermore, a buffer is installed at the very bottom of the magnetic levitation track, perpendicular to the magnetic column. This buffer further prevents the car from hitting the bottom; however, in this case, the magnetic column contacts the buffer to prevent bottoming out, eliminating the need for a separate buffer at the bottom of the elevator shaft.

[0019] Furthermore, to ensure a stable speed output from the permanent magnet synchronous motor, a controller is provided. This controller extends out of the elevator shaft via a control cable, possesses computer processing capabilities, and communicates with the permanent magnet synchronous motor. The controller comprises a nonlinear differential tracker, an extended observer, and a fractional-order proportional-integral-differential controller. The nonlinear differential tracker tracks the signal; the extended observer observes the internal state of the system and estimates unpredictable states; and the fractional-order proportional-integral-differential controller nonlinearly combines the outputs of the nonlinear differential tracker and the extended observer to provide a stable output signal.

[0020] Furthermore, to avoid sudden changes in output speed or overshoot caused by abrupt changes in the set speed value, a nonlinear differential tracker is incorporated with a nonlinear function. The nonlinear differential tracker satisfies the following expression:

[0021]

[0022] In the formula: v(t) is the input signal; h is the integration step size; r is the tracking factor; fhan is a nonlinear function; the nonlinear function fhan includes a sign function to mitigate output jumps and overshoot caused by sudden changes in the setpoint, and the relationship between the sign function and the nonlinear function satisfies the following logical expression:

[0023]

[0024] Furthermore, to eliminate the jitter that occurs at the origin and segment points of the controlled permanent magnet synchronous motor, the extended observer modifies the transition of the optimal control function at the origin and segment points of the permanent magnet motor. The optimal control function performs transition processing at the origin and segment points. Firstly, the extended observer satisfies the following expression:

[0025]

[0026] Where f nal The expression for (e, α, δ) is:

[0027]

[0028] In the above expression, ω is the input signal; e is the observation error; Z1 is the tracking signal of the input signal; Z2 is the differential signal of the input signal; Z3 is the observed signal of the system disturbance; α1, α2, α3 are tracking factors; δ is the filtering factor; β1, β2, β3 are the extended observer output error correction gain; b0 is the compensation factor; u is the system output; f nal (e, α, δ) is the optimal control function. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the layout structure of the elevator system in Example 1;

[0030] Figure 2 for Figure 1 A top-view structural diagram;

[0031] Figure 3 This is a schematic diagram of the layout of the magnetic suspension track in an elevator system.

[0032] Figure 4 for Figure 3 A schematic diagram of the structure of the elevator system from the first floor to the lowest point;

[0033] Figure 5 This is a control principle diagram of a permanent magnet synchronous motor in an elevator system.

[0034] Figure 6 Based on Figure 5 Speed ​​curve of a permanent magnet synchronous motor based on control principle.

[0035] Explanation of the reference numerals in the instruction manual: 1. Elevator shaft; 2. Permanent magnet synchronous motor; 3. Mounting beam; 4. Counterweight; 5. Car; 6. Magnetic suspension track; 7. Magnetic column; 8. Frame; 9. Electromagnet unit; 10. Magnetizing contact; 11. Magnetizer; 12. Cable. Detailed Implementation

[0036] The following detailed explanation illustrates the specific implementation methods:

[0037] Example 1:

[0038] like Figure 1 , Figure 2 , Figure 3 and Figure 4 The elevator system shown is based on a permanent magnet synchronous motor and includes a car 5 and an elevator drive system. The elevator drive system includes a mounting beam 3, which is fixedly installed on the inner wall of the elevator shaft 1. A permanent magnet synchronous motor 2 is fixedly connected to the upper end of the mounting beam 3. A cable reel is coaxially connected to the output shaft of the permanent magnet synchronous motor 2. A steel rope is wound on the cable reel. The car is suspended on the steel rope through a pulley system. A counterweight 4 is matched to the other end of the steel rope. The winding and releasing of the steel rope realizes the rising and falling of the car 5. The car 5 is placed in the elevator shaft 1. A magnetic suspension track 6 is installed in the elevator shaft 1. Magnetic columns 7 that cooperate with the magnetic suspension track are installed on the outer wall of the elevator. Electromagnetic units 9 are installed in the magnetic suspension track 6. The electromagnet units 9 are arranged in segments in the magnetic suspension track 6. The electromagnet units 9 are arranged at the position where the elevator stops at each floor of the elevator shaft 1.

[0039] The magnetic levitation track 6 is a C-shaped track, and the magnetic column 7 is cylindrical, with the magnetic column 7 fitting loosely within the C-shaped track. By setting the magnetic levitation track 6 as a C-shaped track, the magnetic lines of force of the electromagnets attached to the C-shaped track are more concentrated at the geometric center of the magnetic levitation track 6. The magnetic column 7 can be accommodated inside the track cavity, and the magnetic column 7 passes through the opening of the C-shaped track.

[0040] The magnetic columns 7 are fixedly connected to the outer wall of the car 5 via the frame 8. The magnetic columns 7 are connected to the car 5 using a high-strength and high-toughness material. The frame 8 is assembled from multiple steel trusses, but high-strength carbon fiber or titanium alloy can also be used as the frame material. The magnetic columns 7 are vertically installed at the four corners of the elevator's outer wall. The trusses have tensile and compressive strength characteristics. Through the truss connection, even if the magnetic columns 7 act as fulcrums, they can fully support the car 5 and meet the stress requirements for sudden stopping of the car 5 during operation.

[0041] In the magnetic levitation track 6 from the first floor to the bottom and from the top floor to the top of elevator shaft 1, the installed electromagnet units 9 are arranged continuously and extend to both ends of the magnetic levitation track 6. To cope with situations where the elevator falls to the bottom or overshoots the top, under normal circumstances, the elevator will fall a maximum of two floors before stopping at the corresponding floor door. However, for subsequent safety, the electromagnet units from the first floor to the bottom of elevator shaft 1 are arranged continuously. When each floor above the second floor is decelerated accordingly, the deceleration is continued at the bottom floor until it stops. In this way, the car 5 will not contact the bottom, nor will it stop too quickly, resulting in a sudden impact that could injure the trapped personnel.

[0042] A magnetizer 11 is installed on the side wall of elevator shaft 1 to magnetize electromagnet unit 9 and magnetic column 7. The magnetizer 11 is connected to electromagnet unit 9 separately by cable 12. The magnetizer 11 is mainly used to magnetize magnetic column 7 to make it a permanent magnet. Electromagnet unit 9 is directly energized by magnetizer 11 to generate magnetic force.

[0043] A magnetizing contact is installed on the inner wall of the magnetic levitation track corresponding to the first floor, with a magnetizing contact point 10 on the magnetic column. When the magnetic column 7 is suspended on the first floor, the magnetizing contact connects with the magnetizing contact point 10, and the magnetizing contact is connected to the magnetizer via a cable. The purpose of this design is to ensure that the magnetic column 7 is magnetized only on the first floor, so that the magnetizer 11 can be located on the bottom floor for easy maintenance. Since the car 5 spends the most time on the first floor, the magnetic column 7 can be remagnetized in a timely manner.

[0044] At the very bottom of the magnetic levitation track 6, a buffer is installed perpendicularly to the magnetic column 7. This buffer further prevents the car from hitting the bottom; however, in this case, the magnetic column contacts the buffer to prevent this, eliminating the need for a separate buffer at the bottom of the elevator shaft.

[0045] Example 2:

[0046] like Figures 1-4 As shown in the figure, this embodiment illustrates how an elevator system responds to four different situations, and the response methods are as follows:

[0047] First, when there is no stop in the middle of the elevator, the elevator rises and falls at the set speed driven by the permanent magnet motor. If the speed does not exceed the set speed, the individual electromagnets are not energized, the electromagnets have no magnetic force, and the elevator rises and falls normally.

[0048] Secondly, in extreme cases where the ascent and descent speeds reach abnormal speeds and the permanent magnet synchronous motor also malfunctions, this solution will immediately energize the individual electromagnets that have not yet reached the floor. When the elevator reaches the floor with the energized electromagnet, the electromagnet on that floor and the magnetic column on the outer wall of the elevator attract each other, which can help the elevator slow down and eventually stop at the door of a certain floor to facilitate rescue work.

[0049] Third, when the elevator is about to stop at or depart from a certain floor, the permanent magnet synchronous motor experiences vibration at low speeds. If it gradually stops at a certain floor, the electromagnet of that floor is energized. At this time, the electromagnet of that floor attracts the magnetic column, and together with the decrease in speed of the permanent magnet synchronous motor, it slows down the elevator's movement. At the same time, due to the magnetic attraction, the magnetic force will counteract part of the elevator's gravity, reducing the load driven by the permanent magnet synchronous motor and effectively alleviating the low-speed vibration of the permanent magnet synchronous motor.

[0050] Fourth, when the elevator starts at a certain floor, the electromagnet located near the top of the magnetic column on that floor can be energized first, so that the electromagnet exerts an upward pulling force on the magnetic column. When the magnetic column is directly facing the electromagnet, the electromagnet at that point will be immediately disconnected, and the next electromagnet will be energized, thus maintaining the pulling force. The whole process is similar to the operation of a maglev train. However, since the electromagnet is not used as a power source, but only to counteract the weight of the elevator, the permanent magnet synchronous motor can operate under low load or no load conditions, which can avoid the vibration problem that occurs in the permanent magnet synchronous motor at low speed.

[0051] Example 3:

[0052] like Figure 5 As shown, a controller is specially set up for the operation of the permanent magnet synchronous motor (PMSM). The controller extends out of the elevator shaft through a control cable. The controller has computer processing capabilities and communicates with the permanent magnet synchronous motor. The controller consists of a nonlinear differential tracker (TD), an extended observer (ESO), and a fractional proportional-integral-differential controller (FOPID).

[0053] The aforementioned nonlinear differential tracker TD is used to track signals; its function is to obtain a smooth input signal by processing the difference between the reference signal and the output signal through the nonlinear function in the active disturbance rejection control.

[0054] Extended observers (ESOs) are used to observe the internal state of a system and to estimate the unpredictable state of the system.

[0055] The fractional-order proportional-integral-derivative (FOPID) controller is used to nonlinearly combine the outputs of the nonlinear differential tracker (TD) and the extended observer (ESO) to provide a stable output signal.

[0056] The nonlinear differential tracker TD utilizes the tracking and filtering characteristics of the input signal and implements the transient process through the sign function, thereby mitigating the output mutation and overshoot caused by the sudden change of the set value, thus reducing the response speed and overshoot.

[0057] The nonlinear differential tracker TD satisfies the following expression:

[0058]

[0059] In the formula: v(t) is the input signal; h is the integration step size; r is the tracking factor; fhan is a nonlinear function; the nonlinear function fhan includes a sign function to mitigate output jumps and overshoot caused by sudden changes in the setpoint, and the relationship between the sign function and the nonlinear function satisfies the following logical expression:

[0060]

[0061] The Extended Observer (ESO) modifies the transition of the optimal control function at the origin and segment points of the permanent magnet synchronous motor. The ESO performs transition processing at the origin and segment points within the optimal control function, and satisfies the following expression:

[0062]

[0063] Where f nal The expression for (e, α, δ) is:

[0064]

[0065] In the above expression, ω is the input signal; e is the observation error; Z1 is the tracking signal of the input signal; Z2 is the differential signal of the input signal; Z3 is the observed signal of the system disturbance; α1, α2, α3 are tracking factors; δ is the filtering factor; β1, β2, β3 are the extended observer output error correction gain; b0 is the compensation factor; u is the system output; f nal (e, α, δ) is the optimal control function.

[0066] When the permanent magnet synchronous motor (PMSM) is running at low speeds of 100 rad / min and 200 rad / min, the controller in this embodiment can effectively meet the control requirements for motor overshoot, response speed, and time to reach steady state.

[0067] like Figure 6 As shown: A comparative experiment was conducted between a traditional controller and a controller that improved the nonlinear differential tracker and extended observer in the traditional controller. The thick black line represents the output speed of the motor controlled by the improved controller, and the thin black curve represents the output speed of the motor controlled by the traditional controller.

[0068] We can see that when the motor is running at low speeds of 100 rad / min and 200 rad / min, the improved controller outperforms the traditional controller in terms of tracking performance, response speed, robustness, and anti-interference capability.

[0069] The above embodiments are merely illustrative of the principles and functional effects of the present invention and are not intended to limit the present invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A permanent magnet synchronous motor-based lift system, comprising a car and an elevator drive system, the elevator drive system comprising a mounting beam fixedly mounted on the inner side wall of an elevator shaft, a permanent magnet synchronous motor fixedly connected to the upper end of the mounting beam, a winding device coaxially connected to the output shaft of the permanent magnet synchronous motor, a steel rope wound on the winding device, the car suspended on the steel rope through a pulley system and moved by the dragging of the steel rope, the car placed in the elevator shaft, a magnetic suspension track installed in the elevator shaft, a magnetic force column installed on the outer wall of the elevator and matched with the magnetic suspension track, and an electromagnet monomer installed in the magnetic suspension track, the electromagnet monomers arranged in sections in the magnetic suspension track and arranged at the positions where the elevator hovers on each floor of the building.

2. The permanent magnet synchronous motor-based lift elevator system of claim 1, wherein: The magnetic suspension track is a C-shaped track, and the magnetic force column is cylindrical and gap-fitted in the C-shaped track.

3. Permanent magnet synchronous motor based lift system according to claim 1 or 2, characterized in that: The magnetic force column is fixedly connected to the outer wall of the car through a frame, the frame is assembled by a plurality of steel structure trusses, and the magnetic force column is vertically installed at the four corners of the outer wall of the elevator.

4. The permanent magnet synchronous motor-based lift elevator system of claim 3, wherein: In the magnetic suspension tracks from the bottom of the first floor to the top of the highest floor of the elevator shaft, the installed electromagnet monomers are continuously arranged and extend to both ends of the magnetic suspension track.

5. The permanent magnet synchronous motor-based lift elevator system of claim 4, wherein: A magnetizer for magnetizing the electromagnet monomers and the magnetic force column is installed on the side wall of the elevator shaft, and the magnetizer is separately connected to the electromagnet monomers by a cable.

6. The permanent magnet synchronous motor-based lift elevator system of claim 5, wherein: A magnetizing contact is installed on the inner wall of the corresponding magnetic suspension track of the first floor, and a magnetizing contact point is provided on the magnetic force column, the magnetizing contact and the magnetizing contact point are in communication when the magnetic force column hovers in the first floor, and the magnetizing contact and the magnetizer are in communication through a cable.

7. The permanent magnet synchronous motor-based lift elevator system of claim 6, wherein: A bumper vertically opposite to the magnetic force column is installed at the bottom of the magnetic suspension track.

8. The permanent magnet synchronous motor-based lift elevator system of claim 7, wherein: The permanent magnet synchronous motor is provided with a controller, the controller extends out of the elevator shaft through a control cable, the controller has computer processing capability and communicates with the permanent magnet synchronous motor, the controller comprises a nonlinear differential tracker, an extended observer and a fractional order proportional integral differential controller, the nonlinear differential tracker is used for tracking signals, the extended observer is used for observing the state inside the system and estimating the unpredictable state of the system, and the fractional order proportional integral differential controller is used for nonlinearly combining the outputs of the nonlinear differential tracker and the extended observer to provide a stable output signal.

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