WO2020259232A1

WO2020259232A1 - Magnetic bearing and high-performance servo motor

Info

Publication number: WO2020259232A1
Application number: PCT/CN2020/094049
Authority: WO
Inventors: 李月芹
Original assignee: 李月芹
Priority date: 2019-06-23
Filing date: 2020-06-03
Publication date: 2020-12-30
Also published as: CN110417181A; CN110417181B

Abstract

A magnetic bearing and a high-performance servo motor. The magnetic bearing comprises a housing, and is characterized by further comprising a fixed ring provided in the housing and a plurality of magnetic rollers provided circumferentially along the periphery of the fixed ring. The fixed ring comprises four circular rings concentrically provided and nested in sequence, and the four circular rings are sequentially a rare earth metal ring, a Teflon ring, a permanent magnet ring, and a copper ring from inside to outside; the magnetic rollers at least comprise a permanent magnet, and the polarity of the permanent magnet ring on the fixed ring is opposite to that of the permanent magnet of the magnetic rollers. The servo motor using the magnetic bearing provided by the present invention has a simple control circuit, a long service life and a fast rotation speed.

Description

A magnetic bearing and high-performance servo motor

This application claims the priority of a Chinese patent application filed on June 23, 2019 with the application number 20191054830.5 and the invention title "A Magnetic Bearing and High Performance Servo Motor", the entire content of which is incorporated into this application by reference.

Technical field

The invention relates to a magnetic suspension bearing and a high-performance servo motor, belonging to the technical field of motors.

Background technique

The servo motor provided in the prior art is a motor with a mechanical bearing, which includes a stator and a rotor. A winding for rotation is provided in the slot of the stator. When a current is applied to the winding, the rotor rotates in the mechanical bearing. This kind of servo motor The disadvantage is that the mechanical bearings are severely worn, the motor life is short, and the speed is low.

technical problem

In order to overcome the shortcomings of the prior art, the purpose of the invention is to provide a magnetic suspension bearing and a high-performance servo motor. The magnetic suspension bearing has a simple structure, has a long service life and a high output speed.

Technical solutions

In order to achieve the objective of the invention, the invention provides a magnetic suspension bearing, which includes a housing, and is characterized in that it also includes a fixed ring arranged in the housing and a plurality of magnetic rollers arranged on the outer periphery of the fixed ring and arranged in the circumferential direction. The ring includes four rings that are concentrically arranged and nested in sequence. The four rings are rare earth metal rings, Teflon rings, permanent magnet rings, and copper rings from the inside to the outside; the magnetic roller includes at least permanent For the magnet, the polarity of the permanent magnet ring on the fixed ring is opposite to that of the permanent magnet of the magnetic roller.

Preferably, the magnetic roller is a magnetic roller, which is a rare earth metal ring, a Teflon ring, a permanent magnet ring and a copper ring in order from the inside to the outside.

Preferably, the rare earth metal is neodymium.

Preferably, the housing at least includes a shielding layer for isolating the external interference from the magnetic field generated by the fixed ring and the magnetic roller.

In order to achieve the objective of the invention, the present invention also provides a servo motor, which includes a motor and a driver. The motor movably sets the rotor shaft on the support through the above-mentioned magnetic suspension bearing. The driver is based on a set operating mode. Provide AC current to the drive winding of the motor.

Preferably, the driver includes an ACDC converter for converting AC power into DC power, an energy storage device for storing DC power, and an instruction arithmetic unit; the instruction arithmetic unit is based on the amount of electrical energy stored in the energy storage and The operation mode of the motor controls the power supply of the ACDC converter.

Preferably, the command calculation unit includes a current detection unit, a speed command unit, an energy storage detection unit, a current command calculation unit, and a current control unit, wherein the current detection unit is used to detect the current value at the input of the ACDC converter; The unit is used to detect the power stored in the energy storage; the speed command unit calculates the required power to drive the motor according to the speed mode; the current command calculation unit is based on the command of the speed command unit and the power that the energy storage provided by the energy storage detection unit can provide Calculate the proportion of electric energy supplied from the ACDC converter and the energy storage to the motor; the current control unit controls the ACDC converter to provide electric energy according to the proportion of power supplied by the current control unit according to the instruction of the current command calculation unit and the current supplied by the current detection unit.

Preferably, the command calculation unit includes a voltage detection unit, a speed command unit, an energy storage detection unit, a voltage command calculation unit, and a current control unit, wherein the voltage detection unit is used to detect the voltage value at the input of the ACDC converter; The unit is used to detect the power stored in the energy storage; the speed command unit calculates the required power to drive the motor according to the speed mode; the voltage command calculation unit is based on the command of the speed command unit and the power that the energy storage provided by the energy storage detection unit can provide Calculate the proportion of the electric energy supplied from the ACDC converter and the energy storage to the motor; the voltage control unit controls the ACDC converter to provide electric energy according to the proportion it should supply according to the instruction of the voltage command calculation unit and the supply voltage provided by the voltage detection unit.

Beneficial effect

Compared with the prior art, the magnetic bearing provided by the invention has a simple structure and does not require additional power supply to generate supporting force. Since the servo motor provided by the invention makes the rotor magnetically suspended on the base, it does not need to overcome the mechanical bearing when the rotor rotates. Resistance, and small mechanical friction, therefore, long life, high speed and large output power.

Description of the drawings

Fig. 1 is a schematic diagram of the composition of the magnetic suspension bearing provided by the present invention.

Figure 2 is a block diagram of the servo motor power supply circuit provided by the present invention.

Fig. 3 is a working state diagram of the servo motor provided by the present invention.

Fig. 4 is a block diagram of a modification of the servo motor power supply circuit provided by the present invention.

Fig. 5 is a block diagram of another modification of the servo motor power supply circuit provided by the present invention.

Fig. 6 is a circuit diagram of an ACDC converter provided by the present invention.

The best mode of the invention

The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings, in which the same or similar reference numerals indicate the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary, and the illustrated embodiments are only used to explain the present invention, and cannot be construed as limiting the present invention.

Those skilled in the art can understand that, unless specifically stated, the singular forms "a", "an", "said" and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of the described features, integers, steps, operations, elements and/or components, but does not exclude the presence or addition of one or more other features, Integers, steps, operations, elements, components, and/or combinations thereof. It should be understood that when we refer to an element as being "connected" to another element, it can be directly connected to the other element, or intervening elements may also be present. The term "and/or" as used herein includes all or any unit and all combinations of one or more associated listed items.

Those skilled in the art can understand that all terms (including technical terms and scientific terms) used herein have the same meaning as those commonly understood by those of ordinary skill in the art to which the present invention belongs. It should also be understood that the terms used in this application document should be understood as having a meaning consistent with the prior art, and unless specifically defined in this application document, they will not be interpreted with extreme meanings.

Embodiments of the invention

Fig. 1 is a schematic diagram of the composition of the magnetic suspension bearing provided by the invention. As shown in Fig. 1, the magnetic suspension bearing provided by the invention includes a housing 5, a fixed ring arranged in the housing 5, and a plurality of circumferentially arranged outside the fixed ring. Magnetic rollers Ro1-Ro8, the fixed ring includes four circular rings arranged concentrically and nested in sequence, the four circular rings sequentially from the inside to the outside, the rare earth metal ring 1, the Teflon ring 2, the permanent magnet ring 3 And the copper ring 4, the upper end of the permanent magnet 3 is N polarity, and the lower end is S polarity. The magnetic roller includes at least a permanent magnet. Preferably, the magnetic roller is a magnetic roller. The magnetic roller Ro is a rare earth metal ring, a Teflon ring, a permanent magnet ring, and a copper ring from the inside to the outside. The upper end of the magnet is S pole, and the lower end is N pole. Preferably, the rare earth metal is neodymium. The casing 5 preferably includes a magnetic shielding material to prevent the magnetic field generated by the fixed ring and the magnetic roller from interfering with the outside. Although the invention is exemplarily described with eight magnetic rollers, there may be any number of magnetic rollers.

When in use, the shaft sub-axis AX of the servo motor is fixed on the fixed ring. When the rotor shaft AX is driven to rotate by the rotating magnetic field generated by the stator of the servo motor, the fixed ring also rotates. The fixed ring and the surrounding magnetic There will be a magnetic levitation between the rollers, so as to make frictionless sliding, and the magnetic rollers will rotate.

The power supply circuit of the servo motor provided by the present invention is described below.

Figure 2 is a block diagram of the power supply circuit of the servo motor provided by the present invention. As shown in Figure 2, the control system includes an ACDC converter, which is used to boost the AC power provided by the AC power supply 201 and convert it into DC power. The ACDC converter includes an inductor 202, a power converter 203, and a filter 204. The AC power source 201 is connected to the power converter 203 via the inductor 202. The power converter 203 converts AC power into DC power and boosts it, and then filters it. The filter 204 filters out AC components.

The output terminal of the electric energy converter 203 is connected to the energy storage 209 and provides DC electric energy to the current inverter 206. The energy storage 209 may use a rechargeable battery, a large-capacity capacitor, an electric double layer capacitor, and the like.

A capacitor 207 is also provided on the DC side of the inverter 206. The AC side of the inverter 206 is connected to the AC motor M, and is used to provide an AC current to the motor M to generate a rotating magnetic field. The rotation speed and rotation position of the AC motor M are detected by the encoder 211. The instruction of the rotation speed of the electric motor M is output from the rotation speed instruction unit 221.

The speed control unit 222 operates according to the speed command from the rotation speed command unit 221 and the feedback signals from the encoder 211 and the current detector 223, and implements the speed control, current control, and PWM control of the AC motor M, and controls the inverter based on the output. 206 performs PWM control. Since this control is well-known, detailed description is omitted.

The power supply circuit provided by the present invention also includes the instruction calculation unit, including a current detection unit 234, a speed command unit 221, an energy storage detection unit 231, a current command calculation unit 232, and a current control unit 233, wherein the current detection unit 234 is used for The current value at the input of the ACDC converter is detected; the energy storage detection unit 231 is used to detect the amount of electricity stored in the energy storage 209; the speed command unit 221 calculates the required electric energy to drive the motor M according to the speed mode; the current command calculation unit 232 according to the speed command The instruction of the unit 221 and the energy storage device 209 provided by the energy storage detection unit 231 calculates the proportion of the electrical energy supplied to the motor from the ACDC converter and the energy storage 209; the current control unit 233 is based on the instruction of the current instruction calculation unit 232 and The power supply current provided by the current detection unit 234 controls the ACDC converter to provide electrical energy according to the ratio it should supply. In addition, in this example, the speed command is issued from the rotation speed command unit 221, but it may also be configured to issue a position command, and the speed control unit 222 may perform position control, speed control, current control, and PWM control of the AC motor M.

On the other hand, the energy storage state of the energy storage 209 is detected by the energy storage detection unit 231. In addition, the required electric energy of the AC motor M is calculated by the rotation speed command unit 221. The detection value of the energy storage detection unit 231 and the required electric energy from the rotation speed command unit 221 are input to the current command calculation unit 232, and the current command calculation unit 232 calculates the output current of the ACDC converter 205. That is, when the power factor of the AC power supply 201 is 1, the magnitude of the current of the AC power supply 201 is indicated. The current control unit 233 operates according to the output of the current command calculation unit 232, the voltage of the AC power source 201, and the signal from the current detector 234, and implements current control and PWM control of the AC power source 201, and makes the power converter 203 perform PWM operation.

The working process of the ACDC converter 205 is described below. In the rotation speed command unit 221, the instantaneous electric energy required by the AC motor M is calculated, that is, the electric energy required to drive the electric motor M is calculated according to the rotation speed mode. The required electric energy is calculated from the product of the speed command and the torque command according to the speed mode. The speed command is obtained as the speed mode of the robot, that is, the speed command of the AC motor, and the torque command is obtained from the torque command when the test robot is moving.

The electric energy required by the AC motor M is supplied from the energy storage 209 and the ACDC converter 205. The current command calculation unit 232 determines the supply ratio of the two. The stored energy detection unit 231 calculates output and storable power based on the storage amount. The current command calculation unit 232 calculates the power output from the ACDC converter 205, that is, the current command value corresponding to the power, based on the electric energy required by the motor from the rotation speed command unit 221 and the detected value from the stored energy detection unit 231. The electric energy required by the motor from the current command unit 221 can be output at all times including the current time and the value after the current time, or one cycle of the rotation speed mode can be output to the current command calculation unit 232 in advance. The storage capacity of the energy storage 209 can be calculated based on the voltage and current entering and leaving the energy storage 209. Alternatively, it may be calculated from only one of voltage and current. In addition, the energy storage detection unit 231 may not detect the storage amount itself, but may perform detection based on the electric energy flowing into or out of the energy storage 209.

In this way, the calculation of the current command calculation unit 232 considers the electric energy required by the motor corresponding to the rotation speed mode and the stored energy stored in the energy storage to calculate the current command. The current control unit 233 controls the ACDC converter 205 so that a power source current corresponding to the current command value flows from the AC power source 201 to the ACDC converter 205. With this structure, the power supply current can be controlled to a sine wave and the power factor is 1. In addition, as the current command value provided to the current control unit 233, as described above, not only the power factor is controlled to be 1, but also control other than the power factor=1 can be performed.

Fig. 3 is an example of controlling the working state of the ACDC converter according to the speed mode. Fig. 3(a) is a waveform diagram of the motor rotation speed, Fig. 3(b) is the torque required by the motor, and Fig. 2(c) is the motor Energy demand, Figure 3(d) is the output of the ACDC converter, Figure 3(e) is the output of the energy storage, Figure 3(f) is the stored energy stored in the energy storage, the horizontal axis is the common time axis . As shown in Figure 3, at t0, the motor rotates at a high speed. From t1 to t2, enter the deceleration state. From t2 to t3, the work is carried out while accelerating. From t3 to t4, after the work is completed, the motor accelerates and then rotates at a high speed from t5. Repeat the above process thereafter.

In the example shown in FIG. 3, the motor requires deceleration torque from t1 to t2, from t2 to t3, requires torque for work, and from t3 to t4, requires acceleration torque. The torque at this speed is calculated in advance based on the results of simulation calculations or test speeds based on the content of work. The electric energy required by the motor is determined by the product of the motor's rotation speed and the required torque. It can be seen that a large amount of electric energy is required from t2 to t3 during operation, which in turn requires large energy as a time integral. In order to cope with the large energy during such work, the current output value is set as follows. In FIG. 3, a command for obtaining a predetermined output current is output to the ACDC converter from time t1. From t1 to t2, although the motor is performing regeneration work, the ACDC converter outputs electric energy from the AC power supply 201 to the ACDC converter. As a result, as shown in Figure 4(e), from t1 to t2, the regenerative electric energy from the motor and the electric energy from the power supply flow into the energy storage. Starting at t2, the electric energy from both the energy storage and the power supply flows to the motor, and continues until t4. Then, while detecting the energy storage state, a current command for the energy storage device to perform the energy storage operation is issued, and the current command returns to zero at time t41. In this way, the required required electric energy is calculated according to the operating mode, and when the current command is determined, even if the conversion capacity of the ACDC converter or the energy storage capacity of the energy storage is small, the required energy can be provided to the motor.

Fig. 4 shows a block diagram of a power supply circuit according to another embodiment of the present invention. In FIG. 4, the same components as those in FIG. 2 are given the same reference numerals. The feature of this embodiment is that the command calculation unit includes a voltage detection unit 253, a speed command unit 221, an energy storage detection unit 231, a voltage command calculation unit 251, and a voltage control unit 252, wherein the voltage detection unit 253 is used to detect ACDC The voltage value at the input of the converter; the energy storage detection unit 231 is used to detect the amount of electricity stored in the energy storage; the speed command unit 221 calculates the required electric energy to drive the motor according to the working mode; the voltage command calculation unit 251 is based on the command of the speed command unit 221 Calculate the ratio of the electric energy supplied to the motor from the ACDC converter and the energy storage 209 with the energy storage provided by the energy storage detection unit 231; the voltage control unit 252 provides voltage according to the instructions of the voltage command calculation unit and the voltage detection unit 253 The power supply voltage controls the ACDC converter to provide power according to the proportion it should supply. In this way, the voltage command is changed according to the rotation speed command and the energy storage state, and the corresponding voltage command is obtained, and the ACDC converter 205 is operated. Since the voltage of the energy storage 209 differs according to the energy storage state, the command value of the DC voltage is changed according to the rotation speed command and the energy storage state. In this way, the present invention can also be realized.

Fig. 5 is a block diagram of the power supply circuit of another variable column provided by the present invention. As shown in Fig. 5, the same parts as the power supply circuit shown in Fig. 2 will not be repeated, and only the different parts will be described below. The power supply circuit shown in FIG. 5 also includes a current limit calculation unit 261, which is used for the ACDC converter 205 to calculate the ACDC conversion based on the energy storage information provided by the energy storage detection unit 209 and the instructions provided by the speed command unit 221 The voltage command output by the device 205 and calculate its maximum limit current value. The voltage instruction unit 262 provides instructions to the voltage control unit 263 in accordance with instructions from the current limit calculation unit 261. The voltage control unit 263 supplies the current limiting unit according to the DC voltage command, the information provided by the voltage detection unit 253 for detecting the voltage at the input of the ACDC converter 205, and the information provided by the voltage detection unit 265 for detecting the voltage at the output of the ACDC converter 205. 264 refers to the current command value. The current limit unit 264 determines the limit value of the current of the power supply 201 based on the signal of the current limit calculation unit 261 and the instruction provided by the voltage control unit 263, thereby limiting the current flowing from the AC power supply 201. Since the voltage command value and the current limit value are variably controlled according to the rotation speed command and the stored energy, the capacity of the booster 205 and the energy storage 209 can be further reduced.

The control system provided by the present invention can provide control signals to multiple motors, and the energy storage or ACDC converter supplies all motors to provide electrical energy. Each motor has its own inverter. The DC bus side of the motor inverter is commonly connected, and then connected to the output terminal of the ACDC converter 205.

Fig. 6 is a circuit diagram of the ACDC converter provided by the present invention. As shown in Fig. 6, the present invention provides an ACDC converter. The first switching element T1 and the second switching element T2 are controlled by a pulse width modulation circuit to turn them on or off at the same time. . When the first switching element T1 and the second switching element T2 are turned on, the current of the AC power supply 201 only flows through the inductor 202, and the excitation energy is stored in the inductor 202. When the first switching element T1 and the second switching element T2 are disconnected, the excitation energy of the inductor 202 flows through the AC power supply 201 and the bridge rectifier circuit composed of the diode D1 and the diode D2 for rectification, and then is filtered by the capacitor 204 to output DC power can. During the release of the excitation energy of the reactor 2, the voltage at both ends of the first switching element T1 and the second switching element T2 is approximately equal to the voltage at both ends of the capacitor 204. When the release is disconnected, the voltage drops to that of the AC voltage of the AC power supply 201. Instantaneous value. This voltage drop is captured by the series circuit of the capacitor C1 and the resistor R1 or the series circuit of the capacitor C2 and the resistor R2. When the falling voltage is less than the value of the reference power supply, the comparator CO1 or the comparator CO2 outputs a high level, and the pulse width modulation circuit outputs a pulse that turns on the first switching element T1 and the second switching element T2. Since the first switching element T1 and the second switching element T2 are turned on after the excitation energy of the inductor 202 becomes zero, the current flowing through the AC power source 201 rises from zero ampere. The amount of power supplied by the AC power supply 201 can be controlled by controlling the square wave signal output by the PWM circuit of the pulse width modulation circuit.

During the on period, since either of the positive half cycle and the negative half cycle of the AC voltage is maintained at a constant value, the peak current of the inductor 202 before the off is proportional to the instantaneous value of the AC voltage. In addition, the slope of the decrease from the peak current is proportional to the difference between the voltage of the capacitor 204 and the instantaneous value of the AC voltage. Since the voltage of the AC power supply is a sine wave, the current waveforms in the positive half cycle and the negative half cycle are the same, that is, even-order harmonic currents do not flow. Therefore, the ACDC converter provided by the present invention can suppress even harmonic interference.

It should be noted that the language used in this specification is mainly selected for readability and teaching purposes, not for explaining or limiting the subject of the present invention. Therefore, without departing from the scope and spirit of the appended claims, many modifications and alterations are obvious to those of ordinary skill in the art. As for the scope of the present invention, the disclosure of the present invention is illustrative rather than restrictive, and the protection scope required by the present invention is defined by the appended claims.

Industrial applicability

The magnetic suspension bearing and the high-performance servo motor provided by the present invention can be manufactured in the industry and can achieve the following beneficial effects: the magnetic suspension bearing has a simple structure and does not require additional power supply to generate supporting force. The servo motor provided by the invention makes the rotor magnetic The magnetic suspension is on the base. When the rotor rotates, there is no need to overcome the resistance of the mechanical bearing, and the mechanical friction is small, so it has a long life, high speed and high output power.

Claims

A magnetic suspension bearing, which includes a housing, is characterized in that it also includes a fixed ring arranged in the housing and a plurality of magnetic rollers arranged on the outer periphery of the fixed ring and arranged in the circumferential direction. The fixed ring includes concentrically arranged and sequentially nested Four rings, the four rings are rare earth metal rings, Teflon rings, permanent magnet rings and copper rings in order from the inside to the outside; the magnetic roller includes at least a permanent magnet, and a permanent magnet ring on the fixed ring The polarity of the magnetic roller permanent magnet is opposite.
The magnetic suspension bearing according to claim 1, wherein the magnetic roller is a magnetic roller, which is a rare earth metal ring, a Teflon ring, a permanent magnet ring and a copper ring in order from the inside to the outside.
The magnetic suspension bearing according to claim 2, wherein the rare earth metal is neodymium.
The magnetic suspension bearing according to claim 3, wherein the shell at least comprises a shielding layer for isolating the external interference of the magnetic field generated by the fixed ring and the magnetic roller.
A servo motor, characterized in that it comprises a motor and a driver, the motor is movably arranged on a support with a rotor shaft through the magnetic suspension bearing of any one of claims 1-4, and the driver operates according to a set The mode provides AC current to the drive winding of the motor.
The servo motor according to claim 5, wherein the driver comprises an ACDC converter for converting alternating current into direct current electric energy, an energy storage device for storing direct current electric energy, and an instruction operation unit; the instruction operation unit According to the electric energy storage amount of the energy storage device and the operation mode of the electric motor, the electric energy supply amount of the ACDC converter is controlled.
The servo motor according to claim 6, wherein the command calculation unit includes a current detection unit, a speed command unit, an energy storage detection unit, a current command calculation unit, and a current control unit, wherein the current detection unit is used to detect The current value at the input of the ACDC converter; the energy storage detection unit is used to detect the amount of electricity stored in the energy storage; the speed command unit calculates the required electric energy to drive the motor according to the speed mode; the current command calculation unit is based on the command and energy storage of the speed command unit The energy storage provided by the detection unit calculates the proportion of the electrical energy supplied from the ACDC converter and the energy storage to the motor; the current control unit controls the ACDC converter according to the instruction of the current command calculation unit and the current supplied by the current detection unit Provide electricity in proportion to its supply.
The servo motor according to claim 6, wherein the command calculation unit includes a voltage detection unit, a speed command unit, an energy storage detection unit, a voltage command calculation unit, and a current control unit, wherein the voltage detection unit is used to detect The voltage value at the input of the ACDC converter; the energy storage detection unit is used to detect the amount of electricity stored in the energy storage; the speed command unit calculates the required electric energy to drive the motor according to the speed mode; the voltage command calculation unit is based on the command and energy storage of the speed command unit The energy storage provided by the detection unit calculates the proportion of the electrical energy supplied from the ACDC converter and the energy storage to the motor; the voltage control unit calculates the command and voltage of the unit according to the voltage command.

To