CN113872467B

CN113872467B - Control method and device of frequency converter, electric appliance and readable storage medium

Info

Publication number: CN113872467B
Application number: CN202111163766.8A
Authority: CN
Inventors: 贺伟衡; 杨斌; 刘树清; 靳珂珂
Original assignee: Midea Group Co Ltd; GD Midea Heating and Ventilating Equipment Co Ltd
Current assignee: Midea Group Co Ltd; GD Midea Heating and Ventilating Equipment Co Ltd
Priority date: 2021-09-30
Filing date: 2021-09-30
Publication date: 2024-08-06
Anticipated expiration: 2041-09-30
Also published as: CN113872467A

Abstract

The invention provides a control method and device of a frequency converter, an electric appliance and a readable storage medium, wherein the control method of the frequency converter comprises the following steps: acquiring the rotation direction of a rotor of the magnetic suspension motor; the rotor is reversely rotated, the frequency converter is controlled to enter a power generation mode, wherein the magnetic levitation motor charges a capacitor in the frequency converter when the frequency converter is operated in the power generation mode, the bearing control device of the rotor drives the rotor to keep in suspension under the power supply of the capacitor, and the protection of the rotor can be realized by operating the control method, so that the problem that the magnetic levitation motor is easy to damage when the magnetic levitation motor is reversely rotated is solved.

Description

Control method and device of frequency converter, electric appliance and readable storage medium

Technical Field

The present invention relates to the field of control technologies, and in particular, to a method and apparatus for controlling a frequency converter, an electric apparatus, and a readable storage medium.

Background

Under the influence of the refrigerant, the magnetic levitation motor can reverse, and at present, a control scheme for reversing the magnetic levitation motor does not exist, so that once the magnetic levitation motor reverses, the magnetic levitation motor is easily damaged.

Disclosure of Invention

The present invention aims to solve at least one of the technical problems existing in the prior art or related art.

To this end, a first aspect of the present invention is to provide a control method of a frequency converter.

A second aspect of the present invention provides a control device for a frequency converter.

A third aspect of the present invention is to provide one of the appliances.

A fourth aspect of the present invention is to provide a second electrical appliance.

A fifth aspect of the present invention is to provide a readable storage medium.

In view of this, according to a first aspect of the present invention, there is provided a control method of a frequency converter, wherein the frequency converter is connected to a magnetic levitation motor, the control method of the frequency converter comprising: acquiring the rotation direction of a rotor of the magnetic suspension motor; and controlling the frequency converter to enter a power generation mode based on rotor inversion, wherein the magnetic levitation motor charges a capacitor in the frequency converter when the frequency converter operates in the power generation mode, and the bearing control device of the rotor drives the rotor to keep levitation under the power supply of the capacitor.

According to the technical scheme, the control method of the frequency converter is provided, the protection of the rotor can be realized by operating the control method, and the problem that the magnetic levitation motor is easy to damage when the magnetic levitation motor rotates reversely is solved.

The technical scheme of the application is realized by the following scheme that in the running process of the magnetic suspension motor, the rotating direction of the rotor is obtained, if the rotor is reversed, a signal is sent to the frequency converter, so that the frequency converter enters a power generation mode under the condition of responding the signal, and in the power generation mode, the rotating mechanical energy of the rotor is converted into electric energy, at the moment, the capacitor in the frequency converter is charged under the action of the electric energy, and the charged capacitor plays a role of supplying power to the bearing control device of the rotor so as to support the bearing control device to run, so that the rotor keeps suspended.

In the scheme, under the condition that the rotor is reversely rotated, the rotor can still keep in suspension, and the contact friction probability of the rotor and the protection bearing is reduced, so that the heating and abrasion of the rotor and the protection bearing are reduced, and the service life of the magnetic suspension motor is prolonged.

In the above technical solution, the bearing control device can drive the rotor to suspend under the power supply of the capacitor, wherein the manner of implementing the suspension of the rotor can be implemented by using the repulsion between different magnets.

In the above technical scheme, the situation that the rotor is reversed may occur when the control system of the magnetic levitation motor is suddenly powered off, specifically, when the control system of the magnetic levitation motor is suddenly powered off, the magnetic levitation motor still operates according to the state between the power off states, the frequency converter can close the driving output due to the power off of the system, the refrigerant in the system can give the rotor a reversed impact force in the process of balancing the pressure due to the high exhaust pressure of the system where the magnetic levitation motor is located, and the rotation speed of the rotor reaches zero rapidly under the action of the impact force. Because the rotor has inertia in the rotating process, the rotor cannot stop rotating at the moment of zero rotating speed, but continues rotating under the action of the inertia, so that the rotor is reversed.

The technical scheme of the application is that when the rotor is reversed, the rotating speed of the rotor is given to the frequency converter, so that the frequency converter enters a power generation mode after receiving the rotating speed of the rotor, and the kinetic energy of the rotor is converted into electric energy, so that the bearing control device can work, the rotor is kept to be suspended, and the influence of the rotor reversal on the service life of the magnetic suspension motor is reduced.

In one of the solutions, the rotor is reversed, which may be caused by the reverse flow of the refrigerant in the system, in the case where the inverter and the magnetic levitation motor are not simultaneously operated, and in which case the rotor is normally not in suspension.

In addition, the control method of the frequency converter provided by the application also has the following accessory technical characteristics.

In the above technical scheme, based on rotor reversal, the control frequency converter enters into the power generation mode, specifically includes: acquiring the reversal rotation speed of a rotor; and controlling the frequency converter to enter a power generation mode under the condition that the reverse rotation speed is greater than or equal to the preset rotation speed.

In the technical scheme, if the rotor is reversed, the frequency converter is controlled to enter a power generation mode, so that the frequency converter is switched too frequently, and the frequency converter is easy to damage.

According to the technical scheme, before the frequency converter is controlled to enter the power generation mode, the reverse rotation speed of the rotor is also obtained, if the reverse rotation speed is too high, if the reverse rotation speed exceeds a preset rotation speed, namely the safe rotation speed, the rotor is considered to be extremely easy to contact with the protection bearing and wear in an unsteady state, and at the moment, the frequency converter is controlled to enter the power generation mode so as to control the rotor to keep in suspension.

In the control scheme, the frequency of switching of the frequency converter is reduced, and the service life of the frequency converter is prolonged.

In addition, when the rotor rotates at a safe rotating speed, friction and abrasion between the rotor and the protection bearing are in an acceptable range, high temperature and large abrasion of the magnetic suspension motor cannot occur, and finally the motor is damaged.

In any of the above technical solutions, before the controlling the frequency converter to enter the power generation mode, the method further includes: and determining the rotor reversal of the magnetic levitation motor based on the fact that the rotation direction of the rotor is opposite to the preset direction.

In the technical scheme, whether the rotor is reversely rotated or not is judged, if the judgment is not carried out, the misjudgment of the rotation direction of the rotor can occur, namely, when the rotor is in forward rotation, the rotor is misjudged to be reversely rotated, and when misjudgment occurs, the frequency converter can be switched to a power generation mode, the rotor cannot be driven, the magnetic suspension motor is stopped, and the running stability of the magnetic suspension motor is affected.

In order to avoid the occurrence of the above situation, before the frequency converter is controlled to enter the power generation mode, the rotation direction of the rotor is obtained and compared with the preset direction, and if the rotation direction is inconsistent with the preset direction, namely opposite, the rotor is considered to be reversed.

In the control scheme, whether the rotor is reversed or not is judged, and the reliability of operation control of the magnetic suspension motor is improved.

In any of the above technical solutions, before acquiring the rotation direction of the rotor of the magnetic levitation motor, the method further includes: acquiring a wire connection state between the frequency converter and the magnetic suspension motor; determining that the wire connection state is abnormal based on the fact that the preset direction is inconsistent with the rotation direction corresponding to the wire connection state; and determining that the wire connection state is normal based on the fact that the preset direction is consistent with the corresponding rotation direction of the wire connection state.

In the technical scheme, the preset direction is the direction of the rotor rotating correctly, and when the wire connection state is abnormal, the rotating direction corresponding to the wire connection state is inconsistent with the preset direction, so that after the wire connection state is obtained, the rotating direction corresponding to the wire connection state can be compared with the preset direction, and whether the wire connection is normal or not can be determined.

In the process, the diagnosis of whether the connection of the frequency converter and the magnetic suspension motor is abnormal can be realized, and the problems caused by abnormal connection, such as the failure of the magnetic suspension motor, occupy a large amount of maintenance time and workload, are reduced.

In any of the above technical solutions, the alert information is output based on the abnormality of the wire connection state.

In the technical scheme, the reminding information is output, so that a user can know whether the wire connection is abnormal or not in time, and the abnormality is processed in time, and the loss probability caused by the abnormal connection is reduced.

According to a second aspect of the present invention, there is provided a control device for a frequency converter, the frequency converter being connected to a magnetic levitation motor, the control device for the frequency converter comprising: an acquisition unit for acquiring a rotation direction of a rotor of the magnetic levitation motor; and the control unit is used for controlling the frequency converter to enter a power generation mode based on rotor inversion, wherein the magnetic suspension motor charges a capacitor in the frequency converter when the frequency converter operates in the power generation mode, and the bearing control device of the rotor drives the rotor to keep in suspension under the power supply of the capacitor.

The technical scheme of the application provides a control device of a frequency converter, and by using the control device, the protection of a rotor can be realized, and the problem that a magnetic levitation motor is easy to damage when the magnetic levitation motor is reversed is solved.

In the above technical solution, the control unit is specifically configured to: acquiring the reversal rotation speed of a rotor; and controlling the frequency converter to enter a power generation mode under the condition that the reverse rotation speed is greater than or equal to the preset rotation speed.

In any of the above solutions, the control unit is further configured to: and determining the rotor reversal of the magnetic levitation motor based on the fact that the rotation direction of the rotor is opposite to the preset direction.

In any of the above solutions, the obtaining unit is further configured to: acquiring a wire connection state between the frequency converter and the magnetic suspension motor; determining that the wire connection state is abnormal based on the fact that the preset direction is inconsistent with the rotation direction corresponding to the wire connection state; and determining that the wire connection state is normal based on the fact that the preset direction is consistent with the corresponding rotation direction of the wire connection state.

In any of the above solutions, the control unit is further configured to: and outputting reminding information based on abnormal connection state of the wires.

According to a third aspect of the present invention, there is provided an electrical appliance comprising: a control device for a frequency converter as claimed in any one of the preceding claims.

The technical scheme of the application provides an electric appliance, wherein the electric appliance is provided with the control device of any one of the frequency converters, so that the electric appliance has all the beneficial technical effects of the control device of any one of the frequency converters, and the description is omitted.

According to a fourth aspect of the present invention, there is provided an electrical appliance comprising: a magnetic levitation motor having a rotor; bearing control means for driving the rotor in suspension; the frequency converter is connected with the magnetic suspension motor and the bearing control device and is used for executing the steps of the control method of the frequency converter.

The technical scheme of the application provides an electric appliance, wherein the electric appliance is provided with a magnetic suspension motor, a bearing control device and a frequency converter, wherein the frequency converter executes the steps of the control method of any frequency converter, so that the electric appliance has all the beneficial technical effects of the control method of any frequency converter, and the description is omitted.

In the above technical solution, further includes: the eddy current sensor is connected with the frequency converter and used for detecting the rotation direction and the reverse rotation speed of the rotor.

In the above technical solution, the electric appliance includes an air conditioner.

According to a fifth aspect of the present invention there is provided a readable storage medium having stored thereon a program or instructions which when executed by a processor performs the steps of a method of controlling a frequency converter as described in any of the above.

The technical solution of the present application proposes a readable storage medium, wherein a program or an instruction stored on the readable storage medium, when executed by a processor, implements the steps of the method for controlling a frequency converter according to any one of the above, so that the readable storage medium has all the beneficial technical effects of the method for controlling a frequency converter according to any one of the above, and will not be described herein again.

Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Drawings

The foregoing and/or additional aspects and advantages of the invention will become apparent and may be better understood from the following description of embodiments taken in conjunction with the accompanying drawings in which:

Fig. 1 is a schematic flow chart of a control method of a frequency converter according to an embodiment of the invention;

FIG. 2 is a schematic flow chart of controlling a frequency converter to enter a power generation mode based on rotor reversal in an embodiment of the invention;

fig. 3 shows a schematic block diagram of a control device of a frequency converter in an embodiment of the invention;

FIG. 4 shows a schematic block diagram of an appliance in an embodiment of the present invention;

FIG. 5 shows a schematic view of a spin shaft, an eddy current sensor, a groove, and a protective bearing in an embodiment of the invention;

FIG. 6 is a schematic diagram showing the detection result of the eddy current sensor in the embodiment of the invention;

Fig. 7 is a schematic diagram showing a detection result of the eddy current sensor in the embodiment of the invention.

The correspondence between the reference numerals and the component names in fig. 5 is:

510 rotating shaft, 512 grooves, 520 eddy current sensor, 530 protecting bearings.

Detailed Description

So that the manner in which the above recited aspects, features and advantages of the present application can be understood in detail, a more particular description of the application, briefly summarized below, may be had by reference to the appended drawings. It should be noted that, without conflict, the embodiments of the present application and features in the embodiments may be combined with each other.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those described herein, and therefore the scope of the present invention is not limited to the specific embodiments disclosed below.

Example 1

According to an embodiment of the present invention, the present invention provides a control method of a frequency converter, where the frequency converter is connected to a magnetic levitation motor, as shown in fig. 1, the control method of the frequency converter includes:

102, acquiring the rotation direction of a rotor of a magnetic levitation motor;

Step 104, controlling the frequency converter to enter a power generation mode based on rotor inversion, wherein when the frequency converter operates in the power generation mode, the magnetic levitation motor charges a capacitor in the frequency converter, and the bearing control device of the rotor drives the rotor to keep levitation under the power supply of the capacitor.

The embodiment of the application provides a control method of a frequency converter, and by running the control method, the protection of a rotor can be realized, and the problem that a magnetic levitation motor is easy to damage when the magnetic levitation motor rotates reversely is solved.

The embodiment of the application is realized by the following scheme that in the running process of the magnetic suspension motor, the rotating direction of the rotor is obtained, if the rotor is reversed, a signal is sent to the frequency converter, so that the frequency converter enters a power generation mode under the condition of responding the signal, and in the power generation mode, the rotating mechanical energy of the rotor is converted into electric energy, at the moment, the capacitor in the frequency converter is charged under the action of the electric energy, and the charged capacitor plays a role of supplying power to the bearing control device of the rotor so as to support the bearing control device to run, so that the rotor keeps suspended.

In the above embodiment, the bearing control device can drive the rotor to float under the power supply of the capacitor, wherein the suspension of the rotor can be realized by utilizing the repulsion between different magnets.

In the above embodiment, the situation that the rotor is reversed may occur when the control system of the magnetic levitation motor is suddenly powered off, specifically, when the control system of the magnetic levitation motor is suddenly powered off, the magnetic levitation motor still operates according to the state between the power off states, the frequency converter can close the driving output due to the power off of the system, and the refrigerant in the system can give the rotor a reversed impact force in the process of balancing the pressure due to the high exhaust pressure of the system where the magnetic levitation motor is located, so that the rotation speed of the rotor reaches zero rapidly under the action of the impact force. Because the rotor has inertia in the rotating process, the rotor cannot stop rotating at the moment of zero rotating speed, but continues rotating under the action of the inertia, so that the rotor is reversed.

The embodiment of the application is that when the rotor is reversed, the rotating speed of the rotor is given to the frequency converter, so that the frequency converter enters a power generation mode after receiving the rotating speed of the rotor, and the kinetic energy of the rotor is converted into electric energy, so that the bearing control device can work, the rotor is kept in suspension, and the influence of the rotor reversal on the service life of the magnetic suspension motor is reduced.

In one embodiment, the rotor is reversed, if the inverter and the magnetic levitation motor are not simultaneously operated, due to the reverse flow of the refrigerant in the system, in which case the rotor is normally not levitated.

In the above embodiment, as shown in fig. 2, based on rotor reversal, the control of the inverter into the power generation mode specifically includes:

step 202, obtaining the reversal rotation speed of a rotor;

And 204, controlling the frequency converter to enter a power generation mode under the condition that the reverse rotation speed is greater than or equal to the preset rotation speed.

In this embodiment, if the rotor is reversed, the frequency converter is controlled to enter the power generation mode, so that the frequency converter is switched too frequently, and the frequency converter is easily damaged.

Before the frequency converter is controlled to enter the power generation mode, the embodiment of the application also obtains the reverse rotation speed of the rotor, and if the reverse rotation speed is too high, if the reverse rotation speed exceeds the preset rotation speed, namely the safe rotation speed, the rotor is considered to be extremely easy to contact with the protection bearing and wear in an unsteady state, and at the moment, the frequency converter is controlled to enter the power generation mode so as to control the rotor to keep in suspension.

In any of the foregoing embodiments, before controlling the frequency converter to enter the power generation mode, the method further includes: and determining the rotor reversal of the magnetic levitation motor based on the fact that the rotation direction of the rotor is opposite to the preset direction.

In this embodiment, whether the rotor is reversely rotated is determined, if the rotor is not determined, misdetermination of the rotation direction of the rotor occurs, that is, when the rotor is in forward rotation, the rotor is misdetermined to be reversely rotated, and when misdetermination occurs, the frequency converter is switched to a power generation mode, so that the rotor cannot be driven, the magnetic levitation motor is stopped, and the operation stability of the magnetic levitation motor is affected.

In any of the above embodiments, before acquiring the rotation direction of the rotor of the magnetic levitation motor, further comprising: acquiring a wire connection state between the frequency converter and the magnetic suspension motor; determining that the wire connection state is abnormal based on the fact that the preset direction is inconsistent with the rotation direction corresponding to the wire connection state; and determining that the wire connection state is normal based on the fact that the preset direction is consistent with the corresponding rotation direction of the wire connection state.

In this embodiment, the preset direction is the direction in which the rotor rotates correctly, and when the wire connection state is abnormal, the rotation direction corresponding to the wire connection state will not coincide with the preset direction, so after the wire connection state is obtained, the rotation direction corresponding to the wire connection state can be compared with the preset direction, so as to determine whether the wire connection is normal.

In any of the above embodiments, the alert information is output based on the abnormality of the wire connection state.

In the embodiment, the reminding information is output, so that a user can know whether the wire connection is abnormal or not in time, and the abnormal situation is processed in time, and the loss probability caused by the abnormal connection is reduced.

Example two

In one embodiment, as shown in fig. 3, the present invention provides a control device 300 of a frequency converter, where the frequency converter is connected to a magnetic levitation motor, and the control device 300 of the frequency converter includes: an acquisition unit 302 for acquiring a rotation direction of a rotor of the magnetic levitation motor; and the control unit 304 is used for controlling the frequency converter to enter a power generation mode based on rotor inversion, wherein the magnetic levitation motor charges a capacitor in the frequency converter when the frequency converter operates in the power generation mode, and the bearing control device of the rotor drives the rotor to keep levitation under the power supply of the capacitor.

In the above embodiment, the control unit 304 is specifically configured to: acquiring the reversal rotation speed of a rotor; and controlling the frequency converter to enter a power generation mode under the condition that the reverse rotation speed is greater than or equal to the preset rotation speed.

In any of the above embodiments, the control unit 304 is further configured to: and determining the rotor reversal of the magnetic levitation motor based on the fact that the rotation direction of the rotor is opposite to the preset direction.

In any of the above embodiments, the obtaining unit 302 is further configured to: acquiring a wire connection state between the frequency converter and the magnetic suspension motor; determining that the wire connection state is abnormal based on the fact that the preset direction is inconsistent with the rotation direction corresponding to the wire connection state; and determining that the wire connection state is normal based on the fact that the preset direction is consistent with the corresponding rotation direction of the wire connection state.

In any of the above embodiments, the control unit 304 is further configured to: and outputting reminding information based on abnormal connection state of the wires.

Example III

In one embodiment, the present invention provides an electrical appliance comprising: a control device for a frequency converter as claimed in any one of the preceding claims.

The embodiment of the application provides an electric appliance, wherein the electric appliance is provided with the control device of any one of the frequency converters, so that the electric appliance has all the beneficial technical effects of the control device of any one of the frequency converters, and the description is omitted herein.

Example IV

In one embodiment, as shown in FIG. 4, the present invention provides an appliance 400 comprising: a magnetic levitation motor 402, the magnetic levitation motor 402 having a rotor; bearing control 404 for driving the rotor in suspension; frequency converter 406, frequency converter 406 being connected to magnetic levitation motor 402 and bearing control 404 for performing the steps of the method of controlling frequency converter 406 as described above.

The embodiment of the present application proposes an electric appliance 400, wherein the electric appliance 400 has a magnetic levitation motor 402, a bearing control device 404 and a frequency converter 406, wherein the frequency converter 406 performs the steps of the control method of any of the frequency converters described above, and therefore, the electric appliance 400 has all the beneficial technical effects of the control method of any of the frequency converters described above, and will not be described herein.

In the above embodiment, further comprising: the eddy current sensor is connected to the frequency converter 406 for detecting the rotation direction and the reverse rotation speed of the rotor.

In one embodiment, the rotor has a rotation shaft, at least three grooves are arranged in the circumferential direction of the rotation shaft, distances between center points of two adjacent grooves in the at least three grooves are different, the eddy current sensor is used for detecting sampling signals when the rotation shaft rotates, and the step of detecting the rotation direction of the rotor comprises the following steps: according to the sampling signals, determining the time difference of two adjacent grooves in the at least three grooves passing through the eddy current sensor; determining a target duration in the time difference; and determining the rotation direction to be detected of the rotating shaft, namely the rotation direction of the rotor, according to the target duration.

In this embodiment, when the rotation shaft rotates, a sampling signal of the rotation shaft in a rotating state acquired by the eddy current sensor is acquired. The sampling information is analyzed to obtain the time difference when two adjacent grooves (depressions) on the rotating shaft are respectively positioned in the detection area of the eddy current sensor, namely the time required by the eddy current sensor from the detection of one groove to the detection of the adjacent other groove along the rotating direction of the rotating shaft. Wherein the time difference comprises the time length that all possible eddy current sensors pass through between two grooves, and since the rotating shaft is provided with at least three grooves, in one rotating period, the time difference comprises at least three time lengths, and each time length corresponds to two adjacent grooves of different groups respectively. According to preset conditions, selecting a target duration as a judging basis from a plurality of durations of the time difference, and judging the rotation direction of the rotation shaft to be detected by taking the target duration as the basis.

By the above embodiment, the state of the rotation shaft operation can be reproduced in software by using the sampling signal detection and signal separation circuit for the rotation shaft operation state, and the rotation direction of the rotation shaft can be analyzed. The problem that the rotation direction of the rotating shaft cannot be determined is solved, the system fault of the magnetic suspension motor caused by the inversion of the magnetic suspension motor is effectively prevented, the service life of the magnetic suspension motor is prolonged, and the operation reliability of the magnetic suspension motor is improved. And only one eddy current sensor is needed to be arranged, so that the detection of the rotation direction of the rotation shaft can be realized, the detection cost is reduced, and the multiple use requirements of a user are met.

The target duration may be a time difference between any two adjacent grooves located in the detection area of the eddy current sensor.

It is worth mentioning that the rotation shaft has and has only two rotation directions, namely a first rotation direction and a second rotation direction, the first rotation direction being one of clockwise and counterclockwise, the second rotation direction being opposite to the first rotation direction.

The magnetic levitation motor is provided with a rotating shaft and an eddy current sensor positioned on the peripheral side of the rotating shaft, and at least three grooves are formed in the rotating shaft along the circumferential direction of the rotating shaft. The distance between the center points of two adjacent grooves is different, namely, on the section of the rotating shaft, the rotating shaft is divided into at least three sectors by connecting lines of the center points of at least three grooves and the axis of the rotating shaft, and the angles of each sector in the at least three sectors are different. Therefore, when the rotating shaft rotates positively and reversely, the time required for the eddy current sensor to pass through the same groove is different, so that sampling signals detected by the positive rotation and the reverse rotation are different, and the rotating direction of the rotating shaft can be distinguished through the time difference between the two grooves during rotation. The eddy current sensor can detect the rotating shaft periodically according to the sampling period when the rotating shaft rotates, so as to obtain a sampling signal aiming at the rotating shaft, and the rotating direction of the rotating shaft to be detected is determined through the sampling signal. The sampling period is not suitable to be too long or too short, the sampling signal of 360 degrees of rotation of the rotating shaft cannot be completely collected by the too short sampling period, the too long sampling period is not beneficial to timely judging the rotating direction of the rotating shaft, and if the rotating shaft is in a state opposite to the preset direction, the stable operation of the magnetic suspension telephone is not beneficial.

In one embodiment, the step of detecting the rotational direction of the rotor includes: in the process that the rotating shaft rotates in the rotating direction to be detected, processing a sampling signal of the rotating shaft to obtain a level signal corresponding to the sampling signal; determining a rotation period of the rotation shaft according to the level signal; determining the duration between at least three adjacent two high-level signals in one rotation period according to the level signals; selecting a target duration from at least three durations; and judging the rotation direction to be detected, namely the rotation direction of the rotor, according to the target duration.

In this embodiment, the rotation of the rotation shaft is controlled in accordance with the rotation direction to be measured. When the grooves on the rotating shaft pass through the eddy current sensor, a pulse signal is generated in the sampling signal of the eddy current sensor, and the positions of the corresponding non-grooves in the sampling signal are stable. After the sampling period of the eddy current sensor is finished, in order to eliminate signal interference in the sampling signal, the sampling signal obtained in the sampling period is processed to convert the sampling signal into a level signal, so that the influence of partial interference on the first time detection process is eliminated. The high level signal in the level signal indicates that the groove is positioned in the detection area of the eddy current sensor, and the low level signal indicates that the groove is not positioned in the detection area of the eddy current sensor.

Specifically, processing the sampling signal of the rotation axis specifically includes: outputting a high level signal based on the sampled value indicated by the sampled signal being greater than or equal to the first signal threshold: and outputting a low-level signal based on the sampling value indicated by the sampling signal being less than or equal to a second signal threshold, wherein the first signal threshold is greater than a second signal threshold. So that it is determined whether the sampled signal is a high level signal or a low level signal by defining two parameters, a first signal threshold and a second signal threshold.

Further, because the angles of the sectors formed by the adjacent two grooves and the axis of the rotating shaft are different, that is, the distances between the center points of any two adjacent grooves are different, the time required for the eddy current sensor to pass through the adjacent two grooves in different groups is different. When the time length between the adjacent high-level signals of the level signals is the same, the eddy current sensor repeatedly collects pulse signals of the two grooves, and the rotating shaft rotates once. So that the rotation period of the rotation shaft can be determined using the level signal. The frequency of the rotating shaft can be calculated through the rotating period, a limiting range can be provided for selecting the target duration, the data processing amount is reduced, the data processing requirement on a processor is further reduced, and the manufacturing cost of the magnetic levitation motor is reduced.

For example, as shown in fig. 6 and 7, the rotation shaft completes one rotation from time t1 to time t 4. Then, the rotation is continued until the time t5 and the time t6 are reached, two pulse waveforms are generated again, and if the rotation is continued, the previous process is repeated, and then deltat _(t4-t1)＝Δt_(t5-t2)＝Δt_(t6-t3) is the time (rotation period) required for one rotation of the shaft.

Further, each groove corresponds to one high level signal in the level signals, then in one period, the level signals include at least three high level signals, at least three grooves are in one-to-one correspondence with the at least three high level signals, a time interval (duration) is reserved between every two adjacent high level signals, the at least three grooves can be divided into at least three adjacent two grooves, and the at least three adjacent high level signals are correspondingly reserved in the level signals, namely, at least three durations are reserved, and are collectively called as the time difference between the detection of the adjacent two grooves by the eddy current sensor.

In one embodiment, the step of detecting the rotational direction of the rotor includes: in the process that the rotating shaft rotates in the rotating direction to be detected, processing a sampling signal of the rotating shaft to obtain a level signal corresponding to the sampling signal; determining a rotation period of the rotation shaft according to the level signal; determining the duration between at least three adjacent two high-level signals in one rotation period according to the level signals; determining the end point moment of a reference time length meeting preset conditions in at least three time lengths; the time length with the starting time as the end time is recorded as the target time length; and judging the rotation direction to be detected, namely the rotation direction of the rotor, according to the target duration.

In this embodiment, since the order in which the eddy current sensor passes through the at least three grooves is different when the rotation shaft rotates in the first rotation direction and the second rotation direction, that is, the order in which the same length of time is detected is different when the rotation shaft rotates in the different rotation directions. Therefore, the reference time length as the sequence reference is selected from the plurality of time lengths in one rotation period according to the preset condition. And on the time axis, the next time period of the reference time period is recorded as a target time period for judging the rotation direction. The starting time of the target duration is the end time of the reference duration. Therefore, unified selection criteria can be set for the target duration, so that the rotation direction of the rotation shaft to be detected can be conveniently determined by using the target duration.

It will be appreciated that the preset condition is for selecting a duration from a plurality of durations. Since the angles of the sectors formed by the adjacent two grooves and the axis of the rotary shaft are different, that is, the distances between the adjacent two grooves are different. The time period for which the preset condition is satisfied may be any one of at least three time periods within one rotation period. The preset conditions comprise a maximum value, a minimum value, a middle value or an Nth duration in at least three durations, and the like, one value can be selected through the preset conditions, and the preset conditions can be reasonably set according to user habits.

In one embodiment, taking the first rotation direction as a counterclockwise direction as an example, the step of detecting the rotation direction of the rotor includes: according to the sampling signal when the rotating shaft rotates, determining the time difference of the detection of the adjacent two grooves by the eddy current sensor; selecting a target duration according to the time difference; whether the target duration is within a preset duration range or not, if so, determining that the rotation direction to be detected is a counterclockwise direction, and if not, determining that the rotation direction to be detected is a clockwise direction.

In this embodiment, after the target period is determined, the target period is compared with a preset period range when the rotation shaft is rotated counterclockwise. When the target time length is within the preset time length range, the difference between the detected target time length when the rotating shaft rotates in the rotation direction to be detected and the detected target time length when the preset rotating shaft rotates in the counterclockwise direction (the first rotation direction) is smaller, and the detected target time length can be approximately the same, and then the rotation direction to be detected can be determined to be the counterclockwise direction. Otherwise, it can be determined that the rotation direction to be measured is not counterclockwise, i.e., clockwise. Therefore, the automatic detection of the rotation direction of the rotating shaft is realized, the system fault of the magnetic suspension motor caused by the inversion of the magnetic suspension motor is effectively prevented, the service life of the magnetic suspension motor is prolonged, and the operation reliability of the magnetic suspension motor is improved.

The preset duration range is determined according to the level signal detected when the rotation shaft rotates in the counterclockwise direction under the same rotation speed condition.

For specific example, as shown in fig. 5, a schematic diagram of a rotating shaft 510, an eddy current sensor 520, at least three grooves 512, and a protective bearing 530.

Three grooves a1, a2 and a3 with the same size are designed on the rotating shaft. Groove a1 and groove a3 are axially 180 degrees apart, and groove a2 is at 135 degrees from groove a1, groove a2 being at 45 degrees to groove a3. When the rotation shaft rotates anticlockwise, when the groove a1 passes through the eddy current sensor, a waveform at the time t1 shown in fig. 7 is generated, and after the rotation shaft continues to rotate 135 degrees, the groove a2 passes through the eddy current sensor, and a waveform corresponding to the time t2 in fig. 7 is output. The rotation shaft continues to rotate anticlockwise by 45 degrees, and when the groove a3 passes through the eddy current sensor, the waveform at the time t3 is output. And the groove a1 is further intersected with an eddy current sensor by rotating 180 degrees anticlockwise, and the eddy current sensor obtains a signal which is a waveform corresponding to the time t 4. In fig. 7, signal 1 is a sampled signal, and signal 2 is a level signal after the sampled signal processing. At the time from time t1 to time t4, the rotation shaft completes one rotation, the rotation period is Δt _b(t4-t1)＝Δt_b(t5-t2)＝Δt_b(t6-t3), and at this time, the frequency (rotation speed) f _(t4-t1)＝1/Δt_(t4-t1)＝1/Δt_(t5-t2)＝1/Δt_(t6-t3) of the shaft rotation is determined, and f _(t4-t1) is set as the preset rotation speed. At this point Deltat _b(t4-t3)>Δt_b(t2-t1)>Δt_b(t3-t2). The preset condition is set to a minimum time length, that is, Δt _b(t3-t2) is set as the reference time length, and the time length after the reference time length Δt _b(t3-t2) on the time axis is Δt _b(t4-t3). Then t _b(t4-t3) + -k is taken as a preset duration range of anticlockwise direction under the preset rotating speed, k is the error amount, and can be set as required. When the rotating shaft rotates in the rotating direction to be detected and the rotating speed of the shaft is the preset rotating speed, if the determined target duration is within the range of t _b(t4-t3) +/-k, the rotating direction to be detected can be judged to be anticlockwise.

In one embodiment, taking the first rotation direction as a clockwise direction as an example, the step of detecting the rotation direction of the rotor includes: according to the sampling signal when the rotating shaft rotates, determining the time difference of the detection of the adjacent two grooves by the eddy current sensor; selecting a target duration according to the time difference; calculating the quotient of the target duration and the rotation period; determining a preset ratio range according to the included angles between the connecting lines of the central points of the two grooves corresponding to the target time length and the axis of the rotating shaft respectively when the rotating shaft rotates in the clockwise direction; whether the ratio is in a preset ratio range corresponding to the clockwise direction or not, if so, judging that the rotation direction to be detected is the clockwise direction, and if not, judging that the rotation direction to be detected is the anticlockwise direction.

In this embodiment, the target time length and the rotation period of the rotation shaft are divided to obtain the ratio of the target time length and the rotation period, that is, the duty ratio of the target time length in one rotation period. And determining the rotation direction to be detected according to a comparison result of the ratio and a preset ratio range corresponding to the first rotation direction.

Specifically, when the ratio is within the preset ratio range, it is indicated that the difference between the duty ratio of the target time length in the rotation period when the rotation shaft rotates in the rotation direction to be measured and the duty ratio of the target time length when the preset rotation shaft rotates in the clockwise direction is smaller, and the duty ratio is approximately the same, and it is determined that the rotation direction to be measured is clockwise. Under the condition that the ratio exceeds the preset ratio range, the rotation direction to be detected can be determined to be the reverse direction of the clockwise direction, namely the anticlockwise direction. Therefore, a required preset duration range is not required to be determined through the rotating speed of the rotating shaft, the step of rotating speed calculation is omitted, a large number of preset duration ranges are not required to be stored in advance for different rotating speeds, the data to be processed by the processor is small, and the requirement on the processor is reduced. Meanwhile, the automatic detection of the rotation direction of the rotating shaft can be realized, the system fault of the magnetic suspension motor caused by the inversion of the magnetic suspension motor is effectively prevented, the service life of the magnetic suspension motor is prolonged, and the operation reliability of the magnetic suspension motor is improved.

Further, before comparing the ratio with a preset ratio range, controlling the rotation of the rotation shaft in advance according to a first rotation direction, determining an included angle between the connecting lines of the central points of the two grooves forming the target time length and the axis of the rotation shaft, which are taken as a judging basis, dividing the included angle by 360 degrees, determining the preset ratio range corresponding to the clockwise direction according to the ratio and the error amount obtained by division calculation, and storing the preset ratio range in a system so as to judge the rotation direction to be detected of the rotation shaft through the preset ratio range, thereby realizing automatic detection of the rotation direction of the rotation shaft.

And similarly, the same configuration mode is adopted for the preset ratio range corresponding to the anticlockwise direction.

For example, as shown in fig. 5, the position of the groove a1 and the groove a3 on the axis are different by 180 °, and the position of the groove a2 is 135 ° compared to the position of the groove a1, and the angle of the groove a2 relative to the groove a3 is 45 °. When the rotary shaft rotates in the rotation direction to be measured, a waveform as shown in fig. 6 is generated. Wherein, the signal 1 is a sampling signal, and the signal 2 is a level signal after sampling signal processing. The rotation shaft completes one rotation from time t1 to time t 4. The rotation then continues to time t5, again producing a pulse waveform. Continuing the rotation repeats the previous process. The rotation period Δt _a(t4-t1)＝Δt_a(t5-t2)＝Δt_a(t6-t3) is the time required for one rotation of the shaft, and the frequency (rotation speed) of the shaft rotation is obtained from the time of one rotation, f=1/Δt _(t4-t1)＝1/Δt_(t5-t2)＝1/Δt_(t6-t3). At this time Δt _a(t2-t1)>Δt_a(t4-t3)>Δt_a(t3-t2), the maximum time length (preset condition) is taken as a starting decision point, i.e. each time length is calculated starting at time t 2. The subsequent comparison of the target duration Δt _a(t3-t2) with the entire period yields: the ratio M ₂＝Δt_a(t3-t2)Δt_a(t5-t2) =1/8. At this time, for the preset ratio range, on the rotation axis, the maximum duration corresponds to the groove a1 and the groove a3 having the largest included angle. When the rotation shaft is determined to rotate clockwise in advance, the eddy current sensor sequentially passes through the groove a1, the groove a3, the groove a2 and the groove a1, and then two grooves corresponding to the target time length are the groove a3 and the groove a2 respectively, so that the preset ratio range (alpha/360 DEG) which corresponds clockwise is determined to be + -m, m is the error amount, the error amount can be set as required, and alpha is the included angle between the groove a3 and the groove a2 and the axis connecting line, namely 45 deg. Similarly, when the rotation shaft is determined to rotate anticlockwise, the eddy current sensor sequentially passes through the groove a1, the groove a2, the groove a3 and the groove a1, and then two grooves corresponding to target time length are the groove a2 and the groove a1 respectively, so that a preset ratio range (beta/360 DEG) is determined to be anticlockwise corresponding to the preset ratio range + -m, m is the error amount, the error amount can be set as required, and beta is the included angle between the groove a2 and the groove a1 and the axis connecting line, namely 135 deg. The clockwise direction of rotation to be measured can be determined by comparing M ₂ with a preset ratio range corresponding to clockwise/counterclockwise.

In one embodiment, the step of detecting the rotational direction of the rotor includes: acquiring a first sampling signal in the process that the rotating shaft rotates according to the rotation direction to be detected and a second sampling signal in the process that the rotating shaft rotates according to the opposite direction; comparing the target time length corresponding to the first sampling signal with the target time length corresponding to the second sampling signal; and judging the rotation direction to be detected according to the magnitude relation of the two.

In this embodiment, since the order in which the eddy current sensor passes through the at least three grooves is different when the rotation shaft rotates in the first rotation direction and the second rotation direction, that is, the size of the target period after the reference period on the time axis is different when the rotation shaft rotates in the different rotation directions. Therefore, the rotation direction of the rotation shaft can also be detected by the magnitude relation of the target time length when the rotation shaft rotates in the opposite direction.

Specifically, the rotating shaft is controlled to operate according to the rotating direction to be detected, and meanwhile, a first sampling signal is acquired through the eddy current sensor, and the target time length serving as a judging basis in the rotating direction to be detected is determined according to the first sampling signal. The rotating shaft is then controlled to run again in the opposite direction, wherein the opposite direction is opposite to the direction of rotation to be measured. Meanwhile, a second sampling signal is acquired through the eddy current sensor, and the target time length used as a judgment basis in the rotation process in the opposite direction is determined according to the second sampling signal. Comparing the target time lengths corresponding to the two sampling signals in different rotation states, determining the size relation between the two sampling signals, and determining whether the rotation direction to be detected is the first rotation direction or the second rotation direction according to the size relation.

Further, a preset magnitude relation related to the first rotation direction is pre-stored in the system. Determining a rotation direction to be measured according to the magnitude relation, specifically comprising: and under the condition that the magnitude relation accords with the preset magnitude relation, judging that the rotation direction to be detected is the first rotation direction, and judging that the opposite direction of the rotation direction to be detected is the second rotation direction. And under the condition that the magnitude relation does not accord with the preset magnitude relation, judging that the rotation direction to be detected is the second rotation direction, and judging that the opposite direction of the rotation direction to be detected is the first rotation direction. And further, the state of the rotating shaft is detected in real time, so that the precise maintenance is facilitated, the overhaul and maintenance cost is reduced, the problem that the service life of the magnetic levitation motor is reduced or even damaged due to the fact that the rotating shaft is not prevented from rotating in time is avoided, and the service life and the reliability of the magnetic levitation motor are indirectly improved.

The preset magnitude relation may be determined based on a first reference level signal obtained when the rotation shaft rotates in the first rotation direction and a second reference level signal obtained when the rotation shaft rotates in the second rotation direction.

For example, as shown in fig. 5, three grooves a1, a2, and a3 of the same size are designed on the rotation shaft. The position of the groove a1 and the groove a3 are different by 180 DEG on the rotation axis, the position of the groove a2 is 135 DEG compared with the position of the groove a1, and the angle of the groove a2 relative to the groove a3 is 45 deg. Take the counterclockwise first direction of rotation as an example. The rotating shaft is controlled to rotate anticlockwise, a sampling signal sampled by the eddy current sensor is shown as a signal 1 in fig. 7, the sampling signal is processed by the sampling circuit and the signal processing module to obtain a level signal of a signal 2 in fig. 7, and the rotation period deltat _b(t4-t1)＝Δt_b(t5-t2)＝Δt_b(t6-t3) is the time required by one rotation of the shaft. At this time Δt _b(t4-t3)>Δt_b(t2-t1)>Δt_b(t3-t2), the minimum time length (preset condition) is taken as a starting decision point, namely, each time length is calculated starting at time t3, and the subsequent target time length is Δt _b(t4-t3). When the rotation shaft is controlled to rotate clockwise, a sampling signal sampled by the eddy current sensor is shown as a signal 1 in fig. 6, and the sampling signal is processed by the sampling circuit and the signal processing module to obtain a level signal (a second reference level signal) of a signal 2 in fig. 6, wherein a rotation period deltat _a(t4-t1)＝Δt_a(t5-t2)＝Δt_a(t6-t3) is the time required for one rotation of the shaft. At this time Δt _a(t2-t1)>Δt_a(t4-t3)>Δt_a(t3-t2), the minimum time length (preset condition) is taken as a starting decision point, namely, each time length is calculated starting at time t3, and the subsequent target time length is Δt _a(t4-t3). It can be seen that when the clock signal rotates clockwise and counterclockwise, Δt _b(t4-t3)＞Δt_a(t4-t3) is configured, where the preset size relationship is that the target time length corresponding to the first sampling signal is longer than the target time length corresponding to the second sampling signal.

In one embodiment, the step of detecting the rotational direction of the rotor includes: in the process that the rotating shaft rotates in the rotating direction to be detected, processing a sampling signal of the rotating shaft to obtain a level signal corresponding to the sampling signal; determining a rotation period of the rotation shaft according to the level signal; calculating the frequency of the rotating shaft according to the rotating period; determining the duration between at least three adjacent two high-level signals in one rotation period according to the level signals; selecting a target duration from at least three durations; and determining the rotation direction to be detected of the rotating shaft according to the target duration.

In this embodiment, the frequency of the rotation shaft, i.e. the rotational speed of the rotation shaft, is related to the rotation period. Specifically, the frequency of the rotation shaft is a ratio of 1 to the rotation period. Through the embodiment, the rotation period and the rotation direction can be determined through the sampling signals fed back by the rotation shaft, the running frequency of the rotation shaft can be analyzed, a large amount of data support is provided for a user to control the magnetic levitation motor, the user can design an empty box strategy of the magnetic levitation motor conveniently, and the work efficiency of the magnetic levitation motor is improved.

In the above embodiment, the electric appliance 400 includes an air conditioner.

Example five

In one embodiment, the present invention provides a readable storage medium having stored thereon a program or instructions which, when executed by a processor, implement the steps of a method of controlling a frequency converter as described in any one of the above.

The embodiment of the present application proposes a readable storage medium, where a program or an instruction stored on the readable storage medium, when executed by a processor, implements the steps of the method for controlling a frequency converter according to any one of the foregoing, and therefore, the readable storage medium has all the beneficial technical effects of the method for controlling a frequency converter according to any one of the foregoing, which are not described herein again.

In the description of the present invention, the term "plurality" means two or more, unless explicitly defined otherwise, the orientation or positional relationship indicated by the terms "upper", "lower", etc. are based on the orientation or positional relationship shown in the drawings, merely for convenience of description of the present invention and to simplify the description, and do not indicate or imply that the apparatus or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention; the terms "coupled," "mounted," "secured," and the like are to be construed broadly, and may be fixedly coupled, detachably coupled, or integrally connected, for example; can be directly connected or indirectly connected through an intermediate medium. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

In the description of the present invention, the terms "one embodiment," "some embodiments," "particular embodiments," and the like, mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In the present invention, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The control method of the frequency converter is characterized in that the frequency converter is connected with a magnetic suspension motor, and the control method of the frequency converter comprises the following steps:

Acquiring the rotation direction of a rotor of the magnetic suspension motor;

Based on the rotor reversal, the frequency converter is controlled to enter a power generation mode,

The magnetic levitation motor charges a capacitor in the frequency converter when the frequency converter operates in a power generation mode, and the bearing control device of the rotor drives the rotor to keep levitation under the power supply of the capacitor;

Based on the rotor reversal, the frequency converter is controlled to enter a power generation mode, and the method specifically comprises the following steps:

Acquiring the reverse rotation speed of the rotor;

And controlling the frequency converter to enter a power generation mode under the condition that the reverse rotation speed is greater than or equal to a preset rotation speed.

2. The control method of a frequency converter according to claim 1, characterized by further comprising, before controlling the frequency converter to enter a power generation mode:

and determining the rotor reversal of the magnetic levitation motor based on the fact that the rotation direction of the rotor is opposite to the preset direction.

3. The control method of a frequency converter according to claim 2, characterized by further comprising, before acquiring the rotation direction of the rotor of the magnetic levitation motor:

Acquiring a wire connection state between the frequency converter and the magnetic suspension motor;

determining that the wire connection state is abnormal based on the fact that the preset direction is inconsistent with the rotation direction corresponding to the wire connection state;

and determining that the wire connection state is normal based on the fact that the preset direction is consistent with the rotation direction corresponding to the wire connection state.

4. A control method of a frequency converter according to claim 3, wherein,

And outputting reminding information based on the abnormal connection state of the lead.

5. The utility model provides a controlling means of converter, its characterized in that, the converter is connected with magnetic suspension motor, controlling means of converter includes:

An acquisition unit for acquiring a rotation direction of a rotor of the magnetic levitation motor;

a control unit for controlling the inverter to enter a power generation mode based on the rotor reversal,

The control unit is specifically configured to:

Acquiring the reverse rotation speed of the rotor;

6. The control device of a frequency converter according to claim 5, wherein the control unit is further configured to:

7. The control device of a frequency converter according to claim 6, wherein the acquisition unit is further configured to:

8. The control device of a frequency converter according to claim 7, wherein the control unit is further configured to:

9. An electrical appliance, comprising:

a control device of a frequency converter according to any one of claims 5 to 8.

10. An electrical appliance, comprising:

A magnetic levitation motor having a rotor;

Bearing control means for driving the rotor in suspension;

a frequency converter connected to the magnetic levitation motor and the bearing control device for performing the steps of the control method of the frequency converter according to any of claims 1 to 4.

11. The appliance of claim 10, further comprising:

and the eddy current sensor is connected with the frequency converter and used for detecting the rotation direction and the reverse rotation speed of the rotor.

12. An appliance according to claim 10 or 11, wherein the appliance comprises an air conditioner.

13. A readable storage medium, characterized in that the readable storage medium has stored thereon a program or instructions which, when executed by a processor, implement the steps of the control method of a frequency converter according to any one of claims 1 to 4.