CN113872467A

CN113872467A - Control method and device of frequency converter, electric appliance and readable storage medium

Info

Publication number: CN113872467A
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; Guangdong Midea HVAC Equipment Co Ltd
Priority date: 2021-09-30
Filing date: 2021-09-30
Publication date: 2021-12-31

Abstract

The invention provides a control method and a control 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 frequency converter is controlled to enter a power generation mode based on the rotor reversal, wherein when the frequency converter operates in the power generation mode, the magnetic suspension motor charges a capacitor in the frequency converter, and a bearing control device of the rotor drives the rotor to keep suspension under the power supply of the capacitor.

Description

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

Technical Field

The invention relates to the technical field of control, in particular to a control method and device of a frequency converter, an electric appliance and a readable storage medium.

Background

Under the influence of a refrigerant, the magnetic suspension motor can be reversely rotated, and at present, a control scheme for reversely rotating the magnetic suspension motor is not available, so that the magnetic suspension motor is easily damaged once the magnetic suspension motor is reversely rotated.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art or the related art.

To this end, a first aspect of the present invention provides a method for controlling a frequency converter.

In a second aspect of the present invention, a control apparatus for a frequency converter is provided.

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

In a fourth aspect of the present invention, a second electrical appliance is provided.

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

In view of the above, according to a first aspect of the present invention, there is provided a method for controlling a frequency converter, wherein the frequency converter is connected to a magnetic levitation motor, the method for controlling the frequency converter includes: 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 the rotor reversal, wherein when the frequency converter operates in the power generation mode, the magnetic suspension motor charges a capacitor in the frequency converter, and a bearing control device of the rotor drives the rotor to keep suspension under the power supply of the capacitor.

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

The technical scheme of this application is realized through following scheme, at magnetic suspension motor moving in-process, acquire the direction of rotation of rotor, if the rotor appears the reversal, then to the converter signals, so that the converter is under the condition of responding this signal, get into the electricity generation mode, under the electricity generation mode, rotor pivoted mechanical energy can change the electric energy into, at this moment, electric capacity in the converter can charge under the effect of this electric energy, electric capacity after charging has played the effect of the bearing controlling means power supply for the rotor, so that support bearing controlling means operation, make the rotor keep suspending.

In the scheme, the rotor can still keep suspension under the condition that the rotor rotates reversely, and the probability of contact friction between the rotor and the protective bearing is reduced, so that the heating and abrasion of the rotor and the protective 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 suspending the rotor can be realized by utilizing repulsion between different magnets.

In the technical scheme, the condition that the rotor rotates reversely can occur when the control system of the magnetic suspension motor is suddenly powered off, specifically, when the control system of the magnetic suspension motor is suddenly powered off, the magnetic suspension motor still operates according to the state between the power-off states, and the frequency converter can close the driving output due to the system power-off. Because the rotor has inertia in the rotation process, the rotor cannot stop rotating at the moment when the rotating speed is zero, but continues to rotate under the action of the inertia, and then the reverse rotation of the rotor is formed.

The technical scheme of this application is when the rotor reversal, gives the converter with the slew velocity of rotor reversal to the converter gets into the electricity generation mode after receiving the rotational speed of rotor reversal, converts the kinetic energy of rotor into the electric energy, so that ensures that bearing control device can work, keeps the rotor suspension, so that reduce the influence of rotor reversal to magnetic suspension motor life.

In one embodiment, the condition of the rotor being reversed may also be caused by the refrigerant flowing in the system in a reverse direction when the frequency converter and the magnetic levitation motor are not in operation at the same time, in which case the rotor is usually not levitated.

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

In the above technical solution, based on the rotor reversal, the frequency converter is controlled to enter the power generation mode, which specifically includes: 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 the preset rotation speed.

In the technical scheme, if the rotor is reversely rotated, 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 easily damaged.

The technical scheme of this application still obtains the reversal rotational speed of rotor before control converter gets into the power generation mode, if the reversal rotational speed is too high, if when exceeding preset rotational speed, also be safe rotational speed, think that the rotor is very easily with protection bearing contact and wearing and tearing under the state of not suspending, at this moment, control converter gets into the power generation mode to control rotor keeps suspending.

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

In addition, considering that the friction and the abrasion between the rotor and the protective bearing are within an acceptable range when the rotor rotates at a safe rotating speed, the magnetic suspension motor cannot generate high temperature and large abrasion, and the motor is finally damaged.

In any of the above technical solutions, before controlling the frequency converter to enter the power generation mode, the method further includes: and determining the rotor reversal of the magnetic suspension 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 rotates reversely needs to be judged, if the rotor does not rotate reversely, the rotor rotation direction is misjudged, namely when the rotor rotates forwards, the rotor is misjudged to rotate reversely, and when the rotor rotates forwards, the frequency converter is switched to a power generation mode, the rotor cannot be driven, so that the magnetic suspension motor is stopped, and the operation stability of the magnetic suspension motor is influenced.

In order to avoid the above situation, before the frequency converter is controlled to enter the power generation mode, the rotation direction of the rotor is obtained, the rotation direction is compared with the preset direction, and if the rotation direction is not consistent with the preset direction, that is, the rotation direction is opposite, the rotor is considered to be reversely rotated.

In the control scheme, whether the rotor is reversely rotated or not is judged, so that the reliability of the operation control of the magnetic suspension motor is improved.

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

In the technical scheme, 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 is inconsistent with the preset direction, so that 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 the process, the diagnosis of whether the connection between the frequency converter and the magnetic suspension motor is abnormal or not can be realized, and the problems caused by abnormal connection, such as the magnetic suspension motor fault, and the occupation of a large amount of maintenance time and workload, are reduced.

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

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 handle the abnormality 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 apparatus for a frequency converter, the frequency converter being connected to a magnetic levitation motor, the control apparatus comprising: the acquisition unit is used for acquiring the rotation direction of a rotor of the magnetic suspension motor; and the control unit is used for controlling the frequency converter to enter a power generation mode based on the rotor reverse rotation, wherein when the frequency converter operates in the power generation mode, the magnetic suspension motor charges a capacitor in the frequency converter, and a bearing control device of the rotor drives the rotor to keep suspended under the power supply of the capacitor.

The technical scheme of this application provides a controlling means of converter, uses this controlling means, can realize the protection of rotor, reduces the problem that magnetic levitation motor appears damaging easily when magnetic levitation motor reverses.

In the above technical solution, the control unit is specifically configured to: 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 the preset rotation speed.

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

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

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

According to a third aspect of the invention, there is provided an electrical appliance comprising: a control device for an inverter as defined in any one of the above.

The technical scheme of this application provides an electric appliance, and wherein, this electric appliance has the controlling means of the converter of any one of the aforesaid, therefore, electric appliance has the whole beneficial technological effects of the controlling means of the converter of any one of the aforesaid, here, no longer gives details.

According to a fourth aspect of the invention, there is provided an electrical appliance comprising: a magnetic levitation motor having a rotor; the bearing control device is used for driving the rotor to keep suspension; a frequency converter connected with the magnetic levitation motor and the bearing control device for performing the steps of the method for controlling a frequency converter as claimed in any one of the above.

The technical scheme of this application provides an electric appliance, wherein, this electric appliance has magnetic levitation motor, bearing control device and converter, and wherein, the step of the control method of the above-mentioned converter of converter execution is carried out to the converter, therefore, electric appliance has the whole beneficial technological effects of the control method of the above-mentioned converter of any item, and here, no longer give unnecessary details.

In the above technical solution, the method further comprises: and the eddy current sensor is connected with the frequency converter and is 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 invention, there is provided a readable storage medium on which a program or instructions are stored, which program or instructions, when executed by a processor, implement the steps of the control method of a frequency converter according to any one of the above.

The technical solution of the present application provides a readable storage medium, wherein a program or an instruction stored on the readable storage medium is executed by a processor to implement the steps of the control method of the frequency converter according to any one of the above descriptions, and therefore, the readable storage medium has all the beneficial technical effects of the control method of the frequency converter according to any one of the above descriptions, and details are not repeated herein.

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 above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a schematic flow chart illustrating a method for controlling a frequency converter according to an embodiment of the present invention;

FIG. 2 is a schematic flow chart illustrating the control of the inverter to enter a power generation mode based on rotor reversal in an embodiment of the present 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 invention;

FIG. 5 shows a schematic view of a rotating 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 the detection result of the eddy current sensor in the embodiment of the invention.

Wherein, the correspondence between the reference numbers and the names of the components in fig. 5 is:

510 rotating shaft, 512 groove, 520 eddy current sensor, 530 protecting bearing.

Detailed Description

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

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

Example one

According to an embodiment of the present invention, the present invention provides a method for controlling a frequency converter, wherein the frequency converter is connected to a magnetic levitation motor, as shown in fig. 1, the method for controlling the frequency converter comprises:

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

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

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

The embodiment of the application is realized through the following scheme, at magnetic suspension motor moving in-process, acquire the direction of rotation of rotor, if the rotor appears the reversal, then send the signal to the converter, so that the converter is under the circumstances of responding this signal, get into the electricity generation mode, under the electricity generation mode, rotor pivoted mechanical energy can change into the electric energy, at this moment, electric capacity in the converter can charge under the effect of this electric energy, electric capacity after charging has played the effect of supplying power for the bearing controlling means of rotor, so that support bearing controlling means operation, make the rotor keep suspending.

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

In the above embodiment, the condition that the rotor rotates reversely 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 a state between the power failures, and due to the system power failure, the frequency converter may close the driving output. Because the rotor has inertia in the rotation process, the rotor cannot stop rotating at the moment when the rotating speed is zero, but continues to rotate under the action of the inertia, and then the reverse rotation of the rotor is formed.

The embodiment of this application is exactly when the rotor reversal, gives the converter with the slew velocity of rotor reversal to the converter gets into the electricity generation mode after receiving the rotational speed of rotor reversal, converts the kinetic energy of rotor into the electric energy, so as to ensure that bearing control device can work, keeps the rotor suspension, so that reduces the influence of rotor reversal to magnetic suspension motor life.

In one embodiment, the rotor is reversed in a situation where the inverter and the magnetic levitation motor are not in operation at the same time, due to the refrigerant flowing in the system in a reverse direction, in which case the rotor is normally not levitated.

In the above embodiment, as shown in fig. 2, the controlling the frequency converter to enter the power generation mode based on the rotor reverse rotation specifically includes:

step 202, acquiring the reverse rotation speed of the 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 rotates reversely, 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.

The embodiment of the application still obtains the reversal rotational speed of rotor before controlling the converter and entering the electricity generation mode, if the reversal rotational speed is too high, if when exceeding preset rotational speed, also be the safe rotational speed, think that the rotor is very easily with protection bearing contact and wearing and tearing under the non-suspension state, at this moment, control converter and enter the electricity generation mode to control the rotor and keep suspending.

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

In this embodiment, whether the rotor rotates reversely needs to be determined, if not, the rotation direction of the rotor is erroneously determined, that is, when the rotor rotates forward, the rotor is erroneously determined to rotate reversely, and when the rotor is erroneously determined, the frequency converter is switched to the 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 obtaining the rotation direction of the rotor of the magnetic levitation motor, the method further includes: acquiring a wire connection state between a frequency converter and a magnetic suspension motor; determining that the connection state of the lead is abnormal based on the inconsistency of the preset direction and the rotation direction corresponding to the connection state of the lead; and determining that the wire connection state is normal based on the consistency of the preset direction and the rotation direction corresponding to the wire connection state.

In this embodiment, the preset direction is a direction in which the rotor rotates correctly, and when the connection state of the wire is abnormal, the rotation direction corresponding to the connection state of the wire is inconsistent with the preset direction, so that after the connection state of the wire is obtained, the rotation direction corresponding to the connection state of the wire can be compared with the preset direction to determine whether the connection of the wire is normal.

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

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 handle the abnormality 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 apparatus 300 for a frequency converter, the frequency converter being connected to a magnetic levitation motor, the control apparatus 300 for the frequency converter comprising: an obtaining unit 302, configured to obtain a rotation direction of a rotor of a magnetic levitation motor; and a control unit 304, configured to control the frequency converter to enter a power generation mode based on the rotor reverse rotation, where in the power generation mode of the frequency converter, the magnetic levitation motor charges a capacitor in the frequency converter, and a bearing control device of the rotor drives the rotor to keep levitation under power supply of the capacitor.

In the foregoing embodiment, the control unit 304 is specifically configured to: 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 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 suspension 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 a frequency converter and a magnetic suspension motor; determining that the connection state of the lead is abnormal based on the inconsistency of the preset direction and the rotation direction corresponding to the connection state of the lead; and determining that the wire connection state is normal based on the consistency of the preset direction and the rotation direction corresponding to the wire connection state.

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

EXAMPLE III

In one embodiment, the present invention provides an electrical appliance comprising: a control device for an inverter as defined in any one of the above.

The embodiment of the present application provides an electrical appliance, wherein the electrical appliance has the control device of any one of the frequency converters described above, and therefore, the electrical appliance has all the beneficial technical effects of the control device of any one of the frequency converters described above, and details are not repeated herein.

Example four

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

The embodiment of the present application provides an electrical appliance 400, wherein the electrical appliance 400 has a magnetic levitation motor 402, a bearing control device 404 and a frequency converter 406, wherein the frequency converter 406 executes the steps of the control method of any one of the frequency converters described above, and therefore, the electrical appliance 400 has all the beneficial technical effects of the control method of any one of the frequency converters described above, and details are not repeated herein.

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

In one embodiment, the rotor has a rotating shaft, the rotating shaft is provided with at least three grooves in the circumferential direction, the distance between the center points of two adjacent grooves in the at least three grooves is different, and the eddy current sensor is configured to detect a sampling signal when the rotating shaft rotates, wherein the step of detecting the rotation direction of the rotor includes: determining the time difference of two adjacent grooves in the at least three grooves passing through the eddy current sensor according to the sampling signal; determining a target duration in the time difference; and determining the rotation direction to be measured of the rotating shaft, namely the rotation direction of the rotor according to the target duration.

In this embodiment, when the rotating shaft rotates, a sampling signal acquired by the eddy current sensor is acquired while the rotating shaft is in a rotating state. The sampling information is analyzed to obtain the time difference when two adjacent grooves (recesses) on the rotation of 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 other adjacent groove along the rotation direction of the rotating shaft. The time difference comprises the time length of all possible eddy current sensors passing between the two grooves, and the time difference comprises at least three time lengths in one rotation period due to the fact that the rotating shaft is provided with at least three grooves, and each time length corresponds to two adjacent grooves in different groups respectively. And selecting a target time length serving as a judgment basis from the plurality of time lengths of the time difference according to a preset condition, and judging the rotation direction to be detected of the rotating shaft by taking the target time length as the basis.

With the above embodiment, the state of the rotation axis running can be reproduced in software by using the sampling signal detection and signal separation circuit for the running state of the rotation axis, and the rotation direction of the rotation axis can be analyzed. The problem that the rotating direction of the rotating shaft cannot be determined is solved, the system fault of the magnetic suspension motor caused by the fact that the magnetic suspension motor rotates reversely 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 need set up an eddy current sensor, can realize the detection of the direction of rotation axis, be favorable to reducing the detection cost, satisfy many-sided user demand of user.

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

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

It should be noted that the magnetic levitation motor is provided with a rotating shaft and an eddy current sensor located on the periphery side of the rotating shaft, and at least three grooves are provided on the rotating shaft in the circumferential direction of the rotating shaft. The distance between the center points of two adjacent grooves is different, that is, on the cross 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 forwards and backwards, the time required for the eddy current sensor to pass through the same groove is different, so that sampling signals detected by the forward rotation and the reverse rotation are different, and the rotating direction of the rotating shaft can be distinguished by the time difference between the two grooves during rotation. The eddy current sensor can periodically detect the rotating shaft according to a 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 needing to be detected can be determined through the sampling signal. The sampling period is not suitable to be too long or too short, the sampling signal of the rotating shaft rotating for 360 degrees cannot be completely collected in 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 comprises: processing the sampling signal of the rotating shaft in the process that the rotating shaft rotates in the rotating direction to be detected 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 time length between at least three adjacent high level signals in a rotation period according to the level signals; selecting a target time length from at least three time lengths; and judging the rotation direction to be detected, namely the rotation direction of the rotor according to the target time length.

In this embodiment, the rotation of the rotating shaft is controlled in accordance with the direction of rotation to be measured. When the groove on the rotating shaft passes through the eddy current sensor, a pulse signal is generated in a sampling signal of the eddy current sensor, and the position of the non-groove in the sampling signal is 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. Wherein a high level signal in the level signal indicates that the groove is in the detection area of the eddy current sensor, and a low level signal indicates that the groove is not in the detection area of the eddy current sensor.

Specifically, the processing of the sampling signal of the rotating shaft specifically comprises: outputting a high level signal based on the sampling value indicated by the sampling 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 value, wherein the first signal threshold value is greater than the second signal threshold value. Thereby determining whether the sampling signal is a high level signal or a low level signal by defining two parameters of the first signal threshold and the second signal threshold.

Further, because the angles of the sectors formed by the two adjacent grooves and the axis of the rotating shaft are different, that is, the distance between the center points of any two adjacent grooves is different, the time required for the eddy current sensor to pass through two adjacent grooves in different groups is different. When the time length between adjacent high level signals of the level signals is the same as a value, the eddy current sensor repeatedly collects pulse signals of two grooves, and the rotating shaft rotates one circle at the moment. So that the rotation period of the rotation axis can be determined using the level signal. The frequency of the rotating shaft can be calculated through the rotating period, a limit 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 suspension 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 to the time t5, t6, two pulse waveforms are generated again, the rotation is continued, the previous process is repeated, and delta t_(t4-t1)＝Δt_(t5-t2)＝Δt_(t6-t3)The time required for one rotation of the shaft (rotation period).

Further, each groove corresponds to one high level signal in the level signals, so in one period, the level signals will include at least three high level signals, the at least three grooves correspond to the at least three high level signals one to one, a time interval (duration) exists between every two adjacent high level signals, the at least three grooves can be divided into at least three groups of two adjacent grooves, and the corresponding level signals have at least three groups of two adjacent high level signals, that is, at least three durations exist, and the at least three durations are collectively referred to as time differences between two adjacent grooves detected by the eddy current sensor.

In one embodiment, the step of detecting the rotational direction of the rotor comprises: processing the sampling signal of the rotating shaft in the process that the rotating shaft rotates in the rotating direction to be detected 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 time length between at least three adjacent high level signals in a rotation period according to the level signals; determining the end point time of a reference time length which meets a preset condition in at least three time lengths; recording the time length of which the starting point time is the end point time as a target time length; and judging the rotation direction to be detected, namely the rotation direction of the rotor according to the target time length.

In this embodiment, since the rotating shaft rotates in the first rotating direction and the second rotating direction, the sequence of the eddy current sensor passing through the at least three grooves is different, that is, the sequence of detecting the same time duration is different when the rotating shaft rotates in the different rotating directions. Therefore, the reference time length to be sequentially referred to is selected from a plurality of time lengths in one rotation period according to a preset condition. And recording the next time length of the reference time length as a target time length for judging the rotation direction on the time axis. And the starting time of the target time length is the end time of the reference time length. Therefore, a uniform selection standard can be set for the target duration, so that the target duration is utilized to determine the rotation direction to be detected of the rotating shaft in the follow-up process.

It is understood that the preset condition is for selecting one time period from a plurality of time periods. Because the angles of the fan shapes formed by the two adjacent grooves and the axis of the rotating shaft are different, namely the distance between the two adjacent grooves is different. The time period satisfying the preset condition may be any one of at least three time periods within one rotation period. The preset conditions comprise the maximum value, the minimum value, the middle value or the Nth time length and the like in at least three time lengths, and only 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 the 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, the time difference of the eddy current sensor detecting two adjacent grooves is determined; selecting a target duration according to the time difference; and whether the target time length is within a preset time length range, if so, determining that the rotation direction to be detected is in the anticlockwise direction, and if not, determining that the rotation direction to be detected is in the clockwise direction.

In this embodiment, after the target time period is determined, the target time period is compared with a preset time period range when the rotary shaft is rotated counterclockwise. When the target duration is within the preset duration range, it is described that a difference between the target duration detected when the rotating shaft rotates in the to-be-detected rotating direction and the target duration detected when the preset rotating shaft rotates in the counterclockwise direction (the first rotating direction) is smaller and can be approximately the same, and it is determined that the to-be-detected rotating direction is the counterclockwise direction. Otherwise, it is 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 reversal 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.

It should be noted that the preset time length range is determined according to the level signal detected when the rotating shaft rotates in the counterclockwise direction under the same rotating speed condition.

By way of specific example, as shown in fig. 5, a schematic view 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. The groove a1 and the groove a3 are located at positions 180 DEG apart on the axis, concaveGroove a2 is then at 135 deg. compared to groove a1, and groove a2 is at 45 deg. relative to groove a 3. When the rotating shaft rotates counterclockwise, the groove a1 passes through the eddy current sensor to generate a waveform at the time point t1 shown in fig. 7, and after the rotating shaft rotates 135 degrees, the groove a2 passes through the eddy current sensor to output the waveform corresponding to the time point t2 in fig. 7. The rotating shaft continues to rotate counterclockwise by 45 °, and when the groove a3 passes through the eddy current sensor, the waveform at the time point t3 is output. And then the rotation is continued by 180 degrees, the groove a1 is intersected with the eddy current sensor, and the signal obtained by the eddy current sensor is the waveform corresponding to the t4 moment. In fig. 7, signal 1 is a sampling signal, and signal 2 is a level signal after the sampling signal is processed. From the time t1 to the time t4, the rotating shaft completes one rotation, and the rotation period is Δ t_b(t4-t1)＝Δt_b(t5-t2)＝Δt_b(t6-t3)At this time, the frequency (rotational speed) f of the shaft rotation is determined_(t4-t1)＝1/Δt_(t4-t1)＝1/Δt_(t5-t2)＝1/Δt_(t6-t3)A1 is to f_(t4-t1)As a preset rotation speed. At this time, Δ t_b(t4-t3)>Δt_b(t2-t1)>Δt_b(t3-t2). The preset condition is set to a minimum duration, i.e. at_b(t3-t2)As the reference time length, a reference time length Δ t on the time axis_b(t3-t2)The time period thereafter is Δ t_b(t4-t3). Then will t_b(t4-t3)And k is a preset duration range in the counterclockwise direction at the preset rotating speed, and k is an error amount and can be set as required. When the rotating shaft rotates in the rotating direction to be measured and the rotating speed of the shaft is a preset rotating speed, if the determined target time length is t_b(t4-t3)Within the range of +/-k, the rotation direction to be measured 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, the time difference of the eddy current sensor detecting two adjacent grooves is determined; 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 an included angle between the central points of the two grooves corresponding to the target duration and a connecting line of the axis of the rotating shaft when the rotating shaft rotates clockwise; and judging whether the ratio is in a preset ratio range corresponding to the clockwise direction, 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 duration and the rotation period of the rotating shaft are divided to obtain a ratio of the target duration and the rotation period, that is, a ratio of the target duration in one rotation period. And determining the rotation direction to be detected according to the comparison result of the ratio and the preset ratio range corresponding to the first rotation direction.

Specifically, when the ratio is within the preset ratio range, it is described that a difference between a ratio of the target duration in the rotation period when the rotation shaft rotates in the rotation direction to be measured and a ratio of the target duration when the rotation shaft rotates in the clockwise direction, which is set in advance, is small and can be approximately the same, and it is determined that the rotation direction to be measured is the clockwise direction. When the ratio is beyond the preset ratio range, the rotation direction to be measured can be determined to be the opposite direction of the clockwise direction, namely the anticlockwise direction. Therefore, the required preset time length range does not need to be determined through the rotating speed of the rotating shaft, the step of rotating speed calculation is omitted, a large number of preset time length ranges do not need to be stored in advance for different rotating speeds, the data volume 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 reverse rotation 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 the ratio is compared with a preset ratio range, the rotation of the rotating shaft is controlled in advance according to the first rotating direction, an included angle between the central point of each of the two grooves forming the target time length and the connecting line of the axis of the rotating shaft is determined as a basis for judgment, division is performed on the included angle and 360 degrees, the preset ratio range corresponding to the clockwise direction is determined according to the ratio and the error obtained by the division, and the preset ratio range is stored in the system, so that the rotating direction to be detected of the rotating shaft is judged through the preset ratio range, and the automatic detection of the rotating direction of the rotating shaft is realized.

Similarly, the same configuration mode is adopted for the range of the preset ratio corresponding to the counterclockwise direction.

Specifically, as shown in fig. 5, groove a1 and groove a3 are located 180 ° apart on the axis, groove a2 is located 135 ° compared to groove a1, and groove a2 is angled 45 ° relative to groove a 3. When the rotating shaft is rotated in the direction of rotation 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 processed by the sampling signal. From time t1 to time t4, the rotation shaft completes one rotation. Then, the rotation is continued to the time t5, and a pulse waveform is generated again. The previous process is repeated as the rotation continues. Period of rotation Δ t_a(t4-t1)＝Δt_a(t5-t2)＝Δt_a(t6-t3)The time required for one rotation of the shaft is obtained from the time of one rotation, and f is 1/Δ t_(t4-t1)＝1/Δt_(t5-t2)＝1/Δt_(t6-t3). At this time, Δ t_a(t2-t1)>Δt_a(t4-t3)>Δt_a(t3-t2)The calculation of each time period is started at time t2 with the maximum time period (preset condition) as the start determination point. Subsequent target duration Δ t_a(t3-t2)Comparing with the whole period to obtain: ratio M₂＝Δt_a(t3-t2)Δt_a(t5-t2)1/8. At this time, for the preset ratio range, the maximum duration corresponds to the groove a1 and the groove a3 having the largest included angle on the rotation axis. When the rotating shaft is determined to rotate clockwise in advance, the eddy current sensor passes through the groove a1 → the groove a3 → the groove a2 → the groove a1 in sequence, and two grooves corresponding to a target duration are respectively the groove a3 and the groove a2, so that the range of the preset ratio corresponding to the clockwise is determined to be (alpha/360 degrees) ± m, m is an error amount, and can be set as required, and alpha is an included angle between the groove a3 and the groove a2 and an axis line, namely 45 degrees. Similarly, when it is determined that the rotating shaft rotates counterclockwise, the eddy current sensor passes through the groove a1 → the groove a2 → the groove a3 → the groove a1, and the two grooves corresponding to the target time duration are the groove a2 and the groove a1, respectively, so as to determine that the preset ratio range corresponding to the counterclockwise is (β/360 °) ± m, where m is an error amount, and the error amount may be set as requiredAnd beta is the angle between groove a2 and groove a1 and the line of the axis, namely 135 degrees. By comparing M₂And the preset ratio range corresponding to clockwise/counterclockwise can determine that the rotation direction to be measured is clockwise.

In one embodiment, the step of detecting the rotational direction of the rotor comprises: acquiring a first sampling signal in the rotating process of a rotating shaft according to the rotating direction to be detected and a second sampling signal in the rotating process of the rotating shaft 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 size relationship of the two.

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

Specifically, the rotating shaft is controlled to rotate according to the rotating direction to be detected, meanwhile, a first sampling signal is acquired through the eddy current sensor, and the target time length serving as a judgment basis in the rotating direction to be detected is determined according to the first sampling signal. And controlling the rotating shaft to rotate again in the opposite direction, wherein the opposite direction is opposite to the rotating direction to be measured. Meanwhile, a second sampling signal is acquired through the eddy current sensor, and the target time length serving as a judgment basis in the process of rotating in the opposite direction is determined according to the second sampling signal. And comparing the target time lengths corresponding to the two sampling signals in different rotation states, determining the size relationship 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 relationship.

Further, the system is pre-stored with a predetermined magnitude relationship associated with the first rotational direction. Determining the rotation direction to be measured according to the size relationship, specifically comprising: and under the condition that the size relation accords with the preset size relation, judging that the rotation direction to be measured is a first rotation direction, and judging that the opposite direction of the rotation direction to be measured is a 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 measured is a second rotation direction, and judging that the opposite direction of the rotation direction to be measured is a first rotation direction. And then realize real-time detection rotation axis state to carry out accurate maintenance, reduced maintenance and maintenance cost, avoided not stopping in time that the rotation axis is reversed and lead to the problem that magnetic levitation motor life-span reduces even damage, indirectly improved magnetic levitation motor life-span and reliability.

The preset magnitude relationship may be determined based on a first reference level signal obtained when the rotation axis is rotated in the first rotation direction and a second reference level signal obtained when the rotation axis is rotated 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 rotary shaft. Groove a1 and groove a3 are located 180 ° apart on the axis of rotation, groove a2 is located 135 ° compared to groove a1, and the angle of groove a2 relative to groove a3 is 45 °. Take the counterclockwise direction as the first rotation direction as an example. Firstly, the rotating shaft is controlled to rotate anticlockwise, a sampling signal sampled by the eddy current sensor is shown as a signal 1 in figure 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 figure 7, and the rotating period delta t_b(t4-t1)＝Δt_b(t5-t2)＝Δt_b(t6-t3)The time required for one rotation of the shaft. At this time, Δ t_b(t4-t3)>Δt_b(t2-t1)>Δt_b(t3-t2)The minimum time length (preset condition) is used as a start judgment point, that is, the time lengths are calculated from the time t3, and the subsequent target time length is delta t_b(t4-t3). When the rotating shaft is controlled to rotate clockwise, the sampling signal sampled by the eddy current sensor is shown as signal 1 in fig. 6, the sampling signal is processed by the sampling circuit and the signal processing module to obtain a level signal (second reference level signal) of signal 2 in fig. 6, and the rotating period delta t is_a(t4-t1)＝Δt_a(t5-t2)＝Δt_a(t6-t3)The time required for one rotation of the shaft. At this time, Δ t_a(t2-t1)>Δt_a(t4-t3)>Δt_a(t3-t2)At minimum duration (preset)Condition) as the start determination point, i.e., the calculation of the respective time periods is started at time t3, and the subsequent target time period is Δ t_a(t4-t3). It can be seen that at clockwise and counterclockwise rotation, Δ t_b(t4-t3)＞Δt_a(t4-t3)If the preset size relationship is configured, the target duration corresponding to the first sampling signal is greater than the target duration corresponding to the second sampling signal.

In one embodiment, the step of detecting the rotational direction of the rotor comprises: processing the sampling signal of the rotating shaft in the process that the rotating shaft rotates in the rotating direction to be detected 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 time length between at least three adjacent high level signals in a rotation period according to the level signals; selecting a target time length from at least three time lengths; and determining the rotation direction to be measured of the rotating shaft according to the target time length.

In this embodiment, the frequency of the rotating shaft, i.e., the rotational speed of the rotating shaft, is related to the period of rotation. Specifically, the frequency of the rotating shaft is a ratio of 1 to the rotation period. Through the embodiment, not only can the rotation cycle and the rotation direction be determined through the sampling signal of rotation axis feedback, the operating frequency of rotation axis can also be analyzed, and then a large amount of data support is provided for the user to control the magnetic suspension motor, the user design magnetic suspension motor's of being convenient for empty box strategy is favorable to improving the work efficiency of magnetic suspension motor.

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

EXAMPLE five

In one embodiment, the invention provides a readable storage medium on which a program or instructions are stored, which when executed by a processor implement the steps of the method of controlling a frequency converter according to any one of the preceding claims.

An embodiment of the present application provides a readable storage medium, wherein a program or an instruction stored on the readable storage medium is executed by a processor to implement the steps of the control method of the frequency converter according to any one of the above descriptions, and therefore, the readable storage medium has all the beneficial technical effects of the control method of the frequency converter according to any one of the above descriptions, and details are not repeated herein.

In the description of the present invention, the terms "plurality" or "a plurality" refer to two or more, and unless otherwise specifically limited, the terms "upper", "lower", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are merely for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus should not be construed as limiting the present invention; the terms "connected," "mounted," "secured," and the like are to be construed broadly and include, for example, fixed connections, removable connections, or integral connections; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the description of the present invention, the description of the terms "one embodiment," "some embodiments," "specific embodiments," etc., means 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 terms used above 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, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A control method of a 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;

controlling the frequency converter to enter a generating mode based on the rotor reversal,

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

2. The method for controlling the inverter according to claim 1, wherein the controlling the inverter to enter a power generation mode based on the rotor reversal specifically comprises:

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.

3. The method for controlling an inverter according to claim 1 or 2, wherein before controlling the inverter to enter the power generation mode, the method further comprises:

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

4. The method for controlling a frequency converter according to claim 3, further comprising, before obtaining 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 inconsistency between the preset direction and the rotation direction corresponding to the wire connection state;

and determining that the wire connection state is normal based on the consistency of the preset direction and the rotation direction corresponding to the wire connection state.

5. The control method of a frequency converter according to claim 4,

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

6. A control device of a frequency converter, characterized in that the frequency converter is connected with a magnetic levitation motor, the control device of the frequency converter comprises:

the acquisition unit is used for acquiring the rotation direction of a rotor of the magnetic suspension motor;

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

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

acquiring the reverse rotation speed of the rotor;

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

9. The apparatus for controlling a frequency converter according to claim 8, wherein the obtaining unit is further configured to:

10. The control device of the frequency converter according to claim 9, wherein the control unit is further configured to:

11. An electrical appliance, comprising:

control device of a frequency converter according to any of claims 6 to 10.

12. An electrical appliance, comprising:

a magnetic levitation motor having a rotor;

the bearing control device is used for driving the rotor to keep suspension;

frequency converter connected with the magnetic levitation motor and the bearing control device for performing the steps of the method of controlling a frequency converter according to any of claims 1 to 5.

13. The electrical appliance according to claim 12, further comprising:

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

14. The appliance according to claim 12 or 13, characterized in that the appliance comprises an air conditioner.

15. A readable storage medium, characterized in that it stores 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 5.