CN113300636A - Motor star-delta conversion starting method and device and compressor system - Google Patents
Motor star-delta conversion starting method and device and compressor system Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P1/00—Arrangements for starting electric motors or dynamo-electric converters
- H02P1/16—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters
- H02P1/26—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters for starting an individual polyphase induction motor
- H02P1/32—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters for starting an individual polyphase induction motor by star-delta switching
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P1/00—Arrangements for starting electric motors or dynamo-electric converters
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- H02P1/022—Security devices, e.g. correct phase sequencing
Abstract
The invention relates to the technical field of motor control, and particularly provides a motor star-delta conversion starting method, a motor star-delta conversion starting device and a compressor system, aiming at solving the problem of how to safely and reliably complete the starting of a motor. The method comprises the steps of detecting the phase current of the motor in real time when the motor starts to operate in a star shape, calculating the deviation between the phase current and the rated current, judging whether the ratio of the deviation to the rated current is smaller than a preset first percentage, and determining whether to perform star-delta conversion on a motor winding according to the judgment result so as to finish the starting of the motor. If the ratio is larger than or equal to the preset first percentage, the difference between the current phase current and the rated current is larger, and the motor is not started, so that star-delta conversion is not performed; when the ratio is judged to be smaller than the preset first percentage, whether star-delta conversion is carried out or not is further judged according to the variable quantity of the phase current in a certain time period, and the motor is started, so that misjudgment caused by normal fluctuation of the phase current can be effectively avoided.
Description
Technical Field
The invention relates to the technical field of motor control, in particular to a motor star-delta conversion starting method, a motor star-delta conversion starting device and a compressor system.
Background
In the starting process of the motor, a large starting torque is needed from rest to a rated rotating speed, correspondingly generated starting current is also large, and in order to reduce the impact of the starting current on the motor, a star-delta conversion starting method is generally adopted to start the motor. Specifically, when the motor starts, the three-phase winding of the motor is switched to be in star connection, 380V voltage applied to the motor can be converted into 220V voltage through star starting, and under the condition that the impedance of the motor is not changed, the voltage is remarkably reduced, the starting current is greatly reduced, and large current impact cannot be caused on the motor. When the rotating speed of the motor under the star starting reaches the rated rotating speed, the three-phase winding of the motor is switched to be in angle connection, so that the 220V voltage applied to the motor is converted into 380V voltage, and the motor starting is completed. In the process, the operation time (the time for the motor to reach the rated rotating speed from rest) of the motor under the star-type starting is set before the motor leaves a factory and cannot be adjusted according to the actual operation condition of the motor, so that the situation that the motor is switched to the angle-type operation before the rated rotating speed (the motor does not complete the starting) is not reached due to factors such as large load and the like can exist, the voltage applied to the motor after the motor is switched to the angle-type operation is converted from 220V to 380V, the generated impact current far exceeds the bearable range of the contactor, the service life of the contactor is shortened, and the motor is damaged.
Accordingly, there is a need in the art for a new motor star delta switching start scheme to address the above problems.
Disclosure of Invention
In order to overcome the above-mentioned drawbacks, the present invention is proposed to provide a method, a device and a compressor system for starting a star-delta converter of a motor, which solve or at least partially solve the problem of how to safely and reliably start the motor.
In a first aspect, a method for starting star-delta conversion of a motor is provided, and the method includes:
switching a motor winding into star connection according to the received starting instruction, and then controlling the motor to start running;
detecting phase current in the running process of the motor in real time and calculating the deviation of the phase current and rated current;
and judging whether the ratio of the deviation to the rated current is smaller than a preset first percentage or not, and determining whether to perform star-delta conversion on a motor winding according to a judgment result so as to complete the starting of the motor.
In an embodiment of the foregoing method, "determining whether a ratio of the deviation to the rated current is smaller than a preset first percentage, and determining whether to perform star-delta conversion on a motor winding according to a determination result" specifically includes:
and if the ratio of the deviation to the rated current is greater than or equal to the preset first percentage, continuously maintaining the motor winding to be in star connection without carrying out star-to-angle conversion.
In an embodiment of the foregoing method, "determining whether a ratio of the deviation to the rated current is smaller than a preset first percentage, and determining whether to perform star-delta conversion on a motor winding according to a determination result" specifically includes:
if the ratio of the deviation to the rated current is smaller than the preset first percentage, carrying out star-delta conversion on a motor winding, switching the motor winding into angular connection, and completing the starting of the motor; alternatively, the first and second electrodes may be,
if the ratio of the deviation to the rated current is smaller than the preset first percentage, obtaining phase currents detected within a certain time period after the detection time of the phase currents corresponding to the ratio, and judging whether the variation delta It of each phase current within the certain time period is smaller than a preset second percentage; if so, carrying out star-delta conversion on the motor winding, switching the motor winding into angular connection, and completing the starting of the motor; if not, continuing to maintain the motor winding to be in star connection without star-to-delta conversion;
wherein the content of the first and second substances,
said ItAnd It-1Phase currents detected at the t-th and t-1-th times, respectively, within the certain period of time.
In one embodiment of the above method, the preset first percentage is ± 10%, and the preset second percentage is ± 5%.
In a second aspect, an electric machine star-delta conversion starting device is provided, the device comprising:
a motor operation control module configured to switch the motor winding to a star connection according to the received start instruction and then control the motor to start operation;
the current detection processing module is configured to detect phase current in the motor operation process in real time and calculate deviation of the phase current and rated current;
and the star-delta conversion judging module is configured to judge whether the ratio of the deviation to the rated current is smaller than a preset first percentage or not, and decide whether to perform star-delta conversion on a motor winding according to the judgment result so as to complete the starting of the motor.
In one embodiment of the above apparatus, the star-to-delta conversion determination module is configured to continue to maintain the motor windings in a star connection without performing star-to-delta conversion after determining that the ratio of the deviation to the rated current is greater than or equal to the preset first percentage.
In an embodiment of the above apparatus, the star-delta conversion determining module is configured to, after determining that the ratio of the deviation to the rated current is smaller than the preset first percentage, perform star-delta conversion on the motor winding, switch the motor winding to an angular connection, and complete the motor start; alternatively, the first and second electrodes may be,
the star-delta conversion determination module is configured to, after determining that the ratio of the deviation to the rated current is less than the preset first percentage:
if the ratio of the deviation to the rated current is smaller than the preset first percentage, obtaining the phase current detected within a certain time after the detection time of the phase current corresponding to the ratio, and judging the variation delta I of each phase current within the certain timetWhether all are less than a preset second percentage; if so, carrying out star-delta conversion on the motor winding, switching the motor winding into angular connection, and completing the starting of the motor; if not, continuing to maintain the motor winding to be in star connection without star-to-delta conversion;
wherein the content of the first and second substances,
said ItAnd It-1Phase currents detected at the t-th and t-1-th times, respectively, within the certain period of time.
In a third aspect, a compressor system is provided, where the system includes a compressor, a current detection device, and the motor star-delta switching start device in the foregoing embodiment;
the current detection means is configured to detect a phase current of the motor in the compressor and output the detected phase current to the motor star-delta conversion starting means;
the motor star-delta conversion starting device is configured to start the compressor according to the received compressor starting instruction and the phase current output by the current detection device.
In a fourth aspect, a storage device is provided, which stores a plurality of program codes, and the program codes are suitable for being loaded and executed by a processor to execute the motor star-delta conversion starting method of the above embodiment.
In a fifth aspect, a control device is provided, comprising a processor and a storage device, the storage device being adapted to store a plurality of program codes, the program codes being adapted to be loaded and run by the processor to perform the motor star-delta switching start-up method according to the above embodiments.
One or more technical schemes of the invention at least have one or more of the following beneficial effects:
in the technical scheme of the invention, when the motor starts to operate in a star shape (the motor windings are connected in a star shape), the phase current of the motor is detected in real time, the deviation between the phase current and the rated current is calculated, whether the ratio of the deviation to the rated current is less than a preset first percentage is judged, and whether star-delta conversion is carried out on the motor windings is determined according to the judgment result so as to finish the starting of the motor. If the ratio is larger than or equal to the preset first percentage, the difference between the current phase current and the rated current is larger, and the motor is not started, so that the motor winding needs to be continuously maintained to be in star connection, and star-delta conversion is not performed. If the value is less than the preset first percentage, the current phase current is close to the rated current, the phase current of the motor is closer to the rated current and tends to be stable along with further operation of the motor, and the rotating speed of the motor is also shown to be closer to the rated rotating speed, so that star-delta conversion can be performed on the motor, and the motor is started.
Further, when the ratio is judged to be smaller than the preset first percentage, whether star-delta conversion is carried out or not can be judged according to the variable quantity of the phase current in a certain time period, and the motor is started, so that misjudgment caused by normal fluctuation of the phase current can be effectively avoided. Specifically, phase currents detected within a certain time period after the detection time of the phase currents corresponding to the ratio are obtained, and whether the variation delta It of each phase current within the certain time period is smaller than a preset second percentage is judged; if so, carrying out star-delta conversion on the motor winding, switching the motor winding into angular connection, and completing the starting of the motor; if not, the motor winding is continuously maintained to be in star connection, and star-to-angle conversion is not carried out.
Drawings
Embodiments of the invention are described below with reference to the accompanying drawings, in which:
fig. 1 is a schematic diagram of main flow steps of a motor star-delta conversion starting method according to an embodiment of the invention;
fig. 2 is a schematic main structural diagram of a star-delta switching starting device of the motor according to an embodiment of the invention;
FIG. 3 is a schematic diagram of an application scenario of the present invention;
list of reference numerals:
11: a motor operation control module; 12: a current detection processing module; 13: and a star-delta conversion judging module.
Detailed Description
Some embodiments of the invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only for explaining the technical principle of the present invention, and are not intended to limit the scope of the present invention.
In the description of the present invention, a "module" or "processor" may include hardware, software, or a combination of both. A module may comprise hardware circuitry, various suitable sensors, communication ports, memory, may comprise software components such as program code, or may be a combination of software and hardware. The processor may be a central processing unit, microprocessor, image processor, digital signal processor, or any other suitable processor. The processor has data and/or signal processing functionality. The processor may be implemented in software, hardware, or a combination thereof. Non-transitory computer readable storage media include any suitable medium that can store program code, such as magnetic disks, hard disks, optical disks, flash memory, read-only memory, random-access memory, and the like. The term "a and/or B" denotes all possible combinations of a and B, such as a alone, B alone or a and B. The term "at least one A or B" or "at least one of A and B" means similar to "A and/or B" and may include only A, only B, or both A and B. The singular forms "a", "an" and "the" may include the plural forms as well.
In the star-delta switching starting process of the motor in the prior art, the running time of the motor under star starting is set before the motor leaves a factory and cannot be adjusted according to the actual running condition of the motor, so that the situation that the motor is switched to the angular running before reaching the rated rotating speed (incomplete starting) due to factors such as large load and the like may exist, the voltage applied to the motor after being switched to the angular running is converted from 220V to 380V, and the generated impact current far exceeds the bearable range of a star contactor (a contactor for switching a motor winding into star connection, such as a star contactor KM3 in fig. 3), so that the service life of the contactor is shortened, the motor is damaged, and safe and reliable motor starting cannot be realized.
In the embodiment of the invention, when the motor starts to operate in a star shape (the motor windings are connected in a star shape), the phase current of the motor can be detected in real time, the deviation between the phase current and the rated current is calculated, whether the ratio of the deviation to the rated current is smaller than a preset first percentage or not is judged, and whether star-delta conversion is carried out on the motor windings or not is determined according to the judgment result so as to complete the starting of the motor. If the ratio is larger than or equal to the preset first percentage, the difference between the current phase current and the rated current is larger, and the motor is not started, so that the motor winding needs to be continuously maintained to be in star connection, and star-delta conversion is not performed. If the ratio is smaller than the preset first percentage, the current phase current is close to the rated current, the phase current of the motor is closer to the rated current and tends to be stable along with further operation of the motor, and the rotating speed of the motor is also closer to the rated rotating speed, so that star-delta conversion can be performed on the motor, and the motor is started.
Further, since the phase current may fluctuate normally in actual operation, if it is determined whether to perform star-delta conversion only according to the comparison result between the ratio and the preset first percentage, erroneous determination may be caused. Therefore, when the ratio is judged to be smaller than the preset first percentage, the embodiment of the invention can judge whether to perform star-delta conversion according to the variation (fluctuation condition) of the phase current in a certain time period to complete the starting of the motor, so that the misjudgment caused by the normal fluctuation of the phase current can be effectively avoided.
Referring to fig. 3, fig. 3 is a schematic diagram of an application scenario of the present invention. As shown in fig. 3, the water-cooled screw chiller mainly comprises a screw compressor, a large-current and high-power motor is arranged in the screw compressor, a large starting torque is needed when the screw compressor is started, and in order to reduce the impact of starting current on the motor in the starting process, after a starting instruction of the compressor is received, the main contactor KM1 and the star contactor KM3 are controlled to be closed, the angular contactor KM2 is kept to be disconnected, a motor winding in the compressor is switched to be in star connection, and then the compressor is controlled to start to operate; and then, the W-phase current in the running process of the compressor is detected in real time through a current detection device, the running state of the compressor is judged according to the deviation of the W-phase current and the rated current, and if the W-phase current is close to the rated current, the star contactor KM3 is controlled to be disconnected and the corner contactor KM2 is controlled to be closed, the motor winding is switched to be in corner connection, and the starting of the compressor is completed. The power supply contactor QF is used for switching on or switching off a power supply circuit between a power supply and the compressor.
Referring to fig. 1, fig. 1 is a diagram of a star-delta switching start method of a motor according to an embodiment of the invention. As shown in fig. 1, the method for starting star-delta conversion of a motor in the embodiment of the present invention may include the following steps:
step S101: and switching the motor winding into star connection according to the received starting instruction, and then controlling the motor to start running.
The star connection is a connection mode in which the ends of three-phase windings of a three-phase motor are connected together to form a common point, and then one end wire is respectively led out from the head ends of the three-phase windings. The start command refers to a command for controlling the motor to start running after the motor is powered on.
The angle connection refers to a connection mode of connecting the tail end of each phase winding of the three-phase motor with the head end of the subsequent phase winding.
Step S102: and detecting the phase current in the running process of the motor in real time and calculating the deviation of the phase current and the rated current.
Rated current means the current at which the motor operates at rated voltage at rated power, if the phase current reaches the rated current indicating that the output power of the motor has reached the rated valueThe load can be normally driven with constant power, that is, the motor is started completely. In addition, since the phase current fluctuates when the motor is operated, the deviation between the phase current and the rated current may be a positive value or a negative value. The deviation of the phase current from the rated current can be expressed as Δ I ═ Ip-Ir，IpIs a phase current of p-phase, IrIs the rated current.
Step S103: and judging whether the ratio of the deviation to the rated current is smaller than a preset first percentage or not, and determining whether to perform star-delta conversion on the motor winding according to a judgment result so as to finish the starting of the motor. The ratio of the deviation to the rated current can be expressed as
The smaller the value of the preset first percentage, the better, if the preset first percentage is a smaller value, when the ratio k is smaller than the preset first percentage, it indicates that the phase current I ispAlready close to the rated current IrThe output power of the motor is already close to the rated power. Therefore, the motor winding can be switched into angle type connection according to star-delta conversion of the motor winding, and the motor starting is completed. When the ratio k is greater than or equal to a preset first percentage, phase current I is indicatedpHas not yet approached the rated current IrThe motor has not been started yet, and therefore star-delta conversion cannot be performed. An example is as follows: the preset first percentage is 10%.
Since the phase current may fluctuate normally in actual operation, if the star-delta conversion is determined only according to the comparison result between the ratio and the preset first percentage, an erroneous determination may be caused. Thus, in one embodiment, when the deviation k is less than the preset first percentage, it may be further determined whether to perform star-to-delta conversion by:
step 31: obtaining the phase current I corresponding to the ratio kpFor example, the phase current detected for a certain period of time, e.g., 5s, after the detection timing of (c).
Step 32: determining each phase current in the certain periodVariation amount DeltaItWhether all are less than a preset second percentage; if the amount of change Δ ItIf the second percentage is less than the preset second percentage, go to step 33; if the amount of change Δ ItIf the second percentage is greater than or equal to the predetermined second percentage, go to step 34.
Wherein the content of the first and second substances,
Itand It-1Phase currents detected at the t-th and t-1-th times, respectively, within the certain period of time.
The smaller the value of the preset second percentage is, the better, if the preset second percentage is a smaller value, when the variation amount delta ItLess than a second predetermined percentage, indicating phase current IpHas a relatively small fluctuation range and tends to be stable. When the amount of change Δ ItWhen the current is greater than or equal to a preset second percentage, the phase current I is indicatedpIs relatively large and does not yet tend to be stable, the deviation k being less than the preset first percentage possibly being due to the phase current IpIs caused by a large fluctuation. An example is as follows: the preset second percentage is 5%.
Step 33: and carrying out star-delta conversion on the motor winding, and switching the motor winding into angle type connection to finish the starting of the motor.
Step 34: and continuously maintaining the motor windings in star connection without star-to-delta conversion.
In the embodiment of the invention, when the ratio k is judged to be smaller than the preset first percentage, the variation delta I of the phase current in a certain time can be further determinedtWhether star-delta conversion is carried out or not is judged, the motor starting is completed, and misjudgment caused by normal fluctuation of phase current can be effectively avoided.
It should be noted that, although the foregoing embodiments describe each step in a specific sequence, those skilled in the art will understand that, in order to achieve the effect of the present invention, different steps do not necessarily need to be executed in such a sequence, and they may be executed simultaneously (in parallel) or in other sequences, and these changes are all within the protection scope of the present invention.
Referring to fig. 2, fig. 2 is a schematic structural diagram of a star-delta switching starting device of a motor according to an embodiment of the present invention. As shown in fig. 2, the star-delta conversion starting device of the motor in the embodiment of the present invention mainly includes a motor operation control module 11, a current detection processing module 12, and a star-delta conversion determination module 13. For simplicity, although a processor and memory are not shown in fig. 2, those skilled in the art will appreciate that the motor star delta switching activation device may be part of the processor and/or memory. For example, in some embodiments, one or more of the motor operation control module 11, the current detection processing module 12, and the star-to-delta conversion determination module 13 may be part of a processor. In some embodiments, these modules may correspond to a portion of the electronic circuitry in the processor that performs signal or data processing, respectively, and may also correspond to associated program code stored in a computer-readable medium (e.g., memory). In some embodiments, one or more of the motor operation control module 11, the current detection processing module 12, and the star-delta switching determination module 13 may be combined together into one module. In some embodiments, the motor operation control module 11 may be configured to switch the motor windings to the star connection according to the received start instruction, and then control the motor to start operation; the current detection processing module 12 may be configured to detect phase currents during operation of the motor in real time and calculate deviations of the phase currents from the rated currents; the star-delta conversion determination module 13 may be configured to determine whether a ratio of the deviation to the rated current is smaller than a preset first percentage, and determine whether to perform star-delta conversion on the motor winding according to the determination result to complete the motor start. In one embodiment, the description of the specific implementation function may be referred to in steps S101 to S103.
In one embodiment, the star-to-delta conversion determination module 13 may be configured to continue to maintain the motor windings in a star connection without performing star-to-delta conversion after determining that the ratio of the deviation to the rated current is greater than or equal to a preset first percentage. And after the ratio of the deviation to the rated current is judged to be smaller than a preset first percentage, carrying out star-delta conversion on the motor winding, switching the motor winding into angle type connection, and finishing the starting of the motor. In one embodiment, the description of the specific implementation function may be referred to in step S103.
In one embodiment, the star-to-delta conversion determination module 13 may be configured to perform the following operations after determining that the ratio of the deviation to the rated current is less than a preset first percentage:
if the ratio of the deviation to the rated current is smaller than a preset first percentage, phase current detected within a certain time period after the detection time of the phase current corresponding to the ratio is obtained, and the variation delta I of each phase current within the certain time period is judgedtWhether all are less than a preset second percentage; if so, carrying out star-delta conversion on the motor winding, switching the motor winding into angular connection, and completing the starting of the motor; if not, the motor winding is continuously maintained to be in star connection, and star-to-angle conversion is not carried out. In one embodiment, the specific implementation functions may be described in reference to steps 31-34.
The technical principles, the solved technical problems and the generated technical effects of the motor star-delta conversion starting device described above are similar to those of the embodiment of the motor star-delta conversion starting method shown in fig. 1, and it can be clearly understood by those skilled in the art that for convenience and simplicity of description, the specific working process and related descriptions of the motor star-delta conversion starting device may refer to the contents described in the embodiment of the motor star-delta conversion starting method, and are not described herein again.
Further, in an embodiment of the compressor system of the present invention, the compressor system may include a compressor, a current detection device, and the motor star-delta conversion starting device described in the above embodiment of the motor star-delta conversion starting device. The current detecting means may be configured to detect a phase current of the motor in the compressor and output the detected phase current to the motor star-delta conversion starting means, and the motor star-delta conversion starting means may be configured to start the compressor according to the received compressor start instruction and the phase current output by the current detecting means.
Further, in one embodiment of the storage device of the present invention, the storage device may store a plurality of program codes adapted to be loaded and run by a processor to perform the motor star transition start method described in the above embodiment of the motor star transition start method.
Further, in an embodiment of the control device of the present invention, the control device may comprise a processor and a storage device, the storage device being adapted to store a plurality of program codes, said program codes being adapted to be loaded by the processor and to run the motor star transition start method as described above for the embodiment of the motor star transition start method.
It will be understood by those skilled in the art that all or part of the flow of the method according to the above-described embodiment may be implemented by a computer program, which may be stored in a computer-readable storage medium and used to implement the steps of the above-described embodiments of the method when the computer program is executed by a processor. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer-readable medium may include: any entity or device capable of carrying said computer program code, media, usb disk, removable hard disk, magnetic diskette, optical disk, computer memory, read-only memory, random access memory, electrical carrier wave signals, telecommunication signals, software distribution media, etc. It should be noted that the computer readable medium may contain content that is subject to appropriate increase or decrease as required by legislation and patent practice in jurisdictions, for example, in some jurisdictions, computer readable media does not include electrical carrier signals and telecommunications signals as is required by legislation and patent practice.
Further, it should be understood that, since the modules are only configured to illustrate the functional units of the system of the present invention, the corresponding physical devices of the modules may be the processor itself, or a part of software, a part of hardware, or a part of a combination of software and hardware in the processor. Thus, the number of individual modules in the figures is merely illustrative.
Those skilled in the art will appreciate that the various modules in the system may be adaptively split or combined. Such splitting or combining of specific modules does not cause the technical solutions to deviate from the principle of the present invention, and therefore, the technical solutions after splitting or combining will fall within the protection scope of the present invention.
The embodiment of the invention can detect the phase current of the motor in real time and calculate the deviation between the phase current and the rated current when the motor starts to operate in a star shape (the motor windings are connected in a star shape), judge whether the ratio of the deviation to the rated current is less than a preset first percentage, and determine whether to perform star-delta conversion on the motor windings according to the judgment result so as to finish the starting of the motor. If the ratio is larger than or equal to the preset first percentage, the difference between the current phase current and the rated current is larger, and the motor is not started, so that the motor winding needs to be continuously maintained to be in star connection, and star-delta conversion is not performed. If the ratio is smaller than the preset first percentage, the current phase current is close to the rated current, the phase current of the motor is closer to the rated current and tends to be stable along with further operation of the motor, and the rotating speed of the motor is also closer to the rated rotating speed, so that star-delta conversion can be performed on the motor, and the motor is started. Further, when the ratio is judged to be smaller than the preset first percentage, the embodiment of the invention can judge whether to perform star-delta conversion according to the variation (fluctuation condition) of the phase current in a certain time period to complete the starting of the motor, so that the misjudgment caused by the normal fluctuation of the phase current can be effectively avoided.
So far, the technical solution of the present invention has been described with reference to one embodiment shown in the drawings, but it is easily understood by those skilled in the art that the scope of the present invention is obviously not limited to these specific embodiments. Equivalent changes or substitutions of related technical features can be made by those skilled in the art without departing from the principle of the invention, and the technical scheme after the changes or substitutions can fall into the protection scope of the invention.
Claims (10)
1. A star-delta conversion starting method of a motor is characterized by comprising the following steps:
switching a motor winding into star connection according to the received starting instruction, and then controlling the motor to start running;
detecting phase current in the running process of the motor in real time and calculating the deviation of the phase current and rated current;
and judging whether the ratio of the deviation to the rated current is smaller than a preset first percentage or not, and determining whether to perform star-delta conversion on a motor winding according to a judgment result so as to complete the starting of the motor.
2. The method for starting star-delta conversion of the motor according to claim 1, wherein the step of determining whether the ratio of the deviation to the rated current is smaller than a preset first percentage and determining whether to perform star-delta conversion on the motor winding according to the determination result specifically includes:
and if the ratio of the deviation to the rated current is greater than or equal to the preset first percentage, continuously maintaining the motor winding to be in star connection without carrying out star-to-angle conversion.
3. The method for starting star-delta conversion of the motor according to claim 2, wherein the step of determining whether the ratio of the deviation to the rated current is smaller than a preset first percentage and determining whether to perform star-delta conversion on the motor winding according to the determination result specifically includes:
if the ratio of the deviation to the rated current is smaller than the preset first percentage, carrying out star-delta conversion on a motor winding, switching the motor winding into angular connection, and completing the starting of the motor;
alternatively, the first and second electrodes may be,
if the ratio of the deviation to the rated current is smaller than the preset first percentage, obtaining the phase current detected within a certain time after the detection time of the phase current corresponding to the ratio, and judging the variation delta I of each phase current within the certain timetWhether all are less than the preset secondTwo percent; if so, carrying out star-delta conversion on the motor winding, switching the motor winding into angular connection, and completing the starting of the motor; if not, continuing to maintain the motor winding to be in star connection without star-to-delta conversion;
wherein the content of the first and second substances,
said ItAnd It-1Phase currents detected at the t-th and t-1-th times, respectively, within the certain period of time.
4. The electric motor star-delta transition start method of claim 3, wherein the preset first percentage is ± 10% and the preset second percentage is ± 5%.
5. An electric motor star-delta conversion starting device, characterized in that the device comprises:
a motor operation control module configured to switch the motor winding to a star connection according to the received start instruction and then control the motor to start operation;
the current detection processing module is configured to detect phase current in the motor operation process in real time and calculate deviation of the phase current and rated current;
and the star-delta conversion judging module is configured to judge whether the ratio of the deviation to the rated current is smaller than a preset first percentage or not, and decide whether to perform star-delta conversion on a motor winding according to the judgment result so as to complete the starting of the motor.
6. The motor star-delta conversion starting device according to claim 5, further comprising:
the star-delta conversion judging module is configured to continue to maintain the motor windings in star connection without star-delta conversion after judging that the ratio of the deviation to the rated current is greater than or equal to the preset first percentage.
7. The motor star-delta conversion starting device according to claim 6, further comprising:
the star-delta conversion judging module is configured to perform star-delta conversion on a motor winding after judging that the ratio of the deviation to the rated current is smaller than the preset first percentage, switch the motor winding into an angle type connection and complete the starting of the motor; alternatively, the first and second electrodes may be,
the star-delta conversion determination module is configured to, after determining that the ratio of the deviation to the rated current is less than the preset first percentage:
if the ratio of the deviation to the rated current is smaller than the preset first percentage, obtaining the phase current detected within a certain time after the detection time of the phase current corresponding to the ratio, and judging the variation delta I of each phase current within the certain timetWhether all are less than a preset second percentage; if so, carrying out star-delta conversion on the motor winding, switching the motor winding into angular connection, and completing the starting of the motor; if not, continuing to maintain the motor winding to be in star connection without star-to-delta conversion;
wherein the content of the first and second substances,
said ItAnd It-1Phase currents detected at the t-th and t-1-th times, respectively, within the certain period of time.
8. A compressor system, characterized in that the system comprises a compressor, a current detection device and a motor star-delta conversion starting device of any one of claims 5 to 7;
the current detection means is configured to detect a phase current of the motor in the compressor and output the detected phase current to the motor star-delta conversion starting means;
the motor star-delta conversion starting device is configured to start the compressor according to the received compressor starting instruction and the phase current output by the current detection device.
9. A storage device having a plurality of program codes stored therein, wherein the program codes are adapted to be loaded and run by a processor to perform the method for starting a star-delta conversion of an electric motor according to any one of claims 1 to 4.
10. A control apparatus comprising a processor and a memory device, the memory device adapted to store a plurality of program codes, wherein the program codes are adapted to be loaded and run by the processor to perform the method of starting a star-delta conversion of an electric motor of any of claims 1 to 4.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010113760.9A CN113300636B (en) | 2020-02-24 | Star-angle conversion starting method and device for motor and compressor system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010113760.9A CN113300636B (en) | 2020-02-24 | Star-angle conversion starting method and device for motor and compressor system |
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| Publication Number | Publication Date |
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| CN113300636A true CN113300636A (en) | 2021-08-24 |
| CN113300636B CN113300636B (en) | 2024-05-10 |
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| CN87212289U (en) * | 1987-08-27 | 1988-07-20 | 张惠芬 | Multifunctional power-saving controller for electrical machinery |
| JP2008144602A (en) * | 2006-12-06 | 2008-06-26 | Hitachi Industrial Equipment Systems Co Ltd | Starting device of screw compressor |
| CN101304225A (en) * | 2008-06-04 | 2008-11-12 | 沈阳天成自动化工程有限公司 | Motor energy-saving converting controller and control method |
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