CN111654226A - Induction motor control system - Google Patents
Induction motor control system Download PDFInfo
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- CN111654226A CN111654226A CN202010382601.9A CN202010382601A CN111654226A CN 111654226 A CN111654226 A CN 111654226A CN 202010382601 A CN202010382601 A CN 202010382601A CN 111654226 A CN111654226 A CN 111654226A
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- outlet terminal
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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
- H02P25/00—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details
- H02P25/16—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the circuit arrangement or by the kind of wiring
- H02P25/18—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the circuit arrangement or by the kind of wiring with arrangements for switching the windings, e.g. with mechanical switches or relays
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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
- H02P25/00—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details
- H02P25/16—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the circuit arrangement or by the kind of wiring
- H02P25/18—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the circuit arrangement or by the kind of wiring with arrangements for switching the windings, e.g. with mechanical switches or relays
- H02P25/184—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the circuit arrangement or by the kind of wiring with arrangements for switching the windings, e.g. with mechanical switches or relays wherein the motor speed is changed by switching from a delta to a star, e.g. wye, connection of its windings, or vice versa
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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
- H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
- H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Control Of Ac Motors In General (AREA)
Abstract
The invention provides an induction motor control system which is suitable for an efficient motor control system of oilfield equipment, can meet the requirement of higher starting torque when a motor is started by flexibly switching winding connection modes, adopts a switching power supply mode, not only retains the advantage that a frequency converter can flexibly adjust the rotating speed of the motor, but also ensures that the motor has higher efficiency and power factor under different operating conditions. In addition, the induction motor control system provided by the invention can flexibly adjust the number of turns of the three-phase motor winding according to the size of the load, thereby ensuring that the motor has higher efficiency and power factor under different loads, saving electric energy and bringing remarkable economic benefit.
Description
Technical Field
The invention relates to the technical field of motors and control thereof, in particular to an induction motor control system.
Background
Most induction motors used in oil fields have the problem that the operation condition of the motor is not matched with the capacity of the motor and the type of a frequency converter, so that the sizes of the induction motor and the matched frequency converter are increased, and the waste of energy is also caused.
Disclosure of Invention
Embodiments of the present invention provide an induction motor control system for solving technical problems in the prior art.
In order to achieve the purpose, the invention adopts the following technical scheme.
An induction motor control system is characterized by comprising an induction motor, a frequency converter, a winding switching unit, a plurality of main switches and a main controller; the induction motor and the frequency converter are mutually connected in parallel and are connected with an external power grid through a main switch circuit; the winding switching unit and the induction motor are mutually connected in parallel, and the main controller is connected with the winding switching unit in series;
the induction motor comprises an A-phase winding, a B-phase winding and a C-phase winding, wherein the A-phase winding, the B-phase winding and the C-phase winding are respectively connected with each other through a plurality of wire outlet ends; the winding switching unit is provided with a plurality of control switches; the main controller enables the induction motor to be connected with an external power grid circuit by switching the on-off of the main switches and the control switches, or enables the induction motor to be connected with the external power grid circuit through the frequency converter, and changes the turns of the A-phase winding, the B-phase winding and the C-phase winding of the induction motor.
Preferably, it is characterized in that:
the main switch comprises a first main switch, a second main switch and a third main switch; the induction motor and the frequency converter are respectively connected with the third main switch and the second main switch in series and then are connected with an external power grid through the first main switch circuit;
the A-phase winding comprises a first A-phase outlet terminal, a second A-phase outlet terminal, a third A-phase outlet terminal, a fourth A-phase outlet terminal and a fifth A-phase outlet terminal; the B-phase winding comprises a first B-phase outgoing line end, a second B-phase outgoing line end, a third B-phase outgoing line end, a fourth B-phase outgoing line end and a fifth B-phase outgoing line end; the C-phase winding comprises a first C-phase outlet terminal, a second C-phase outlet terminal, a third C-phase outlet terminal, a fourth C-phase outlet terminal and a fifth C-phase outlet terminal; the winding switching unit comprises a first control switch, a first alternating current contactor, a second alternating current contactor, a third alternating current contactor, a fourth alternating current contactor, a second control switch and a third control switch, wherein the first alternating current contactor, the second alternating current contactor, the third alternating current contactor and the fourth alternating current contactor are respectively connected with the first control switch in parallel, and the second control switch and the third control switch are respectively connected with the first alternating current contactor and the third alternating current contactor in series;
the first A-phase outlet terminal, the first B-phase outlet terminal and the first C-phase outlet terminal are respectively connected with a fourth C-phase outlet terminal, a fourth A-phase outlet terminal and a fourth B-phase outlet terminal through a second alternating current contactor circuit; the second A-phase outlet terminal, the second B-phase outlet terminal and the second C-phase outlet terminal are respectively connected with a third A-phase outlet terminal, a third B-phase outlet terminal and a third C-phase outlet terminal through a first alternating current contactor circuit; the third A-phase outlet terminal, the third B-phase outlet terminal and the third C-phase outlet terminal are respectively connected with the first A-phase outlet terminal, the first B-phase outlet terminal and the first C-phase outlet terminal through a third alternating current contactor circuit; the fourth A-phase outlet terminal, the fourth B-phase outlet terminal and the fourth C-phase outlet terminal are respectively connected with the fifth A-phase outlet terminal, the fifth B-phase outlet terminal and the fifth C-phase outlet terminal through a fourth alternating current contactor circuit;
the main controller switches on and off of the first alternating current contactors, the second alternating current contactors, the third alternating current contactors and the fourth alternating current contactors through the control switches, and the number of turns of the A-phase winding, the B-phase winding and the C-phase winding of the induction motor is changed.
Preferably, when the main controller controls the first main switch and the third main switch to be closed and the second main switch to be opened, the first control switch and the second control switch are closed, the coils of the first alternating current contactor and the second alternating current contactor are electrified, and the main contacts of the first alternating current contactor and the second alternating current contactor are closed.
Preferably, when the main controller controls the first main switch and the second main switch to be closed and the third main switch to be opened, the coil and the main contact of the second alternating current contactor are opened, the normally closed contact of the second alternating current contactor is closed, the coil of the fourth alternating current contactor is electrified, the main contact and the normally open contact are closed, and the normally closed contact of the fourth alternating current contactor is opened.
Preferably, the time relay is respectively connected with the second alternating current contactor and the fourth alternating current contactor through a normally closed contact and a normally open contact of the time relay; when the main controller controls the first main switch and the second main switch to be closed and the third main switch to be opened, the normally closed contact of the time relay is opened and the normally open contact of the time relay is closed.
Preferably, the winding switching unit further includes: the first current sensor is connected between the third A-phase outlet end and the fourth A-phase outlet end in series; the second current sensor is connected between the third B-phase outlet end and the fourth B-phase outlet end in series; and the main controller switches the on-off of the control switch according to the current signals acquired by the first current sensor and the second current sensor.
Preferably, the switching of the control switch by the main controller according to the current signals acquired by the first current sensor and the second current sensor comprises:
when the current signals acquired by the first current sensor and the second current sensor are increased, the main controller controls the second control switch to be switched off and the third control switch to be switched on; a coil of the first alternating current contactor is disconnected with the main contact, and the normally closed contact is closed; a coil of the third alternating current contactor is electrified, the main contact is closed, and the normally closed contact is opened;
when the current signals acquired by the first current sensor and the second current sensor are reduced, the main controller controls the second control switch to be closed and the third control switch to be opened;
when the current signals acquired by the first current sensor and the second current sensor are larger than the preset threshold value of the main controller, the main controller controls the first control switch to be switched off.
According to the technical scheme provided by the embodiment of the invention, the induction motor control system suitable for the oil field and capable of saving energy efficiently can meet the requirement of higher starting torque when the motor is started by flexibly switching the winding connection mode, and the advantage that the rotating speed of the motor can be flexibly adjusted by a frequency converter is reserved and the motor has higher efficiency and power factor under different operating conditions by adopting a power supply switching mode. In addition, the induction motor control system provided by the invention can flexibly adjust the number of turns of the three-phase motor winding according to the size of the load, thereby ensuring that the motor has higher efficiency and power factor under different loads, saving electric energy and bringing remarkable economic benefit.
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
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic block diagram of an induction motor control system according to the present invention.
Fig. 2 is a main circuit diagram of an induction motor control system according to the present invention.
Fig. 3 is a circuit diagram illustrating a control principle of an induction motor control system according to the present invention.
Fig. 4 is a winding connection diagram of an induction motor control system according to the present invention at startup.
Fig. 5 is a winding connection diagram of an induction motor control system according to the present invention during normal operation.
Fig. 6 is a winding connection diagram of an induction motor control system according to the present invention when the number of turns of the induction motor is changed.
In the figure:
101. induction motor 102 frequency converter 103, winding switching unit 104, main controller 105, first current sensor 106, second current sensor;
A1. a first phase A outlet terminal A2, a second phase A outlet terminal A3, a third phase A outlet terminal A4, a fourth phase A outlet terminal A5 and a fifth phase A outlet terminal;
B1. a first phase-B outgoing line end B2, a second phase-B outgoing line end B3, a third phase-B outgoing line end B4., a fourth phase-B outgoing line end B5. and a fifth phase-B outgoing line end;
C1. a first C-phase outlet terminal C2., a second C-phase outlet terminal C3., a third C-phase outlet terminal C4, a fourth C-phase outlet terminal C5., and a fifth C-phase outlet terminal;
km1, a first ac contactor km2, a second ac contactor km3, a third ac contactor km4, a fourth ac contactor;
s1, a first main switch S2, a second main switch S3 and a third main switch;
K1. the first control switch K2., the second control switch K3. and the third control switch.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may also be present. Further, "connected" or "coupled" as used herein may include wirelessly connected or coupled. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
For the convenience of understanding the embodiments of the present invention, the following description will be further explained by taking several specific embodiments as examples in conjunction with the drawings, and the embodiments are not to be construed as limiting the embodiments of the present invention.
Referring to fig. 1, the induction motor control system provided by the present invention is mainly used for oil field equipment, and includes an induction motor 101, a frequency converter 102, a winding switching unit 103, a plurality of main switches, and a main controller 104; the induction motor 101 and the frequency converter 102 are connected in parallel and are connected with an external power grid through a main switch circuit; the winding switching unit 103 and the induction motor 101 are connected in parallel, and the main controller 104 is connected in series with the winding switching unit 103;
the three-phase winding of the stator of the induction motor 101 comprises an A-phase winding, a B-phase winding and a C-phase winding, wherein the A-phase winding, the B-phase winding and the C-phase winding are respectively connected with each other through a plurality of wire outlet ends; the winding switching unit 103 has a plurality of control switches; the main controller 104 makes the induction motor 101 directly connected with an external power grid circuit or connected with the external power grid circuit through the frequency converter 102 by switching on and off of a plurality of main switches and control switches, and further changes the starting current and starting torque of the induction motor 101 by changing the number of turns of the A-phase winding, the B-phase winding and the C-phase winding of the induction motor 101; or the armature current of the induction motor 101 is further changed by changing the number of turns of the a-phase winding, the B-phase winding and the C-phase winding of the induction motor 101 according to the magnitude of the starting current of the induction motor 101.
Further, in some preferred embodiments, as shown in fig. 2, the main switches include a first main switch S1, a second main switch S2, and a third main switch S3; the induction motor 101 and the frequency converter 102 are respectively connected with a third main switch S3 and a second main switch S2 in series and then are connected with an external power grid through a first main switch S1 circuit;
the A-phase winding comprises a first A-phase outlet end A1, a second A-phase outlet end A2, a third A-phase outlet end A3, a fourth A-phase outlet end A4 and a fifth A-phase outlet end A5; the phase B winding comprises a first phase B outgoing line end B1, a second phase B outgoing line end B2, a third phase B outgoing line end B3, a fourth phase B outgoing line end B4 and a fifth phase B outgoing line end B5; the C-phase winding comprises a first C-phase outlet end C1, a second C-phase outlet end C2, a third C-phase outlet end C3, a fourth C-phase outlet end C4 and a fifth C-phase outlet end C5; the winding switching unit 103 includes a first control switch K1 and first, second, third and fourth ac contactors KM1, KM2, KM3 and KM4 respectively connected in parallel to the first control switch K1, and second and third control switches K2 and K3 respectively connected in series to the first and third ac contactors KM1 and 3. One end of a coil of the first alternating current contactor KM1 is connected with an external power grid through a first control switch K1, the other end of the coil is firstly connected to a normally closed contact KM31 of a third alternating current contactor KM3, then connected to a second control switch K2, and finally connected to the external power grid through a first control switch K1; one end of a coil of the third alternating current contactor KM3 is connected to a power grid through a first control switch K1, and the other end of the coil is firstly connected to a normally closed contact KM11 of a first alternating current contactor KM1, then connected to a third control switch K3, and finally connected to an external power grid through a first control switch K1; one end of a coil of the second alternating current contactor KM2 is connected to an external power grid through a first control switch K1, and the other end of the coil is firstly connected to a normally closed contact KM41 of a fourth alternating current contactor KM4 and then connected to the power grid through a first control switch K1; one end of a coil of the fourth alternating current contactor KM4 is connected to a power grid through a first control switch K1, and the other end of the coil is firstly connected to a normally closed contact KM21 of the second alternating current contactor KM2 and then connected to the power grid through a first control switch K1;
the first phase A outgoing line end A1, the first phase B outgoing line end B1 and the first phase C outgoing line end C1 are respectively connected with a fourth phase C outgoing line end C4, a fourth phase A outgoing line end A4 and a fourth phase B outgoing line end B4 through a second alternating current contactor KM2 circuit; the second phase A outgoing line end A2, the second phase B outgoing line end B2 and the second phase C outgoing line end C2 are respectively connected with a third phase A outgoing line end A3, a third phase B outgoing line end B3 and a third phase C outgoing line end C3 through a first alternating current contactor KM1 circuit; a third phase A outgoing line end A3, a third phase B outgoing line end B3 and a third phase C outgoing line end C3 are respectively connected with a first phase A outgoing line end A1, a first phase B outgoing line end B1 and a first phase C outgoing line end C1 through a third alternating current contactor KM3 circuit; and a fourth phase A outlet terminal A4, a fourth phase B outlet terminal B4 and a fourth phase C outlet terminal C4 are respectively connected with a fifth phase A outlet terminal A5, a fifth phase B outlet terminal B5 and a fifth phase C outlet terminal C5 through a fourth alternating current contactor KM4 circuit.
In the preferred embodiment of the present invention, the main controller 104 energizes or de-energizes the coil of the ac contactor, and further switches the connection form of the three-phase winding of the induction motor 101, and the manner of changing the number of turns of the three-phase winding can be implemented according to the working condition of the induction motor 101, for example, in some embodiments:
when the induction motor 101 is started in a deep well environment, as shown in fig. 2 and 3, the first main switch S1 and the third main switch S3 are first closed to connect the three-phase winding of the induction motor 101 to the grid (the second main switch S2 is open), the first control switch K1 and the second control switch K2 are closed, the coils of the first ac contactor KM1 and the second ac contactor KM2 are energized, and the main contacts of the first ac contactor KM1 and the second ac contactor KM2 are closed; as shown in fig. 4, the first a-phase outlet terminal a1 is connected to the fourth C-phase outlet terminal C4, the first B-phase outlet terminal B1 is connected to the fourth a-phase outlet terminal a4, and the first C-phase outlet terminal C1 is connected to the fourth B-phase outlet terminal B4, so that the connection mode of the three-phase winding of the induction motor 101 is an angular type; at this time, the induction motor 101 has a large starting current and a large starting torque.
In other embodiments, when the induction motor 101 is in a normal working condition, the main controller 104 controls the first main switch S1 and the second main switch S2 to be closed, the induction motor 101 is switched from the power supply of the power grid to the power supply of the frequency converter 102 (the third main switch S3 is opened), the coil of the second ac contactor KM2 is powered off, the main contacts are opened, the normally closed contact KM21 of the second ac contactor KM2 is closed, the coil of the fourth ac contactor KM4 is powered on, the main contacts and the normally open contact KM42 are closed, and the normally closed contact KM41 of the fourth ac contactor KM4 is opened. At this time, as shown in fig. 5, the connection mode of the three-phase windings of the induction motor 101 is star-shaped, and in this operation mode, the rotation speed of the induction motor can be flexibly adjusted by the frequency converter 102 to adapt to different operation conditions, and meanwhile, the motor is ensured to have higher efficiency and power factor.
In further preferred embodiments, the control system of the induction motor 101 also has a time relay, the coil of which is connected in parallel with the coil of the second ac contactor KM2, the coil of the second ac contactor KM2 being connected at one end to the external grid through the first control switch K1 and at the other end first to the normally closed contact KM41 of the fourth ac contactor KM4, then to the normally closed contact KT11 of the time relay and finally to the grid through the first control switch K1; one end of a coil of the fourth alternating current contactor KM4 is connected to a power grid through a first control switch K1, the other end of the coil is firstly connected to a normally closed contact KM21 of the second alternating current contactor KM2, then connected to a normally open contact KT12 of a time relay, and finally connected to the power grid through a first control switch K1; the normally open contact KM42 of the fourth AC contactor KM4 is connected in parallel with the normally open contact KT12 of the time relay. When the main controller 104 controls the first main switch S1 and the second main switch S2 to be closed and the third main switch S3 to be open, the normally closed contact of the time relay is opened and the normally open contact of the time relay is closed. The working process of the time relay is as follows: for example, when the induction motor 101 is in the normal working condition, the delay time of the time relay is set as the starting time of the motor, when the motor finishes starting, the motor enters the normal operation working condition, the normally closed contact KT11 of the time relay is opened, the normally open contact KT12 is closed, the coil of the second alternating current contactor KM2 is powered off, the main contact of the second alternating current contactor KM2 is opened, the normally closed contact KM21 of the second alternating current contactor KM2 is closed, the coil of the fourth alternating current contactor KM4 is powered on, the main contact of the fourth alternating current contactor KM4 is closed, the normally open contact KM42 of the fourth alternating current contactor KM4 is closed, and the normally closed contact KM41 of the fourth alternating current contactor KM4 is opened; at the same time, switch S2 is closed and switch S3 is opened, and the induction motor 101 is switched from mains supply to the frequency converter 102 supply.
In a preferred embodiment of the present invention, an operation mode for changing the number of winding turns according to load torques of the induction motor 101 under different working conditions is further provided, specifically, the winding switching unit 103 further includes: a first current sensor 105 connected in series between the third a-phase outlet terminal A3 and the fourth a-phase outlet terminal a 4; a second current sensor 106 connected in series between a third phase-B outlet terminal B3 and a fourth phase-B outlet terminal B4; the main controller 104 switches the on/off of the control switch according to the current signals acquired by the first current sensor 105 and the second current sensor 106;
when the load torque becomes large, that is, the current signals acquired by the first current sensor 105 and the second current sensor 106 increase, the main controller 104 controls the second control switch K2 to be opened and the third control switch K3 to be closed; the coil of the first alternating current contactor KM1 is disconnected from the main contact, and the normally closed contact KM11 is closed; a coil of the third alternating current contactor KM3 is electrified, a main contact is closed, and a normally closed contact KM31 is opened;
as shown in fig. 6, when the current signals obtained by the first current sensor 105 and the second current sensor 106 decrease after the induction motor 101 operates for a certain period of time, the main controller 104 controls the second control switch K2 to be closed, the third control switch K3 to be opened, and the induction motor 101 returns to the operating state of fig. 5;
when the current signals acquired by the first current sensor 105 and the second current sensor 106 are greater than the preset threshold of the main controller 104, that is, the circuit is over-current, the main controller 104 controls the first control switch K1 to be turned off, and the system stops running. In this embodiment, master controller 104 may select a digital signal processor model TMS320F 28335.
It will be understood by those skilled in the art that the coil, main contacts, normally closed and normally open contacts of the ac contactor, and normally closed and normally open contacts of the time relay are inherent components of the ac contactor itself.
In summary, the present invention provides an induction motor control system, which includes a three-phase induction motor, a frequency converter, a winding switching unit, a plurality of main switches, and a main controller; the induction motor and the frequency converter are mutually connected in parallel and are connected with an external power grid through a main switch circuit; the winding switching unit and the induction motor are mutually connected in parallel, and the main controller is connected with the winding switching unit in series; the main controller changes the starting current and starting torque of the induction motor by changing the number of turns of the three-phase winding of the induction motor. The induction motor control system provided by the invention has the following advantages:
firstly, in order to meet the requirement of higher starting torque required by the starting of the oil pumping unit, the three-phase winding of the induction motor is connected into an angle shape and the stator winding is directly connected into a power grid during starting so as to improve the starting current of the induction motor;
secondly, after the induction motor for the oil field is started, the load carried by the induction motor is reduced, so that the three-phase windings of the induction motor are connected into a star shape through a digital signal processor and an alternating current contactor, and meanwhile, the stator windings are switched from power supply of a power grid to power supply of a frequency converter, so that the rotating speed of the induction motor can be adjusted according to different operation conditions;
finally, a tap is led out from the three-phase winding of the induction motor, so that the number of turns of the winding of the induction motor is convenient to adjust, and the armature current of the induction motor can be more flexibly changed according to different loads. The invention effectively improves the operation efficiency and the power factor of the induction motor for the oil field under the complex working condition, reduces the rated capacity of the induction motor and the frequency converter thereof, and can bring remarkable economic benefit.
Those of ordinary skill in the art will understand that: the figures are merely schematic representations of one embodiment, and the blocks or flow diagrams in the figures are not necessarily required to practice the present invention.
From the above description of the embodiments, it is clear to those skilled in the art that the present invention can be implemented by software plus necessary general hardware platform. Based on such understanding, the technical solutions of the present invention may be embodied in the form of a software product, which may be stored in a storage medium, such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the method according to the embodiments or some parts of the embodiments.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for apparatus or system embodiments, since they are substantially similar to method embodiments, they are described in relative terms, as long as they are described in partial descriptions of method embodiments. The above-described embodiments of the apparatus and system are merely illustrative, and the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (7)
1. An induction motor control system is characterized by comprising an induction motor, a frequency converter, a winding switching unit, a plurality of main switches and a main controller; the induction motor and the frequency converter are mutually connected in parallel and are connected with an external power grid through the main switch circuit; the winding switching unit and the induction motor are mutually connected in parallel, and the main controller is connected with the winding switching unit in series;
the induction motor comprises an A-phase winding, a B-phase winding and a C-phase winding, wherein the A-phase winding, the B-phase winding and the C-phase winding are respectively connected with each other through a plurality of wire outlet ends; the winding switching unit is provided with a plurality of control switches; the main controller enables the induction motor to be connected with an external power grid circuit by switching on and off of the plurality of main switches and the control switches, or enables the induction motor to be connected with the external power grid circuit through the frequency converter, and changes the turn numbers of the A-phase winding, the B-phase winding and the C-phase winding of the induction motor.
2. The induction motor control system of claim 1, wherein:
the main switch comprises a first main switch, a second main switch and a third main switch; the induction motor and the frequency converter are respectively connected with the third main switch and the second main switch in series and then are connected with an external power grid through the first main switch circuit;
the A-phase winding comprises a first A-phase outlet terminal, a second A-phase outlet terminal, a third A-phase outlet terminal, a fourth A-phase outlet terminal and a fifth A-phase outlet terminal; the B-phase winding comprises a first B-phase outgoing line end, a second B-phase outgoing line end, a third B-phase outgoing line end, a fourth B-phase outgoing line end and a fifth B-phase outgoing line end; the C-phase winding comprises a first C-phase outlet terminal, a second C-phase outlet terminal, a third C-phase outlet terminal, a fourth C-phase outlet terminal and a fifth C-phase outlet terminal; the winding switching unit comprises a first control switch, a first alternating current contactor, a second alternating current contactor, a third alternating current contactor, a fourth alternating current contactor, a second control switch and a third control switch, wherein the first alternating current contactor, the second alternating current contactor, the third alternating current contactor and the fourth alternating current contactor are respectively connected with the first control switch in parallel, and the second control switch and the third control switch are respectively connected with the first alternating current contactor and the third alternating current contactor in series;
the first A-phase outlet terminal, the first B-phase outlet terminal and the first C-phase outlet terminal are respectively connected with the fourth C-phase outlet terminal, the fourth A-phase outlet terminal and the fourth B-phase outlet terminal through the second alternating current contactor circuit; the second A-phase outlet terminal, the second B-phase outlet terminal and the second C-phase outlet terminal are respectively connected with the third A-phase outlet terminal, the third B-phase outlet terminal and the third C-phase outlet terminal through the first alternating current contactor circuit; the third A-phase outlet terminal, the third B-phase outlet terminal and the third C-phase outlet terminal are respectively connected with the first A-phase outlet terminal, the first B-phase outlet terminal and the first C-phase outlet terminal through the third alternating current contactor circuit; the fourth A-phase outlet terminal, the fourth B-phase outlet terminal and the fourth C-phase outlet terminal are respectively connected with the fifth A-phase outlet terminal, the fifth B-phase outlet terminal and the fifth C-phase outlet terminal through the fourth alternating current contactor circuit;
and the main controller switches the first alternating current contactor, the second alternating current contactor, the third alternating current contactor and the fourth alternating current contactor to be switched on and off through the control switch, so that the number of turns of the A-phase winding, the B-phase winding and the C-phase winding of the induction motor is changed.
3. The induction motor control system of claim 2, wherein when the main controller controls the first main switch and the third main switch to be closed and the second main switch to be open, the first control switch and the second control switch are closed, the coils of the first ac contactor and the second ac contactor are energized, and the main contacts of the first ac contactor and the second ac contactor are closed.
4. The induction motor control system of claim 2, wherein when the main controller controls the first main switch and the second main switch to be closed and the third main switch to be open, the coil and the main contacts of the second ac contactor are open, the normally closed contacts of the second ac contactor are closed, the coil of the fourth ac contactor is energized, the main contacts and the normally open contacts are closed, and the normally closed contacts of the fourth ac contactor are open.
5. The induction motor control system according to claim 4, further comprising a time relay which is electrically connected to the second ac contactor and the fourth ac contactor through its normally closed contact and normally open contact, respectively; when the main controller controls the first main switch and the second main switch to be closed and the third main switch to be opened, the normally closed contact of the time relay is opened, and the normally open contact of the time relay is closed.
6. The induction motor control system of claim 2, wherein the winding switching unit further comprises: the first current sensor is connected between the third A-phase outlet end and the fourth A-phase outlet end in series; the second current sensor is connected between the third B-phase outlet end and the fourth B-phase outlet end in series; and the main controller switches the on-off of the control switch according to the current signals acquired by the first current sensor and the second current sensor.
7. The induction motor control system of claim 6, wherein the main controller switching the control switch on and off according to the current signals obtained by the first current sensor and the second current sensor comprises:
when the current signals acquired by the first current sensor and the second current sensor are increased, the main controller controls the second control switch to be switched off, and the third control switch is switched on; the coil of the first alternating current contactor is disconnected with the main contact, and the normally closed contact is closed; a coil of the third alternating current contactor is electrified, a main contact is closed, and a normally closed contact is opened;
when the current signals acquired by the first current sensor and the second current sensor are reduced, the main controller controls the second control switch to be closed, and the third control switch is opened;
when the current signals acquired by the first current sensor and the second current sensor are larger than the preset threshold value of the main controller, the main controller controls the first control switch to be switched off.
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| CN202010382601.9A CN111654226A (en) | 2020-05-08 | 2020-05-08 | Induction motor control system |
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| CN202010382601.9A CN111654226A (en) | 2020-05-08 | 2020-05-08 | Induction motor control system |
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| US5521471A (en) * | 1992-07-30 | 1996-05-28 | Yang; Tai-Her | Series (or compound) motor and control circuit for adjusting effective exciting turn ratio of series field winding according to rotational speed or load current |
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| CN104320040A (en) * | 2014-11-10 | 2015-01-28 | 吐鲁番地区万隆电气有限公司 | Triangular starting and star-shaped operation energy-saving control cabinet for pumping unit and control method thereof |
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| US20200067441A1 (en) * | 2016-12-07 | 2020-02-27 | Moteurs Leroy-Somer | Method for controlling the speed of a motor |
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|---|---|---|---|---|
| US5521471A (en) * | 1992-07-30 | 1996-05-28 | Yang; Tai-Her | Series (or compound) motor and control circuit for adjusting effective exciting turn ratio of series field winding according to rotational speed or load current |
| CN1949636A (en) * | 2005-10-12 | 2007-04-18 | 莫特斯·帕提 | Electrical machine |
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| US20200067441A1 (en) * | 2016-12-07 | 2020-02-27 | Moteurs Leroy-Somer | Method for controlling the speed of a motor |
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