CN1077739C - Control system for three-phase motor - Google Patents

Control system for three-phase motor Download PDF

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CN1077739C
CN1077739C CN97116525A CN97116525A CN1077739C CN 1077739 C CN1077739 C CN 1077739C CN 97116525 A CN97116525 A CN 97116525A CN 97116525 A CN97116525 A CN 97116525A CN 1077739 C CN1077739 C CN 1077739C
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control
circuit
signal
output
phase
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CN1211851A (en
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甘新东
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Abstract

The present invention relates to a control system for a three-phase motor, which comprises a sampling and detecting device, a signal processing device, a single chip computer control device and a star/triangle switching control device. The control system can automatically switch the connecting mode of a motor winding according to load change and also has the functions of starting time selection, power selection and automatic protection of phase failure, overload, short circuit, excess voltage, under voltage, unbalance of three-phase voltage and other failures. The system can make a motor have a high running load rate and has the advantages of favorable energy saving effect, low cost and convenient use and maintenance. In order to avoid motor stopping accidents when the system fails, the system is provided with a spare hand control system.

Description

Control system for three-phase motor
Technical field
The present invention relates to the control of motor, relate more specifically to the three-phase alternating-current motor control system.
Background technology
The load factor of a large amount of alternating current motors that use is generally lower at present, causes the serious waste of electric energy.The energy savings policy of " exploitation is laid equal stress on saving, saves and puts prior " of country's proposition certainly leads to huge motive force to the exploitation of alternating current motor power-saving technology with application.Thereby, the starting of AC electrical mechanism, energy-conservation, protection are realized that Comprehensive Control also is a kind of inevitable trend.
The energy-saving control device of existing alternating current motor mainly contains two types: a kind of is simple star/delta switching device shifter, as Chinese patent CN1111409 number a kind of power-saving computerized protector for three-phase asynchronous electric machine has been proposed, though wherein control method is simple, but economize on electricity source rate is not high, and impulse current is bigger when switching, sometimes even produce stopping accident; Another kind is to adopt ac voltage regulator, promptly change the angle of flow of thyristor automatically according to the operating condition of motor, thereby realize energy-conservation by the terminal voltage that changes motor, the major defect of this class device is that electrical network is existed serious harmonic wave interference, and complex structure, cost are higher, on-the-spotly use, maintenance is also inconvenient, actual conditions show that this class device also is difficult to promote in the practical application.
Summary of the invention
Purpose of the present invention just is to overcome above-mentioned these deficiencies of the prior art, propose a kind of simple in structure, use, easy to maintenance, cost is low, electrical network is not had the harmonic wave interference, consumes the control system for three-phase motor that metal material is few, in light weight, floor space is little, load factor is high, energy-saving effect is remarkable and have the kinds of protect function.
For realizing above-mentioned goal of the invention, the present invention is made of following described technical scheme.Control system for three-phase motor of the present invention adopts the control core of single-chip microcomputer as system, comprises four major parts of control device that sampling one checkout gear, signal processing apparatus, monolithic processor control device, star/delta are switched, wherein:
1) described sampling-checkout gear includes: by comprising transformer B 1Voltage sampling-detecting unit at interior voltage sample circuit and voltage detecting 1 composition; II is by comprising resistance R 4～R 7And transformer B 2At interior three-phase imbalance sample circuit, three-phase imbalance testing circuit 2 and amplitude limiter D 5Three-phase imbalance sampling-the detecting unit of forming; III is by comprising current transformer LKA, LKB, LKC, resistance R 1, R 2, R 3With transformer B 3, B 4, B 5At interior three-phase current sample circuit 3, power selection circuitry 4 and amplitude limiter D 12Current sampling-detecting unit of forming.
Described voltage sampling-detecting unit, three-phase imbalance sampling-detecting unit, current sampling-detecting unit flow to described signal processing apparatus with voltage signal, three-phase imbalance signal and current signal respectively.
2) described signal processing apparatus comprises three essentially identical signal processing units 5,6,7 of circuit structure, each described signal processing unit is made up of the comparison circuit of two covers work independently of one another and output stage separately thereof, and each described comparison circuit also includes action threshold value adjuster W separately 1, W 2With Signal Monitor LED 1, LED 2, each described signal processing unit 5,6,7 flows to described monolithic processor control device with output signal separately respectively.
The output signal of described signal processing unit 5,6,7 includes three-phase imbalance signal, over-current signal, star connection signal, triangle connection signal, under-voltage signal and state and presses signal.
3) described monolithic processor control device includes: I is by single-chip microcomputer IC 5And accessory circuit, address latch IC 6And programmable read only memory IC 7The Single-chip Controlling unit of forming; II is used to preset the toggle switch K of start delay time 3III is by switching circuit BG 7～BG 12, output relay J 3, J 2, J 1And operating state display led 7～LED 11The output ON-OFF control circuit of forming 8,9,10;
Each output signal of described signal processing unit 5,6,7 is through described single-chip microcomputer IC 5The corresponding interface end flow to described Single-chip Controlling unit, described Single-chip Controlling unit is according to each signal of being carried by described signal processing unit 5,6,7 and by described toggle switch K 3Input preset time delayed signal.Pass through described single-chip microcomputer IC according to predetermined operation program 5The corresponding interface end control the work of described output ON- OFF control circuit 8,9,10;
4) described star/delta switching device shifter includes: i motor three phase winding A-X, B-Y, C-Z; Ii star connects control contactor CJY and triangle connects control contactor CJ △.
The excitation winding of described control contactor CJY and CJ △ is subjected to output relay J in the described output ON-OFF control circuit 10 1The control of transfer contact, thereby from two described control contactors of circuit assurance, can only have one to be energized simultaneously, when described star connection control contactor CJY is energized, its three couples of normally opened contact CJY 1-3Closure, (three pairs of normally opened contacts of CJ △ disconnect), three phase winding A-X of described motor, B-Y, C-Z are star and connect; Otherwise, when described triangle control contactor CJ △ is energized, its three couples of normally opened contact CJ △ 1-3Closure, three couples of normally opened contact CJY of CJY 1-3Disconnect three phase winding A-X of described motor, B-Y, C-Z connection triangular in shape.
In addition, output relay J in the described output ON-OFF control circuit 8 3Transfer contact be series in the electric power loop between the different terminals of the elementary winding of described transformer B1 and described control contactor CTY and CJ △ excitation winding; When obviously descending appears in line voltage, described output relay J 3Work, its transfer contact action is in order to guarantee the reliability of system works.
Output relay J in the described output ON-OFF control circuit [9] 2Normally opened contact also be series in the electric power loop of described control contactor CJY and CJ △ excitation winding; when faults such as overvoltage, under-voltage, imbalance of three-phase voltage and the phase failure, overload, short circuit occurring; described motor three phase windings and electrical network disconnect fully, thereby the right side under the realization failure condition is by protection.
In addition; for preventing to cause stopping accident owing to above-mentioned automatic control equipment breaks down; control system for three-phase motor of the present invention also has a standby manual overvide; this standby back dynamic control device, this standby manual overvide comprises an artificial automatic/hand change over switch K who is used to cut off single-chip microcomputer automatic control equipment power supply and connects standby manual overvide power supply 5, one by hand switch K 7, the hand switch control circuit formed of output switch circuit 11, one by time-base circuit IC 8And comprise time-delay adjuster RT 2At interior accessory circuit, inverter ic 9And the time-delay control apparatus of output switch circuit 12 compositions.
Output relay J in the described output switch circuit 11 5Normally opened contact be series in the electric power loop of described Motor Control contactor CJY and CJ △ excitation winding, in order to realize manually opened control to described motor.
Output relay J in the described output switch circuit 12 4Transfer contact also be series in the electric power loop of described Motor Control contactor CJY and CJ △ excitation winding, its effect with automatic control equipment described in output relay J 1Effect identical, be used to realize star/delta switching controls to motor.
Control system for three-phase motor of the present invention also has following technical characterictic:
1) in described Single-chip Controlling unit, increases and forbid starting sequence voluntarily, and be provided with one and reset K switch 4Link with described Single-chip Controlling unit,, describedly forbid that starting sequence will guarantee that system can not start voluntarily when electrical network is powered again voluntarily, have only to operate and reset K switch if in case the grid power blackout situation takes place 4, system could be started again, thereby avoids because the accident or the loss of powering and may cause again after having a power failure.
2) at the input and the described single-chip microcomputer IC of output switch circuit 9 described in the described unit machine control unit device 5Three-phase imbalance signal input interface end between connect Device in one-way on state D 100, be used for when the phase failure (quick-fried disconnected) situation occurring in advance, forbidding that motor is started as power safety.
3) the Signal Monitor LED in described signal processing unit 5,6,7 1, LEK 2Be optical display, and each optical display all adopts the color that differs from one another, as yellow, redness etc., in order to distinguish different types of fault, as three-phase imbalance, overcurrent ..., or different conditions, as the connection of showing one's color, triangle connect.
Described Signal Monitor can also comprise an acoustics display, is used to only rely on the sense of hearing and knows that promptly existing certain fault or abnormal conditions take place.
4) whole console switch choice device, various displays should be arranged on the guidance panel in the described control system for three-phase motor, so that operation and observation.
Motor control system of the present invention is through the check of operation and regular test shows, and the native system operation conditions is good, and performance meets the requirements fully.Switch to full-load run by zero load or light running, the response time is less than 1 second, and no current impacts during load changing.Native system energy-saving effect highly significant, average power saving rate reaches about 30%, and the highest power saving rate can reach 52.7%.
Because the present invention has the starting time selection function; the automatic protection functions of the power controlling selection function and the phase failure, overload, short circuit, overvoltage, under-voltage, imbalance of three-phase voltage etc.; it is variation automatic switchover motor winding connecting mode according to load for In-particular, makes the present invention to carry out comprehensive whole control to the starting of alternating current motor, energy-conservation, protection.
Below in conjunction with the content that each Figure of description is showed the working condition of control system for three-phase motor of the present invention is done more detailed description, wherein:
Description of drawings
Fig. 1 is the electrical schematic diagram of multi-function single-chip computer automatic control equipment in the control system for three-phase motor of the present invention;
Fig. 2 is the hand switch control circuit and the time-delay control electrical schematic diagram of standby manual overvide in the control system for three-phase motor of the present invention;
Fig. 3 is the control principle figure of described standby manual overvide.
Embodiment
The operation principle of native system automatic control equipment at first is described in conjunction with the content of Fig. 1.Formal prestart at first must be accomplished in system: 1) the power selection device in the power selection circuitry 4 is arranged on suitable power gear; 2) operation toggle switch K 3Select the start delay time; 3) check each threshold value adjuster W in the signal processing unit 5,6,7 1, W 2... do not adjust by giving fixed requirement.
During starting, Closing Switch K at first 1, the required power supply of system promptly is added to each power supply side of circuit, and display led 11Should be luminous.This moment is as display led 8Luminous, show that the power supply of electrical network three-phase voltage is normal, export circuit breaker J simultaneously 2Be energized its closing of contact, the work of Be Controlled motor starting.In the start delay time range, make output relay J by described Single-chip Controlling unit controls 1Be not energized display led 9Not luminous, and LED 10Luminous, it changes abstract contact and is in 1 end, connects the electric power loop of star control contact CJY, and CJY is energized, its three couples of normally opened contact CJY 1-3Closure, motor are in the star coupled situation, thereby realize the reduced voltage starting of motor.
After the starting time-delay finishes, be subjected to the control of described Single-chip Controlling unit, output relay J 1Be energized, at this moment display led 9Luminous and LED 10Not luminous, its transfer contact produces action and swings to 2 ends, and triangle control contactor CJ △ electric power loop is switched on, and star control contactor CJY electric power loop is cut off, so three couples of contact CJY of contactor CJY 1-3Disconnect, and three couples of normally opened contact CJ △ of CJ △ 1-3Closure, motor are in the triangle coupled situation, and after this motor enters the full voltage operation.
In the running of motor, the loading condition that control system is judged motor according to the performance number and the real-time current value that detects of user's selection when zero load or underloading, passes through relay J 1Control connects hornwork CJY action, and motor is star and connects, and moves with the step-down power save mode; At full load, be still and pass through relay J 1Control contactor CJ △ action, motor connection triangular in shape, thereby board full voltage, high efficiency mode move.
When in detected voltage, three-phase imbalance, the current value each surpasses when giving the scope of setting earlier Single-chip Controlling unit controls relay J 2Discharge display led 8Extinguish, its contact disconnects, and the power supply of control contactor CJY and CJ △ is cut off, thereby realizes the automatic protection of failure condition.
If obviously descending appears in line voltage, for example when 380 volts drop to 320 volts, Single-chip Controlling unit controls relay J 3Action, LED 7Luminous, its transfer contact turns to 2 ends by 1 end, be compensated so add to voltage not enough on contactor CJY and the CJ △ winding, thus the reliability of assurance system works.
For fear of actuating motor mistakenly under the situation that occurs the phase failure, between the input of output ON-OFF control circuit 9 and single-chip microcomputer three-phase imbalance signal input interface end, connect Device in one-way on state D 100When the phase failure occurring, the unbalanced signal end is low level, and relay is by J 2Discharge, its contact disconnects, thereby motor can not be started.
Referring now to Fig. 2 and Fig. 3.
When the automatic control section that comprises the Single-chip Controlling unit breaks down and motor need be sent out when working on, standby manual overvide is absolutely necessary., at first artificial automatic/hand change over switch should be pulled to manual " 1 " position from automatic " 2 " position, this moment, the power supply of control section was cut off automatically for this reason, and the power supply of manual control part is switched on.Before formal starting, should at first check time-delay adjuster RT in the delay control circuit 2Adjusted value whether correct, and press button switch K 6Delay circuit is resetted.During starting, hand control switch K closes 7, actuating of relay action J 5, its closing of contact LED 13Luminous, within the reference time delay of delay control circuit because relay J 4Do not work, its transformation energy point is in 1 end, connects the power supply of control contactor CJY, thereby presents the star connection, realizes the motor reduced voltage starting.When the time-delay process finishes relay J 4Action, LED 12Luminous, 2 ends are swung in its transfer contact, disconnect the power supply of CJY and connect the power supply of CJ △, connect so connect the passive triangle that switches to from star, and motor begins the full voltage operation.
As embodiment, the employed main circuit element of control system for three-phase motor of the present invention and each signal threshold value are done following suggestion:
1) as single-chip microcomputer IC 5Adopt 8031 single chip circuits;
2) as address latch IC 6Adopt 373 circuit;
3) as the IC of EPROM 7Adopt 2732 circuit;
4) when current detection value during greater than 1.2 to 1.8 times of rated value, protective circuit work is cut off the electricity supply.
5) when three-phase imbalance voltage greater than rated value 20% the time, protective circuit work is cut off the electricity supply.
6) when voltage bolt measured value greater than rated value 20% or less than rated value 20% the time, send alarm signal.
It will be apparent to those skilled in the art, the physical circuit of showing by Figure of description and participate in number only as an example with the principle and the basic comprising of explanation technical solution of the present invention, and be not limiting the scope of the invention.

Claims (3)

1, a kind of control system for three-phase motor includes the star/delta switching device shifter, the checkout gear of taking a sample, and signal processing apparatus, monolithic processor control device is characterized in that described star/delta switching control comprises:
1) described sampling-checkout gear includes:
I is by comprising transformer (B 1) voltage sampling-detecting unit of forming in interior voltage sample circuit and voltage detecting (1);
II is by comprising resistance (R 4)～(R 7) and transformer (B 2) at interior three-phase imbalance sample circuit, three-phase imbalance testing circuit (2) and amplitude limiter (D 5) the three-phase imbalance sampling-detecting unit formed;
III is by comprising current transformer (LKA), (LKB), (LKC), resistance (R 1), (R 2), (R 3) and transformer (B 3), (B 4), (B 5) at interior three-phase current sample circuit (3), power selection circuitry (4) and amplitude limiter (D 12) current sampling-detecting unit of forming; Described voltage sampling-detecting unit, three-phase imbalance sampling-detecting unit, current sampling-detecting unit flow to described signal processing apparatus with voltage signal, three-phase imbalance signal and current signal respectively;
2) described signal processing apparatus comprises three essentially identical signal processing units of circuit structure (5), (6), (7), each described signal processing unit is made up of the comparison circuit of two covers work independently of one another and output stage separately thereof, and each described comparison circuit also includes action threshold value adjuster (W separately 1), (W 2) ... and Signal Monitor (LED 1), (LED 2) ..., each described signal processing unit (5), (6), (7) flow to described monolithic processor control device with output signal separately respectively: the output signal of described signal processing unit (5), (6), (7) includes three-phase imbalance signal, over-current signal, star connection signal, triangle connection signal, under-voltage signal and state and presses signal;
3) described monolithic processor control device includes:
I is by single-chip microcomputer (IC 5) and accessory circuit, address latch (IC 6) and programmable read only memory (IC 7) the Single-chip Controlling unit formed;
II is used to preset the toggle switch (K of start delay time 3);
III is by switching circuit (BG 7)～(BG 12), output relay (J 3), (J 2), (J 1) and operating state display (LED 7)～(LED 11) output ON-OFF control circuit (8), (9), (10) formed;
Each output signal of described signal processing unit (5), (6), (7) is through described single-chip microcomputer (IC 5) the corresponding interface end flow to described Single-chip Controlling unit, described Single-chip Controlling unit is according to each signal of being carried by described signal processing unit (5), (6), (7) and by described toggle switch (K 3) input preset time delayed signal.Pass through described single-chip microcomputer (IC according to predetermined operation program 5) the corresponding interface end control the work of described output ON-OFF control circuit (8), (9), (10);
4) described star/delta switching device shifter includes:
I motor three phase windings (A-X), (B-Y), (C-Z);
II star connects control contactor (CJY) and triangle connects control contactor (CJY △);
The excitation winding of described control contactor (CJY) and (CJ △) is subjected to output relay J in the described output ON-OFF control circuit [10] 1The control of transfer contact, thereby from two described control contactors of circuit assurance, can only have one to be energized simultaneously, when described star connects control contactor (CJY) when being energized, its three couples of normally opened contact (CJY 1-3) closure, the three pairs of normally opened contacts of (CJ △) disconnect, three phase windings of described motor (A-X), (B-Y), (C-Z) be star to connect; Otherwise, when described triangle control contactor (CJ △) when being energized, its three couples of normally opened contact (CJ △ 1-3) closure, three couples of normally opened contact (CJY (CJY) 1-3) disconnect three phase windings of described motor (A-X), (B-Y), (C-Z) connection triangular in shape;
In addition, output relay (J in the described output ON-OFF control circuit [8] 3) transfer contact be series in the electric power loop between the different terminals of the elementary winding of described transformer (B1) and described control contactor (CTY) and (CJ △) excitation winding;
Output relay (J in the described output ON-OFF control circuit [9] 2) normally opened contact also be series in the electric power loop of described control contactor (CJY) and (CJ △) excitation winding.
2, control system for three-phase motor as claimed in claim 1, it is characterized in that: this system also has a standby manual overvide, and described standby manual overvide comprises an artificial automatic/hand change over switch (K who is used to cut off single-chip microcomputer automatic control equipment power supply and connects standby manual overvide power supply 5), one by hand switch (K 7), the hand switch control circuit formed of output switch circuit [11], one by time-base circuit (IC 8) and comprise time-delay adjustment (RT 2) at interior accessory circuit, inverter (IC 9) and the delay control circuit formed of output switch circuit [12];
Output relay (J in the described output switch circuit [11] 5) normally opened contact be series in the electric power loop of described Motor Control contactor (CJY) and (CJ △) excitation winding; Output relay (J in the described output switch circuit [12] 4) transfer contact also be series in the electric power loop of described Motor Control contactor (CJY) and (CJ △) excitation winding.
3, control system for three-phase motor as claimed in claim 1 or 2 is characterized in that:
1) in described Single-chip Controlling unit phase control unit, increases and forbid starting sequence voluntarily, and be provided with one and reset switch (K 4) link with described Single-chip Controlling unit;
2) at the input of output switch circuit described in the described monolithic processor control device [9] and (IC of described single-chip microcomputer 5) connect unidirectional conducting dress (D between the three-phase imbalance signal input interface end 100);
3) Signal Monitor in described signal processing unit [5], [6], [7] is optical display (LED 1), (LED 2) ... each optical display adopts the color that differs from one another;
4) described Signal Monitor also comprises an acoustics display;
5) whole console switch, choice device, various displays is arranged on the guidance panel in the described control system for three-phase motor.
CN97116525A 1997-09-12 1997-09-12 Control system for three-phase motor Expired - Fee Related CN1077739C (en)

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Application Number Priority Date Filing Date Title
CN97116525A CN1077739C (en) 1997-09-12 1997-09-12 Control system for three-phase motor

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Application Number Priority Date Filing Date Title
CN97116525A CN1077739C (en) 1997-09-12 1997-09-12 Control system for three-phase motor

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CN1077739C true CN1077739C (en) 2002-01-09

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102324734A (en) * 2011-09-14 2012-01-18 埃美圣龙(宁波)机械有限公司 Default phase protecting method and device for three-phase motor

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1111409A (en) * 1994-11-22 1995-11-08 张学俊 Power-saving computerized protector for three-phase asynchronous electric machine

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1111409A (en) * 1994-11-22 1995-11-08 张学俊 Power-saving computerized protector for three-phase asynchronous electric machine

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