CN1042882C - Phase-control method for stopping a drive smoothly - Google Patents
Phase-control method for stopping a drive smoothly Download PDFInfo
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- CN1042882C CN1042882C CN94194979A CN94194979A CN1042882C CN 1042882 C CN1042882 C CN 1042882C CN 94194979 A CN94194979 A CN 94194979A CN 94194979 A CN94194979 A CN 94194979A CN 1042882 C CN1042882 C CN 1042882C
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Abstract
The present invention relates to a phase-move control method for smoothly stopping a pump-driven device, which can avoid impact waves of pressure simultaneously. In order to avoid the impact waves of pressure, a moving-phase angle (D) between current and voltage of a motor is increased from zero watt-hour according to a straight-line slope by an alternating current regulator, and the phase angle (PA) descends and reaches a turning point (W). If the turning point (W) is detected according to the observation to the phase angle, then, the regulator is used for carrying out phase-move control according to a preset phase-angle rated value curve (R (t)) which carries out linear change following time at the time. Thus, the rotation number of the motor is not abruptly changed any longer, because the quick change of the phase angle is avoided.
Description
The present invention relates to an a kind of drive unit, particularly level and smooth phase-shifting control method of shutting down of pump drive of making, it is controlled according to the phase angle between the voltage and current of drive motors.
The phase-shifting control method that is used to make drive unit smoothly shut down peaceful srr promoter is known, wherein, regulates according to the phase angle between electric moter voltage and the current of electric.For the adjusting of level and smooth shutdown, special requirement has been proposed.Closing under the pump drive situation because the unexpected flow in pipe-line system changes, can produce pressure surge, it is also referred to as " water blaster ", and it not only may damage pipe-line system, and can be because the destruction on the acoustics cause interference effect.
So-called unexpected changes in flow rate at first occurs in, the drive unit of centrifugal pump, for example situation of directly being turn-offed by the motor contactor under opening.Simultaneously, the correlation below existing between revolution and the flow or between revolution variation and pressure variation.This flow is direct pump revolution in proportion to; And pressure change to be directly that revolution in proportion to changes square.
Under the situation of directly turn-offing a pump drive that has a three phase electric machine,, can in the shortest time, reach the inactive state of drive unit, because pump shows a high countertorque according to the load torque curve Pum of Fig. 1.In Fig. 1, put down in writing the relation of torque M and revolution n.Represent motor torque with Mom, represent the load torque, represent accelerating torque, represent turning over (limit) torque, represent specified operating point with N with Kim with Bm with Pum.Because the high countertorque Pum of pump can produce the variation of revolution n fast, it changes owing to above-mentioned relation causes a changes in flow rate and a pressure that impacts shape.Therefore cause a pressure wave, promptly known water blaster.Existing check-valves has increased the weight of this problem.
Described current of electric i when directly turn-offing in Fig. 2, electric moter voltage u and revolution n be curve over time.
As counter measure, used several different methods so far.By stopping immediately when a swing load can avoid drive unit turn-offing being provided with on the pump drive.The energy that swing load is stored can cause a shutdown that delays of pump, and therefore, pressure changes and changes in flow rate has also become slowly.This method needs high machinery cost and for operation, needs additional power.
By using frequency converter, pump motor is slowly shut down according to the rated revolution N of a revolution slope from it.This method is the comparison costliness under bigger pump power situation especially.
In order to turn-off and connect pump motor, can also use so-called level and smooth starting drive, it is according to the principle work of a three-phase current adjuster.Except can smoothly starting, said apparatus also provides the possibility of level and smooth shutdown.At this moment, this motor terminal voltage does not impact shape by phase shifts and is turned off, but is fed adjusting, and therefore, motor is slow machine halt similarly.
Exist different level and smooth shutdown quality in this case: the simplest form is, makes phase shifting angle begin to enlarge linearly from zero degree when shutting down, and stops until motor.If when the motor torque that reduces is lower than load torque herein, then cause a revolution fast to change as Fig. 3, this in most of the cases causes a water blaster again.Another method is, detects motor terminal voltage and regulates according to a slope when shutting down.But, in order to detect the essential additional firmware of motor terminal voltage.Simultaneously, difficulty is that on the one hand described voltage is by phase shift, and this voltage must be provided for control with zero potential on the other hand.Detection and " filtering " by this motor terminal voltage can produce a time-lag that regulating characteristics is had adverse effect under simple settling mode situation.
Originally be used for the operational mode of the level and smooth starting drive of level and smooth phase-shifting control method of shutting down as Fig. 4 known based on, it discloses in DE-OS 4005679.Herein, a three phase electric machine Mt is connected on three-phase electricity A, the B and C of a three phase network by a thyristor circuit, and described thyristor circuit comprises antiparallel thyristor 1A, 1B, 1C.These six thyristors can be by suitable circuits for triggering 2 conductings.If thyristor is in the state of conducting, the then current vanishes of passing through at electric current 1A, 1B, 1C zero crossing place later on a triggering.If using under the alternating current situation respectively after current vanishes, thyristor can conducting again after the time of a qualification, and people claim that this is a phase shifting control.This delay is commonly referred to as phase shifting angle.
The theory structure of this level and smooth starting drive except described alternating current adjuster circuit and circuits for triggering, also comprises testing circuit 3A, 3B, 3C.They show the state that thyristor is right.Simultaneously, only divide into two states " do not have stream " and " current-carrying ", as among Fig. 5 by illustrating as an example from the 4th the curve IOA in top, it is corresponding to the electric current I A among the phase place A.
A testing circuit 4 is used for synchronization signal (VOAB), and it can provide a signal with synchronized based on line voltage VAB.This signal is also only divided into two states " positive voltage " or " negative voltage ", and can be derived out by the voltage VAB between two phase place A and the B according to Fig. 5.
Just can try to achieve phase angle PA between current of electric and voltage by described signal.
Signal according to this for example IOA, it shows that single thyristor is to the state of 1A, 1B, 1C and can reproduce the time point of current over-zero especially, this current over-zero by for example in curved section IOA trailing edge represent, according to this signal VOAB that reproduces the line voltage zero crossing that change synchronously with line voltage VAB and special, just can predict the phase angle PA between electric moter voltage and the current of electric again.These correlations comprise according to indicate with FPA, being used for phase place A thyristor all can be as seen from Figure 5 to the control of trigger angle to the curved section of 1A.
The objective of the invention is to, a kind of level and smooth method of shutting down of pump drive that simply makes is provided, can avoid compression shock simultaneously so that pipe-line system be not damaged with certain degree avoid damage effect on the acoustics.Realize that this point is with a kind of level and smooth phase-shifting control method of shutting down of drive unit that makes, and be specially adapted to pump drive, it is controlled according to the phase angle between the voltage and current of drive motors, promptly, by enlarging phase shifting angle, the phase angle is at first born over time, and this phase angle variations changes its direction on breakover point then; Instantaneous phase angle when detecting breakover point sets out, and by an adjuster, makes phase shifting angle comply with a predetermined phase angle rated value curve and is conditioned as input parameter.In this method, do not need the hardware that adds with respect to the control of general level and smooth starting drive with phase shifting control.For this method, what only need is phase angle between electric current and the voltage, and it is in general control method or existed or can derive simply from existing data information and know.
Especially simply be that this phase shifting angle had been that straight line increases until predicting breakover point in the past.Advantageous in addition is that this has the change curve of a straight line in time for the phase angle rated value curve of positive phase angle variations.The increase of phase shifting angle is in the zone that per second is 15 to 20 degree.This phase angle rated value curve is in the scope that per second is 0.5 to 6 degree better for the increase of straight line in time in addition.One of said method particularly advantageous flexible program is, being adjusted in to pre-determine of phase shifting angle is used for carrying out as follows under the linear phase angle rated value curve prerequisite for positive phase angle variations in time:
A, in constant duration Δ t, phase angle and the phase angle rated value of measuring compared;
B, simultaneously, the instantaneous phase angle when detecting breakover point is input in the adjuster as the output valve with reference to usefulness;
If the phase angle that c records according to time interval Δ t is greater than the rated value at this time point, then this phase shifting angle reduces by one first difference with respect to its last numerical value, otherwise, increases this first difference on this last numerical value;
D, this reference value increase by one second difference when the next time interval Δ t according to rated value;
E is so long as the phase shifting angle that newly draws less than the phase shifting angle of maximum possible, then by phase angle of measuring and reference value correspondingly, repeats above-mentioned step in next time interval Δ t.
Shut down perdurabgility in order to control, advantageous manner is that the climb rate of this linear phase angle rated value curve is adjustable.
Embodiments of the invention will explain by accompanying drawing below.Show in the accompanying drawings:
Fig. 6 is an a phase shifting angle and phase angle curve over time;
Fig. 7 is a flow chart that is used for phase shifting control;
Fig. 8 is a curve chart that is used for the pump shutdown according to the inventive method.
The level and smooth phase-shifting control method of shutting down that the present invention is used for pump drive has been described in Fig. 6.In according to figure under the following curve controlled phase shifting angle D situation, with the phase angle PA that produces between the voltage and current of drive motors of di sopra curve.In order to turn-off pump motor, at first from phase shifting angle D=0 °, then it increases according to a linear ramp.So just cause the decline of an electric moter voltage and at first bear with the phase angle variations dPA/dt of time correlation.In cycle, that is to say that at each electrical network in constant duration Δ t, for example according to top method described in the prior art, this phase angle PA is tried to achieve.The just observed and analysis during the linearity of phase shifting angle D increases of the change curve of phase angle PA.In being chosen in the scopes that per second is 15 to 20 degree, the climb rate that will be used for the linear increase of phase shifting angle D accordingly under the situation, just can in the curve of phase angle PA, produce a breakover point W.If this breakover point W is detected, just indicate that motor is in such state: at this moment,, just be higher than motor torque and cause a unexpected revolution to descend as the pump running torque of load torque, and then cause the water slug effect if further reduce voltage.From this time point t
1Rise, phase shifting angle D is no longer linear to be increased, but is so controlled by an adjuster, and promptly phase angle PA that is to say that according to a linear ramp phase angle rated value curve R (t) according to Fig. 6 increases as much as possible behind breakover point W.Such result is that the motor revolution is not suddenly to change, because adjuster can not change the phase angle through phase shifting angle D control electric moter voltage fast.As can be seen from Figure 6, the phase angle PA that this is measured is subject to physical condition in the present embodiment and does not follow phase angle rated value curve R (t) variation.Herein, in the phase I behind breakover point W, this phase shifting angle D is at first almost constant, that is to say, it is stable that electric moter voltage also keeps, and on a later time point, this voltage just descends by the increase of phase shifting angle D.
The for example available PD adjuster of this adjusting realizes that its controlled quentity controlled variable (Regelgroesse) is phase angle PA.The adjusting parameter (Stellgroesse) that is used for phase shifting control is phase shifting angle D.The rated value of controlled quentity controlled variable increases according to the slope R (t) of a linearity, and it originates in phase angle PA when detecting breakover point W
wInstantaneous value, and until a maximum.The slope of this linear ramp R (t) preferably can be regulated by parameter " shutdown perdurabgility ".
Fig. 7 has shown the flow chart of phase shifting control of the present invention.According to this, phase shifting angle D begins to increase at first linearly from zero degree, therefore causes the decline of a phase angle PA, that is to say, causes a negative in time phase change dP A/dt.After each time interval Δ t, that is at each electrical network week of this situation after date, as start described detected phase angle PA.First difference that changes dD corresponding to the phase shifting angle of linear ramp is so design, and promptly this slope on the one hand can not be excessive, because otherwise, the critical point of motor just may be skipped, on the other hand, can not be too little, because if not this breakover point W just can not be detected.If phase angle variations dPA/dt in time no longer bears, then this will indicate, breakover point W reaches.The phase angle PA that this is corresponding
wBe exactly the initial rated value or the reference value R of adjuster.From this time point; this phase shifting control is just undertaken by adjuster; this linear phase angle rated value curve R (t) just is input in the above-mentioned adjuster as rated value or reference value; that is to say; in one-period; this phase angle reference value R always increases with this reference value increment dR, and this dR can calculate from the shutdown of regulation perdurabgility.Reference value increment dR can be from the coordinate PA of breakover point W
w, t
1With this condition: shutdown T perdurabgility according to the rules, at time point t
2=t
1This phase angle ,+T place is accrued to be 120 ° and to draw.Push away it according to this, the reference value increment dR in a time interval Δ t can calculate: dR=[(120 °-PA
w)/T] Δ t.Carry out an inquiry in this cycle: whether this phase angle PA that measures is greater than reference value R.For the situation greater than R, this phase shifting angle D reduces a difference dD1 with respect to its last numerical value.This increment dD1 calculates with a PID adjuster under the present embodiment situation.If this phase angle PA is less than or equal to rated value R, then make phase shifting angle D correspondingly increase difference dD1.Corresponding with it, should also increase corresponding to the rated value R at phase angle increment dR and and then be defeated by next regulating step again, until measured, as the phase shifting angle D of the pilot angle D of maximum possible
MaxBe reached.Arrive this, the level and smooth shutdown that is used for pump drive finishes.
In Fig. 8, the phase-shifting control method current of electric i that is used for the level and smooth shutdown of pump drive according to the present invention has been described, electric moter voltage u and motor revolution n be curve over time.Descend by the voltage that control is arranged, just can realize that does not have the revolution curve of decline suddenly.This revolution n begins to descend continuously at leisure, then with bigger slope excessively to the zone of a linearity.This linear slope that descends the zone depends on the slope of predetermined linear phase angle rated value curve R (t), and can regulate by " shutting down perdurabgility ".
Claims (6)
1. make a drive unit; the level and smooth phase-shifting control method of shutting down of a special pump drive; it is controlled according to the phase angle between the voltage and current of drive motors (PA); it is characterized in that; by increasing phase shifting angle (D), the phase angle is at first born over time, then in stopping process; this phase angle variations changes its direction at breakover point (W), the instantaneous phase angle (PA when detecting breakover point (W)
w) set out by an adjuster, this phase shifting angle (D) is conditioned as the input parameter according to a predetermined phase angle rated value curve (R (t)).
2. by the described phase-shifting control method of claim 1, it is characterized in that: phase shifting angle (D) all is linear increasing up to detecting breakover point (W) preceding.
3. by the described phase-shifting control method of claim 2, it is characterized in that: the linearity increase in time of this phase angle rated value curve (R (t)) is in the scope of per second 0.5 to 6 degree.
4. by claim 1 or 2 described phase-shifting control methods, it is characterized in that: (R (t) has one and is the linear change curve of positive phase angle variations in time this phase angle rated value curve.
5. by the described phase-shifting control method of claim 2, it is characterized in that: the linearity increase in time of this phase shifting angle (D) is in the scope that per second is 15 to 20 degree.
6. by the described phase-shifting control method of claim 1, it is characterized in that: the adjusting of phase shifting angle (D) will be carried out with following steps according to predetermined linear phase angle rated value curve (R (t)):
A. in constant duration Δ t, phase angle (PA) and the phase angle rated value of measuring (R (t)) compared;
B. simultaneously, the instantaneous phase angle (PA in the time of will detecting breakover point (W)
w) be input in the adjuster as the output valve of reference usefulness;
If the phase angle (PA) that c. records behind time interval Δ t is greater than the rated value (R (t)) at this time point, then phase shifting angle (D) reduces one first difference (dD1) with respect to its final value, if not, increase this first difference (dD1) with respect to its final value;
D. this reference (R) increases one second difference (d (R)) when the next time interval Δ t according to rated value (R (t));
E. if the phase shifting angle (D) of newly trying to achieve less than the phase shifting angle (D of maximum possible
Max), just be used in phase angle (PA) and the corresponding reference value (R) measured among the next time interval Δ t, repeat above-mentioned step.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN94194979A CN1042882C (en) | 1994-01-31 | 1994-01-31 | Phase-control method for stopping a drive smoothly |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN94194979A CN1042882C (en) | 1994-01-31 | 1994-01-31 | Phase-control method for stopping a drive smoothly |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1142876A CN1142876A (en) | 1997-02-12 |
| CN1042882C true CN1042882C (en) | 1999-04-07 |
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ID=5039595
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN94194979A Expired - Lifetime CN1042882C (en) | 1994-01-31 | 1994-01-31 | Phase-control method for stopping a drive smoothly |
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| Country | Link |
|---|---|
| CN (1) | CN1042882C (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3009445A1 (en) * | 1980-03-12 | 1981-09-17 | Pekazett Baumaschinen GmbH, 6660 Zweibrücken | Speed control for asynchronous motor in crane - has two of three phases each controlled by series triac. or thyristors in antiparallel |
| EP0310131A2 (en) * | 1987-10-02 | 1989-04-05 | Allen-Bradley Company, Inc. | Method and system for braking an electric motor |
| US4994951A (en) * | 1988-04-21 | 1991-02-19 | Otis Elevator Company | PWM inverter control unit |
-
1994
- 1994-01-31 CN CN94194979A patent/CN1042882C/en not_active Expired - Lifetime
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3009445A1 (en) * | 1980-03-12 | 1981-09-17 | Pekazett Baumaschinen GmbH, 6660 Zweibrücken | Speed control for asynchronous motor in crane - has two of three phases each controlled by series triac. or thyristors in antiparallel |
| EP0310131A2 (en) * | 1987-10-02 | 1989-04-05 | Allen-Bradley Company, Inc. | Method and system for braking an electric motor |
| US4994951A (en) * | 1988-04-21 | 1991-02-19 | Otis Elevator Company | PWM inverter control unit |
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| Publication number | Publication date |
|---|---|
| CN1142876A (en) | 1997-02-12 |
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Expiration termination date: 20140131 Granted publication date: 19990407 |