CN104935224A - AC synchronous motor and overload protection method therefor - Google Patents
AC synchronous motor and overload protection method therefor Download PDFInfo
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- CN104935224A CN104935224A CN201510385225.8A CN201510385225A CN104935224A CN 104935224 A CN104935224 A CN 104935224A CN 201510385225 A CN201510385225 A CN 201510385225A CN 104935224 A CN104935224 A CN 104935224A
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- current
- motor
- overload
- overload protection
- value
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Classifications
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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
- H02P29/00—Arrangements for regulating or controlling electric motors, appropriate for both AC and DC motors
- H02P29/02—Providing protection against overload without automatic interruption of supply
- H02P29/032—Preventing damage to the motor, e.g. setting individual current limits for different drive conditions
Abstract
The invention relates to an AC synchronous motor and an overload protection method therefor. The method includes the step of determining whether a motor is overloaded according to the current effective value iq of the motor, and limiting the rotating speed of the motor if the motor is overloaded. The steps of determining whether the motor is overloaded concretely include: performing zero lower limit integration on I<q><2>-I<rated><2>, and calculating a difference between an integration result and a heating action value; calculating the difference between the iq and I<most>; comparing the above two differences, and making the greater difference be an overload starting quantity; and limiting the rotating speed of the motor if the overload starting quantity is not less than zero, wherein the heating action value is k (I<most><2>-I<rated><2>), k being a set coefficient, I<rated> being the rated current of the motor, and I<most> being the highest current of the motor. A heat accumulation effect is embodied during an overload determining process (i.e., overload starting conditions), motor parameters (except the current effective value) that are difficult to obtain in a conventional method do not needed, and thus the problem that a motor thermal model is difficult to obtain is solved.
Description
Technical field
The present invention relates to a kind of ac synchronous motor and overload protection method thereof.
Background technology
Along with the development of society, motor especially autosynchronous motor is applied more and more extensive as irreplaceable power and drive unit in industrial production and people's life.Because overload causes the situation of burn-down of electric motor to happen occasionally.
Existing overload protection method, mainly comprises: first judge whether motor occurs maybe will transship, and adopts the mode of shutting down, reducing rotating speed or power output to protect motor when judging overload.
For judging that the method that maybe will occur to transship occurs motor, mainly comprise in prior art:
1. thermal relay Protection Code.Thermal relay utilizes bimetal leaf dilatancy principle to develop.But the discreteness of sheet metal is large, need often to calibrate sheet metal.
2. by burying the method for temperature sensor direct temperature measurement underground.The method needs the cooperation of electrical machinery plant, has buried temperature sensor underground at present in some high capacity motor, but does not also bury temperature sensor underground in most of middle-size and small-size motor.
3. the thermal model of motor is set up.The method is the more practicable method of one, can realize heat accumulative.The thermal model mostly being single order or second order adopted in motor thermal protector at present, model is fairly simple, but in motor thermal model, the acquisition of key parameter is relatively difficult.
4. utilize inverse-time overcurrent to realize overcurrent protection.The method carries out judgement by setting restraining line to I-t characteristic curve to realize thermal overload protection, but the method does not reflect heat accumulation effect.
5. utilize the size of current of electric to judge, and gather current of electric calculated value can be caused delayed.
In addition, after the generation of judgement overload maybe will occur, need to limit rotating speed, if arranged, rotating speed is improper still can produce the situation of burning.
Therefore, existing methodical defect is mainly three aspects: 1, and during current sample, gathering current of electric has hysteresis quality; 2, when judging overload, the motor thermal model related to obtains difficulty; 3, when motor speed is limited, arrange that rotating speed is improper still causes burn-down of electric motor.
Summary of the invention
The object of this invention is to provide a kind of synchronous machine overload protection method, obtain the problem of difficulty in order to solve motor thermal model.The present invention simultaneously also provides the synchronous machine utilizing said method.
For achieving the above object, the solution of the present invention comprises:
Ac synchronous motor overload protection method, according to the current effective value iq of motor, judges whether overload, if transship, and limiting motor rotating speed; Judge whether that the concrete steps of transshipping comprise: to i
2 q-I
2 volumecarry out subzero limit integration, and calculate the difference of integral result and heating operating value; Calculate i simultaneously
qwith I
?difference; The size of more above-mentioned two differences, makes larger one to be overload startup amount; If overload startup amount is not less than zero, then limiting motor rotating speed; Wherein, the operating value that generates heat is k (I
2 ?-I
2 volume), k is setting coefficient, I
volumefor the rated current of motor, I
?for the maximum current of motor.
Further, by current loop control limiting motor rotating speed, if overload startup amount is greater than zero, then overload protection electric current is drawn and is determined electric current; If overload startup amount is not less than zero, then overload protection speed gets the smaller value of verification electric current and given electric current; Wherein, overload protection electric current is through the given value of current value of carrying guard method and calculating; Verification electric current produces according to the verification of rated current, maximum current and current effective value.
Further, verifying electric current is that the difference of target current and current effective value regulates through PID and produces; Wherein, target current, when q shaft current is greater than maximum current and the duration is less than setting-up time, gets maximum current, under the duration is more than or equal to setting-up time situation, gets rated current.
Further, described setting-up time is 2s.
This aspect additionally provides a kind of ac synchronous motor, and ac synchronous motor comprises controller, and controller is according to overload protection method determination overload protection electric current, and described overload protection electric current is through the given value of current value of carrying guard method and calculating.
The present invention is when judging overload (transship entry condition), embody heat accumulation effect, and do not need by the parameter of electric machine (parameter except current effective value) being difficult to obtain in existing method, thus solve the problem obtaining motor thermal model suffering.
When limiting motor speed, also calculating verification speed, avoiding arranging improperly causing burn-down of electric motor.
Accompanying drawing explanation
Fig. 1 is overload protection method embodiment synchronous motor control system block diagram of the present invention;
Fig. 2 is the schematic diagram of overload protection method embodiment overload protection method of the present invention;
Fig. 3 is overload protection method embodiment overload protection building-block of logic of the present invention;
Fig. 4 is overload protection method embodiment overload protection program flow diagram of the present invention.
Embodiment
Below in conjunction with accompanying drawing, the present invention will be further described in detail.
Overload protection method embodiment
Ac synchronous motor current effective value computational methods, utilize two-phase real-time current to calculate, and in use, only need gather and appoint biphase current.Such as a, b phase, then current effective value calculating section is realized by following formula
Wherein i
a, i
bfor a, b phase current, θ is angle of rotor of motor, and iq is q shaft current, is current effective value.
Be more than a kind of account form obtaining effective current, also can adopt other account forms of the prior art.
As shown in Figure 1, gather and appoint biphase current, calculating current effective value iq (as above embodiment); According to the current effective value calculated (according to current effective value, but and not only according to current effective value, also comprising the parameter of electric machine and other detected values), judge whether overload, if transship, limiting motor rotating speed.
Just follow-up judgement and process can be carried out because first overload protection needs to detect current effective value; above-mentioned account form can detect that rapidly current effective value contributes to subsequent treatment, avoids making overload protection cause burn-down of electric motor not in time because of the hysteresis quality of current acquisition.
According to the difference of synchronous control mode, limiting motor rotating speed has different concrete manifestation forms, and such as synchronous machine adopts the control mode of outer voltage current inner loop, and limiting motor rotating speed is finally converted into the control to electric current.The such as control mode of rotating speed outer shroud current inner loop, limiting motor rotating speed is finally also converted into the control to electric current.About limiting motor rotating speed, in prior art, there is various ways.
As Fig. 2, according to overload entry condition, if meet overload entry condition, then overload protection electric current gets verification electric current, if do not meet overload entry condition, then overload protection electric current is drawn and determined electric current.Wherein, given electric current is the given electric current that outer shroud provides, and overload protection electric current is through the given value of current value that overload protection method is determined, as shown in Figure 1, the given electric current produced through rotating speed outer shroud is converted into overload protection electric current through overload protection.
As Fig. 2,3,4 gives a kind of preferred mode, in above-mentioned two---judge the mode of overload and the mode to motor speed restriction, mode that all have employed optimization, that be different from prior art: when judging overload (transship entry condition), embody heat accumulation effect, and do not need, by the parameter of electric machine (parameter except current effective value) being difficult to obtain in existing method, to embody overload entry condition in fig. 2; When limiting motor speed, calculating verification speed, avoiding arranging improperly causing burn-down of electric motor, be embodied in comparing of Fig. 2 lieutenant colonel's galvanoscope and given electric current.
Concrete, ac synchronous motor overload protection method, comprise q shaft current conversion part, target current selects part 1, PID controller 2, overload protection actuating section 3 is totally four parts.
Current effective value calculating section is realized by following formula
Wherein ia, ib are a, b phase current, and θ is angle of rotor of motor.
Target current select part 1 comprise by difference calculator 11, zero comparator 12, triggered timer 13 and 14, with logical one 5, true value selector 16.Q shaft current and maximum current input difference calculator 11.The output input zero comparator 12 of difference comparsion device 11.Zero comparator 12 exports input triggered timer 13 and 14 on the one hand, inputs and logical one 5 on the other hand with triggered timer 13 together with the output of 14.True value selector 16 is inputted as criterion, when criterion is that true time true value selector 16 exports maximum current, when exporting rated current for fictitious time with the output of logical one 5.
The function that target current selects part 1 to realize is: target current, when q shaft current is greater than maximum current and the duration is less than 2s, gets maximum current, under the duration is more than or equal to 2s situation, gets rated current.
PID controller 2 comprises subtracter 21, PID arithmetic part 22.Subtracter 21 calculates the difference of target current and q shaft current, and then PID arithmetic part 22 passing ratio, integration and differentiation calculate verification electric current.
Overload protection actuating section 3 comprises multiplier 31,32 and 33, subtracter 34,35,36 and 39, subzero limit integrator 37, gain 38, and comparator 310 and 311, on the occasion of selector 312; Rated current and maximum current are by multiplier 32,33, and subtracter 36 and gain 38 calculate heating operating value.
Q shaft current and rated current by multiplier 31,32, subtracter 35, amount that subzero limit integrator 37 calculates that the motor feels hot.Amount that the motor feels hot and heating operating value input subtracter 39 export heating bias.Q shaft current and the bias of maximum current input subtracter 34 output current.Heating bias and electric current bias are by comparator 310 output overloading startup amount.Comparator 312 determines calculating current by overload startup amount, and when overload startup amount non-negative, calculating current gets the smaller value of verification electric current and given electric current; When transshipping startup amount for time negative, calculating current is directly drawn and is determined electric current.
That is: overload protection actuating section is first to i
q 2-I
2 volumecarry out subzero limit integration, and calculate the difference of integral result and heating operating value; Calculate i simultaneously
qwith I
?difference; The size of more above-mentioned two differences, makes larger one to be overload startup amount; If overload startup amount is not less than zero, then limiting motor rotating speed.Wherein, the operating value that generates heat is k (I
2 ?-I
2 volume), k is setting coefficient (in the present embodiment, k gets 2, as other execution modes, also can use other values), I
volumefor the rated current of motor, I
?for the maximum current of motor.
Adopt above-mentioned to i
2-I
2 volumecarry out subzero limit integration, only carry out integration when current effective value is greater than rated value, the not integration when being less than rated value, can be sensitive reflect heat accumulation effect.And with k (I
2 ?-I
2 volume) compare, by k (I
2 ?-I
2 volume) as heating operating value, that can embody heating can tolerance degree.Owing to also considering I and I simultaneously
?difference, the startup amount of therefore transshipping has taken into account heating and electric current overrun condition.
By current loop control limiting motor rotating speed, if overload startup amount is greater than zero, then overload protection electric current is drawn and is determined electric current; If overload startup amount is not less than zero, then overload protection speed gets the smaller value of verification electric current and given electric current.
Be illustrated in figure 4 and specifically protect flow process.
Step 1 makes " current effective value=[sin (θ-4 π/3)-sin θ] * ia+ [sin (θ-4 π/3)-sin (θ-2 π/3)] * ib " performs step 2 afterwards.
Step 2 makes " difference=q shaft current square-rated current square " afterwards perform step 3.
Step 3 makes " the motor feels hot amount=the motor feels hot amount+difference " performs step 4 afterwards.
Step 4 judges, and whether " the motor feels hot measures " is less than or equal to zero.If be less than or equal to zero, then perform step 5; Otherwise, perform step 6.
Step 5 makes " the motor feels hot amount=0, overload identifier=0 " afterwards perform step 8.
Step 6 judges, and whether " the motor feels hot measures " is more than or equal to " stagnant circular rector ".If be more than or equal to, then perform step 7; Otherwise, perform step 8.
Step 7 makes " the motor feels hot amount=stagnant circular rector " performs step 8 afterwards.
Step 8 judges, and whether " overload identifier " equals zero.If equal, then perform step 9; Otherwise, perform step 13.
Whether whether step 13 judges " overload starts symbol " equals 2 is less than " setting-up time " with " counter ".When " overload start symbol " equals 2 and " counter " is less than " setting-up time ", perform step 14; Otherwise, perform step 15;
Step 14 makes " counter " adds 1 rear execution step 16;
Step 15 makes " target current=rated current " performs step 16 afterwards;
Step 16 makes " difference between current=target current-rated current " performs step 17 afterwards;
Step 17 calculates " electric current 1 " by PID and performs step 18 afterwards;
Step 18 judges, and whether " electric current 1 " is more than or equal to given electric current.If be more than or equal to, then perform step 19; Otherwise perform step 20;
Return after step 19 makes " calculating current=electric current 1 ";
Return after step 20 makes " calculating current=given electric current ";
Step 9 judges, and whether " actual current " is greater than " maximum current ".If be greater than, then perform step 10; Otherwise, perform step 11.
Return after step 10 makes " the motor feels hot measures=generate heat operating value, overload identifier=2, target current=maximum current, counter=0 ".
Step 11 judges, and whether " the motor feels hot measures " is more than or equal to " heating operating value ".If be more than or equal to, then perform step 12; Otherwise, return.
Return after step 14 makes " overload identifier=1 ".
Synchronous machine embodiment
Synchronous motor structure in the present embodiment is identical with synchronous machine of the prior art, and difference is that overload protection method applies the method in above embodiment.
Claims (5)
1. ac synchronous motor overload protection method, is characterized in that, according to the current effective value iq of motor, judges whether overload, if transship, and limiting motor rotating speed; Judge whether that the concrete steps of transshipping comprise:
To i
2 q-I
2 volumecarry out subzero limit integration, and calculate the difference of integral result and heating operating value; Calculate i simultaneously
qwith I
?difference;
The size of more above-mentioned two differences, makes larger one to be overload startup amount; If overload startup amount is not less than zero, then limiting motor rotating speed; Wherein, the operating value that generates heat is k (I
2 ?-I
2 volume), k is setting coefficient, I
volumefor the rated current of motor, I
?for the maximum current of motor.
2. ac synchronous motor overload protection method according to claim 1, is characterized in that, by current loop control limiting motor rotating speed,
If overload startup amount is greater than zero, then overload protection electric current is drawn and is determined electric current;
If overload startup amount is not less than zero, then overload protection speed gets the smaller value of verification electric current and given electric current;
Wherein, overload protection electric current is through the given value of current value of carrying guard method and calculating; Verification electric current produces according to the verification of rated current, maximum current and current effective value.
3. ac synchronous motor overload protection method according to claim 2, is characterized in that, verification electric current is that the difference of target current and current effective value regulates through PID and produces; Wherein, target current, when q shaft current is greater than maximum current and the duration is less than setting-up time, gets maximum current, under the duration is more than or equal to setting-up time situation, gets rated current.
4. ac synchronous motor overload protection method according to claim 3, is characterized in that, described setting-up time is 2s.
5. application rights requires the ac synchronous motor of overload protection method according to any one of 1-4; it is characterized in that; ac synchronous motor comprises controller; controller is according to overload protection method determination overload protection electric current, and described overload protection electric current is through the given value of current value of carrying guard method and calculating.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510385225.8A CN104935224B (en) | 2015-06-30 | 2015-06-30 | Ac synchronous motor and its overload protection method |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510385225.8A CN104935224B (en) | 2015-06-30 | 2015-06-30 | Ac synchronous motor and its overload protection method |
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| Publication Number | Publication Date |
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| CN104935224A true CN104935224A (en) | 2015-09-23 |
| CN104935224B CN104935224B (en) | 2017-06-16 |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105356419A (en) * | 2015-10-30 | 2016-02-24 | 中国兵器工业集团第二O二研究所 | Improved artillery alternating-current servo system motor current overload protection method |
| CN105375440A (en) * | 2015-10-30 | 2016-03-02 | 中国兵器工业集团第二O二研究所 | Motor power overloading protection method for gun AC servo system |
| CN105449640A (en) * | 2016-01-04 | 2016-03-30 | 许继集团有限公司 | AC asynchronous motor as well as effective current value calculation method and overload protection method thereof |
| CN116526425A (en) * | 2023-04-11 | 2023-08-01 | 上海华建电力设备股份有限公司 | Digital implementation method for thermal overload protection of alternating current motor |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105356419A (en) * | 2015-10-30 | 2016-02-24 | 中国兵器工业集团第二O二研究所 | Improved artillery alternating-current servo system motor current overload protection method |
| CN105375440A (en) * | 2015-10-30 | 2016-03-02 | 中国兵器工业集团第二O二研究所 | Motor power overloading protection method for gun AC servo system |
| CN105449640A (en) * | 2016-01-04 | 2016-03-30 | 许继集团有限公司 | AC asynchronous motor as well as effective current value calculation method and overload protection method thereof |
| CN105449640B (en) * | 2016-01-04 | 2018-03-16 | 许继集团有限公司 | AC induction motor and its current effective value computational methods and overload protection method |
| CN116526425A (en) * | 2023-04-11 | 2023-08-01 | 上海华建电力设备股份有限公司 | Digital implementation method for thermal overload protection of alternating current motor |
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| CN104935224B (en) | 2017-06-16 |
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