Description of drawings
Fig. 1 is the MT rotating coordinate system of stator magnetic linkage oriented vector control;
Fig. 2 is an asynchronous machine M axle T type equivalent electric circuit;
Fig. 3 is an asynchronous machine T axle T type equivalent electric circuit;
Fig. 4 is the vector control flow chart of the no velocity location transducer of asynchronous machine;
Fig. 5 is that the rotary speed in the stator magnetic linkage oriented vector control system of asynchronous machine is inferred control flow chart;
Fig. 6 is the MT space-time polar plot of the stator magnetic linkage oriented vector control system of asynchronous machine when operate as normal;
Fig. 7 is the space-time polar plot of the stator magnetic linkage oriented vector control system of asynchronous machine when stator voltage is leading;
Fig. 8 is the space-time polar plot of the stator magnetic linkage oriented vector control system of asynchronous machine when stator voltage lags behind.
Fig. 9 is that the simple and easy rotary speed in the Vector Control System for Asynchronous Machine is inferred control flow chart.
Symbol description:
E
1: the stator-induced electromagnetic gesture.
E
2': convert rotor induction gesture to stator side.
E
2-ideal': convert to the ideal value of the rotor induction gesture of stator side.
E
2-real': convert to the actual value of the rotor induction gesture of stator side.
E '
δ: convert air gap inductive electromotive force to stator side.
E '
δ-ideal: convert to the ideal value of the air gap inductive electromotive force of stator side.
E '
δ-real: convert to the actual value of the air gap inductive electromotive force of stator side.
E
1-ideal: the ideal value of stator-induced electromagnetic gesture.
E
1-real: the actual value of stator-induced electromagnetic gesture.
f
n: the rated frequency of motor.
k
P-ω: the speed adjustment is with the proportional gain of proportional plus integral control ring.
k
I-ω: the speed adjustment is with the storage gain of proportional plus integral control ring.
k
P-iTs: the proportional gain of speed control ring.
k
I-iTs: the storage gain of speed control ring.
k
P-iTp: the proportional gain of Position Control ring.
k
T-iTp: the storage gain of Position Control ring.
K: subscript, represent this sampled data or calculated data.
i
f: the external exciting current of synchronous separately excited machine excitation winding.
i
Hys: the dead-time compensation current threshold.
i
1M: the stator excitation electric current.
i
1T: the stator torque current.
i
2M': convert rotor excitation current to stator side.
i
2T': convert rotor torque electric current to stator side.
I
1n: the specified phase current of motor.
l
E σ: synchronous machinery excitation winding leakage inductance.
L
e: the synchronous machinery excitation winding inductance.
l
1: the rotary electric machine leakage inductance.
l
2': convert rotor leakage inductance to stator side.
L
1: the excitation axle inductance of stator magnetic linkage oriented synchronous machine.
L
2: the torque axis inductance of stator magnetic linkage oriented synchronous machine.
L
1 δ: the excitation axle inductance of the synchronous machine of air gap flux linkage orientation.
L
2 δ: the torque axis inductance of the synchronous machine of air gap flux linkage orientation.
L
d: the d-axis inductance of stator winding.
L
q: the transverse axis inductance of stator winding.
L
Md: the d-axis mutual inductance between the synchronous machine rotor winding.
L
Mq: the transverse axis mutual inductance between the synchronous machine rotor winding.
LPF: low pass filter.
M ': convert motor mutual inductance to stator side.
P: differential operator.
p
p: the motor number of pole-pairs.
r
1: rotary electric machine resistance.
Sigma: the integral that integral and calculating is used.
T
e: the electromagnetic torque of motor.
T
e *: the output torque instruction value.
T
c: the carrier cycle of AC/DC power-converting device.
t
d: the Dead Time that the AC/DC power-converting device sets in advance.
T
r: the rotor circuit transition time constant.
T
S-ω: the control cycle of proportional plus integral control ring.
V
DC: DC bus-bar voltage.
The mean value of DC bus-bar voltage instantaneous value.
V
1M: stator excitation voltage.
V
1M *: the stator excitation voltage reference value.
V
1T: stator torque voltage.
V
1n: the specified voltage between phases of motor.
V
1-real: the voltage vector of AC/DC power-converting device output.
V
1-ideal: the desirable output voltage vector of AC/DC power-converting device when the control system operate as normal.
v
Out: the AC/DC power-converting device output voltage behind the dead-time compensation.
α
u: the duty ratio that U exports mutually.
ψ
1d: motor d-axis armature reaction magnetic linkage.
ψ
1q: motor cross-magnetizing armature reaction magnetic linkage.
ψ
f: the magnetic linkage that the permanent magnet of magneto produces.
ψ
δ d: motor d-axis air gap magnetic linkage.
ψ
δ q: motor transverse axis air gap magnetic linkage.
ψ
1M: the stator excitation magnetic linkage.
ψ
1T: stator torque magnetic linkage.
ψ
2M': convert rotor-exciting magnetic linkage to stator side.
ψ
2T': convert rotor torque magnetic linkage to stator side.
ψ
δ M': convert air gap excitation magnetic linkage to stator side.
ψ
δ T': convert air gap torque magnetic linkage to stator side.
φ
s: the stator magnetic linkage oriented MT rotating coordinate system of synchronous machine and the phase difference of dq rotating coordinate system.
φ
δ: the air gap flux linkage orientation MT rotating coordinate system of synchronous machine and the phase difference of dq rotating coordinate system.
θ: the phase angle of MT rotary coordinate system.
The guess value at the phase angle of MT rotary coordinate system.
The guess value at rotor mechanical phase angle.
ω
1: the stator magnetic linkage angular velocity of rotation.
The guess value of stator magnetic linkage angular velocity of rotation.
ω
1e: the basic estimated value of stator magnetic linkage angular velocity of rotation.
ω
r: the rotor mechanical angular velocity of rotation.
The guess value of rotor mechanical angular velocity of rotation.
ω
SL: the slippage angular speed of asynchronous machine.
The guess value of the slippage angular speed of asynchronous machine.
Δ ω: the regulating the speed of the phase angle error of MT rotating coordinate system.
ε
VM: the error between M axle stator excitation voltage reference value and the actual M axle stator excitation voltage.
σ: the magnetic leakage factor of asynchronous machine.
Embodiment
According to Figure of description technical scheme of the present invention is further elaborated below.Figure 1 shows that the MT rotating coordinate system based on the stator magnetic linkage oriented vector control of stator magnetic linkage, this coordinate system is positioned at excitation axle M axle on the stator magnetic linkage vector, and is synchronous with its maintenance; The leading M axle 90 of torque axis T axle is spent simultaneously.The present invention selects stator magnetic linkage oriented vector control system, and like this, stator magnetic linkage just becomes Be Controlled target magnetic linkage.
All parameters of electric machine rotor can be decomposed into M axle component and T axle component at the MT rotating coordinate system as stator voltage, stator current.Wherein, the M axle is because consistent with Be Controlled target flux linkage vector, and M axle component is all relevant with the motor magnetic linkage; T axle component is then relevant with motor torque; M axle component and T axle component are separate.Like this, the vector control system of motor just can be controlled the excitation current component of M axle independently, makes motor action on the working point of specified in advance magnetic flux density; Simultaneously, the motor vector control system also can be adjusted T shaft torque current component separately, obtains the electromagnetic torque of needs, thereby accurately controls the speed or the position of motor.
For asynchronous machine, based on the definition of MT reconnaissance rotating coordinate system, the T type equivalent electric circuit of asynchronous machine can be broken down into T axle T type equivalent electric circuit and M axle T type equivalent electric circuit, as Fig. 2, shown in Figure 3.Here, follow common asynchronous machine theory, the parameter of asynchronous machine rotor side need be converted to stator side, and the numerical value after the conversion is with subscript ' represented.
In rotating coordinate system, each vector all becomes the actionless vector of relative rotating coordinate system, so magnetic linkage also produces revolving electro-motive force except producing transformer electromotive force.By the stator terminal of AC/DC power-converting device output voltages such as frequency converter to asynchronous machine, the stator voltage equation that can be obtained asynchronous machine by equivalent circuit diagram is:
Numerical expression 1
Here, p is a differential operator.
Owing to contain the stator magnetic linkage component in the following formula, and the relation between stator magnetic linkage, air gap magnetic linkage and rotor flux is as follows:
ψ
δM′=M′(i
1M+i
2M′)=ψ
1M-l
1i
1M=ψ
2M′-l
2′i
2M′
ψ
δ T'=M ' (i
1T+ i
2T')=ψ
1T-l
1i
1T=ψ
2T'-l
2' i
2T' numerical expression 2
The control of simple relatively stator magnetic linkage oriented vector control MT rotating coordinate system occasion at first is discussed below:
In general, AC/DC power-converting devices such as frequency converter can be by adjusting output voltage apace, thereby reach the purpose of the stator current of accurately controlling asynchronous machine.And because the resistance of the resistance of output circuit and asynchronous machine itself is very little, the time constant of transient process is very little, and we can suppose that the stator current command value of asynchronous machine can be regarded as almost consistent with its actual value.And when real electrical machinery is controlled, for the magnetic flux density that makes asynchronous machine remains on the rated operation point of design, exciting current i
1MWill be controlled consciously and be become a steady state value.Simultaneously, according to the load size of motor and the instruction rotating speed of motor, calculate the size of adjusting the torque current command value automatically by the upper level speed control.
That is to say, the present invention at first needs to determine the stator current command value of motor, and the lowermost layer of whole vector control system is based upon on the basis of high speed Current Control, current regulator ACRM shown in control flow Fig. 4 (AutoCurrent Regulator for Magnetization) and ACRT (Auto Current Regulator for Torque).According to the current instruction value of this moment, the three-phase resultant vector of stator current will be controlled on the specified amplitude and phase place by AC/DC power-converting devices such as frequency converters.And the AC/DC power-converting device will automatically be exported a suitable voltage by the ACR control ring when realizing Current Control, and obviously, stator input voltage at this time should satisfy stator voltage equation numerical expression 1.
By based on stator magnetic linkage ψ
1The basic definition of MT rotating coordinate system of stator magnetic linkage oriented vector control, if MT rotating coordinate system accurate positioning as can be known, T axle magnetic linkage is zero.So by the definition of numerical expression 2, the stator voltage equation of the asynchronous machine of formula 1 can be simplified and is rewritten as:
Numerical expression 3
Numerical expression above investigating, we can notice, in the output voltage based on the AC/DC power-converting device of Current Control, T shaft voltage V
1TIn comprising very important rotor flux angular velocity of rotation ω
1Information.Meanwhile, M shaft voltage V when motor normally moves
1MThe locating information that has comprised the MT rotating coordinate system.The present invention is exactly the design of not having the vector control system of velocity location transducer at this point.
On the other hand, usually current instruction value is in that the AC/DC power-converting device is inner when generating, by one once or the secondary low pass filter in addition export next link to after the smoothing processing and handle.If so when current instruction value did not have very violent change, stator voltage did not have bigger change yet.If it is constant that vector control can be controlled exciting current, then can ignore the differential term of stator magnetic linkage, simplify stator voltage equation 3.T shaft voltage by the output of AC/DC power-converting device calculates the basic estimated value ω of the stator magnetic linkage angular velocity of rotation of motor at this moment
1e:
Numerical expression 4
Obviously, the result of calculation of following formula precision when high speed driving and motor steady operation still can; But when low speed even zero-speed, perhaps in the control of dynamic transition process, because T shaft voltage V
1TIt is very little to become, and at this time factor such as the position error of the change of the error of the test error of electric current and voltage and the parameter of electric machine, stator magnetic linkage, rotating coordinate system, the equational simplification of stator voltage all will be brought bigger error to the estimation of stator magnetic linkage angular velocity of rotation.Because the phase place of MT rotating coordinate system need be by the integration gained of stator magnetic linkage angular velocity of rotation, so the accumulation of the slight error of the angular velocity of rotation of magnetic linkage can cause the great error at phase angle, cause the location of MT rotating coordinate system inaccurate, further cause the estimation error of stator magnetic linkage angular velocity of rotation conversely again.Such vicious circle causes the accumulation of error, even causes that The whole control system becomes unstable, causes the motor rotary speed to send out and shakes or the uncontrollable phenomenon of whole system.
In order to address this problem, the present invention will utilize M shaft voltage V in the stator voltage equation
1M, adopt the following M shaft voltage V that passes through
1MCalculate the error amount of the angular velocity of rotation of MT rotating coordinate system and real electrical machinery stator magnetic linkage, finally obtain the angular velocity of rotation and the phase place of stator magnetic linkage accurately, and the actual rotary speed of MT rotary coordinate system and rotor magnetic linkage is kept synchronously, and its phase place is consistent.
The careful stator voltage equation 3 of investigating, we are defined as stator-induced electromagnetic gesture E with the product of the angular velocity of rotation of stator magnetic linkage and stator magnetic linkage
1, and stator-induced electromagnetic gesture E
1Be consistent with the T axle always.Simultaneously, stator voltage vector V
1Under the state of the normal operation of the system that is projected on the M axle should be numerical expression 3 resulting M shaft voltages, and we are referred to as fiducial value V
1M *This pattern 3 can be re-expressed as:
Numerical expression 5
By following formula, the space-time polar plot of the stator magnetic linkage oriented vector control system when we can be with the normal rotating operation of asynchronous machine is expressed as Fig. 6.But, when the AC/DC power-converting device carries out Current Control, only according to formula 4 controls, then along with M shaft voltage actual value V often takes place load change
1MWith fiducial value V
1M *Inconsistent phenomenon.If the M shaft voltage actual value V of current AC/DC power-converting device output
1MWith fiducial value V
1M *At this time defined MT rotary coordinate system of control system self and actual stator induced potential E are not described not simultaneously,
1Produced phase error physically.
In other words, this error is actually because stator-induced electromagnetic gesture E
1Different the causing of the phase place of actual phase and the control system imagination.Simultaneously, because stator voltage can be by stator-induced electromagnetic gesture E on circuit theory
1The stator pressure drop that is produced with stator current is synthetic to be obtained, so stator-induced electromagnetic gesture E
1Deviation must cause the deviation of stator voltage.When motor normally moved, as shown in Figure 3, stator voltage was almost vertical with the M axle, thus the phase place of stator voltage as deviation is arranged slightly, the projection on the M axle just has bigger change.And this change by the present invention as the position error signal utilization, constantly adjust the rotary speed of MT rotating coordinate system according to the change conditions of M shaft voltage.
Fig. 7 has shown actual stator induced potential E
1-realSpace-time polar plot when leading, the voltage vector V of AC/DC power-converting device output
1-realAlso be ahead of the voltage vector V that control system is scheduled to
1-ideal, the result causes the M shaft voltage V of AC/DC power-converting device output
1MLess than fiducial value V
1M *At this time control system should strengthen the rotary speed of MT coordinate system, to catch up with stator-induced electromagnetic gesture E
1-realPhysical location.And in order to set up the Tracing Control system of an agility, this rotary acceleration should be relevant with the deviate size.
On the contrary, Fig. 8 has shown actual stator induced voltage E
1-realDuring hysteresis, the voltage vector V of AC/DC power-converting device output
1Also lag behind the voltage vector that control system is scheduled to, the result causes the M shaft voltage V of AC/DC power-converting device output
1MGreater than fiducial value V
1M *At this time control system should reduce the rotary speed of MT coordinate system, waits for that induced voltage catch up with.Equally, the rotary speed that reduces should be relevant with the deviate size.When low speed rotation, this speed adjustment sometimes even can make the reverse rotation of MT coordinate system makes The whole control system have the relatively large degree of freedom, to adapt to dynamic changes such as load torque.
In sum, the M shaft voltage V that exports by more current AC/DC power-converting device
1MWith fiducial value V
1M *Size, as shown in Figure 7 and Figure 8, the present invention imports the Δ ω that regulates the speed, this Δ ω that regulates the speed produces by following proportional plus integral control ring.The size of the control system passing ratio integral control ring high speed and the Δ ω that dynamically regulates the speed reaches MT rotary coordinate system and rotor induction gesture rotary speed and keeps synchronous purpose.
Δ ω=k
P-ωε
VM+ k
I-ω∫ ε
VMDt numerical expression 6
Here, M shaft voltage error
Coefficient k
P-ωAnd k
I-ωBe respectively proportional gain and the storage gain of speed adjustment with the proportional plus integral control ring.In order to limit the numerical value of the Δ ω that regulates the speed, the final calculation result of integral and proportional plus integral control ring is the restriction of upper and lower bound in addition, and when the processing of limits value, it is unified that the limits value of the final calculation result of the limits value of integral and proportional plus integral control ring should keep, the malfunctioning phenomenon of control system that is produced when avoiding integrated value considerably beyond final limits value.
In addition, when this proportional plus integral control ring is realized by the CPU programming, need handle the following formula discretization.The digital integration formula of discretization can merely be used Euler's integral:
Δ ω=k
P-ωε
VM|
k+ k
I-ωε
VM|
kT
S-ω+ Sigma|
K-1 Numerical expression 7
Here, T
S-ωBe the control cycle of proportional plus integral control ring, subscript k represents this sampled data, and subscript k-1 represents sampled data last time.In order to guarantee control performance, generate the difference of the working mechanism of PWM waveform, control cycle T according to use CPU
S-ωNeed be set to be certain relation with the carrier cycle of AC/DC power-converting device.For example, the carrier frequency of large-sized DC/AC power converting apparatus is lower usually, has only thousands of Hz, can be with control cycle T under this occasion
S-ωBe set to the AC/DC power-converting device carrier cycle 1/2nd, both calculated at twice in that the preceding half-sum of carrier wave is later half; Under common carrier frequency, for example under the carrier frequency of 8kHz~15kHz, can be with control cycle T
S-ωBe set to identical with the carrier cycle of frequency converter; When very high carrier frequency, then can suitably relax, doubly move by the plural number of carrier cycle.Certainly, control cycle T
S-ωAlso can be set to have nothing to do, by the cycle self contained function that sets in advance with the carrier cycle of AC/DC power-converting device.
In addition, the computational methods of the digital integration of discretization can also adopt other numerical integratings such as Simpson's integration, but do not have basic difference on the The whole control principle, no longer discuss here.
Meanwhile, integral needs to upgrade by following formula after following formula has calculated:
Sigma|
k=k
I-ωε
VM|
kT
S-ω+ Sigma|
K-1 Numerical expression 8
Control system is after Δ ω is regulated the speed in importing, and convolution 4 calculates the angular velocity of rotation basic value ω of resulting stator magnetic linkage
1e, can obtain stator magnetic linkage angular velocity of rotation guess value and be:
Numerical expression 9
Behind stator magnetic linkage angular velocity of rotation guess value integration, just can obtain the phase angle of MT rotary coordinate system:
Numerical expression 10
The following formula discretization is handled and to be handled equally by the front principle, and later similar problem is repeated description no longer also.If control system makes above-mentioned controlling unit high speed motion in design, for example press two/one-period action of carrier cycle, perhaps press the carrier cycle action, when perhaps doubly moving by the plural number of carrier cycle, control system can be adjusted the angular velocity of rotation guess value of stator magnetic linkage at a high speed, the actual rotary speed of MT rotary coordinate system and motor stator magnetic linkage is remained synchronously, and make both phase places dynamically keep unanimity, thereby the vector control of no velocity location transducer is achieved.
In addition, import the Δ ω that regulates the speed after, the calculating of magnetic linkage angular velocity of rotation guess value is to the parameter of electric machine no longer sensitivity that becomes, because the angular velocity of rotation basic value ω of stator magnetic linkage
1eThe error of calculation can in Δ ω item, be offset.This is a subsidiary effect of the present invention, and its result makes the vector control system of whole no velocity location transducer have suitable robustness (robustness), and change has automatic compensating effect to the parameter of electric machine.
Control flow Fig. 5 has shown above-mentioned stator magnetic linkage angular velocity of rotation guess value
Phase angle with the MT rotary coordinate system
Computational process.Because in working control, high speed current regulator ACRM and ACRT will inevitably bring the variance components of sizable output voltage, cause the angular velocity of rotation guess value
Change, cause the performance of whole Electric Machine Control.So as shown in FIG., the present invention has adopted one or more low pass filters to suppress the variance components of output voltage, makes the angular velocity of rotation guess value
Become level and smooth.
Calculate after the guess value of magnetic linkage angular velocity of rotation, whole vector control flow process has just obtained the phase information of vital rotating coordinate system, three-phase alternating current can be converted into MT two-phase direct current thus, speed or positioning control link by motor produces the torque current command value then, produce the excitation current instruction value by the magnetic linkage control device, control ring by exciting current and torque current produces excitation output voltage and torque output voltage again, again with the two-phase dc voltage conversion of excitation output voltage and torque output voltage to three-phase alternating voltage, converse the three-phase duty ratio by three-phase alternating voltage, obtain the three-phase PWM switch command by the three-phase duty ratio at last.In addition, owing to exist slippage between the rotary speed of the rotary speed of rotator of asynchronous machine and stator magnetic linkage, so, also need to calculate the slip of motor in order to control the rotary speed of rotor.
M axis voltage references value V by careful investigation coordinate system
1M *Computational methods, can learn the M axis voltage references value V of stator magnetic linkage oriented vector control system
1M *It is a small positive voltage; To the less demanding occasion of system's control precision, M axis voltage references value V can be set simply
1M *Be zero, simultaneously, suppose that also the magnetic linkage of being controlled is identical with the rotor flux size.Because the basic estimated value ω of magnetic linkage angular velocity of rotation
1eCan obtain the regulating the speed correction of Δ ω, also can simplify and calculate by following formula:
Numerical expression 11
By the setting of following formula, the calculating of the Δ ω that regulates the speed can use numerical expression 6 to calculate, and the computational methods at the computational methods of the guess value of the rotary speed of magnetic linkage and phase angle are also aforementioned identical simultaneously.Control flow Fig. 9 has shown above-mentioned magnetic linkage angular velocity of rotation guess value
Phase angle with the MT rotary coordinate system
Computational process.
Though the M axis voltage references value V of following formula
1M *Very simple, need the parameter of motor hardly, but M axis voltage references value V clearly
1M *Simplification follow the trail of for the speed of system to bring error.Because numerical expression 6 has used proportional integral calculating, thus the out of control of system finally caused for the continuous accumulation that prevents error, necessary here restriction proportion integral and calculating bound, even can be calculated by a usage ratio control ring.Calculating as for exciting current and excitation magnetic linkage then can be adopted the design of electrical motor value.In addition, the error for the motor electromagnetic torque that error caused of exciting current then needs to be proofreaied and correct with other method.For example in deciding rotating speed control, can adjust the electromagnetic torque of motor by the size of adjusting torque current, perhaps be proofreaied and correct by surveying back importing correction coefficient.
The rotation electrical angle speed of the stator magnetic linkage angular velocity of rotation of asynchronous machine and rotor differs a slippage angular velocity omega
SL, usually the rated slip rate of asynchronous machine is designed in about 0.02~0.05, and slip is also bigger when being in transient process such as starting when asynchronous machine, so the speed control ring of vector control system must be considered the slippage angular velocity omega
SLInfluence.
In stator magnetic linkage oriented vector control system, can obtain the approximate calculation formula:
Numerical expression 12
The arrangement The above results, the guess value of the rotation electrical angle speed of rotor is:
Numerical expression 13
After rotor rotated electrical angle speed guess value integration, just can obtain the guess value of the position angle of rotor:
Numerical expression 14
Here, p
pBe the motor number of pole-pairs.
Because the present invention is based upon on the basis of superfast Current Control, so need the command value of clear torque current and the command value of exciting current.Hereinafter with the computational methods of the command value of at first clear and definite electric current.
The computational methods of the command value of stator torque current become along with control purpose difference.That is to say that the multi-mode controller in the vector control flow chart 4 (Multi Mode Controller) is along with control purpose difference can be selected control model flexibly.For example, the control purpose can obtain the command value of torque current with following ASR (AutoSpeed Regulator) control ring for accurately to control under the occasion of motor rotary speed; And work as the control purpose is under the pinpoint occasion, can obtain the command value of torque current with APR (Auto Position Regulator) control ring; More complicated application scenario needs the composite application of these two kinds of controls, perhaps obtains the command value of torque current with other method.And on the other hand, in papermaking, printing and dyeing, steel rolling etc. are used, also need to use the control purpose for accurately controlling the torque control model of motor output electromagnetic torque.Below, will be illustrated above-mentioned control model respectively.
In stator magnetic linkage oriented vector control system, the expression formula of the electromagnetic torque of motor and magnetic linkage and electric current can be expressed as:
Numerical expression 15
In the formula, subscript-this variable of item expression is a vector, upper right mark~item expression common mode symmetry vector.
Because the basic thought of vector control is exactly with magnetic linkage and torque current decoupling zero respectively, so in the said stator flux linkage orientation vector system, when stator torque axis magnetic linkage is controlled as zero, and when the stator excitation magnetic linkage was controlled as constant, clearly the electromagnetic torque of motor and stator torque current were proportionate relationship.Therefore, if the output torque instruction value is designated, just it is as follows to utilize the above-mentioned relation formula to calculate the command value of stator torque current:
Numerical expression 16
In the formula, T
e *Be the output torque instruction value.Stator magnetic linkage ψ
1MNumerical value then can singly find by design of electrical motor.
Simultaneously, can in above-mentioned each calculating formula, add correction coefficient in actual applications, carry out correction calculation, to obtain bigger precision by the means such as correction or experiment of dispatching from the factory.
Motor speed control ring ASR can design by following proportional plus integral control mode, is obtained the command value of stator torque current by the error of motor rotary speed:
Numerical expression 17
Here, coefficient k
P-iTsAnd k
I-iTsBe respectively proportional gain and the storage gain of speed control ring ASR, ω
*Rotation electrical angle speed value for motor.In addition, in order to limit electric current, the integral of following formula and final calculation result be the restriction of upper and lower bound in addition.When the processing of limits value, the limits value of integral and the limits value of current instruction value should keep unified, the malfunctioning phenomenon of control system that is produced when avoiding integrated value considerably beyond the limits value of current instruction value.
In addition, asynchronous machine is owing to the existence of slip, and rotary speed of rotator need be considered slippage angular speed, and slippage angular speed can calculate by numerical expression 12.And synchronous machine is exactly the magnetic linkage rotary speed because rotor and magnetic linkage keep synchronously at any time so rotor rotates electrical angle speed.
In addition, asynchronous machine Position Control ring APR can calculate by following proportional plus integral control mode, is obtained the command value of stator torque current by the angular error of rotor:
Numerical expression 18
Here, coefficient k
P-iTpAnd k
I-iTpBe respectively proportional gain and the storage gain of Position Control ring APR.The integral here and the treatment principle of command value are same as above.
In more complicated application, can outside speed control ring ASR, add one deck Position Control ring APR again, equally also can obtain the effect of positioning control, Position Control ring APR at this time is designed to be obtained by the angular error of rotor the command value of motor rotary speed, is finally obtained the command value of stator torque current again from the error of motor rotary speed by speed control ring ASR:
Numerical expression 19
The integral here and the treatment principle of command value are same as above.
What deserves to be mentioned is that in the design of the foregoing description, the storage gain of the proportional plus integral control ring of position angle often is set to zero.The elastic system of the response class springy that positioning control at this moment shows, and as one of positioning control system important performance parameter, the elasticity of whole system is called as the stiffness coefficient of positioning control.
In the vector control system,,, alternating current component is transformed into DC component, so that control and computing so must carry out 3/2 ac/dc coordinate transform to it because interchange instantaneous values such as stator and rotor current voltage are in variable condition always; Simultaneously, because the operation result of control system is a flip-flop, also must carry out one time 2/3 AC/DC coordinate transform to it, thus obtain can control of conversion the needed three-phase alternating voltage of AC/DC power-converting device such as device, thereby calculate the three-phase PWM waveform.Here, owing to relate to the size of each component after the coordinate transform, the present invention uses following coordinate transform formula.
Become the conversion that 2 phase right angle rest frames exchange instantaneous value by the three-phase alternating current instantaneous value:
Numerical expression 20
Wherein, if use the mode of two phase samplers, the numerical value of a phase of sampling can not calculated by other two-phase.For example V does not have the occasion of sampling mutually, can be calculated by following formula:
V=-U-W numerical expression 21
Become the conversion of MT DC component by the interchange instantaneous value of 2 phase right angle rest frames:
Numerical expression 22
Here, θ is the phase angle of MT rotating coordinate system.
Become the conversion of the interchange instantaneous value of 2 phase right angle rest frames by the MT DC component:
Numerical expression 23
Exchange the conversion that instantaneous value becomes the three-phase alternating current instantaneous value by 2 phase right angle rest frames:
Numerical expression 24
In the vector control flow chart of the various embodiments described above, control system is utilized the resulting T shaft voltage of above-mentioned current regulator computing V
1TWith M shaft voltage V
1MCarry out 2/3 AC/DC coordinate transform, calculate the instantaneous value of three-phase output voltage.Then, according to the instantaneous value of above-mentioned three-phase output voltage, be calculated as follows out the duty ratio of three-phase output:
Numerical expression 25
In the formula, V
DC0Be desirable d-c bus voltage value.
The last three-phase that is calculated AC/DC power-converting device such as frequency converter by the three-phase output duty cycle is 6 groups of required PWM drive waveforms of bridge up and down, thereby drive the three-phase switch of bridge up and down.
In addition, although the explanation of each embodiment of the present invention is description and the calculation of each physical quantity of motor being carried out space vector with rectangular coordinate system, but the mathematical description of polar coordinate system equally also can be realized basic controlling thought of the present invention, and both do not have difference fundamentally.
Although example of the present invention hereto has been described, the present invention is not subjected to the restriction of above-mentioned example, in the scope of the technological thought of Miao Shuing, can certainly implement the present invention with other various dissimilar forms in this article.