CN103684169A - Dead-beat based direct torque control method for permanent magnet synchronous motor - Google Patents

Abstract

The invention discloses a dead-beat based direct torque control method for a permanent magnet synchronous motor. Errors between given magnetic linkage amplitude and actual magnetic linkage amplitude as well as between given torque amplitude and actual torque amplitude are compensated accurately and simultaneously within a control cycle, and dead-beat control of magnetic linkage and torque is realized. Meanwhile, a space voltage vector modulation method is introduced into a control system to enable switching frequency to be constant. By the control method, system performance can be well improved, magnetic linkage and torque pulsation can be lowered obviously, dynamic response speed of the torque is equivalent to that of a conventional direct torque control scheme, and the direct torque control method basically keeps the advantages of simple structure and fast dynamic torque response.

Description

A kind of based on dead-beat direct torque control method for permanent magnetic synchronous electric machine

[technical field]

The present invention relates to electric machines control technology field, particularly a kind of control method of permagnetic synchronous motor.

[background technology]

In tradition Direct Torque Control System for Permanent Magnet Synchronous Motor, according to the region, position of torque, two stagnant ring controller outputs of magnetic linkage and stator magnetic linkage, from switch list, select suitable space vector of voltage to control motor torque, magnetic linkage.But the space vector of voltage that can select is limited, and to the selection of space vector of voltage, be also more rough in switch list, therefore can bring the large problem of pulsation of torque and magnetic linkage.And owing to just space vector of voltage being selected, and the mode of not utilizing space voltage to modulate can cause the non-constant of switching frequency, is unfavorable for the hardware designs of inverter in system.

At present, for the existing multiple modified model direct torque control scheme of large problem of pulsing of torque and magnetic linkage in traditional Direct Torque Control System for Permanent Magnet Synchronous Motor, be summed up and can be divided into four class schemes:

1) adopt improved switch list

Refer to shown in Fig. 1, document [1-5] is by being subdivided into vector plane 12 sectors and adopting the method for improved space voltage vector switch list to select most suitable voltage vector and then obtain torque more accurately, magnetic linkage control.

Refer to shown in Fig. 2, document [6-10] has been introduced fuzzy logic controller the alternative condition of space voltage vector has been done to refinement.Utilize fuzzy reasoning that stator magnetic linkage error, torque error and magnetic linkage angle have been carried out to rational fuzzy classification, thereby make the selection of space vector of voltage more accurate.But the amount of calculation of On-line Fuzzy reasoning is large, be difficult to real-time control.

Refer to shown in Fig. 3, document [11-13] has proposed the permagnetic synchronous motor Direct Torque PREDICTIVE CONTROL based on area voltage vector table, according to motor model, derive the PREDICTIVE CONTROL angle of voltage vector in each region, in each control cycle, insert the PREDICTIVE CONTROL that zero vector is realized torque and magnetic linkage.

These methods have reduced the pulsation of torque and magnetic linkage, but because control algolithm is still based upon on the basis that 8 limited space vector of voltage are selected, can not guarantee the constant of switching frequency.

2) introduced multi-electrical level inverter

Refer to shown in Fig. 4 (a)-Fig. 4 (c), document [14-18] has been introduced multi-electrical level inverter to increase the quantity of selectable voltage space vector, has reduced the pulsation of torque and magnetic linkage, but has needed more switching devices, and the complexity of system hardware structure is increased.

3) direct torque control of space voltage vector modulation (SVM)

Refer to shown in Fig. 5, utilize the modulation technique of space voltage vector can obtain more, continually varying space vector of voltage, and then realize motor magnetic linkage, torque are controlled more accurately.According to this modulation control thought, document [19-23] has proposed the method Direct Torque scheme based on space vector modulation, and these schemes have reduced torque pulsation effectively, and make switching frequency constant.But because proportional integral (PI) controller is applied in torque control loop, PI controller parameter is responsive to motor speed and load variations, and PI controller itself has phase place hysteresis effect makes the dynamic response of torque slack-off.

4) direct torque control of sliding moding structure

Refer to shown in Fig. 6, document [24-28] is introduced Sliding mode variable structure control strategy in permagnetic synchronous motor direct torque control and is substituted two hysteresis regulators in traditional direct torque control with torque and two sliding mode controllers of magnetic linkage, and its output is modulated and guaranteed that inverter switching frequency is constant by space voltage vector.But when sliding formwork switches, there is dither problem, system is played pendulum.

In tradition Direct Torque Control System for Permanent Magnet Synchronous Motor, according to the region, position of torque, two stagnant ring controller outputs of magnetic linkage and stator magnetic linkage, from switch list, select suitable space vector of voltage to control motor torque, magnetic linkage.But the space vector of voltage that can select is limited, and to the selection of space vector of voltage, be also more rough in switch list, therefore can bring the large problem of pulsation of torque and magnetic linkage.And owing to just space vector of voltage being selected, and the mode of not utilizing space voltage to modulate can cause the non-constant of switching frequency, is unfavorable for the hardware designs of inverter in system.

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[summary of the invention]

The object of the present invention is to provide a kind ofly based on dead-beat direct torque control method for permanent magnetic synchronous electric machine, to solve existing control method, bring the pulsation of torque and magnetic linkage large, the inconstant problem of switching frequency.

To achieve these goals, the present invention adopts following technical scheme:

Based on a dead-beat direct torque control method for permanent magnetic synchronous electric machine, comprise the following steps:

1), k-1 constantly, the biphase current i of three-phase current detection unit inspection _a, i _binput three phase static, to two-phase static coordinate converter unit, obtains the i under static two phase coordinate systems through 3/2 coordinate transform _α, i _βelectric current; The busbar voltage U being detected by DC bus-bar voltage detecting unit _dcwith inverter switching states S _a, S _b, S _cinput stator voltage computing module forms three-phase voltage u _a, u _b, u _c, and carry out 3/2 coordinate transform and obtain the voltage u under static two phase coordinate systems _α, u _β;

2), magnetic linkage and torque estimating device are according to the current i of input _α, i _β, voltage u _α, u _β, and the initial position θ of PMSM rotor _r0the stator magnetic linkage calculation of initial value determining obtains actual torque amplitude T _e, the actual magnetic linkage amplitude of stator | ψ _s|, the actual magnetic linkage of stator position θ _s, actual stator flux linkage vector ψ _s;

3), reference stator flux linkage vector calculator is according to the actual magnetic linkage amplitude of stator | ψ _s|, actual torque amplitude T _eapplication of formula (7) calculates k-1 actual torque angle δ (k-1) constantly; According to reference stator magnetic linkage amplitude | ψ _s| ^*, torque reference amplitude application of formula (7) calculates k torque reference angle δ constantly ^*(k); Torque reference angle δ ^*and ω (k) _r(k-1) T _safter addition, deduct actual torque angle δ (k-1), obtain k reference stator flux linkage vector constantly

with the actual flux linkage vector ψ of k-1 moment stator _s(k-1) the angle difference Δ δ between ^*(k); Angle difference Δ δ ^*(k) with the k-1 angular position theta of stator magnetic linkage vector reality constantly _s(k-1) be added, obtain the k position angle of reference stator flux linkage vector constantly

; K is the position angle of reference stator flux linkage vector constantly

with with reference to stator magnetic linkage amplitude | ψ _s| ^*by formula (3), calculate, obtain k constantly with reference to stator magnetic linkage vector

${\mathrm{\ψ}}_s^{*}\left(k\right)={\left|{\mathrm{\ψ}}_s\right|}^{*}\∠{\mathrm{\θ}}_s^{*}\left(k\right)---\left(3\right)$

$\left\{\begin{array}{c}{\mathrm{\δ}}^{*}\left(k\right)=\arcsin \left(\frac{2T_e^{*}{L}_s}{3n_p\left|{\mathrm{\ψ}}_f\right|{\left|{\mathrm{\ψ}}_s\right|}^{*}}\right)\\ \mathrm{\δ}(k-1)=\arcsin \left(\frac{2T_e(k-1)L_s}{3n_p\left|{\mathrm{\ψ}}_f\right|\left|{\mathrm{\ψ}}_s(k-1)\right|}\right)\end{array}\right.---\left(7\right)$

Wherein, ω _r(k-1) represent the k-1 rotating speed of permagnetic synchronous motor constantly; T _srepresent the employing cycle; L _srepresent stator inductance, n _prepresent motor number of pole-pairs, | ψ _s| ^*represent reference stator magnetic linkage amplitude; | ψ _f| represent rotor flux amplitude; | ψ _s(k-1) | represent the k-1 actual magnetic linkage amplitude of stator constantly;

4), reference stator flux linkage vector

be admitted to reference stator voltage vector calculator, utilize formula (5) to obtain reference stator voltage vector u (k) and send into the on off state sequence that space voltage vector modulation module obtains next switch periods, control permagnetic synchronous motor and be rotated;

$u\left(k\right)=\frac{{\mathrm{\ψ}}_s^{*}\left(k\right)-{\mathrm{\ψ}}_s(k-1)}{T_s}+R_s{i}_s(k-1)---\left(5\right)$

In formula: i _s(k-1) represent k-1 stator current vector constantly, R _srepresent stator resistance.

With respect to prior art, the present invention has following beneficial effect:

The present invention is a kind of based on dead-beat direct torque control method for permanent magnetic synchronous electric machine, in a control cycle simultaneously fine compensation the error of given magnetic linkage amplitude and actual magnetic linkage amplitude, given torque amplitude and actual torque amplitude, having realized the dead beat of magnetic linkage and torque controls, space voltage vector modulator approach is introduced to control system simultaneously, make switching frequency constant.Control method of the present invention is elevator system performance preferably, the method can obviously reduce magnetic linkage and torque pulsation, and the dynamic responding speed of torque is suitable with traditional direct torque control scheme, substantially kept Direct Torque method have advantages of simple in structure, torque dynamic response is fast.

[accompanying drawing explanation]

Fig. 1 is twelve-section direct torque control interval division schematic diagram;

Fig. 2 is the Direct Torque Control System for Permanent Magnet Synchronous Motor block diagram of fuzzy logic;

Fig. 3 is the Direct Torque PREDICTIVE CONTROL block diagram based on area voltage vector table;

Fig. 4 is multi-electrical level inverter one phase bridge arm topological figure; Wherein, Fig. 4 (a) is diode clamp construction unit, and Fig. 4 (b) flies across electric merge structure unit, and Fig. 4 (c) is H bridge cascade structure;

Fig. 5 is the Direct Torque Control System for Permanent Magnet Synchronous Motor block diagram of space voltage vector modulation;

Fig. 6 is the Direct Torque Control System for Permanent Magnet Synchronous Motor structure chart of sliding moding structure;

Fig. 7 is traditional direct torque control torque and A phase current stable state waveform;

Fig. 8 is traditional direct torque control magnetic linkage amplitude stable state waveform;

Fig. 9 is traditional direct torque control stator magnetic linkage vector stable state waveform;

Figure 10 is traditional direct torque control stator magnetic linkage track stable state waveform;

Figure 11 is traditional direct torque control torque dynamic waveform;

Figure 12 is traditional direct torque control torque dynamic waveform partial enlarged drawing;

Figure 13 is the torque of dead beat direct torque control and A phase current stable state waveform;

Figure 14 is dead beat direct torque control magnetic linkage amplitude stable state waveform;

Figure 15 is dead beat direct torque control stator magnetic linkage vector stable state waveform;

Figure 16 is dead beat direct torque control stator magnetic linkage track stable state waveform;

Figure 17 is dead beat direct torque control ginseng torque dynamic waveform;

Figure 18 is dead beat direct torque control torque dynamic waveform partial enlarged drawing;

Figure 19 is the location diagram between each flux linkage vector in a switch periods;

Figure 20 is permagnetic synchronous motor dead beat direct Torque Control block diagram;

Figure 21 is reference stator flux linkage vector computing block diagram;

Figure 22 is reference stator voltage vector computing block diagram;

Figure 23 is reference stator voltage vector computing block diagram;

Figure 24 is the output timing diagram of space voltage vector.

[embodiment]

Below in conjunction with accompanying drawing, the present invention is described in further detail.

In order to realize the dead beat of torque and magnetic linkage, control, need to analyze the position relationship between each flux linkage vector in a switch periods, by analysis and prediction position relationship between each flux linkage vector in a switch periods, find and should be applied to space voltage vector on motor, and this space voltage vector can accurately compensate difference between magnetic linkage reference value and actual value and the difference between torque reference value and actual value simultaneously.Shown in Figure 19, be k-1 constantly to the k position relationship between each flux linkage vector in this switch periods constantly.

Suppose that current time is the k-1 moment, the position relationship between each flux linkage vector as shown in Figure 19, known reference stator flux linkage vector with the actual flux linkage vector ψ of stator _s(k-1) the angle difference Δ δ between ^*(k) can be calculated by formula (1):

Δδ ^*(k)=δ ^*(k)-δ(k-1)+ω _r(k-1)T _s （1）

In formula:

Δ δ ^*(k)---the angle difference between the actual flux linkage vector of reference stator flux linkage vector and stator;

δ ^*(k)---the angle of torsion that k expects constantly;

δ (k-1)---k-1 is the angle of torsion of reality constantly;

ω _r(k-1)---k-1 is the rotating speed (electric angle speed) of reality constantly;

T _s---the systematic sampling cycle (being the k moment and the interval of k-1 between the moment).

Because sampling period of system will be much smaller than the mechanical time constant of motor, so think rotational speed omega in formula (1) _rconstant within the sampling period, perseverance is ω _r(k-1).

Reference stator flux linkage vector position angle

can obtain by through type (2):

${\mathrm{\θ}}_s^{*}\left(k\right)=\mathrm{\Δ}{\mathrm{\δ}}^{*}\left(k\right)+{\mathrm{\θ}}_s(k-1)---\left(2\right)$

In formula:

the position angle of moment reference stator flux linkage vector;

θ _s(k-1)---k-1 is the position angle of stator magnetic linkage vector reality constantly;

Owing to being that system is given with reference to stator magnetic linkage amplitude, so just can be obtained by formula (3) with reference to stator magnetic linkage vector:

${\mathrm{\ψ}}_s^{*}\left(k\right)={\left|{\mathrm{\ψ}}_s\right|}^{*}\∠{\mathrm{\θ}}_s^{*}\left(k\right)---\left(3\right)$

In formula:

constantly with reference to stator magnetic linkage vector;

| ψ _s| ^*---with reference to stator magnetic linkage amplitude.

After voltage equation discretization in permagnetic synchronous motor Mathematical Modeling, and adopt the expression way of vector can obtain formula (4).

$u\left(k\right)=\frac{{\mathrm{\ψ}}_s^{*}\left(k\right)-{\mathrm{\ψ}}_s(k-1)}{T_s}+R_s{i}_s\left(k\right)---\left(4\right)$

In formula:

U (k)---k should be applied to the voltage vector of motor constantly;

ψ _s(k-1)---k-1 is actual stator flux linkage vector constantly;

I _s(k)---k is stator current vector constantly;

R _s---stator resistance.

Due to the pressure drop R on the stator resistance of normally working in up-to-date style (4) at motor _si _s(k) will be much smaller than stator terminal voltage, and consider i _sand i (k) _s(k-1) difference is less, and the voltage vector that therefore should be applied on motor can use formula (5) to represent.

$u\left(k\right)=\frac{{\mathrm{\ψ}}_s^{*}\left(k\right)-{\mathrm{\ψ}}_s(k-1)}{T_s}+R_s{i}_s(k-1)---\left(5\right)$

In formula:

I _s(k-1)---k-1 is stator current vector constantly.

By the space voltage vector obtaining with upper type just can be simultaneously accurately compensating torque and magnetic linkage error, realized the dead beat control of torque and magnetic linkage.

According to the basic principle of aforementioned permagnetic synchronous motor dead beat direct torque control, can obtain the structured flowchart of its control system as shown in figure 20, as shown in Figure 20, permagnetic synchronous motor dead beat direct torque control is still a kind of direct control to stator flux of motor and electromagnetic torque, there is no current controlled circuit, also do not utilize complicated rotating coordinate transformation, control algolithm is all to complete under rest frame, so its control method still belongs to the category of Direct Torque Control.

The present invention is a kind of based on dead-beat Direct Torque Control System for Permanent Magnet Synchronous Motor, itself and traditional direct Torque Control difference are magnetic linkage control loop and torque control loop to unite two into one, and its control loop comprises that DC bus-bar voltage detecting unit, three-phase current detection unit, three phase static modulate (SVM) module to two-phase static coordinate converter unit (clark converter unit), magnetic linkage with torque estimating device, reference stator flux linkage vector calculator, reference stator voltage vector calculator and space voltage vector.

The present invention is a kind of based on dead-beat direct torque control method for permanent magnetic synchronous electric machine, specifically comprises the following steps: the biphase current i of three-phase current detection unit inspection first _a, i _binput three phase static is to two-phase static coordinate converter unit, through three phase static, to 3/2 coordinate transform of two-phase static coordinate converter unit, obtains the i under static two phase coordinate systems _α, i _βelectric current, the busbar voltage U being detected by DC bus-bar voltage _dcwith inverter switching states S _a, S _b, S _cinput stator voltage computing module forms three-phase voltage u _a, u _b, u _c, and carry out 3/2 coordinate transform and obtain the voltage u under static two phase coordinate systems _s(u _α, u _β).

Magnetic linkage and torque estimating device are according to the current i of input _α, i _β, voltage u _α, u _β, and the initial position θ of PMSM rotor _r0the stator magnetic linkage initial value determining; Calculate actual torque amplitude T _e, the actual magnetic linkage amplitude of stator | ψ _s|, the actual magnetic linkage of stator position θ _s, actual stator flux linkage vector ψ _s.

In the present invention, reference stator flux linkage vector calculator has substituted torque hysteresis comparator and the flux linkage hysteresis comparator device in traditional direct Torque Control.Reference stator flux linkage vector computing block diagram as shown in figure 21.

As shown in figure 21, reference stator flux linkage vector

by reference stator magnetic linkage amplitude | ψ _s| ^*, the actual magnetic linkage amplitude of stator | ψ _s|, the actual magnetic linkage of stator position θ _s, torque reference amplitude

actual torque amplitude T _ewith motor speed ω _rcalculate.Torque equation formula in motor model can be derived the calculating formula (6) of angle of torsion.

$\mathrm{\δ}=\arcsin \left(\frac{{2T}_e{L}_s}{{3n}_p\left|{\mathrm{\ψ}}_f\right|\left|{\mathrm{\ψ}}_s\right|}\right)---\left(6\right)$

In formula:

| ψ _s|, | ψ _f|---stator magnetic linkage amplitude and rotor flux amplitude;

L _srepresent stator inductance, n _prepresent motor number of pole-pairs;

δ---angle of torsion (angle of stator magnetic linkage vector and rotor flux vector).

By calculating formula (6) discretization, torque reference angle δ ^*(k) can obtain by through type (7) with actual torque angle δ (k-1).

$\left\{\begin{array}{c}{\mathrm{\δ}}^{*}\left(k\right)=\arcsin \left(\frac{2T_e^{*}{L}_s}{3n_p\left|{\mathrm{\ψ}}_f\right|{\left|{\mathrm{\ψ}}_s\right|}^{*}}\right)\\ \mathrm{\δ}(k-1)=\arcsin \left(\frac{2T_e(k-1)L_s}{3n_p\left|{\mathrm{\ψ}}_f\right|\left|{\mathrm{\ψ}}_s(k-1)\right|}\right)\end{array}\right.---\left(7\right)$

In formula:

δ ^*(k)---torque reference angle;

| ψ _s| ^*,

---reference stator magnetic linkage amplitude and torque reference amplitude;

δ (k-1)---k-1 is the angle of torsion of reality constantly;

| ψ _s(k-1) |, T _e(k-1)---k-1 is the actual magnetic linkage amplitude of stator and actual torque amplitude constantly.

Then by formula (1), obtain reference stator flux linkage vector with the actual flux linkage vector ψ of stator _s(k-1) the angle difference Δ δ between ^*(k); By formula (2), obtain reference stator flux linkage vector

position angle

finally by formula (3), obtain reference stator flux linkage vector

This reference stator flux linkage vector

be admitted to reference stator voltage vector calculator, utilize formula (5) to obtain reference stator voltage vector u (k).Reference stator voltage vector calculator has substituted the switch list in traditional direct Torque Control.Reference stator voltage vector computing block diagram as shown in figure 22.

Then space voltage vector modulation (SVM) module of voltage vector u (k) being sent in control loop obtains the on off state sequence that next switch periods needs.

In control loop, the target of space voltage vector modulation is the needed reference voltage vector u of fundamental space voltage vector synthesis system (k) that utilizes inverter to produce.The theoretical foundation of space voltage vector modulation is the mean value principle of equal effects, in a switch periods by basic voltage vectors is combined, its mean value is equated with reference voltage vector.8 fundamental voltage space vectors that produced by voltage source inverter as shown in figure 23.

Six nonzero voltage space vectors are divided into vector plane the sector of six 60 degree.Figure 23 has also represented the specific implementation of the reference voltage vector in the first sector.Vector correlation based on shown in Figure 23, the realization that space voltage vector is modulated at the first sector can be obtained by formula (8).

In formula:

U _s---reference voltage vector;

T _s---the switch periods of system;

T ₀, T ₁, T ₂---basic voltage vectors u ₀, u ₁and u ₂the time acting on respectively;

The angle of θ---reference voltage vector.

When reference voltage vector is arranged in other Wu Ge district, can by corresponding basic voltage vectors and Zero voltage vector, synthesize after the same method.Like this, just can pass through space voltage vector modulation technique, the synthetic space voltage vector that obtains needs.Because the different switching sequence of inverter can produce obstructed output voltage wave result, can produce different space voltage vector modulator approaches.

Consider and adopt TI company's T MS320F2812DSP as the realization basis of systematic control algorithm herein, therefore modal seven segmentation space voltage vector modulator approaches have been adopted herein, be divided into two the action time of each voltage vector, simultaneously giving action time of Zero voltage vector etc. u ₀with u ₇, and to guarantee to only have an on off state to change at every turn, the on off sequence producing is like this u ₀→ u ₁→ u ₂→ u ₇→ u ₂→ u ₁→ u ₀.Its on off state output as shown in figure 24.

Finally, the on off sequence of space voltage vector modulation module output acts on inverter, and the dead beat that has so just completed magnetic linkage and torque is controlled.

Experiment condition: during Steady Experimental, torque reference is given as 40Nm, Reference Stator Flux Linkage amplitude is given as 0.95Wb, by regulating excitation of direct current generator to make motor speed be defined in about 100rpm; During dynamic experiment torque reference given by 40Nm bust, be 10Nm, then by 10Nm, risen to as 40Nm.It should be noted that, the experimental result of two kinds of control strategies all obtains when inverter switching frequency is 5k.

Adopt traditional Direct Torque Control.Figure 7 shows that the stable state waveform of torque reference and actual torque; Figure 8 shows that the stable state waveform of Reference Stator Flux Linkage amplitude and actual magnetic linkage amplitude; Figure 9 shows that stator magnetic linkage vector stable state waveform; Figure 10 shows that stator magnetic linkage track stable state waveform.Experimental result is known, and under traditional Strategy of Direct Torque Control, torque pulsation is larger, and its torque pulsation amplitude is approximately 20Nm, contains a large amount of harmonic componentss in current waveform, has indirectly confirmed torque pulsation larger; Magnetic linkage pulsation amplitude is about 0.02Wb; Stator magnetic linkage vector locus is circular, and the pulsation of confirmation magnetic linkage is larger indirectly simultaneously.

The dynamic waveform of torque reference and actual torque is known as shown in Figure 11, and under traditional Strategy of Direct Torque Control, actual torque can be followed the variation of torque reference fast.The local amplification of torque reference and actual torque dynamic waveform is known as shown in Figure 12, and its response time that torque step is changed is about 1ms.

The present invention is a kind of based on dead-beat direct torque control method for permanent magnetic synchronous electric machine.Figure 13 shows that the stable state waveform of torque reference and actual torque; Figure 14 shows that the stable state waveform of Reference Stator Flux Linkage amplitude and actual magnetic linkage amplitude.From the steady result of Figure 13 institute's torque reference and actual torque, under dead beat Strategy of Direct Torque Control, torque pulsation is less, and its torque pulsation amplitude is approximately 5Nm, and current waveform is more smooth, has indirectly confirmed torque pulsation less.The known actual magnetic linkage amplitude of the stable state waveform of Reference Stator Flux Linkage amplitude and actual magnetic linkage amplitude is pulsed substantially near Reference Stator Flux Linkage amplitude as shown in Figure 14, and its magnetic linkage pulsation amplitude is about 0.005Wb.By the stable state waveform of stator magnetic linkage vector shown in Figure 15 and Figure 16 and the known stator magnetic linkage vector locus of stator magnetic linkage track stable state waveform, be circular, the pulsation of confirmation magnetic linkage is less indirectly simultaneously.

Figure 17 shows that the dynamic waveform of torque reference and actual torque; Figure 18 shows that the local amplification of torque reference and actual torque dynamic waveform.The dynamic waveform of torque reference and actual torque is known as shown in Figure 17, and under dead beat Strategy of Direct Torque Control, actual torque can be followed the variation of torque reference fast.The local amplification of torque reference and actual torque dynamic waveform is known as shown in Figure 18, and its response time that torque step is changed is about 1ms.

Steady Experimental result from permagnetic synchronous motor tradition direct torque control and dead beat Direct Torque Control, adopts traditional Direct Torque Control, and torque pulsation is about 20Nm; And adopting dead beat Direct Torque Control of the present invention, torque pulsation is about 5Nm; Adopt traditional Direct Torque Control, the contained harmonic components of electric current is larger; And adopting dead beat Direct Torque Control, the contained harmonic components of electric current is less.Adopt traditional Direct Torque Control, magnetic linkage pulsation is about 0.02Wb; And adopting dead beat Direct Torque Control, magnetic linkage pulsation is about 0.005Wb.Hence one can see that, adopts dead beat Direct Torque Control can improve preferably the control performance of torque and magnetic linkage during stable state, can suppress preferably torque and magnetic linkage pulsation.Dynamic experiment result from permagnetic synchronous motor tradition direct torque control and dead beat Direct Torque Control, adopts traditional Direct Torque Control, and torque step response time is about 1ms; Adopt dead beat Direct Torque Control, torque step response time is also about 1ms.Hence one can see that, and in the time of dynamically, tradition direct torque control and dead beat Direct Torque Control can be followed torque reference instruction variation fast, and the dynamic property of two kinds of control strategies is substantially suitable.By the present invention, the experiment of two kinds of control strategies is contrasted, known traditional Direct Torque method has the advantages such as simple in structure, torque dynamic response is fast, but also has the problems such as magnetic linkage and torque pulsation are large, inverter switching frequency is non-constant.The dead beat Direct Torque Control that the present invention proposes is elevator system performance preferably, the method can obviously reduce magnetic linkage and torque pulsation, and the dynamic responding speed of torque is suitable with traditional direct torque control scheme, substantially kept Direct Torque method have advantages of simple in structure, torque dynamic response is fast.

Claims (1)

1. based on a dead-beat direct torque control method for permanent magnetic synchronous electric machine, it is characterized in that, comprise the following steps:

1), k-1 constantly, the biphase current i of three-phase current detection unit inspection _a, i _binput three phase static, to two-phase static coordinate converter unit, obtains the i under static two phase coordinate systems through 3/2 coordinate transform _α, i _βelectric current; The busbar voltage U being detected by DC bus-bar voltage detecting unit _dcwith inverter switching states S _a, S _b, S _cinput stator voltage computing module forms three-phase voltage u _a, u _b, u _c, and carry out 3/2 coordinate transform and obtain the voltage u under static two phase coordinate systems _α, u _β;

2), magnetic linkage and torque estimating device are according to the current i of input _α, i _β, voltage u _α, u _β, and the initial position θ of PMSM rotor _r0the stator magnetic linkage calculation of initial value determining obtains actual torque amplitude T _e, the actual magnetic linkage amplitude of stator | ψ _s|, the actual magnetic linkage of stator position θ _s, actual stator flux linkage vector ψ _s;

3), reference stator flux linkage vector calculator is according to the actual magnetic linkage amplitude of stator | ψ _s|, actual torque amplitude T _eapplication of formula (7) calculates k-1 actual torque angle δ (k-1) constantly; According to reference stator magnetic linkage amplitude | ψ _s| ^*, torque reference amplitude

application of formula (7) calculates k torque reference angle δ constantly ^*(k); Torque reference angle δ ^*and ω (k) _r(k-1) T _safter addition, deduct actual torque angle δ (k-1), obtain k reference stator flux linkage vector constantly (k) with the actual flux linkage vector ψ of k-1 moment stator _s(k-1) the angle difference Δ δ between ^*(k); Angle difference Δ δ ^*(k) with the k-1 angular position theta of stator magnetic linkage vector reality constantly _s(k-1) be added, obtain the k position angle of reference stator flux linkage vector constantly

(k); K is the position angle of reference stator flux linkage vector constantly

(k) with reference to stator magnetic linkage amplitude | ψ _s| ^*by formula (3), calculate, obtain k constantly with reference to stator magnetic linkage vector

(k);

${\mathrm{\ψ}}_s^{*}\left(k\right)={\left|{\mathrm{\ψ}}_s\right|}^{*}\∠{\mathrm{\θ}}_s^{*}\left(k\right)---\left(3\right)$

$\left\{\begin{array}{c}{\mathrm{\δ}}^{*}\left(k\right)=\arcsin \left(\frac{2T_e^{*}{L}_s}{3n_p\left|{\mathrm{\ψ}}_f\right|{\left|{\mathrm{\ψ}}_s\right|}^{*}}\right)\\ \mathrm{\δ}(k-1)=\arcsin \left(\frac{2T_e(k-1)L_s}{3n_p\left|{\mathrm{\ψ}}_f\right|\left|{\mathrm{\ψ}}_s(k-1)\right|}\right)\end{array}\right.---\left(7\right)$

Wherein, ω _r(k-1) represent the k-1 rotating speed of permagnetic synchronous motor constantly; T _srepresent the employing cycle; L _srepresent stator inductance, n _prepresent motor number of pole-pairs, | ψ _s| ^*represent reference stator magnetic linkage amplitude; | ψ _f| represent rotor flux amplitude; | ψ _s(k-1) | represent the k-1 actual magnetic linkage amplitude of stator constantly;

4), reference stator flux linkage vector

be admitted to reference stator voltage vector calculator, utilize formula (5) to obtain reference stator voltage vector u (k) and send into the on off state sequence that space voltage vector modulation module obtains next switch periods, control permagnetic synchronous motor and be rotated;

$u\left(k\right)=\frac{{\mathrm{\ψ}}_s^{*}\left(k\right)-{\mathrm{\ψ}}_s(k-1)}{T_s}+R_s{i}_s(k-1)---\left(5\right)$

In formula: i _s(k-1) represent k-1 stator current vector constantly, R _srepresent stator resistance.

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