CN106803731A - A kind of five-phase PMSM model prediction method for controlling torque - Google Patents

Abstract

The invention discloses a kind of five-phase PMSM model prediction method for controlling torque, belong to the design of polyphase machine ac control system and manufacture in power electronics and power drives field, it is mainly comprised the following steps：Sector where calculating dead beat voltage vector first, 4 voltage vectors (2 big vectors of middle vector+2) only chosen in the sector, as the input set of model prediction direct torque, accomplish real-time update；Then using forecast model to input set in 4 voltage vectors be predicted calculating, combined objective function choose optimal voltage vector as system subsequent time input.The inventive method uses model prediction direct torque, and with excellent dynamic response performance, and amount of calculation is smaller, and Digital Implementation is more easy, alleviates the pressure of digit chip.

Description

A kind of five-phase PMSM model prediction method for controlling torque

Technical field

(five phase inversions are included the present invention relates to polyphase machine ac control system in power electronics and power drives field Device, five-phase PMSM) design and manufacture, more particularly to a kind of five-phase PMSM model prediction direct torque side Method.

Background technology

The progress of microelectric technique and Power Electronic Technique, is that the development of polyphase ac governing system is laid a good foundation.It is many The advantage of phase system is essentially consisted in：The vibration of motor and noise are smaller, and inverter capacity is big, good output, and reliability By force, power density is high.

Finite aggregate model prediction direct torque (Finite-Control-Set Model Predictive Torque Control, FCS-MPTC) it is a kind of vehicle air-conditioning algorithm.In five phase current transformers-motor driven systems, generally only select Take 11 vectors (big vector+zero vector, MPTC-11) or 21 vectors (big vector+middle vector+zero vector, MPTC-21) are made For input is gathered.In FCS-MPTC algorithms, the voltage vector in input set will be carried out time in each controlling cycle Go through calculating.Choose 11 vectors to gather as input, although reduce meeting in amount of calculation, but motor stator electric current to a certain extent There is larger harmonic wave, torque pulsation is larger and control effect is not good when causing motor stable state；And 21 vectors are chosen as defeated Although entering set enriches the quantity of domination set, and improves the control performance of system, to numerical control system bring compared with Big computation burden, can produce the other problemses such as digital delay.

The content of the invention

The technical problems to be solved by the invention are to provide a kind of five-phase PMSM model prediction direct torque side Method, mitigates the computation burden of numerical control system, it is ensured that the excellent control performance of system.

In order to solve the above technical problems, the technical solution adopted by the present invention is：

A kind of five-phase PMSM model prediction method for controlling torque, comprises the following steps：

Step 1：Voltage of the Parker rotation transformation by five-phase PMSM under natural system of coordinates according to extension, The physical quantitys such as electric current, magnetic linkage, torque are respectively mapped under two orthogonal coordinate systems of d1-q1 and d3-q3；

Step 2：Fundamental space voltage vector to the phase voltage source inventer of two level five is classified, and calculate it is big or middle, The amplitude of small voltage vector is respectively：

In formula, U_L, U_M, U_SThe amplitude of large, medium and small voltage vector is represented respectively；U_dcRepresent the bus electricity of inverter direct-flow side Pressure size；

Step 3：Torque and magnetic linkage error calculation according to five-phase induction motor go out dead beat voltage vector predicted value, then extract Go out the amplitude and positional information of dead beat predicted voltage vector；

Step 4：Voltage vector positional information according to being calculated determines the place sector of dead beat voltage vector；

Step 5：Choose input set of 4 vectors in sector where dead beat voltage vector as PREDICTIVE CONTROL；

Step 6：It is predicted evaluation to the voltage vector in domination set to calculate, the minimum value for choosing object function is corresponding Voltage vector is applied to inverter.

Further, the step 3 is specially：

The variable quantity △ δ that torque error according to the k moment calculates required power angle δ are：

T_e ^refRepresent the set-point of motor speed outer shroud torque；δ represents the power angle between electric machine rotor magnetic linkage, N_pTable Show motor number of pole-pairs, L_dRepresent d-axis inductance, ψ_fRepresent the magnetic linkage of permanent magnet, ψ_sRepresent stator magnetic linkage vector；

According to formulaCalculate the stator magnetic linkage error under α β coordinate systems：

ψ_s ^refRepresent the set-point of fundamental wave magnetic linkage；

Component U of the dead beat voltage vector predicted value under two-phase α β rest frames_αAnd U_βFor：

Finally according to formulaTry to achieve the amplitude and positional information of voltage vector in dead-beat control method：

Further, the object function is：

Wherein, i=m, m+1, m+2, m+3；M represents the sector number where dead beat voltage vector in each sampling period； ψ_sd1-q1 ^refRepresent the set-point of first harmonic spatial stator magnetic linkage；T_e(k+1)、ψ_sd1-q1(k+1) torque of k+1 moment is represented respectively and is determined The predicted value of sub- magnetic linkage；ψ_sd3-q3(k+1) the harmonic prediction value of k+1 moment stator magnetic linkages is represented；ψ_sd3-q3 ^refFor harmonic wave space is fixed The set-point of sub- magnetic linkage；λ₁、λ₂Respectively in the weight coefficient of first harmonic spatial harmonic space stator magnetic linkage component.

Further, I in object function_maxFor：

|I_lim| the current limit value for setting is represented, current amplitude after detecting that a certain voltage vector is acted on exceedes maximum The limitation of value, then do not choose the voltage vector.

Compared with prior art, the beneficial effects of the invention are as follows：

1) simplify the input domination set of FCS-MPTC methods, it is to avoid substantial amounts of redundant computation, alleviate digital control The computation burden of system.

2) remain FCS-MPTC methods rapid dynamic response speed, the advantages of robustness is good.

3) present invention is analyzed based on five phase inverter motor driven systems, equally can be with expanded application in other multiphases electricity Machine；The problems such as occasion simultaneously for other power conversions is related to such as power, torque pulsation, current harmonics also provides ginseng Examine value.

Brief description of the drawings

Fig. 1 is the allomeric function block diagram of the inventive method.

Fig. 2 is the schematic diagram for calculating dead beat voltage vector.

Fig. 3 is the block diagram for predicting torque and magnetic linkage.

Fig. 4 is Space Rotating coordinate transform computing block diagram.

Fig. 5 is that the inventive method calculates duration.

Fig. 6 is the calculating duration of MPTC-21 (10 big middle vector+zero vectors of vector+10) method.

Fig. 7 is the motor speed under stable situation, torque and a phase current waveforms (n=550r/min, T_L=8Nm).

Fig. 8 is the motor speed under current intelligence, torque and a phase current waveforms (n=550r/min, T_LJumped by 2Nm Fade to 8Nm).

Specific embodiment

The present invention is further detailed explanation with reference to the accompanying drawings and detailed description.The inventive method significantly subtracts Small amount of calculation, also realizes the PREDICTIVE CONTROL to torque, improves the dynamic response capability of system.Specifically include following steps：

Five-phase induction motor system includes 4 frees degree and zero-sequence component.Under motor normal operating condition, according to the group of extension Be respectively mapped to symmetrical physical quantity under natural system of coordinates under two orthogonal coordinate systems of d1-q1 and d3-q3 by gram rotation transformation. Space vector to the phase voltage source inventer of two level five is classified (table 1), and calculates all kinds of voltage vectors according to formula (1) Amplitude size.

The voltage vector component class of table 1

In formula (1), U_dcRepresent the busbar voltage size of inverter direct-flow side.Vector under d1-q1 coordinate systems is sat with d3-q3 There is corresponding relation in the vector under mark system：Large, medium and small vector under d1-q1 coordinate systems, can be mapped under d3-q3 coordinate systems It is small, in, big vector.

In order to reduce amount of calculation, dead beat voltage vector is calculated first, only choose in sector where dead beat voltage vector 4 vectors (2 middle vectors of big vector+2) as input set, it is to avoid to the redundant computation of unrelated vector.

Surface-mount type five-phase PMSM torque T_eExpression formula be：

In formula, δ represents the power angle between electric machine rotor magnetic linkage, N_pRepresent motor number of pole-pairs, L_dD-axis inductance is represented, ψ_fRepresent the magnetic linkage of permanent magnet, ψ_sRepresent stator magnetic linkage.Stator magnetic linkage amplitude is generally remained in Direct Torque Control constant, Changed come the torque of regulation motor by changing the size of power angle.Generally, power angle and its variable quantity are smaller, can Do approximate processing：

δ≈sinδ (3)

Based on this, the variable quantity △ δ that the torque error according to the k moment calculates required power angle are：

T_e ^refRepresent the set-point of motor speed outer shroud torque.

Magnetic linkage error under α β coordinate systems is calculated according to formula (4)：

ψ_s ^refThe set-point of fundamental wave magnetic linkage is represented, according to motor stator voltage equation, dead beat predicted voltage arrow is can obtain The α β component sizes of amount：

The amplitude and positional information of voltage vector in track with zero error algorithm are tried to achieve finally according to formula (6)：

Dead beat voltage vector in table 2 to gained has carried out Definition of Division.According to the voltage location angle letter being calculated Cease to determine the sector where it.

The sector of table 2 divides and domination set chooses table

According to sector number, traversal prediction is carried out to 4 voltage vectors (2 middle vectors of big vector+2) in its domination set Calculate, optimal vector is chosen further according to object function.Objective function J is：

Wherein i=m, m+1, m+2, m+3；M represents the sector number where dead beat voltage vector in each sampling period； ψ_sd1-q1 ^refRepresent the set-point of first harmonic spatial magnetic linkage；T_e(k+1)、ψ_sd1-q1(k+1) torque of k+1 moment and magnetic linkage are represented respectively Predicted value；ψ_sd3-q3(k+1) predicted value of k+1 moment harmonic wave magnetic linkages is represented；λ₁、λ₂Difference first harmonic spatial harmonic space stator magnet Weight coefficient of the chain component in evaluation function；ψ_sd3-q3 ^refIt is the set-point of harmonic wave space magnetic linkage, in order to suppress stator current Low-order harmonic, its value is disposed as 0.I in object function_max, current protection effect is embodied, its definition is such as formula (9)：

|I_lim| the current limit value for setting is represented, current amplitude after detecting that a certain voltage vector is acted on exceedes maximum The limitation of value, then do not choose the voltage vector；If within the scope of set-point, this regulation for not interfering with object function is made With.

In Fig. 1, whole system is divided into rotor flux and is observed with torque, and dead beat voltage vector is calculated, torque and magnetic linkage are pre- Survey calculating, Space Rotating coordinate transform and calculate four parts.The particular content of wherein major part is：

1) rotor flux is observed with torque

The inventive method needs to go out the voltage vector that kth moment needs apply according to magnetic linkage, torque error inverse, therefore needs Real-time monitored is carried out to rotor flux.The set-point of torque is obtained by speed error by a PI controller.

2) dead beat voltage vector is calculated

Fig. 2 shows the schematic diagram calculation of dead beat voltage vector.Approximate calculation is carried out to power angle, combined torque error is obtained To the expectancy changes amount △ δ of power angle, and calculate the magnetic linkage error under α β coordinate systems.According to magnetic linkage error, indifference is calculated Beat voltage vector and its place sector, 4 voltage vectors (2 big vectors of middle vector+2) in sector are FCS-MPTC side The input set of method.

3) torque is calculated with Flux estimation

In FCS-MPTC methods, the precision of torque prediction calculating section directly affects the control performance of system.Obtaining current is State variable, according to the form of standard state spatial function, state equation is written as：In order to obtain discretization Current of electric state equation, in sampling time T_sHypothesis is made in the case of less：Think system input variable u in kT_s~(k+ 1)T_sIt is constant in time；H represents the influence of back-emf, changes relatively slow for electric current loop, it also hold that H is in kT_s~(k+1) T_sIt is constant in time interval.Torque and the Flux estimation block diagram of figure are obtained, the coefficient matrix in formula is as follows：

The different torque of voltage vector correspondence different in input set and Flux estimation value, combined objective function, to pre- The magnetic linkage of survey is estimated with torque, choose the minimum on off state of target function value as system subsequent time input.

4) Space Rotating coordinate transform is calculated

Fig. 5 gives and transforms to the extension Parker transformation matrices that double d-q coordinate systems are used by five phase rest frames.Pass What sensor was detected is the phase current under usual abcde coordinate systems, and forecast model is carried out under d-q rotating coordinate systems, It is therefore desirable to first by under the current transformation of sensor detection to d1-q1 coordinate systems and d3-q3 coordinate systems.

Claims (4)

1. a kind of five-phase PMSM model prediction method for controlling torque, it is characterised in that comprise the following steps：

Step 1：Voltage, electricity according to the Parker rotation transformation for extending by five-phase PMSM under natural system of coordinates The physical quantitys such as stream, magnetic linkage, torque are respectively mapped under two orthogonal coordinate systems of d1-q1 and d3-q3；

Step 2：Fundamental space voltage vector to the phase voltage source inventer of two level five is classified, and calculates large, medium and small electricity The amplitude of vector is pressed to be respectively：

In formula, U_L, U_M, U_SThe amplitude of large, medium and small voltage vector is represented respectively；U_dcRepresent that the busbar voltage of inverter direct-flow side is big It is small；

Step 3：Torque and magnetic linkage error calculation according to five-phase induction motor go out dead beat voltage vector predicted value, then extract nothing The amplitude and positional information of beat predicted voltage vector；

Step 4：Voltage vector positional information according to being calculated determines the place sector of dead beat voltage vector；

Step 5：Choose input set of 4 vectors in sector where dead beat voltage vector as PREDICTIVE CONTROL；

Step 6：Evaluation is predicted to the voltage vector in domination set to calculate, and chooses the corresponding voltage of minimum value of object function Vector is applied to inverter.

2. a kind of five-phase PMSM model prediction method for controlling torque as claimed in claim 1, it is characterised in that institute Step 3 is stated to be specially：

The variable quantity △ δ that torque error according to the k moment calculates required power angle δ are：

$\mathrm{\Δ}\mathrm{\δ}=\frac{2}{5}\frac{\[T_e^{ref}-T_e\left(k\right)\]L_d}{N_p\left|{\mathrm{\ψ}}_s\right|{\mathrm{\ψ}}_f}$

T_e ^refRepresent the set-point of motor speed outer shroud torque；δ represents the power angle between electric machine rotor magnetic linkage, N_pRepresent electricity Machine number of pole-pairs, L_dRepresent d-axis inductance, ψ_fRepresent the magnetic linkage of permanent magnet, ψ_sRepresent stator magnetic linkage vector；

According to formulaCalculate the stator magnetic linkage error under α β coordinate systems：

$\left\{\begin{array}{c}{\mathrm{\Δ\ψ}}_{\mathrm{\α}}=\left|{{\mathrm{\ψ}}_s}^{ref}\right|cos({\mathrm{\δ}}_s+\mathrm{\Δ}\mathrm{\δ})-\left|{\mathrm{\ψ}}_s\left(k\right)\right|{\mathrm{cos\δ}}_s\\ {\mathrm{\Δ\ψ}}_{\mathrm{\β}}=\left|{{\mathrm{\ψ}}_s}^{ref}\right|sin({\mathrm{\δ}}_s+\mathrm{\Δ}\mathrm{\δ})-\left|{\mathrm{\ψ}}_s\left(k\right)\right|{\mathrm{sin\δ}}_s\end{array}\right.$

ψ_s ^refRepresent the set-point of fundamental wave magnetic linkage；

Component U of the dead beat voltage vector predicted value under two-phase α β rest frames_αAnd U_βFor：

$\left\{\begin{array}{c}{U}_{\mathrm{\α}}=\frac{{\mathrm{\Δ\ψ}}_{\mathrm{\α}}}{T_s}+i_{\mathrm{\α}}{R}_s\\ U_{\mathrm{\β}}=\frac{{\mathrm{\Δ\ψ}}_{\mathrm{\β}}}{T_s}+i_{\mathrm{\β}}{R}_s\end{array}\right.$

Finally according to formulaTry to achieve the amplitude and positional information of voltage vector in dead-beat control method：

$\left\{\begin{array}{c}{U}_{ref}|=\sqrt{{U_{\mathrm{\β}}}^2+{U_{\mathrm{\α}}}^2}\\ {\mathrm{\θ}}_{U_{ref}}=\arctan (U_{\mathrm{\β}}/U_{\mathrm{\α}})\end{array}\right..$

3. a kind of five-phase PMSM model prediction method for controlling torque as claimed in claim 1 or 2, its feature exists In the object function is：

$J=|T_e^{ref}-T_e{(k+1)}_i|+{\mathrm{\λ}}_1|T_{sd1-q1}^{ref}-T_{sd1-q1}{(k+1)}_i|+{\mathrm{\λ}}_2|T_{sd3-q3}^{ref}-T_{sd3-q3}{(k+1)}_i|+I_{\max }$

Wherein, i=m, m+1, m+2, m+3；M represents the sector number where dead beat voltage vector in each sampling period； ψ_sd1-q1 ^refRepresent the set-point of first harmonic spatial stator magnetic linkage；T_e(k+1)、ψ_sd1-q1(k+1) torque of k+1 moment is represented respectively and is determined The predicted value of sub- magnetic linkage；ψ_sd3-q3(k+1) the harmonic prediction value of k+1 moment stator magnetic linkages is represented；ψ_sd3-q3 ^refFor harmonic wave space is fixed The set-point of sub- magnetic linkage；λ₁、λ₂Respectively in the weight coefficient of first harmonic spatial harmonic space stator magnetic linkage component.

4. a kind of five-phase PMSM model prediction method for controlling torque as claimed in claim 3, it is characterised in that

I in object function_maxFor：

$I_{max}=\left\{\begin{array}{cc}0& \left|I_s(k+1)\right|<\left|I_{\lim }\right|\\ \mathrm{\&infin;}& \left|I_s(k+1)\right|\&GreaterEqual;\left|I_{\lim }\right|\end{array}\right.$

|I_lim| the current limit value for setting is represented, current amplitude after detecting that a certain voltage vector is acted on exceedes maximum Limitation, then do not choose the voltage vector.