CN103904975B - A kind of control method of salient-pole synchronous motor - Google Patents

Abstract

The present invention relates to a kind of control method of salient-pole synchronous motor, first by dq coordinate system transformation to jm coordinate system, by coordinate conversion relation, the electromagnetic torque expression formula of salient-pole synchronous motor under dq coordinate system is converted, obtain a kind of electromagnetic torque expression formula that reluctance torque is decomposed, then according to the magnitude relationship of d-axis and q-axis inductance, select the reservation item in reluctance torque, thus realize the control to salient-pole synchronous motor.Control procedure is insensitive to parameter, there is not curve, and robustness comparatively MTPA method effectively improves.In whole control procedure of the present invention, only need three-phase current and the rotor position information of knowing salient-pole synchronous motor, and d-axis and q-axis inductance L _d, L _qmagnitude relationship, insensitive to parameter of electric machine change, control simple, vulnerability to jamming is good, speed-regulating range width.

Description

A kind of control method of salient-pole synchronous motor

Technical field

The present invention relates to a kind of control method of salient-pole synchronous motor, being a kind of control method by decomposing salient-pole synchronous motor cogging torque, belonging to variable frequency ac drive technical field.

Background technology

At present, the advantages such as vector control technology is accurate with speeds control, torque pulsation is little, speed-regulating range width are widely used at synchronous motor transmission field.For the vector control of salient-pole synchronous motor, in order to make full use of its reluctance torque, and create breakdown torque current ratio (MTPA) control method.From the derivation of MTPA method, MTPA can obtain optimum ac-dc axis electric current distribution effects, thus realizes using minimum electric current to obtain maximum electromagnetic torque, and theoretically, this is a kind of desirable control program.But in the middle of practical application, MTPA can not reach its due effect.Main cause has: (1) is in the process of its theory deduction, use the rotor flux of motor, the parameters of electric machine such as ac-dc axis inductance, because these parameters are in the running of motor, constantly change along with the change of motor speed, temperature and electric current, and be nonlinear change, the Immunity Performance of control system is deteriorated.So in actual applications, the optimum allocation of ac-dc axis electric current and the control effects of expection can not be realized, and can torque pulsation be caused, affect control precision further.(2) due in MTPA control method, the computing formula of ac-dc axis electric current is very complicated, common way is offline simulation ac-dc axis electric current distribution curve, then be written in the microcontroller such as single-chip microcomputer, DSP and control in real time, a kind of error on the whole can only be met minimum by the known this offline simulation method of the relevant knowledge of numerical analysis method, so larger error may can be there is in some part, thus cause control precision to be deteriorated, in conjunction with reason described in (1), control effects can be deteriorated further.

Summary of the invention

The technical problem solved

In order to avoid the deficiencies in the prior art part, the present invention proposes a kind of control method of salient-pole synchronous motor, and solving breakdown torque current ratio (MTPA) method affects larger problem by parameter and calculating in actual use.

Technical scheme

A control method for salient-pole synchronous motor, decomposes reluctance torque, then by the magnitude relationship of d-axis and q-axis inductance, selects the reservation item in reluctance torque, thus realizes the control to salient-pole synchronous motor.Technical characteristic is it successively containing following steps:

Step 1: according to given rotating speed n ^*carry out PI adjustment with the difference of feedback rotating speed n, obtain given quadrature axis current $i_q^{*}=K_{\mathrm{pn}}\·e_n+K_{\mathrm{in}}\∫e_n\mathrm{dt},K_{\mathrm{pn}}>0,K_{\mathrm{in}}>0;$ Wherein: K _pn, K _inbe respectively the ratio of pi regulator, integral coefficient; e _n=n ^*-n;

Step 2: according to given quadrature axis current with feedback quadrature axis current i _qdifference carry out PI adjustment, obtain given quadrature-axis voltage $u_q^{*}=K_{\mathrm{pq}}\·e_{\mathrm{iq}}+K_{\mathrm{iq}}\∫e_{\mathrm{iq}}\mathrm{dt},K_{\mathrm{pq}}>0,K_{\mathrm{iq}}>0;$ Wherein: K _pq, K _iqbe respectively the ratio of pi regulator, integral coefficient; $e_{\mathrm{iq}}=i_q^{*}-i_q;$

Step 3: according to the magnitude relationship of d-axis and q-axis inductance, under selecting jm coordinate system, corresponding current component carries out closed-loop adjustment, after current PI adjuster, exports given direct-axis voltage concrete steps are as follows:

Dq axis coordinate system is turned clockwise 45 ° by step (a), obtains jm coordinate system;

Step (b) is by coordinate transform formula by current i _d, i _qobtain current i _j, i _m;

Step (c) obtains d-axis and q-axis inductance L according to the type of motor _dand L _qif, L _d>L _q, with current component i _mcarry out closed-loop adjustment, given parameters is feedback parameter is i _m;

If L _d<L _q, with current component i _jcarry out closed-loop adjustment, given parameters is feedback parameter is i _j;

Step 4: carry out PI adjustment with the difference of the given parameters and feedback parameter that carry out the current component of closed-loop control in step 3, obtain given direct-axis voltage $u_d^{*}=K_{\mathrm{pd}}\&CenterDot;e_{\mathrm{id}}+K_{\mathrm{id}}\&Integral;e_{\mathrm{id}}\mathrm{dt},K_{\mathrm{pd}}>0,K_{\mathrm{id}}>0;$ Wherein: K _pd, K _idbe respectively the ratio of pi regulator, integral coefficient;

If the current component carrying out closed-loop control is i _m, so

If the current component carrying out closed-loop control is i _j, so

Step 5: by given rectangular axis component of voltage obtain given space voltage vector according to space vector width pulse modulation method pair carry out Vector modulation, obtain the control signal required for inverter.

The parameter of 3 described pi regulators, needs to regulate according to salient-pole synchronous motor self character and system performance requirements.

Beneficial effect

The control method of a kind of salient-pole synchronous motor that the present invention proposes, control principle block diagram is as shown in Figure 1: first by dq coordinate system transformation to jm coordinate system, as shown in Figure 2, by coordinate conversion relation, the electromagnetic torque expression formula of salient-pole synchronous motor under dq coordinate system is converted, obtain a kind of electromagnetic torque expression formula that reluctance torque is decomposed, then according to the magnitude relationship of d-axis and q-axis inductance, select the reservation item in reluctance torque, thus realize the control to salient-pole synchronous motor.Control procedure is insensitive to parameter, there is not curve, and robustness comparatively MTPA method effectively improves.

The inventive method has following beneficial effect:

(1) in whole control procedure of the present invention, three-phase current and the rotor position information of knowing salient-pole synchronous motor is only needed, and d-axis and q-axis inductance L _d, L _qmagnitude relationship, insensitive to parameter of electric machine change, control simple, vulnerability to jamming is good, speed-regulating range width;

(2) the present invention is not owing to needing to carry out the work such as the curve of traditional MTPA, so the error not having curve to bring, programming is simple, and torque pulsation is little, and computational speed is fast, and the robustness of control effectively improves.

Accompanying drawing explanation

Fig. 1: control principle block diagram

Fig. 2: dq coordinate system and jm coordinate system

Fig. 3: dq coordinate system electric current is to the conversion of jm coordinate system electric current

Fig. 4: load torque change curve

Fig. 5: simulation result---A phase current, rotating speed, electromagnetic torque curve

Embodiment

Now in conjunction with the embodiments, the invention will be further described for accompanying drawing:

The present invention decomposes reluctance torque, then by the magnitude relationship of d-axis and q-axis inductance, selects the reservation item in reluctance torque, thus realizes the control to salient-pole synchronous motor.Technical characteristic is it successively containing following steps:

(1) according to given rotating speed n ^*carry out PI adjustment with the difference of feedback rotating speed n, obtain given quadrature axis current $i_q^{*}=K_{\mathrm{pn}}\&CenterDot;e_n+K_{\mathrm{in}}\&Integral;e_n\mathrm{dt},K_{\mathrm{pn}}>0,K_{\mathrm{in}}>0;$ Wherein, K _pn, K _inbe respectively the ratio of pi regulator, integral coefficient, e _n=n*-n;

(2) according to given quadrature axis current with feedback quadrature axis current i _qdifference carry out PI adjustment, obtain given quadrature-axis voltage $u_q^{*}=K_{\mathrm{pq}}\&CenterDot;e_{\mathrm{iq}}+K_{\mathrm{iq}}\&Integral;e_{\mathrm{iq}}\mathrm{dt},K_{\mathrm{pq}}>0,K_{\mathrm{iq}}>0;$ Wherein, K _pq, K _iqbe respectively the ratio of pi regulator, integral coefficient, $e_{\mathrm{iq}}=i_q^{*}-i_q.$

(3) in the I district shown in Fig. 1 first by rectangular axis current transformation under jm coordinate system, according to the magnitude relationship of d-axis and q-axis inductance, under selecting jm coordinate system, corresponding current component carries out closed-loop adjustment, after current PI adjuster, exports given direct-axis voltage concrete steps are as follows:

A dq axis coordinate system is turned clockwise 45 ° by (), obtain jm coordinate system;

B () is by coordinate transform formula

$\left[\begin{array}{c}{i}_j\\ i_m\end{array}\right]=\frac{\sqrt{2}}{2}\left[\begin{array}{cc}1& 1\\ 1& -1\end{array}\right]\left[\begin{array}{c}{i}_d\\ i_q\end{array}\right]---\left(1\right)$

By current i _d, i _qobtain current i _j, i _m;

C () obtains d-axis and q-axis inductance L by the type of motor _d, L _qsize, if L _d>L _q, so closed-loop parameters is i _m, be namely given as i _m=0, feedback parameter is i _m; If L _d<L _q, so closed-loop parameters is i _j, be namely given as i _j=0, feedback parameter is i _j.Here respectively for embedded permanent magnetic synchronous motor and salient pole type electrically excited synchronous motor, the selection of closed loop current component is described:

1. the electromagnetic torque expression formula under embedded permanent magnetic synchronous motor dq coordinate system is

$T_{\mathrm{em}}=\frac{3}{2}{p}_n({\mathrm{\&psi;}}_d{i}_q-{\mathrm{\&psi;}}_q{i}_d)=\frac{3}{2}{p}_n[{\mathrm{\&psi;}}_f{i}_q+(L_d-L_q)i_d{i}_q]---\left(2\right)$

In formula, T _em: electromagnetic torque; p _n: number of pole-pairs; ψ _d: d axle magnetic linkage; ψ _q: q axle magnetic linkage.

Obtained by formula (1)

$T_{\mathrm{em}}=\frac{3}{2}{p}_n{\mathrm{\&psi;}}_f{i}_q+\frac{{3p}_n}{4}(L_d-L_q)(i_j^2-i_m^2)---\left(3\right)$

In embedded permanent magnetic synchronous motor, there is L _d<L _q, i.e. L _d-L _q<0, again because all be more than or equal to 0, therefore, can control i _j=0, then electromagnetic torque expression formula becomes

$T_{\mathrm{em}}=\frac{3}{2}{p}_n{\mathrm{\&psi;}}_f{i}_q-\frac{{3p}_n}{4}(L_d-L_q)i_m^2---\left(4\right)$

2. the electromagnetic torque expression formula under salient pole type electrically excited synchronous motor (undamped winding) dq coordinate system is

$T_{\mathrm{em}}=\frac{3}{2}{p}_n({\mathrm{\&psi;}}_d{i}_q-{\mathrm{\&psi;}}_q{i}_d)=\frac{3}{2}{p}_n[M_{\mathrm{af}}{i}_f{i}_q+(L_d-L_q)i_d{i}_q]---\left(5\right)$

In formula, M _af: the amplitude of stator one phase winding and excitation winding mutual inductance; i _f: exciting current.

Obtained by formula (1)

$T_{\mathrm{em}}=\frac{3}{2}{p}_n{M}_{\mathrm{af}}{i}_q+\frac{{3p}_n}{4}(L_d-L_q)(i_j^2-i_m^2)---\left(6\right)$

In salient pole type electrically excited synchronous motor, there is L _d>L _q, i.e. L _d-L _q>0, again because all be more than or equal to 0, therefore, can control i _m=0, then electromagnetic torque expression formula becomes

$T_{\mathrm{em}}=\frac{3}{2}{p}_n{M}_{\mathrm{af}}{i}_f{i}_q-\frac{{3p}_n}{4}(L_d-L_q)i_j^2---\left(7\right)$

As can be seen from the electromagnetic torque expression formula of embedded permanent magnetic synchronous motor and salient pole type electrically excited synchronous motor (undamped winding), first the control method that the present invention proposes decomposes reluctance torque, then determines reservation item concrete in reluctance torque.

(4) set-point of closed loop current component selected in step (2) and the difference of value of feedback are carried out PI adjustment, obtain given direct-axis voltage $u_d^{*}=K_{\mathrm{pd}}\&CenterDot;e_{\mathrm{id}}+K_{\mathrm{id}}\&Integral;e_{\mathrm{id}}\mathrm{dt},K_{\mathrm{pd}}>0,K_{\mathrm{id}}>0;$ Wherein, K _pd, K _idbe respectively the ratio of pi regulator, integral coefficient, if closed loop current component is chosen as i _m, so if closed loop current component selects i _j, so

(5) by given rectangular axis component of voltage obtain given space voltage vector according to space vector width pulse modulation method pair carry out Vector modulation, obtain the control signal required for inverter.

Specific embodiment is as follows:

Matlab2008b/Simulink6.0 is adopted to carry out simulating, verifying.The salient-pole synchronous motor adopted in emulation is an embedded permanent magnetic synchronous motor, and design parameter is: number of pole-pairs p _n=6; Stator winding resistance R _s=0.03048 Ω; D-axis inductance L _d=0.602mH; Quadrature axis inductance L _q=1.295mH; Permanent magnet flux linkage Ψ _r=0.0566wb; Given rotating speed n ^*=1500rpm.Simulated conditions is specially: simulation time is 0.2s, and simulation step length is 1e-5, and calculation method is ode4(Runge-Kutta); Starting duty torque is elevated to 15Nm when being 10Nm, 0.08s gradually, drops to 5Nm gradually during 0.15s, until emulation terminates during 0.2s, concrete load torque change curve as shown in Figure 4.

The concrete steps that embodiment comprises are as follows:

1. obtain current rotor position θ and rotating speed n and stator three-phase current i by the simulation model of permanent magnet synchronous motor _a, i _b, i _c;

2. calculate the current component of permanent magnet synchronous motor under dq coordinate system:

(2.1). calculate the component of permanent magnet synchronous motor stator current under α β coordinate system by following formula:

$\left[\begin{array}{c}{i}_{\mathrm{\&alpha;}}\\ i_{\mathrm{\&beta;}}\end{array}\right]=\frac{3}{2}\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& -\frac{\sqrt{3}}{2}\end{array}\right]\left[\begin{array}{c}{i}_A\\ i_B\\ i_C\end{array}\right]---\left(8\right)$

(2.2). calculate the component of permanent magnet synchronous motor stator current under dq coordinate system by following formula:

$\left[\begin{array}{c}{i}_d\\ i_q\end{array}\right]=\left[\begin{array}{cc}\cos \mathrm{\&theta;}& \sin \mathrm{\&theta;}\\ -\sin \mathrm{\&theta;}& \cos \mathrm{\&theta;}\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{\&alpha;}}\\ i_{\mathrm{\&beta;}}\end{array}\right]---\left(9\right)$

3. calculate i by following steps _j, i _m:

(3.1). dq coordinate system is turned clockwise 45 °, obtain jm coordinate system;

(3.2). calculate the current component of permanent magnet synchronous motor stator current under jm coordinate system by following formula

$\left[\begin{array}{c}{i}_j\\ i_m\end{array}\right]=\frac{\sqrt{2}}{2}\left[\begin{array}{cc}1& 1\\ 1& -1\end{array}\right]\left[\begin{array}{c}{i}_d\\ i_q\end{array}\right]---\left(10\right)$

4. judge d-axis and q-axis inductance L _d, L _qsize, determine closed loop current component: because L _d<L _q, so closed-loop parameters is i _j, be namely given as i _j=0, feedback parameter is i _j;

5. the operation control of permanent magnet synchronous motor is implemented by following steps:

(5.1). the regulating parameter of setting speed ring pi regulator is respectively K _pn=5, K _in=1; The regulating parameter K of setting two electric current loop pi regulators _pq=50, K _iq=10, K _pd=50, K _id=10;

(5.2). obtain given quadrature-axis voltage u by following steps _q*:

(5.2.1). $e_{\mathrm{iq}}=i_q^{*}-i_q;$

(5.2.2). $u_q^{*}=K_{\mathrm{pq}}\&CenterDot;e_{\mathrm{iq}}+K_{\mathrm{iq}}\&Integral;e_{\mathrm{iq}}\mathrm{dt};$

(5.3). obtain given direct-axis voltage by following steps

(5.3.1). $e_{\mathrm{id}}=i_j^{*}-i_j;$

(5.3.2). $u_d^{*}=K_{\mathrm{pd}}\&CenterDot;e_{\mathrm{id}}+K_{\mathrm{id}}\&Integral;e_{\mathrm{id}}\mathrm{dt};$

(5.4). according to the given quadrature-axis voltage that rotor position and (5.2) of permanent magnet synchronous motor draw (5.3) the given direct-axis voltage drawn by the component of following formula calculating voltage vector under α β coordinate system:

$\left[\begin{array}{c}{u}_{\mathrm{\&alpha;}}^{*}\\ u_{\mathrm{\&beta;}}^{*}\end{array}\right]=\left[\begin{array}{cc}\cos \mathrm{\&theta;}& -\sin \mathrm{\&theta;}\\ \sin \mathrm{\&theta;}& \cos \mathrm{\&theta;}\end{array}\right]\left[\begin{array}{c}{u}_d^{*}\\ u_q^{*}\end{array}\right]---\left(11\right)$

(5.5). carry out voltage vector synthesis according to space vector width pulse modulation method, calculate the threephase switch control signal S required for inverter by following steps _a, S _b, S _c:

(5.5.1) sector residing for resultant vector is judged:

By known input order

$\left\{\begin{array}{c}{u}_1=u_{\mathrm{\&beta;}}^{*}\\ u_2=\sqrt{3}{u}_{\mathrm{\&alpha;}}^{*}-u_{\mathrm{\&beta;}}^{*}\\ u_3=-\sqrt{3}{u}_{\mathrm{\&alpha;}}^{*}-u_{\mathrm{\&beta;}}^{*}\end{array}\right.---\left(12\right)$

N is obtained: if u by following principle ₁> 0, then A=1, otherwise A=0; If u ₂> 0, then B=1, otherwise B=0; If u ₃> 0, then C=1, otherwise C=0.Then N=A+2B+4C.

After obtaining N value, corresponding relation as shown in Table 1, obtains sector residing for resultant vector.

The corresponding relation of table 1N value and sector

N	1	2	3	4	5	6
							Sector number	Ⅱ	Ⅵ	Ⅰ	Ⅳ	Ⅲ	Ⅴ

(5.5.2) action time of adjacent two vectors that this sector is corresponding is determined: order

$\left\{\begin{array}{c}X=\frac{\sqrt{3}{T}_s}{U_{\mathrm{dc}}}{u}_{\mathrm{\&beta;}}\\ Y=\frac{\sqrt{2}{T}_s}{2U_{\mathrm{dc}}}(\sqrt{3}{u}_{\mathrm{\&alpha;}}+u_{\mathrm{\&beta;}})\\ Z=\frac{\sqrt{3}{T}_s}{2U_{\mathrm{dc}}}(-\sqrt{3}{u}_{\mathrm{\&alpha;}}+u_{\mathrm{\&beta;}})\end{array}\right.---\left(13\right)$

Then blended space voltage vector the action time of adjacent two space vector of voltage can be obtained by table 2.Wherein, T _xrepresent the action time of the last vector in adjacent two vectors, T _ythe action time of a vector after representing.

Table 2 vector table action time

Sector number

Ⅰ

Ⅱ

Ⅲ

Ⅳ

Ⅴ

Ⅵ

T X

-Z

Z

X

-X

-Y

Y

T Y

X

Y

-Y

Z

-Z

-X

When calculating (T _x+ T _y) > T _stime, produce saturated, make zero vector action time be negative value, therefore will process saturation time.As (T _x+ T _y) > T _stime, order

$\left\{\begin{array}{c}{T}_X=\frac{T_X}{T_X+T_Y}{T}_s\\ T_y=\frac{T_Y}{T_X+T_Y}{T}_s\end{array}\right.---\left(14\right)$

(5.5.3) the calculating voltage space vector switching point time, order

$\left\{\begin{array}{c}{T}_{\mathrm{\&alpha;}}=\frac{T_s-T_X-T_Y}{4}\\ T_b=T_a+\frac{T_X}{2}\\ T_c=T_b+\frac{T_Y}{2}\end{array}\right.---\left(15\right)$

Then the space vector of voltage switching point time can be tabled look-up and 3 to be drawn.T in table 3 _cm1, T _cm2, T _cm3be respectively the space vector of voltage switching point moment.

Table 3 space vector of voltage switching point timetable

Sector number

Ⅰ

Ⅱ

Ⅲ

Ⅳ

Ⅴ

Ⅵ

T cm1

T a

T b

T c

T c

T b

T a

T cm2

T b

T a

T a

T b

T c

T c

T cm3

T c

T c

T b

T a

T a

T b

(5.5.4) pulse generate

By the T calculated _cm1, T _cm2, T _cm3as modulating wave compared with carrier wave, finally obtain the control signal S of inverter _a, S _b, S _c, drive motors, realizes controlling functions.

Final acquisition simulation result as shown in Figure 5.

Claims (2)

1. a control method for salient-pole synchronous motor, is characterized in that step is as follows:

Step 1: according to given rotating speed n ^*carry out PI adjustment with the difference of feedback rotating speed n, obtain given quadrature axis current k _pn> 0, K _in> 0; Wherein: K _pn, K _inbe respectively the ratio of pi regulator, integral coefficient; e _n=n ^*-n;

Step 2: according to given quadrature axis current with feedback quadrature axis current i _qdifference carry out PI adjustment, obtain given quadrature-axis voltage k _pq> 0, K _iq> 0; Wherein: K _pq, K _iqbe respectively the ratio of pi regulator, integral coefficient;

Step 3: according to the magnitude relationship of d-axis and q-axis inductance, under selecting jm coordinate system, corresponding current component carries out closed-loop adjustment, after current PI adjuster, exports given direct-axis voltage concrete steps are as follows:

Dq axis coordinate system is turned clockwise 45 ° by step (a), obtains jm coordinate system;

Step (b) is by coordinate transform formula $\left[\begin{array}{c}{i}_j\\ i_m\end{array}\right]=\frac{\sqrt{2}}{2}\left[\begin{array}{cc}1& 1\\ 1& -1\end{array}\right]\left[\begin{array}{c}{i}_d\\ i_q\end{array}\right],$ By current i _d, i _qobtain current i _j, i _m;

Step (c) obtains d-axis and q-axis inductance L according to the type of motor _dand L _qif, L _d>L _q, with current component i _mcarry out closed-loop adjustment, given parameters is feedback parameter is i _m;

If L _d<L _q, with current component i _jcarry out closed-loop adjustment, given parameters is feedback parameter is i _j;

Step 4: carry out PI adjustment with the difference of the given parameters and feedback parameter that carry out the current component of closed-loop control in step 3, obtain given direct-axis voltage k _pd> 0, K _id> 0; Wherein: K _pd, K _idbe respectively the ratio of pi regulator, integral coefficient;

If the current component carrying out closed-loop control is i _m, so

If the current component carrying out closed-loop control is i _j, so

Step 5: given rectangular axis component of voltage the component of voltage vector under α β coordinate system is obtained after Park inverse transformation again according to space vector width pulse modulation method pair carry out voltage vector synthesis, obtain the control signal required for inverter.

2. the control method of salient-pole synchronous motor according to claim 1, is characterized in that: the parameter of 3 described pi regulators, needs to regulate according to salient-pole synchronous motor self character and system performance requirements.