CN106487303B - A kind of vector control method of permanent magnet synchronous motor - Google Patents

Abstract

A kind of vector control method of permanent magnet synchronous motor, includes the following steps：Step 1, according to controlled quentity controlled variable U_dAnd U_qU is obtained by Park inverse transformations_αAnd U_β；Step 2, according to the static U obtained_αAnd U_βValue carries out the projection scalar U in three phase coordinates_a、U_bAnd U_cCalculating；Step 3, according to the U obtained_a、U_bAnd U_cValue calculates three-phase duty ratio, in conjunction with the projection scalar formula U in three phase coordinates_a、U_bAnd U_cSituation of change, calculate three-phase duty ratio.The present invention provides a kind of vector control methods for simplifying cumbersome flow, reducing size of code, the permanent magnet synchronous motor for shortening conversion time.

Description

A kind of vector control method of permanent magnet synchronous motor

Technical field

The invention belongs to Motor Control Field more particularly to a kind of vector control methods of permanent magnet synchronous motor.

Background technology

Space voltage vector control is the most popular method of permanent magnet synchronous motor control at present, is being obtained largely It promotes.

Fig. 1 depicts the schematic diagram that three-phase PWM inverter supplies electricity to permanent magnet synchronous motor, must to make motor symmetrically work Palpus three-phase is powered simultaneously.A, b, c respectively represent the on off state of three bridge walls, it is specified that：" 1 " expression of upper bridge wall break-over of device, Lower bridge wall break-over of device is indicated with " 0 ", and is arranged in order according to UVW phase sequences.It can derive, the phase voltage of three-phase inverter output Vector [U_u、U_v、U_w]^TWith switch state vector [a, b, c]^TRelationship be：

U in formula_dcIt is direct current power source voltage.

Formula is substituted into space vector of voltage formula U_out=2/3 (U_U+U_Ve^j2π/3+U_We ^j4π/3) obtain corresponding inverter work The relationship of pattern and output voltage, as shown in table 1：

Table 1

By the result of calculation in table 1,8 fundamental space voltage vectors as shown in Figure 2, wherein space voltage vector are obtained Amplitude is equal, is equal to 2U_dc/ 3, phase angle mutual deviation π/3 are denoted as U respectively₀, U₆₀、U₁₂₀、U₁₈₀、U₂₄₀、U₃₀₀, and Zero voltage vector It is denoted as O₀₀₀, O₁₁₁.When inverter individually exports fundamental voltage space vector U₀When, the stator magnetic linkage vector Ψ of motor

Starting end from A to B along being parallel to U₀Direction movement, as shown in Figs 1-4.When being moved to B points, if changed Fundamental voltage space vector is U₆₀Output, then the starting end of stator magnetic linkage vector Ψ is also accordingly changed to the movement from B to C.In this way Go down, after all six non-zero fundamental voltage space vector individually output successively respectively, stator magnetic linkage vector Ψ starting ends Movement locus is a regular hexagon, as shown in Figure 3.

Obviously, can be only formed the rotating excitation field of regular hexagon according to such power supply mode, rather than it is desirable that circle Shape magnetic field.

So we will allow regular hexagon to become the sides N shape, and the number of N is bigger, just closer to circle.Thus need More inverter switching states.One of which method is the linear session group using the fundamental voltage space vector of six non-zeros Conjunction obtains more on off states.

In Fig. 4, U_x+60And U_xRepresent two adjacent fundamental voltage space vectors, U_outIt is the reference phase voltage arrow of output Amount, amplitude represent the amplitude of voltage, and angular velocity of rotation is exactly the angular frequency of the sinusoidal voltage exported.U_outIt can be by U_xAnd U_x+60 Linear ageing synthesis, it is equal to t₁/T_pwmU again_xWith t₂/T_pwmU_x+60Vector sum.Wherein t₁And t₂It is U respectively_xWith U_x+60The time of effect.T_pwmIt it is total period, but t₁And t₂Need not be equal to T_pwm, in general, in T_pwmIn should also wrap Action time t containing zero vector₀And t₇, pass through t₀And t₇Modulation ratio can be controlled, to control the amplitude of resultant vector.It presses According to this mode, in next T_pwmPeriod still uses U_xAnd U_x+60Linear session combination, but action time

t₁' and t₂' different from last time, they must assure that the new space vector of voltage U of synthesis_out' and original voltage Space vector U_outAmplitude it is equal.

So go down, in each T_pwmIt period, can all change the action time of adjacent basic vector, and ensure to synthesize Space vector of voltage amplitude it is all equal, therefore, work as T_pwmWhen sufficiently small, the track of space vector of voltage is an approximate circle The regular polygon of shape.

It can be obtained according to projection of each vector in rectangular coordinate system reference axis in Fig. 4：

|U_out|T_pwmCos θ=t₁|U_x|+t₂|U_x+60|cosπ/3

t₂|U_x+60| sin π/3=| U_out|T_pwmsinθ

It can all obtain as a result,：

|U_x+60|=| U_x|=| U_dc|

t₁=MT_pwmsin(π/3-θ)

t₂₌MT_pwmsinθ

In formula, T_pwmIt can select in advance, according to the PWM wave period of itself, when emulation is limited to 1, U_outIt can be by V/F songs Line determines, can also be arranged according to high tension voltage, θ can be by output sinusoidal voltage angular frequency and nT_pwmProduct determine that M is Debugging ratio.Therefore, as known two adjacent fundamental space vector U_x+60And U_xAfterwards, so that it may to determine action time t₁And t₂。

In figure 3, when inverter individually exports zero vector, the stator magnetic linkage vector of motor is motionless.According to this A feature, in T_pwmPeriod is inserted into the time t of zero vector effect₀, make T_pwm=t₀+t₁+t₂+t₇

By such method, angular frequency can be adjusted, to achieve the purpose that frequency conversion.

Vector controlled is into this thinking：Realize the control method of analog DC motor come to permanent-magnet synchronous by coordinate transform Motor is controlled, and implementation step is as follows：

1) according to magnetic potential and power it is constant pass orthogonal transformation in principle, by three phase static coordinate transform at the static seat of two-phase Mark, that is, Clarke transformation, rest frame is first converted to by the electric current of three-phase, then by rotation transformation by the static seat of two-phase Mark becomes two cordic phase rotators, that is, Park transformation, and stator current is broken down by rotor field-oriented 2 in Park transformation A DC component i_d、i_q(wherein i_dFor excitation current component, i_qFor torque current component).

2) electric current loop is controlled by controller, controls i_dIt is equivalent to control magnetic flux, and controls i_qIt is equivalent to control Torque processed.It is adjusted by PI, obtains the component of voltage i.e. U on d, q axis_dAnd U_q。

3) controlled quentity controlled variable U_dAnd U_qU is obtained by Park inverse transformations_αAnd U_β。

4) output that vector controlled is realized according to traditional Space vector modulation method, achievees the purpose that vector controlled.

Figure it is seen that entire space can be divided into 6 sectors by these basic space vectors, wherein U₀Rotation angle is represented as 0 fundamental space vector, U₆₀Rotation angle is represented as 60 fundamental space vector, U₁₂₀Represent rotation The fundamental space vector that angle is 120, U₁₈₀Rotation angle is represented as 180 fundamental space vector, U₂₄₀Represent rotation angle as 240 fundamental space vector, U₃₀₀Rotation angle is represented as 300 fundamental space vector, considers space voltage arrow shown in figure Measure U_out, can be by U_αAnd U_βIndicate the component on its α axis and β axis in rest frame.Now with U_αAnd U_βBelieve as input Number, with DC bus-bar voltage U_dcAs parameter, 6 required road PWM can be obtained after calculation processing.

The positive and negative of projection according to given space vector of voltage in three phase coordinate system of space may determine that the voltage space Which sector vector is located at.As shown in figure 5, note Ua, Ub and Uc are its projection scalar in three phase coordinates：

According to above formula, the sector N residing for space voltage vector can be determined by following rule：

N=A+2B+4C

Wherein, if U_a>0, then A=1, otherwise A=0

If U_b>0, then B=1, otherwise B=0

If Uc>0, then C=1, otherwise C=0

Common variable X, Y, Z are re-introduced into calculate time t₁And t₂：

According to sector label N determined above, the sector residing for space vector and two boundary vector t can be obtained₁And t₂Make With the relationship of time, as shown in table 2：

Sector N

I

Ⅱ

Ⅲ

Ⅳ

Ⅴ

Ⅵ

t1

Z

Y

-Z

-X

X

-Y

t2

Y

-X

X

Z

-Y

-Z

Table 2

But since the decline of direct current power source voltage may be such that the amplitude of voltage vector reduces, calculate time t₁With t₂The sum of be possible to be more than PWM cycle T_pwmHalf T, i.e. t₁And t₂>T, such case are referred to as saturation.It needs to be repaiied as follows Just：

T is used at this time₁And T₂Instead of t₁And t₂。

Re-define duty cycle parameters T_aon, T_bon, T_con:

Finally, it may be determined that the practical duty ratio T for controlling required three-phase PWM wave_a, T_b, T_c, as shown in table 3：

Sector N

I

Ⅱ

Ⅲ

Ⅳ

Ⅴ

Ⅵ

Ta

Tbon

Taon

Taon

Tcon

Tcon

Tbon

Tb

Taon

Tcon

Tbon

Tbon

Taon

Tcon

Tc

Tcon

Tbon

Tcon

Taon

Tbon

Taon

Table 3

It is the flow of traditional vector control algorithm above.

But traditional control method flow is excessively cumbersome, software code amount is excessive, and conversion time is long.

Invention content

In order to overcome, the flow of the vector control method of existing permanent magnet synchronous motor is cumbersome, software code amount is excessive, conversion The deficiency of overlong time, the present invention provides it is a kind of simplify cumbersome flow, reduce size of code, shorten conversion time permanent magnetism it is same Walk the vector control method of motor.

The technical solution adopted by the present invention to solve the technical problems is：

A kind of vector control method of permanent magnet synchronous motor, the control method include the following steps：

Step 1, according to controlled quentity controlled variable U_dAnd U_qU is obtained by Park inverse transformations_αAnd U_β, formula is as follows：

U α=U_dcosθ-U_qsinθ；

U β=U_qcosθ+U_dsinθ；

In formula, U_dAnd U_qFor the component of voltage on d, q axis, U_αAnd U_βIndicate point on the α axis and β axis in rest frame Amount, θ are space bit angle setting；

Step 2, according to the static U obtained_αAnd U_βValue carries out the projection scalar U in three phase coordinates_a、U_bAnd U_cCalculating, it is public Formula is as follows：

U_a=U_α

Step 3, according to the U obtained_a、U_bAnd U_cValue calculates three-phase duty ratio, public in conjunction with the projection scalar in three phase coordinates Formula U_a、U_bAnd U_cSituation of change, calculate three-phase duty ratio, formula is as follows：

Wherein：T₁For PWM cycle T_pwmHalf, U_maxAnd U_minIt is U_a、U_bAnd U_cIn maximum and minimum value.

Beneficial effects of the present invention are mainly manifested in：Simplify cumbersome flow, reduce size of code, shortens conversion time.

Description of the drawings

Fig. 1 is the Principle of Electric Engine figure of three-phase PWM inverter.

Fig. 2 is three dimensional vector diagram.

Fig. 3 is regular hexagon magnetic linkage track.

Fig. 4 is the linear combination figure of space vector of voltage.

Fig. 5 is Traditional Space voltage vector control schematic diagram.

Fig. 6 is vector controlled schematic diagram.

Fig. 7 is analogous diagram.

Fig. 8 is SVPWM module composition figures.

Fig. 9 is vector control module figure.

Figure 10 is emulation three-phase duty ratio waveform.

Figure 11 is emulation three-phase current waveform.

Figure 12 is emulation rotation speed change waveform.

Specific implementation mode

The invention will be further described below in conjunction with the accompanying drawings.

With reference to Fig. 6~Figure 12, a kind of vector control method of permanent magnet synchronous motor, the area with traditional vector control algorithm It is not that this vector control algorithm need not carry out action time calculating, sector calculates and time saturation judges, simplifies cumbersome stream Journey includes the following steps：

Step 1, according to controlled quentity controlled variable U_dAnd U_qU is obtained by Park inverse transformations_αAnd U_β, formula is as follows：

U α=U_dcosθ-U_qsinθ；

U β=U_qcosθ+U_dsinθ；

In formula, U_dAnd U_qFor the component of voltage on d, q axis, U_αAnd U_βIndicate point on the α axis and β axis in rest frame Amount, θ are space bit angle setting；

Step 2, according to the static U obtained_αAnd U_βValue carries out the projection scalar U in three phase coordinates_a、U_bAnd U_cCalculating, it is public Formula is as follows：

U_a=U_α

Step 3, according to the U obtained_a、U_bAnd U_cValue calculates three-phase duty ratio, and traditional vector controlled is needed according to rule First to judge the sector residing for space voltage vector, be sweared then in conjunction with two boundaries further according to the sector obtained residing for space vector The action time of amount calculates three-phase duty ratio.And this vector controlled only needs to combine the projection scalar formula in three phase coordinates U_a、U_bAnd U_cSituation of change, calculate three-phase duty ratio, formula is as follows：

Wherein：T₁For PWM cycle T_pwmHalf, U_maxAnd U_minIt is U_a、U_bAnd U_cIn maximum and minimum value.

Simulation model is as follows：By building SVPWM modules, which is added in entire illustraton of model, such as Fig. 7 and Fig. 8 institutes Show, Fig. 7 is vehicle simulation model, and Fig. 8 is Vector Control Model.The flow entirely converted is that rotating speed of target is obtained by rotating speed model To the I of target_dAnd I_q, in conjunction with the I obtained by the coordinate transform of Clark and Park by motor three-phase current_dAnd I_qValue of feedback, U is obtained by electric current loop_dAnd U_q。U_dAnd U_qBy Vector Control Model, three-phase duty ratio T is obtained_a、T_b、T_c。T_a、T_b、T_cIn conjunction with The three-phase current I to output that high tension voltage passes through three-phase voltage model and motor model_a、I_b、I_cAnd actual speed.It obtains Three-phase duty ratio is as shown in figure 9, three-phase duty ratio T as seen from the figure_a、T_b、T_cWaveform and tradition are such as schemed without any difference Shown in 10, three-phase current I as seen from the figure_a、I_b、I_cSine degree it is very good.As shown in figure 11, actual speed can be steady Reach rotating speed of target, such as current goal rotating speed is 1500 turns, after emulation, 1500 can steadily be reached by measuring actual speed Turn.

Claims (1)

1. a kind of vector control method of permanent magnet synchronous motor, it is characterised in that：The control method includes the following steps：

Step 1, according to controlled quentity controlled variable U_dAnd U_qU is obtained by Park inverse transformations_αAnd U_β, formula is as follows：

U α=U_dcosθ-U_qsinθ；

U β=U_qcosθ+U_dsinθ；

In formula, U_dAnd U_qFor the component of voltage on d, q axis, U_αAnd U_βIndicate that the component on the α axis and β axis in rest frame, θ are Space bit angle setting；

Step 2, according to the static U obtained_αAnd U_βValue carries out the projection scalar U in three phase coordinates_a、U_bAnd U_cCalculating, formula is such as Under：

U_a=U_α

Step 3, according to the U obtained_a、U_bAnd U_cValue calculates three-phase duty ratio, in conjunction with the projection scalar formula U in three phase coordinates_a、 U_bAnd U_cSituation of change, calculate three-phase duty ratio, formula is as follows：

Wherein：T₁For PWM cycle T_pwmHalf, U_maxAnd U_minIt is U_a、U_bAnd U_cIn maximum and minimum value.