CN103701395A - Positive and negative sequence harmonic injection-based motor rotor primary position estimation method - Google Patents

Abstract

The invention discloses a positive and negative sequence harmonic injection-based motor rotor primary position estimation method. The method improves the estimation angel error generated when a traditional rotary high-frequency injection method is used for estimating a d axis position. A stator resistor and a nonlinear feature of an inverter dead zone are comprised, and influences of line time delay and filter delay on the rotor primary position are analyzed, so the primary d axis position of a rotor can be more accurately, faster and more stably estimated; the polarity of magnetic pole of a permanent magnet is distinguished by a magnetic saturation effect on the d axis through estimation, and finally the accurate rotor primary angle is obtained. The positive and negative sequence harmonic injection-based motor primary position estimation method is easy to realize, has very strong antijamming capacity, and can more accurately, faster and more stably measure the primary position of the rotor.

Description

A kind of rotor initial position method of estimation of injecting based on positive and negative sequence harmonic wave

Technical field

The invention belongs to technical field of motors, be specifically related to a kind of rotor initial position method of estimation of injecting based on positive and negative sequence harmonic wave.

Background technology

Therefore will accurately control the motion state of permagnetic synchronous motor, need to know the rotor-position signal that motor is real-time, traditional magneto is general adopts additional position transducer, is used for detection rotor position.Yet employing position transducer has not only increased the complexity of cost and electric machine structure, and in some high temperature, high pressure or severe corrosive environment, position transducer can reduce reliability or the transducer of system and cannot normally work.Therefore the position Sensorless Control that, realizes permanent magnet synchronous motor has become one of important directions of permanent magnet motor control technology development in recent years.At present, the position Sensorless Control of permanent magnet motor adopts back-emf detection method, high frequency signal injection method or flux observer method etc. mostly.

Publication number is that the patent of CN1286525 discloses and a kind ofly by detecting the method for back-emf zero crossing, is used for determining rotor-position, and its antijamming capability is strong, and position probing is accurate, but several specific positions of back-emf zero crossing can only be detected.The patent that and for example publication number is CN101534088 discloses a kind of definite method of rotor-position, it is by injecting higher harmonic components, through complicated treatment circuit, draw rotor-position signal, but its antijamming capability a little less than, simultaneously because extracted high order harmonic component amount is less, to having relatively high expectations of signal processing circuit, and also there is larger error in result.

Utilize in recent years the method for flux observer principle detection rotor position signalling to obtain very large development, its main advantage is to access continuous rotor-position signal, and for advanced algorithms such as vector control, direct torque control, this is very important.Compare with Harmonic Injection Method, flux observer method does not need complicated modulate circuit just can obtain relatively accurate rotor position angle, and the antijamming capability of circuit is also improved.But existing magneto flux observer is mainly based on stator rest frame, if publication number is disclosed method in CN202059359U and CN102340278A, be all through computing, permanent magnet flux linkage component in stator magnetic linkage to be resolved out, thereby can calculate continuous rotor-position signal.This method is comparatively extensive in the application of the Sensorless Control Technique field of motor, and technology is also comparatively ripe, but the intermediate quantity in computational process is of ac, all higher to the computational speed of processor and required precision, affected by intermediate link filter amplitude-frequency characteristic and phase-frequency characteristic.This algorithm is for non-salient pole permanent magnet motor, computational process is comparatively simple, and easily realize, intermediate computations link also can be simplified, but for salient pole machine, in computational process, need to estimate roughly in advance rotor-position, then estimated value is proofreaied and correct, greatly increased thus amount of calculation, and increased the error of observed result, computational process required time increases simultaneously, makes the dynamic property variation of control system.Flux observer in pilot process in order to eliminate the impact of the noise that electromagnetic interference introduces, generally can suitably add some filters, these filters can observe resulting rotor-position signal cause error in various degree to the observer of this principle, and produce error in various degree along with the difference of load and rotating speed.

Summary of the invention

For the existing above-mentioned technical problem of prior art, the invention provides a kind of rotor initial position method of estimation of injecting based on positive and negative sequence harmonic wave, can be more accurately, the initial position that records rotor of fast and stable.

A rotor initial position method of estimation of injecting based on positive and negative sequence harmonic wave, comprises the steps:

(1) to motor stator winding, injecting amplitude is V _cangular frequency is w _cforward harmonic voltage; Through static alpha-beta coordinate system transformation, to synchronous rotary d-q coordinate system, obtain the voltage vector V of forward harmonic voltage under synchronous rotary d-q coordinate system _dq;

(2) according to voltage vector V _dq, calculate and try to achieve the current phasor I of motor stator electric current under synchronous rotary d-q coordinate system _dq;

(3) through synchronous rotary d-q coordinate system transformation to static alpha-beta coordinate system, obtain the current phasor I of stator current under static alpha-beta coordinate system _{α β};

(4) from current phasor in extract electric current negative sequence component

to electric current negative sequence component

carry out successively low-pass filtering and rotate demodulation obtaining electric current negative sequence component

(5) according to electric current negative sequence component

by following relational expression arctangent computation, obtain negative phase-sequence phase theta ₁;

$\begin{array}{cc}{I}_{\mathrm{\&alpha;\&beta;}2}^{-}=I_{\mathrm{cp}}{e}^{j{\mathrm{\&theta;}}_1}& I_{\mathrm{cp}}=\end{array}\sqrt{I_{}{{R2}_{}}^2+{I_{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="HDA0000451935510000011.png"\; state="\{\{state\}\}">R</figure-callout>}1}}^2}$

$\begin{array}{cc}{I}_{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="HDA0000451935510000011.png"\; state="\{\{state\}\}">R</figure-callout>}1}=\frac{I_{\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="HDA0000451935510000011.png"\; state="\{\{state\}\}">r</figure-callout>}1}}{2}+\frac{I_{r3}}{2}& I_{R2}=\frac{I_{r2}}{2}+\frac{I_{r2}}{2}+\frac{I_{r4}}{2}\end{array}$

$\begin{array}{cccc}{I}_{\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="HDA0000451935510000011.png"\; state="\{\{state\}\}">r</figure-callout>}1}=\frac{V_c\&CenterDot;r}{r^2+{L_d}^2{w_c}^2}& I_{r2}=\frac{V_c\&CenterDot;L_d\&CenterDot;w_c}{r^2+{L_d}^2{w_c}^2}& I_{r3}=\frac{V_c\&CenterDot;r}{r^2+{L_q}^2{w_c}^2}& I_{r4}=\frac{V_c\&CenterDot;L_q\&CenterDot;w_c}{r^2+{L_q}^2{w_c}^2}\end{array}$

Wherein: L _dand L _qbe respectively d axle inductive component and the q axle inductive component of motor stator inductance under synchronous rotary d-q coordinate system, r is stator resistance, and j is imaginary unit;

(6) to motor stator winding, inject the negative sense harmonic voltage of identical amplitude same angular frequency, according to step (1) to (5), in like manner calculate the current phasor I of stator current under static alpha-beta coordinate system _{α β}and therefrom extract electric current positive sequence component

and then to electric current positive sequence component

carry out low-pass filtering and rotate demodulation obtaining electric current positive sequence component

according to electric current positive sequence component

pass through relational expression

arctangent computation obtains positive sequence phase theta ₂;

(7), according to following relational expression, determine the angle theta of synchronous rotary d-q coordinate system d axle and static alpha-beta coordinate system α axle:

If θ ₁>=θ ₂, θ=0.5*[θ ₁-0.5* (θ ₁-θ ₂)];

If θ ₁≤ θ ₂, θ=0.5*[θ ₁+ π-0.5* (θ ₁+ π-θ ₂)];

(8) according to angle theta, by the magnetic saturation effect on d axle, distinguish the polarity of permanent magnet pole, and then the rotor initial angle of definite motor.

In described step (1), according to following formula, calculate the voltage vector V of forward harmonic voltage under synchronous rotary d-q coordinate system _dq:

$\left\{\begin{array}{c}{V}_d=V_c\cos (w_{c}t-\mathrm{\&theta;})\\ V_q=V_c\sin (w_{c}t-\mathrm{\&theta;})\end{array}\right.$

Wherein: voltage vector V _dqcomprise d shaft voltage component V _dwith q shaft voltage component V _q, t is the time.

In described step (2), according to following formula, calculate the current phasor I of motor stator electric current under synchronous rotary d-q coordinate system _dq:

$\left\{\begin{array}{c}{I}_d=\frac{V_c\&CenterDot;r}{r^2+{L_d}^2{w_c}^2}\cos (w_{c}t-\mathrm{\&theta;})+\frac{V_c\&CenterDot;L_d\&CenterDot;w_c}{r^2+{L_d}^2{w_c}^2}\sin (w_{c}t-\mathrm{\&theta;})\\ I_q=\frac{V_c\&CenterDot;r}{r^2+{L_q}^2{w_c}^2}\sin (w_{c}t-\mathrm{\&theta;})-\frac{V_c\&CenterDot;L_q\&CenterDot;w_c}{r^2+{L_q}^2{w_c}^2}\cos (w_{c}t-\mathrm{\&theta;})\end{array}\right.$

Wherein: current phasor I _dqcomprise d shaft current component I _dwith q shaft current component I _q, t is the time.

In described step (3), according to following formula, calculate the current phasor I of stator current under static alpha-beta coordinate system _{α β}:

Wherein: t is the time.

In described step (4), the following formula of basis is from current phasor I _{α β}in extract electric current negative sequence component

$I_{\mathrm{\&alpha;\&beta;}}^{-}=I_{\mathrm{\&alpha;\&beta;}}^{-}\&CenterDot;e^{-2w_{c}t}$

Wherein: t is the time.

In described step (4), the following formula of basis is to electric current negative sequence component

carry out low-pass filtering:

Wherein:

for the electric current negative sequence component after low-pass filtering, t is the time.

In described step (4), according to following formula, be rotated demodulation and obtain electric current negative sequence component

$I_{\mathrm{\&alpha;\&beta;}2}^{-}=I_{\mathrm{\&alpha;\&beta;}1}^{-}\&CenterDot;e^{2w_{c}t}$

Wherein:

for the electric current negative sequence component after low-pass filtering, t is the time.

Rotor initial position method of estimation of the present invention has been improved the estimated angle error that traditional rotation high-frequency signal injection estimation d shaft position produces, the nonlinear characteristic that comprises stator resistance and Inverter Dead-time, wire time time delay, the impact of filtering delay-time on initial position of rotor estimation have equally also been analyzed, therefore can make the initial d shaft position estimation of rotor more accurate, quick and stable; Recycling estimation obtains the polarity that magnetic saturation effect on d axle is distinguished permanent magnet pole, finally obtains rotor initial angle accurately.The inventive method implements simply, and has very strong antijamming capability, can be more accurately, the initial position that records rotor of fast and stable.

Accompanying drawing explanation

Fig. 1 is the steps flow chart schematic diagram of rotor initial position method of estimation of the present invention.

Embodiment

In order more specifically to describe the present invention, below in conjunction with the drawings and the specific embodiments, technical scheme of the present invention is elaborated.

The three-phase permanent magnet synchronous motor of take is example, and this parameter of electric machine is as shown in table 1:

Table 1

Rated power (W)	1500
		Rated speed (rpm)	1000
Nominal torque (N*m)	14.3
		Rated current (A)	3.8
Winding connection	Y type
		Phase resistance R s(　)	2.15
D-axis inductance L d(H)	0.0632
		Quadrature axis inductance L q(H)	0.0919
Permanent magnet equivalence magnetic linkage (Wb)	0.5

As shown in Figure 1, this rotor initial position method of estimation, comprises the steps:

(1) to motor stator winding, injecting amplitude is V _cangular frequency is w _cforward harmonic voltage (applying the magnetic field being rotated counterclockwise to motor); Through static alpha-beta coordinate system transformation, to synchronous rotary d-q coordinate system, obtain the voltage vector V of forward harmonic voltage under synchronous rotary d-q coordinate system _dq;

The voltage vector V of forward harmonic voltage under static alpha-beta coordinate system _{α β}as follows:

$\left\{\begin{array}{c}{V}_{\mathrm{\&alpha;}}=V_c\cos \left(w_{c}t\mathrm{\&theta;}\right)\\ V_{\mathrm{\&beta;}}=V_c\sin \left(w_{c}t\right)\end{array}\right.$

For voltage vector V _{α β}, according to following relational expression, make static alpha-beta coordinate system transformation to synchronous rotary d-q coordinate system:

$\left\{\begin{array}{c}{V}_d=V_{\mathrm{\&alpha;}}\cos \mathrm{\&theta;}-+V_{\mathrm{\&beta;}}\sin \mathrm{\&theta;}\\ V_q=V_{\mathrm{\&alpha;}}(-\sin \mathrm{\&theta;})+V_{\mathrm{\&beta;}}\cos \mathrm{\&theta;}\end{array}\right.$

Obtain the voltage vector V of forward harmonic voltage under synchronous rotary d-q coordinate system _dqas follows:

$\left\{\begin{array}{c}{V}_d=V_c\cos (w_{c}t-\mathrm{\&theta;})\\ V_q=V_c\sin (w_{c}t-\mathrm{\&theta;})\end{array}\right.$

Wherein: θ is the angle of synchronous rotary d-q coordinate system d axle and static alpha-beta coordinate system α axle.

(2) due to voltage vector V _dqthere is following relation with motor stator electric current:

$\left\{\begin{array}{c}{V}_d=V_c\cos (w_{c}t-\mathrm{\&theta;})=r\&CenterDot;I_d+L_d\frac{{\mathrm{dI}}_d}{\mathrm{dt}}\\ V_q=V_c\sin (w_{c}t-\mathrm{\&theta;})=r\&CenterDot;I_q+L_q\frac{{\mathrm{dI}}_q}{\mathrm{dt}}\end{array}\right.$

Wherein: L _dand L _qbe respectively d axle inductive component and the q axle inductive component of motor stator inductance under synchronous rotary d-q coordinate system, r is stator resistance;

Consideration, when motor stable state, solves and obtains the current phasor I of motor stator electric current under synchronous rotary d-q coordinate system above formula _dqas follows:

(3) through synchronous rotary d-q coordinate system transformation to static alpha-beta coordinate system, obtain the current phasor I of stator current under static alpha-beta coordinate system _{α β}:

$\begin{array}{c}{I}_{\mathrm{\&alpha;\&beta;}}=I_{\mathrm{dq}}\&CenterDot;e^{\mathrm{j\&theta;}}\\ =(\frac{I_{\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="HDA0000451935510000011.png"\; state="\{\{state\}\}">r</figure-callout>}1}}{2}+\frac{I_{r3}}{2})e^{j{w}_{c}t}+(\frac{{\mathrm{<figure-callout\; id="1"\; label="I\; r"\; filenames="HDA0000451935510000011.png"\; state="\{\{state\}\}">I</figure-callout>}}_r}{2}-\frac{I_{r3}}{2})e^{j(2\mathrm{\&theta;}-w_{c}t-\frac{\mathrm{\&pi;}}{2})}+(\frac{I_{r2}}{2}\\ -\frac{I_{r4}}{2})e^{j(2\mathrm{\&theta;}-w_{c}t+\frac{\mathrm{\&pi;}}{2})}\end{array}$

Wherein: ${\mathrm{<figure-callout\; id="1"\; label="I\; r"\; filenames="HDA0000451935510000011.png"\; state="\{\{state\}\}">I</figure-callout>}}_r=\frac{V_c\&CenterDot;r}{r^2+{L_d}^2{w_c}^2},I_{r2}=\frac{V_c\&CenterDot;L_d\&CenterDot;w_c}{r^2+{L_d}^2{w_c}^2},I_{r3}=\frac{V_c\&CenterDot;r}{r^2+{L_q}^2{w_c}^2},I_{r4}=\frac{V_c\&CenterDot;L_q\&CenterDot;w_c}{r^2+{L_q}^2{w_c}^2};$

Order: $I_{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="HDA0000451935510000011.png"\; state="\{\{state\}\}">R</figure-callout>}1}=\frac{I_{\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="HDA0000451935510000011.png"\; state="\{\{state\}\}">r</figure-callout>}1}}{2}+\frac{I_{r3}}{2},I_{R2}=\frac{I_{r2}}{2}+\frac{I_{r4}}{2},I_{R3}=\frac{I_{\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="HDA0000451935510000011.png"\; state="\{\{state\}\}">r</figure-callout>}1}}{2}-\frac{I_{r3}}{2},I_{R4}=\frac{I_{r2}}{2}-\frac{I_{r4}}{2};$

?

Wherein:

Stator current vector can be regarded a positive sequence component being rotated counterclockwise and a negative sequence component turning clockwise as, and the positional information of rotor is all positioned on negative sequence component as can be seen here.

(4) the following formula of basis is from current phasor I _{α β}in extract electric current negative sequence component

Then, according to following formula to electric current negative sequence component

carrying out low-pass filtering obtains:

Finally, the electric current negative sequence component after to low-pass filtering according to following formula

be rotated demodulation and obtain electric current negative sequence component

$I_{\mathrm{\&alpha;\&beta;}2}^{-}=I_{\mathrm{\&alpha;\&beta;}1}^{-}\&CenterDot;e^{2w_{c}t}$

(5) according to electric current negative sequence component

by following relational expression arctangent computation, obtain negative phase-sequence phase theta ₁;

Wherein:

can and change along with parameter of electric machine variation, and the impact of dead band on it.

(6) to motor stator winding, injecting amplitude is V _cangular frequency is w _cnegative sense harmonic voltage (applying the magnetic field turning clockwise to motor); The voltage vector V of negative sense harmonic voltage under static alpha-beta coordinate system _{α β}as follows:

$\left\{\begin{array}{c}{V}_{\mathrm{\&alpha;}}=V_c\cos (-w_{c}t)\\ V_{\mathrm{\&beta;}}=V_c\sin (-w_{c}t)\end{array}\right.$

Through static alpha-beta coordinate system transformation, to synchronous rotary d-q coordinate system, obtain the voltage vector V of negative sense harmonic voltage under synchronous rotary d-q coordinate system _dqas follows:

$\left\{\begin{array}{c}{V}_d=V_c\cos (w_{c}t-\mathrm{\&theta;})\\ V_q=V_c\sin (w_{c}t-\mathrm{\&theta;})\end{array}\right.$

(7) due to voltage vector V _dqthere is following relation with motor stator electric current:

$\left\{\begin{array}{c}{V}_d=V_c\cos (w_{c}t-\mathrm{\&theta;})=r\&CenterDot;I_d+L_d\frac{{\mathrm{dI}}_d}{\mathrm{dt}}\\ V_q=V_c\sin (w_{c}t-\mathrm{\&theta;})=r\&CenterDot;I_q+L_q\frac{{\mathrm{dI}}_q}{\mathrm{dt}}\end{array}\right.$

Consideration, when motor stable state, solves and obtains the current phasor I of motor stator electric current under synchronous rotary d-q coordinate system above formula _dqas follows:

$\left\{\begin{array}{c}{I}_d=\frac{V_c\&CenterDot;r}{r^2+{L_d}^2{w_c}^2}\cos (w_{c}t-\mathrm{\&theta;})+\frac{V_c\&CenterDot;L_d\&CenterDot;w_c}{r^2+{L_d}^2{w_c}^2}\sin (w_{c}t-\mathrm{\&theta;})\\ I_q=\frac{V_c\&CenterDot;r}{r^2+{L_q}^2{w_c}^2}\sin (w_{c}t-\mathrm{\&theta;})-\frac{V_c\&CenterDot;L_q\&CenterDot;w_c}{r^2+{L_q}^2{w_c}^2}\cos (w_{c}t-\mathrm{\&theta;})\end{array}\right.$

(8) through synchronous rotary d-q coordinate system transformation to static alpha-beta coordinate system, obtain the current phasor I of stator current under static alpha-beta coordinate system _{α β}:

The positional information of rotor is all positioned in positive sequence component as can be seen here.

(9) the following formula of basis is from current phasor I _{α β}in extract electric current positive sequence component

Then, according to following formula to electric current positive sequence component

carrying out low-pass filtering obtains:

Finally, the electric current positive sequence component after to low-pass filtering according to following formula

be rotated demodulation and obtain electric current positive sequence component

$I_{\mathrm{\&alpha;\&beta;}2}^{+}=I_{\mathrm{\&alpha;\&beta;}1}^{+}{e}^{2w_{c}t}$

(10) according to electric current positive sequence component

by following relational expression arctangent computation, obtain positive sequence phase theta ₂;

(11) known:

at θ ₁, θ ₂in expression formula,

expression formula be consistent, impact

factor be consistent, after twice processing above

value be identical, and within 0 to 90 degree, so θ in theory ₁> θ ₂; So permanent-magnetic synchronous motor rotor initial position can be normalized within the scope of 0 to 180 degree, judge.

According to following relational expression, determine the angle theta of synchronous rotary d-q coordinate system d axle and static alpha-beta coordinate system α axle:

If θ ₁>=θ ₂, θ=0.5*[θ ₁-0.5* (θ ₁-θ ₂)];

If θ ₁≤ θ ₂, θ=0.5*[θ ₁+ π-0.5* (θ ₁+ π-θ ₂)];

(12) according to angle theta, by the magnetic saturation effect on d axle, distinguish the polarity of permanent magnet pole, and then the rotor initial angle of definite motor.

Given positive and negative square-wave voltage in θ direction, the peak value of detection feedback current, if forward is given regularly current peak ratio inverse, to timing greatly, θ is the rotor initial angle of motor; If oppositely give regularly current peak larger to timing than forward, the rotor initial angle of θ and motor differs 180 °.

We verify present embodiment by experiment, and its result is as shown in table 1, and the rotor initial angle of angle theta and motor exists above-mentioned relation really as can be seen from the table, and deviation is very little.

Table 1

The rotor initial angle of setting	Angle theta
		0	0
10	10.1125
		20	20.5500
30	31.2175
		40	41.5000
50	51.0875
		60	60.5325
70	70.0450
		80	80.0500
90	90.0000
		100	99.9500
110	109.9500
		120	119.4675
130	128.9125
		140	138.5000
150	148.7825
		160	159.4450
170	169.8875
		180	-0.0025
190	10.1125
		200	20.5500
210	31.2175
		220	41.5000
230	51.0875
		240	60.5325
250	70.0400
		260	80.0500
270	90.0000
		280	99.9500
290	109.9550
		300	119.4675
310	128.9155
		320	138.5000
330	148.7850
		340	159.4450
350	169.8875
		360	-0.0025

Claims (7)

1. a rotor initial position method of estimation of injecting based on positive and negative sequence harmonic wave, comprises the steps:

(1) to motor stator winding, injecting amplitude is V _cangular frequency is w _cforward harmonic voltage; Through static alpha-beta coordinate system transformation, to synchronous rotary d-q coordinate system, obtain the voltage vector V of forward harmonic voltage under synchronous rotary d-q coordinate system _dq;

(2) according to voltage vector V _dq, calculate and try to achieve the current phasor I of motor stator electric current under synchronous rotary d-q coordinate system _dq;

(3) through synchronous rotary d-q coordinate system transformation to static alpha-beta coordinate system, obtain the current phasor I of stator current under static alpha-beta coordinate system _{α β};

(4) from current phasor I _{α β}in extract electric current negative sequence component

to electric current negative sequence component

carry out successively low-pass filtering and rotate demodulation obtaining electric current negative sequence component

(5) according to electric current negative sequence component

by following relational expression arctangent computation, obtain negative phase-sequence phase theta ₁;

$\begin{array}{cc}{I}_{\mathrm{\&alpha;\&beta;}2}^{-}=I_{\mathrm{cp}}{e}^{j{\mathrm{\&theta;}}_1}& I_{\mathrm{cp}}=\end{array}\sqrt{I_{}{{R2}_{}}^2+{I_{R1}}^2}$

$\begin{array}{cc}{I}_{R1}=\frac{I_{r1}}{2}+\frac{I_{r3}}{2}& I_{R2}=\frac{I_{r2}}{2}+\frac{I_{r2}}{2}+\frac{I_{r4}}{2}\end{array}$

$\begin{array}{cccc}{I}_{r1}=\frac{V_c\&CenterDot;r}{r^2+{L_d}^2{w_c}^2}& I_{r2}=\frac{V_c\&CenterDot;L_d\&CenterDot;w_c}{r^2+{L_d}^2{w_c}^2}& I_{r3}=\frac{V_c\&CenterDot;r}{r^2+{L_q}^2{w_c}^2}& I_{r4}=\frac{V_c\&CenterDot;L_q\&CenterDot;w_c}{r^2+{L_q}^2{w_c}^2}\end{array}$

Wherein: L _dand L _qbe respectively d axle inductive component and the q axle inductive component of motor stator inductance under synchronous rotary d-q coordinate system, r is stator resistance, and j is imaginary unit;

(6) to motor stator winding, inject the negative sense harmonic voltage of identical amplitude same angular frequency, according to step (1) to (5), in like manner calculate the current phasor I of stator current under static alpha-beta coordinate system _{α β}and therefrom extract electric current positive sequence component

and then to electric current positive sequence component

carry out low-pass filtering and rotate demodulation obtaining electric current positive sequence component

according to electric current positive sequence component

pass through relational expression

arctangent computation obtains positive sequence phase theta ₂;

(7), according to following relational expression, determine the angle theta of synchronous rotary d-q coordinate system d axle and static alpha-beta coordinate system α axle:

If θ ₁>=θ ₂, θ=0.5*[θ ₁-0.5* (θ ₁-θ ₂)];

If θ ₁≤ θ ₂, θ=0.5*[θ ₁+ π-0.5* (θ ₁+ π-θ ₂)];

(8) according to angle theta, by the magnetic saturation effect on d axle, distinguish the polarity of permanent magnet pole, and then the rotor initial angle of definite motor.

2. rotor initial position method of estimation according to claim 1, is characterized in that: in described step (1), according to following formula, calculate the voltage vector V of forward harmonic voltage under synchronous rotary d-q coordinate system _dq:

$\left\{\begin{array}{c}{V}_d=V_c\cos (w_{c}t-\mathrm{\&theta;})\\ V_q=V_c\sin (w_{c}t-\mathrm{\&theta;})\end{array}\right.$

Wherein: voltage vector V _dqcomprise d shaft voltage component V _dwith q shaft voltage component V _q, t is the time.

3. rotor initial position method of estimation according to claim 1, is characterized in that: in described step (2), according to following formula, calculate the current phasor I of motor stator electric current under synchronous rotary d-q coordinate system _dq:

$\left\{\begin{array}{c}{I}_d=\frac{V_c\&CenterDot;r}{r^2+{L_d}^2{w_c}^2}\cos (w_{c}t-\mathrm{\&theta;})+\frac{V_c\&CenterDot;L_d\&CenterDot;w_c}{r^2+{L_d}^2{w_c}^2}\sin (w_{c}t-\mathrm{\&theta;})\\ I_q=\frac{V_c\&CenterDot;r}{r^2+{L_q}^2{w_c}^2}\sin (w_{c}t-\mathrm{\&theta;})-\frac{V_c\&CenterDot;L_q\&CenterDot;w_c}{r^2+{L_q}^2{w_c}^2}\cos (w_{c}t-\mathrm{\&theta;})\end{array}\right.$

Wherein: current phasor I _dqcomprise d shaft current component I _dwith q shaft current component I _q, t is the time.

4. rotor initial position method of estimation according to claim 1, is characterized in that: in described step (3), according to following formula, calculate the current phasor I of stator current under static alpha-beta coordinate system _{α β}:

Wherein: t is the time.

5. rotor initial position method of estimation according to claim 1, is characterized in that: in described step (4), the following formula of basis is from current phasor I _{α β}in extract electric current negative sequence component

$I_{\mathrm{\&alpha;\&beta;}}^{-}=I_{\mathrm{\&alpha;\&beta;}}\&CenterDot;e^{-w_{c}t}$

Wherein: t is the time.

6. rotor initial position method of estimation according to claim 1, is characterized in that: in described step (4), the following formula of basis is to electric current negative sequence component

carry out low-pass filtering:

Wherein: for the electric current negative sequence component after low-pass filtering, t is the time.

7. rotor initial position method of estimation according to claim 1, is characterized in that: in described step (4), according to following formula, be rotated demodulation and obtain electric current negative sequence component

$I_{\mathrm{\&alpha;\&beta;}2}^{-}=I_{\mathrm{\&alpha;\&beta;}1}^{-}\&CenterDot;e^{2w_{c}t}$

Wherein: for the electric current negative sequence component after low-pass filtering, t is the time.

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