CN105932912A - Method for detecting initial position of rotor of PMSM (permanent magnet synchronous motor) - Google Patents

Abstract

The invention relates to a new method for detecting the initial position of a rotor of a PMSM (permanent magnet synchronous motor), and the method does not need to extract a negative sequence component of a high-frequency current. The method employs DFT (discrete Fourier transform) to extract the amplitude values of a high-frequency current d and a q-axis component, obtains an error term comprising the position information of the rotor through the relation between the amplitude values of the high-frequency current d and the q-axis component, and then extracts the position angle of the rotor from the error item through employing a PI regulator. The method employs the saturation effect of an iron core of the motor, and judges the N/S polarity of a magnetic pole through the change characteristics of the amplitude of a high-frequency current vector. Compared with a conventional heterodyne method, the method is unrelated with the initial phase of an injection signal, also does not need a large number of filters, is simple in structure, is easy to implement, and provides a new method for the extraction of the position angle of the rotor in no-sensor control based on a high-frequency injection method.

Description

A kind of initial position detection method for permanent magnet synchronous electric motor rotor

Technical field

The present invention relates to a kind of permagnetic synchronous motor (PMSM) method for detecting initial position of rotor, especially built-in type permanent magnetism Synchronous motor (PMSM) method for detecting initial position of rotor.

Background technology

In sensorless control system, if accurate initial position angle of rotor can not be obtained during electric motor starting, the most then lead Cause magnetic linkage and moment not exclusively decouples, deteriorate systematic function, the impact of long starting current time serious, can be caused even to damage Converter and motor.For the PMSM of rotor magnetic steel built-in type, high-frequency signal injection is the rotor-position discrimination method of a kind of practicality. The method first isolates the negative sequence component in high frequency electric response with wave filter, then utilizes heterodyne method therefrom to extract containing turning The error term of subspace positional information obtains rotor position angle by Luenberger observer again.This method is not only extracting negative phase-sequence A large amount of wave filter need to be used during component, cause signal phase to postpone, and the trigonometric function of heterodyne method exterior multiplication and high-frequency carrier signal Relevant, due to sampling, communication, the time delay of signal processing in reality, the superposition phase of carrier signal in the rotor position angle obtained Parallactic angle, causes the estimation difference of positional information.And Luenberger observer is relevant with electromechanics equation, needs rotary inertia etc. Mechanical parameter, cannot obtain accurate parameter in some occasion.

Summary of the invention

It is desirable to provide a kind of permagnetic synchronous motor (PMSM) method for detecting initial position of rotor, with solve existing forever Magnetic-synchro motor (PMSM) method for detecting initial position of rotor needs a large amount of wave filter, calculating is complicated, cause rotor position information The problem of estimation difference.The concrete scheme of the present invention is as follows:

A kind of permagnetic synchronous motor (PMSM) method for detecting initial position of rotor, comprises the following steps:

Step 1: at estimation frame'sAxle andAxle is injected separately into high-frequency rotating voltageWithContained The high frequency electric response of rotor position informationWith

Step 2: described high frequency electric is responded by discrete Fourier transform (DFT)WithIt is demodulated, extracts described The amplitude of high frequency electric response componentWithCalculate described squared magnitude poor, obtain the error term of described rotor-position

Step 3: utilize pi regulatorBy the regulation of described error term to zero to extract rotor position angle

Step 4: the phase place detecting the described amplitude of described high frequency electric response corresponding when reaching maximum can get rotor N The position θ of pole_N, by θ_NWith the rotor position angle extractedMake comparisons, if θ_NWithDifference less than 90 °, then described in extract Rotor position angleFor actual rotor position θ, if θ_NWithDiffer by more than 90 °, then described in the rotor position angle that extractsAdd 180 ° is actual rotor position θ.

Use technique scheme, the invention have the advantages that:

The invention provides a kind of permagnetic synchronous motor (PMSM) method for detecting initial position of rotor, outside the method is with tradition Difference method is compared, not only unrelated with Injection Signal initial phase, and need not use a large amount of wave filter, its simple in construction, it is easy to number Word realizes, and the extraction for sensorless strategy rotor position angle based on high-frequency signal injection provides a kind of new method.We Method is particularly suited for the detection of built-in type permagnetic synchronous motor (PMSM) initial position of rotor.

Accompanying drawing explanation

Fig. 1 shows that the rotor position angle that DFT demodulates extracts schematic diagram；

Fig. 2 shows d axle stator magnetic linkage and current relationship；

Fig. 3 shows the initial position angle of rotor Cleaning Principle figure of pole polarity identification；

Fig. 4 shows high frequency electric DFT magnitude extraction waveform；

Fig. 5 (a) shows the error term waveform containing positional information；

Fig. 5 (b) shows angle waveform；

Fig. 6 shows hardware experiment platform；

Fig. 7 shows high frequency electric vector locus under different initial position；

Fig. 8 (a) shows actual value and the detected value of initial position detection experimental result；And

Fig. 8 (b) shows the detection error of initial position detection experimental result.

Detailed description of the invention

For further illustrating each embodiment, the present invention is provided with accompanying drawing.These accompanying drawings are the invention discloses content one Point, it is mainly in order to illustrate embodiment, and the associated description of description can be coordinated to explain the operation principles of embodiment.Coordinate ginseng Examining these contents, those of ordinary skill in the art will be understood that other possible embodiments and advantages of the present invention.

In conjunction with the drawings and specific embodiments, the present invention is further described.Fig. 1 is that the rotor position angle of DFT demodulation carries Take schematic diagram.For the DFT demodulation principle of analysis of high frequency current signal, on the basis of dq coordinate system, introduce a new coordinate SystemIts according to(Estimated value for rotor position angle θ) rotate, then the transformation matrix of this coordinate system can represent For:

$T_{\hat{d}\hat{q}\→dq}=\left[\begin{array}{cc}cos\mathrm{\Δ}\mathrm{\θ}& sin\mathrm{\Δ}\mathrm{\θ}\\ -sin\mathrm{\Δ}\mathrm{\θ}& cos\mathrm{\Δ}\mathrm{\θ}\end{array}\right]---\left(1\right)$

It is far longer than rotor velocity, therefore permanent magnet magnetic linkage Ψ owing to injecting the angular velocity of high frequency voltage pumping signal_f Negligible compared to the magnetic linkage that stator current produces, the flux linkage equations under dq coordinate system is transformed toUnder coordinate system, have:

$\left[\begin{array}{c}{\mathrm{\Ψ}}_{\hat{d}}\\ {\mathrm{\Ψ}}_{\hat{q}}\end{array}\right]={T_{\hat{d}\hat{q}\→dq}}^{-1}\left[\begin{array}{cc}{L}_d& 0\\ 0& L_q\end{array}\right]T_{\hat{d}\hat{q}\→dq}\left[\begin{array}{c}{i}_{\hat{d}}\\ i_{\hat{q}}\end{array}\right]---\left(2\right)$

Being deformed by above formula, obtaining current-responsive expression formula is:

$\left[\begin{array}{c}{i}_{\hat{d}}\\ i_{\hat{q}}\end{array}\right]=\frac{1}{L_{\Σ}^2-L_{\mathrm{\Δ}}^2}\left[\begin{array}{cc}{L}_{\Σ}+L_{\mathrm{\Δ}}\cos \left(2\mathrm{\Δ}\mathrm{\θ}\right)& L_{\mathrm{\Δ}}\sin \left(2\mathrm{\Δ}\mathrm{\θ}\right)\\ L_{\mathrm{\Δ}}\sin \left(2\mathrm{\Δ}\mathrm{\θ}\right)& L_{\Σ}-L_{\mathrm{\Δ}}\cos \left(2\mathrm{\Δ}\mathrm{\θ}\right)\end{array}\right]\left[\begin{array}{c}{\mathrm{\Ψ}}_{\hat{d}}\\ {\mathrm{\Ψ}}_{\hat{q}}\end{array}\right]---\left(3\right)$

In formula: L_Σ=(L_d+L_q)/2, L_Δ=(L_q-L_d)/2。

The rotation high frequency voltage injecting following form encourages:

$\left\{\begin{array}{c}{i}_{\hat{d}}=-\left(I_{i0}+I_{i1}\cos \left(2\mathrm{\Δ}\mathrm{\θ}\right)\right){\mathrm{cos\ω}}_{i}t+I_{i1}\sin \left(2\mathrm{\Δ}\mathrm{\θ}\right){\mathrm{sin\ω}}_{i}t\\ i_{\hat{q}}=-I_{i1}\sin \left(2\mathrm{\Δ}\mathrm{\θ}\right){\mathrm{cos\ω}}_{i}t+\left(I_{i0}-I_{i1}\cos \left(2\mathrm{\Δ}\mathrm{\θ}\right)\right){\mathrm{sin\ω}}_{i}t\end{array}\right.\left[\begin{array}{c}{u}_{i\hat{d}}\\ u_{i\hat{q}}\end{array}\right]=\left|u_i\right|\left[\begin{array}{c}{\mathrm{sin\ω}}_{i}t\\ {\mathrm{cos\ω}}_{i}t\end{array}\right]---\left(4\right)$

In formula: u_iFor Injection Signal amplitude, ω_iFor Injection Signal frequency.According to magnetic linkage-voltage equationCan :

$\left[\begin{array}{c}{\mathrm{\Ψ}}_{\hat{d}}\\ {\mathrm{\Ψ}}_{\hat{q}}\end{array}\right]=\frac{u_i}{{\mathrm{\ω}}_i}\left[\begin{array}{c}-{\mathrm{cos\ω}}_{i}t\\ {\mathrm{sin\ω}}_{i}t\end{array}\right]---\left(5\right)$

Formula (5) is substituted in formula (3) and high frequency electric response can be obtained:

$\left\{\begin{array}{c}{i}_{\hat{d}}=-\left(I_{i0}+I_{i1}\cos \left(2\mathrm{\Δ}\mathrm{\θ}\right)\right){\mathrm{cos\ω}}_{i}t+I_{i1}\sin \left(2\mathrm{\Δ}\mathrm{\θ}\right){\mathrm{sin\ω}}_{i}t\\ i_{\hat{q}}=-I_{i1}\sin \left(2\mathrm{\Δ}\mathrm{\θ}\right){\mathrm{cos\ω}}_{i}t+\left(I_{i0}-I_{i1}\cos \left(2\mathrm{\Δ}\mathrm{\θ}\right)\right){\mathrm{sin\ω}}_{i}t\end{array}\right.---\left(6\right)$

In formula:

The amplitude expression that can obtain current component according to formula (6) is:

$\left\{\begin{array}{c}|i_{\hat{d}}{|}^2=I_{i0}^2+I_{i1}^2+2I_{i1}{I}_{i0}\cos \left(2\mathrm{\Δ}\mathrm{\θ}\right)\\ |i_{\hat{q}}{|}^2=I_{i0}^2+I_{i1}^2-2I_{i1}{I}_{i0}\cos \left(2\mathrm{\Δ}\mathrm{\θ}\right)\end{array}\right.---\left(7\right)$

Then:

$|i_{\hat{d}}{|}^2-|i_{\hat{q}}{|}^2=4I_{i1}{I}_{i0}cos\left(2\mathrm{\Δ}\mathrm{\θ}\right)---\left(8\right)$

By formula (8) it can be seen that d, q axle component amplitude relational expression of high frequency electric response signal contains rotor-position Information, and the amplitude of electric current can be obtained by Fourier transformation.It is analogous to heterodyne method, to extract rotor position from error term Angle setting, then error term needs abbreviation to be sin (2 θ) form.Therefore, can be byChange intoCoordinate system, its transformation matrix of coordinates For:

Then, existIn coordinate system

$\begin{array}{c}|i_{\hat{d}}{|}^2-|i_{\hat{q}}{|}^2=4I_{i1}{I}_{i0}\cos \left(2{\mathrm{\Δ\θ}}^{\′}\right)\\ =4I_{i1}{I}_{i0}\cos \left(2\left(\mathrm{\Δ}\mathrm{\θ}-\frac{\mathrm{\π}}{4}\right)\right)=4I_{i1}{I}_{i0}\sin \left(2\mathrm{\Δ}\mathrm{\θ}\right)\end{array}---\left(10\right)$

Therefore, by above-mentioned analysis, utilize pi regulator the error term closed loop shown in formula (10) to be regulated after 0, The angle information obtained is rotor position angle

Illustrate how to judge rotor magnetic pole polarity with reference to Fig. 2 and Fig. 3, so that it is determined that actual rotor position.Fig. 2 shows d Axle stator magnetic linkage and the relation of electric current.From in figure, the degree of saturation of stator core is relevant with d shaft current size, when d axle electricity When the flux component of miscarriage life is identical with rotor flux direction, degree of saturation increases；When d shaft current produce flux component with turn When sub-flow direction is contrary, degree of saturation weakens.Due to the existence of this saturation effect, when injecting high-frequency rotating voltage drive Time, the high frequency electric response of generation can be modulated, and when high frequency electric response vector signal forwards rotor N pole to, amplitude reaches Maximum, when forwarding S pole to, degree of saturation weakens on the contrary, and inductance increases, and current amplitude reduces.

According to above-mentioned principle, the phase place corresponding when reaching maximum of the amplitude of detection high frequency electric response signal can be turned The position θ of sub-N pole_N, this angle and rotor physical location angle error are relatively big, but can be used to judge pole polarity.By θ_NWith front Literary composition demodulates the rotor position angle extracted based on DFT high frequency electricCompare, if the two difference is less than 90 °, then extract The rotor position angle gone outIt is actual rotor angular position theta；If the two differs by more than 90 °, then the rotor position angle extractedFor Position, S pole, adds that 180 ° are actual rotor angular position theta.Add the DFT method initial position angle of rotor detection of pole polarity identification Principle is as shown in Figure 3.Therefore, the built-in type PMSM method for detecting initial position of rotor of the present invention comprises the following steps:

Step 1: at estimation frame'sAxle andAxle is injected separately into high-frequency rotating voltageWithContained The high frequency electric response of rotor position informationWith

Step 2: described high frequency electric is responded by discrete Fourier transform (DFT)WithIt is demodulated, extracts described The amplitude of high frequency electric response componentWithCalculate described squared magnitude poor, obtain the error term of described rotor-position

Step 3: utilize pi regulator by described error termRegulate to zero to extract rotor position angle

Step 4: the phase place detecting the described amplitude of described high frequency electric response corresponding when reaching maximum can get rotor N The position θ of pole_N, by θ_NWith the described rotor position angle extractedMake comparisons, if θ_NWithDifference is less than 90 °, the most described extraction The rotor position angle gone outFor actual rotor position θ, if θ_NWithDiffer by more than 90 °, then described in the rotor position angle that extracts It is actual rotor position θ plus 180 °.

The present invention is by emulation and verifies its effectiveness and accuracy.At Matlab/Simulink software platform On emulate, it should be noted that saturation effect ignored by electrical machine element model, thus cannot carry out according to core sataration characteristic The emulation of pole polarity identification.In software environment, just the most first verify rotor-position angle extraction method based on DFT demodulation Really at dSPACE hardware, property, then verifies that in line platform initial position angle of rotor based on the method detects.Emulation motor ginseng Number is consistent with experiment motor: rated power 2kW, rated current 8A, and the every phase winding resistance of armature is 7 Ω, d-axis inductance 2.5mH, Quadrature axis inductance 8.5mH, number of pole-pairs is 3.Inject high frequency voltage frequency 1250Hz, amplitude 5V.

Fig. 4 show the high frequency electric d axle component and amplitude waveform thereof sensed after injecting high-frequency rotating excitation.Can by figure Know, designed high-frequency current signal DFT demodulation method, it is possible to by the high frequency electric magnitude extraction of injected frequency out, Jin Erwei Realize from magnitude relation, extract rotor position error item to lay the foundation

Fig. 5 show rotor position angle based on DFT high frequency electric demodulation method and extracts waveform, and wherein figure (a) show root The error term 4I obtained according to d, q shaft current magnitude relation_i1I_i0Sin (2 Δ θ) waveform, figure (b) show utilize pi regulator from The angle extracted in error term and actual measurement angle waveform.From in figure, the method can extract rotor position angle and essence Degree is high, response is fast.

For the above-mentioned effectiveness of method for detecting initial position of rotor based on the demodulation of DFT high frequency electric of checking, built as Built-in type PMSM Variable-frequency Regulating Speed Experimental Platform shown in Fig. 6.Main by built-in type permagnetic synchronous motor, universal frequency converter DR50A And dSPACE real-time emulation system composition.DSPACE onboard processor DS1104 is automatically performed the compiling of code and then produces PWM Pulse driven switch device works.Rotor physical location, injected frequency 1250Hz, the rotation of amplitude 10V is recorded by encoder High frequency voltage, carries out DFT method demodulation and then extracts rotor-position high frequency electric.

The tracing waveform of high frequency electric vector when Fig. 7 show different initial position, it can be seen that high frequency electric Track be one oval, and the major axis of ellipse is rotor position angle with horizontal angle.

Fig. 8 show experimental result based on DFT high frequency electric demodulation initial position detection.Rotor physical location is used in advance Encoder records, and then decouples high frequency electric under without basic waves exciting and then extracts rotor-position, to testing result Error carries out curve fitting, and as shown in figure (b), testing result and actual result are in 5 ° of electrical angles, and precision is higher, it is possible to meet Vector controlled requirement.

Although specifically showing and describe the present invention in conjunction with preferred embodiment, but those skilled in the art should be bright In vain, in the spirit and scope of the present invention limited without departing from appended claims, in the form and details can be right The present invention makes a variety of changes, and is protection scope of the present invention.

Claims (1)

1. an initial position detection method for permanent magnet synchronous electric motor rotor, it is characterised in that comprise the following steps:

Step 1: at estimation frame'sAxle andAxle is injected separately into high-frequency rotating voltageWithObtain containing rotor The high frequency electric response of positional informationWith

Step 2: described high frequency electric is responded by discrete Fourier transform (DFT)WithIt is demodulated, extracts described high frequency The amplitude of current-responsive componentWithCalculate described squared magnitude poor, obtain the error term of described rotor-position

Step 3: utilize pi regulator by described error termClosed loop regulates to zero to extract rotor position angle

Step 4: the phase place detecting the described amplitude of described high frequency electric response corresponding when reaching maximum can get rotor N pole Position θ_N, by θ_NWith the rotor position angle extractedMake comparisons, if θ_NWithDifference less than 90 °, then described in the rotor that extracts Position angleFor actual rotor position θ, if θ_NWithDiffer by more than 90 °, then described in the rotor position angle that extractsPlus 180 ° For actual rotor position θ.