阅读说明：本技术 一种提高永磁同步电机风机逆风起动能力的方法 (Method for improving upwind starting capability of permanent magnet synchronous motor fan ) 是由 童怀 于 2021-08-23 设计创作，主要内容包括：本发明公开了一种提高永磁同步电机风机逆风起动能力的方法,在风机强逆风起动开环运行阶段转子出现抖动使转子位置角估算值大幅波动,可能导致从位置开环切入位置闭环时转子位置估算的算法不收敛,最终导致起动失败；由于强逆风起动形成开环旋转磁场的三相正弦波电流幅值大、电机磁路进入饱和状态使电感参数减小并导致位置估算的收敛域减小,本发明根据电感参数减小的特点优化强逆风起动时的位置角估算参数,同时通过前馈补偿使转子位置角估算值波动减小,并选择在转子估算位置角波动值小于预设值的时刻切入位置闭环,从而避免从位置开环切入位置闭环时转子位置角估算可能不收敛的问题,提高系统的逆风起动能力。(The invention discloses a method for improving the upwind starting capability of a permanent magnet synchronous motor fan, wherein the rotor shakes in the strong upwind starting open-loop operation stage of the fan to enable the estimation value of the position angle of the rotor to fluctuate greatly, which may cause the non-convergence of the algorithm of the estimation of the position of the rotor when the position is switched from open loop to closed loop, and finally cause the starting failure; the invention optimizes the position angle estimation parameters when the strong upwind starts according to the characteristic of reduced inductance parameters, simultaneously reduces the fluctuation of the estimated value of the rotor position angle through feedforward compensation, and selects to cut into the position closed loop when the fluctuation value of the estimated position angle of the rotor is smaller than a preset value, thereby avoiding the problem that the estimation of the rotor position angle is not converged when the position closed loop is cut into the position closed loop from the position open loop, and improving the upwind starting capability of the system.)

1. A method for improving upwind starting capability of a permanent magnet synchronous motor fan is characterized by comprising the following steps:

measuring inductance parameters of the permanent magnet synchronous motor corresponding to phase current peak values of different windings to determine the influence of the saturation of the motor on the inductance parameters; before starting up against the wind, the motor is subjected to brake control, and the intensity of the against wind is judged according to the brake current amplitude; setting a phase current peak value and an open-loop operation frequency of a motor winding according to the upwind intensity, and generating three-phase sine wave current in the motor winding to form an active rotating magnetic field so that the permanent magnet synchronous motor works in an open-loop operation mode;

determining the saturation degree of a motor magnetic circuit according to the phase current peak value of the open-loop operation winding, and calculating inductance parameters when starting against the wind; establishing a stator voltage equation under an actual rotating coordinate system and a stator voltage equation under an expected rotating coordinate system when an included angle exists between the stator voltage equation and the actual rotating coordinate system, and calculating a current difference value between current under the expected rotating coordinate system and current under the actual rotating coordinate system; calculating the motor back electromotive force according to the current difference, and estimating the motor rotor position angle according to the calculated motor back electromotive force;

determining a convergence domain of a back electromotive force estimation coefficient and a rotor position angle compensation coefficient according to inductance parameters during upwind starting, and determining values of the back electromotive force estimation coefficient and the rotor position angle compensation coefficient; calculating the position angle of the active rotating magnetic field in an open-loop operation mode, and obtaining an estimated difference value of the estimated position angle of the motor rotor and the position angle; according to the change rule of the rotor position angle estimation error fluctuation, the fluctuation of the rotor position angle estimation error is reduced by an active compensation method; selecting a switching-in position closed-loop operation mode at the moment when the fluctuation value of the estimated position angle of the rotor is smaller than a preset value; and under the position closed-loop operation mode, the speed-regulating operation of the permanent magnet synchronous motor controlled by the position sensor is carried out.

2. The method for improving the upwind starting capability of the permanent magnet synchronous motor fan according to claim 1, wherein the step of determining the saturation degree of a magnetic circuit of the motor according to the phase current peak value of the open-loop running winding and calculating the inductance parameter during upwind starting comprises the following steps:

forming a data table of inductance parameters by measuring the inductance parameters of the permanent magnet synchronous motor corresponding to the phase current peak values of different windings;

firstly determining the phase current peak value I of the motor winding by using the data table_p0At which two currents i₁And i₂Then, the inductance is calculated by interpolation.

3. The method for improving the upwind starting capability of a fan of a permanent magnet synchronous motor according to claim 1, wherein the determining the convergence domain of the back electromotive force estimation coefficient and the rotor position angle compensation coefficient according to the inductance parameter at the upwind starting time, and the determining the values of the back electromotive force estimation coefficient and the rotor position angle compensation coefficient comprises:

back emf estimation coefficientAnd rotor position angle compensation coefficientThe calculation formula of the convergence domain of (a) is:

wherein the content of the first and second substances,inductance parameters of a d axis and a q axis of the upwind starting motor are respectively, e is the counter electromotive force of the motor, and T is the sampling time of discrete points;

andthe calculation formula of the value is as follows:

the coefficient zeta is 0.3-0.5, the value of the coefficient zeta is the same as that of the working condition without the headwind, and the coefficient zeta is 0.6-0.8.

4. The method for improving the upwind starting capability of the fan of the permanent magnet synchronous motor according to claim 1, wherein the method for reducing the fluctuation of the estimation error of the rotor position angle by an active compensation method according to the variation rule of the fluctuation of the estimation error of the rotor position angle comprises the following steps:

calculating an estimation error theta_errMaximum value of fluctuation theta_err-MAX＝MAX(θ_err) Minimum value θ_err-MIN＝MIN(θ_err) And compensating for amplitude theta_COMP＝(θ_err-MAX-θ_err-MIN)/2；

Actively compensating for rotor position estimation angle fluctuations as follows:

in the above formula, the first and second carbon atoms are,estimating an angle, θ, for the actively compensated rotor position_MFor estimating the electric machineRotor position angle, N is the harmonic order of the active compensation, f₀For open-loop operating frequency, t is a time parameter, θ_COMP-SFTIs an actively compensated phase shift angle.

5. The method for improving the upwind starting capability of a PMSM fan according to claim 1, wherein said selecting a cut-in position closed-loop operating mode at a time when the rotor estimated position angle fluctuation value is less than a preset value comprises:

calculating the rotor position angle estimation difference after active compensationAnd low-pass filtering the estimated difference;

according to the formulaJudging whether the fluctuation value of the estimated position angle of the rotor is smaller than a preset value, wherein theta_ξEstimating a preset value, theta, for controlling the rotor, at which the position angle fluctuation is as small as possible_ξThe value range is (1.5-3.0); theta_{err_LPF}A low-pass filtered value representing the position angle estimate difference;

the selection is made to switch from the position open-loop operating mode to the position closed-loop operating mode at a time when the estimated rotor position angle fluctuation value is less than a preset value.

6. A position sensorless permanent magnet synchronous motor fan is characterized in that a controller of the fan is loaded with a computer program; computer program implementing the steps of the method of upwind startability according to one of claims 1 to 5 when being executed.

7. A computer-readable storage medium, in which a computer program is stored which, when being executed, carries out the method steps of the upwind method according to any one of claims 1 to 5.

Technical Field

The invention relates to the technical field of motor control, in particular to a method for improving starting capability of a permanent magnet synchronous motor fan without a position sensor.

Background

The permanent magnet synchronous motor fan has the advantages of simple structure, high efficiency and wide speed regulation range, and is widely applied to the fields of indoor air purification, mine tunnel ventilation and the like at present. The permanent magnet synchronous motor position sensorless control technology can reduce hardware cost and improve system reliability, and has become a very important research direction in the field of fan control in recent years. Because the rotor position angle of the motor is difficult to accurately estimate when the permanent magnet synchronous motor is static or at low speed, the estimation error of the rotor position has great influence on the starting capability of the permanent magnet synchronous motor, particularly, a permanent magnet synchronous motor fan system is started under the condition of headwind, the starting load working condition is complex and changeable, the difficulty of estimating the rotor position is further increased, and the research for improving the headwind starting capability is a hotspot in the fan control scheme of the permanent magnet synchronous motor without the position sensor.

In order to solve the problem of estimation of the rotor position angle of the motor when the motor is static, the high-frequency injection method based on the initial position detection method of the rotor of the permanent magnet synchronous motor is provided by Jia Honghing et al in Chinese Motor engineering journal (VOL.27, NO.15), the high-frequency injection method can accurately detect the rotor position angle under the static condition, so that the starting capability of the motor is improved, but the algorithm execution time of the method is long, the implementation process is complex, high-frequency electromagnetic noise exists in the starting process, and the fan user is generally hard to accept.

The control method for controlling upwind starting of a permanent magnet synchronous motor fan without a position sensor is respectively researched by Hospital on daily electric appliances (2014, NO.7) and by Hezattlebin and the like on daily electric appliances (2019, NO.6), but the two methods only research the problems of upwind state identification and upwind rotating speed estimation, and do not research the problems that in the strong upwind starting open-loop operation stage, the estimation value of the rotor position angle fluctuates greatly due to the reasons that the amplitude of three-phase sine wave current forming an active rotating magnetic field is large, the rotor is likely to shake during the open-loop operation of the motor and the like, and the estimation algorithm of the rotor position angle is not converged when the rotor is switched into a position closed loop from the position open loop, and finally the starting failure is caused.

Patent (ZL201910660918.1) proposes a method for improving the starting performance of a permanent magnet synchronous motor without a position sensor, but the method is only proposed for the working condition without headwind, and does not consider the problem that the estimated value of the rotor position angle greatly fluctuates under the headwind working condition and the problem that the magnetic circuit of a strong headwind starting motor is saturated.

Disclosure of Invention

The invention aims to provide a method for improving the upwind starting capability of a permanent magnet synchronous motor fan, which is used for overcoming the problems that in the prior art, the rotor shakes in the strong upwind starting open-loop operation stage of the fan to enable the estimated value of the position angle of the rotor to fluctuate greatly, the algorithm for estimating the position of the rotor is not converged when the position is switched from an open loop to a closed loop, and finally the starting failure is caused.

In order to realize the task, the invention adopts the following technical scheme:

a method for improving the upwind starting capability of a permanent magnet synchronous motor fan comprises the following steps:

measuring inductance parameters of the permanent magnet synchronous motor corresponding to phase current peak values of different windings to determine the influence of the saturation of the motor on the inductance parameters; before starting up against the wind, the motor is subjected to brake control, and the intensity of the against wind is judged according to the brake current amplitude; setting a phase current peak value and an open-loop operation frequency of a motor winding according to the upwind intensity, and generating three-phase sine wave current in the motor winding to form an active rotating magnetic field so that the permanent magnet synchronous motor works in an open-loop operation mode;

determining the saturation degree of a motor magnetic circuit according to the phase current peak value of the open-loop operation winding, and calculating inductance parameters when starting against the wind; establishing a stator voltage equation under an actual rotating coordinate system and a stator voltage equation under an expected rotating coordinate system when an included angle exists between the stator voltage equation and the actual rotating coordinate system, and calculating a current difference value between current under the expected rotating coordinate system and current under the actual rotating coordinate system; calculating the motor back electromotive force according to the current difference, and estimating the motor rotor position angle according to the calculated motor back electromotive force;

determining a convergence domain of a back electromotive force estimation coefficient and a rotor position angle compensation coefficient according to inductance parameters during upwind starting, and determining values of the back electromotive force estimation coefficient and the rotor position angle compensation coefficient; calculating the position angle of the active rotating magnetic field in an open-loop operation mode, and obtaining an estimated difference value of the estimated position angle of the motor rotor and the position angle; according to the change rule of the rotor position angle estimation error fluctuation, the fluctuation of the rotor position angle estimation error is reduced by an active compensation method; selecting a switching-in position closed-loop operation mode at the moment when the fluctuation value of the estimated position angle of the rotor is smaller than a preset value; and under the position closed-loop operation mode, the speed-regulating operation of the permanent magnet synchronous motor controlled by the position sensor is carried out.

Further, the determining the saturation degree of the magnetic circuit of the motor according to the phase current peak value of the open-loop operation winding, and calculating the inductance parameter when starting against the wind includes:

forming a data table of inductance parameters by measuring the inductance parameters of the permanent magnet synchronous motor corresponding to the phase current peak values of different windings;

firstly determining the phase current peak value I of the motor winding by using the data table_p0At which two currents i₁And i₂Then, the inductance is calculated by interpolation.

Further, the determining a convergence domain of the back emf estimation coefficient and the rotor position angle compensation coefficient according to the inductance parameter at the upwind start and determining the values of the back emf estimation coefficient and the rotor position angle compensation coefficient includes:

back emf estimation coefficientAnd rotor position angle compensation coefficientThe calculation formula of the convergence domain of (a) is:

wherein the content of the first and second substances,inductance parameter of d axis and q axis of upwind starting motor respectivelyThe number e is the counter electromotive force of the motor, and T is the sampling time of discrete points;

andthe calculation formula of the value is as follows:

the coefficient zeta is 0.3-0.5, the value of the coefficient zeta is the same as that of the working condition without the headwind, and the coefficient zeta is 0.6-0.8.

Further, the method for reducing the fluctuation of the rotor position angle estimation error through an active compensation method according to the change rule of the fluctuation of the rotor position angle estimation error comprises the following steps:

calculating an estimation error theta_errMaximum value of fluctuation theta_err-MAX＝MAX(θ_err) Minimum value θ_err-MIN＝MIN(θ_err) And compensating for amplitude theta_COMP＝(θ_err-MAX-θ_err-MIN)/2；

Actively compensating for rotor position estimation angle fluctuations as follows:

in the above formula, the first and second carbon atoms are,estimating an angle, θ, for the actively compensated rotor position_MFor estimating the rotor position angle of the machine, N is the number of actively compensated harmonics, f₀For open-loop operating frequency, t is a time parameter, θ_COMP-SFT is the phase shift angle of the active compensation.

Further, the selecting the cut-in position closed-loop operation mode at the moment when the rotor estimated position angle fluctuation value is smaller than the preset value includes:

calculating the rotor position angle estimation difference after active compensationAnd low-pass filtering the estimated difference;

according to the formulaJudging whether the fluctuation value of the estimated position angle of the rotor is smaller than a preset value, wherein theta_ξEstimating a preset value, theta, for controlling the rotor, at which the position angle fluctuation is as small as possible_ξThe value range is (1.5-3.0%); theta_{err_LPF}A low-pass filtered value representing the position angle estimate difference;

the selection is made to switch from the position open-loop operating mode to the position closed-loop operating mode at a time when the estimated rotor position angle fluctuation value is less than a preset value.

A position sensorless permanent magnet synchronous motor fan is characterized in that a controller of the fan is loaded with a computer program; the computer program, when executed, performs the method steps of the upwind starting capability.

A computer-readable storage medium, in which a computer program is stored which, when being executed, carries out the steps of the method of upwind starting capability.

Compared with the prior art, the invention has the following technical characteristics:

the invention optimizes the position angle estimation parameters when the strong upwind starts according to the characteristic of reduced inductance parameters, simultaneously reduces the fluctuation of the estimated value of the rotor position angle through feedforward compensation, and selects to cut into the position closed loop when the fluctuation value of the estimated position angle of the rotor is smaller than a preset value, thereby avoiding the problem that the estimation of the rotor position angle is not converged when the position closed loop is cut into the position closed loop from the position open loop, and improving the upwind starting capability of the system.

Drawings

FIG. 1 is a block diagram of a position sensorless vector control system for a permanent magnet synchronous motor;

FIG. 2 is a γ δ hypothetical coordinate system and a dq coordinate system;

FIG. 3 estimation of position angle θ using front rotor in accordance with aspects of the present invention_MThe fluctuation is large;

FIG. 4 shows the scheme of the invention for obtaining the estimated rotor position angleThe fluctuation is reduced;

FIG. 5 shows experimental waveforms for successful strong upwind start of the method of the present invention.

Detailed Description

The invention provides a method for solving the problem that in the strong upwind starting open-loop operation stage of a fan, the estimation value of the rotor position angle greatly fluctuates due to the reasons that the amplitude of three-phase sine wave current forming an active rotating magnetic field is large, the rotor in the open-loop operation of a motor is likely to shake and the like, so that the algorithm for estimating the rotor position is likely not to be converged when the position is switched from the open loop to the closed loop, and finally the starting failure is caused. As shown in fig. 1 to 5, the method for improving the upwind starting capability of the permanent magnet synchronous motor fan provided by the invention comprises the following steps:

step 1, measuring inductance parameters L of phase current peak values of different windings corresponding to permanent magnet synchronous motor_d(i)、L_q(i)。

The method aims to determine the influence of the saturation of a motor magnetic circuit on inductance parameters, a star connection method is adopted for a motor winding, direct current is conducted in the winding, the direct current of one phase is i, the direct current of the other two phases is-0.5 i, the direct current i is gradually increased from small to small, and the inductance parameters L of the d axis and the q axis of the motor under different current values i and dq coordinate systems are measured_d(i)、L_q(i) And forming a data table of inductance parameters.

And 2, performing brake control on the motor before starting in headwind, and judging that the headwind strength is strong headwind, medium headwind or weak headwind according to the brake current amplitude.

Step 3, setting a phase current peak value I of the motor winding according to the upwind intensity_p0And open loop operationFrequency f₀Three-phase sine wave current is generated in a motor winding so as to form an active rotating magnetic field, and at the moment, the permanent magnet synchronous motor works in an open-loop synchronous operation mode.

Wherein, the three-phase sine wave current generated in the permanent magnet synchronous motor winding is expressed as:

in the above formula, I_U,I_V,I_WAre respectively three-phase sine wave current of motor winding I_p0And t is a time parameter for the set phase current peak value of the motor winding.

Step 4, determining the saturation degree of the motor magnetic circuit according to the phase current peak value of the open-loop operation winding, and calculating the upwind starting inductance parameter

In the step, I is determined by using the data table of inductance parameters obtained in the previous step_p0Between which two currents i₁And i₂Then, the inductance is calculated by an interpolation method:

step 5, establishing a stator voltage equation under an actual rotating coordinate system (dq coordinate system), wherein in the scheme, the stator voltage equation under the dq coordinate system is expressed as:

in the above formula, u_d、u_qD-axis voltage and q-axis voltage of the stator winding respectively; i.e. i_d、i_qD-axis current and q-axis current of the stator winding respectively; r_sIs a stator resistor; l is_d、L_qD-axis and q-axis inductors respectively; e is the back electromotive force of the motor;omega is the rotation angular velocity of dq coordinate system; p is a differential operator, and p is d/dt;

establishing a stator voltage equation under an expected rotation coordinate system when an included angle delta theta exists between the expected rotation coordinate system and an actual rotation coordinate system, wherein in the scheme, the expected rotation coordinate system is a gamma delta estimation coordinate system, and the voltage equation of the stator under the coordinate system is as follows:

in the above formula, u_γ、u_δEstimating the stator voltage components i of the gamma and delta axes in the coordinate system for gamma and delta, respectively_γ、i_δStator current components of gamma and delta axes, omega, respectively_MEstimating the angular velocity of rotation of the coordinate system for γ δ, p being a differential operator; delta theta is an included angle between the gamma delta estimation coordinate system and the dq coordinate system, namely a position angle estimation error;

calculating the difference value of the current in the expected rotating coordinate system and the current in the actual rotating coordinate system:

in the above formula, T is the sampling time of discrete points, i_γ(n+1)、i_δ(n +1) is the actual current of the motor at the sampling point (n +1), i_Mγ(n+1)、i_Mδ(n +1) is the estimated current at sample point (n +1), i_γ(n+1)、i_δ(n +1) is the estimated current error at sample point (n +1), e_MThe back electromotive force of the motor in the expected rotating coordinate system is obtained, and delta e is the error between the back electromotive force of the expected rotating coordinate system and the back electromotive force of the dq coordinate system;

step 6, calculating the back electromotive force of the motor according to the current difference

e_M(n+1)＝e_M(n)-K_δΔi_δ(n+1) (6)

In the above formula, e_M(n+1)、e_M(n) is the back electromotive force of the motor at the sampling point (n +1) and the sampling point (n), respectively, Delta i_δ(n +1) is a sampling point (n +1) delta axis current error, K_δEstimating coefficients for the back emf;

estimating a motor rotor position angle theta from the derived motor back emf_M：

In the above formula, θ_M(n+1)、θ_M(n) is the position angle of the rotor of the motor at the sampling point (n +1) and the sampling point (n), delta i_γ(n +1) is the gamma-axis current difference at sample point (n +1), K_EIs the motor back electromotive force coefficient, K_θA rotor position angle compensation coefficient;

step 7, according to the inductance parameterDetermining back emf estimation coefficientsAnd rotor position angle compensation coefficientAnd determines the convergence domain ofAndthe value:

when Δ θ ≈ 0, by integrating equations (5) (6) (7), a discrete equation of the back electromotive force and position angle estimation algorithm can be obtained:

the back emf estimation algorithm formula (6) and the position angle estimation algorithm formula (7) are stable under the condition thatAndis less than 1, so that the back emf estimation coefficient K is less than_δAnd a rotor position angle compensation coefficient K_θThe convergence domain of (c) is:

for inductance parameters, taking into account the effect of magnetic circuit saturation of the machineCorresponding toAndthe convergence domain of (c) is:

andthe value of (A) is calculated by adopting the following formula:

wherein the coefficient zeta is 0.3-0.5, the value of the coefficient zeta is the same as that of the working condition without the headwind, and the coefficient zeta is 0.6-0.8In the convergence domain of the system as much as possible to obtain a larger compensation coefficient valueThe purpose is to increase the disturbance rejection of the position estimation; as can be seen from equation (10), the motor magnetic circuit entering the saturation state reduces the inductance parameter, resulting in a reduced convergence range of the position estimation.

Step 8, calculating the position angle theta of the active rotating magnetic field in the open-loop synchronous operation mode₀And calculating theta₀And estimating the motor rotor position angle theta_MAnd theta₀Difference of (a), i.e. theta_err＝θ_M-θ₀。

9, according to the change rule of the fluctuation of the estimation error of the rotor position angle, the estimation error theta of the rotor position angle is enabled to be realized by an active compensation method_errThe fluctuation of (2) is reduced.

Step 9.1, solving for theta_errMaximum value of fluctuation theta_err-MAXMinimum value θ_err-MINAnd compensating for amplitude theta_err-COMP：

Step 9.2, actively compensating the rotor position estimation angle fluctuation according to the following formula

In the above formula, the first and second carbon atoms are,estimating an angle for the actively compensated rotor position, N being the harmonic order of the active compensation, f₀For open-loop operating frequency, t is a time parameter, θ_COMP-SFTIs an actively compensated phase shift angle.

And 10, selecting a cut-in position closed-loop operation mode at the moment when the rotor estimated position angle fluctuation value is smaller than a preset value.

Step 10.1, estimating difference value of rotor position angle after active compensation according to the following discrete calculation formula

And toAnd (3) low-pass filtering:

in the above formula, θ_err-LPF(n+1)、θ_err-LPF(n) estimating differences for the position angles, respectivelyLow pass filtered value at sample point (n +1), sample point (n), K_θerrLPFEstimating a difference for a position angleLow pass filter coefficient, rotor position angle estimation difference after selecting active compensationThe purpose of low-pass filtering is to make K_θerrLPFThe value is large, and the requirement of the system on quick dynamic response is met;

step 10.2, judging whether the fluctuation value of the rotor estimated position angle is less than the preset value according to the following formula

In the above formula, θ_ξEstimating a preset value, theta, for controlling the rotor, at which the position angle fluctuation is as small as possible_ξThe value range is (1.5-3.0%);

step 10.3, selecting the moment when the fluctuation value of the estimated position angle of the rotor is smaller than a preset value, switching from the position open-loop operation mode to the position closed-loop operation mode, and controlling the position angle of the motor without a position sensor:

and step 11, carrying out speed regulation operation of the permanent magnet synchronous motor without position sensor control in a position closed loop operation mode.

Example (b):

the principle experiment verifies that the permanent magnet synchronous motor outer rotor fan is adopted, and the parameters of the motor and the frequency converter are as follows: rated power is 200W; number of pole pairs p_n(ii) 5; stator resistance R_s3.45 Ω; stator straight-axis inductance L without considering magnetic circuit saturation_d9.0 mH; quadrature axis inductance L_q10.0 mH; back electromotive force coefficient K_E35.3V/krpm; DC bus voltage rated value V_dc310V; bus filter capacitance 200 muF. Considering the saturation of the magnetic circuit, the inductance parameters corresponding to the phase current peak values i of different windings are shown in table 1, the winding inductance decreases with the saturation of the magnetic circuit, and when the current is 5A, the inductance parameter is 0.89 times of the inductance when the magnetic circuit is not saturated.

TABLE 1 inductance parameters corresponding to different phase current peak values

I(A)	0.3	1	2	3	4	5	6	7	8
										Ld(mH)	9.0	8.9	8.7	8.5	8.2	8.0	7.6	7.0	6.5
Lq(mH)	10.0	9.8	9.5	9.2	9.0	8.6	8.0	7.5	7.0

Fig. 1 is a block diagram of a position sensorless vector control of a permanent magnet synchronous motor system according to the present invention, which includes units such as a double-resistance sampling circuit, Clarke and PARK transformation, maximum torque to current ratio control (MTPA), speed loop, dq-axis current loop, PARK inverse transformation, rotor position estimation, SVPWM calculation, and three-phase PWM inverter.

The invention adopts a motor rotor position estimation method based on a gamma delta expected rotation coordinate system, establishes the gamma delta expected rotation coordinate system in a permanent magnet synchronous motor vector control d and q coordinate system as shown in figure 2, wherein the motor rotates anticlockwise, U, V, W represents a three-phase stator winding, e_MFor estimating the back emf, the direction coincides with the delta axis, e the actual back emf, the direction coincides with the q axis, theta represents the actual position angle of the rotor, theta_MRepresenting the estimated rotor position angle, Δ θ - θ_MRepresenting the position angle estimation error.

Selecting motor winding phase current peak value I of open-loop operation according to upwind intensity_p0Is 5A, and an open-loop operating frequency f is set₀3.45Hz, the inductance parameter isTo take into account the effects of saturation of the motor's magnetic circuitAndthe convergence domain of (c) is:

andthe values of (A) are as follows:

where the coefficient ζ is 0.4 and ξ is 0.8.

FIG. 3 shows an embodiment of the present invention using the estimated difference θ of the front rotor position angle_MWaveform of (a), theta_MIs relatively large, theta_MThe ripple contains mainly 6 th harmonics, and if the position is switched from open to closed in this case, the algorithm for rotor position angle estimation may not converge, resulting in a failed start.

Calculating the position angle theta of the active rotating magnetic field in the open-loop synchronous operation mode according to FIG. 3₀And estimating the motor rotor position angle theta_MDifference of (a) theta_err＝θ_M-θ₀To find out theta_errMaximum value of fluctuation theta_err-MAX12.3 electrical degrees, minimum value θ_err-MIN2.1 ° electrical angle.

FIG. 4 shows an example of the difference θ between the rotor position angle estimates using the scheme of the present invention_MIs reduced by an active compensation method, as can be seen from the figure, the value of the fluctuation of the rotor position estimation angle is reduced by theta_err-MAXAnd theta_err-MINThe compensation amplitude theta can be obtained_COMPElectrical angle 5.1 °, harmonic number N of active compensation 6, phase shift angle θ of active compensation in this example_COMP-SFTTake an electrical angle of 125 deg..

FIG. 5 shows the experimental waveforms for successful strong upwind start according to the method of the present invention, and the phase current peak value I of the motor winding selected for open-loop operation according to the upwind strength_p0At 5A, open loop operating frequency f₀According to the invention, after the rotor position estimation angle fluctuation value is reduced by an active compensation method, the position closed loop is entered, as can be seen from fig. 5, because the closed loop is under the condition of upwind, in the transition region of the open loop switching into the closed loop, the phase current peak value of the motor winding is increased to 6.5A, and after about 300ms, the system enters a stable position closed loop operation mode. In fig. 5, in order to study the stability of the system at the time of upwind start, the voltage waveform V to the bus is increased_dcThe tracking detection of (2) that the bus voltage V at upwind start is shown in the figure_dcThe falling is generated in the transition region of the open loop switching into the closed loop, but the amplitude value does not exceed 20V, and for a motor with the rated power of 200W, it is reasonable to take 200 muF as the filter capacitor of the upwind starting bus, and it can be seen from figure 5 that the motor is started successfully under the strong upwind working condition finally.

The above embodiments are only used to illustrate the technical solutions of the present application, and not to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present application and are intended to be included within the scope of the present application.