A Position-Free Sliding Mode Control Method

Abstract

The present invention discloses a position-free sliding mode control method, which relates to the field of motor control technology and solves the technical problem of high computational complexity of existing permanent magnet synchronous motor control methods. The method comprises: sampling the three-phase current of the motor through an AD module, and obtaining the feedback current I of the γδ axis after abc→γδ transformation. δ , I γ ; Set the speed by comparing ω * and feedback speed ω est Get the speed deviation ω err ,ω err After comparing the deviation PI regulator, the command current I is obtained * ; Command current I * The reference current β of the γδ axis is obtained by sinβ and cosβ respectively, which is the weak magnetic angle; I γ After comparing the deviation PI regulator, the reference voltage of the γδ axis is obtained. δ After comparing the deviation PI regulator, the reference voltage of the γ and δ axes is obtained respectively through γ * δ * → After γδ transformation, we get the control voltage V γ 、V δ ; V γ 、V δ After undergoing the transformations of γδ→αβ and αβ→abc in sequence, a PWM control signal is obtained, which is used to control the operation of the motor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of motor control, more particularly, it relates to a positionless sliding mode control method. BACKGROUND

[0002] The existing patent application files CN202110918272.X and CN202111047159.5 use sliding mode control for position estimation algorithm of positionless permanent magnet synchronous motor. The former needs to construct an integral sliding mode surface to ensure the system converges in a limited time, and also needs to design a second-order nonsingular terminal sliding mode controller to ensure the system has good control accuracy and faster convergence speed. Finally, through an adaptive control method, a parameter setting type sliding mode tracking controller is designed to estimate the upper bound of uncertainty factors, which is complex to design and difficult to set, and is difficult to implement. The latter is a permanent magnet synchronous motor sliding mode control strategy based on fixed-time variable power exponential reaching law, which is complex in algorithm and difficult to realize digitally. SUMMARY

[0003] The technical problem to be solved by the present application is to solve the above-mentioned deficiencies of the prior art. The purpose of the present application is to provide a positionless sliding mode control method with simple calculation.

[0004] The technical solution of the present application is: a positionless sliding mode control method, comprising:

[0005] Step S1. Sample the three-phase current of the motor through the AD module, and get the feedback current of the shaft after abc→ conversion.

[0006] Step S2. Get the speed deviation by comparing the set speed with the feedback speed , get the command current after comparing the deviation PI regulator; the command current is respectively , get the command reference current of the shaft , ,

[0007] Step S3. and get the command reference voltage of the shaft after comparing the deviation PI regulator , ​​​​After comparing the deviation PI regulator, we get The command reference voltage of the shaft ;

[0008] Step S4. 、 Respectively after → After transformation, the control voltage is obtained 、 ; 、 In turn, after → 、 →abc transformation, the PWM control signal is obtained, and the PWM control signal is used to control the motor to run.

[0009] As a further improvement, in step S1, the AD module samples the phase current of the motor and , the other phase current + ;

[0010] From the sampling of the last current 、 and the estimated angle obtained according to the last AD module interruption, we get 、 , the specific implementation process is shown in the following formula (1), (2), (3) respectively:

[0011] (1)

[0012] (2)

[0013] (3).

[0014] Further, the calculation process of the estimated angle is as follows: first, calculate the current error estimate value 、 , then according to 、 , the speed of the last 2 times , the last command reference current , and the speed current feedback coefficient 、 、 、 , the speed and angle feedback amount 、 is calculated, and then according to 、 , the back electromotive force coefficient Calculate the angular velocity corresponding to the estimated feedback electromotive force and estimated angle change , and finally according to 、 Find the estimated angle The specific implementation process is as follows:

[0015] (4)

[0016] (5)

[0017] (6)

[0018] (7)

[0019] (8)

[0020] in is the position estimation coefficient, and T is the carrier period.

[0021] Further, in step S2, according to , the carrier period T is used to calculate the angular velocity increment ,according to 、 , speed LPF coefficient Calculate the angular velocity increment , and finally according to 、 Calculated The specific implementation process is as follows:

[0022] (9)

[0023] (10)

[0024] according to 、 、 、 、 、 、 Calculated 、 、 、 ,The specific implementation process is as shown in the following formula (11):

[0025] (11)

[0026] in is the motor induced voltage constant, is the motor d-axis inductance, is the motor q-axis inductance, R is the motor stator resistance, , is the output of the previous voltage command estimation loop before the carrier period AD module triggers an interrupt;

[0027] according to the last speed deviation , the speed loop proportional coefficient , the speed loop integral coefficient , and the carrier period T, the current command current is calculated according to , , the current axis command reference current , is calculated according to the following formula (12) (13) (14):

[0028] (12)

[0029] (13)

[0030] (14).

[0031] Further, in step S3, the command deviation current , is first calculated according to the previous feedback current , , the current voltage , is calculated according to , , axis voltage loop proportional coefficient , , axis speed loop integral coefficient , , the current voltage axis, axis after comparison deviation PI regulator is obtained , , and finally the command reference voltage , , , , , , is calculated according to , , the specific implementation process is shown in the following formula (15) (16) (17) respectively:

[0032] (15)

[0033] (16)

[0034] (17).

[0035] Further, in step S4, the voltage command value of the motor U, V, W phase is calculated according to , , respectively , , , the specific implementation process is shown in the following formula (18) (19) (20) respectively:

[0036] (18)

[0037] (19)

[0038] (20)

[0039] According to , , , bus voltage Vdc, duty cycle CPu, CPv, CPw of PWM control signal is calculated, the specific implementation process is shown in the following formula (21) respectively:

[0040] (21)

[0041] Wherein dutyMAX is the value of 100% duty cycle corresponding to the number stored in the PWM carrier interrupt period register.

[0042] Advantages

[0043] Compared with the prior art, the application has the advantages of:

[0044] The application solves the shortcomings of high algorithm complexity, estimation difficulty and difficulty in digital implementation in the PMSM sliding mode estimation algorithm of the prior art, and can be applied to position estimation of any PMSM, and is also applicable to AC induction motors. The algorithm is simple, has strong universality, high reliability, and has good economic and social application value. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 is a hardware structure block diagram of the application;

[0046] Figure 2 It is a specific calculation flow chart of the present invention;

[0047] Figure 3 This is a current waveform diagram of the motor controlled by the present invention from startup to operation;

[0048] Figure 4 This is a waveform diagram of the present invention controlling the motor to switch from open-loop startup to closed-loop startup;

[0049] Figure 5 This is a waveform diagram of the present invention controlling the motor to run at 30 Hz. DETAILED DESCRIPTION

[0050] The present invention will be further described below with reference to the specific embodiments in the accompanying drawings.

[0051] See Figures 1-5 The sliding mode controller block diagram of the present invention is as follows: Figure 1 As shown, the complete control system includes rectification, filtering, voltage regulation, inversion, and motor current sampling. DB1 is the rectifier bridge, which converts the input AC power into pulsating DC power. Electrolytic capacitors C1 and C2 are energy storage capacitors, stabilizing the rectified bus voltage. R1 and R2 are equalizing resistors, maintaining the voltage across bus energy storage capacitors C1 and C2 at half the bus voltage. Cement resistor R3 is a soft-start protection resistor, preventing damage to the rectifier bridge and subsequent IPM modules due to overcurrent breakdown during power-up. K1 is a soft-start relay, which disconnects starting resistor R3 after startup to minimize losses caused by soft-start resistor R1 during inverter operation and improve inverter efficiency. RS1 is the motor U-phase sampling resistor, RS2 is the motor V-phase sampling resistor, RS3 is the motor W-phase sampling resistor, and RS4 is the motor bus current sampling resistor, providing bus current sampling and protection. Vdc is the bus voltage.

[0052] A position-free sliding mode control method, comprising:

[0053] Step S1. Sample the three-phase current of the motor through the AD module and pass through abc→ After transformation, we get Feedback current of the axis 、 ;abc→ The transform is referred to as Clark transform;

[0054] Step S2. Set the speed by comparing With feedback speed Get speed deviation , After comparing the deviation PI regulator, the command current is obtained ; Command current Passing respectively , get axis command reference current , , is the field weakening angle, i.e. is the 2r rotation coordinate system in 3s-2s-2r axis current and the quadrature axis axis angle;

[0055] Step S3. and get axis command reference voltage , and get axis command reference voltage ;

[0056] Step S4. , get control voltage → , , ; , get PWM control signal after → , →abc transformation, and use the PWM control signal to control the motor to run; → Park transformation, → , Clark inverse transformation.

[0057] In step S1, the AD module samples the phase currents of the motor and , and the other phase current + ;

[0058] get , and the estimated angle obtained according to the last AD module interruption, and get , by 3 / 2 transformation, which is called Clark transformation. The specific implementation process is shown in the following formulas (1), (2), and (3):

[0059] (1)

[0060] (2)

[0061] (3).

[0062] Estimated angle The calculation process is to first calculate the current error estimate 、 , and then according to 、 , first 2 speeds , the last instruction reference current , and the speed current feedback coefficient 、 、 、 Calculate the speed and angle feedback 、 , and then according to 、 , back electromotive force coefficient Calculate the angular velocity corresponding to the estimated feedback electromotive force and estimated angle change , and finally according to 、 Find the estimated angle The specific implementation process is as follows:

[0063] (4)

[0064] (5)

[0065] (6)

[0066] (7)

[0067] (8)

[0068] in is the position estimation coefficient, and T is the carrier period.

[0069] In step S2, according to , the carrier period T is used to calculate the angular velocity increment ,according to 、 , speed LPF coefficient Calculate the angular velocity increment , and finally according to 、 Calculated , the specific implementation process is shown in the following formula (9) (10) respectively:

[0070] (9)

[0071] (10)

[0072] According to , , , , , , , the calculation is obtained , , , , the specific implementation process is shown in the following formula (11) respectively:

[0073] (11)

[0074] Wherein is the motor induction voltage constant, is the motor d-axis inductance, is the motor q-axis inductance, R is the motor stator resistance, , is the output of the previous voltage command estimation loop in the carrier period AD module triggered interrupt;

[0075] According to the last speed deviation , the speed loop proportional coefficient , the speed loop integral coefficient , the carrier period T, the current command current is calculated, according to , , the current axis command reference current , is calculated, the specific implementation process is shown in the following formula (12) (13) (14) respectively:

[0076] (12)

[0077] (13)

[0078] (14).

[0079] In step S3, first according to , and the previous feedback current , , the command deviation current 、 , according to 、 , the voltage loop proportional coefficient of the axis 、 , the speed loop integral coefficient of the axis 、 respectively calculate the axis, the current voltage obtained after comparing the deviation PI regulator of the axis 、 , finally according to 、 、 、 、 、 、 the instruction reference voltage is calculated 、 , the specific implementation process is shown in the following formula (15) (16) (17) respectively:

[0080] (15)

[0081] (16)

[0082] (17).

[0083] In step S4, the voltage instruction values of the U, V, W phases of the motor are calculated respectively according to 、 、 、 、 , the specific implementation process is shown in the following formula (18) (19) (20) respectively:

[0084] (18)

[0085] (19)

[0086] (20)

[0087] According to 、 、 , the duty cycle CPu, CPv, CPw of the PWM control signal is calculated according to the bus voltage Vdc, the specific implementation process is shown in the following formula (21) respectively:

[0088] (21)​

[0089] wherein dutyMAX is the value stored in the PWM carrier interrupt period register corresponding to a 100% duty cycle.

[0090] The present application overcomes the shortcomings of high algorithm complexity, difficult estimation and difficult digital implementation in the PMSM sliding mode estimation algorithm of the conventional technology, can be applied to the position estimation of any PMSM, has simple algorithm, strong universality, high reliability, and has good economic and social application value. The present application can also effectively compensate and improve the deviation of the angle and the angular velocity caused by the software delay and the filter delay in the conventional algorithm.

[0091] The above is only the preferred embodiment of the present application, and it should be pointed out that for those skilled in the art, without departing from the structure of the present application, a number of modifications and improvements can be made, which will not affect the effect of the implementation of the present application and the practicability of the patent.

Claims

1. A position-free sliding mode control method, characterized in that: include: Step S1. Sample the three-phase current of the motor through the AD module and pass through abc→ After transformation, we get Feedback current of the axis 、 ; Step S2. Set the speed by comparing With feedback speed Get speed deviation , After comparing the deviation PI regulator, the command current is obtained ; Command current Passing respectively 、 get Axis command reference current 、 , is the magnetic weakening angle; Step S3. and After comparing the deviation PI regulator, we get Axis command reference voltage , and After comparing the deviation PI regulator, we get Axis command reference voltage ; Step S4. 、 Passing respectively → After transformation, the control voltage is obtained 、 ; 、 Experienced in turn → 、 →After the abc transformation, the PWM control signal is obtained, and the PWM control signal is used to control the motor operation; In step S1, the AD module samples the phase current of the motor and , the other phase current + ; By sampling the last current 、 And the estimated angle obtained from the last AD module interrupt After 3 / 2 transformation, we get 、 The specific implementation process is as follows: （1） （2） （3）； Estimated angle The calculation process is to first calculate the current error estimate 、 , and then according to 、 , first 2 speeds , the last instruction reference current , and the speed current feedback coefficient 、 、 、 Calculate the speed and angle feedback 、 , and then according to 、 , back electromotive force coefficient Calculate the angular velocity corresponding to the estimated feedback electromotive force and estimated angle change , and finally according to 、 Find the estimated angle The specific implementation process is as follows: （4） （5） （6） （7） （8） in is the position estimation coefficient, and T is the carrier period.

2. A position-free sliding mode control method according to claim 1, characterized in that: In step S2, according to , the carrier period T is used to calculate the angular velocity increment ,according to 、 , speed LPF coefficient Calculate the angular velocity increment , and finally according to 、 Calculated The specific implementation process is as follows: （9） （10） according to 、 、 、 、 、 、 Calculated 、 、 、 ,The specific implementation process is as shown in the following formula (11): （11） in is the motor induced voltage constant, is the motor d-axis inductance, is the motor q-axis inductance, R is the motor stator resistance, 、 It is the output of the previous voltage instruction estimation loop in the carrier cycle AD module that triggers the interruption; According to the last speed deviation , speed loop proportional coefficient , speed loop integral coefficient , carrier period T calculates the current command current ,according to 、 Calculate the current Axis command reference current 、 The specific implementation process is as follows: （12） （13） （14）。 3. A position-free sliding mode control method according to claim 2, characterized in that: In step S3, first 、 and the previous feedback current 、 Calculate command deviation current 、 ,according to 、 , Voltage loop proportional coefficient of the axis 、 , Speed ​​loop integral coefficient of the axis 、 Calculate separately axis, The current voltage obtained after the axis passes through the comparison deviation PI regulator 、 , and finally according to 、 、 、 、 、 Calculate the command reference voltage 、 The specific implementation process is as follows: （15） （16） （17）。 4. A position-free sliding mode control method according to claim 3, characterized in that: In step S4, according to 、 、 Calculate the voltage command values ​​of the U, V, and W phases of the motor respectively 、 、 The specific implementation process is as follows: （18） （19） （20） according to 、 、 , bus voltage Vdc to calculate the duty ratios CPu, CPv, and CPw of the PWM control signal. The specific implementation process is as shown in the following formula (21): （21） in dutyMAX The value stored in the PWM carrier interrupt period register corresponds to a 100% duty cycle.

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