CN114759848A - Improved direct torque control method based on space vector modulation - Google Patents

Improved direct torque control method based on space vector modulation Download PDF

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Publication number
CN114759848A
CN114759848A CN202011577460.2A CN202011577460A CN114759848A CN 114759848 A CN114759848 A CN 114759848A CN 202011577460 A CN202011577460 A CN 202011577460A CN 114759848 A CN114759848 A CN 114759848A
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flux linkage
motor
torque
value
space vector
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Inventor
魏振
姚广
赵楠
任祥正
张楠
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Research Institute of Physical and Chemical Engineering of Nuclear Industry
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Research Institute of Physical and Chemical Engineering of Nuclear Industry
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
    • H02P21/14—Estimation or adaptation of machine parameters, e.g. flux, current or voltage
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
    • H02P21/05—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation specially adapted for damping motor oscillations, e.g. for reducing hunting
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
    • H02P21/14—Estimation or adaptation of machine parameters, e.g. flux, current or voltage
    • H02P21/20—Estimation of torque
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P25/00—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details
    • H02P25/02—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the kind of motor
    • H02P25/022—Synchronous motors
    • H02P25/024—Synchronous motors controlled by supply frequency
    • H02P25/026—Synchronous motors controlled by supply frequency thereby detecting the rotor position
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
    • H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
    • H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters
    • H02P27/08—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
    • H02P6/10—Arrangements for controlling torque ripple, e.g. providing reduced torque ripple
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P2207/00—Indexing scheme relating to controlling arrangements characterised by the type of motor
    • H02P2207/05—Synchronous machines, e.g. with permanent magnets or DC excitation

Abstract

The invention discloses an improved direct torque control method based on space vector modulation, which comprises the steps of (I) parameter acquisition coordinate transformation; (II) estimating stator flux linkage; (III) estimating the torque of the motor; (IV) torque flux linkage regulation control; (V) reference voltage estimation; (VI) a space vector algorithm. The invention adopts the combination of the space vector modulation technology and the direct torque control strategy, effectively reduces the pulsation of torque and flux linkage, and simultaneously ensures that the switching frequency of the inverter becomes constant; the method for estimating the stator flux linkage by using the improved flux linkage integrator eliminates the influence of the initial position deviation of the rotor on the estimation of the stator flux linkage, and further improves the detection precision of the rotor position and the stator flux linkage.

Description

Improved direct torque control method based on space vector modulation
Technical Field
The invention belongs to the field of permanent magnet synchronous motor control, and particularly relates to an improved direct torque control method based on space vector modulation.
Background
The permanent magnet synchronous motor has the advantages of high power density, excellent mechanical performance, easy maintenance and the like, and is widely applied to the fields of industrial control and the like. The current direct torque control and vector control are two high-performance control strategies of the permanent magnet synchronous motor. Space Vector Modulation (SVM) is that in a control period, any required voltage vector can be obtained by synthesizing adjacent basic voltage vectors and zero voltage vectors, and linear continuous adjustment of the voltage vector is realized. Direct Torque Control (DTC) is a method based on stator magnetic field orientation and space voltage vector analysis, and selects a proper space voltage vector from a prefabricated switch table to directly Control Torque and flux linkage according to Torque deviation, flux linkage deviation and the space position of a stator flux linkage and a certain rule; the direct torque control has attracted wide attention due to the characteristics of simple structure, fast torque response and good dynamic performance, however, in the conventional direct torque control mode, the selectable voltage vectors are eight basic voltage space vectors and zero vectors all the time, and the method for selecting the voltage vectors cannot meet the requirement of a system for completely compensating the torque and flux linkage errors at the same time, so that the problems of switching frequency change, large torque pulsation, flux linkage pulsation, poor starting and low-speed performance and the like are caused, and the popularization and application of the mode are limited.
Disclosure of Invention
The invention is provided for overcoming the defects of torque ripple, flux linkage ripple and the like of a permanent magnet synchronous motor driver for direct torque control in the prior art, and aims to provide an improved direct torque control method based on space vector modulation.
The invention is realized by the following technical scheme:
an improved direct torque control method based on space vector modulation comprises the following steps:
parameter acquisition coordinate transformation
Collecting direct current voltage, three-phase current and voltage of the motor, and completing the conversion of motor parameters to a two-phase static coordinate system;
(II) stator flux linkage estimation
According to the motor parameter value, an improved integrator is adopted to complete the estimation of the stator flux linkage, and the absolute value of the flux linkage is calculated;
(III) Motor Torque estimation
Calculating the electromagnetic torque of the motor according to the estimated value of the stator flux linkage and the current value of the motor, accumulating the calculated values for multiple times, and then averaging to obtain a final motor torque value;
(IV) Torque flux linkage Regulation control
Comparing the estimated stator flux linkage absolute value and the torque value with reference values of the stator flux linkage absolute value and the torque value respectively, calculating a deviation value, wherein the torque deviation value is subjected to PI (proportional-integral) regulator to obtain a load angle increment, and the deviation value of the torque deviation value and the flux linkage absolute value is used as the input of a reference voltage estimation unit;
(V) reference Voltage estimation
Calculating a voltage vector reference value required to be synthesized by the system according to the load angle increment and the deviation value of the absolute value of the stator flux linkage;
(VI) space vector algorithm
And according to the voltage vector reference value, executing a space vector algorithm, calculating a duty ratio, outputting a PWM (pulse-width modulation) driving signal, controlling the three-phase inverter to synthesize a required voltage vector, and driving the motor to operate.
In the above technical solution, the improved integrator is:
Figure BDA0002864767630000021
in the formula: z is a radical ofα、zβIs the compensation value of the flux linkage integral.
In the above technical solution, the compensation value z of the flux linkage integralα、zβDesigned as a saturation function, and limits the amplitude thereof,
Figure BDA0002864767630000031
in the formula:
Figure BDA0002864767630000032
is the magnitude of the flux linkage.
In the above technical solution, the calculation formula of the electromagnetic torque of the motor is a two-phase direct current rotating coordinate system formula:
Te＝Pn[ψfiq+(Ld-Lq)idiq]。
in the above technical solution, the two-phase dc rotating coordinate system formula is adopted as the front pair iα、iβThe current is subjected to park transformation to convert it into iq、idThen to iq、idAnd filtering the current to obtain the current which is then calculated according to a formula.
In the above technical solution, the filtering uses a first-order low-pass filter for filtering.
In the above technical solution, the motor torque value TmtThe average electromagnetic torque T is obtained by accumulating and averagingaveCompared with the motor output torque improved by a motor manufacturer, the motor output torque is multiplied by a coefficient K to be corrected to obtain the motor output torque,
Tmt＝K*Tave。
in the above technical solution, before the estimation of the stator flux linkage in step (ii) is performed, the position of the rotor of the motor is checked.
In the above technical solution, the method for detecting the position of the motor rotor is a rotor positioning method.
In the above technical solution, the rotor positioning method specifically includes: firstly, a 90-degree voltage vector which is 10% -30% of rated voltage is introduced to a q axis of a motor stator, and a rotor is positioned in a 90-degree direction; and then a zero-degree voltage vector which is 10% -30% of the rated voltage is introduced to the q axis of the motor stator, so that the rotor is positioned to zero degree.
The invention has the beneficial effects that:
the invention provides an improved direct torque control method based on space vector modulation, which combines a space vector modulation technology with a direct torque control strategy, effectively reduces the pulsation of torque and flux linkage, and simultaneously ensures that the switching frequency of an inverter becomes constant; the stator flux linkage estimation is carried out by adopting the method of improving the flux linkage integrator, the influence of the initial position deviation of the rotor on the stator flux linkage estimation is eliminated, and the detection precision of the rotor position and the stator flux linkage is further improved.
Drawings
FIG. 1 is a block diagram of a conventional direct torque control system;
FIG. 2 is a control system architecture diagram of the improved direct torque control method of the present invention based on space vector modulation;
FIG. 3 is a main flow chart of the improved direct torque control method of the present invention based on space vector modulation;
FIG. 4 is a sub-flowchart of the improved direct torque control method based on space vector modulation of the present invention.
For a person skilled in the art, without inventive effort, other relevant figures can be derived from the above figures.
Detailed Description
In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution of the improved direct torque control method based on space vector modulation according to the present invention is further described below by referring to the drawings of the specification and through specific embodiments.
Example 1
An improved direct torque control method based on space vector modulation comprises the following steps:
parameter acquisition coordinate transformation
Collecting direct current voltage, three-phase current and voltage of the motor, and completing the conversion of motor parameters to a two-phase static coordinate system;
(II) stator flux linkage estimation
According to the motor parameter value, an improved integrator is adopted to complete the estimation of the stator flux linkage, and the absolute value of the flux linkage is calculated;
(III) Motor Torque estimation
Calculating the electromagnetic torque of the motor according to the estimated value of the stator flux linkage and the current value of the motor, accumulating the calculated values for multiple times, and then calculating the average value to obtain the final torque value of the motor;
(IV) Torque flux linkage Regulation control
Comparing the estimated stator flux linkage absolute value and the torque value with reference values of the stator flux linkage absolute value and the torque value respectively, calculating a deviation value, wherein the torque deviation value is subjected to PI (proportional-integral) regulator to obtain a load angle increment, and the deviation value of the torque deviation value and the flux linkage absolute value is used as the input of a reference voltage estimation unit;
(V) reference Voltage estimation
Calculating a voltage vector reference value required to be synthesized by the system according to the load angle increment and the deviation value of the absolute value of the stator flux linkage;
(VI) space vector algorithm
And according to the voltage vector reference value, executing a space vector algorithm, calculating a duty ratio, outputting a PWM (pulse-width modulation) driving signal, controlling the three-phase inverter to synthesize a required voltage vector, and driving the motor to operate.
The improved direct torque control method based on space vector modulation of the invention adopts C language to be written in a DSP control board for operation, FIG. 3 is a main program flow chart, FIG. 4 is a timer interrupt subprogram flow chart, the timer interrupt subprogram is executed in the main program, and the improved direct torque control technical algorithm based on space vector modulation is mainly completed, and the specific program flow is as follows:
the main procedure is as follows:
(I) start with
Program start, from the main program entry, S1;
(II) initialization
Initializing the DSP, and finishing the initialization work of a DSP peripheral clock, a watchdog, an IO port (input and output) and an interrupt vector table (S2);
(III) configuration register
Configuring a timer, a PWM register, an SCI register, and an interrupt register, and enabling a related interrupt function, S3;
(IV) initializing software parameters
Initializing relevant parameters such as a timer, a PWM duty ratio, delay time, RS232 communication software and the like, and S4;
(V) Loop waiting
Entering a main loop, and waiting for the occurrence of timer interruption, S5;
(VI) executing the interrupt program and returning
And executing the timer interrupt subprogram, returning to the main program after the timer interrupt subprogram is completed, and circularly waiting S6.
The timer interrupt subroutine is implemented as follows:
(I) interrupt Start
A timer interrupt occurs, and a timer interrupt program is entered, S7;
(II) parameter acquisition coordinate transformation
Collecting direct current voltage, three-phase current and voltage of the motor, and completing the conversion of motor parameters to a two-phase static coordinate system S8;
(III) stator flux linkage estimation
According to the motor parameter value, an improved integrator is adopted to replace an original pure integrator, the estimation of the stator flux linkage is completed, and the absolute value of the flux linkage is calculated, S9;
(IV) Motor Torque estimation
Calculating the electromagnetic torque of the motor according to the estimated value of the stator flux linkage and the current value of the motor, accumulating the calculated values for multiple times, and then averaging to obtain a final motor torque value S10;
(V) Torque flux linkage Regulation control
Comparing the estimated stator flux absolute value and the torque value with reference values of the stator flux absolute value and the torque value respectively, calculating a deviation value, wherein the torque deviation value is subjected to PI regulator to obtain a load angle increment, and the deviation value of the torque deviation value and the flux absolute value is used as input of a reference voltage estimation unit S11;
(VI) reference voltage estimation
Calculating a voltage vector reference value required to be synthesized by the system according to the load angle increment and the deviation value of the absolute value of the stator flux linkage, S12;
(VII) space vector algorithm
Executing a space vector algorithm according to the voltage vector reference value, calculating a duty ratio, outputting a PWM (pulse-width modulation) driving signal, controlling a three-phase inverter to synthesize a required voltage vector, and driving a motor to operate S13;
(VIII) interrupt completion return to Main program
The algorithm for motor modified direct torque control is completed, and the interruption completion returns to the main routine, S14.
The improvement of the present invention and the resulting benefits thereof are detailed below by comparison with conventional direct torque control methods.
(1) Improved voltage synthesis mode and torque flux linkage regulation mode
The structure of a direct torque control system of a conventional permanent magnet synchronous motor is shown in fig. 1, and the system mainly comprises a motor torque estimator, a stator flux linkage estimator, a torque hysteresis comparator, a flux linkage hysteresis comparator and a switching voltage vector selection unit.
The conventional DTC control principle is specifically as follows: detecting the switching state of the inverter and the three-phase current and voltage of the motor in real time, and obtaining the current i of the motor under a two-phase static coordinate system through coordinate transformationα、iβAnd voltage uα、uβAnd the real-time torque T to the motor through the stator flux linkage and the torque estimatoreAnd absolute value of flux linkage feedback
Figure BDA0002864767630000071
Reference value of both and torque and flux linkage
Figure BDA0002864767630000072
And obtaining control signals of flux linkage and torque through the hysteresis comparator after comparison, selecting a proper basic voltage vector according to the control signals by referring to a switch state selection table, and controlling the output of the inverter to finish the control operation of the motor.
In a conventional control mode, the mode of the switch state selection table can only select eight basic voltage space vectors and zero vectors, and cannot select the most appropriate voltage vector compensation system to meet the requirements of complete torque and flux linkage errors.
The invention is based on the conventional direct torque control technology, adopts the space vector modulation technology to replace a switch state selection table, and realizes the linear continuous adjustment of a voltage vector through any voltage vector required by a basic voltage vector and zero voltage vector synthesis system in a control period, wherein the structural diagram of the DTC-SVM control system is shown in figure 2.
The reference voltage estimator is used for estimating a reference voltage vector, and the basic principle thereof is composed of equations (1) to (3):
Figure BDA0002864767630000081
Figure BDA0002864767630000082
Figure BDA0002864767630000083
in the formula: i.e. iα,iβ-stator α, β axis currents;
uα,uβ-stator α, β axis voltage;
ψα,ψβ-flux linkage of stator α, β axes;
Δψα,Δψβ-offset values of stator α, β axis flux linkages;
δs,Δδs-phase angle, load angle increment of stator flux linkage vector;
θ - - -rotor position angle;
Rs-stator resistance.
In the DTC-SVM control system, an adjusting mode of a hysteresis comparator is not adopted any more, a PI regulator is adopted for outputting a load increment angle for torque, the load increment angle and a deviation value of a flux linkage are used as input of a reference voltage estimator, the reference voltage estimator calculates a required reference voltage vector, the reference voltage value is modulated by an SVM unit to generate a PWM signal, a three-phase inverter is controlled to synthesize the required voltage vector, and the driving operation of the permanent magnet synchronous motor is completed.
(2) Improved flux linkage estimation method
Also, in the direct torque control strategy, the flux linkage ψsIs important, and the stator flux linkage psi of the permanent magnet synchronous motor under the alpha-beta coordinate system is normalα、ψβAnd torque TeCan be expressed as:
Figure BDA0002864767630000084
Te＝1.5Pn(ψαiβ-ψβiα) (5)
p in formula (5)n-number of motor pole pairs.
According to the formula, the conventional direct torque control system adopts a pure integrator to estimate the stator flux linkage, the pure integrator has the problems of direct current offset and initial value, the rotor of the permanent magnet synchronous motor has initial excitation, and the rotor magnetic pole positioning method inevitably brings errors of the initial value of the rotor excitation on the amplitude and the phase, so the pure integrator can cause inaccuracy of stator flux linkage estimation, and therefore the improved integrator is adopted to replace the original flux linkage integrator:
Figure BDA0002864767630000091
in the above formula zα、zβThe compensation value for the flux linkage integral is typically designed as a saturation function and its amplitude is limited.
Figure BDA0002864767630000092
In the above formula
Figure BDA0002864767630000093
Is the magnitude of the flux linkage.
The improved integrator has the advantages of a pure integrator and a low-pass filter, amplitude attenuation of the low-pass filter can be eliminated, direct-current components in stator flux linkage can be restrained, and detection accuracy of the flux linkage and the position of a rotor is improved.
(3) Improved stator flux linkage initial value estimation method
In the conventional permanent magnet synchronous motor direct torque control technology, a flux linkage estimation algorithm needs to know the position of an initial flux linkage, but since a sensorless control system has no sensor to know the current position of a rotor, the control system must firstly check the position of the rotor of the motor, and the main methods are two methods:
1) adopting a pulse vibration high-frequency voltage injection method: according to the method, a high-frequency voltage signal is injected on a straight shaft of an estimated two-phase rotating coordinate system, closed-loop regulation control is performed, and judgment is performed by combining the direction of the straight shaft, so that the position angle of a rotor can be quickly and accurately detected under the condition of any initial position without changing or adding a hardware circuit.
2) A rotor positioning method: by performing chopping control (duty ratio is 0.1) on the upper tube and the lower tube of the A phase (any phase) of the inverter, after repeating for many times, the rotor magnetic pole is fixed in the magnetic pole direction corresponding to the A phase winding.
The first method is a pulse vibration high-frequency injection method, which has high detection precision but complex algorithm, and a rotor positioning method has simple control but low precision. The invention adopts a rotor positioning method through comparison.
Rotor positioning typically performs chopper control on phase a, positioning the rotor at zero axis. However, if the rotor of the motor is near 180 degrees, the chopping control is carried out on the phase A, the generated electromagnetic force has a phase difference of 180 degrees, the rotor cannot rotate, and the zero axis cannot be positioned.
The method for twice zero setting positioning comprises the following steps: the rotor is first oriented 90 degrees to the q-axis of the motor stator by applying a sufficiently large 90 degree voltage vector (typically 10% -30% of the nominal voltage). The motor stator q-axis is then energized with a sufficiently large zero degree voltage vector (typically 10% -30% of rated voltage) to position the rotor to zero degrees. Therefore, the rotor can be positioned at zero degree through two positioning operations no matter whether the initial position of the rotor of the motor is at a special position of 90 degrees or 180 degrees or not.
(4) Improved electromagnetic torque estimation method
The calculation of the electromagnetic torque in the direct torque control is very important, and particularly, when the motor is just started, because the current of the motor is small, if the formula (5) is directly adopted to calculate the torque, the accuracy is quite low, so that the motor cannot be started, and even the overcurrent condition is caused. This patent does not use the formula (5) for calculation, but uses the formula in the d _ q coordinate system (two-phase dc rotational coordinate system).
Te＝Pn[ψfiq+(Ld-Lq)idiq] (8)
The advantage of using this formula:
1) less parameters, only iq、idTwo values need to be calculated, and the others are fixed values. And in the formula (5), psiα、ψβ、iα、iβAre all quantities that need to be calculated, and psiα、ψβThe initial estimate is not accurate.
2)iq、idFor the purpose of facilitating calculation and filtering of the DC value, and ψ in equation (5)α、ψβ、iα、iβAll are traffic flows, and the calculation is inconvenient.
Before the formula (8) is adopted, the formula I needs to be pairedα、iβThe current is subjected to park transformation to convert it into iq、idAt the same time, to improve the precision, the pair i must be usedq、idFiltering the current, adopting a first-order low-pass filter to filter the current because the two values are direct current, adopting a formula (8) to calculate the torque value after the filtering, and then accumulating and averaging the torque value to obtain the average electromagnetic torque TaveThe value is compared with the motor output torque improved by the motor manufacturer, and is multiplied by a coefficient K for correction to finally obtain the torque Tmt。
Tmt＝K*Tave (9)
The invention utilizes the DSP28335 control board to carry out software programming, realizes the control algorithm and carries out motor test, and the test result shows that after the direct torque control technology is combined with the SVM technology, the continuous adjustment of voltage space vector is realized, the pulsation of torque and flux linkage is effectively reduced, the control performance of the system is greatly improved, and meanwhile, the improved integrator improves the detection precision of stator flux linkage and rotor position angle.
The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.

Claims (10)

1. An improved direct torque control method based on space vector modulation is characterized in that: the method comprises the following steps:
parameter acquisition coordinate transformation
Collecting direct current voltage, three-phase current and voltage of a motor, and completing the conversion of motor parameters to a two-phase static coordinate system;
(II) stator flux linkage estimation
According to the motor parameter value, an improved integrator is adopted to complete the estimation of the stator flux linkage, and the absolute value of the flux linkage is calculated;
(III) Motor Torque estimation
Calculating the electromagnetic torque of the motor according to the estimated value of the stator flux linkage and the current value of the motor, accumulating the calculated values for multiple times, and then averaging to obtain a final motor torque value;
(IV) Torque flux linkage Regulation control
Comparing the estimated stator flux linkage absolute value and the torque value with reference values of the stator flux linkage absolute value and the torque value respectively, calculating a deviation value, wherein the torque deviation value is subjected to PI (proportional-integral) regulator to obtain a load angle increment, and the deviation value of the torque deviation value and the flux linkage absolute value is used as the input of a reference voltage estimation unit;
(V) reference Voltage estimation
Calculating a voltage vector reference value required to be synthesized by the system according to the load angle increment and the deviation value of the absolute value of the stator flux linkage;
(VI) space vector algorithm
And according to the voltage vector reference value, executing a space vector algorithm, calculating a duty ratio, outputting a PWM (pulse-width modulation) driving signal, controlling the three-phase inverter to synthesize a required voltage vector, and driving the motor to operate.
2. The improved direct torque control method based on space vector modulation according to claim 1, characterized in that: the improved integrator is as follows:
Figure FDA0002864767620000021
in the formula: z is a radical ofα、zβIs the compensation value of the flux linkage integral.
3. The improved direct torque control method based on space vector modulation according to claim 2, characterized in that: compensation value z of said flux linkage integralα、zβDesigned as a saturation function, and limits the amplitude thereof,
Figure FDA0002864767620000022
in the formula:
Figure FDA0002864767620000023
is the magnitude of the flux linkage.
4. The improved direct torque control method based on space vector modulation according to claim 1, characterized in that: the calculation formula of the electromagnetic torque of the motor is a two-phase direct current rotating coordinate system formula:
Te＝Pn[ψfiq+(Ld-Lq)idiq]。
5. the method of claim 4 wherein the direct torque control is based on space vector modulation, wherein: front pair i adopting the two-phase DC rotating coordinate system formulaα、iβThe current is subjected to park transformation to convert it into iq、idThen to iq、idAnd filtering the current, and inputting the filtered current into a formula for calculation.
6. The improved direct torque control method based on space vector modulation according to claim 5, characterized in that: the filtering is performed by adopting a first-order low-pass filter.
7. The method of claim 1 wherein the direct torque control is based on space vector modulation, wherein: the motor torque value TmtAverage electromagnetic torque T is obtained by accumulating and averagingaveCompared with the motor output torque improved by a motor manufacturer, the motor output torque is multiplied by a coefficient K to be corrected to obtain the torque,
Tmt＝K*Tave。
8. the improved direct torque control method based on space vector modulation according to claim 1, characterized in that: and (3) checking the position of the motor rotor before the estimation of the stator flux linkage in the step (II) is carried out.
9. The improved direct torque control method based on space vector modulation according to claim 8, characterized in that: the detection method of the motor rotor position is a rotor positioning method.
10. The improved direct torque control method based on space vector modulation according to claim 9, characterized in that: the rotor positioning method specifically comprises the following steps: firstly, a 90-degree voltage vector which is 10% -30% of rated voltage is introduced to a q axis of a motor stator, and a rotor is positioned in a 90-degree direction; and then a zero-degree voltage vector which is 10% -30% of the rated voltage is led to the q axis of the motor stator, so that the rotor is positioned to zero degree.
CN202011577460.2A 2020-12-28 2020-12-28 Improved direct torque control method based on space vector modulation Pending CN114759848A (en)

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