CN114865980A - Virtual inductor self-correcting permanent magnet motor current ripple spread spectrum control method and system - Google Patents

Virtual inductor self-correcting permanent magnet motor current ripple spread spectrum control method and system Download PDF

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CN114865980A
CN114865980A CN202210579543.8A CN202210579543A CN114865980A CN 114865980 A CN114865980 A CN 114865980A CN 202210579543 A CN202210579543 A CN 202210579543A CN 114865980 A CN114865980 A CN 114865980A
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current ripple
value
phase current
virtual
inductance
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甘醇
任浩天
倪锴
石昊晨
王宏喆
张冲
曲荣海
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Huazhong University of Science and Technology
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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
    • H02P23/00—Arrangements or methods for the control of AC motors characterised by a control method other than vector control
    • H02P23/0004—Control strategies in general, e.g. linear type, e.g. P, PI, PID, using robust control
    • H02P23/0022—Model reference adaptation, e.g. MRAS or MRAC, useful for control or parameter estimation
    • 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
    • H02P23/00—Arrangements or methods for the control of AC motors characterised by a control method other than vector control
    • H02P23/14—Estimation or adaptation of motor parameters, e.g. rotor time constant, flux, speed, 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
    • 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
    • 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
    • H02P6/14—Electronic commutators
    • H02P6/16—Circuit arrangements for detecting position
    • H02P6/18—Circuit arrangements for detecting position without separate position detecting elements
    • H02P6/182—Circuit arrangements for detecting position without separate position detecting elements using back-emf in windings
    • 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
    • H02P6/28—Arrangements for controlling current
    • 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
    • H02P2203/00—Indexing scheme relating to controlling arrangements characterised by the means for detecting the position of the rotor
    • H02P2203/03—Determination of the rotor position, e.g. initial rotor position, during standstill or low speed operation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/64—Electric machine technologies in electromobility

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Control Of Motors That Do Not Use Commutators (AREA)

Abstract

The invention discloses a virtual inductor self-correcting permanent magnet motor current ripple spread spectrum control method and system, and belongs to the technical field of motors. According to the method, the three-phase current ripple peak value is taken as a control object according to a virtual inductance parameter set value, the switching frequency of the next switching period is updated through a three-phase current ripple spread spectrum control module, and a three-phase current ripple characteristic inflection point predicted value is calculated; obtaining a three-phase current ripple characteristic inflection point sampling value through sampling; inputting the sampling value and the predicted value of the characteristic inflection point of the three-phase ripple current into a virtual inductor self-correction module, and obtaining a virtual inductor correction value through decoupling function calculation and proportional-integral control; and updating the set value of the virtual inductance parameter according to the corrected value of the virtual inductance, thereby realizing the high-accuracy control of the three-phase current ripple peak value. The method comprehensively considers the self-inductance mutual inductance parameter of the motor, reduces the influence of inductance change on the current ripple prediction precision in the motor operation process, improves the control accuracy of the system, and realizes a better current ripple control effect.

Description

Virtual inductor self-correcting permanent magnet motor current ripple spread spectrum control method and system
Technical Field
The invention belongs to the technical field of motors, and particularly relates to a virtual inductor self-correcting permanent magnet motor current ripple spread spectrum control method and system.
Background
Among a plurality of motor types, the permanent magnet synchronous motor is widely applied to electric automobiles, fans, machine tools and the like due to the advantages of high efficiency, high power density, simplicity, reliability and the like. In recent years, due to the emergence and development of new technologies, new processes and new devices, the performance of the permanent magnet synchronous motor is further improved, and the application range of the permanent magnet synchronous motor is continuously widened.
In order to reduce the running loss of the permanent magnet motor and improve the safety and stability of the whole electromagnetic system, the state has the control requirement on current ripples of the control system. In order to achieve the requirement, the traditional system adopts a mode of increasing the switching frequency to reduce the current ripple, but the current ripple is far lower than the application requirement at some moments, so that additional switching loss is caused; meanwhile, the single switching frequency can cause the electromagnetic interference of the switching frequency to be intensified. According to the existing scheme of calculating the current ripple through given parameters so as to adjust the switching frequency, although a better control effect can be achieved when the parameters are accurate, in most cases, the actual system parameters deviate from the set values due to the fact that the voltage of a bus fluctuates, the inductance is saturated along with the temperature change or the current and internal power factor angle change of a magnetic circuit caused by load increase and load decrease is saturated. At this time, it is difficult to achieve the desired ripple control effect using such a control scheme, and the ripple control stability thereof cannot be ensured.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a permanent magnet motor current ripple spread spectrum control method and system based on virtual inductor self-correction, which establish a simplified model for predicting the current ripple of a permanent magnet motor, are used for simplifying the control difficulty on the basis of ensuring the control precision and establishing a virtual inductor self-correction model and aim to reduce the current ripple control error by taking a virtual inductor as a control object on the basis of the self-correction model.
In order to achieve the above object, in one aspect, the present invention provides a virtual inductor self-correcting current ripple spread spectrum control method for a permanent magnet motor, including the following steps:
(1) calculating a three-phase current change expression in the next switching period according to the set value of the virtual inductor;
(2) updating the switching frequency of the next switching period according to the expected value of the current ripple and the expression of the change rate of the three-phase current in the next switching period obtained in the step 1, and calculating a predicted value of the characteristic inflection point of the three-phase current ripple in the next switching period;
(3) sampling in the next switching period to obtain a sampling value of a three-phase current ripple characteristic inflection point, and obtaining a virtual inductance correction value according to the sampling value and the ripple prediction value of the three-phase current ripple characteristic inflection point obtained in the step (2); updating the expression of the three-phase current change rate in the step (1) according to the virtual inductance correction value;
(4) repeating the steps (1) - (3) to realize virtual inductance self-correction and current ripple spread spectrum control.
Further, the step (1) specifically includes:
simplifying the mathematical model of the permanent magnet motor, neglecting the resistance of the stator winding and neglecting the leakage self-inductance of the stator winding, then the average value M of the mutual inductance of the stator winding s0 Is the average value L of self-inductance of the stator winding s0 Half of the amplitude M of the mutual induction second harmonic of the stator winding s2 And stator winding self-inductance second harmonic amplitude L s2 Equal, i.e. M s0 ＝L s0 /2；M s2 ＝L s2 (ii) a Taking the moving back-emf caused by the permanent magnet flux linkage changes and the back-emf caused by the self-inductance and mutual inductance changes of the stator windings as the steady-state back-emfObtaining the relation between the duty ratio of the upper bridge arm switch and the steady-state back electromotive force according to a modulation principle;
according to the original inductance parameter L s0 、L s2 And real-time inductance parameter L s0 '、L s2 ' Definitions of virtual inductance L V1 、 L V2 ；
And obtaining a three-phase current change expression corresponding to different switching states in the next switching period according to the virtual inductance, the rotor position, the steady-state counter potential, the direct-current bus voltage and the upper bridge arm switching state column write current equation (KCL) and voltage equation (KVL).
Further, the step (3) specifically includes:
(3.1) sampling in the next switching period to obtain a sampling value of a three-phase current ripple characteristic inflection point;
(3.2) respectively obtaining feedback decoupling function values F through a virtual inductance decoupling function according to the three-phase current ripple characteristic inflection point sampling value obtained in the step (3.1) and the predicted value of the three-phase current ripple characteristic inflection point obtained in the step (2) v1m 、F v2m And predicted decoupling function value F v1c 、F v2c ；
(3.3) obtaining a feedback decoupling function value F in the step (3.2) v1m 、F v2m And predicted decoupling function value F v1c 、F v2c And (5) performing difference making, and obtaining a virtual inductance correction value through a proportional-integral controller. Updating a virtual inductance set value according to the virtual inductance correction value, and further updating the three-phase current change rate expression in the step (1);
and (3.4) repeating the steps (1) to (3) to finally stabilize the virtual inductor to a true value.
Further, the step (3.1) specifically includes:
sampling three-phase currents A, B and C when the upper bridge arm of each phase of the converter is switched in one switching period;
regarding the current fundamental wave in the switching period as linear change, and obtaining a fundamental wave current linear expression in the switching period through the three-phase current sampling value;
and (4) subtracting the sampling value of each three-phase current from the fundamental wave current value at the corresponding moment to obtain the sampling value of the ripple characteristic inflection point of the three-phase current.
Further, the step (3.2) specifically includes:
and obtaining a virtual inductance decoupling function according to the obtained relation between the three-phase current ripple and the virtual inductance, wherein the equation expression calculation result is positively correlated with the size of the virtual inductance.
Respectively taking the three-phase current ripple characteristic inflection point sampling value obtained in the step (3.1) and the three-phase current ripple characteristic inflection point predicted value obtained in the step (2) as input, and solving a feedback decoupling function value F through a virtual inductance decoupling function v1m 、F v2m And predicted decoupling function value F v1c 、F v2c 。
The output voltage of the inverter is step wave with switching frequency, the movement counter electromotive force of the motor is sine wave with electric cycle frequency, and the voltage difference value of the inverter and the motor is the counter electromotive force generated by the current fluctuation flowing through the three-phase coupling inductor. Through a simplified motor model, the self-inductance and mutual-inductance matrixes of the permanent magnet motor can be equivalently changed into a matrix containing L s0 、L s2 And the matrix of the rotor position can decouple the three-phase current according to the KCL and KVL equations to obtain an independent current change rate expression.
Based on the virtual inductance parameter self-correction technology, the switching period at the next moment can be obtained through conditions such as current ripple expected values and current change rate expressions, so that the spread spectrum control is performed on the inverter, the switching loss of a main circuit is effectively reduced, and the EMI noise peak value of a motor system is reduced.
The invention also provides a virtual inductance self-correcting permanent magnet motor current ripple spread spectrum control system, which comprises:
the controller is used for sending the upper bridge arm switch duty ratio of a k switch period to the three-phase current ripple spread spectrum control module in the k-1 switch period;
the three-phase current ripple spread spectrum control module is used for calculating a three-phase current change rate expression in a k switching period according to a virtual inductance set value in the k-1 switching period, calculating and changing the switching frequency of the k switching period according to a current ripple expected value, and sending a predicted value of a three-phase current ripple characteristic inflection point of the k switching period to the virtual inductance self-correction module;
the virtual inductor self-correction module is used for acquiring three-phase current sampling signals of a k switching period in the k switching period, calculating sampling values of three-phase current ripple characteristic inflection points of the k switching period, substituting the sampling values and three-phase current ripple characteristic inflection point prediction values into a virtual inductor decoupling function respectively, obtaining virtual inductor correction values through proportional-integral adjustment, sending the virtual inductor correction values to the three-phase current ripple spread spectrum control module, and correcting virtual inductor setting values used by the three-phase current ripple spread spectrum control module for regulating and controlling switching frequency of the k +2 switching period in the k +1 switching period to achieve a better current ripple spread spectrum control effect.
Furthermore, in the three-phase current ripple spread spectrum control module, the relationship between the duty ratio of the upper bridge arm switch and the steady-state back electromotive force is obtained according to a modulation principle by simplifying a mathematical model of the permanent magnet motor, neglecting the resistance of a stator winding, neglecting the leakage self-inductance of the stator winding and taking the movement back electromotive force caused by the flux linkage change of the permanent magnet and the back electromotive force caused by the self-inductance and mutual inductance change of the stator winding as the steady-state back electromotive force;
according to the original inductance parameter L s0 、L s2 And real-time inductance parameter L s0 '、L s2 ' Definitions of virtual inductance L V1 、 L V2 ；
And writing a current equation and a voltage equation according to the virtual inductor, the rotor position, the steady-state counter potential, the direct-current bus voltage and the upper bridge arm switching state column to obtain a three-phase current change rate expression corresponding to different switching states in the next switching period.
Further, k switches in the virtual inductor self-correction module are periodically sampled to obtain sampling values of three-phase current ripple characteristic inflection points, and feedback decoupling function values F are respectively obtained through a virtual inductor decoupling function and the predicted values of the three-phase current ripple characteristic inflection points v1m 、F v2m And predicted decoupling function value F v1c 、 F v2c (ii) a Decoupling the feedback by a function value F v1m 、F v2m And predicted decoupling function value F v1c 、F v2c And (4) performing subtraction, obtaining a virtual inductance correction value through a proportional-integral controller, updating a virtual inductance set value according to the virtual inductance correction value, and further updating the three-phase current change expression.
Furthermore, sampling values of the three-phase current ripple characteristic inflection points are obtained by sampling three-phase currents A, B and C in a k switching period when an upper bridge arm switch of each phase of the converter acts; regarding the current fundamental wave in the switching period as linear change, and obtaining a fundamental wave current linear expression of the switching period through a three-phase current sampling value; and (4) subtracting the sampling value of each three-phase current from the current value of the fundamental wave at the corresponding moment to obtain a sampling value of the characteristic inflection point of the current ripple.
Compared with the prior art, the technical scheme of the invention can achieve the following beneficial effects:
(1) the permanent magnet motor model used for calculating the current change rate expression is a reasonably simplified model, and a virtual inductance concept is provided, so that the current change rate expression has few use parameters in the calculation process, and is convenient for mathematical simplification and rule summarization.
(2) By introducing the virtual inductance self-correction technology, the invention can ensure the accuracy of the calculation of the current change rate expression by the virtual inductance self-correction under the condition that the motor parameters change, thereby ensuring the accuracy of the current ripple spread spectrum control.
(3) Due to the introduction of the virtual inductance self-correction technology, the method can reduce the requirement on the accuracy of the initial parameter setting of the motor model, make up for the initial parameter setting error through the virtual inductance self-correction, and ensure the accuracy of the current ripple spread spectrum control.
Drawings
FIG. 1 is a two-level permanent magnet motor circuit model;
FIG. 2 is a schematic diagram of an equivalent circuit of a two-level permanent magnet motor embodying the present invention;
FIG. 3 is a schematic diagram of single-phase current ripple prediction during a single switching cycle;
FIG. 4 is a schematic diagram of single phase current ripple measurement during a single switching cycle in accordance with an embodiment of the present invention;
FIG. 5 is a flow chart of virtual inductor self-calibration implemented in accordance with the present invention;
FIG. 6 is a block diagram of a virtual inductor self-correcting PMSM current ripple spread spectrum control implementation implemented in the present invention;
FIG. 7 is a control system operating diagram of an implementation of the present invention;
fig. 8 is a graph illustrating the effect of current ripple control according to a conventional current ripple control scheme under varying motor parameters;
fig. 9 is a diagram of the current ripple control effect of the virtual inductor self-correcting permanent magnet motor current ripple spread spectrum control scheme implemented according to the present invention under the condition of motor parameter variation.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
Aiming at the blank of the self-correcting technology in the application of current ripples, the invention establishes a two-level permanent magnet motor current ripple spread spectrum control model and a virtual inductor self-correcting model based on a virtual inductor concept, and adjusts the virtual inductor parameters used in the current ripple spread spectrum control based on the relation between a current ripple characteristic inflection point sampling value, a predicted value of the current ripple characteristic inflection point and the virtual inductor, so as to improve the accuracy of the current ripple spread spectrum regulation.
Compared with the traditional current ripple spread spectrum control technology, the current ripple spread spectrum control technology containing the virtual inductor self-positive has higher tolerance on the input error of the motor parameters, and has better current ripple spread spectrum regulation and control effect under the condition that the motor parameters change due to various reasons.
Therefore, the invention firstly provides the control application of the self-correction technology on the current ripple, and effectively improves the stability and reliability of the current ripple spread spectrum control.
As shown in fig. 1, the present invention is directed to the two-level permanent magnet machine described above, with three-phase windings coupled to each other due to mutual inductance. Wherein L is a 、L b 、L c Is three-phase self-inductance, M ab 、M bc 、M ac Is three-phase mutual inductance, V la 、V lb 、V lc Is back-emf, V, due to mutual and self-inductance variations fa 、V fb 、V fc Is the back emf due to rotor flux linkage changes. Simplifying the mathematical model of the permanent magnet motor, neglecting the resistance of the stator winding and neglecting the leakage self-inductance of the stator winding, then the average value M of the mutual inductance of the stator winding s0 Is the average value L of self-inductance of the stator winding s0 Half of the amplitude M of the mutual induction second harmonic of the stator winding s2 And stator winding self-inductance second harmonic amplitude L s2 Equal, i.e. M s0 ＝L s0 /2；M s2 ＝L s2 。
As shown in FIG. 2, V ad 、V bd 、V cd For phase output voltage, there are two voltage states (V) relative to the midpoint of the DC bus dc /2,-V dc /2) wherein V dc Is a DC bus voltage, V ab 、V bc 、V ca 、V ac 、 V ba 、V cb Is the voltage, V, generated by mutual inductive coupling of three-phase currents aj 、V bj 、V cj Is the equivalent steady state voltage.
Wherein, V aj 、V bj 、V cj Can be regarded as the sum of counter electromotive force generated by mutual inductance and self-inductance change and counter electromotive force and common mode counter electromotive force generated by rotor flux linkage change, V ki ＝(2*d i -1)*V dc 2; k is a, b, c, wherein d i Duty ratio of upper arm, V ab 、V bc 、V ca 、V ac 、V ba 、V cb Satisfies the following conditions:
V jk ＝-M jk *di j /dt；j,k＝a,b,c；j≠k；
by the equation:
i a +i b +i c ＝0，
L a *di a /dt＝V ad -V ba -V ca -V cj ，
L b *di b /dt＝V bd -V ab -V cb -V cj ，
L c *di c /dt＝V cd -V ac -V bc -V cj ，
the current change rate expressions of different voltage vector action sections in a single switching period can be calculated as follows (taking phase A as an example):
Figure BDA0003661796720000081
introducing a virtual inductance concept, and converting a current change rate expression into (taking the phase A as an example):
Figure BDA0003661796720000091
wherein i is 0, …, 7; j is a, b, c is the switching state and current phase number, L v1 、L v2 Is a virtual inductance, d a 、d b 、d c Is the duty ratio of an upper bridge arm of the three-phase switch,
Figure BDA0003661796720000092
the motor coefficient is always constant in the modulation system.
As shown in fig. 3, according to the current change rate expression and the duty ratio of the upper arm of the three-phase switch, the switching frequency at the next time is calculated according to the expected value of the current ripple: max (x) i ,y i )/i rippleref . Wherein x i ，y i Are respectively the different characteristic turning point values of three-phase current i rippleref Is the current ripple set point.
Through the steps, the switching frequency at the next moment can be calculated according to the existing parameters.
Secondly, based on the virtual inductance self-correction model, the current ripple can be still accurately controlled under the condition that the motor parameters are changed or the initial value is not accurately set.
As shown in fig. 4, in a switching period, sampling three-phase currents a, B, and C when the upper bridge arm switch of each phase of the converter is operated; taking the current fundamental wave in the switching period as linear change, and calculating to obtain a fundamental wave current linear expression in the switching period;
Figure BDA0003661796720000101
(the midpoint of the switching period is used as a time zero point), and the difference is made between the three-phase current sampling value and the fundamental wave current value to obtain the sampling value of the three-phase current ripple characteristic inflection point.
Sampling the sampled current ripple characteristic inflection point sampling value x am 、x bm And the calculated predicted value x of the inflection point of the current ripple characteristic ac 、x bc Substituting a virtual inductance decoupling function:
Figure BDA0003661796720000102
Figure BDA0003661796720000103
Figure BDA0003661796720000104
wherein x is a 、x b The current ripple values at the first inflection points of the phase current ripples of the phase a and the phase b are respectively. Respectively obtaining feedback decoupling function values F v1m 、F v2m And predicted decoupling function value F v1c 、F v2c In which V is dc Is a DC bus voltage, T 1 Is the switching period, theta is the rotor electrical angle, d a 、d b 、d c Is the duty ratio of the three-phase upper bridge arm. Decoupling function value F of feedback v1m 、F v2m And predicted decoupling function value F v1c 、F v2c And (5) performing difference making, and obtaining a virtual inductance correction value through proportional integral adjustment.
Through the above calculation method, the virtual inductance value can be corrected in real time, and a specific correction flow chart is shown in fig. 5.
Based on the virtual inductor self-correcting permanent magnet motor current ripple spread spectrum control model, the current ripple closed-loop control of the permanent magnet motor can be realized.
The controller is implemented as a block diagram shown in fig. 6, the duty ratio of the upper bridge arm switch is input into a three-phase current ripple spread spectrum control module, the three-phase current ripple spread spectrum control module takes a current ripple peak value as a control object, regulates and controls the switching frequency according to parameters such as a virtual inductor setting value and outputs a predicted value of a current ripple characteristic inflection point to a virtual inductor self-correction module, and the virtual inductor self-correction module calculates a virtual inductor correction value according to the current ripple characteristic inflection point predicted value and a sampled current ripple characteristic inflection point sampling value and outputs the virtual inductor correction value to the three-phase current ripple spread spectrum control module for correcting the virtual inductor setting value to form a closed loop.
The control system comprises a control core, a three-phase current ripple spread spectrum control module and a virtual inductance self-correction module, wherein a controller receives information such as three-phase current and rotor position in a k-1 switching period, the information of the duty ratio of an upper bridge arm switch and the rotor position is transmitted into the three-phase current ripple spread spectrum control module, the three-phase current ripple spread spectrum control module calculates a three-phase current change rate expression of each switching state section of the k switching period in the k-1 switching period based on the information and a virtual inductance set value, obtains switching frequency of the k switching period according to a current ripple expected value, transmits a predicted value of a current ripple characteristic inflection point of the k switching period into the virtual inductance self-correction module, the virtual inductance self-correction module samples the k switching period to obtain a current sampling signal of the k switching period, and calculates a sampling value of the three-phase current ripple characteristic inflection point of the k switching period, and substituting the predicted values and the three-phase current ripple characteristic inflection points into a virtual inductance decoupling function respectively, obtaining a virtual inductance correction value through proportional-integral adjustment, and sending the virtual inductance correction value to a three-phase current ripple spread spectrum control module for correcting a virtual inductance set value used by the three-phase current ripple spread spectrum modulation module for regulating and controlling the switching frequency of the k +2 switching period in the k +1 switching period, wherein the specific flow is shown in fig. 7.
As shown in fig. 8, the current ripple spread spectrum control effect of the conventional current ripple spread spectrum control scheme under the condition of the motor parameter variation is shown, wherein the per unit value is obtained relative to the current ripple set value. As shown in fig. 9, the control effect of the current ripple spread spectrum control scheme after adding the virtual inductor self-correction module is under the condition that the motor parameter changes, where a per unit value is obtained relative to the current ripple set value. After the virtual inductor self-correcting module is added, the current ripple control effect is obviously improved.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (10)

1. The virtual inductance self-correcting permanent magnet motor current ripple spread spectrum control method is characterized by comprising the following steps:
(1) calculating a three-phase current change expression in the next switching period according to the set value of the virtual inductor;
(2) updating the switching frequency of the next switching period according to the current ripple expected value and the expression of the three-phase current change rate in the next switching period obtained in the step (1), and calculating a predicted value of the characteristic inflection point of the three-phase current ripple in the next switching period;
(3) sampling in the next switching period to obtain a sampling value of the three-phase current ripple characteristic inflection point, and obtaining a virtual inductance correction value according to the sampling value and the predicted value of the three-phase current ripple characteristic inflection point obtained in the step (2); updating the set value of the virtual inductor according to the corrected value of the virtual inductor;
(4) and (4) repeating the steps (1) to (3), thereby realizing virtual inductance self-correction and current ripple spread spectrum control.
2. The virtual inductor self-correcting permanent magnet motor current ripple spread spectrum control method according to claim 1, wherein the step (1) specifically comprises:
simplifying a mathematical model of the permanent magnet motor, neglecting the resistance of a stator winding, neglecting the leakage self-inductance of the stator winding, taking the movement back-emf caused by the flux linkage change of a permanent magnet and the back-emf caused by the self-inductance and the mutual inductance change of the stator winding as steady-state back-emf, and obtaining the relation between the duty ratio of an upper bridge arm switch and the steady-state back-emf according to a modulation principle;
according to the original inductance parameter L s0 、L s2 And real-time inductance parameter L s0 '、L s2 ' Definitions of virtual inductance L V1 、L V2 ；
And writing a current equation and a voltage equation according to the virtual inductor, the rotor position, the steady-state counter potential, the direct-current bus voltage and the upper bridge arm switching state column to obtain three-phase current change rate expressions corresponding to different switching states in the next switching period.
3. The virtual inductor self-correcting permanent magnet motor current ripple spread spectrum control method according to claim 1, wherein the step (3) specifically comprises:
(3.1) sampling in the next switching period to obtain a sampling value of a three-phase current ripple characteristic inflection point;
(3.2) respectively obtaining feedback decoupling function values F through a virtual inductance decoupling function according to the sampling values of the three-phase current ripple characteristic inflection points obtained in the step (3.1) and the predicted values of the three-phase current ripple characteristic inflection points v1m 、F v2m And predicted decoupling function value F v1c 、F v2c ；
(3.3) obtaining a feedback decoupling function value F in the step (3.2) v1m 、F v2m And predicted decoupling function value F v1c 、F v2c And (3) performing subtraction, obtaining a virtual inductance correction value through a proportional-integral controller, and updating the expression of the three-phase current change rate in the step (1) according to the virtual inductance correction value.
4. The virtual inductor self-correcting permanent magnet motor current ripple spread spectrum control method according to claim 3, wherein the step (3.1) specifically comprises:
sampling ABC three-phase current when the upper bridge arm of each phase of the converter is switched in one switching period;
regarding the current fundamental wave in the switching period as linear change, and obtaining a fundamental wave current linear expression in the switching period through the three-phase current sampling value;
and (4) subtracting the sampling value of each three-phase current from the fundamental wave current value at the corresponding moment to obtain the sampling value of the ripple characteristic inflection point of the three-phase current.
5. The virtual inductor self-correcting permanent magnet motor current ripple spread spectrum control method according to claim 3, wherein the step (3.2) specifically comprises:
deducing a virtual inductance decoupling function according to the relation between the obtained three-phase current ripple and the virtual inductance;
respectively taking the sampling value of the three-phase current ripple characteristic inflection point and the predicted value of the three-phase current ripple characteristic inflection point as input, and solving a feedback decoupling function value F through a virtual inductance decoupling function v1m 、F v2m And predicted decoupling function value F v1c 、F v2c 。
6. The virtual inductance self-correcting permanent magnet motor current ripple spread spectrum control system is characterized by comprising a controller, a three-phase current ripple spread spectrum control module and a virtual inductance self-correcting module;
the controller is used for sending the duty ratio of the upper bridge arm switch in the k switching period to the three-phase current ripple spread spectrum control module in the k-1 switching period;
the three-phase current ripple spread spectrum control module is used for calculating a three-phase current change rate expression in a k switching period according to a virtual inductance set value in the k-1 switching period, calculating and changing the switching frequency of the k switching period according to a current ripple expected value, and sending a predicted value of a three-phase current ripple characteristic inflection point of the k switching period to the virtual inductance self-correction module;
the virtual inductor self-correction module is used for acquiring three-phase current sampling signals of the k switching period in the k switching period, calculating sampling values of three-phase current ripple characteristic inflection points of the k switching period, respectively substituting the sampling values and three-phase current ripple characteristic inflection point predicted values into a virtual inductor decoupling function, obtaining a virtual inductor correction value through proportional integral adjustment, and sending the virtual inductor correction value to the three-phase current ripple spread spectrum control module to update a virtual inductor set value, so that current ripple spread spectrum control is realized.
7. The virtual inductance self-correcting permanent magnet motor current ripple spread spectrum control system according to claim 6, wherein a relation between an upper bridge arm switch duty ratio and a steady-state back electromotive force is obtained according to a modulation principle by simplifying a mathematical model of a permanent magnet motor, neglecting stator winding resistance, neglecting stator winding leakage self-inductance, and taking a moving back electromotive force caused by permanent magnet flux linkage change and a back electromotive force caused by self-inductance and mutual inductance change of a stator winding as the steady-state back electromotive force in the three-phase current ripple spread spectrum control module;
according to the original inductance parameter L s0 、L s2 And real-time inductance parameter L s0 '、L s2 ' Definitions of virtual inductance L V1 、L V2 ；
And writing a current equation and a voltage equation according to the virtual inductor, the rotor position, the steady-state counter potential, the direct-current bus voltage and the upper bridge arm switching state column to obtain three-phase current change rate expressions corresponding to different switching states in the next switching period.
8. The virtual inductor self-correcting permanent magnet motor current ripple spread spectrum control system of claim 6, wherein k switch cycles in the virtual inductor self-correcting module are sampled to obtain sampling values of three-phase current ripple characteristic inflection points, and feedback decoupling function values F are respectively obtained through a virtual inductor decoupling function and the predicted values of the three-phase current ripple characteristic inflection points v1m 、F v2m And predicted decoupling function value F v1c 、F v2c (ii) a Decoupling the feedback by a function value F v1m 、F v2m And predicted decoupling function value F v1c 、F v2c And performing subtraction, obtaining a virtual inductance correction value through a proportional-integral controller, sending the virtual inductance correction value to a three-phase current ripple spread spectrum control module, and further using the three-phase current ripple spread spectrum control moduleAnd setting a new virtual inductance value, and further calculating a three-phase current change expression.
9. The virtual inductor self-correcting permanent magnet motor current ripple spread spectrum control system of claim 8, wherein the sampling value of the three-phase current ripple characteristic inflection point is obtained by sampling three-phase currents of A, B and C during switching actions of an upper bridge arm of each phase of the converter in a k switching period; regarding the current fundamental wave in the switching period as linear change, and obtaining a fundamental wave current linear expression in the switching period through a three-phase current sampling value; and (4) subtracting the three-phase current sampling value from the fundamental wave current value at the corresponding moment to obtain a sampling value of the three-phase current ripple characteristic inflection point.
10. The virtual inductor self-correcting permanent magnet motor current ripple spread spectrum control system of claim 6, wherein the virtual inductor self-correcting module is used to regulate the switching frequency of the k +2 switching period at the k +1 switching period through the three-phase current ripple spread spectrum control module at the virtual inductor set value corrected at the k switching period.
CN202210579543.8A 2022-05-25 2022-05-25 Virtual inductor self-correcting permanent magnet motor current ripple spread spectrum control method and system Pending CN114865980A (en)

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