CN116247989A - Permanent magnet synchronous motor two-phase four-switch fault-tolerant control method based on MPC - Google Patents

Permanent magnet synchronous motor two-phase four-switch fault-tolerant control method based on MPC Download PDF

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CN116247989A
CN116247989A CN202310171758.0A CN202310171758A CN116247989A CN 116247989 A CN116247989 A CN 116247989A CN 202310171758 A CN202310171758 A CN 202310171758A CN 116247989 A CN116247989 A CN 116247989A
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motor
phase
permanent magnet
magnet synchronous
stator
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张迪
周符
张金龙
魏艳君
漆汉宏
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Yanshan University
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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
    • H02P21/0003—Control strategies in general, e.g. linear type, e.g. P, PI, PID, using robust control
    • 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
    • H02P21/14—Estimation or adaptation of machine parameters, e.g. flux, current or voltage
    • H02P21/141—Flux 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
    • 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
    • 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
    • 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

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Abstract

The invention discloses a permanent magnet synchronous motor two-phase four-switch fault-tolerant control method based on MPC. The control system adopts a double-ring structure, the outer ring controls the rotating speed of the motor through the PI regulator, and the maximum torque current ratio is combined to provide torque and flux linkage reference values for the inner ring; the inner ring adopts model prediction direct torque control, and a stator voltage equation and a stator current prediction model are utilized to obtain a flux linkage and a torque predicted value; and obtaining the optimal switching state of the inverter by using the cost function, and controlling the rest switching tubes to realize fault-tolerant operation of the motor. The invention can still enable the system to stably operate after the switching tube fails, does not need to switch control strategies, and effectively improves the safety and reliability of the operation of the permanent magnet synchronous motor.

Description

Permanent magnet synchronous motor two-phase four-switch fault-tolerant control method based on MPC
Technical Field
The invention relates to a permanent magnet synchronous motor two-phase four-switch fault-tolerant control method based on MPC, and belongs to the technical field of permanent magnet synchronous motor control.
Background
In recent years, permanent magnet synchronous motors are widely applied to new energy automobile driving systems, and excellent control performance is a basis for realizing stable operation of electric automobiles. The inverter is a core component of the motor driving system of the electric automobile, once the motor driving system fails, the serious consequences such as power failure and the like of the whole automobile are caused, driving safety is endangered, and the fault-tolerant control technology of the inverter can effectively improve the operation reliability of the motor driving system and improve the safety of the automobile.
The common topology structures of the fault-tolerant inverter mainly comprise a three-phase four-bridge arm fault-tolerant topology, a three-phase four-switch Guan Rongcuo topology and a two-phase four-switch Guan Rongcuo topology. The different fault-tolerant topologies have different characteristics, the three-phase four-bridge arm fault-tolerant topology is characterized in that 1 redundant bridge arm is added on the basis of the original bridge arm, the utilization rate of voltage vectors is high, the fault problem can be effectively solved, but the number and the cost of switching devices of the inverter are obviously increased; compared with the four-bridge arm topology, the three-phase four-bridge Guan Rongcuo topology has the advantages of small volume and low cost, but the effective value of the voltage vector is only half of that of the inverter when the inverter works normally, the selectable voltage vector is few, the output torque pulsation is large, and meanwhile, the topology can only fault-tolerant single-phase faults of the inverter, so that the application range of the inverter is limited; the two-phase four-switch Guan Rongcuo inverter is characterized in that a neutral point of a motor is connected to a midpoint of a direct-current power supply by directly discarding fault phases, so that single-phase faults of the inverter can be fault-tolerant, single-phase faults of the motor can be fault-tolerant, the fault-tolerant topology structure is simple, the number of required additional devices is small, the cost is low, the size is small, and the inverter has larger advantages.
In the aspect of control technology, the traditional permanent magnet synchronous motor control technology based on vector control has complex parameter calculation and slow dynamic response speed, and can not meet the demands of people. In recent years, students at home and abroad have made a great deal of researches on the operation state of the motor system in a normal working state, and few researches on the operation state of the system under the condition of inverter faults are carried out by proposing novel control schemes such as model predictive control, fuzzy control, sliding mode control and the like. Particularly, the permanent magnet synchronous motor control technology based on model predictive control utilizes a cost function to select an optimal voltage vector, has the advantages of small torque pulsation, high dynamic response speed and the like, can effectively improve the dynamic response speed of motor control, and becomes a hot spot for research in the aspect of motor drive control technology at present.
Disclosure of Invention
In order to solve the technical problems, the invention provides a permanent magnet synchronous motor two-phase four-switch fault-tolerant control method based on MPC, which combines fault-tolerant topology reconstruction with a model prediction direct torque control strategy, so that the system has certain fault-tolerant capability and good steady-state and dynamic performance.
The technical scheme adopted by the invention is as follows:
a permanent magnet synchronous motor two-phase four-switch fault-tolerant control method based on MPC comprises the following steps:
(1) When a certain phase of switching tube of the inverter fails, a failure bridge arm is disconnected, a motor neutral point is connected to a direct-current power supply midpoint, and the inverter is reconfigured into a two-phase four-switch fault-tolerant operation topology.
(2) Three-phase stator current i of permanent magnet synchronous motor is collected by current Hall sensor a 、i b 、i c Calculating and obtaining an electric angle theta and an actual rotating speed n of a motor rotor by utilizing a photoelectric encoder; according to the electric angle theta of the motor rotor, three-phase stator current i a 、i b 、i c After the rotation coordinate transformation, the dq axis current component i under the two-phase synchronous rotation coordinate system is obtained d 、i q ；
(3) Rotating speed outer ring design based on PI regulator, and motor realityRotational speed n and given rotational speed n * Difference is made, and an electromagnetic torque reference value T is obtained through a PI controller e * The method comprises the steps of carrying out a first treatment on the surface of the According to the electromagnetic torque reference value T e * Obtaining a stator flux linkage reference value |ψ by a maximum torque current ratio control method s * |；
(4) Discretizing a mathematical model of the permanent magnet synchronous motor under a two-phase synchronous rotation coordinate system, and obtaining a predicted value of the stator current at the moment (k+1) according to a differential equation of the stator current;
(5) Respectively constructing a stator flux linkage and an electromagnetic torque prediction model according to the relation among the stator flux linkage, the electromagnetic torque and the stator current, and obtaining a stator flux linkage predicted value and an electromagnetic torque predicted value of the motor at the moment (k+1) by utilizing the predicted value of the stator current at the moment (k+1) in the step (4);
(6) The inner ring adopts a model prediction direct torque control strategy, a cost function is constructed by utilizing a reference value and a predicted value of electromagnetic torque and stator flux linkage, the optimal switching state of the inverter is obtained through the cost function, and the inverter controls the action of a switching tube according to the optimal switching state, so that fault tolerant operation of the permanent magnet synchronous motor is realized.
The technical scheme of the invention is further improved as follows: in the step (1), the neutral point of the permanent magnet synchronous motor needs to be led out, the DC side of the inverter is connected with two capacitors in series, and the middle tap of the two capacitors is used as the midpoint of a DC power supply and is connected with the neutral point of the permanent magnet synchronous motor through a bidirectional thyristor. When detecting that a certain phase switching tube of the inverter has faults, the phase bridge arm is disconnected from the motor, meanwhile, the bidirectional thyristor is closed, the neutral point of the motor is connected to the midpoint of the direct-current power supply, and the inverter is reconfigured into a fault-tolerant operation topology of two-phase four-switch by using the residual switching tube.
The technical scheme of the invention is further improved as follows: in the step (3), the electromagnetic torque reference value T e * The acquisition formula of (1) is:
Figure BDA0004099581390000031
k in p And k i Proportional gain and integral gain in the PI controller, respectively;
the maximum torque current ratio control method is used for obtaining the stator flux linkage reference value |ψ s * I, the formula is as follows:
Figure BDA0004099581390000032
in which L s The stator inductor has the expression:
Figure BDA0004099581390000033
p n as pole pair number of permanent magnet synchronous motor, ψ f Is a permanent magnet flux linkage.
The technical scheme of the invention is further improved as follows: in the step (4), after the mathematical model of the permanent magnet synchronous motor is discretized, the obtained stator current differential equation is shown as the following formula:
Figure BDA0004099581390000034
in the above, U d (k) And U q (k) The components of the reference voltage vector applied to the motor by the inverter at the moment k are respectively the d-axis and q-axis components in a two-phase synchronous rotation coordinate system, i d (k) And i q (k) Respectively the components of the stator current of the motor at the moment k, namely the d axis and the q axis under a two-phase synchronous rotation coordinate system, L d And L q The components of the equivalent inductance of the stator winding in the d axis and the q axis are respectively, R is the resistance of the stator winding of the motor, omega e For the electrical angular velocity of the motor rotor, T s Sampling time;
stator current predicted value i of motor at (k+1) d (k+1) and i q (k+1) can be obtained by the above formula.
The technical scheme of the invention is further improved as follows: in the step (5), according to the relation between the stator flux linkage and the stator current in the motor model, a stator flux linkage prediction model can be constructed as follows:
Figure BDA0004099581390000041
substituting the predicted value of the stator current at the moment (k+1) into the above formula to obtain the predicted value |ψ of the stator flux linkage at the moment (k+1) s (k+1)|；
Similarly, an electromagnetic torque predictive model may be constructed as follows:
Figure BDA0004099581390000042
electromagnetic torque predictive value T of motor at (k+1) e (k+1) can be obtained by the above formula.
The technical scheme of the invention is further improved as follows: in the step (6), a cost function is constructed by the reference value and the predicted value of the electromagnetic torque and the stator flux linkage, and the cost function is shown in the following formula:
Figure BDA0004099581390000043
in the fault-tolerant running state of the system, as only two bridge arms and four switching tubes of the inverter are left for controlling the motor, the switching states are only four; based on a model predictive control strategy, the predictive values of the electromagnetic torque and the stator flux linkage at the moment (k+1) under four different switch states can be obtained; the switching state which enables the cost function J to be minimum is selected as the optimal switching state of the inverter, and the inverter controls the switching tube to act according to the optimal switching state, so that fault-tolerant operation of the permanent magnet synchronous motor can be realized.
By adopting the technical scheme, the invention has the following technical progress:
the invention combines the three-phase four-switch inverter with the permanent magnet synchronous motor with the neutral point, and can realize the switching from the normal running state to the fault-tolerant running state by only one extra fast bidirectional thyristor, and has simple structure. The electromagnetic torque and stator flux linkage of the motor are used as control variables, the stator current is used as an intermediate variable, model prediction torque control is adopted, the optimal vector is directly selected by a cost function, and the system response is rapid. The model predictive control can effectively inhibit electromagnetic torque pulsation, so that the motor can run more stably, and the reliability and fault-tolerant running capacity of a motor driving system are improved.
Drawings
FIG. 1 is a block diagram of a model predictive torque control for a permanent magnet synchronous motor system with a neutral point driven by a two-phase four-switch fault tolerant inverter;
FIG. 2 is a fault tolerant control flow diagram;
FIG. 3 is a schematic diagram of an open circuit of a switching tube;
FIG. 4 is a schematic diagram of a two-phase four-switch fault-tolerant reconstruction;
FIG. 5 is a graph of the correspondence between the output voltage vector of the inverter and the switching state quantity in a fault state;
FIG. 6 is a waveform diagram of rotational speed of a motor output under a fault tolerant control system;
fig. 7 is a torque waveform diagram of motor output under a fault tolerant control system.
Detailed Description
The invention is further illustrated by the following examples:
the invention relates to a permanent magnet synchronous motor two-phase four-switch fault-tolerant control method based on MPC, which is a permanent magnet synchronous motor two-phase four-switch fault-tolerant direct torque control method based on model predictive control, and a specific control block diagram is shown in figure 1. When an open-circuit fault occurs in the switching tube of the inverter, firstly cutting off the connection between a motor port and a fault bridge arm of the inverter, connecting a motor neutral point to a power supply midpoint, and carrying out fault-tolerant reconstruction on the system topology through the rest switching tube; the controller outer ring is a rotating speed ring designed based on a PI regulator, a given torque is output through the PI regulator, and a reference stator flux linkage is given by maximum torque current ratio control (MTPA). The inner ring adopts a model prediction direct torque control strategy, and based on a stator voltage equation and a stator current prediction model, a stator flux linkage and an electromagnetic torque predicted value are obtained; and obtaining the optimal switching state of the inverter by using the cost function, and controlling the rest switching tubes to realize fault-tolerant operation of the motor, wherein a control flow chart of the control flow chart is shown in figure 2. The system can still ensure the safe and stable operation of the system under the condition of the fault of the switch tube, so that the system can maintain good steady state and dynamic performance.
According to the invention, the neutral point of the permanent magnet synchronous motor needs to be led out, the DC side of the inverter is connected with two capacitors in series, and the middle tap of the two capacitors is used as the midpoint of a DC power supply and is connected with the neutral point of the permanent magnet synchronous motor through a bidirectional thyristor. When an open circuit failure occurs in a certain phase switching tube of the inverter, for example, an open circuit failure occurs in an a-phase switching tube S1 of the inverter, as shown in fig. 3. The connection between the motor port and the inverter fault bridge arm is cut off, meanwhile, the bidirectional thyristor is closed, the motor neutral point is connected to the power supply midpoint, and the inverter is reconfigured into a fault-tolerant operation topology of two-phase four-switch by using the residual switching tube, as shown in fig. 4.
Three-phase stator current i of permanent magnet synchronous motor a 、i b 、i c The electric angle theta and the actual rotating speed n of the motor rotor are acquired by a current Hall sensor and are obtained by calculation by a photoelectric encoder; according to the electric angle value of the motor rotor, the three-phase stator current is transformed by the rotation coordinate to obtain the dq-axis current component i under the two-phase synchronous rotation coordinate system d 、i q 。
The controller outer ring is a rotating speed ring designed based on a PI regulator, a given torque is output through the PI regulator, and a reference stator flux linkage is given by maximum torque current ratio control (MTPA). The actual rotation speed n and the given reference rotation speed n * Difference is made, and a reference torque value T is obtained through a PI regulator e * The formula is as follows:
Figure BDA0004099581390000061
k in p And k i Proportional gain and integral gain in the PI controller, respectively.
The maximum torque current ratio control method is used for obtaining the stator flux linkage reference value |ψ s * I, the formula is as follows:
Figure BDA0004099581390000062
in which L s The stator inductor has the expression:
Figure BDA0004099581390000063
p n as pole pair number of permanent magnet synchronous motor, ψ f Is a permanent magnet flux linkage.
Discretizing a mathematical model of the permanent magnet synchronous motor under a two-phase synchronous rotation coordinate system, and obtaining a predicted value of the stator current at the moment (k+1) according to a differential equation of the stator current, wherein the predicted value is shown in the following formula:
Figure BDA0004099581390000071
in the above, U d (k) And U q (k) The components of the reference voltage vector applied to the motor by the inverter at the moment k are respectively the d-axis and q-axis components in a two-phase synchronous rotation coordinate system, i d (k) And i q (k) Respectively the components of the stator current of the motor at the moment k, namely the d axis and the q axis under a two-phase synchronous rotation coordinate system, L d And L q The components of the equivalent inductance of the stator winding in the d axis and the q axis are respectively, R is the resistance of the stator winding of the motor, omega e For the electrical angular velocity of the motor rotor, T s Is the sampling time.
Stator current predicted value i of motor at (k+1) d (k+1) and i q (k+1) can be obtained by the above formula.
And (3) respectively constructing a stator flux linkage and an electromagnetic torque prediction model according to the relation among the stator flux linkage, the electromagnetic torque and the stator current, and obtaining a stator flux linkage predicted value and an electromagnetic torque predicted value of the motor at the moment (k+1) by utilizing the predicted value of the stator current at the moment (k+1) in the step (4).
According to the relation between the stator flux linkage and the stator current in the motor model, a stator flux linkage prediction model can be constructed as follows:
Figure BDA0004099581390000072
substituting the predicted value of the stator current at the moment (k+1) into the above formula to obtain the predicted value |ψ of the stator flux linkage at the moment (k+1) s (k+1)|；
Similarly, an electromagnetic torque predictive model may be constructed as follows:
Figure BDA0004099581390000073
electromagnetic torque predictive value T of motor at (k+1) e (k+1) can be obtained by the above formula.
The controller inner ring adopts a model predictive direct torque control strategy, and a cost function is constructed by utilizing a reference value and a predictive value of electromagnetic torque and stator flux linkage, wherein the cost function is shown in the following formula:
Figure BDA0004099581390000081
and selecting the optimal voltage vector at the next moment by solving the minimum value of the cost function, and then outputting the switching state corresponding to the optimal voltage vector to control the residual switching tube so as to achieve the fault-tolerant operation purpose.
In the fault-tolerant running state of the system, as the inverter only has two bridge arms and four switching tubes to control the motor, the switching states are only four, and the switching state combination method and the corresponding voltage vector in the fault-tolerant running state are as follows:
assuming a phase a bridge arm switching tube failure, the fuse is blown out quickly to isolate the phase a bridge arm, and the switching state is combined with M because the inverter only has four switching tubes to control the motor 0 (0,0)，M 1 (0,1)，M 2 (1,0)，M 3 Four types of (1, 1) are shown in fig. 5, wherein numerals in brackets indicate states of switching tubes of a B-phase bridge arm and a C-phase bridge arm, wherein "1" indicates that an upper switching tube of the same bridge arm is in an on state, and a lower switching tube is in an off state, and "0" indicates that upper and lower switching tubes of the same bridge arm are in an off state opposite to "1". When the inverter has a fault of the A-phase switching tube, the A-phase is processedAfter bridge arms are isolated, the bidirectional thyristors TR are simultaneously connected, so that the neutral point N of the permanent magnet synchronous motor is connected to the midpoint of the direct-current side capacitor, and a new topology of the motor control system in a fault state is constructed. Three-phase voltage U output by inverter AN 、U BN 、U CN The expression of (2) is shown as formula (7), wherein U DC Is a direct current source voltage.
Figure BDA0004099581390000082
Transforming the phase voltage under the three-phase static coordinate system into the voltage under the two-phase static coordinate system alpha, beta, and obtaining the voltage expression as follows:
Figure BDA0004099581390000083
similarly, under the other switching states, the phase voltages under the three-phase coordinate system are converted into the voltages under the static coordinate system, and the corresponding relation between the switching states and the voltage vectors of the three-phase four-switch inverter are shown in table 1:
TABLE 1 switch state and voltage vector under fault tolerant control during phase A failure
Figure BDA0004099581390000091
The model prediction direct torque control strategy is adopted, so that predicted values of electromagnetic torque and stator flux linkage at the moment (k+1) in the four different switch states can be obtained; the switching state which minimizes the cost function J in the formula (6) is selected as the optimal switching state of the inverter, and the inverter controls the switching tube to act according to the optimal switching state, so that fault-tolerant operation of the permanent magnet synchronous motor can be realized.
In order to illustrate the two-phase four-switch fault-tolerant control method of the permanent magnet synchronous motor based on MPC, the stable operation of the inverter under open-circuit faults can be realized on the basis of keeping the normal operation of the system, the fault-tolerant operation capacity of the system is improved, simulation verification is carried out on the proposed fault-tolerant control method on MATLAB/Simulink software, and the simulation result is given and analyzed in detail.
The parameters of the permanent magnet synchronous motor used in simulation are as follows: rated voltage U N =220V, ac-dc axis inductance L d ＝L q ＝5.25×10 -3 H, pole pair number p n =4, stator resistance R s Permanent magnet flux linkage ψ=1.2Ω f 0.0796Wb, moment of inertia J=0.0027 kg.m 2 . The sampling period is 25ms.
When simulation starts, the given rotating speed is 600r/min, the input torque is 2 N.m, the inner ring adopts direct torque control based on model prediction, each switching tube of the inverter normally operates, the phase A switching tube fails in 0.2s, the control system disconnects the phase A bridge arm, and meanwhile, the neutral point of the motor is connected with the midpoint of the direct current power supply, so that the system continues to operate in a two-phase four-switch Guan Rongcuo mode.
Fig. 6 is a waveform diagram of the rotational speed of the motor output when switching from the normal state to the fault tolerant operation mode after a failure of the a-phase switching tube. At 0s, the rotating speed is set to 600r/min, and the rotating speed of the motor rises to the set value at 0.07s, so that the motor reaches a stable state. When t=0.2 s, the system fails to switch to a fault-tolerant operation mode, the motor rotation speed can well follow the given operation, and the system can quickly reach a stable state after the failure; as can be seen from the enlarged graph, the rotating speed pulsation is increased to 0.6r/min in the fault-tolerant running mode, and compared with the normal mode, the rotating speed pulsation is slightly increased, and the stable performance can still be kept better.
Fig. 7 is a waveform diagram of electromagnetic torque output by the motor when switching from the normal state to the fault tolerant operation mode after a phase a switching tube failure. At 0s, the given torque is 2n.m, and the system reaches steady state at 0.07s after start-up. When t=0.2 s, the phase A fault enters a fault-tolerant running mode, the torque pulsation output by the motor is increased to 0.3 N.m from the original 0.1 N.m, the waveform has no obvious jump type fluctuation, the electromagnetic torque can quickly enter a stable state, and the electromagnetic torque keeps good steady state and dynamic performance.
From the above, it can be known that: according to the MPC-based two-phase four-switch fault-tolerant control method for the permanent magnet synchronous motor, provided by the invention, under the condition of the fault of the switching tube of the inverter, good steady state and dynamic performance can be kept, so that the system has certain fault-tolerant operation capability, and the stability and robustness of the system are improved.
The above examples are only preferred embodiments of the present invention and are described in detail, not as a limitation of the technical method, it should be noted that: it will be apparent to those skilled in the art that various modifications and equivalent substitutions can be made without departing from the basic principles of the invention, and these modifications should also be considered as being within the scope of the invention.

Claims (6)

1. A permanent magnet synchronous motor two-phase four-switch fault-tolerant control method based on MPC is characterized in that: the method comprises the following steps:
(1) When a certain phase of switching tube of the inverter fails, a failure bridge arm is disconnected, a motor neutral point is connected to a direct-current power supply midpoint, and the inverter is reconfigured into a two-phase four-switch fault-tolerant operation topology;
(2) Three-phase stator current i of permanent magnet synchronous motor is collected by current Hall sensor a 、i b 、i c Calculating and obtaining an electric angle theta and an actual rotating speed n of a motor rotor by utilizing a photoelectric encoder; according to the electric angle theta of the motor rotor, three-phase stator current i a 、i b 、i c After the rotation coordinate transformation, the dq axis current component i under the two-phase synchronous rotation coordinate system is obtained d 、i q ；
(3) Based on the design of a rotating speed outer ring of the PI regulator, the actual rotating speed n of the motor and the given rotating speed n * Difference is made, and an electromagnetic torque reference value T is obtained through a PI controller e * The method comprises the steps of carrying out a first treatment on the surface of the According to the electromagnetic torque reference value T e * Obtaining a stator flux linkage reference value |ψ by a maximum torque current ratio control method s * |；
(4) Discretizing a mathematical model of the permanent magnet synchronous motor under a two-phase synchronous rotation coordinate system, and obtaining a predicted value of the stator current at the moment (k+1) according to a differential equation of the stator current;
(5) Respectively constructing a stator flux linkage and an electromagnetic torque prediction model according to the relation among the stator flux linkage, the electromagnetic torque and the stator current, and obtaining a stator flux linkage predicted value and an electromagnetic torque predicted value of the motor at the moment (k+1) by utilizing the predicted value of the stator current at the moment (k+1) in the step (4);
(6) The inner ring adopts a model prediction direct torque control strategy, a cost function is constructed by utilizing a reference value and a predicted value of electromagnetic torque and stator flux linkage, the optimal switching state of the inverter is obtained through the cost function, and the inverter controls the action of a switching tube according to the optimal switching state, so that fault tolerant operation of the permanent magnet synchronous motor is realized.
2. The MPC-based two-phase four-switch fault-tolerant control method for the permanent magnet synchronous motor, according to claim 1, is characterized in that: in the step (1), a neutral point of the permanent magnet synchronous motor needs to be led out, two capacitors are connected in series to the DC side of the inverter, and the middle taps of the two capacitors are used as the midpoint of a DC power supply and are connected with the neutral point of the permanent magnet synchronous motor through a bidirectional thyristor; when detecting that a certain phase switching tube of the inverter has faults, the phase bridge arm is disconnected from the motor, meanwhile, the bidirectional thyristor is closed, the neutral point of the motor is connected to the midpoint of the direct-current power supply, and the inverter is reconfigured into a fault-tolerant operation topology of two-phase four-switch by using the residual switching tube.
3. The MPC-based two-phase four-switch fault-tolerant control method for the permanent magnet synchronous motor, according to claim 1, is characterized in that: in the step (3), the electromagnetic torque reference value T e * The acquisition formula of (1) is:
Figure FDA0004099581370000021
k in p And k i Proportional gain and integral gain in the PI controller, respectively;
the maximum torque current ratio control method is used for obtaining the stator flux linkage reference value |ψ s * I, the formula is as follows:
Figure FDA0004099581370000022
in which L s The stator inductor has the expression:
Figure FDA0004099581370000023
p n as pole pair number of permanent magnet synchronous motor, ψ f Is a permanent magnet flux linkage.
4. The MPC-based two-phase four-switch fault-tolerant control method for the permanent magnet synchronous motor, according to claim 1, is characterized in that: in the step (4), after the mathematical model of the permanent magnet synchronous motor is discretized, the obtained stator current differential equation is shown as the following formula:
Figure FDA0004099581370000024
in the above, U d (k) And U q (k) The components of the reference voltage vector applied to the motor by the inverter at the moment k are respectively the d-axis and q-axis components in a two-phase synchronous rotation coordinate system, i d (k) And i q (k) Respectively the components of the stator current of the motor at the moment k, namely the d axis and the q axis under a two-phase synchronous rotation coordinate system, L d And L q The components of the equivalent inductance of the stator winding in the d axis and the q axis are respectively, R is the resistance of the stator winding of the motor, omega e For the electrical angular velocity of the motor rotor, T s Sampling time;
stator current predicted value i of motor at (k+1) d (k+1) and i q (k+1) can be obtained by the above formula.
5. The MPC-based two-phase four-switch fault-tolerant control method for the permanent magnet synchronous motor, according to claim 1, is characterized in that: in the step (5), according to the relation between the stator flux linkage and the stator current in the motor model, a stator flux linkage prediction model can be constructed as follows:
Figure FDA0004099581370000031
substituting the predicted value of the stator current at the moment (k+1) into the above formula to obtain the predicted value |ψ of the stator flux linkage at the moment (k+1) s (k+1)|；
Similarly, an electromagnetic torque predictive model may be constructed as follows:
Figure FDA0004099581370000032
electromagnetic torque predictive value T of motor at (k+1) e (k+1) can be obtained by the above formula.
6. The MPC-based two-phase four-switch fault-tolerant control method for the permanent magnet synchronous motor, according to claim 1, is characterized in that: in the step (6), a cost function is constructed by the reference value and the predicted value of the electromagnetic torque and the stator flux linkage, and the cost function is shown in the following formula:
Figure FDA0004099581370000033
in the fault-tolerant running state of the system, as only two bridge arms and four switching tubes of the inverter are left for controlling the motor, the switching states are only four; based on a model predictive control strategy, the predictive values of the electromagnetic torque and the stator flux linkage at the moment (k+1) under four different switch states can be obtained; the switching state which enables the cost function J to be minimum is selected as the optimal switching state of the inverter, and the inverter controls the switching tube to act according to the optimal switching state, so that fault-tolerant operation of the permanent magnet synchronous motor can be realized.
CN202310171758.0A 2023-02-27 2023-02-27 Permanent magnet synchronous motor two-phase four-switch fault-tolerant control method based on MPC Pending CN116247989A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117375465A (en) * 2023-10-13 2024-01-09 哈尔滨工业大学（威海） Busbar boosting control method for neutral point power supply permanent magnet synchronous motor

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117375465A (en) * 2023-10-13 2024-01-09 哈尔滨工业大学（威海） Busbar boosting control method for neutral point power supply permanent magnet synchronous motor
CN117375465B (en) * 2023-10-13 2024-06-11 哈尔滨工业大学（威海） Busbar boosting control method for neutral point power supply permanent magnet synchronous motor

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