CN115173770A - Control method and control system of permanent magnet synchronous motor for vehicle - Google Patents

Control method and control system of permanent magnet synchronous motor for vehicle Download PDF

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Publication number
CN115173770A
CN115173770A CN202210521812.5A CN202210521812A CN115173770A CN 115173770 A CN115173770 A CN 115173770A CN 202210521812 A CN202210521812 A CN 202210521812A CN 115173770 A CN115173770 A CN 115173770A
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motor
control
current
unit
voltage
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徐泽绪
李帅
李岩
范雨卉
董力嘉
李伟亮
刘亚川
冉再庆
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FAW Group Corp
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FAW Group Corp
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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
    • H02P21/22—Current control, e.g. using a current control loop
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L15/00—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles
    • B60L15/20—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
    • 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
    • H02P21/0003—Control strategies in general, e.g. linear type, e.g. P, PI, PID, using robust control
    • H02P21/0017—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
    • 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
    • H02P21/0021—Control strategies in general, e.g. linear type, e.g. P, PI, PID, using robust control using different modes of control depending on a parameter, e.g. the speed
    • 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
    • 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
    • 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
    • H02P27/12—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 pulsing by guiding the flux vector, current vector or voltage vector on a circle or a closed curve, e.g. for direct torque 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
    • 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
    • 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
    • Y02T10/72—Electric energy management in electromobility

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Control Of Ac Motors In General (AREA)

Abstract

The invention provides a control method and a control system of a permanent magnet synchronous motor for a vehicle. The torque control unit converts a torque command input by the whole vehicle control unit into a corresponding stator current command; the control mode enabling unit has the function of selecting and switching a corresponding control mode according to the current rotating speed of the motor, and when the rotating speed of the motor is lower than a basic speed point, the unit enables the MPC control mode; when the rotating speed of the motor is higher than a base speed point, the unit enables a PID control mode; the SVPWM modulation unit takes the phase voltage vector calculated by the MPC or PID unit as input, calculates the actual conduction sequence and conduction time of the inverter power tube corresponding to the target voltage, generates 6 paths of PWM low-voltage modulation signals and controls the on-off of the 6 paths of power tubes in the inverter; and the motor controller switches on and off a power switch tube of the inverter according to a certain rule under the modulation action of the SVPWM modulation unit, and modulates the input direct-current voltage into three-phase alternating-current voltage.

Description

Control method and control system of permanent magnet synchronous motor for vehicle
Technical Field
The invention relates to the technical field of motor control, in particular to a control method and a control system of a permanent magnet synchronous motor for a vehicle.
Background
The permanent magnet synchronous motor has the advantages of high efficiency, excellent durability, large torque and power density, easiness in control and the like, and is widely applied to a new energy automobile electric drive system. In the running process of the whole vehicle, the permanent magnet synchronous motor outputs corresponding torque under the instruction action of the motor controller. For torque control of permanent magnet synchronous motors, a currently common algorithm is the vector control algorithm (FOC).
Compared with a direct torque method, the vector control algorithm has no overlarge torque fluctuation in a low-speed area, and the over-temperature is not easy to cause; and the method comprises a current closed-loop control process, is not easy to cause overcurrent, and can meet the requirements of stable large-torque output required by the low speed and climbing of the automobile.
The vector control algorithm is to perform coordinate transformation processing on three-phase current of the alternating current motor, gradually transform the three-phase static coordinate system into a two-phase static coordinate system and a synchronous rotating coordinate system, and finally obtain two direct current components, namely a direct-axis current component and an alternating-axis current component. Therefore, the control of the alternating current is converted into the control of the direct current, the accurate tracking of the actual current to the instruction current is realized through the current closed-loop control structure, and the MPC control algorithm is adopted in more and more occasions nowadays for the PID control algorithm commonly used in the engineering.
And (3) PID control algorithm: the difference between the reference value and the actual value of the motor quadrature-direct axis current component is used as output, the input voltage component of the motor model is obtained through the PID control unit, and the back electromotive force generated by the rotor flux linkage is coupled in a feedforward mode to obtain the final phase voltage input value of the model.
A finite set MPC control algorithm: and (4) without the assistance of an SVPWM (space vector pulse width modulation) algorithm, the optimal voltage vector solution is confirmed by bringing the voltage vector corresponding to each switching state of the inverter into the cost function, so that the optimal switching state in the current carrier frequency period is obtained.
Continuous set MPC control algorithm: and (3) combining modulation algorithms such as SVPWM (space vector pulse width modulation) or SPWM (sinusoidal pulse width modulation), obtaining an optimal voltage vector solution by searching a minimum value point of the cost function in the constraint condition, and generating a modulation wave with a plurality of switch combinations through a PWM (pulse width modulation) module.
The PID control algorithm has the following drawbacks: in the engineering application process, a process of modeling a control system is lacked in most cases, and the setting of parameters mainly adopts qualitative adjustment, so that accurate quantification is difficult to realize; for a time-varying system, PID parameters need to be adjusted in real time, and the time cost of parameter setting at the early stage is improved.
The MPC control algorithm has the following drawbacks: the MPC control algorithm can realize accurate control based on a motor model, and has the defects of overlarge calculated amount, small carrier frequency period when the motor runs to a high-speed interval, and difficulty in allocating enough resources to the system for the MPC control algorithm.
Therefore, for controlling the permanent magnet synchronous motor for the vehicle, a control strategy which can overcome the defects of the PID control algorithm and the MPC control algorithm and combine the advantages of the PID control algorithm and the MPC control algorithm is needed.
Disclosure of Invention
Aiming at the problems, the invention provides a control method and a control system of a permanent magnet synchronous motor for a vehicle.
The invention provides a control method of a permanent magnet synchronous motor for a vehicle, which is characterized in that the control method is switched according to the relative relation between the actual rotating speed of the current motor and a basic speed point, when the rotating speed is lower than the basic speed point, an MPC (personal computer) control algorithm is adopted, and when the rotating speed is higher than the basic speed point, a PID (proportion integration differentiation) control algorithm is adopted; the MPC control algorithm and the PID control algorithm take the current command output by the torque control unit as a reference quantity to carry out closed-loop control on the current.
Further, the MPC control algorithm calculates the state variable and voltage vector results in the next several control periods through state space equation derivation according to the state variable measurement value of the motor at the current moment; and establishing a cost function related to the state variable error and the phase voltage fluctuation amount, and obtaining a phase voltage vector corresponding to the optimal control precision through one-time calculation.
Further, the MPC control algorithm is implemented by the specific steps of:
(1) Sampling three-phase current and rotor position;
(2) D/q axis current is obtained through coordinate transformation, and angular velocity is obtained through rotation transformation settlement;
(3) Calculating a d/q axis voltage value at the current moment according to the voltage model;
(4) Obtaining the optimal value of the d/q axis voltage variation at the next moment according to an MPC control algorithm;
(5) And outputting the d/q axis voltage value at the next moment.
Further, the state space equation of the MPC control algorithm is:
Figure BDA0003643785510000031
wherein id and iq are respectively the dq axis current of the motor; ld and Lq are respectively shaft inductors of a motor dq; w is the motor speed, wi q Is the product of the motor speed and the q-axis current, wi d Is the product of the motor speed and the d-axis current; r is the internal resistance of the motor coil; lambda is the motor rotor flux linkage; ud and uq are the motor dq axis voltages respectively.
Further, the cost function of the MPC control algorithm is:
Figure BDA0003643785510000032
wherein Np is the predicted step number, nu is the predicted control step number, Q is the weight of the system output change, and R is the weight of the system control input change; id/q is an actual current vector under a motor dq axis, id/q, ref is a reference current vector under the motor dq axis, delta ud/q is the variable quantity of a voltage vector under the motor dq axis, id/q, base is a current rated value, ud/q and base is a voltage rated value.
Further, the PID control algorithm carries out frequent qualitative adjustment on the phase voltage vector according to the actual error of the current in each control period, so that the output current of the motor gradually approaches to the reference value.
The invention provides a control system of a permanent magnet synchronous motor for a vehicle, which comprises a motor power driving part and a motor control logic part; the motor power driving part comprises a direct current bus power supply, a motor controller and a permanent magnet synchronous motor; the motor control logic part comprises a torque control unit, a control mode enabling unit, an MPC control unit, a PID control unit and an SVPWM modulation unit; the torque control unit converts a torque command input by the whole vehicle control unit into a corresponding stator current command; the control mode enabling unit selects and switches a corresponding control mode according to the current rotating speed of the motor, and enables the MPC control mode when the rotating speed of the motor is lower than a basic speed point; when the rotating speed of the motor is higher than a base speed point, the unit enables a PID control mode; the MPC control mode and the PID control mode take the current instruction output by the torque control unit as a reference quantity to carry out closed-loop control on the current; the SVPWM modulation unit takes the phase voltage vector calculated by the MPC or PID unit as input, calculates the actual conduction sequence and conduction time of the inverter power tube corresponding to the target voltage, generates 6 paths of PWM low-voltage modulation signals and controls the on-off of the 6 paths of power tubes in the inverter; the motor controller switches on and off a power switch tube of the inverter under the modulation action of the SVPWM modulation unit, modulates input direct-current voltage into three-phase alternating-current voltage, acts on a three-phase input end of the permanent magnet synchronous motor, and excites the three-phase input end to generate expected three-phase current.
Further, the motor control logic part also comprises a weak magnetic current calculation unit which is used for acquiring the specific offset corresponding to the d-axis current along with the increase of the rotating speed or the torque in a weak magnetic interval of the motor.
The invention provides electronic equipment which comprises a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to realize the steps of the permanent magnet synchronous motor control method.
The present invention provides a computer readable storage medium for storing computer instructions which, when executed by a processor, implement the steps of a permanent magnet synchronous motor control method according to the present invention.
The invention has the beneficial effects that:
(1) The technical advantages of the MPC control algorithm and the PID control algorithm can be integrated, and the high-precision and flexible control function can be realized. By adopting the invention, an MPC algorithm can be adopted in the constant torque area of the motor, thereby reducing the overshoot of the controlled object, shortening the response time of the system and realizing the accurate control of the output torque of the motor. When the rotating speed of the motor rises and enters a constant power area, the system is switched to a PID control algorithm, and the calculation load of the system is reduced while the control precision is ensured.
(2) The invention is different from the method of directly selecting the dq axis current or the stator flux linkage and the output torque in the prior literature and patent when establishing the state vector of the MPC algorithm. In order to ensure that a standard state space equation can be formed after the motor model is subjected to discretization and derivation processing, the invention establishes a model consisting of id, iq, w and wi d 、wi q The formed 5-dimensional state vector reduces the workload of formula processing in the subsequent prediction calculation process of the model.
(3) In the process of establishing the cost function, the invention increases the dimension reduction processing process of the state vector, only selects two dimensions of id and iq to participate in calculation, and simplifies the cost function into a quadratic programming form about the current error of the dq axis and the voltage increment of the dq axis. In addition, the invention respectively carries out standardization processing on the two physical quantities of current and voltage, so that the two physical quantities can be compared in the same order of magnitude, thereby omitting the selection process of weight coefficients.
Drawings
FIG. 1 is a schematic diagram of a control system of a permanent magnet synchronous motor for a vehicle;
FIG. 2 is an MPC control algorithm implementation.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1.
1. The technical advantages of an MPC control algorithm and a PID control algorithm are adopted comprehensively by the scheme, and stable and accurate control of the motor can be realized. The control strategy is to switch the control method according to the relative relation between the actual rotating speed of the current motor and a basic speed point, when the rotating speed is lower than the basic speed point (namely in a constant torque area), an MPC control algorithm is adopted, and when the rotating speed is higher than the basic speed point (namely in a constant power area), a PID control algorithm is adopted; the MPC control algorithm and the PID control algorithm take the current command output by the torque control unit as a reference quantity to carry out closed-loop control on the current.
In a low-speed interval, the electromagnetic characteristics of the motor present a highly linear relationship, accurate modeling can be performed, and an MPC control algorithm realized based on the model has sufficient control precision; in a high-speed interval, because the stator core has magnetic saturation and cross coupling phenomena, the armature reaction of the stator coil is complex, the whole system has a nonlinear relation, an accurate mathematical model capable of real-time operation is difficult to establish, a modeling link can be omitted by adopting a PID algorithm, and the development time cost is greatly shortened on the premise of meeting the control requirement.
Example 2.
A control system of a permanent magnet synchronous motor for a vehicle is shown in fig. 1.
In the technical scheme of fig. 1, the motor control system comprises two parts, namely a motor power driving part and a motor control logic part. The motor power driving part comprises a direct current bus power supply, a motor controller and a permanent magnet synchronous motor. The motor control logic part comprises a torque control unit, a control mode enabling unit, an MPC control unit, a PID control unit, a weak magnetic current calculation unit and an SVPWM modulation unit. The torque control unit converts a torque instruction input by the whole vehicle control unit into a corresponding stator current instruction; the control mode enabling unit has the function of selecting and switching a corresponding control mode according to the current rotating speed of the motor, and when the rotating speed of the motor is lower than a basic speed point, the unit enables the MPC control mode; when the rotating speed of the motor is higher than a base speed point, the unit enables a PID control mode; the MPC control mode and the PID control mode take the current instruction output by the torque control unit as a reference quantity to carry out closed-loop control on the current; the SVPWM modulation unit takes the phase voltage vector calculated by the MPC or PID unit as input, calculates the actual conduction sequence and conduction time of the inverter power tube corresponding to the target voltage, generates 6 paths of PWM low-voltage modulation signals and controls the on-off of the 6 paths of power tubes in the inverter; under the modulation action of the internal control unit, the motor controller switches on and off a power switch tube of the inverter according to a certain rule, modulates input direct-current voltage into three-phase alternating-current voltage, acts on a three-phase input end of the permanent magnet synchronous motor, and excites the three-phase input end to generate expected three-phase current.
Specifically, the method comprises the following steps:
(1) The motor power driving part comprises a direct current bus power supply, a motor controller and a permanent magnet synchronous motor. The direct current bus power supply provides input electric energy for the electric drive system; under the modulation action of the internal control unit, the motor controller switches on and off a power switch tube of the inverter according to a certain rule, modulates input direct-current voltage into three-phase alternating-current voltage, acts on a three-phase input end of the permanent magnet synchronous motor, and excites the three-phase input end to generate expected three-phase current.
(2) The motor control logic part comprises a torque control unit, an MPC control unit, a PID control unit, a weak magnetic current calculation unit, a control mode enabling unit and an SVPWM modulation unit.
(3) The torque control unit has the function of converting a torque command input by the whole vehicle control unit into a corresponding stator current command, and common methods comprise an MTPA method, a negative id weak magnetic current correction method, a table look-up method and the like.
(4) The MPC control unit functions to perform closed-loop control of the current with reference to the current command outputted from the torque control unit. According to the measured value of the state variable of the motor at the current moment, the state variable and voltage vector results in the next several control periods are calculated through mathematical model derivation. And establishing a cost function related to the state variable error and the phase voltage fluctuation amount, and obtaining a phase voltage vector corresponding to the optimal control precision through one-time calculation.
(5) The function of the PID control unit is to perform closed-loop control of the current by taking the current command output by the torque control unit as a reference. And carrying out frequent qualitative adjustment on the phase voltage vector according to the actual error of the current in each control period, so that the output current of the motor gradually approaches a reference value, and the control precision of the system is improved.
(6) The function of the weak magnetic current calculation unit is to acquire the specific offset corresponding to the d-axis current along with the increase of the rotating speed or the torque in the weak magnetic interval of the motor.
(7) The function of the control mode enabling unit is to select and switch the corresponding control mode according to the current rotating speed of the motor. When the rotating speed of the motor is lower than a basic speed point, namely in a constant torque interval, enabling an MPC control mode by the unit; when the rotating speed of the motor is higher than a basic speed point, namely in a constant power interval, the unit needs to enable a PID control mode.
(8) The SVPWM modulation unit takes the phase voltage vector calculated by the MPC or PID control unit as input, calculates the actual conduction sequence and conduction time of the inverter power tube corresponding to the target voltage, generates 6 paths of PWM low-voltage modulation signals and controls the on-off of the 6 paths of power tubes in the inverter.
Example 3.
An implementation scheme of an MPC control algorithm is shown in fig. 2, and the specific steps are as follows:
(1) Sampling three-phase current and rotor position;
(2) D/q axis current is obtained through coordinate transformation, and angular velocity is obtained through rotation transformation settlement;
(3) Calculating a d/q axis voltage value at the current moment according to the voltage model;
(4) Acquiring the optimal value of the d/q axis voltage variation at the next moment according to the MPC control algorithm;
(5) And outputting the d/q axis voltage value at the next moment.
Wherein, the state space equation of the MPC control algorithm is as follows:
Figure BDA0003643785510000091
wherein id and iq are respectively the dq axis current of the motor; ld and Lq are respectively shaft inductors of a motor dq; w is the motor speed, wi q Is the product of the rotational speed and the q-axis current, wi d Is the product of the rotational speed and the d-axis current; r is the internal resistance of the motor coil; lambda is the motor rotor flux linkage; ud and uq are the motor dq axis voltages respectively.
The invention is different from the method of directly selecting the dq-axis current or the stator flux linkage and the output torque in the prior literature and patent when establishing the state vector of the MPC algorithm. In order to ensure that a standard state space equation can be formed after the motor model is subjected to discretization and derivation processing, the invention establishes a model consisting of id, iq, w and wi d 、wi q The formed 5-dimensional state vector reduces the workload of formula processing in the subsequent prediction calculation process of the model.
The cost function of the MPC control algorithm is:
Figure BDA0003643785510000092
wherein Np is the predicted step number, nu is the predicted control step number, Q is the weight of the system output change, and R is the weight of the system control input change; id/q is an actual current vector under a motor dq axis, id/q, ref is a reference current vector under the motor dq axis, delta ud/q is the variable quantity of a voltage vector under the motor dq axis, id/q, base is a current rated value, ud/q and base is a voltage rated value.
In the process of establishing the cost function, the invention increases the dimension reduction processing process of the state vector, only selects two dimensions of id and iq to participate in calculation, and simplifies the cost function into a quadratic programming form about the current error of the dq axis and the voltage increment of the dq axis. In addition, the invention respectively standardizes the two physical quantities of current and voltage, so that the two physical quantities can be compared in the same order of magnitude, thereby omitting the selection process of weight coefficients.
Example 4.
An electronic device comprises a memory and a processor, wherein the memory stores a computer program, and the processor realizes the steps of the permanent magnet synchronous motor control method when executing the computer program. A computer readable storage medium for storing computer instructions which, when executed by a processor, implement the steps of a permanent magnet synchronous motor control method according to the present invention.

Claims (10)

1. A control method of a permanent magnet synchronous motor for a vehicle is characterized by comprising the following steps: the control method is switched according to the relative relation between the actual rotating speed of the current motor and a basic speed point, when the rotating speed is lower than the basic speed point, an MPC control algorithm is adopted, and when the rotating speed is higher than the basic speed point, a PID control algorithm is adopted; the MPC control algorithm and the PID control algorithm take the current command output by the torque control unit as a reference quantity to carry out closed-loop control on the current.
2. The control method of the permanent magnet synchronous motor for a vehicle according to claim 1, characterized in that: the MPC control algorithm calculates the state variable and voltage vector results in the next control periods through state space equation derivation according to the state variable measurement value of the motor at the current moment; and establishing a cost function related to the state variable error and the phase voltage fluctuation amount, and obtaining a phase voltage vector corresponding to the optimal control precision through one-time calculation.
3. The control method of the permanent magnet synchronous motor for the vehicle according to claim 2, characterized in that: the MPC control algorithm is realized by the following specific steps:
(1) Sampling three-phase current and rotor position;
(2) D/q axis current is obtained through coordinate transformation, and angular velocity is obtained through rotation transformation settlement;
(3) Calculating a d/q axis voltage value at the current moment according to the voltage model;
(4) Obtaining the optimal value of the d/q axis voltage variation at the next moment according to an MPC control algorithm;
(5) And outputting the d/q axis voltage value at the next moment.
4. The control method of the permanent magnet synchronous motor for the vehicle according to claim 2, characterized in that: the state space equation of the MPC control algorithm is as follows:
Figure FDA0003643785500000021
wherein id and iq are respectively the dq axis current of the motor; ld and Lq are respectively the motor dq shaft inductors; w is the motor speed, wi q Is the product of the motor speed and the q-axis current, wi d Is the product of the motor speed and the d-axis current; r is the internal resistance of the motor coil; lambda is the motor rotor flux linkage; ud and uq are the motor dq axis voltages respectively.
5. The control method of the permanent magnet synchronous motor for the vehicle according to claim 2, characterized in that: the cost function of the MPC control algorithm is as follows:
Figure FDA0003643785500000022
wherein Np is the predicted step number, nu is the predicted control step number, Q is the weight of the system output change, and R is the weight of the system control input change; id/q is an actual current vector under a motor dq axis, id/q, ref is a reference current vector under the motor dq axis, delta ud/q is the variable quantity of a voltage vector under the motor dq axis, id/q, base is a current rated value, ud/q and base is a voltage rated value.
6. The control method of the permanent magnet synchronous motor for the vehicle according to claim 1, characterized in that: and the PID control algorithm is used for carrying out frequent qualitative adjustment on the phase voltage vector according to the actual error of the current in each control period, so that the output current of the motor gradually approaches to a reference value.
7. A control system of a permanent magnet synchronous motor for a vehicle is characterized in that: the control system comprises a motor power driving part and a motor control logic part; the motor power driving part comprises a direct current bus power supply, a motor controller and a permanent magnet synchronous motor; the motor control logic part comprises a torque control unit, a control mode enabling unit, an MPC control unit, a PID control unit and an SVPWM modulation unit; the torque control unit converts a torque instruction input by the whole vehicle control unit into a corresponding stator current instruction; the control mode enabling unit selects and switches a corresponding control mode according to the current rotating speed of the motor, and enables the MPC control mode when the rotating speed of the motor is lower than a basic speed point; when the rotating speed of the motor is higher than a base speed point, the unit enables a PID control mode; the MPC control mode and the PID control mode take the current instruction output by the torque control unit as a reference quantity to carry out closed-loop control on the current; the SVPWM modulation unit takes the phase voltage vector calculated by the MPC or PID unit as input, calculates the actual conduction sequence and conduction time of the inverter power tube corresponding to the target voltage, generates 6 paths of PWM low-voltage modulation signals and controls the on-off of the 6 paths of power tubes in the inverter; the motor controller switches on and off a power switch tube of the inverter under the modulation action of the SVPWM modulation unit, modulates input direct-current voltage into three-phase alternating-current voltage, acts on a three-phase input end of the permanent magnet synchronous motor, and excites the three-phase input end to generate expected three-phase current.
8. The control system of a permanent magnet synchronous motor for a vehicle according to claim 7, characterized in that: the motor control logic part also comprises a weak magnetic current calculation unit which is used for acquiring the specific offset corresponding to the d-axis current along with the increase of the rotating speed or the torque in a weak magnetic interval of the motor.
9. An electronic device comprising a memory and a processor, the memory storing a computer program, characterized in that: the processor, when executing the computer program, realizes the steps of the method of any of claims 1-6.
10. A computer-readable storage medium for storing computer instructions, characterized in that: the computer instructions, when executed by a processor, implement the steps of the method of any one of claims 1-6.
CN202210521812.5A 2022-05-13 2022-05-13 Control method and control system of permanent magnet synchronous motor for vehicle Pending CN115173770A (en)

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