Permanent magnet synchronous motor control method, controller, compressor and household appliance

Abstract

The invention relates to a permanent magnet synchronous motor control method, a controller, a compressor and a household appliance, and the method comprises the steps: firstly obtaining the stator current of a motor, determining a stator flux linkage theoretical value of the motor according to the stator current, and then defining a stator flux linkage estimation value function of the motor, determining a rotor flux linkage characteristic value according to a stator flux linkage estimation value function of the motor, obtaining a first deviation function and a second deviation function, solving a stator flux linkage estimation value when the second deviation function is a minimum value, and determining the stator flux linkage estimation value meeting a constraint condition as a target stator flux linkage value; and finally determining the rotating speed of the motor according to the target stator flux linkage value, and controlling the motor according to the rotating speed of the motor. According to the method, the target stator flux linkage value after interference removal is accurately estimated by taking the characteristics that the rotor flux linkage is a constant value and is not related to the rotor rotating speed as well as the condition that the first deviation function is zero as a constraint condition, so that the accuracy of motor rotating speed estimation is improved, and the motor is accurately controlled.

Description

Technical Field

[0001] The present application relates to the field of motor stall detection, and in particular to a permanent magnet synchronous motor control method, a controller, a compressor and household electrical appliances. Background Art

[0002] Compressors are widely used in household appliances, such as refrigerators and freezers. The core components of the compressor are the controller and the permanent magnet synchronous motor. During the operation of the compressor, the controller generally uses the PMSM (Permanent-magnet Synchronous Motor) magnetic field oriented control method to control the motor. This method collects the stator current signal, transforms the coordinates, estimates the back electromotive force, and then controls the motor or adjusts the motor speed according to the back electromotive force.

[0003] However, since the back EMF information of the motor is proportional to the rotor speed, when the rotor speed is low, the back EMF is also relatively small, and the back EMF information cannot be stably extracted, and thus the motor cannot be accurately controlled. Summary of the invention

[0004] The present application solves at least one of the above-mentioned technical problems to a certain extent. To this end, the present application provides a permanent magnet synchronous motor control method, a controller, a compressor and a household appliance, which can control the motor more accurately.

[0005] In a first aspect, an embodiment of the present application provides a permanent magnet synchronous motor control method, the method comprising:

[0006] Obtain the stator current of the motor in a two-phase stationary coordinate system;

[0007] Determining a theoretical value of a stator flux of the motor according to the stator current;

[0008] A stator flux estimation value function of the motor is defined, wherein the variable is the stator flux estimation value, wherein the stator flux estimation value is the stator flux value after removing interference from the stator flux theoretical value;

[0009] Determining a rotor flux characteristic value according to a stator flux estimation function of the motor, wherein the rotor flux characteristic value is positively correlated with a rotor flux amplitude of the motor;

[0010] Constructing a first deviation function and a second deviation function, wherein the first deviation function is a deviation between the rotor flux characteristic value and the rotor flux amplitude, and the second deviation function is a deviation between the stator flux estimation value function and the stator flux theoretical value;

[0011] Obtaining the stator flux estimation value when the second deviation function is a minimum value, and determining the stator flux estimation value satisfying a constraint condition as a target stator flux value, wherein the constraint condition is that the first deviation function is zero;

[0012] Determining the rotation speed of the motor according to the target stator flux value;

[0013] The motor is controlled according to the rotation speed of the motor.

[0014] In some embodiments, determining a theoretical value of a stator flux of the motor according to the stator current includes:

[0015] Inputting the stator current into the current loop to obtain the stator voltage of the motor;

[0016] The theoretical value of the stator flux of the motor is obtained by the following formula:

[0017] pψ αβ =-R s i αβ +v αβ ;

[0018] Among them, p is the differential operator, ψ αβ =[ψ α ,ψ β ] T is the theoretical value of stator flux, i αβ =[i α ,i β ] T ,v αβ =[v α ,v β ] T are the stator current and stator voltage of the motor in the two-phase stationary coordinate system, R s is the stator phase resistance.

[0019] In some embodiments, determining the rotor flux characteristic value according to the stator flux estimation function of the motor includes:

[0020] The rotor flux characteristic value of the motor is obtained by the following formula:

[0021]

[0022] in, is the rotor flux characteristic value, is the estimated value of the stator flux, is the inductance matrix, L0=(L d +L q ) / 2 is the average inductance, L1=(L d -L q) / 2 is the differential inductance, L d ,L q is the d-axis and q-axis inductance, θ e is the rotor electrical angle.

[0023] In some embodiments, constructing the first deviation function includes:

[0024] The first deviation function is constructed by the following formula:

[0025]

[0026] in, is the first deviation function, is the rotor flux eigenvalue, || || is the Euclidean norm, ψ f is the rotor flux amplitude.

[0027] In some embodiments, constructing the second deviation function comprises:

[0028] The second deviation function is constructed by the following formula:

[0029]

[0030] in, is the second deviation function, is the estimated value of the stator flux, ψ αβ =[ψ α ,ψ β ] T is the theoretical value of the stator flux.

[0031] In some embodiments, obtaining the stator flux estimation value when the second deviation function is a minimum value, and determining the stator flux estimation value satisfying the constraint condition as the target stator flux value, includes:

[0032] Taking the first deviation function being zero as a constraint condition and the second deviation function as the objective function, the following Lagrangian function is constructed:

[0033]

[0034] Among them, L m is the Lagrangian function, is the second deviation function, is the first deviation function, λ is the Lagrange multiplier;

[0035] The stator flux theoretical value and the stator current are substituted into the Lagrangian function to obtain the target stator flux value.

[0036] In some embodiments, substituting the stator flux theoretical value and the stator current into the Lagrangian function to obtain the target stator flux value includes:

[0037] Solve the partial derivatives of the Lagrangian function and set the partial derivatives equal to zero to construct the following first functional equation:

[0038]

[0039] in, is the gradient operator;

[0040] Based on the first functional equation, the second functional equation is obtained:

[0041]

[0042] in, is the estimated value of the stator flux, ξ αβ =[ξ α ,ξ β ] T is the theoretical value of the stator flux, i αβ =[i α ,i β ] T is the stator current of the motor in the two-phase stationary coordinate system, is the inductance matrix, L0=(L d +L q ) / 2 is the average inductance, L1=(L d -L q ) / 2 is the differential inductance, L d ,L q is the d-axis and q-axis inductance, θ e is the rotor electrical angle, λ is the Lagrange multiplier, ψ f is the rotor flux amplitude;

[0043] Substitute the stator flux theoretical value and the stator current into the second functional equation to obtain a solution to the stator flux estimation value, and determine the solution to the stator flux estimation value as the target stator flux value.

[0044] In some embodiments, determining the speed of the motor according to the target stator flux value includes:

[0045] Determining the electrical angle of the motor according to the target stator flux value;

[0046] The electrical angle is input into a phase-locked loop to obtain the rotational speed of the motor.

[0047] In a second aspect, an embodiment of the present application provides a controller, comprising at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the permanent magnet synchronous motor control method as described above.

[0048] In a third aspect, an embodiment of the present application provides a compressor, comprising a permanent magnet synchronous motor and a controller as described above, wherein the permanent magnet synchronous motor is connected to the controller.

[0049] In a fourth aspect, an embodiment of the present application provides a household appliance, comprising a whole machine controller and the compressor as described above, wherein the whole machine controller is connected to the compressor.

[0050] Compared with the prior art, the present application has at least the following beneficial effects: in the permanent magnet synchronous motor control method in the present application, the stator current of the motor in a two-phase stationary coordinate system is first obtained, and the stator flux theoretical value of the motor is determined according to the stator current, and then the stator flux estimation function of the motor is defined, and the variable is the stator flux estimation value, and the rotor flux characteristic value is determined according to the stator flux estimation function of the motor, and a first deviation function and a second deviation function are obtained, wherein the first deviation function is the deviation between the rotor flux characteristic value and the rotor flux amplitude, and the second deviation function is the deviation between the stator flux estimation function and the stator flux theoretical value, and then the stator flux estimation value when the second deviation function is a minimum value is obtained, and the stator flux estimation value that meets the constraint condition is determined as the target stator flux value, wherein the constraint condition is that the first deviation function is zero, and finally the motor speed is determined according to the target stator flux value, and the motor is controlled according to the motor speed. Therefore, the permanent magnet synchronous motor control method takes the rotor flux as a constant value and the characteristic that it is not related to the rotor speed. It takes the first deviation function to be zero as a constraint condition, accurately estimates the target stator flux value after removing the interference, and then determines the motor speed based on the target stator flux value after removing the interference, thereby improving the accuracy of the motor speed estimation and enabling more accurate control of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0052] Figure 1 It is a structural schematic diagram of a household appliance provided in an embodiment of the present application;

[0053] Figure 2It is a schematic diagram of a controller structure provided in an embodiment of the present application;

[0054] Figure 3 It is a flowchart of a permanent magnet synchronous motor control method provided in an embodiment of the present application;

[0055] Figure 4 The embodiment of this application provides Figure 3 Schematic diagram of the process of step S106;

[0056] Figure 5 It is a structural schematic diagram of a permanent magnet synchronous motor control device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0058] It should be noted that, if there is no conflict, the various features in the embodiments of the present application can be combined with each other, all within the scope of protection of the present application. In addition, although the functional module division is performed in the device schematic diagram and the logical order is shown in the flow chart, in some cases, the steps shown or described can be performed in a sequence different from the module division in the device or the flow chart. Furthermore, the words "first", "second", "third", etc. used in this application do not limit the data and execution order, but only distinguish the same items or similar items with basically the same functions and effects.

[0059] See also Figure 1 , Figure 1 Schematic diagram of the circuit structure of a household appliance provided in an embodiment of the present application. Figure 1 As shown, the household appliance 100 includes a whole machine controller 10 , an evaporator 20 , a condenser 30 and a compressor 40 , wherein the whole machine controller 10 is connected to the compressor 40 .

[0060] The compressor 40 compresses the low-temperature and low-pressure gas from the evaporator 20 into a high-temperature and high-pressure liquid through a motor, and then sends it to the condenser 30. It is sprayed into the evaporator 20 through a capillary tube, and the pressure drops suddenly, and the liquid refrigerant becomes gaseous, absorbing a large amount of heat in the air through the heat sink.

[0061] The whole machine controller 10 communicates with the compressor 40 via the LIN / CAN bus. The whole machine controller 10 sends instructions to the compressor 40 to control the working power of the compressor 40, start the compressor 40 or shut it down. Specifically, the whole machine controller 10 can send a target speed or target power instruction to the compressor 40, and the compressor 40 then uses the current loop and speed loop control according to the target speed or target power instruction. The speed loop control is mainly used to perform state switching and speed PID control with a period of Tms. The current loop control is mainly used to perform phase current reading, observer algorithm, SVPWM, current PID control, and synchronized with the PWM period. In parameter debugging, the current loop is adjusted first, and the current loop parameters are adjusted through the current waveforms in the pre-positioning stage and the open-loop stage, and then the speed loop PI parameters are adjusted.

[0062] The compressor 40 includes a controller 402 and a motor 401, the motor 401 is connected to the controller 402, and the controller 402 is connected to the whole machine controller 10. During the operation of the compressor 40, the controller 402 receives instructions issued by the whole machine controller 10, and can perform fault detection such as the voltage and current of the motor system, and then report the fault status to the whole machine controller 10 through LIN. The controller 402 can also output a PWM signal through the PID and SMC control algorithms according to the instructions issued by the whole machine controller 10, and the PWM signal controls the working state of the three-phase bridge, thereby controlling the speed, current or power of the motor 401.

[0063] Motor 401 is a permanent magnet synchronous motor (PMSM), which works on the principle of using permanent magnets to generate a magnetic field on the rotor. When three-phase current is passed through the stator winding, a rotating magnetic field is generated. This rotating magnetic field interacts with the magnetic field of the permanent magnet on the rotor to generate a synchronously rotating electromagnetic torque, thereby driving the motor rotor to rotate.

[0064] At present, a PMSM magnetic field oriented control method is used to control the motor 401. This method collects the stator current signal, estimates the back electromotive force information through coordinate transformation, and then calculates the angle information and position information of the rotor according to the back electromotive force information, and finally controls the motor or adjusts the speed of the motor according to the angle information and position information of the rotor. However, when the speed of the rotor is low, the back electromotive force is also small, and the back electromotive force information cannot be stably extracted, and thus the motor cannot be accurately controlled.

[0065] Based on the above reasons, an embodiment of the present application provides a permanent magnet synchronous motor control method, which includes first obtaining the stator current of the motor in a two-phase stationary coordinate system, determining the stator flux theoretical value of the motor according to the stator current, and then defining the stator flux estimation function of the motor, where the variable is the stator flux estimation value, and determining the rotor flux characteristic value according to the stator flux estimation function of the motor, obtaining a first deviation function and a second deviation function, wherein the first deviation function is the deviation between the rotor flux characteristic value and the rotor flux amplitude, and the second deviation function is the deviation between the stator flux estimation function and the stator flux theoretical value, obtaining the stator flux estimation value when the second deviation function is a minimum value, and determining the stator flux estimation value that satisfies the first deviation function to be zero as the target stator flux value, and finally determining the motor speed according to the target stator flux value, and controlling the motor according to the motor speed.

[0066] Therefore, the permanent magnet synchronous motor control method takes the rotor flux as a constant value and the characteristic that it is not related to the rotor speed. It takes the first deviation function to be zero as a constraint condition, accurately estimates the target stator flux value after removing the interference, and then determines the motor speed based on the target stator flux value after removing the interference, thereby improving the accuracy of the motor speed estimation and enabling more accurate control of the motor.

[0067] Please also read Figure 2 , Figure 2 402 is a schematic diagram of the hardware structure of a controller provided in an embodiment of the present application. The controller 402 includes at least one processor 4021 (connected by a system bus or other communication methods). Figure 2 A processor is used as an example) and a memory 4022. The controller 402 may exist in the form of a chip.

[0068] In which, the memory 4022 stores instructions that can be executed by the at least one processor 4021, and the instructions are executed by the at least one processor 4021. The processor 4021 is used to provide computing and control capabilities to execute relevant commands, for example, to control the compressor 40 to execute any one of the permanent magnet synchronous motor control methods provided in the following embodiments of the present application.

[0069] The memory 4022, as a non-transient computer-readable storage medium, can be used to store non-transient software programs, non-transient computer executable programs and modules, such as the program instructions / modules corresponding to the permanent magnet synchronous motor control method provided in the following embodiments of the present application. The processor 4021 can implement the permanent magnet synchronous motor control method in any of the following method embodiments by running the non-transient software programs, instructions and modules stored in the memory 4022. Specifically, the memory 4022 may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some embodiments, the memory 4022 may also include a memory remotely arranged relative to the processor 4021, and these remote memories may be connected to the processor 4021 via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network and a combination thereof.

[0070] In some embodiments, the controller 402 may be a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a single chip microcomputer, an ARM (Acorn RISC Machine) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination of these components. In addition, the controller 402 may also be any conventional processor, controller, microcontroller, or state machine. The controller 402 may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in combination with a DSP, and / or any other such configuration.

[0071] The present application provides a method for controlling a permanent magnet synchronous motor. Figure 3 , Figure 3 The flowchart of the permanent magnet synchronous motor control method provided in the embodiment of the present application is shown in S100, and the method includes but is not limited to the following steps:

[0072] S101: Obtaining the stator current of the motor in a two-phase stationary coordinate system;

[0073] First, measure the three-phase current of the motor, and then convert it into the current i in the two-phase stationary coordinate system (αβ coordinate system) through Clarke transformation. αβ =[i α ,i β ] T .

[0074] The stator current can be detected by a current sensor, such as a Hall effect sensor, a current transformer, a shunt resistor, etc. It can also be directly measured using a current sampling circuit. For example, in the three-phase winding of the motor, a low-resistance sampling resistor (shunt) is connected in series, the voltage drop across the resistor is measured, and the current value is calculated according to Ohm's law.

[0075] S102: determining a theoretical value of a stator flux of the motor according to the stator current;

[0076] Stator flux refers to the sum of the magnetic flux of the magnetic field generated by the current in the stator coil of the motor. The size of the stator flux directly affects the electromagnetic torque and operating performance of the motor. The stator flux is related to the stator current and magnetic flux, and the stator flux can be obtained by integrating the stator current and stator voltage.

[0077] Specifically, first input the stator current into the current loop to obtain the stator voltage of the motor, and then obtain the theoretical value of the stator flux of the motor through the following formula:

[0078] pψ αβ =-R s i αβ +v αβ (1)

[0079] Among them, p is the differential operator, ψ αβ =[ψ α ,ψ β ] T is the theoretical value of stator flux, i αβ =[i α ,i β ] T ,v αβ =[v α ,v β ] T are the stator current and stator voltage of the motor in the two-phase stationary coordinate system, R s is the stator phase resistance.

[0080] That is, the theoretical value of stator flux ψ αβ =∫(-R s i αβ +v αβ ), where the stator current i αβ is the measured value, which is the current value obtained after being disturbed (such as measurement interference, dead zone effect, initial conditions and other external interference factors), then the theoretical value of stator flux ψ αβ is based on the stator current i αβ The directly calculated value is also the stator flux after interference. If the motor speed is estimated based on the theoretical value of the stator flux, the motor speed estimation will be inaccurate, and the motor cannot be accurately controlled.

[0081] Therefore, in the embodiment of the present application, it is necessary to use the stator flux theoretical value ψ αβ And some constraints are used to estimate the actual value of the stator flux of the motor, which is the stator flux value after the interference is removed. The stator flux value after the interference is removed is used to estimate the speed of the motor, thereby improving the accuracy of motor control.

[0082] S103: defining a stator flux estimation value function of the motor, wherein a variable is a stator flux estimation value, wherein the stator flux estimation value is a stator flux value obtained by removing interference from the stator flux theoretical value;

[0083] The stator flux value is estimated, and the stator flux estimated value is the actual stator flux value. As a variable, the stator flux estimation function of the motor is defined, and then the optimal solution of the stator flux estimation value is obtained according to the constraint conditions.

[0084] S104: determining a rotor flux characteristic value according to a stator flux estimation value function of the motor, wherein the rotor flux characteristic value is positively correlated with a rotor flux amplitude of the motor;

[0085] The rotor flux refers to the sum of the magnetic flux of the magnetic field generated by the rotor current or permanent magnet on the motor rotor. In a permanent magnet synchronous motor, the rotor flux is usually generated by the permanent magnets on the rotor, while in an asynchronous motor (induction motor), the rotor flux is mainly generated by the rotor current. The rotor flux is closely related to the torque and speed of the motor. The output torque and speed of the motor can be adjusted by changing the rotor flux. The rotor flux amplitude (the size of the rotor flux) will affect the operating stability and efficiency of the motor. In the embodiment of the present application, the motor is a permanent magnet synchronous motor, and therefore, the rotor flux amplitude has a stable and unchanging characteristic.

[0086] The estimated value of the stator flux of the motor and the amplitude of the rotor flux of the motor satisfy the following formula:

[0087]

[0088] in, is the estimated value of the stator flux, is the inductance matrix, L0=(L d +L q ) / 2 is the average inductance, L1=(L d -L q ) / 2 is the differential inductance, L d ,L q are the d-axis and q-axis inductances, is the rotor electrical angle, ψ f is the rotor flux amplitude.

[0089] In formula (2), the inductance matrix L is known, and the rotor electrical angle is the estimated rotor electrical angle, or the actual rotor electrical angle. The present application embodiment derives the rotor electrical angle For the purpose, the rotor electrical angle Get the motor speed.

[0090] Define the rotor flux characteristic value of the motor:

[0091]

[0092] in, is the rotor flux characteristic value.

[0093] According to formula (2), we can get It is positively correlated with the rotor flux amplitude.

[0094] Since the rotor flux amplitude is fixed, the rotor flux characteristic value and the rotor flux amplitude should satisfy the following constraints:

[0095]

[0096] Here, |||| is the Euclidean norm, which is an operation symbol used to find the amplitude.

[0097] That is, in the process of estimating the stator flux, the estimated stator flux estimation value should make the rotor flux characteristic value and the rotor flux amplitude satisfy the constraint condition of formula (4), that is, the amplitude of the rotor flux characteristic value is equal to the rotor flux amplitude.

[0098] S105: constructing a first deviation function and a second deviation function, wherein the first deviation function is a deviation between the rotor flux characteristic value and the rotor flux amplitude, and the second deviation function is a deviation between a stator flux estimation value function and the stator flux theoretical value;

[0099] Based on the above embodiment, it can be known that the estimated stator flux estimation value should make the amplitude of the rotor flux characteristic value equal to the rotor flux amplitude. Therefore, the first deviation function is constructed by the following formula:

[0100]

[0101] in, is the first deviation function, is the rotor flux eigenvalue, |||| is the Euclidean norm, ψ f is the rotor flux amplitude.

[0102] Ideally, Then the estimated stator flux should satisfy Under the constraints, the stator flux estimation value is solved.

[0103] The second deviation function is constructed by the following formula:

[0104]

[0105] in, is the second deviation function, is the estimated value of the stator flux, ψ αβ =[ψ α ,ψ β ] T is the theoretical value of the stator flux.

[0106] The second deviation function is the objective function, which characterizes the difference between the stator flux estimation value and the stator flux theoretical value. It may include multiple minimum values. If the minimum value can be found to minimize the second deviation function, it is considered that the stator flux estimation value can well fit the stator flux theoretical value.

[0107] Then the stator flux estimation value should make the second deviation function is the minimum value and satisfies the constraints The stator flux estimation value that meets the above conditions is the target stator flux value with the smallest error and after removing interference.

[0108] S106: Calculate the stator flux estimation value when the second deviation function is a minimum value, and determine the stator flux estimation value that satisfies the first deviation function to be zero as a target stator flux value;

[0109] Based on the above embodiment, when the objective function is minimized, the constraint conditions must also be satisfied. This is a constrained optimization problem, which can be expressed by the following formula:

[0110]

[0111] In the embodiment of the present application, the Lagrangian function is used to solve the above formula (7). The Lagrangian function is a function that combines the original objective function and the constraint condition. It is a method for finding the extreme value of a function under the constraint condition. It forms an unconstrained problem by adding the constraint condition to the objective function, and then solves this new problem. In the embodiment of the present application, the original objective function is the second deviation function, and the constraint condition is that the first deviation function is zero.

[0112] Specifically, Figure 4 As shown, step S106 includes:

[0113] S1061: Taking the first deviation function being zero as a constraint condition and the second deviation function as an objective function, construct the following Lagrangian function:

[0114]

[0115] Among them, L m is the Lagrangian function, is the second deviation function, is the first deviation function, λ is the Lagrange multiplier;

[0116] S1062: Substitute the stator flux theoretical value and the stator current into the Lagrangian function to obtain the target stator flux value.

[0117] When solving the Lagrangian function, first calculate the partial derivatives of the variables and the Lagrangian multipliers, and set these partial derivatives equal to zero to form a set of equations. If the system of equations is linear, it can be solved directly. If the system of equations is nonlinear, it may be necessary to use an iterative method such as Newton's method or gradient descent.

[0118] After finding the solution to the system of equations, it is necessary to verify whether these solutions meet the constraints, that is, whether they meet the constraint that the first deviation function is zero, and eliminate the solutions that do not meet the constraints. The remaining solutions are the final solutions. If there are multiple solutions, it is necessary to further analyze these solutions to determine which one is the optimal solution, such as by comparing the objective function values ​​of these solutions to determine the optimal solution.

[0119] In the embodiment of the present application, the Lagrangian function is solved, and the obtained solution is the target stator flux value.

[0120] Specifically, first solve the partial derivative of formula (8) and set the partial derivative equal to zero to construct the following first functional equation:

[0121]

[0122] in, is the gradient operator;

[0123] Based on the first functional equation, the second functional equation is obtained:

[0124]

[0125] in, is the estimated value of the stator flux, ξ αβ =[ξ α ,ξ β ] T is the theoretical value of the stator flux, i αβ =[i α ,iβ ] T is the stator current of the motor in the two-phase stationary coordinate system, is the inductance matrix, L0=(L d +L q ) / 2 is the average inductance, L1=(L d -L q ) / 2 is the differential inductance, L d ,L q is the d-axis and q-axis inductance, θ e is the rotor electrical angle, λ is the Lagrange multiplier, ψ f is the rotor flux amplitude.

[0126] Then, the stator flux theoretical value and the stator current are substituted into the second functional equation to obtain a solution to the stator flux estimation value, and the solution to the stator flux estimation value is determined as the target stator flux value.

[0127] In formula (10), the rotor flux amplitude ψ f , the inductance matrix L is known, and the unknowns are the estimated values ​​of the stator flux and the Lagrange multiplier λ. Solving equation (10) yields the solution to the second functional equation.

[0128] In the solution process, the first two equations of formula (10) can be solved to obtain and

[0129]

[0130] Substituting formula (11) back to the third formula of formula (10), we get λ:

[0131]

[0132] λ takes positive values:

[0133]

[0134] Therefore, in the actual solution process, the stator current and the theoretical value of the stator flux can be substituted into formula (13) to obtain the corresponding Lagrange multiplier λ, and then the stator current, the theoretical value of the stator flux and the Lagrange multiplier λ can be substituted into formula (11) to obtain and That is the estimated value of the target stator flux.

[0135] S107: determining the rotation speed of the motor according to the target stator flux value;

[0136] First, the electrical angle of the motor is determined according to the target stator flux value, and then the electrical angle is input into the phase-locked loop to obtain the motor speed.

[0137] Specifically, the electrical angle of the motor is obtained by the trigonometric formula:

[0138]

[0139] Then the electrical angle Input the phase-locked loop to get the motor speed The speed of the motor It is obtained by the target stator flux value, which removes the interference and makes the motor speed It also removes interference and is more precise.

[0140] S108: Control the motor according to the rotation speed of the motor.

[0141] Motor speed Characterize the actual speed of the motor. A vector control algorithm can be used to control the speed of the motor. To control the motor. Specifically, the target speed can be set, and then the target speed (the set value of the motor speed) and the motor speed can be used to control the motor. The deviation value of (the feedback value of the motor speed) generates a corresponding PWM signal, and the PWM signal passes through the inverter to control the change of the motor speed and adjust the motor speed to the target speed.

[0142] In summary, the permanent magnet synchronous motor control method takes the rotor flux as a constant value and is not related to the rotor speed. It takes the first deviation function as zero as a constraint condition, accurately estimates the target stator flux value after removing interference, and then determines the motor speed based on the target stator flux value after removing interference, thereby improving the accuracy of motor speed estimation and enabling more accurate control of the motor.

[0143] It should be noted that in each of the above embodiments, there is not necessarily a certain order between the above steps. A person skilled in the art can understand, based on the description of the embodiments of the present application, that in different embodiments, the above steps may have different execution orders, that is, they may be executed in parallel, may be executed interchangeably, and so on.

[0144] As another aspect of the embodiment of the present application, the embodiment of the present application provides a permanent magnet synchronous motor control device. The permanent magnet synchronous motor control device can be a software module, and the software module includes a number of instructions, which are stored in a memory in the electric regulator. The processor can access the memory and call the instructions for execution to complete the permanent magnet synchronous motor control method described in the above embodiments.

[0145] In some embodiments, the permanent magnet synchronous motor control device can also be constructed by hardware devices. For example, the permanent magnet synchronous motor control device can be constructed by one or more chips, and each chip can work in coordination with each other to complete the permanent magnet synchronous motor control method described in the above embodiments. For another example, the permanent magnet synchronous motor control device can also be constructed by various logic devices, such as a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), a single-chip microcomputer, an ARM (Acorn RISC Machine) or other programmable logic devices, discrete gates or transistor logic, discrete hardware components, or any combination of these components.

[0146] See also Figure 5 , Figure 5 An embodiment of the present application provides a permanent magnet synchronous motor control device, which includes a permanent magnet synchronous motor control device 200 including an acquisition module 201, a first determination module 202, a definition module 203, a second determination module 204, a construction module 205, a calculation module 206, a third determination module 207 and a control module 208.

[0147] Among them, the acquisition module 201 is used to obtain the stator current of the motor in a two-phase stationary coordinate system. The first determination module 202 is used to determine the stator flux theoretical value of the motor according to the stator current. The definition module 203 is used to define the stator flux estimation function of the motor, and the variable is the stator flux estimation value, wherein the stator flux estimation value is the stator flux value after removing interference from the stator flux theoretical value. The second determination module 204 is used to determine the rotor flux characteristic value according to the stator flux estimation function of the motor, wherein the rotor flux characteristic value is positively correlated with the rotor flux amplitude of the motor. The construction module 205 is used to construct a first deviation function and a second deviation function, wherein the first deviation function is the deviation between the rotor flux characteristic value and the rotor flux amplitude, and the second deviation function is the deviation between the stator flux estimation function and the stator flux theoretical value. The obtaining module 206 is used to obtain the stator flux estimation value when the second deviation function is a minimum value, and determine the stator flux estimation value that satisfies the constraint condition as the target stator flux value, wherein the constraint condition is that the first deviation function is zero. The third determining module 207 is used to determine the speed of the motor according to the target stator flux value. The control module 208 is used to control the motor according to the speed of the motor.

[0148] Therefore, the permanent magnet synchronous motor control device takes the rotor flux as a constant value and the characteristic that it is not related to the rotor speed. It takes the first deviation function to be zero as a constraint condition, accurately estimates the target stator flux value after removing interference, and then determines the motor speed based on the target stator flux value after removing interference, thereby improving the accuracy of the motor speed estimation and enabling more accurate control of the motor.

[0149] It should be noted that, since the permanent magnet synchronous motor control device 200 and the permanent magnet synchronous motor control method in the above embodiment are based on the same application concept, the corresponding contents in the above method embodiment are also applicable to the device embodiment and will not be described in detail here.

[0150] The present application also provides a non-transitory computer-readable storage medium, wherein the non-transitory computer-readable storage medium stores computer-executable instructions, and the computer-executable instructions are executed by one or more processors, for example Figure 2 A processor 4021 in the embodiment may enable the one or more processors to execute the permanent magnet synchronous motor control method in any of the above method embodiments.

[0151] An embodiment of the present application also provides a computer program product, which includes a computer program stored on a non-transitory computer-readable storage medium, and the computer program includes program instructions. When the program instructions are executed by the controller 402, the controller 402 executes any one of the permanent magnet synchronous motor control methods.

[0152] In summary, the permanent magnet synchronous motor control method takes the rotor flux as a constant value and is not related to the rotor speed. It takes the first deviation function as zero as a constraint condition, accurately estimates the target stator flux value after removing interference, and then determines the motor speed based on the target stator flux value after removing interference, thereby improving the accuracy of motor speed estimation and enabling more accurate control of the motor.

[0153] The above described device or equipment embodiments are merely illustrative, wherein the unit modules described as separate components may or may not be physically separated, and the components displayed as module units may or may not be physical units, that is, they may be located in one place, or may be distributed on multiple network module units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present embodiment.

[0154] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a general hardware platform, and of course, by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the relevant technology can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the permanent magnet synchronous motor control method described in each embodiment or some parts of the embodiment.

[0155] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Under the concept of the present application, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes in different aspects of the present application as described above, which are not provided in detail for the sake of simplicity. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some of the technical features can be replaced by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A permanent magnet synchronous motor control method, characterized in that: The method comprises: Obtain the stator current of the motor in a two-phase stationary coordinate system; Determining a theoretical value of a stator flux of the motor according to the stator current; A stator flux estimation value function of the motor is defined, wherein the variable is the stator flux estimation value, wherein the stator flux estimation value is the stator flux value after removing interference from the stator flux theoretical value; Determining a rotor flux characteristic value according to a stator flux estimation function of the motor, wherein the rotor flux characteristic value is positively correlated with a rotor flux amplitude of the motor; Constructing a first deviation function and a second deviation function, wherein the first deviation function is a deviation between the rotor flux characteristic value and the rotor flux amplitude, and the second deviation function is a deviation between the stator flux estimation value function and the stator flux theoretical value; Obtaining the stator flux estimation value when the second deviation function is a minimum value, and determining the stator flux estimation value satisfying a constraint condition as a target stator flux value, wherein the constraint condition is that the first deviation function is zero; Determining the rotation speed of the motor according to the target stator flux value; The motor is controlled according to the rotation speed of the motor.

2. The method according to claim 1, characterized in that: Determining a theoretical value of a stator flux of the motor according to the stator current includes: Inputting the stator current into the current loop to obtain the stator voltage of the motor; The theoretical value of the stator flux of the motor is obtained by the following formula: pψ αβ =-R s i αβ +v αβ ; Among them, p is the differential operator, ψ αβ =[ψ α ,ψ β ] T is the theoretical value of stator flux, i αβ =[i α ,i β ] T ,v αβ =[v α ,v β ] T are the stator current and stator voltage of the motor in the two-phase stationary coordinate system, R s is the stator phase resistance.

3. The method according to claim 2, characterized in that The determining of the rotor flux characteristic value according to the stator flux estimation value function of the motor comprises: The rotor flux characteristic value of the motor is obtained by the following formula: in, is the rotor flux characteristic value, is the estimated value of the stator flux, is the inductance matrix, L0=(L d +L q ) / 2 is the average inductance, L1=(L d -L q ) / 2 is the differential inductance, L d ,L q is the d-axis and q-axis inductance, θ e is the rotor electrical angle.

4. The method according to claim 3, characterized in that The constructing of the first deviation function comprises: The first deviation function is constructed by the following formula: in, is the first deviation function, is the rotor flux eigenvalue, || || is the Euclidean norm, ψ f is the rotor flux amplitude.

5. The method according to claim 3, characterized in that: The constructing of the second deviation function comprises: The second deviation function is constructed by the following formula: in, is the second deviation function, is the estimated value of the stator flux, ψ αβ =[ψ α ,ψ β ] T is the theoretical value of the stator flux.

6. The method according to claim 1, characterized in that The step of obtaining the stator flux estimation value when the second deviation function is a minimum value, and determining the stator flux estimation value satisfying the constraint condition as a target stator flux value, includes: Taking the first deviation function being zero as a constraint condition and the second deviation function as the objective function, the following Lagrangian function is constructed: Among them, L m is the Lagrangian function, is the second deviation function, is the first deviation function, λ is the Lagrange multiplier; The stator flux theoretical value and the stator current are substituted into the Lagrangian function to obtain the target stator flux value.

7. The method according to claim 6, characterized in that Substituting the stator flux theoretical value and the stator current into the Lagrangian function to obtain the target stator flux value includes: Solve the partial derivatives of the Lagrangian function and set the partial derivatives equal to zero to construct the following first functional equation: in, is the gradient operator; Based on the first functional equation, the second functional equation is obtained: in, is the estimated value of the stator flux, ξ αβ =[ξ α ,ξ β ] T is the theoretical value of the stator flux, i αβ =[i α ,i β ] T is the stator current of the motor in the two-phase stationary coordinate system, is the inductance matrix, L0=(L d +L q ) / 2 is the average inductance, L1=(L d -L q ) / 2 is the differential inductance, L d ,L q is the d-axis and q-axis inductance, θ e is the rotor electrical angle, λ is the Lagrange multiplier, ψ f is the rotor flux amplitude; Substitute the stator flux theoretical value and the stator current into the second functional equation to obtain a solution to the stator flux estimation value, and determine the solution to the stator flux estimation value as the target stator flux value.

8. The method according to claim 1, characterized in that: The step of determining the rotation speed of the motor according to the target stator flux value includes: Determining the electrical angle of the motor according to the target stator flux value; The electrical angle is input into a phase-locked loop to obtain the rotational speed of the motor.

9. A controller, characterized in that: The controller comprises: At least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the permanent magnet synchronous motor control method as described in any one of claims 1-8.

10. A compressor, characterized in that: It comprises a permanent magnet synchronous motor and a controller as claimed in claim 9, wherein the permanent magnet synchronous motor is connected to the controller.

11. A household appliance, characterized in that: The invention comprises a whole machine controller and the compressor according to claim 10, wherein the whole machine controller is connected to the compressor.

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