Refrigerator and Method for Optimizing the Positioning Angle of a Motor

Abstract

The present invention discloses a refrigerator and a method for optimizing the positioning angle of a motor. The refrigerator includes: a compressor, whose driving mechanism is a motor; a controller, which is configured to: when receiving a start command, control the rotor of the motor to rotate until it is determined that the rotor rotates to the positioning angle, then control the motor to start dragging and obtain the back electromotive force parameter of the motor; wherein, the initial value of the positioning angle is a preset value; when it is determined that the back electromotive force parameter is not lower than a preset threshold, the positioning angle is corrected according to a preset correction value. By adopting the embodiment of the present invention, the problem that the compressor is difficult to start or cannot start can be effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of household appliances, and particularly to a refrigerator and a method for optimizing the positioning angle of a motor. Background Art

[0002] Currently, motors of compressors in refrigerators, air conditioners, etc. or motors of washing machines, etc. usually adopt Field-Oriented Control (FOC) to achieve variable frequency control. FOC can precisely control the magnitude and direction of the magnetic field, making the motor torque stable, with low noise, high efficiency, and having a high-speed dynamic response. During the process of controlling the motor operation through FOC, the starting process of the motor generally includes several stages such as positioning, dragging, and closed-loop control. Among them, the positioning angle of the motor in the positioning stage is generally a fixed predetermined angle, and when starting with a large load, the fixed predetermined angle easily causes difficulties or inability to start the compressor. Summary of the Invention

[0003] An embodiment of the present invention provides a refrigerator and a method for optimizing the positioning angle of a motor, which can effectively solve the problem of difficult or impossible start of the compressor.

[0004] An embodiment of the present invention provides a refrigerator, including:

[0005] A compressor, whose driving mechanism is a motor;

[0006] A controller, which is used for:

[0007] When receiving a start command, controlling the rotation of the rotor of the motor until it is determined that the rotor rotates to the positioning angle, then controlling the motor to start by dragging, and obtaining the back electromotive force parameter of the motor; wherein, the initial value of the positioning angle is a preset value;

[0008] When it is determined that the back electromotive force parameter is not lower than a preset threshold, correcting the positioning angle according to a preset correction value.

[0009] Compared with the prior art, the refrigerator disclosed in the embodiment of the present invention detects the back electromotive force parameter of the motor when its rotor rotates to the positioning angle, and compares the back electromotive force parameter with a preset threshold to determine whether the positioning angle of the motor at this time is the optimal positioning angle. If the back electromotive force parameter is not lower than the preset threshold, the positioning angle is corrected according to the preset correction value, and then the positioning angle of the motor in the positioning stage is corrected to the target angle, which can effectively optimize the positioning angle of the motor, thereby effectively solving the problem of difficult or impossible start of the compressor.

[0010] As an improvement of the above solution, the back electromotive force parameter is the ratio of the d-axis back electromotive force to the q-axis back electromotive force of the motor.

[0011] In this embodiment, the back electromotive force parameter is the ratio of the d-axis back electromotive force to the q-axis back electromotive force of the motor, which can accurately reflect the operating conditions of the motor.

[0012] As an improvement to the above solution, obtaining the back electromotive force parameter of the motor includes:

[0013] Obtaining the stator current and stator voltage of the α-axis and β-axis of the motor;

[0014] According to the stator current and stator voltage of the α-axis and β-axis of the motor, and the stator resistance and stator inductance of the motor obtained in advance, calculating the α-axis back electromotive force and β-axis back electromotive force of the motor;

[0015] According to the positioning angle, the α-axis back electromotive force and the β-axis back electromotive force, calculating the d-axis back electromotive force and the q-axis back electromotive force;

[0016] Calculating the ratio of the d-axis back electromotive force to the q-axis back electromotive force to obtain the back electromotive force parameter of the motor.

[0017] In this embodiment, by obtaining the stator current and stator voltage of the α-axis and β-axis of the motor when its rotor rotates to a certain preset angle, and combining the stator resistance and stator inductance of the motor obtained in advance, calculating the α-axis back electromotive force and β-axis back electromotive force, and then combining the α-axis back electromotive force, β-axis back electromotive force and this preset angle, calculating the d-axis back electromotive force and q-axis back electromotive force corresponding to this preset angle, the back electromotive force parameter corresponding to this preset angle can be accurately calculated, thereby improving the accuracy of determining the optimal positioning angle.

[0018] As an improvement to the above solution, the calculation formula for the α-axis back electromotive force is:

[0019] E α =V α –R s I α –L s dI α / dt;

[0020] The calculation formula for the β-axis back electromotive force is:

[0021] E β =V β –R s I β –L s dI β / dt;

[0022] Wherein, E α is the α-axis back electromotive force; E β are respectively the β-axis back electromotive force; V αis the stator voltage of the α-axis of the motor; V β is the stator voltage of the β-axis of the motor; I α is the stator current of the α-axis of the motor; I β is the stator current of the β-axis of the motor; R s is the stator resistance of the motor; L s is the stator inductance of the motor.

[0023] As an improvement of the above solution, the calculation formula for the back electromotive force of the d-axis is:

[0024] E d = E α cos(θ esti ) + E β sin(θ esti );

[0025] The calculation formula for the back electromotive force of the q-axis is:

[0026] E q = E β cos(θ esti ) - E α sin(θ esti );

[0027] Among them, E d is the back electromotive force of the d-axis; E q is the back electromotive force of the q-axis; E α is the back electromotive force of the α-axis; E β are respectively the back electromotive forces of the β-axis; θ esti is the positioning angle.

[0028] Another embodiment of the present invention provides a method for optimizing the positioning angle of a motor, including:

[0029] When a start command is received, control the rotor of the motor to rotate until it is determined that the rotor rotates to the positioning angle, then control the motor to start dragging, and obtain the back electromotive force parameters of the motor; among them, the initial value of the positioning angle is a preset value;

[0030] When it is determined that the back electromotive force parameters are not lower than the preset threshold, correct the positioning angle according to the preset correction value.

[0031] Compared with the prior art, the method for optimizing the positioning angle of the motor disclosed in the embodiments of the present invention detects the back electromotive force parameters of the motor when its rotor rotates to the positioning angle, and compares the back electromotive force parameters with a preset threshold value to determine whether the positioning angle of the motor at this time is the optimal positioning angle. If the back electromotive force parameters are not lower than the preset threshold value, the positioning angle is corrected according to a preset correction value, and then the positioning angle of the motor in the positioning stage is corrected to the target angle, which can effectively optimize the positioning angle of the motor, thereby effectively solving the problem that the compressor is difficult to start or cannot start.

[0032] As an improvement of the above solution, the back electromotive force parameter is the ratio of the d-axis back electromotive force to the q-axis back electromotive force of the motor.

[0033] In this embodiment, the back electromotive force parameter is the ratio of the d-axis back electromotive force to the q-axis back electromotive force of the motor, which can accurately reflect the operating condition of the motor.

[0034] As an improvement of the above solution, the obtaining of the back electromotive force parameters of the motor includes:

[0035] Obtaining the stator current and stator voltage of the α-axis and β-axis of the motor;

[0036] According to the stator current and stator voltage of the α-axis and β-axis of the motor, and the stator resistance and stator inductance of the motor obtained in advance, calculating the α-axis back electromotive force and β-axis back electromotive force of the motor;

[0037] According to the positioning angle, the α-axis back electromotive force and the β-axis back electromotive force, calculating the d-axis back electromotive force and the q-axis back electromotive force;

[0038] Calculating the ratio of the d-axis back electromotive force to the q-axis back electromotive force to obtain the back electromotive force parameter of the motor.

[0039] As an improvement of the above solution, the calculation formula for the α-axis back electromotive force is:

[0040] E α =V α –R s I α –L s dI α / dt;

[0041] The calculation formula for the β-axis back electromotive force is:

[0042] E β =V β –R s I β –L s dI β / dt;

[0043] Among them, E α is the back electromotive force of the α-axis; E β are respectively the back electromotive forces of the β-axis; V α is the stator voltage of the α-axis of the motor; V β is the stator voltage of the β-axis of the motor; I α is the stator current of the α-axis of the motor; I β is the stator current of the β-axis of the motor; R s is the stator resistance of the motor; L s is the stator inductance of the motor.

[0044] As an improvement of the above solution, the calculation formula of the back electromotive force of the d-axis is:

[0045] E d = E α cos(θ esti ) + E β sin(θ esti );

[0046] The calculation formula of the back electromotive force of the q-axis is:

[0047] E q = E β cos(θ esti ) - E α sin(θ esti );

[0048] Among them, E d is the back electromotive force of the d-axis; E q is the back electromotive force of the q-axis; E α is the back electromotive force of the α-axis; E β are respectively the back electromotive forces of the β-axis; θ esti is the positioning angle. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 is a schematic structural diagram of a refrigerator provided by an embodiment of the present invention;

[0050] Figure 2 is a schematic internal structure diagram of a refrigerator provided by an embodiment of the present invention;

[0051] Figure 3 is a schematic structural diagram of a compressor provided by an embodiment of the present invention;

[0052] Figure 4 is a phase current curve diagram of the refrigerator provided by an embodiment of the present invention when starting at different positioning angles;

[0053] Figure 5 It is a schematic structural diagram of a FOC control circuit provided by an embodiment of the present invention;

[0054] Figure 6 It is a schematic diagram of the specific process of a controller of a refrigerator provided by an embodiment of the present invention;

[0055] Figure 7 It is a schematic diagram of the process of an optimized method for the positioning angle of a motor provided by an embodiment of the present invention. Specific embodiments

[0056] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts belong to the scope of protection of the present invention.

[0057] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0058] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0059] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0060] See Figure 1 , which is a schematic structural diagram of a refrigerator provided by an embodiment of the present invention.

[0061] An embodiment of the present invention provides a refrigerator, including:

[0062] A compressor 100, whose driving mechanism is a motor 101;

[0063] The controller 200 is used to:

[0064] When a start command is received, the rotor of the motor 101 is controlled to rotate until it is determined that the rotor rotates to a positioning angle, the motor 101 is controlled to start by dragging, and a back electromotive force parameter of the motor 101 is obtained; wherein the initial value of the positioning angle is a preset value;

[0065] When it is determined that the back electromotive force parameter is not lower than a preset threshold, the positioning angle is corrected according to a preset correction value.

[0066] For example, see Figure 2 The compressor 100 is usually located at the bottom of the back of the refrigerator, and the outer shell is fixed on the bottom plate and connected to the refrigerator refrigeration pipeline through two pipe openings.

[0067] In a specific embodiment, the refrigerator provided by the embodiment of the present invention may also include a condenser, an anti-condensation tube, a drying filter, a capillary tube, an evaporator and a gas-liquid separator. The refrigeration working process of the refrigerator provided by this embodiment includes a compression process, a condensation process, a throttling process and an evaporation process. Among them, the compression process is: plug in the power cord of the refrigerator, when the contacts of the thermostat are connected, the compressor 100 starts to work, and the low-temperature and low-pressure refrigerant is sucked into the compressor 100, and is compressed into a high-temperature and high-pressure superheated gas in the cylinder of the compressor 100 and then discharged into the condenser; the condensation process is: the high-temperature and high-pressure refrigerant gas dissipates heat through the condenser, the temperature continues to drop, and is gradually cooled to a saturated vapor of normal temperature and high pressure, and is further cooled to a saturated liquid, and the temperature no longer drops. The temperature at this time is called the condensation temperature, and the pressure of the refrigerant remains almost unchanged during the entire condensation process. ; The throttling process is: the saturated liquid refrigerant after condensation is filtered out of moisture and impurities by a drying filter and then flows into the capillary tube, through which throttling and pressure reduction are performed, and the refrigerant becomes wet steam at room temperature and low pressure; the evaporation process is: the wet steam at room temperature and low pressure begins to absorb heat and vaporize in the evaporator, which not only reduces the temperature of the evaporator and its surroundings, but also turns the refrigerant into a low-temperature, low-pressure gas. The refrigerant coming out of the evaporator passes through the gas-liquid separator and returns to the compressor 100 again, and the above process is repeated to transfer the heat in the refrigerator to the air outside the box, thereby achieving the purpose of refrigeration.

[0068] For example, the compressor 100 of the refrigerator provided in this embodiment is a reciprocating compressor 100, such as Figure 3As shown in the figure, it includes: a motor 101, a crankshaft 5, a connecting rod 4, a piston 2, a slider 3, a cylinder 1, an intake valve 6, and an exhaust valve 7. After the motor 101 starts, the motor 101 drives the crankshaft 5, the crankshaft 5 drives the connecting rod 4, the connecting rod 4 drives the piston 2, and the piston 2 moves up and down. The movement of the piston 2 causes the volume inside the cylinder 1 to change. When the piston 2 moves downward, the volume of the cylinder 1 increases, the intake valve 6 opens, the exhaust valve 7 closes, and air is drawn in to complete the intake process; when the piston 2 moves upward, the volume of the cylinder 1 decreases, the exhaust valve 7 opens, the intake valve 6 closes, and the compression process is completed.

[0069] It should be noted that the back electromotive force refers to the electromotive force generated by the tendency to resist the change of current. When the motor 101 starts initially, the excitation winding establishes a magnetic field, and the armature current generates another magnetic field. The two magnetic fields interact to start the operation of the motor 101. The armature winding rotates in the magnetic field, so the generator 101 effect is generated. Actually, the rotating armature generates an induced electromotive force, which is opposite in polarity to the armature voltage. This self-induced electromotive force is called the back electromotive force. The back electromotive force consumes the electrical energy in the circuit. When the back electromotive force parameter is too large, the power cannot meet the normal operation requirements of the load, and stalling is likely to occur. Therefore, in this embodiment, when the rotor rotates to the positioning angle, by judging whether the back electromotive force parameter after positioning is not lower than the preset threshold, it is determined whether the current positioning angle is the optimal positioning angle. If so, it means that the motor 101 is prone to stalling at this time. Correcting the positioning angle can prevent the motor 101 from stalling, thus ensuring the smooth start of the compressor 100. Moreover, it can also achieve the effect of positioning and starting with a smaller current, thereby reducing the impact noise during startup and avoiding damage and carbonization of the compressor 100 coil caused by large-current positioning. In this embodiment, the preset threshold can be set according to the pre-stall determination value of the motor 101, which is not limited here.

[0070] It should be noted that in this embodiment, the preset correction value can be selected from 1 - 359° according to actual needs. For example, it can be 1°, 10°, 15°, 30°, 45°, 60°, etc., which is not limited here. The initial value of the positioning angle of the motor 101 can be 0 - 360°. For example, it can be 0°, 10°, 15°, 30°, 45°, 60°, 360°, etc., which is not limited here. Preferably, in this embodiment, the preset correction value is 30°, and the initial value of the positioning angle of the motor 101 is 0°. As Figure 3 shown, if the initial value of the positioning angle of the motor 101 is the angle at point A and the preset correction value is 30°, then the corrected positioning angle at the first start is 30° at point B, and the corrected positioning angle at the second start is 60° at point C, and so on to obtain points D, E, F, G. The phase current for starting the motor 101 with the positioning angles from A to G is as Figure 4as shown

[0071] Compared with the prior art, the refrigerator disclosed in the embodiment of the present invention detects the back electromotive force parameter of the motor 101 when its rotor rotates to the positioning angle, and compares the back electromotive force parameter with a preset threshold value to determine whether the positioning angle of the motor 101 at this time is the optimal positioning angle. If the back electromotive force parameter is not lower than the preset threshold value, the positioning angle is corrected according to a preset correction value, and then the positioning angle of the motor 101 in the positioning stage is corrected to the target angle, which can effectively optimize the positioning angle of the motor 101, thereby effectively solving the problem that the compressor 100 is difficult to start or cannot start.

[0072] As an optional embodiment, the back electromotive force parameter is the ratio of the d-axis back electromotive force to the q-axis back electromotive force of the motor 101.

[0073] In this embodiment, the back electromotive force parameter is the ratio of the d-axis back electromotive force to the q-axis back electromotive force of the motor 101, which can accurately reflect the operating condition of the motor 101.

[0074] See Figure 5 , in this embodiment, the motor 101 adopts the FOC algorithm. The specific algorithm process is as follows: the three-phase currents Ia, Ib, and Ic flowing through the PMSM motor 101 can be obtained through the sampling resistor R. After Clarke transformation, Iα and Iβ are obtained, and then through Park transformation, they are converted into Iq and Id. On the other hand, according to Iα and Iβ, the actual speed ω is estimated through an estimator, compared with the set speed, and after PI adjustment, the reference Iq and Id currents are output. After current loop PI adjustment, the actual Vq and Vd are output. After inverse Clarke and inverse Park transformations, and SVM modulation, finally, a three-phase bridge is output to drive the motor 101. There are two closed loops in the FOC control algorithm. One is the current closed loop, including the Q-axis current loop and the D-axis current loop. The other is the speed loop. The current loop is the outer loop, and the speed loop is the inner loop. Both closed loops are achieved through PI adjustment. The current loop adjustment is for torque and excitation, and the speed loop adjustment is for speed.

[0075] Further, the obtaining of the back electromotive force parameter of the motor 101 includes:

[0076] Obtaining the stator current and stator voltage of the α-axis and β-axis of the motor 101;

[0077] According to the stator current and stator voltage of the α-axis and β-axis of the motor 101, and the stator resistance and stator inductance of the motor 101 obtained in advance, the α-axis back electromotive force and β-axis back electromotive force of the motor 101 are calculated;

[0078] Based on the positioning angle, the α-axis back electromotive force, and the β-axis back electromotive force, the d-axis back electromotive force and the q-axis back electromotive force are calculated.

[0079] Calculate the ratio of the d-axis back electromotive force to the q-axis back electromotive force to obtain the back electromotive force parameter of the motor 101.

[0080] In this embodiment, by obtaining the stator current and stator voltage of the α-axis and β-axis of the motor 101 when its rotor rotates to a certain preset angle, and combining the stator resistance and stator inductance of the motor 101 obtained in advance, the α-axis back electromotive force and the β-axis back electromotive force are calculated. Then, combining the α-axis back electromotive force, the β-axis back electromotive force, and this preset angle, the d-axis back electromotive force and the q-axis back electromotive force corresponding to this preset angle are calculated, which can accurately calculate the back electromotive force parameter corresponding to this preset angle, thereby improving the accuracy of determining the optimal positioning angle.

[0081] Specifically, the calculation formula for the α-axis back electromotive force is:

[0082] E α = V α –R s I α –L s dI α / dt;

[0083] The calculation formula for the β-axis back electromotive force is:

[0084] E β = V β –R s I β –L s dI β / dt;

[0085] Wherein, E α is the α-axis back electromotive force; E β are respectively the β-axis back electromotive force; V α is the α-axis stator voltage of the motor 101; V β is the β-axis stator voltage of the motor 101; I α is the α-axis stator current of the motor 101; I β is the β-axis stator current of the motor 101; R s is the stator resistance of the motor 101; L s is the stator inductance of the motor 101.

[0086] Specifically, the calculation formula for the d-axis back electromotive force is:

[0087] E d = E α cos(θesti ) + E β sin(θ esti );

[0088] The calculation formula for the q - axis back electromotive force is as follows:

[0089] E q = E β cos(θ esti ) - E α sin(θ esti );

[0090] Among them, E d is the d - axis back electromotive force; E q is the q - axis back electromotive force; E α is the α - axis back electromotive force; E β are respectively the β - axis back electromotive forces; θ esti is the positioning angle.

[0091] See Figure 6 , the following takes a specific embodiment to illustrate the working process of the controller 200 of the refrigerator provided in this embodiment:

[0092] S11. When receiving a start instruction, control the rotor of the motor 101 to rotate;

[0093] S12. Determine whether the rotor rotates to the positioning angle. If so, enter step S13;

[0094] S13. Control the motor 101 to start by dragging and obtain the back - electromotive - force parameters of the motor 101;

[0095] S14. Determine whether the back - electromotive - force parameters are not lower than a preset threshold. If so, enter step S15; otherwise, end this process;

[0096] S15. Correct the positioning angle according to a preset correction value and end this process.

[0097] See Figure 7 , which is a schematic flow chart of a method for optimizing the positioning angle of a motor provided in an embodiment of the present invention.

[0098] The embodiment of the present invention provides a method for optimizing the positioning angle of a motor, including:

[0099] S21. When receiving a start instruction, control the rotor of the motor to rotate until it is determined that the rotor rotates to the positioning angle, then control the motor to start by dragging and obtain the back - electromotive - force parameters of the motor; wherein, the initial value of the positioning angle is a preset value;

[0100] S22. When it is determined that the back electromotive force parameter is not lower than the preset threshold, the positioning angle is corrected according to the preset correction value.

[0101] It should be noted that the back electromotive force refers to the electromotive force generated by the tendency to resist the change of current. When the motor 101 starts initially, the excitation winding establishes a magnetic field, and the armature current generates another magnetic field. The two magnetic fields interact to start the operation of the motor 101. The armature winding rotates in the magnetic field, so a generator effect is generated. In fact, the rotating armature generates an induced electromotive force, which is opposite to the polarity of the armature voltage. This self-induced electromotive force is called the back electromotive force. The back electromotive force consumes the electrical energy in the circuit. When the back electromotive force parameter is too large, the power cannot meet the normal operation requirements of the load, and stalling is likely to occur. Therefore, in this embodiment, when the rotor rotates to the positioning angle, by determining whether the back electromotive force parameter after positioning is not lower than the preset threshold, it is determined whether the current positioning angle is the optimal positioning angle. If so, it means that the motor 101 is prone to stalling at this time. Correcting the positioning angle can prevent the motor 101 from stalling, thereby ensuring the smooth start of the compressor 100. In this embodiment, the preset threshold can be set according to the stalling determination previous value of the motor 101, which is not limited here.

[0102] It should be noted that in this embodiment, the preset correction value can be selected from 1 - 359° according to actual needs. For example, it can be 1°, 10°, 15°, 30°, 45°, 60°, etc., which is not limited here. The initial value of the positioning angle of the motor can be 0 - 360°. For example, it can be 0°, 10°, 15°, 30°, 45°, 60°, 360°, etc., which is not limited here. Preferably, in this embodiment, the preset correction value is 30°, and the initial value of the positioning angle of the motor is 0°. As Figure 3 shown, if the initial value of the positioning angle of the motor is the angle at point A and the preset correction value is 30°, then the corrected positioning angle at the first start is 30° at point B, and the corrected positioning angle at the second start is 60° at point C, and so on to obtain points D, E, F, G. The phase current of the motor starting with the positioning angle from A to G is as Figure 4 shown.

[0103] Compared with the prior art, the motor positioning angle optimization method disclosed in the embodiment of the present invention detects the back electromotive force parameter of the motor when its rotor rotates to the positioning angle, and compares the back electromotive force parameter with the preset threshold to determine whether the positioning angle of the motor at this time is the optimal positioning angle. If the back electromotive force parameter is not lower than the preset threshold, the positioning angle is corrected according to the preset correction value, and then the positioning angle of the motor in the positioning stage is corrected to the target angle, which can effectively optimize the positioning angle of the motor, thereby effectively solving the problem of difficult or impossible start of the compressor.

[0104] As one of the optional embodiments, the back electromotive force parameter is the ratio of the d-axis back electromotive force to the q-axis back electromotive force of the motor.

[0105] In this embodiment, the back electromotive force parameter is the ratio of the d-axis back electromotive force to the q-axis back electromotive force of the motor, which can accurately reflect the operating condition of the motor.

[0106] See Figure 5 , in this embodiment, the motor 101 adopts the FOC algorithm. The specific algorithm process is as follows: The three-phase currents Ia, Ib, and Ic flowing through the PMSM motor 101 can be obtained by sampling the resistor R. After Clarke transformation, Iα and Iβ are obtained, and then through Park transformation, they are converted into Iq and Id. On the other hand, according to Iα and Iβ, the actual rotational speed ω is estimated through an estimator, compared with the set rotational speed, adjusted by PI, the reference Iq and Id currents are output, adjusted by the current loop PI, the actual Vq and Vd are output, and through inverse Clarke and inverse Park transformations, as well as SVM modulation, finally, a three-phase bridge is output to drive the motor 101. There are two closed loops in the FOC control algorithm. One is the current closed loop, including the Q-axis current loop and the D-axis current loop, and the other is the speed loop. The current loop is the outer loop, and the speed loop is the inner loop. Both closed loops are realized through PI adjustment. The current loop adjusts torque and excitation, and the speed loop adjusts the rotational speed.

[0107] Further, obtaining the back electromotive force parameter of the motor includes:

[0108] Obtaining the stator current and stator voltage of the α-axis and β-axis of the motor;

[0109] According to the stator current and stator voltage of the α-axis and β-axis of the motor, and the stator resistance and stator inductance of the motor obtained in advance, the α-axis back electromotive force and β-axis back electromotive force of the motor are calculated;

[0110] According to the positioning angle, the α-axis back electromotive force, and the β-axis back electromotive force, the d-axis back electromotive force and the q-axis back electromotive force are calculated;

[0111] Calculating the ratio of the d-axis back electromotive force to the q-axis back electromotive force to obtain the back electromotive force parameter of the motor.

[0112] Specifically, the calculation formula for the α-axis back electromotive force is:

[0113] E α =V α –R s I α –L s dI α / dt;

[0114] The calculation formula for the back electromotive force of the β-axis is as follows:

[0115] E β = V β – R s I β – L s dI β / dt;

[0116] Wherein, E α is the back electromotive force of the α-axis; E β are respectively the back electromotive force of the β-axis; V α is the stator voltage of the α-axis of the motor; V β is the stator voltage of the β-axis of the motor; I α is the stator current of the α-axis of the motor; I β is the stator current of the β-axis of the motor; R s is the stator resistance of the motor; L s is the stator inductance of the motor.

[0117] Specifically, the calculation formula for the back electromotive force of the d-axis is as follows:

[0118] E d = E α cos(θ esti ) + E β sin(θ esti );

[0119] The calculation formula for the back electromotive force of the q-axis is as follows:

[0120] E q = E β cos(θ esti ) - E α sin(θ esti );

[0121] Wherein, E d is the back electromotive force of the d-axis; E q is the back electromotive force of the q-axis; E α is the back electromotive force of the α-axis; E β are respectively the back electromotive force of the β-axis; θ esti is the positioning angle.

[0122] It should be noted that the positioning angle optimization method for the motor provided in this embodiment can be applied to the motors of compressors in household appliances such as refrigerators and air conditioners, or to the motors of household appliances such as washing machines. Of course, it can also be applied to other devices with motors, which is not limited here. The specific description of the positioning angle optimization method for the motor provided in this embodiment can refer to the above device embodiment and will not be elaborated here.

[0123] Another embodiment of the present invention further provides a controller. The controller of this embodiment includes: a processor, a memory, and a computer program stored in the memory and executable on the processor, such as the positioning angle optimization method of the motor in the above method embodiment. When the processor executes the computer program, the steps in the above embodiments of the positioning angle optimization method of each motor are implemented.

[0124] Exemplarily, the computer program may be divided into one or more modules / units, and the one or more modules / units are stored in the memory and executed by the processor to complete the present invention. The one or more modules / units may be a series of computer program instruction segments capable of performing specific functions, and the instruction segments are used to describe the execution process of the computer program in the controller.

[0125] The controller may include, but is not limited to, a processor and a memory. Those skilled in the art can understand that the schematic diagram is only an example of the controller and does not constitute a limitation on the controller. It may include more or fewer components than shown, or combine certain components, or different components. For example, the controller may further include input / output devices, network access devices, buses, etc.

[0126] The so-called processor may be a central processing unit (CPU), or may also be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc. The processor is the control center of the controller and connects various parts of the entire controller through various interfaces and lines.

[0127] The memory can be used to store the computer programs and / or modules. By running or executing the computer programs and / or modules stored in the memory and invoking the data stored in the memory, the processor realizes various functions of the controller. The memory may include high-speed random access memory and may also include non-volatile memory, such as a hard disk, internal memory, plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, Flash Card, at least one magnetic disk storage device, flash memory device, or other volatile solid-state storage devices.

[0128] Wherein, if the modules / units integrated in the controller are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on such an understanding, to implement all or part of the processes in the above-described embodiment methods of the present invention, it can also be completed by a computer program instructing relevant hardware. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, the steps of the above-described method embodiments can be realized. Among them, the computer program includes computer program code, and the computer program code can be in the form of source code, object code, executable file, or some intermediate form, etc. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disc, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal, and software distribution medium, etc. It should be noted that the content included in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium does not include electrical carrier signals and telecommunication signals.

[0129] It should be noted that the device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. In addition, in the attached drawings of the device embodiments provided by the present invention, the connection relationships between the modules indicate that they have communication connections, which can be specifically implemented as one or more communication buses or signal lines. Those of ordinary skill in the art can understand and implement it without creative efforts.

[0130] The above are the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present invention.

Claims

1. A refrigerator, characterized in that, Including: A compressor, whose drive mechanism is a motor; A controller, which is used for: When receiving a start instruction, controlling the rotation of the rotor of the motor until it is determined that the rotor rotates to a positioning angle, then controlling the motor to start by dragging, and obtaining the back electromotive force parameter of the motor; wherein, the initial value of the positioning angle is a preset value; When it is determined that the back electromotive force parameter is not lower than a preset threshold, correcting the positioning angle according to a preset correction value; The back electromotive force parameter is the ratio of the d-axis back electromotive force to the q-axis back electromotive force of the motor.

2. The refrigerator according to claim 1, wherein The obtaining of the back electromotive force parameter of the motor includes: Obtaining the stator current and stator voltage of the α-axis and β-axis of the motor; According to the stator current and stator voltage of the α-axis and β-axis of the motor, and the stator resistance and stator inductance of the motor obtained in advance, calculating the α-axis back electromotive force and β-axis back electromotive force of the motor; According to the positioning angle, the α-axis back electromotive force and the β-axis back electromotive force, calculating the d-axis back electromotive force and the q-axis back electromotive force; Calculating the ratio of the d-axis back electromotive force to the q-axis back electromotive force to obtain the back electromotive force parameter of the motor.

3. The refrigerator according to claim 2, characterized in that, The calculation formula of the α-axis back electromotive force is: E α = V α – R s I α – L s dI α / dt; The calculation formula of the β-axis back electromotive force is: E β = V β – R s I β – L s dI β / dt; where, E α is the back electromotive force of the α-axis; E β are the back electromotive forces of the β-axis respectively; V α is the stator voltage of the α-axis of the motor; V β is the stator voltage of the β-axis of the motor; I α is the stator current of the α-axis of the motor; I β is the stator current of the β-axis of the motor; R s is the stator resistance of the motor; L s is the stator inductance of the motor.

4. The refrigerator according to claim 2, characterized in that, The calculation formula of the d-axis back electromotive force is: E d = E α cos(θ esti ) + E β sin(θ esti ); The calculation formula of the q-axis back electromotive force is: E q = E β cos(θ esti ) - E α sin(θ esti ); Among them, E d is the d-axis back electromotive force; E q is the q-axis back electromotive force; E α is the α-axis back electromotive force; E β are respectively the β-axis back electromotive force; θ esti is the positioning angle.

5. A method for optimizing the positioning angle of an electric motor, characterized in that, Including: When receiving a start instruction, controlling the rotation of the rotor of the motor until it is determined that the rotor rotates to a positioning angle, then controlling the motor to start by dragging, and obtaining the back electromotive force parameter of the motor; wherein, the initial value of the positioning angle is a preset value; When it is determined that the back electromotive force parameter is not lower than a preset threshold, correcting the positioning angle according to a preset correction value; The back electromotive force parameter is the ratio of the d-axis back electromotive force to the q-axis back electromotive force of the motor.

6. The positioning angle optimization method of the motor according to claim 5, characterized in that, The obtaining of the back electromotive force parameter of the motor includes: Obtaining the stator current and stator voltage of the α-axis and β-axis of the motor; According to the stator current and stator voltage of the α-axis and β-axis of the motor, and the stator resistance and stator inductance of the motor obtained in advance, calculating the α-axis back electromotive force and β-axis back electromotive force of the motor; According to the positioning angle, the α-axis back electromotive force and the β-axis back electromotive force, calculating the d-axis back electromotive force and the q-axis back electromotive force; Calculating the ratio of the d-axis back electromotive force to the q-axis back electromotive force to obtain the back electromotive force parameter of the motor.

7. The positioning angle optimization method of the motor according to claim 6, characterized in that, The calculation formula of the α-axis back electromotive force is: E α = V α – R s I α – L s dI α / dt; The calculation formula of the β-axis back electromotive force is: E β = V β – R s I β – L s dI β / dt; Among them, E α is the back electromotive force of the α-axis; E β are respectively the back electromotive forces of the β-axis; V α is the stator voltage of the α-axis of the motor; V β is the stator voltage of the β-axis of the motor; I α is the stator current of the α-axis of the motor; I β is the stator current of the β-axis of the motor; R s is the stator resistance of the motor; L s is the stator inductance of the motor.

8. The positioning angle optimization method of the motor according to claim 6, characterized in that, The calculation formula of the d-axis back electromotive force is: E d = E α cos(θ esti ) + E β sin(θ esti ); The calculation formula of the q-axis back electromotive force is: E q = E β cos(θ esti ) - E α sin(θ esti ); where E d is the d-axis back electromotive force; E q is the q-axis back electromotive force; E α is the α-axis back electromotive force; E β are respectively the β-axis back electromotive force; θ esti is the positioning angle.

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