A control method and device of a refrigerator, the refrigerator, and a storage medium

Abstract

The application discloses a refrigerator control method and device, a refrigerator and a storage medium. The method comprises the following steps: determining a first rotating speed and a second rotating speed in a rotating speed range of a motor in a compressor of the refrigerator; wherein a stage less than the first rotating speed is a first rotating speed stage, a stage greater than or equal to the first rotating speed and less than the second rotating speed is a second rotating speed stage, and a stage greater than or equal to the second rotating speed is a third rotating speed stage; acquiring an operating rotating speed of the motor; and according to a rotating speed stage in which the operating rotating speed of the motor is located in the rotating speed range, adopting a pre-set control mode corresponding to the rotating speed stage to adjust a d-axis current of the motor and / or an output voltage of a controller of the motor. According to the scheme, the operating rotating speed of the motor is improved under the condition that the bus voltage of the motor in the refrigerator compressor and the back electromotive force of the motor are unchanged, so that the low-frequency energy efficiency of the refrigerator and the high-frequency freezing capacity of the refrigerator can be considered.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of refrigerators, and particularly relates to a control method and device for a refrigerator compressor motor, a refrigerator, and a storage medium. BACKGROUND

[0002] Most refrigerators have a freezer compartment temperature of -18℃, and some refrigerators can reach a minimum of -24℃. With the upgrading of consumer demand, the preservation requirements for meat ingredients are becoming higher and higher, such as the increasing demand for freezing at -38℃ or below. The quick-freezing mode of ordinary refrigerators cannot meet this consumer demand. The demand for lower freezing temperatures requires the refrigerator compressor to have greater cooling capacity. At the same time, since the cooling capacity demand is small when the temperatures of the various compartments of the refrigerator reach the set value, the compressor is required to have a wider range of cooling capacity.

[0003] In related solutions, when the refrigerator uses a variable frequency compressor (such as a variable frequency piston compressor), the variable frequency piston compressor operates at a speed range of 1200 rpm (i.e., revolutions per minute, indicating the number of rotations per minute of the device) to 4200 rpm. Among them, the variable frequency piston compressor operates at high frequency to quickly pull down the temperature, and the variable frequency piston compressor operates at low frequency to maintain the temperature of each compartment after the temperature is pulled down by quick freezing. The frequency of the variable frequency piston compressor operating at low frequency is generally 20-33 Hz, and the refrigerator operates in this interval most of the time, so the low-frequency energy efficiency is crucial to power consumption.

[0004] However, to improve the energy efficiency of the variable frequency piston compressor of the refrigerator operating at low frequency, the back electromotive force of the motor in the variable frequency piston compressor needs to be improved, and the higher the back electromotive force of the motor, the more difficult it is to increase the high frequency when the variable frequency piston compressor needs to operate at high frequency.

[0005] The above content is only used to assist in understanding the technical solutions of the present application and does not represent the acknowledgement of the above content as prior art. SUMMARY

[0006] The present application aims to provide a control method and device for a refrigerator, a refrigerator, and a storage medium, to solve the problem that the low-frequency energy efficiency of the refrigerator cannot be improved and the freezing capacity of the refrigerator cannot be improved at the same time because the refrigerator needs to operate at high frequency but operates at low frequency most of the time, and to improve the operating speed of the motor by keeping the bus voltage of the motor in the refrigerator compressor and the back electromotive force of the motor unchanged, so as to achieve the effect of improving the low-frequency energy efficiency of the refrigerator and improving the freezing capacity of the refrigerator at the same time.

[0007] The application provides a refrigerator control method, comprising: determining a first rotating speed and a second rotating speed in a rotating speed range of a motor in a compressor of the refrigerator; wherein, in the rotating speed range, a stage less than the first rotating speed is recorded as a first rotating speed stage, a stage greater than or equal to the first rotating speed and less than the second rotating speed is recorded as a second rotating speed stage, and a stage greater than or equal to the second rotating speed is recorded as a third rotating speed stage; during operation of the motor, obtaining an operating rotating speed of the motor; and according to a rotating speed stage in which the operating rotating speed of the motor is located in the rotating speed range, adopting a control mode corresponding to the rotating speed stage and pre-set to adjust a d-axis current of the motor and / or an output voltage of a controller of the motor.

[0008] In some embodiments, the first rotating speed and the second rotating speed in the rotating speed range of the motor in the compressor of the refrigerator are determined by: determining a back electromotive force coefficient of the motor and a bus voltage of the controller of the motor; taking a product of the bus voltage and the back electromotive force coefficient multiplied by a first set calculation coefficient as the first rotating speed; and taking a product of the first rotating speed and a second set calculation coefficient as the second rotating speed.

[0009] In some embodiments, the adjusting of the d-axis current of the motor and / or the output voltage of the controller of the motor according to the rotating speed stage in which the operating rotating speed of the motor is located in the rotating speed range, by adopting the control mode corresponding to the rotating speed stage and pre-set, comprises: if the operating rotating speed of the motor is in the first rotating speed stage, performing optimal control on the d-axis current of the motor to obtain a first optimal d-axis current, so as to control the operation of the motor according to the first optimal d-axis current; if the operating rotating speed of the motor is in the second rotating speed stage, continuing to perform optimal control on the d-axis current of the motor to obtain a second optimal d-axis current, so as to control the operation of the motor according to the second optimal d-axis current; at the same time, performing over-modulation control on the output voltage of the controller of the motor to obtain an over-modulation voltage of the output voltage of the controller of the motor, so that the controller of the motor controls the operation of the motor according to the over-modulation voltage; if the operating rotating speed of the motor is in the third rotating speed stage, performing over-modulation control on the output voltage of the controller of the motor to obtain an over-modulation voltage of the output voltage of the controller of the motor, so that the controller of the motor controls the operation of the motor according to the over-modulation voltage; at the same time, stopping the optimal control on the d-axis current of the motor and starting the field weakening control on the d-axis current of the motor to obtain a field weakening d-axis current, so as to control the operation of the motor according to the field weakening d-axis current.

[0010] In some embodiments, in the first and second rotating speed stages, the d-axis current of the motor is controlled by optimization, including: the MTPA angle of the motor is controlled by optimization at a first set step, to obtain an optimized MTPA angle of the corresponding stage, and then the optimized d-axis current under the corresponding stage is determined according to the MTPA angle of the corresponding stage; or the d-axis current of the motor is directly controlled by optimization at a second set step, to obtain the optimized d-axis current under the corresponding stage.

[0011] In some embodiments, in the second and third rotating speed stages, the output voltage of the controller of the motor is controlled by over-modulation, including: two adjacent voltage vectors set for the output voltage of the controller of the motor are determined, denoted as a first voltage vector and a second voltage vector; in the case that the sum of the first voltage vector and the second voltage vector is greater than a set sampling period, the first voltage vector and the second voltage vector are proportionally reduced by a set reduction ratio to obtain a first reduced voltage vector and a second reduced voltage vector; the output voltage of the controller of the motor is adjusted by using the first reduced voltage vector and the second reduced voltage vector, to obtain the output voltage control of the controller of the motor in the corresponding stage.

[0012] In some embodiments, in the third rotating speed stage, the field weakening control of the d-axis current of the motor includes: the d-axis voltage of the motor and the q-axis voltage of the motor are determined; the terminal voltage of the motor is determined according to the d-axis voltage of the motor and the q-axis voltage of the motor; the difference between the terminal voltage and the first output voltage is adjusted by PI to obtain the field weakening d-axis current.

[0013] In some embodiments, in the third rotating speed stage, the operation of the motor is controlled by the field weakening d-axis current, including: based on the second optimized d-axis current, the second optimized d-axis current is changed to the field weakening d-axis current at a set current acceleration, and then the operation of the motor is controlled by the field weakening d-axis current.

[0014] To match the above method, another aspect of the present application provides a control device of a refrigerator, comprising: a control unit configured to determine a first speed and a second speed in a speed range of a motor in a compressor of the refrigerator; wherein in the speed range, a stage less than the first speed is recorded as a first speed stage, a stage greater than or equal to the first speed and less than the second speed is recorded as a second speed stage, and a stage greater than or equal to the second speed is recorded as a third speed stage; an acquisition unit configured to acquire a running speed of the motor during operation of the motor; and the control unit is further configured to adjust a d-axis current of the motor and / or an output voltage of a controller of the motor according to a speed stage in which the running speed of the motor is located in the speed range, by using a control mode corresponding to the speed stage and preset.

[0015] In some embodiments, the control unit determines the first speed and the second speed in the speed range of the motor in the compressor of the refrigerator, comprising: determining a back electromotive force coefficient of the motor and a bus voltage of the controller of the motor; taking the product of the bus voltage and the ratio of the back electromotive force coefficient and a first set calculation coefficient as the first speed; and taking the product of the first speed and a second set calculation coefficient as the second speed.

[0016] In some embodiments, the control unit adjusts the d-axis current of the motor and / or the output voltage of the controller of the motor according to the speed stage in which the running speed of the motor is located in the speed range, by using the control mode corresponding to the speed stage and preset, comprising: if the running speed of the motor is in the first speed stage, performing optimal control on the d-axis current of the motor to obtain a first optimal d-axis current, so as to control the operation of the motor according to the first optimal d-axis current; if the running speed of the motor is in the second speed stage, continuing to perform optimal control on the d-axis current of the motor to obtain a second optimal d-axis current, so as to control the operation of the motor according to the second optimal d-axis current; at the same time, performing over-modulation control on the output voltage of the controller of the motor to obtain an over-modulation voltage of the output voltage of the controller of the motor, so that the controller of the motor controls the operation of the motor according to the over-modulation voltage; if the running speed of the motor is in the third speed stage, performing over-modulation control on the output voltage of the controller of the motor to obtain an over-modulation voltage of the output voltage of the controller of the motor, so that the controller of the motor controls the operation of the motor according to the over-modulation voltage; at the same time, stopping the optimal control on the d-axis current of the motor and starting the field weakening control on the d-axis current of the motor to obtain a field weakening d-axis current, so as to control the operation of the motor according to the field weakening d-axis current.

[0017] In some embodiments, the control unit, in the first rotating speed stage and the second rotating speed stage, performs optimal control on the d-axis current of the motor, including: performing optimal control on the MTPA angle of the motor by a first set step to obtain an optimal MTPA angle in the corresponding stage, and then determining the optimal d-axis current in the corresponding stage according to the MTPA angle in the corresponding stage; or directly performing optimal control on the d-axis current of the motor by a second set step to obtain the optimal d-axis current in the corresponding stage.

[0018] In some embodiments, the control unit, in the second rotating speed stage and the third rotating speed stage, performs over-modulation control on the output voltage of the controller of the motor, including: determining two adjacent voltage vectors set for the output voltage of the controller of the motor, denoted as a first voltage vector and a second voltage vector; in the case that the sum of the first voltage vector and the second voltage vector is greater than a set sampling period, making the first voltage vector and the second voltage vector be proportionally reduced by a set reduction ratio to obtain a first reduced voltage vector and a second reduced voltage vector; and adjusting the output voltage of the controller of the motor by using the first reduced voltage vector and the second reduced voltage vector to obtain the output voltage control of the controller of the motor in the corresponding stage.

[0019] In some embodiments, the control unit, in the third rotating speed stage, performs field weakening control on the d-axis current of the motor, including: determining the d-axis voltage of the motor and the q-axis voltage of the motor; determining the terminal voltage of the motor according to the d-axis voltage of the motor and the q-axis voltage of the motor; and performing PI adjustment on the difference between the terminal voltage and the first output voltage to obtain the field weakening d-axis current.

[0020] In some embodiments, the control unit, in the third rotating speed stage, controls the operation of the motor according to the field weakening d-axis current, including: based on the second optimal d-axis current, changing the second optimal d-axis current to the field weakening d-axis current by a set current acceleration, and then controlling the operation of the motor according to the field weakening d-axis current.

[0021] In order to match the above device, the application further provides a refrigerator, including the above-mentioned refrigerator control device.

[0022] In order to match the above method, the application further provides a storage medium, including a stored program, wherein when the program runs, the device where the storage medium is located performs the above-mentioned refrigerator control method.

[0023] Therefore, the scheme of the application divides the rotating speed range of the motor into three stages, adopts different control modes according to different stages where the operating rotating speed of the motor is located, adjusts the output voltage of the frequency conversion controller of the motor in the case of adjusting the current of the motor, so as to ensure that the compressor is optimal in efficiency in the whole frequency range, thereby improving the operating rotating speed of the motor in the case that the bus voltage of the motor and the counter electromotive force of the motor are unchanged, so as to realize the coexistence of the low-frequency energy efficiency improvement and the high-frequency freezing capacity improvement of the refrigerator.

[0024] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent from the description, or can be learned by practice of the present application.

[0025] The technical scheme of the present application will be further described in detail below with reference to the drawings and embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 Flowchart of an embodiment of the control method of the refrigerator of the present application;

[0027] Figure 2 Flowchart of an embodiment of determining the first rotating speed and the second rotating speed in the rotating speed range of the motor in the compressor of the refrigerator in the method of the present application;

[0028] Figure 3 Flowchart of an embodiment of the over-modulation control of the output voltage of the controller of the motor in the method of the present application;

[0029] Figure 4 Flowchart of an embodiment of the field weakening control of the d-axis current of the motor in the method of the present application;

[0030] Figure 5 Structural schematic diagram of an embodiment of the control device of the refrigerator of the present application;

[0031] Figure 6 Control flowchart of an embodiment of the control method of the motor in the refrigerator compressor of the present application;

[0032] Figure 7 Control flowchart of an embodiment of the MTPA control method in the control method of the motor in the refrigerator compressor of the present application;

[0033] Figure 8 Control flowchart of an embodiment of the field weakening control method in the control method of the motor in the refrigerator compressor of the present application.

[0034] In combination with the drawings, the reference signs in the embodiments of the present application are as follows:

[0035] 102 - acquisition unit; 104 - control unit. DETAILED DESCRIPTION

[0036] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described below in connection with specific embodiments of the present application and corresponding drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0037] Since the limit values of the output voltage and output current of the frequency converter of the motor in the refrigerator compressor are limited, if the operation frequency is to be increased, the back electromotive force of the motor (such as a permanent magnet synchronous motor) in the refrigerator compressor needs to be reduced, which leads to the decrease of the motor efficiency; and if the low-frequency energy efficiency is to be improved, the back electromotive force of the motor needs to be increased, which makes the improvement of the low-frequency energy efficiency of the refrigerator and the enhancement of the freezing capacity of the refrigerator contradictory. Experimental research shows that widening the operation range of the refrigerator compressor can improve the low-frequency energy efficiency and enhance the freezing capacity of the refrigerator, and increasing the speed of the compressor can make the refrigerator achieve a lower evaporation temperature and a larger freezing capacity, thus having better preservation capacity.

[0038] Since the refrigerator compressor is operated at low frequency for a long time, the low-frequency energy efficiency is required to be high. With the upgrading of the deep freezing demand of consumers, the maximum speed of the refrigerator compressor is getting higher and higher, which has been increased from 4200 rpm of the ordinary refrigerator compressor to 6000 rpm or above, which challenges the driving level of the refrigerator compressor. The control mode for improving the low-frequency energy efficiency in some schemes is MTPA mode, i.e. maximum torque current ratio control mode. This control mode makes the maximum torque of the unit current output, thereby improving the low-frequency energy efficiency. The high-frequency control strategy of some other schemes is field weakening control. The principle is that when the output voltage reaches the maximum, a negative d-axis current is added to continue to increase the speed. For example, for the current control in the full frequency range, MTPA control is used below the base speed, and field weakening control is used above the base speed.

[0039] Therefore, considering that, in the high frequency aspect, the high frequency of the motor cannot continue to increase due to the bus voltage limitation of the motor in the refrigerator compressor, so that the freezing capacity of the refrigerator cannot continue to improve. In the low frequency aspect, generally, in order to improve the running speed of the motor, the back electromotive force of the motor is reduced, but reducing the back electromotive force of the motor will reduce the low frequency energy efficiency of the motor, so that the low frequency energy efficiency of the refrigerator is low, that is, the low frequency power consumption increases. In addition, in the related scheme, the flux weakening is used to widen the speed, but too deep flux weakening will cause the motor demagnetization, thereby causing the speed instability and other problems. In order to improve the low frequency energy efficiency of the refrigerator and enhance the freezing capacity of the refrigerator, the scheme of the present application provides a control method of a refrigerator, in particular, a control method of a motor in a refrigerator compressor, which can improve the running speed of the motor without changing the bus voltage of the motor and the back electromotive force of the motor, so as to achieve the effect of simultaneously considering the low frequency energy efficiency and the high frequency stability. In addition, for the current control in the full frequency band, the scheme of using MTPA control below the base speed and using flux weakening control above the base speed only controls the current, and the speed range is limited. In addition to the current control, the scheme of the present application also controls the voltage, which can further improve the speed and widen the speed range, so as to save energy at low frequency and improve the freezing capacity at high frequency.

[0040] According to an embodiment of the present application, a control method of a refrigerator is provided, as shown in Figure 1 The flowchart of an embodiment of the method of the present application is shown. The refrigerator has a compressor, and the compressor has a motor. The control method of the refrigerator comprises steps S110 to S130.

[0041] At step S110, in the case that the refrigerator is started and operated, the first speed and the second speed in the speed range of the motor in the compressor of the refrigerator are determined. In the speed range, the stage less than the first speed is recorded as the first speed stage, the stage greater than or equal to the first speed and less than the second speed is recorded as the second speed stage, and the stage greater than or equal to the second speed is recorded as the third speed stage.

[0042] In some embodiments, the first speed and the second speed in the speed range of the motor in the compressor of the refrigerator can be determined in combination Figure 2 The flowchart of an embodiment of determining the first speed and the second speed in the speed range of the motor in the compressor of the refrigerator in the method of the present application is shown, which further illustrates the specific process of determining the first speed and the second speed in the speed range of the motor in the compressor of the refrigerator in step S110, comprising steps S210 to S230.

[0043] Step S210, determining the back electromotive force coefficient of the motor and the bus voltage of the controller of the motor.

[0044] Step S220, the bus voltage and the back EMF coefficient of the ratio, and the first set of calculation coefficient of the product, as the first speed. First set of calculation coefficient, such as 0.87 and the ratio of √3.

[0045] Step S230, the first speed and the second set of calculation coefficient of the product, as the second speed. Second set of calculation coefficient, such as 1.15.

[0046] Specifically, Figure 6 For an embodiment of the control method of the motor in the refrigerator compressor. As Figure 6 The scheme of the present application provides a control method of the motor in the refrigerator compressor, comprising: step 11, according to the motor parameters and the input voltage of the frequency converter of the motor, the first speed ω1 of the motor is calculated, and the calculation method is: Where, U dc is the bus voltage of the frequency converter of the motor, and the motor parameters are is the back EMF coefficient of the motor, which represents the back EMF value generated per unit speed.

[0047] Let the second speed ω2 = 1.15ω1, and divide the speed range of the motor into three stages according to the first speed and the second speed, namely the first speed stage, the second speed stage and the third speed stage. In each stage, different control methods are used to control the operation of the motor.

[0048] At step S120, during the operation of the motor, the running speed of the motor is obtained. As Figure 6 The scheme of the present application provides a control method of the motor in the refrigerator compressor, further comprising: step 12, obtaining the running speed ω of the motor.

[0049] At step S130, according to the speed stage in which the running speed of the motor is located in the speed range, the control method corresponding to the speed stage is used to adjust the d-axis current of the motor and / or the output voltage of the controller of the motor, so that the compressor in which the motor is located is optimal in the full frequency band of its own working frequency. As Figure 6As shown, the scheme of the present application provides a control method of a motor in a refrigerator compressor, further comprising: step 13, determining which stage in the speed range of the motor the running speed ω of the motor is in, and according to the stage in which the running speed ω of the motor is in the speed range of the motor, using the control mode in the stage to control the running process of the motor, specifically, by controlling the running parameters of the motor (such as the current of the motor or the voltage of the motor), the running process of the motor is controlled, and then at least one of steps 14, 15 and 16 can be executed according to the actual situation of the running speed ω of the motor.

[0050] The scheme of the present application provides a control mode of a motor in a refrigerator compressor, which not only reasonably allocates the current of the compressor (specifically the current of the motor), but also increases the output voltage of the controller (such as the frequency converter controller of the motor) at a suitable speed, which can improve the driving speed while ensuring the optimal efficiency of the compressor in the full frequency range, so that the running speed of the motor can be improved without changing the bus voltage of the motor and the back electromotive force of the motor, while considering the low-frequency energy efficiency, and the refrigeration capacity and stability at high frequency.

[0051] In some embodiments, the step S130 adjusts the d-axis current of the motor and / or the output voltage of the controller of the motor according to the speed stage in which the running speed of the motor is in the speed range, using the pre-set control mode corresponding to the speed stage, including at least one of the following adjustment processes:

[0052] The first adjustment process: if the running speed of the motor is in the first speed stage, the d-axis current of the motor is controlled by optimization to obtain a first optimized d-axis current, so as to control the running of the motor according to the first optimized d-axis current, that is, to adjust the running speed of the motor according to the first optimized d-axis current. For example, in the first adjustment process, automatic optimization MTPA control is used, which can adjust the efficiency and improve the low-frequency energy efficiency. In fact, by optimizing the d-axis current of the motor, the minimum d-axis current in the set d-axis current range is obtained, and the running speed of the motor is adjusted according to the minimum d-axis current.

[0053] Specifically, as shown, Figure 6 The scheme of the present application provides a control method of a motor in a refrigerator compressor, further comprising: step 14, when the motor running speed ω < ω1, automatic optimization MTPA control is used to improve the energy efficiency. Of course, the scheme of the present application can also be replaced by a scheme that directly optimizes the d-axis current I d without optimizing the MTPA angle, which can avoid the operation of the trigonometric function and simplify the operation process, and the d-axis current I d < 0.

[0054] Wherein, the MTPA control is to get a d-axis current to optimize efficiency under the base speed (such as the first speed interval and the second speed interval); the field weakening current is to control the d-axis current to achieve the purpose of improving the speed above the base speed (such as the third speed interval).

[0055] The second adjusting process: if the running speed of the motor is in the second speed stage, the d-axis current of the motor is continuously controlled to obtain a second optimized d-axis current to control the running of the motor according to the second optimized d-axis current; meanwhile, the output voltage of the controller of the motor is controlled to obtain an overmodulation voltage of the output voltage of the controller of the motor, so that the controller of the motor controls the running of the motor according to the overmodulation voltage, that is, the controller of the motor controls the running speed of the motor to increase according to the first output voltage.

[0056] Specifically, as shown in Figure 6 The method provided by the application further comprises: when the running speed ω of the motor satisfies ω1≤ω<ω2, the overmodulation control is added to the voltage of the motor on the basis of step 14 to increase the output voltage of the frequency conversion controller of the motor. In this speed interval, the control mode of the optimized MTPA is continuously used to achieve the purpose of improving the speed and increasing the efficiency. That is, the overmodulation and the automatic optimized MTPA are used in this speed interval.

[0057] The third adjusting process: if the running speed of the motor is in the third speed stage, the overmodulation control is performed on the output voltage of the controller of the motor to obtain an overmodulation voltage of the output voltage of the controller of the motor, so that the controller of the motor controls the running of the motor according to the overmodulation voltage. Meanwhile, the optimized control on the d-axis current of the motor is stopped, and the field weakening control on the d-axis current of the motor is started to obtain a field weakening d-axis current to control the running of the motor according to the field weakening d-axis current, that is, to adjust the running speed of the motor according to the field weakening d-axis current.

[0058] Specifically, as shown in Figure 6As shown, the present invention provides a control method for a motor in a refrigerator compressor, which further includes: Step 16: When the motor's operating speed ω≥ω2, the optimization MTPA control method in step 15 is changed to a field weakening control method. Based on step 15, the field weakening control method is used to control the d-axis current to further increase the speed, while retaining the overmodulation control method for the output voltage of the motor's inverter controller. Within this speed range, control is applied from both the output voltage of the motor's inverter controller and the d-axis current of the motor to achieve the purpose of increasing the speed. That is to say, within this speed range, both the overmodulation control of the output voltage of the motor's inverter controller and the field weakening control of the motor's d-axis current are used simultaneously to further increase the speed of the motor drive.

[0059] In some implementations, the d-axis current of the motor is optimized during the first speed stage and the second speed stage. This includes: optimizing the MTPA angle of the motor by a first set step size to obtain the optimized MTPA angle for the corresponding stage, and then determining the optimized d-axis current for the corresponding stage based on the MTPA angle, such as the first optimized d-axis current and the second optimized d-axis current. Alternatively, the d-axis current of the motor is directly optimized by a second set step size to obtain the optimized d-axis current for the corresponding stage, such as the first optimized d-axis current and the second optimized d-axis current.

[0060] Figure 7 This is a control flowchart illustrating an embodiment of the optimal MTPA control method in the motor control method of a refrigerator compressor according to the present invention. Figure 7 As shown, the main operation steps of the automatic optimization MTPA control method are as follows:

[0061] Step 21: Record the MTPA angle θ at the previous moment. n-1 Based on the current I at the previous moment n-1 and MTPA angle θ n-1 Obtain the d-axis current I dn-1 =-I n-1 ×cosθ n-1 To control the d-axis, the current I is recorded after the motor has stabilized. n .

[0062] Wherein, the MTPA angle θ at the previous moment n-1 Initially, an angle of 0° is set. Then, based on this set angle (e.g., 0°), positive or negative optimization is performed at a set step size s. The MTPA angle obtained in the previous optimization is the MTPA angle θ at the previous moment. n-1 The current I at the previous moment n-1 It is the angle θ between MTPA and the previous moment. n-1The corresponding motor current. The judgment of whether a motor is operating stably is that if the change in motor current is within a set current change range, the motor is considered to be operating stably.

[0063] Current I at the previous moment n-1 Current current I n All values ​​represent the total current. By changing the MTPA angle, the d-axis current is changed, and after the d-axis current changes, the total current I... n-1 The angle will also change, eventually finding the MTPA angle or d-axis current corresponding to the minimum total current. The total current can be obtained by sampling the motor phase current through the controller's sampling circuit, or it can be calculated using formulas, for example: Id is the d-axis current, and Iq is the q-axis current.

[0064] Step 22: Find the next optimal MTPA angle θ according to the set step size s (s>0). n First, search in the direction of increasing the MTPA angle, that is, find the current optimal MTPA angle θ. n =θ n-1 +s, based on the current optimal MTPA angle θ n Determine the current I n .

[0065] Then based on the current current I n Calculate the d-axis current I dn =-I n ×cosθ n Record the current I after the motor has stabilized. n '.

[0066] The step size 's' is determined based on the current MTPA angle. For example, if the current MTPA angle is 5°, cos5° = 0.996, then the step size 's' can be slightly larger, for example, 's = 5'. The next angle is 10°, and cos10° = 0.985. The difference between 0.985 and 0.996 is small, resulting in a relatively accurate calculation of the d-axis current I. d The fluctuations won't be significant. If the current MTPA angle is 45°, then the step size s should be smaller. This is because if the step size s is still equal to 5, cos45° = 0.707, but cos50° = 0.64. The difference between 0.64 and 0.707 is substantial, affecting the calculated d-axis currents I. d The difference will be significant.

[0067] In other words, the principle followed in determining the step size s is to allow the d-axis current I to... d The jump should not be too large, to prevent the d-axis current I d Excessive variation leads to speed fluctuations, and it also prevents missing the optimal d-axis current I. d .

[0068] Step 23: Compare the current I at the previous moment. n-1 'and current I n The magnitude of ', if the current I at the previous moment n-1 Current current I n If '' indicates that the optimization direction is correct, continue in the direction of increasing and follow step 22 to find the next MTPA angle. If the current I at the previous moment... n-1 '<Current Current I n If 'θ' indicates an incorrect optimization direction, the next step is to search for the next MTPA angle in the direction of decreasing MTPA, which is the current optimal MTPA angle θ. n =θ n-1 -s.

[0069] Repeat the above steps until the current I is obtained within the set current range. n 'Minimum'.

[0070] Wherein, the current optimal MTPA angle θ n It should satisfy 0°<θ n <90°.

[0071] In addition, the method of directly optimizing the d-axis current of the motor is similar to the method of optimizing the MTPA angle of the motor, except that the MTPA angle in the optimization control of the MTPA angle of the motor is replaced by the d-axis current. This will not be elaborated further here.

[0072] In some embodiments, the specific process of overmodulating the output voltage of the motor controller during the second speed stage and the third speed stage is described in the following exemplary description.

[0073] The following is combined with Figure 3 The diagram shows an embodiment of the method of the present invention in which the output voltage of the controller of the motor is over-modulated. The specific process of over-modulating the output voltage of the controller of the motor is further explained, including steps S310 to S330.

[0074] Step S310: Determine two adjacent voltage vectors for the output voltage setting of the controller for the motor, denoted as the first voltage vector and the second voltage vector.

[0075] Step S320: When the sum of the first voltage vector and the second voltage vector is greater than the set sampling period, the first voltage vector and the second voltage vector are proportionally reduced according to the set reduction ratio to obtain the first reduced voltage vector and the second reduced voltage vector.

[0076] Step S330, the first reduced voltage vector and the second reduced voltage vector are used to adjust the output voltage of the controller of the motor, so as to obtain the output voltage control of the controller of the motor in the corresponding stage, such as the first output voltage and the second output voltage.

[0077] The calculation method of the overmodulation control is as follows:

[0078] In the SVPWM (space vector pulse width modulation) control of the motor, two adjacent voltage vectors T1 and T2, when T1+T2>T (T is a sampling period), T1 and T2 are reduced in equal ratio, that is,

[0079] In some embodiments, in the third rotating speed stage, the specific process of the field weakening control of the d-axis current of the motor is described in the following example.

[0080] The specific process of the field weakening control of the d-axis current of the motor is further described below in combination with the embodiment flowchart of the field weakening control method of the d-axis current of the motor in the method of the application shown in Figure 4 The specific process of the field weakening control of the d-axis current of the motor is further described below in combination with the embodiment flowchart of the field weakening control method of the d-axis current of the motor in the method of the application shown in

[0081] Step S410, the d-axis voltage of the motor and the q-axis voltage of the motor are determined.

[0082] Step S420, the terminal voltage of the motor is determined according to the d-axis voltage of the motor and the q-axis voltage of the motor.

[0083] Step S430, the difference between the terminal voltage and the first output voltage is PI regulated to obtain the field weakening d-axis current. The first input voltage is the overmodulation maximum voltage U m .

[0084] The specific calculation method of the field weakening control is as follows:

[0085] Figure 8 The control flowchart of the embodiment of the field weakening control method of the motor in the control method of the motor in the refrigerator compressor of the application is shown in Figure 8 As shown in the figure, the field weakening control method comprises: calculating the terminal voltage U of the motor according to the d-axis voltage and the q-axis voltage of the motor s Comparing the terminal voltage U m of the motor with the overmodulation maximum voltage U s of the output voltage of the frequency conversion controller of the motor m The difference between the terminal voltage U dref of the motor and the overmodulation maximum voltage U dref is PI regulated by a PI regulator to output the d-axis current I dref .

[0086] Here, the overmodulation maximum voltage U m is: in the second speed stage (i.e. the stage that has not entered the field weakening control), the motor speed is increased, the output voltage of the motor frequency converter is detected, there is a limit value, when the output voltage of the motor frequency converter reaches the limit value, the motor speed cannot continue to increase, and this voltage is the overmodulation maximum voltage U m .

[0087] Among them, the PI regulator is also called proportional integral regulator, the input is generally error (voltage error in the scheme of the application), assuming that the input is ε, then the output PI.out=Kp×ε+Ki×∫ε, Kp is proportional coefficient, Ki is integral coefficient. That is, the PI regulator is proportional to the error accumulation and amplification, and the output is fed back to the system to achieve balance and stability. At that time, the above is an example of the PI regulator model, and there are some other factors in the actual adjustment process.

[0088] In some embodiments, in the third speed stage, the operation of the motor is controlled according to the field weakening d-axis current, including: based on the second optimal d-axis current, the second optimal d-axis current is changed to the field weakening d-axis current at a set current acceleration, and then the operation of the motor is controlled according to the field weakening d-axis current, so that the running speed of the motor changes smoothly.

[0089] In step 16, since the d-axis current used in the previous speed interval, i.e. the second speed stage, i.e. the second optimal d-axis current, is calculated by the optimal MTPA control mode, when the third speed interval, i.e. the third speed stage, is changed to field weakening control, the d-axis current calculated by the optimal MTPA control mode in the second speed stage, i.e. the second optimal d-axis current, and the d-axis current corresponding to the field weakening control, such as the field weakening d-axis current, may differ greatly, so a current acceleration is needed to make the d-axis current change from the second optimal d-axis current to the field weakening d-axis current slowly and smoothly, so as to prevent the current from changing suddenly and causing the speed to be unstable.

[0090] Among them, the selection of the current acceleration is that the smaller the better in principle, so as to prevent the current from changing suddenly and causing the speed of the motor to be unstable, such as 0.3A or less.

[0091] The control method of the motor in the refrigerator compressor provided by the scheme of the application controls the output voltage of the motor frequency converter and the d-axis current of the motor, which can increase the running speed of the motor under the condition that the bus voltage of the motor and the back electromotive force of the motor do not change, and can improve the low-frequency energy efficiency and the running speed.

[0092] According to the technical scheme of the embodiment, the speed range of the motor is divided into three stages, different control modes are adopted according to different stages in which the running speed of the motor is located, and the output voltage of the frequency conversion controller of the motor is adjusted under the condition of adjusting the current of the motor, so as to ensure that the compressor is optimal in efficiency in the whole frequency range, thereby improving the running speed of the motor under the condition that the bus voltage of the motor and the counter electromotive force of the motor are unchanged, and achieving the compatibility of improving the energy efficiency at low frequency and improving the freezing capacity at high frequency.

[0093] According to the embodiment of the application, a control device of a refrigerator corresponding to the control method of the refrigerator is also provided. Referring to Figure 5 The device of the application is shown in the structural schematic diagram of an embodiment thereof. The refrigerator has a compressor, and the compressor has a motor. The control device of the refrigerator comprises an acquisition unit 102 and a control unit 104.

[0094] The control unit 104 is configured to determine a first speed and a second speed in a speed range of the motor in the compressor of the refrigerator under the condition that the refrigerator is started and operated. In the speed range, a stage less than the first speed is recorded as a first speed stage, a stage greater than or equal to the first speed and less than the second speed is recorded as a second speed stage, and a stage greater than or equal to the second speed is recorded as a third speed stage. The specific functions and processes of the control unit 104 are described with reference to step S110.

[0095] In some embodiments, the control unit 104 determines the first speed and the second speed in the speed range of the motor in the compressor of the refrigerator, comprising:

[0096] The control unit 104 is specifically further configured to determine the counter electromotive force coefficient of the motor and the bus voltage of the controller of the motor. The specific functions and processes of the control unit 104 are also described with reference to step S210.

[0097] The control unit 104 is specifically further configured to take the product of the ratio of the bus voltage to the counter electromotive force coefficient and a first set calculation coefficient as the first speed. The first set calculation coefficient is, for example, the ratio of 0.87 to √3. The specific functions and processes of the control unit 104 are also described with reference to step S220.

[0098] The control unit 104 is specifically further configured to take the product of the first speed and a second set calculation coefficient as the second speed. The second set calculation coefficient is, for example, 1.15. The specific functions and processes of the control unit 104 are also described with reference to step S230.

[0099] Specifically, Figure 6A control flow chart of an embodiment of the control device of a motor in a refrigerator compressor. As shown in Figure 6 The control device of a motor in a refrigerator compressor provided by the present application includes: step 11, calculating a first rotating speed ω1 of the motor according to motor parameters and an input voltage of a frequency converter of the motor, and the calculation device is: Wherein, U dc is a bus voltage of the frequency converter of the motor, and the motor parameters are is a back electromotive force coefficient of the motor, indicating a back electromotive force value generated per unit rotating speed.

[0100] Let a second rotating speed ω2 = 1.15ω1, and divide the rotating speed range of the motor into three stages, i.e. a first rotating speed stage, a second rotating speed stage and a third rotating speed stage, according to the first rotating speed and the second rotating speed. In each stage, a different control mode is used to control the operation of the motor.

[0101] The acquisition unit 102 is configured to acquire a running rotating speed of the motor during the operation of the motor. As shown in Figure 6 The control device of a motor in a refrigerator compressor provided by the present application further includes: step 12, acquiring a running rotating speed ω of the motor. The specific functions and processes of the control unit 104 are described in step S120.

[0102] The control unit 104 is further configured to adjust a d-axis current of the motor and / or an output voltage of the controller of the motor according to a rotating speed stage in which the running rotating speed of the motor is located in the rotating speed range, by using a pre-set control mode corresponding to the rotating speed stage, so as to make the compressor in which the motor is located optimal in efficiency in a full frequency band of a working frequency of the motor. The specific functions and processes of the control unit 104 are further described in step S130. As shown in Figure 6 The control device of a motor in a refrigerator compressor provided by the present application further includes: step 13, determining in which stage of the rotating speed range of the motor the running rotating speed ω of the motor is located, and controlling the operation of the motor according to the stage in which the running rotating speed ω of the motor is located in the rotating speed range of the motor, specifically, by controlling the running parameters (such as the current of the motor or the voltage of the motor) of the motor to control the operation of the motor, and then at least one of step 14, step 15 and step 16 can be executed according to the actual situation of the running rotating speed ω of the motor.

[0103] The control method of the motor in the refrigerator compressor provided by the scheme of the present application can improve the output voltage of the controller (such as the frequency conversion controller of the motor) at a proper rotating speed, can ensure the optimal efficiency of the compressor in the whole frequency band while improving the driving rotating speed, and can improve the operating rotating speed of the motor while ensuring the low-frequency energy efficiency, the high-frequency refrigerating capacity and the high-frequency stability without changing the bus voltage of the motor and the back electromotive force of the motor.

[0104] In some embodiments, the control unit 104 adjusts the d-axis current of the motor and / or the output voltage of the controller of the motor according to the rotating speed stage in which the operating rotating speed of the motor is located in the rotating speed range, by using the control method corresponding to the rotating speed stage, and the adjustment process includes at least one of the following:

[0105] The first adjustment process: the control unit 104 is specifically configured to, if the operating rotating speed of the motor is located in the first rotating speed stage, perform optimal control on the d-axis current of the motor to obtain a first optimal d-axis current, and controls the operation of the motor according to the first optimal d-axis current, that is, adjusts the operating rotating speed of the motor according to the first optimal d-axis current. In fact, the optimal control on the d-axis current of the motor is used to obtain the minimum d-axis current in the set d-axis current range, and the operating rotating speed of the motor is adjusted according to the minimum d-axis current.

[0106] Specifically, as shown in Figure 6 The control device of the motor in the refrigerator compressor provided by the scheme of the present application further includes the following step 14: when the operating rotating speed of the motor is less than ω1, the automatic optimal MTPA control is used to improve the energy efficiency. Of course, the scheme of the present application can also be replaced by another scheme, that is, the MTPA angle is not optimized, but the d-axis current I d is directly optimized, which can avoid the trigonometric function operation and simplify the operation process, and the d-axis current I d < 0.

[0107] The second adjustment process: the control unit 104 is specifically configured to, if the operating rotating speed of the motor is located in the second rotating speed stage, continue to perform optimal control on the d-axis current of the motor to obtain a second optimal d-axis current, and controls the operation of the motor according to the second optimal d-axis current. At the same time, the output voltage of the controller of the motor is modulated to obtain an over-modulation voltage of the output voltage of the controller of the motor, so that the controller of the motor controls the operation of the motor according to the over-modulation voltage, that is, the controller of the motor controls the operating rotating speed of the motor to be increased according to the first output voltage.

[0108] Specifically, as shown in Figure 6 The control device of the motor in the refrigerator compressor provided by the scheme of the present application further comprises: step 15, when the running speed ω of the motor satisfies ω1≤ω<ω2, the over-modulation control is added to the voltage of the motor on the basis of step 14 to increase the output voltage of the frequency converter of the motor. In this speed range, the control mode of the optimized MTPA is continued to be used to achieve the purpose of increasing the speed and improving the efficiency. That is, in this speed range, the over-modulation and the automatic optimized MTPA control device are used at the same time.

[0109] The control unit 104 is further configured to, if the running speed of the motor is in the third speed stage, perform over-modulation control on the output voltage of the controller of the motor to obtain an over-modulation voltage of the output voltage of the controller of the motor, and control the motor to run by the controller of the motor according to the over-modulation voltage. At the same time, the optimized control on the d-axis current of the motor is stopped, and the field-weakening control on the d-axis current of the motor is started to obtain a field-weakening d-axis current, so as to control the motor to run according to the field-weakening d-axis current, that is, to adjust the running speed of the motor according to the field-weakening d-axis current.

[0110] Specifically, as shown in Figure 6 The control device of the motor in the refrigerator compressor provided by the scheme of the present application further comprises: step 16, when the running speed ω of the motor is greater than or equal to ω2, the control mode of the optimized MTPA in step 15 is changed to a field-weakening control mode, and the field-weakening control mode is used to further increase the speed by controlling the d-axis current on the basis of step 15, while the over-modulation control mode of the output voltage of the frequency converter of the motor is retained. In this speed range, the control is performed from two aspects of the output voltage of the frequency converter of the motor and the d-axis current of the motor respectively to achieve the purpose of increasing the speed. That is, in this speed range, the over-modulation control of the output voltage of the frequency converter of the motor and the field-weakening control of the d-axis current of the motor are used at the same time to further increase the speed of the motor.

[0111] In some embodiments, the control unit 104 performs the optimized control on the d-axis current of the motor in the first speed stage and the second speed stage, comprising:

[0112] The control unit 104 is further configured to perform optimization control on the MTPA angle of the motor according to a first preset step size to obtain the optimization MTPA angle for the corresponding stage, and then determine the optimization d-axis current for the corresponding stage based on the MTPA angle for the corresponding stage, such as the first optimization d-axis current and the second optimization d-axis current. Alternatively, the control unit 104 is further configured to directly perform optimization control on the d-axis current of the motor according to a second preset step size to obtain the optimization d-axis current for the corresponding stage, such as the first optimization d-axis current and the second optimization d-axis current.

[0113] Figure 7 This is a control flowchart of an embodiment of the MTPA (Mechanical Mode and Power Optimization) control device in the motor control device of a refrigerator compressor according to the present invention. Figure 7 As shown, the main operating steps of the automatic optimization MTPA control device are as follows:

[0114] Step 21: Record the MTPA angle θ at the previous moment. n-1 Based on the current I at the previous moment n-1 and MTPA angle θ n-1 Obtain the d-axis current I dn-1 =-I n-1 ×cosθ n-1 Record the current I after the motor has stabilized. n .

[0115] Wherein, the MTPA angle θ at the previous moment n-1 Initially, an angle of 0° is set. Then, based on this set angle (e.g., 0°), positive or negative optimization is performed at a set step size s. The MTPA angle obtained in the previous optimization is the MTPA angle θ at the previous moment. n-1 The current I at the previous moment n-1 It is the angle θ between MTPA and the previous moment. n-1 The corresponding motor current.

[0116] The judgment of whether a motor is running stably is that when the change value of the motor current is within the set current change range, the motor is considered to be running stably.

[0117] Step 22: Find the next optimal MTPA angle θ according to the set step size s (s>0). n First, search in the direction of increasing the MTPA angle, that is, find the current optimal MTPA angle θ. n =θ n-1 +s, based on the current optimal MTPA angle θ n Determine the current I n .

[0118] Then based on the current current I n Calculate the d-axis current I dn =-In x cos θ n , after the motor runs stably, record the current I n .

[0119] Wherein, the determination of the set step s is according to the current MTPA angle self-defined, for example: the current MTPA angle is 5°, cos5° = 0.996, so the set step s can be a little larger, for example s = 5, the next angle is 10°, cos10° = 0.985. 0.985 and 0.996 are small, the calculated d-axis current I d will not fluctuate greatly. If the current MTPA angle is 45°, the set step s should be smaller, because if the set step s is still equal to 5, cos45° = 0.707, but cos50° = 0.64, 0.64 and 0.707 are large, the calculated two d-axis currents I d will be very different.

[0120] That is, for the determination of the set step s, the principle followed is to let the d-axis current I d cannot jump too much, both to prevent the d-axis current I d change too much to cause the speed fluctuation, also to avoid missing the optimal d-axis current I d .

[0121] Step 23, compare the current I n-1 ' and the current I n ' of the last time, if the current I n-1 ' of the last time is greater than the current I n ', it means that the optimization direction is correct, continue to find the next MTPA angle in the increasing direction according to step 22. If the current I n-1 ' of the last time is less than the current I n ', it means that the optimization direction is wrong, the next step is to find the next MTPA angle in the decreasing direction, that is, the current optimal MTPA angle θ n = θ n-1 -s.

[0122] In this way, repeat the above steps until the current I n ' obtained finally is minimum.

[0123] Wherein, the current optimal MTPA angle θ n should satisfy 0° < θ n < 90°.

[0124] In addition, the control unit 104 directly optimizes the d-axis current of the motor in the same way as the MTPA angle of the motor, except that the MTPA angle of the motor is replaced by the d-axis current for optimization control, which will not be repeated here.

[0125] In some embodiments, the control unit 104 modulates the output voltage of the motor controller in the second and third speed stages, including:

[0126] The control unit 104 is specifically configured to determine two adjacent voltage vectors for the output voltage of the motor controller, denoted as the first voltage vector and the second voltage vector. The specific functions and processes of the control unit 104 are also described in step S310.

[0127] The control unit 104 is specifically configured to proportionally reduce the first voltage vector and the second voltage vector by a set reduction ratio to obtain a first reduced voltage vector and a second reduced voltage vector when the sum of the first voltage vector and the second voltage vector is greater than a set sampling period. The specific functions and processes of the control unit 104 are also described in step S320.

[0128] The control unit 104 is specifically configured to adjust the output voltage of the motor controller using the first reduced voltage vector and the second reduced voltage vector to obtain the output voltage control of the motor controller in the corresponding stage, such as the first output voltage and the second output voltage. The specific functions and processes of the control unit 104 are also described in step S330.

[0129] Wherein, the calculation device of over-modulation control is as follows:

[0130] Two adjacent voltage vectors T1, T2, when T1+T2>T (T is a sampling period), T1, T2 are proportionally reduced, that is,

[0131] In some embodiments, the control unit 104 controls the d-axis current of the motor in the third speed stage, including:

[0132] The control unit 104 is specifically configured to determine the d-axis voltage of the motor and the q-axis voltage of the motor. The specific functions and processes of the control unit 104 are also described in step S410.

[0133] The control unit 104 is further configured to determine the terminal voltage of the motor according to the d-axis voltage of the motor and the q-axis voltage of the motor. The specific functions and processes of the control unit 104 are also described in step S420.

[0134] The control unit 104 is further configured to perform PI adjustment on the difference between the terminal voltage and the first output voltage to obtain the field-weakening d-axis current. The specific functions and processes of the control unit 104 are also described in step S430. The first input voltage is the over-modulation maximum voltage U m .

[0135] The specific calculation device of the field-weakening control is as follows:

[0136] Figure 8 The control flowchart of an embodiment of the field-weakening control device of the control device of the motor of the refrigerator compressor is shown in FIG. 4. As shown in FIG. 4, the field-weakening control device includes the following steps: Figure 8 calculating the terminal voltage of the motor according to the d-axis voltage and the q-axis voltage of the motor comparing the terminal voltage U s of the motor with the over-modulation maximum voltage U m of the output voltage of the frequency converter of the motor s performing PI adjustment on the difference between the terminal voltage U m of the motor and the over-modulation maximum voltage U dref .

[0137] Here, the over-modulation maximum voltage U m is the limit value of the output voltage of the frequency converter of the motor when the motor speed is increased in the second speed stage (i.e., the stage without field-weakening control), and the motor speed cannot be further increased when the output voltage of the frequency converter of the motor reaches the limit value. This voltage is the over-modulation maximum voltage U m .

[0138] The PI regulator is also called a proportional-integral regulator, and the input of the PI regulator is generally an error (a voltage error in the scheme of the present application). Assuming that the input is ε, the output PI.out = Kp×ε+Ki×∫ε, Kp is a proportional coefficient, and Ki is an integral coefficient. That is, the PI regulator accumulates and proportionally amplifies the error and feeds back the output to the system to achieve balance and stability. The above is an example of the model of the PI regulator, and the PI regulator has some other factors in the actual adjustment process.

[0139] In some embodiments, the control unit 104 controls the operation of the motor according to the field-weakening d-axis current in the third speed stage, including:

[0140] The control unit 104 is further configured to, based on the second optimal d-axis current, change the second optimal d-axis current to the field-weakening d-axis current at a set current acceleration, and then control the motor to run at the field-weakening d-axis current, so as to smoothly change the running speed of the motor.

[0141] In step 16, since the d-axis current used in the previous speed range, i.e., the second optimal d-axis current, is calculated by the optimal MTPA control mode, when the motor is switched to the field-weakening control in the third speed range, i.e., the third speed stage, the d-axis current calculated by the optimal MTPA control mode in the second speed stage, i.e., the second optimal d-axis current, and the d-axis current corresponding to the field-weakening control, such as the field-weakening d-axis current, can be quite different, so a current acceleration needs to be set to slowly and smoothly change the second optimal d-axis current to the field-weakening d-axis current, so as to prevent the sudden change of the current from causing the instability of the speed.

[0142] The selection of the current acceleration is, in principle, as small as possible, so as to prevent the sudden change of the current from causing the instability of the speed of the motor, such as 0.3 A or less.

[0143] The control device of the motor in the refrigerator compressor provided by the scheme can control the output voltage of the frequency converter of the motor and the d-axis current of the motor, can improve the running speed of the motor without changing the bus voltage of the motor and the back electromotive force of the motor, can improve the low-frequency energy efficiency, and can improve the running speed.

[0144] Since the processing and functions realized by the device of the embodiment are basically corresponding to the embodiments, principles and examples of the foregoing method, for the parts not described in detail in the description of the embodiment, reference can be made to the related description in the foregoing embodiments, which will not be repeated here.

[0145] By dividing the speed range of the motor into three stages, adopting different control modes according to different stages of the running speed of the motor, adjusting the output voltage of the frequency converter of the motor under the condition of adjusting the current of the motor, the technical scheme of the application can ensure that the compressor has optimal efficiency in the whole frequency range, has good refrigeration effect, and has low energy consumption.

[0146] According to the embodiment of the application, a refrigerator corresponding to the control device of the refrigerator is also provided. The refrigerator can include the control device of the refrigerator described above.

[0147] Since the processing and functions realized by the refrigerator of the embodiment are basically corresponding to the embodiments, principles and examples of the foregoing device, for the parts not described in detail in the description of the embodiment, reference can be made to the related description in the foregoing embodiments, which will not be repeated here.

[0148] The technical scheme of the present application divides the rotating speed range of the motor into three stages, adopts different control modes according to different stages where the rotating speed of the motor is located, adjusts the output voltage of the frequency conversion controller of the motor under the condition of adjusting the current of the motor, so as to ensure that the compressor has optimal efficiency in the whole frequency range, improve the low-frequency energy efficiency, and ensure the high-frequency refrigeration capacity.

[0149] According to the embodiment of the present application, a storage medium corresponding to the control method of the refrigerator is also provided, which comprises a stored program, wherein when the program is executed, the device where the storage medium is located performs the control method of the refrigerator as described above.

[0150] Since the processing and functions realized by the storage medium of the present embodiment are basically corresponding to the embodiments, principles and examples of the foregoing method, the description of the present embodiment will not be described in detail, and the related description in the foregoing embodiments can be referred to, which will not be described herein.

[0151] The technical scheme of the present application divides the rotating speed range of the motor into three stages, adopts different control modes according to different stages where the rotating speed of the motor is located, adjusts the output voltage of the frequency conversion controller of the motor under the condition of adjusting the current of the motor, so as to ensure that the compressor has optimal efficiency in the whole frequency range, improve the low-frequency energy efficiency, and ensure the high-frequency refrigeration capacity.

[0152] In summary, the person skilled in the art can easily understand that the above-mentioned advantageous modes can be freely combined and superimposed without conflict.

[0153] The above only describes the embodiments of the present application and is not used to limit the present application, and the present application can have various modifications and changes for the person skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the scope of claims of the present application.

Claims

1. A method for controlling a refrigerator, characterized in that, include: Determine a first speed and a second speed within the speed range of the motor in the compressor of the refrigerator; wherein, within the speed range, the stage that is less than the first speed is denoted as the first speed stage, the stage that is greater than or equal to the first speed and less than the second speed is denoted as the second speed stage, and the stage that is greater than or equal to the second speed is denoted as the third speed stage; During the operation of the motor, the operating speed of the motor is obtained; Based on the operating speed of the motor within the specified speed range, a pre-set control method corresponding to that speed range is used to adjust the d-axis current of the motor and / or the output voltage of the motor's controller, including: If the operating speed of the motor is in the first speed stage, then the d-axis current of the motor is optimized to obtain the first optimized d-axis current, so as to control the operation of the motor according to the first optimized d-axis current; If the operating speed of the motor is in the second speed stage, then the d-axis current of the motor is continuously optimized to obtain a second optimized d-axis current, so as to control the operation of the motor according to the second optimized d-axis current; at the same time, the output voltage of the motor controller is over-modulated to obtain an over-modulated voltage of the output voltage of the motor controller, so that the motor controller controls the operation of the motor according to the over-modulated voltage. If the operating speed of the motor is in the third speed stage, then the output voltage of the motor controller is over-modulated to obtain an over-modulated voltage, so that the motor controller controls the operation of the motor according to the over-modulated voltage; at the same time, the optimization control of the d-axis current of the motor is stopped, and the field weakening control of the d-axis current of the motor is started to obtain a field weakening d-axis current, so that the operation of the motor is controlled according to the field weakening d-axis current.

2. The refrigerator control method according to claim 1, characterized in that, Determining the first and second speeds within the speed range of the motor in the refrigerator compressor includes: Determine the back EMF coefficient of the motor and the bus voltage of the motor controller; The ratio of the bus voltage to the back EMF coefficient, multiplied by a first set calculation coefficient, is used as the first rotational speed. The product of the first rotational speed and the second set calculation coefficient is taken as the second rotational speed.

3. The refrigerator control method according to claim 1, characterized in that, In the first speed stage and the second speed stage, the d-axis current of the motor is optimized and controlled, including: The MTPA angle of the motor is optimized according to the first set step size to obtain the optimized MTPA angle of the corresponding stage, and then the optimized d-axis current of the corresponding stage is determined according to the MTPA angle of the corresponding stage. Alternatively, the d-axis current of the motor can be directly optimized according to the second set step size to obtain the optimized d-axis current at the corresponding stage.

4. The refrigerator control method according to claim 1, characterized in that, In the second and third speed stages, the output voltage of the motor controller is over-modulated, including: Determine two adjacent voltage vectors for the output voltage setting of the controller for the motor, denoted as the first voltage vector and the second voltage vector; If the sum of the first voltage vector and the second voltage vector is greater than the set sampling period, the first voltage vector and the second voltage vector are reduced proportionally according to the set reduction ratio to obtain the first reduced voltage vector and the second reduced voltage vector. The output voltage of the motor controller is adjusted using the first reduced voltage vector and the second reduced voltage vector to obtain the output voltage control of the motor controller at the corresponding stage.

5. The refrigerator control method according to claim 1, characterized in that, In the third speed stage, the field weakening control of the d-axis current of the motor includes: Determine the d-axis voltage and the q-axis voltage of the motor; The terminal voltage of the motor is determined based on the d-axis voltage and the q-axis voltage of the motor. The difference between the terminal voltage and the first output voltage is PI-regulated to obtain the field weakening d-axis current; the first output voltage is the overmodulated voltage of the output voltage of the motor controller.

6. The refrigerator control method according to claim 1, characterized in that, In the third speed stage, controlling the motor operation according to the weakening d-axis current includes: Based on the second optimal d-axis current, the second optimal d-axis current is changed to the field weakening d-axis current according to the set current acceleration, and then the operation of the motor is controlled according to the field weakening d-axis current.

7. A control device for a refrigerator, characterized in that, include: The control unit is configured to determine a first speed and a second speed within a speed range of the motor in the compressor of the refrigerator; wherein, within the speed range, a phase less than the first speed is denoted as the first speed phase, a phase greater than or equal to the first speed and less than the second speed is denoted as the second speed phase, and a phase greater than or equal to the second speed is denoted as the third speed phase; The acquisition unit is configured to acquire the operating speed of the motor during the operation of the motor; The control unit is further configured to adjust the d-axis current of the motor and / or the output voltage of the motor's controller according to the speed stage of the motor's operating speed within the speed range, using a pre-set control method corresponding to that speed stage, including: If the operating speed of the motor is in the first speed stage, then the d-axis current of the motor is optimized to obtain the first optimized d-axis current, so as to control the operation of the motor according to the first optimized d-axis current; If the operating speed of the motor is in the second speed stage, then the d-axis current of the motor is continuously optimized to obtain a second optimized d-axis current, so as to control the operation of the motor according to the second optimized d-axis current; at the same time, the output voltage of the motor controller is over-modulated to obtain an over-modulated voltage of the output voltage of the motor controller, so that the motor controller controls the operation of the motor according to the over-modulated voltage. If the operating speed of the motor is in the third speed stage, then the output voltage of the motor controller is over-modulated to obtain an over-modulated voltage, so that the motor controller controls the operation of the motor according to the over-modulated voltage; at the same time, the optimization control of the d-axis current of the motor is stopped, and the field weakening control of the d-axis current of the motor is started to obtain a field weakening d-axis current, so that the operation of the motor is controlled according to the field weakening d-axis current.

8. The control device for a refrigerator according to claim 7, characterized in that, The control unit determines a first speed and a second speed within the speed range of the motor in the refrigerator's compressor, including: Determine the back EMF coefficient of the motor and the bus voltage of the motor controller; The ratio of the bus voltage to the back EMF coefficient, multiplied by a first set calculation coefficient, is used as the first rotational speed. The product of the first rotational speed and the second set calculation coefficient is taken as the second rotational speed.

9. The control device for a refrigerator according to claim 7, characterized in that, The control unit performs optimization control on the d-axis current of the motor during the first speed stage and the second speed stage, including: The MTPA angle of the motor is optimized according to the first set step size to obtain the optimized MTPA angle of the corresponding stage, and then the optimized d-axis current of the corresponding stage is determined according to the MTPA angle of the corresponding stage. Alternatively, the d-axis current of the motor can be directly optimized according to the second set step size to obtain the optimized d-axis current at the corresponding stage.

10. The control device for a refrigerator according to claim 7, characterized in that, The control unit performs overmodulation control on the output voltage of the motor controller during the second speed phase and the third speed phase, including: Determine two adjacent voltage vectors for the output voltage setting of the controller for the motor, denoted as the first voltage vector and the second voltage vector; If the sum of the first voltage vector and the second voltage vector is greater than the set sampling period, the first voltage vector and the second voltage vector are reduced proportionally according to the set reduction ratio to obtain the first reduced voltage vector and the second reduced voltage vector. The output voltage of the motor controller is adjusted using the first reduced voltage vector and the second reduced voltage vector to obtain the output voltage control of the motor controller at the corresponding stage.

11. The control device for a refrigerator according to claim 7, characterized in that, The control unit, in the third speed phase, performs field weakening control of the d-axis current of the motor, including: Determine the d-axis voltage and the q-axis voltage of the motor; The terminal voltage of the motor is determined based on the d-axis voltage and the q-axis voltage of the motor. The difference between the terminal voltage and the first output voltage is PI-regulated to obtain the field weakening d-axis current; the first output voltage is the overmodulated voltage of the output voltage of the motor controller.

12. The control device for a refrigerator according to claim 7, characterized in that, The control unit, in the third speed stage, controls the operation of the motor according to the weakening d-axis current, including: Based on the second optimal d-axis current, the second optimal d-axis current is changed to the field weakening d-axis current according to the set current acceleration, and then the operation of the motor is controlled according to the field weakening d-axis current.

13. A refrigerator, characterized in that, include: The control device for the refrigerator as described in any one of claims 7 to 12.

14. A storage medium, characterized in that, The storage medium includes a stored program, wherein, when the program is executed, it controls the device containing the storage medium to perform the control method of the refrigerator as described in any one of claims 1 to 6.

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