Compressor control method and device, variable frequency air conditioner and storage medium

Abstract

The invention discloses a control method and device for a compressor, a variable frequency air conditioner and a storage medium, and the method comprises the steps that in the operation process of the compressor, the carrier wave ratio needed by the operation frequency of the compressor to reach the target frequency and the phase voltage instruction value output by a controller used for controlling the compressor are obtained; if the carrier wave ratio is smaller than the preset proportion value and the phase voltage instruction value is larger than the first voltage amplitude limiting value, whether the direct-axis current of the compressor needs to be increased in the negative direction or not is judged; if yes, the direct-axis current of the compressor is controlled to be increased to the current amplitude limiting value in the negative direction, and the quadrature-axis voltage of the compressor is kept unchanged in the process that the direct-axis current of the compressor is increased to the current amplitude limiting value in the negative direction, so that the actual motor rotating speed of the compressor is increased to the target rotating speed. According to the invention, the technical problem of poor control stability during high-frequency operation of the compressor in the prior art is solved at least to a certain extent.

Description

Technical Field

[0001] The present invention belongs to the technical field of household electrical appliances, and in particular relates to a control method and device for a compressor, a variable frequency air conditioner and a storage medium. Background Art

[0002] In variable frequency air conditioning systems, the bus voltage has a certain upper limit due to device limitations. Therefore, if the compressor motor back electromotive force is high and the operating frequency is high, the required phase voltage will exceed the maximum value that the bus voltage can provide, resulting in the speed being unable to increase. At this time, it is necessary to negatively increase the direct-axis current to reduce the motor phase voltage and increase the speed. Usually, the voltage closed-loop method is used, and the difference between the voltage limit value and the actual voltage value is input into a PI (proportional integral) controller to obtain the required direct-axis current. The voltage command calculated by the controller needs to take effect in the next carrier cycle, and there is a digital delay.

[0003] In order to reduce the loss and heat of power devices, improve the efficiency of electronic control, and reduce the computing load of MCU, the switching frequency of motor control is usually required to be under certain limits, usually 3-6kHz. However, with the increase of compressor operating frequency and the increase of the number of motor poles of the compressor, if the switching frequency cannot be increased, the carrier ratio of the controller will be very low, the sampling and control delays will increase, and the current loop performance will decrease. Especially for position sensorless control, it will also reduce the accuracy and stability of the position observer. At this time, if the motor is still in weak magnetic control, it is easy to cause weak magnetic ring oscillation, resulting in system loss of control. As a result, the operating frequency of the compressor is limited. Summary of the invention

[0004] The embodiments of the present invention provide a control method and device for a compressor, a variable frequency air conditioner and a storage medium, which at least to some extent solve the technical problem of poor control stability of the compressor when it operates at a high frequency in the related art.

[0005] In a first aspect of the present invention, a control method for a compressor is provided, comprising: during the operation of the compressor, obtaining a carrier ratio required for making the operating frequency of the compressor reach a target frequency, and a phase voltage command value output by a controller for controlling the compressor; if the carrier ratio is less than a preset ratio, and the phase voltage command value is greater than a first voltage limit value, determining whether it is necessary to negatively increase the direct-axis current of the compressor; if so, controlling the compressor to negatively increase the direct-axis current of the compressor to a current limit value, and maintaining the cross-axis voltage unchanged during the process of the direct-axis current negatively increasing to the current limit value, so that the actual motor speed of the compressor is increased to the target speed.

[0006] In combination with the first aspect, in some embodiments, the determination of whether it is necessary to negatively increase the direct-shaft current of the compressor includes: obtaining the actual motor speed of the compressor and the actual direct-shaft current of the compressor to obtain a first speed value and a first current value; if the first speed value is less than the target speed, and the first current value is less than the current limit value, it indicates that the direct-shaft current of the compressor needs to be negatively increased.

[0007] In combination with the first aspect, in some embodiments, the controlling of the direct-shaft current of the compressor to negatively increase to the current limiting value includes: controlling the direct-shaft current of the compressor to negatively increase through a PI controller; obtaining the actual motor speed and the actual direct-shaft current of the compressor after negatively increasing the direct-shaft current of the compressor to obtain a second speed value and a second current value; if the second speed value is less than the target speed, and the second current value is less than the current limiting value, returning to the step of controlling the direct-shaft current to negatively increase through the PI controller, otherwise, stopping the negative increase of the direct-shaft current of the compressor.

[0008] In combination with the first aspect, in some embodiments, the method also includes: after the actual motor speed of the compressor increases to the target speed, if the phase voltage command value output by the controller is less than the second voltage limit value, the direct-axis current is controlled to increase according to a preset increment until the phase voltage command value output by the controller reaches the second voltage limit value.

[0009] In combination with the first aspect, in some embodiments, the first voltage limit value is determined according to a preset constant coefficient and the second voltage limit value, and the first voltage limit value is smaller than the second voltage limit value.

[0010] In combination with the first aspect, in some embodiments, the preset ratio value is in the range of 8 to 12.

[0011] In combination with the first aspect, in some embodiments, after obtaining the carrier ratio required to make the operating frequency of the compressor reach the target frequency, and the phase voltage command value output by the controller for controlling the compressor, it also includes: if the carrier ratio is greater than or equal to the preset ratio value, and the phase voltage command value output by the controller for controlling the compressor is greater than the second voltage limit value, the motor of the compressor is subjected to voltage closed-loop weak magnetic control; if the carrier ratio is greater than or equal to the preset ratio value, and the phase voltage command value output by the controller for controlling the compressor is less than or equal to the second voltage limit value, the motor of the compressor is subjected to MTPA control.

[0012] In combination with the first aspect, in some embodiments, after obtaining the carrier ratio required to make the operating frequency of the compressor reach the target frequency, it also includes: when the carrier ratio is less than the preset ratio value, if the phase voltage command value output by the controller for controlling the compressor is less than or equal to the first voltage limit value, MTPA control is performed on the motor of the compressor.

[0013] In a second aspect of the present invention, a control device for a compressor is provided, comprising: a data acquisition unit, for acquiring, during the operation of the compressor, a carrier ratio required for making the operating frequency of the compressor reach a target frequency, and a phase voltage command value output by a controller for controlling the compressor; a judgment execution unit, for judging whether it is necessary to negatively increase the direct-axis current of the compressor if the carrier ratio is less than a preset ratio and the phase voltage command value is greater than a first voltage limit value; and a control execution unit, for controlling the direct-axis current of the compressor to negatively increase to a current limit value if it is necessary to negatively increase the direct-axis current of the compressor, and maintaining the cross-axis voltage unchanged during the process of the direct-axis current negatively increasing to the current limit value, so that the actual motor speed of the compressor is increased to the target speed.

[0014] In a third aspect of the present invention, a variable frequency air conditioner is provided, comprising: a compressor; a processor; and a memory for storing instructions executable by the processor, wherein the processor is configured to execute the instructions to implement the compressor control method described in any embodiment of the first aspect.

[0015] In a fourth aspect of the present invention, a computer-readable storage medium is provided, on which a computer program is stored, characterized in that when the program is executed by a processor, the compressor control method described in any embodiment of the first aspect is implemented.

[0016] One or more technical solutions provided by the embodiments of the present invention achieve at least the following technical effects or advantages:

[0017] According to one or more embodiments provided by the present invention, when the carrier ratio required for the compressor's operating frequency to reach the target frequency is less than a preset ratio value and the phase voltage command value is greater than the first voltage limit value, the direct-axis current is controlled to increase negatively to the current limit value, and the quadrature-axis voltage is maintained unchanged during the process of the direct-axis current increasing negatively to the current limit value, so that when the motor of the compressor is at a high speed and low carrier ratio, there is enough voltage space for the direct-axis voltage to adjust the direct-axis current to follow the load changes. Thereby, the stability of weak magnetic control under low carrier ratio is improved, and the control stability of the compressor during high-frequency operation is also improved, and the maximum operating frequency of the compressor can be increased. It is also possible to increase the frequency increase rate during weak magnetic control, so that the operating frequency of the compressor reaches the target frequency faster, and the actual motor speed of the compressor is increased to the target speed faster. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 A flow chart showing a method for controlling a compressor according to some embodiments of the present invention is shown;

[0020] Figure 2 A schematic diagram showing the comparison between the actual phase voltage command output by the controller and the target phase voltage under different carrier ratios is shown;

[0021] Figure 3 The figure shows the change process of the motor speed and voltage when the motor is subjected to voltage closed-loop weak magnetic control and the current loop bandwidth is high according to some embodiments of the present invention;

[0022] Figure 4 The figure shows the change process of the speed waveform and voltage of the motor when the motor is subjected to high speed and low carrier ratio weak magnetic control according to some embodiments of the present invention;

[0023] Figure 5 A time delay schematic diagram of a compressor control system is shown;

[0024] Figure 6 A schematic diagram showing motor voltage closed-loop flux weakening control, motor vector control and angle delay compensation according to some embodiments of the present invention is shown;

[0025] Figure 7 The control logic of the compressor control method provided according to some embodiments of the present invention is shown;

[0026] Figure 8 A schematic diagram showing a control device for a compressor provided according to some embodiments of the present invention is shown;

[0027] Fig. 9 A schematic structural diagram of a variable frequency air conditioner provided according to some embodiments of the present invention is shown. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0030] A compressor control method provided in an embodiment of the present invention is used to control a variable frequency compressor, and can be applied to household appliances such as variable frequency air conditioners, variable frequency refrigerators or variable frequency washing machines equipped with variable frequency compressors. Figure 1 As shown, the compressor control method includes the following steps S101 to S103:

[0031] Step S101: during the operation of the compressor, obtaining a carrier ratio required for the operating frequency of the compressor to reach a target frequency, and a phase voltage command value output by a controller for controlling the compressor;

[0032] Step S102: if the carrier ratio is less than the preset ratio value, and the phase voltage command value is greater than the first voltage limit value, it is determined whether the direct axis current of the compressor needs to be negatively increased;

[0033] Step S103: If yes, control the compressor's direct-axis current to increase negatively to the current limit value, and maintain the compressor's quadrature-axis voltage unchanged during the process of the compressor's direct-axis current increasing negatively to the current limit value, so that the actual motor speed of the compressor increases to the target speed.

[0034] It can be understood that the phase voltage command value is calculated by the controller of the compressor, and the command for adjusting the motor phase voltage of the compressor is a value calculated by the controller through the current loop and the coordinate transformation after the current loop.

[0035] The number of pole pairs of the compressor motor is generally 2 or 3. For motors with 5 or more pole pairs, if the switching frequency of the controller is 6kHz, when the operating frequency of the compressor reaches 120Hz, the carrier ratio is 10 or even lower, calculated as follows: 10 = 6000Hz / (120HZ*5). When the carrier ratio is 10, the switching device of the inverter in the controller used to control the compressor can switch on and off at most 10 times in one electrical cycle, which seriously reduces the control performance and effect. Figure 2 As shown in the figure, the target phase voltage waveform, the actual phase voltage command when the carrier ratio is 50, and the actual phase voltage command when the carrier ratio is 10 are compared. It can be seen that when the carrier ratio is 50, the target phase voltage is basically consistent with the actual phase voltage command output by the controller. However, as the carrier ratio decreases, discretization will introduce a large number of harmonics, which will lead to a significant reduction in the dynamic performance of the motor using voltage closed-loop weak magnetic control at high speed and low carrier ratio, and will also affect the position observer that depends on the phase current command and phase voltage command.

[0036] In the steady state of the motor, the dq axis voltage u of the motor is d 、u q It can be expressed as the following formula (1):

[0037]

[0038] When the motor runs at high speed, the resistance voltage drop can be ignored, so the dq axis voltage u d 、u q It can be expressed as:

[0039]

[0040] In the above formulas (1) and (2), R represents the resistance of the motor, L d , L q are the direct-axis inductance and quadrature-axis inductance of the motor, i d 、i q Represent the direct axis current and quadrature axis current, ψ f represents the permanent magnet flux, ω e is the electrical angular velocity of the motor rotation.

[0041] It is understandable that the phase voltage of the motor Limited by the bus voltage of the controller, the phase voltage of the motor cannot increase infinitely. From the above formula (2), it can be seen that as the motor speed increases, the quadrature axis voltage u q Increasing; As the load increases, the quadrature axis current iq The increase in the direct-axis voltage u d The amplitude increases. The load and speed of the compressor under the same working condition are exactly related. Therefore, as the operating frequency of the compressor increases, the direct axis voltage u d and, quadrature axis voltage u q The amplitude of increases at the same time. In order to maintain the phase voltage not exceeding the limit value of the bus voltage, it is necessary to further increase the direct-axis current i negatively through voltage closed-loop weak magnetic control. d And reduce the quadrature axis voltage u q In order to improve the load capacity, it is also necessary to increase the direct axis voltage u d , forming a dynamic direct-axis voltage u d and the quadrature axis voltage u q Dual voltage regulation, under the dual voltage regulation of voltage closed-loop weak magnetic control, the direct axis voltage u d and the quadrature axis voltage u q The change process of Figure 3 shown. Figure 3 The figure shows the motor speed waveform and the direct axis voltage u when the motor is subjected to voltage closed-loop weak magnetic control. d , quadrature axis voltage u q and phase voltage command value u m The voltage waveform of Figure 3 It can be seen that when the current loop bandwidth is high, the dual voltage regulation process can be completed quickly, thereby quickly reaching the target frequency. However, in the case of high speed and low carrier ratio, the current loop bandwidth is reduced, and the amplitude of the phase voltage is also at a limit state. The voltage regulation process slows down and cannot cope with rapid speed increase requirements or load changes, and may even cause system instability. Through the above step S102, the direct-axis current is controlled to increase negatively to the current limit value, and the cross-axis voltage is maintained unchanged during the process of the direct-axis current negatively increasing to the current limit value, so that there is enough voltage space for the direct-axis voltage u in the case of high speed and low carrier ratio. d To adjust the quadrature axis current i q Following the changes in load, the operating frequency of the compressor can quickly reach the target frequency under the conditions of high speed and low carrier ratio, so that the actual motor speed of the compressor can be quickly increased to the target speed, and the stability of weak magnetic control under high speed and low carrier ratio is improved, thereby increasing the maximum operating frequency of the compressor.

[0042] In some embodiments, the carrier ratio required to make the operating frequency of the compressor reach the target frequency is obtained in real time. After each time the carrier ratio required to make the operating frequency of the compressor reach the target frequency is obtained; it is determined whether the carrier ratio currently obtained is less than a preset ratio value; if the carrier ratio currently obtained is less than the preset ratio value, a phase voltage command value output by a controller for controlling the compressor is obtained; if the phase voltage command value is greater than the first voltage limit value, it indicates that the compressor has entered a high speed and low carrier ratio state, and high speed and low carrier ratio weak magnetic control is performed on the motor. High speed and low carrier ratio weak magnetic control of the motor includes: determining whether it is necessary to increase the direct-axis current of the compressor in a negative direction; if it is necessary to increase the direct-axis current of the compressor in a negative direction, controlling the direct-axis current of the compressor to increase negatively to the current limit value, and maintaining the cross-axis voltage unchanged during the process of the direct-axis current of the compressor increasing negatively to the current limit value, so that there is enough voltage space for the direct-axis voltage u under the condition of high speed and low carrier ratio. d To adjust the quadrature axis current i q Follow the load changes.

[0043] In some embodiments, the preset ratio value is in the range of 8 to 12. It is understandable that the preset ratio value can be set to 8, 9, 10, 11 or 12. In some embodiments, in step S102, the direct axis current can be controlled to increase negatively to the current limit value by a PI controller.

[0044] In some embodiments, determining whether it is necessary to negatively increase the direct-shaft current of the compressor includes: detecting the actual motor speed of the compressor and the actual direct-shaft current of the compressor to obtain a first speed value and a first current value; if the first speed value is less than the target speed and the first current value is less than the current limit value, it indicates that the direct-shaft current of the compressor needs to be negatively increased.

[0045] In some embodiments, it is determined whether the first speed value is less than the target speed; if the first speed value is less than the target speed, it is determined whether the first current value is less than the current limit value; if the first current value is less than the current limit value, it indicates that the direct-axis current of the compressor needs to be negatively increased.

[0046] In some embodiments, controlling the direct-shaft current of the compressor to increase negatively to a current limiting value includes: controlling the direct-shaft current of the compressor to increase negatively through a PI controller; obtaining the actual motor speed of the compressor and the actual direct-shaft current of the compressor after the direct-shaft current of the compressor is negatively increased, so as to obtain a second speed value and a second current value; if the second speed value is less than the target speed and the second current value is less than the current limiting value, returning to the step of controlling the direct-shaft current to increase negatively through the PI controller to negatively increase the direct-shaft current of the compressor for the next time; otherwise, it indicates that the direct-shaft current of the compressor has reached the current limiting value, stopping the negative increase of the direct-shaft current of the compressor, and maintaining the direct-shaft current of the compressor unchanged at the current limiting value.

[0047] In some embodiments, controlling the direct-axis current of the compressor to increase negatively through a PI controller may include: performing PI regulation on the direct-axis current according to the difference between the given value of the quadrature-axis voltage and the quadrature-axis voltage output by the current loop, so as to increase the direct-axis current of the compressor negatively.

[0048] It can be understood that the negative increase of the direct-axis current means that the current direction of the given direct-axis current is negative, and the current value increases. Since the current direction of the given direct-axis current is a current value in the negative direction (for example: -9A) during magnetic field weakening control, the permanent magnet magnetic flux is weakened, and the direct-axis current is PI-regulated according to the difference between the given value of the quadrature-axis voltage and the quadrature-axis voltage output by the current loop, so that the current value in the negative direction given for the direct-axis current increases. For example, through PI regulation, the direct-axis current increases from -9A to -10A.

[0049] In some embodiments, the quadrature axis voltage is given a value u qset The quadrature axis voltage u of the current loop output q The difference is input to the PI controller of the weak magnetic ring to obtain the required direct axis current reference value i d-ref And input into the current loop: i d-ref =PI(u qset -u q ) so that the direct-axis current can increase negatively, and then the direct-axis current is closer to the current limit value. The direct-axis current is continuously increased negatively through the PI adjustment of the weak magnetic ring until the direct-axis current negatively increases to the current limit value. After the direct-axis current negatively increases to the current limit value, the direct-axis current remains unchanged at the current limit value. At this time, the quadrature-axis voltage u q It will increase as the actual motor speed of the compressor increases.

[0050] In some embodiments, the quadrature axis voltage given value u qset Less than the maximum voltage u that the controller's inverter can output max , according to the maximum voltage u that the inverter can output max Multiplying the product with a coefficient less than 1 gives the quadrature axis voltage given value u qset .

[0051] Figure 4 The figure shows the speed waveform and direct-axis voltage u of the motor when the motor is subjected to high-speed and low-carrier ratio weak magnetic control. d , quadrature axis voltage u q and phase voltage command value u m The voltage waveform from Figure 4 It can be seen that during the motor speed increase process of the compressor, the quadrature axis voltage u qGradually increases to a certain value, the required phase voltage exceeds the maximum value that the bus voltage can provide, then the quadrature axis voltage u q Entering the holding stage, the quadrature axis voltage u q The holding phase increases the direct-axis current i in the negative direction. d To reduce the phase voltage and increase the speed, until the direct axis current i d Increase to the current limit value; then, the direct axis current i d Keep the current limit unchanged, the quadrature axis voltage u q Continue to increase so that the actual motor speed of the compressor continues to increase until the actual motor speed increases to the target speed.

[0052] It is understandable that the current limit value is determined by the actual parameters of the motor and the external motor control (including the inverter, etc.) of the compressor to prevent the output current from exceeding the safe range allowed by the motor and the external motor control to protect the electronic components of the motor and the external motor control. Therefore, the current limit values ​​of different compressors are different, and the specific value of the current limit value is not limited here. In some embodiments, the current limit value can be set according to the maximum allowable current of the motor: less than or equal to the maximum allowable current of the motor. Of course, a dynamic current limit value can also be used.

[0053] It is understandable that after the actual motor speed of the compressor reaches the target speed, there may still be voltage margin. In some embodiments, after the actual motor speed of the compressor increases to the target speed, if the phase voltage command value output by the controller is less than the second voltage limit value, indicating that there is still voltage margin, the direct-axis current is controlled to increase according to the preset increment so that the direct-axis current increases slowly until the phase voltage command value output by the controller reaches the second voltage limit value. Exemplarily, the preset increment is 1A, the current direct-axis current is -10A, the direct-axis current is controlled to increase for the first time according to the preset increment, so that the direct-axis current increases to -9A, the direct-axis current is controlled to increase for the second time according to the preset increment, and the direct-axis current increases to -8A, and so on, until the phase voltage command value output by the controller reaches the second voltage limit value.

[0054] The first voltage limit value and the second voltage limit value are set to protect the electronic components of the motor and the external machine electronic control to prevent the output voltage from exceeding the allowable range of the motor and the external machine electronic control. In some embodiments, the first voltage limit value is determined based on a preset constant coefficient and the second voltage limit value, and the first voltage limit value is less than the second voltage limit value.

[0055] In some embodiments, the first voltage limit value is the product of a preset constant coefficient and the second voltage limit value, and the preset constant coefficient is a decimal less than 1 and close to 1. The first voltage limit value is ku Limit , the second voltage limit value is u Limit, k is a preset constant coefficient, satisfying 0.8<k<1, and in some embodiments, k=0.9. It should be noted that the second voltage limit value is related to the bus voltage of the compressor, and can be calculated by multiplying the bus voltage of the compressor by the modulation ratio of the pulse width modulation performed by the controller.

[0056] When the carrier is relatively low, the delay of the compressor control system cannot be ignored, such as Figure 5 As shown, after sampling the current i(t) at time t, the corresponding phase voltage command value and the PWM (Pulse-width modulation) duty cycle D(t) are calculated, and the PWM duty cycle D(t) is updated at time t+Ts, where Ts represents the PWM control period, that is, the carrier period. Therefore, there is a one-beat delay link in the control system. When the carrier ratio is relatively low, for example, when the carrier ratio is 10, a one-beat delay will cause the angle error of the motor to reach 36°, which will seriously affect the dynamic performance of the current loop, aggravate the coupling of the dq axes, and also cause the current to be too large and the control system to be unstable. Especially after entering the voltage closed-loop weak magnetic control, the lag of the PWM control and the decrease in the current loop bandwidth under high speed and low carrier ratio cause the dq axis current to be unable to keep up with the increase in motor speed or the current required for the increase in load in time, resulting in reduced performance of the weak magnetic loop or even loss of control. Therefore, in some embodiments, the control method of the compressor provided in the embodiments of the present invention also includes delay compensation for the control system. As Figure 6 As shown, assuming that the instantaneous speed of the motor remains unchanged, the angle the motor rotates during the delay process is ω e T s ,ω e is the electrical angular velocity of the motor, T s is the control delay time, T s The same as the carrier period of the control. Therefore, in order to compensate for the delay of the control system, the angle of the position observer should be advanced by ω in the coordinate transformation link after the current loop calculates the voltage command. e T s , delay compensation is performed on the control system, including: calculating the phase voltage command value according to the sum of the motor angle calculated by the position observer and the angle delay compensation, wherein the angle delay compensation is the angle that the motor rotates during the delay process. Figure 4 As shown in the figure, the angle θ actually used to calculate the phase voltage command value comp =θ est +ω e T s , where θ est Represents the motor angle calculated by the position observer. Angle delay compensation at least solves the current deviation and high degree of dq axis coupling caused by angle error to a certain extent, and realizes delay compensation of the control system.

[0057] In some embodiments, the control method of the compressor provided in an embodiment of the present invention may also include the following step S103: if the carrier ratio is greater than or equal to the preset ratio value, and the phase voltage command value output by the controller is greater than the second voltage limit value, the compressor motor is subjected to voltage closed-loop weak magnetic control.

[0058] In some embodiments, the control method of the compressor provided in an embodiment of the present invention may also include the following step S104: if the carrier ratio is greater than or equal to the preset ratio value, and the phase voltage command value output by the controller is less than or equal to the second voltage limit value, MTPA control is performed on the motor of the compressor, so that the maximum output electromagnetic torque can be obtained with the minimum current, and the requirements for the inverter and the power loss can also be reduced.

[0059] In some embodiments, when the carrier ratio currently obtained is greater than or equal to a preset ratio value, it is determined whether the phase voltage command value output by the controller is greater than the second voltage limit value. If so, the compressor motor is subjected to voltage closed-loop weak magnetic control; if not, the compressor motor is subjected to MTPA (Maximum Torque Per Ampere, maximum torque current ratio) control, so that the maximum output electromagnetic torque can be obtained with the minimum current.

[0060] It is understandable that if Figure 6 As shown, the motor is subjected to voltage closed-loop weak magnetic control, including: the maximum voltage u output by the inverter of the controller max The voltage value u of the current loop output S The difference is input to the PI controller of the weak magnetic ring to obtain the required direct axis current reference value i d-ref And input to the current loop so that the direct axis current i d The negative increase reduces the phase voltage of the motor. In the voltage closed-loop weak magnetic control of the motor, the speed loop, current loop, coordinate transformation, position estimation and SVPWM calculation process can refer to the relevant technologies and Figure 6 At the same time, the quadrature axis voltage u q and increase the direct axis voltage u d , forming a dynamic direct-axis voltage u d and the quadrature axis voltage u q Dual voltage regulation is achieved to realize voltage closed-loop weak magnetic control to increase motor speed.

[0061] In some embodiments, if the carrier ratio is less than a preset ratio value, and the phase voltage command value output by the controller for controlling the compressor is less than or equal to the first voltage limit value, MTPA control is performed on the motor of the compressor.

[0062] In order to facilitate understanding of the compressor control method provided by the embodiment of the present invention, Figure 7 , a control logic of the control method of the compressor provided by the embodiment of the present invention is given:

[0063] Step S1: During the operation of the compressor, the required carrier ratio N is calculated according to the switching frequency fs of the controller, the target frequency fn of the compressor operation and the number of pole pairs Pn of the motor: N = f s / f n P n ;

[0064] Step S2: Determine whether the required carrier ratio N is less than a preset ratio value N1: N<N1, if yes, proceed to step S3, if no, proceed to step S10;

[0065] Step S3: Determine the phase voltage command value U output by the controller m Is it greater than the first voltage limit value kU Limit :U m >kU Limit If yes, proceed to step S4 to S9 to perform high speed and low carrier ratio weak magnetic control on the motor; if no, proceed to step S11;

[0066] Step S4: Determine whether the actual motor speed n1 of the compressor is less than the target speed n: n1 < n? If yes, proceed to step S5; if no, proceed to step S7;

[0067] Step S5: Determine whether the direct-axis current is less than the current limit value: i d <i dlimit ? If yes, go to step S6, if no, go to step S4;

[0068] Step S6: Control the direct-axis current to increase in the negative direction through the PI controller: PI(u qset -u q ), and return to step S4;

[0069] Step S7: Maintain the actual motor speed of the compressor at the target speed: maintain n=n1, and proceed to step S8;

[0070] Step S8: Determine the phase voltage command value U m Is it less than the second voltage limit value U Limit :U m <U Limit ? If yes, go to step S9, if no, end the current high speed and low carrier ratio weak magnetic control;

[0071] Step S9: Increase the direct-axis current according to a preset increment: i d ++, and return to step S8;

[0072] Step S10: Determine whether the phase voltage command value output by the controller is greater than the second voltage limit value: U m >U Limit ? If yes, go to step S12, if no, go to step S11;

[0073] Step S11: performing MTPA control on the motor of the compressor;

[0074] Step S12: Perform voltage closed-loop magnetic weakening control on the motor of the compressor.

[0075] Based on the same inventive concept, an embodiment of the present invention provides a compressor control device, which can be applied to household appliances with variable frequency compressors, such as variable frequency air conditioners, variable frequency refrigerators or variable frequency washing machines.

[0076] like Figure 8 As shown, the control device of the compressor includes: a data acquisition unit 801, which is used to acquire the carrier ratio required for making the operating frequency of the compressor reach the target frequency, and the phase voltage command value output by the controller for controlling the compressor during the operation of the compressor; a judgment execution unit 802, which is used to judge whether it is necessary to negatively increase the direct-axis current of the compressor if the carrier ratio is less than a preset ratio value and the phase voltage command value is greater than a first voltage limit value; a control execution unit 803, which is used to control the direct-axis current of the compressor to increase negatively to the current limit value if it is necessary to negatively increase the direct-axis current of the compressor, and maintain the cross-axis voltage unchanged during the process of the direct-axis current negatively increasing to the current limit value, so that the actual motor speed of the compressor is increased to the target speed.

[0077] In some embodiments, the judgment execution unit 802 is used to: detect the actual motor speed of the compressor and the actual direct-shaft current of the compressor to obtain a first speed value and a first current value; if the first speed value is less than the target speed, and the first current value is less than the current limit value, it indicates that the direct-shaft current of the compressor needs to be negatively increased.

[0078] In some embodiments, the control execution unit 803 includes: a first execution subunit, used to: control the direct-axis current of the compressor to increase negatively through a PI controller; obtain the actual motor speed and the actual direct-axis current of the compressor after the direct-axis current of the compressor is negatively increased, so as to obtain a second speed value and a second current value; if the second speed value is less than the target speed, and the second current value is less than the current limit value, return to the step of controlling the direct-axis current to increase negatively through the PI controller, otherwise, stop negatively increasing the direct-axis current of the compressor.

[0079] In some embodiments, the control execution unit 802 also includes a second execution sub-unit, which is used to: after the actual motor speed of the compressor increases to the target speed, if the phase voltage command value output by the controller is less than the second voltage limit value, control the direct-axis current to increase according to a preset increment until the phase voltage command value output by the controller reaches the second voltage limit value.

[0080] In some embodiments, the first voltage limit value is determined according to a preset constant coefficient and the second voltage limit value, and the first voltage limit value is smaller than the second voltage limit value.

[0081] In some embodiments, the preset ratio value is in the range of 8 to 12.

[0082] In some embodiments, the control execution unit 802 also includes: a third execution sub-unit, which is used to perform voltage closed-loop weak magnetic control on the motor of the compressor if the carrier ratio is greater than or equal to the preset ratio value, and the phase voltage command value output by the controller for controlling the compressor is greater than the second voltage limit value; if the carrier ratio is greater than or equal to the preset ratio value, and the phase voltage command value output by the controller for controlling the compressor is less than or equal to the second voltage limit value, perform MTPA control on the motor of the compressor.

[0083] In some embodiments, the control execution unit 802 also includes: a fourth execution sub-unit, which is used to perform MTPA control on the motor of the compressor when the carrier ratio is less than the preset ratio value and if the phase voltage command value output by the controller for controlling the compressor is less than or equal to the first voltage limit value.

[0084] The specific functions of each functional unit in the above device have been described in detail in the compressor control method provided in some embodiments of the present invention, and will not be elaborated here.

[0085] Based on the same inventive concept, the present invention also provides a variable frequency air conditioner, such as Fig. 9 As shown, the variable frequency air conditioner includes: a compressor; a processor 902; and a memory 904 for storing executable instructions of the processor 902, wherein the processor 902 is configured to execute the instructions to implement the compressor control method described in any one of the above embodiments.

[0086] Among them, Fig. 9In the embodiment of the present invention, a bus architecture (represented by bus 900) is shown, and bus 900 may include any number of interconnected buses and bridges, and bus 900 links various circuits including one or more processors represented by processor 902 and memory represented by memory 904. Bus 900 may also link various other circuits such as peripherals, voltage regulators, and power management circuits, which are well known in the art and are therefore not further described herein. Bus interface 905 provides an interface between bus 900 and receiver 901 and transmitter 903. Receiver 901 and transmitter 903 may be the same element, namely a transceiver, providing a unit for communicating with various other devices over a transmission medium. Processor 902 is responsible for managing bus 900 and general processing, while memory 904 may be used to store data used by processor 902 when performing operations.

[0087] Based on the same inventive concept, an embodiment of the present invention further provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the compressor control method of any of the above embodiments is implemented.

[0088] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0089] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0090] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0091] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0092] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0093] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for controlling a compressor, characterized in that: include: During the operation of the compressor, obtaining a carrier ratio required to make the operating frequency of the compressor reach a target frequency, and a phase voltage command value output by a controller for controlling the compressor; If the carrier ratio is less than the preset ratio value, and the phase voltage command value is greater than the first voltage limit value, determining whether the direct axis current of the compressor needs to be negatively increased; If so, the direct-axis current of the compressor is controlled to increase negatively to the current limit value, and the quadrature-axis voltage of the compressor is maintained unchanged during the process of the direct-axis current of the compressor increasing negatively to the current limit value, so that the actual motor speed of the compressor is increased to the target speed.

2. The method according to claim 1, characterized in that The determining whether it is necessary to negatively increase the direct-axis current of the compressor comprises: Detecting an actual motor speed of the compressor and an actual direct-axis current of the compressor to obtain a first speed value and a first current value; If the first speed value is smaller than the target speed, and the first current value is smaller than the current limit value, it indicates that the direct-axis current of the compressor needs to be negatively increased.

3. The method according to claim 1, characterized in that The controlling the direct-axis current of the compressor to increase negatively to a current limit value comprises: The direct-axis current of the compressor is controlled to increase negatively by a PI controller; Acquire the actual motor speed of the compressor and the actual direct-axis current of the compressor after the direct-axis current of the compressor is negatively increased, so as to obtain a second speed value and a second current value; If the second speed value is less than the target speed and the second current value is less than the current limit value, return to the step of controlling the direct-axis current to increase negatively through the PI controller; otherwise, stop negatively increasing the direct-axis current of the compressor.

4. The method according to claim 1, characterized in that Also includes: After the actual motor speed of the compressor increases to the target speed, if the phase voltage command value output by the controller is less than the second voltage limit value, the direct-axis current is controlled to increase according to a preset increment until the phase voltage command value output by the controller reaches the second voltage limit value.

5. The method according to claim 3, characterized in that The first voltage limit value is determined according to a preset constant coefficient and the second voltage limit value, and the first voltage limit value is smaller than the second voltage limit value.

6. The method according to claim 1, characterized in that The preset ratio value is in the range of 8 to 12.

7. The method according to claim 1, characterized in that After obtaining the carrier ratio required to make the operating frequency of the compressor reach the target frequency and the phase voltage command value output by the controller for controlling the compressor, the method further includes: If the carrier ratio is greater than or equal to the preset ratio value, and the phase voltage command value output by the controller for controlling the compressor is greater than the second voltage limit value, voltage closed-loop magnetic weakening control is performed on the motor of the compressor; If the carrier ratio is greater than or equal to the preset ratio value, and the phase voltage command value output by the controller for controlling the compressor is less than or equal to the second voltage limit value, MTPA control is performed on the motor of the compressor.

8. The method according to claim 1, characterized in that After obtaining the carrier ratio required to make the operating frequency of the compressor reach the target frequency, the method further includes: In the case where the carrier ratio is smaller than the preset ratio value, if the phase voltage command value output by the controller for controlling the compressor is smaller than or equal to the first voltage limit value, MTPA control is performed on the motor of the compressor.

9. A compressor control device, characterized in that: include: A data acquisition unit, used to acquire, during the operation of the compressor, a carrier ratio required to make the operating frequency of the compressor reach a target frequency, and a phase voltage command value output by a controller for controlling the compressor; A judgment execution unit, configured to judge whether it is necessary to negatively increase the direct-axis current of the compressor if the carrier ratio is less than a preset ratio value and the phase voltage command value is greater than a first voltage limit value; The control execution unit is used to control the direct-axis current of the compressor to increase negatively to a current limit value if it is necessary to increase the direct-axis current of the compressor negatively, and to maintain the cross-axis voltage unchanged during the process of the direct-axis current negatively increasing to the current limit value, so as to increase the actual motor speed of the compressor to the target speed.

10. A variable frequency air conditioner, characterized in that: include: compressor; processor; A memory for storing instructions executable by the processor, wherein the processor is configured to execute the instructions to implement the compressor control method according to any one of claims 1 to 9.

11. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the compressor control method according to any one of claims 1 to 9 is implemented.

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