Current control method, circuit, air conditioner and storage medium of three-phase power supply

Abstract

The application discloses a current control method and circuit of a three-phase power supply, an air conditioner and a storage medium, wherein the current control method of the three-phase power supply comprises the following steps: obtaining a stable bus reference voltage according to a first bus voltage of a switching power supply history; obtaining a current regulation value according to the bus reference voltage, a second bus voltage and a pre-stored feedforward coefficient; obtaining an axis voltage before each current axis input motor, and obtaining a voltage state of the second bus voltage according to the second bus voltage and the axis voltage; determining a target current axis to be regulated from multiple current axes according to the voltage state, and feeding back and regulating the current of the target current axis according to the current regulation value, so as to stabilize the bus voltage obtained after the actual current is transformed. The technical scheme aims to improve the response speed of the current loop, so as to reduce the occurrence of the situation that the air conditioner is out of control and stops.

Description

Technical Field

[0001] This invention relates to the field of air conditioner technology, and in particular to a current control method, circuit, air conditioner, and storage medium for a three-phase power supply. Background Technology

[0002] Currently, for large air conditioners with a single-phase input current exceeding 16A, industry regulations no longer require harmonic limitations. Therefore, when setting up the circuit topology, three-phase PFC topology is no longer used; instead, the rectified and filtered bus voltage is directly inverted to control the motor. In this case, if the three-phase power supply experiences significant fluctuations, it will directly cause rapid fluctuations in the bus voltage. This can easily lead to the motor control loop being unable to respond in time, causing the fluctuations to exceed the controllable range and resulting in the air conditioner shutting down uncontrollably. Summary of the Invention

[0003] The main objective of this invention is to provide a current control method, circuit, air conditioner, and storage medium for a three-phase power supply, aiming to improve the response speed of the current loop and reduce the occurrence of uncontrolled shutdown of the air conditioner.

[0004] To achieve the above objectives, the present invention proposes a three-phase power supply current control method, applied to a switching power supply for controlling a motor. The switching power supply has multiple current axes, including:

[0005] A stable bus reference voltage is obtained based on the first bus voltage in the history of the switching power supply.

[0006] Obtain the current second bus voltage, and obtain the current adjustment value based on the bus reference voltage, the second bus voltage, and the pre-stored feedforward coefficient;

[0007] Obtain the shaft voltage before each current axis inputs to the motor, and obtain the voltage state of the second bus voltage based on the second bus voltage and the shaft voltage;

[0008] Based on the voltage state, the target current axis to be adjusted is determined from multiple current axes, and the current of the target current axis is adjusted by feedback according to the current adjustment value to stabilize the bus voltage obtained after the actual current has been transformed.

[0009] In some embodiments, obtaining the current regulation value based on the bus reference voltage, the second bus voltage, and the pre-stored feedforward coefficient specifically includes:

[0010] The current voltage deviation is obtained by subtracting the bus reference voltage from the second bus voltage.

[0011] The product of the current voltage deviation and the feedforward coefficient is used as the current adjustment value.

[0012] In some embodiments, the plurality of current axes include quadrature axes and direct axes. The step of acquiring the shaft voltage before each current axis is input to the motor, and acquiring the voltage state of the second bus voltage based on the second bus voltage and the shaft voltage; determining the target current axis to be adjusted from the plurality of current axes based on the voltage state includes:

[0013] Obtain the current quadrature-axis voltage and current direct-axis voltage of the motor, and determine the voltage utilization rate of the second bus voltage based on the second bus voltage, the current quadrature-axis voltage, and the current direct-axis voltage;

[0014] If the voltage utilization rate does not reach the preset utilization rate, it is determined that the second bus voltage is in an unsaturated state, and the quadrature axis is determined to be the target current axis to be adjusted.

[0015] If the voltage utilization rate reaches the preset utilization rate, it is determined that the second bus voltage is in a saturated state, and the direct axis and the quadrature axis are determined to be the target current axis to be adjusted.

[0016] In some embodiments, determining the voltage utilization rate of the second bus voltage based on the second bus voltage, the current quadrature-axis voltage, and the current direct-axis voltage specifically includes:

[0017] The current quadrature-axis voltage and the current direct-axis voltage are converted to obtain the current voltage value in the quadrature-direct-axis coordinate system;

[0018] The voltage utilization rate is determined based on the relationship between the voltage utilization rate of the second bus voltage and the current voltage value and the second bus voltage in the perpendicular axis coordinate system.

[0019] In some embodiments, the current axis includes a quadrature axis and a direct axis, and the feedback adjustment of the current of the target current axis according to the current adjustment value specifically includes:

[0020] When the target current axis is the quadrature axis, the actual current of the quadrature axis is adjusted based on the current adjustment value.

[0021] When the target current axis is both the quadrature axis and the direct axis, the actual current of the quadrature axis and the direct axis is adjusted according to the current adjustment value.

[0022] In some embodiments, when the target current axis is a quadrature axis, the feedback adjustment of the current of the quadrature axis according to the current adjustment value specifically includes:

[0023] Obtain the first cross-axis actual current of the cross-axis;

[0024] The actual speed of the motor is obtained, and a preset given speed and the deviation value of the actual speed are obtained;

[0025] The preset first cross-axis given current is adjusted based on the deviation value, the current adjustment value, and the actual current of the first cross-axis, wherein the first cross-axis given current is positively correlated with the current adjustment value;

[0026] The actual current of the first cross-axis is adjusted based on the adjusted first cross-axis given current.

[0027] In some embodiments, when the target current axis is both the quadrature axis and the direct axis, the feedback adjustment of the current of the quadrature axis and the direct axis according to the current adjustment value specifically includes:

[0028] Obtain the second cross-axis actual current of the cross-axis and the direct axis actual current of the direct axis;

[0029] The preset direct-axis given current is adjusted according to the current adjustment value, and the actual direct-axis current is adjusted according to the adjusted direct-axis given current, wherein the direct-axis given current is positively correlated with the current adjustment value.

[0030] The actual speed of the motor is obtained, and the preset second quadrature axis given current is adjusted according to the deviation between the preset given speed and the actual speed, as well as the adjusted direct axis actual current.

[0031] The actual current of the second quadrature axis is adjusted based on the adjusted given current of the second quadrature axis.

[0032] This invention also proposes a current control circuit for use in a switching power supply for controlling a motor. The switching power supply has multiple current axes, including:

[0033] An error acquisition module, wherein the input terminal of the error acquisition module is electrically connected to the motor to obtain a stable bus reference voltage based on the historical first bus voltage of the switching power supply; and to acquire the current second bus voltage and obtain a current adjustment value based on the bus reference voltage, the second bus voltage and a pre-stored feedforward coefficient.

[0034] A feedback control loop, wherein the output of the feedback control loop is connected to the controlled end of the motor;

[0035] A main control chip, electrically connected to the motor, is used to acquire the shaft voltage before each current axis inputs to the motor, and to acquire the voltage state of the second bus voltage based on the second bus voltage and the shaft voltage; and,

[0036] Based on the voltage state, the target current axis to be adjusted is determined from multiple current axes, and the feedback control loop is controlled to adjust the current of the target current axis according to the current adjustment value, so as to stabilize the bus voltage obtained after the current of the target current axis has been transformed.

[0037] The present invention also proposes an air conditioner, which includes the above-described current control circuit.

[0038] The present invention also proposes a storage medium comprising the above-described three-phase power supply current control method.

[0039] The technical solution of this invention obtains the corresponding bus reference voltage based on the historical first bus voltage of the switching power supply, and obtains the corresponding current adjustment value based on the deviation between the second bus voltage and the bus reference voltage. This enables direct monitoring of the bus voltage, avoiding the lag of the previous method of indirectly adjusting the bus voltage by feedback from the voltage output of the inverter circuit. Furthermore, after determining the voltage state of the second bus voltage, the technical solution of this invention directly adjusts the current axis corresponding to the voltage state based on the current adjustment value, further improving the response speed of the current loop. This ensures that the bus voltage obtained after the actual current of the current axis is transformed is stable, reducing the occurrence of uncontrolled shutdown of the air conditioner due to the motor control loop not responding in time. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0041] Figure 1 This is a flowchart illustrating an embodiment of the current control method for a three-phase power supply according to the present invention.

[0042] Figure 2 This is a schematic diagram of the process S200 in this invention;

[0043] Figure 3 This is a schematic diagram of the process S300 in this invention;

[0044] Figure 4 This is a schematic diagram of the process of S310 in this invention;

[0045] Figure 5 This is a schematic diagram of the process S400 in this invention;

[0046] Figure 6This is a schematic diagram of the process S410 in this invention;

[0047] Figure 7 This is a schematic diagram of the process S420 in this invention;

[0048] Figure 8 This is a schematic diagram of the structure of an embodiment of the current control circuit of the present invention;

[0049] Figure 9 This is a schematic diagram of another embodiment of the current control circuit of the present invention;

[0050] Figure 10 This is a schematic diagram of an existing switching power supply.

[0051] Figure 11 This is a feedback loop diagram of an embodiment of the current control circuit of the present invention;

[0052] Figure 12 This is a feedback loop diagram of another embodiment of the current control circuit of the present invention.

[0053] Explanation of icon numbers:

[0054] label name label name 510 Error acquisition module 520 Feedback control loop 511 Filtering module 530 Main control chip 512 Bus voltage feedforward module

[0055] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0056] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0057] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0058] This invention proposes a current control method for a three-phase power supply.

[0059] It should be noted that, as Figure 10As shown, for large air conditioners with a current of 16A or more, their switching power supply consists directly of a rectifier circuit and an inverter circuit, without a PFC (Power Factor Correction) circuit for power factor correction. Therefore, if the three-phase power supply input to the rectifier circuit experiences large fluctuations, it will directly cause rapid fluctuations in the bus voltage. However, the existing motor control loop provides feedback on the motor input voltage, which is also feedback on the output voltage of the inverter circuit. This means that the motor control loop can only adjust after the fluctuation is transmitted to the output of the inverter circuit. It is easy for the motor control loop to be unable to respond in time, causing the bus voltage fluctuation to exceed the controllable range, resulting in uncontrolled shutdown.

[0060] To solve the above problems, refer to Figure 1 , Figure 9 , Figure 11 and Figure 12 In one embodiment, it is applied to a switching power supply, the switching power supply including a current axis having an actual current and a given current, including:

[0061] S100. Obtain a stable bus reference voltage based on the first bus voltage in the history of the switching power supply.

[0062] In this embodiment, the switching power supply can be equipped with a filter circuit to perform deep filtering on the historical first bus voltage to obtain a stable constant as the bus reference voltage. Alternatively, an analog-to-digital conversion circuit can be set to obtain the median of the historical first bus voltage over a period of time as the bus reference voltage.

[0063] Furthermore, the bus reference voltage can be the median, average, or other values ​​of the historical first bus voltage over a period of time (such as a time period corresponding to a sampling period of 10 minutes, 15 minutes, etc.).

[0064] S200: Obtain the current second bus voltage, and obtain the current adjustment value based on the bus reference voltage, the second bus voltage, and the pre-stored feedforward coefficient;

[0065] In this embodiment, the feedforward coefficient is set by the R&D personnel during the design phase according to the transfer function of the voltage feedforward module, so that when the voltage feedforward module is working, it can convert the deviation between the bus reference voltage and the second bus voltage into a corresponding current value according to its transfer function to compensate for the current of the feedback loop. The converted current value is the current adjustment value.

[0066] S300: Obtain the shaft voltage before each current shaft inputs to the motor, and obtain the voltage state of the second bus voltage based on the second bus voltage and the shaft voltage;

[0067] It should be noted that during the operation of the switching power supply, the bus voltage is not always in a stable state, but will fluctuate periodically. However, if the bus voltage fluctuates due to power grid fluctuations, causing it to follow the fluctuations of the input three-phase power supply and exceed the preset fluctuation range, the existing feedback loop will be unable to adjust the bus voltage in a timely manner. The preset fluctuation range is the controllable range of the aforementioned feedback loop, which is derived by the R&D personnel based on a large number of experimental results during the design process.

[0068] In this embodiment, the current axis includes a quadrature axis and a direct axis. The quadrature axis is used to control the magnetic field of the motor, and the direct axis is used to control the torque of the motor.

[0069] During motor operation, the operating state of the current shaft varies depending on the current state of the second bus voltage. The operating state can be determined based on the ratio of the maximum amplitude of the fundamental AC voltage output by the inverter circuit to the current second bus voltage. When the maximum amplitude of the fundamental AC voltage to the current second bus voltage does not exceed a preset ratio, it indicates that the voltage is in an unsaturated state. At this time, there is no current input to the direct shaft of the motor. Therefore, if the fluctuation of the current second bus voltage exceeds the preset fluctuation range, only the current loop of the quadrature shaft needs to be compensated. Thus, the main control chip 530 controls the voltage feedforward module to input the current adjustment value to the current loop input terminal of the quadrature shaft. When the maximum amplitude of the fundamental AC voltage to the current second bus voltage exceeds a preset ratio, it indicates that the voltage is in a saturated state. At this time, there is current input to the direct shaft of the motor. Therefore, if the fluctuation of the current second bus voltage exceeds the preset fluctuation range, it is necessary to compensate for the current loops of both the direct shaft and the quadrature shaft simultaneously. Since the current of the quadrature shaft can be converted through the direct shaft, the main control chip 530 can directly control the voltage feedforward module to input only the current adjustment value to the current loop input terminal of the direct shaft, and then achieve simultaneous compensation for the current loops of both the direct shaft and the quadrature shaft through current conversion.

[0070] S400. Determine the target current axis to be adjusted from multiple current axes according to the voltage state, and adjust the current of the target current axis according to the current adjustment value to stabilize the bus voltage obtained after the actual current is transformed.

[0071] In this embodiment, the current of the target current axis includes the actual current and the given current. The actual current is the motor current output value of the current axis, and the given current is the target current of the current axis. Specifically, when the switching power supply performs feedback regulation on the second bus voltage, the actual current after feedback regulation will undergo two transformation processes to obtain the second bus voltage corresponding to the actual current. Therefore, when the fluctuation of the second bus voltage exceeds the preset fluctuation range, the present invention inputs the current regulation value into the feedback loop of the current axis to be regulated. The feedback loop will adjust the given current of the current axis according to the input current regulation value, and then perform feedback control on the actual current according to the given current to make the actual current gradually approach the given current, thereby changing the actual current of the current axis and thus changing the second bus voltage corresponding to the actual current. The given current is the target current of the current axis.

[0072] When the current second bus voltage drops, the current adjustment value is positive, increasing the given current of the current axis. As a result, after the actual current is controlled by feedback based on the given current, the actual current of the current axis increases, and the corresponding second bus voltage after transformation also increases. When the second bus voltage rises rapidly, the current adjustment value is negative, decreasing the given current of the current axis. As a result, after the actual current is controlled by feedback based on the given current, the actual current of the current axis decreases, and the corresponding second bus voltage after transformation also decreases.

[0073] The technical solution of this invention obtains the corresponding bus reference voltage based on the historical first bus voltage of the switching power supply, and obtains the corresponding current adjustment value based on the deviation between the second bus voltage and the bus reference voltage. This enables direct monitoring of the bus voltage, avoiding the lag of the previous method of indirectly adjusting the bus voltage by feedback from the voltage output of the inverter circuit. Furthermore, after determining the voltage state of the second bus voltage, the technical solution of this invention directly adjusts the current axis corresponding to the voltage state based on the current adjustment value, further improving the response speed of the current loop. This ensures that the bus voltage obtained after the actual current of the current axis is transformed is stable, reducing the occurrence of uncontrolled shutdown of the air conditioner due to the motor control loop not responding in time.

[0074] Optionally, refer to Figure 1 , Figure 2 , Figure 11 and Figure 12 The step of obtaining the current adjustment value based on the bus reference voltage, the second bus voltage, and the pre-stored feedforward coefficient specifically includes:

[0075] S210. The current voltage deviation is obtained by subtracting the bus reference voltage from the second bus voltage.

[0076] S220. The product of the current voltage deviation and the feedforward coefficient is used as the current adjustment value.

[0077] In this embodiment, since the actual current of the current axis is positively correlated with its corresponding bus voltage after conversion, when the current second bus voltage drops, the bus voltage should be promptly raised to maintain stability. Therefore, the current voltage deviation obtained by subtracting the bus reference voltage from the second bus voltage is positive. After multiplying this deviation by the transfer function and the feedforward coefficient, the resulting current adjustment value is also positive. Thus, the actual current of the current axis will gradually increase during feedback processing. Conversely, when the current second bus voltage rises rapidly, the bus voltage should be promptly lowered to maintain stability. Therefore, the current voltage deviation obtained by subtracting the bus reference voltage from the second bus voltage is negative. After multiplying this deviation by the transfer function and the feedforward coefficient, the resulting current adjustment value is also negative. Thus, the actual current of the current axis will gradually decrease during feedback processing.

[0078] Reference Figures 1 to 3 In one embodiment, the plurality of current axes includes quadrature axes and direct axes. The step of acquiring the shaft voltage before each current axis is input to the motor, and acquiring the voltage state of the second bus voltage based on the second bus voltage and the shaft voltage; determining the target current axis to be adjusted from the plurality of current axes based on the voltage state specifically includes:

[0079] S310. Obtain the current quadrature-axis voltage and current direct-axis voltage of the motor, and determine the voltage utilization rate of the second bus voltage based on the second bus voltage, the current quadrature-axis voltage and the current direct-axis voltage;

[0080] S320. If the voltage utilization rate does not reach the preset utilization rate, it is determined that the second bus voltage is in an unsaturated state, and the quadrature axis is determined to be the target current axis to be adjusted.

[0081] S330. If the voltage utilization rate reaches the preset utilization rate, then the second bus voltage is determined to be in a saturated state, and the direct axis and quadrature axis are determined to be the target current axis to be adjusted.

[0082] It should be noted that the state of the bus voltage is related to the voltage utilization rate of the second bus voltage. The voltage utilization rate of the second bus voltage refers to the ratio of the maximum amplitude of the fundamental AC voltage that the inverter circuit can output to the bus voltage. In this embodiment, the maximum amplitude of the fundamental AC voltage that the inverter circuit can output is related to the quadrature-axis voltage and the direct-axis voltage. Both the quadrature-axis voltage and the direct-axis voltage can be obtained by converting the actual current of the corresponding axis.

[0083] When obtaining the quadrature-axis voltage and direct-axis voltage, the control chip calculates the current quadrature-axis voltage, current direct-axis voltage, and second bus voltage according to the voltage utilization rate formula to obtain the current voltage utilization rate of the DC bus. The main control chip 530 also stores preset utilization rates in its memory. These preset utilization rates are set by researchers according to different motor models. When the voltage utilization rate does not reach the preset utilization rate, it indicates that the current second bus voltage is in an unsaturated state. At this time, there is no current input to the direct axis of the motor, therefore the current axis to be adjusted is determined to be the quadrature-axis. When the voltage utilization rate reaches the preset utilization rate, it indicates that the current second bus voltage is in a saturated state. At this time, there is current input to the direct axis of the motor, therefore the current axis to be adjusted is determined to be the quadrature-axis.

[0084] Reference Figures 1 to 4 In one embodiment, determining the voltage utilization rate of the second bus voltage based on the second bus voltage, the current quadrature-axis voltage, and the current direct-axis voltage specifically includes:

[0085] S311. Perform a conversion process on the current quadrature-axis voltage and the current direct-axis voltage to obtain the current voltage value in the quadrature-direct-axis coordinate system;

[0086] S312. Determine the voltage utilization rate based on the relationship between the voltage utilization rate of the second bus voltage and the current voltage value and the second bus voltage in the perpendicular axis coordinate system.

[0087] The quadrature axis and direct axis are not the actual current axes of the motor, but rather a quadrature-direct axis coordinate system established on the motor rotor. This coordinate system rotates synchronously with the rotor. The direction of the rotor magnetic field is taken as the direct axis, and the direction perpendicular to the rotor magnetic field is taken as the quadrature axis. This decouples the AC voltage output by the inverter circuit from the quadrature axis and the direct axis, resulting in good control characteristics. Therefore, in this embodiment, by performing PARK transformation on the current quadrature axis voltage and the current direct axis voltage, the current voltage value in the quadrature-direct axis coordinate system can be obtained, which is the AC voltage output by the inverter circuit. The utilization rate is the ratio of the maximum amplitude of the fundamental AC voltage that the inverter circuit can output to the DC bus voltage, and the voltage utilization rate is determined accordingly.

[0088] Reference Figures 1 to 5 In one embodiment, the plurality of current axes include quadrature axes and direct axes, and the feedback adjustment of the current of the target current axis according to the current adjustment value specifically includes:

[0089] S410. When the target current axis is the quadrature axis, the current of the quadrature axis is adjusted according to the current adjustment value.

[0090] S420. When the target current axis is the quadrature axis and the direct axis, the current of the quadrature axis and the direct axis is adjusted according to the current adjustment value.

[0091] In this embodiment, when the maximum amplitude of the fundamental AC voltage occupies no more than a preset proportion of the bus voltage, it indicates that the second bus voltage is in an unsaturated state. At this time, there is no current input to the direct shaft of the motor. Therefore, if the fluctuation of the second bus voltage exceeds the preset fluctuation range, only the current loop of the quadrature shaft needs to be compensated. When the maximum amplitude of the fundamental AC voltage occupies more than a preset proportion of the bus voltage, it indicates that the second bus voltage is in a saturated state. At this time, there is current input to the direct shaft of the motor. Therefore, if the fluctuation of the second bus voltage exceeds the preset fluctuation range, both the current loops of the direct shaft and the quadrature shaft need to be compensated.

[0092] Reference Figure 1 , Figure 6 , Figure 11 and Figure 12 In one embodiment, when the target current axis is the quadrature axis, the feedback adjustment of the current on the quadrature axis according to the current adjustment value specifically includes:

[0093] S411. Obtain the first cross-axis actual current of the cross-axis;

[0094] S412. Obtain the actual speed of the motor, and obtain the preset given speed and the deviation value of the actual speed;

[0095] S413. Adjust the preset first cross-axis given current of the cross-axis according to the deviation value, the current adjustment value and the actual current of the first cross-axis, wherein the first cross-axis given current is positively correlated with the current adjustment value;

[0096] S414. The actual current of the first quadrature axis is adjusted by feedback according to the adjusted first quadrature axis given current.

[0097] In this embodiment, the motor feedback control loop 520 obtains the actual rotational speed fed back by the motor and a preset given rotational speed to obtain the rotational speed deviation between the given rotational speed and the actual rotational speed. Simultaneously, the deviation adjustment value and the rotational speed deviation are input into the quadrature-axis feedback loop of the feedback control loop 520. This causes the preset first quadrature-axis given current to be adjusted based on the input rotational speed deviation and the deviation adjustment value. The adjusted value is then set to the current value of the first quadrature-axis given current. Based on the adjusted first quadrature-axis given current, the actual current is controlled by feedback, causing the first quadrature-axis actual current to gradually approach the first quadrature-axis given current. This change in the first quadrature-axis actual current alters the bus voltage corresponding to the first quadrature-axis actual current.

[0098] Reference Figure 1 , Figure 7 , Figure 11 and Figure 12 In one embodiment, when the target current axis is both the quadrature axis and the direct axis, the feedback adjustment of the current on the quadrature axis and the direct axis according to the current adjustment value specifically includes:

[0099] S421. Obtain the second cross-axis actual current of the cross-axis and the direct axis actual current of the direct axis;

[0100] S422. Adjust the preset direct-axis given current according to the current adjustment value, and adjust the actual direct-axis current according to the adjusted direct-axis given current, wherein the direct-axis given current is positively correlated with the current adjustment value.

[0101] S423. Obtain the actual speed of the motor, and adjust the preset second quadrature axis given current according to the deviation between the preset given speed and the actual speed, and the adjusted direct axis actual current.

[0102] S424. Adjust the actual current of the second quadrature axis according to the adjusted given current of the second quadrature axis.

[0103] In this embodiment, the deviation value is adjusted to the direct-axis feedback loop of the input feedback control loop 520, so that the preset direct-axis given current is adjusted according to the input deviation value, and the adjusted value is adjusted to the current value of the direct-axis given current. Thus, the actual direct-axis current is controlled according to the adjusted direct-axis given current, so that the actual direct-axis current gradually approaches the direct-axis given current, thereby changing the actual direct-axis current.

[0104] It should be noted that the quadrature-axis current and direct-axis current of the motor are obtained by decoupling the total current of the motor, that is... Therefore, the target value of the total current can be adjusted based on the speed deviation between the given speed and the actual speed of the motor. The adjusted target value of the total current and the actual direct-axis current are input together into the quadrature-axis feedback loop of the feedback control loop 520 to obtain an adjusted second quadrature-axis given current. The actual current is then fed back and controlled based on the second quadrature-axis given current, so that the second quadrature-axis actual current gradually approaches the second quadrature-axis given current, thus changing the second quadrature-axis actual current. The direct-axis given current is related to the total input current and the second quadrature-axis given current.

[0105] Therefore, when the current second bus voltage drops, the current adjustment value is positive, increasing the second quadrature axis given current, thus increasing the calculated second quadrature axis given current. Consequently, the actual direct axis current and the actual second quadrature axis current after feedback adjustment, after transformation, also increase the corresponding bus voltage. Conversely, when the current second bus voltage rises rapidly, the current adjustment value is negative, decreasing the second quadrature axis given current, thus decreasing the calculated second quadrature axis given current. Consequently, the actual direct axis current and the actual second quadrature axis current after feedback adjustment, after transformation, also decrease the corresponding bus voltage.

[0106] Reference Figure 8 The present invention also proposes a current control circuit for use in a switching power supply for controlling a motor, wherein the switching power supply has multiple current axes, including:

[0107] An error acquisition module 510, the input terminal of which is electrically connected to the motor, is used to obtain a stable bus reference voltage based on the historical first bus voltage of the switching power supply; and to obtain the current second bus voltage and obtain a current adjustment value based on the bus reference voltage, the second bus voltage and a pre-stored feedforward coefficient.

[0108] Feedback control loop 520, the output of which is connected to the controlled end of the motor;

[0109] The main control chip 530, electrically connected to the motor, is used to acquire the shaft voltage before each current axis inputs to the motor, and to acquire the voltage state of the second bus voltage based on the second bus voltage and the shaft voltage; and,

[0110] Based on the voltage state, the target current axis to be adjusted is determined from multiple current axes, and the feedback control loop 520 is controlled to adjust the current of the target current axis according to the current adjustment value, so as to stabilize the bus voltage obtained after the current of the target current axis has been transformed.

[0111] In this embodiment, the error acquisition module 510 may include a feedback circuit with filtering or analog-to-digital conversion functions.

[0112] During motor operation, the error acquisition module 510 collects the historical first bus voltage and the current first bus voltage of the switching power supply in real time, processes the first bus voltage to obtain a stable bus reference voltage, and then processes the deviation between the second bus voltage and the bus reference voltage according to its transfer function to obtain the corresponding current regulation value, and outputs it to the feedback control loop 520.

[0113] The main control chip 530 determines the state of the second bus voltage based on the second bus voltage and the voltage of each current axis output by the error acquisition module 510 or other voltage acquisition modules. When the line voltage occupies less than a preset proportion of the second bus voltage, it indicates that the voltage is in an unsaturated state. At this time, there is no current input to the direct axis of the motor. Therefore, if the fluctuation of the second bus voltage exceeds the preset fluctuation range, the main control chip 530 controls the error acquisition module 510 to input the current adjustment value to the input terminal of the quadrature axis current loop of the feedback control loop 520. When the line voltage occupies more than a preset proportion of the second bus voltage, it indicates that the voltage is in a saturated state. At this time, there is current input to the direct axis of the motor. Therefore, if the fluctuation of the second bus voltage exceeds the preset fluctuation range, the main control chip 530 can directly control the error acquisition module 510 to input only the current adjustment value to the input terminal of the direct axis current loop of the feedback control loop 520, and then achieve simultaneous compensation of the current loops of the direct axis and quadrature axis through the current conversion of the feedback control loop 520.

[0114] This allows the feedback loop to adjust the given current of the current axis according to the input current adjustment value, and then to control the actual current by feedback according to the given current, so that the actual current gradually approaches the given current, thereby changing the actual current of the current axis and thus changing the bus voltage corresponding to the actual current. The given current is the target current of the current axis.

[0115] Reference Figure 9 In one embodiment, the error acquisition module 510 includes:

[0116] The filter module 511 is electrically connected to the motor and is used to collect the historical first bus voltage and the current first bus voltage of the switching power supply, and to filter the first bus voltage to obtain a stable bus reference voltage.

[0117] The bus voltage feedforward module 512 is electrically connected to the output terminals of the motor and the filter module 511, respectively, and is used to collect the current second bus voltage of the switching power supply, and obtain the current regulation value according to the bus reference voltage, the second bus voltage and the feedforward coefficient.

[0118] In this embodiment, the filtering module 511 may include a filtering circuit or an analog-to-digital conversion circuit, etc.

[0119] During the operation of the switching power supply, the filtering module 511 collects the historical first bus voltage of the switching power supply in real time, filters the first bus voltage to obtain a stable bus reference voltage, and outputs it to the bus voltage feedforward module 512. This allows the bus voltage feedforward module 512 to process the deviation between the current second bus voltage and the bus reference voltage of the switching power supply according to its transfer function, obtain the corresponding current regulation value, and output it to the feedback control loop 520.

[0120] The present invention also proposes an air conditioner, which includes a motor and the aforementioned current control circuit. The specific structure of the current control circuit is as described in the above embodiments. Since the air conditioner adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated here.

[0121] The present invention also proposes a storage medium comprising the above-described three-phase power supply current control method. The specific structure of the three-phase power supply current control method is described in the above embodiments. Since this storage medium adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated here.

[0122] The above description is merely an optional embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A current control method of a three-phase power supply, applied to a switching power supply for controlling a motor, the switching power supply being provided with a plurality of current axes, characterized by, The method comprises: obtaining a stable bus reference voltage according to a first bus voltage of the switching power supply history; obtaining a current regulation value according to the bus reference voltage, a second bus voltage and a pre-stored feedforward coefficient; obtaining an axis voltage of each current axis before the axis voltage is input into the motor, and obtaining a voltage state of the second bus voltage according to the second bus voltage and the axis voltage; determining a target current axis to be regulated from a plurality of current axes according to the voltage state, and performing feedback regulation on a current of the target current axis according to the current regulation value, so as to stabilize a bus voltage obtained after a conversion process of the current of the target current axis. The method further comprises: determining the current regulation value by subtracting the second bus voltage from the bus reference voltage to obtain a current voltage deviation, and taking a product of the current voltage deviation and the feedforward coefficient as the current regulation value.

2. The current control method of a three-phase power supply according to claim 1, characterized by, The method further comprises: obtaining a current quadrature axis voltage and a current direct axis voltage of the motor, and determining a voltage utilization rate of the second bus voltage according to the second bus voltage, the current quadrature axis voltage and the current direct axis voltage; if the voltage utilization rate does not reach a preset utilization rate, it is determined that the second bus voltage is in an unsaturated state, and the quadrature axis is determined as the target current axis to be regulated; if the voltage utilization rate reaches the preset utilization rate, it is determined that the second bus voltage is in a saturated state, and the quadrature axis and the direct axis are determined as the target current axes to be regulated. The method further comprises:

3. The current control method of a three-phase power supply according to claim 1, wherein, performing conversion processing on the current quadrature axis voltage and the current direct axis voltage to obtain a current voltage value in a quadrature-direct axis coordinate system; determining the voltage utilization rate according to a relationship among the voltage utilization rate, the current voltage value in the quadrature-direct axis coordinate system and the second bus voltage. The method further comprises:

4. The current control method of a three-phase power supply according to claim 3, wherein, when the target current axis is the quadrature axis, performing feedback regulation on the current of the quadrature axis according to the current regulation value; when the target current axis is the quadrature axis and the direct axis, performing feedback regulation on the currents of the quadrature axis and the direct axis according to the current regulation value. The method further comprises: obtaining a first quadrature axis actual current of the quadrature axis; obtaining an actual rotating speed of the motor, and obtaining a preset given rotating speed and a deviation value of the actual rotating speed; Adjust a preset first quadrature-axis given current according to the deviation value, the current regulation value and the first quadrature-axis actual current, wherein the first quadrature-axis given current is positively correlated with the current regulation value; Feedback regulate the first quadrature-axis actual current according to the adjusted first quadrature-axis given current.

5. The current control method of a three-phase power supply according to claim 3, wherein, The feedback regulating the currents of the quadrature axis and the direct axis according to the current regulation value when the target current axis is the quadrature axis and the direct axis specifically includes: Obtain a second quadrature-axis actual current of the quadrature axis and a direct-axis actual current of the direct axis; Adjust a preset direct-axis given current according to the current regulation value, and feedback regulate the direct-axis actual current according to the adjusted direct-axis given current, wherein the direct-axis given current is positively correlated with the current regulation value; Obtain an actual rotating speed of the motor, and adjust a preset second quadrature-axis given current according to a deviation value between a preset given rotating speed and the actual rotating speed and the adjusted direct-axis actual current; Feedback regulate the second quadrature-axis actual current according to the adjusted second quadrature-axis given current.

6. A current control circuit applied to a switching power supply for controlling a motor, said switching power supply being provided with a plurality of current axes, characterized by Comprise: An error obtaining module, an input end of the error obtaining module is electrically connected with a motor, to obtain a stable bus reference voltage according to a first bus voltage of a history of the switching power supply; and obtain a current regulation value according to the bus reference voltage, a second bus voltage and a pre-stored feedforward coefficient; wherein the current regulation value is obtained according to the bus reference voltage, the second bus voltage and the pre-stored feedforward coefficient specifically includes: obtaining a current voltage deviation by subtracting the second bus voltage from the bus reference voltage; taking a product of the current voltage deviation and the feedforward coefficient as the current regulation value; A feedback control loop, an output end of the feedback control loop is connected with a controlled end of the motor; A main control chip, the main control chip is electrically connected with the motor, to obtain an axis voltage before each current axis is input into the motor, and obtain a voltage state of the second bus voltage according to the second bus voltage and the axis voltage; and Determine a target current axis to be regulated from a plurality of current axes according to the voltage state, and control the feedback control loop to feedback regulate a current of the target current axis according to the current regulation value, to stabilize a bus voltage obtained by a transformation processing of the current of the target current axis; The multiple current axes include a quadrature axis and a direct axis, the axis voltage before each current axis inputting the motor is obtained, and the voltage state of the second bus voltage is obtained according to the second bus voltage and the axis voltage; the target current axis to be adjusted is determined from the multiple current axes according to the voltage state, including: obtaining the current quadrature axis voltage and the current direct axis voltage of the motor, and determining the voltage utilization rate of the second bus voltage according to the second bus voltage, the current quadrature axis voltage and the current direct axis voltage; if the voltage utilization rate does not reach a preset utilization rate, it is determined that the second bus voltage is in an unsaturated state, and the quadrature axis is determined as the target current axis to be adjusted; if the voltage utilization rate reaches the preset utilization rate, it is determined that the second bus voltage is in a saturated state, and the direct axis and the quadrature axis are determined as the target current axes to be adjusted.

7. An air conditioner characterized by comprising: The air conditioner comprises a motor and the current control circuit according to claim 6.

8. A storage medium, characterized by The storage medium comprises the current control method of the three-phase power supply according to any one of claims 1-5.

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