阅读说明：本技术 永磁电机的弱磁切换方法及装置、空调器 (Weak-magnetic switching method and device for permanent magnet motor and air conditioner ) 是由 张嘉鑫 张高廷 邝超洪 周琛 姜学想 刘武斌 于 2020-11-20 设计创作，主要内容包括：本申请实施例涉及一种永磁电机的弱磁切换方法及装置、空调器,永磁电机的弱磁切换方法包括如下步骤：获取永磁电机的运行参数；根据所述运行参数,判断是否满足第一设定条件,所述第一设定条件用于指示所述永磁电机进入弱磁控制模式；如果是,则维持当前直流母线电压的利用率,将所述永磁电机的控制模式由双电流调节器控制模式切换至单电流调节器控制模式；切换完成后,通过单电流调节器控制模式,调节所述直流母线电压的利用率。本申请实施例的永磁电机的弱磁切换方法可以使永磁电机在进入或退出弱磁控制模式时切换前后的电机工作点相对稳定,实现平稳切换。(The embodiment of the application relates to a weak magnetic switching method and device of a permanent magnet motor and an air conditioner, wherein the weak magnetic switching method of the permanent magnet motor comprises the following steps: acquiring the operating parameters of the permanent magnet motor; judging whether a first set condition is met or not according to the operation parameters, wherein the first set condition is used for indicating the permanent magnet motor to enter a weak magnetic control mode; if so, maintaining the utilization rate of the current direct current bus voltage, and switching the control mode of the permanent magnet motor from a double-current regulator control mode to a single-current regulator control mode; and after the switching is finished, the utilization rate of the voltage of the direct current bus is adjusted through a single current regulator control mode. The weak magnetic switching method of the permanent magnet motor can enable the working points of the permanent magnet motor before and after switching to be relatively stable when the permanent magnet motor enters or exits a weak magnetic control mode, and stable switching is achieved.)

1. A weak magnetic switching method of a permanent magnet motor is characterized by comprising the following steps:

acquiring the operating parameters of the permanent magnet motor;

judging whether a first set condition is met or not according to the operation parameters, wherein the first set condition is used for indicating the permanent magnet motor to enter a weak magnetic control mode;

if so, maintaining the utilization rate of the current direct current bus voltage, and switching the control mode of the permanent magnet motor from a double-current regulator control mode to a single-current regulator control mode;

and after the switching is finished, the utilization rate of the voltage of the direct current bus is adjusted through a single current regulator control mode.

2. The method for switching field weakening of a permanent magnet motor according to claim 1, further comprising, after switching is completed:

judging whether a second set condition is met or not according to the operating parameters, wherein the second set condition is used for indicating the permanent magnet motor to exit from a weak magnetic control mode;

if so, maintaining the utilization rate of the current direct current bus voltage, and switching the control mode of the permanent magnet motor from the single current regulator control mode to the double current regulator control mode;

and after the switching is finished, regulating the utilization rate of the voltage of the direct current bus through a double-current regulator control mode.

3. The method of switching field weakening of a permanent magnet motor according to claim 2, wherein said step of switching said control mode of said permanent magnet motor from a dual current regulator control mode to a single current regulator control mode further comprises:

acquiring an MTPA angle of the permanent magnet motor in operation, and judging whether the MTPA angle is zero or not;

if yes, setting the MTPA angle as a first compensation value.

4. The method of switching field weakening of a permanent magnet motor according to claim 3, wherein said step of switching said control mode of said permanent magnet motor from a single current regulator control mode to a dual current regulator control mode further comprises:

setting the MTPA angle to a second compensation value, wherein the second compensation value is larger than the first compensation value.

5. The method for switching field weakening of a permanent magnet motor according to claim 1, wherein said maintaining the utilization rate of the current dc bus voltage comprises:

by limitingThe value of (a) maintains the utilization rate of the current DC bus voltage unchanged, wherein u_dFor d-axis given voltage, u_qA voltage is given to the q-axis.

6. The method of switching field weakening of a permanent magnet motor according to claim 5, wherein said adjusting said utilization of said dc bus voltage by a single current regulator control mode comprises:

correcting in a fixed step length modeGiven values of (a).

7. The field weakening switching method of a permanent magnet motor according to claim 1, wherein said first setting condition includes:

wherein u is_dFor d-axis given voltage, u_qGiven a voltage, u, for the q-axis_sThe highest voltage available for the current dc bus.

8. The field weakening switching method of a permanent magnet motor according to claim 1, wherein said second setting condition includes:

i_d＞k*i_qwherein i is_dIs d-axis current, i_qIs the q-axis current and k is the proportionality coefficient.

9. A weak magnetic switching device of a permanent magnet motor is characterized by comprising:

the operation parameter acquisition module is used for acquiring the operation parameters of the permanent magnet motor;

the first judgment module is used for judging whether a first set condition is met or not according to the operation parameters, and the first set condition is used for indicating the permanent magnet motor to enter a weak magnetic control mode;

the first switching module is used for maintaining the utilization rate of the current direct current bus voltage and switching the control mode of the permanent magnet motor from a double-current-regulator control mode to a single-current-regulator control mode if the current direct current bus voltage is the same as the direct current bus voltage;

and the first adjusting module is used for adjusting the utilization rate of the voltage of the direct current bus through a single current regulator control mode after switching is finished.

10. An air conditioner, comprising:

at least one memory and at least one processor;

the memory for storing one or more programs;

when executed by the at least one processor, cause the at least one processor to implement a method of field weakening switching of a permanent magnet machine according to any of claims 1-8.

Technical Field

The invention relates to the technical field of permanent magnet motors, in particular to a weak magnetic switching method and device of a permanent magnet motor and an air conditioner.

Background

The permanent magnet motor has the advantages of high power density, high efficiency, simple and reliable mechanical structure and the like, and is widely applied to the industrial field. For example, in the field of air conditioners, the use of permanent magnet motors to drive refrigeration compressors has become the mainstream choice for compressor manufacturers. Unlike induction motors, the rotor flux linkage of a permanent magnet motor is generated by permanent magnets, and the rotor flux linkage is constant in size and cannot be adjusted by controlling the rotor current. Therefore, the speed regulation capability of the permanent magnet motor is limited, and the weak magnetic control technology has important significance on the stability of the permanent magnet motor in high-frequency operation.

The existing weak magnetic control method mainly comprises a formula method, a table look-up method, a negative id compensation method, lead angle weak magnetic control and a weak magnetic control method based on a single current regulator. Different from the traditional double-current control method, the single-current flux weakening control method utilizes the coupling relation of id-iq (id is d-axis current, and iq is q-axis current), and synchronous control of flux weakening depth and electromagnetic torque can be realized by only controlling single-axis current during flux weakening control of the motor. The problem of out-of-control saturation of the current regulator in deep flux weakening in the traditional method is effectively solved, and the stability and the control capability of the motor in high frequency are improved.

Fig. 1 is a control schematic diagram of a single current regulator based flux weakening control method, which is different from other double current loop based flux weakening control methods. The method utilizes the coupling relation of the quadrature-direct axis current, and controls the flux weakening depth and the torque by controlling only the d-axis current when the system enters a flux weakening control mode, so that the method has better regulating capacity and quick dynamic response during flux weakening.

However, the conventional switching method applied to the single and double current regulators is difficult to suppress current jitter during switching in practical application, and is easy to generate torque oscillation during switching.

Disclosure of Invention

The first purpose of the present invention is to provide a method for switching the field weakening of a permanent magnet motor, which can make the motor operating points before and after switching the permanent magnet motor when entering or exiting the field weakening control mode relatively stable, and realize stable switching.

The purpose of the invention is realized by the following technical scheme:

a weak magnetic switching method of a permanent magnet motor comprises the following steps:

acquiring the operating parameters of the permanent magnet motor;

judging whether a first set condition is met or not according to the operation parameters, wherein the first set condition is used for indicating the permanent magnet motor to enter a weak magnetic control mode;

if so, maintaining the utilization rate of the current direct current bus voltage, and switching the control mode of the permanent magnet motor from a double-current regulator control mode to a single-current regulator control mode;

and after the switching is finished, the utilization rate of the voltage of the direct current bus is adjusted through a single current regulator control mode.

Further, after the switching is completed, the method further comprises the following steps:

judging whether a second set condition is met or not according to the operating parameters, wherein the second set condition is used for indicating the permanent magnet motor to exit from a weak magnetic control mode;

if so, maintaining the utilization rate of the current direct current bus voltage, and switching the control mode of the permanent magnet motor from the single current regulator control mode to the double current regulator control mode;

and after the switching is finished, regulating the utilization rate of the voltage of the direct current bus through a double-current regulator control mode.

Further, before the control mode of the permanent magnet motor is switched from the dual current regulator control mode to the single current regulator control mode, the method further includes:

acquiring an MTPA angle of the permanent magnet motor in operation, and judging whether the MTPA angle is zero or not;

if yes, setting the MTPA angle as a first compensation value.

Further, before the control mode of the permanent magnet motor is switched from the single current regulator control mode to the dual current regulator control mode, the method further includes:

setting the MTPA angle to a second compensation value, wherein the second compensation value is larger than the first compensation value.

Further, the maintaining the utilization rate of the current dc bus voltage includes:

by limitingThe value of (a) maintains the utilization rate of the current DC bus voltage unchanged, wherein u_dFor d-axis given voltage, u_qA voltage is given to the q-axis.

Further, the adjusting the utilization rate of the dc bus voltage through the single current regulator control mode includes:

correcting in a fixed step length modeGiven values of (a).

Further, the first setting condition includes:

wherein u is_dFor d-axis given voltage, u_qGiven a voltage, u, for the q-axis_sThe highest voltage available for the current dc bus.

Further, the second setting condition includes:

i_d＞k*i_qwherein i is_dIs d-axis current, i_qIs the q-axis current and k is the proportionality coefficient.

The second purpose of the present invention is to avoid the disadvantages in the prior art and provide a weak magnetic switching device for a permanent magnet motor, which can make the motor operating points before and after switching of the permanent magnet motor when entering a weak magnetic control mode relatively stable, and realize stable switching.

The purpose of the invention is realized by the following technical scheme:

a weak magnetic switching device of a permanent magnet motor comprises:

the operation parameter acquisition module is used for acquiring the operation parameters of the permanent magnet motor;

the first judgment module is used for judging whether a first set condition is met or not according to the operation parameters, and the first set condition is used for indicating the permanent magnet motor to enter a weak magnetic control mode;

the first switching module is used for maintaining the utilization rate of the current direct current bus voltage and switching the control mode of the permanent magnet motor from a double-current-regulator control mode to a single-current-regulator control mode if the current direct current bus voltage is the same as the direct current bus voltage;

and the first adjusting module is used for adjusting the utilization rate of the voltage of the direct current bus through a single current regulator control mode after switching is finished.

The third objective of the present invention is to provide an air conditioner to avoid the disadvantages of the prior art, so that the working points of the permanent magnet motor in the compressor of the air conditioner before and after switching are relatively stable when entering the weak magnetic control mode, and the stable switching is realized.

The purpose of the invention is realized by the following technical scheme:

an air conditioner comprising:

at least one memory and at least one processor;

the memory for storing one or more programs;

when executed by the at least one processor, the one or more programs cause the at least one processor to carry out the steps of the method of field weakening switching of a permanent magnet machine according to the first object of the claims.

The weak magnetic switching method of the permanent magnet motor in the embodiment of the application has the following technical effects:

the working point of the motor is controlled by adjusting the maximum utilization rate of the voltage of the direct current bus, so that the d-axis current and the q-axis current can be kept stable before and after switching, torque oscillation is inhibited, the working point of the motor is relatively stable before and after switching, and stable switching in a weak magnetic control mode is realized;

the control angle of the weak magnetic cut-in and cut-out adopts a setting mode with a certain interval, so that the repeated jumping of a program between the cut-in and cut-out can be effectively prevented when the motor runs at the critical frequency;

the algorithm is easy to realize, does not occupy the internal storage space of the controller too much, is insensitive to motor parameters, is stable and reliable in switching, and has better robustness.

Drawings

The invention is further illustrated by means of the attached drawings, but the embodiments in the drawings do not constitute any limitation to the invention, and for a person skilled in the art, other drawings can be derived on the basis of the following drawings without inventive effort.

FIG. 1 is a control schematic diagram of a single current regulator based flux weakening control method;

FIG. 2 is a schematic diagram of a permanent magnet motor control based on single and double current loops;

fig. 3 is a schematic flow chart of a flux weakening switching method of a permanent magnet motor in an example of the embodiment of the present application;

fig. 4 is a schematic flow chart of a flux weakening switching method of a permanent magnet motor in an example of the embodiment of the present application;

fig. 5 is a schematic flow chart of a flux weakening switching method of a permanent magnet motor in an example of the embodiment of the present application;

fig. 6 is a schematic structural diagram of a field weakening switching device of a permanent magnet motor in an example of the embodiment of the present application;

fig. 7 is a schematic structural diagram of an air conditioner according to an example of the embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the examples of the present invention and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise, and "a plurality" typically includes at least two.

The words "if", as used herein, may be interpreted as "at … …" or "at … …" or "in response to a determination" or "in response to a detection", depending on the context. Similarly, the phrases "if determined" or "if detected (a stated condition or event)" may be interpreted as "when determined" or "in response to a determination" or "when detected (a stated condition or event)" or "in response to a detection (a stated condition or event)", depending on the context. The invention is further described with reference to the following examples.

When the motor runs at low speed, the current coupling relation is weak, the control cannot be carried out through a single current regulator, and a double current regulator mode is still needed. As shown in fig. 2, fig. 2 is a control schematic diagram of a control method based on a dual current regulator, and the difference between the two control methods is that when the motor enters or exits the field weakening control, the low-high speed control algorithm is switched to generate torque oscillation. The oscillation problem generated by the switching can lead the motor to vibrate strongly and generate abnormal sound, and lead the motor to be out of control to trigger protection and stop.

The conventional switching method for entering single-current flux weakening generally adopts a method of comparing a given voltage with the maximum available voltage of a direct-current bus, namelyIn the formula u_dFor d-axis given voltage, u_qGiven a voltage, u, for the q-axis_sThe highest voltage available for the current dc bus. Exit flux weakening can adopt i_d＞k*i_qJudging the conditions, wherein i_dIs d-axis current, i_qK is a proportionality coefficient for the q-axis current, which can be determined experimentally. However, this switching method is difficult to suppress the current jitter during the switching process, and the motor may repeatedly jump between entry and exit when operating at the critical frequency.

In fig. 2, when the permanent magnet motor is operated at a low speed and does not enter the field weakening state, the dual-current regulator control mode is still adopted. When the condition of entering the weak magnetic control mode is detected, the double current regulators fail, and the permanent magnet motor adopts the single current regulator control mode. The weak magnetic control switching module is used for judging and executing conditions of entering and exiting weak magnetic, and aiming at the technical problems, the embodiment of the application provides a weak magnetic switching method of a permanent magnet motor, which can realize smooth switching between a dual-current regulator control mode and a single-current regulator weak magnetic control.

As shown in fig. 3 and 4, in an exemplary embodiment, a method of switching field weakening of a permanent magnet motor includes the steps of:

s301: and acquiring the operating parameters of the permanent magnet motor.

In one embodiment, the permanent magnet motor is applied to a compressor of an air conditioner, and in other examples, the permanent magnet motor can also be applied to other equipment.

S302: and judging whether a first set condition is met or not according to the operation parameters, wherein the first set condition is used for indicating the permanent magnet motor to enter a weak magnetic control mode.

In some examples, the operating parameters include MTPA angle and d-axis set voltage u of the permanent magnet motor during operation_dQ-axis given voltage u_qThe highest voltage u available for the current DC bus_sAnd driving parameters such as motor phase current, wherein, taking the linear MTPA control as an example, and the MTPA control angle Is theta, then Id ═ Is sin (theta), Iq ═ Is cos (theta), Is the stator current of the permanent magnet motor, i Is_qIs the q-axis current of the permanent magnet motor.

In one example, the desired voltage is passedAnd the maximum voltage u available for the direct current bus of the current motor system_sThe comparison of (1) and (2) to judge whether the motor needs to be switched into the flux weakening operation, namely the first setting condition comprises:

s303: if so, maintaining the utilization rate of the current direct current bus voltage, and switching the control mode of the permanent magnet motor from a dual-current regulator control mode to a single-current regulator control mode.

In one example, the motor voltage limit ellipse and current limit circle mathematical expressions are shown in equations 1 and 2.

Wherein i_d、i_qIs d, q axis current, L_d、L_qIs d, q axis inductance,. psi_fIs a permanent magnet flux linkage u_sIs DC bus voltage, omega is motor angular velocity, rho is salient rate, I_limIs the motor current maximum.

The operating point range of the motor can be determined by the equations (1) and (2), as shown in fig. 5.

In FIG. 5, l is the MTPA trace, l and i_qThe included angle of the motor is MTPA control angle theta, T is a constant torque curve, and the voltage limit ellipse and the current limit circle of the motor are in i_qThe intersected area on the positive half shaft is the operable interval of the working point of the motor. Under the same parameter, due to the characteristics of the control algorithm, the DC bus voltage utilization rate of the dual-current regulator control mode and the single-current regulator control mode are different, and the single-current regulator weak magnetic control mode is slightly larger than the dual-current regulator control mode, namely an ellipse in the figureω₁Has a working range slightly larger than omega₂。

In FIG. 5, the voltage limit ellipse is determined by equation (1), which characterizes when u_s、ψ_fA cluster of ellipses omega varying with the angular speed omega of the motor when Ld, Lq and rho are not changed₁、ω₂Two of which are present. As can be seen from FIG. 5, when the other constant number is not changed, u_sAs ω increases, so too does ω. That is, u_sThe increase in angular speed of the motor may result in an increased operating range of the motor. Omega₁And ω₂Two ellipses in the representation chart represent the rotating speed range in which the permanent magnet motor can operate. The current limit circle is determined by formula (2), and represents the maximum stator current that can be achieved by the motor, and the intersection part of the voltage limit ellipse and the current limit circle is the operable operating point of the motor.

When the double current loops run to the voltage saturation, the working point of the motor is the intersection point and l of the voltage limit ellipse and the constant torque curve₁The intersection of (a). When switching into single current loop control, i_d-i_qThe relation no longer satisfies MTPA distribution relation, and the motor working point is the intersection point of the voltage limit ellipse and the constant torque curve, namely point A. And because the utilization rate of the direct current bus voltage is slightly higher during the single current loop weak magnetic control, the working point of the motor moves up to the boundary of the voltage limit ellipse along the constant torque curve T, namely the point B, so that the current jitter during switching is caused, and the motor can not smoothly and stably switch the working state. Therefore, the flux-weakening switching method of the permanent magnet motor according to the embodiment of the present application limits the utilization rate of the dc bus voltage after switching, so as to enable ω during switching₁And ω₂The operation areas are overlapped, the stability of the working points of the motor before and after switching is kept, and the voltage utilization rate of the direct current bus of the single current regulator control algorithm is recovered after the switching is finished.

In fig. 5, before switching, the operating point is point a, and in the embodiment of the present application, by limiting the utilization rate of the dc bus voltage, ω is calculated₂Is reduced to omega₁When the ranges of the points A and B are close or coincident, the switching is performed, namely the points A and B are close or coincident, after the switching is completed, the working point is the point B, and then the switching is releasedLimiting the voltage utilization of the DC bus to omega₂Increasing to its original range.

In one example of the above-mentioned method,the control mode of single current flux weakening can be limited for the voltage required by the motorThe required voltage of the permanent magnet motor is reduced to a certain extent by the given value, so that the utilization rate of the direct current bus voltage is limited, the required voltage and the power of the permanent magnet motor are unchanged at the switching moment, and the permanent magnet motor is stably switched into a single-current weak-magnetism control mode.

In one example, the maintaining the current utilization rate of the dc bus voltage includes:

by limitingThe utilization rate of the current direct current bus voltage is kept unchanged.

In the motor control of dual current regulators, MTPA or i is generally used_dA control form of 0. But in the presence of i_dWhen the control is switched into the weak magnetic control of the single current regulator as 0, the direct axis current i_dIt is necessary to quickly increase from 0 to a certain value and to keep it stable in order to maintain the torque required for the current belt load. Therefore, if the MTPA is set to 0 °, the rate of change of id is high during the adjustment process, and it is difficult to ensure the smooth and stable switching process.

Therefore, in an embodiment, before switching the control mode of the permanent magnet motor from the dual current regulator control mode to the single current regulator control mode, the method further includes:

acquiring an MTPA angle of the permanent magnet motor in operation, and judging whether the MTPA angle is zero or not;

if yes, setting the MTPA angle as a first compensation value to enable the motor to have a direct-axis component, and realizing smooth switching of the control mode.

S304: and after the switching is finished, the utilization rate of the voltage of the direct current bus is adjusted through a single current regulator control mode.

In a specific example, the step-by-step correction can be performed in a fixed step or variable step mannerTo a set given value in the single current regulator control mode.

In an example, after switching to enter the weak magnetic control mode, the embodiment of the present application further includes a step of exiting the weak magnetic control mode:

judging whether a second set condition is met or not according to the operating parameters, wherein the second set condition is used for indicating the permanent magnet motor to exit from a weak magnetic control mode;

if so, maintaining the utilization rate of the current direct current bus voltage, and switching the control mode of the permanent magnet motor from the single current regulator control mode to the double current regulator control mode;

and after the switching is finished, regulating the utilization rate of the voltage of the direct current bus through a double-current regulator control mode.

In one example, the second setting condition includes:

i_d＞k*i_qwherein i is_dIs d-axis current, i_qIs the q-axis current and k is the proportionality coefficient.

In one example, before switching the control mode of the permanent magnet motor from the single current regulator control mode to the dual current regulator control mode, the method further includes:

setting the MTPA angle to a second compensation value, wherein the second compensation value is larger than the first compensation value.

The control flow of switching out the weak magnetism is basically opposite to the flow of switching in, and the second compensation value needs to be larger than the first compensation value, so that the condition of withdrawing from and exiting from the weak magnetism control mode is expanded by a certain scale, and the weak magnetism control switching module is prevented from switching back and forth between the control modes of switching in and switching out the weak magnetism when the frequency of the motor runs at a critical value. And enter single current flux weakeningWhen controlling, i_d-i_qThe following relationship is satisfied:

according to i_d、i_qConversion of sampled value into its weak magnetic angleTo control the switching angle. After the switching is completed, the direct current bus voltage is corrected in a fixed step length mode so as to ensure the stability and reliability of the operation of the motor.

The weak magnetic switching method of the permanent magnet motor in the embodiment of the application has the following technical effects:

the working point of the motor is controlled by adjusting the maximum utilization rate of the voltage of the direct current bus, so that the d-axis current and the q-axis current can be kept stable before and after switching, torque oscillation is inhibited, the working point of the motor is relatively stable before and after switching, and stable switching in a weak magnetic control mode is realized;

the control angle of the weak magnetic cut-in and cut-out adopts a setting mode with a certain interval, so that the repeated jumping of a program between the cut-in and cut-out can be effectively prevented when the motor runs at the critical frequency;

the algorithm is easy to realize, does not occupy the internal storage space of the controller too much, is insensitive to motor parameters, is stable and reliable in switching, and has better robustness.

Corresponding to the weak magnetic switching method of the permanent magnet motor, the embodiment of the application also provides a weak magnetic switching device of the permanent magnet motor.

Fig. 6 is a schematic structural diagram of a weak magnetic switching device of a permanent magnet motor according to an example of the present application, and the weak magnetic switching device 600 of the permanent magnet motor includes:

an operation parameter obtaining module 601, configured to obtain an operation parameter of the permanent magnet motor;

a first determining module 602, configured to determine whether a first set condition is met according to the operating parameter, where the first set condition is used to instruct the permanent magnet motor to enter a weak magnetic control mode;

the first switching module 603 is configured to, if yes, maintain the utilization rate of the current dc bus voltage, and switch the control mode of the permanent magnet motor from the dual-current-regulator control mode to the single-current-regulator control mode;

and the first adjusting module 604 is configured to adjust the utilization rate of the dc bus voltage through a single current regulator control mode after the switching is completed.

In an exemplary embodiment, the weak magnetic switching apparatus 600 of the permanent magnet motor further includes:

the second judgment module is used for judging whether a second set condition is met or not according to the operation parameters after the switching is finished, wherein the second set condition is used for indicating the permanent magnet motor to exit from the weak magnetic control mode;

the second switching module is used for maintaining the utilization rate of the current direct current bus voltage and switching the control mode of the permanent magnet motor from the single current regulator control mode to the double current regulator control mode if the current direct current bus voltage is the utilization rate of the current direct current bus voltage;

and the second adjusting module is used for adjusting the utilization rate of the direct-current bus voltage through a double-current-regulator control mode after the switching is finished.

In an exemplary embodiment, the weak magnetic switching apparatus 600 of the permanent magnet motor further includes:

the third judgment module is used for acquiring an MTPA angle of the permanent magnet motor before the control mode of the permanent magnet motor is switched from the double-current regulator control mode to the single-current regulator control mode, and judging whether the MTPA angle is zero or not;

and the first compensation module is used for setting the MTPA angle as a first compensation value if the MTPA angle is the first compensation value.

In an exemplary embodiment, the weak magnetic switching apparatus 600 of the permanent magnet motor further includes:

and the second compensation module is used for setting the MTPA angle as a second compensation value before the control mode of the permanent magnet motor is switched from the single-current regulator control mode to the double-current regulator control mode, wherein the second compensation value is larger than the first compensation value.

In an exemplary embodiment, the first switching module 603 includes:

a first obtaining unit for obtaining the first voltage difference value Deltau through the following formula₁：

A first limiting unit for limitingOf the value of (a), maintaining said first voltage difference value Deltau₁The value of (a) is not changed.

In an exemplary embodiment, the first adjustment module 604 includes:

a correction unit for correcting in a fixed step mannerGiven values of (a).

In one exemplary embodiment, the first setting condition includes:

wherein u is_dFor d-axis given voltage, u_qGiven a voltage, u, for the q-axis_sThe highest voltage available for the current dc bus.

In one exemplary embodiment, the second setting condition includes:

i_d＞k*i_qwherein i is_dIs d-axis current, i_qIs the q-axis current and k is the proportionality coefficient.

Fig. 7 is a schematic structural diagram of an air conditioner according to an embodiment of the present application, where the air conditioner 70 includes: at least one memory 71 and at least one processor 72, said memory 71 for storing one or more programs; for storing program instructions; the processor 72 is configured to invoke the program instructions stored in the memory, and when the one or more programs are executed by the at least one processor, the at least one processor is configured to implement the field weakening switching method of the permanent magnet motor according to any one of the embodiments of the present application.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the protection scope of the present invention, although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.