A deep field weakening method for permanent magnet synchronous motor based on voltage self-adaption

Abstract

The application discloses a deep field-weakening method of a permanent magnet synchronous motor based on voltage self-adaption, which divides the operation of the permanent magnet synchronous motor into a non-field-weakening stage, a conventional field-weakening stage and a deep field-weakening stage by the field-weakening method, so that the processor can judge the field-weakening stage of the current operation condition of the permanent magnet synchronous motor according to the voltage under the current operation state of the permanent magnet synchronous motor, and can perform real-time adjustment and feedback on the permanent magnet synchronous motor according to the judgment result, so that the direct-axis current instruction and the quadrature-axis current instruction can be effectively adjusted in time through the self-adaption of the direct-axis voltage and the quadrature-axis voltage, the output power of the permanent magnet synchronous motor in the deep field-weakening area is improved, the stability of the operation of the permanent magnet synchronous motor is ensured, the permanent magnet synchronous motor can stably output higher torque under high speed, and the application has good applicability.

Description

Technical Field

[0001] This invention belongs to the field of motor technology, and in particular relates to a deep field weakening method for permanent magnet synchronous motors based on voltage adaptive technology. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) benefit from numerous advantages in design, manufacturing, and control, and are widely used in various industrial and daily life applications. Furthermore, my country's abundant rare earth resources make the market for PMSMs particularly large. PMSMs can be categorized into surface-mounted and internal types based on the difference in their direct and quadrature axis inductance. Internal PMSMs (IPMSMs) are more widely used because they offer a wider speed range under field weakening conditions. The concept of field weakening control in PMSMs originates from the field control of separately excited DC motors. When the terminal voltage of a separately excited DC motor reaches its limit, the excitation current should be reduced to maintain voltage balance and allow the motor to operate at a higher speed with constant power. However, since the excitation magnetic field of a PMSM is generated by permanent magnets, it is difficult to adjust once the motor is manufactured. This makes it difficult to achieve high-speed operation requiring field weakening, thus limiting its application in certain situations.

[0003] In practical applications, existing permanent magnet synchronous motors suffer from low maximum torque due to the presence of a deep field weakening zone during operation, resulting in poor operational stability and output power. To address this issue, we propose a voltage-adaptive deep field weakening method for permanent magnet synchronous motors. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention provides a voltage-adaptive deep field weakening method for permanent magnet synchronous motors, which avoids the problem that existing permanent magnet synchronous motors have low maximum torque in the deep field weakening zone during actual use, resulting in poor stability and output power.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a deep field weakening method for a permanent magnet synchronous motor based on voltage adaptation, comprising the following steps:

[0006] S1. Real-time acquisition of the motor's output voltage u during operation. out Direct-axis voltage u d and quadrature axis voltage u q .

[0007] S2. Obtain the maximum output voltage set by the motor driver, i.e., the field weakening voltage point u. ref .

[0008] S3. Obtain the set motor deep field weakening critical point, i.e., the cross-axis voltage switching point u between conventional field weakening and deep field weakening. qlim .

[0009] S4. The processor determines the current magnetic weakening stage based on the voltage under the current operating state, and divides it into non-magnetic weakening stage, normal magnetic weakening stage and deep magnetic weakening stage.

[0010] S5. If the field is not weakened, the direct and quadrature axis currents will not be adjusted in real time.

[0011] S6. If it is in the normal field weakening stage, then use the field weakening voltage point u ref and output voltage u out As the input and feedback of a conventional field weakening controller, the controller outputs a direct-axis current command with an adjustment amount Δi. d .

[0012] S7. If it is in the deep magnetic weakening stage, then take the deep magnetic weakening threshold point u as the reference. qlim and quadrature axis voltage u q As the input and feedback for the deep field weakening controller, the controller output is the quadrature-axis current command adjustment amount Δi. q .

[0013] S8. Set the original direct-axis current i dref and quadrature axis current given i qref The direct-axis magnetic weakening adjustment amount Δi is superimposed respectively. d and cross-axis weak magnetic adjustment amount Δi q As the final DC current given i dref_fwc and quadrature axis current given i qref_fwc It is fed into the current loop for control.

[0014] As a preferred embodiment of the present invention, in step S2, the magnetic weakening voltage point u ref Less than or equal to the maximum voltage output capability of the motor driver.

[0015] As a preferred embodiment of the present invention, in step S3, the switching point u between the conventional magnetic weakening and deep magnetic weakening cross-axis voltages is... qlim Less than or equal to zero.

[0016] As a preferred embodiment of the present invention, in step S3, the switching point u between the conventional magnetic weakening and deep magnetic weakening cross-axis voltages is... qlim These are either pre-set fixed values ​​or calculated values ​​based on the motor's operating conditions.

[0017] As a preferred embodiment of the present invention, in steps S6 and S7, the conventional field weakening controller and the deep field weakening controller are proportional-integral regulators.

[0018] In a preferred embodiment of the present invention, in step S6, the conventional field weakening controller continuously calculates at different stages and outputs Δi. d Less than or equal to zero.

[0019] In a preferred embodiment of the present invention, in step S7, the depth field weakening controller calculates only during the conventional field weakening and depth field weakening stages, and outputs Δi. q Less than or equal to zero.

[0020] Compared with the prior art, the beneficial effects that this invention can achieve are:

[0021] This invention divides the operation of a permanent magnet synchronous motor (PMSM) into three stages: non-field weakening, conventional field weakening, and deep field weakening. The processor determines the current field weakening stage based on the voltage of the PMSM during operation. After determining the field weakening stage, the processor adjusts and provides feedback in real time based on the determination result. This allows for timely and effective adaptive adjustment of the quadrature and direct axis current commands through the quadrature and direct axis voltages, improving the output power of the PMSM in the deep field weakening region and ensuring its operational stability. It enables the PMSM to stably output higher torque at high speeds and has good applicability. Attached Figure Description

[0022] Figure 1 This is a schematic diagram illustrating the calculation principle of step S6 of the present invention;

[0023] Figure 2 This is a schematic diagram illustrating the calculation principle of step S7 of the present invention;

[0024] Figure 3 This is a schematic diagram illustrating the determination of the magnetic field weakening stage in this invention. Detailed Implementation

[0025] To make the technical means, creative features, and achieved objectives and effects of this invention readily understandable, the invention is further described below with reference to specific embodiments. However, the following embodiments are merely preferred embodiments of this invention and not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments described herein without creative effort are all within the protection scope of this invention. Unless otherwise specified, the experimental methods in the following embodiments are conventional methods, and the materials and reagents used in the following embodiments are commercially available unless otherwise specified.

[0026] Example

[0027] like Figures 1-3 The method for deep field weakening of a permanent magnet synchronous motor based on voltage adaptation, as shown, includes the following steps:

[0028] S1. Real-time acquisition of the motor's output voltage u during operation. out Direct-axis voltage u d and quadrature axis voltage u q .

[0029] S2. Obtain the maximum output voltage set by the motor driver, i.e., the field weakening voltage point u. ref .

[0030] S3. Obtain the set motor deep field weakening critical point, i.e., the cross-axis voltage switching point u between conventional field weakening and deep field weakening. qlim .

[0031] S4. The processor determines the current magnetic weakening stage based on the voltage under the current operating state, and divides it into non-magnetic weakening stage, normal magnetic weakening stage and deep magnetic weakening stage.

[0032] S5. If the field is not weakened, the direct and quadrature axis currents will not be adjusted in real time.

[0033] S6. If it is in the normal field weakening stage, then use the field weakening voltage point u ref and output voltage u out As the input and feedback of a conventional field weakening controller, the controller outputs a direct-axis current command with an adjustment amount Δi. d .

[0034] S7. If it is in the deep magnetic weakening stage, then take the deep magnetic weakening threshold point u as the reference. qlim and quadrature axis voltage u q As the input and feedback for the deep field weakening controller, the controller output is the quadrature-axis current command adjustment amount Δi. q .

[0035] S8. Set the original direct-axis current i dref and quadrature axis current given i qref The direct-axis magnetic weakening adjustment amount Δi is superimposed respectively. d and cross-axis weak magnetic adjustment amount Δi q As the final DC current given i dref_fwc and quadrature axis current given i qref_fwc It is fed into the current loop for control.

[0036] Example 1

[0037] S1. Real-time acquisition of the motor's output voltage u during operation. out Direct-axis voltage u d and quadrature axis voltage u q .

[0038] S2. Obtain the maximum output voltage set by the motor driver, i.e., the field weakening voltage point u. ref .

[0039] S3. Obtain the set motor deep field weakening critical point, i.e., the cross-axis voltage switching point u between conventional field weakening and deep field weakening. qlim .

[0040] S4. Based on the voltage under the current operating state, the processor determines the current magnetic weakening stage and classifies it into three stages according to the following conditions: non-magnetic weakening stage, normal magnetic weakening stage, and deep magnetic weakening stage.

[0041] Condition ① ;

[0042] Condition ②, ;

[0043] Condition ③ ;

[0044] If condition ① is met, it is in the non-weakening magnetic field stage; if condition ② is met, it is in the conventional weakening magnetic field stage; if condition ③ is met, it is in the deep weakening magnetic field stage.

[0045] ① During the non-field weakening stage, no field weakening adjustment is performed because the voltage has not reached the output voltage limit of the motor driver.

[0046] ② During the conventional field weakening stage, the direct-axis flux linkage is still positive. The field weakening purpose is achieved by adjusting the direct-axis current command.

[0047] ③ Deep field weakening stage: In this stage, the direct-axis flux linkage is negative, and the field weakening purpose is achieved by adjusting the quadrature-axis current command.

[0048] S5. If the field is not weakened, the direct and quadrature axis currents will not be adjusted in real time.

[0049] S6. If it is in the normal field weakening stage, then use the field weakening voltage point u ref and output voltage u out As the input and feedback of a conventional field weakening controller, the controller outputs a direct-axis current command with an adjustment amount Δi. d .

[0050] S7. If it is in the deep magnetic weakening stage, then take the deep magnetic weakening threshold point u as the reference. qlim and quadrature axis voltage u q As the input and feedback for the deep field weakening controller, the controller output is the quadrature-axis current command adjustment amount Δi. q .

[0051] S8. Set the original direct-axis current i dref and quadrature axis current given i qref The direct-axis field weakening adjustment Δid and the quadrature-axis field weakening adjustment Δiq are respectively superimposed as the final DC current reference idref_fwc and quadrature-axis current reference iqref_fwc, and then fed into the current loop for control.

[0052] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A deep field weakening method for a permanent magnet synchronous motor based on voltage adaptation, characterized in that, Includes the following steps: S1, acquiring output voltage u of motor in real time when the motor is running out , direct-axis voltage u d , and quadrature-axis voltage u q ; S2, acquire the maximum output voltage set by the motor driver, i.e. the field weakening voltage point u ref ; S3. Obtain the set motor deep field weakening critical point, i.e., the cross-axis voltage switching point u between conventional field weakening and deep field weakening. qlim ; S4. The processor determines the current magnetic field weakening stage based on the voltage under the current operating state, and divides it into non-magnetic field weakening stage, conventional magnetic field weakening stage and deep magnetic field weakening stage. S5. If the field is not weakened, the direct and quadrature axis currents will not be adjusted in real time. S6. If it is in the normal field weakening stage, then use the field weakening voltage point u ref and output voltage u out As the input and feedback of a conventional field weakening controller, the controller outputs a direct-axis current command with an adjustment amount Δi. d ; S7. If it is in the deep magnetic weakening stage, then take the deep magnetic weakening threshold point u as the reference. qlim and quadrature axis voltage u q As the input and feedback for the deep field weakening controller, the controller output is the quadrature-axis current command adjustment amount Δi. q ; S8. Set the original direct-axis current i dref and quadrature axis current given i qref The direct-axis magnetic weakening adjustment amount Δi is superimposed respectively. d and cross-axis weak magnetic adjustment amount Δi q As the final DC current given i dref_fwc and quadrature axis current given i qref_fwc It is fed into the current loop for control.

2. The deep field weakening method for a permanent magnet synchronous motor based on voltage adaptation according to claim 1, characterized in that: In step S2, the magnetic weakening voltage point u ref Less than or equal to the maximum voltage output capability of the motor driver.

3. The deep field weakening method for a permanent magnet synchronous motor based on voltage adaptation according to claim 1, characterized in that: In step S3, the cross-axis voltage switching point u between conventional magnetic weakening and deep magnetic weakening is... qlim Less than or equal to zero.

4. The deep field weakening method for a permanent magnet synchronous motor based on voltage adaptation according to claim 1, characterized in that: In step S3, the cross-axis voltage switching point u between conventional magnetic weakening and deep magnetic weakening is... qlim These are either pre-set fixed values ​​or calculated values ​​based on the motor's operating conditions.

5. The deep field weakening method for a permanent magnet synchronous motor based on voltage adaptation according to claim 1, characterized in that: In steps S6 and S7, the conventional field weakening controller and the deep field weakening controller are proportional-integral regulators.

6. The deep field weakening method for a permanent magnet synchronous motor based on voltage adaptation according to claim 1, characterized in that: In step S6, the conventional field weakening controller continuously calculates at different stages and outputs Δi d Less than or equal to zero.

7. The deep field weakening method for a permanent magnet synchronous motor based on voltage adaptation according to claim 1, characterized in that: In step S7, the depth field weakening controller is calculated only during the conventional field weakening and deep field weakening phases, and the output Δi q Less than or equal to zero.

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