阅读说明：本技术 一种永磁同步电机无级深度弱磁方法及系统 (Stepless depth flux weakening method and system for permanent magnet synchronous motor ) 是由 刘灿 *非凡 𠚵非凡 于 2020-07-20 设计创作，主要内容包括：本发明公开了一种永磁同步电机无级深度弱磁方法及系统,克服现有技术的无法充分发挥永磁同步电机特性的问题,本发明拓展高速攻略,提高深度弱磁的稳定性,且减少动态调节中的扭矩损失,利用补偿电压查表后的电流进行电压前馈模块,随着转速的升高,系统稳定性升高,在高速弱磁时可以快速稳定动态响应,且扭矩损失很小,避免了扭矩的损失,充分发挥永磁同步电机的特性,确保电机稳定运行在深度弱磁区,动态响应快,鲁棒性强,简单易操作。(The invention discloses a stepless depth flux weakening method and a stepless depth flux weakening system for a permanent magnet synchronous motor, which solve the problem that the characteristics of the permanent magnet synchronous motor cannot be fully exerted in the prior art, expand high-speed strategy, improve the stability of the depth flux weakening, reduce the torque loss in dynamic adjustment, utilize the current after compensating voltage lookup to carry out a voltage feedforward module, and along with the increase of the rotating speed, the stability of the system is increased, the dynamic response can be quickly and stably realized during high-speed flux weakening, the torque loss is very small, the torque loss is avoided, the characteristics of the permanent magnet synchronous motor are fully exerted, the motor is ensured to stably run in a depth flux weakening area, the dynamic response is quick, the robustness is strong, and the operation is simple and easy.)

1. A stepless depth flux weakening method for a permanent magnet synchronous motor is characterized by comprising the following steps:

s1: the voltage closed-loop module is used for closed-loop regulating the required voltage compensation amount according to the required voltage utilization rate;

s2: the required voltage compensation quantity is input into a current lookup module to perform lookup to obtain a required current point;

s3: the required current point obtained by table lookup is output through the current regulator;

s4: calculating a voltage feedforward compensation quantity by a voltage feedforward unit at a required current point obtained by table lookup;

s5: the output of the current regulator and the voltage feedforward compensation quantity form the final wave-generating voltage.

2. The stepless depth flux weakening method for the permanent magnet synchronous motor according to claim 1, wherein the step S1 comprises the following steps:

s11: the voltage closed-loop module sets the current bus voltage U according to the required voltage utilization rate_dc；

S12: will U_d ^*And U_q ^*After the arithmetic square root is solved, the current bus voltage U is set_dcPerforming linear operation;

s13: performing PI operation on the linear operation result to obtain a voltage compensation quantity delta U_dc；

Wherein, U_d ^*And U_q ^*Is the output of the current regulator.

3. The stepless depth flux weakening method for the permanent magnet synchronous motor according to claim 1, wherein the step S2 comprises the following steps:

s21: weak magnetic current points are calibrated in advance and stored in a program of a current table look-up module;

s22: when the program is running, the current table look-up module looks up the table voltage U according to the compensated table_dcReal, from a lookup table of motor speed Spd and torque request Tor (i)_d，i_q)；

Wherein Tor represents a motor torque command.

4. The stepless depth flux weakening method for the permanent magnet synchronous motor according to claim 1, wherein the step S3 comprises the following steps:

s31: the current regulator selects a PI controller;

s32: the current regulator will look up the current (i)_d，i_q) As a reference input;

s33: the current regulator performs PI operation on the lookup table current and idf and iqf to regulate the output reference voltage (U)_d*，U_q*)；

Wherein idf and iqf are DQ axis currents fed back by the motor actually.

5. The stepless depth flux weakening method for the permanent magnet synchronous motor according to claim 1, wherein the step S4 comprises the following steps:

s41: determining a flux linkage parameter table;

s42: the voltage feedforward unit obtains the reference current (i) according to the table lookup_d，i_q) Calculating real-time flux linkage psi by combining with flux linkage parameter table calibrated in advance_dAnd psi_q；

S43: the feedforward voltage calculation unit calculates the feedforward voltage compensation U according to the current rotating speed Spd of the motor_dC and U_qC。

6. The stepless depth flux weakening method for the permanent magnet synchronous motor according to claim 5, wherein the S41 comprises the following steps:

s411: calibrating and taking points through a rack;

s412: making a program table by a fitting method or an insertion method;

s413: running the code in real time according to (i)_d，i_q) And finding out the current magnetic linkage.

7. The stepless depth flux weakening method for the permanent magnet synchronous motor according to claim 5, wherein the calculation method of S43 specifically comprises calculation through a PMSM motor voltage equation, wherein the PMSM motor voltage equation is as follows:

U_dC＝-Spd*2π/60*ψ_q

U_qC＝Spd*2π/60*ψ_d

wherein, U_dC and U_qC is feedforward voltage compensation quantity, Spd is current rotating speed of motor, psi_dAnd psi_qIs a real-time flux linkage.

8. The stepless depth flux weakening method for the permanent magnet synchronous motor as claimed in claim 1, wherein the specific calculation method of S5 is as follows: (U)_d*，U_qA and (U)_dC，U_qC) The sum of which constitutes the final wave voltage (U)_d，U_q)。

9. A stepless depth flux weakening system of a permanent magnet synchronous motor adopts the stepless depth flux weakening method of the permanent magnet synchronous motor according to any one of claims 1 to 8, and is characterized by comprising a voltage closed loop module, a current lookup table module, a voltage feedforward unit and a current regulator.

Technical Field

The invention relates to the technical field of electromagnetism, in particular to a stepless depth flux weakening method and a stepless depth flux weakening system for a permanent magnet synchronous motor, which can improve the existing flux weakening strategy, expand high-speed power, improve the stability of depth flux weakening and reduce torque loss in dynamic adjustment.

Background

With the development of national economy and science and technology, the motor plays more and more important roles in various industries. The permanent magnet synchronous motor benefits from a plurality of advantages in the aspects of design, manufacture and control, and is widely applied to various industrial production and living occasions. In addition, the rare earth resources in China are rich, and the application market of the permanent magnet synchronous motor is particularly large in China. The permanent magnet synchronous motor can be divided into a surface-mounted type and a built-in type according to the difference of quadrature-direct axis inductance, and the built-in type permanent magnet synchronous motor (IPMSM) can have a wider speed regulation interval under the condition of weak magnetism, so that the application is wider.

In the control strategy of IPMSM, in order to maximize efficiency and maximize utilization of current capacity, the motor is controlled to operate on a maximum torque to current ratio (MTPA) curve before field weakening, and is limited by a current limit relationship of an upper voltage limit as the motor speed is increased.

The permanent magnet synchronous motor is mostly required to operate in a wide speed range, high requirements are provided for the flux weakening quality, the flux weakening strategy is incomplete, and instability and even out of control of high-speed operation are easily caused. Especially, in the motor with the characteristic current point inside the current circle, the conventional directional flux weakening method is easy to cause the problem of voltage saturation in the vicinity of high-speed external characteristics, and particularly, the system control is unstable during dynamic adjustment.

The conventional flux weakening strategy has the following limitations: 1. the traditional flux weakening strategies are mostly concentrated in the area on the right side of the characteristic current point, the characteristics of the permanent magnet synchronous motor are not fully exerted, for the permanent magnet synchronous motor with a current limit circle larger than the characteristic current point, the power lifting space still exists on the left side of the characteristic current point, the control difficulty is increased when the permanent magnet synchronous motor runs in the area, the unstable factors are increased, instability is easy to occur, and part of flux weakening strategies do not control the area; 2. in an actual system, once a current circle and a voltage ellipse are intersected near a characteristic current point along with the rise of the rotating speed, the voltage ring is easy to lose control, the system stability is increasingly poor, and small disturbance can possibly cause the reverse change of instruction current and actual current to enter an out-of-control state; 3. the traditional flux weakening strategy is usually to avoid flux weakening instability in a torque sacrificing mode in dynamic response, the torque loss is large, and when the voltage utilization rate exceeds the preset voltage utilization rate, the traditional high-speed flux weakening strategy adopts a voltage closed loop to prevent instability, but the problem of torque loss is usually not considered, so that the torque sacrifice is large, and the high-speed power performance is influenced.

Disclosure of Invention

The invention provides a stepless depth flux weakening method for a permanent magnet synchronous motor, which aims to overcome the problem that the characteristics of the permanent magnet synchronous motor cannot be fully exerted in the prior art, and the method fully exerts the characteristics of the permanent magnet synchronous motor, has strong robustness, and is simple and easy to operate.

The invention also solves the problems of large torque loss and easy out-of-control in the prior art, can ensure that the motor stably runs in a deep weak magnetic region, and has the advantages of fast dynamic response, strong robustness and small torque loss.

In order to achieve the purpose, the invention adopts the following technical scheme:

a stepless depth flux weakening method for a permanent magnet synchronous motor comprises the following steps:

s1: the voltage closed-loop module is used for closed-loop regulating the required voltage compensation amount according to the required voltage utilization rate;

s2: the required voltage compensation quantity is input into a current lookup module to perform lookup to obtain a required current point;

s3: the required current point obtained by table lookup is output through the current regulator;

s4: calculating a voltage feedforward compensation quantity by a voltage feedforward unit at a required current point obtained by table lookup;

s5: the output of the current regulator and the voltage feedforward compensation quantity form the final wave-generating voltage.

Preferably, the S1 includes the following steps:

s11: the voltage closed-loop module sets the current bus voltage U according to the required voltage utilization rate_dc；

S12: will U_d ^*And U_q ^*After the arithmetic square root is solved, the current bus voltage U is set_dcPerforming linear operation;

S13：performing PI operation on the linear operation result to obtain a voltage compensation quantity delta U_dc；

Wherein, U_d ^*And U_q ^*Is the output of the current regulator.

Preferably, the S2 includes the following steps:

s21: weak magnetic current points are calibrated in advance and stored in a program of a current table look-up module;

s22: when the program is running, the current table look-up module looks up the table voltage U according to the compensated table_dcReal, from a lookup table of motor speed Spd and torque request Tor (i)_d，i_q)；

Wherein Tor represents a motor torque command.

Preferably, the S3 includes the following steps:

s31: the current regulator selects a PI controller;

s32: the current regulator will look up the current (i)_d，i_q) As a reference input;

s33: the current regulator performs PI operation on the lookup table current and idf and iqf to regulate the output reference voltage (U)_d*，U_qX); wherein idf and iqf are DQ axis currents fed back by the motor actually.

Preferably, the S4 includes the following steps:

s41: determining a flux linkage parameter table;

s42: the voltage feedforward unit obtains the reference current (i) according to the table lookup_d，i_q) Calculating real-time flux linkage psi by combining with flux linkage parameter table calibrated in advance_dAnd psi_q；

S43: the feedforward voltage calculation unit calculates the feedforward voltage compensation U according to the current rotating speed Spd of the motor_dC and U_qC。

Preferably, the S41 includes the following steps:

s411: calibrating and taking points through a rack;

s412: making a program table by a fitting method or an insertion method;

s413: running the code in real time according to (i)_d，i_q) And finding out the current magnetic linkage.

Preferably, the calculation method of S43 specifically includes calculating by a PMSM motor voltage equation, where the PMSM motor voltage equation is:

U_dC＝-Spd*2π/60*ψ_q

U_qC＝Spd*2π/60*ψ_d

wherein, U_dC and U_qC is feedforward voltage compensation quantity, Spd is current rotating speed of motor, psi_dAnd psi_qIs a real-time flux linkage.

Preferably, the specific calculation method of S5 is as follows: (U)_d*，U_qA and (U)_dC，U_qC) The sum of which constitutes the final wave voltage (U)_d，U_q}。

A stepless depth flux weakening system of a permanent magnet synchronous motor comprises a voltage closed loop module, a current look-up table module, a voltage feedforward unit and a current regulator.

Therefore, the invention has the following beneficial effects:

1. the invention expands high-speed strategy, improves the stability of deep weak magnetism and reduces the torque loss in dynamic adjustment;

2. the current after the compensation voltage is looked up is utilized to carry out a voltage feedforward module, the system stability is improved along with the increase of the rotating speed, the dynamic response can be rapidly and stably carried out during the high-speed flux weakening, the torque loss is small, and the loss of the torque is avoided;

3. the characteristics of the permanent magnet synchronous motor are fully exerted, the motor is ensured to stably run in a deep weak magnetic area, the dynamic response is fast, the robustness is strong, and the operation is simple and easy.

Drawings

FIG. 1 is a flow chart of the present invention.

Fig. 2 is a block diagram of the architecture of the present invention.

Fig. 3 is a functional block diagram of the voltage closed loop module of the present invention.

FIG. 4 is a schematic block diagram of the current lookup module of the present invention.

FIG. 5 is a functional block diagram of the voltage feed forward unit of the present invention.

Fig. 6 is a functional block diagram of the current regulator of the present invention.

Fig. 7 is a functional block diagram of the present embodiment.

In the figure: 1. the device comprises a voltage closed-loop module 2, a current look-up table module 3, a voltage feedforward unit 4 and a current regulator.

Detailed Description

The invention is further described with reference to the following detailed description and accompanying drawings.