阅读说明：本技术 一种基于转矩闭环的永磁同步电机弱磁控制方法 (A kind of permanent magnet synchronous motor field weakening control method based on torque closed loop ) 是由 苏丹丹 李志远 李浩东 孙振铎 于 2019-09-04 设计创作，主要内容包括：本发明提供了一种基于转矩闭环的永磁同步电机弱磁控制方法。该方法基于空间电压矢量角度的弱磁控制原理,采用转矩闭环的控制策略,获得所需的空间电压矢量的角度。具体是,基于参考转矩与实际转矩之间的误差,采用PI控制策略,得到所需的空间电压矢量的角度。该方法无需求解强耦合的非线性方程组、不依赖于电机本身的电气参数,具有很强的鲁棒性,无需计算弱磁电流,大大简化了弱磁控制。(The present invention provides a kind of permanent magnet synchronous motor field weakening control methods based on torque closed loop.Weak magnetic control principle of this method based on space voltage vector angle obtains the angle of required space voltage vector using the control strategy of torque closed loop.Specifically, the angle of required space voltage vector is obtained using PI control strategy based on the error between torque reference and actual torque.This method is not necessarily to the Nonlinear System of Equations for solving close coupling, the electric parameter independent of motor itself, and there is very strong robustness to enormously simplify weak magnetic control without calculating weak magnetoelectricity stream.)

1. a kind of permanent magnet synchronous motor field weakening control method based on torque closed loop, characterized in that forever by torque closed-loop control Space voltage vector angle when magnetic-synchro motor weak magnetic controls.

2. the permanent magnet synchronous motor field weakening control method according to claim 1 based on torque closed loop, characterized in that be based on Error between torque reference and actual torque obtains the angle of required space voltage vector using PI control strategy.

3. the permanent magnet synchronous motor field weakening control method according to claim 2 based on torque closed loop, characterized in that required Space voltage vector angle γ^*Calculation formula it is as follows:

In formula, Δ T_eError between torque reference and actual torque, K_pT、K_iTThe respectively ratio and integration system of torque error Number, γ₀For the initial angle of voltage vector.

4. the permanent magnet synchronous motor field weakening control method according to claim 2 based on torque closed loop, characterized in that practical Torque is obtained after carrying out Clarke transformation and Park transformation according to the signal of current sensor feedback.

5. the permanent magnet synchronous motor field weakening control method according to claim 2 based on torque closed loop, characterized in that according to The angle γ of obtained required space voltage vector^*, and d shaft voltage V is calculated according to following formula_dWith q shaft voltage V_q；

In formula, V_smaxFor the maximum space voltage vector of inverter output；

Later to d shaft voltage V_dWith q shaft voltage V_qIt carries out Park inverse transformation and obtains v_α ^*、v_β ^*, and required electricity is modulated based on SVPWM Press vector.

Technical field

The present invention relates to Motor Control Field, specifically a kind of permanent magnet synchronous motor weak magnetic control based on torque closed loop Method processed.

Background technique

For permanent magnet synchronous motor, when DC bus-bar voltage is rated value and motor output torque is nominal torque, institute Corresponding motor speed is known as base speed.Base speed hereinafter referred to as permanent torque area, generallys use unitary current maximum torque control to drop Low copper wastage improves operational efficiency, while reducing the capacity requirement to inverter.

More than base speed, if rotor flux remains unchanged, the counter electromotive force of rotor will be greater than the maximum input electricity of motor Pressure, motor speed will be unable to further increase.The magnetomotive force that permanent-magnetic synchronous motor rotor permanent magnet generates is constant, only passes through tune Stator current is saved, i.e. increase field supply component, permanent magnet magnetic potential is offset using armature-reaction, reduced motor gas-gap and synthesize magnetic Gesture realizes weak magnetic speed-up.Base speed generallys use weak magnetic control referred above to invariable power area to weaken air gap flux linkage and limit anti- Electromotive force makes it not improve and increase with revolving speed.Weak magnetic control is to realize the important means of permanent magnet synchronous motor high-speed cruising.Such as Under the premise of where guaranteeing that motor works normally, DC bus-bar voltage is made full use of, to reduce weak magnetoelectricity stream, is all the time The difficult point of weak magnetic control.

Summary of the invention

It is an object of the invention to provide a kind of permanent magnet synchronous motor field weakening control methods based on torque closed loop, with abundant Using DC bus-bar voltage, weak magnetoelectricity stream is reduced.

The object of the present invention is achieved like this: a kind of permanent magnet synchronous motor field weakening control method based on torque closed loop, Space voltage vector angle when being controlled by torque closed-loop control permanent magnet synchronous motor weak magnetic.Specifically, it is based on torque reference Error between actual torque obtains the angle of required space voltage vector using PI control strategy.

The calculation formula of the angle of required space voltage vector is as follows:

In formula, Δ T_eError between torque reference and actual torque, K_pT、K_iTThe respectively ratio and product of torque error Divide coefficient, γ₀For the initial angle of voltage vector.

According to the angle γ of obtained required space voltage vector^*, and d shaft voltage V is calculated according to following formula_d With q shaft voltage V_q；

In formula, V_smaxFor the maximum space voltage vector of inverter output；

Later to d shaft voltage V_dWith q shaft voltage V_qIt carries out Park inverse transformation and obtains v_α ^*、v_β ^*, and institute is modulated based on SVPWM Need voltage vector.

The present invention is based on the weak magnetic control principles of space voltage vector angle to be obtained using the control strategy of torque closed loop The angle of required space voltage vector.This method is without solving the Nonlinear System of Equations of close coupling, independent of motor itself Electric parameter, there is very strong robustness without calculating weak magnetoelectricity stream to enormously simplify weak magnetic control.

Detailed description of the invention

Fig. 1 is the maximum voltage polar plot that inverter is exported in linear zone.

Fig. 2 is inverter maximum output voltage V under dq coordinate system_smaxWith the relational graph of dq shaft voltage.

Fig. 3 is the functional block diagram of the FW control based on torque closed loop.

Specific embodiment

In order to make full use of DC bus-bar voltage, to reduce weak magnetoelectricity stream, the invention proposes one kind to be based on torque closed loop Permanent magnet synchronous motor field weakening control method.

(1) mathematical model of the permanent magnet synchronous motor under dq two-phase rotating coordinate system is established

When analyzing three-phase permanent magnet synchronous motor, generally requires and does following hypothesis:

1) stator winding Y shape connects, and leads to symmetrical three phase sine alternating current；

2) saturation effect of silicon steel sheet is ignored, and air-gap field is at Sine distribution；

3) eddy-current loss and magnetic hystersis loss of motor are not considered；

4) there is no excitation winding on rotor.

According to above-mentioned it is assumed that voltage equation of the permanent magnet synchronous motor under dq two-phase rotating coordinate system are as follows:

In formula (1), V_d、V_qRespectively stator voltage component under dq two-phase rotating coordinate system；L_d、L_qRespectively d-axis (d axis) Inductance and quadrature axis (q axis) inductance, have L for durface mounted permanent magnet synchronous motor_d=L_q, have L for internal permanent magnet synchronous motor_d< L_q；i_d、i_qThe respectively electric current of d axis and q axis；R_sFor stator winding resistance；ω_rFor the angular rate of rotor；λ_fFor permanent magnet production Raw magnetic linkage.

The torque equation of motor are as follows:

In formula (2), T_eTo export electromagnetic torque, P is the number of poles of permanent magnet synchronous motor.

(2) maximum output voltage of inverter

The transmission characteristic of inverter refers to the relationship between line voltage virtual value and modulation index.Modulation index (Modulation Index, MI) is defined as the ratio between peak value and maximum fundamental wave phase voltage of inverter fundamental wave phase voltage phasor, Calculation method is as follows:

In formula (3), V_dcFor DC bus-bar voltage.

As inverter output voltage V_sFor space voltage vector hexagon maximum inscribed circle when, the value of modulation index are as follows:

Space voltage vector modulation (Space Vector Pulse Width Modulation, SVPWM) control strategy Advantage is can to directly control alternating-current motor stator magnetic linkage rotational trajectory, to obtain quasi-circular rotating excitation field, therefore can be not High switching frequency declines low torque ripple, reduces current harmonics.When modulation index is less than 0.907, inverter output line electricity It is linear relationship between pressure and modulation index.Once modulation index is more than or equal to 0.907, inverter output line voltage and modulation Non-linear, current harmonics increase at the same time, torque pulsation increase can be presented in index.To guarantee that inverter works in linear zone, The maximum value of modulation index should take 0.907.

When modulation index is equal to 0.907, the voltage vector of inverter output is its maximum value V in linear zone_smax, such as Shown in Fig. 1, which is the radius of the maximum inscribed circle of space voltage vector hexagon.Hexagon is no no-voltage arrow in Fig. 1 The maximum voltage vector that inverter can be output when amount, but current harmonics increases at this time, and torque pulsation increases, and inverter work exists Inelastic region.To reduce current harmonics, six side of voltage vector for using space voltage vector modulation technology to export inverter The inscribed circle of shape.Modulation index is equal to 0.907 at this time, and the voltage vector of inverter output is the radius V of inscribed circle_smax。

(3) based on the weak magnetic control principle of space voltage vector angle

For permanent magnet synchronous motor, either controlled using unitary current maximum torque control or weak magnetic, Voltage equation under dq two-phase rotating coordinate system is the same, i.e. formula (1).But inverter under both control strategies The constraint condition of output voltage vector (see formula (6)) is different (such as formula (7), (8)), thus the property of equation group have it is bright Significant difference is different.

V_s< V_smax (7)

V_s=V_smax (8)

When using unitary current maximum torque control, voltage vector V needed for motor work_sIt is defeated less than inverter maximum Voltage V out_smax(see formula (7)), voltage equation of the permanent magnet synchronous motor under dq two-phase rotating coordinate system are two independent Linear equation, therefore can be solved using the method for decoupling.Theoretically, after motor speed and given torque reference, the two Whether there is or not array solutions for equation, and can get by unitary current maximum torque control makes the smallest optimal solution of stator current.

It is limited by DC bus-bar voltage, the maximum output voltage of inverter is V_smax.Under weak magnetic control, in order to improve The utilization rate of DC bus-bar voltage, the voltage vector V of motor work_sInverter maximum output voltage V should be equal to_smax(see formula (8)), voltage equation group of the permanent magnet synchronous motor under dq two-phase rotating coordinate system is two non-linear sides to intercouple at this time Journey.After motor speed and torque reference are given, which only has unique solution.In the solution of Nonlinear System of Equations In the process, even there is the disturbance of very little, it is also possible to cause the greatest differences of solution.And motor is during the work time, it is various to disturb It is dynamic be it is unavoidable, such as the fluctuation of DC bus-bar voltage, the variation of the parameter of electric machine, inverter output voltage it is non-linear Deng.Therefore, which is one of the difficult point of weak magnetic control.

The maximum space voltage vector V of inverter output_smaxRelationship with dq shaft voltage is as shown in Fig. 2, γ is V in figure_smax With q shaft voltage V_qBetween angle.At this point, dq shaft voltage can be calculated by formula (9).

Formula (9) are substituted into permanent magnet synchronous motor in the voltage equation formula (1) under dq two-phase rotating coordinate system, it can :

Formula (10) is the theoretical basis of the weak magnetic control proposed by the invention based on space voltage vector angle.Pass through Analysis is it is found that formula (10) is single input (γ), dual output (i_q、i_d) Nonlinear System of Equations, and each given input quantity (γ) can only acquire one group of solution (i of equation group_q、i_d), the group solution based on equation can calculate this according to torque formula (2) When output torque.

Therefore, the weak magnetic control based on space voltage vector angle can not decouple Nonlinear System of Equations (formula (10)) Under the premise of, torque reference needed for the angle (γ) by controlling space voltage vector makes motor output, without being answered with calculating Given weak magnetoelectricity stream (i_d)。

(4) based on the permanent magnet synchronous motor field weakening control method of torque closed loop

When being controlled using the weak magnetic based on space voltage vector angle, after given voltage vector angle, the output of motor Torque is unique.It therefore can be based on the error between torque reference and actual torque, using PI control strategy, needed for obtaining Space voltage vector angle γ^*, it is shown below:

In formula, Δ T_eFor torque reference T_e ^*With actual torque T_eBetween torque error, K_pT、K_iTRespectively torque error Ratio and integral coefficient, γ₀For the initial angle of voltage vector.

Fig. 3 is the functional block diagram of weak magnetic (FW) control proposed by the invention based on torque closed loop.Firstly, electric current is passed The signal of sensor feedback carries out Clarke transformation and converts with Park, obtains current motor output torque T_e, and calculate itself and reference Torque T_e ^*Between error delta T_e；Then, carrying out PI (formula (11)) to torque error can be obtained the space electricity of inverter output Press the angle γ of vector^*, and d axis and q shaft voltage are calculated according to formula (9)；Finally, it is inverse to carry out Park to d axis and q shaft voltage Transformation obtains v_α ^*、v_β ^*, and required voltage vector is modulated based on SVPWM.