阅读说明：本技术 无差拍转矩控制装置、方法和系统 (Deadbeat torque control apparatus, method and system ) 是由 向超群 成庶 李卓鑫 张璐琳 陈春阳 于 2019-10-25 设计创作，主要内容包括：本发明公开了一种无差拍转矩控制装置、方法和系统。其中,无差拍转矩控制方法包括：包括：接收参考转矩<Image he="65" wi="85" file="DDA0002247971840000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>定子电压μ<Sub>sα</Sub>,μ<Sub>sβ</Sub>,定子电流i<Sub>sα</Sub>,i<Sub>sβ</Sub>,定子电阻R<Sub>s</Sub>,离散周期T<Sub>s</Sub>,定、转子自感和定转子互感L<Sub>s</Sub>,L<Sub>r</Sub>,L<Sub>m</Sub>,电机极对数p；计算定子磁链和转子磁链；计算k时刻感应电机的转矩；计算k时刻感应电机的转矩角；计算转矩角增量；对定子磁链离散化,得到k时刻的定子磁链,以及k时刻参考定子磁链；计算k+1时刻的定子电压。根据本发明技术方案,通过无差拍控制代替直接转矩控制的滞环比较器,并加入延时补偿,实现转矩的准确跟踪,减小转矩脉动,固定了开关频率。(The invention discloses a deadbeat torque control device, method and system. The deadbeat torque control method comprises the following steps: the method comprises the following steps: receiving a reference torque Stator voltage mu sα ，μ sβ Stator current i sα ，i sβ Stator resistance R s Discrete period T s Stator and rotor self inductance and stator and rotor mutual inductance L s ，L r ，L m The number p of pole pairs of the motor; calculating a stator flux linkage and a rotor flux linkage; calculating the torque of the induction motor at the moment k; calculating a torque angle of the induction motor at the moment k; calculating a torque angle increment; discretizing the stator flux linkage to obtain a stator flux linkage at the time k and a reference stator flux linkage at the time k; meterAnd calculating the stator voltage at the k +1 moment. According to the technical scheme of the invention, a dead-beat control replaces a hysteresis comparator controlled by direct torque, and delay compensation is added, so that accurate tracking of the torque is realized, torque pulsation is reduced, and switching frequency is fixed.)

1. A deadbeat torque control method, comprising:

receiving a reference torque

the stator flux linkage and the rotor flux linkage are calculated according to the following formulas:

Ψ_s＝L_si_s+L_mi_r Ψ_r＝L_ri_r+L_mi_s

decomposing the stator flux linkage in a two-phase static coordinate system to obtain psi_sαAnd psi_sβCalculating the torque of the induction motor at the moment k according to the following formula:

T_e(k)＝p[ψ_sα(k)i_sβ(k)-ψ_sβ(k)i_sα(k)]

calculating the torque angle of the induction motor at the moment k according to the following formula:

The torque angle increment is calculated according to the following equation:

discretizing the stator flux linkage to obtain the stator flux linkage at the moment k:

and reference stator flux at time k:

The stator voltage at time k +1 is calculated according to the following equation:

2. a deadbeat torque control method, comprising:

receiving a reference torque

the stator flux linkage and the rotor flux linkage are calculated according to the following formulas:

Ψ_s＝L_si_s+L_mi_r Ψ_r＝L_ri_r+L_mi_s

decomposing the stator flux linkage in a two-phase static coordinate system to obtain psi_sαAnd psi_sβCalculating the torque of the induction motor at the time k according to the following formula

T_e(k)＝p[ψ_sα(k)i_sβ(k)-ψ_sβ(k)i_sα(k)]

Calculating the torque angle of the induction motor at the moment k according to the following formula:

The torque angle increment is calculated according to the following equation:

discretizing the stator flux linkage to obtain the stator flux linkage at the moment k:

and time kReference stator flux linkage:

The stator voltage at time k +2 is calculated according to:

3. a deadbeat torque control apparatus, comprising:

receiving means for reference torque

a torque calculation component that calculates stator flux linkage and rotor flux linkage according to the following formulas:

Ψ_s＝L_si_s+L_mi_r Ψ_r＝L_ri_r+L_mi_s

decomposing the stator flux linkage in a two-phase static coordinate system to obtain psi_sαAnd psi_sβCalculating the torque, T, of the induction machine at time k according to the following formula_e(k)＝p[ψ_sα(k)i_sβ(k)-ψ_sβ(k)i_sα(k)]；

A torque angle calculation means for calculating a torque angle of the induction motor at time k according to the following equation:

A torque angle increment calculating means for calculating a torque angle increment according to the following formula:

a discretization component for discretizing the stator flux linkage to obtain the stator flux linkage at the time k:

Stator voltage calculation means for calculating a stator voltage at the time k +1 according to the following formula:

4. a deadbeat torque control apparatus, comprising:

a receiving part for receiving a reference torque

torque calculation means for calculating the stator flux linkage and the rotor flux linkage according to the following formulas:

Ψ_s＝L_si_s+L_mi_r Ψ_r＝L_ri_r+L_mi_s

decomposing the stator flux linkage in a two-phase static coordinate system to obtain psi_sαAnd psi_sβCalculating the torque of the induction motor at the time k according to the following formula,

T_e(k)＝p[ψ_sα(k)i_sβ(k)-ψ_sβ(k)i_sα(k)]

a torque angle calculation means for calculating a torque angle of the induction motor at time k according to the following equation:

A torque angle increment calculating means for calculating a torque angle increment according to the following formula:

a discretization component for discretizing the stator flux linkage to obtain the stator flux linkage at the time k:

and reference stator flux at time k:

Stator voltage calculation means for calculating a stator voltage at the time k +2 according to:

5. a deadbeat torque control system, comprising:

a rotational speed sensing device for sensing a rotational speed of a rotor of the induction motor;

a PI regulator for outputting a reference torque according to the rotor speed sensed by the speed sensing device and a reference speed;

the deadbeat torque control device of claim 3 or 4 connected to said PI regulator;

the three-level SVPWM is connected with the dead-beat torque control device;

a transistor, an input terminal of which is connected to an output terminal of the three-level SVPWM;

an induction motor connected to an output terminal of the transistor;

power sensing means for sensing voltage and current of a stator three phase winding of the induction machine;

and the coordinate transformation module is used for converting the voltage and the current of the three-phase winding of the stator of the induction motor to a two-phase static coordinate system and outputting the result to the deadbeat torque control device.

6. A deadbeat torque control method for use with the system of claim 5, comprising:

sensing a rotor speed of the induction motor by a speed sensing device;

outputting a reference torque according to the rotor rotating speed sensed by the rotating speed sensing device and a reference rotating speed through a PI regulator;

sensing, by a power sensing device, a voltage and a current of a stator three-phase winding of the induction machine;

converting the voltage and the current of a stator three-phase winding of the induction motor to a two-phase static coordinate system through a coordinate conversion module, and outputting the result to the deadbeat torque control device;

calculating stator voltage through a deadbeat torque control device, and outputting the stator voltage to a three-level SVPWM;

the three-level SVPWM outputs a switching sequence signal to the induction motor via the transistor.

Technical Field

The invention relates to space voltage vector pulse width modulated direct torque control, in particular to a deadbeat torque control device, method and system.

Background

The three-level inverter is a topological structure with low harmonic content and low switching loss, compared with a two-level inverter, a switching device has lower voltage stress and is widely applied to the field of high voltage and high power, and the three-phase eight-switch is used as a fault-tolerant structure of the three-level topological structure, so that compared with a four-bridge-arm redundant structure, the three-level inverter has fewer devices and is simple to operate. However, the three-phase eight-switch topology has the problem of uneven voltage division of a direct-current side support capacitor, namely, the midpoint potential is deviated, the harmonic content of voltage is increased, the voltage born by two ends of a power tube is increased, and the normal operation of a load is influenced. In order to solve the problems, a TL-Boost circuit is used as input of a three-phase eight-switch in a research on a three-phase eight-switch two-stage T-type photovoltaic grid-connected inverter, and the neutral point potential is controlled by controlling the on-off of a switch tube. The literature, "model prediction direct torque control of a three-phase eight-switch fault-tolerant inverter-driven PMSM system" adopts model prediction direct torque control, establishes a cost function of voltage vector influencing torque, flux linkage and midpoint potential according to a mathematical model of a motor, selects a vector with the minimum cost function as an optimal proper output, and inhibits fluctuation of the midpoint potential to a certain extent, but determination of weight coefficients corresponding to the flux linkage, the torque and the midpoint potential in the cost function is difficult. The literature, namely an eight-switch three-phase inverter-induction motor transmission system direct torque control algorithm, adds a midpoint potential hysteresis comparator on the basis of an original hysteresis comparator for direct torque control, and prepares a new switching vector table, so that the midpoint potential is considered while electromagnetic torque and flux linkage are controlled.

Direct Torque Control (DTC) is an ac motor Control method with fast response, simple structure and good robustness. However, the traditional direct torque control adopts hysteresis comparison control to replace a current loop, flux linkage and torque cannot be accurately controlled, pulsation of the flux linkage and the torque is caused, and the observation accuracy of the flux linkage and the rotating speed directly influences the control accuracy of a system; because the switching frequency of the device is not fixed, the output current generates harmonics of different frequencies. In order to solve the problems, researchers at home and abroad make researches, and the literatures of 'surface-mounted permanent magnet synchronous motor direct torque control variable angle prediction control' and 'surface-mounted permanent magnet synchronous motor direct torque control variable amplitude value prediction control research' equally divide the amplitude value and the phase angle of a voltage vector, and select the optimal voltage vector to output by calculating that the predicted flux linkage and the deviation of the torque from a given value are minimum, so that the torque pulsation is reduced. The literature 'research on direct torque control of a permanent magnet synchronous motor based on a second-order sliding mode algorithm' is to replace a traditional PI controller with a second-order sliding mode controller, reduce the influence caused by the observation error of flux linkage and torque, and reduce torque pulsation. The literature 'novel duty ratio modulation strategy for direct torque control of permanent magnet synchronous motor' formulates a novel switch table based on flux linkage and torque weight factors by comparing the action degree of voltage vectors on flux linkage and torque, selects an optimal vector, and then calculates the optimal duty ratio of the selected vector according to the minimum composite pulsation of the flux linkage and the torque, thereby taking both flux linkage pulsation and torque pulsation into consideration. Documents of 'direct torque control research of a permanent magnet synchronous motor based on a sliding-mode observer' and 'direct torque control research of a sliding-mode flux observer of an induction motor' adopt the sliding-mode observer to observe flux linkage and rotating speed respectively, so that the robustness and control precision of a system are improved, and the dynamic response of the system is accelerated. The document "direct torque control of induction machine based on constant frequency torque controller" compares the torque PI with two opposite triangular waves, replaces a hysteresis comparator, fixes the switching frequency and reduces the current harmonics. The document discloses an improved asynchronous motor model prediction direct torque control method, which is based on the traditional model prediction direct torque control with delay compensation, adds a switching frequency term in a cost function of torque and flux linkage to limit the switching frequency, optimizes a vector selector, solves the cost function by using three voltage vectors of a sector where a predicted reference voltage vector is located, selects an optimal vector, reduces the calculation amount of the cost function solution, reduces the torque and flux linkage pulsation, and reduces the switching frequency.

Dead beat Control (DB) is a discrete time predictive Control method, aiming to make the Control variable reach the desired value in one Control period, with fast response speed and high Control accuracy. The literature 'dead beat direct torque control of the built-in permanent magnet synchronous motor based on the effective flux linkage observer' takes electromagnetic torque as a dead beat control variable, changes hysteresis control of direct torque into dead beat control, solves a unitary quadratic equation, selects an optimal voltage vector, and outputs the voltage vector by a space voltage vector modulation method, so that torque pulsation is reduced, control accuracy is improved, but equation solution is complex, a calculation process is complex, and corresponding rapidity is reduced. In order to avoid solving a quadratic equation, the literature 'simplifying design of deadbeat space vector modulation direct torque control' simplifies deadbeat torque control, selects a voltage vector based on direct torque control, only carries out deadbeat control on the torque based on constant flux linkage amplitude, calculates the duty ratio of the selected voltage, reduces the calculated amount, reduces torque pulsation to a certain extent and improves the control precision. The literature "dead-beat current predictive control of a permanent magnet synchronous motor" is based on motor vector control, a current PI controller is changed into a current dead-beat controller, the control rapidity is improved, but when the nominal inductance of the controller exceeds twice of the actual inductance, a system can be unstable, and current oscillation is caused. The literature, namely 'permanent magnet synchronous motor dead-beat current prediction control', considers sampling delay and calculation delay, adopts a current dead-beat controller, predicts twice currents, eliminates static errors, considers the influence of nonlinearity and dead time of an inverter on voltage distortion, compensates the distortion of voltage in the current dead-beat controller, and improves the steady-state precision of a system.

Disclosure of Invention

Deadbeat-based direct torque control has not been applied to control a three-phase eight-switch inverter. The present invention has been made in view of the above.

According to an embodiment of the present invention, there is provided a deadbeat torque control method including: receivingReference torqueStator voltage mu_Sα,μ_sβStator current i_sα,i_sβStator resistance R_sDiscrete period T_sStator and rotor self inductance and stator and rotor mutual inductance L_s，L_r，L_mThe number p of pole pairs of the motor; the stator flux linkage and the rotor flux linkage are calculated according to the following formulas: Ψ_s＝L_si_s+L_mi_rψ_r＝L_ri_r+L_mi_sThe stator flux linkage is decomposed in a two-phase static coordinate system to obtain psi_sαAnd psi_sβCalculating the torque of the induction motor at the moment k according to the following formula:

T_e(k)＝p[ψ_sα(k)i_sβ(k)-ψ_sβ(k)i_sα(k)]

calculating the torque angle of the induction motor at the moment k according to the following formula:

wherein

The torque angle increment is calculated according to the following equation:

discretizing the stator flux linkage to obtain the stator flux linkage at the moment k:

and reference stator flux at time k:wherein theta is_s(k+1)＝θ_s(k) + Δ δ (k); the stator voltage at time k +1 is calculated according to the following equation:

according to still another embodiment of the present invention, there is provided a deadbeat torque control method including: receiving a reference torque

Stator voltage mu_sα,μ_sβStator current i_sα,i_sβStator resistance R_sDiscrete period T_sStator and rotor self inductance and stator and rotor mutual inductance L_s，L_r，L_mThe number p of pole pairs of the motor; the stator flux linkage and the rotor flux linkage are calculated according to the following formulas: Ψ_s＝L_si_s+L_mi_rΨ_r＝L_ri_r+L_mi_s(ii) a Decomposing the stator flux linkage in a two-phase static coordinate system to obtain psi_sαAnd psi_sβCalculating the torque of the induction motor at the moment k according to the following formula:

T_e(k)＝p[ψ_sα(k)i_sβ(k)-ψ_sβ(k)i_sα(k)]

calculating the torque angle of the induction motor at the moment k according to the following formula:wherein

The torque angle increment is calculated according to the following equation:

discretizing the stator flux linkage to obtain the stator flux linkage at the moment k:and reference stator flux at time k:

wherein theta is_s(k+2)＝θ_s(k) + Δ δ (k); the stator voltage at time k +2 is calculated according to:

according to still another embodiment of the present invention, there is provided a deadbeat torque control apparatus including: a receiving part for receiving a reference torque

Stator voltage mu_sα,μ_sβStator current i_sα,i_sβStator resistance R_sDiscrete period T_sStator and rotor self inductance and stator and rotor mutual inductance L_s，L_r，L_mThe number p of pole pairs of the motor;

a torque calculation component that calculates stator flux linkage and rotor flux linkage according to the following formulas: Ψ_s＝L_si_s+L_mi_rΨ_r＝L_ri_r+L_mi_sThe stator flux linkage is decomposed in a two-phase static coordinate system to obtain psi_sαAnd psi_sβCalculating the torque of the induction motor at the moment k according to the following formula:

T_e(k)＝p[ψ_sα(k)i_sβ(k)-ψ_sβ(k)i_sα(k)]

a torque angle calculation means for calculating a torque angle of the induction motor at time k according to the following equation:

wherein

A torque angle increment calculating means for calculating a torque angle increment according to the following formula:

a discretization component for discretizing the stator flux linkage to obtain the stator flux linkage at the time k:

and a reference stator flux at time k, i.e. a stator flux at time k +1：

Wherein theta is_s(k+1)＝θ_s(k) + Δ δ (k); stator voltage calculation means for calculating a stator voltage at the time k +1 according to the following formula:

according to still another embodiment of the present invention, there is provided a deadbeat torque control apparatus including: a receiving part for receiving a reference torque

Stator voltage mu_sα,μ_sβStator current i_sα,i_sβStator resistance R_sDiscrete period T_sStator and rotor self inductance and stator and rotor mutual inductance L_s，L_r，L_mThe number p of pole pairs of the motor;

torque calculation means for calculating the stator flux linkage and the rotor flux linkage according to the following formulas: Ψ_s＝L_si_s+L_mi_rΨ_r＝L_ri_r+L_mi_s(ii) a A torque calculation unit for decomposing the stator flux linkage in the two-phase stationary coordinate system to obtain psi_sαAnd psi_sβCalculating the torque of the induction motor at the moment k according to the following formula:

T_e(k)＝p[ψ_sα(k)i_sβ(k)-ψ_sβ(k)i_sα(k)]

a torque angle calculation means for calculating a torque angle of the induction motor at time k according to the following equation:

wherein

A torque angle increment calculating means for calculating a torque angle increment according to the following formula:

a discretization component for discretizing the stator flux linkage to obtain the stator flux linkage at the time k:

and reference stator flux at time k:wherein theta is_s(k+2)＝θ_s(k) + Δ δ (k); stator voltage calculation means for calculating a stator voltage at the time k +2 according to:

according to still another embodiment of the present invention, there is provided a deadbeat torque control system including: the rotating speed observation device is used for sensing the rotating speed of the rotor of the induction motor; a PI regulator for outputting a reference torque according to the rotor speed sensed by the speed sensing device and a reference speed; the deadbeat torque control device is connected to the PI regulator; the three-level SVPWM is connected with the dead-beat torque control device; a transistor, an input terminal of which is connected to an output terminal of the three-level SVPWM; an induction motor connected to an output terminal of the transistor; a power sensing device for sensing voltage and current of a stator three-phase winding of an induction motor; and the coordinate transformation module is used for converting the voltage and the current of the three-phase winding of the stator of the induction motor to a two-phase static coordinate system and outputting the result to the deadbeat torque control device.

According to still another embodiment of the present invention, there is provided a deadbeat torque control method for the above system, including: sensing the rotor speed of the induction motor through a speed sensing device; outputting a reference torque according to the rotor rotating speed sensed by the rotating speed sensing device and a reference rotating speed through a PI regulator; sensing, by a power sensing device, a voltage and a current of a stator three-phase winding of an induction motor; converting the voltage and current of a stator three-phase winding of the induction motor to a two-phase static coordinate system through a coordinate conversion module, and outputting the result to a deadbeat torque control device; calculating stator voltage through a deadbeat torque control device, and outputting the stator voltage to a three-level SVPWM; the three-level SVPWM outputs a switching sequence signal to the induction motor via the transistor.

According to the technical scheme of the invention, a dead-beat control replaces a hysteresis comparator controlled by direct torque, and delay compensation is added, so that accurate tracking of the torque is realized, torque pulsation is reduced, and switching frequency is fixed.

Drawings

Fig. 1 shows the topology of an eight-switch three-phase inverter.

Fig. 2 shows a schematic flow diagram of a deadbeat torque control method according to an embodiment of the present invention.

Fig. 3 shows a schematic block diagram of a deadbeat torque control arrangement according to an embodiment of the present invention.

FIG. 4 shows a schematic block diagram of a deadbeat torque control system according to an embodiment of the present invention.

Fig. 5 shows an operation control block diagram of the deadbeat torque control system according to the embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to specific embodiments and the accompanying drawings.

Three-phase eight-switch inverter topology

The three-phase eight-switch T-type inverter is a fault-tolerant structure of a three-level T-type inverter in a fault state, that is, after a certain phase fails, a bridge arm of the phase is cut off, and a fault phase output is connected with a midpoint of a direct-current link, as shown in fig. 1.

Defining a switching function S_x：

x＝B,C

The stator voltage vector can be expressed as

Wherein, U_an，U_bnAnd U_cnRespectively stator phase voltages.

Induction machine mathematic model

In a two-phase stationary coordinate system, the voltage equation and flux linkage equation of an induction motor can be expressed as

Wherein u is_sIs the stator voltage i_s、i_rStator current and rotor current, R_s、R_rStator and rotor resistances, psi, respectively_s、ψ_rStator flux linkage and rotor flux linkage, omega, respectively_rAs the rotor speed, L_s、L_r、L_mThe self inductance of the stator and the rotor and the mutual inductance of the stator and the rotor are respectively.

The torque equation of the induction machine is

Wherein T is_eIs electromagnetic torque, p is the number of pole pairs of the motor, δ is the stator-rotor flux linkage angle, i.e., torque angle, and L'_sStator transient inductance:

deadbeat based direct torque control

The deadbeat control (DB) is a highly accurate time discrete technique, and the target of the deadbeat torque control is to make the electromagnetic torque reach a given value within one control cycle. Deadbeat-based direct torque control has not been applied to control a three-phase eight-switch inverter. The invention introduces dead-beat control of torque based on direct torque control of Space Vector Pulse Width Modulation (SVPWM) and is used for controlling an induction motor driven by a three-phase eight-switch converter.

First embodiment

According to a first embodiment of the present invention, a deadbeat torque control method is provided. Fig. 1 shows a schematic flow chart of the deadbeat torque control method. As shown in fig. 1, the method comprises the steps of:

s110, reference torque

Stator voltage mu_sα,μ_sβStator current i_sα,i_sβStator resistance R_sDiscrete period T_sStator and rotor self inductance and stator and rotor mutual inductance L_s，L_r，L_mThe number p of pole pairs of the motor;

s120, calculating a stator flux linkage and a rotor flux linkage,

wherein the stator flux linkage is calculated according to the following formula: Ψ_s＝L_si_s+L_mi_r，

The rotor flux linkage is calculated according to the following formula: Ψ_r＝L_ri_r+L_mi_s。

S130, decomposing the stator flux linkage in a two-phase static coordinate system to obtain psi_sαAnd psi_sβCalculating the torque of the induction motor at the moment k according to the following formula:

T_e(k)＝p[ψ_sα(k)i_sβ(k)-ψ_sβ(k)i_sα(k)]

calculating a torque angle of the induction motor at time k according to the following formula:

specifically, a torque equation of the induction motor is discretized, so that electromagnetic torque at the time k is obtained. The discretization process is to select a discretization period so that each physical quantity is kept unchanged in the period. In this embodiment, the discrete period is Ts, and each circuit parameter is not changed in one Ts period.

The objective of the deadbeat torque control is to make the torque at time k +1 equal to the torque setpoint obtained at the speed PI:

s140, calculating a torque angle increment, specifically according to the following formula:

specifically, sin δ (k +1) may be calculated from a torque calculation formula at the time k +1, and then the torque angle increment Δ δ (k) may be calculated in combination with a torque calculation formula of the induction motor at the time k.

S150, discretizing the stator flux linkage to obtain the stator flux linkage at the moment k:

according to the dead beat principle, the reference stator flux linkage at the k moment, namely the stator flux linkage at the k +1 moment:

wherein theta is_s(k+1)＝θ_s(k)+Δδ(k)

Thus, a reference stator flux linkage may be derived from the torque angle increment Δ δ (k)

S160, calculating the stator voltage at the time k +1 according to the following formula:

the process and reasons for using this formula to solve for the stator voltage are described below to facilitate the understanding of the formula used at step S160 by those skilled in the art:

the equations (6) and (7) in step S150 are decomposed in the two-phase stationary coordinate system

Discretizing the stator voltage equation in a two-phase static coordinate system with a discretization period of Ts,

by substituting the formulae (8) and (9) for the formula (10), the formula

According to the formula, the voltage vector u required to be output to the SVPWM can be calculated_ref(k) (the voltage obtained according to equation 11 is the predicted reference voltage vector u_ref(k) Two components) and then outputs pulses according to a space vector pulse width modulation scheme, thereby controlling the output of the inverter.

Second embodiment

Due to the delay of calculation and one beat of control period in the digital control system, the reference voltage vector calculated at the moment k acts at the moment k +1 and reaches the given torque and the given flux linkage at the moment k + 2. In order to eliminate the one-beat lag of a digital control system, the delay compensation is added into a dead-beat direct torque controller, and the electromagnetic torque and the stator flux linkage are predicted twice. The following describes a calculation procedure and a calculation result in the case of predicting the electromagnetic torque and the stator flux linkage twice.

The electromagnetic torque and the stator flux linkage at the time k +2 can be predicted according to the equations (3) and (11)

Due to the reference voltage vector calculated at the time k, a given torque and a given flux linkage are only reached at the time k +2, i.e.

The torque angle increment Δ δ (k) is obtained from equations (3) and (14)

By adding the formulae 11 and 13

Stator resistance voltage drop R due to k and k +1 time_si_sα(k) And R_si_sαThe (k +1) is very small compared with other terms, and can be ignored, so that the calculation is more accurate, the resistance voltage drop of the stator at the k moment and the k +1 moment can be considered to be unchanged, namely R_si_sα(k)＝R_si_sα(k +1), and according to the deadbeat torque control principle, the stator flux linkage angle at time k +2 is θ_s(k+2)＝θ_s(k)+Δδ(k)

Equation (17) can be simplified as:

as can be seen from the above description, in the method of the second embodiment, steps S140, S150, and S160 of the first embodiment are adjusted, and other steps are the same as or similar to those of the first embodiment.

Third embodiment

According to a third embodiment of the present invention, there is also provided a deadbeat torque control apparatus. Fig. 3 shows a schematic block diagram of the apparatus. As shown in fig. 3, the apparatus includes:

receiving means 310 for receiving a reference torque

Stator voltage mu_sα,μ_sβStator current i_sα,i_sβStator resistance R_sDiscrete period T_sStator and rotor self inductance and stator and rotor mutual inductance L_s，L_rLm, number of motor pole pairs p;

a torque calculation component 320 for calculating the stator flux linkage and the rotor flux linkage according to the following formulas: Ψ s ═ Lsi_s+L_mi_rΨ_r＝L_ri_r+L_mi_s(ii) a Decomposing the stator flux linkage in a two-phase static coordinate system to obtain psi_sαAnd psi_sβCalculating the torque of the induction motor at the moment k according to the following formula:

T_e(k)＝p[ψ_sα(k)i_sβ(k)-ψ_sβ(k)i_sα(k)]

a torque angle calculating part 330 for calculating a torque angle of the induction motor at time k according to the following equation:

a torque angle increment calculating means 340 for calculating a torque angle increment according to the following formula:

discretization means 350 discretizing the stator flux to obtain the stator flux at time k:

and a time k reference stator flux, i.e. a time k +1 stator flux:

wherein theta is_s(k+1)＝θ_s(k)+Δδ(k)

A stator voltage calculating part 360 for calculating a stator voltage at the time k +1 according to the following formula:

the torque angle increment calculating means 340, the discretizing means 350 and the stator voltage calculating means 360 of the apparatus may also perform the method steps described in the second embodiment. For the device, please refer to the above description of the method embodiment, which is not described in detail herein.

Fourth embodiment

According to a fourth embodiment of the present invention, there is also provided a deadbeat torque control system. Fig. 4 shows a schematic block diagram of the deadbeat torque control system. As shown in fig. 4, the deadbeat torque control system includes the following components:

the rotational speed sensing device 410 for sensing the rotational speed of the rotor of the induction motor may be a speed sensor. And a PI regulator 420 for outputting a reference torque according to the rotor rotation speed sensed by the rotation speed sensing means and the reference rotation speed. The function of the PI regulator 420 is to determine the most suitable reference torque according to the actual rotation speed of the induction motor, so that the torque of the induction motor k +1 or k +2 reaches the reference torque at the moment.

A deadbeat torque control means 430 connected to the PI regulator, and the specific configuration of the deadbeat torque control means 430 can be seen from the description relating to the third embodiment.

The three-level SVPWM 440 is connected to the deadbeat torque control means. And a transistor 450 having an input terminal connected to an output terminal of the three-level SVPWM. And an induction motor 460 connected to an output terminal of the transistor. A power sensing device 470 for sensing the voltage and current of the stator three-phase winding of the induction machine. And a coordinate transformation module 480 for transforming the stator three-phase winding voltage and current of the induction motor to a two-phase stationary coordinate system and outputting the result to the deadbeat torque control device. Since the voltage and current sensors measure the voltage and current of the three-phase winding of the stator of the induction motor, and belong to a three-phase static coordinate system, for research convenience, the coordinate transformation module 480 transforms the stator voltage and current of the three-phase static coordinate system of the induction motor to a two-phase static coordinate system.

The deadbeat torque control means 430 receives the voltage and current on the two-phase stationary coordinate system from the coordinate conversion module 480, receives the reference torque from the PI regulator, and performs the calculation processing described in the first or second embodiment, thereby outputting the predicted reference voltage vector U to the three-level SVPWM_refThe three-level SVPWM outputs a switching sequence to the transistor 450.

FIG. 5 shows a control block diagram of the operation of a three-level deadbeat predictive direct torque control system based on space vector modulation. Wherein the rotation speed sensing device 410 senses an actual observed rotation speed of the induction motor, the actual observed rotation speed ω_rAnd a reference rotational speed

The reference torque is output after passing through the PI regulator 420. The reference rotating speed is a reference value defined according to the specific use condition of the motor, for example, in the field of rail transit, the speed of a train needs to be within a certain range in the turning process of the train, and the range can be used as the basis for setting the reference rotating speed. The power sensing device 470, not shown, senses three-phase voltages and currents of the stator of the induction motor, and converts the three-phase voltages and currents into voltages and currents in a two-phase stationary coordinate system, which are input to the deadbeat torque control device 430, through the coordinate transformation module 480. The torque calculation component and the stator-rotor flux linkage calculation component are shown in a simplified combination as "torque flux linkage observation" modules. Reference torque and actual torqueThe torque angle increment is obtained by the torque angle increment calculating part 340, i.e. the reference flux linkage is obtained, and the predicted reference voltage vector U is obtained by the stator voltage calculating part 360_ref(the stator voltage calculated according to the formula 11 or 18 is two components of the prediction reference voltage vector), and finally outputs the switching sequence S by the three-level SVPWM method_a，S_b，S_c。

Fifth embodiment

Accordingly, the present invention also provides a deadbeat torque control method for the control system of fig. 5, comprising:

sensing the rotor speed of the induction motor through a speed sensing device;

outputting a reference torque according to the rotor rotating speed sensed by the rotating speed sensing device and a reference rotating speed through a PI regulator;

sensing, by a power sensing device, a voltage and a current of a stator three-phase winding of an induction motor;

converting the voltage and current of a stator three-phase winding of the induction motor to a two-phase static coordinate system through a coordinate conversion module, and outputting the result to a deadbeat torque control device;

calculating stator voltage through a deadbeat torque control device, and outputting the stator voltage to a three-level SVPWM;

the three-level SVPWM outputs a switching sequence signal to the induction motor via the transistor.

Those of ordinary skill in the art will understand that: the discussion of any embodiment above is meant to be exemplary only, and is not intended to intimate that the scope of the disclosure, including the claims, is limited to these examples; within the idea of the invention, also features in the above embodiments or in different embodiments may be combined, steps may be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

In addition, well known power/ground connections to Integrated Circuit (IC) chips and other components may or may not be shown within the provided figures for simplicity of illustration and discussion, and so as not to obscure the invention. Furthermore, devices may be shown in block diagram form in order to avoid obscuring the invention, and also in view of the fact that specifics with respect to implementation of such block diagram devices are highly dependent upon the platform within which the present invention is to be implemented (i.e., specifics should be well within purview of one skilled in the art). Where specific details (e.g., circuits) are set forth in order to describe example embodiments of the invention, it should be apparent to one skilled in the art that the invention can be practiced without, or with variation of, these specific details. Accordingly, the description is to be regarded as illustrative instead of restrictive.

While the present invention has been described in conjunction with specific embodiments thereof, many alternatives, modifications, and variations of these embodiments will be apparent to those of ordinary skill in the art in light of the foregoing description. For example, other memory architectures (e.g., dynamic ram (dram)) may use the discussed embodiments.

The embodiments of the invention are intended to embrace all such alternatives, modifications and variances that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, substitutions, improvements and the like that may be made without departing from the spirit and principles of the invention are intended to be included within the scope of the invention.