RU2401502C2 - Frequency-regulated asynchronous drive - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: there is provided electric drive operation with forced parametres by the torque that is three times higher relative to nominal value and speed up to 1.5 Ω_nom while providing reliable operation of electric drive power unit. Frequency-regulated asynchronous drive has four control loops: drive speed control loop, rotor flux linkage control loop and control loops of active and reactive components of motor stator current vector. To create forced operation modes following is introduced in control system: correction unit isolating control channels and excluding their interference, limiters of moment, currents and AM stator voltage setting signals providing correct motor speed regulation depending on the torque with preset overload factor, functional converter automatically separating regulation zones with forced torque and speed, units providing forward flow shaping before sending electric drive speed regulation signal, setting unit for motor rotor speed rise intensity to set desired electromagnetic torque changing rate and smoothing surges and pulsations in setting signal.

EFFECT: higher dynamic characteristics and reliable operation of power converter; expansion of application range for asynchronous drive; decrease in cost, dimensions, weight; saving materials, resources and consumed energy.

6 cl, 8 dwg

Description

The invention relates to electrical engineering, in particular to frequency-controlled electric drives built on the basis of asynchronous electric motors, and can be used in precision high-speed electric drives, for example, in electric drives installed in mechanisms of mobile hoisting cranes, in stop valves of pipeline transport, in modern metal-cutting machines with CNC and other technical facilities using modern energy-saving technologies.

Known asynchronous electric drive with feedback on the angular velocity of the rotor of the engine [1] - Pozdeev A.A. Electromagnetic and electromechanical processes in frequency-controlled asynchronous electric drives. - Cheboksary: From Chuvash. Univ., 1998. - 172 pp. (p. 51, Fig. 3.9 - analogue), in which the frequency-current vector control method with indirect field orientation is adopted to control the speed of the electric motor. The structure of this electric drive includes functionally coupled frequency converter (autonomous voltage inverter), phase current sensors of the electric motor, speed sensor of the electric motor rotor, PI-regulators of rotation speed, flow and torque components of the stator current, slip reference unit and coordinate converters from the rotating coordinate system to the stationary and from stationary to rotating, ensuring the generation of sinusoidal signals and the stator current orientation along the rotor flux linkage vector. The known drive system allows for independent control of the flux and electromagnetic moment of the induction motor, however, it does not provide accurate orientation of the coordinate system in various operating modes. During the operation of the electric drive, the influence of the operation of the channels for regulating currents and speed is manifested and, as a result, the required quality of torque control in dynamic and static modes of operation is not provided, the structure of the control system does not exclude inrush currents in transient modes. In this case, the static and dynamic characteristics of the drive fall [2] - Glazenko TA, German-Galkin SG, Polishchuk SB, Rydov VA Frequency-controlled asynchronous electric drives for CNC machines. - L., DCSTP, 1988 .-- 28 p., Ill.

Closest to the proposed invention is an adjustable asynchronous electric drive [3] - Patent for the invention No. 2313894, IPC Н02Р 21/12, 27/08, Frequency-controlled asynchronous electric drive. Sidorov P.G., Aleksandrov E.V., Lagun V.V., priority of the invention 06/19/2006, which is selected as a prototype. The electric drive contains a power unit with a series voltage rectifier included in it, a smoothing filter with a voltage sensor, a voltage inverter, the control inputs of which are connected to the outputs of the vector PWM unit, an asynchronous electric motor whose windings are connected through the phase current sensor block to the voltage inverter output, and output shaft to the sensor of the speed of rotation of its rotor and to the transmission mechanism, the adjuster of the current angular speed of the electric motor connected to the first input a speed regulator, to the second input of which the output of the rotor speed sensor is connected, a motor flux linker connected through a large-scale amplifier to the first input of the reactive current regulator, the output of which is connected to the first input of the voltage transformer, the active current regulator is connected to the second input, outputs coordinate voltage transformer connected to the inputs of the vector PWM block, coordinate current transformer connected by inputs to the outputs a block of phase current sensors, and outputs with a second input of the reactive current regulator and with the first input of the active current regulator, a division unit and an observational drive status block equipped with first and second large-scale amplifiers, an aperiodic link, a divider, an integrator and an adder, while the output of the first large-scale the amplifier is connected to the first input of the divider, the output of which through the integrator is connected to the first input of the adder, to the second input of which the output of the second large-scale amplifier is connected, the output of the adder under it is connected to one of the inputs of the vector PWM block, to the input of the coordinate current transducer and to the input of the coordinate voltage transducer, the output of the aperiodic link is connected to the second input of the divider and the second input of the division unit, to the second input of which the output of the speed controller is connected, the output of the division unit is connected to the second input of the active current regulator and to the input of the first large-scale amplifier, and the rotor speed sensor of the electric motor rotor is made in the form of a pulse angular displacement sensor with two Exit, the first of which is the output of the angular position of the rotor of the motor, and a second - output rotation speed of the motor rotor, said first output pulse encoder coupled to the second input of scaling amplifier.

In the indicated frequency-controlled electric drive, the current angular position of the flux linkage is calculated not from the actual values of the stator currents, but from their predetermined values, and the engine torque reference is generated from the actual flux linkage value of the motor rotor. Such a construction of the control system improves the dynamic performance of the drive and increases the reliability of the converter. However, the control system of this electric drive does not provide full use of the capabilities inherent in the induction motor, namely, the operation of the drive with maximum (forced) moments M _max = (2.0-3.0) M _nom in the speed range of the rotor of the electric motor from zero to nominal and with maximum power in the speed range from Ω _Nom to 1.5Ω _Nom . Reliable operation of the electric drive with forced operation modes of the executive electric motor in terms of torque and speed reduces the rated power of the electric motor and the drive as a whole, reduces the overall mass characteristics of the drive, mechanical transmission, and allows the introduction of energy-saving technologies in modern industrial equipment.

The objective of the invention is to ensure the operation of the drive with forced modes of the Executive motor at a moment two to three times relative to the nominal value and speed up to 1.5Ω _nom while ensuring reliable operation of the power unit of the frequency converter of an asynchronous electric drive.

The solution to this problem is achieved by the fact that in a frequency-controlled asynchronous electric drive containing a power unit with a network voltage rectifier included in it, a smoothing filter with a voltage sensor, a voltage inverter, the control inputs of which are connected to the outputs of the vector PWM unit, asynchronous motor, windings which is connected through a block of phase current sensors to the output of the voltage inverter, and the output shaft to the speed sensor of its rotor and to the transmission gear zmu, current motor angular speed adjuster, electric motor flux linkage adjuster, speed controller connected in series, to the second input of which the output of the rotor speed sensor is connected, and the first division unit, active and reactive current regulators, coordinate voltage converter, the outputs of which are connected to the unit inputs vector PWM, coordinate current transducer connected by inputs to the outputs of the phase current sensors block, and outputs with the second input of the reactant regulator current and with the first input of the active current regulator, an observational block of the state of the electric drive, equipped with the first and second scale amplifiers, aperiodic link, divider, first integrator and first adder, while the output of the first scale amplifier is connected to the first input of the divider, the output of which is through the first integrator connected to the first input of the first adder, to the second input of which the output of the second large-scale staff amplifier is connected, the output of the first adder is connected to one of the inputs of the vecto PWM, to the input of the coordinate current transducer and to the input of the coordinate voltage transducer, the output of the aperiodic link is connected to the second inputs of the divider and the second input of the first division unit, and the rotor speed sensor of the electric motor rotor is made in the form of a pulse sensor with two outputs, the first of which is the output the angular position of the rotor of the electric motor, and the second by the output of the rotational speed of the rotor of the electric motor, while the first output of the pulse sensor is connected to the input of the second large-scale amplifier In particular, the first functional converter is introduced in series, the first and second input of which are connected respectively to the output of the flux linkage master and the second output of the pulse sensor, the first multiplier, the flux linkage regulator, the second input of which is connected to the output of the aperiodic link, and the first restriction block, the output of which is connected to the first input of the reactive current regulator and the input of the aperiodic link, the second functional converter, the output of which is connected to the second input of the first the second multiplier, the second limiting block connected in series to the input of which the reactive current regulator is connected, and the second adder, the third limiting block connected in series to the input of which the active current regulator is connected, and the third adder, the voltage limiting block, to which the first and second input are connected respectively, the second and third adders, and the outputs of the voltage limiting block are connected to the inputs of the coordinate voltage transformer, the correction block, the first, second, third and fourth the inputs of which are connected respectively to the first and second outputs of the coordinate current transducer, to the second output of the pulse sensor and the output of the aperiodic link, and the first and second outputs, respectively, to the second inputs of the second and third adders, the first relay element connected in series, the input of which is connected to the output of the flux linkage , and the logical adder, the second relay element, the input of which is connected to the output of the aperiodic link, and the output to the second input of the logical adder, the connected switch and the intensity controller, the output of which is connected to the first input of the motor speed controller, as well as the fourth limiting unit, the input of which is connected to the output of the first division unit, and the output to the second input of the active current controller and the input of the first large-scale amplifier, while the control input of the switch is connected to the output of the logical adder.

The first functional converter comprises a third scale amplifier, a second division block and a module block connected in series, the first and second input of the converter functionally being the input of the third scale amplifier and the second input of the second division block, and the output of the module block being the output.

The second functional converter comprises a rise time adjuster and a second integrator connected in series, as well as a non-linear element, the input and output of which are connected respectively to the output and the second input of the second integrator, the output of the second functional converter being the output of the second integrator.

The correction unit contains a fourth scale amplifier, a differentiator and a fourth adder connected in series, a fifth scale amplifier and a second multiplier connected in series, the output of which is connected to the second input of the fourth adder, a sixth scale amplifier, a third multiplier and a fifth adder, and a seventh scale amplifier, the input of the fourth large-scale amplifier is simultaneously connected to the second inputs of the second and third multipliers and the seventh sum Ator, the first input of the correction unit is the input of the fifth scaling amplifier, the second input - input of the sixth scaling amplifier, the third input - input of the fourth scaling amplifier fourth input - a first input of the seventh scale amplifier, and first and second output respectively, - the output of the fourth and fifth adders.

The correction unit provides compensation for the effect of cross-linking on the processes occurring in the torque circuit of the drive in accordance with the expressions:

- коэффициент рассеяния; I_d, I_q проекции векторов напряжения и тока статора на оси d и q; ω_ψ - частота вращения вектора потокосцепления ротора.where ψ _r is the flux linkage module of the rotor; L _s , L _r , L _m - phase inductance of the stator, rotor, mutual;

- scattering coefficient; I _d , I _q projection of the stator voltage and current vectors on the d and q axes; ω _ψ is the rotation frequency of the rotor flux linkage vector.

The maximum value of the task of the active current generated in the fourth block limitation is determined in accordance with the expression:

where K _m - coefficient of overload at the moment; I _s , I _d - nominal values of stator current vectors and active current.

As illustrations in figure 1 is a vector diagram explaining the principle of orientation of the coordinate system along the rotor flux linkage vector; figure 2 is a functional diagram of the proposed variable frequency drive; figure 3 - functional diagram of the first functional Converter; 4 is a functional diagram of a second functional Converter; 5 is a functional block diagram of the correction; 6 is a limitation of the output voltage of a stand-alone voltage inverter; Fig.7 - selection of the vectors of the output voltage of the voltage inverter; Fig. 8 is a voltage plot explaining the operation of an electric drive.

The frequency-controlled asynchronous electric drive contains a power unit (SB) 1 with a network voltage rectifier (V) 2 included in it, a smoothing filter (SF) 3 with a voltage sensor (DN) 4 and a voltage inverter (IN) 5, vector pulse modulation (PWM block) 6, induction motor (M) 7, phase current sensor block (BFT) 8, transmission mechanism (PM) 9, pulse displacement sensor (ID) 10 with two outputs, the first output 11 is the angular position of the rotor electric motor, and the second output 12 - th speed setpoint current angular speed of the motor (GPV) 13, dial flux linkage of the motor 14, the speed controller (CWR) 15, a first division unit (DB1) 16, the active current controller (PT _q) 17, a reactive current regulator (PT _d) 18, the coordinate voltage transducer (KP1) 19, the coordinate current transducer (KP2) 20, the observational block of the state of the electric drive (NBS) 21, containing the first 22 and second 23 scale amplifier (MU1), (MU2), aperiodic link (A3) 24, divider (D) 25, the first integrator (I1) 26 and the first adder (C1) 27, therefore, the connected first functional converter (FP1) 28, the first multiplier (P1) 29, the flow controller (RP) 30 and the first restriction unit (BO1) 31, the second functional converter (FP2) 32, the second connected restriction block (BO2) 33 in series the second adder (C2) 34, the third adder block (BO3) 35 connected in series and the third adder (C3) 36, the voltage limiter (BON) 37, the correction unit (BC) 38, the first relay element (RE1) 39 connected in series and the logic adder (I) 40, the second relay element (RE2) 41, a series-connected switch (Com) 42 and an intensity adjuster (ZI) 43, a fourth limiting unit (BO4) 44.

The functional converter FP1 consists of a series-connected third scale amplifier (MU3) 45, a second division unit (BD2) 46 and a module unit (BM) 47.

Functional converter FP2 consists of a slew rate generator 48, a second integrator (I2) 49 and a non-linear element (NE) 50.

The correction unit consists of a fourth scale amplifier (MU4) 51 and a differentiator (Dif) 52 connected in series, a fifth scale amplifier (MU5) 53 connected in series, a second multiplier (P2) 54 and a fourth adder (C4) 55 connected in series with a sixth scale amplifier ( MU6) 56, the third multiplier (P3) 57 and the fifth adder (C5) 58, the seventh scale amplifier (MU7) 59.

All used components of the control system are known or can be obtained from known devices by combining them by known methods.

The application and construction of coordinate converters of voltages 19 and currents 20 are described in detail in [4] - Elements of a frequency drive control system with subordinate vector control. / Alekseev V.V., Dartau V.A., Rudakov V.V. - Electrical industry. Electric Drive Series. - M., 1981. issue 4 (93), speed controllers 15, currents 17, 18, flux link 30 with known requirements for the circuit can be built according to the requirements and rules set forth in [5], Besekersky V.A., Popov E.P. Theory of automatic control systems. - M .: Nauka, 1973. - 350 s, with the implementation of the hardware based on the methods given in [6] - Tetelbaum IM, Schneider Yu.R. 400 circuits for ABM. - M., Energy, 1978, division block 16, 46, divider 25, smoothing filter 3, integrator 26, 49, scale amplifier 22, 23, 45, 51, 53, 56, 59, aperiodic link 24, adder 27, 34 , 36, 55, 58, multiplier 29, 54, 57, restriction block 31, 33, 35, 44, relay element 39, 41, non-linear element 50, module block 47, differentiator 52, as well as logical adder 40 can be implemented on operational amplifiers [7] - U. Titze, K. Schenk. Semiconductor circuitry. - M .: Mir, 1982, [8] - Lyseko E.V. Functional elements of relay devices on integrated circuits. - M.: Energoatomizdat, 1083. - 128 p., [9] - Shilo V.L. Functional analog integrated circuits. - M .: Radio and communications, 1982. - 128 p. or digital circuits. Switch 42 can be implemented on reed switches, relays, electronic keys, etc. The hardware implementation and operation of the vector PWM 6 unit with operation diagrams is described in [10, 11] - Izosimov DB, Rybkin S.E. Pulse width modulation of three-phase autonomous inverters. - Electricity, 1997. - No. 6, Izosimov DB, Rybkin S.E. Shevtsov S.V. Simplex control algorithms for a three-phase autonomous voltage inverter with PWM. - Electrical Engineering, 1993, No. 12. The operation of the pulse displacement transducer 10 is described in [12] - Displacement transducers. Indication blocks. Catalog 2001 - St. Petersburg, OJSC SKB "IS", 2001. - 125 p. Functional and electrical circuits of an autonomous voltage inverter 5, a rectifier of a network voltage 2, a smoothing filter 3, their operation and recommendations for use are given in [13] - German - Galkin SG. Computer Simulation of Semiconductor Systems in MATLAB 6.0: A Training Manual. - St. Petersburg: CROWN print, 2001 .-- 320 p., Ill. Functional and electrical circuits, a description of the work, and recommendations for choosing the elements of the intensity adjuster ZI 43 are given in [14]. Basharin A.V., Novikov V.A., Sokolovsky G.G. Electric Drive Management: A Textbook for High Schools. - L., Energy Publishing House. Leningra. Sep., 1982. - 392 s, pp. 54-59.

The power unit (SB) 1 provides the conversion and power amplification of the control signals received at the control inputs of the voltage inverter (IN) from the vector 6 PWM block 6, control the gates of the power transistors, the formation of protection and galvanic isolation of the power and control circuits.

Sensors of mechanical and electrical variables of the electric drive form normalized feedback signals with galvanic isolation of the measuring and information circuits. The following are used in the control equipment of the electric drive: voltage sensor (DN) 4, consisting of a resistive divider and an isolating amplifier with optocoupler isolation, installed in the DC link after a capacitive smoothing filter (SF) 3, a block of phase current sensors (BDFT) 8 of the compensation type, installed in the output phases of an autonomous voltage inverter (ID) 5, and a pulse sensor (ID) 10 installed in the transmission mechanism (PM) 9 or on the actuator motor (M) 7, which measures the speed and angular position of the mouth RA induction motor. When installing a displacement sensor in the transmission mechanism (PM) 9, the gear ratio of the kinematic chain from the motor shaft to the displacement sensor must be an integer value and have a value from 1 to 4, which is determined by the permissible maximum speed of the pulse sensor and the processing features of the sensor output signal [12 ] - Displacement transducers. Indication blocks. Catalog 2001 - St. Petersburg, OJSC SKB "IS", 2001. - 125 p.

In the angular displacement sensor (ID) 10, rectangular measuring pulses A and B are generated, shifted 90 degrees relative to each other, the repetition rate of which is determined by the speed of the electric motor, and the phase shift of signal A relative to signal B (either +90 degrees or -90 hail) determines the direction of rotation of the electric motor. A short pulse R determines the zero position of the pulse displacement sensor 10. In the electronic block of the pulse displacement sensor 10, made on the basis of TTL logic, voltage-normalized signals 0-5V are generated for subsequent processing and generation of signals proportional to the angle of rotation or speed of the motor rotor [10] - p. 3-5. Displacement transducers. Indication blocks. Catalog. - St. Petersburg: OJSC SKB "IS", 2001. - 125 p.

The functional converter FP1 generates a signal for setting the flux linkage of the rotor ψ ₂ . The functional relationship between the real motor speed ω and the flux linkage of the rotor HELL determines the constancy of ψ ₂ at the level of setting the nominal flux linkage of the rotor ψ _2nom at a rotor speed of 0 ω _rmax ω _r = ω _rnom and a decrease in ψ ₂ when ω _to > ω _nom . The latter option ensures the operation of blood pressure in the speed control zone above the nominal voltage with a constant nominal voltage of the stator.

The functional converter FP2 at a given time t _B generates a signal for setting the flux link ψ _2z in the form of a linearly increasing voltage with a stepped form of the input signal. After reaching steady-state value the output signal PP2, a power unit control system logic signal appears at SB1 control permission from the actuator control signal ω _z.

The formation of the required nature of the drive transient processes is associated with the use of a special master device - a ZI intensity adjuster [40]. The purpose of this driver is to convert the step-by-step driving signal of speed ω _s into a control signal ω _y , which will change in time according to a certain predetermined law. The linear law of the change in the signal ω _y in time is usually used.

The operation of the forced drive is as follows. Vector control of a frequency-controlled asynchronous electric drive is associated both with a change in the frequency and current values of the variables of the asynchronous motor - current, voltage, slip, and with the mutual orientation of their vectors in polar or Cartesian coordinate systems. By controlling the amplitude values of the variables and the angles between their vectors, the induction motor is fully controlled both in statics and dynamics, which gives a noticeable improvement in the quality of transients compared to scalar control. It is this fact that is decisive in the choice of systems with vector control.

The main purpose of the vector control system in a controlled drive is regulation and stabilization of engine torque and speed [15] - Rudakov VV, Stolyarov IM, Dartau VA Asynchronous electric drives with vector control. - L., Energoatomizdat, 1987 .-- 136 p.

The moment of the induction motor is formed due to the impact on the absolute values of the stator flux link vectors ψ ₁ , main flux link ψ _µ , rotor flux link ψ ₂ , stator currents I ₁ and rotor I ₂ , as well as phase shifts between them. The construction principle and technical implementation of electric drive control systems depend on which vectors are chosen as adjustable. A feature of control systems with a reference vector ψ ₂ is a simpler control structure than with a reference vector ψ _μ . The moment of blood pressure when the coordinate system is oriented along the vector ψ ₂ is determined by the expression 1 [16] - Kovach KP, Ratz I. Transients in AC machines. - M-L., Gosenergoizdat, 1963 .-- 744 p.

where L ₂ is the inductance of the rotor winding, reduced to the stator circuit, L ₁₂ is the mutual inductance.

A vector diagram with the orientation of the flux linkage vector of the rotor ψ ₂ along the d axis of the coordinate system dq is shown in Fig. 1. The vectors of the magnetization currents I _µ , the rotor I ₂ and the projection of the stator and rotor current vectors on the axis of the rotating — d, q and fixed — α, β coordinate systems are also shown there. Wherein

those. in the steady state, the rotor current vector I _{2 is} perpendicular to the vector ψ ₂ , behind it by an angle of 90 el. hail, and its modulus at ψ ₂ = const changes in proportion to the absolute slip.

In motor mode, the stator current vector I _{1 is} ahead of the vector ψ ₂ by an angle

θ = arc tg (L ₂ ω _0nom s _a / R ₂ ), its component I _1d = ψ ₂ / L ₁₂ determines the flux linkage of the rotor ψ ₂ and the component I _1q = ψ ₂ L ₂ ω _0nom S _a / (L ₁₂ R ₂ ) compensates for the effect of the rotor reaction on it.

In accordance with expressions (1), (2), the electromagnetic moment of an induction motor is determined by the interaction of the orthogonal components of the rotor flux linkage ψ ₂ = ψ _2d = L ₁₂ I _1d and the stator current I _lq . Thus, during stabilization ψ ₂ , as well as during stabilization ψ _µ , the vector control system will be similar to the control system for DC motors, where the stator current component I _1d determines the flux linkage ψ ₂ AM (magnetic flux of the DCT), and the component I _1q is the moment component stator current (similar to the current of the DPT armature).

по оси d при отсутствии задания скорости и статической нагрузки на валу АД (М_с=0) должно обеспечиваться задание исходного потокосцепления ψ₂ лишь за счет составляющей тока статора I_1d. При этом вектор тока статора

, равный по модулю току I_1d, будет совпадать по направлению с вектором

, равным по модулю потокосцеплению ψ_2d. Если подобного совпадения не произойдет, то появление составляющей I_1d≠0 приведет согласно (1) к возникновению электромагнитного момента М≠0 и при М_с=0 начнется движение вала ротора АД. Тогда за счет обратной связи по скорости двигателя система должна обеспечить фазовый поворот вектора

до его совпадения с вектором

, при котором электромагнитный момент станет равным нулю и произойдет останов двигателя. При неподвижном роторе (f₁=0, αω_0ном=0) и отсутствии статической нагрузки вектор

будет неподвижен в пространстве, а ток I₁ - постоянным во времени. Подобное состояние АД аналогично условию подачи постоянного тока в обмотку возбуждения ДПТ без подключения его якорной цепи к источнику напряжения.The vector diagram of figure 1 allows you to give a physical interpretation of the principle of construction of vector control systems of blood pressure. In a control system with orientation of the rotor flux link vector

along the d axis, in the absence of a speed and a static load on the AM shaft (M _s = 0), the initial flux linkage ψ ₂ must be set only due to the stator current component I _1d . In this case, the stator current vector

equal in absolute value to the current I _1d will coincide in the direction with the vector

modulo flux linkage ψ _2d . If such a coincidence does not occur, then the appearance of the component I _1d ≠ 0 will lead, according to (1), to the appearance of an electromagnetic moment M ≠ 0 and when M _s = 0, the movement of the rotor shaft of the HELL will begin. Then, due to feedback on the engine speed, the system should provide a phase rotation of the vector

until it matches the vector

at which the electromagnetic moment becomes equal to zero and the engine stops. With a stationary rotor (f ₁ = 0, αω _0nom = 0) and the absence of static load, the vector

will be motionless in space, and the current I ₁ - constant in time. Such a state of blood pressure is similar to the condition for supplying direct current to the excitation winding of the DCT without connecting its armature circuit to a voltage source.

относительно

и, в итоге, формирование электромагнитного момента М≠0, под действием которого при М>Мс начинается движение вала ротора АД. Это движение будет происходить до тех пор, пока реальная скорость АД не сравняется с заданным значением. При их равенстве вектор

вновь устанавливается по направлению вектора

, а электромагнитный момент становится равным нулю. Однако в отличие от предыдущего режима ток статора является уже переменным во времени, а вектор

вращается в пространстве со скоростью, пропорциональной частоте тока статора. С той же скоростью вращается и система координат d-q. Поэтому составляющие I_1d и ψ_2d остаются на прежнем уровне. АД работает в режиме идеального холостого хода со скоростью, связанной с заданной частотой тока статора. Подобное состояние АД аналогично режиму идеального холостого хода ДПТ, когда при постоянном его возбуждении и М_с=0 якорная цепь ДПТ подключена к регулируемому источнику постоянного напряжения.When a signal for setting the speed of blood pressure arrives, the control system first ensures the rotation of the vector

regarding

and, in the end, the formation of the electromagnetic moment M ≠ 0, under the action of which, at M> Ms, the movement of the rotor shaft begins. This movement will occur until the real blood pressure velocity is equal to the set value. With their equality, the vector

set again in the direction of the vector

, and the electromagnetic moment becomes equal to zero. However, unlike the previous mode, the stator current is already variable in time, and the vector

rotates in space at a speed proportional to the frequency of the stator current. The coordinate system dq rotates at the same speed. Therefore, the components I _1d and ψ _2d remain at the same level. AM works in idle mode at a speed associated with a given frequency of the stator current. Such a state of blood pressure is similar to the ideal idle mode of the DPT, when, with its constant excitation and M _c = 0, the anchor circuit of the DPT is connected to an adjustable constant voltage source.

относительно

таким образом, чтобы, во-первых, составляющая I_1d оставалась неизменной, сохраняя постоянство потокосцепления ψ₂, а во-вторых, составляющая I_1q увеличилась до значения, при котором электромагнитный момент становился равным моменту сил сопротивления на валу АД и двигатель выходил бы на установившийся режим.With an increase in the load on the AD shaft, the control system provides a vector rotation

regarding

so that, firstly, the component I _1d remains unchanged, maintaining a constant flux linkage ψ ₂ , and secondly, the component I _1q increases to a value at which the electromagnetic moment becomes equal to the moment of resistance forces on the motor shaft and the motor goes out steady state.

по мере увеличения нагрузки скользит по линии, перпендикулярной вектору

. Результирующая составляющая токов статора и ротора по оси q создает составляющую потокосцепления ψ_µq. При этом конец вектора ψ_µ скользит по прямой 2, также перпендикулярной вектору

. Таким образом, при увеличении нагрузки двигателя и стабилизации ψ₂ поток намагничивания двигателя также увеличивается.In the vector diagram of figure 1, the vector

as the load increases, it glides along a line perpendicular to the vector

. The resulting component of the stator and rotor currents along the q axis creates the flux linkage component ψ _µq . In this case, the end of the vector ψ _μ slides along the straight line 2, also perpendicular to the vector

. Thus, with an increase in engine load and stabilization of ψ ₂ , the magnetization flux of the engine also increases.

When the rotor flux linkage is stabilized (ψ ₂ = const), the mechanical characteristics of the AD are similar to the characteristics of DCTs with independent excitation. Since the theory and technical solutions of electric drive control systems with DPT having independent excitation are sufficiently tested, the attractiveness of using vector control systems with rotor flow control is understandable.

Functional diagram of an electric drive for vector control of an induction motor and determination of rotor flux linkage in the observational state block according to the flow model is shown in FIG. 2. The organization features of this variant of the functional diagram include the presence of four control loops for controlling the speed, flux linkage of the rotor, and components of the stator current vector. External to the current control loop I _q is the motor speed control loop. At the input of the current control loop I _q , the output of the speed controller U _pc , which sets the value of the electromagnetic moment, and the feedback signal calculated in KP2 are compared. External to the current path along the d axis is the rotor flux linkage control loop with the flow regulator (RP) 30. The output of the flow regulator (RP) 30 is a signal for setting the stator current component along the real axis I _d . At the input of the controller (RP) 30, the reference signal ψ _2z and the true value of the rotor flux calculated in the NBS 21 are compared. Considering the high requirements for the dynamic operating modes of the drive, the PID controller is used in the internal circuit of the stator current component ί _d , and the RP flux linkage controller in the external control loop can be performed either in the form of a PI-controller for an astatic control system, or in the form of a P-controller for a static system. To avoid significant overshoot in the internal circuit at the input of the current regulator RT it is advisable to install an aperiodic filter with a transfer function:

where T _f = T _r is the filter time constant.

Speed control loop with the speed controller (CWR) 15 is closed by the signal ω _r, the current proportional to the induction motor rotor speed obtainable with the pulse generator (ID) 10. The result of the summation in the controller 15, the rotational speed reference signal ω _z, and a negative feedback signal engine speed ω _t is a signal to set the engine torque. The polarity of the reference signal ω _s determines the direction of the moment and engine speed.

The optimal control loops are configured based on the slave control method based on the desired speed of the electric drive [17] - Remshin BI, Yampolsky DS Design and commissioning of subordinate control systems for electric drives. M., Energy. - 184 p. Information about the orientation of the coordinate system in real time is calculated by calculation in the observational state block based on the parameters of the blood pressure and the system of mathematical differential equations of the rotor chain of the blood pressure. This option of constructing a drive system provides high-quality control of the moment of blood pressure in the dynamics, as well as the ability to control speeds above the nominal. A prerequisite for the implementation of the proposed control structure is the presence of a pulse sensor on the HELL shaft, the resolution of which, ultimately, determines the maximum accuracy and range of regulation of the engine speed. The vector control system allows you to separate the control channels and provide independent control modulo the flux linkage vector of the rotor and the motor speed while maintaining direct proportionality between the moment developed by the motor and the stator current component, which is in quadrature with the rotor flux linkage wave. Thanks to this, it becomes possible to implement dual-zone speed control of the rotor HELL. In the first regulation zone from zero to the nominal speed, the motor is controlled by simultaneously increasing the amplitude and frequency of the output voltage of the frequency converter. In the second zone, regulation from nominal to maximum engine speed is controlled only by increasing the frequency of the converter output voltage. The voltage amplitude is maintained constant equal to the nominal value. This control allows you to increase the range of regulation of the engine speed above the nominal and, therefore, to expand the scope of frequency-controlled electric drives.

The frequency of the voltage at the output of the power block (SB) 1 in the d-q coordinate system is determined by the expression 3 [18] - Kozyaruk A.E., Rudakov V.V. Modern and promising algorithmic support for variable frequency drives. - St. Petersburg., El. tech. company, 2004. - 127 p .:

Therefore, in the first regulation zone, in accordance with (3), for ψ ₂ = const, the frequency ω ₀ changes in proportion to the voltage component U _s , and in the second regulation zone for U _s = const, the frequency ω ₀ changes inversely to the modulus of the rotor flux vector ψ ₂ . The rotor flux linkage vector module in the control system is set at the nominal value level.

The transfer from the control zone with constant torque to the control zone with constant power is carried out automatically using FP1. At the input of the rotor flux linkage controller, there is not a single constant driving action, but a signal inversely proportional to the rotor speed of the motor. This signal is amplified with a gain factor K _{ψ by a} third large-scale amplifier (MSM) 45 and is fed to the input of the second division unit 46 and calculation of the module (BM) 47. In the block of the module 47, the rotor flux link signal is limited from above at a unit level. Therefore, in the first control zone, when the rotor speed of the motor is less than the nominal ω _r <ω _{rnom, the} signal for setting the flux linkage does not change and the electric drive operates with ψ ₂ = const. After the engine accelerates to a speed above the nominal ω _r > ω _{rnom, the} rotor flux linkage signal leaves the limit and the electric drive goes into the second regulation zone.

The initial information for constructing a vector control system is information on the instantaneous values and spatial position of the flux linkage vector in the air gap, the instantaneous values of the stator currents or voltages, and the rotor speed of the motor. The coordinates of the electric drive, measured in a fixed coordinate system, can be converted to a rotating coordinate system, and constant values proportional to the components of the vectors in the fixed coordinate system can be extracted from them. According to these coordinates, control is performed. A rotating coordinate system is adopted in a certain way oriented relative to the engine flux linkage vector. Convenient control algorithms take place when the coordinate system is oriented relative to the flux linkage of the motor rotor.

The engine is powered by a power unit with a DC link and a voltage inverter. The voltage at the inverter output U _A , U _B , U _C creates currents in the stator windings of the motor ί _A , ί _B , ί _C in a fixed coordinate system. In the drive structure of FIG. 2, high-speed current loops are made in a rotating coordinate system. The output signals of the current regulators U _d and U _q , which are signals for setting the inverter voltage, are DC signals in a rotating coordinate system. Therefore, the current control loops along the direct and quadrature axes include coordinate transformers (KP1), (KP2) 19, 20. In the coordinate voltage transducer (KP1) 19, the control is transferred from the rotating coordinate axes dq to the stationary α-β according to the expression (4 ):

In the coordinate converter (KP2) 20, the calculation of the currents I _d and I _q proportional to the moment and flux linkage of the rotor of the electric motor occurs according to the expressions (5):

where i _α and i _β are the components of the current in a fixed coordinate system;

ω _to - the speed of rotation of the coordinate system rotating with the field of the electric motor.

The components of the stator current i _α , i _β in a fixed coordinate system are calculated from the actual instantaneous values of the phase currents of the electric motor stator measured in BFT 8 in accordance with expression (6) [2] - Glazenko T.A., German-Galkin S.G. , Polishchuk S.B., Rydov V.A. Frequency-controlled asynchronous electric drives for CNC machines. - L., LDNTP, 1988 .-- 28 s, ill .:

Instantaneous values of phase currents in a fixed coordinate system are measured using an electric current sensor of the LEM type [19] - Sensors - current and voltage transformers of the LEM series. Specifications TU 3413-001-00512622-96. - Tver, LLC "TVELEM". - 1996. - 29 p., Or a resistive sensor.

Reference signals U _α, U _β to calculate the phase voltages _{U A, U B, U C} , forming the desired phase stator currents i _a, i _a, i _c, outputted from the coordinate converter voltages 19 are applied to respective inputs of a vector PWM unit 6, where the projections of the equivalent voltage vectors at the terminals of the stator of the electric motor are calculated, which are instantaneous values of phase voltages averaged over a certain discrete interval from high-frequency switching pulsations.

The mathematical model of the AD rotor is implemented in the NBS 21, the input of which, in addition to the current values of I _d , I _q components of the stator current, receives a signal proportional to the angle of rotation of the motor rotor from the first output 11 of the pulse sensor 10. The NBS generates a signal proportional to the flux coupling ψ ₂ of the motor rotor and signal θ, which determines the orientation of the coordinate system. The structural diagram of the NBS is shown in Fig.5.

The observational block of the state of the electric drive (NBS) 21 is built in a rotating coordinate system (d-q), oriented along the rotor flux linkage vector. The unit restores the variables necessary for the implementation of the vector control algorithm in accordance with equations (7) of the rotor circuit of the electric motor:

Where:

- постоянная роторной цепи;

- constant rotor chain;

R ₂ , L ₂ , L _m - resistance, inductors of the rotor and the magnetization circuit;

ί _d , ί _q are the projections of the stator current vector on the d and q axes;

ω _ψ is the rotation frequency of the rotor flux linkage vector;

ω _s is the slip frequency;

ω _r is the rotational speed of the rotor of the electric motor;

Z _p is the number of pairs of poles; ψ ₂ - flux linkage of the rotor.

Note that to restore the variables in the observational block of state 21, instead of the real values of the stator current in the axes (d, q), their set values _{ί dз} , _{ί qз are used} , which is permissible for high-speed current circuits that work out the set values without phase and static errors.

The values of the rotor flux linkage and the frequency of the rotary EMF of the engine are determined in the observation block of state 21 in accordance with expressions 8, 9 obtained from the system of equations of the rotor circuit of the electric motor 7:

Expression (8) shows that when the rotary coordinate system d is oriented along the rotor flux linkage vector ψ ₂ , the flux linkage value is uniquely determined by the stator current component along the straight axis d. Expression (9) makes it possible for a known value of flux linkage to calculate the value of the frequency of the rotary EMF from the stator current component along the quadrature axis q. The calculation of the rotor flux linkage and the rotary EMF frequency according to formulas 8, 9 ensures the orientation of the d axis along the rotor flux link vector ψ ₂ (see the vector diagram of FIG. 1).

To determine the rotation angle θ, the sum of the measured velocity value multiplied by the number of pole pairs and the rotor frequency calculated in the state observation unit (NBS) 21 is calculated, which determines the current value of the voltage frequency at the motor stator - ω _0el = p _n ω + ω _{r .} Integration of this quantity in the integrator I1 26 gives the current value of the rotation angle θ of the rotating coordinate system dq relative to the fixed coordinate system α-β connected with the stator. This value is used in the coordinate converter blocks KP1, KP2 of the direct channel and the feedback channel to calculate the necessary values of the guides sinθ and cosθ.

In the proposed control system, the elimination of the influence of cross-links between the flow control channels and the engine speed is ensured by using high-speed current circuits [20] - Novotny D.W. and Lipo T.A. Introduction to Field Orientation and High Performance AC Drives Second Edition / IEE Industry Applications Society Annual Meeting. 1986. Section 2, and a special correction unit (BC) 38 that generates compensation signals in accordance with equations 10:

The exclusion of channel interference allows the rotor flux linkage control loop and the torque control loop to be considered autonomous and makes it possible to independently control the rotor flux linkage and the torque of an asynchronous electric motor, similar to how the excitation flux is regulated in an DC motor with independent excitation. In particular, it is possible to pre-magnetize the motor, i.e. the ability to set the flow before the speed reference signal is sent to the speed loop, and when the engine speed is zero.

Functional converters (FP1) 28, (FP2) 32 provide the formation of the amplitude value of the engine flow, as well as its slew rate. The signal for setting the flux linkage from ZP 14 is input to FP1. The output signal FP1 is determined by the value of the engine speed. As long as the engine speed does not exceed the nominal value, the signal at the output of FP1 sets the nominal flow, which remains constant in the entire range of speed regulation below the nominal value. When the motor speed exceeds the nominal value, the signal at the FP1 output will decrease and the speed greater than the nominal one will be achieved when the rotor flux linkage is weakened at a constant voltage value on the stator.

PP2 unit 32 with a signal _of a reference ψ OP1 28 to the input rotor flux control circuit provides a smooth increase of the rotor flux linkage. Block NE 50, connected by an input to the output of the integrator (I2) 49, and by an output with the input of the integrator I2, limits the maximum permissible value of flux linkage. The integrator gain determines the rate of increase of the rotor flux linkage taking into account the specified rise time supplied to the input of the integrator I2 from the rise time adjuster (RVN) 48.

At the input of the speed controller of the controlled drive, an intensity adjuster (ZI) 43 is provided. When a speed reference signal of any speed is applied to its input, including a step-like form, the change of the speed reference signal at the output of the intensity adjuster occurs according to a linear or other law, which ensures smooth the nature of acceleration and braking of the drive.

To ensure the correct operation of the slave control system, the output signal of the external loop controller must be limited [17, 21] - Remshin BI, Yampolsky DS Design and commissioning of subordinate control systems for electric drives. - M., Energy, 1975. - 184 s, Epstein I.I. Automated AC drive. - M., Energoatomizdat, 1982. - 120 p. To limit the stator currents along the straight and quadrature axes, flow restriction (RF) and speed (RFC) controllers are provided with output signal limiting blocks ί _d , ί _q (BO1), (BO4) 31.44. The limitation of the output signal of the external circuit controller comes into effect if in the transient the error signal at its input, which is the difference between the reference signal and the feedback signal, becomes unacceptably large. The lack of limitation of the output signal of the controller can lead to an unacceptable increase in the output value of the slave circuit. The presence of a restriction block not only in the flow control loop, but also in the speed control loop of the electric motor rotor allows you to independently limit the values of the motor torque and stator current along the q axis.

, не превышал предельно допустимого ограничения I_1огр. When choosing the current limiting values ί _d , ί _q (BO2), (BO3) 33.35, it means that they must be selected so that the stator total current module, defined as

, did not exceed the maximum permissible limit I _1gr.

Setting the maximum allowable maximum moments of blood pressure is limited by the limiter (BO4) 44. The signal M _{3 is} limited by BO4 44 at the level of the task corresponding to the selected maximum value of the electromagnetic moment of blood pressure. The torque value is determined by the control signal U _pc depending on the operating mode of the drive. The limitation of the electromagnetic moment is also associated with the choice of the maximum permissible stator current I _1max . To this end, in block BO4 44, taking into account the maximum stator current I ₁ and the real value of the stator current component along the d - I _1d axis, the vector of the maximum allowable stator current component I _{1qmax is determined} in accordance with the expression:

where K _m is the momentum boost coefficient

The constancy of the task of the electromagnetic moment when the rotor flux linkage is changed in accordance with the definition of the moment by expression (1) is ensured by dividing in (BD1) 16 the signal U _pc at the output of the RFC 15 proportional to the moment by a signal proportional to the rotor flux linkage ψ ₂ calculated in NBS 21. At the output of BD1, a reference signal is formed I _1qз of the stator current component along the q axis.

, то

, U_q=0, если

, то проводится проверка реализуемости активного напряжения U_q. Для проверки реализуемости напряжения U_q вводится вспомогательная величина

, характеризующая максимально реализуемое активное напряжение. Если |U_q|<U_qmax, то выход ограничителя равен U_d=U_dз, U_q=U_qз, в противном случае U_d=U_dз,

.The voltage limiting block (BON) 37 provides the formation of tasks for the active voltage and magnetization voltage, taking into account the voltage restrictions inherent in the voltage inverter. The area of physically realizable phase voltage of the blood pressure, powered by a voltage inverter, is a regular hexagon oriented by diameter along the directional unit vectors of the phases (Fig.6). The diameter of the hexagon is determined by the value of the constant voltage U ₀ from the smoothing filter (SF) 3 of the power unit (SB) 1. Using a piecewise-linear border of the hexagon as a voltage limit allows you to realize all the energy possibilities of the voltage inverter 5, but leads to ripples of the electromagnetic moment with frequency equal to six times the frequency of the electric motor. In order to eliminate pulsations of the electromagnetic moment, a “smooth” restriction is implemented in BON 37, i.e. voltage module limitation. Taking into account the different rates of magnetic and electrical processes in an induction motor in BON 37, a hierarchical check of the feasibility of the active voltage and reactive current of the active voltage and magnetization voltage calculated in the control units is carried out. A feasibility test of the voltage U _{d is} carried out, that is, if

then

, U _q = 0 if

, then the feasibility of the active voltage U _q is checked. To check the realizability of the voltage U _q, an auxiliary quantity is introduced

characterizing the maximum realized active voltage. If | U _q | <U _qmax , then the output of the limiter is U _d = U _dз , U _q = U _qз , otherwise U _d = U _dз ,

.

The input effect on controlling the speed of the drive with the ZUS 13 is fed to the input of the speed controller using a switching element (Com) 42 connected between the current angular speed adjuster 13 and the intensity adjuster 43. The state of the contacts of the switch 42 is determined by the signal value (1, 0) from the output adder logic (AND) 40. in the absence of signal flux ψ ₂ or in the presence, but the signal strength ψ ₂ from the first output Out1 supervisory state block (CHD) is less than 21 deadband relay element (RE2) 41, Uche switch (com) 42 is in an open state and a signal (GPV) 13 is not fed to the input (GI) 43 and, respectively, to the input of the speed controller (CWR) 15 drive. When setting the value of the signal ψ ₂ in accordance with the task, the key switches to the closed state, which allows you to control the speed of the electric motor. The use of serial connection of signals - first, the formation of the magnetization signal HELL - ψ _2z , and then the supply of a speed control signal ω _s allows you to prepare a magnetic motor system to create a moment, which eliminates the inrush current and torque, allows you to get allowable errors and to match the set and current drive speed without significant overshoot.

,

,

и

,

,

в соответствии с формулами:The vector PWM block 6 provides the formation of the law of modulation and the law of switching the power switches of the voltage inverter, which create voltage HELL in the phase windings in accordance with the tasks generated in the coordinate transformer (KP1) 19. The law of switching power switches minimizes switching losses in the autonomous voltage inverter and motor [9] - Izosimov DB, Rybkin S.E. Shevtsov S.V. Simplex control algorithms for a three-phase autonomous voltage inverter with PWM. - Electrical Engineering, 1993, No. 12. By the signals U _α , U _β in the PWM block, internal variables are formed

,

,

and

,

,

in accordance with the formulas:

where U _dα , U _dβ , U _qα , U _qβ are the tasks for the active voltage and magnetization voltage converted to the α - β system, taking into account the voltage limit.

According to the table, in accordance with the combination of signs of the total internal variables signΛ ¹ , signΛ ² , signΛ ³ , the number N of the sector of the space of realized stresses S _N is determined, in which the voltage reference vector is located. Nonzero vectors U *, U ** are determined, which are used to form the required voltage vector averaged over the period of modulation, and the fraction of the time λ *, λ ** of the inclusion of each of these vectors. Moreover, the turn-on time of the zero vector Λ ⁰ is defined as Λ ⁰ = 1-λ * -λ **. A graphical interpretation of the choice of output voltage vectors in the PWM block for controlling an autonomous voltage inverter is presented in FIG. 5

signΛ ¹ signΛ ² signΛ ³ N sectors λ * λ ** U * U ** + + + one Λ ¹ Λ ² U ₁ U ₂ + + - Invalid combination + - + 6 -Λ ² Λ ³ U ₆ U ₁ + - - 5 -Λ ³ Λ ¹ U ₅ U ₆ - + + 2 Λ ³ -Λ ¹ U ₂ U ₃ - + - 3 Λ ² -Λ ³ U ₃ U ₄ - - + Invalid combination - - - four -Λ ¹ -Λ ² U ₄ U ₅ U *, U ** - AIN output voltage vectors used to implement a given voltage vector; λ *, λ ** are the fractions of the PWM period times in which the selected PWM voltage vectors are included.

In accordance with the above algorithm, the vector PWM block 6 converts the output voltage signals of the KP1 coordinate converter into equivalent signals U _A , U _B , U _{C of a} three-phase coordinate system that determine the output voltages SB 1 of the frequency converter.

Presented in figure 2 functional blocks are mainly implemented by software in a microprocessor control system of the electric drive. The microcontroller also implements interface functions in connection with sensors of current, voltage, angle, speed.

In accordance with the principle of operation of the considered control system of FIG. 2, FIG. 8 shows the qualitative dependences of its main variables a) as a function of the moment of blood pressure with a constant speed reference signal — FIG. 8 (waveforms 1-6) M = var, ω _z = const; and b) as a function of the speed control signal at a constant static moment M _c = 0 - (oscillograms 7-12) ω _s = var, M = const.

As a result of the action of the PI speed controller, the mechanical characteristic of HELL has absolute static stiffness in the load region M _s <M _smah (line 1 in Fig. 8, oscill 1), and at M _s > M _{smah the} mechanical characteristic is due to limitation of the controller output signal the speed and PI controllers of the current components in the d, q axes is absolutely soft (line 2-3 in Fig. 8, oscill. 1). Speed stabilization when changing the load of the drive is provided by changing the output signal of the speed controller U _pc . The latter leads to a change in the reference signal M _{3 the} electromagnetic moment of blood pressure and the slip signal (Fig. 8, oscill. 6). As the static load M _s increases, the voltage at the output of SB1 and the slip signal s calculated in the state observational block (NBS) 21 (Fig. 8, oscill. 2) increase accordingly, and the motor speed remains unchanged and corresponds to a given value of ω _s . The dashed lines of the mechanical characteristics of the blood pressure in Fig. 8, axis 1 reflect the movement of the original characteristic ω _dw = f (M _n ) when the signal changes the speed. In this case, the engine operates with maximum torque at any value of the load moment in the range from M _n = 0 to M _n = M _max .

As the load increases, the stator current component I _q , which determines the BP moment, also increases (Fig. 8, oscills. 3), and the current component I _d and the rotor flux coupling ψ ₂ determined by it remain constant (Fig. 8, oscills.4-5 )

In the absence of a signal for setting the speed of blood pressure (ω _s = 0) and the absence of a load on the motor shaft, a constant moment of resistance forces M _s = 0, the initial output voltage U ₁ and the frequency of the converter f are equal to zero. When the load of the moment of resistance forces appears, the output voltage U ₁ and the frequency f of the converter correspond to the values at which the initial ideal idle speed of the motor drive ω ₀ 0 and the mechanical characteristic of the motor provides a moment M _s at ω = 0 (Fig. 8, oscill. 8, 9). According to this moment, the initial signals M _s , I _q , U _pc are also determined (Fig. 8, oscills 6, 10). In this case, the signals I _d and ψ ₂ determine the nominal flux linkage of the rotor (Fig. 8, oscill. 11, 12).

As the reference signal ω _z increases, the voltage and frequency at the SB output of the frequency converter also increase. With ω _s = ω _{som, the} output voltage of the SB and its frequency reach nominal values. Further increase _of the job ω accompanied constancy voltage U = U _1nom on Sa output (osts.7, 8) and the transition operation zone in BP reduction of rotor flux by reducing the stator current component I _d (8, osts.11-12) . The maximum moment also decreases. When ω _z = ω _zs, the ideal idle speed is set at the maximum specified level corresponding to f _ogre (point 2 in Fig. 8 oscill. 7). The stator current component and the rotor flux linkage corresponding to it are set at the same time at the minimum level I _d2 and ψ ₂₂ (os. 11, 12).

Thus, the use in the structure of a frequency-controlled asynchronous electric drive of a vector control system for the rotor speed of the electric motor with the organization of four control loops for controlling the speed, flux linkage of the rotor and stator current components in accordance with the provisions of the slave control method allowed us to solve the problem of operation of the drive actuator motor with forced modes 2-3 times torque overload in the speed range from zero to nominal and one-time speed overload when the drive is operating at a speed higher than the nominal one with flow attenuation.

To create forced operation modes with reliable operation of the power unit of the electric drive, the following are introduced into the structure of the drive control system: a correction unit that decouples the control channels and excludes their mutual influence on each other, limiters of reference signals to the torque, currents, and stator voltages of the motor unit, ensuring correct speed control electric motor depending on the moment with a given overload ratio, a functional converter that automatically separates the regulation zones with connected modes in time and speed, the switch and relay elements that provide the logic for generating control signals for the excitation of the electric motor and control the speed of the drive, which eliminates inrush currents in the voltage inverter and increases the reliability of the power unit, the rate of increase in the rate of increase of the rotor speed of the electric motor, which sets the desired rate of change of the electromagnetic moment and smoothing throws and ripples in the job signal.

The proposed construction of the control system provides, in comparison with the known solutions, higher dynamic performance by improving the speed and accuracy of coordinate control of the drive control system and reliable operation of the converter, expands the scope of the asynchronous drive, reduces the cost, size, weight of the motor and drive as a whole, saves materials, resources and energy consumed by the drive.

Information sources

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3. Patent for invention No. 2313894 MPK8 Н02Р 21/12, 27/08 Frequency-controlled asynchronous electric drive. Sidorov P.G., Aleksandrov E.V., Lagun V.V., priority of the invention 06/19/2006, prototype.

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Claims (6)

1. Frequency-controlled asynchronous electric drive, comprising a power unit with a series voltage rectifier connected to it, a smoothing filter with a voltage sensor, a voltage inverter, the control inputs of which are connected to the outputs of the vector PWM unit, an asynchronous electric motor, the windings of which are connected through a phase sensor block currents to the output of the voltage inverter, and the output shaft to the speed sensor of its rotor and to the transmission mechanism, the setpoint of the current angular velocity electrode the drive, the motor flux linkage adjuster, a speed controller connected in series to the second input of which the output of the rotor speed sensor is connected, and a first division unit, active and reactive current regulators, a coordinate voltage converter, the outputs of which are connected to the inputs of the vector PWM block, coordinate current converter connected by inputs to the outputs of the block of phase current sensors, and outputs with a second input of the reactive current regulator and with the first input of the active regulator current, an observation unit of the state of the electric drive, equipped with the first and second scale amplifiers, an aperiodic link, a divider, a first integrator and a first adder, while the output of the first scale amplifier is connected to the first input of the divider, the output of which through the first integrator is connected to the first input of the first adder, to the second input of which the output of the second large-scale amplifier is connected, the output of the first adder is connected to one of the inputs of the vector PWM block, to the input of the coordinate current transformer, and to the input of the coordinate voltage converter, the output of the aperiodic link is connected to the second input of the divider and the second input of the first division unit, and the rotor speed sensor of the electric motor rotor is made in the form of a pulse sensor with two outputs, the first of which is the output of the angular position of the electric motor rotor, and the second is the speed output rotation of the rotor of the electric motor, while the first output of the pulse sensor is connected to the input of the second large-scale amplifier, characterized in that a follower is introduced into it connected the first functional converter, the first and second input of which are connected respectively to the output of the flux linkage master and the second output of the pulse sensor, the first multiplier, the flux linkage regulator, the second input of which is connected to the output of the aperiodic link, and the first restriction block, the output of which is connected to the first input of the regulator reactive current and the input of the aperiodic link, the second functional converter, the output of which is connected to the second input of the first multiplier, is followed the second adder connected to the input of the reactive current regulator and the second adder, the third adder connected to the input of which the active current regulator is connected, and the third adder, the voltage limiting unit, to the first and second inputs of which the second and the third adders, the outputs of the voltage limiting unit are connected to the inputs of the coordinate voltage transformer, the correction unit, the first, second, third and fourth inputs of which are connected to respectively, to the first and second outputs of the coordinate current transformer, to the second output of the pulse sensor and the output of the aperiodic link, and the first and second outputs, respectively, to the second inputs of the second and third adders, the first relay element is connected in series, the input of which is connected to the output of the flux linkage adjuster, and logical adder, the second relay element, the input of which is connected to the output of the aperiodic link, and the output to the second input of the logical adder, connected in series OP, the input of which is connected to the output of the current angular velocity adjuster, and the intensity adjuster, the output of which is connected to the first input of the motor speed controller, as well as the fourth limiting unit, whose input is connected to the output of the first division unit, and the output - to the second input of the active regulator current and the input of the first large-scale amplifier, while the control input of the switch is connected to the output of the logical adder. 2. The drive according to claim 1, characterized in that the first functional converter comprises a third scale amplifier, a second division unit and a module unit connected in series, the first and second inputs of the functional converter being the input of the third scale amplifier and the second input of the second division unit, respectively, and output - the output of the module block. 3. The electric drive according to claim 1, characterized in that the second functional converter comprises series-connected rise time adjuster and a second integrator, as well as a non-linear element, the input and output of which are connected respectively to the output and second input of the second integrator, the output of the second functional converter is an output second integrator. 4. The drive according to claim 1, characterized in that the correction unit comprises a fourth scale amplifier, a differentiator and a fourth adder connected in series, a fifth scale amplifier and a second multiplier connected in series, the output of which is connected to the second input of the fourth adder, and a sixth scale amplifier connected in series the third multiplier and the fifth adder, as well as the seventh scale amplifier, while the input of the fourth scale amplifier is simultaneously connected to the second inputs of the second of the third and third multipliers and the seventh adder, the first input of the correction block is the input of the fifth scale amplifier, the second input is the input of the sixth scale amplifier, the third input is the input of the fourth scale amplifier, the fourth input is the first input of the seventh scale amplifier, and the first and second output, respectively output of the fourth and fifth adders. 5. The drive according to claim 1, characterized in that the correction unit provides compensation for the effect of cross-linking on the processes occurring in the torque circuit of the drive in accordance with the expressions:

where ψ _r is the flux linkage module of the rotor;
L _s , L _r , L _m - phase inductance of the stator, rotor, mutual;

- scattering coefficient;
I _d , I _q - projection of the stator voltage and current vectors on the d and q axes;
ω _ψ is the rotation frequency of the rotor flux linkage vector; 6. The drive according to claim 1, characterized in that the maximum value of the reference active current generated in the fourth limiting unit is determined in accordance with the expression

where K _m - coefficient of overload at the moment;
I _s , I _d - nominal values of stator current vectors and active current.

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