SU758447A2 - Dc electric drive with minimizing losses in motor - Google Patents

Description

The invention relates to a controlled DC electric drive and can be used in electric drives of various machines and a mechanism, for example, in electric drives of rolling mills, in ship, transport electric drives, and is ⁵ improvement of the known electric drive described in ed. No. 663052.

Mainly auto No. 663052 describes a direct current electric drive, in which by maintaining the optimal ratio between the current in the armature circuit and the excitation flux, energy losses are minimized in steady-state conditions and in transient processes. The known direct current electric drive with minimization of losses in the motor contains excitation current and armature voltage sensors, a speed sensor, a functional converter and a multiplication unit with an armature current sensor connected to its second input, as well as an excitation regulator, to the input of which is connected an integration unit with three inputs that are connected, respectively, 2 with the output of the multiplication unit, with the output of the voltage sensor at the armature and with the output of the excitation current sensor 11J.

This drive provides approximate fulfillment of the condition of minimum losses in the engine where si is the angular velocity, s * ';

Iq - current in the motor anchor circuit, A;

Cd - internal resistance of the motor anchor circuit, Ohm;

engine design coefficient;

СО - motor excitation flow, Wb; variable coefficient characterizing the dependence of steel losses on speed

AR _St ~ loss in engine steel, W;

Ιβ is the excitation current of the motor. A;

- resistance of the field winding of the motor, Ohm.

s 758447

As is known, the magnitude of the energy of losses emitted in the engine during the transition process, the process of changing the speed, significantly depends on the law by which this speed change in time occurs. The minimum energy of losses in the engine during the transition process is achieved if, at any speed and any moment of static resistance of the CD on the motor shaft, the values of the current in the armature circuit and the excitation flux of the engine (and, therefore, the moment developed by the engine) are chosen so that, under the condition (1) the following condition was simultaneously satisfied:

mechanical losses in the engine, W; moment of static resistance on the motor shaft, Nm.

If the moment of resistance Μς is a known function of speed, and the dependences & Ρμ₽.χ (α>) _; G (uj) and (cf) equation (2) implicitly determines the unambiguous dependence of the optimal excitation flux, and equation (1) determines the dependence of the optimal current in the armature circuit on the excitation flow “I opt” - I qoOT

Knowing ^ (αΛ, Οίω), dmech (ω), ΐв (ф) ^and the motor parameters according to equation (3), we can calculate the optimal value of the current that should flow in the motor armature in the transient process as a function of motor speed.

In the above-described electric drive, in the transient process, automatic selection of the armature current and the excitation flux in accordance with condition (3) is not provided, and therefore, the automatic generation of an optimal minimum energy loss diagram of the engine speed change over time is not provided.

The aim of the invention is the provision of automatic generation of an optimal minimum energy loss diagram of changes in engine speed over time with a known dependence of the resistance moment on speed.

This is achieved by the fact that in the electric drive according to ed. No. 663052, a variable speed controller of engine speed and a non-linear block designed to reproduce a smooth monotonic speed function (3), and an integration unit with two inputs with output signal limitation, the input of the non-linear block connected to the speed sensor, the second block input introduced integration - with an armature current sensor, and the integrator output is connected to the regulating input of the intensity adjuster.

This embodiment of the electric drive makes it possible in transients with a known dependence of the moment of static resistance 10 on the speed Мс (ш) to form an optimal diagram of the change in engine speed over time, which is optimal for minimizing the energy of losses.

In FIG. 1 is a structural diagram of the proposed electric drive; in FIG. 2 presents 15 relationships between the armature current and the excitation flux; in FIG. 3 - nonlinear functions reproduced by a nonlinear block with various dependencies of the resistance moment on speed.

In FIG. 1 the following designations are given: 1 - speed sensor; 2 - functional converter; 3 - block multiplication;

- an integration unit with three inputs;

- excitation regulator; 6 - current sensor 25 anchors; 7 - field current sensor; 8 - voltage sensor at anchor; 9 - adjuster of adjustable intensity of change of drive speed; 10 - integration unit with two inputs with output signal limitation; 11 is a nonlinear block.

In FIG. 2, curves 12 and 13 are the optimal ratios between the armature current and the excitation flux obtained from equation (1) at different engine speeds to minimize the losses in the motor.

Curves 14 and 15 approximate the optimal dependences (curves 12 and 13) and represent the relations between the armature current and the excitation flux, which take place ₄ θ in the proposed drive with some choice of the coefficients K ^, Kj, Ku

In FIG. 3 curves 16 and 17 represent typical velocity functions _{ί οητ} (ω)> reproduced by the non-linear block 11 for cases of a constant moment of resistance on the shaft М с-СОп <еЕ and fan moment, respectively, and obtained from expression (3).

The proposed electric drive contains, according to _J0, a speed sensor 1, a functional converter 2, a multiplication unit 3 connected by its second input to the armature current sensor 6, an integration unit 4 with three inputs connected _{55 by the} first input to the output of the multiplication unit 3, and an excitation regulator 5 , as well as a regulator of adjustable intensity of change of speed of the actuator 9 and series-connected non-linear unit 11 and the integ-.

7 10 with two inputs and with output limitation. The integration unit 4 is connected by its second input to the output of the voltage Sensor 8 at the motor armature, and its third input is connected to the excitation current sensor 7. The input of the nonlinear block And is connected to the speed sensor 1, the second input of the integration unit 10 is connected to the current sensor of the armature 6, and the output of the integration unit 10 is connected to the control input of the intensity adjuster 9.

The electric drive operates as follows.

The signal from the speed sensor 1 is fed to the input of the functional converter 2 and the non-linear block 11. The signal from the output of the non-linear block 11 is added to the input of the integrator 10 with a signal proportional to the armature current and from the armature current sensor 6. The output signal of the integration unit 10 the regulating input of the intensity adjuster 9 controls the change in drive speed in transients. The integrator 10 to prevent the accumulation of large signals at its output in static modes should be equipped with an output signal limiter. The multiplication unit 3 carries out the continuous multiplication of two signals - the armature 6 received from the current sensor and received from the functional converter 2. At the output of the multiplication unit 3, a signal is generated that comes with a plus sign and with a coefficient of K 4 to the first input of integration unit 4. To its second input with a minus sign and with a coefficient K, a signal is transmitted from the sensor 8, proportional to the voltage applied to the motor armature, and a signal proportional to the current the excitations from the sensor 7. In the proposed drive, with the appropriate choice of the coefficients K ^, K ^, K, the relations between the current in the armature circuit and the excitation flux (curves 14 and 15) are very close to optimal (curves 12 and 13) described by the condition (1) Due to the introduction of a nonlinear block 11, an integration unit 10, and an adjustable intensity adjuster 9 in transients, the intensity of the change in engine speed automatically

6 is supported such that under which condition (3) will hold: ^K 5 ~ ^ OPT (w) · Ku = θ

Thus, in the proposed drive with an appropriate choice of the coefficients K | - K £, the minimum energy loss in the engine is maintained in steady-state conditions in accordance with condition (1), as well as in transients due to the automatic formation of the optimal diagram of the change in speed while fulfilling the conditions (1) and (3).

In the proposed electric drive, as calculations show, the energy of losses released in transients is reduced by 10-20% compared with the case when the excitation flux in the transient is not. is regulated. The reduction of losses leads to a corresponding decrease in engine heating. The greatest effect can be obtained by using the proposed electric drive for mechanisms with heavy duty cycles. In this case, there may be an increase in the engine uptime, · as well as an increase in the productivity of the mechanism by 10–20% due to the better use of the drive motor for heating.

Claims (2)

The invention relates to an adjustable DC electric drive and can be used in electric drives of various machines and mechanisms, for example, in electric drives of rolling mills, in shipboard, transport electric drives, and is an improvement of the known electric drive described in the authors. No. 663052. Basically auth.St. No. 6,63052 describes a DC electric drive in which, by maintaining an optimal ratio between the current in the core circuit and the Excitation flow, energy loss is minimized in the established modes and in the transients. The known DC motor drive with minimization of losses in the motor contains excitation current and voltage sensors on the core, series-connected speed sensor, functional transducer, and multiplication unit with a sub-switch. The core sensor to its second input, as well as the excitation controller, to the input of which the integration unit is connected to three inputs, which are connected respectively to the output of the multiplication unit, to the voltage of the core sensor and sensor current stroke 1J. In this electric drive, a minimum condition of minimum is provided in the engine; -I, R ,, qH .. (, R, VO, ") tu - angular velocity, s; Ttj is the current in the engine gearbox, A; Tin is the internal resistance of the engine circuit, Ohm; - constructive engine coefficient; co - motor excitation flow, Wb; Q (IU | - Variable coefficient characterizing the dependence of losses in steel on the speed of losses in engine steel, W; 1 - engine excitation current. A; P k - resistance of the engine excitation winding. Ohm. 3.7 the motor during a transient process of varying the speed depends significantly on what law this speed changes over time. The minimum energy loss in the motor during the transient process is achieved if at any speed and any moment on the motor shaft, choose the values of the current in the crustal circuit and the motor excitation flow (and, therefore, the torque developed by the motor), so that if condition (1) is fulfilled, the following condition is also satisfied: wVt, Птгч 7 л ( 2. I 1 ™ e LRr - mechanical losses in the engine, W; moment of static resistance on the engine shaft, Nm. In case the moment of resistance J (is a known function of speed, and also known dependences РР |, drl (si), G (lc) and IQ (CP) equation (2) implicitly defines a unique dependence on the initial excitation flux, cp ,,, and equation (1) determines the dependence of the optimal current in the core circuit on the excitation flux 91opt-Jaop-rG opt1 - 0 -T opt) l3 Zna), aM DRmeg MDe (f) engine parameters by the equation (3) it is possible to calculate the optimal value of the current that must flow in the engine's crank circuit in the transient process, as a function of the motor speed. In the above-described electric drive, in the transient process, the automatic selection of the core current and the excitation flux in accordance with condition (3) is not provided, and consequently, the optimal time-loss diagram of the engine speed variation is not automatically generated. The aim of the invention is to provide an automatic generation of the optimum by the minimum loss energy energy diagram of the engine speed change over time with a known dependence of the resistance moment on the speed. This is achieved by the fact that in the electric drive according to auth.st. No. 6,63052, a variable speed drive for the motor speed and a nonlinear unit connected in series to reproduce a smooth monotonic velocity function (3), and a two-stroke integration unit with a limited output signal are entered, the input of the nonlinear unit is connected to the speed controller, the second the input of the integration unit is with the current sensor core, and the output of the integrator is connected to the regulating input of the intensity detector. Such an embodiment of the electric drive allows, in transient processes, with a known dependence of the moment of static resistance on the speed Mf (br), to form an optimal, with respect to the minimum loss energy, diagram of the change in the speed of the motor with time. FIG. 1 is given the structural scheme of the proposed electric drive; in fig. Figure 2 shows the relationship between the core current and the excitation flow; in fig. 3 - nonlinear functions reproduced by a nonlinear block with different dependences of the resistance moment on speed. FIG. 1 the following designations are given: 1 - speed sensor; 2 - functional converter; 3 - multiplication unit; 4- integration block with three inputs; 5- excitation regulator; 6 - cor current sensor; 7 — excitation current sensor; 8 — bark voltage sensor; 9 — adjuster of variable intensity of the drive speed; 10 is an integration unit with two inputs with limited output; II - nonlinear block. FIG. 2, curves 12 and 13 are optimal in terms of the minimum loss in the engine by the relations between the core current and the excitation flow, obtained from condition (1) at different engine speeds. Curves 14 and 15 approximate the optimal dependencies (curves 12 and 13) and represent the relations between the core current and the excitation flow, which take place in the proposed electric drive with a certain choice of coefficients K., K, K ,. On the fit. 3, curves 16 and 17 represent typical functions of the velocity 1p (w) reproduced by the nonlinear block 11 for cases of constant moment of resistance on the shaft M s. and fan torque, respectively, and derived from (3). The proposed electric drive contains serially connected speed sensor I, functional converter 2, multiplication unit 3 connected by its second input to current sensor cor 6, integration unit 4 with three inputs connected by the first input to the forward side of multiplier 3, and excitation regulator 5, and also a variable intensity control unit for changing the speed of the actuator 9 and the series-connected nonlinear unit 11 and the integrated unit. 5 p) Vani 10 with two inputs and with limited output. The integration unit 4 is connected by its second input to the output of the Voltage Sensor 8 on the engine bark, and its third input is connected to the excitation current sensor 7. The input of the nonlinear unit I is connected to the speed sensor 1, the second input of the integration unit 10 is connected to the current sensor cor 6, and the output of the integration unit 10 is connected to the regulating input of the intensity setter 9. The drive operates as follows. The signal from the speed sensor 1 is fed to the input of a functional converter 2 and the nonlinear block 11. The output from the nonlinear block 11 is summed up at the input of the integrator 10 with a signal proportional to the current core and coming from the current sensor cor 6. The output signal of the integrator 10 arrives at a control input of the intensity setting unit 9 controls the change in drive speed in transients. Integrator 0 to prevent large signals from accumulating at its output in static modes should be provided with an output limiter. The multiplication unit 3 continuously multiplies two signals - coming from the Cor 6 current sensor and coming from the function transducer. 2. At the output of the multiplication unit 3, a signal is generated that comes with a plus sign and a factor of K / J to the first input of the integrating unit 4. At its second input with a minus sign and with the factor K, the signal proportional to the voltage applied to sensor 8 The motor is koryu, and its third input with a minus sign and with a coefficient K receives a signal, of a proportional current to the excitation current from sensor 7. In the proposed electric drive, an appropriate choice of coefficients K, K ", Kj maintains the ratio between the current in the core circuit and the excitation flow (curves 14 and 15) are very close to optimal (curves 12 and 13) described by the condition (1 Thanks to the introduction to the electric circuit of the nonlinear unit 11, the integration unit 10 and the variable intensity control unit 9 in transients of the engine speed change automatically automatically such that the condition (3) -s-onTM-i y O will be fulfilled (4) Thus, in the proposed electric drive, with an appropriate choice of the coefficients Ki-K c, the minimum loss energy in the engine in stanovivshihs modes in accordance with the condition (1), as well as transients by automatically generating optimum chart speed variations when both of the conditions (1) and (3). In the proposed electric drive, as shown by calculations, the energy of losses occurring in transients is reduced by 10-20% compared with the case when the excitation flow in the transient process is not. is regulated. Reducing losses leads to a corresponding decrease in engine heating. The greatest effect can be obtained by using the proposed electric drive for mechanisms with heavy duty cycles. In this case, there may be an increase in the engine uptime, as well as an increase in the productivity of the mechanism by 10–20% due to better use of the drive engine in heating. Claims of the invention Electric current of direct current with minimization of engine losses according to auth.St. And 6,63052, characterized in that, in order to automatically form the optimal for the minimum loss energy of the diagrams; engine speed changes with a known dependence of the moment of static resistance on speed, a variable intensity engine speed adjuster and a serially connected nonlinear unit and two-input integration unit with limited output signal are entered into it, the nonlinear unit input is connected to the speed sensor, the second input the integration unit with the current sensor core, and the output of the integration unit is connected to the regulating input of the intensity setter. Sources of information accepted in the examination during the examination 1. USSR author's certificate No. 663052, cl. And 02 P 5/06, 1977.