RU2068614C1 - Electric drive system - Google Patents

Abstract

FIELD: automated electric drives using thyristor and transistor power amplifiers. SUBSTANCE: electric drive system with DC motor has main speed control circuit, relay current feedback implemented by nonlinear element of DEAD ZONE type, and mean current square feedback using second F(i)=i²signi function nonlinear, element, averaging filter, and multiplier. EFFECT: reduced energy loss, improved reliability in comprehensive range of speed and load variations. 7 dwg

Description

 The invention relates to electrical automation and is intended for use in automated electric drives with thyristor and transistor power amplifiers.

 Known electric drive systems containing a DC motor, master and speed sensor, the outputs of which are connected respectively to the summing and subtracting inputs of the comparison element, the output of which is connected to the input of the speed controller, the current sensor of the armature winding of the motor, current controller, one input of which is connected to the output of the controller speed, the second input through a non-linear element is connected to the output of the current sensor, and the output through the power amplifier is connected to the motor armature (A.S. USSR N 653708, MKI H 02 P 5/06 Publishing date 25.03.76, BI, N 11; A.S. USSR N 1108592, MKI H 02 P 5/06. Publishing 08.15.84. BI N 30; Linear amplifiers semiconductor UPL-1 series. Technical description and instruction Operating Instructions. 2 AE.380.166 TO).

 Known technical solutions belong to the class of adjustable electric drives with subordinate coordinate control, in particular, to speed control systems with a subordinate current control loop. In such systems, with a simple technical implementation, a high quality of speed regulation and current limitation in transient conditions are achieved. However, the energy losses in the armature winding in such electric drive systems are not controlled and in transient processes can reach large values, which reduces the reliability of the motors. It should be noted that in an electric drive, energy losses are proportional to the square of the current, and the electromagnetic moment to the instantaneous value of the current. When using thyristor or transistor power amplifiers, the armature current of the motor contains a variable component, the value of which changes with changes in the operating modes of the electric drive system (Perelmuter V.M. Sidorenko V.A. Control systems of thyristor electric direct current drives. M. Energoatomizdat, 1988, p. 304 ) In addition, with changes in ambient temperature, the restrictions on the effective current and the motor torque change in different ways. So, with decreasing temperature, the strength of the metal structures that make up the object of regulation of the electric drive decreases. Therefore, a reduction in the current limit setting is required. The engine cooling conditions, on the contrary, improves with decreasing temperature. Therefore, large rms currents are permissible. Satisfying the conflicting requirements for the correction of the effective current and torque with temperature changes using one current feedback in known systems is impossible.

 Therefore, the disadvantage of the known drive systems is low reliability.

усилитель мощности, выход которого подключен к якорной обмотке электродвигателя, датчик тока, включенный последовательно с якорной обмоткой двигателя, усредняющий фильтр и блок перемножения, коммутатор, первый и второй информационные входы которого подключены к выходам соответственно датчика тока и блока перемножения, управляющий вход соединен с выходом элемента ИЛИ, а выход подключен к второму входу регулятора тока, первый вход которого подключен к выходу регулятора скорости, а выход подключен к входу усилителя мощности, первый вход элемента ИЛИ подключен к выходу нелинейного элемента, а второй вход через последовательно соединенные усредняющий фильтр и пороговый элемент подключен к выходу блока перемножения, первый вход которого подключен к выходу датчика тока, а второй вход через блок выделения модуля подключен к выходу датчика напряжения, соединенного параллельно с якорной обмоткой электродвигателя [патент РФ по заявке N 5013528/07 от 8.10.91, положит.реш. от 6.04.92, МКИ H 02 P 5/06 N 2001498, 1993,(37)]
Известная система электропривода содержит два контура регулирования: главный, образованный регулятором скорости и датчиком скорости, и внутренний подчиненный, который в зависимости от режима работы электропривода выполняет подчиненное регулирование тока или мощности. В установившихся режимах, при малых ошибках регулирования скорости и при отсутствии перегрузок по мощности в подчиненном контуре действует отрицательная обратная связь по току, благодаря чему обеспечивается постоянство статических характеристик системы. В динамических режимах при больших изменениях ошибки регулирования скорости и при перегрузках во внутреннем контуре действует отрицательная обратная связь по мощности, благодаря чему минимизируется мощность, потребляемая электродвигателем.Of the known devices, the closest to the achieved result to the proposed technical solution is an electric drive system containing a DC motor, a speed sensor and a sensor, the outputs of which are connected respectively to the summing and subtracting inputs of the comparison element, the output of which is connected to the combined inputs of the speed controller and relay element with characteristic

a power amplifier, the output of which is connected to the armature winding of the electric motor, a current sensor connected in series with the armature winding of the motor, an averaging filter and a multiplication unit, a switch, the first and second information inputs of which are connected to the outputs of the current sensor and the multiplication unit, the control input is connected to the output OR element, and the output is connected to the second input of the current regulator, the first input of which is connected to the output of the speed controller, and the output is connected to the input of the power amplifier, the first input OR element is connected to the output of a nonlinear element, and the second input is connected through a series-connected averaging filter and a threshold element to the output of the multiplication unit, the first input of which is connected to the output of the current sensor, and the second input, through the module selection unit, is connected to the output of the voltage sensor connected in parallel with Anchor winding of the electric motor [RF patent on the application N 5013528/07 from 8.10.91, posit.res. from 6.04.92, MKI H 02 P 5/06 N 2001498, 1993, (37)]
The known electric drive system contains two control loops: a main one, formed by a speed controller and a speed sensor, and an internal subordinate, which, depending on the operating mode of the electric drive, performs subordinate current or power regulation. In steady-state conditions, with small errors in speed control and in the absence of power overloads in the slave circuit, negative current feedback acts, which ensures the constancy of the static characteristics of the system. In dynamic modes, with large changes in the speed control errors and during overloads in the internal circuit, negative power feedback acts, thereby minimizing the power consumed by the electric motor.

 The disadvantage of such an electric drive system is the low reliability of the electric motor with a wide range of changes in speeds and loads. This is due to the fact that during the operation of the system there is no simultaneous control of losses in the armature winding of the motor and electromagnetic moment. The energy loss in the armature winding is proportional to the square of the current, and the electromagnetic moment to the instantaneous value of the current. When using thyristor or transistor power amplifiers, the armature current of the motor contains a variable component, the value of which changes with changes in the operating modes of the electric drive system. In addition, with changes in ambient temperature, the restrictions on the effective current and the motor torque change in different ways. So, with a decrease in temperature, large currents are allowed, but lower maximum torque values.

 Therefore, the disadvantage of the known electric drive system is the low reliability of the electric motor with a wide range of changes in speeds and loads.

 The purpose of the proposed invention is to increase reliability by reducing energy loss and limiting current.

усилитель мощности, выход которого подключен к якорной обмотке электродвигателя, датчик тока, включенный последовательно с якорной обмоткой двигателя, усредняющий фильтр и блок перемножения, введены первый нелинейный элемент типа "зона нечувствительности" и второй нелинейный элемент с характеристикой F(i) i²sign i, включенный между выходом датчика тока и входом усредняющего фильтра, выход которого подключен к первому входу блока перемножения, второй вход которого соединен с выходом релейного элемента, а выход соединен с первым вычитающим входом усилителя мощности, второй вычитающий вход которого подключены через нелинейный элемент типа "зона нечувствительности" к выходу датчика тока, а суммирующий вход подключен к выходу регулятора скорости.This goal is achieved by the fact that in the known electric drive system containing a DC motor, a master and a speed sensor, the outputs of which are connected respectively to the summing and subtracting inputs of the comparison element, the output of which is connected to the combined inputs of the speed controller and relay element with characteristic

a power amplifier, the output of which is connected to the armature winding of the electric motor, a current sensor connected in series with the armature winding of the motor, an averaging filter and a multiplication unit, the first nonlinear element of the type "dead zone" and the second nonlinear element with the characteristic F (i) i ² sign i connected between the output of the current sensor and the input of the averaging filter, the output of which is connected to the first input of the multiplication unit, the second input of which is connected to the output of the relay element, and the output is connected to the first subtracting swing of the power amplifier, a second subtracting input of which is connected via a nonlinear element such as "dead band" to the output of the current sensor and the summing input connected to the output of the speed regulator.

Compared with the closest similar solution, the claimed technical solution has the following distinctive features:
the first non-linear element of the type "dead zone";
the second nonlinear element with characteristic F (i) i ² sign i.

 Therefore, the claimed technical solution meets the requirement of "novelty."

When implementing the invention, the reliability of the electrical wire system is improved by reducing energy losses in the armature winding and limiting the current. In steady-state modes, with a small control error (for example, less than 5%), only one speed controller acts in the system, which ensures high speed and accuracy of speed stabilization. If the error increases, for example, when the driving or disturbing influence changes, negative feedback on the square of the current is included in the system, due to which the losses in the armature winding are minimized in the transient process. If the current exceeds the permissible value, negative current feedback is activated in the electric drive system, which limits the current and, therefore, the torque. As a result, the following are provided in the electric drive system:
high precision speed control in steady state;
high speed;
low energy losses in the armature winding in transient conditions;
fast current and torque limitation.

 This increases the reliability of the drive system.

 Therefore, the claimed technical solution meets the requirement of "positive effect".

 For each distinguishing feature, a search is made for known technical solutions in the field of electric automation and automated electric drive.

 Nonlinear elements of the "dead zone" type are known in electric drive systems (Basharin A. V. Novikov, V. A. Sokolovsky, G. Electric Drive Control. L. Energoizdat, 1982, pp. 74-77, Fig. 2-19). In the known and proposed technical solutions, these elements perform similar functions of current limiting in transient conditions.

Nonlinear elements with characteristic F (i) i ² sign i have not been found in known devices of a similar purpose.

 Therefore, the claimed technical solution meets the requirement of "significant differences".

The essence of the alleged invention is illustrated in FIG. 1-7. Figure 1 shows the functional diagram of the electric drive system, which contains: speed controller 1, comparison element 2, relay element 3, speed controller 4, multiplication unit 5, averaging filter 6, power amplifier 7, the first non-linear element of the type "dead zone" 8 , the second non-linear element with characteristic F (i) i ² sign i 9, DC motor 10, current sensor 11, speed sensor 12.

 In the electric drive system, the master 1 and the speed sensor 12 are connected respectively to the summing and subtracting inputs of the comparison element 2, the output of which is connected to the combined inputs of the relay element 3 and the speed controller 4, the output of which is connected to the summing input of the power amplifier 7, the first subtracting input of which is connected to the output of the multiplication unit 5, the second subtractive input through the first non-linear element 8 is connected to the output of the current sensor 11, and the output is connected to the armature winding of the electric motor 10, in series with The switcher includes a current sensor 11, the output of which is connected through a second nonlinear element 9 and an averaging filter 6 connected in series to one of the inputs of the multiplication unit 5.

где K₈ коэффициент передачи первого нелинейного элемента 8;
I_o максимально допустимое значение тока.The electric drive system operates as follows. The armature winding of the electric motor 10 is connected to the output of the power amplifier 7. The motor speed Ω is regulated by changing the voltage across the armature winding. The speed of the engine 10 is measured using a speed sensor 12, for example, a tachogenerator. The current of the motor 10 is measured using a current sensor 11, for example, a shunt. The signal U ₁₁ , proportional to the current i of the motor armature winding, is fed to the inputs of the first 8 and second 9 non-linear elements. A signal is generated at the output of the first 8 non-linear element of the type "dead zone"

where K _{8 is} the transmission coefficient of the first nonlinear element 8;
I _{o the} maximum permissible current value.

The output signal of the second nonlinear element
U ₉ = K ₉ U $\genfrac{}{}{0ex}{}{\text{2}}{\text{eleven}}$ signU ₁₁ = K ₉ K $\genfrac{}{}{0ex}{}{\text{2}}{\text{eleven}}$ i ² signi,
where K _{9 is} the transmission coefficient of the second nonlinear element 9;
K ₁₁ gear ratio of the current sensor 11.

где K₆ коэффициент передачи усредняющего фильтра 6;

среднее значение квадрата тока якорной обмотки.The signal U _{9 is} proportional to the power loss in the armature winding P _p r _i i ² , where r _{i is the} resistance of the armature circuit. This signal is fed to the input of the averaging filter 6, which selects the average value of the signal U ₉ proportional to the average value of the square of the current

where K ₆ the transmission coefficient of the averaging filter 6;

average value of the square of the current of the armature winding.

The signal U ₁ proportional to the required value of the adjustable speed is supplied to the summing input of the comparison element 2. The subtracting input of the comparison element receives a signal U ₁₂ from the output of the speed sensor 12, which is proportional to the rotation speed Ω of the armature of the engine 10. In the comparison element 2, the regulation error e U ₁ - U ₁₂ is calculated. The signal U ₂ from the output of the comparison element 2 is fed to the input of the speed controller 4 and is converted by it in accordance with the standard law of regulation, for example, PI-.

где U_e напряжение, соответствующее уровню логической единицы;
ε_o заданное напряжение переключения релейного элемента 3.The signal U ₂ from the output of the comparison element is fed to the input of the relay element 3, the output of which is formed voltage

where U _{e is the} voltage corresponding to the level of a logical unit;
ε _{o the} set switching voltage of the relay element 3.

Сигналы U₅ и U₈ с выходов блока перемножения 5 и первого нелинейного элемента типа "зона нечувствительности" 8 поступают соответственно на первый и второй вычитающие входы усилителя мощности 7.The signal U ₃ from the output of the relay element 3 is fed to the input of the multiplication unit 5, at the other input of which there is a voltage U ₅ proportional to the average square of the current of the armature winding of the electric motor 10. As a result, a signal is generated at the output of the multiplication unit 5

The signals U ₅ and U ₈ from the outputs of the multiplication unit 5 and the first non-linear element of the type "dead zone" 8 are received respectively at the first and second subtracting inputs of the power amplifier 7.

и ток двигателя на превышает значения I_o, заданного уставкой первого нелинейного элемента 8, то выходные сигналы блока перемножения 5 и первого нелинейного элемента 8 U₅ 0 и U₈ 0. В этом случае в системе электропривода действует только одна отрицательная обратная связь по скорости. При использовании ПИ-регулятора скорости 4 система является астатической как по задающему, так и возмущающему воздействиям. Следовательно, в электроприводе обеспечивается высокая точность стабилизации скорости в установившихся режимах и высокое быстродействие при отработке малых отклонений скорости.If the system error in speed does not exceed a predetermined value ε _o , i.e.

and the motor current does not exceed the value of I _o specified by the setting of the first nonlinear element 8, then the output signals of the multiplication unit 5 and the first nonlinear element 8 U ₅ 0 and U ₈ 0. In this case, only one negative speed feedback acts in the electric drive system. When using the PI-controller of speed 4, the system is astatic both in terms of driving and disturbing influences. Consequently, the electric drive provides high accuracy of speed stabilization in steady-state conditions and high speed when practicing small speed deviations.

In dynamic modes, when the reference signal or mechanical load changes, the control error ε changes. If the error exceeds the value of e _o , the relay element 3 switches, and the signal from the output of the multiplier 5, proportional to the average square of the current of the armature winding of the motor 10, is fed to the first subtracting input of the power amplifier 7. As a result, the internal negative feedback acts in the electric drive system according to the average square of the current, due to which the losses in the armature winding are minimized during transient conditions.

If the current i of the armature winding of the motor 10 exceeds the value of I _o corresponding to the maximum allowable moment and specified by the setting of the first nonlinear element 8, the output signal of this element U ₈ acts on the second subtracting input of the power amplifier 7. As a result, the motor current is limited at a given level I _o .

 Thus, the proposed electric drive system contains three circuits: the main one, formed by the speed controller 4 and the speed sensor 12, and two internal subordinates: current and mean square current. The main control loop provides high precision speed stabilization in steady state. The slave control loop of the average square of the current is switched on in transient conditions and minimizes losses in the armature winding of the motor. An internal loop with non-linear current feedback provides current and, therefore, motor torque limitation at a given level.

 Therefore, in the proposed electric drive system, the reliability of the electric motor is improved by reducing energy losses in the armature winding and limiting the current in transient conditions. Another important advantage of the proposed electric drive system is the independent setting of restrictions on the moment and losses in the armature winding of the motor.

In order to confirm the positive effect achieved in the proposed technical solution, a simulation of the electric drive system was carried out using an IBM-PC / AT computer. We studied a system with the following parameter values:
active resistance of the armature winding of the motor r 1 Ohm;
motor inductance inductance L 0.01 G;
the moment of inertia of the mechanical load, reduced to the motor shaft I, 0.1 kg / m ² ;
engine design constant C 1 V s / rad;
coefficient of transmission of the speed sensor K ₁₂ 1 V s / rad;
coefficient of transfer of a current sensor K ₁₁ 1 B / A;
the transmission coefficient of the second nonlinear element K ₉ 1 B ^-1 ;
transmission coefficient of the averaging filter K ₆ 1;
averaging filter time constant T ₆ 0.01 s;
parameters of the relay element 3: U _e 1; ε _o 0.01 B;
the transmission coefficient of the multiplication block K ₅ 2;
parameters of the PI speed controller K ₄ 0.25; T ₄ 0.1 s;
transmission coefficient of the power amplifier K ₇ 10;
the parameters of the first nonlinear element 8: I _o 5 A; K ₈ 20.

 In FIG. Figures 2-7 show the simulation results. FIG. 2 shows a transient diagram for the speed Ω in a system without current feedback, FIG. 3 is a process diagram for speed in a system with a slave circuit, power control (prototype), and FIG. 4 is a diagram for speed in the proposed system. Similar diagrams for currents are shown in FIG. 5-7 respectively. The above results indicate an improvement in dynamic and energy characteristics in the proposed electric drive system compared to the prototype and other similar devices. The energy loss in the armature winding of the motor in the proposed system compared with the prototype is reduced by 30% and compared with a system without current feedback by 80%, the efficiency of the system increases by 6% compared with the prototype and by 30% compared with the system without current feedback.

 Therefore, in the proposed electric drive system, in comparison with the known, provides increased reliability of the engine by reducing losses in the armature winding and limiting in transient conditions.

 Using the proposed technical solution in an automated electric drive will improve the technical characteristics and reliability of electrical equipment and reduce energy loss. YYY6

Claims (1)

An electric drive system comprising a DC motor, a master and a speed sensor, the outputs of which are connected respectively to the summing and subtracting inputs of the comparison element, the output of which is connected to the combined inputs of the speed controller and relay element with the characteristic:

a power amplifier, the output of which is connected to the armature winding of the electric motor, a current sensor connected in series with the armature winding of the motor, an averaging filter and a multiplication unit, characterized in that the first non-linear element of the type "sensitivity zone" and the second non-linear element with characteristic f (i) i ² signi, connected between the output of the current sensor and the input of the averaging filter, whose output is connected to the first input of the multiplication unit, a second input coupled to an output relay element And an output connected to a first subtractor input of the power amplifier, a second subtracting input of which is connected via a first non-linear element such as "dead band" to the output of the current sensor and the summing input connected to the output of the speed controller,
where ε is the regulation error,
U _e voltage corresponding to the level of a logical unit,
e _o predetermined switching voltage of the relay element,
i current of the armature winding of the motor.

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