RU2322747C2 - Electric driver for producing of torque abd its control system - Google Patents

Abstract

FIELD: electrical engineering, applicable for imparting of a precision turn, rotary and oscillatory motions to various mechanisms within a wide range of angles and angular velocities.

SUBSTANCE: the electric drive has a step motor, whose shaft is coupled to the electric drive output shaft through a reduction gear. An additional motor is kinematically linked with the output shaft of the electric drive by a belt transmission, and the torque developed by it on the output shaft exceeds the friction torque on the output shaft, but it doesn't exceed the torque on the output shaft from the step motor. The electric drive control system has a DC voltage source, step motor with a stop motor control unit, additional motor with a selector switch of the direction of its rotation. The step motor control unit is provided with control outputs, and its input is connected to the DC voltage source. The additional motor is connected to an additional supply source via the selector switch of the direction of its rotation, and its control inputs are connected to the control outputs of the step motor.

EFFECT: expanded dynamic range of rotary speeds of the output shaft, enhanced reliability, precision of the rotary speed and provided a turn of the output shaft through the preset angle.

2 cl, 4 dwg

Description

The invention relates to mechanical engineering and can be used to communicate precision rotational or oscillatory motion to various mechanisms, both during their regular use, and when testing measuring angle sensors, angular velocities, linear (centrifugal) accelerations, during testing and operation of mechanisms used in folk household, in simulators, etc.

Known electric drive to create torque, containing placed in the housing a multi-stage planetary gearbox with sequential arrangement of stages, the output shaft in the form of a gear wheel connected to the carrier of the previous stage, satellites, drive element, etc. [1].

To control the electric drive, if it is made on DC motors, in the simplest case, a DC power source with a given output voltage and, if necessary, a rheostat [2] or another device for controlling the voltage of the electric motor, for example, a device with pulse-width modulation, are used. To control an AC electric motor, by analogy, an adjustable autotransformer can be used.

The disadvantage of such electric drives for creating torque is the low efficiency, low accuracy of the rotation speed of the output shaft of the device, the inability to provide rotation of the output shaft by a given angle, to set the oscillatory motion.

From the point of view of controlling the electric drive, direct connection through a rheostat allows you to adjust the speed of rotation of the electric motor, but significantly reduces the efficiency of the device, cannot provide the specified accuracy of the speed of rotation of the output shaft of the device, and cannot provide rotation by a given angle. When you turn on the AC motor through an autotransformer, the efficiency drops slightly, but it is impossible to provide the specified rotation parameters of the output shaft of the device.

The electric drive is known according to the patent of the Russian Federation No. 2002361, Н02Р 8/00 [3], which contains signs that make it possible to take it as a prototype for an electric drive to create a torque, and for its control system. Of the total number of features of the known device, the essential (and common) from the point of view of the proposed device are the following.

The electric drive for generating torque contains a stepper motor connected to the output shaft of the electric drive through the gearbox, a second (additional) motor kinematically connected to the output shaft.

Its control system contains a power source (assumed by default), a stepper motor, a second (optional) electric motor (in this case, direct current), a stepper motor control unit (general purpose of interconnected functional units) and a rotation direction switch (functionally these are certain signs prototype), connected to the output of the second electric motor, while the outputs of the control unit of the stepper motor are connected to the windings of the stepper motor.

The disadvantage of the prototype device is the low accuracy of the output shaft rotation speed even when using a stepper motor. This is due to the following. At low speeds of rotation of the output shaft of the device (when the second motor is off), the moment created by the stepper motor is transmitted through the differential to the second motor, which can rotate from this moment. As a result of this, due to the subtraction of the velocities in the differential, the rotation speed of the output shaft will not correspond to the set one. When operating at maximum rotational speeds, when the second electric motor enters the work, the rotational speeds of the device add up the rotational speeds of the two motors. Since the rotational speed of the second motor has low accuracy, the rotational speeds of the output shaft cannot have high accuracy. Thus, these disadvantages of the drive do not allow its use in precision devices and in devices that provide rotation by a given angle or precision oscillatory mode. Moreover, the features of the stepper motor, as such (low throttle response, loss of synchronism [4]), determine a significant drawback of the device in which it is installed, namely, a decrease in its functional reliability.

The objectives of the proposed technical solution are to expand the dynamic range of speeds of rotation of the output shaft of the electric drive in the mode of acceleration, increase the functional reliability, ensure precision accuracy of the speed of rotation, provide the ability to rotate the output shaft of the drive to a predetermined angle and oscillatory operation (such as pendulum). In addition, the proposal achieves a simplification of the design of the device.

The technical result is achieved in that in the electric drive to create a torque containing a stepper motor, the output shaft of which is connected through a gearbox to the output shaft of the electric drive, and an additional electric motor kinematically connected to the output shaft of the electric drive, the kinematic connection of the additional electric motor to the output shaft of the electric drive is made using a belt drive comprising a belt enclosing a driving and driven pulleys located respectively on an output shaft the additional electric motor and on the output shaft of the electric drive or on the output shaft of the stepper motor, while the torque developed by the additional electric motor on the output shaft of the electric drive is greater than the friction moment on the output shaft of the electric drive, but does not exceed the torque on the output shaft of the electric drive from the stepper motor.

An electric drive control system for generating a torque, comprising a constant voltage power supply, a stepper motor and a stepper motor control unit, connected to the outputs of the stepper motor windings, an additional electric motor and an additional electric motor rotation direction switch, an additional power source is introduced, the input of the stepper motor control unit is connected with constant voltage power supply, additional electric motor through rotation direction switch is connected to an additional power supply, the stepper motor control unit is provided with control outputs, an additional motor rotation direction switch is provided with control inputs which are connected to stepper motor control outputs of the control unit.

The essence of the invention is illustrated using graphic materials of figure 1 and figure 2, which shows the functional (kinematic) block diagrams of the proposed electric drive to create a torque. The drawings show only the principal components of the device and do not show the supports, stops, bearings, gears, etc., since their execution can be any, and they are not the subject of this invention. The presented devices are essentially equivalent to each other. Figures 3 and 4 show block diagrams of the electric motor control system of the electric drive of the invention, differing in types and characteristics of the additional electric motor, additional power supply and the design of the rotation direction switch of the additional motor, which are also essentially equivalent to each other.

The numbers in the drawings indicate:

1 - step electric motor;

2 - gear;

3 - output shaft of the electric drive;

4 - additional electric motor;

5 - a leading pulley;

6 - driven pulley;

7 - belt transmission belt;

8 - rotary platform;

9 - power supply unit of a stepper motor;

10 - control unit stepper motor;

11 - unit for setting the operating modes of the stepper motor;

12 - switch windings of a stepper motor;

13 - windings of a stepper motor;

14 - additional power supply;

15 - switch of direction of rotation of the additional electric motor 4.

The electric drive to create a torque (Fig. 1 and Fig. 2) consists of a stepper motor 1 connected by means of a reducer 2 to the output shaft 3 of the electric drive, and an additional electric motor 4, the drive pulley 5 of which is connected to the driven pulley using a belt 7 of a belt drive 6 electric drives. In this case, the driven pulley 6 can be installed directly on the output shaft 3 of the electric drive (Fig. 1) or on the output shaft of the stepper motor 1 (Fig. 2). On the output shaft 3 of the electric drive can be installed any mechanism that requires rotation (rotation) according to a given law (at a given angle), or a rotary platform 8, on which the tested equipment can be placed. Reducer 2, depending on the technical characteristics of the electric drive, can be multi-stage.

The control units 10 (Fig. 3 and Fig. 4) of stepper motors are shown conditionally divided into two independent units 11 and 12 only in order to make it easier to consider the operation of the proposed devices as a whole. In reality, they can be performed in any way using semiconductor devices, microcircuits, controllers, computers, etc., including in the form of a monoblock. The control unit of the stepper motor 10 is equipped with control outputs, the direction switch of rotation of the additional electric motor 15 is equipped with control inputs that are connected to the control outputs of the control unit of the stepper motor.

The power to the windings of the stepper motor (Fig. 3, Fig. 4) is supplied from the power supply unit of the stepper motor 9 through the control unit of the stepper motor 10 (from the output of the switch windings of the stepper motor 12). The management of this switch is carried out using the pulse signals of the unit for setting the operation modes of the stepper motor 11. The power to the additional motor 4 is supplied from the additional power supply 14 through the rotation direction switch of the additional electric motor 15, which is controlled from the control unit of the stepper motor 10.

The requirements for the additional electric motor 4 arise from its functional purpose in the proposed device - to provide an additional moment during acceleration of the electric drive (to provide an increase in the throttle response of the device), to compensate the rotational moment of friction at high rotational speeds (increase the dynamic range of rotational speeds) and do not affect the formation of the specified rotation speed by a stepper motor. For this, its maximum torque reduced to the output shaft of the device should not exceed the torque of the stepper motor also brought to the output shaft of the device. In the control system of Fig. 3, this is ensured by the fact that at start-up and low speeds of rotation of the electric motor 4, due to its large current consumption, the output voltage of the additional power supply unit 14 sharply decreases, and thus the power and starting moment of the additional electric motor 4 decrease, although its maximum starting moment at a rated supply voltage can significantly exceed the rated starting torque of the stepper motor 1. In the control system of FIG. 4, an asynchronous electric motor a ka connected to an additional ac power supply unit 14, having a soft starting characteristic, operates in a large dynamic speed range without electrical overload (an example of a design of such an electric motor can be an electric motor of a household fan). This set of properties of an alternating voltage source and an asynchronous electric motor are equivalent to the properties of a dc voltage source with a falling characteristic and a dc voltage motor.

The belt transmission belt 7 (FIGS. 1 and 2) serves not only to transmit the moment from the additional electric motor 4 to the output shaft of the electric drive 3, but also, due to the certain viscosity of the belt transmission belt 7, to damp the resonant vibrations, the occurrence of which is inevitable in a high-quality electromechanical a system with elasticity, impulse control forces and inertial mass. The viscosity of the belt introduces attenuation into this system and vibrations do not occur.

The power supply unit of the stepper motor 9 (Fig.3, 4) is connected to the control unit of the stepper motor 10, which contains a unit for setting the operating modes of the stepper motor 11 and the switch windings of the stepper motor 12. They work together as follows. The unit for setting the operating modes of the stepper motor 11 generates a sequence of control pulses of the keys of the switch of the windings of the stepper motor 12. This switch (usually made on transistors operating in the key mode) sequentially supplies the windings 13 of the stepper motor 1 with a supply voltage.

The additional power supply 14 is connected to the additional electric motor 4 using the switch of rotation direction of the additional electric motor 15. Its controlled keys K1-K4 form four operating modes of the additional electric motor 4 (see Figs. 3 and 4): the initial one, when the power circuit of the additional electric motor is disconnected (none of the keys K1-K4 is turned on), two operating states in which the power circuits of the additional electric motor 4 are closed, and the polarity (or phase for figure 4) of its connection to the block the power supply is opposite (keys K1 and K2 or K3 and K4 are turned on), and the fourth state is when the switches, for example K2 and K4, are short-circuited by the electric circuit of the additional electric motor 4 itself, which contributes to the braking of the additional electric motor 4 and an accelerated decrease in the speed of rotation of the output shaft 3 devices.

The device operates as a whole as follows.

The voltage on the windings of the stepper motor 13 (Fig. 3 and Fig. 4) is supplied from the power supply unit of the stepper motor 9 through the control unit of the stepper motor 10 in the form of pulses in accordance with the frequency and sequence generated by the unit for setting the operating modes of the stepper motor 11 (stepper control unit an electric motor, as such, is not included in the scope of claims, therefore, it is not given in the application materials and is not considered in detail). The rotation of the rotor of the stepper motor 1 is transmitted through the gearbox 2 to the output shaft of the electric drive 3. Through the belt drive, the rotation is also transmitted to the shaft of the additional electric motor 4, and it can rotate at idle. When the auxiliary voltage 4 is supplied to the additional electric motor 4 through the closed keys of the rotation direction switch of the additional electric motor 15 (this is ensured when the electric drive operates in the entire range of moments and rotational speeds of the output shaft of the device using control signals from the control unit of the stepper motor 10 to the rotation direction switch of the additional electric motor 15), then he at the expense of his own moment through a belt drive informs the output shaft 3 of the electric drive Ode additional torque. In the simplest case, when changing the direction of rotation of the stepper motor, the control unit of the stepper motor 10 removes the control signals from the keys K1 and K2 and sets such signals on the keys K3 and K4 or vice versa. If necessary, braking an additional electric motor 4 from the control unit of the stepper motor 10 to the inputs of the switch direction of rotation of the additional electric motor 15 receives signals that open the keys K2 and K4. A specific implementation of the control circuit of the rotation direction switch of the additional electric motor 15 is not shown in the drawings, since the specific circuit is a “matter of taste” of the developer. As fairly universal control schemes, driver chips from International Rectifier can be used, the simplest of which is IR2101.

With a low speed of rotation of the output shaft 3 and the speed of rotation of the additional electric motor 4, its torque is maximum. This increases the total torque during acceleration of the electric drive and its throttle response. As the speed of rotation of the output shaft of the electric drive increases, the additional electric motor reaches the nominal mode, compensates for friction losses in the device, creates additional torque and supports the rotation of the stepper motor at its maximum possible speeds.

The variable component of the rotational speed (vibration) of the rotor and the output shaft of the device, arising due to the pulse control of the stepper motor, smooths the belt transmission of the additional motor due to the viscous and elastic properties of the belt. These properties of the belt drive (especially its viscosity) dampen resonances in the electromechanics of the device.

The rotation of the output shaft of the electric drive to a predetermined angle with a given speed, as well as the precise oscillatory mode of the output shaft 3 of the device is ensured by the formation by the control unit of the stepper motor 10 of the required number of pulses to the windings of the stepper motor with the necessary sequence and frequent switching. The control algorithm produces a unit for setting the operating modes of the stepper motor 11. In this case, simultaneously with a change in the direction of rotation of the stepper motor, the polarity (or phase) of the power supply of the additional motor 4 is changed as described above.

To reverse the direction of rotation of the induction motor (figure 4), usually having two windings, designed to create a rotating magnetic field, the switch of the direction of rotation of the additional motor 15 should switch only one of them (for example, "capacitor"), and the second can be turned on simultaneously with the inclusion of the power source 14 or an additional key (not shown in the drawing).

The simplification of the device compared to the prototype is achieved due to the fact that instead of a differential gearbox simple gears are used using gears and a belt, and even an unstabilized voltage source with maximum current limitation and without forced control, which is used in the device, can be used as an additional power source -prototype, or standard AC voltage network.

The proposed set of features in the proposal considered by the authors was not found to solve the problem and does not follow explicitly from the prior art, which allows us to conclude that the technical solution meets the criteria of "novelty" and "inventive step".

The considered electric drive to create a torque on which a platform is mounted, driven by rotation, will be used to set precise rotational movements with different angular speeds of various devices during their testing in the production process. The electric drive is currently under construction.

Literature

1. Kudryavtsev V.N. Planetary gears. - L .: 1966, p. 247-243, Fig. 133 and 134.

2. I.M. Yurovsky, N.A. Chekalin. Laboratory workshop on electric drive and control fundamentals. Second edition, revised and revised. M .: Higher school, 1972, p. 9, fig. 1.3, fig. 1.4.

3. RF patent №2002361 Н02Р 8/00, (prototype).

4. Microelectric motors for automation systems (technical reference). Ed. E.A. Lodochnikova and F.M. Yuferova. M .: Energy, 1969.

5. RF patent 2065542, IPC 6: F16H 3/44.

Claims (2)

1. An electric drive for generating torque, comprising a stepper motor, the output shaft of which is connected through a gearbox to the output shaft of the electric drive, and an additional electric motor, kinematically connected with the output shaft of the electric drive, characterized in that the kinematic connection of the additional electric motor with the output shaft of the electric drive is made using a belt a transmission containing a belt covering the driving and driven pulleys, respectively located on the output shaft of the additional electric of the motor and on the output shaft of the electric drive or on the output shaft of the stepper motor, while the torque developed by the additional electric motor on the output shaft of the electric drive is greater than the friction moment on the output shaft of the electric drive, but does not exceed the torque on the output shaft of the electric drive from the stepper motor. 2. The control system of the electric drive to create a torque, containing a constant voltage power source, a stepper motor and a stepper motor control unit, connected by outputs to the windings of the stepper motor, an additional electric motor and a direction switch of rotation of the additional electric motor, characterized in that an additional power source is introduced into it , the input of the stepper motor control unit is connected to a constant voltage power source, additional the body of the electric motor through a switch of direction of rotation is connected to an additional source, the control unit of the stepper motor is equipped with control outputs, the switch of direction of rotation of the additional motor is equipped with control inputs that are connected to the control outputs of the control unit of the stepper motor.

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