SU928575A1 - Dc electric drive - Google Patents

Description

The invention relates to electrical engineering, in particular, to systems for synchronizing the speed of direct current electric motors. A known DC motor contains a motor connected to a power switch with modulating and reversing inputs, a motor speed sensor connected to the input of a frequency-phase discriminator, the second input of which is connected to the source of the master frequency, and the output through a filter to the input of the threshold device. The disadvantage of the electric drive is a limited synchronization range, especially in the area of low motor speeds. The closest to the invention to the technical essence is a DC electric drive containing a motor connected to the output of the power switch, a motor speed sensor connected to the input of the frequency-phase discriminator whose second input is connected to the output of the master frequency generator, and the output through The Ailter has an inverter input, two threshold devices, the outputs of which are connected to 5, respectively, to the input and output of the inverter, and the outputs to the inputs of the OR circuit and a trigger connected to the right upstream with the reversing input of the power switch, and the direction of rotation of the electric motor. The possibility of changing in this electric drive not only the magnitudes but also the sign of the electromagnetic moment provides stability of regulation, at all rotational frequencies, including low, down to zero, which ensures a wide range of frequency regulation. In addition, it is possible to control when the alternating active load moment in the whole range of rotational frequencies 2. The disadvantage of this electric drive is that counterinclusion at high rotational frequencies leads to an excessively large torus moment, the value of which depends on the sum of the supply voltage and the EMF of an electric motor, which, in turn, causes a delay in transients and even self-oscillations in this case — phase. These phase self-oscillations cause instability of the instantaneous frequency of rotation, which reduces the quality of regulation. This occurs at medium rotational frequencies at low moments of the | Load, and especially at idle speed, when the operating point is close to neutral and Phase fluctuations lead to opposition. A disadvantage of the known electric drive is the insufficiently high quality of regulation at medium rotational speeds at low loading torques. The purpose of the present invention is to improve the quality of regulation. The goal is achieved by the fact that two logic blocks are added to the drive, the first of which contains a frequency converter for pulse duration, and two-input logic circuits AND-NOT and AND, and the second is NOT the circuit, the second and the third two-input circuit AND and OR circuit, with the first input of the converter connected to the additional output of the source of the master frequency, the second input of the converter to the output of the main circuit OR and the first input of the first with And connecting the output with the modulating input of the power switch, the converter output is connected to the first input of the NAND circuit, the output of which is connected to the second input of the first AND circuit, and the second input to the output of the additional OR circuit, whose inputs are connected to the outputs of the second and the third And circuit, connected by the first inputs with the trigger outputs, and the second with the output and the input of the NOT circuit, the input of which is also connected to the output of the motor direction of rotation direction. In FIG. 1 shows a diagram of the device; on league. 2, 3, and 4 are diagrams and characteristics explaining his work. The DC electric drive contains an electric motor 1 connected to it by a power switch 2, st | 9 5, which is connected with the motor shaft of the sensor 3 rotational speed, the pulse frequency-phase discriminator C one input of which is connected to the speed sensor 3 and the other input of the pulse frequency phase discriminator is connected to the output of the master frequency generator 5. The discriminator output is connected to the input of the filter 6, the output of which through inverter 7 is connected to the threshold element 8. Additionally, the output of the filter 6 is connected to the input of the threshold element 9. The output of the threshold element 8 is connected to the first inputs of the trigger 10 and the logic circuit OR 11, to the second inputs which is connected to the output of the threshold element 9. The direct output of the trigger 10 is connected to the reversing input of the power switch 2. The logic unit 12 is composed of serially connected frequency converters 15 in the pulse duration and logic of NAND gates 14 and 15. And the converter 13 may be implemented, for example, a series connection of a frequency converter in analog and pulse-width modulator. The converter input 13 is connected to the auxiliary input of the rotation speed setting unit 5, one of the inputs of the circuit 15 and the synchronization input of the converter 13 is connected to the output of the logic circuit OR 11, and the output of the AND circuit 15 is connected to the modulating input of the power switch 2. The motor rotation direction adjuster 16 is connected to the input of the logic unit 17, consisting of the logical circuit NOT 18, the second and third circuits AND 19 and 20, the first inputs of which are connected to the outputs of the circuit HE 18 and the setting device 16, and the second respectively to the direct and inverse . mu trigger outputs 10. The input of the Converter 13 is connected to the auxiliary output of the oscillator 5 of the master frequency. One of the inputs of the logic circuit 15 and the clock input of the converter 13 is connected to the output of the logic circuit OR 11, and the output of the logic circuit 15 is connected to the modulating input of the power switch 2. The setpoint 16 of the direction of rotation of the electric motor is connected to the input of the logic block 17, consisting of a logic circuit 18, a second and a third logic circuit AND 19 and 20. The first input of logic circuit 19 is connected to the output of the logic circuit HE 18, and the first input of logic circuit 20 is connected to the output of the setting device 16 of the direction of rotation engine. The second input of the logic circuit AND 19 is connected to the direct one, and the second input of the logic circuit AND 20 is the inverse output of the trigger 10. Logic unit 17 contains an additional logic circuit OR 21, the inputs of which are connected to the outputs of the logic circuits AND 19 and 20, and the output - to the second input circuit AND-NOT 1 The drive works as follows. The frequency of the output signal of sensor 3 is determined by the dependence f3 O (where ff) is the reference frequency; Fgp is the rotation frequency; j is a coefficient whose sign is determined by the direction of rotation. From here follows Pr-% - pot, (2) where is the phase of the sensor output signal; (, is the angular position of the rotor; -% of the reference signal. This signal provides a high frequency of information on the y position and rotor speed in an unlimited range of rotation speed, including the GWR-0 signal. Signals from the speed sensor 3 In the phase-locked loop mode, the input signals J of the discriminator are maintained, i.e., i.e., b is fo time from here F - - (- bp - f Pulsed frequency-phase drive minator C has a logic input. On the frequency press equalization of the characteristics of the discriminator relay at f. 4n output 1 at Gd, -7, at the output O, (where 4 f signal sensitivity at the first input of the discriminator; f d - frequency of the signal at the second input of the discriminator. in phase comparison mode output signal The discriminator is a sequence of pulses corresponding to a logical unit with a frequency f4 and a fill factor Kj proportional to the difference between the veils of the compared signals -, x - 4, - AF. 4. 21E Trb The discriminator pulse output signal is fed to a filter 6, the main element of which is the integrating RC-link. Therefore, the output / filter signal has a sawtooth shape with a constant component proportional to the value of K at its input. The output signal of the filter 6 arrives at the inverter 7. The direct and inverted filter signals arrive at the threshold elements 8 and 9. As a result of the impact of the sawtooth signal on the threshold element, rectangular pulses are generated at its output, the filling factor (J) of which depends on a constant component of the sawtooth input signal and, thus, from Q4 and, ultimately, on the phase difference of the discriminator input signals (Fig. 2). Static characteristics determining the dependence of the output signals of the threshold element. the difference in the output signals of the phase discriminator shown in Fig. 3. Due to the presence of an inverter 7, these characteristics have areas with opposite tilts, and the thresholds of tuning elements 8 and 9 are, for example, so that the sloping areas have a common point on the phase axis (x-axis) 57. In this case, at a fixed position of the operating point on the phase axis, only one of the two threshold elements is triggered. The output signals of the threshold elements 8 and 9 are fed to the logic circuit OR 11, the filling factor of the output signal of which K-y / j has the relationship shown in FIG. The output signals of the threshold elements 8 and 9 also go to the separate inputs of the trigger 10 and set it, respectively, to state 1. The output signal of the OR 11 circuit through the logic unit 12 is fed to the modulating input of the power switch, and the output signal of the trigger 10 is fed to the reversing switch of the power switch 2. The effects on the electric modules of the modulating and roar inputs of the power switch are provided by the table. Tab

With increasing load, the motor () creates a moment in the direction of rotation, and with decreasing (M 0), a braking moment is created.

The torque is controlled by varying the pulse filling factor of logic 1, following with frequency and 1. Positive moment cojiflaejcfl with alternating direct switching on and off, and negative torque with alternating anticlockwise and dynamic braking.

Consider further the operation of the drive, for example, with a given right direction of rotation. In this case, the operating point is to the right of the neutral point / C (Fig. 3).

With a small moment of load, the operating point is close to / K and phase fluctuations N I F,

BP

, 0, (Рвр) (6)

K, The pulses from the output of the converter arrive at the input of the AND-HI circuit 14 and their further passage depends on the output signal of the logic block 17, whose operation is determined by the table.

table 2

Right

Claims (2)

The output signal of the logical lock 17 depends on the combination of SIGYL 58, arising under the influence of disturbing factors, can transfer it to the area to the left of the point, which causes the trigger 10 to switch to the state 0. At this, the inclusions are relatively low frequencies of rotation. . However, at medium frequencies and higher, the braking that occurs during opposition may be excessively large, which degrades the quality of regulation. Therefore, in the proposed device, the automatic regulation of the opposition and, thus, the braking torque depending on the rotation frequency is introduced. This is done using logic blocks 12 and 17, which work as follows. The input of the frequency converter 13 to the pulse duration receives a signal from the source of the reference frequency, which determines the rotational frequency. The output pulses of the converter 13 are synchronized by the output signal of the circuit OR 11 and have a duration proportional to the frequency at the input of the converter. Thus, a correspondence is established between the pulse filling factor at the output of the converter 13 and the predetermined rotational frequency. 9 setters 16 for rotational direction and trigger 10, i.e. from the mode of operation of the drive. With the inclusion, i.e. when the electric drive creates a positive moment for a given direction, the signal O at the output of block 17, and after switching the trigger 10 for a negative one, i.e. braking moment, at the output of block 17, signal 1. At signal O at the output of block 17, logic unit 12 passes, without changing, the pulses of the OR 11 circuit to the modulating input of the power switch. Thus, in direct switching on mode, block 12. does not matter. At signal 1 at the output of logic unit 17, the passage of pulses through the AND-NE 1 scheme at which they are integrated opens. Inverted pulses arrive at Scheme I 15 and close it to pass the output pulses of the OR 11 circuit (Fig. 2). Thus, the signal at the output of logic block 12 is determined as follows: K, K, K5, K.- go () de, the fill factors of the output signals of the OR 11 circuit, the converter 1 3 and the logic block 12; determined by dependency (6). As can be seen from (6) and (7) in the mode of creating a braking one, i.e. negative moment, the opposition may be produced or not produced, depending on the frequency of rotation. In the absence of opposition, a negative moment is created dynamically by deceleration, while the absolute value of the moment is much less than with opposition. As can be seen from FIG. 4, with Igp F negative, i.e. the braking torque is created by alternating with the frequency of modulation of the dynamic braking and countering modes, with g, p FO, the opposition’s weight decreases, and with Inp i - p, the anti-switching is completely stopped and the braking moment is created only by dynamic braking 5 For some fixed Iepi dependence M (AV) is represented in FIG. . With the corresponding implementation of dependence (6), it is necessary to have a dependence of the inhibition and dynamic braking on the rotation frequency (Fig. 4). The characteristics (Fig. 3) relate to the case of the right direction of rotation -. In the left direction of rotation, the characteristics of Out. 7 Kf will be symmetrical to the characteristics of the right rotation with a vertical axis of symmetry passing through the 1t point. The proposed device allows the introduction of automatic regulation of the braking torque depending on the rotational speed, which makes it possible to improve the quality of regulation at low load points and expand the functionality of the electric drive. Invention A direct current drive containing an electric motor connected to the output of a power switch, a rotational speed sensor of an electric motor connected to one input of a frequency-phase discriminator, the second input of which is connected to the output of a setting frequency generator, and the output through a filter to the input of an inverter, two threshold elements The outputs of which are connected respectively to the input and output of the inverter, and the outputs -. with the inputs of the OR circuit and the trigger connected by the direct input to the reversing input of the power switch, and the setter of the direction of rotation of the electric motor, which, in order to improve the quality of regulation, two logic blocks are added to the drive, the first of which contains a converter frequencies in the pulse duration and two-input circuits AND-NOT and AND, and the second circuit is NOT, the second and third two-input circuits are AND and OR, the first input of the converter is connected to the auxiliary output of the generator and the master frequency, the second input of the converter - with the output of the main circuit OR, and the first input of the first circuit AND connected to the output with the modulating input of the power switch, the output of the converter eleven connected to the first input of the circuit IS-NOT whose output is connected to the second input of the first circuit AND, and the second input to the output of the additional OR circuit whose inputs are connected to the outputs of the second and third circuits AND connected by the first inputs to the outputs of the triggers, and the second respectively - with the output and the input of the circuit NOT, the input of which is connected to the output of the sensor of the direction of rotation of the electric motor. 857512 . Information sources, taken into account in the examination to become Be Larionova V.V. and Fedorov V.V. Correction method for hine-cooled contactless DC motors. Collection of electronic equipment in automation, edited by Yu.I.Konev, vol. 9, M., Soviet Radio, 1977. 10 2. USSR author's certificate in application N ° 26 1372/07, cl. H02R 5 / Ob, 1978. ig.1 -I 1-1 SffJlB fg M i 1 P m. t 111 " I I I i i Fig 5 Direct t4 8ik / 1H} 3f uuHOMUiftCKoe MtJHOMQf ecKoe rotation npomu oS tf / iH: ifeHUt Bf SPf VRz. B