SU1104630A1 - Control device for d.c. motor - Google Patents

Abstract

A DC MOTOR CONTROL DEVICE, containing a clock pulse generator, the output of which is through a blocking driver and a block of delayed pulses connected to the inputs of the switching unit, other inputs of which are connected to the outputs of the comparison unit and the structure changing unit, and outputs through the trigger with the inputs of the amplifier and the unit structure changes, the other input of which is connected to the output of the block of delayed pulses, the outputs of the amplifier are connected to the control inputs of the pulse interrupters, some terminals which, through a power supply unit, are connected to a single motor output, the circuit of which includes a current transducer, diodes, and a register, characterized in that, in order to improve the quality of regulation, two matching circuits are additionally introduced, two counters, a reversible counter, and a series-connected unit set current- ,. analog converter - code, additional register, adder, and frequency converter - code, with the clock generator output through two coincidence circuits, two counters, a reversible counter, re (L hister and adder connected to the amplifier input, the inputs of the comparison unit are connected to The converters' outputs are analog - code and frequency - code, the second. The inputs of the coincidence circuits are connected to the trigger output, and the other output of the motor is connected to series-connected diodes, each of which is connected between the output of On its chopper pulse) and the side of the power unit. WITH

Description

The invention relates to electrical engineering, in particular, to devices for the automatic control of direct current electric drives, and can be used to control the current of inductive loads. A device for relay control of a motor current is known, comprising a driver pulse generator connected via a locking and delayed pulse generator to the inputs of a switching unit, the other inputs of which are connected to the outputs of the structure changing unit, the unit of current and current setpoint of the structure changing unit. also through amplifiers - to a pulse interrupter. Pulse driver ll is connected to the input of the block for changing the structure. The disadvantage of the device is the low quality of regulation due to the significant pulsadia of the controlled current with an abrupt change in voltage across the load. Moreover, at small values of the relative duration of switching-on, the uniform rotation of the motor may be disturbed. The closest in technical essence to the invention is a device for controlling a direct current motor, comprising a clock pulse generator, the output of which is connected to the outputs of the switching unit through the drivers of blocking and delayed pulses, the other inputs of which are connected to the outputs of the comparison unit and the structure changing unit, and the outputs through a trigger are connected to the inputs of the amplifier and the structural change unit, the other input of which is connected to the output of the block of delayed pulses, the outputs of the amplifier They are not connected to the control inputs of the impulse interrupters, some of the outputs of which are connected to one output of the engine through the power supply unit, the circuit of which includes a current transducer, diodes, and a register. In addition, the device contains a one-shot, a comparator, an integrator connected in series with the register, and an input connected to inversion unit 2 J. The known device has a poor quality of controlled current, in particular, substantial pulsations of current with a lower synchronization frequency due to the inertia of the integrator. The consequence of this drawback is the violation of the uniformity of rotation of the engine, especially at low rotational frequencies. The purpose of the invention is to improve the quality of regulation. The goal is achieved in that a device for controlling a direct current motor, comprising a clock pulse generator, the output of which is connected via the blocking driver and the delayed pulse unit to the inputs of the switching unit, the other inputs of which are connected to the outputs of the comparison unit and the structure changing unit, and the outputs through the trigger inputs of the amplifier and the block of structure change, the other input of which is connected to the output of the block, delayed pulses, the outputs of the amplifier are connected to the control inputs and Mp.pysnyh interrupters, one output of which through the power supply unit is connected to one motor output, the circuit of which includes a current transducer, diodes, register, additionally introduced two coincidence circuits, two counters, a reversible counter, a series-connected current reference unit, an analogue converter - code, additional register, adder, and also frequency converter — the code at the same time, the output of the clock frequency generator through two coincidence circuits, two counters, a reversible counter, a register, and an adder are connected to the amplifier's home, the inputs of the comparison unit are connected to the outputs of analogue converters — the code and frequencies — the code, the second inputs of the matching circuits are connected to the trigger output, and another motor terminal is connected to serially connected diodes, each of which is connected between the output of the corresponding pulse chopper and the power supply terminal. . FIG. 1 is a schematic of a device for controlling a DC motor; in fig. 2 - timing diagrams for the operation of the device. . A device for controlling a direct current motor (Fig. 1) comprises a clock pulse generator 1, the output of which is blocked through the driver, night 2 and the block 3 of delayed pulses 1 1 connected to the inputs of the switching unit 4, the other inputs of which are connected to the outputs of the unit 5 comparison and block 6 structure changes, and the outputs through the trigger 7 are connected to the inputs of the amplifier 8 and the block 6 structure changes, the other input of which is connected to the output of the block 3 delayed pulses, the outputs of the amplifier 8 are connected to the control inputs of pulsed drives Breakers 9, one terminals that are connected through the power supply unit 10 to one output of the engine 11, the circuit of which includes a current measuring converter 12, diodes 13, register 14, two circuits 15 and 16, two counters 17 and 18, a reversible counter 19, series-connected current setting unit 20, converter 21 analog — code, additional register 22, adder 23, and frequency converter 24 — code. The output of the oscillator 1 clock through two circuits 15 and 16 coincidence, two counters 17 and 18, a reversible counter 19, a register 14 and an adder 23 are connected to the input of the amplifier 8, the inputs of the comparison unit 5 are connected to the outputs of the analogue converters 21 and the frequency code 24, the second inputs of circuit 15 and 16 of coincidence are connected to the output of trigger 7, and the other output of motor 11 is connected to series-connected diodes 13, each of which is connected between the output of the corresponding pulse chopper 9 and the output of power supply 10. Switching unit 4 fulfills the distribution function of pulses coming from comparator unit 5 and forming a 3 delayed pulses, and is implemented on AND-OR-NOT gates. The structure changing unit 6 performs switching of the logic elements of the switching unit 4 in accordance with the output signals of the trigger 7. The device operates as follows. At the initial moment of start (figure 2), the current of the engine core 11 is zero,. and the square-wave pulse voltage frequency generated by current transducer 12 has an initial value f, Digital code Z, generated in frequency converter 24 - code by counting the number of pulses of quarter duration for a time interval Tp equal to half the period of the measuring output signal f the current converter 12 is supplied to the first summing inputs of the comparison unit 5. The analog voltage generated by reference block 20 and corresponding to the value of current setpoint 1, the analog converter converts the code to code Z. Z values are written to additional register 22 and, arriving at the second summing inputs of comparison unit 5, determine the output voltage of the last (Fig. 1) O, at 1, at 1 Z; In the initial state, with the relative duration of switching on -J1 i 0.5, the voltage U2 corresponding to logical 1 and U25 corresponding to logical O, coming from the outputs of block 6 of the structure change to control of the switch block 4, allows the passage of the first trigger signal 7 of the pulses U of the unit 3 delayed pulses and to the second input - voltage U25 1. The voltage pulses and, from the output of the unit 3 delayed pulses are located in the center of the zone of action of the pulses of the former 2 locking pulses. The duration t, −2t, is determined by the maximum recharge time of the switching capacitor of the pulse chopper 9. The trigger 7 is in one stable state at which the voltage and from its direct output allows the pulse generator 1 clock to pass through the coincidence circuit 15 the input of the counter 17 (voltage pulses), In accordance with the division factor of the counters 17 and 18 (where t, j is the maximum value of the pulse from the output of the TrggeRZ 7 Gtoh); T .. - the period of the pulse generator 1 clock pulse. At the summing input of the reversible counter 19, the voltage pulses Uj (j. In addition, the amplified voltage of 1 p. of the direct output of the trigger 7 arrives at the control input of the pulse interrupters 9, opens it. The digital totalizer 23 arrives at the first summing inputs of the adder 23 the code Zj О recorded from the output of the reversing counter 19 in register 14, and on the second the value of the code Z from the output of the additional register 22. The total value of the code Z Z. "Z from the output of the adder 23 is amplified and goes to the control impulse interrupter inputs 9. Therefore, the value of the Z code determines the supply voltage U of the motor. To obtain, for example, a linear dependence of the voltage 4 F (Zj), it is necessary that the switched voltages of the power supply unit 10 correspond to the values of the voltage of the additional booster steps of the power supply unit 10, switching pulsed interrupters 9; nominal supply voltage of the motor 11. The supply voltage of the first voltage boost stage and the number of switching voltage booster stages of the power supply unit 10 is determined by the specific requirements for speed control zone, current pool. R corresponds to the value of the voltage 31, the code L. that arrives at the motor 11 is equal to. / 2 Z 3 dbno 1,2 ,. minimum voltage value of the voltage step. 11 of the non-starting engine of the mobile state {. 0.5) the current I increases, the frequency f of the current transducer I ,, and the value of the code Z- increases. According to formula (2), if Z is equal; and Z. output pulse of voltage 1 and block 5 of comparison to the second input of trigger 7 (since, 5 and 1, O), sets the latter in the opposite steady state. Voltage 06 U2g O is fed to the inputs of circuits 15 and 16, the coincidence and, because the voltage and the counter 17 stops counting the pulses of the 1 clock pulse generator, and the counter 18 starts. The pulse choppers 9 are closed, the current 1 of the motor 11 and the frequency f of the current measuring converter 12 are reduced. The impulse voltage U,, the next with a constant frequency f. 1 / T, arrives at the first input of the trigger 7, sets it to the initial state. When ,, (is determined by the duration in accordance with the formula (3) (T, - t) i CTr., At the output of the counter 18 there are no voltage pulses U,. The value of the code Z. at the output of the register 14 and, therefore, Z, Z - + Z remains constant. The positive potential from the direct output of flip-flop 7 opens pulsed interrupters 9. The current Ij of the motor 11 and the frequency f of the current measuring transducer 12 increase. Next, the process of stabilizing the current of the motor 11 repeats. 0.5 (first control structure) for opening pulse interrupts The telephones 9 (at the first input of the trigger 7) receive pulses Uj of a constant frequency, and the closing (to the second input of the trigger 7) pulses U22, generated by the relay method. The voltage U ,, power of the motor 11 is equal to / 2 - and ., but / l With an increase in the speed of rotation of the engine 11, the block 6 changes the structure, integrating the current value -j (the duration of the voltage pulses from the outputs of the trigger 7) for a period of time. (3-4) T |, when reaching -jj-j. , 5 changes the potentials of the output voltages U j, O, and 1 These voltages, affecting 25 on the switching unit 4, permit the supply of voltage pulses U to the first input, voltage pulses, to the second input. Therefore, when y) 0.5 (second control structure), pulses and arrive at the closure of the pulse interrupters 9. at a constant frequency, and for opening, the pulses generated by the relay method when the current Ij2 drops to the setpoint 1. The process of current stabilization 1 при at –y 0.5 occurs in a similar way as at, 5. Switching the control structure from the first to the second and vice versa is carried out in order to save the switching frequency 1 of the pulse interrupters 9 when the load parameters of the motor 11 or the input voltage of the power supply unit 10 are changed. With a further increase to T TiTiM, the counter 17, counting the pulses of the generator 1 clock pulses during the pulse operation from the direct output of the trigger 7, will be filled in with the voltage pulse at its output according to formula (3). As a result, the value of the output code Z of the reversible counter 19 will increase, which will also lead to an increase in ZZ at the output of the adder 23. Zj-11 age The voltage U on the motor is one tete in accordance with formula (5), which will decrease -y, and The process of stabilizing the current Ij at 0.5 repeats. In the event of disturbing actions, for example, an abrupt increase in the input voltage of the power supply unit 10 or the load on the motor shaft 11, a transition from the second control structure of the impulse interrupters 9 to the first and decrease to j Tm; r will occur (Fig. 2 considers the case decrease -j to v. when pulsed interrupters 9 are operated on the first structure). In this case, the duration of the voltage pulse Ujg output from the direct trigger output is equal to t and, in accordance with formula (3), a voltage pulse U is formed at the output of the counter 18. An input to the subtracting input of the reversible counter 19, the indicated pulse, in addition, also reducing the amplitude of the current pulsations reduces the unevenness of the motor rotation, especially at low rotational frequencies, and improves the harmonic composition of the consumed and regulated currents. This does not lead to a decrease in the code Z, Z .., + Z and, consequently, the output of the adder 23. According to formula (5), the voltage 1) on the motor 11 decreases, the relative duration of the switch on increases and then the process of stabilizing the current Ij2 on the first structure control of the pulse interrupters 9 is repeated. Thus, the control of the relative on-time duration If-is carried out in each switching period of the pulse interrupters by measuring the pulse duration from the trigger output and, accordingly, forming the amplitude of the analog value of the motor supply voltage (4), (5). Therefore, the device eliminates ripple current cor with a frequency lower than the switching frequency, due to the transition from one load characteristic to another in accordance with the equation g- + C n and) F i p F-V 3 Av / l resistance of the motor core circuit; (m is the speed of rotation of the engine; F is the magnetic flux of the engine; securing the engine, which leads to an improvement in the quality indicators of the control process.

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Claims (1)

DEVICE FOR CONTROLLING A DC MOTOR, containing a clock pulse generator, the output of which is connected through the blocking driver and the delayed pulse block to the inputs of the switching unit, the other inputs of which are connected to the outputs of the comparison unit and the structure changing unit, and the outputs through the trigger to the inputs of the amplifier and unit structural changes, the other input of which is connected to the output of the unit of delayed pulses, the outputs of the amplifier are connected to the control inputs of the pulse choppers, some of which through a power supply unit they are connected to one output of the motor, the circuit of which includes a measuring current transducer, diodes, a register, characterized in that, in order to improve the quality of regulation, two matching circuits are additionally introduced into it, two counters, a reversible counter, and a reference unit connected in series current. an analog – code converter, an additional register, an adder, and a frequency – code converter, and the output of the clock generator through two matching circuits, two from the counter, a reversible counter, a register and an adder connected to the amplifier input, the inputs of the comparison unit are connected to the outputs of the converters analogue - code and frequency - code, the second inputs of the matching circuits are connected to the trigger output, and the other motor terminal is connected to series-connected diodes, each of which is connected between the output of the corresponding pulse circuit breaker and the output of the power supply.