SU1229725A1 - Digital electric drive - Google Patents

Abstract

The invention relates to the papermaking and metalworking industries and may find wide application in stabilizing the speed of vras, rolls of papermaking machines and rolling mills. The task of correcting the code in the accumulating adder is solved, thereby increasing its speed. The required speed of the electric drive is set by the code at the output of the setpoint device, which, by a signal, the Start from the start block output is written to the accumulating adder. The code-to-analog converter converts the output signal of the adder in the motor control signal. The speed of rotation of the motor shaft is fixed by a frequency speed sensor. The Start signal passes through the OR element and starts digital correction blocks, namely, it sets the RS flip-flop to the zero state and writes the task code to the counter. The next pulse after the start signal from the output of the speed sensor sets the first pulse shaper to the state “O” and it begins to form a feedback pulse of duration TO. At the moment corresponding to the leading edge of this pulse, a pulse is formed at the output of the second pulse shaper, which sets the RS flip-flop to the state "1. The RS trigger opens the first AND element and the output pulses of the speed sensor are passed to the counter subtraction input. At the moment of counter zeroing, a signal is generated at the output of the third element I, which, through the second element OR, will go to the R input of the RS trigger and set it to the state “O A TOC pulse is generated at the output of the RS flip-flop. The comparison unit compares the pulse durations To and Tdc. The result of the comparison in discrete form is fed to the input of the accumulating adder, thereby correcting the rotation speed of the electric motor. Means are provided to compensate for the overflow of the accumulating adder. 1 il. iP CL GCHE to So JV

Description

The invention relates to papermaking and metalworking machinery and may find application in stabilizing the speed of rotation of the rolls of papermaking machines and rolling mills.

The purpose of the invention is to increase the speed of the electric drive.

The drawing shows a structural diagram of the drive.

The circuit contains an electric motor 1 (direct current), a speed sensor 2, the first element I 3, the first driver 4 pulses, a comparison unit 5, accumulating adder 6, a code converter - analog 7, counter 8, RS flip-flop 9, third, second and the fourth elements are AND 10-12, the second, the first and the third elements are OR 13-15, the second and the third pulse shaper 16 and 17, the setting device 18, the start block 19, the X-code of the task signal.

The drive works in the following way.

The required speed of the electric motor 1 is set by the output code N of the setting device 18, which, by the output signal of the start of the starting block 19, is recorded in accumulator adder 6. The code-analog converter 7 generates a control signal of the motor 1 proportional to the code at the output of the accumulating adder 6. The code obtained at the output of the converter - analogue 7, the signal is fed to the input of the electric motor 1. The output of the speed sensor 2 generates a frequency f, proportional to the actual speed of rotation of the electric motor 1. Simultaneously, the output One start signal of the start block 19 passes through the third element OR 15 and starts digital correction blocks: sets the RS flip-flop 9 and the first formulator of 4 pulses to the “O” state and writes the setpoint code N to the counter 8. The next after that pulse the output of the speed sensor 2 sets the first pulse shaper 4 to the "1" state, which determines the start of pulse formation with duration T "at the output of the first shaper 4 pulses.

The 8 moment of time corresponding to the leading edge of a pulse of duration To, the pulse from the output of the second driver 16 pulses sets RS flip-flop 9 to the state "1. RS flip-flop 9 opens the first element AND 3, and pulses from the output of speed sensor 2 pass to the subtract input of counter 8. When the counter 8 is zeroed, a signal is generated at the output of the third element AND 10 that passes through the second element OR 13 to the R input RS-TpHriepa 9 and set it to "O. Thus, at the output of the RS flip-flop

9 a pulse of duration is formed. Comparison unit 5 compares the durations of the pulses To and Tos-Discrete comparison result is integrated in accumulative adder 6, as a result

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which is corrected by the speed of the electric motor 1. With large differences in the durations of the pulses To and Tos, overflow accumulator 6 may overflow. In this case, when all bits of the accumulating adder 6 are set to "O, the signal that passes through the first element OR 14, again zaschschet the output code N of the setter 18 to the accumulating adder 6 and through the third element OR 15 will start the digital correction blocks, forming pulses of duration T and Tos

With small differences in the durations of the pulses To and T "C, the digital correction blocks are started after pounding both pulses with the duration To and Tos with the pulse from the output of the third driver 17 pulses.

In the established regime T ,, Tos, therefore f N / Tf ,. Consequently, in a set mode, the output code of accumulating adder 6 is unchanged, and the speed of the electric motor 1 is constant and proportional to the input code N.

Increasing the speed of this digital electric drive is achieved, firstly, by reducing the duration of the pulse; secondly, by increasing the rate of change of the code accumulating the accumulator 1 about the adder (since the comparison of the durations of the pulses is performed with a higher frequency), thirdly, due to the fact that The overflow accumulative adder starts a new digital correction cycle, which is performed with the reverse feedback signal, which has a smaller error than the feedback signal in the previous correction cycle.

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Claims (1)

Invention Formula A digital electric drive containing a series-connected comparison unit accumulating a adder, a code-analog converter, an electric motor and a speed sensor connected to the first inputs of the first pulse driver and the first element I, as well as a control device connected by an output to the second input of the accumulating adder, differing in: that, in order to increase the speed of the electric drive, the second driver of the pulses, the trigger unit, the second AND element, the first OR element and the last sequently connected in counter, and a third element, the second element OR, RS-flip-flop, the fourth AND gate, a third pulse shaper and third the OR element connected by the second input to the output of the first OR element and to the third input of the accumulating adder, and the output to the second inputs of the second OR element and the first VIH pulse and to the first input of the counter connected by the second input to the output of the generator, and the third input - with the output of the first element And connected by the second input to the first input of the comparison unit and to the forward output RS-flip-flop connected by S-input through the second pulse shaper with the second input of the comparator unit and with the direct output of the first pulse shaper connected by an inverse output to the second input of the fourth element And, the input of the second element And connected with the output of the accumulating adder, and the output with the first input of the first OR element connected by the second input to the output of the trigger unit.