SU1288892A1 - Digital generator of three-phase sine signals - Google Patents

Abstract

The invention relates to electrical engineering - and can be used in an electric drive control system. The stability of the phase shift and the amplitude of the output voltage are increased. The control unit 1 amplifies the frequency control signal of the variable frequency generator 2 and the counting direction control signal of the reversible counter (PC) 3. In the permanently memorized blocks 4, 5, the values of the sinusoidal signal are recorded so that a periodic change of the digital code at the output of the PC 3 leads to a change digital codes at the outputs of blocks 4, 5 sinusoidally with the same period and with a phase shift of I20. A change in the counting direction of PC 3 leads to a change in the signal phase from blocks 4, 5 to 180. The signals from the blocks 4, 5 through the corresponding DAC 6, 7 are passed to the adders 8, 9, where the constant component is compensated. In the accumulator 10, a third phase of a three-phase sinusoidal signal is formed. The amplitude of the three-phase sinusoidal signal is set with a control source 11 of the reference voltage. 1 h, para. f-ly, 2 ill. s (L (o 00 00 00 soy

Description

The invention relates to electrical engineering, measurement technology and can be used in an electric drive control system.

The aim of the invention is to increase the stability of the phase shift and to provide an adjustment of the amplitude of the output voltage.

Fig. 1 shows the structural electrical circuit of a digital generator of three-phase sinusoidal signals; Fig. 2 illustrates stress plots showing its operation.

The digital generator of three-phase sinusoidal signals contains a control unit, a variable frequency generator 2, a reversible counter 3, the first and second blocks 4 and 5 of permanent storage, the first and second digital-to-analog converters 6 and 7, the first, second and third adders 8-10 and controlled source, 11 reference voltage.

. The digital generator works as follows.

The first output of control unit 1 generates a frequency control signal of oscillator 2, from the output of which a periodic sequence of pulses arrives at the counter input of the reversible counter 3. The control signal of the counting direction of the reversible counter 3 comes from the second output of control unit 1 (Fig. 1). In the first and second blocks 4 and 5 of permanent memorization, the values of the sinusoidal signal are recorded in such a way that the periodic change of the digital code at the output of the reversible counter a 3 leads to a change in the digital codes (at the outputs of the first and second blocks 4 and 5) sinusoidally, c the same periods and with a phase shift of 120 ° (Fig.2 a). Correction of the counter counting direction

3 leads to a phase change signal at the outputs of the first and second blocks

4 and 5 by 180. The outputs of the first and second digital-to-analog converters 6 and 7 sinusoidal signals have a constant component (fig.2b), which is compensated for the first and second adders 8 and 9 The adder 10 is designed to receive the third phase of a three-phase sinusoidal signal (fig.26). Amplitude of a three-phase sinusoidal

The signal depends on the voltage at the output of the controlled source 11, which converts the amplitude control signal from the third

the output of the control unit 1, to the unipolar output voltage. In this case, the control signal from control unit 1 can be in both digital and analog forms, which

will require an appropriate implementation of the controlled source 11. Thus, the signals from the first output of control unit 1 change the frequency, from the second change the phase sequence, from the third - change the amplitude of the three-phase sinusoidal signals.

Claims (2)

1. A digital generator of three-phase sinusoidal signals containing series-connected 25 a control unit and a variable frequency generator, successively connected to a level meter, the first permanent memory unit and the first digital-to-analog converter 30 are connected in series the second Permanent Memory unit and the second D / A converter first, second and third adders / characterized in that, in order to increase the stability of the phase shifts of the output voltage, a reference voltage source is introduced into it which is connected to the first and second reference inputs the digital jjQ converter lair and the first inputs of the first and second adders, the input of the second Permanent Memory Unit is combined with the input of the first Permanent Memory Unit, 5 the output of the variable frequency generator is connected to the counting input of a reversible counter, the control input of which is connected to the second output of the control unit, the output of the first digital input JQ of the logic converter is connected to the second input of the first adder, the output of which is connected to the first input of the third adder, the second input of which is connected to the output of the second With a north-west signal, the second input of the second cyi-i-mater is connected to the output of a second digital-to-analog converter, and the outputs of the first, second, and third adders are outputs of a digital three-phase sinusoidal signal generator. 2. The generator according to claim. Characterized in that, in order to provide amplitude adjustment Out, 5 The output voltage, the source of the reference voltage is made in the form of a controlled source of the reference voltage, and the input of the controlled source of the reference voltage is connected to the third output of the control unit.