SU1480059A1 - Converter for measuring value and direction of direct current - Google Patents

Abstract

The invention relates to electrical engineering and can be used in electric drive, automation and control systems for measuring high direct currents. The converter contains an alternating voltage generator 1 with two galvanically separated outputs, the voltages of which are mutually shifted by 90 elec. Both of these outputs are connected to the diagonals of the alternating current of the ring diode-resistor modulator 11, the output 12 of which is formed by tapping from the middle points of the output transformer and the drossel 10 of the alternating voltage generator 1. The magnetic modulator 3 is powered by the alternator voltage output 1 and is magnetised by the measured direct current of the current source 5. The output windings 6 of the magnetic modulator 3 are connected to the first input of the phase-sensitive demodulator 7, the second input of which is supplied with a reference voltage from the output 12 resistor-diode ring modulator 11. When changing the direction of the measured DC varies the polarity of the voltage across the load 8 phase-sensitive domodul torus 7. 2 yl.

Description

The invention relates to electrical engineering and can be used in electric drive, automation and control systems for measuring high direct currents.

The purpose of the invention is to simplify the device.

FIG. 1 shows a circuit diagram in principle; in fig. 2 - diagrams that explain the operation of the proposed converter.

The alternating main voltage generator is based on the well-known stabilized transistor oscillator circuit with an L-C circuit in the feedback circuit. The output circuit of the auto-oscillator 1, formed by the secondary winding of its internal transformer, is connected to the working windings 1 of the magnetic modulator 3 in series and oppositely connected. The circuit is connected in series with the connected windings 4 of the control of the magnetic modulator 3 to the source 5 of the measured DC current with great internal resistance.

The output circuit of the magnetic modulator 3, formed by successively and consistently turning on its output windings 6, which summarize the output signal of double frequency, is connected to the first input of the phase-sensitive demodulator 7 connected to the reversible output of the direct current with the payload 8 of the converter. The frequency of the oscillator 1 is stabilized by its internal serial LC circuit containing capacitor 9 and choke 10. The secondary winding of throttles 10 serves as the second galvanically-developed AC output circuit of the oscillator 1, which has a nearly sinusoidal fundamental frequency voltage shifted in phase by 90 ° with respect to the voltage of the rectangular shape of the first output circuit of the oscillator 1.

The first and second output circuits of the alternating current of the auto-oscillator 1, formed respectively by the secondary windings of the output transformer and droplets 10 of the auto-oscillator 1, are connected to the first and second ac inputs of the ring diode-resistor modulator 11, the output circuit 12 of which is formed by the midpoint terminals the secondary windings of the output transformer and the drossel 10 of the oscillator 1 and connected to the second input of the phase-sensitive demodulator 7.

 FIG. Figure 2 shows the diagrams: a — a rectangular-shaped alternating current output voltage, taken from the first output circuit of the autogenerator 1; b is the output voltage taken from the second output circuit of the alternating current of the autogenerator 1; in - output voltage of alternating current of doubled frequency, taken from output circuit 12 of ring modulator 11; g is the change in the measured direct current of source 5; d is the change in the output voltage of an alternating current of twice the frequency taken from the output circuit of the magnetic modulator 3; e is the change in the output reverse signal of the direct current taken from the output circuit of the phase-sensitive modulator 7.

The Converter operates as follows.

When applying alternating current voltage rectangular shape from the secondary winding of the transformer of the oscillator (Fig. 2a) into the circuit of the working windings of the magnetic modulator 3, as well as one alternating current input of the ring modulator 11 simultaneously to its other AC input enters almost sinusoidal voltage from the secondary winding of the drossel 10 of the auto-generator 1, shifted in phase by 90 ° relative to the output voltage of the auto-generator I.

At the same time, in the interval 0 - t (Fig, 2), the output circuit of the secondary windings of the magnetic modulator 3 generates an alternating current voltage of double frequency with a phase close to the voltage phase of the first output circuit of the autogenerator (Fig. 2e). In this case, the output circuit of the ring modulator 11 also generates a double voltage alternating voltage (Fig. 2c) with constant magnitude and phase as a result of the forced switching of the output voltage of the Drossel 10 (Fig. 2b) with a rectangular reference voltage (Fig. 2a). ), switching the diodes of the ring modulator 11.

A phase-sensitive demodulator 7, made, for example, using transistor switching

The keys controlled by the reference voltage of double frequency (Fig. 2c) supplied from the output of the ring modulator 11 to the second input 13 of the demodulator 7, at the same time, produces a push-pull rectification of the output voltage of the double frequency of the magnetic modulator (Fig. 2e, f), fed further to the averaging input of the payload 8 of the converter.

Accordingly, at time tj, when, for example, the polarity of the input signal of the device changes (Fig. 2d), its magnetic modulator 3 responds to this by a corresponding change in the magnitude and phase of the output voltage of the doubled frequency (Fig. 2e), with the phase value This voltage is close to the 180th with respect to the phase of the main output voltage of the oscillator 1 (Fig. 2a). In this case, the phase-sensitive demodulator 7, to the second input I3 of which the reference voltage of the double frequency of the stable phases and values from the output of the ring modulator 1I still continues, reacts to a change in the phase of the output voltage of the magnetic modulator 3 supplied to the first input demodulator 7, changing the polarity of the rectified output signal (Fig. 2e),

Claims (1)

Invention Formula  A converter for measuring the value and direction of the direct current, comprising an alternating voltage generator of the fundamental frequency, the first output of which is connected to a magnetic modulator with a frequency doubling of the alternating current output signal, an output circuit connected to the first input. do phase-sensitive demodulator, source reference. AC voltage doubled voltage connected to the second input of a phase sensitive demodulator, characterized in that, for the sake of simplicity, the alternating voltage generator of the fundamental frequency is designed to provide an electrically isolated additional output with an alternating current voltage of the fundamental frequency shifted by 90 relative to the voltage of its first output, and the source of the reference alternating voltage of the doubled frequency is made in the form of an annular diode-resistor modulator connected by the first and second AC inputs with the first and second outputs of the alternating voltage generator of the fundamental frequency, respectively. eflmfflffi / u UAJ J Myshlg