SU699651A1 - Pulse-width modulator - Google Patents

Description

I

The invention relates to electrical engineering, in particular, to an automatic control technique and can be used in constant voltage regulators and in stabilized voltage converters.

In pulsed automatic control systems, devices with astatic regulation are known, based on a comparison of the voltages of two oscillators, one of which is a reference, the other is a converter of a continuous signal to frequency l. In such devices, there is the problem of synchronizing the frequency of the generators, especially in transient conditions.

The closest in technical essence to the proposed invention is a pulse-width modulator, made in the form of a phase-sensitive circuit, containing a master oscillator with a transformer, an oscillator synchronized with it and a transformer, and a form voltage pulse. In this case the master oscillator is connected to the synchronization generator through the capacitor and the transformer winding of the incident generator and is controlled by the pulse width former 2.,

A disadvantage of the known modulator is that it does not allow for the implementation of astatic regulation, which increases the stability of the output voltage.

The purpose of the invention is the implementation of astatic regulation.

The goal is achieved by the fact that the impulse length driver: the owl is connected to the windings of the synchronized generator transformer.

The invention is illustrated by drawings, where in FIG. 1 - a schematic diagram of the proposed OP-pulse-width modulator; in fig. 2 - time diagrams of voltages and currents. The pulse width modulator contains a master oscillator, made on transistors 1, 2, and a oscillator synchronized with it, made on transistors 3, 4 .. The latter is synchronized in frequency from the master oscillator with the help of a capacitor 5 through the winding b of the master transformer of the master oscillator to regulate phase of the synchronized generator, an impulse length driver 7 is used, in particular, a magnetic amplifier connected between the bases of transistors in the form of two half-wave circuits with a common winding control and pulse shaper 7 determines the duration of the residence time of the transistors 3 and 4 in the open state and thereby controls the generator phase. The supply of the current oepeMeHHOtxt current shaper 7 carries the voltage removed from the windings 8, 9 of the transformer of the synchronized generator. As in the well-known modulator / output, the alternating voltage of the master oscillator Ozg has a rectangular shape with a steep switching front. The synchronized oscillator is made with positive feedback implemented by the windings 8, 9, due to which the states of the transistors 3 and 4 and the output voltage of this generator Us are changed, being shifted relative to and oC in the direction of advancing. The cores of the output transformers of the generators are the same, therefore the clock frequency of the synchronized generator oscillations is slightly less than the frequency of the master oscillator. The voltage across winding 6 is also alternating and has a rectangular shape. The charging current i has the form of short pulses, the beginning of which coincides with the switching moment of transistors 1, 2. In the absence of other control pulses, pulse i. provides switching of transistors 3, 4 simultaneously with switching of transistors; 1, 2 and in this case, the output voltage of the synchronized generator coincides in phase with U. The output voltage generated by the summation of the voltages from the output of the generators has the form of two square pulses, the duration of which can be regulated over a wide range. The duration of the voltage pulses and, therefore, the temporal ishaial between the falling edges of the pulses of the output voltage Ugj ,, nponopuHOHa ib to the current 1 at the biasing of the cores of the magnetic amplifier. The leading edge of the pulses is determined by the front (JpoirroM pulses of the master oscillator. In a certain randomly taken c semi-half period, conventionally taken as the first, the duration of the impulses of the controlled oscillator is determined by the expression S, (1) where - the pulse duration of the master oscillator 1; a - constant; i - the control current deviates from the rated current. Similarly to this, in the following half-periods: ,, (()) Or summing up, we get a type that shows that the pulse duration: the controlled oscillator is an approximate sum of r ,, (t) T ajAi Ct1dl (4), the more accurate the shorter the period and the slower the input control current 1 changes. The duration of the modulator output pulse is the difference (sum) phases of generators, i.e. on the basis of (4); t tft) -otjM (-t) dt + Zr,., where, is the duration of the output of the modulator impulse but ghz to the first half-period. Thus, the proposed modulator circuit makes the duration of the output pulses not proportional to the input current, and the integral of the current deviation from the nominal, which allows for astatic regulation.

Claims (2)

1. USSR Authors ’No 338975, cl. H 2 M 3/10, 1970. 2.Kosov O. A. Power amplifiers in transistors in the switching mode. M ,, Energie, 1971, p. 362. Chv Chbyi 0 J 1 j (at