SU131791A1 - Device for pulse width modulation - Google Patents

Description

Devices for pulse-width modulation on semiconductor triodes, made in the form of a phase-sensitive circuit, are known.

A disadvantage of such devices is the difficulty of summing rectangular pulses at the output of the modulator.

In the described invention, this disadvantage is eliminated by summing rectangular impulses with the help of two Reciprocating rectifiers. This simplifies the device and increases the reliability of its work.

Schematically, a device for pulse width modulation is shown in the figure.

The device has two multivibrators: one, made on triodes 1 and 2 according to the circuit with transformer coupling, plays the role of a master oscillator of rectangular pulses, and the other, made on triodes 3 -yi 4, is forced to start. Tr-iods 3 to 4 are controlled by the output voltage of the master multivibrator using windings 5 and 6 of the Tpi transformer, which are connected in parallel but in antiphase. A resistance 7 and a blocking valve 8 are included in the winding circuit 5. In the winding circuit 6, a resistance 9 and a choke with a bias magnet 10m, which is made on a core with a rectangular hysteresis loop, are connected in series. The voltage on the winding 6 is somewhat larger than the voltage on the winding 5.

The combination of two chokes W, belonging to different arms of a multivibrator, together with their windings, // works like a magnetic amplifier with free even harmonics. If the magnetization of the chokes 10, carried out by the bias current from the clamps / 2-/.2, is such that the cores of the chokes are not saturated during the half-period of the supply voltage, then the triodes 3 at 4 switch No. 131791-2 are wound with the windings 5 of the transformer Tr at the same time as the triodes / and 2. Therefore, the voltages at the output of the transformer Tr and Tpz coincide in phase. If the cores of chokes 10 are saturated (each U is one of the full periods) At the saturation angle, the voltage at the output of the transformer Tp will be ahead of the voltage at the output of TpaHc opiMaTopa Gra at the angle - F The sum of the voltages from the outputs of the transformers Tpi and Tp is applied to the rectifier bridge 13. At the output of bridge 14, a voltage in the form of rectangular pulses arises with a duty cycle from 0 to 1. Be; the duty cycle depends on the saturation angle of the chokes 10.

With Qualitative throttles, the saturation angle may vary from

0do radians With a change in the saturation angle from O to the pulse duty ratio at the output of the device varies from O to 1 (if the sum of voltages from the outputs of the transformers 7pi and Tr is used)

1 to O (when using the difference of these voltages).

Invention

A device for pulse-width modulation on semiconductor devices and magnetic elements, made in the form of a phase-sensitive circuit, consisting of a master multivibrator and a multivibrator with forced starting, with the aim of controlling the circuit of the device, in the output circuit The modulators used two Reciprocating rectifiers designed to supply from the AC side, respectively, the sum and difference of the rectangular voltages of the multivibrators and the output signal.