SU1297193A1 - Variable a.c.voltage-to-d.c.voltage converter - Google Patents

Abstract

The invention relates to a converter technique and is intended to regulate power in a load. The purpose of the invention is to improve the temperature stability of the linearization of the adjustment characteristic while simultaneously galvanically isolating the power circuit and the control circuit. In the converter containing the rectifier. 1, regulating the thyristor 2 and the control device 3, the output of the photodetector of the optocoupler pair 8 is connected between the emitter and the second base of the single junction transistor 6, and the light emitter input is connected to a pulse-width modulator (PWM) 9. By introducing the PWM 9, the temperature stability and improved linearization of the adjustment characteristic. The introduction of an optocoupler allows for galvanic isolation of the power circuit and the control circuit. 2 Il. c /) go gjusi

Description

The invention relates to a conversion technique and is intended to regulate power in a load, and may also find application in various voltage and current regulators in electrical installations.

The purpose of the invention is to improve the temperature stability and linearization of the adjustment characteristic while simultaneously galvanically isolating the power circuit and the control circuit.

FIG. 1 is a schematic electrical diagram of the proposed variable voltage to constant converter; in fig. 2 is a diagram of an operational amplifier that plays the role of a pulse-width modulator.

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the output of the first base of the unijunction transistor 6, the control electrode, the cathode of thyristor 2; When the thyristor 2 is opened, the voltage between the cathode and the anode sharply decreases to 1-2 V, while the capacitor 7 does not charge until the thyristor 2 closes at the end of the half-period of the supply voltage wives In the next half period, the process is repeated. The angle of unlocking of the thyristor 2 in electrical degrees is determined by the charging time of the capacitor 7, which in turn is determined by the total time of current flow through the charging circuit (the unlocking angle Y

 -. 360

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The output element of the optocoupler 8 is a photodiode or photoreflector Adjustable transducer sensor controlled by the light flux

a constant voltage contains a rectifier 1, a thyristor 2 and a control device 3, consisting of an amplitude limiter in the form of a series-connected resistor-25 4 and a zener diode 5 connected in parallel to the thyristor 2, and a trigger device containing a single junction transistor 6 and a capacitor 7, with a single junction; the transistor 30 is connected by the first base to the control electrode of the thyristor 2, by the second base to the connection point of resistor 4 and zener diode 5, and by the emitter through the condensate LED forming the input circuit of the optocoupler 8. To increase the temperature stability, an amplitude current pulses are received on the LED of the optocoupler wherein the output element of the optocoupler is in the saturation region. Linearize the characteristics of the optocoupler. it is included in the circuit of the pulse-width modulator 9. With this control of the optocoupler, the current in the output element will have the form of pulses of a certain duration and amplitude. The charge capacitor 7 will be pulsed.

torus - to the point of thyristor 2, 35 connection; the voltage on it will be zavistabiltron 5 and positive load bus. An optocoupler pair 8 and a pulse-width modulator (PWM) 9 connected to the LED pins are additionally introduced into the control unit. At. This output element of the optocoupler is connected with its first output to the emitter and the second output to the output base of the unijunction transistor 6.

The device works as follows.

The operation of the charger is based on the phase-pulse method of regulating the voltage or the charging current using a thyristor 2 connected in series with the load 10. When an alternating voltage is applied to the rectifier 1, the capacitor 7 is charged through the output element of the optocoupler 8. After reaching the voltage across the capacitor 7 of the threshold of the single-transistor 6, the capacitor 7 is discharged along the circuit: the emitter,

the output of the first base of the unijunction transistor 6, the control electrode, the cathode of thyristor 2; When the thyristor 2 is opened, the voltage between the cathode and the anode sharply decreases to 1-2 V, while the capacitor 7 does not charge until the thyristor 2 closes at the end of the half-period of the supply voltage wives In the next half period, the process is repeated. The angle of unlocking of the thyristor 2 in electrical degrees is determined by the charging time of the capacitor 7, which in turn is determined by the total time of current flow through the charging circuit (the unlocking angle Y

 -. 360

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The output element of the optocoupler 8 is a photodiode or photorescent diode, which forms the input circuit of the optocoupler 8. In order to increase the temperature stability, current amplitude pulses of the optocoupler LED are received, at which the output element of the optocoupler is in the saturation region. Linearize the characteristics of the optocoupler. it is included in the circuit of the pulse width modulator 9. With this control of the optocoupler, the current in the output element will take the form of pulses of a certain duration and amplitude. The charge capacitor 7 will be carried out by pulses from the network to the capacitance and the total (integral) volt-second area of the incoming current pulses, the number of which is in turn determined

40 by the modulation frequency and the unlocking angle (thyristor control), i.e. linearly depends on the angle of unlocking the thyristor.

One of the possible schemes of a pulse width 45 pulse current modulator is shown in FIG. 2, where the operational amplifier 11 serves as a key, the modulation frequency is determined by resistor 12 and capacitor 13.

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Claims (1)

Invention Formula An adjustable AC-to-DC converter, containing an expander, a thyristor and a control device, consisting of a limiter and a lithium in the form of a series-connected resistor and a zener diode, is connected in parallel thyristor, and a trigger device containing a single junction transistor and a capacitor, the single junction transistor being connected to the thyristor control electrode, the second base to the connection point of the resistor and the zener diode, and the emitter through the capacitor to the connection point of the thyristor, zener diode and positive output view, characterized in that, in order to improve the temperature stability and linearization of the regulation characteristic with simultaneous galvanic isolation of the power circuit and the control circuit, an optocoupler pair and a pulse-width modulator were added, switched on parallel to the optical output of the optocoupler, and the output of the photodetector was connected first to the emitter and the second to the output of the second receiver base ra. single junction transistor P eleven 12 Cz} Compiled by E. Melnikova Editor Y. Sereda Tekhred L. Serdyukova Proofreader O. Lugova Order 792/59 Circulation 661 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, Projecto st., 4 FIG. 2