SU1198698A1 - Controlled a.c.voltage-to-a.c.voltage converter - Google Patents

Description

The invention relates to electrical engineering and is intended for use in the regulation of the power of active and inductive loads.

The purpose of the invention is to reduce high-frequency noise, increase reliability.

The drawing shows a diagram of the proposed device.

The circuit contains a regulator 10 of a diode bridge, filled with diodes 1-4, thyristor 5, and a control unit consisting of a control key made on transistor 6, the base of which is connected through a resistor 7 with a circuit that determines: ~ the duty cycle of the periods of alternating voltage applied to the load.

This scheme, which determines the duty cycle of alternating voltage periods, includes a ϋ-flip-flop 8, made on a Ι76ΤΜ2 chip, and a timing chain containing potentiometer 9, the middle pin of which is connected to it by a ϋ-flip-flop, and 25 extreme leads through diodes 10 and 11 are connected to the ϋ-input of the ϋ-flip-flop.

0, - the output and ϋ-input of the три-flip-flop are connected via a storage capacitor 12. 30

The power supply control unit is made on the limiting resistors 13 and 14, the Zener diode 15, the rectifier diode · 16 and the filter capacitor 17. ₃₅

Parallel input power ϋ-flop 8 included a filter capacitor 17, at ^'{+' input of which is energized from a power source through a limiting resistor 13 and 4θ rectifying diode 16, and the output filter capacitor 17 is connected to the second output of the diode bridge.

To stabilize the magnitude of the constant ^ voltage, the ϋ-trigger 45 8 supply, the Zener diode 15 and the limiting resistor 14 connected in parallel are included in the circuit.

‘The anode of the Zener diode 15 is connected to the negative terminal of the filtering 50 capacitor 17, and the cathode of the Zener diode 15 is connected to a point uniting the conclusions of the limiting resistor 13; rectifier diode 16 and C input вход-trigger 8. 55

The device works as follows.

The positive half-cycles of the network are limited by the load element (resistor) 13 and the Zener diode 15 and through a rectifier element (diode) (Ί6 charge the storage element (capacitor) 17 connected in parallel to the trigger 8. Positive voltage front at the Zener diode 15, which appears once during the transition period line voltage through zero, is used for clocking the trigger 8.

When the trigger 8 is shown on the diagram, periodic oscillations occur with a period proportional to K · C, where K is the resistance of the adjusting storage element (potentiometer) 9; and C is the capacitance of the storage element (condenser) 12.

Assume that capacitor 12 is discharged and at the non-inverting output of the trigger is low, and at the inverting output ~ high. Then, the capacitor 12 is charged with the inverting output through the left half of the resistor 9 and the diode 10 to the switching threshold during ΐ "·, = C E _A where E _d - the resistance between the left terminal of a potentiometer 9 and a middle point.

As soon as the threshold is reached, at the next clock pulse, trigger 8 is switched, and capacitor 12 is discharged from the inverting trigger output through the right half of potentiometer 9 and diode 11 to the switching threshold in time = С, where Ер is the resistance of the right half of potentiometer 9.

As soon as the threshold is reached, at the next clocking pulse, the trigger will switch and the system will return to the initial state. Full period

RL

The duty cycle of 5 -y- ^e - p linearly

.L ^to n

depends on the resistance of potentiometer 9 (where T is the period of the network).

During the non-inverting output of the trigger 8, there will be a high state, which through the resistor 7 will open the transistor 6, which includes the thyristor 5 and the diode bridge on diodes Ί-4 will be open for a while.

3

1198698

four

In the low state time will Ζ _Ά at the noninverting output of flip-flop 8 through the resistor 7 which closes the transistor 6, the thyristor 5 will be locked, which means that the load supply circuit 18 will be broken.

Claims (1)

A VARIABLE VOLTAGE VARIABLE TRANSFORMER, containing a regulator connected between the input and output pins of the device, made in the form of a diode bridge, in the diagonal of which the thyristor is connected, that, in order to reduce high-frequency noise and increase reliability, the control node contains a transistor, a resistor in the base transistor circuit, a potentiometer, the first and second th diodes, storage capacitor, B-trigger, filter capacitor, rectifier diode, Zener diode, the first and second limiting resistors, while the transistor is connected to the emitter with the control input of the thyristor of the regulator, the collector is connected to the positive output of the diode bridge of the regulator, and the base is connected to the th output of the B-flip-flop via a resistor, 6 - the output of which is connected to the average output of the adjustment potentiometer, the first diode is connected to one extreme output of the anode The second diode is connected to the other extreme terminal of the potentiometer by the cathode, the cathode of the first diode and the anode of the second diode are connected to the B input of the B-flip-flop, between the B-input and the 0-output of the B-flip-flop The capacitor, K- and 3-inlets and the common output of the B-flip-flop are connected to the negative terminal of the regulator's diode bridge; The B-trigger input is connected to the anode of the rectifier diode and the positive terminal of the Zener diode, the negative terminal of the latter is connected to the common output of the B-trigger, the first limiting resistor is connected in parallel with the zener diode, The second limiting resistor is connected by one pin to the anode of the rectifier diode, and the other pin to the pin for connecting the load that is connected to the pin for connecting the power supply. 869861 I L 5 > 1 1198698