SU1582302A2 - Stabilized ac voltage-to-dc voltage converter - Google Patents

Abstract

The invention relates to the field of electrical engineering and can be used as a power source. The purpose of the invention is to increase efficiency. The device consists of a transformer 1 with primary and secondary 2, 14, 16, 17, 15 windings, and the winding 2 is made with a midpoint connected to one of the outputs of the device. Through the resistors 12, 13 and rectifiers 18, 19 with filters 20, 21, diodes 8, 9, power transistors 3, 4, and control transistors 10, 11 are connected to the secondary windings, forming a full-voltage input voltage rectifier. A comparison circuit 6 is connected between the output terminals of the device, the amplifier output of which is connected to the base of the regulating transistor 7 connected between the middle point of the winding 2 and the anodes of the diodes 8, 9. The emitters of transistors 3, 4 are connected to the output of the device and the comparison circuit 6. The additionally introduced capacitor 22 is connected between the middle point of the winding 2 and the collector of the transistor 7. The introduction of the capacitor 22 (and its inclusion in the circuit of the device) allows to obtain a full opening of the power transistors with increasing SRI half-wave input voltage from zero to an output voltage, and decreases - from the output voltage to zero, and accurate maintenance of the constant voltage at the filter inlet 5 at an input voltage greater than the output. This ensures minimal losses in the power circuit. 5 il.

Description

The invention relates to electrical engineering and can be used as a stabilized source of power, for example, in low-voltage power circuits of computer power supply,

The purpose of the invention is increased efficiency.

Fig. 1 shows an electric circuit for stabilized conversion.

During one half-cycle of the alternating input voltage, the control transistor 10 is open by the unlocking voltage removed from the winding 14. Through the collector-emitter of the open transistor 10, the unlocking voltage from the winding 16 and the filter 20 opens the power transistor 3. The output

The alternating voltage gel in POSTIAN-JQ filter 5 produces a smoothing out; 2 is a voltage waveform (emitter-collector junction)

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20

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zk one of the power transistors | on

FIG. 3 - waveform at the input of the smoothing filter; Fig. 4 shows a voltage waveform U3) of one of the | power transistors; Fig. 5 shows an oscillogram at the input of a smoothing filter without an additionally introduced capacitor (all oscillograms are given in the stabilization mode of the output voltage).

The stabilized converter (AC to DC contains a transformer 1 with a primary winding connected to the mains supply and five secondary windings. A power | secondary winding 2 is made with a midpoint and connected to the collectors of power transistors 3 and 4, JQ emitters of which are connected via an output filter 5 to an output of the device and a comparison circuit 6 including an output voltage sensor with an amplifier (not shown) whose output h is connected to the base of the regulating transistor 7S whose emitter is connected with the middle point of the winding 2 and the output of the device, and the collector - with the anodes of diodes 8 and 9, the cathodes of which are connected to the bases of the control transistors 10 and 11 and the first terminals of the resistors 12 and 13, respectively, the second terminals of which are connected to the first terminals of the secondary windings 14 and 15,

Secondary windings 16 and 17 through full-wave rectifiers 18 and 19 and filters 20 and 21 are connected to the collectors of the power transistors 3 and 4, and the second leads to the collectors of the control transistors 10 and 11 and the second leads of the secondary windings 14 and 15, respectively. . The capacitor 22 is first connected to the collector of the regulating transistor 79 and the second to the middle point of the secondary winding 20

The Converter operates as follows.

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direct voltage. From the output of the output voltage sensor with an amplifier, the base of the regulating transistor 7 receives a feedback signal proportional to the difference between the output voltage and the reference voltage.

Depending on the magnitude of this signal, the current through the transistor 7 flowing through the current-open diode 8, resistor 12 and windings 14, 16 and 2, and the voltage across the capacitor 22, and the voltage across the capacitor 22, vary, and the capacitance of this capacitor is determined the base current of the control transistors 10 and 11, so that when the capacitor 22 discharges (charges) this current for at least one period of the input voltage, the voltage on it does not change significantly. When the input voltage rises from zero, the power transistor 3 opens and saturates first from the voltage on the filter 20, which through the winding 14, the resistor 12 and the control transistor 10 is applied to the base of the power transistor 3, and then the unlocking voltage removed from windings 14,

When the voltage on the base of the control transistor 10 voltage across the capacitor 22 is exceeded, a diode 8 is opened, the capacitor 22 is connected to the base of the control transistor 10. After that, the voltage on the base of the control transistor 10 remains constant despite the increase in the winding voltage 14, the transistors 10 and 3 are switched to the active mode. The output voltage repeats the voltage across the capacitor 22, since transistors 3 and 10 are connected with respect to the load according to the emitter follower circuit.

The difference between the output and input voltages is highlighted on the power transistor 3 (FIG. 2). When the voltage decreases on the windings 2 and 14 and the filter 20 to a voltage lower than the voltage on the capacitor 22, it closes

Q filter 5 produces a smoothing of

five

0

five

Q h o

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direct voltage. From the output of the output voltage sensor with an amplifier, the base of the regulating transistor 7 receives a feedback signal proportional to the difference between the output and the reference voltages.

Depending on the magnitude of this signal, the current through the transistor 7 flowing through the input voltage of the diode 8, the resistor 12 and the windings 14, 16 and 2 that is open in this half-period varies, and the voltage on the capacitor 22, the capacitance of this capacitor is determined by the base voltage. the current of the control transistors 10 and 11, so that when the capacitor 22 is discharged (charged) by this current for at least one period of the input voltage, the voltage on it does not change significantly. When the input voltage rises from zero, the power transistor 3 opens and saturates first from the voltage on the filter 20, which through the winding 14, the resistor 12 and the control transistor 10 is applied to the base of the power transistor 3, and then the unlocking voltage removed from windings 14,

When the voltage on the base of the control transistor 10 voltage across the capacitor 22 is exceeded, a diode 8 is opened, the capacitor 22 is connected to the base of the control transistor 10. After that, the voltage on the base of the control transistor 10 remains constant despite the increase in voltage on the winding 14 , the transistors 10 and 3 go into active mode. The output voltage repeats the voltage across the capacitor 22, since transistors 3 and 10 are connected with respect to the load according to the emitter follower circuit.

The difference between the output and input voltages is highlighted on the power transistor 3 (FIG. 2). When the voltage decreases on the windings 2 and 14 and the filter 20 to a voltage lower than the voltage on the capacitor 22, the diode 8 closes, the current increases sharply the base of the control transistor 10 and the transistors 10 and 2 are switched to the saturation mode. At the same time losses in them are minimal. When the input voltage passes through zero, the power transistor 3 closes on the base to the emitter junction, and the power transistor 4 opens due to the energy stored in the filter 21. The process then proceeds in a similar way.

Thus, the introduction of the capacitor 22 reduces the heating of the power transistors, increases the efficiency and reduces the losses in transistors 3 and 4 by eliminating the effect of increasing voltage U ke of power transistors 3 and 4 while reducing the input voltage.

As can be seen on the oscillograms of the voltage of the U3 transistor 3, given

FIG. 2

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Fig.Z

figs 3 and 4, this voltage in ike and ac in a device without a capacitor is much larger than with a capacitor. This leads to an increase in voltage at the input of the smoothing filter 5 and the output of the device and its shape, as shown on fig.Z and 5.

Claims (1)

Invention Formula Stabilized AC / DC converter on auth. No. 1403299, about tl and h and y - y and with the fact that, in order to increase efficiency, a capacitor was additionally introduced into it, one output of which is connected to the middle output of the first the secondary winding, and its second output is connected to the collector of the fifth transistor. FIG. four rm Phage. five