SU1220077A1 - Two-step converter with self-excitation - Google Patents

Abstract

The invention relates to secondary power sources with automatic elimination of the asymmetry of the operation of the converter's shoulders. The purpose of the invention is to improve the accuracy of balancing. In the device, throttles (dr) 19 and 20 are used in a mode with one-sided periodic saturation of their cores. The core dr 20 is re-magnetized under the action of the voltage of the winding 16 applied to its winding through the control junction of the transistor 4 and the diode 22. Others 19 re-warms in the opposite direction tg under the action of the voltage of the 17 fff divider (f

Description

through diode 23, Time (over magnetisation, Other 19, 20 is shorter than the remaking time of the core of the transformer 6. The introduction of an adjustable voltage divider (DN) 18 makes it possible to eliminate the asymmetry in the operation of the converter's shoulders due to the technological variation of the element parameters. Use of a capacitor 5 automatically

The invention relates to electrical engineering and can be used in converter equipment, in particular for powering electronic equipment.

The purpose of the invention is to improve the accuracy of balancing the operation of the converter shoulders by eliminating the effect of magnetic permeability scatter of the chokes cores. g

The drawing is a diagram

push-pull converter with self-excitation.

Two-stroke 1st converter contains capacitors 1 and 2, transistors 3 and 4, forming a transistor-capacitive bridge, a capacitor 5 that increases the stability of the measured state, a transformer 6 having a primary winding 7, a secondary winding 8 connected to a rectifier 9 with a capacitive filter 10 , the positive feedback windings 11 and 12, connected to the control transitions of the transistors through resistors 13 and 14, two identical auxiliary windings 15 and 16, to which the newly introduced voltage parts 17 and 18 are connected, are two identical often osdvigayuschih l dross 19 and 20, dividing diodes 21 and 22, additional diodes 23 and 24,

Let us first consider the processes occurring in the converter, without taking into account the effect of capacitor 5. In the considered converter, chokes 19 and 20 are used in the mode with one-sided periodic saturation of their cores, therefore the direction of the magnetization reversal of the core,

:,

20077

eliminates asymmetry caused by changes in load current and ambient temperature. The use of frequency diagrams x DN 17, 18 eliminates the need for the selection of cores chokes on magnetic permeability and expands the range of adjustment to eliminate asymmetry, 1 Il.

13

five

 at

35 40 25

thirty

the torus, it comes to saturation, is called the forward direction, and its opposite is called the reverse direction. We believe that there is no asymmetry in the operation of the converter’s shoulders and the transfer coefficients of parts 17 and 18 are the same, t. e, K | K,

Assuming that transistor 4 is open, then the winding 7 is connected through its power section to the capacitor 2, under the action of the voltage of which the core of the transformer 6 is rewired and through the winding 8 through the rectifier 9 with the capacitive filter 10 the energy is transferred to the converter output. Transistor 4 is open by the current flowing through its control junction and resistor 14 from winding 12, and transistor 3 is locked by the voltage of winding 11. The core of the throttle 20 is re-magnetized in the forward direction under the action of the winding voltage 16 applied to its winding through the control junction of the transistor 4 and the diode 22. At the same time, the core of the choke 19 is reversal reversal under the action of the output voltage applied to its winding through the diode 23. the voltage of the divider 17,

The time of magnetization reversal of each throttle should be less than the time of magnetization reversal of the core of the transformer 6.

At the moment of saturation of the core of the throttle 20 through its winding and the diode 22 from the winding 16 to the control junction of the transistor 4 receives a current pulse, causing it to be intensively locked. Voltage polarity changes

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on the windings of the transformer 6. Transistor 3 opens, the switch winding 7 to capacitor 1, under the action of the voltage of which the core of the transformer 6 remagines in the opposite direction of the SRI. Drossel 20 energy is recovered to windings 16 and 12 and resistor 14 through diode 22 , as a result of which the induction of its core changes from saturation to residual induction .. As soon as magnetic induction takes on the value of residual induction, diode 22 is closed and the output of divider 18 is connected to the winding of drossel 20 through diode 24, the voltage of which the throttle core is reversal in the opposite direction.

At the moment the core of the throttle 20 is applied, the magnetic induction of the core of the throttle 19 reaches a value approximately equal to the middle of the section + Br, BsJ of the hysteresis loop of the core material, which is determined by the choice of K 0.75. After changing the polarity of the voltage of the transformer windings, a stage of energy recovery accumulated by the choke 19 in the previous half-period of conversion begins at the output of the divider 17 through the diode 23. As soon as this stage of recovery ends, the diode 21 connecting the winding of the throttles 19 through the control junction of the transistor 3 is unlocked to winding 15, under the action of voltage of which, the core of the throttle re-magnetizes in the forward direction.

Further operation of the converter with the open transistor 3. passes as well as with the open transistor 4.

The use of a voltage divider 18 with an adjustable transmission coefficient in the range from 0 to 1 allows the magnetic induction value of the core of the throttle 20 to be set when reversing in the opposite direction at any point of the section, -Bs, the core material hysteresis loop, which in turn allows change the duration of the on state of transistor 4 with respect to the similar duration of transistor 3 (approximately 140% when used in the drossea

20077

l x ring cores from oxyfiber 2000 them). Consequently, adjustable voltage divider 18 allows eliminating asymmetry in operation of 5 converter shoulders due to technological variation in the parameters of transistors (direct voltage of the control transition, resorption time of excess carriers), diodes (direct voltage), chokes (induk0

five

0

qi saturation)

Capacitor 5 is used for the purpose of increasing the stability of the quantized state, i.e., the capacitor 5 is automatically eliminated asymmetry in the converter caused by a change in its load current, the ambient temperature.

The mechanism for eliminating asymmetry in the converter by capacitor 5 is as follows.

Suppose that transistor 4 is turned on and the duration of its on state (taking into account resorption time) is longer than that of transistor 3. As long as the core of the throttles 20 is at the same time, the capacitor 5 is charged to the amplitude value of the voltage of the winding 7 and does not affect the operation of the converter neither At the moment of saturation of the core of the throttles 20 into the circuit.base of transistor 4 through the diode 22 enters the locking current pulse.

5 in transistor 4, the process of resorption of excess carriers occurs, accompanied by a small increase in the collector voltage and a decrease in the voltages on the windings of the transfer matrix. Taking into account that when switching transistors the voltage on the capacitor 5 practically does not change, then an insignificant decrease in the voltage on the winding 8 causes a sharp decrease in the current of the rectifier 9. As soon as the voltage on the winding 8 decreases by an amount equal to the direct voltage rectifier 9, the latter is locked, disconnecting the load from the winding 8. Next, the transistor 4 is unobstructedly closed, and the core of the transformer 6 continues to oscillate in the original direction under

5 by the action of the energy of the charged capacitor 5 until the voltage at the latter becomes zero. Then growth stops

five

0

five

the polarity of the voltage on its windings and the start of charge of the opposite polarity of the capacitor 5 by the energy accumulated by the transformer 6. Since the voltage on the winding 11 is proportional to the voltage on the capacitor 5, then As it is charged, the transistor 3 opens, its charge is partially charged by the energy of the input source. At the moment when the discharge of capacitor 5 finishes, the transistor 3 is fully opened, connecting the winding 7 to the capacitor 1, as a result of which the cores of the transformer 6 and the chokes 19 and 20 are re-switched in the opposite direction, the rectifier connects the load circuit to the winding 8, the capacitor 5 op It does not affect the operation of the converter until the throttle core 19 is saturated. After its saturation, the transistor 3 and the rectifier 9 are locked, and the transformer core continues to re-magnetize in the same direction under the action of the voltage applied to the winding 7 in the capacitor 5. Only now this process takes longer, because at the time of the locking of the transistor 3 the magnetizing current of the transformer has smaller value than at the moment of locking the transistor 4, t, e. automatic balancing of the converter's shoulders occurs.

The use of frequency dividers in frequency-dependent circuits eliminates the need for selecting chokes for magnetic chokes

Editor N. Gunko

Compiled by I.Voytovich

Tehred L.Oleynik Proofreader E.Sirohman

1329/58

Circulation 631 Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Branch PIP Patent, Uzhgorod, st. Project, 4

permeability, which leads to simplification and reduction of production costs, in addition, the range of adjustment to eliminate asymmetry in the operation of the converter expands.

Claims (1)

Invention Formula Push-pull converter with self-excitation, containing a bridge, two arms of which are formed by a capacitor a transformer, the primary winding of which is bridged by a capacitor and connected to the diagonal of an alternating current, and the secondary winding is connected via a rectifier with a capacitive filter to the output terminals of the converter, and the positive feedback windings are connected through resistors to control transistors of the transistors, two single-winding frequency-setting droplets connected to the specified control transitions through the separation diodes and auxiliary windings of the transformer, and additional diodes, characterized in that To improve the accuracy of balancing the operation of the converter's shoulders by eliminating the influence of scattering of magnetic permeability cores on chokes, two resistive voltage dividers are introduced into it, one of which is adjustable, the input of each of them is connected to the corresponding auxiliary winding of the transformer, and the output through the specified additional diode to the winding of the corresponding throttle.