SU1517103A2 - D.c. voltage converter - Google Patents

Abstract

The invention relates to electrical engineering, in particular, to converter technology, can be applied in the sources of secondary power supply of electronic equipment. The purpose of the invention is to increase reliability and reduce the level of generated high-frequency interference by limiting the collector current pulses in cell transistors. A common LCD filter 3 of the converter contains two throttles 16, 17 on separate magnetic cores, two recovery diodes 18, 19, and a common smoothing capacitor 20, each filter choke made with a three-winding one. At the same time, the minimum volume of the smoothing capacitor of the converter filter is achieved with the ratio of the number of turns of the first and second windings of each throttle of the smoothing filter equal to the transformation ratio of the output transformers of the corresponding single-cycle cells. 1 hp f-ly. 3 il.

Description

(61) 951596

(21) 4367548 / 24-07

(22) 01/25/88

(46) 10/23/89. Bul No. 39

(71) Vinnitsa plant of radio equipment

(72) S.D. Rudyk and V.E. Turchaninov

(53) 621.314.57 (088.8)

(56) USSR author's certificate 951596, cl. H 02 M 3/335, 1982.

(54) CONSTANT VOLTAGE CONVERTER

(57) The invention relates to electrical engineering, in particular, to converter technology, can be applied in sources of secondary power supply of electronic equipment. The purpose of the invention is to increase the reliability and

reducing the level of generated high frequency noise is confusing to limit the collector current pulses in cell transistors. A common LCD filter 3 of the converter contains two droplets 16, 17 on separate magnetic conductors, two recovery diodes 18, 19, and a common smoothing capacitor 20, each filter choke made with a three-winding one. At the same time, the minimum volume of the smoothing capacitor of the converter filter is achieved with the ratio of the number of turns of the first and second windings of each throttle of the smoothing filter equal to the transformation ratio of the output transformers of the corresponding one-stroke cells. 1 hp f-ly, 3 ill.

a 5

ABOUT)

SP

about with

N)

The invention relates to electrical engineering, in particular to converter equipment, can be applied to sources of secondary electrical power. no electronic equipment and is an improvement device according to the author. St. No. 951596.

The aim of the invention is to increase reliability and reduce the level of generated high-frequency interference by limiting the collector current pulses in cell transistors.

FIG. Figure 1 shows a DC voltage converter with single-ended cells connected in parallel to a power source; in fig. 2 is a variant of a circuit in which single-ended cells are connected to a power source in series; in fig. 3 is a timing diagram explaining the operation of the DC / DC converter of FIG. 1, with single-phase antiphase control, Mi cells.

The constant voltage converter (Fig. 1) consists of two one-stroke converter cells 1 and 2, one full-phase work on a common smoothing filter 3.

Each of the single-ended conversion cells consists of a power switch 4 (5) connected to a power trailer} 1 transformer 6 (7) containing a primary 8 (9), a secondary 10 (11) and a winding 12 (13). In this case, the secondary windings 10 (11) of the output transformers 6 (7) are connected to the common smoothing filter through rectifying diodes 1A (15). A common smoothing filter 3 converter ((complete, SOSTOYTIM from other throttles 16 (17), two recovery diodes 18 (19) and smoothing capacitor 20. Moreover, each filter throttle is made with three windings, the first windings 21 (22) of which are connected in series with the primary windings 8 (9) of output transformers 6 (71 single-point cells 1 (2). One output of winding 23 (24) of each drossel filr is connected to the cathode of the corresponding recovery diode 18 (19). The connection point of the other output of the second winding of each throttle with the first output of three The winding 25 (26) throttle is connected to the corresponding rectifying diodes of one tactical converter cells.

) Q

5 0 5

Q

Q, 5

The second outputs of the third windings of the filter chokes 3 are combined and connected to the smoothing capacitor of the converter. Additional windings 12 and 13 of the output transformers 6 and 7 are connected to each other through a diode 27 and a resistor 28.

The output of the DC-DC converter is connected to the load 29. In each single-cycle converter cell there are additional elements for fixing the voltage on the power switches of the cells — additional windings of output transformers 30 and 31, additional windings 32 and 33 of chokes of converter and diodes 34 and 35 respectively.

The DC-DC converter variant (Fig. 2) differs from the previously described one only by the elements intended for fixing the voltage on the power keys of the single-ended cells.

Those elements for the converter (Fig. 3) are latching diodes 36 and 37 and capacitors 38 and 39 of the capacitive voltage divider.

The constant voltage converter (Fig. 1) operates as follows.

The power transistors 4 and 5 are turned on alternately, since the control voltages on their bases are out of phase 180 with respect to each other. When the positive pulse supplied to the base turns on the power transistor 4, the switching diode 14 starts to conduct and the energy is supplied to the output choke 16 and the load 29 of the converter. At this stage, the magnetizing current of the primary winding of the transformers increases, which flows through the serially connected primary winding 8 of the output transformer 6 and the first winding 21 of the throttles 16. This current in the interval (t, -tj, FIG. 3) magnetizes the core of the output transformer 6 in the forward direction direction. The accumulation of energy in the droplet of the smoothing filter at this time interval occurs due to the flow of currents; the first winding 2 - current collector of the power transistor 4, the second winding 23 - current of the secondary winding of the transformer 6.

51

At the same time interval, due to the emf on the winding 12, current begins to flow along the circuit 12-27-28-13-12, magnetizing the core of the output transformer 7 in the opposite direction by flowing the magnetizing current through the additional winding 13, At time tj to the base of the transistor A pulse is applied to the blocking voltage and it turns off. In this case, the rectifying diode 14 is locked and part of the energy stored in the inductor 16 is transferred to the converter load 29, a current is drawn along the circuit: 23-25 - parallel connection of the capacitor 20 and load 29 - rectification diode 18-23. This process occurs on a time interval (

Simultaneously with these processes, starting from the time t /, the energy accumulated in the core of the output transformer 6 is recovered to the converter power supply through a circuit: 30-34 - converter power supply - 32-30. In this case, on the time interval () on the windings of the output transformer, an emf arises at a sign opposite to that induced on them at the time interval (t, -t). At the moment of time t - the process of energy recovery of the core of the output transformer 6 ends and the emf on its windings drops to zero,

At time t, the transistor 5 of the single-ended converter cell 2 is opened and, due to the emf, winding 13 begins to penetrate the current along the circuit 13-12-27-28-13, and the core of the power transformer 6 is magnetized in the opposite direction. This process goes on a time interval (t4-t5). At time t /, a positive pulse is applied to the base of the transistor 4, and the processes in the single-step converter cell 1 are repeated. All processes in the single-ended converter cell 2 are similar, but with a phase shift of 180,

The processes in the variant of the proposed converter (Fig. 2) are carried out in a similar way except for the fact that the energy accumulated in the core of the output transformer 6 (7) is recuperated into a power source

036

A cotton fly goes along the chain 8-39-37-21-8 (9-22-36-38-9).

By changing the ratio of the turns of the second and third windings (23, 25, and 26) of each drossel, the energy conversion functions are redistributed between the output transformers and the throttle of the output filter of the converter, and therefore, the redistribution of the volumes occupied by these elements.

When the ratio between the number of turns of the first and second windings of each filter throttles changes, the amplitude and shape of the current through the smoothing capacitor of the converter filter changes.

The continuous current condition of the output filter capacitor is determined, i.e. condition of the mode corresponding to the minimum amplitude of the current flowing through the capacitor 20.

Wo wj

Denoted by p tt tt to

W “o W ,,

transformation effect of output transformers of single-ended converter circuits;

Assuming that the losses in all elements of the converter are zero, both single-ended conversion cells are loaded symmetrically, get the ratio

1k-p-,

(ABOUT

where IK is the average value of the collector current of the power transistor switch in the closed state interval; IH is the magnitude of the DC load current of the converter.

The minimum current of the smoothing capacitor of the converter filter corresponds to the triangular shape of this current. As soon as there is a change in the amplitude of the currents of the windings 25 and 26 of chokes 16 and 17 at the moments of switching (times t ,, t.), A rectangular component appears in the current of the smoothing capacitor 20 and the current increases. Thus, the condition of a non-symmetrical current through the capacitor 20 and the condition of its smallest volume is equality

nh, 5 (Wa4) W55 (wu) 21k-n (2) where 1 .. is the average

"/ (one/

 current flowing

on winding 25 (26)

throttle at the stage of energy storage;

I- average value

) the current flowing through the winding 25 (26) drossel at the stage of energy consumption. From the condition of equality of the ampere turns of the chokes of the smoothing filter on the time intervals of the closed and open states of the power switches, it follows% g (“) (P) (g

(7. From where

(3)

t. U

k 71 (11)

OR

I.n.W, 3 (j, 20

Wtuzt)

 P

(four)

Wild)

From expression (4) it follows that when the ratio of the number of turns of the first and second windings of each smooth filter drossel is equal to the transformation ratio of the output transformers of the corresponding single-cycle cells, the amplitude of the current through the smoothing filter capacitor and, consequently, its volume is minimal. Fig. 3 shows diagrams corresponding to the fulfillment of condition (4), the dashed line shows diagrams for the case of violation of this condition,

Constant voltage converter, as compared with the known technical solution, has a number of technical and economic advantages: increased reliability. This is due to the fact that the winding of the throttle is present in the input circuit of each one-stroke converter cell, i.e. element, in which instantaneous changes in current are impossible, which prevents the power transistors from going out of order even when the cores of the output transformers of the converter cells are saturated. In addition, for the same reason, the pulsed overloads of the power transistors of the single-stage cells are limited when they are opened in the time interval corresponding to the recovery time of the reverse resistance of the rectifier diodes and the converter filter. An additional advantage is that when building on the basis of

the proposed technical solution of the stabilized power supply simplifies the control circuit of the converter and the formation of the basic signals of the power transistors, since there is no need for a severe limitation of the voltage pulse filling factors on the windings of the Output Transformers of the converter; reducing the level of high-frequency noise due to the reduction of pulse overloads of diodes of the secondary drivers and recuperative diodes of the output filter of the converter in the time interval corresponding to the recovery time of the reverse resistance of these diodes.

The magnitude of these overloads is limited due to the presence of throttles in the primary chains of single-ended conversion cells.

In addition, an additional reduction in the amount of smoothing capacitor is achieved when the condition

) We (.9)

W,

W,

P.

14 (1 +) (11)

With THIS, in the current of the smoothing capacitor of the filter, the converter has no rectangular component.

Claims (1)

1. Constant on-converter converter - aut. St. No. 951396, characterized in that, in order to increase reliability and reduce the level of generated high-frequency interference by limiting the collector current pulses in cell transistors, the common LCD filter of the converter contains two chokes on separate magnetic cores, two recuperating diodes and a common smoothing capacitor, each choke the filter is triple-winding, the first winding is connected sequentially with the primary winding of the output transformer of the corresponding single-cycle cell, one exit of the second winding connected to the corresponding recovery diode, the connection point of the other output of the second winding to the first output of the third winding is connected via a rectifier to the secondary winding of the output transformer of the corresponding one-cycle cell. 9151 7 10310 a second conclusions of the third windings of drog-sheni numbers of turns of the first and second mudflows are combined and connected to the common windings of each drossel; smoothing filter filter smoothing capacitor are equal to coefficients ra converter transformer output transformer2, the transducer according to claim 1, about t -pu corresponding single-ended characterized by the fact that the relationship. 2