SU1065997A2 - D.c. voltage convereter - Google Patents

Abstract

1. CONVERTER VOLTAGE CONVERTER according to ed. St. No. 978293, characterized in that, in order to heal reliability, inserted chains of a series-connected diode and a capacitor are connected parallel to the primary winding of each output transformer, the first terminals of the capacitors of these chains are connected to the connection points of the key element with the first output of the primary winding of the corresponding output transformer, and a current-limiting element is switched on between the points of connection of the second terminals of the capacitors with the diode; 2. A converter according to claim 1, characterized in that a resistor is used as a current limiting element. 3. A converter according to claim 1, characterized in that a choke is used as a current limiting element. (L

Description

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The invention relates to electrical engineering and may be used in secondary power supply systems for converting direct voltage.

According to the main author. St. No. 978293 is known a constant voltage converter f containing two successively connected single-phase inverter cells to the input terminals, each of which contains a key element connected to the dermal winding of the output transformer, the secondary winding of which is connected via a corresponding rectifier to a common LCD filter whose output connected to the output pins, and the connection point of each key element with one of the pins of the primary winding of the corresponding output transformer connected to the corresponding first electrode of the regenerative diode, while parallel to the input pins a capacitive voltage divider is connected, the midpoint of which is connected to the other terminals of the primary windings of the output transformers, and each of the extreme points of this voltage divider is connected to the corresponding second electrodes of the regenerative diodes. Under no circumstances should the key elements of the DC / DC converter be removed from the area of safe operating modes, you must use RCD chains to reduce the voltage rise rate on the closing key element l.

 A disadvantage of the known voltage converter is that the voltage amplitude at the RCD capacitors is equal to the voltage of the converter power supply. In addition, an individual RCD chain must be established for each key element. Large 1 dynamic losses when switching on key elements are caused by large values of and /) current through key elements when discharging RCB chain capacitors and cause low efficiency of a known constant voltage converter. In addition, at large capacitances of the RCD capacitors in the resistors, significant active power is selected, which leads to a deterioration in the thermal conditions of the elements and a decrease in reliability and converter.

The purpose of the invention is to increase the reliability of a constant voltage converter by decreasing the voltage amplitude on capacitors RCB of chips that change the trajectories of the operating points of key elements.

nocTaBJi6; HHaH goal is achieved by the fact that in a constant voltage converter parallel to the primary winding of each output transformer there are connected chains of a series-connected diode and a capacitor, and the first terminals of the capacitors of these chains are connected to the points of connection of the key element with the first output of the primary winding of the corresponding output transformer, .a a current-limiting element is connected between the points of connection of the second terminals of the capacitors with the diodes.

A resistor can be included as a current-limiting element.

In addition, a choke may be included as a current-limiting element.

FIG. 1 shows an electrical circuit of a DC converter; in fig. 2 - temporary diagrams of voltages and currents, illustrating his work.

The constant voltage converter (Fig. 1) contains two inverter cells connected in series to the converter output terminals. The first inverter cell contains the key element 1, the input capacitor 2, the output transformer 3 with the primary winding 4 and the output winding 5, one-rectifier rectifier b and the recovery diode 7. The second inverter cell contains the key element 8, the input capacitor 9, the output transformer 10 with the primary a winding 11 and an output winding 12, a single-ended rectifier 13 and a recovery diode 14. Both inverter cells work in antiphase on a common diode-inductive capacitive filter 15-16-17.

A load 18 is connected to the output pins of the converter. The input capacitors 2 and 9 form a capacitive voltage divider, the midpoint of which is connected to the primary windings of output transformers 4 and 11, and the corresponding electrodes of the recovery diodes 7 and 14 are connected to each extreme point of the second voltage divider . In parallel with the primary winding 4 of the outfeed transformer 3, a chain of series-connected

diode 19 and condensate 20. Paoallelno primary winding 11 of the output transformer 10 is connected to a chain of series-connected diode 21 and capacitor 22. The first lead of the capacitor 20 is connected to the attachment point of the key element 1 with the primary winding 4 of the output. transformer 3, and the first lead of capacitor 22 is connected to the point of connection of the key element 8 with the primary winding 11 of the output transformer 10. Between the connection points of the second leads of capacitors 20 and 22 with diodes 19 and 21 respectively, an additional resistor is included Instead of a resistor 23 an additional choke may be included 2. The DC / DC converter operates as follows. Key elements 1 and 8 operate alternately and are controlled by voltage pulses shifted by half the switching period of the key element of each inverter cell. Suppose that key element 1 is open and key element 8 is closed. In this case, a voltage equal to EPIT / 2 is applied to the primary winding 4 of the transformer 3; (where is the power supply voltage of the converter connected to the input terminals). The primary flow path of the primary winding 4 of the transformer 3 is closed on the circuit: 2-1-4-2. During the open state, the key element 1 conducts a rectifying diode b and the energy from the secondary winding 5 of the transformer 3 is supplied to the output choke 16 and the load 18 of the converter. In addition, when the key element 1 is opened, the charging current of the capacitor 20 begins to flow, which closes along the circuit 2-1-20-23-21-2. During the open state of the key element 1 (the time interval t - t in Fig. 2), the capacitor 20 is charged to a voltage equal to, and the maximum charge current of the capacitor is limited by the resistance of the resistor 23. When the key element 1 is turned off ( time t, 2 under the influence of the EMF of self-induction, diode 19 is opened. the process of recharging capacitor 20 begins. At the same time the rectifying diode 6 is closed. The recharging current of the capacitor increases in proportion to the decrease of the current of the key element 1. For m reloading the capacitor, the voltage on the capacitor increases slowly, and therefore the dynamic losses when the key element 1 is turned on and the voltage increase rate on the key element 1 decreases, at time t (Fig. 2) the key element closes completely and its current becomes zero. The process of overcharging the capacitor 20 in the interval continues at the expense of the energy accumulated in the inductance of the magnetization of the transformer 3. At the moment of time 1, the voltage on the capacitor 20 reaches the value E ,, - / 2 and the overcharge current Yes, the capacitor 20 s: Ivanovits equal to zero. At the same time, under the influence of the self-induced EMF of the primary winding4 of the transformer 3, the recovery diode 7 is opened and the process of recovering the energy accumulated in the magnetizing inductance of the transformer 3 begins, the energy recovery in the magnetization inductance of the transformer 3 begins, time interval i-; The -t, while the voltage on the key element 1 is fixed at the level of the time i, the said process of energy recovery accumulated in the inductance of the magnetization of the transformer 3 is terminated. In the time interval ig - t, the discharge of capacitor 20 to the primary winding 4 of transformer 3 occurs, while the discharge current is closed along the circuit: 20-23-21-4-20. At time {7, the voltage across the capacitor 20 reaches zero. The discharge current of the capacitor 20 flowing in the interval across the winding 4 of the transformer 3 magnetizes the core of the transformer 3 in the direction opposite to magnetizing it when the key element is open. At time t, key element 1 re-opens and the processes are repeated. In the second inverter cell, the processes proceed similarly. At the time point ty, the key element 8 opens and current flows through the primary winding 11 of the transformer 10, which closes the loop: 9-11-8-9. At the same time, a voltage equal to / 2 is applied to the primary winding 11 of the transformer 10, and the rectifying diode 1T is in a conducting state and the energy from the secondary winding 12 of the transformer 10 is supplied to the output choke 16 and the load of the converter 18. In addition, during opening the key element 8 begins to flow a charge current of the capacitor 22, which closes the circuit: 9-19-23-22-8-9. During the open state of the key element 8, the capacitor 22 is charged to a voltage equal to Epit / 2 / while the maximum charge current of the capacitor is limited by the resistance of the resistor 23. When the key element 8 is turned off, at time ig (Fig 2) The primary winding 11 of the transformer 10 induces an emf of self-induction, under the influence of which diode 21 opens and the process of recharging capacitor 22 begins. At the same time, the rectifying diode 13 closes. At time 3, the key element 8 closes and its current becomes zero. In the time interval ti) - f.o, recharging of the capacitor 22 occurs due to the energy accumulated in

Claims (3)

1. DC CONVERTER by ed. St. No. 978293, characterized in that, in order to increase reliability, parallel to the primary winding of each output transformer are connected FIG. / introduced circuits from the diode and capacitor connected in series, the first terminals of the capacitors of these chains are connected to the connection points of the key element with the first terminal of the primary winding of the corresponding output transformer, and a current limiting element is connected between the connection points of the second outputs of the capacitors with diodes ·. 2. Converter pop. 1, characterized in that a resistor is used as a current-limiting element. , 3. Converter by π. 1, characterized in that a choke is used as a current-limiting element. SLL <„, 10659.97>