SU1683145A2 - D c/d c voltage converter - Google Patents

Abstract

The invention relates to electrical engineering and can be used in secondary power sources. The purpose of the invention is to increase reliability by reducing the average voltage across the transistor. The converter contains a controllable power switch 2, connected via diode 6 and the primary winding 5 of the output transformer to the input terminals, and the node for limiting the voltage rise rate on the switch 2, made in the form of an LCD three-port network. The goal is achieved by shunting diode 6 by resistor 12 when choosing its resistance from the ratio 2V Lr + C} / C R T / C, where C is the capacitor capacitance 9; Ck - the capacity of the collector junction switch 2jLg and Lf inductance of drossel 10 and winding 5; T - key switching period. The advantage of using a converter in power supplies is realized in reducing the negative effect on equipment. 2 Il.

Description

figure 1

The invention relates to the field of electrical engineering, it can be used in the source of secondary power supply and is an improvement of the device according to the author. cn N. 1330713.

The chain of inventions is to increase reliable. ™ by reducing the average voltage across the transistor.

Figure 1 is an electrical circuit diagram of the device; from FIG. 2, diagrams of stresses (R. — for a known device, b — for a proposed one).

In FIG. 2, the following notation is used: r3hl — the duration of the switch on of the key;

t is the duration of the front off;

1rae - the duration of the discharge inductance of the transformer;

tn pause duration;

UK is the voltage at the key collector;

UOOM is hard not to pull out the transformer primary winding,

The fan (Fig. 1) contains a power switch (transistor 2) connected to the input power supply 1, controlled by the control unit 3, an electrical load 4, for example, an output transformer, the primary winding 5 of which is connected via a diode 6 to the power switch output -ia 2 v- is connected to another input terminal 1, the LCD three-terminal consists of diode 8, capacitor 9 and a series circuit of droplets 10 and diode 11. A series circuit of elements 8 and 9 is connected between input terminal 7 and the connection point of key 2 and diode 6, and LD-e 10-11 triple A ynik is connected to choke 10 and to input terminal 1. Diode 6 is bounded by resistor 12.

The Converter operates as follows.

When key 2 is opened, the rate of increase of voltage on it is terminated by capacitor 9 — the voltage on the left capacitor plate remains at the level of the supply voltage (diode 8 is open) until the end of inductability 5 is completed.

The voltage on key 2, in accordance with the operation of the proposed converter, reaches 2Unnr + AD, where the overvoltage (Jmn + Au is determined by the specific type of converter (with direct or reverse connection of the diode), as well as the mode of operation, and the inductance value neither

After the end of the inductance discharge 5, the voltage at the output of the primary winding Wabm drops from oscillatory transients (Fig. 2, b) to the level

supply voltage Up. The voltage UK on the key 2 along the resistor circuit 12 drops to the same value, but with the time constant Ri2 Sk. An applied voltage drop (Unv-T + AD) is applied to the capacitor 9 of the LCD three-port network. However, since the capacitor 9 recharge circuit (inductive-diode branch 10-11, input busbars, transformer winding 5 and resistor 12) has a resistor greater than or equal to a critical level (condition 1), there is no overcharging process and the voltage across its LD branches (and the left lining of the capacitor 9) aperiodically decreases to zero.

When the key 2 is closed with the negative voltage surge applied to the LD-zetwy 10-11, the capacitor 9 is recharged (left facing from the potential -Opit to + Upit), and upon subsequent opening the processes are repeated.

Thus, due to shunting of the diode 6, the voltage on the key 2 after its opening is not frozen at the level of 2Unnr + AU, but decreases with a constant time r Ri2 CK (comparative diagrams a and b, Fig.2), and, consequently, decreases the average value of the voltage on the key (1.3-1.8 times) increases the duty cycle and increases the reliability of the key.

In addition, the introduction of resistor 12 actually connects parallel to the winding 5 a damping circuit, represented by resistor 12 and capacitance Ck, which effectively damps the parasitic oscillatory transient on winding 5 when turning off the switch 2. With the usual connection of such a damping chain, additional

proportional losses (С - capacitance introduced with a damping chain).

When damping - with the selection of the resistance of resistor 12, the capacity of the collector junction already used in the circuit is used (one way or another, the charge is reused in each key operation cycle), which ensures the efficiency of the process, since there is no additional loss to the efficiency of the converter not reduced. The advantage obtained when using a converter in power supplies is realized in reducing the negative effect (associated with the specified type of interference) on the equipment.

Claims (1)

Invention Formula Constant voltage converter on avt. Ns 1330713, characterized in that, in order to increase reliability by reducing the average voltage across the transistor, the blocking diode is shunted by an additionally inserted resistor, the resistance of which is selected from YLT + LQ 2I С Vk where C is the capacitance of a three-pole capacitor; Ck - the capacity of the collector transition key; Lfl and C - the inductance of the throttles of the three-pole and the primary winding of the output 0 transformer; T-period to l. conversion period Schig.2