SU1663720A1 - Constant voltage transistor converter - Google Patents

Abstract

The invention relates to electrical engineering, in particular to converter equipment, and can be used in the secondary power supply sources of various electronic equipment. The goal is to improve the weight and size indicators, increase efficiency and reliability by protecting against overloads. The converter is made according to a half-bridge circuit on transistors 1, 2 and capacitors 3, 4. Throttle 15 prevents the transistors 1, 2 from going out even when the core of the output transformer 5 is saturated. The diodes 16, 17 injected close the circuit of the drossel 15 current circuit. dynamic losses when turning on transistors 1, 2. 1 Il.

Description

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The invention relates to electrical engineering, more precisely to converter equipment, and can be used in the secondary power supply sources of various electronic equipment.

The purpose of the invention is to improve mass-size parameters and increase efficiency and reliability by protecting against overloads.

The drawing shows an electrical circuit of a DC to DC transistor converter.

The device contains the first and second transistors 1 and 2, the first and second capacitors 3 and 4, the output transformer 5, the secondary windings 6 and 7 of which through the rectifier 8 and the filter 9 are connected to the output terminals 10 and 11. The first input terminal 12 is connected to the collector of the first transistor 1 and one output of the first capacitor 3, the second input output 13 of the subconnectors to the emitter of the second transistor 2 and one output of the second capacitor 4. The middle point of the first and second capacitors 3 and 4, formed by their other outputs, is connected to one output primary winding 14 of the transformer 5. A throttle 15 is also inserted in the converter, connected between the emitter of the first and the collector of the second transistor 1 and 2. The anode of the inserted first diode 16 is connected to the cathode of the inserted second diode 17 and to another terminal of the primary winding 14 of the transformer 5. Cathode the inserted first diode 16 is connected to the emitter of the first transistor 1, the anode of the inserted second diode 17 is connected to the collector of the second transistor 2. Parallel to the primary winding 14 of the power transformer 5, the inserted capacitor 18 is connected.

Constant voltage to constant voltage converter works as follows.

The first and second transistors 1 and 2 operate alternately and are controlled by a pulse of a voltage across a half of the switching period of the transistors 1 and 2.

Suppose that the first transistor 1 is open and the second transistor 2 is closed. In this case, the primary winding 14 of the transformer 5 is applied a voltage equal to Epit / 2. where Epit is the voltage source of the converter power supply connected to input terminals 12 and 13. The current flow path of the primary winding 14 of the power transformer 5 is closed along the circuit 3 - 1 - 15 - 17 - 14-3.

During the open state of the first transistor 1, the corresponding rectifier diode 8 and the energy

from the secondary winding 6, the transformer Agora 5 enters the filter 9 and the converter load connected to the output terminals 10 and 11. At the same stage, the current in the choke 15 and in the primary winding 14 of the transformer 5 increases, energy is accumulated in the choke 15, and magnetization the transformer core 5 in the forward direction. In this case, the diode 16 is locked. In addition, when transistor 1 is turned on, capacitor 18 is charged to a voltage equal to -; р-.

The inrush current of the capacitor 18 is limited by the choke 15.

When the transistor 1 closes under the action of the emf self-induction arising on the primary winding 14 of transformer 5, the process of recharging capacitor 18 begins. The recharging current of capacitor 18 rises in proportion to the decrease in the collector current of transistor 1. As the capacitor 18 recharges, the voltage on it increases slowly, therefore, the dynamic losses during the closing of the transistor 1 and the rate of increase of the voltage on the first transistor 1 are reduced.

Under the action of the self-induced EMF arising on the winding of the choke 15, the diodes 16 and 17 are opened and the DC link of the choke 15 is closed. A voltage equal to Epit is applied to the closed transistor 1.

At the moment when the transistor 2 opens, current flows through the primary winding 14 of the transformer 5, which closes along the circuit 4-14-16-15-2-4, a charge of the capacitor 18 occurs. At the same time, the primary winding 14 of the transformer 5 is applied voltage

equal to -, and the corresponding diode of the rectifier 8 is in a conducting state and the energy from the secondary winding 7 of the transformer 5 is fed to the filter 9 and the load of the converter. At the same stage, the current in the inductor 15 and in the primary winding 14 of the transformer 5 increases, there is an accumulation of energy in the inductor 15, as well as the magnetization of the core of the transformer 5 in the opposite direction. In this case, the diode 17 is locked.

When closing the transistor 2 under the action of the EMF of self-induction arising on the primary winding 14 of the power transformer 5, the process of recharging the capacitor 18 begins. The recharging current of the capacitor 18 increases in proportion to the decrease in the collector current of the troanzistor 2 therefore, the dynamic losses during the closing of the transistor 2 and the rate of increase of the voltage across it are reduced.

Under the action of the self-induced EMF arising on the winding of the choke 15, the diodes 16 and 17 are opened and the DC link of the droplet 15 closes. A voltage equal to Epit is applied to the closed transistor 2.

At the next time point, transistor 1 opens again, and the described processes are repeated.

Thus, the converter allows to increase the reliability due to the presence of throttles in its input circuit, i.e., an element in which instantaneous changes of the winding current are impossible. This prevents the power transistors from going out of operation even if the core of the power transformer is saturated due to a failure in the circuit control or interference in the supply voltage, and also reduces the number of elements in the control circuit by simplifying it. The increase in reliability is also due to the reduction in the number of elements in the smoothing filters of the voltage channels when building on the basis of the proposed solution of a multichannel power source, since the proposed technical solution only uses capacitive filters in the channel filters.

In addition, the efficiency is increased due to the fact that the overloading of the diodes of the rectifier of the converter is reduced during the period of recovery of the reverse resistance of the diodes of the rectifier. Magnitude

These overloads are limited by the choke in the primary converter circuit. Due to the introduction of an additional capacitor connected in parallel to the primary

winding of the power transformer, reduced dynamic losses when closing the power transistors of the converter.

Weight and size are also improving.

performance due to the fact that in the presence of a variety of loads, i.e., when a constant-voltage transistor converter is executed by a multichannel one, it is possible in the filters of such a converter

use only capacitive filter.

Claims (1)

Claims of the Inverter DC Voltage Converter, made half-bridge circuit, the DC diagonal of which is connected to the input terminals, and the diagonal of the alternating current to the primary winding of the output transformer, the secondary winding of which through the rectifier and filter is connected to the output terminals, and connecting the power circuits of series-connected transistors forms one of the pins of the alternating current diagonal, characterized in that, in order to improve the weight and size efficiency and reliability by overload protection, the respective diodes are inserted into each of the mentioned power circuits of the transistors, which form a series circuit that is shunted by the injected choke, while the conductivity of the diodes is opposite to that of the transistors, and the primary the winding of the output transformer is shunted by an injected capacitor.