SU1274087A1 - Converter - Google Patents

Abstract

The invention relates to the field of electrical engineering and can be used in secondary power sources. The purpose of the invention is to increase reliability and efficiency. The converter consists of a power amplifier with transistors 1.2, a current sensor 3, an output transformer 4, a rectifier with filter 5, capacitive dividers 6, 7, a master oscillator 8, a pulse-width modulator 9, a pulse shaper 10, a threshold element 11. Wwe (L

Description

The pores of a switch element 12, protection triggers 13, 14, delay elements 15, 16, balancing triggers 17, 18, logical three-input elements And 19, 20 provide protection to the transistors of the power amplifier by ensuring symmetrical operation over 7 half periods. Continuous balancing takes place throughout the entire duration of the action of frig-narrow. The magnitude of the max, the current through the transistors, can be set by the reference level of the threshold elements and adjusted. 2 Il.

The invention relates to electrical engineering and can be used in secondary power sources. The purpose of the invention is to increase the reliability and efficiency of the converter. FIG. 1 shows the converter circuit; in fig. 2 - timing diagrams explaining the operation of the scheme. The converter consists of transistors Ii 2 power amplifier, current sensor 3, output transformer 4, rectifier with inductive capacitive filter 5, capacitive dividers 6 and 7 of master oscillator 8, modulator 9 pulse-oscillator, pulse generator 10, threshold elements II and 12, protection triggers 13 and 14, delay elements 15 and 16, balancing triggers 17 and 18, logical three-input elements AND 19 and 20. The circuit operates as follows In the nominal operating mode, the signals from the current sensor outputs do not exceed the reference level of the threshold elec 11 and 12. At the same time, the protection triggers 13 and 14, delay elements 15 and 17, balancing triggers 17 and 18 are in the initial state and do not affect the passage of the control signals from the output of the pulse-width modulator 9 through the loop The elements are 19 and 20 in the input circuits of the transistors 1 and 2 of the power amplifier. If the current of one of the transistors of the power amplifier, for example, transistor 1, at time t (see Fig. 2) exceeds a predetermined value, the signal from the first output of current sensor 3 exceeds the reference level of the threshold element 12 and converts it to operating condition (U,). The output of the threshold element 12 puts the protection trigger 14 into the operational state (IC). The protection trigger 14, with its output signal at time t, locks the logic element 20 and, therefore, locks the transistor 1 of the power amplifier until the end of the transformation half-period t (i, i, i). At time t, the protection trigger 14 returns to the initial state (u, φ) by the output signal of the pulse driver 10 (i, p). At time t, the output signal of the protection trigger 14 arrives at the input of delay element 16. Delay element 16 at time t (produces a short pulse. This pulse is shifted relative to time tj by a time equal to half of the conversion period (T / 2) of the converter (U, j). The output signal of time delay element 16 converts to state balancing trigger 18 (U, g). Balancing trigger 18 with its output signal at time tg locks logic element 19 and, therefore, locks transistor 2 of the power amplifier until the end of the transformation half-period tg (U, 12) and the tg balancing trigger 18 returns to the initial state (U, g) by the output signal of the driver 19 (U, o). In the case that the current of the transistor 2 of the power amplifier exceeds a predetermined value, the circuit works similarly. protection trigger 13 is operational. Output

31

the signal of the latter closes the AND 19 gate and, consequently, the transistor 2 of the power amplifier to the end of the converter half-period. At the same time, the output signal of the protection trigger 13 triggers a delay element 15, which, after a time equal to half the conversion period (T / 2), produces a short pulse to start the balancing trigger 17. The latter triggers and closes the AND 20 gate and, therefore, the transistor 1 power amplifier until the end of the half-cycle conversion. The resetting of the flip-flops 13 and 17 to the initial state is carried out by the output signal of the pulse generator 10.

In this scheme, the transistors of the power amplifier of the converter are protected at the moment of the occurrence of an overcurrent (in the same half-cycle of conversion), and a continuous balancing of the operation of the power amplifier occurs during the entire time of the overload action. These factors eliminate the overload of the transistors of the power amplifier over current, since the maximum current through the transistors can be set, for example, by the reference level of the threshold elements and can be adjusted. This provides increased efficiency and reliability of the converter in comparison with the prototype.

740874

Claims (1)

Invention Formula A converter containing a master oscillator connected through a pulse-width modulator and a driver of 5 pulses with a power amplifier made on two transistors and an output transformer, an output rectifier with a filter, a current sensor transistor power amplifier with  two outputs and a threshold element, characterized in that, in order to increase reliability and efficiency by providing a power amplifier that is symmetrical over half-periods, a second threshold element, two protection triggers, two delay elements, two balancing triggers, two three-input logic elements are introduced into it And, with the outputs 0 current sensors connected to inputs corresponding threshold elements whose outputs are associated with the first inputs of the corresponding protection triggers, the outputs of which are connected to the first inputs of the corresponding elements AND and the inputs of the corresponding delay elements whose outputs are connected to the first inputs of the corresponding balancing triggers, outputs 0 of which are connected to the second inputs And elements, the outputs of the pulse-width | Nogo modulator are connected to the third inputs of the elements, the outputs of which are connected to the control inputs of the corresponding transistors of the power amplifier, and the second inputs of protection triggers and balancing triggers with the pulse driver output.