SU838976A1 - Voltage inverter - Google Patents

Description

The invention relates to electrical engineering, in particular to a constant voltage converter of one level or a variable or constant voltage. another level, and can be used in master oscillators and oscillators. Known transducers are known in which bias circuit 1 is introduced to improve the excitation. The circuit with the best excitation conditions 2 is also known. The disadvantage of this circuit is the degradation of the circuit when the transistors are connected in parallel in each arm, which is associated with equalizing characteristics transistor. The closest to the proposed by the technical essence is a voltage converter, the excitation of which is carried out by shunting the base-collector junction of the power transistor at the moment of applying the supply voltage containing the inverter cell on the power switching transistors, one of whose power electrodes are connected to the primary winding of the output transformer is a midpoint connected to one of the input terminals, and the other power electrodes are connected to the second input-: dc, a switching transformer, a starting unit with a starting transistor, a capacitor and a resistor. However, the excitation of the circuit of the specified voltage converter depends on the rate of rise, the supply voltage, and the excitation process is a single character. The purpose of the invention is to increase the reliability of drive inverter. The goal is achieved by introducing a second transistor, three resistors and an additional winding of a switching transformer, made with a midpoint through a parallel-connected capacitor and a resistor connected to one of the input terminals in the voltage converter, and the first electrodes of the starting transistors are connected to the ends of the primary winding of the switching transformer, the midpoint of which through a resistor is connected to one of the input terminals.

and the second electrodes are connected to the second input terminal, at. In this way, the control electrodes are connected to the ends of the auxiliary winding of the switching transformer through the inserted resistors.

The drawing shows the electric circuit of the proposed converter.

The converter contains an output transformer 1, the primary winding of which consists of two windings 2 and 3. The middle point 4 of the primary windings 2 and 3 of the output transformer 1 is connected to the input terminal 5 via a resistor b with the middle point 7 of the primary winding 8 and 9 of the switching transformer 10, and also through a parallel-connected resistor 11 and a capacitor 12 - with the midpoint of additional windings 13 and 14 of the switching transformer 10. The emitters of the power transistors 15, 16 and 17, 18 are connected to another input terminal 19. The ends 2 and 3 of the primary The coils of the output transformer 1 are connected via diodes 20 and 21 to the ends B and 9 of the primary winding of the switching transformer 10, which are connected to another input terminal 19 and to the midpoint of the secondary winding 10 through the power circuits of the starting transistors 22 and 23. The bases of the starting transistors 22 and 23 through the resistors 26 and 27 are connected respectively, with the ends of the additional windings 13 and 14 of the switching transformer 10, the ends of the secondary windings 24 and 25 of which through the resistors 28 -. 31 are connected to the bases of power transistors 15-18.

The voltage converter operates as follows.

When the power source is turned on, the charge of the capacitor 12 starts. The charging current flows through the resistors 26 and 27 and the base-emitter transitions of the starting transistors 22 and 23. Because of the inevitable technological and constructive variation in the parameters of the transistors 22 and 23, the WHO generation. At the same time, the capacitor 12 is charged almost up to the voltage of the power source and the voltage on the half of the additional winding of the switching transformer 10. At the end of the arming and starting, the transistors 22 and 23 are closed and in the further operation of the circuit accept. When the converter oscillates and the input voltage is present, the capacitor 12 is discharged into resistor 11. Moreover, as soon as the difference between the input voltage and the voltage across capacitor 12 exceeds the threshold voltage for the starting transistors 22 and 23, generation occurs.

The proposed device is advisable to use in the case of parallel connection of transistors in the shoulders of a voltage converter when it is necessary to obtain reliable excitation of the converter, especially with a smooth increase in the input voltage.

Claims (3)

Invention Formula A voltage converter that contains an inverter cell on power switching transistors, some of whose power electrodes are connected to the primary winding of an output transformer with a mid-point connected to one of the input terminals, and the other power electrodes are connected to the second input terminal, a switching transformer, trigger block with trigger transistor, capacitor and resistor, which is different in that, in order to increase the excitation reliability of the converter, a second a transistor, three resistors and an additional KoiviMyTHpyKBuero transformer winding, made with a midpoint through a parallel-connected capacitor and a resistor connected to one of the input terminals, the first electrodes of the starting transistors connected to the ends of the primary winding of the switching transformer, the midpoint of which is connected through the resistor to one of the input terminals, and the second electrodes are connected to the second input terminal, while the control electrodes are connected to the ends of an additional winding switching transformer. Sources of information taken into account in the examination 1. Basovsky v.F. Transistor Voltage Converters, Kiev, Technique, 1974, p. 30, Fig.9 a-d. 2. The same figure. 9 f. 3. USSR author's certificate number 478404, cl. H 02 M 7/537, 1975. Ago -d}