SU1644339A1 - Inverter with separate excitation - Google Patents

Abstract

The invention relates to converter technology and can be used in the development of secondary power sources. The goal is to increase reliability by reducing the transistor overload. The inverter contains a push-pull power amplifier with cross-connectors, which provide for the exclusion of through currents, as well as control transistors 4 and 5, having a conductivity type opposite to power transistors 6 and 7, which ensure the inverter to be turned off when overload conditions occur current in the load circuit. 1 il.

Description

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The invention relates to converter technology and can be used in the development of secondary power sources.

The goal is to increase reliability by reducing the transistor overload,

The drawing shows a diagram of the inverter.

The inverter contains a master oscillator 1, whose outputs through diodes 2 and 3 and control transistors 4 and 5. are connected to the bases of the power transistors 6 and 7, the collectors of which are connected to the primary winding of the transformer 8 with a midpoint which is connected to the first input, and the emitters these transistors 6 and 7 are connected to the second input terminal. In parallel with the power switches, lead-through circuits, consisting of capacitors 9 and 10, resistors 11-14, are connected. The connection points of resistors 11-14 through diodes 15 and 16 are connected to the bases of power transistors 7 and 6, respectively, in addition, the collectors of power transistors 6 and 7 are connected via diodes 17 and 18 to the bases of control transistors 4 and 5. To the base of power transistor 7 is connected to the node 19 run.

The inverter works as follows.

When the power is turned on, the start-up unit 19 in the form of a single-pulse generator generates an unlocking pulse for the initial launch of the inverter into the base circuit of one of the power transistors 6 and 7 (for example, 7).

The transistor 7 under the action of this pulse enters the saturation mode, while the control transistor 5 opens and maintains the transistor 7 in the open state (the diode 18 is also open). The power transistor 6 is in the closed state and a negative bias is applied to its base through diode 2 from a two-pole generator of rectangular external excitation pulses. The capacitor 9 of the outgoing circuit is charged from the power source through the winding of the transformer 8 to the voltage determined by the power source Ep. The capacitor 10 is discharged by the open transistor 7. The control transistor 4 is in the closed state, which is provided by the diode 17 and the fact that a negative bias from the oscillator 1 is applied to the emitter.

Consider the switching process of the inverter when the polarity of the input pulse of the excitation generator 1 is changed.

When applying a positive voltage to the emitter of the transistor 4 and the cathode of diode 2, the transistor 6 at the first time

is in the closed state because transistor 4 cannot open due to the voltage on the collector of transistor 6. At the same time, a pulse of opposite negative polarity is applied to the emitter of transistor 5. A negative potential through diode 3 contributes to accelerated resorption of charge carriers in the power switch base, which corresponds to its forced closing. In this case, the capacitor 10 is charged and removes part of the load current from the closing transistor. Increasing the voltage across the collector of the power transistor also provides for closing the control transistor 5.

The current flowing when charging the capacitor 10 is limited by the limiting

the resistor 12, through the diode 15 enters the base of the power transistor 6, which begins to open, which leads to a decrease in the voltage on its collector, leading to the appearance of the base current of the control transistor 4 and, as a result, to maintain the base current of the power switch 6 from the generator 1 excitation. When transistor 6 is opened, capacitor 9 is discharged through resistors 11 and 13,

limiting shock collector current key. When overload occurs at the output of the inverter, the collector current of the transistors begins to increase, which leads to an increase in the collector voltage and closure

control transistors 4 and 5, which cut off the base current of the power switches, which prevents the output of the power transistors from st.

The proposed inverter makes it possible to eliminate the failures of the power transistors of the converter during current overloads during switching operations, which results in an increased reliability of their switching. The energy of the current-collecting chains is used for the initial unlocking of the power transistors, which leads to a reduction in the turn-on time and energy losses during switching.

Claims (1)

Invention Formula Inverter with independent excitation, containing a transformer, the primary winding of which has a midpoint connected to the first input terminal, the extreme leads of this winding are connected to the collectors of power transistors and current-carrying chains, the capacitor of each of which is connected by one end to the collector of the corresponding power transistor, and the other end through a thinning resistor - to the first output terminal of the input control diode and resistor, the second output of the opposite type transistor is connected to the second input terminal, the susceptibility and the first diode inserted are also connected to the emitters and the power supply is according to a series circuit, and the base transistors, and a master oscillator, about t -5 of each of the power transistors connected in that, in order to with the first conclusions of the opposite-parallel increase of the inverter reliability by means of connected inputs of the second reducing the overload of transistors, second diode and collector-emitter junction the pins of the current-leading transistor diodes, the second pins connected respectively to the bases of force-10, which are connected to the corresponding outflow of the transistors of opposite arms, the course of the master oscillator, and to the base of the same time, the collector is the basic transition of each of the power transistors connected Dog power transistor, bazokollektor-run.