SU1601719A1 - Push-pull inverter - Google Patents

Abstract

The invention relates to electrical engineering and can be used in secondary power supply and automation systems. The purpose of the invention is to simplify the device. The power transistors 1 and 2 are controlled by a current transformer 8 (9), the control winding of which 14 (15) is closed through a control transistor 6 (7) to a capacitor 21. A resistor 22 common to the two shoulders of the inverter provides a discharge to the capacitor 21. Diodes 23-25 limit the values of the voltage applied to the control transistors 6 and 7 when they are locked by returning the energy stored in the scattering inductance of the control windings 14 and 15 to the power supply 19. 2 Il. 2 h.p.f.

Description

-five

ABOUT

about

P1

one.

Yu

The invention deviates to electrical engineering and can be used in secondary power supply and automation systems.

The purpose of the invention is to simplify the device.

Figure 1 shows the circuit diagram of a push-pull inverter; Fig. 2 shows oscillograms of voltages and toxvs on its respective elements.

The inverter contains power transistors 1 and 2, switching load 3, control nodes 4 and 5. The control units include control transistors 6 and 7 and current transformers 8 and 9, current transformers contain primary 10 and 11, basic 12 vi 13 and control 14 and 15 windings. The inverter has control inputs 16 and 17, a first input terminal 18 for connecting a power source 19 and a second 20 input terminal. Capacitor 21, resistor 22 are common to the two inverter arms.

The power transistors 1 and 2 transitions collector-emitter included in the load circuit 3, which is made, for example, with a midpoint to which the input terminal 20 and the cathodes of the first diodes 23 and 24 are connected. The connection points of the same terminals of the primary 10 are connected to the first input terminal 18 and 11 and base 12 and 13 windings of transformers B and current 9, control windings 14 and 15 of which are connected to control collectors by first pins. Transistors B and 7, each of which is connected to a base with a control input 16 and 17 of control nodes 4 and 5, respectively, and an emitter to a first input terminal 18 and a first terminal of a capacitor 21, the second terminal of which is connected to the second terminals of the control windings 14 and 15, and through a resistor 22 - with a pin 20. A capacitor 21 is shunted by a second diode 25.

Oscillograms (Fig. 2) show control voltages 25 and 27 at inputs 16 and 17, collector currents 28 and 29 of transistors 1 and 2; voltage 30 on condenser 21.

Possible implementation of the proposed push-pull converter according to other two-contact schemes - bridge, half-bridge. In general, Mr-Aozheg’s load can be realized in various ways and contain a transformer, rectifiers, filters, etc.

Consider the established mode of operation, when the control inputs 16 and 17 receive periodic sequences of square pulses with non-changeable parameters, which ensure that the control transistors are turned on until a saturated state

 for the initial time, the time of the moment, laziness to the input 16 of the next pulse (oscillogram 26, figure 2). Up to this point, the capacitor 21 is charged from the source 19 through the resistor 22, the transistor 7 is turned on by a pulse at the control input 17, and the current from the voltage across the capacitor 21 and the source 19 flows through the winding 15 and the collector-emitter junction “Wired through a resistor 22, which provides the remagnetization of the core of the transformer 9 and the reverse offset of the transition emitter-base of the power transistor 2.

5 Transistor 1 is switched on due to the positive feedback between windings 10 and 12, the core magnetizes with the ampered turns of winding 10. When a next pulse 0 arrives at input 16, the control transistor 6 1L turns on through its transition collector The emitter voltage of the capacitor 21 is applied to the winding 14, changing the polarity of the voltages on the windings of 10 m 12 and providing a shaped resorption of excess carriers in the base area of the transistor 1 and its next locking. In the dissolving of excess carriers in the base area of transistor 1, winding 12 is actually 0 short-circuited, and the capacitor discharge at the first stage (oscillogram 30, Fig.2) is maximum. At the second stage, the control transistors 6 and 7 are open, and the power transistors T and 2 are closed.

5When the minimum capacity

of the capacitor 21, it can be completely discharged by the end of the second stage, and the current through the windings 14 and 15 at a given voltage source 19 is actually set by resistor 22. At the end of the control pulse at the input 17, the control transistor 7 is locked The polarity of the electromotive force on the windings 15, 11 and 13 of the current transformer 9. The amplitude of the electromotive force at 45 on the winding 15 is limited by the voltage level of the power supply source 19 and the voltage drop across the diode 24 and the voltage across the diode 25 equal to the voltage across the capacitor 21. Limiting the voltage of the emitter collector of closed control transistors increases the functional reliability or allows the use of lower-voltage control transistors having the best frequency parameters. The energy stored in the winding 15 by the time of locking the transistor 7 is transformed in the windings 11 and 13, ensuring that the transistor 2 is unlocked by their differential voltage, after which the transistor 2 remains open in the third stage and

saturated by positive feedback between the windings 11 and 13 of the current transformer 9.

At the end of the third stage, the impulse of the control voltage reappears at the input 17, transmsto 7 is turned on and through its collector-emitter junction to the winding 15 of the transformer 9 of the eye is applied the voltage of the capacitor 21, which is transformed into the windings 11 and 13 and provides forced resorption on Thursday, the excess carrier in the base of transistor 2 and its subsequent locking. On the fifth step, both control transistors 6 and 7 are open, and power transistors t and 2 are closed, their control transitions are displaced in the direction observable. At the end of the fifth step, when the control voltage ends at the input 16, the transistor 6 is locked and the polarity of the EMF on the windings 14, 12 and 19 of the current transformer 8 changes. At the same time, the EMF amplitude on the winding 14 is limited by the sum of the voltage of the power supply source 19, the direct voltage drop across the diode 23 and the voltage on the diode 25. The energy from the winding 14 is transformed into 12 m 10 windings, providing the initial transistor 1 for their differential voltage, then at the sixth stage, the transistor 1 remains turned on due to the positive reverse between the windings 10 and 12. Next, the electrical processes are repeated.

Having one resistor 22 and one capacitor 21 simplifies the device. The introduction of reverse diodes 23-25 improves the functional reliability of the converter by eliminating overvoltages on control transistors and limiting the level of this voltage, as well as eliminating the change of polarity of the voltage across the capacitor.

Claims (1)

1. A push-pull inverter containing two power transistors, each of which is connected via a control circuit to a current transformer, having a primary winding connected in series to the power circuit connected to the input circuit of the power transistor, the base winding and the control winding of the first transformer the first current through the first control transistor is connected to the first input terminal of the inverter, and the second output through a resistor to the second input terminal of the inverter and through a capacitor to the first of the inverter, the control winding of the second current transformer is connected to the first input terminal of the inverter through the second control transistor by a first output terminal, characterized in that, for the sake of simplicity, the control winding of the second current transformer is connected to the second output terminal terminal 25 of the first current transformer. 2, the inverter according to claim 1, characterized in that, in order to increase the CTt / i reliably by limiting the voltage on the control transistors, the first output 0 of the control winding of each current transformer is connected to the second input diode through the first input diode the output of the inverter, and the capacitor is shunted by the second diode entered. 5 3. The inverter according to claim 1, excl and often with the fact that in each current transformer the primary winding is connected to the emitter of the corresponding power transistor by the first output, the first output of the base 0 winding is connected to the base of the power transistor, and the second outputs of the primary and The base windings of the current transformer are combined.