SU1760626A1 - Power amplifier - Google Patents

Abstract

The invention relates to elements of automatic devices and can be used in automation systems, which are subject to increased requirements for reliability and efficiency of a power amplifier. The purpose of the invention is to increase efficiency while increasing the reliability of protection of power circuits. The power amplifier contains a load 4, an output transformer 1, a current transformer 18, four transistors 5, 6, 23, 24, two I-HE elements 9, 10, five resistors 11, 12, 13, 14, 15, two capacitors 16, 17, the master oscillator 25, the power source 7, the blocking voltage source 8, which, in the aggregate, reduces the losses in the power transistors, increases the protection of the transistors from overvoltages, and excludes their overload. 1 il.

Description

The invention relates to elements of automatic devices and can be used in automation systems.

The purpose of the invention is to increase efficiency while increasing the reliability of protection of power circuits.

The drawing shows a circuit diagram of a power amplifier.

The power amplifier contains the output transformer 1 with the primary and secondary windings 2 and 3, the load 4, the first and second power transistors 5 and 6, the power source 7, the blocking source 8 and the blocking voltage, the first and second elements AND-HE 9 and 10, the first and the second bias resistors 11 and 12, the first and second resistors 13 and 14, the starting circuit resistor 15, the first and second coupling capacitors 16 and 17, the current transformer 18 with the first and second feedback windings 19 and 20 and with the first and second secondary circuits windings 21 and 22 feedback, the first and second control transistors 23 and 24, the input source in the form of a master oscillator 25 with anti-phase outputs relative to the common bus device.

The power amplifier works as follows.

From the master oscillator 25, the control rectangular voltage pulses that are out of phase (p + 180) are supplied to the inputs of the AND-HE elements 9, 10. Let a positive pulse through the capacitor 16 is applied to the element AND-HE 9, which inverts it, providing at its output a zero potential, which in turn locks the transistor 23. At the same time, a small flow will flow into the base of the power transistor 5

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unlocking current, current in the collector circuit of the power transistor 5, in the winding 22 of the current transformer 18, in the winding 2 of the output transformer 1. The current in the primary winding 19 of the current transformer 18 will cause a current in the secondary winding 21 to go along the winding 21 , resistor 13, bases, emitter junction of transistor 5, blocking voltage source 8, winding 21 of current transformer 18. Since this current is proportional to the collector current, the saturation coefficient of transistor 5 will be practically unchanged over a wide range of load current 4, which will provide minimal power loss in power circuits and control circuits.

At the end of the duration of the positive impulse to the input element AND-NOT

9, a capacitor 16 is supplied with a zero (or negative) pulse, which will provide a positive potential at its output, opening the transistor 23. In this case, the base current of the power transistor 5 will transfer to the collector circuit of the transistor 23 and transistor 5 will start to close. Simultaneously with the supply of zero potential to the input element AND-HE 9, the input pulse of the element AND-NOT 10 is given a pulse of positive polarity, which, having passed through it, will close the transistor 24 and provide unlocking of the power transistor 6 through the current transformer 18 with windings 20, 22 In this case, the processes occurring in the power circuit of the transistor 6 will be similar to the processes described above for the power transistor 5. It should be noted that replacing a break in the windings located in the base circuit of the power transistors by shorting them with the transistor 23 (24), as of the diagram shows, reduce overpotential in the reference transistors chains 5 (6).

In case of failure of oscillations of the master oscillator 25, the current through the capacitors 16, 17 at the end of the transient process of charging (discharging) these capacitors will become zero. At the inputs of elements AND-NOT 9,

10 thanks to the resistors 11,12 voltage close to zero is established, and the positive potentials at the outputs, which open the control transistors 23, 24 and close the power transistors 5, 6, thereby eliminating the short circuit on the power circuit.

The use of the invention will allow to control the power amplifier from microprocessor technology, eliminate the short circuit in the power circuit through the output transformer and power transistors in case of failure of oscillations of the master oscillator, reduce losses from the power transistors and control circuits, reduce the overvoltage in the base circuits of power transistors, All this will lead to increased reliability and efficiency of the power amplifier.

Claims (1)

Claims of the Power Amplifier, containing an output transformer, primary winding 0 of which is included in the collector circuit of the first and second power transistors, having the same structure, and the middle point of the primary winding is connected via a power source to the emitters of the first and second 5 power transistors, to which the first busbar voltage source is connected, the first and second control transistors having the structure of power transistors, in collector circuits of which are connected in series, respectively, the first resistor with the first secondary feedback winding and the second resistor with the second feedback secondary as well as oeistor 5 of the starting circuit and the first and second bias resistors, with tl and h to n and h with tag / that, in order to increase efficiency while increasing the reliability of protection of power targets, the first and second elements of AND-NOT are introduced. 0, the first and second separation capacitors, some of the plates of which are inputs for supplying antiphase input signals relative to the common bus of the device, the other plates are connected first 5 inputs, respectively, of the first and second NAND elements, the second inputs of which are connected and are the input for supplying a control signal, wherein between the first inputs of the first and second AND NAND elements and the connection point of the emitters of the first and second power transistors, common bus device, included, respectively, the first and second bias resistors, outputs 5 of the first and second elements of the NAND are connected to the bases of the first and second control transistors, respectively, the emitters of which are connected to the connection point of the emitters of the first and second power transistors, in whose collector circuits the first and second primary windings of the feedback are inserted, and primary and The secondary feedback windings are the windings of an inserted current transformer, the first and second primary windings of the feedback being connected to each other, and the secondary windings are opposite in relation to vuyuschim primary windings of the feedback poichem the free ends of the first and second secondary windings of the feedback source connected to the second bus locking voltage and the base of the first and second power transistors are connected to the collectors of the first and second control transistors, while between the midpoint of the primary winding of the output transformer and the base of one of the power transistors included a starting circuit resistor. Uxlj With g77kl / s # # / e -ff