SU1325660A1 - Key bridge power amplifier - Google Patents

Abstract

The invention relates to radio engineering. The purpose of the invention is to increase the efficiency when de-phasing the input signals of half-bridges. The device contains power transistors CT) 1-4, resistors 5-8, transformers 9 and 10c with input secondary windings 11-14 and additional windings 19-22, forward diodes 15-18 and load 23. The goal is achieved by drastically reducing through currents through ST 1-4 by shunting their input signal for the duration of the unlocking signal. 1 il. (L JTJ5d2

Description

The invention relates to radio engineering and can be used to power the active and reactive loads of key power amplifiers, in which the output voltage is adjusted or its amplitude modulated at a constant supply voltage by dephasing the input signals of the power amplifier relative to each other.

The purpose of the invention is to increase the efficiency when the input signals of half-bridges are dephased.

The drawing shows a circuit diagram of a key bridge power amplifier.

The key bridge power amplifier contains power transistors I – 4, resistors 5–8, transformers 9 and 10, input secondary windings 11–14, forward diodes 15–18, additional windings 19–22, and load 23.

Key bridge power amplifier works as follows.

Let at a given moment of time the polarity at the input of the transformer 9 is such that the power transistor 1 must be open and nascent, and the power transistor 2 of this half-bridge is closed. At the same time, at the input of the transformer O, the signal is shifted in phase so that the power transistor 4, diagonally located with the power transistor 1, is still closed and the power transistor 3 must be open. The current through the load 23 does not leak. In this case, the polarity of the signal on the additional winding 19 of the transformer 10 is such that the shifted diode 15 is open and shunts the base-emitter junction of the power transistor 1, not allowing the minority carriers to accumulate in its base without the collector current. At the same time, the additional winding 21 of the transformer shunts through the open direct-displaced diode 17 a base-emitter junction of the power transistor 3.

After changing the polarity of the signal at the input of the transformer 10, the power transistor 4 opens, the shifted diode 15 closes, allowing the power transistor 1 to open. Through the load 23, a current flows through the circuit (+ Ek) - the power transistor L - load 23 - power transistor 4 - (-Ek).

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Then, the polarity of the signal at the input of the transformer 9 changes. In this case, the power transistor I closes and the power transistor 2 should open.

However, since the power transistor 3 is still in cut-off mode, no current flows through the load 23. The polarity of the signal on the additional winding 20 of the transformer 10 is such that the shifted diode 16 is open and shunts the base-emitter junction of the power transistor 2, preventing the base carriers of the power transistor 2 from accumulating and passing through the through-through power transistor 1 through it. Polarity The signal on the additional winding 22 of the transformer 9 is such that direct-mounted diode I8 is also open and begins to shunt the base-emitter junction of the power transistor 4 before changing the polarity of the signal on the transformer 10.

After changing the polarity at the input of the transformer 10, the power transistors 2 and 3 are opened, as the terminals are locked (diode 16, and the current begins to flow along the {+ Ek) circuit of the power transistor 3 - load 23 - power transistor 2 - (-Ec) .

Then, the polarity of the input signal of the transformer 9 is changed, and all processes are repeated in the same way.

Since the power transistors, which at a certain point in time must open when exposed to an I chop signal, and their collector current is cut off by closed diagonally arranged power transistors, do not enter the base saturation mode due to the fact that their input signal is shunted for this period of time, through the currents through the power transistors are sharply reduced, which significantly increases the efficiency of the key bridge power amplifier, especially at large dephasing angles of the input signals, and reduces the soinaemuyu power to active devices key bridge power amplifier.

Claims (1)

Invention Formula Key bridge power amplifier, made with transformer31325660 Inlet and output, which contains the input secondary windings of the adjacent each half-bridge, the two power transis arms are connected oppositely, about the teller having one structure, and the fact that, in order to parallel the base-emitter efficiency, dephasing the progress of each of the power transistors of the input half-bridge signals, trans-connected two circuits from the series-format input is made of two connected resistors and input double-input transformers for each primary winding, as well as forward-half-bridge, while The additional diode and the additional winding, the windings of one half-bridge, are connected by the same name with the secondary windings of the input trans-input secondary winding, a transformer of the other half-bridge.