SU1700743A1 - Amplifier with galvanic isolation - Google Patents

Description

one.

(21) 4723027/09

(22) 07.19.89

(46) 12/23/91. Bul №47

(72) L.V. Reznikov, K.D. Polozov, V.A. Yezhov,

D.D. Rovinsky, N.A. Petrov, V.D. Sulimin

and Yu.N. Shchelkunov

(53) 621.375.024 (088.8)

(56) US Patent No. 4506230, cl. DOS F3 / 38, 1985.

(54) GALVANIZED AMPLIFIER

(57) The invention relates to amplifier technology. The purpose of the invention is to improve the noise immunity. The amplifier with galvanic isolation uses input and output amplifiers of direct current 1.2, modulator 3, demodulator 4, signal and reading transformers 5, b, pulse generator 7, first and second serial RC circuits 8, 9 and amplifier power 10, made on the first and second transistors 11,12, additional transformer 13, first and second resistors 14, 15 and capacitor 16. To reduce the transmission coefficient error of the device, the pulse generator 7 is made low-power, the input and output amplifiers are constantly current of 1, 2 and 3 the timing of the modulator and demodulator 4 are carried out from the supply transformer 6. The output voltage of the power amplifier 10 due to the introduction of the capacitor 16 becomes smooth and without emission of high-frequency oscillations. The influence of the leakage inductance of the signal transformer 5 is eliminated by the first and second successive RC circuits 8, 9, which introduce attenuation to the oscillatory process. 1 il.

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The invention relates to the field of electrical engineering and can be used in amplifying devices of constant voltage and current with galvanic separation of input and output.

The purpose of the invention is to improve the noise immunity,

The drawing shows a circuit diagram of the proposed amplifier.

A galvanically isolated amplifier contains input 1 and output 2 DC amplifiers, modulator 3, demodulator 4, signal 5 and power supply 6 transformers, pulse generator 7, first 8 and second 9 RC circuits and power amplifier 10, made on the first 11 and second 12 transistors, an additional transformer 13, the first 14 and second 15 resistors, the capacitor 16.

The proposed amplifier with galvanic isolation works as follows.

The input DC voltage is amplified in the DC input amplifier 1 and fed to the input of the modulator 3, where under the action of the synchronization voltage the slowly varying voltage is converted into a sequence of two-polarized pulses that pass through the signal transformer 5 , are converted in demodulator 4 again into a slowly varying voltage, in which there are short voltage drops, due to the imperfect demodulation of the alternating voltage at the output of the signal transformer 5. After the output 2-stand amplifier d.c. output voltage is repeated a desired transmission ratio input voltage.

However, the magnitude of the output voltage is influenced by the non-identity of the signal transformer 5 and the noise generated by the variable modulating voltage source, which is usually performed as an auto-oscillator with a saturable output transformer. Saturation of the specified transformer causes abrupt changes in the current and voltage surges in the transformer of the oscillator and, as a result, interference to the input input 1 and output 2 amplifiers of the direct current, which causes an error in the transmission coefficient of the device. At the same time, a similar effect occurs when the appearance of parasitic oscillations caused by the scattering inductance of the signal transformer 5, DL

eliminating the device transmission error, the generator 7 is low-power, and the input 1 and output 2 DC amplifiers are powered, and the modulator 3 and demodulator 4 are synchronized from the supply transformer 6. The output voltage of the power amplifier 10 is introduced by the introduction of a capacitor 16 without emissions and high-frequency fluctuations. And the influence of the leakage inductance of the signal transformer 5 is eliminated by the first and second consecutive RC circuits 8 and 9, which, while maintaining the galvanic isolation between the input and the output, introduce the necessary attenuation into the oscillatory process of the leakage inductance of the signal transformer 5, its parasitic capacitances and parasitic mounting capacities. Thus, the introduction of a power amplifier 10 with a capacitor 16 and damping RC circuits makes it possible to reduce the influence of the intermediate voltage conversion and the high-frequency alternating voltage and increase the noise immunity of the proposed device.

Claims (1)

Invention A galvanically isolated amplifier containing a DC input and output amplifiers, a modulator and a demodulator, a signal and supply transformer, and a pulse generator, the output of the DC input amplifier being connected through the modulator to the primary winding of the signal transformer , the secondary winding of which is connected through the demodulator to the input of the output DC amplifier, the control inputs of the modulator and the demodulator are connected to the corresponding secondary windings of pi A transformer, characterized in that, in order to increase the noise immunity, the first and second serial RC circuits and a power amplifier made on the first and second transistors, an additional transformer with the first and second secondary windings, the first and second resistors and a capacitor, the base of each the transistor is connected to its emitter through a series-connected corresponding resistor and the secondary winding of an additional transformer, the capacitor is connected between the bases of the first and second transistors, the collectors of which are connected to the ends of the primary winding of the supply transformer, the midpoint of which is connected to the corresponding power supply; another power supply is connected to the combined emitter of the first and the second transistor, the primary winding of the signal transformer, and the auxiliary transformer connected to the second RC circuit is connected to the output of the pulse generator, the first on between the primary end and the start of the second RC circuit is connected between the primary winding of the primary signal and the end of the secondary transformer.