SU1566459A1 - Ac-to-dc voltage converter - Google Patents

Abstract

The invention relates to radio engineering. The purpose of the invention is to improve the accuracy of converting high-frequency voltages and expanding the dynamic range of the conversion to higher voltages. The converter contains an alternating voltage amplifier 1, resistors 10, 11, capacitors 12, 13, 14. The goal is achieved by ensuring that the constant blocking voltage on the outputs of switches made on diodes 19, 20 decreases to zero. For this purpose, integrating amplifiers 2, 6, resistors 15, 16 and capacitors 17, 18. 1 Il.

Description

The invention relates to radio engineering and can be used in the development of generators, detectors, voltmeters, etc.

The purpose of the invention is to improve the accuracy of the conversion of high-frequency voltages and the expansion of the dynamic range of conversion in the direction of high voltages.

The drawing shows an electrical schematic diagram of an AC to DC converter.

The AC-DC converter contains an AC amplifier 1, a first integrating amplifier 2 made on a resistor 3, a capacitor 4 and an operational amplifier 5, a second integrating amplifier 6 made on a resistor 7, a capacitor 8 and an operational amplifier 9, the first 10 and second 11 resistors, first 12, second 13 and third 14 capacitors, first 15 and second 16 additional resistors, first 17 and second 18 additional capacitors, first 19 and second 20 diodes.

The converter operates as follows.

The converted voltage is fed to the input of the AC to DC converter, to the resistors 10 and 11. The capacitance values of the capacitors 12, 13, 17, 18 and 14 are selected so that the cut-off frequencies of the equivalent filters with resistors 10 and 11 are less than the lower frequency of the converted voltage. In this case, the alternating voltages at the common points of the capacitors 12 and 17 and the resistor and 16, as well as at the common points of the capacitors 13 and 18 and the resistors and 15 are close to zero due to the negative feedback of the amplifier 1.

With a positive half-period of the converted voltages, approximately equal currents are created, flowing to the output of the amplifier 1 through the circuit: resistor 11, capacitor 18, diode 20 and through the circuit: resistor 10, capacitors 12, 13 and 18, diode 20. In this case, the current flowing through the capacitors 12, 13 and 18, creates a voltage drop in them.

With a negative half-period of the converted voltage, approximately equal currents are created, flowing to the output of amplifier 1 through a circuit: a resistor 10, a capacitor 17, a diode 19, and through a circuit: a resistor II, capacitors 13, 12, and 17, diode 19. In this case, the current flowing through the capacitors 13 and 12 has the same direction as with positive half-cycles of the input voltage. At the same time, the capacitor 17 is charging.

As a result of charging the capacitor 18 at the output of the diode 20, the voltage is negative, the specified negative voltage is integrated in the integrating amplifier 6. A positive constant voltage is generated at the output of the operational amplifier 9, which is transmitted through the resistor 16 to the connection point of the resistor 10 and capacitors 12 and 17.

As a result of charging the capacitor 17 at the output of the diode 19 positively, the specified positive voltage is integrated in the integrating amplifier 2. At the output of the operational amplifier 5, a negative constant voltage is generated, which is transmitted through the resistor 15 to the connection point of the resistor 11 and the capacitors 13 and 18. In steady state, the inputs of the integrating amplifiers 2 and 6 have zero voltages, i.e. the outputs of the diodes 19 and 20, the voltage is zero. There are also voltages at the outputs of the operational amplifiers 5 and 9, so that the current created between them through the resistors 16, 10, 11, 15, balances the average value of the current pulses charging the capacitors 12 and 13.

If the resistance of the resistors 10 and 1 1 at the input of the AC voltage to DC converter is equal, the isolation capacitor can be omitted. That is, in the steady state, the constant discharge current of the capacitors 12 and 13 through the resistors 10 and 11 turns out to be equal to the half-wave rectified charge current of the capacitors 12 and 13.The outputs of the AC / DC converter with this inclusion are the connection point of the resistors 10 and 16 and the capacitors 12 and

17, as well as the connection point of the resistors 11 and 15 and the capacitors 13 and

18.

It is advisable to phase-use the full range of the output converted voltage, i.e., the voltage difference from the points indicated above.

The average value of the current pulses charging the capacitors 12 and 13 with a positive half-cycle of the input voltage, ^ is determined as follows:

".O ^- 2 R? _o 'the average value of the current pulses charging the capacitors 12 and 13 with a negative input half-cycle, voltage 5, ₍₃ is determined as follows:

η, in 2 R _M '' where U _sv is the average rectified value of the converted voltage;

е ₍ - voltage at the inputs of amplifier 1;

Rio’Rh resistors 25 and 11 respectively.

The current balancing the indicated pulses of the charging current of the capacitors and 13 creates a voltage drop on the resistors 10 and 11, which 30 is the output voltage U _{eb (X} when it is differential removed:

^υ βΜ = (Th ⁺ W (R, o ⁺ Rm). (3)

With appropriate simplifications, and to learn that

k. '(4) ^e 1 we can finally write the conversion coefficient

V_vzh = 2 Г1 + 2 (- | - / - - ± ^ 0. St. 2 K, L

As can be seen from equation (5), the conversion coefficient has multi

Plicative and additive errors. The multiplicative error is proportional to the square error of the resistors Yu and II. The indicated value is extremely small and with real errors of resistors, for example, 0.1Z is two millionths. 59 The additive error is equal to the ratio of the voltage drop across the diodes to the input voltage reduced in K, times.

Claims (1)

Claim An AC to DC converter comprising first and second resistors, the first terminals of which are combined and are the input of the AC to DC converter, and the second terminals are connected to the first terminals of the first and second capacitors, respectively, the second terminal of the first capacitor connected to the inverting input of the AC amplifier , the non-inverting input of which is connected to a common bus, the output of an alternating voltage amplifier, through a third capacitor is connected to the point duction of the anode and cathode of the first and second diodes, characterized in that, p. In order to increase the accuracy of high-frequency voltage conversion and expand the dynamic range of the conversion to higher voltages, the first and second integrating amplifiers, the first and second additional resistors and the first and second additional capacitors are introduced, the input of the first integrating amplifier connected to the cathode of the first diode, and the output through the first additional resistor to the connection point of the second resistor with the second capacitor, the second output of which is connected to the inverting input amplifies By dividing the alternating voltage, the input of the second integrating amplifier is connected to the anode of the second diode, and the output is through the second additional resistor to the connection point of the first resistor with the first capacitor, while the first additional capacitor is connected between the connection point of the first resistor with the first capacitor and the cathode of the first diode, and the second additional capacitor 'is connected between the connection point of the second resistor with the second capacitor and the anode of the second diode. <·