SU808975A1 - Resistance and cutting resistance to frequency converter - Google Patents

Description

(54) CONVERTER ACTIVE AND REACTIVE RESISTANCE IN FREQUENCY

circuit, and the integrator input is connected to another input of the comparison unit and its output.

Figure 1 shows a block diagram of a converter; FIG. 2 shows diagrams explaining his work.

The converter contains measuring circuit 1, unit 2, comparison, integrator 3, inverter 4, first RC circuit 5 and second CS circuit b.

The output of the measuring circuit 1 is connected to the first input of the comparison unit 2, the output of which is connected to its second input and to the output of the integrator 3, the output of the latter is connected to the output of the inverter 4 ;. and with the output of the first RC circuit 5, the output of the inverter 4 is connected to the input of the second RC circuit, the outputs of the KC circuits 5 and 6 are connected respectively to the first and second inputs of the measuring circuit 1, the comparison output is the output of the converter.

The device works in the following way.

In the steady state operation of the device from the output of the comparison unit 2, opposite-polar rectangular pulses with a constant amplitude of ±, and (Fig. 2, d) follow. When the polarity of the output voltage C + Ug is changed to - UQ, the voltage at the output of the integrator 3 will begin to decrease, and at the output of the inverter 4 - to increase (Fig. 2b, c), and the sensor entering measuring circuit 1 through The CS circuit is supplied with a triangular anti-phase voltage. Enabling the sensor through an RC circuit is necessary to prevent the inverter 4 and the integrator 3 from closing on the direct current,

If the resistances of both arms of the sensor are equal, i.e. 2 Z, TO at the midpoint of the sensor, the signal is compensated if, at the midpoint of the sensor, a triangular voltage appears, the rate of increase of which is determined by the difference (Fig. 2a). This voltage is applied to the first input of the comparator unit 2 and is compared with its response threshold U,..,, Determined by its transmission coefficient of the circuit as a feedback. Changing the transmission coefficient of the positive feedback circuit: allows the adjustment of the initial frequency of the converter. At the moment of equality of the voltage at the inputs of the comparison unit 2 at its output, the polarity of the voltage changes to the opposite (fig.2g),

as a result, the voltage at the output of integrator-3 decreases, and at the output of the inverter increases (Fig.26, c), the voltage at the middle point of the sensor decreases to the negative threshold level of the comparison unit 2. Next, the device operation cycle repeats.

The dotted line in figure 2 shows the work of the Converter with a different value of the difference Z,

The feedback voltage is ± U0, and at the output of the integrator 3 is determined by the ratio

 C1

where t: is the integrator time constant.

The output voltage of the inverter is

U)

the signal at the output of the measuring circuit is

..a. Taking into account formulas (1) and (2) we have

.) t (W. C-)

The period of the output signal of the converter with regard to formula (4) is equal to

. () -, 2Un.

T-ACZi-Z, j) and the frequency of s (y)

()

 V

2i „

Ur

1C 2 and.

It - and.

h ii, - and

Claims (2)

1. Author je certificate of the USSR 382232, NOZ K 13/20, 1974. 2. Authors certificate of the USSR 561907, G 01 R 27/26, 1975. Wn M, l r l -lf - l-t -tf-1 rf-t- tf-t-1