Brief theoretical information

Properties of the nonlinear resistive two-terminal network are determined by its current-voltage characteristic (CVC). The equivalent circuit of such a two-terminal network to represent a nonlinear resistive element.

A series connection of linear and nonlinear two terminal current-voltage characteristics of the resulting circuit is usually found by constructing mirroring CVC linear dipole. Mirroring can build on the plane of CVC expression

I=(E-U_n)/R,

where U_n - voltage nonlinear element corresponding to each given value of circuit current.

The mode of operation of the circuit will be determined by the point of intersection of the mirroring CVC and CVC nonlinear dipole.

Such constructions are held with graphic-analytical method of solving problems.

The analytical solution of the problem of CVC of the nonlinear element approximatelt one of the known functions and then find the joint solution of the obtained above expressions for mirroring CVC linear element.

At consecutive connection of the nonlinear elements of the graphic-analytical analysis of the operation of the circuit may be done in two ways:

1) by constructing mirroring CVC one of the nonlinear elements and further solving the problem according to the above-described case for problem analysis for series non-linears elements scheme;

2) the way to build a CVC total obtained by adding the characteristics of both non-linear elements along the axis of voltage.

To obtain the total CVC of two parallel connected non-linear elements, the sum of their characteristics should be carried out on the axis of the current. It is also possible to apply the analytical way of solving the problem similar to the above described.

CVC nonlinear elements are usually found experimentally.

The procedure of experiments

Experiment 1. Getting CVC semiconductor diode

Assemble the circuit shown in fig. 3. 9.

Fig. 3. 9. The scheme to acquire CVC of semiconductor diode

Turn on the circuit for simulation. Altering the EMF of source in the order given in table. 3. 9, measure the currents flowing through the circuit and drop voltage of the diode and record them in this table.

Table 3. 9

Definition of CVC of semiconductor diode

According to the obtained results, build the dependence I(U).

Date: 2018-08-27; view: 28246