2.5 The rational design the throttle of smoothing filter

The calculation is started from the identification of the oriented value of the spindle’s width a of the throttle’s core according to the formula:

; (2.24)

From the Addition Г it is necessary to choose the standard magnetic core that has a not less than obtained value.

For the chosen magnetic core it is calculated the additional coefficient with respect to the length of field line l_ф :

, (2.25)

After that it is calculated the corresponded optimal width of overlap span l_z% and the value of equivalent magnetic conductivity of magnetic core μ_z with respect to the presence of span:

; (2.26)

. (2.27)

Using the obtained data it is possible to identify the width of insulating gap between the cores of magnetic core h_ig and the number of throttle’s windings W_L

, mm (2.28)

(2.29)

Chose the current density j on the winding in the range 3…4 (A/mm²) it is possible to calculate the diameter of winding without insulation

(2.30)

According to the found value of d it is identified the aperture occupation ratio by the following formula:

, (2.31)

where d_n is the diameter of conductor with isolation, mm;

b is the width of magnetic conductor aperture, sm;

h is the high of magnetic conductor aperture, sm.

If the condition 0,25 < k_M < 0,35 is satisfied, then the magnetic core has been chosen correctly.

To amend the value U_0x it is identified the resistance of the throttle’s wending r_D and the exact value of the voltage drop

(2.31)

(2.32)

According to obtained value of the voltage drop U’_0x it is amended the value U_0x.

The obtained results have to be shown in the table 2.12.

Table 2.12 – The design values of the throttle

Parameters

Sc, sm2

a, mm

c, mm

h, mm

b, mm

C, mm

H, mm

G, mm

hпр, mm

WL, lap

d, mm

kM

rD , Ω

ΔU’D, V

U’0x, V

Calculation results

2.6 Definition of the initial data for calculation of transformer

For the scheme shown on the figure 1.2 the electrical parameters of EMF such as U_2x phase of the secondary winding and effective value of current I₂ secondary winding of transformer are defined by the formulas:

(2.33)

(2.34)

The power-to-size ratio of transformer is defined by the formula:

(2.35)

The values K6, K7, K8 are shown in the table 2.13 for calculation U_х, I₂, P_Г

_{Table 2.13 – Coefficients are used to define Uх, I2, PГ}

Scheme of rectifier	K6	K7	K8
Single phase single-step (fig.2.2, a)	1,11	0,71
Single phase double-step (fig.2.2, b)	1,11	1
Three phase single-step (fig.2.2, c)	0,855	0,58
Three phase double-step scheme of Larinov (fig.2.2, d)	0,43	0,82

The obtained results have to be shown in the following table 2.14.

Table 1.6 – The initial data for calculation of transformer

Un, V	fn, Hz	U2x,V	I2, A	PPSR, V∙A	Bm, T	j, A/mm2	kcs	k0