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Telecom sectors generally operate at negative voltages to reduce the effect of corrosion caused in the metallic wire due to electrochemical reaction while communicating signals. To feed those lines and to have an effective digital data transmission, a power electronic converter referred as Modified Negative Luo Converter (MNLC) is proposed in this paper. MNLC is a high gain converter in which the output voltage increases in geometric progression. This paper portrays a novel concept of a 50 Hz pulse data transmission through RLCG (Resistance-inductance-capacitance with a shunt conductance) transmission line using MNLC. Signal frequency of 50 Hz to be transmitted is anded with a high frequency pulse that charges and discharges MNLC and produces the boosted negative output voltage. The boosted output is again transmitted through the RLCG transmission line from which 50 Hz data pulse is retrieved at the output of the transmission line by comparing with a comparator signal. This sort of MNLC aided data transmission not only introduces less loss in its transmitted data but also overcomes various health hazards of conventional radio frequency (RF) communication. This technique also proves that any data bit stream can be transmitted and retrieved using the proposed high gain DC-DC converter. The simulation model of the proposed system is implemented in MATLAB for various switching frequencies with its prototype of the converter developed and the results are verified.

The usage of −48V DC in the telecom sectors exists in current scenario and the telecom stations always require voltage in the range between −45 V and −55 V for safe operation. This negative voltage also helps in preventing corrosion of the metallic copper when operated under wet conditions. The sulphation of the battery which leads to failure is also eliminated by the usage of negative signal, since the build of lead sulphate only leads to battery failure. When the metallic leads used for communication are at negative potential with respect to ground, the metal ions go form the ground to the wire instead of the situation where positive voltage would cause quick corrosion. Thus the electrochemical reaction causing corrosion is highly avoided by maintaining the negative potential feeding the telecom lines. In this, the negative output voltage is produced using MNLC and it also focuses on effective pulse data transmission which plays a vital role in telecoms.

Radio frequency waves possess the longest wavelength in the electromagnetic spectrum. They also have a uniform frequency and amplitude at all time instants [

MNLC is a modified superlift converter in which the output voltage increases in geometric progression with six times the gain compared to the conventional NOSLC whose gain value is three. Here the data pulse transmission concept is implemented with the switching pulse of MNLC. The pulse activates the process of on and off of the MNLC circuit that produces a very high output voltage. Ultimately data pulse retrieval is obtained only from the boosted voltage.

Section 2 deals with the explanation of overview of the proposed system, and Section 3 portrays the operation of MNLC with its modes and analysis followed by its simulation results. The modeling of RLCG transmission line has been dealt in Section 4. Section 5 explains the concept of interface of MNLC with the transmission line followed by the simulation results of data transmission for various switching frequencies. Section 6 depicts the hardware model of MNLC implemented in open loop followed by conclusion in Section 7.

The block diagram of the proposed system is given in

The RLCG parameters have been modeled for coverage of 1000 meters and discussed in the forth coming section. RLCG is a combination of RLC circuit with a shunt conductance ‘G’. The transmitted voltage through the RLCG line is the boosted output from MNLC. The enhanced output from MNLC transmits the required data effectively.

_{in}, capacitors C_{1} and C_{2}, inductor L_{1} and L_{2} switch S, diodes D_{1}, D_{2} and D_{3} and the load resistance R. The working principle is explained with the switch “S” on and off as two modes of operation as shown in

During mode-I, the switch S is turned ON between the period 0 and ΔT as shown in _{1} and capacitor C_{1}. Since capacitor C_{1} and has zero impedance to current, the capacitor C_{1} charges faster than inductor thus forward biasing the diode D_{1}. Thus charge gets stored in inductor L_{1}, L_{2} and Capacitor C_{1}, also during this period, the load current is maintained constant by the discharging capacitor C_{2}. Thus the energy stored in the capacitor C_{2} during the previous cycle is transferred to the load.

During mode-2, the switch S is turned off between the period ΔT and T as shown in _{1}, L_{2} and the capacitor C_{1} discharges across the nodal points of the capacitor C_{2} thus boosting the output voltage. The load current is supplied by the inductor.

The equations governing mode-I are as follows,

Here

The current through the inductor

k is the duty ratio and T is the on-period cycle.

The voltage across the capacitor

The current through the capacitor

From Mode II:

During mode-II, the current through the inductor

Here

The current through the inductor

Equating (3) & (6),

From the above, the gain equation is obtained as,

The output voltage is given by,

The values of

Variation ratio of the output voltage is given by,

By substituting the values for frequency, resistance and k as 50 kHz, 100 Ω and 67%, the value of

Using the above design equations, the component parameters are computed as shown in

The MNLC is simulated using the above design values and the results are depicted in the following figures.

MNLC is simulated for an input voltage of 20 V as shown in _{1}, the input side capacitor and the load capacitor C_{2}. The voltage across the capacitor C_{1} is shown as 19V in _{3} as 140 V and _{2} as 130 V.

The modeling of transmission cable through which the negative voltage is transmitted to influence effective data transmission is explained in this section. The transmission line comprises of a RLCG circuit and it has been modelled for distance coverage of 1000 meters.

SL. No | Parameter | Values |
---|---|---|

1. | V_{in} (Input voltage) | 20 V |

2. | f_{s} (switching frequency) | 50 kHz |

3. | k (Duty ratio) | 0.67 |

4. | R (Resistive load) | 100 Ω |

5. | Expected V_{0} (Output voltage) | −121.1 V |

6. | L_{1}, L_{2} (Inductors) | 0.01 mH |

The transmission line has four parameters namely resistance (R), inductance (L), capacitance (C) and a shunt conductance which is named as RLCG circuit. The capacity of the power transmission is maintained only by the series inductance of the RLCG circuit. The shunt capacitance causes a charging current to flow in the line and plays a significant role in medium and long lines. These parameters are uniformly distributed throughout but can be made as a lumped circuit for analysis.

Having all this assumption, the equations for series resistance, inductance and capacitance of RLCG circuit is given in the following analysis.

1. Resistance in RLCG circuit (R)

The dc resistance is given by:

ρ = resistivity of conductor―Ω・m.

l = length in m.

a = cross-sectional area―m^{2}.

The distribution of current is uniform only for dc and becomes non-uniform when it comes for ac. With the increase of frequency, the non-uniformity also increases. The resistance of metals increases with increase in temperature. It increases linearly and the resistance at temperature “t” is given by,

R_{t} = resistance at t˚ centigrade.

R_{0} = resistance at 0˚ centigrade.

∆t = difference in temperature.

2. Inductance in RLCG circuit (L)

The inductance can be derived for a single phase two wire line. A single phase line consisting of two solid conductors of radii “r_{1}” and “r_{2}” are kept at a distance “D”. The inductance in each conductor is due to internal and external flux linkages.

The inductance of first conductor due to external flux linkage is given by,

The inductance of second conductor due to external flux linkage is given by

The total inductance of the circuit is

i.e.

Or the above equation can be written as,

Thus the inductance is modelled in RLCG line using the above equation.

3. Capacitance in RLCG circuit (C)

Considering the same two solid conductors, the capacitance value is calculated. The two conductors are named as “c_{1}” and “c_{2}”. The potential difference between the two conductors is given as

q is the charge on the conductor per meter.

ξ is the permittivity of the medium and D is the distance and r_{1} and r_{2 }are the radii of the conductors.

Substituting (21) in (20), the capacitance obtained is

Thus the capacitance value is also obtained.

Using the design equations, the transmission line parameters are tabulated in

A. RLCG LINE with Negative DC Input Voltage

In this section, initially a negative DC voltage V_{in} is fed as an input to the RLCG transmission line and its results are verified. Then the transmission line is interfaced with the proposed MNLC and the data pulse retrieval is effectively shown.

Sl. No | Parameters | Value |
---|---|---|

1 | R | 0.83 Ω/m |

2 | L | 5.8 μH/m |

3 | C | 0.485 nF/m |

B. Interface of MNLC with RLCG Transmission Line

The interface of MNLC with transmission line is shown below in

B.1. Simulation Waveforms of MNLC Interface with RLCG Transmission Line

The MNLC interface with RLCG transmission line is simulated using various switching frequencies like 25 kHz, 1 kHz and 500 Hz whose outputs are shown below.

a. With 25 kHz

In this, the switching frequency of 25 kHz is chosen for MNLC. The data to be transmitted is the same 50 Hz signal which is already portrayed in the previous section. Both the signals are anded and provided as a switching pulse to MNLC. The output voltage of MNLC is a very high boosted output with less ripple. This again is transmitted through the RLCG transmission line. The output obtained from the line is a low value output because of the losses introduced in the transmission line due to the passive components. This voltage is compared with a comparator signal and the pulse of 50 Hz is retrieved at the transmission line. Thus the following figures depict the simulated outputs.

Thus the

b. With 1 KHz

The pulse retrieval at the output of a RLC transmission line is shown here for a frequency of 1 KHz [

C. With 500 Hz

The input voltage of MNLC is 50V which is shown in the

This section portrays the prototype developed for MNLC and shows the boosted output voltage. This voltage is transmitted through the RLCG line and the respective output from the line is measured. It is again compared with a comparator signal for retrieving the data pulse transmitted. This is how the transmitted voltage aids in the retrieval of pulse. For an input of 6 V,

The pulse data transmission using RLCG impedance line with the aid of MNLC is effectively achieved here. The health hazards of RF are overcome in this paper by introducing a simple lift converter which effectively charges and discharges to the load thereby influencing the process of data transmission on a ground level. The pulse data retrieval at the output is obtained by comparing the output signal from MNLC with a reference signal. Thus any data pattern can be transmitted and received using this kind of simple and efficient method which becomes highly helpful in telecom sectors.

V. Chamundeeswari,Dr. R. Seyezhai, (2016) An Approach towards Pulse Data Transmission Using Modified Negative Luo Converter (MNLC) for Telecoms. Circuits and Systems,07,2712-2728. doi: 10.4236/cs.2016.79234