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Dc Power Supply for Lead-Free Wave Soldering Machine

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Dc Power Supply for Lead-free Wave Soldering Machine

Dc Power Supply 

Tenarasi Subramaniam EP094304

Dept of Electrical Power Engineering

College of Engineering

University Tenaga Nasional, UNITEN


    Abstract—Purpose of this journal article is to design a dc power supply to a lead-free wave soldering. This dc supply input is a 3ø AC supply. The ac supply is converted by using 2 type of converters. Three phase rectifiers and a DC/DC buck converter used in this design. Transformer is also used in order to step- down the ac voltage supply to be supplied into the wave soldering machine as per the specification given.

  1. Introduction

     Dc power supply is an integral part with many components. Dc power supply has power switching and dc linear power supply. In this paper, the Ac supply is supplied into a transformer to step down the high voltage into the accommodated the needed voltage supply to be supplied in the lead free wave soldering machine.  Transformer reduced the amplitude of the voltage supplied. Then the step down voltage supplied into three phase rectifier. By using the three-phase rectifier it avoids problems associated the voltage ripple and current and operate as rectifier to change the Ac voltage supply into Dc the stepped down dc voltage then will be directed into buck converter to step down the dc voltage as desired output.  

  1. dc power supply model

  1. Specification given to design the dc power source.

In the design specification, a 300Vdc supposed to be generated to be supplied to the soldering machine. Given information:

  1. The input is three-phase AC mains with nominal voltage     11kV (50Hz).
  2. Output voltage is 300 V DC. Output power is 10 kW. Output voltage ripple factor must be less than 2%.
  3. The AC supply fluctuates ±1 %. The output voltage must be    stable at 300 V under all input variations.
  1. System design.

System design described in block diagram:

[pic 1][pic 2][pic 3]

[pic 4][pic 5]

[pic 6]

[pic 7]

[pic 8]

[pic 9]

Chart 1: Flow diagram

  1. Working principle of the design with calculation.

Ac supply source was supplied to the step down 3ø (2 winding transformer). 11kv given is the nominal voltage, nominal voltage needs to change into phase voltage as per the working shown in the below calculation as following.

Vphase = (11 kV)/√3= 6350.85 V

Since it is three phase, positive sequence has been considered in the calculation for the phase angle as below.


                             Va = 6350.850° V

                                 Vb = 6350.85120° V

                                Vc = 6350.85240°V

[pic 10]

Figure 1: Phasor Diagram

The 3phase supply connected to a step

down transformer. This is to ensure the 11kv 3phase ac voltage is not injected straight to the 3phase rectifier.

Therefor a step down transformer is used to step down the voltage. Calculation as below to determine the transformer parameters.The step-down voltage connected to the 3 phase rectifier, the ac voltage being rectified into dc voltage to be supplied to a dc/dc buck converter. The values for the R and L was assumed based on the textbook [2].Final component used for the dc power supply was the buck converter. The main purpose of using the buck converter is to provide a smaller output voltage compared to the supply. This is as well a step down transformer but more into a dc supply. The calculation as per below.

D =[pic 11][pic 12](1)

         = [pic 13][pic 14]= 0.72

f = switching frequency ( 29000 Hz)

[pic 15]

                        Lmin = [pic 16][pic 17]   (2)

                                = [pic 18][pic 19]

                                = 43.44 µH

                            L = 1.25 x 43.44 µH (3)

                               =0.000054 H = 54 µH

                                  Po[pic 20][pic 21]    (4)

                                               = [pic 22][pic 23]

                                               = 9 Ω


                                C = [pic 24][pic 25] (5)

                                   =[pic 26][pic 27]     


                                    = 41 µF

IL [pic 28][pic 29]        (6)        

    [pic 30][pic 31]


[pic 32][pic 33]

[pic 34][pic 35]

  1. hardware component selection

Hardware component selection is giving in the form of table as in the Table 1. These components are based on the stimulation.


Hardware component selection



AC Voltage Source

The AC Voltage Source block represents an ideal voltage source that maintains sinusoidal voltage across its output terminals, independent of the current flowing through the source.


Step down transformer

To decrease ac voltages as per required



Acts as a bistable switch, conducting when gate receives a current trigger and continue to conduct while the voltage across the device is not reversed (forward-biased)


Pulse Generator

Generate pulse at set interval


Insulated Gate Bipolar Transistor (IGBT)

Three terminal power semiconductor device used for high efficiency and and fast switching. IGBT has higher switching speed as MOSFET and lower power dissipation as BJT.



To allow an electric current to pass in one direction (called the diode's forward direction), while blocking current in the opposite direction



Used to block AC while allowing DC current to pass through it.



Store electrical energy and provide the same energy to the circuit when necessary



Control the flow of current to the other components



To take the current reading

As required


To take the voltage reading

As required

Table 1: Hardware component



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