Journal of Engineering and Sustainable First Online Scientific Conference for

Development Graduate Engineering Students

http://jeasd.uomustansiriyah.edu.iq June 2020
https://doi.org/10.31272/jeasd.conf.1.52

IMPLEMENTATION OF A BATTERY-FED SINGLE-PHASE INVERTER

FOR A LOW POWER INDUCTION HEATING APPLICATIONS

Aziz Sh. Hamad1 *Isam M. Abdulbaqi2

1, 2) College of Engineering/Mustansiriyah Univ. Baghdad-Iraq

Abstract: In low power induction heating applications The available literature about this subject are
like brazing or welding of small sections, a low power patents of such device fed from the mains
furnace required. This paper deals with implementation without design details as well [1, 2, 3]. In [4],
of a proposed power supply fed from a portable battery
Hanan K., study this furnace in details and
for such applications. Such furnace used in case of
unavailability of electric mains or to avoid flame of an simulate the proposed furnace using MATLAB
ordinary welding equipment. A prototype of a single- Simulink.
phase Push-Pull inverter implemented and an
experimental test is conducted. The results approve the
validity of the proposed circuit.
Keywords: Induction Furnace, Brazing, Push-Pull.

1. Introduction
The application of induction heating for brazing
of copper tubes for repair may need a self-fed Figure 1. The proposed circuit to be implemented

portable device due to unavailability of In [4] a 24V battery feeding the Push-Pull
electricity mains in the sight. This work inverter of a step-up transformer is proposed
considers such circumstances, then a portable and simulated. The simulation results of the
furnace has to be implemented. Such a source circuit shown in Figure. 1 reveals that
must be of simple and cheap design in order to (I2=0.44A) and a sinusoidal voltage appears
across the tank circuit (V2=355.24V), inducing
be of low weight. Also, it must be flexible to be
a sinusoidal current in the tank circuit (𝐼𝑡𝑎𝑛𝑘 =
used for brazing of copper pipes. For this 1131A). This means that the current ratio (𝐼𝑟 )
purpose, a Push-Pull high frequency single- of the circuit (𝐼𝑟 = 𝐼𝑡𝑎𝑛𝑘 ⁄I2) is about (2570).
phase voltage source inverter is intended to feed This magnitude of induction coil current is able
a parallel tank circuit composed of the induction to generate a sufficient magnetic flux for the
coil connected in parallel to a low equivalent welding process by induction.
series resistance (ESR) capacitor as shown in The objective of this research is to implement a
prototype of the controversial circuit proposed
Fig. 1.
by [4] and approve experimentally that the

*Corresponding Author: embaki56@yahoo.com

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conclusions from the simulation results are only. Fig. 3 show the implemented prototype of
accurate. Fig. 2.
In this work the designed ferrite transformer [5]
is wounded and the IC (SG 3525 PPSB) is
chosen as a PWM drive for the Push-Pull
electronic switches [6]. The implemented circuit
is tested by applying the output voltage of
150V, 50Hz from the proposed inverter across a
tank circuit of (1.54mH) and (0.33µF). The
obtained results approve the validity of the
proposed circuit in [4].

2. Design Implementation
Figure 2. The implemented circuit.
The circuit designed and simulated in [4]
consists of two parts, the triggering circuit and
the power circuit. The power circuit is well
analyzed, while, the triggering circuit has to be
discussed in this work. The most important part
of the power circuit is the ferrite transformer;
hence, the same design steps are implemented,
and an EE ferrite core type 0P43515EC wounded
with the same type and number of primary and
secondary windings. The switches are
MOSFETs type IRFP250 [7].
The triggering circuit is implemented using a
PWM chip type SG 3525 PPSB [8] as a
controller for the pulse width of the trigger fed
to the MOSFETs. The properties of the IC are as
follows:
 Operation voltage of (8.0V-35V). Figure 3. The implemented Push-Pull circuit
 Separate Oscillator Sync Pin.
 Input Undervoltage Lockout. 3. Experimental Work and Discussion
 Adjustable Deadtime Control.
The aim of the experiments is to prove the
 Oscillator Range of (100Hz-400kHz).
validity of the proposed circuit. Two
A schematic diagram of the implemented circuit experiments are conducted, in the first one, the
is shown in Figure. 2. Two resistances are inverter loaded by a 700Ω pure resistive load, as
added, the first is of 10Ω connected in series shown in Fig. 4. The triggering pulses to the
with the battery and the second of 440Ω is gate of the transistors shown in Fig. 5, while
connected in series with the tank circuit. These Fig. (6-8) show the output voltage, the voltage
resistances are added for the sake of protection across the transformer primary, and the battery
during the experimental test and to show the current consecutively. The load used in [4] is a
current waveforms at these branches of the tank circuit composed of an induction coil of
circuit. Also, a tap of half the output voltage of 1µH, and 10µF capacitor of 400kVAr. The huge
the transformer secondary is used for testing current of this circuit must be avoided in this

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step. Hence, the tank circuit used in the second It is clear that the output voltage is a square
experiment instead composed of a (1.54mH) wave of 150V, 50kHz as shown in Fig. 8, which
toroidal shape, ferrite core coil (to simulate the is half the output voltage of the transformer.
induction coil), connected in parallel to a
(0.33µF, 400kVAr) capacitor.
The following results shown in figures
(9-13) are obtained in the lab. The importance
of this test is that it proves the ability of the
proposed power supply to feed induction
furnaces in such applications.

(50V/div.), (10µs/div.)

Figure 7. The output voltage waveform

Figure 4. The test with 700Ω resistive load

(1V/div.), (10µs/div.)

Figure 8. The current from the battery

(2V/div.), (10µs/div.)

Figure 5. The triggering pulses to the gate

(50V/div.), (10µs/div.)

(20V/div.), (10µs/div.) Figure 9. The voltage waveform across the tank circuit

Figure 6. The primary voltage waveform

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4. Discussion of Results
The experimental results obtained prove the idea
adopted for such type of power supplies in
induction heating. The results show that the
current supplied from the push-pull transformer
(I2) is (1.5mA) while the tank circuit current
(1V/div.), (10µs/div.)
(𝐼𝑡𝑎𝑛𝑘 ) is:
𝑉𝑡𝑎𝑛𝑘
𝐼𝑡𝑎𝑛𝑘 =
Figure 10. The voltage across the 440Ω resistor 𝑋𝑐
𝑉𝑡𝑎𝑛𝑘 ≡ The rms value of the voltage across the
tank circuit.

𝐼𝑡𝑎𝑛𝑘 ≡ The rms value of the current passing

through the tank circuit.

𝑋𝑐 ≡ The capacitive reactance of the parallel

capacitance of the tank circuit.

(50V/div.), (10µs/div.) Since

1
Figure 11. The secondary output voltage waveform 𝑋𝑐 =
2𝜋𝑓𝑟 𝐶

𝑓𝑟 ≡ The resonance frequency of the tank

circuit.

𝐶 ≡ The capacitance of the parallel capacitance

of the tank circuit.

(10V/div.), (10µs/div.) The resonance frequency (𝑓𝑟 ) is 50kHz, and the

capacitance=0.33μF
Figure 12. The voltage across the primary
1
𝑋𝑐 = = 9.646Ω
2𝜋 × 50 × 103 × 0.33 × 10−6

From the experimental results: 𝑉𝑡𝑎𝑛𝑘𝑚𝑎𝑥 =150V,

which represents the maximum value of the
voltage across the tank circuit shown in Fig. 12.
Where,

(1V/div.), (10µs/div.) 𝑉𝑡𝑎𝑛𝑘𝑚𝑎𝑥 150

𝑉𝑡𝑎𝑛𝑘 = = = 106V
√2 √2
106
𝐼𝑡𝑎𝑛𝑘 = = 11A
Figure 13. The voltage across the 5Ω resistance in 9.646
series with battery

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First Online Scientific Conference for Graduate Engineering Students June 2020

The current (I2) from the ferrite transformer feed the induction coil by the reactive power
secondary passing through the 440 Ω resistance itself. This feature is suitable for a low
(𝑟𝑠 ), which is connected in series with the tank weight, simple and low-price portable tool.
circuit can be measured by measuring the Fig. (14) show the tank capacitor.
effective voltage (𝑉𝑟𝑠 ) across (𝑟𝑠 ), using a true
(rms) voltmeter as follows:
𝑉𝑟𝑠 0.7
I2 = = = 1.6mA
𝑟𝑠 440
Hence, (I2) represents the current fed by
transformer secondary. From the previous
calculations the current ratio (𝐼𝑟𝑎𝑡𝑖𝑜 )between the
real current and the imaginary current (𝐼𝑡𝑎𝑛𝑘 ) of
the tank circuit is:
𝐼𝑡𝑎𝑛𝑘 11
𝐼𝑟𝑎𝑡𝑖𝑜 = = = 6875
I2 1.6 × 10−3
Figure 14. The tank capacitor of 0.33µF
Since, the apparent power supplied to the tank
circuit is equal to the terminal voltage of the c) Since, the required capacitor for the welding
transformer secondary multiplied by its output machine is of 10µF capacity, then this
current (I2), then: capacitor can be achieved as two capacitors
of 5µF connected in parallel as that shown
𝑃𝑜 = 𝑉𝑡𝑎𝑛𝑘 × 𝐼𝑠 = 106 × 0.0016 = 0.17VA in Fig. 15, since each capacitor of mass
equal to 600g, then the an 1200g will be the
The transformer output voltage is the same as mass of the two capacitors.
that of the tank circuit, then the power of the d) The proposed induction coil for this welding
tank circuit is machine will be as predicted by Fig. 16.
𝑃𝑡𝑎𝑛𝑘 = 𝑉𝑡𝑎𝑛𝑘 × 𝐼𝑡𝑎𝑛𝑘 = 106 × 11 = 1166VA

Hence, these results prove the validity of the

theoretical results achieved using MATLAB
Simulink by [4], taking into consideration the
application of a real brazing load.

5. Conclusions:
This work leads to many conclusions, these
are: Figure 15. The 5µF capacitor
a) The proposed circuit can be used as a power
supply for a portable induction welding e) The portable welding machine can be
machine. built from two parts, the driving circuit
b) The tank circuit load is more suitable than and the tank circuit. These two parts
the series resonant circuit in that, the series connected by two thin (Litz) wires. This
circuit use a step down high frequency property furnishes a high flexibility for
ferrite transformer[9], while the tank circuit the users during the welding process.

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First Online Scientific Conference for Graduate Engineering Students June 2020

Portable Induction Welding Machine Using

Battery and PV Power Source". M.Sc.
Thesis, University of Technology, Iraq.
5. Wm. T. McLyman, (2004). "Transformer
and Inductor Design Handbook". Third
Edition, Marcel Dekker, Inc.
6. Muhammad H. Rashid, (2007) "Power
Electronics: Circuits, Devices, and
Applications". Third Edition, Prentice-Hall.
7. Keith Billings, Taylor Morey, (2011).
Figure 16. The proposed induction coil for copper "Switch Mode Power Supply Handbook".
tube brazing
3rd Edition, McGraw-Hill.
8. Ned Mohan, William P. Robbins, Tore M.
Acknowledgment
Undeland. (2003). “Power Electronic
Authors appreciate Mustansiriyah University for Converters, Applications, and Design". 2nd
providing R&D lab and support this work. Also, Edition. USA.
appreciate the academic support of Dr. Abdul 9. Mohammad Hameed Khazaal. Isam
Hassan A. Altai and Dr. Ali H. Abduljabbar. Mahmood Abdulbaqi, Rabee’ Hashim
Also, we present our grateful thanks to Eng. Thejel (2016). “Modeling, Design and
Intisar H. Daher for her logistics support. Analysis of an Induction Heating Coil for
Brazing Process Using FEM”. Proc. Al-
Conflict of interest Sadeq International Conference on
Multidisciplinary in IT and Communication
The authors of this article acknowledge that the
Science and Applications (AIC-MITCSA).
publication of this article cause no conflict of
pp. 1-6.
interest to anybody or institution.

References

1. C. H. Henderson. (1968). “Portable Remote

Induction Brazing Station with Flexible
Lead”. United States Patent Office No.
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2. John, P. Robert, C. (2006). “Portable
Induction Heating Tool for Soldering Pipes
having a U-Shaped Head Portion
Comprising an Induction Coil”. European
Patent Specification No. 1 725 366 B1.
3. John P. Robert C. (2007). “Induction Coil
Design for Portable Induction Heating
Tool”. United State Patent No. 7.202450 B2.
4. Hanan K. Abdulabbas. (2019). " Design and
Analysis of a Push-Pull Inverter for

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