29-08-2016, 03:57 PM
1451536196-SimulationofmosfetBasedInverter.pdf (Size: 1.15 MB / Downloads: 7)
Abstract: This paper illustrate use of series resonant half bridge inverter for induction heating appliances. For Induction Heating
high frequency inverter circuit is used, which can deliver output at different frequencies by Metal Oxide Semi Conductor Field Effect
Transistor (MOSFET).The series resonant inverter is implemented to provide Zero Current Switching (ZCS) for all switches at turn off
condition and Zero Voltage Switching at diode turn on. To achieve the desired high frequency with reduced switching losses resonant
inverter is used. MATLAB / SIMULINK is used for simulating the power electronic converter circuit used for Induction Heating
appliances. By changing the frequency of inverter, variable output power is obtained.
Introduction
Induction heating can be utilized for various application like
Scan hardening, strip heating, counter hardening, single-shot
hardening, melting, brazing, bonding, forging, fitting and
heat treatment etc [1]. The heating of workpiece is obtained
by employing electromagnetic induction theory and the
distribution of power density inside the heated workpiece is
acquired effectively by the selection of power supply
frequency and the appropriate design of induction coil [2]. In
previous days vacuum tube oscillator based high frequency
power supply were used for induction heating application
above 100KHz.This led to defects such as huge volume,
short life time, and low efficiency and preheating. With the
development in the field of high power semiconductor device
technology, various switching devices like static induction
transistor (SIT), insulated gate bipolar transistor (IGBT), and
metal oxide semiconductor field effect transistor (MOSFET)
high frequency power supply can be achieved with great
success [3]. IGBT is widely used in generators as it has low
on resistance and also it needs very little power to drive its
gate. IGBT can be used for frequency up to 60 KHz, but not
suitable for above 60 KHz frequency.SIT can be used but it
has drawback like high conduction loss, complicated
fabrication process, high cost and price which restrict its
used. Whereas MOSFET has advantage like high switching
speed, can be connected in parallel which makes it useful for
obtaining high range frequencies from 60KHz to 500KHz.
2. Induction Heating Principle
A source of high frequency electricity is used to drive a large
alternating current through a coil. This coil is known as the
work coil. The passage of current through this coil generates
a very intense and rapidly changing magnetic field in the
space within the work coil. The workpiece to be heated is
placed within this intense alternating magnetic field. The
alternating magnetic field induces a current flow in the
conductive workpiece. The arrangement of the work coil and
the workpiece can be thought of as an electrical transformer.
The work coil is like the primary where electrical energy is fed in, and the workpiece is like a single turn secondary that
is short-circuited. This causes tremendous currents to flow
through the workpiece. These are known as eddy currents.
In addition to this, the high frequency used in induction
heating applications gives rise to a phenomenon called skin
effect. This skin effect forces the alternating current to flow
in a thin layer towards the surface of the workpiece. The skin
effect increases the effective resistance of the metal to the
passage of the large current. Therefore it greatly increases the
heating effect caused by the current induced in the
workpiece.