Soft Switching Techniques Are Highly Recommended To Reduce Switching Losses And Conduction Losses, During Each Turning On & Turning Off of Power Electronics Devices.

1. KALINGA INSTITUTE OF INDUSTRIAL
TECHNOLOGY
Seminar on
Resonant and Soft Switching Converter
Under Guidance of: Presented by :-
Prof. A. Das GUPTA Anup Kumar
Dept. of Electrical Engineering Branch : M. Tech (E.E)
KIIT University Roll no: 1052002
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2. Resonant and Soft Switching converter
Contents
Introduction
What do mean by Resonance?
PWM dc-to-dc converter
Resonance and Soft Switching Converter
Comparison between ZCS and ZVS Converter
Advantages and Disadvantages
Application
Conclusion
References

3. Resonant and Soft Switching converter
1.Introduction
PWM dc-dc converters suffer from
1.Switching power loss and stress loss.
2.Electromagnetic interference.
Overcome by application of Resonant and
Soft Switching Converter.

4. RESONANCE
. It is a phenomenon of generating large amplitude of frequency during each
turning on and turning off of the switching power device.
.

In general resonance disturbances are produced whenever
A circuit is connected to or disconnected from the power supply.
 A circuit is shorted.
 There is a sudden change in the applied voltage from one finite value to
another.
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5. SERIES RLC NETWORK
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6. Resonant and soft switching converter
L.C NETWORK

7. Resonant and Soft Switching Converter.
. PWM DC-DC CONVERTER
In this scheme, the on-time Ton is varied but chopping frequency f (or
chopping period T) is kept constant. Variation of Ton means adjustment of
pulse width, as such this scheme is also called pulse-width-modulation
scheme.
Vo =(Ton/T)Vs
Where :
Vo=output voltage in volt.
Ton=switch on time.
T= switching time period.
Ton/T=duty cycle.
Vs=supply voltage in volt.

8. Resonance and Soft Switching converter
PWM DC-TO-DC BUCK TYPE CONVERTER

9. Resonant and Soft Switching Converter
Advantages of PWM Converter.
1. It provides smoother operation.
2. Ripple will be less.
3. Less conduction loss.
Disadvantages of PWM Converter.
1.High switching power loss.
2.Stress loss.
3.Electromagnetic Interference.

10. Resonant and Soft Switching Converter
Recently, switch-mode power supplies have become smaller and
lighter due to higher switching frequency. However, higher switching
frequency causes lots of periodic losses at turn ON and turn OFF,
resulting in increasing losses of the whole system. Therefore, many
converters have been presented that use resonance to reduce
switching losses. Many researches using resonance have presented a
zero-voltage and zero-current switching (ZVZCS) converter that
performs zero-voltage switching (ZVS) and zero-current switching
(ZCS) simultaneously. However, the auxiliary circuit for resonance
increases the complexity of the circuit, as well as its cost.

11. Resonant and Soft Switching Converter
Classification of Resonance type DC-DC
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12. Resonant and Soft Switching Converter
Quasi Resonant Converter
Quasi-Resonant converters (QRC’S) can be considered as a
hybrid of resonant and PWM converters. The underlining
principle is to replace the power switch in PWM converters
with resonant switch. The switch current and/or voltage
waveforms are forced to oscillate in quasi sinusoidal
manner.
It is classified into 2 classes.
Zero Current Switching.
Zero voltage Switching.

13. ZERO CURRENT SWITCHING
It is formed by replacing the power switch in PWM converter with ZC
resonant switch. The output filter inductor is sufficiently large so that its
current is approximately constant. Prior to turning the switch on, the
output current Io freewheels through the diode Df. The resonant
capacitor voltage Vcr equals zero. At to, the switch is turned on with
ZCS.
A Quasi sinusoidal current Is flows through Lr and Cr ,the output filter,
and the load. S is then softly commutated at t1 with ZCS again. During
and after the gate pulse, resonant capacitor voltage Vcr rises and then
decays at a rate depending upon the output current .The output voltage
regulation is achieved by controlling the switching frequency.
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14. Resonant and Soft Switching Converter
Circuit Diagram of ZCS Converter
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15. Resonant and Soft Switching Converter
Output Voltage and Current Waveform.
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16. Resonant and Soft Switching Converter
ZVS CONVERTERS
In these converters, the resonant capacitor provides a zero voltage
condition for the switch to turn on and turn off. When the switch ‘s’ is
turned on, it carries the output current Io. The supply voltage Vi reverse
biases the diode Df .When the switch ‘s’ is turned of with Zero Voltage
turned off, the output current starts to flow through the resonant
capacitor Cr. When the resonant capacitor voltage Vcr equals to zero, the
anti parallel diode turns on The resonant capacitor is shorted and the
source voltage is applied to the resonant inductor Ilr increases linearly
until it reaches Io. Then Df turns off.
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17. Resonant and Soft Switching Converter
ZVS AT SWITCHING FREQUENCY 50 K HZ

18. Resonant and Soft Switching
Converter
Output Current and Voltage Waveform

19. Comparison between ZCS and ZVS
Converters
1. ZCS can eliminate the switching losses at turn off and reduce the
switching losses at turn on.
2. In ZCS switches under high current stress, resulting in higher
conduction loss. However, it should be noted that ZCS is relatively
effective in reducing loss for power devices (such as IGBT).
3. ZVS can eliminate the capacitive turn on loss. It is suitable for high
frequency operation.
4. ZCS operate with constant on time control whereas ZVS operate with
constant off time control.
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20. Advantages of ZCS and ZVS
1. Reduces switching power loss.
2. Eliminate switch stress and EMI.
3. High efficiency.

21. Application of ZCS and ZVS
1. Electronic ballasts for gas-discharge lamps.
2. Electrosurgical generators.
3. Induction heaters.
4. Piezoelectric transformers.

22. Conclusion
In conventional PWM dc-to-dc and dc-to-ac converters, the controllable
switches are operated in switch mode where they are required to turn on
and turn off the entire load current during each switching. In this switch
mode operation, the switches are subjected to high switching stress and
high switching power loss that increases linearly with the switching
frequency of the PWM.
These shortcomings of the PWM converters can be eliminated, if the
switching frequency is increased in order to reduce the size and weight
and to increase the power density.
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23. Resonant and Soft Switching Converter
REFRENCES
1. Power Electronics, Converters, Application, and Design by N. Mohan
Robbins.
2. Power Electronics, Circuits, Devices and Application by M.H. Rashid.
3. Matlab Software.
4. www.ieeexplore.ieee.org
5. www.sciencedirect.com
6. Wikipedia.
7. www.answers.com

24. THANK YOU
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