KALINGA INSTITUTE OF INDUSTRIAL TECHNOLOGY

Seminar onSeminar onResonant and Soft Switching ConverterResonant and Soft Switching Converter

Under Guidance of: Presented by :- Under Guidance of: Presented by :- Prof. A. Das GUPTA Anup Kumar Prof. A. Das GUPTA Anup Kumar

Dept. of EDept. of Electrical Engineeringlectrical Engineering Branch : M. Tech (E.E)Branch : M. Tech (E.E) KIIT UniversityKIIT University Roll no: 1052002 Roll no: 1052002

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Resonant and Soft Switching converter

ContentsIntroduction What do mean by Resonance?PWM dc-to-dc converter Resonance and Soft Switching ConverterComparison between ZCS and ZVS ConverterAdvantages and DisadvantagesApplication ConclusionReferences

Resonant and Soft Switching converter

1.Introduction

PWM dc-dc converters suffer from1.Switching power loss and stress loss.2.Electromagnetic interference.Overcome by application of Resonant and Soft Switching Converter.

RESONANCE

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.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.

SERIES RLC NETWORK

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Resonant and soft switching converter

L.C NETWORK

Resonant and Soft Switching Converter.

. PWM DC-DC CONVERTERIn 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.

Resonance and Soft Switching converter

PWM DC-TO-DC BUCK TYPE CONVERTER

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.

Resonant and Soft Switching ConverterRecently, 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.

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Resonant and Soft Switching Converter

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Classification of Resonance type DC-DC

Resonant and Soft Switching Converter

Quasi Resonant ConverterQuasi-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.

ZERO CURRENT SWITCHING

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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.

Resonant and Soft Switching Converter

Circuit Diagram of ZCS Converter

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Resonant and Soft Switching Converter

Output Voltage and Current Waveform.

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Resonant and Soft Switching Converter

ZVS CONVERTERS

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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.

Resonant and Soft Switching Converter

ZVS AT SWITCHING FREQUENCY 50 K HZ

Resonant and Soft Switching

Converter

Output Current and Voltage Waveform

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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.

Advantages of ZCS and ZVS

1. Reduces switching power loss.2. Eliminate switch stress and EMI.3. High efficiency.

Application of ZCS and ZVS

1. Electronic ballasts for gas-discharge lamps.2. Electrosurgical generators.3. Induction heaters.4. Piezoelectric transformers.

Conclusion

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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.

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.org5. www.sciencedirect.com6. Wikipedia.7. www.answers.com

THANK YOU

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