KALINGA INSTITUTE OF INDUSTRIAL TECHNOLOGY Seminar on Resonant and Soft Switching ConverterUnder Guidance of: Presented by :-Prof. A. Das GUPTA Anup KumarDept. of Electrical Engineering Branch : M. Tech (E.E)KIIT University Roll no: 1052002 Dec 1, 2012 1 1
Resonant and Soft Switching converter ContentsIntroductionWhat do mean by Resonance?PWM dc-to-dc converterResonance and Soft Switching ConverterComparison between ZCS and ZVS ConverterAdvantages and DisadvantagesApplicationConclusionReferences
Resonant and Soft Switching converter 1.IntroductionPWM dc-dc converters suffer from1.Switching power loss and stress loss.2.Electromagnetic interference.Overcome by application of Resonant andSoft Switching Converter.
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. Dec 1, 2012 4
Resonant and soft switching converterL.C NETWORK
Resonant and Soft Switching Converter.. PWM DC-DC CONVERTERIn this scheme, the on-time Ton is varied but chopping frequency f (orchopping period T) is kept constant. Variation of Ton means adjustment ofpulse width, as such this scheme is also called pulse-width-modulationscheme.Vo =(Ton/T)VsWhere :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 ConverterAdvantages 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 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.
Resonant and Soft Switching ConverterClassification of Resonance type DC-DC Dec 1, 2012 1 11
Resonant and Soft Switching Converter Quasi Resonant ConverterQuasi-Resonant converters (QRC’S) can be considered as ahybrid of resonant and PWM converters. The underliningprinciple is to replace the power switch in PWM converterswith resonant switch. The switch current and/or voltagewaveforms are forced to oscillate in quasi sinusoidalmanner.It is classified into 2 classes.Zero Current Switching.Zero voltage Switching.
ZERO CURRENT SWITCHINGIt is formed by replacing the power switch in PWM converter with ZCresonant switch. The output filter inductor is sufficiently large so that itscurrent is approximately constant. Prior to turning the switch on, theoutput current Io freewheels through the diode Df. The resonantcapacitor voltage Vcr equals zero. At to, the switch is turned on withZCS.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. Duringand after the gate pulse, resonant capacitor voltage Vcr rises and thendecays at a rate depending upon the output current .The output voltageregulation is achieved by controlling the switching frequency. Dec 1, 2012 13
Resonant and Soft Switching Converter Circuit Diagram of ZCS ConverterDec 1, 2012 14
Resonant and Soft Switching Converter Output Voltage and Current Waveform.Dec 1, 2012 1 15
Resonant and Soft Switching Converter ZVS CONVERTERSIn these converters, the resonant capacitor provides a zero voltagecondition for the switch to turn on and turn off. When the switch ‘s’ isturned on, it carries the output current Io. The supply voltage Vi reversebiases the diode Df .When the switch ‘s’ is turned of with Zero Voltageturned off, the output current starts to flow through the resonantcapacitor Cr. When the resonant capacitor voltage Vcr equals to zero, theanti parallel diode turns on The resonant capacitor is shorted and thesource voltage is applied to the resonant inductor Ilr increases linearlyuntil it reaches Io. Then Df turns off. Dec 1, 2012 16
Resonant and Soft Switching ConverterZVS AT SWITCHING FREQUENCY 50 K HZ
Resonant and Soft Switching ConverterOutput Current and Voltage Waveform
Comparison between ZCS and ZVSConverters1. ZCS can eliminate the switching losses at turn off and reduce theswitching losses at turn on.2. In ZCS switches under high current stress, resulting in higherconduction loss. However, it should be noted that ZCS is relativelyeffective in reducing loss for power devices (such as IGBT).3. ZVS can eliminate the capacitive turn on loss. It is suitable for highfrequency operation.4. ZCS operate with constant on time control whereas ZVS operate withconstant off time control. Dec 1, 2012 19
Advantages of ZCS and ZVS1. Reduces switching power loss.2. Eliminate switch stress and EMI.3. High efficiency.
Application of ZCS and ZVS1. Electronic ballasts for gas-discharge lamps.2. Electrosurgical generators.3. Induction heaters.4. Piezoelectric transformers.
ConclusionIn conventional PWM dc-to-dc and dc-to-ac converters, the controllableswitches are operated in switch mode where they are required to turn onand turn off the entire load current during each switching. In this switchmode operation, the switches are subjected to high switching stress andhigh switching power loss that increases linearly with the switchingfrequency of the PWM.These shortcomings of the PWM converters can be eliminated, if theswitching frequency is increased in order to reduce the size and weightand to increase the power density. Dec 1, 2012 22
Resonant and Soft Switching ConverterREFRENCES1. Power Electronics, Converters, Application, and Design by N. MohanRobbins.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