CHAPTER1
INTRODUCTION TO ZVT
1.1 What is ZVT?
Zero voltage switching can best be defined as conventional square wave power conversion during the switch’s on-time with “resonant” switching transitions. For the most part, it can be considered as square wave power utilizing a constant off-time control which varies the conversion frequency, or on-time to maintain regulation of the output voltage. For a given unit of time, this method is similar to fixed frequency conversion which uses an adjustable duty cycle, as shown in Fig. 1. Fig1.1 Zero voltage switching
Regulation of the output voltage is accomplished by adjusting the effective duty cycle, performed by varying the …show more content…
This snubber cell provides perfectly ZVT turn on and ZCT turn off together for the mainswitch of a converter by using only one quasi resonant circuitwithout an important increase in the cost and complexity of theconverter. New ZVT–ZCT–PWM converter equipped with the proposed snubber cell implements most the desirable featuresof both the ZVT and ZCT converters presented previously, and overcomes most the drawbacks of these converters. The steadystate operation of the new converter is analyzed in detail, and this theoretical analysis is verified exactly by a prototype of a1-kW and 100-kHz boost converter. In this thesis, a boost converter operating all the switching devices under Zero Voltage Transition is studied and a model converter which can supply a load of 250W is designed and is used in a PV energy system. In this converter topology, a part of the circuit resonates for a small portion of the switching cycle of the converter, known as the auxiliary circuit that enhances the soft transition from ON state to OFF state and vice versa, thus improving the converter efficiency by reducing the dominating portion of in losses i.e. the losses that occur due to hard transition of the switches. Due to reduced losses during switching transitions heating effect of MOSFETs is reduced and they have a longer life. The comparative study between the new topology and conventional hard switching converter is analyzed in terms of improvement of efficiency and reduction of switching
INTRODUCTION TO ZVT
1.1 What is ZVT?
Zero voltage switching can best be defined as conventional square wave power conversion during the switch’s on-time with “resonant” switching transitions. For the most part, it can be considered as square wave power utilizing a constant off-time control which varies the conversion frequency, or on-time to maintain regulation of the output voltage. For a given unit of time, this method is similar to fixed frequency conversion which uses an adjustable duty cycle, as shown in Fig. 1. Fig1.1 Zero voltage switching
Regulation of the output voltage is accomplished by adjusting the effective duty cycle, performed by varying the …show more content…
This snubber cell provides perfectly ZVT turn on and ZCT turn off together for the mainswitch of a converter by using only one quasi resonant circuitwithout an important increase in the cost and complexity of theconverter. New ZVT–ZCT–PWM converter equipped with the proposed snubber cell implements most the desirable featuresof both the ZVT and ZCT converters presented previously, and overcomes most the drawbacks of these converters. The steadystate operation of the new converter is analyzed in detail, and this theoretical analysis is verified exactly by a prototype of a1-kW and 100-kHz boost converter. In this thesis, a boost converter operating all the switching devices under Zero Voltage Transition is studied and a model converter which can supply a load of 250W is designed and is used in a PV energy system. In this converter topology, a part of the circuit resonates for a small portion of the switching cycle of the converter, known as the auxiliary circuit that enhances the soft transition from ON state to OFF state and vice versa, thus improving the converter efficiency by reducing the dominating portion of in losses i.e. the losses that occur due to hard transition of the switches. Due to reduced losses during switching transitions heating effect of MOSFETs is reduced and they have a longer life. The comparative study between the new topology and conventional hard switching converter is analyzed in terms of improvement of efficiency and reduction of switching