Sharif Digital Repository

Clamp mode snubbers are very well suited for the series structure of the insulated-gate bipolar transistors (IGBTs) in pulsed power applications. They properly meet the necessities expected from them such as the fast operating of the series IGBTs since they have no effect on the gate side. In addition, they can provide safe voltage condition for the IGBTs in short circuit faults, which are very probable in pulsed applications. The clamp mode snubber can perform its voltage balancing task whenever the power capacity of the snubber can support the injected powers due to the voltage unbalancing factors. This paper initially introduces the main factors injecting power to the snubbers. Then, it... 

The lack of turn-off ability makes the spark gap-based Marx generator uncontrollable in terminating the output pulse. In addition, there are some limitations for rise time and voltage gain improvements in the conventional critically-damped Marx design. In this paper, an efficient over-damped design of Marx circuit is proposed, which leads to a shorter rise time as well as a larger voltage gain. A chopping magnetic switch is employed to achieve the desired values of the fall time and full width at half maximum (FWHM). Moreover, adding a DC bias circuit to the magnetic switch provides the ability to adjust the pulse FWHM parameter. Therefore, an output pulse with a shorter rise time, larger... 

Applying series configuration of the insulated gate bipolar transistors (IGBTs) to the pulsed power supplies offers unique features such as compactness and long life time. In the high-voltage pulsed power supplies, a large number of the IGBTs are required to be serially connected. Hence, the safe operating condition provision for the series IGBTs is an important and crucial issue. The effect of the voltage unbalancing factors becomes remarkable when the number of switches in the series structure increases. There are passive and active methods to balance the voltage of the series IGBTs. In both of these methods, an amount of power must be dissipated to remove the effect of the voltage... 

Clamp mode resistor capacitor diode (CMRCD) snubbers have a simple and easy implementing structure. They have been widely adopted in the pulsed power supplies to provide a safe operating condition for the series insulated gate bipolar transistors (IGBTs). The main problem of the CMRCD snubbers is their poor performance in the voltage balancing of the series IGBTs. They are essentially overvoltage protectors and clamp the voltage of the IGBTs in a probable potentially dangerous condition. This issue diminishes the expected lifetime of the series IGBTs, where a number of them face a higher level of the voltage than that of the others. The unbalanced voltage of the series IGBTs will result in a... 

The series configuration of fast semiconductor switches seems to be the key component in the high-voltage and fast rising time pulse generation. In this approach, two important issues must be considered. The first is to provide a safe operating condition for the switches in transient intervals. The second is to design a gate drive system with the capability of driving a large number of discrete devices simultaneously. The aim of this paper is to obviate these two requirements. First, different factors affecting the unbalanced voltage sharing between the series switches are discussed. In this investigation, the switch-to-ground parasitic capacitance effect has been recognized as the major... 

Nanosecond pulsed-power generators have many applications in industries. As the rise time and fall time of conventional semiconductor switches are usually more than a few nanoseconds, it is necessary to employ special switches or new pulse generating methods to achieve nanosecond pulses. A common method for producing narrow pulse voltage waveforms is using the reverse recovery process of diodes. In this method, a super fast recovery diode is used as an opening switch in an inductor current path. A drift step recovery diode can form a rapid cut-off current front; Hence this method can be an effective solution to generate narrow pulses. This paper describes an investigation about the effect of...