Reliability Enhancement of Power IGBTs under Short-Circuit Fault Condition Using Short-Circuit Current Limiting-Based Technique

Like the widely-used semiconductor switch, Insulated Gate Bipolar Transistors (IGBTs) are subject to many failures and degradation in power electronic converters. In Short Circuit Fault (SCF), as the most reported failures in IGBTs, drastic, sudden temperature rise, and peak SCF current are widespread failures owing to a relatively long delay of the protection subsystem. This paper proposes a protection strategy to limit the junction temperature rise by limiting the SCF current by adding a small value resistor in the IGBT emitter. Second, it reduces the SCF current to a value much less than the saturated current. With the proposed control approach, sudden temperature rise during SCF is controlled, preventing significant failure in IGBTs. The extension of the permissible SCF time is achieved even for the cases with temporary arcs. A simple control loop activates in the SCF condition and does not create slow transients for the IGBT. The results of this paper are validated through simulation and experiment.

Electrical Characterizations of 35-kV Semi-Insulating Gallium Arsenide Photoconductive Switch

In this paper, a three-layer GaAs photoconductive semiconductor switch (GaAs PCSS) is designed to withstand high voltage from 20 to 35 kV. The maximum avalanche gain and minimum on-state resistance of GaAs PCSS are 1385 and 0.58 Ω, respectively, which are the highest values reported to date. Finally, the influence of the bias voltage on the avalanche stability is analyzed. The stability of the GaAs PCSS is evaluated and calculated. The results show that the jitter values at the bias voltages of 30 kV and 35 kV are 164.3 ps and 106.9 ps, respectively. This work provides guidance for the design of semiconductor switches with high voltage and high gain.

INFLUENCE OF THE CAPACITANCE OF THE CAPACITOR OF THE DISCHARGE CIRCUIT OF SEMI-CONDUCTOR ELECTRIC DISCHARGE INSTALLATIONS ON THEIR OUTPUT CURRENTS OF LIMITED DURATION

Based on the analysis of transient processes of oscillatory and aperiodic discharges of the storage capacitor of the electric discharge installation to the load, it is proved that an increase in its capacity always causes an increase in the value of the discharge current corresponding to a fixed duration of the discharge, less than the duration of reaching the maximum value of the discharge current. For the capacities of the discharge capacitor varied over a wide range, the change in the value of the discharge current in the load during its forced interruption at a certain time was studied. Based on this study, we proposed a method for increasing the rate of rising of impulse currents in the load, which consists in choosing a discharge capacitor with a larger capacity compared with a capacity sufficient to implement the desired technological mode, and forced interrupting the current in the load at a certain point in time, which corresponds to a certain fixed duration discharge (less than the duration of reaching the maximum value of the discharge current when the capacitor capacity is sufficient to implement the required technological mode). The forced limitation of the discharge duration is carried out by a fully controlled semiconductor switch. This method can be used as the basis for the production of spark erosion nano-sized powders of metals and alloys. Ref. 15, fig. 3, table .

REGULATION OF OUTPUT DYNAMIC CHARACTERISTICS OF ELECTRIC DISCHARGE INSTALLATIONS WITH RESERVOIR CAPACITORS

The paper reveals the dependences of the output dynamic characteristics of semiconductor electric discharge installations (EDIs) with reservoir capacitors on the features of the change in the value of their capacitance. In particular, it is substantiated that for any fixed discharge duration less than the duration of reaching the maximum discharge current, an increase in the capacitance of such storage devices causes an increase in the value of the final discharge current both at aperiodic and oscillatory discharges in the linear resistance of the technological load. The change in the value of the discharge current in the load in the case of forced interruption of this current at a certain moment of time is investigated. Based on the obtained regularities, the authors of the work proposed to use the capacitance of the EDI's capacitor, which is larger than capacitance required to implement the maximum value of the discharge current in the load. Using a capacitor with a larger capacity and a fully controlled semiconductor switch in the discharge circuit of the EDI, it is possible to obtain the required maximum current value at a shorter duration of the discharge process. Thus, it is possible to regulate the main dynamic parameters of pulse currents in the load – the rate of their rise and/or their duration by changing the value of the capacitance of the discharge capacitor EDI. This approach is expedient for increasing the productivity of EDIs, focused on the production of dispersed spark powders of metals and alloys. References 15, figures 3.

Capacitor Commutation Method for MVDC Hybrid Circuit Breakers

The medium voltage DC (MVDC) type system can connect multiple terminals to a common MVDC bus, so it is possible to connect several renewable DC power sources to the common MVDC bus, but a DC circuit breaker is needed to isolate short circuit accidents that may occur in the MVDC bus. For this purpose, the concept of a hybrid DC circuit breaker that takes advantage of a low conduction loss contact type switch and an arcless-breaking semiconductor switch has been proposed. During break the hybrid switch, a dedicated current commutation device is required to temporarily bypass the load current flowing through the main switch into a semiconductor switch branch. Existing current commutation methods include a proactive method and a reverse current injection method by a LC (Inductor-capacitor) resonant circuit. This paper proposes a power circuit of a new MVDC hybrid circuit breaker using a low withstanding voltage capacitor branch for commutation and a sequence controller according to it, and verifies its operation through an experiment.

Breakdown Behavior of GaAs PCSS with a Backside-Light-Triggered Coplanar Electrode Structure

The competitive relationship between the surface flashover of the coplanar electrodes and the body current channel was investigated. Breakdown behavior of GaAs photo-conductive semiconductor switch (PCSS) with a backside-light-receiving coplanar electrode structure was studied in this paper. GaAs PCSS was triggered by the laser pulse with an extrinsic absorption wavelength of 1064 nm. Special insulating construction was designed for GaAs PCSS, while the surface of the electrodes was encapsulated with transparent insulating adhesive. Our first set of experiments was at a bias voltage of 8 kV, and the surface flashover breakdown of GaAs PCSS was observed with 10 Hz triggering laser pulse. In the second experiment, at a bias voltage of 6 kV, the body current channel breakdown appeared on the backside of the GaAs PCSS. Compared with these results, the existence of a competitive relationship between the surface flashover breakdown and the body current channel breakdown of the GaAs PCSS was confirmed. When the bias voltage is set within a certain range (just reaching avalanche mode), GaAs PCSS with a backside-light-receiving coplanar electrode structure will undergo the body current channel breakdown. This finding is also consistent with the simulation results.