Laurent Gonthier

Aging test results for high temperature TRIACs during power cycling

This paper deals with the functional reliability study of a new 16 A - 600 V high-temperature TRIAC family, subjected to power cycles, simulating the component in harsh real operation conditions. The targeted application is a vacuum cleaner (1800 W - 230 V - 50 Hz). In this kind of application, one of the major issues for TRIAC, which leads to high mechanical stresses for the assembly, occurs when the switch turns-on in ldquojammed nozzle operationrdquo, i.e. when the tube is blocked. In that case, the TRIAC junction temperature reaches at most 180degC, higher than the maximum value specified by the manufacturer (i.e. 150degC). The aim of this study is to evaluate the TRIACs lifetime under these operation conditions. The thermal stresses generate local temperature variations and then, some mechanical stresses (assembly degradation). For TRIACs, the junction-to-case thermal resistance (Rth(j-c)) increase is the signature of such a damage. The lifetime has been studied and fitted with a Lognormale distribution. The components damages, due to the mechanical stresses, have been explained thanks to some qualitative two-dimensional thermo-mechanical simulations using finite elements (ANSYSreg).

Lifetime prediction modeling of non-insulated TO-220AB packages with lead-based solder joints during power cycling

In this paper, a physical model is proposed to estimate the TRIAC solder joint fatigue during power cycling. The lifetime prediction is based on the following assumptions: the case temperature swing (DTcase) is the main acceleration factor, the solder joints are the weakest materials in the non-insulated TO-220AB TRIAC package and the plastic strain within the solder layer due to shearing is the failure cause.

EN55015 compliant 500 W dimmer with low-losses symmetrical switches

An AC light dimmer topology using two voltage-controlled symmetrical switches is presented. After an introduction of the silicon structure of these new engineering devices, their conduction losses are compared to today technologies. Gate driver circuits are presented to fulfill EN55015 standard with low commutation losses. The impact of the recovery current is also discussed

Thermal runaway evaluation for high temperature TRIACS

This paper deals with thermal runaway that could occur for the new high-temperature TRIACs which are used with junction temperatures up to 160degC in transient state. The conditions to avoid thermal runaway for the specific case of alternative voltage are discussed. Experimental measurements are given and compared with a theoretical analysis.

AC/DC reversible mixed inverter with built-in inrush-current limitation and cut-off stand-by losses

A new inverter using two thyristors in place of two freewheeling diodes is presented. This inverter allows a reversible DC/AC converter to be implemented. This converter can control the inrush-current and allow bridge full-disconnection at stand-by to suppress undesired losses. This is achieved by a full-silicon solution without the need of any inrush-current limiting resistor and or mechanical relays. In this paper, PSPICE simulation results are presented to validate the converter operation. Experimental results are given to discuss the on-state threshold voltage difference between a slow diode, using in a classic inverter, and a thyristor used in this new topology.

Standby consumption reduction for capacitive power supplies

Most appliances that only require a low current in the range of 10 mA to 50 mA to supply the control circuit still, even today, use capacitive power supplies. In these appliances the MCU usually controls one or two Triacs, one LED and sometimes a buzzer; they are, for example, coffee machines, food processors, room heaters, hand dryers or low-end fridges. It is increasingly difficult to meet standard standby power requirements with such capacitive power supplies. We explain here how capacitive power supplies can be modified to better meet these requirements or to increase their output current capability while maintaining power consumption during standby operation mode at a low level.