Showing papers on "Junction temperature published in 1968"

Temperature-compensating thyristor control

Abstract: A temperature-sensing element is mounted in good heat transfer relation with a thyristor, and is connected to a control winding of the thyristor firing control circuit. When the temperature of the thyristor rises too high for existing operating conditions the sensing element is effective to reduce the current flow in the thyristor, without stooping it altogether. A signal derived from the current flow through the thyristor may be combined with a signal from the temperature-sensing means to provide a control more accurately representative of the junction temperature in the thyristor. The control is continuous over a predetermined temperature range.

The amplifying gate thyristor

Abstract: High frequency, high current operation of thyristors requires simultaneous consideration of turn-off time, di/dt and dv/dt capability. The frequency of operation and the type of circuit dictate the turn-off time and dv/dt which are required of a device. These two parameters are established by suitable gold doping to control the minority carrier lifetime and by employing "shorted emitter" techniques to ccntrol the low current alpha's of the device. In addition, at high currents and voltages, a thyristor's capability of withstanding steep wavefront, high current pulses (i.e., di/dt capability) often also proves to be a major limiting factor in its application. This characteristic is primarily determined by the instantaneous junction temperature; thus, it is essential that localized heating be minimized. Unfortunately, this problem is aggravated by increased dissipation resulting from the lower lifetime that is required to achieve the short turn-off time. In order to minimize the instantaneous temperature rise, a substantial increase in effective conducting area during the turn-on interval is required.

Performance Characteristics of Thermomagnetic Devices Involving Graded Mass and Gap. I. Generators

Abstract: The theory pertaining to operating characteristics of thermomagnetic generators with graded mass and gap has been developed using the fundamentals of irreversible thermodynamics. On introducing transport theory and a considerable number of simplifying assumptions, analytic results were obtained for the efficiency of such devices in terms of the transport coefficients evaluated at the hot junction temperature. The numerical results have been compared to those obtained with materials of constant bandgap and to calculations performed by the method of averaged parameters. The advantages of using a graded gap material for energy conversion are pointed out.

The temperature dependence of avalanche current in silicon p-n junctions†

Abstract: The temperature dependence of the avalanche current of a silicon p-n junction is calculated by considering the space-charge generation current and avalanche multiplication factor as functions of temperature. It is found that, as the temperature is increased with constant bias voltage, the avalanche current decreases to a minimum. The temperature at which this minimum occurs and the minimum value of the avalanche current are shown as functions of the original junction temperature within the range 150° K to 500°K. The avalanche current has a positive temperature coefficient above this minimum. Comparison with existing theories on the temperature coefficient of breakdown voltage shows qualitative agreement.