Junction temperature

About: Junction temperature is a research topic. Over the lifetime, 5058 publications have been published within this topic receiving 58643 citations.

Method and apparatus for reducing electrical and thermal crosstalk of a laser array

Abstract: Active compensation techniques are used for control of temperature, wavelength, and other characteristics of lasers within a laser array. The laser array includes a plurality of lasers and a plurality of dissipation elements. The dissipation elements can be interstitial to the lasers and can be implemented as non-lasing diodes. The dissipation elements are selectively activated (i.e., turned “on” to dissipate power) to adjust the temperature at the laser junctions. The change in junction temperature allows the lasers to operate at their specified wavelengths. The dissipation elements can be individually controlled and two or more bits of resolution can be provided. Active compensation can be used to adjust (i.e., to compensate) the temperature of selected lasers when one or more lasers are deselected. Active compensation can also be used to adjust (i.e., “tweak”) the wavelengths of the lasers within the laser array to be within their specified wavelengths.

Stabilizing scintillation detector systems with pulsed LEDs: a method to derive the LED temperature from pulse height spectra

Abstract: Photomultiplier tubes (PMTs) can be stabilized with light emitting diodes (LEDs) used as reference light sources. The LED is supplied with short voltage pulses that produce well-defined light portions if the LED temperature is kept constant. However, if the PMT must be operated in a wide temperature range, the LED light output is no longer a constant but becomes a function of the junction temperature. This problem can be solved at low expense by means of a new method. The LED is operated in two alternating pulse modes distinguished by the pulse voltage. The LED light output depends on the pulse voltage and, therefore, the PMT pulse height spectrum shows two distinct peaks. However, not only is the total amount of light L emitted per pulse but also the shape of the temperature dependence L(T) varies with the pulse voltage. The numerical ratio R of the peak positions corresponding to the two different LED modes is therefore a function of the LED temperature as well. Since it is a ratio, R is independent of the actual PMT gain but characterizes the LED junction temperature. Thus, the pulse height ratio of the different LED signals can serve as an LED thermometer. Moreover, measuring L and R at several temperature points covering the full operational range yields a calibration function L(R). With this knowledge, commercial off-the-shelf LED components can be used as precise reference light sources in a wide range of ambient temperatures

A Simple Approach for Dynamic Junction Temperature Estimation of IGBTs on PWM Operating Conditions

Abstract: Power modules including IGBTs (Insulated Gate Bipolar Transistor) are widely used in motor drivers. For the design optimization of the IGBT modules fitted with motor driving conditions, the IGBT junction temperature and the cooling conditions has become a major issue with the increase of the current density and the demand for downsized modules. Especially, estimation of "worst-case" junction temperature caused by a motor locked condition is necessary prior to the module design. In this paper, we propose a simple approach for dynamic junction temperature behavior of IGBTs PWM (Pulse Width Modulation) inverter modules. The dynamic electrothermal calculations are performed using familiar spreadsheet software. In this approach, the mathematical models of the temperature dependencies of the device losses and quasi-one- dimensional difference equations of thermal conduction were used to estimate the junction temperature of the module. To narrow down many device and module parameters in the initial stage of thermal design of the inverter modules, this proposed approach will be an effective tool.