Current injection technique: Difference between revisions

Revision as of 10:40, 27 May 2009

Revision as of 13:16, 7 June 2009

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The current injection technique was developed and published by Dr S. Eio of Staffordshire University (United Knigdom) in 2007.

The current injection technique was developed and researched to reduce the turn-OFF switching transient of power bipolar [[semiconductor]] devices. The Turn-OFF switching transient of [[Silicon]] based power bipolar semiconductor devices is known to limit the device switching speed and therefore limiting the efficiency of the application it is used within. This turn-OFF switching transient is due to the stored charge in the device during the forward conduction state.

Different techniques such as carrier lifetime control, injection efficiency and buffer layer devices have been used to minimiseminimize this, but all result in a trade-OFF between the ON-state loss and the switching speed.

The current injection technique examined in Dr Eio's publications optimiseoptimize the switching transient of power diodes, thyristors and Insulated Gate Bipolar Transistors (IGBTs) without the need of changing the structure of these devices. To implement the current injection technique, a [[current]] injection circuit was developed with results indicating that the injection of an additional current during its switching transient can reduce the reverse recovery charge of a given power diode and thyristor, and also reduce the tail current of an IGBT.

Practical experimental results on diodes[[diode]]s and thyristors[[thyristor]]s showed that the amplitude of the injected current required is proportional to the peak reverse recovery current and proved that these devices experience a momentary increase in recombination of current carriers during the injection of the additional current. This help to prevent the device from conducting large negative current, which in turn reduce its reverse recovery charge and reverse recovery time. Results obtained from experiments with an IGBT showed a significant reduction in the time where current falls to zero when opposing current was injected into the device during its turn-off transient. Further simulation results from numerical modellingmodeling showed that the injected opposing current temporary increase recombination in the device and therefore reduce the extracted excess carriers that was stored within the device.

To prevent circuit commutation and bonding between the current injection circuit and the main test circuit where the Device under Test (DUT) is connected to, a non-invasive circuit was developed to magnetically couple the two circuits.

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7.N.Shammas, S.Eio, S.Nathan, K.Shukry, D.Chamund., “Thermal Aspects of Power Semiconductor Devices and Systems,” VII Conference Thermal Problems in Electronics, MicroTherm’07, 24th – 28th June 2007, Lodz, Poland

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[[Category:Semiconductors| ]]