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implement an isolated DC-DC converter able to supply both high- and low-side floating gate drivers. Under-Voltage Lockout (UVLO) and Power Good functions ensure the proper power-up of the driver. Configurable non-overlapping logic either generates half-bridge dead time internally or uses two complementary PMW signals from the controller. It also includes a four channels isolated signal transceiver (2 Tx and 2 Rx) for PWM and fault signals transmission towards or back from secondary sides through tiny pulse transformers. The secondary side IC (figure 4) includes a push-pull driver delivering 10A at 125°C and 8A at 225°C, suited to drive 300A/1700V SiC MOSFET modules. It also includes UVLO, Desaturation and Over Temperature Protection (OTP) fault detection circuits, as well as a two channels isolated signal transceivers. Note that having a fast Desaturation detection protection is fundamental when driving SiC MOSFET’s as their robustness to short circuits is limited to about 10μs at 600V. This means that the short-circuit protection, i.e. the desaturation protection, must react in few μs. In HADES2S, the desaturation blanking time can be programmed between 0.2μs and 8μs by an external capacitor. In case of such an event, the push-pull stage is put in high impedance and the gate of the power transistor is smoothly discharged through the internal soft-shutdown transistor to avoid high dI/dt during turn off. For fast switching devices like SiC and GaN transistors, temperature ruggedized gate drivers brings the benefit of putting them very close to power switches and hence minimizing the gate loop parasitic inductance. This allows for fast switching, resulting in low switching losses, while avoiding ringing that could impact system performances or the reliability of the power transistor. The ultimate objective is to locate the gate driver inside the power module to build SiC-based Intelligent Power Modules (IPM’s). Two kind of SiC MOSFET’s IPM’s are currently in development embedding Fig. 3: HADES® v2 Primary Side IC (HADES2P): DC-DC Controller & Isolated Signal Transceivers. HADES® gate driver: an extreme temperature 600V/25A module, assembled in a hermetically sealed packages and rated up to 225°C (Ta), and a high reliability 3-phases 1200V/100A power module for operation in excess of 200°C (Tj). The first module targets the most stringent temperature environments found in Oil & Gas Drilling and in Jet Engines. The second module is aimed at high power density applications. In both cases, IPM technology provides users with a compact, efficient, reliable and easy-to-use solution to start their power converter design. Fig. 4: HADES® v2 Secondary Side IC (HADES2S): Driver & Protection Functions. Clamping down on harmful harmonics By Steve Hughes The rise of non-linear loads in industrial and commercial applications has brought the debate about harmonic currents to the forefront. We already know they cause damage to equipment, consume more energy and raise costs in the long term, but now the European parliament is taking action to introduce minimum targets. This article explores how harmonics often go unnoticed, the damage they cause and what you can do about it using harmonic filtering techniques. It seems that human-kind has an insatiable appetite to dominate every aspect of our environment. At home, in the car or at the office, we demand complete control. Traditionally, our electronic devices have helped us to achieve this and have, over time, become the centre of our world. Whether it’s personal, commercial or industrial, the electrical systems that power everything around us, actively or passively Steve Hughes is managing director of REO UK - www.reo.co.uk www.electronics-eetimes.com Electronic Engineering Times Europe May 2015 41


EETE MAY 2015
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