Optocouplers Support High Power, High Speed Switching Inverters

Focus:

Gate-drive optocouplers are useful in high-speed inverter applications because they can provide the high-current gate-drive required for high-speed switching of IGBTs, while also lessening the effects of the EMI generated by high-speed switching. The isolation of input and output grounds within the optocoupler is responsible for its high common-mode rejection (CMR), preventing EMI and noise from interfering with operation of the gate-driver IC. The article discusses the IGBT characteristics that influence gate-drive requirements; gives rules of thumb for the gate-driver ratings required for common IGBT ratings; explains the usefulness of a noninverting buffer when driving very large IGBTs; and discusses tradeoffs in switching speed and EMI suppression.

What you’ll learn:

• How to understand the influence of IGBT characteristics on gate-drive requirements in high-speed inverters
• How to understand the noise-immunity benefits of using gate-drive optocouplers in high-speed inverters

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Author & Publication:

Gary Aw, Applications Engineer, Avago Technologies, San Jose, Calif., Power Electronics Technology, Apr 01 2009

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