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A Simple Low-Cost Gate Drive for Multiple SiC MOSFETs for Single-Switch Induction Heater
  • Arun Paul
Arun Paul
Electronics Device Worldwide Private Limited

Corresponding Author:[email protected]

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Abstract

Two popular application domains of low-power single-switch induction heating systems are cooking and off-line sealing of plastic/glass containers. Sealing operation could be using cap or capless, the latter is preferred because of ease of inspection of sealing quality. For near continuous-duty operation of the converter, due to the superior power loss and thermal characteristics, two SiC MOSFETs connected in parallel are preferred for the switch. The design of gate drive circuit (GDC) for these devices is complicated. The desired gate voltage is not only highly asymmetrical, due to small gate threshold voltage, it is sensitive to ringing in gate signal, the range of negative bias is also constrained. The duty-cycle of the high-frequency gate signal for the switch is small. This article proposed a novel GDC where, using a single-polarity control power supply, a pulse-transformer is used to feed desired asymmetrical gate voltage to several isolated devices. To avoid spurious turn-on, this research further proposed a novel transformer for feeding bi-polar asymmetrical gate voltage with requisite signal and power-noise isolation to effectively use of respective Kelvin source terminal. The proposed idea has been completely validated by driving two SiC MOSFETs in a power converter for high-speed off-line induction sealing applications.