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  1. Wide band gap (WBG) devices have been widely applied in industrial applications owning to their advantages of low switching loss, low on-stage voltage drop, and high operating temperature. Paralleling operation of power devices/modules is attractive due to its cost-effective and high power characteristics. In applications require very high current capability, paralleling operation of off-the-shelf power devices/modules becomes the only choice. However, current balancing operation of individual power device/module becomes difficult due to the differences of circuit parasitics. To investigate the device/module and circuit parasitics influences on the current sharing performance, in this article, a subcircuit model was built in MATLAB. Comprehensive comparisons and analysis are performed, which can provide guidance for engineers when designing the system with paralleling devices/modules. Moreover, the solutions to achieve current balancing operating are proposed with the aid of active gate driver. Experiment results are presented and analyzed to validate the effectiveness of current sharing solutions.
  2. Silicon carbide (SiC) MOSFET features low switching loss and it is advantageous in high switching frequency application, but the manufacture per Ampere cost is approximately five times higher than the silicon (Si) IGBT. Therefore, by paralleling Si IGBT and SiC MOSFET together, a trade-off between cost and loss is achieved. In this paper, a four control freedoms active gate driver (AGD) including turn-on delay, turn-off delay, and two independent gate voltages, is proposed to optimize the performance of the paralleled device. By adjusting these four control freedoms, optimal operation for paralleled device can be obtained. Moreover, the proposed AGD can dynamically adjust the current ratio between two paralleled devices, which can help achieve thermal balance between two devices and improve system reliability. Double pulse test (DPT) experimental results are presented and analyzed to validate the effectiveness of the proposed AGD for paralleled Si IGBT and SiC MOSFET application.
  3. Wide band gap (WBG) devices feature high switching frequency operation and low switching loss. They have been widely adopted in tremendous applications. Nevertheless, the manufacture cost for SiC MOSFET greater than that of the Si IGBT. To achieve a trade off between cost and efficiency, the hybrid switch, which includes the paralleling operation of Si IGBT and SiC MOSFET, is proposed. In this article, an active gate driver is used for the hybrid switch to optimize both the switching and thermal performances. The turn-on and turn-off delays between two individual switches are controlled to minimize the switching loss of traditional Si IGBT. In this way, a higher switching frequency operation can be achieved for the hybrid switch to improve the converter power density. On the other hand, the gate source voltages are adjusted to achieve an optimized thermal performance between two individual switches, which can improve the reliability of the hybrid switch. The proposed active gate driver for hybrid switch is validated with a 2 kW Boost converter.