Reliability remains an issue for the Si/SiC hybrid switch adopting the conventional switching strategy of the internal SiC MOSFET that turns on earlier, and off later. Such issue is attributable to the overcurrent stress under the heavy load operating condition, which adversely affects the SiC MOSFET during the gate delay time. To solve this problem without increasing the extra power loss, a novel variable-frequency current-dependent switching strategy combining the variable switching pattern strategy, and the variable pulsewidth modulation (PWM) frequency strategy is proposed. Variable switching pattern strategy can avoid the overcurrent stress of the SiC MOSFET at the heavy load operating condition, and the designed optimal delay time in different switching patterns can achieve the compromise between the excellent reliability, and the power loss of Si/SiC hybrid switch. Variable PWM frequency strategy can effectively reduce the switching loss of the Si/SiC hybrid switch by decreasing the switching frequency around the peak current region. An Si/SiC-hybrid-switch-based single-phase inverter platform is constructed and tested. Test results show that the power loss of the single-phase inverter adopting such switching strategy outperforms the current-dependent switching strategy with 9.4% reduction of power loss, and overcurrent stress of SiC MOSFET is avoided.

中文翻译：

---

在基于 Si/SiC 混合开关的逆变器中改善效率和 SiC MOSFET 过流应力之间折衷的变频电流相关开关策略

对于采用内部 SiC MOSFET 的传统开关策略的 Si/SiC 混合开关而言，可靠性仍然是一个问题，该开关策略先导通，后关断。该问题归因于重负载工作条件下的过流应力，这在栅极延迟时间内对 SiC MOSFET 产生不利影响。为了在不增加额外功率损耗的情况下解决这个问题，提出了一种结合可变开关模式策略和可变脉宽调制（PWM）频率策略的新型变频电流相关开关策略。可变开关模式策略可以避免 SiC MOSFET 在重载工作条件下的过流应力，不同开关模式下设计的最佳延迟时间可以在出色的可靠性、以及 Si/SiC 混合开关的功率损耗。可变PWM频率策略可以通过降低峰值电流区域附近的开关频率来有效降低Si/SiC混合开关的开关损耗。构建并测试了基于 Si/SiC 混合开关的单相逆变器平台。测试结果表明，采用这种开关策略的单相逆变器的功率损耗优于电流相关开关策略，功率损耗降低了 9.4%，并且避免了 SiC MOSFET 的过流应力。