基于动态DPWM的三电平损耗及结温研究

Research on Three-level Loss and Junction Temperature Based on Dynamic DPWM

降低功率器件损耗对中点箝位型(NPC)三电平变流器的热可靠性以及使用寿命等方面至关重要。变流器常用的脉宽调制策略可分为连续脉宽调制(SCPWM)与断续脉宽调制(DPWM)策略。SCPWM存在开关损耗大和结温高等缺点;传统DPWM可降低损耗但只能在特定的功率因数角下才可发挥最大效果,为了在宽功率因数范围内都具有最低的损耗,提出一种动态的DPWM策略。通过检测瞬时功率因数角,实时修正参考调制波,使得相电压箝位区域与对应相电流峰值尽可能重合,从而有效降低开关损耗以及抑制器件结温。最后,仿真和实验验证了该方法的有效性。

Reducing the loss of power devices is crucial to the thermal reliability and service life of neutral point clamped(NPC)three-level converters.The commonly used pulse width modulation strategies of converters can be divided into continuous pulse width modulation(SCPWM)and discontinuous pulse width modulation(DPWM)strategies.SCPWM has the disadvantages of large switching loss and high junction temperature.The traditional DPWM can reduce the loss but can only play the maximum effect at a specific power factor angle.In order to obtain the lowest loss in a wide power factor range,a dynamic DPWM strategy is proposed.By detecting the instantaneous power factor angle,the ref-erence modulation wave is corrected in real time,so that the phase voltage clamping area coincides with the corre-sponding phase current peak as much as possible,thereby effectively reducing the switching loss and inhibiting the junction temperature of the device.Finally,the effectiveness of the method is verified by simulation and experiment.