【摘要】 电力电子变换多采用PWM方法实现功率传送,其载波通常都为等腰三角载波。但要实现软开关PWM调制,特别是对于三相电力变换器,如果用等腰三角波作为载波就无法实现软开关PWM,因为此时变换器往往需要三相开关器件同步开通或关断,取而代之的是采用锯齿波作为载波。然而载波方式改变之后,PWM的频谱有何变化,产生的影响将会如何,本文就此作了深入分析。研究结果指出等腰三角载波PWM与锯齿载波PWM的频谱有很大不同,后者的边频带更宽,谐波更丰富,必须采取有效措施才能将其滤除。更多还原

【Abstract】 Power electronic conversions are mostly using the PWM method to transfer electrical power,and the carrier wave is usually an isosceles triangle type. With the use of isosceles triangle wave as the carrier wave,soft switching PWM mode is hard to be applied,especially for three-phase power converter,because the three-phase inverter switching devices often need to synchronize the on or off states,and an alternative method is the use of a sawtooth wave as the carrier wave. However,after replacing the isosceles triangle carrier wave with sawtooth carrier wave,how the PWM spectrum changes and what the impacts will be? This paper has made an in-depth analysis on these issues. The study concluded that the frequency spectrums of the isosceles triangle and the sawtooth carrier PWM mode are quite different,while the latter has wider sideband and more harmonics,so effective measures must be taken to filter out the harmonics.更多还原