两级式逆变器前级电路两种控制下的损耗分析

Loss Analysis of Front Circuit of Two Stage Inverters Under Two Control Methods

传统控制下两级式逆变器中间母线电压存在较大二次纹波,降低了中间母线电解电容寿命;而利用逆变侧瞬时输出功率前馈控制前级直流变换器的方法可抑制该纹波,但其对电路损耗的影响未知。这里分析比较了这两种控制下两级式逆变器前级电路的损耗。运用器件Datasheet中伏安特性、开通损耗及关断损耗与电流的关系曲线,通过image2data软件提取参数,采用最小二乘法拟合得到伏安表达式和开关电流公式,结合变换器开关电压电流解析式,建立了器件损耗模型并进行预估。最后对比了实验测试损耗与理论预估损耗,证明了采用功率前馈控制时前级电路损耗更大。

Under the traditional control,the intermediate bus voltage of two stage inverter has a relatively large secondary ripple voltage, which will reduce the life of the middle bus electrolytic capacitor. A method is proposed to feed forward the instantaneous output power to the forward direct current converter in order to suppress ripple voltage.The loss of the front circuit of two stage inverter is analyzed and compared under these two control methods.Using the volt ampere characteristics and losses of turning on and turning off with the current of device datasheet, then, through the image2data software to extract parameters, the volt ampere expression and the switching current formula are obtained by least square method,and combined with the analysis of switching current and voltage converter to establish the loss model of each device and predict the power losses.The experimental loss and theoretical prediction loss are compared, and prove there have a higher power loss of the front circuit converter with power forward controller.