二次型Boost变换器工作模式及输出电压纹波分析

Output Voltage Ripple of Quadratic Boost Convertert

根据二次型Boost变换器输入电感和储能电感的工作模式,划分了二次型Boost变换器的工作模式区域,并分析了不同能量传输模式时输出电压的纹波特性。根据储能电感电流谷值与输出电流的关系,分析了二次型Boost变换器在开关管关断期间的能量传输模式:完全电感供能模式(CISM)和不完全电感供能模式(IISM),得出了CISM与IISM的临界电感值和临界工作条件。当储能电感工作于连续导电模式(CCM)时,二次型Boost变换器既可以工作于CISM,也可以工作于IISM;当储能电感工作于不连续导电模式(DCM)时,二次型Boost变换器只能工作于IISM。对于给定输入电感、负载、电容和开关频率的二次型Boost变换器,当储能电感工作于CCM-CISM模式时,输出电压纹波最小,输出电压纹波仅由开关管导通期间输出电容电压的下降幅度决定,与储能电感无关;而当储能电感工作于DCM-IISM模式时,输出电压纹波最大,输出电压纹波随着储能电感的减小而增大。最后,通过试验装置验证了理论分析的正确性。

According to operating modes of input inductor and storage inductor, operating mode district of quadratic boost converter is discussed and output voltage ripples with different energy transmission modes are analyzed. According to the relation of the valley storage inductor current and the output current, energy transmission modes(ETM) of quadratic boost converter during switch turned off are analyzed. ETM can be divided into the complete inductor supply mode(CISM) and the incomplete inductor supply mode(IISM), the critical inductance and critical condition between CISM and IISM are deduced. It is pointed that the quadratic boost converter may work in CISM or IISM when storage inductor works in continuous conduction mode(CCM), while the quadratic boost converter must work in IISM when storage inductor works in discontinuous conduction mode(DCM). As for quadratic boost converter with certain input inductor, load, capacitor and switching frequency, when storage inductor works in CCM-CISM, output voltage ripple of quadratic boost converter is determined by capacitor voltage during switch turned off, being independent of the current flowing through the inductor. When storage inductor works in DCM-IISM, the converter has the largest output voltage ripple that is also decreasing with storage inductance. A prototype of quadratic boost converter is built and the experimental results verify the analysis results.