用于级联型多电平变换器的新型脉宽调制方法

A Novel Pulse Width Modulation Scheme for Cascaded Multilevel Inverter

提出一种用于级联型多电平变换器的新型脉宽调制(pulse width modulation,PWM)方法,即将单个三角载波信号与多个梯形波调制信号进行规则对称采样。推导了梯形波边坡角与输出基波幅值和谐波含量的关系。与其他常用的PWM方法相比,该方法调制下的输出基波幅值更高,在选取适当的边坡角后,输出波形的谐波特性非常好。以5电平和13电平级联型多电平变换器为控制对象,对所提出的PWM方法进行了仿真验证,证明其在输出电压幅值和谐波特性方面具有优良的性能。

A novel pulse width modulation （PWM） scheme for cascaded multilevel inverter is proposed, i.e., the single triangle carrier signal and multi trapezoidal modulation signals are symmetrically sampled by rule. The relation of trapezoidal wave slope angle to amplitude of output fundamental component and harmonic content is deduced. The amplitude of output fundamental component by the proposed scheme is higher than that by other common used PWM methods; and the harmonic characteristic of output wave is satisfied while appropriate slope angle is chosen. Taking 5-level and 13-level cascaded multilevel inverters as controlled objects, the proposed PWM scheme is validated by simulation and it is proved that the proposed scheme possesses good performances in output voltage amplitude and harmonic characteristic.