单极性SPWM逆变桥驱动方式研究

在工程实践中,单极性正弦脉宽调制(SPWM)逆变桥路具有多种驱动方式。理论分析、样机实验及软件仿真发现,不同的驱动方式造成了逆变桥臂单端输出波形、双端输出谐波上的差异。单臂斩波驱动时,桥臂中点的响应Ua为正半波不变、负半波抬高一个幅值的变异正弦波形,Ub为调制波频率的方波波形。双臂斩波驱动时,Ua和Ub呈现互差调制波半周期的正弦半波波形。就总的谐波系数(THD)而言,带同臂互补的驱动方式要优于不带同臂互补的驱动方式。通过研究这些差异,对在工程上正确合理地选择桥路的驱动方式无疑是有益的。

Research on driving modes of unipolar SPWM inverter bridge

A unipolar SPWM inverter bridge has manifold driving modes in practical engineering instances.Through the theoretical analysis,simulations and corresponding prototype experiments,differences have been found both between single-end output waveforms and between double-end output harmonics by using certain driving modes.When driven by a single-arm chopped wave,the form of Ua which is the response of the bridge arm midpoint changes to a distorted sine wave of which the positive half remains unchanged while the negative half has an additional offset.In the mean time,the form of Ub is a square wave at the modulation frequency.Alternatively,driven by a double-arm chopped wave,the form of Ua and Ub are two sine waves with only a positive half respectively and a phase shift of π relative to each other.The total harmonic distortion(THD) factor gets better utilizing the scheme with the complementary same-arm than that without it.The investigation of these differences would significantly benefit the optimal selection of driving modes of the unipolar SPWM inverter bridge.