抗电感参数扰动的400Hz逆变器控制策略研究

Research on the Control Strategy for the 400Hz Inverter Against the Fluctuation of the Filter Inductance

400Hz逆变器需具备一定的过载能力,以使挂接于交流母线电子设备故障时继电保护装置动作。然而,过载时滤波电感感值会显著下降,传统有源阻尼控制难以适应LC滤波器谐振频率f_(r)宽范围变化。此外,考虑到400Hz逆变器低次谐波频率较高,其往往落于控制带宽之外且接近于f_(r),低次谐波抑制和系统稳定性较难得以兼顾。为实现滤波电感参数扰动下400Hz逆变系统稳定性提升和宽频率范围低次谐波抑制,文中采用二阶滤波器对有源阻尼内环进行相位超前补偿,提出有源阻尼自适应控制律,其根据预设阻尼比在线调整不同工况下内环反馈比例系数,以实现滤波器谐振峰相同阻尼效果。进一步,提出采用附加相角补偿的特定次谐波谐振控制,并给出相位补偿角度的设计方法,其可实现控制带宽外以及f_(r)附近低次谐波抑制。最后,搭建一台600W单相400Hz逆变器,实验结果表明,所提控制策略可以实现不同工况下滤波电感参数扰动时良好的系统稳定性和低次谐波抑制效果。

The sustainability of overload is usually required in 400Hz inverter application,which enables the trigger of protection if the electrical device connected to the AC bus fails.However,as the filter inductance dramatically decreases in the overload condition,the traditional active damping(AD)fails to effectively dampen the LC-filter resonance under the wide variation of the resonant frequency f_(r).Furthermore,the low-order harmonics are commonly located far away from the control bandwidth,and the frequencies of which are relatively high and approaching f_(r).It is thereby hard to achieve the system stability and the harmonic suppression,simultaneously.Aiming at solving the stability and the harmonic problem under the fluctuation of the filter inductance,this paper employed a second-order filter to realize the phase-lead compensation of the AD loop.The adaptative AD control law,which adjusts the AD gain online according to the elaborated damping ratio,was further proposed to obtain the same damping performance.Moreover,the selective harmonic resonant control with phase compensation,together with its design guideline,was proposed to realize the suppression of low-order harmonics located around f_(r).Finally,a 600W single-phase 400Hz inverter was built.The experimental result under the fluctuation of the filter inductance validates that satisfied stability and harmonic suppression performance have been achieved by the proposed control strategy.