逆变器数字化控制关键技术

研究并解决数字控制的时间量化和数值量化对基于数字信号处理器(DSP)的逆变电源系统性能的不良影响。首先通过优化采样方式,显著减小控制变量的采样延时;采用前馈校正技术对死区效应进行补偿,以降低输出电压的谐波含量。提出频率调节和相位调整相结合的思想,合理设计数字锁相环,提高锁相速度和精度。利用实时的中心值校正信号改进数字控制算法,有效地消除数字运算截断误差累积造成的输出变压器直流偏磁问题。理论分析与实验结果证实了这些控制策略的有效性和合理性。

Digital Control Techniques for Inverters

The digital inverter and the uninterruptible power supply(UPS) represent the development trend of power electronics.However,the time quantization and the numerical quantization in the discrete-time system result in a series of problems in the digital control inverter,such as sampling delay,computational delay,serious dead time effect,and truncation error,etc.This paper studies the corresponding technique for designing a digital single-phase full-bridge online UPS.The flux imbalance of the output transformer is induced by the accumulation of the truncation error,and the digital control algorithm is modified with real time bias correction signals.By selecting the optimal sampling mode,the sampling delay of control variables may be apparently reduced.The feed-forward compensation scheme is proposed to alleviate the dead time effect.By adjusting the frequency and the phase of the inverter output voltage alternately,the digital phase-locked loop(PLL) is implemented in the software.Theoretical analysis and experimental results demonstrate the validity and the feasibility of these control schemes.