可调式逆变器输出滤波器的原理与实践

提出一种基于可调电感的可调式逆变器输出滤波器。根据电机和逆变器工作状态，通过加在直流励磁绕组上的可控电源对可调电感进行控制。在电机起动时，使电感值较小，以便产生较大的起动力矩；在稳态运行时，根据基波频率、载波频率和负载电流来改变电感值，以便获得较好的滤波效果和电气传动效果。与定常参数滤波器相比，可调式滤波器能较好地满足电气传动系统对滤波器的特殊要求。可调电感的主要特点是，能够进行连续电气调节，易于实现闭环，通过对结构的合理设计可以得到近似线性电感。给出了以数字信号处理器DSP为控制单元的可调式逆变器输出滤波器的基本结构，分析了滤波器和近似线性可调电感的工作原理，以及可调电感的控制策略，并列举了部分试验结果。

Principle and practice of adjustable inverter output filter

In the inverter output filter with an adjustable inductor proposed the adjustable inductor can change its inductance according to different working states of motor and inverter, appropriately by adjusting the voltage applied on the inductor DC excitation coils. When motor starts up, the inductance of an adjustable inductor can be adjusted a small value to generate a large starting torque. When the motor works in its steady state, the inductance of the output filter can be adjusted according to the inverter fundamental frequency, carrier frequency, and load current. A better filtering effect and better electrical driving effect can thus be achieved. In comparison with filters with constant parameters, inverter output filters with adjustable parameters can satisfy special requirements for inverter output filtering of electrical driving systems. The adjustable inductor has the following main features: 1) the electrical adjustment of the inductor can be performed continuously; 2)a closed loop control can be applied to the inductor easily; 3) an approximately linear inductor can be obtained by a reasonable design of the structure of the adjustable inductor. The basic structure of the proposed adjustable inverter output filter with DSP (Digital Signal Processor) as its control unit, its working principles and control strategies are discussed with some experimental results given.