Dead Time Compensation for General-purpose Inverters

In this paper a method is proposed for compensating the dead-time in a synchronous rotating reference frame, which is suitable for general-purpose inverters. A simple and practical instantaneous harmonics current detecting method is introduced, which realizes a special filter based on DFT (Discrete Fourier Transform). The amplitude of this filter is 1 in first-harmonic frequency, the amplitude is 0 in other harmonic, and the phase of the filter is 0 in first-harmonic frequency. The filter can follow the fundamental wave in one period. Firstly the FIR filter is designed and its coefficients are worked out in this paper. Then the recursion of filtering algorithm is obtained according to the response character of the filter, and the calculation is thus greatly simplified. One result of the output only needs two multiplications and two additions. The theoretical analysis and simulation have shown that this filter not only takes advantages of digital filters in the accuracy, but also overcomes the bad dynamics performance.