Distortion Analysis and Duty Ratio Correction Algorithm for Asymmetric Modulation of Two-Stage Matrix Converter

Abstract

When applying the two-stage matrix converter (TSMC) to the aero variable-speed constant-frequency generation system, the high input frequency varying between 360 and 800 Hz becomes a great challenge to its control. One of the most commonly used modulation methods for TSMC is the dual space vector modulation (DSVM). Simulation and experiments show that despite its advantages such as simplicity and low switching loss, the asymmetric DSVM causes distortion both in the output voltages and input currents of the TSMC. In this paper, the conception of "pulse orthocenter" (PO) is introduced via a BUCK model, and the influence of PO's fluctuation upon the actual output is revealed. Based on the PO theory, the spectra of TSMC's output voltages and input currents are then analyzed, indicating that asymmetric modulation causes 3nω in ± (3m ± 1)ω o harmonics in the output voltages and (3n ± 1)ω in harmonics in the input currents. In order to suppress these harmonics, a duty ratio correction (DRC) algorithm is proposed to improve the waveform quality without increasing switching loss. The DRC formula is provided and the available range of related parameters discussed. The correctness of distortion analysis is testified via simulation, and the validity and feasibility of the DRC algorithm is verified via experiments.Index Terms-Distortion analysis, duty ratio correction (DRC), two-stage matrix converter (TSMC), variable-speed constant frequency (VSCF).

A Spread-Spectrum Modulation Scheme for a 3 × 6 Indirect Matrix Converter Based on a Current Ripple Model

“…Furthermore, vm(t) stands for a periodic signal with an amplitude within [-1, 1]. Typically, sine wave, triangular wave, and exponential wave are selected as modulation signals, which can be expressed as follows: (11) where ks is the symmetry index in the range (0, 1).…”

“…Recent advancements in wide bandgap semiconductors, such as silicon carbide (SiC), have significantly expanded the feasible carrier frequency of power converters [7][8][9]. Various approaches have been proposed to enhance the effectiveness of power converters using pulse-width modulation (PWM), including optimization techniques for vector selection among available vectors [10], reduction in common-mode components in modulation waves [11,12], refinement of switch sequences [13][14][15], and enhancement of carrier properties [16][17][18]. Spread-spectrum modulation (SSM) is an ideal strategy for reducing EMI in multiphase IMC systems.…”

Harmonic Analysis and Attenuation Strategy for a Two-Stage Matrix Converter Fed by Dual-Inverter Based on Pulse Barycenter Method

“…On this basis, PBM can be used to analyze the grid-side current harmonics of TSMCs according to the pulse barycenter movement [34][35][36]. Specifically, the grid-side harmonic-equivalent-value-based PBM contains the information on the pulse location and the relationship between the grid-side current harmonics and the pulse barycenter can be effectively reflected by this value [36][37][38][39]. For a dual-inverter TSMC system, this paper employs PBM to analyze the effect of the current pulse distribution on the grid-side current harmonics in detail, then uses Fourier transformation to obtain the change rule of the pulse pattern with current harmonics; thus, a modulation strategy for dual-inverter TSMCs based on zero-vector duty-cycle correction (DCC) is proposed.…”